Norman Bauman, Author at New 女生小视频 Science news and science articles from New 女生小视频 Fri, 10 May 1996 23:00:00 +0000 en-US hourly 1 https://wordpress.org/?v=7.0.3 242057827 Panic over falling sperm counts may be premature /article/1840501-panic-over-falling-sperm-counts-may-be-premature/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 10 May 1996 23:00:00 +0000 http://mg15020291.000 New York

AMERICAN men are not suffering from declining sperm counts. In fact their
sperm seem to be doing rather well, researchers announced at a meeting of the
American Urological Association in Florida last week. What鈥檚 more, sperm counts
are closely correlated with birth rates, says Harry Fisch, director of the Male
Reproductive Center at Columbia Presbyterian Medical Center, New York.

Fisch鈥檚 findings contradict those of European researchers, who have been
amassing evidence for a worldwide decline in sperm counts. In 1992, Niels
Skakkebaek of the University of Copenhagen sounded the first alarm. After
analysing data from studies going back to the 1930s, he concluded that there had
been a dramatic decline in sperm counts. Last year, a French study confirmed
that counts were falling in Paris.

Skakkebaek and others argue that the decline鈥攖ogether with other male
reproductive problems such as an increase in testicular cancer and malformations
of the penis鈥攎ight be linked to rising levels of oestrogen-like compounds
in the environment. People are exposed to oestrogen mimics in foods such as milk
and soya beans, and through polluting chemicals such as PCBs, dioxins and
detergents. Other researchers found male fish in polluted waters behaving
physiologically like females, and there has been a shift in the sex ratios of
alligators in polluted waters in Florida.

Fisch, however, believes there has been no decline in sperm counts. He says
that the European studies were flawed because they failed to take into account
geographical variations and fluctuations from year to year, or suffered from
sampling bias.

Fisch reviewed sperm counts of 1283 men who banked sperm between 1970 and
1994 before they had a vasectomy, in Los Angeles, Roseville in Minnesota, and
New York City. He found a statistically significant increase in New York and
Minnesota and a slight but not statistically significant increase in California.
The average sperm count rose from 77 million per millilitre in 1970 to 89
million/ml in 1994, he reports in the latest issue of Fertility and
Sterility. In the same issue, Alvin Paulsen of the University of
Washington in Seattle, reports that he found no fall-off in sperm counts among
510 students who donated sperm for research between 1972 and 1993.

Most surprising, says Fisch, was the great variation in counts both
geographically and from year to year. He believes this explains why earlier
studies wrongly concluded that there has been a severe decline. Within the US,
counts varied hugely according to where men live. Californian men had the lowest
counts (73 million/ml). In Minnesota they were higher (101 million/ml), but New
Yorkers held the record (131 million/ml).

But Fisch also points out that variation from one year to the next could be
greater than the variation over 25 years. For example, the variation from 1976
to 1977 is almost as large as the entire variation for all years. 鈥淪o if you
selected two years out of this data, you could get completely different
conclusions about the long-term trend,鈥 he says. 鈥淚f we looked at our data from
1984 to 1994, we would also have concluded a decline.鈥 Fisch also found a strong
correlation between the average sperm count in a particular year and the birth
rate in Minnesota, suggesting that sperm counts may be an index of fertility
(see
Graph).FIG-20291001.jpg

How sperm counts are correlated to birth rates

These findings clearly contradict those of the Danish and French studies,
Fisch says. The study that first put men on alert was Skakkebaek鈥檚 huge
multi-study analysis, in which he looked at the data from 61 sperm count studies
in the medical literature since 1930, covering 14 947 men. He found that between
1940 and 1990, sperm counts fell by 60 per cent on average, and he concluded
that there was 鈥渁 genuine decline in semen quality鈥.

Fisch points out that 93 per cent of the men in Skakkebaek鈥檚 pre-1970 data
were from New York, where he found sperm counts were highest, whereas after
1970, most of the data came from developing countries, where sperm counts were
lower. He observed differences in geography, not time, says Fisch.

Skakkebaek admits that a meta-analysis of the world鈥檚 literature is 鈥渧ery
crude鈥. 鈥淔isch鈥檚 data are very important,鈥 he says. Recent studies in Edinburgh
and Belgium show declines, while studies in Toulouse, France, and from Finland
do not, he says.

But that does not mean that all is well, Skakkebaek says. 鈥淚 confidently
believe there is a problem with male reproductive health.鈥 The incidence of
testicular cancer is increasing every year, and in Denmark now affects 1 per
cent of young men.

