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Biomedical subjects

C E Stevens

Publications and source records attributed to C E Stevens.

At least 145 records · Page 8Linked to original sources
PubMed1977

The e antigen and vertical transmission of hepatitis B surface antigen.

The relationship of e antigen (eAg) and its antibody (anti-e) to vertical transmission of hepatitis B surface antigen (HBsAg) from chronic asymptomatic HBsAg carrier women to their children was investigated in Taiwan. Sera from 20 of the 62 women studied were positive for eAg (32%); serum from only one woman was positive for anti-e (2%). A total of 85% of the babies born to eAg positive mothers became HBsAg carriers, while only 31% of the babies became carriers when the mother was eAg negative. Maternal e antigenemia correlated with a high HBsAg titer, and both parameters were equally good predictors of vertical transmission.

Aspartate Aminotransferases↗
PubMed1977

Hepatitis type A and hemodialysis: a seroepidemiologic study in 15 U.S. centers.

Four hundred sixty patients and staff from 15 U.S. dialysis centers were surveyed by the immune adherence hemagglutination technique for antibody to hepatitis A antigen (anti-HA). The age-standardized anti-HA prevalence was 42.9% in patients and 42.1% in staff. These rates are almost identical to those of socioeconomically comparable urban volunteer blood donors never exposed to dialysis settings. There was no correlation between anti-HA prevalences and duration of dialysis treatment or employment. Among 100 patients and staff followed for 1 year 92% to 94% did not change their anti-HA status. The prevalence of anti-HA was identical in subjects with past histories of multiple blood transfusions or accidental inoculations with blood-contaminated instruments and in those without such histories. We conclude that hepatitis A virus rarely if every spreads by parenteral mechanisms, that there is no epidemiologic evidence confirming the existence of chronic hepatitis A viremic carrier states, and that hemodialysis does not play a significant role in the spread of type A hepatitis.

Adolescent↗
PubMed1976

Distribution of antibody to hepatitis a antigen in urban adult populations.

To investigate the prevalence and distribution of antibody to hepatitis A antigen we tested 947 randomly selected people in the Greater New York City area; 45 per cent were antigen positive, as determined by the immune adherence method. Antibody was detected two to three times more frequently in lower social classes (72 to 80 per cent) than in middle and upper-middle classes (18 to 30 per cent). The rate of antibody detection was strongly correlated with age; the prevalence gradually increased throughout adulthood and reached its peak level in people 50 years of age and older. Those with serologic evidence of past exposure to hepatitis B virus were significantly more often antibody positive than those without such evidence (61 vs. 40 per cent; P less than 0.001). Very few of the positive subjects had had hepatitis. The prevalence of this antibody varies among different population groups, increases with age, decreases with rise in socioeconomic status, is independent on sex and race, and correlates with serologic evidence of hepatitis B virus infections.

Adolescent↗
PubMed1976

Antibody against the hepatitis type B core antigen. A new tool for epidemiologic studies.

Four random samples representing populations at low (volunteer blood donors), intermediate, (VD clinic patients), high (family contacts of chronic antigen carriers) and very high (male homosexuals) risk of exposure to HBV were surveyed. Among HBsAg and anti-HBs negative individuals an average of 3.3% were found to be anti-HBc positive, and among those with anti-HBs, 19.4% were anti-HBc positive. Anti-HBc, with concurrent anti-HBs and without, was detected more frequently in the high risk samples than in the low risk. Individuals was a past history of acute viral hepatitis were more frequently anti-HBc positive than those without such a history, and anti-HBc positivity was frequently accompanied by serum transaminase elevation. Anti-HBc may persist for many years after an episode of acute hepatitis. In households of carriers, the highest frequency of anti-HBc was observed among spouses, which would argue for the possibility of sexual transmission. A significant excess of females with both types of antibody was observed in families of carriers. Anti-HBc determinations in conjunction with other HBV markers, provide a useful new tool for epidemiologic studies.

Adolescent↗
PubMed1975

Evidence against breast-feeding as a mechanism for vertical transmission of hepatitis B.

