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M T Schechter

Publications and source records attributed to M T Schechter.

At least 181 records · Page 10Linked to original sources
PubMed1989

Evidence that prior immune dysfunction predisposes to human immunodeficiency virus infection in homosexual men.

To investigate the role of host susceptibility to HIV-1 infection, we studied subsequent seroconversion in 161 individuals, initially seronegative to HIV-1, who underwent skin testing for cutaneous anergy at an index visit within a prospective study of homosexual men. There were 23 seroconversions in these men by 45 months following the skin testing, yielding a crude rate of seroconversion of 14.3%. While results of purified protein derivative (PPD), Candida, and Trichophyton skin tests were not associated with subsequent course, anergy to dinitrochlorobenzene (DNCB) was predictive of subsequent seroconversion. Kaplan-Meier estimates for the risk of seroconversion during 45 months of follow-up in those men initially anergic and reactive to DNCB were 28.9 and 11.1%, respectively, yielding a relative risk of 2.6 (p = 0.006). The estimated relative risk was stable with adjustment by Cox regression for annual number of male sexual partners and frequency of receptive anal intercourse, and was not sensitive to various changes in the definition of seroconversion time and of eligibility criteria. These data suggest that an impaired host immune status may be associated with an increased risk of HIV-1 infection that is independent of risk of exposure to the virus, supporting earlier speculations that HIV-1 may itself be opportunistic. The notion of varying host susceptibility to infection, at least with regard to sexual transmission in homosexual men, may help to explain the frequent observation of individuals who have been repeatedly exposed to the virus and yet have remained uninfected.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Retinopathy of prematurity: a new epidemic?

This study provides the first empiric evidence for the existence of a new epidemic of retinopathy of prematurity-induced blindness. Data from a population-based register of handicapping conditions in the Canadian province of British Columbia, and a birth weight-specific census of live-born infants in British Columbia, were used to determine annual, population-level incidences of retinopathy of prematurity-induced blindness during 1952 to 1983. Changes in incidence since the end of the original epidemic (1954) were determined by subdividing the 29-year period (1955 to 1983) into two intervals (1955 to 1964 and 1965 to 1983). Standardized incidence ratio analyses revealed a marginally significant increase in the overall incidence of retinopathy of prematurity-induced blindness in the later as compared with the earlier period. Infants weighing 750 to 999 g at birth had a significantly increased standardized incidence ratio of 3.07 (95% confidence interval 1.26, 11.06). No increases in risk were observed in heavier or lighter weight infants. Because ascertainment and diagnostic changes do not explain the weight-specific increases in incidence, these results provide the first population-level evidence for a new epidemic.

Blindness↗
PubMed1988

Evaluation of a postocclusive reactive circulatory hyperaemia (PORCH) test for the assessment of ulnar collateral circulation.

This prospective double-blind study compared Doppler assessment of the ulnar collateral circulation with the Allen's test and a postocclusive reactive circulatory hyperaemia (PORCH) test in 144 patients (288 hands). The PORCH test involves inflation of a blood pressure cuff on the upper arm to a supra systolic (+50 mmHg) pressure for two minutes. Prior to cuff deflation, both radial and ulnar arteries are occluded at the wrist; the cuff is then deflated and a 15-second period allowed so as to restore blood flow down to the wrist. Ulnar artery compression is now released and the time to revascularization measured. Fifty-eight per cent of hands with an abnormal Allen's test had a normal ulnar collateral circulation. Results of Allen's test were not significantly affected by patients' sex or smoking status (p greater than 0.1) but there was a significant difference (p = 0.001) in the false positive rates between patients over 40 years of age (0.2) and those under 40 years of age (0.03). Results of the PORCH test were not significantly affected by patients' age, sex or smoking status (p greater than 0.1). With a revascularisation time of 19 sec as a "cut off" for ulnar abnormality the PORCH test, unlike the Allen's test, was perfectly predictive of an abnormal ulnar collateral circulation and had no false positives.

Aged↗
PubMed1988

Evaluation of diagnostic criteria for bacteriuria in acutely spinal cord injured patients undergoing intermittent catheterization.

