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PubMed1989

Epidemiological significance of microbiological pollution criteria for river recreational waters.

A retrospective follow-up study was conducted during the summer of 1986 in the French Ardèche basin in order to assess the relationship between swimming-related morbidity and the bacteriological quality of the recreational water. 5737 tourists in eight holiday camps were questioned as to the occurrence of illness and their bathing habits during the week preceding the interviews. The rate-ratio contrasting swimmers and non-swimmers for total morbidity is 2.1 (1.8-2.4) = 95% confidence interval); gastrointestinal illness is the major type of morbidity and differs significantly between the two groups (RR = 2.4 (1.9-3.0) for total gastrointestinal cases; RR = 2.3 (1.7-3.2) for 'objective' gastrointestinal cases). Faecal streptococci (FS) are best correlated to gastrointestinal morbidity, using direct linear regression models. Faecal coliforms (FC) are not as good predictors of the risk. The concentration of faecal streptococci above which the 'objective' gastrointestinal morbidity among bathers is significantly greater than among non-bathers is 20 FS/100 ml. Swimmers suffer skin ailments much more frequently than non-swimmers (RR = 3.7 (2.4-5.7]; although the relationship may be artefactual, this type of morbidity is well correlated with the concentration of faecal coliforms, aeromonas and pseudomonas. This study provides epidemiological data on which to base microbiological standards for river recreational waters dependent on what might be considered as an 'acceptable' risk.

Adolescent↗
PubMed1990

Management of lone star ticks (Acari: Ixodidae) in recreational areas with acaricide applications, vegetative management, and exclusion of white-tailed deer.

A project on management of lone star ticks, Amblyomma americanum (L.), at Land Between the Lakes, a Tennessee Valley Authority recreational area in Kentucky-Tennessee, during 1984-1988, demonstrated the effectiveness and economics of three control technologies. Acaricide applications (chlorpyrifos at 0.28 kg [AI]/ha), vegetative management (mowing and removal of 40% overstory and 90-100% of midstory, understory, and leaf litter), and host management (white-tailed deer exclusion from a 71-ha campground with a single-line fence) provided 75, 70, and 64% mean controls of all life stages of the lone star tick, respectively. Combinations of acaricide applications + vegetative management, acaricide applications + host management, and acaricide applications + vegetative management + host management produced 94, 89, and 96% mean control of all life stages, respectively. The costs of acaricide applications (two per year), vegetative management (two mowings per year), and white-tailed deer exclusion (single-line fence) were $45, $150, and $30/ha/yr, respectively. Results of this project are used to design management strategies that could be considered for use against lone star ticks in recreational areas.

Analysis of Variance↗
PubMed2005

Lifetime recreational exercise activity and breast cancer risk among black women and white women.

BACKGROUND: Physical inactivity is a potentially modifiable breast cancer risk factor. Because few data on this relationship exist for black women, we examined the relationship between breast cancer risk and lifetime and time- or age-specific measures of recreational exercise activity among white women and among black women. METHODS: The Women's Contraceptive and Reproductive Experiences Study was a multicenter population-based case-control study of black women and white women aged 35-64 years with newly diagnosed invasive breast cancer. We collected detailed histories of lifetime recreational exercise activity during in-person interviews with 4538 case patients with breast cancer (1605 black and 2933 white) and 4649 control subjects (1646 black and 3033 white). Control subjects were frequency-matched to case patients on age, race, and study site. We examined associations between exercise activity measures (metabolic equivalents of energy expenditure [MET]-hours per week per year) and breast cancer risk overall and among subgroups defined by race, other breast cancer risk factors, and tumor characteristics by use of unconditional logistic regression. All statistical tests were two-sided. RESULTS: Among all women, decreased breast cancer risk was associated with increased levels of lifetime exercise activity (e.g., average MET-hours per week per year, P(trend) = .002). An average annual lifetime exercise activity that was greater than the median level for active control subjects was associated with an approximately 20% lower risk of breast cancer, compared with that for inactivity (for 6.7-15.1 MET-hours/week/year, odds ratio [OR] = 0.82, 95% confidence interval [CI] = 0.71 to 0.93; for > or =15.2 MET-hours/week/year, OR = 0.80, 95% CI = 0.70 to 0.92). The inverse associations did not differ between black and white women (for MET-hours/week/year, P(trend) = .003 and P(trend) = .09, respectively; homogeneity of trends P = .16). No modification of risk was observed by disease stage, estrogen receptor status, or any breast cancer risk factor other than first-degree family history of breast cancer. CONCLUSIONS: This study supports an inverse association between physical activity and breast cancer among black women and among white women.

