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Biomedical subjects

C E Stevens

Publications and source records attributed to C E Stevens.

At least 127 records · Page 7Linked to original sources
PubMed1981

Prevalence of hepatitis B "e" antigen and its antibody in various HBsAg carrier populations.

A total of 749 persistent carriers of hepatitis B surface antigen (HBsAg) were tested for hepatitis B e antigen/antibody to e antigen (HBeAg/anti-HBe) by a radioimmunoassay method. The prevalence of HBeAg was found to be: 9.1% in carrier-blood donors, 10.3% in mentally retarded patients without Down's syndrome, 23.6% in Chinese-Americans, 35.3% in drug addicts, 39.2% in mentally retarded patients with Down's syndrome, 61.4% in homosexual men, and 71.2% in dialysis patients. The prevalence of HBeAg appears to be independent of sex, race, and HBsAg antigenic subtype. Younger carries tend to be more frequently HBeAg positive than older ones. All individuals acutely infected with hepatitis B virus become at least transiently positive for HBeAg. Appearance or clearance of HBsAg, HBeAg and their corresponding antibodies seem to be interrelated.

Adult↗
PubMed1981

Cellular immune response during uncomplicated genital infection with Chlamydia trachomatis in humans.

A lymphocyte transformation (LT) assay for the study of the cellular immune response to Chlamydia trachomatis in humans is described. Subjects studied included 9 newborns whose mothers were C. trachomatis culture negative, 16 seronegative, sexually inexperienced adults, and 107 patients seen at a sexually transmitted disease clinic, including 31 men presenting with acute nongonococcal urethritis and 76 women with known or suspected uncomplicated gonorrhea or with uncomplicated C. trachomatis genital infection. LT stimulation indices (SI) were less than 3.5 in newborns and normal adults, as well as 11 of 12 seronegative, isolation-negative sexually transmitted disease clinic subjects. LTSI greater than 3.5 was found only with subjects who were sero- or culture positive for C. trachomatis. Among men with nongonococcal urethritis, the LTSI correlated better with culture than with antibody. Among women, the LTSI correlated better with antibody than with culture. LTSI decline significantly 3 to 4 weeks after curative therapy in men with nongonococcal urethritis, suggesting that LT response is short-lived and that the LTSI may be an indicator of acute C. trachomatis infection. The sensitivity, specificity, and predictive value of a positive LT assay and of serum and local antibody tests, in terms of C. trachomatis infection defined as positive isolation, were also compared. The predictive value of a positive LTSI for C. trachomatis infection was generally low in the sexually transmitted disease clinic patients: 62% in men with nongonococcal urethritis and 37% in women. However, this study did show the LT assay to be a useful specific test for monitoring the cellular immune response to C. trachomatis infection.

Antibodies, Bacterial↗
PubMed1981

Absorption of volatile fatty acid, Na, and H2O by the colon of the dog.

Volatile fatty acid (VFA) concentrations were examined in the gastrointestinal tract of dogs 24 and 48 hours after a meal. Small concentrations of VFA were present in the stomach and small intestine. Large concentrations were present in the large intestine at both periods after the meal, but the total quantity was reduced markedly between 24 and 48 hours. Colonic absorption and transport of VFA also were examined with in vitro and in vivo perfusion procedures. Both demonstrate that VFA were rapidly absorbed and that the rate of absorption/cm2 of colonic mucosa ws equivalent to that measured in the pig. In vivo results showed that VFA and Na were absorbed at the same rate, and their absorption showed a parallel increase with a decrease in pH of the perfusate. Absorption of Na and VFA alone could account for osmotic absorption of H2O from the colon. Results indicated that although the total quantity of VFA absorbed by the colon of the dog would be nutritionally insignificant, their absorption is of major importance to normal colonic absorptive processes.

Animals↗
PubMed1980

Hepatitis B vaccine: immune responses in haemodialysis patients.

Antibody to hepatitis B surface antigen (anti-HBs) developed within six months in 80% of haemodialysis patients given either two or three 40 micrograms doses of hepatitis B vaccine. A total of 89% had anti-HBs after a booster dose given six months later. Anti-HBs titres were higher in patients who received three initial doses than in those who received only two doses, but the proportion of anti-HBs-positive patients was the same in the two groups. Male patients became anti-HBs positive less often than females and their antibody titres were lower.

Adult↗
PubMed1980

Hepatitis B vaccine: demonstration of efficacy in a controlled clinical trial in a high-risk population in the United States.

