Weight loss blog

RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM AS DETERMINANT OF BLOOD PRESSURE

admin — Fri, 29 Jul 2011 17:29:12 +0000

One of the most important determinants of blood pressure is the renin-angiotensin-aldosterone system (RAAS), which is named for three of the compounds involved in this complex series of biochemical reactions. Although the RAAS plays a role in daily fluctuations in blood pressure, it is also a key player in longer-term regulation, and in hypertension.Here’s how the RAAS system works. Angiotensinogen is a protein produced in the liver on a continuous basis. Renin is an enzyme that is released by the kidneys under conditions of stress, exercise, or certain changes in diet. When angiotensinogen and renin join in the bloodstream, they form angiotensin I. As the blood carrying angiotensin I travels through the lungs, it reacts with angiotensin-converting enzyme (ACE) to form angiotensin II. Angiotensin II has two actions. First, it causes the muscular walls of the arteries, and particularly the arterioles, to contract. This decreases their diameter and drives up blood pressure. Second, angiotensin II prompts the adrenal glands (located on top of the kidneys) to release aldosterone. Aldosterone is a hormone that signals the kidneys to keep more sodium and water in the bloodstream and stop excreting them through the urine. This results in increased blood volume and higher blood pressure. The RAAS is crucial for your health and well-being. Remember, the diameter of your blood vessels and your blood pressure are in constant flux as the needs of your body change from moment to moment, and this is one of the mechanisms that oversees these normal variations. However, when the RAAS pathway becomes overactive, blood pressure is consistently elevated. This is estimated to be the primary cause of high blood pressure in about a third of all people with hypertension.*16/313/5*

ADOLESCENT ALCOHOL PROBLEMS

admin — Sun, 17 Jul 2011 17:22:57 +0000

Not unexpectedly accompanying adolescent drinking there are also alcohol problems. To cite just a few of the statistics from the ever-growing pile:In the 13 to 17 year age group, it is estimated there are three million problem drinkers, and over three hundred thousand teenage alcoholicsDrinking is a significant problem for between 10% and 20% of adolescents.11% of adolescents and 28% of high school seniors drink 5 or more drinks at least once a week.97% of drug-abusing adolescents also use alcohol.Over the last 20 years, life expectancy has increased for all age groups except ages 15 to 24. The three leading causes of death in this age group are accidents, suicide, and homicide, all closely linked to alcohol and drug use.The leading cause of death between ages 16 and 24 is driving while impaired.Drivers age 16 to 24 years constitute 17% of the population; they are involved in 48% of fatal accidents.Daily, 14 adolescents, age 15 to 19 years, die and 360 are injured in alcohol-related traffic accidents.One way to understand the high incidence of problems with substance abuse in adolescence is in terms of the adolescent developmental tasks cited earlier. The first task mentioned was the acceptance of one’s biological role. For women the onset of their menstrual cycle provides clear biological evidence of their transition to adult functioning. For males the transition may be more difficult. But for both in contemporary America the question of how to know you are an adult is often difficult. For many adolescents drinking serves as a rite of passage. Not only is it an adult activity, it is also one way to be “one of the crowd.” Drinking can provide entry to a group of peers. Even as an adult one is often encouraged to drink and given messages that not to drink is to be antisocial. For adolescents with their intolerance of differences and their increased vulnerability to following along with peers’ behavior, not drinking at a party where others are drinking may be even harder for teenagers than for adults.Also, an important part of accepting one’s biological role is learning to be intimate with those of the opposite sex. This can be threatening to many adolescents. Alcohol can be used to avoid intimacy, or to seek intimacy without responsibility. “I wasn’t myself last night, I was really plastered” can be said by either boys or girls to disavow what happened the night before. The same is true in the sexual realm, as a means of experimenting without taking responsibility. In our society being drunk has long provided a “way out.” Often people are not held accountable for actions that occur when they are drunk. Thus, getting drunk can often help adolescents express these increasingly powerful impulses, without really taking direct responsibility for their behavior.Part of the task of attaining independence is learning to set limits for themselves, to develop self-control. For some adolescents this is more difficult than for others. It is particularly difficult about issues like drinking where societal messages and alcohol advertising suggest that “having more than one” is appropriate adult behavior. In the process of learning self-control, adolescents react negatively to adults setting limits. If parents are too aggressive in forbidding alcohol use, it may backfire. Further confusing matters is that adolescent development is characterized as well by changes in patterns of thinking. Prior to age 12 to 13, adolescents generally adhere to concrete rules for behavior. From ages 13 to 15 years, adolescents are likely to question the justification of set rules. They feel that conventions are arbitrary, hence rules supporting them are invalid. By the age of 16 most of them begin to realize that some rules are necessary.Another important task mentioned earlier is the development of a sense of identity. Part of the task of gaining an independent identity involves experimentation in all realms. Adolescents may use alcohol for help in experimenting with different roles and identities. Closely connected to this experimentation is risk taking. Some of this risk taking involves physical danger. Adolescents are said to have a “sense of invulnerability.” Unfortunately, alcohol can further increase this sense of invulnerability and lead to risk taking with dangerous consequences. It is not surprising, as mentioned earlier, that accidents are the leading cause of death in adolescents, and that alcohol use and abuse is heavily implicated in fatal accidents from all causes.As these adolescent developmental tasks are accomplished, the number of problem drinkers decreases. But for a significant proportion of problem drinkers, these problems will persist and grow worse. For far too many, the problem drinking may end in death or disability, long before either outcome.*148\331\2*