Adolescent↗
PubMed2005

Risky sexual behaviors associated with recreational drug use among men who have sex with men in an international resort area: challenges and opportunities.

South Florida is home to a highly transient population of approximately 145,000 men who have sex with men (MSM) and annually hosts over 1.8 million gay and bisexual visitors. To develop more effective interventions for HIV/sexually transmitted infections (STI) prevention in this setting, we conducted a cross-sectional study of recreational drug use and risky sexual behaviors among MSM. A standardized, self-administered questionnaire, reviewed and approved by a university Institutional Review Board, was offered to men 18 years of age and older who reported ever having sex with a man. Men were approached on weekends in five diverse locations in Miami-Dade County and five in Broward County in winter 2004. An honorarium of $10 was offered to those who completed and returned a questionnaire. Of 407 participants, 115 men (28%) lived in Miami-Dade, 147 (36%) lived in Broward, 46 (11%) lived in another county in south Florida, and 99 (24%) lived elsewhere. Overall, 32% reported using one or more "club drugs" in the past year. Club drug use was highly associated with unprotected anal intercourse (UAI) (P < .001). MSM residing outside of south Florida were more likely than local residents to report using cocaine and ketamine and engaging in unprotected receptive anal intercourse (URAI) in the past month (P = .03). Tourists may be even more likely than residents to engage in risky sexual behaviors and use certain recreational drugs. Interventions must be developed, implemented, and evaluated that take into account the unique characteristics of international resort areas.

Adolescent↗
PubMed1982

Norwalk gastrointestinal illness: an outbreak associated with swimming in a recreational lake and secondary person-to-person transmission.

An outbreak of gastrointestinal illness in which headache, low grade fever and myalgia were common symptoms occurred among persons who visited a recreational park in Macomb County, Michigan, on July 13-16, 1979. The temporal clustering of onsets of 121 persons who were the first in their households to become ill suggested an incubation period ranging from 4-77 hours. A history of swimming in the park's lake was elicited with significantly greater frequency from these persons than from park visitors who were not ill (age standardized odds ratio = 4.8; 95% confidence interval, 1.8-12.7). One hundred twenty-six park visitors who became ill were household contacts of index patients who had swum in the lake; at least 62 of these 126 cases were probably due to secondary transmission. A secondary attack rate of 19% was observed in household contacts who had not visited the park. Serologic studies identified Norwalk virus as the etiologic agent. The source of the contamination of the lake could not be determined. Although some water samples collected just before and after the epidemic period had high coliform counts, the geometric mean coliform density of all samples collected on those days was within the limits established by the Environmental Protection Agency as acceptable for recreational contact water.

Adolescent↗
PubMed1996

Occurrence of breast cancer in relation to recreational exercise in women age 50-64 years.

To investigate the relation between recreational physical activity and breast cancer, we conducted an analysis of a population-based case-control study of women age 50-64 years in western Washington State. The study included 537 patients with breast cancer diagnosed during 1988-1990 and 492 randomly selected population control women. Detailed information on recreational exercise habits and other risk factors for breast cancer was ascertained by structured in-person interviews. A similar proportion of cases and controls reported exercise in the 2 years before the referent date (about 50%), or during ages 12-21 years (about 40%). Compared with women who reported no exercise, there was a slightly decreased risk of breast cancer in women who exercised more than 1.5 hours per week in the 2 years before diagnosis (cases) or referent date (controls) [odds ratio (OR) = 0.7; 95% confidence interval (CI) = 0.4-1.1], or who engaged in at least some high-intensity exercise (OR = 0.7;95% CI = 0.4-1.1), but there was no clear decline in risk at the highest categories of duration or intensity. There was no association between any intensity exercise at ages 12-21 years and risk of breast cancer. These results indicate a weak negative association between physical activity and risk of breast cancer in middle-aged women.

Breast Neoplasms↗
PubMed1996

Numerical simulation of a turning alpine ski during recreational skiing.

