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Biomedical subjects

R S Koff

Publications and source records attributed to R S Koff.

At least 55 records · Page 3Linked to original sources
PubMed1995

Seroepidemiology of hepatitis A in the United States.

The seroepidemiology of hepatitis A depends on the biologic features of the agent. Hepatitis A virus (HAV) is shed in the stool, and infectivity titers are significantly higher for stool than for other body materials. As a consequence, the predominant mode of spread is through fecal-oral routes. Common-source vectors include contaminated foods, water, and bivalve mollusks. Risk factors include contact with a person with hepatitis A, attendance or employment at a day care center, recent international travel, exposure to infected food or water during an outbreak, homosexual activity, and injecting drug use. No known risk factors are identified in many cases. Almost 40% of individuals in the United States are seropositive for prior HAV infection, and rates increase with age, perhaps reflecting an aging cohort of persons infected in earlier times when the infection was more common. Not unexpectedly, this decrease in current infection rates has increased the number of susceptible persons.

Hepatitis A↗
PubMed1995

Preventing hepatitis A infections in travelers to endemic areas.

In 1995, 24 million travelers from the United States are anticipated to visit developing countries where hepatitis A is endemic. Passive immunization with immune globulin, before exposure or within two weeks following exposure to the hepatitis A virus, protects against clinical disease in < 70-90% of immunized individuals. The duration of protection, measured in months, is relatively short. Active immunization with a single dose of inactivated hepatitis A virus vaccine appears to provide greater protective efficacy and, based on the persistence of vaccine-induced protective antibodies, should provide protection for years. Booster doses given between six and 12 months are likely to provide immunity that may persist for at least a decade. The inactivated hepatitis A vaccine approved for use in the United States has been clinically well-tolerated; mild transient soreness at the injection site is the most frequently reported adverse reaction. Immunization with inactivated hepatitis A vaccine is a safe and effective method for travelers to endemic areas to protect themselves against this infection.

Cost-Benefit Analysis↗
PubMed1995

Alcohol consumption and the risk of major upper gastrointestinal bleeding.

OBJECTIVE: To examine the association between current alcohol consumption and major upper gastrointestinal bleeding. METHODS: In a case-control study in the United States, Sweden, and Hungary, 1004 incident cases with upper gastrointestinal bleeding without predisposing factors were compared with 2446 controls. Relative risks for categories of alcohol consumption (based on the number of drinks currently consumed/wk) were estimated using logistic regression; the potential confounding effects of cigarettes, nonsteroidal anti-inflammatory drugs, and other factors were controlled simultaneously. RESULTS: Compared with drinkers of < one drink/wk, the relative risks among other current drinkers ranged from 0.8 for 1-6 drinks/wk to 6.3 for > or = 35 drinks; the trend was statistically significant (p < 0.001). A significantly increased relative risk was seen for the heaviest consumption category within various subgroups: gastric and duodenal hemorrhage; males and females; age < 60 yr and > or = 60 yr; and those who consumed beer, wine, liquor, or a combination of beverages. CONCLUSIONS: These findings provide evidence that consumption of alcohol increases the risk of major gastric and duodenal bleeding in nonpredisposed individuals.

Adult↗
PubMed1994

Problem hepatitis viruses: the mutants.

Genetic variations in the known human hepatitis viruses are probably the result (a) of high viral replication rates and poor or absent proofreading ability intrinsic to RNA viruses (HAV, HCV, HDV, HEV) and (b) to a DNA virus (HBV) that uses a reverse-transcription mechanism for genomic replication. Nucleotide substitutions, deletions, duplications, insertions, and rearrangements resulting in amino acid changes may have no consequences, may impair replication, change host susceptibility, or may lead to escape from immune attack. Genetic diversity has been identified in each of the known hepatitis viruses. The importance of mutant viruses in pathogenicity, immunity, natural history, clinical outcomes, vaccine production, and responsiveness to treatment has emerged as an area for intensive study.

Hepatitis Viruses↗
PubMed1994

Idiopathic autoimmune chronic hepatitis triggered by hepatitis A.

Hepatitis A virus (HAV) infection is a well-recognized cause of acute hepatitis with jaundice in adults. However, chronic sequelae of HAV infection are so rare and so poorly defined that their existence remains speculative. In this report we describe a middle-aged woman in whom serologically defined acute hepatitis A appeared to trigger the onset of autoimmune chronic active hepatitis. This and two previously reported cases suggest that in certain individuals, presumably with a genetic predisposition to the development of autoimmune hepatitis, HAV infection may be the precipitating event in the pathogenesis of this disorder.