To evaluate diagnostic criteria for bacteriuria in acutely spinal cord injured patients undergoing intermittent catheterization, we studied paired urine specimens obtained by suprapubic aspiration and intermittent catheterization. Culture of suprapubic aspirate was used to define presence or absence of bacteriuria. Fifty patients were studied for an average of 5 consecutive days; bacteriuria occurred within the study period in 47 (94%). Low-level bacteriuria was frequent; thus, the traditional diagnostic criterion, greater than or equal to 10(5) cfu/ml of midcatheter urine, had unacceptably low sensitivity (gram-positive organisms 0.45; gram-negative organisms 0.65) for bacteriuria documented by suprapubic aspiration. The best diagnostic criterion for gram-positive bacteriuria was between greater than or equal to 10(1) cfu/ml (sensitivity 0.91, specificity 0.86) and greater than or equal to 10(2) cfu/ml (sensitivity 0.85, specificity 0.93). For gram-negative bacteriuria, greater than or equal to 10(1) cfu/ml was optimal (sensitivity 0.96, specificity 0.96); a more practical criterion, greater than or equal to 10(2) cfu/ml, retained excellent sensitivity (0.91). Suprapubic or flank pain and/or tenderness occurred in five of 47 bacteriuric subjects; nonspecific symptoms, possibly associated with bacteriuria, were seen in an additional 28 subjects. We conclude that, in this unique population, a criterion of greater than or equal to 10(2) cfu/ml of midcatheter urine should be used for diagnosis of bacteriuria.

Bacteria↗
PubMed1988

Human amnion as a bioprosthesis for bile duct reconstruction in the pig.

Despite technical advances in management, the complication of late stricture formation and biliary sepsis still occur in bile duct reconstruction. In an attempt to avoid bilioenteric anastomosis, which bypasses the biliary sphincter mechanism, various biologic and artificial materials have been employed clinically and experimentally to replace the damaged bile duct. No satisfactory biliary replacement material has yet been found. In the experimental model of bile duct stricture that has been presented, human amnion bile duct injuries mimicking those seen in clinical practice were repaired using human amnion as a free graft. Noncircumferential duct loss appeared to be satisfactorily repaired using amnion, and the amnion repair was found to be as good as or superior to plastic repair; however, circumferential duct loss was not adequately repaired with the amnion graft.

Alkaline Phosphatase↗
PubMed1988

Patterns of sexual behavior and condom use in a cohort of homosexual men.

To measure the magnitude of risk reduction within a cohort of homosexual men, questionnaire responses in April 1984-March 1985 were compared to those in October 1986-September 1987. A total of 361 subjects were eligible (231 seronegative, 130 seropositive). The annual number of sex partners declined significantly from a median of 8.0 to 5.0 with no difference between the serologic groups. The number of subjects reporting no receptive anal intercourse increased as did condom use during anal receptive intercourse. More seronegatives than seropositives subjects reported no condom use during receptive anal intercourse with regular partners (45.7 per cent versus 23.4 per cent), and with casual partners (14.9 per cent versus 1.5% percent). Among subjects with the most casual sexual contact at the second visit, 33.3 per cent of seronegatives and 29.2 per cent of seropositives did not report usual condom use during receptive anal intercourse with casual partners. Although we have documented marked risk reductions, safe sex practices are still not universal, and a few individuals continue to put themselves at extremely high risk.

Adult↗
PubMed1987

The Vancouver Lymphadenopathy-AIDS Study: 7. Clinical and laboratory features of 87 cases of primary HIV infection.