While downhill snow skiing, recreational alpine skiers enjoy making turning motions with their skis. These motions are mainly induced by skidding, while turning by alpine ski racers is made by carving a trace in the snow. In the present study we treat the turning motions by recreational alpine skiers. This "skidding" turning motion is made possible by centripetal forces acting on the ski and skier dynamic motion systems, with these forces arising due to the skier placing the ski's longitudinal axis at an angle that is inclined away from the velocity vector and edging the ski into the snow. When snow is soft, the edged ski creates a snow impacting force, whereas a snow cutting force occurs when it is hard. Here, we calculate the former force using a three-dimensional water jet analogy, while the latter one using conventional metal cutting theory, after which the corresponding equations of motion for each system are derived and numerically solved. This methodology enables simulating the curvilinear and rotational motion of the ski and skier systems. Resultant simulations quantitatively show for the first time that the resultant radius of curvature of a ski track while downhill skiing is strongly dependent on the location of the ski boot on the ski's longitudinal axis and also on its side-cut (midlength taper).

Biophysical Phenomena↗
PubMed1997

Water running with and without a flotation vest in competitive and recreational runners.

The purpose of this study was to determine whether competitive and recreational runners would replicate land training intensity during water immersion (WI) running with (V) and without (NV) a flotation vest and during treadmill running (Tm). Seven female competitive runners (CR) and seven female noncompetitive runners (NR) were asked to replicate preferred land training intensity characteristic of a 45-min run under three conditions (Tm, V, and NV). When 20-min submaximal runs at the preferred land training intensity were performed for Tm, V, and NV conditions, CR were able to elicit a similar submaximal VO2 for all three conditions. In contrast, the NR group had a significantly (P < 0.05) lower VO2 (27%), HR (23%), VE (26%) and %VO2max (27%) during V versus Tm condition. During the NV condition, NR had a significantly lower VO2 (13%), %VO2max (13%), and a higher RPE compared with Tm running, and a significantly higher VO2 (16%), HR (15%), VE (24%), %VO2max (15%) and RPE compared with the V condition. Competitive runners were able to achieve training intensities similar to land training for WI running with or without a flotation vest. However, recreational runners failed to replicate land training pace, where intensity was significantly lower during WI running without a vest and lowest with a vest, despite efforts to maintain a similar level of exertion.

Adolescent↗
PubMed1998

Self-selected recreational exercise has no impact on early postpartum lactation-induced bone loss.

UNLABELLED: Although exercise is known to positively impact bone mineral density (BMD), its effect on lactation-induced BMD loss has not been previously evaluated in a case-control study. PURPOSE: The purpose of this study was to compare lactation-induced bone changes in women who engaged in regular, self-selected, recreational exercise versus those who refrained from such during early postpartum. METHODS: Subjects were 20 healthy, lactating women who either exercised regularly (exercise, E; N = 11) or refrained from such (control, C; N = 9) during the first 3 months postpartum. Although preconception VO2max was significantly higher in E than C (E = 54.1, C = 36.9 mL.min-1.kg-1), no significant group differences were observed for parity, age, height, weight (WT), % body fat, dietary calcium intake, lactation calcium loss, and serum estradiol. Total body (TB), lumbar spine (LS), and femur neck (FN) BMD were measured within 2 wk of parturition and repeated at 3 months postpartum by dual energy x-ray absorptiometry. RESULTS: Although TB was unchanged, BMD decreased significantly from baseline in both groups at LS (C = -5.4, E = -4.1%) and FN (C = -2.7, E = -2.8%). WT decreased significantly over time but was not significantly correlated with BMD loss. No significant group by time interactions were observed for WT or BMD changes. CONCLUSION: These results suggest that regular, self-selected, recreational E has no impact on early postpartum lactation-induced BMD loss.

Adult↗
PubMed1999

Exercise-induced asthma: diagnosis and treatment for the recreational or elite athlete.

Exercise-induced asthma: diagnosis and treatment for the recreational or elite athlete. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S33-S38, 1999. Exercise-induced asthma (EIA) is found in 10-50% of recreational and elite athletes, depending on the population studied. The diagnosis may be made with symptoms (cough, wheeze, chest tightness, etc. with exercise) and with pulmonary function measurements (spirometry or peak flow measurements) before and after exercise. Most patients respond well to pre-exercise treatment with an inhaled quick-acting beta agonist. Some patients require additional therapy such as pre-exercise inhaled cromolyn, daily inhaled steroids, salmeterol, theophylline, leukotriene modifiers, or other agents. An occasional patient presents with the symptoms of EIA but responds poorly to treatment. Further investigation may lead to a totally different diagnosis such as vocal cord dysfunction. For most athletes with EIA, proper diagnosis and treatment will allow them to complete at any level.