He points out that Fisch鈥檚 geographical variation 鈥渋n itself would indicate
that there could be environmental impact鈥. 鈥淚t鈥檚 difficult to explain the
difference between East coast and West coast on ethnic grounds,鈥 he says.

The French study, similar to Fisch鈥檚, is by Pierre Jouannet of the Centre for
the Study of Human Eggs and Sperm in Paris. He studied 1351 sperm donors in
Paris. Men who donated sperm for artificial insemination in 1973, at an average
age of 32, had a mean sperm count of 89 million/ml, while men who donated sperm
in 1992 at an average age of 36 had a count of 60 million/ml, a drop of 33 per
cent. Jouannet stresses that his conclusions cannot be extended to any other
place or even to the whole of Paris.

鈥淥ne of the most puzzling points is the tremendous variability of reported
sperm characteristics from one place to another,鈥 says Jouannet. We cannot rule
out the effects of chemicals in the environment. 鈥淭he debate is still open.鈥

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Lasers win out in glaucoma trial /article/1838083-lasers-win-out-in-glaucoma-trial/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Sat, 06 Jan 1996 00:00:00 +0000 http://mg14920112.800 LASERS are as good as drugs at treating glaucoma, according to a long-term study in the US. This should dispel doubts about the effectiveness of lasers, even though the mechanism of glaucoma, and the reason why lasers are so effective, are still poorly understood.

Glaucoma is caused by a build-up of pressure in the eye, which destroys nerve cells and causes loss of vision. Conventional surgery to treat the condition cuts a channel in the eye to drain excess fluid, but the procedure carries a 5 per cent risk of significant loss of vision. Several drugs can reduce the pressure, but they can cause serious side effects such as raised blood pressure and bronchospasm. Laser surgery seems to carry no risk of major side effects, and this study shows that it is as effective at preserving eyesight as drug treatment.

The study was carried out at several centres around the US, and the results were reported in the American Journal of Ophthalmology (vol 120, p 718). The normal pressure in the eye is around 2000 pascals. The 203 patients who took part in the study started out with a mean intraocular pressure of around 3500 pascals, according to Jacob Wilensky, an ophthalmologist at the University of Illinois, Chicago. Each person was treated in one eye with eye drops, and in the other with an argon laser. Three months later, the mean intraocular pressure had dropped to 2400 pascals.

For most of the participants, the doctors were able to maintain the lower pressure and a stable visual field for an average of 7 years. But 10 per cent of patients needed conventional surgery.

鈥淲e could demonstrate that the laser had a statistically significant benefit over medication,鈥 said study chairman Hugh Beckman, of Sinai Hospital, Detroit. 鈥淏ut we couldn鈥檛 demonstrate that that small benefit was clinically significant.鈥 The eyes treated with the laser had 160 pascals lower intraocular pressure, and a slightly lower loss of vision.

Glaucoma is often a disease of old age, and older patients may find it particularly difficult to tolerate the side effects of drugs. Wilensky says that a 75-year-old patient with newly diagnosed glaucoma could have their condition controlled for the rest of their life by a single laser treatment.

Wilensky says that neither laser treatment nor medication can be guaranteed to keep working after a few decades, though some ophthalmologists disagree. On the other hand, mechanical surgery, while riskier, can permanently lower the pressure to whatever level is required. Wilensky says that a 45-year-old patient will probably need conventional surgery eventually, so doctors may as well operate immediately.

Intraocular fluid is secreted behind the iris, and flows past the pupil into the front chamber of the eye. It normally flows out through the trabecular meshwork, a ring of permeable tissue at the periphery of the iris where it joins the cornea. Glaucoma can occur when the meshwork gets clogged.

Surgeons started using lasers in 1979 to cut a hole in the trabecular meshwork to drain the fluid. The procedure worked, but not for the expected reason. Instead of simply drilling a hole, the laser stimulated a reaction in the mesh that changed its chemistry and made it more permeable.

The matrix that holds the cells in the trabecular meshwork together is constantly destroyed and recreated, and an imbalance could clog it up, says Ted Acott, of the Oregon Health Sciences University, Portland. He says that laser treatment causes trabecular cells to secrete enzymes that disrupt the matrix, so the laser appears to affect the biochemistry of the eye, rather than its plumbing.

The eye under pressure

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In a state of denial /article/1837282-in-a-state-of-denial/?utm_campaign=RSS|NSNS&utm_content=currents&utm_medium=RSS&utm_source=NSNS Fri, 06 Oct 1995 23:00:00 +0000 http://mg14819982.200 鈥淓VERYBODY who shoots drugs knows about the needle exchange,鈥 says Norman, a New York heroin addict in his 40s. Three years ago he tested negative for HIV, 鈥渢hank God鈥. He uses a Harlem shooting gallery 鈥 an apartment where people go to inject drugs. Clean syringes are part of the service, so he never shares needles. The gallery operator collects clean needles free of charge at a Harlem needle exchange.