A follow-up study of 147 babies born to mothers known to be carriers of hepatitis B surface antigen (HBsAg) revealed no evidence for a relationship between breast-feeding and the subsequent development of antigenaemia in the babies. All babies were tested at three or more months of age, and the mean age at last follow-up was eleven months with a mean of three serum specimens per baby (not counting cord-blood specimens). The frequency of acquisition of HBsAg and anti-HBs was almost identical among breast-fed and non breast-fed infants. The frequency of other variables known to influence the development of antigenaemia among infants of carrier mothers did not vary according to breast-feeding status: mother's HBsAg titre, HBsAg positivity rate in cord-blood specimens, and HBsAg prevalence among siblings. 32 breast-milk specimens from carrier mothers were all HBsAg negative.

Breast Feeding↗
PubMed1975

Vertical transmission of hepatitis B antigen in Taiwan.

To determine the frequency of vertical transmission of hepatitis B antigen (HB5 Ag) from asymptomatic carrier mothers in Taiwan to their offspring, HB5 Ag was sought by radioimmunoassay and complement fixation. Of 158 babies born to carrier mothers, antigenemia developed in 63; 51 of these antigenemic babies had become antigen positive within the six months of life. Three inter-related factors were found to increase the risk that antigenemia would develop in the infant: a high maternal complement-fixation titer for HB5 Ag: presence of HB5 Ag in the baby's umbilical-cord blood: and antigenemia in siblings. In contrast to previous studies, these findings indicate that vertical transmission from carrier mothers frequently occurs, at least in Taiwan, and may partially explain Taiwan's high prevalence of HB5 Ag.

Age Factors↗
PubMed1975

Hepatitis B antigen in infants born to mothers with chronic hepatitis B antigenemia in Taiwan.

Hepatitis B antigen (HB Ag) was detected by complement fixation (CF) in serum samples of 7.5% of 1,106 pregnant Chinese women tested in Taipei, Taiwan. HG Ag persisted in all but one of 42 women followed for 1 to 18 months (average, nine months) after delivery, and 27 of the 43 infants (63%) born to those women became antigen-positive. Persistance of the antigen was more common than transient or intermittent antigenemia. Twelve had antigenemia when first tested, while 15 later developed antigenemia, usually during the first six months of life. Only one infant developed antibody to HG Ag (anti-HB Ag), and this occurred after transient antigenemia. The HB Ag was found in two of 32 (6%) fathers, and in 18 of 27 (67%) older siblings. The antigen was more common among siblings of antigen-positive than among those of antigen-negative infants. These findings demonstrate that in Taiwan, infants born to mothers who are asymptomatic carriers of HB Ag commonly become infected by heaptitis B (HB) virus. Exposure of infants near the time of birth may be important maintaining the high, chronic HB Ag carrier rate in Taiwan.

Carrier State↗
PubMed1975

Sites of organic acid production and pattern of digesta movement in the gastrointestinal tract of geese.

Sixteen geese were used to assess the movement of fluid and particulate digesta through their gastrointestinal tracts and to determine the diurnal variation in organic acid levels for the various segments of the tract. Fluid (polyethylene glycol and chronium-labeled ethylenediaminetetraacetic acid) and particulate markers (2 and 5 mm long) were administered with the meal. Animals were killed at given intervals after the administration of markers. The gastrointestinal tract was divided into nine segments for measurement of markers, pH, volatile fatty acids (VFA), and lactic acid contents. The data indicated a rapid evacuation of fluid marker from the foregut (crop, ventriculus, and proventriculus), while particulate markers were retained for extended periods of time. Retention of fluid marker was observed only within the cecum. Retrograde movement of particulate marker was demonstrated from the duodenum to ventriculus and proventriculus. Retrograde movement of fluid marker was observed from the cloaca to the colon, cecum, and distal third of the small intestine. However, particulate marker showed no retrograde movement in these segments of tract. Highest VFA levels were observed in the cecum. Retention of digesta and production of VFA within the colon were less than those noted for the dog, pig and pony. Lactic acid comprised less than 10% of the organic acids present in the gastrointestinal tract and were at their highest levels in the proximal and mid small intestine.

