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Biomedical subjects

C E Stevens

Publications and source records attributed to C E Stevens.

At least 109 records · Page 6Linked to original sources
PubMed1984

The large bowel--a supplementary rumen?

The rumen and the mammalian large intestine are similar in many respects. Microbial protein appears to be synthesized and degraded in the digesta of both organs in a comparable manner. The VFA end-products of carbohydrate fermentation are produced in similar concentrations. Digesta pH is maintained with buffer added by the saliva or ileal fluid, HCO3 released into the lumen and rapid absorption of the organic acids. VFA are absorbed at equivalent rates by rumen epithelium and large intestinal mucosa. Over-production of VFA produces similar adverse effects. There is a considerable amount of species variation in the relative length and volume as well as the extent of sacculation of the large intestine. The caecum is the primary site for retention of digesta and microbial fermentation in the large intestine of rabbits, rodents and a few other species. However, the proximal colon is the major site of retention and fermentation in most mammals. Absorptions of Na and VFA appear to account for absorption of most of the water removed during passage of digesta through the large intestine. A relatively slow rate of Na absorption and release of HCO3 appears to provide the fluid and buffering capacity needed for efficient microbial digestion in the rumen and in the large intestine of some species. A more rapid absorption of Na by the large intestine of other species would aid in the conservation of Na and water. The many similarities between the large intestine and the rumen suggest that further comparison can provide additional information on both the function and diseases of these two organs. The rumen has proved to be accessible to a variety of procedures useful for the study of microbial digestive processes and its epithelium has provided a non-glandular tissue for studies of inorganic ion transport as well as the transport and metabolism of VFA. Comparative studies of the large intestine also can provide a better understanding of the functions and malfunctions of the human large intestine. The pig and some species of monkey would appear to be most suitable for examining the effects of diet and carbohydrate malabsorption. The equine large intestine provides a good system for studying events, such as those associated with the recycling of nitrogenous compounds. Furthermore, as demonstrated by comparative studies of the kidney and other organs, a great deal of information can be gained through examination of the various mechanisms that have been developed to serve similar functions.

Animals↗
PubMed1984

Hepatitis B virus antibody in blood donors and the occurrence of non-A, non-B hepatitis in transfusion recipients. An analysis of the Transfusion-Transmitted Viruses Study.

Patients who received transfusions and nontransfused control patients were followed to assess the incidence and cause of post-transfusion hepatitis and to identify donor factors that might relate to risk of hepatitis. We evaluated as risk factors in donors the presence of antibody to hepatitis B virus compared with elevated alanine aminotransferase (ALT) level. Units of blood that were positive for antibody to hepatitis B core antigen (anti-HBc) were associated with a twofold to threefold greater risk of non-A, non-B hepatitis in the recipients than were units without anti-HBc. In the absence of specific serologic tests for non-A, non-B agents, screening of donors for anti-HBc might be considered. Our data suggest that the incidence of non-A, non-B hepatitis might have been reduced by about one third by such screening. However, elevated ALT levels in donors had a similar association with non-A, non-B hepatitis in recipients but would have resulted in fewer units of blood being discarded than would screening for anti-HBc.

Alanine Transaminase↗
PubMed1983

Baseline epidemiological studies for a hepatitis B vaccine trial in Kangwane.

Hepatitis B markers were determined by radioimmunoassay of serum samples from 1 495 Black subjects representative of the resident population of Kangwane, a rural area with a high incidence of chronic liver disease and hepatocellular carcinoma. Pregnant women formed an important part of the study group, since it was intended to assess the frequency of perinatal transmission and the passive immunity of their infants, two factors which would markedly influence an infant immunization programme. A high overall marker positivity rate was found, indicating that hepatitis B is endemic. The hepatitis B surface antigen (HBsAg) carrier rate was 14,6% in adult males and 4,6% in adult females, while 82.6% of adult males and 69,4% of adult females were positive for at least one marker, indicating that infection had been present at some stage. Of infants under 1 year of age 34,5% were positive for antibodies to HBsAg (anti-HBs), compared with 9,3% at 13-24 months, which indicates that transplacental transfer of anti-HBs is frequent. Other markers were acquired even in the 1st year of life, with the sharpest increase at 3-11 years. Perinatal transmission was not common, however, and horizontal transmission during early childhood seemed to play an important role. It was concluded that the risk and frequency of infection justified a vaccine trial in this population and that the target group for vaccination should be infants under 1 year of age.