Autoimmune Diseases↗
PubMed1993

Alpha-fetoprotein glycosylation is abnormal in some hepatocellular carcinoma, including white patients with a normal alpha-fetoprotein concentration.

Lectin-affinity analyses with Lens culinaris agglutinin (LCA) and other lectins have demonstrated that the glycosylation of alpha-fetoprotein (AFP) secreted by hepatocellular carcinomas (HCC) is frequently altered when the serum AFP concentration is increased. To determine if AFP LCA-binding properties are altered in patients with HCC whose serum AFP concentration is normal, the percentage of LCA-binding AFP in serum from white newborns, white normal adults, white patients with chronic hepatitis and hereditary tyrosinemia and white and black patients with HCC were determined. The serum LCA-binding AFP fraction was low in newborns (1-4%) and normal adults (1-8%). There was a significant increase in LCA-binding AFP in patients with chronic hepatitis (10-24%) and hereditary tyrosinemia (5-35%). The AFP LCA-binding fraction was clearly abnormal (greater than 40%) in three of the white patients with an HCC and a normal serum AFP concentration, and the range of values (10-63%) in these HCC patients was similar to that seen in both white and black patients with HCC accompanied by increased AFP concentrations.

Adult↗
PubMed1993

Nonsteroidal anti-inflammatory drug use in relation to major upper gastrointestinal bleeding.

In a study in the United States, Sweden, and Hungary, 335 cases of gastric bleeding without predisposing factors were compared with 670 control subjects, and 239 cases of duodenal bleeding were compared with 489 control subjects. For aspirin taken at least every other day during the week before the onset of bleeding (regular use), the relative risk of gastric bleeding was 4.4 (95% confidence interval [CI], 2.9 to 6.7); for occasional use, it was 3.3 (95% CI, 2.1 to 5.0). For ibuprofen, the corresponding estimates were 1.0 (95% CI, 0.4 to 2.6) and 1.1 (95% CI, 0.5 to 2.4). For naproxen, the estimate for regular use was 4.0 (95% CI, 1.5 to 11). The estimates for any use of piroxicam (crude estimate), indomethacin, and diclofenac during the week before onset were 18 (95% CI, 4.1 to 83), 1.6 (95% CI, 0.4 to 5.9), and 0.9 (95% CI, 0.2 to 4.2), respectively. The corresponding relative risks of duodenal bleeding were 7.1 (95% CI, 4.2 to 12) and 2.2 (95% CI, 1.3 to 3.7) for the regular and occasional use of aspirin, 2.4 (95% CI, 0.5 to 11) and 0.8 (95% CI, 0.3 to 2.0) for ibuprofen, 12 (95% CI, 2.8 to 54) and 9.9 (95% CI, 2.3 to 44) for naproxen, 17 (95% CI, 3.6 to 79) for any use of piroxicam (crude estimate), and 1.7 (95% CI, 0.2 to 14) for any use of indomethacin. There was a significant trend in the risk of gastric bleeding with increasing dose of regular aspirin use (p = 0.002). The relative risk estimates for the regular use of 325 mg or less were significantly elevated for both gastric and duodenal bleeding at 3.1 and 6.4, respectively.

Aged↗
PubMed1993

Hepatitis B today: clinical and diagnostic overview.

The hepatitis B virus is a member of an unusual family of noncytopathogenic, hepatotropic DNA viruses--the hepadnaviruses. The complete virus comprises a lipoprotein coat, the hepatitis B surface antigen, enveloping a nucleocapsid core that contains a small, circular DNA molecule. Four open reading frames have been identified on the hepatitis B virus DNA genome. They encode seven proteins, including a hepatitis B virus DNA polymerase molecule with reverse transcriptase activity. The replication of the virus resembles that of retroviruses and occurs predominantly but not exclusively in hepatocytes. Virus variants involving genomic mutations have been identified. Testing for hepatitis B surface antigen permits detection of many but not all acutely infected patients. Diagnosis of acute infection rests on the identification of IgM antibodies to the hepatitis B core antigen. Antibody to hepatitis B surface antigen appears in serum during the convalescent phase of hepatitis B virus infection. It is the neutralizing, protective antibody largely responsible for immunity to reinfection. In persistent infection hepatitis B surface antigen is present, antibody to hepatitis B core antigen is predominantly an IgG antibody, antibody to hepatitis B surface antigen is not detectable or is present in very low titers and viral replication may be active. Persistent infection leads to an asymptomatic carrier state, chronic hepatitis, cirrhosis and hepatocellular carcinoma. No specific treatment exists for acute hepatitis B virus infection. Current data indicate that approximately 50% of adults who have chronic infection achieve virologic, biochemical and histologic remission from treatment with alpha-2b-interferon.

Hepatitis B↗