IDEAL MARRIAGE: FUNDAMENTAL EQUALITY – THE SEGREGATION AND DIFFERENTIATION OF THE SEXES

admin — Sun, 03 Jul 2011 17:16:30 +0000

Instead of admitting the fact that the segregation and differentiation of the sexes is the cause of most of our marital unhappiness, we console ourselves with idle proverbs such as “True love never runs smoothly,” or “Man cannot live with and cannot live without woman.” Indeed, the antipathies between the sexes are so much taken for granted that most writers on sex regard them as instinctive. It is not only more correct but also more fruitful to regard these differences as merely products of early savage segregation of the sexes due to superstition and later segregation due to the patriarchal property rights which man possessed over woman. An examination of most of the bad traits which are found in women and not men, and vice versa, will lead us back to the patriarchal family. Woman’s cowardice, poor sportsmanship, lack of nobility, invidious love of display, gossiping, infantilism, conservatism, economic irresponsibility, and sexual prudery can all be traced to the harem. And man’s excessive masterfulness, conceit, and monopoly of the power and interesting work of the world are likewise a survival of patriarchal society.Fortunately the old order is breaking down, but this is taking place more slowly than it should, partly because of the resistance of the very men and women who have been injured the most by the old regime, and partly because of economic conditions and general inertia. Women have made great strides in the last quarter of a century in acquiring some of the rights of men, though their readiness to take on men’s duties has not been so conspicuous. The possession by women of the liberties of men while at the same time being left unrestrained because of the immunities which their sex i enjoys is rather trying but must be regarded as merely transitional. Although we have a long way yet to go, men and women are in a better position to be genuine companions today than ever before.*101\275\8*

LEAD A HEART-HEALTHY LIFE-STYLE: DO YOU USE THESE EXCUSES NOT TO EXERCISE?

admin — Wed, 29 Jun 2011 10:40:36 +0000

” I have no time”. You can certainly spare 20 minutes, thrice a week.”I’m too old”. That’s not true. You’re never too old to exercise.”I’m on my feet all day. I don’t need any more exercise”. Unfortunately, just being ‘on your feet’ is not enough exercise for anyone. You need to walk or exercise for some time continuously for it to be effective.”I’m exercising enough”. This statement is unfortunately not true for most people. What you think is enough may not be so. Also you may not be regular enough.”/ find exercising too boring”. This need not be so. Find an exercise you like. Vary your schedule. It is not important what sort of exercise you do, as long as you do something.”I’m not the sporting type”. A common misconception. Exercise does not mean being an athlete, or good at games. Any form of exercise is acceptable and as good as any other.”I find exercising too strenous”. You are probably doing it wrong. You don’t have to huff and puff and drip with sweat for exercise to be good for you. A gentle, but regular exercise schedule is almost as effective as a vigorous one.”I used to exercise, but now I can’t keep it up”. Why not? Maybe you did not like the form of exercise you were doing. Perhaps you just need a little nudge to get you started again. Let reading this give you that inspiration.”It’s too expensive”. That depends on what form of exercise you choose. While golf or an expensive health club can be costly, walking costs nothing.”It could be dangerous”. This is not true for most people. However, if patients having pre-existing heart disease start exercising suddenly at high work-loads, then it can certainly be dangerous. If you have high blood pressure, a family history of heart disease, or chest pain when exercising, it would be prudent to consult a cardiologist before commencing an exercise schedule.*96\254\8*