Adult↗
PubMed2000

Single versus multiple sets in long-term recreational weightlifters.

PURPOSE: The purpose of this study was to determine the effects of increasing training volume from one set to three sets on muscular strength, muscular endurance, and body composition in adult recreational weight lifters. METHODS: Forty-two adults (age 39.7 +/- 6.2 yr; 6.2 +/- 4.6 yr weight training experience) who had been performing one set using a nine-exercise resistance training circuit (RTC) for a minimum of 1 yr participated in this study. Subjects continued to perform one set (EX-1; N = 21) or performed three sets (EX-3; N = 21) of 8-12 repetitions to muscular failure 3 d x wk(-1) for 13 wk using RTC. One repetition maximums (1-RM) were measured for leg extension (LE), leg curl (LC), chest press (CP), overhead press (OP), and biceps curl (BC). Muscular endurance was evaluated for the CP and LE as the number of repetitions to failure using 75% of pretraining 1-RM. Body composition was estimated using the sum of seven skinfold measures. RESULTS: Both groups significantly improved muscular endurance and 1 RM strength (EX-1 by: 13.6% LE; 9.2% LC; 11.9% CP; 8.7% OP; 8.3% BC; and EX-3 by: 12.8% LE; 12.0% LC; 13.5% CP; 12.4% OP; 10.3% BC) (P < 0.05). Both groups significantly improved lean body mass (P < 0.05). No significant differences between groups were found for any of the test variables (P > 0.05). CONCLUSION: Both groups significantly improved muscular fitness and body composition as a result of the 13 wk of training. The results show that one-set programs are still effective even after a year of training and that increasing training volume over 13 wk does not lead to significantly greater improvements in fitness for adult recreational weight lifters.

Adult↗
PubMed1994

Recreational physical activity and risk of benign proliferative epithelial disorders of the breast in women.

The association between recreational physical activity and the risk of benign proliferative epithelial disorders (BPED) of the breast was examined in a case-control study conducted in Adelaide, Australia, between 1983 and 1985. The study included 383 incident, histologically confirmed cases of BPED identified through the major private pathology laboratory, 383 unbiopsied community controls matched to the cases for age and area of residence, and 192 controls whose biopsies did not show any signs of epithelial proliferation. Subjects reported their level of usual weekly physical activity in a self-administered questionnaire. When cases were compared with community controls, there was some evidence for a negative association between risk of BPED and total recreational physical activity. However, the reverse was observed when the cases were compared with biopsy controls. These patterns were essentially the same when examined by intensity of activity and by menopausal status. Despite the lack of an association between physical activity and risk BPED in this study, further investigation is warranted because of the potential benefits for the primary prevention of breast disease.

Adult↗
PubMed1996

Epidemiology of recreational and old-timer ice hockey injuries.

OBJECTIVE: To examine the nature and incidence of injuries suffered by a sample of recreational and old-timer ice hockey players. DESIGN: Random sample of teams followed prospectively. SETTING: Various hockey rinks in the Greater Edmonton Region. PARTICIPANTS: Four hundred and thirty-one subjects--287 adult male recreational (AMRL) and 144 male old-timer (OTL) from five leagues were followed over the 1992-93 hockey season. MAIN OUTCOME MEASURES: Injuries sustained during the duration of a hockey season. RESULTS: A total of 151 injuries (100 AMRL and 51 OTL) were reported. The aggregate injury rate was 12.2/1000 player-exposures (12.3 AMRL and 12.0 OTL). The anatomic region most often injured by AMRL players was the head/neck/facial area (32%) while OTL players reported a greater proportion of lower extremity injuries (40%). Both groups reported sprains/strains as the most common diagnosis (35% AMRL and 47% OTL). The predominant injury mechanism for AMRL players was stick contact (24%) and for OTL players was puck contact (23%). No significant differences were detected between the anatomic, diagnostic, and mechanistic distributions of injury between AMRL and OTL players. Seventy-five percent of injuries occurred during league games, 10% during playoff games, 5% during tournament games, and 10% during practices. Penalties were assessed in 31% of injury instances. Forty-two percent of head/neck/facial injuries, 32% of upper extremity injuries, 13% of torso injuries, and 15% of lower extremity occurred as a result of penalizable behavior (p = 0.01). Three percent of players wearing full or half face protectors suffered facial injuries while 9% of players not wearing facial protection reported facial injuries (p = 0.03; Relative Risk = 2.56). CONCLUSIONS: The injury rates observed were lower than reported rates for major/elite hockey. The proportion of players injured through body contact was lower than that observed in adult major/elite hockey while the diagnostic and anatomic distribution of injury was similar. Studies such as this are useful in the development of injury prevention strategies.