We assessed the efficacy of an inactivated hepatitis B vaccine in a placebo-controlled, randomized, double-blind trial in 1083 homosexual men known to be at high risk for hepatitis B virus infection. The vaccine was found to be safe and the incidence of side effects was low. Within two months, 77% of the vaccinated persons had high levels of antibody against the hepatitis B surface antigen. This rate increased to 96% after the booster dose and remained essentially unchanged for the duration of the trial. For the first 18 months of follow-up, hepatitis B or subclinical infection developed in only 1.4 to 3.4% of the vaccine recipients as compared with 18 to 27% of placebo recipients (P < 0.0001). The reduction of incidence in the vaccinees was as high as 92.3%; none of the vaccinees with a detectable immune response to the vaccine had clinical hepatitis B or asymptomatic antigenemia. A significant reduction of incidence was already seen within 75 days after randomization; this observation suggests that the vaccine may be efficacious even when given after exposure.

Adult↗
PubMed1980

An antigen detected frequently in human sera with elevated levels of alanine aminotransferase: a potential marker for non-A, non-B hepatitis.

In a search for additional antigens associated with virus-induced human liver disease a radioimmunoassay (RIA) was developed using IgG from sera of a multiply transfused person. Polystyrene beads coated with IgG F(ab)'2 fragments, dinitrophenylated F(ab)'2 fragments and 125I-labelled anti-2,4-dinitrophenyl antibodies (Neurath & Strick, 1979) were used in the RIA. An apparently new antigen or the corresponding antibodies were detected in 155 serum specimens from 35/37 (94%)individuals who developed non-A, non-B hepatitis. The antigen was also present in hepatitis B surface antigen-negative sera of blood donors with normal (13.2%) and elevated levels of alanine aminotransferase (34%). The antigen has an approximate mol. wt. of 45,000, a buoyant density of 1.23 g/ml and an isoelectric point of 7.

Alanine Transaminase↗
PubMed1979

HBeAg and anti-HBe detection by radioimmunoassay: correlation with vertical transmission of hepatitis B virus in Taiwan.

A sensitive radioimmunoassay technique was used to detect hepatitis B e antigen (HBeAg). A strong correlation was found between HBeAg positivity of the serum of hepatitis B surface antigen (HBsAg) carrier women in Taiwan and the subsequent development of surface antigenemia in their babies. All babies who became chronic HBsAg carriers were born to HBeAg positive women, maternal HBeAg positivity being a better prior indication of chronic antigenemia developing in the baby than the HBsAg titer in the mother's serum.

Antibodies, Viral↗
PubMed1979

Sites of organic acid production and patterns of digesta movement in the gastro-intestinal tract of the raccoon.

Twelve raccoons were used to assess the movement of fluid and particulate digesta through their gastrointestinal tract and to determine the diurnal variations in organic acid levels for the various segments of the tract. Fluid and particulate markers were administered at the time of meal feeding. Animals were killed at given intervals after the administration of markers. The gastrointestinal tract was removed and divided into seven segments for measurement of markers, pH, volatile fatty acids (VFA) and lactic acid content. The results indicate a rapid transit of the digesta through the entire gastrointestinal tract, with a mean retention time of less than 24 hours for all fluid and particulate markers. Particulate markers up to 2 cm in length were passed rapidly, with limited retention within the tract, much unlike animals with greater gut complexity. The apparent requirements for gut complexity and digesta retention presumably necessary for digestion by gut microflora were not evident in the raccoon. However, even in the absence of these characteristics, microbial fermentation of the ingesta occurred, as evidenced by the levels of organic acids produced. Colonic VFA concentrations achieved levels comparable to levels observed in the ruminants' foregut and the large intestine of the pony. Lactic acid was found throughout the entire gastrointestinal tract.

Animals↗
PubMed1979

Radioimmunoassay of hepatitis B e-antigen (HBeAg): identification of HBeAg not associated with immunoglobulins.

A radioimmunoassay for hepatitis B e-antigen (HBeAg) is described. Polystyrene beads coated with IgG prepared from a human serum containing antibodies to HBeAg (anti-HBe) and anti-HBe IgG labelled with 125I-p-hydroxyphenylpropionic acid N-hydroxysuccinimide ester were used in the test. The radioimmunoassay was approximately 1,000-fold more sensitive than immunodiffusion. At least a transient presence of HBeAg in serum appears to be a common feature of infections by hepatitis B virus. The radioimmunoassay was instrumental in establishing conditions for identification of apparently free monomeric HBeAg. The HBeAg has an approximate mol. wt.of 35,000 and was recovered after isoelectric focusing in fractions with a pH between 4.25 and 4.8. Polyacrylamide gel electrophoresis revealed the presence in HBeAg of a polypeptide with an apparent mol. wt. of 17,000.

