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Biomedical subjects

A Z Kapikian

Publications and source records attributed to A Z Kapikian.

At least 37 records · Page 2Linked to original sources
PubMed1978

Enzyme-linked immunosorbent assay for identification of rotaviruses from different animal species.

Rotaviruses cause gastroenteritis in man and a wide variety of animal species. They cross-react in many immunologic tests and have a similar appearance by electron microscopy, making differentiation among them difficult. Rotaviruses derived from different host species were distinguished by postinfection serum blocking virus activity in an enzyme-linked immunosorbent assay (ELISA). Thirty-three rotavirus isolates from children living in three different parts of the world could not be differentiated by this technique, but they were distinct from four strains recovered from calves, and a series of strains isolated from piglets, foals, monkeys, and infant mice. The four bovine strains were similar, but they could be differentiated from the other animal strains, each of which exhibited a distinct pattern when tested by the ELISA blocking technique.

Animals↗
PubMed1978

Prophylactic doxycycline for travelers' diarrhea. Results of a prospective double-blind study of Peace Corps volunteers in Kenya.

We performed a randomized double-blind study to determine the efficacy of doxycycline (100 mg daily) in preventing travelers' diarrhea among 39 Peace Corps volunteers during their first five weeks in Kenya. The volunteers took either doxycycline or placebo for three weeks and were observed for an additional two weeks. Nine of 21 taking placebo and one of 18 taking doxycycline had travelers' diarrhea during the treatment period (P = 0.012). The protection seemed to persist for at least one week after the drug was stopped. Enterotoxigenic Escherichia coli was the only pathogen isolated from the placebo group, but was not detected in persons taking doxycycline. None of these organisms were resistant to doxycycline or tetracycline, whereas resistance to tetracyclines and other antibiotics was common among the nonenterotoxigenic Esch. coli. We conclude that doxycycline effectively prevented most episodes of travelers' dirrhea.

Adult↗
PubMed1978

Experimental infection of chimpanzees with the Norwalk agent of epidemic viral gastroenteritis.

A fecal filtrate of human origin containing the Norwalk agent of epidemic viral gastroenteritis was administered by stomach tube to chimpanzees in an attempt to induce diarrheal disease. Significant postchallenge serum antibody rises against Norwalk viral antigens were demonstrated in all animals using the techniques of immune electron microscopy and radioimmunoassay. In addition, viral antigens were detected in feces from five of nine animals using radioimmunoassay. Clinical illness characterized by diarrhea and/or vomiting did not occur. Infection was transmitted subsequently by feeding four additional chimpanzees a fecal filtrate prepared from one of the previously infected animals. Development of an antibody response in four animals and detection of viral antigen in two animals that received this passage filtrate indicated that viral replication had occurred in the absence of clinical illness. The availability of the chimpanzee as an experimental animal host susceptible to infection with the Norwalk agent should facilitate the study of epidemic viral gastroenteritis.

Animals↗
PubMed1978

Solid-phase microtiter radioimmunoassay for detection of the Norwalk strain of acute nonbacterial, epidemic gastroenteritis virus and its antibodies.

The development of microtiter solid-phase radioimmunoassays for the detection of Norwalk antigen and its antibody is described. The tests are simple to perform and are sensitive and specific. The test for antigen can be used on crude stool filtrates and suspensions. Both tests are at least as sensitive as immune electron microscopy and more sensitive than immune adherence assay.

Animals↗
PubMed1978

Prevalence of antibody to the Norwalk agent by a newly developed immune adherence hemagglutination assay.

An immune adherence hemagglutination assay (IAHA) for the detection of antibody to the Norwalk agent of acute epidemic nonbacterial gastroenteritis was developed using as antigen virus purified from stool from an experimentally infected volunteer. The assay was sensitive and specific and was efficient for detecting Norwalk antibody seroresponses. The prevalence of Norwalk antibody in various groups in the United States was studied. Antibody to the Norwalk agent was acquired gradually, beginning slowly in childhood and accelerating in the adult period so that by the fifth decade 50% possessed antibody. This pattern of antibody acquisition contrasted sharply with that for the human rotavirus of infantile gastroenteritis. Rotavirus antibody was acquired during early childhood by almost all individuals in the pediatric groups studied. Antibody to the Norwalk agent was also found in rural Bangladesh; in a small prevalence survey of 39 children and adults 21% possessed Norwalk IAHA antibody, whereas 95% possessed antibody to the human rotavirus.