THE UNDERUTILISATION OF MORPHINE : OPIOPHOBIA-PATIENT OPIOPHOBIA

admin — Fri, 17 Jun 2011 10:33:48 +0000

Morphine is the drug of choice for the management of severe pain in advanced cancer but opioids are frequently denied to patients who could benefit from them. Patient Opiophobia-Patients and their families may also have fears or express concerns about morphine therapy. Prescription of morphine is interpreted by some patients as a message that death is imminent. This requires explanation that morphine can be used for months or years and is entirely compatible with a normal lifestyle. Other patients resist taking morphine for fear there may be nothing in reserve should their pain worsen. This requires reassurance that the therapeutic range of morphine is sufficient to allow escalation of the dose if necessary. A history of being ‘allergic to morphine’ usually relates to nausea or vomiting which occurred when parenteral morphine was given to an opioid naive patient for acute pain. Immunological allergy to morphine is rare and given explanation, reassurance and the cover of antiemetics, most patients can be started on morphine without ill effect. Patients may express concern about addiction. They require explanation about tolerance and physical dependence and reassurance that psychological dependence is not a clinical concern. If patients claim that morphine did not help their pain it may be that the dose was too low, given too infrequently or they were not given instructions about what to do for breakthrough pain. The importance of other aspects of patients’ suffering — physical, psychological, social, cultural and spiritual — to their perception of pain cannot be underestimated. Patients given morphine in an apparently appropriate dose but who report no benefit, and especially those who report no benefit after escalation of the dose, nearly always have psychosocial problems compounding their pain.• Given adequate explanation, good prescribing and individual titration of dosage, most patients will achieve good pain relief without unacceptable side effects.*53\55\2*

NATURAL HISTORY OF TYPE 1 DIABETES: EFFECT OF INTENSIVE MANAGEMENT – NEPHROPATHY

admin — Thu, 09 Jun 2011 10:25:43 +0000

In the DCCT, renal involvement (nephropathy) was assessed by ti urine collections at baseline and yearly, with calculations of 24-hour urinary albumin excretion and creatinine clearances. Intensive therapy reduced the mean adjusted risk of microalbuminuria, defined as > 4C albumin/24 hours, by 34% in the primary prevention group (p = 0 and by 43% in the secondary intervention cohort (p = 0.001) . risk of albuminuria, defined as a 300 mg/24 hours, was reduced by ? in the secondary prevention group (p = 0.01). More advanced nephropathy, such as renal failure requiring dialysis, developed in very few patients. The effect of intensive treatment was maintained in various s groups defined according to age, gender, duration of type 1 diabetes, mean blood pressure, baseline HbA1c, dietary protein intake, or history of cigarette smoking.Approximately 27% of primary prevention patients assigned to standard therapy had microalbuminuria after 8 years of follow-up compared with only 15% in those in the intensive therapy group. Among second; prevention patients, approximately 40% assigned to conventional therapy vs. only 25% of these on intensive therapy had microalbuminuria after years in the trial. Thus, although intensive management was effective delaying progression to microalbuminuria in both primary and secondary prevention cohorts, its appearance was not completely prevented. Anal sis during the fourth year after completion of the DCCT in the EDIC Tri showed that the proportion of patients with an increase in urinary albumin excretion continued to be significantly lower in the intensive therapygroup. Microalbuminuria has emerged as an important risk marker f( renal failure and for cardiovascular events. *28\357\8*