Norman is one of the lucky few. There are only 76 needle exchanges in the US 鈥 all set up with private money 鈥 serving perhaps 10 per cent of its estimated 1 to 2 million intravenous drug users. The problem is that federal funds cannot be spent on distributing needles until President Bill Clinton鈥檚 health officials acknowledge that needle exchanges reduce the spread of HIV and do not encourage drug use.

At the same time, state laws prohibit the distribution of needles without a doctor鈥檚 permission. According to Denise Paone of Beth Israel Medical Center in New York, more intravenous drug users live in New York than in any other city in the world 鈥 about 200 000 people 鈥 and half of them are HIV-positive. Despite the enormity of the problem, New York State legislators still refuse to repeal the needle laws.

Last month, the calls of activists and researchers who have lobbied the Clinton administration to support needle exchanges were repeated by a panel of eminent scientists brought together by the US National Academy of Sciences. The panel鈥檚 report concludes that American laws 鈥渦nwittingly鈥 contribute to the sharing of contaminated needles, and that 鈥渘eedle exchange programmes can be effective in preventing the spread of HIV and do not increase the use of illegal drugs鈥.

The activists and researchers say this evidence has been staring politicians in the face for some time. 鈥淭hey鈥檝e had this information for two years and they haven鈥檛 acted on it,鈥 says Dave Fratello of the Drug Policy Foundation, a lobbying organisation based in Washington DC. Peter Lurie from the University of California, San Francisco, goes further. 鈥淭he failure to implement needle exchange programmes is the worst thing that has ever happened in terms of the federal response to AIDS,鈥 he says.

In 1993, Lurie wrote a report for the US Centers for Disease Control assessing the public health impact of needle exchange programmes. It reached the same conclusions as the academy report. But Clinton鈥檚 assistant secretary for health, Philip Lee, says Lurie鈥檚 report lacked scientific rigour. However, when a copy of Lee鈥檚 review of the report was leaked to the press last February, it showed that his own staff supported Lurie.

In the two years since his report, says Lurie, HIV has infected 50 000 intravenous drug users, their sexual partners and children. So official delay will cost thousands of lives. 鈥淭here is now a complete consensus of all the bodies that have looked at this issue,鈥 says Lurie.

Paone is also frustrated with politicians鈥 inaction. 鈥淭hey said before we can act on policy we want scientific studies,鈥 she says. Her group found that regular participation in exchange programmes cut an individual鈥檚 risk of HIV infection by half. 鈥淪o now where鈥檚 the policy change?鈥

The academy鈥檚 report has now added to the evidence in favour of needle exchanges. It drew its conclusions firstly from studies by Edward Kaplan at an exchange in New Haven, Connecticut. These found that over three months the proportion of needles infected with HIV that were returned to an exchange fell from 67 per cent to 42 per cent.

The panel鈥檚 second main source was a study in Tacoma, Washington, which compared rates of viral infection among intravenous drug users attending a needle exchange with those of people visiting an HIV testing centre and a methadone programme. The incidence of HIV was too low for statistical sampling, so the researchers used hepatitis B and C as surrogates. They found that only 25 per cent of patients who tested positive for hepatitis B had used the exchange, whereas among those who tested negative for hepatitis B, 74 per cent had used the exchange.

鈥淭hat鈥檚 awfully close to being a direct demonstration that the needle exchange reduces the incidence of a blood borne viral disease,鈥 says Lincoln Moses, professor of statistics at Stanford University, who chaired the academy panel.

The academy鈥檚 report seems so far to have made little impact in Washington DC. Politicians who have opposed needle exchanges, such as Jesse Helms, the hardline Republican Senator from North Carolina, now refuse to comment. Like many who oppose exchanges, Helms still insists that they encourage drug abuse. Last month, however, members of Helms鈥檚 staff who follow health affairs did not even know about the academy and Lurie reports.