Adult↗
PubMed2005

Hip muscle weakness and overuse injuries in recreational runners.

OBJECTIVE: To test for differences in strength of 6 muscle groups of the hip on the involved leg in recreational runners with injuries compared with the uninvolved leg and a control group of noninjured runners. DESIGN: Descriptive analysis. SETTING: : Three outpatient physical therapy clinics in the Minneapolis/St. Paul metropolitan area. PARTICIPANTS: Thirty recreational runners (17 female, 13 male) experiencing a single leg overuse injury that presented for treatment between June and September 2002. Thirty noninjured runners (16 female, 14 male) randomly selected from a pool of 46 volunteers from a distance running club served as controls. MAIN OUTCOME MEASURES: Self-report demographic information on running habits, leg dominance demonstrated by preferred kicking leg, and injury information. Muscle strength of the 6 major muscle groups of the hip was recorded using a hand-held dynamometer. The highest value of 2 trials was used, and strength values were normalized to body mass(2/3). RESULTS: Results comparing the injured and noninjured groups showed that leg dominance did not influence the leg of injury (chi(2)(1) = 0.134; P = 0.71). Correlations for internal reliability of muscle measurements between trials 1 and 2 with the hand-held dynamometer ranged from 0.80 to 0.90 for the 6 muscle groups measured, and all P values were less than 0.0001. No significant side-to-side differences in hip group muscle strength were found in the noninjured runners (P = 0.62-0.93). Among the injured runners, the injured side hip abductor (P = 0.0003) and flexor muscle groups (P = 0.026) were significantly weaker than the noninjured side. In addition, the injured side hip adductor muscle group was significantly stronger (P = 0.010) than the noninjured side. Duration of symptoms was not a contributing factor to the extent of injury as measured by muscle strength imbalance between injured and uninjured sides. CONCLUSIONS: Although no cause-and-effect relationship has been established, this is the first study to show an association between hip abductor, adductor, and flexor muscle group strength imbalance and lower extremity overuse injuries in runners. Because most running injuries are multifaceted in nature, areas secondary to the site of pain, such as hip muscle groups exhibiting strength imbalances, must also be considered to gain favorable outcomes for injured runners. The addition of strengthening exercises to specifically identified weak hip muscles may offer better treatment results in patients with running injuries.

Adolescent↗
PubMed2004

Beyond the K-hole: a 3-year longitudinal investigation of the cognitive and subjective effects of ketamine in recreational users who have substantially reduced their use of the drug.

RATIONALE: Ketamine is a dissociative anaesthetic that is also a drug of abuse. Previous studies have demonstrated persisting episodic and semantic memory impairments in recreational ketamine users 3 days after taking ketamine. However, the degree to which these deficits might be reversible upon reduction or cessation of ketamine use was not known. OBJECTIVE: To follow-up a population of ketamine users tested 3 years previously and examine whether impairments observed 3 days after drug use are enduring or reversible. METHODS: Eighteen ketamine users and 10 polydrug controls from studies conducted between 3 and 4 years earlier were re-tested on the same battery of cognitive tasks and subjective measures. These tapped episodic, semantic and working memory and executive and attentional functioning. Subjective schizotypal, dissociative, mood and bodily symptoms were also examined and a drug use history recorded. RESULTS: The ketamine users had reduced their frequency of use of ketamine by an average of 88.3%. Performance of ketamine users on tasks tapping semantic memory had improved and this improvement was correlated with their reduction in ketamine use. On tasks tapping episodic memory and attentional functioning, ketamine users still showed deficits compared to polydrug controls. Higher levels of schizotypal symptoms and perceptual distortions were exhibited by the ketamine group, although dissociative symptoms were similar to controls. CONCLUSIONS: These findings indicate that semantic memory impairments associated with recreational ketamine are reversible upon marked reduction of use; however, impairments to episodic memory and possibly attentional functioning appear long-lasting. In addition, schizotypal symptoms and perceptual distortions may persist after cessation of ketamine use. Ketamine users, or potential users, should be aware of the enduring effects of this drug on aspects of memory and subjective experience.