INFECTIONS: THROWING THE BOOK

admin — Thu, 26 May 2011 10:17:29 +0000

The legal profession will not be the same. Currently, for instance, actions are taken against polluters when clusters of disease are linked to the release of disease-causing compounds. Consider the case of Keil Chemical in Lake County, Indiana. In 1991 records indicated that Keil Chemical released about nine hundred tons of a potentially carcinogenic solvent called ethylene dichloride; its city permit allowed the company to release 0.02 ton. From 1987 to 1998, the cancer incidence in Lake County was about 20 percent above the incidence that would have been expected based on national averages.The conventional perspective is that cancer is generally caused by genetic alterations by physical agents. According to this perspective, the evidence looks incriminating, even though experts warn against jumping to conclusions. In the Lake County case, an epidemiologist from the National Cancer Institute warned that “we don’t understand what causes ninety to ninety-five percent of childhood cancer.” But these warnings seem like overly cautious science-speak to people who want justice rather than statistics. When scientific proof of causation is not available, the affected people and the legal professionals base their actions on whatever evidence is available. Disease does not wait for science. If there is an excess of cancer deaths and an excess of a potentially carcinogenic chemical, cause and effect will be inferred unless some viable alternative is presented. If a person hears a shot from a room, walks into the room and sees one person dead on the floor from a bullet wound and another person holding a smoking gun, that too is just an association. Unless the person holding the gun has a good alternative explanation handy, the legal profession will tend to assume that the association reflects causation.In the absence of knowledge about the spectrum of disease causation, experts may unwittingly fan the flames. In the Lake County case, physicians apparently told the parents of two daughters afflicted by rare and different cancers that having both cancers in the same family would be extremely unlikely under normal conditions. Presumably that conclusion was derived by multiplying two small probabilities together to obtain the extremely unlikely joint occurrence within one family. The validity of that conclusion depends on the cancers and what causes them. If the rare cancers were both caused by a common pathogen, then having two in a single family might not be so unusual. Many infectious diseases co-occur frequently within families because family members are more likely to be exposed to the same infectious agents than are two people drawn at random from the population. Medical science has only recently begun to understand infectious causation in the common, well-studied cancers, such as liver, stomach, and cervical cancer. Almost nothing is known about the causes of most rare cancers, certainly not enough to conclude that you can multiply the two small probabilities of having either cancer in a family to obtain the probability of having both in the same family.The new understanding of infectious causation dramatically changes this kind of analysis by drawing attention to feasible alternative explanations for the clustering of cancers and other chronic diseases. Cases of infectious diseases typically cluster either because the potential for transmission varies from place to place or because infectious outbreaks spread from somewhere. Clusters of cancer would therefore be expected for cancers that are caused by infection. If such a cluster happened to occur near the release of a carcinogenic chemical, then the chemical pollutant might be falsely accepted as the cause of the cancer. But infectious causation makes the morass even more ambiguous. If no clustering is associated with the release, the oncogenic chemical could be falsely exonerated. To see this point, imagine that the release did cause some of the cancer. Imagine further that the cancer rates in the vicinity would otherwise have been relatively low because an infectious cause of cancer happened to be rare in the area. An observer might not see any increased incidence of cancer in the area because the lower background rate might mask the effect of the chemical carcinogen. Joint causation further complicates the situation. Noninfectious causes of cancer may exacerbate infectious causes.Before we throw the book at alleged perpetrators, we have to look broadly to see the right targets. Historically, the EPA and CDC have been set up to focus on different targets: the EPA has focused on noninfectious causes of disease, and the CDC on infectious causes. This distinction may become increasingly anachronistic and unproductive as we find more disease that is attributable to both causes.*47\225\2*

IMMUNE POWER DIET: MINERALS AND YOUR MEMORY

admin — Tue, 17 May 2011 10:01:02 +0000

Memory problems are a well known symptom of heavy metal poisoning. Many of us are exposed to unsafe levels of these metals, particularly mercury, which is a food contaminant. There may be many more people suffering the toxic effects of heavy metal poisoning than we now recognize. Do you have any of these memory problems?Do you regularly have trouble recalling the names of people you knew last year?Do you misplace things more often than you used to?Do you ever forget the name of a familiar household object?Before reading this, had you already noticed any problem with your memory?Has a work associate, friend or family member pointed out memory problems to you in the last month?Have you recently felt that you are not quite as alert as you used to be?Have you had in the last month two embarrassing incidents where you forgot something important?If you answered “yes” to these questions, and “yes” to several of the risk factors listed earlier, it is possible that you might be suffering from a toxic accumulation of heavy metals.*55\242\2*

