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Biomedical subjects

W L Heyward

Publications and source records attributed to W L Heyward.

62 records · Page 4Linked to original sources
PubMed1985

The control of hepatitis B virus infection with vaccine in Yupik Eskimos. Demonstration of safety, immunogenicity, and efficacy under field conditions.

In 1981, a hepatitis B vaccine demonstration project was initiated among Yupik Eskimos of southwest Alaska to demonstrate that, under field conditions, the vaccine was safe, immunogenic, and efficacious. Laboratory tests for serologic markers of hepatitis B virus infection (HBsAg, anti-HBs, and anti-HBc) performed on sera collected in May 1981 from 3,988 residents of 17 remote Eskimo villages revealed that 2,645 (66.3%) had no evidence of hepatitis B virus infection. Because of a limited supply of vaccine, specific criteria for selection were used so that those at highest risk of infection would be immunized first. In November 1981, the first dose of vaccine was administered to 1,693 carefully selected individuals. The second dose was administered to 1,678 (99.1%) of those who received the first dose, and the final dose was administered to 1,630 persons (96.3%). Serologic follow-up showed the vaccine to be safe (0.4% experienced minor adverse reactions) and immunogenic (97.4% developed antibody). Vaccine-induced antibody levels were significantly higher for persons less than 30 years of age (p less than 0.001) and for females (p less than 0.001). Vaccine recipients were also protected from hepatitis B virus infection (p = 0.002). This public health measure proved to be feasible and effective in this remote arctic population despite difficult conditions for delivery and administration of this temperature-sensitive vaccine. This strategy for immunization is now being applied on a larger scale in Alaska as part of a program for the primary prevention of this infection and its sequelae.

Adolescent↗
PubMed1984

Epidemiological analysis of the significance of low-positive test results for antibody to hepatitis B surface and core antigens.

To determine the significance of certain serological test results commonly encountered in hepatitis B virus testing, we reviewed serological test data from nine studies of hepatitis B conducted between 1980 and 1982. Three tests, for hepatitis B surface antigen and for antibodies to hepatitis B surface antigen and hepatitis B core antigen (anti-HBs and anti-HBc), were used to measure hepatitis B virus infection risk in various populations. Two results, low levels of anti-HBs alone and low levels of anti-HBc alone, occurred at constant frequencies (2.72 and 0.4%, respectively), regardless of the prevalence of HBV infection in the population. Positivity for low levels of anti-HBs alone persisted for 1 year in less than one-half of those studied; in addition, response to hepatitis B virus vaccine was augmented in only one-third of this group. Positivity for low levels of anti-HBc alone did not persist in any of 11 persons studied. These findings indicate that presently available tests for anti-HBs and anti-HBc at low levels are often nonspecific and should be interpreted with caution.

Alaska↗
PubMed1983

Early detection of primary hepatocellular carcinoma by screening for alpha-fetoprotein in high-risk families. A case-report.

Serum levels of alpha-fetoprotein (AFP) may be raised for up to 2 years before clinical presentation of primary hepatocellular carcinoma (PHC). A group of people judged to be at high risk of PHC because of long-term serological positivity for hepatitis B surface antigen, ethnicity, location of residence, and a strong family history of PHC were screened for increasing levels of AFP. After 1 1/2 years of twice-yearly screening, one of them, a 19-year-old Eskimo man, had a raised AFP level, which continued to rise rapidly over the next 3 months, although the patient remained symptomless and ultrasonography, 99mTc-scan, and computerised tomography of the liver were negative. Hepatic angiography suggested a small tumour in the periphery of the right lobe of the liver, but at laparotomy the right lobe was normal. Instead a tumour was found in the lateral tip of the left lobe. The tumour, a PHC, was resected surgically, and the patient has been well in the 11 months since his operation. His serum AFP level returned to normal 2 weeks after the operation and has remained normal.

Adult↗
PubMed1983

Prevalence of hepatitis B in selected Alaskan Eskimo villages.

Sera collected in 1973-1975 from 3053 residents of 12 selected Alaskan Eskimo villages were tested for evidence of hepatitis B virus infection. Overall, hepatitis B surface antigen (HBsAg) was found in 6.4% of those tested. Evidence of hepatitis B infection (positive for HBsAg or antibody to hepatitis B surface antigen (anti-HBs] varied considerably by village, from 4.6% to 69.9%, and increased with advancing age. The proportion with HBsAg was significantly higher in those under the age of 13 years, and the male/female ratio varied from 0.9 to 1.5 to 1.5 in the prepubertal, postpubertal-premenopausal, and postmenopausal age groups, respectively. The prevalence of hepatitis B e antigen (HBeAg) in HBsAg-positive persons decreased with advancing age, and conversely, the prevalence of antibody to hepatitis B e antigen (anti-HBe) increased with age. Hepatitis B infection was found to be sporadically distributed, with great village-to-village variation and further variation by household within most villages. The high HBsAg and HBeAg seropositivity observed in children suggests that children are both more recently infected with hepatitis B and are more involved in hepatitis B transmission in these villages.

Adolescent↗
PubMed1982

Serological markers of hepatitis B virus and alpha-fetoprotein levels preceding primary hepatocellular carcinoma in Alaskan Eskimos.

The availability of stored sera that had been obtained for other investigations permitted examination of the sequential development of hepatitis B virus (HBV) infection markers and alpha-fetoprotein (AFP) in persons who later developed primary hepatocellular carcinoma (PHC). 9 of the 11 PHC subjects had markers of HBV infection. The results showed that HBV infection could have occurred as little as 10 years before the recognition of PHC. Seroconversion from HBeAg to anti-HBe and significant rises of AFP levels occurred as long as 6 years and 2 years, respectively, before clinical onset of PHC. The finding that anti-HBe seems to precede the rise in AFP by several years suggests that in populations with a high incidence of HBV-associated PHC, or in families with high risk of PHC, the best use of AFP screening may be to monitor HBsAg carriers after seroconversion from HBeAg to anti-HBe.

Adolescent↗
PubMed1981

Primary hepatocellular carcinoma in Alaskan natives, 1969-1979.

The records of 20 Alaskan Native patients with primary hepatocellular carcinoma (PHC) diagnosed in the 11-year period 1969-1979 were reviewed. The annual incidence of PHC was found to be high among Alaskan Native males and especially high among Alaskan Eskimo males (7.6 and 11.2 per 100,000 respectively) in comparison to Greenland and Canadian Eskimos and US white males. Familial and geographic clustering of PHC patients was noted in areas known to be hyperendemic for hepatitis B virus (HBV) infection. A bimodal age distribution among PHC patients occurred with peaks at 15-25 years and 40-65 years. A high prevalence of hepatitis B surface antigen (HBsAg) in serum of patients in the younger age group suggests that HBV infection might be a factor associated with the development of PHC in young Eskimos. PHC in Alaskan Natives is apparently not closely associated with alcoholic cirrhosis.

Adolescent↗