Adult↗
PubMed2006

Detection of the nifH gene of Methanobrevibacter smithii: a potential tool to identify sewage pollution in recreational waters.

AIMS: The goal of this study was to develop and test the efficacy of a PCR assay for the environmental detection of the nifH gene of Methanobrevibacter smithii, a methanogen found in human faeces and sewage. METHODS AND RESULTS: PCR primers for the nifH gene of M. smithii were designed, tested and used to detect the presence or absence of this organism in faecal and environmental samples. Specificity analysis showed that the Mnif primers amplified products only in M. smithii pure culture strains (100%), human faeces (29%), human sewage samples (93%) and sewage-contaminated water samples (100%). No amplification was observed when primers were tested against 43 bacterial stock cultures, 204 animal faecal samples, 548 environmental bacterial isolates and water samples from a bovine waste lagoon and adjacent polluted creek. Sequencing of PCR products from sewers demonstrated that a 222-bp product was the nifH gene of M. smithii. The minimal amount of total DNA required for the detection of M. smithii was 10 ng for human faeces, 10 ng for faecally contaminated water and 5 ng for sewage. Recreational water seeded with M. smithii established a lower detection limit of 13 cells ml(-1). CONCLUSIONS: The Mnif assay developed during this investigation showed successful detection of M. smithii in individual human faecal samples, sewage and sewage-contaminated water but not in uncontaminated marine water or bovine-contaminated waters. The Mnif assay appears to be a potentially useful method to detect sewage-polluted coastal waters. SIGNIFICANCE AND IMPACT OF THE STUDY: This study was the first to utilize methanogens as an indicator of sewage pollution. Mnif PCR detection of M. smithii was shown to be a rapid, inexpensive and reliable test for determining the presence or absence of sewage pollution in coastal recreational waters.

Animals↗
PubMed1997

Health effects of exposure to cyanobacteria (blue-green algae) during recreational water-related activities.

The aim of this study was to investigate effects on health of exposure to cyanobacteria as a result of recreational water activities. Participants, who were aged six years and over, were interviewed at water recreation sites in South Australia, New South Wales and Victoria on selected Sundays during January and February 1995. Telephone follow-up was conducted two and seven days later to record any subsequent diarrhoea, vomiting, flu-like symptoms, skin rashes, mouth ulcers, fevers and eye or ear irritations. On the Sundays of interview, water samples from the sites were collected for cyanobacterial cell counts and toxin analysis. There were 852 participants, of whom 75 did not have water contact on the day of interview and were considered unexposed. The 777 who had water contact were considered exposed. No significant differences in overall symptoms were found between the unexposed and exposed after two days. At seven days, there was a significant trend to increasing symptom occurrence with duration of exposure (P = 0.03). There was a significant trend to increasing symptom occurrence with increase in cell count (P = 0.04). Participants exposed to more than 5000 cells per mL for more than one hour had a significantly higher symptom occurrence rate than the unexposed. Symptoms were not correlated with the presence of hepatotoxins. These results suggest symptom occurrence was associated with duration of contact with water containing cyanobacteria, and with cyanobacterial cell density. The findings suggest that the current safety threshold for exposure of 20,000 cells per mL may be too high.

Adult↗
PubMed1984

Recreational drugs: relationship to AIDS.

Current data suggest that a transmissible agent causes AIDS, but undefined cofactors may also play a role. This paper reviews published data on the relationship between recreational drugs and immune alterations, with particular emphasis on nitrite inhalant (NI) use by homosexual men. In our original cohort of 15 homosexual men, helper:suppressor (H:S) T-cell ratios are stable, but persistently lower in the NI users. A recent analysis of 245 homosexual men shows that NI use is associated with low H:S ratios in homosexual men in Washington, D.C., but not in New York. Although NI use could increase the risk of AIDS by direct or indirect effects, it could also be a surrogate for a lifestyle practice that predisposes homosexual men to the putative AIDS agent. The current evidence concerning use of NI and the risk of AIDS is inconclusive, as is true for two other recreational drugs, heroin and cocaine. Future studies may not be able to dissect the complex interrelationships of drug use and other variables until precise laboratory tests are available for defining exposure to the putative AIDS agent and suspect cofactors.

Acquired Immunodeficiency Syndrome↗