UNINTENDED TEENAGE PREGNANCY

admin — Mon, 09 May 2011 09:54:36 +0000

More than one million pregnancies occur each year among American teenage females, which is equivalent to one adolescent pregnancy beginning every 35 seconds. Since the majority of these pregnancies are unplanned and unwanted, it is no surprise that they frequently create considerable psychological anguish, serious economic consequences, and even health risks that are too often ignored or misunderstood.A few background statistics can highlight the scope of this epidemic.30,000 pregnancies occur annually among girls under fifteen years of age.400,000 American teenagers have abortions each year, accounting for more than one-third of all abortions performed in this country.Six out of ten teenage females who have a child before age seventeen will be pregnant again before age nineteen.With one out of twenty adolescent females having a baby each year, America’s teenage birth rate is the highest in the western hemisphere, double the rate of Sweden, and is an astonishing seventeen times higher than Japan’s.Four out of ten girls now fourteen years old will get pregnant in their teens.These statistics show how widespread the problem of unintended teenage pregnancy is, but to understand why it is a problem, we need to examine some additional aspects of the consequences of teenage pregnancy. To begin with, there are increased health risks associated with teenage pregnancy, particularly among younger teens (those in the thirteen- to sixteen-year age group). For example, babies of teenage mothers have an increased chance of being underweight and are nearly twice as likely to die in infancy as those born to women in their twenties. In addition, teenagers tend to have more medically complicated pregnancies — including miscarriages, toxemia, and hemorrhage — as well as a higher risk of maternal death than women in their twenties.Possibly even more alarming than these medical risks are the socioeconomic consequences of unintended teenage pregnancy. Even though it is now illegal to expel students who are pregnant or who are mothers from public schools, most teenage mothers who keep their babies drop out of school and don’t return. Largely as a result of this abrupt withdrawal from formal education, women in this group are far less likely than their peers to enter the job market or to gain regular employment. It is no surprise, then, that these teenage mothers are overrepresented in poverty statistics and are apt to become largely dependent on government services and support.Unmarried teenage girls who find themselves pregnant are confronted by a series of psychologically complicated choices, as well. They often get little or no support — either emotionally or financially — from the child’s father. They must decide whether to have, an abortion (which sometimes produces intense feelings of guilt and anguish) or have the baby. If they have the baby, they then must decide to keep it or put it up for adoption; today, fewer than 5 percent of unwed teenage mothers choose adoption as a course of action. In other cases, their partners may pressure them to do something they don’t want to, thus creating additional pressures and uncertainties. Here’s how one seventeen-year-old described her dilemma:When I found out I was pregnant, my boyfriend insisted that we get married and have the baby. I had no interest in marrying him or in being saddled with an infant at age eighteen, so I refused. But his parents hired a lawyer to try to stop me from having an abortion, and the whole thing wound up being a nightmare for me and my parents. Fortunately, I got the abortion and dumped my so-called boyfriend, so I’ll be going to college next year instead of playing mommy.Some teenagers, unlike the one quoted above, find themselves rushed into unanticipated marriage as a result of a pregnancy. Unfortunately, these marriages are much likelier than most to end in divorce or desertion, and there is a suicide risk among these young women that is considerably higher than in the general population.There is relatively little research describing the consequences of unintended teenage fatherhood. This may be partly because it is difficult to identify these individuals for study and partly because they are not socially or economically linked to the pregnancy outcome in the same ways mothers are. However, the available evidence (summarized concisely in reports from the Alan Guttmacher Institute and the Ford Foundation) shows that