Adolescent↗
PubMed1983

Immunogenicity of HBV vaccine in healthy Chinese children.

The immunogenic response of healthy Chinese children to three different doses of hepatitis B virus (HBV) vaccine was compared. One hundred susceptible children received two doses of 10, 20 or 40 micrograms a month apart. A month following the first dose 33% of all the children had antibodies. The response rate rose to 78% a month later and 99% four months later. Ninety percent of the 100 children still had antibody at 12 months after vaccination was initiated. The response rate, antibody levels and persistence of antibody were directly related to the dose of vaccine and inversely to the age of children. No adverse reactions were observed.

Child↗
PubMed1983

Immune response to hepatitis B vaccine in newborns.

Three injections of 10 microgram/ml hepatitis B vaccine (Merck) given in the first week after birth, a month later and again at the age of six months to 63 neonates in a rural African population, elicited an antibody response in 93 per cent. The initial hepatitis B marker status of the babies and mothers did not influence the results at nine months. Side-effects were minor and we conclude that the vaccine can effectively and safely be used from birth in endemic situations.

Female↗
PubMed1983

HBIG prophylaxis for perinatal HBV infections--final report of the Taiwan trial.

A randomized double blind placebo controlled efficacy trial of hepatitis B immunoglobulin (HBIG) for prevention of the mother to infant transmitted HBsAg carrier state was conducted in Taiwan where the carrier rate in the general population is 15% to 20%. HBIG was given immediately after birth to infants of e antigen positive HBsAg carrier mothers and all infants were followed for at least 15 months. Among 61 placebo recipients the carrier rate was 92%; compared with 26% among 57 infants who received 0.5 ml HBIG at birth, three months and six months and 54% among 67 infants who received a single 1.0 ml dose of HBIG at birth only. Efficacy was 71% and 42% respectively for the two treatment schedules. The most common response of HBIG-treated infants was passive-active immunization which was 27% in single dose group and 61% in three doses group. Some of the infants who became carriers were probably infected as HBIG protection waned and we expect that higher efficacy can be achieved by HB vaccine in conjunction with HBIG.

Carrier State↗
PubMed1982

Hepatitis B vaccine in medical staff of hemodialysis units: efficacy and subtype cross-protection.

We evaluated the efficacy of hepatitis B vaccine (Heptavax-B) containing only the ad subtype in a randomized, placebo-controlled, double-blind trial among 865 staff members of 43 hemodialysis units in the United States. Surface antibody developed in 92.6 per cent of the subjects after two doses of vaccine and in 96 per cent after the six-month booster. The incidence of infections with hepatitis B virus (with or without hepatitis) was 9.9 per cent in placebo recipients and 2.2 per cent in vaccine recipients (P less than 0.01). The two cases of hepatitis B among vaccine recipients did not occur in subjects in whom antibody had developed. In 81 per cent of the hepatitis events, the virus was of the ay subtype. The indicence of ay virus was 8.2 per cent among placebo recipients and 1.2 per cent among vaccine recipients (P less than 0.005). We conclude that these data confirm the efficacy of the vaccine and demonstrate subtype cross-protection.

Adult↗
PubMed1982

Incidence of hepatitis B virus infections in preschool children in Taiwan.

To determine the incidence of infections with hepatitis B virus (HBV) among Chinese preschool children, 1,510 children (mean age, 29 months) were tested for HBV markers; 15.9% were infected with HBV (7.8% positive for hepatitis B surface antigen [HBsAg] and 8.1% positive for antibody to HBsAg) and 84.1% were susceptible when the children were enrolled in the study. The average length of follow-up was 2.1 years among 1,110 children. Among the 924 susceptible children who were followed up, 10.6% had seroconversions for HBV markers, none of which was associated with clinical illness; the annual incidence of HBV infections was 5.0%. Among the 98 children who experienced HBV infections during the study, 23% became HBsAg carriers, and HBsAg persistence was age-related, with most carriers being among the youngest children infected. In contrast, among the children with HBV markers at the time of enrollment, 118 (49.2%) were HBsAg-positive and 86% were still positive on follow-up. The incidence of HBV infections was significantly associated with the frequency of previous injections.

Age Factors↗
PubMed1982

Hepatitis B vaccine administered to chronic carriers of hepatitis b surface antigen.