In an ongoing prospective study of homosexual men conducted in Vancouver since November 1982, 87 cases of human immunodeficiency virus (HIV) seroconversion have been documented to date. Comparison of laboratory results obtained a mean of 4.9 months before and 5.4 months after the estimated date of seroconversion revealed that a significant increase in the serum IgG level (from 1149 to 1335 mg/dl on average) and in C1q binding (from 8.8% to 14.2% on average) was associated with early HIV infection (p less than 0.001). A marginally significant decrease in the ratio of helper to suppressor (CD4 to CD8) cells (from 1.55 to 1.29 on average) was also noted (p = 0.025). A marked decrease in absolute number of CD4 cells was not seen with seroconversion, which suggests that profound loss of these cells may be a long-term effect of HIV infection. The occurrence of symptoms (including fatigue, fever, night sweats, unintentional weight loss, diarrhea, joint pains, cough unrelated to smoking, shortness of breath, oral thrush, herpes zoster and rash) did not increase with seroconversion. This finding suggests that most cases of HIV seroconversion may be asymptomatic or associated with relatively minor symptoms. On the other hand, generalized lymphadenopathy was found to develop after HIV seroconversion in about 50% of cases.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Prison health services: a utilization study.

A prospective study of health service utilization carried out in the Correctional Services of Canada (CSC), Pacific Region, is reported. Health service encounters occurring at the six Regional Institutions with on-site health care centers between May 29th and June 28th, 1984 were surveyed using a health clinic encounter form. There were 7,449 encounters during the study period. The mean rate of encounters was 5.2 per inmate. Seventy-two percent of these encounters occurred at wickets, and 28% occurred at clinics. Physician visits occurred at a mean estimated annual rate of 6.7 visits per year. This is 2.4 times higher than the mean annual physician visit rate for non-institutionalized men in Canada. The reason for visits was new illness (57%), chronic illness (31%), injuries (5%), psychosocial problems (2%), and administrative (5%). The encounter rate per 100 inmates varied from 19.7 to 1,203.6 across the institutions studied. Overall 89% of all visits were seen by health service nurses, while 11% were seen by physicians. Using ICHPPC-2 Defined, the ten most common complaints presented to the health service were headache, sore throat, stomach complaint, other respiratory complaint, tension headache, limb pain, other/not codable, medical examination, back pain and upper respiratory tract infection. These ten complaints accounted for 4896 (59%) of the total complaints recorded. The majority of visits took less than five minutes, were most often treated with medication, and did not require scheduled follow-up. The 50 most frequent visitors, those making 25 or more visits during the study period, while only 3.5% of the study population, accounted for 25% of all encounters.

British Columbia↗
PubMed1987

Preoperative predictors of mortality risk in ruptured abdominal aortic aneurysm.

A retrospective review of 106 cases of ruptured abdominal aortic aneurysm was undertaken to determine whether analysis of preoperative variables might be predictive of death in this condition. Thirty variables were analyzed by univariate and multivariate methods. Statistically significant differences between survivors and nonsurvivors were noted for 12 of 30 factors when analyzed with univariate tests. Multivariate analysis with stepwise logistic regression demonstrated that elevation of the unmeasured anion gap, a history of congestive heart failure, and the patient's level of consciousness before operation were significantly and independently associated with death. Coefficients generated from this model allowed stratification of patients into four risk groups with respective mortality rates of 100%, 75%, 28%, and 12%. We conclude that it is possible to assign a mortality risk score to individual cases of ruptured abdominal aortic aneurysm on the basis of readily available clinical and laboratory parameters. A prospective study to address this question seems justified.

Acid-Base Equilibrium↗
PubMed1987

Effects of long-term seropositivity to human immunodeficiency virus in a cohort of homosexual men.

The long-term effects of HIV infection were evaluated by comparing data from two visits a mean of 18 months apart in groups of 148 persistently seropositive and 287 persistently seronegative homosexual men. At each visit, the seropositive men exhibited lower CD4 counts, CD4/CD8 ratios, hemoglobin concentrations and lymphocyte counts, and higher C1q binding, IgG and IgA levels. More important, the decline of the CD4/CD8 ratio and the rise of the C1q binding, IgG and IgA, progressed significantly in the seropositive group between visits. Seropositive men were at elevated risk of developing constitutional symptoms and generalized lymphadenopathy. An association was present between development of symptoms and inversion of the CD4/CD8 ratio. The 11 seropositive men who have progressed to AIDS had lower CD4 counts and CD4/CD8 ratios, and higher C1q binding, IgG and IgA, than 134 seropositive AIDS-free men a mean of 21.4 months prior to diagnosis. The AIDS group demonstrated greater decline between visits in the CD4 count, hemoglobin and white blood count (WBC) than the seropositive AIDS-free group. The present data document the long-term effects of HIV infection in a seropositive cohort and suggest the possibility of a subgroup particularly susceptible to the progressive effects of HIV that precede the development of the acquired immunodeficiency syndrome (AIDS).