males who become fathers while in their teens tend to have lower income and less educational attainment than peers who postpone fatherhood until their twenties. Nevertheless, the impact of teenage pregnancy is considerably less on males than on females.Clearly, many adolescent males continue to regard the ultimate responsibility for contraception as the female’s, generally feeling that an unintended pregnancy could have been prevented and thus is the “fault” of the female — in other words, that it is “not their worry.” Others feel a joint responsibility that extends only to offering to share (or perhaps pay entirely) for the cost of an abortion; to them, this gesture is an honest acknowledgment of their involvement and willingness to help, but it is involvement of the most limited sort. In fact, as the noted sex educator Sol Gordon points out, “almost 90 percent of all teenage boys who make a teenage girl pregnant abandon her.”While there are no easy solutions to the problem of unintended teenage pregnancy, it appears that misinformation or complete lack of information is a key factor. At present, only one-third of American junior and senior high schools offer sex education courses, and many of those offered are remarkably incomplete. Since many of the sex education courses are given only to older teenagers, their preventive function is lessened considerably. Those people who believe that sex education should be taught in the home — while voicing a fine idea — overlook the reality of the situation today. Research indicates that only about 10 percent of parents discuss sexuality with their teens beyond simply saying “don’t.” On the other hand, a 1982 study by Zelnik and Kim demonstrates that among unmarried sexually active teenage women, those who have had sex education courses have fewer pregnancies than those who haven’t.Almost all authorities agree that greater responsibility for contraceptive use by the adolescent male is a major element in the effort to reduce the rate of unintended teenage pregnancy. First, educating males about contraceptive options at an early age seems warranted since studies suggest that this information leads to better contraceptive use. Although teenage males are generally unwilling to admit to ignorance or misinformation about sex, it is not unusual to find fifteen- or sixteen-year-old boys who believe that a diaphragm should be removed right after intercourse, or who don’t know the fertile days in a female’s menstrual cycle. Such education need not be restricted to schools — it can be done at home, in church-affiliated programs, or as part of community projects. Education must be practical, too, explaining how and where to purchase contraceptives, why it’s important to discuss birth control with a partner, and why consistent contraceptive use is necessary.Another important step is to provide males (as well as females) with a better view of how birth control practices relate to their own lives. For instance, teens must recognize how rigid sex roles or the risk of parental disapproval can influence their contraceptive behavior. In addition, teens need to be aware that the risk of contracting a sexually transmitted disease is materially reduced by use of certain contraceptive methods. This is important not only because it encourages the teenage male to use contraception, but because the male’s expression of interest and concern about contraception encourages his partner to find and use an appropriate method as well. In addition, teenagers need incentives to engage in responsible birth control practices.Some authorities suggest public campaigns geared at urging teens to say “no” to having intercourse. This approach might be effective with some adolescents, but would probably not be realistically effective with the majority of teenagers, given today’s , patterns of sexual behavior in our culture: it is hard to put a genie back in a bottle. Also, such an approach runs the risk of being repressive — it is, after all, an attempt to frighten teens into abstinence — and this may produce a backlash. Indeed, anti-drug and anti-cigarette campaigns have often been discredited by teens on this basis. In any case, since it is unlikely that the majority of sexually experienced teenagers will become celibate en masse, it is necessary to provide teens with positive role models toward appropriate contraceptive use and a more effective view of the ways in which responsibility in sexual behavior is important to their welfare.*95\342\2*

