Diagnosis of twin zygosity by self-assessment and by genetic analysis

For 173 pairs of like-sex adult twins, self-assessment of zygosity was verified by laboratory diagnosis. Seventeen percent of twins who were very likely monozygous (MZ) believed themselves dizygous (DZ), frequently citing two placentas at their delivery as "evidence." We suggest that twins be asked what leads them to their assessment of their own zygosity. For 93% of Caucasian and 89% of American Black like-sex twins in our sample, DZ twins could be differentiated based on six polymorphic markers retrievable from frozen sera. MZ twins who believe themselves DZ can be considered "environmentally DZ, genetically MZ" twins, and might be used to study genetic and environmental influences on the treatment of twins and on twins' choices of social characteristics.

Plasma oxytocin and vasopressin concentrations in response to prostaglandin injection into the pig

A single i.m. injection of 5 mg PGF-2 alpha evoked a significant elevation of plasma oxytocin values in sows 6 days post partum and during dioestrus. Plasma vasopressin levels in dioestrous sows were not significantly affected by PGF-2 alpha. It is concluded that circulating steroid levels do not interfere with the response of oxytocin levels to PGF-2 alpha.

Identification of benzhydrol as a urinary metabolite of diphenylmethane in the rat

Liquid-liquid extraction and preparative thin-layer chromatography were used to isolate 30 micromoles of benzhydrol from the beta-glucuronidase treated 24 hour urine of rats administered 5.3 mmoles of diphenylmethane. The benzhydrol was identified by its melting point, elemental analysis, infrared, nuclear magnetic resonance, and mass spectra.

Renal hemodynamics and the renin--angiotensin system in cirrhosis: relationship to sodium retention

Renal hemodynamics and the renin-angiotensin-aldosterone system were investigated in 15 cirrhotic patients without renal failure on controlled sodium intake of 140-160 mEq/day and related to the degree of sodium retention as measured by urinary sodium excretion. Fourteen patients were free of clinical ascites when studied. The distribution of renal blood flow was measured by the noninvasive technique of computerized radioisotope renography. In 11 patients, outer cortical renal plasma flow, expressed as a percentage of total effective renal plasma flow, was directly proportional to sodium excretion (P less than or equal to 0.01). Three patients with severe sodium retention (UNa.V less than or equal to 10 mEq) had estimated outer cortical renal plasma flows of less than or equal to 274 ml/min/1.73 M2 as compared to eight cirrhotics with better (UNa.V greater than or equal to 50 mEq) sodium tolerance (mean = 438 ml/min/1.73 M2). A significant inverse correlation (P less than or equal to 0.01) existed between outer renal cortical blood flow and plasma renin activity. No significant relationship was observed between glomerular filtration rate, total effective renal plasma flow, plasma aldosterone concentration and sodium excretion. These results provide further evidence that a renal vascular abnormality exists in cirrhosis, and that diminished outer cortical renal perfusion is related to the elevated renin levels and sodium intolerance observed in cirrhotic patients.

The Mamprobi Survey--a screening survey for cardiovascular disease and risk factors in Africa: methodology and validity

The Mamprobi Survey is a cardiovascular disease prevalence sample survey in an African community in Ghana. This preliminary paper describes its methodology and validity. Response rate corrected for migration from the area was 73%. Subsequent sampling of non-respondents revealed only trivial reasons for non-attendance and only minor differences in health status, suggesting that estimates of disease prevalence by the survey were likely to be accurate.

Planning with the community in mind can prevent hospital closings

A study of 46 closings and mergers in New York City over a 15-year period shows the importance of public funding for the viability of hospitals and the need for sound institutional planning for hospital survival. Regulatory agencies may deny hospitals public funds if they do not respond to their communities.

Cardiovascular status and blood pressure in a population sample in Ghana--the Mamprobi survey

In a medical survey of an urban population in Ghana, abnormal cardiovascular findings were present in 25% of the population aged from 15 to 64 years. This was largely due to hypertension and to cardiomegaly of obscure origin. The prevalence of valvular heart disease was comparatively low. Abnormal cardiovascular findings were commonest in the lowest third of the socio-economic stratum and next most frequent in the highest third. Abnormal findings were not related to smoking or drinking habits; these seem to be only marginally important in the population at present.

Single radial haemolysis: a survey of antibody titres in the highland region of Scotland to recent strains of influenza A

The single radial haemolysis test is conveniently practical and economical and promises to have wide applicability in the study of influenza antibodies in human populations. It can also be adapted for preliminary examination of new virus isolates during epidemics. Using this test a rather higher proportion of the population in the Highland Region of Scotland were found to possess antibody to a recent epidemic strain of influenza (A/Scotland/74) than was the case in the south of England. Antibody was detected and apparently evenly spread throughout all but the most remote island communities. Some evidence of the spread of the subsequent variant, A/Victoria/75, was obtained. Most of the school children in our study had high antibody titres to recent strains but the proportion with high antibody titres to these strains declined speedily from the age of 17 years onwards.

Toxoplasmosis in the perinatal period

Although many of the fundamental biological features of toxoplasmosis are today well appreciated, the practical problem of prevention of its most serious consequence--disabling congenital disease, remains unsolved. The reasons vary in different communities, but are concerned with detection of the chief mode of spread, assessment of incidence, delineation of vulnerable antenatal women in latently infected populations, and assessment of the risks of therapeutics. The results of some of the approaches to these problems in Scotland are reported and discussed.