From the Presidential camp, Lee鈥檚 response came in a press release that concluded: 鈥淲e will immediately review the report and its conclusions in consultation with the relevant [Congressional] committees.鈥

While politicians such as Helms oppose needle exchanges on ideological grounds, many people see the Clinton administration鈥檚 position as purely self-serving. Fratello says the Democrats are afraid that if they endorsed exchange programmes their conservative opponents would say they were 鈥渟oft on crime鈥, something they cannot allow with the Presidential election due next year. Donald Grove, a needle exchange worker at the Lower East Side Harm Reduction Center in New York, puts it more colourfully. Politicians fear a TV advertisement by their opponents in the next election showing an addict shooting up, with the message: 鈥淭his is how my opponent spent your tax dollars.鈥

But if supporters of needle exchanges cannot persuade national and state politicians to act, they are having more success on a local level. Their strategy is to win over people living close to the exchanges, the police, the African-American community, and doctors who treat drug addicts.

Local residents have particularly strong reservations. 鈥淚 live a block away from the needle exchange,鈥 says Nancy Sosman, who is trying to shut down the Lower East Side center, which hands out syringes to 9000 registered clients. 鈥淲e weren鈥檛 even aware of the needle exchange in the neighbourhood until we found people shooting up in vacant lots 鈥 in hallways and between cars.鈥 But other residents say that these problems existed before the centre opened.

鈥淭he point is proper management,鈥 says Beny Primm, head of Addiction Research and Treatment, a large drug treatment programme. For the exchanges to work, he says, they must be acceptable to the community and the users must behave. 鈥淚 think they鈥檙e trying, though you can鈥檛 always control this population.鈥

The politically influential criminal justice system will also have to be won over. 鈥淎nything that makes it easy to obtain drugs or use drugs will encourage the use of drugs,鈥 says Jerome Storch, a former New York State police detective who is now a professor at John Jay College of Criminal Justice, New York. People accept that logic for cigarettes, he argues. 鈥淚鈥檝e talked to people in countries like England who have had programmes,鈥 says Storch. 鈥淭hey tell me that narcotics abuse is escalating.鈥 But what about studies like Lurie鈥檚 which conclude that exchanges do not encourage drug use? 鈥淭heir literature hasn鈥檛 spread into our literature,鈥 he replies.

But Storch鈥檚 arguments are not borne out by experience in other countries. In the Netherlands, for example, there is an network of exchanges. Ernst Buning of the Amsterdam Municipal Health Service says: 鈥淭he estimated number of hard drug users has been stable for the last 10 years.鈥

In Britain, as in the rest of Europe, drug abuse is on the increase, says Colin Sheppard, Deputy Chief Constable of the Norfolk Constabulary. But he does not believe that needle exchanges are to blame. There has been a needle exchange in Norfolk for four years, Sheppard says, but 鈥淭here is no indication that it is a factor which has increased the number of addicts.鈥

In Britain, pharmacies and more than 250 agencies distribute clean needles. 鈥淭he police cooperate, nobody is hostile,鈥 says Gerry Stimson, director of the London-based Centre for Research on Drugs and Health Behaviour. Before 1987, 60 per cent of injecting drug users regularly shared needles, now the figure is between 10 and 15 per cent. 鈥淲e have kept prevalence of HIV infection pretty low by international standards,鈥 says Stimson. 鈥淥utside London the infection among injectors is about 1 per cent, and in London about 7 per cent and stable.鈥 Stimson says that Britain distributes between 6 and 8 million syringes a year to 100 000 regular injectors. Last year in the US, 8 million syringes were distributed for more than 1 million injectors.

Next on the list of opponents to American needle exchanges is the African-American community. Half of new AIDS patients in the US are black. Many black doctors, clergy and politicians have opposed giving addicts needles or drugs, because they see such strategies as cheap substitutes for comprehensive drug treatment programmes and attempts to eradicate poverty and discrimination. But opposition is softening. Primm, an influential black doctor, accepts needle exchanges as 鈥渢he lesser of two evils鈥. And another influential black doctor, Lawrence Brown Jr of Harlem Hospital, signed the academy report.

Finally, doctors who treat addicts in traditional ways still need to be convinced about exchange programmes. 鈥淎s a compassionate physician, who has had patients die of AIDS, and friends die of AIDS, the last thing I鈥檇 want to do is stop something that might prevent the spread of this dreadful disease,鈥 says Herbert Kleber, a psychiatrist at Columbia University and a member of the academy鈥檚 panel. On the other hand, he says, he does not want to encourage intravenous drug use. Kleber says he still dislikes needle exchanges, but, 鈥測ou put aside your feelings and say, 鈥榃hat does the science show?鈥 In the end, he too signed the report.

The number of needles distributed free to American drug users is rising, but only slowly. 鈥淚t鈥檚 extraordinary if you come from outside the US,鈥 says Warwick Anderson, an Australian historian of science at Melbourne University who has studied American public health policy. 鈥淭he US has served as a control group for the rest of the world. The results are obvious and this de facto trial should be halted.鈥

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