We administered up to 6 monthly doses of hepatitis B vaccine to 16 chronic carriers of hepatitis B surface antigen (HBsAg) in an attempt to eliminate the antigen. The HBsAg in this vaccine differs from native antigen. No patients had elimination of HBsAg, but one of 10 no longer carried hepatitis B e antigen (HBeAg), Of 13 patients without preexisting antibody to HBsAg (anti-HBs), none acquired the antibody; two of three patients with preexisting heterotypic anti-HBs had transient, low-level increases in anti-HBs titers. Serum alanine aminotransaminase (ALT) levels fell in eight patients, remained unchanged in six, and increased transiently in two. Decreased ALT and HBeAg clearance, however, did not seem to be related to vaccination, and the transient ALT elevations appeared to represent sporadic, acute non-A, non-B hepatitis. No adverse effects other than sore arm and joint pain were seen. Immunization of chronic HBsAg carriers with hepatitis B vaccine, although ineffective in eliminating HBsAg, appeared to be safe. Such safety, if confirmed, would simplify the design of hepatitis B vaccination programs.

Adult↗
PubMed1982

Therapy of cervical chlamydial infection.

The treatment of cervical Chlamydia trachomatis infection in nonpregnant women was evaluated in a double-blind randomized study. Objective criteria were used to assess the response of cervicitis to therapy. Fifty patients were treated with tetracycline hydrochloride, 500 mg orally four times daily, and 50 patients were treated with rosaramicin, 250 mg orally four times daily, both for 7 days. Both agents were highly effective in eradicating C trachomatis. Both produced significant improvement in objective signs of cervicitis: eliminating mucopurulent endocervical discharge and edema of ectopy, and decreasing the clinical severity score of cervicitis. This trial shows that the 1-week course of tetracycline hydrochloride currently recommended for treatment of chlamydial urethritis in men is also highly effective for the treatment of chlamydial cervical infection in women. Rosaramicin, a macrolide antibiotic, was equally effective but produced a higher rate of gastrointestinal side effects.

Chlamydia Infections↗
PubMed1981

Serum alanine aminotransferase of donors in relation to the risk of non-A,non-B hepatitis in recipients: the transfusion-transmitted viruses study.

To evaluate the incidence of post-transfusion hepatitis and factors influencing its occurrence, the Transfusion-Transmitted Viruses Study prospectively followed 1513 transfusion recipients from 1974 through 1979. The attack rate for non-A,non-B hepatitis was 10 per cent. The incidence of hepatitis was directly related to the alanine aminotransferase (ALT) level in blood donors. In recipients of multiple transfusions of blood that had no donor-ALT level above 29 IU per liter the attack rate was 6 per cent or less; at higher donor-ALT levels the attack rate increased progressively, reaching 45 per cent in recipients of units with an ALT of 60 IU or greater. A similar relation was observed among recipients of single units of blood. Moreover, hepatitis developed in 10 of 11 recipients of two units with an ALT level of 45 IU or greater. These data indicate that screening blood for ALT levels would reduce the incidence of non-A,non-B post-transfusion hepatitis.

Adolescent↗
PubMed1981

Passive-active immunisation against hepatitis B: immunogenicity studies in adult Americans.

Three sex and age matched groups of medical personnel, 20-40 individuals in each, received a course of hepatitis B vaccine: in one group the first dose of vaccine was given a month after injection of hepatitis B immune globulin; in the second, vaccine and immune globulin were given simultaneously; and, in the third, vaccine was given alone. The passively acquired antibody did not interfere with an active immune response to the vaccine. Both the timing of antibody appearance and the antibody titres were similar in the three groups, and the actively acquired antibody persisted for the 8 months of follow-up. Administration of the vaccine together with hepatitis B immune globulin will provide immediate protection, whereas people who receive vaccine alone may lack antibody for several months. This opens new possibilities for post-exposure prophylaxis.

Adult↗
PubMed1981

The immune response of healthy adults to a reduced dose of hepatitis B vaccine.

Three hundred thirty-six medical personnel from hemodialysis centers were treated with three doses, 20 microgram each, of the Merck hepatitis B vaccine (at 0, 1, and 6 months). Within 1 month after the first injection, 41% converted to anti-HBs positivity; after the second injection the conversion rate rose to 80-90%; and after the booster, to 96-98%. The later rate remained unchanged during the 18-month follow-up period. Only 2.8% of those vaccinated did not respond to the vaccine. The patterns of immune responses to 20-microgram doses were found to be exactly the same as to 40-microgram doses. It is suggested that reduced doses of vaccine should be as efficacious as the larger ones.

Adult↗