Animals↗
PubMed1975

Sites of organic acid production and pattern of digesta movement in the gastrointestinal tract of swine.

Twelve swine were used to assess the movement of fluid and particulate digesta through their gastrointestinal tracts and to determine the diurnal variations in organic acid levels for various segments of the tract. Animals were fed twice daily at 12-hour intervals. Fluid (polyethylene glycol and chromium-labeled ethylenediamine-tetraacetic acid) and particulate markers (2 mm OD, and 2 mm and 1 and 2 cm long) were administration of markers. The gastrointestinal tract was divided into 12 segments for measurements of markers, pH, volatile fatty acids (VFA), and lactic acid (LA) contents. The data indicated a rapid evacuation of the fluid and the smaller particles from the stomach and their relatively rapid passage through the small intestine and cecum. There was, however, prolonged retention of both fluid and particulate markers first in the ascending and then in the descending colon. Larger particles (2 cm) were retained in the stomach throughout much of the 60-hour experimental period. LA levels were observed 8 hours postfeeding. The highest levels of VFA in gastric contents averaged 20 mmoles/liter. Gastrointestinal pH values showed significant changes with time postfeeding only within the stomach, where they did not reflect the changes in LA of VFA concentrations. VFA constituted 92% of the organic acids present in the large intestine. Their concentrations varied markedly with time (150-230 mmoles/liter), but the VFA at all times constituted the major anions in the large intestinal contents. The results demonstrated that digesta can be retained for prolonged periods of time in that swine stomach and colon. The high concentrations of organic acids also indicated that substantial degrees of microbial digestion of carbohydrates occurred at both sites.

Animals↗
PubMed1975

Cyclic changes in ionic composition of digesta in the equine intestinal tract.

Effects of diet and time after feeding on osmolality and inorganic ion content of gastrointestinal digesta were studied in 24 ponies. Animals, fed either a conventional or a low-protein, high-cellulose diet, were sacrificed 2, 4, 8, or 12 h after a meal. Animals fed the conventional diet showed cyclic variations in the ionic composition and osmolality of digesta with time after feeding. The most marked variations were seen in the contents of the stomach and small colon. However, results also indicated a cyclic appearance and disappearance of Na in large intestinal contents that correlated with net appearance and disappearance of volatile fatty acid (VFA) and H2O. Since Na and VFA were the major solutes absorbed from the cecum and colon, the ionic composition and water content of large intestinal digesta appeared largely dependent on the rate of microbial digestion. Although the large intestine of animals fed the experimental diet contained approximately twice the quanity of Na, K, Cl, VFA, and H2O, COMPENSATORY ABSORPTION BY THE MOre distal segments of colon resulted in little additional loss of these in the feces.

Animals↗
PubMed1975

Pathogenesis of lead shot poisoning in the mallard duck.

Adult mallard ducks were administered steel pellets to determine the rate of excretion from the gastrointestinal tract. In separate studies the ducks were administered 5 number 6 lead pellets. Birds were examined for clinical signs and sacrificed at given intervals over a 20 day period to assess changes in tissue structure and concentrations of lead with time. The above studies were conducted in 2 groups of ducks, fed a low or a high fiber diet. The rate of steel pellet excretion on birds on the low fiber diet decreased with an increase in pellet size. Pellet excretion was greatly reduced in birds fed the high fiber diet. Administration of lead shot resulted in the development of green diarrhea, anorexia and weakness. It also produced high concentrations of lead in the blood, kidney, liver and bone with lower concentrations in skeletal muscle. The major lesions were destruction of the mitotically active proventricular epithelium and medullary osteocytes, destruction of pectoral muscle cells and the presence of intranuclear inclusion bodies in the proximal tubular epithelium of the kidneys. Birds on the high fiber diet demonstrated more severe clinical signs and higher concentrations of lead in the tissues.

Animals↗