Hepatitis B Antigens↗
PubMed1978

Physiological implications of microbial digestion in the large intestine of mammals: relation to dietary factors.

The rate of digesta marker passage through the large intestine of the dog, pig, and pony correlated with the relative length and degree of sacculation of the colon. Volatile fatty acids (VFA), the end products of microbial digestion of all forms of carbohydrate, were the major anions present in large intestinal contents of all three species. Total VFA concentration was little affected by the feeding of high-versus low-fiber diets. VFA were rapidly transported across colonic mucosa of all three species. Results of comparative studies indicate that production and absorption of VFA are important to the nutrition of some mammals and to the normal secretory and absorptive functions of the large intestine of most mammals.

Animals↗
PubMed1978

Hepatitis A virus infection: new insights from seroepidemiologic studies.

The prevalence of exposure to hepatitis A virus (HAV) increases with increasing age; decreases with increasing socioeconomic class; increases with increasing serologic evidence of prior hepatitis B virus (HBV) exposure but is much more common than HBV exposure; is independent of sex and race; varies in different parts of the world as a function of hygienic, developmental, and unrecognized geographic factors; and is not affected by immune deficiency or immaturity. Transmission of type A hepatitis is enhanced by poor personal hygiene such as that seen in institutions for the mentally retarded. On the other hand, there is no increased exposure to HAV among homosexuals, who have frequent and intimate contact with multiple sexual partners; among hemodialysis patients and staff; or among multiply transfused individuals, all of whom are at significantly increased risk of exposure to HBV. No epidemiologic evidence has confirmed the existence of viremic or intestinal carriers of HAV, and the virus is rarely, if ever, spread by parenteral mechanisms. Finally, HAV appears to play no role in chronic liver disease and a very minor role in fulminant hepatitis; however, HAV is responsible for a sizable proportion (approximately 20%--40%) of sporadic hepatitis among urban adults.

Age Factors↗
PubMed1978

Radioimmunoassay and some properties of human antibodies to hepatitis B core antigen.

A solid-phase radioimmunoassay for antibodies to hepatitis B core antigen (anti-HBc) is described. Polystyrene beads coated with anti-HBc, hepatitis B core antigen prepared from pooled sera of humans infected with hepatitis B virus (HBV) and 125I-labelled anti-HBc were used for the test. Distinct patterns of development and changes of anti-HBc and their immunologic properties are all related to variations of other markers specific for HBV infections. Knowledge concerning the detailed features of the immune response to hepatitis B core antigen may provide deeper insight into the pathogenesis of HBV infections.

Antibodies, Viral↗
PubMed1978

Non-A, non-B hepatitis transmission in chimpanzees: a project of the transfusion-transmitted viruses study group.

Experimental transmission of non-A, non-B hepatitis was apparently accomplished in 5 chimpanzees following inoculation with presumably infectious human sera. Administration of sera from implicated donors with normal alanine aminotransferase (ALT) values, as well as from those with abnormal ALT levels, resulted in the development of ALT abnormalities in the inoculated chimpanzees. Transmission from donors with normal ALT values implies that healthy carriers of non-A, non-B virus exist. Evidence is presented which indicates that a period of viremia precedes the clinical illness by at least 12 days.

Alanine Transaminase↗
PubMed1977

Antibody to hepatitis A antigen in institutionalized mentally retarded patients.

Institutionalized patients with Down syndrome and matched controls with other causes of mental retardation were tested by immune adherence hemagglutination for the presence of antibody to hepatitis A antigen (anti-HA). Altogether 75.1% (175 of 233) exhibited presence of anti-HA, with no differences by sex or age. Patients reactive for hepatitis B surface antigen (HBsAg) or its antibody (anti-HBs) were reactive for anti-HA significantly more frequently than those with a negative reaction for these markers. In contrast to serologic markers of hepatitis type B, prevalence of anti-HA does not depend on the cause of mental retardation or on the age at primary infection. The rate of anti-HA positivity was found to be closely correlated with duration of institutionalization. The study confirmed that many closed institutions for the mentally retarded are hyperendemic for hepatitis type A and that formation of anti-HA is not greatly affected by either immune deficiency or immune immaturity.

Adolescent↗