Acquired Immunodeficiency Syndrome↗
PubMed1987

Subjective fears and objective data: an epidemiologic study of environmental health concerns.

A political emergency arose in 1985 for the province of Alberta, Canada, because allegations of increased health risk had frightened rural Alberta residents exposed for 28 years to the airborne effluent of sour gas processing plants. In an epidemiologic study that took 3 months in the field, cross-sectional and cohort comparisons were conducted for these residents and for two carefully selected control groups. Clinical examinations were conducted with objective methods and criteria. No excess rates were found in the exposed group for any life-threatening or seriously disabling conditions. For the exposed group in the index area the reported cardinal symptoms were slightly higher than in the main unexposed reference group, but the observed cardinal signs were slightly lower. This project shows that scientifically sound strategies can be used to investigate major health controversies. Rigorous clinical methods of measurement, incorporated into a classical epidemiologic study, can inspire confidence in the studied population and can make the results acceptable to clinicians and policy makers. The studies can be done rapidly in response to urgent or crisis situations without compromising methodologic rigor or the quality of the analyses.

Air Pollution↗
PubMed1986

The Vancouver Lymphadenopathy-AIDS Study: 6. HIV seroconversion in a cohort of homosexual men.

In an ongoing prospective study of homosexual men conducted since November 1982 in Vancouver, we identified 345 men who did not have antibody to human immunodeficiency virus (HIV) at the time of enrolment and for whom results of follow-up serologic testing were available. A total of 66 cases of seroconversion were documented among the 345 men between November 1982 and October 1985. Methods of survival data analysis that take into account the varying durations of follow-up were used to study the epidemiologic features of seroconversion in this group. The probability of seroconversion during the entire observation period was 23.1%. The seroconversion rates remained stable, at 10.5% and 10.0% during the last 2 years of the observation period. Cox regression analysis revealed the following variables to be independently associated with risk of seroconversion: frequent receptive anal intercourse, elevated number of male sexual partners in the year before enrolment, use of illicit drugs, a history of gonorrhea and age less than 30 years in November 1982. Multivariate analysis failed to reveal any role of oral sexual activity in the transmission of HIV. Oral ingestion of semen was not associated with seroconversion in either univariate or multivariate analysis. The observation that younger men were more likely to seroconvert suggests that young homosexual men were less likely than older men to modify their sexual behaviour.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The Vancouver Lymphadenopathy-AIDS Study: 5. Antecedent behavioural, clinical and laboratory findings in patients with AIDS and HIV-seropositive controls.

In a group of homosexual men in Vancouver studied prospectively since November 1982, 26 cases of acquired immune deficiency syndrome (AIDS) have arisen. To identify behavioural, clinical and laboratory findings that might predict the development of AIDS in people with antibody to human immunodeficiency virus (HIV), we compared data for 25 patients with AIDS with corresponding data for 80 controls serologically positive for HIV selected from the cohort. The clinical and laboratory data for the patients with AIDS preceded the diagnosis of the syndrome by a mean of 17.5 months. The controls had been both seropositive and AIDS-free for a mean of 16.7 months after acquisition of their data. We detected significant differences between the patients with AIDS and the controls in IgG and IgA levels, absolute number of helper T cells and ratio of helper to suppressor T cells but not in lifetime number of male sexual partners, frequency of receptive anal intercourse or receptive fisting, illicit drug use or history of infectious disease. We also detected an increased risk of AIDS among those who had an elevated number of sexual contacts in AIDS-endemic areas in the 5 years before enrollment. A history of increased early sexual contact in AIDS-endemic areas is likely to be associated with early infection and with an increased risk of AIDS among men with HIV infection of unknown duration. Thus, although our analysis had limited statistical power, we conclude that most lifestyle variables appear to act as exposure factors in HIV infection but not as cofactors in the development of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Diagnostic utility of lymphocyte subset analysis in AIDS case finding.