BIOBOMBS: BIOLOGICAL WARFARE

admin — Mon, 25 Apr 2011 09:45:55 +0000

What Jeffery Amherst actually did or did not do is unclear. Written records suggest that this story may have been based on some advice Amherst gave in his capacity as Britain’s commander in chief in North America. In 1763, Fort Pitt, an outpost at the western edge of colonial Pennsylvania, was in danger of being seized by the local Indians, who had had quite enough of Yankee hospitality. They had already taken over all the nearby outposts and killed the inhabitants. If Fort Pitt were to fall, the Pennsylvania colony would contract to its eastern core around Philadelphia. Amherst sent a letter from his base in New York to the ranking officer for western Pennsylvania, Colonel Henry Bouquet, who was based in Philadelphia: “Could it not be Contrived to Send the Small Pox among those Disaffected Tribes of Indians? We must, on this occasion, Use Every Strategem in our power to Reduce them.”Bouquet wrote back, “I will try to inoculate the ____________with SomeBlankets that may fall in their Hands, and take care not to get the disease myself.” Bouquet apparently deleted the name of the Indian group to protect himself or the plan.The response from Amherst makes his opinion clear: “You will Do well to try to Inoculate the Indians, by means of Blankets, as well as to Try Every other Methode, that can Serve to Extirpate this execrable Race.”The journal of the captain at Fort Pitt, however, indicates that he had already given smallpox-laden blankets and a handkerchief to the Indians before receiving such orders from Bouquet. The use of smallpox-contaminated fabrics apparently was generally recognized as an option that could be used if other methods failed, and sometimes even if they didn’t. Smallpox broke out severely among Indians the following spring, though the outbreak may have resulted from sporadic cases that had been occurring among the Indians even as the captain at Fort Pitt was preparing his blankets. The colonists, having already acquired immunity, were little affected. Fort Pitt was held and eventually grew into a hub of western Pennsylvania: the town of Pittsburgh.Not quite two hundred years later, after Nazi panzer divisions reached Stalingrad, a strange “German disease” hampered their advance. A surprisingly high incidence of tularemia soon occurred among Soviet civilians and troops in the area. Though the bacterium that causes tularemia is similar to the agent of the black plague, tularemia generally stays put in its normal transmission cycle, which involves small mammals and ticks. Human cases occur sporadically if, for example, a person is bitten by an infected tick or is butchering an infected rabbit. Three decades after the Stalingrad outbreak, a promising young medical student named Ken Alibek was asked by his Soviet professor to analyze the unusual cluster of tularemia cases. After intensive study Alibek reported his conclusion to the professor: the epidemic must have been caused intentionally. The professor then told Alibek to “forget you ever said what you just did. I will forget it too … never mention to anyone else what you just told me. Believe me, you’ll be doing yourself a favor.”In one sense tularemia was an effective weapon for the Soviet goal. It helped stop the Nazi advance. But as was the case in western Pennsylvania nearly two centuries before, the weapon was crude and unpredictable—it could fizzle or backfire. The sequence of events in Stalingrad probably began with spraying of the Germans when the winds were favorable; the collateral damage to Soviet civilians and troops may have resulted from a change in wind direction or from infection of rodents, which then dispersed freely across the battered landscape.Learning their lesson from the experience, Soviet strategists shifted their tactics to use of biological agents against targets that were further behind enemy lines. But even this alteration would not have solved the problem. If biological weapons are successful, the enemy territory may soon be the property of those who contaminated it, and a heavily contaminated prize is not very attractive; moreover, the mobility of people in war makes the site of release a poor predictor of the spread of damage.Our emerging knowledge of disease evolution, considered in the context of the biological weapons used in past wars, raises a weighty question. As we learn more of how evolution creates virulence—indeed, as we learn how to manipulate that process—are we likely to begin constructing a new military technology based on our new knowledge? There are dangers, but there are also reasons to think that the dangers can be lessened.With just a little bit of thinking, military strategists and militaristic dictators who are tempted by the low cost and destructive capacity of biological agents recognize the general lesson: biological organisms may be scary, cheap, and accessible, but they are poor military weapons. Even when biological weapons could provide a tactical victory, their use opens the door to long-range difficulties. If the stronger side initiates the use of biological weapons for a tactical advantage, it opens the door to their use by the weaker side. Though biological weapons offer little chance of victory for the weaker side, even a weak opponent can cause a great deal of retaliatory damage to troops or civilians. So the more powerful side has an incentive not to open that door. A similar incentive applies to the weaker side, which risks retaliation from the stronger side’s conventional weapons as well as any biological weapons the stronger side may have. Escalation to an air war provides a contrast: the side that has air superiority and initiates the use of air attacks may suffer little from the other side—as long as the air superiority holds up.Clearly there has been a hesitancy to deploy biological weapons. They have been used when a weak opponent has little else to lose from retaliation, as was the case with the Soviets in Stalingrad, or when a weaker opponent does not have biological weapons for retaliation, as was the case in colonial Pennsylvania. In Stalingrad, the Soviets were not risking a great deal of damage from reprisals, because their situation was dire and because the Nazis did not have a strong biological weapons program and were already using everything in their full arsenal. In western Pennsylvania the situation at Fort Pitt was dire, though the situations in Philadelphia and New York were not; but opening the door was not so risky, because the Indians had neither biological weapons nor overwhelming military power kept in reserve for retaliation.This logic provides an important though somewhat discomforting lesson: a power that wants to avoid being the target of biological weapons during wartime had better have some means for reprisal. It could do that by having biological weapons of its own, or, as the United States has done, by having such an overwhelming reserve capacity for destruction that the use of biological weapons by a less powerful adversary is deterred.Still, even in such cases biological weapons are weapons of last resort. When a city is being overrun or a fort is under siege, biological weapons may turn the tide, but they may do so at a great price and with little predictability. These problems are inherent among living microorganisms because the reproduction, spread, and modification of living organisms, and the feedback loops among these influences, are too complex to predict and control once the organisms are unleashed.The modification of disease organisms for use as weapons during wartime has been a frightening threat ever since the use of chemical weapons during World War I made observers ask whether the science of weapons development should be limited. A deeper analysis of the drawbacks of biological weapons assuages these concerns to some extent by revealing that biological agents tend to generate poor weapons for warfare. But what about biological terrorism?*51\225\2*