Abnormalities of lymphocyte subsets, especially low absolute number of helper T cells, are characteristically present in acquired immune deficiency syndrome (AIDS). Similar abnormalities can be found in patients with persistent generalized lymphadenopathy (PGL) or AIDS-related complex (ARC) and, to a lesser degree, in asymptomatic people who have been exposed to human T-lymphotropic virus type III (HTLV-III). Nevertheless, there appears to be a widespread perception that lymphocyte subset analysis may be useful in AIDS case finding within high-risk groups. We evaluated the diagnostic utility of absolute number of helper T cells and ratio of helper to suppressor T cells in 33 patients with AIDS, 43 patients with PGL who had been referred for lymph node biopsy, 90 patients with PGL and 195 male homosexual controls. At conventional cutoff levels the tests did not appear to revise the probability of AIDS upward to any clinically significant degree when the pretest probability of AIDS was low. Lymphocyte subset analysis does not appear to be a cost-effective method of AIDS case finding in identified groups at risk in which the prevalence of AIDS is low.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Selection of women at high risk of breast cancer for initial screening.

Selective breast cancer screening refers to the intentional restriction of screening to only a high-risk subgroup of the total population of women at risk. Using data from the Canadian National Breast Screening Study, we explored methods of defining such subgroups. Discriminants were based on risk factor information collected prior to screening and were constructed using a training group of 77 cases and 400 controls. They were then tested on a separate group of 38 cases and 200 controls. Both simple risk factor counts and logistic models were utilized and separate analyses were performed for pre- and post-menopausal women. Using a logistic model, we were able to define a high-risk subgroup encompassing less than 40% of the test controls and over 85% of the test cases. Such a selection strategy, if implemented, might reduce initial visit mammography rates by up to 60% with only a small reduction in case detection. Other uses as determining the optimal age for initiation of screening are also discussed.

Age Factors↗
PubMed1985

The Vancouver Lymphadenopathy-AIDS Study: 4. Effects of exposure factors, cofactors and HTLV-III seropositivity on number of helper T cells.

Results of testing for antibody to human T-lymphotropic virus (HTLV-III) and absolute numbers of helper T cells in 219 participants in the Vancouver Lymphadenopathy-AIDS (acquired immune deficiency syndrome) Study were analysed. The mean absolute helper T-cell counts in the 141 HTLV-III seronegative and the 78 seropositive men were 897/mL and 659/mL respectively (p less than 0.001). Established AIDS risk factors such as elevated lifetime number of male sexual partners and frequent receptive anal intercourse did not appear to have any significant effect on number of helper T cells that was independent of HTLV-III antibody status. Seropositive men with less than 100, 100 to 500 or more than 500 male sexual partners in their lifetime had mean absolute helper T-cell counts of 667/mL, 651/mL and 662/mL respectively. Most other risk factors, as well, did not appear to exert any effect on absolute number of helper T cells that was independent of the effect of HTLV-III antibody status. However, independent effects of a history of mononucleosis or hepatitis and of cigarette smoking were noted. The data support the hypothesis that no immune dysfunction beyond that due to the initial infection alone arises from repeated exposure to HTLV-III. Most risk factors appear to act as exposure factors, exerting their effect on the immune system merely by increasing the probability of contact with the agent. The independent effects of a history of mononucleosis or hepatitis suggest that viral agents may be cofactors in the production of immune dysfunction.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Limited usefulness of lymphocytopenia in screening for AIDS in hospital patients.

Lymphocytopenia is often present in patients with acquired immune deficiency syndrome (AIDS) and has been suggested as a useful screening test for AIDS. Of 625 patients consecutively admitted to an acute care university teaching hospital 91 (15%) were found to have a lymphocyte count of less than 1 X 10(9)/L, and 25 (4%) had a count of less than 0.5 X 10(9)/L. The corresponding figures for 32 patients at the hospital in whom AIDS had been diagnosed were 13 (41%) and 4 (13%). Absolute lymphocyte counts in hospitalized patients should not be used as the sole means of identifying patients at high risk for AIDS.

Acquired Immunodeficiency Syndrome↗