Adolescent↗
PubMed1978

Secretory antibody directed against rotavirus in human milk--measurement by means of enzyme-linked immunosorbent assay.

Human milk contains antibodies to a variety of enteropathic agents. We utilized the method of enzyme-linked immunosorbent assay to investigate anti-rotavirus secretory IgA in 113 human milk and colostral specimens from a rural area in Guatemala, 32 colostral specimens from an urban area of Costa Rica, and 12 from an urban area of the United States. Anti-rotavirus SCIgA was found in all colostral samples and in 94% of the milk specimans. Both the absolute concentration of anti-rotavirus SCIgA and concentration relative to total SCIgA were highest in colostrum, falling to lower but detectable levels from one week to two years after birth. No significant differences were noted in the results from the specimens from the three different geographic areas. The possible role of this antibody in immunity to rotavirus infections is discussed.

Antibodies, Bacterial↗
PubMed1978

Immunological response to infection with human reovirus-like agent: measurement of anti-human reovirus-like agent immunoglobulin G and M levels by the method of enzyme-linked immunosorbent assay.

The report describes the development of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against the human reovirus-like agent of infantile gastroenteritis (HRVLA). This ELISA system proved to be four times as sensitive as the standard anti-HRVLA fluorescent-antibody assay and ten times as sensitive as the standard anti-HRVLA complement fixation assay. In addition, the ELISA was capable of determining immunoglobulin G (IgG) and IgM subclasses of anti-HRVLA antibody using a single dilution os serum. With this assay, it was discovered that 11 of 21 infected children had anti-HRVLA IgM in their acute sera before the appearance of anti-HRVLA IgG. ELISA is a useful tool in the evaluation of immunological response to HRVLA infection.

Adult↗
PubMed1978

Hemagglutination by simian rotavirus.

A simian rotavirus (SA-11) was shown to hemagglutinate human group "O" and guinea pig erythrocytes. The hemagglutinin appeared to be associated with the outer capsid of the SA-11 virus and was inhibited by specific hyperimmune anti-SA-11 guinea pig serum.

Animals↗
PubMed1978

Measurement of rotavirus antibody by an enzyme-linked immunosorbent assay blocking assay.

A new method for the measurement of rotavirus antibody is described, utilizing the system of enzyme-linked immunosorbent assay (ELISA). In this method, serum is incubated with a fixed amount of rotavirus antigen, and the amount of antibody is determined by measuring the amount of unneutralized antigen. Such an assay system proved to be as efficient as the other available rotaviral antibody systems. The ELISA blocking assay also has the advantages of not requiring purified or gnotobiotic antigen and of being able to measure rotaviral antibody in all animal species.

Adult↗
PubMed1978

New and old agents in diarrhea: a prospective study of an indigenous adult African population.

We conducted a prospective study 77 indigenous African adults with acute diarrhea seeking care at the major hospital in Nairobi, Kenya, to determine the major pathogens responsible for this syndrome in adults. Fecal and blood specimens were collected and examined for enteric bacterial pathogens, viruses, and parasites. In 13 (26%) inpatients and 11 (49%) outpatients Shigella was found, and heat-labile and heat-stable forms of enterotoxigenic Escherichia coli were found in 9 (18%) inpatients and 1 (4%) outpatient. Human revirus-like agent titers rose significantly in another 3 (6%). Amebic dysentery was not seen although hemagglutination-inhibition tests for invasive Entamoeba histolytica were positive in 4 inpatients. An etiologic agent was found in 65% of patients.

Adolescent↗
PubMed1978

Agents affecting health of mother and child in a rural area of Kenya. XI. Antibodies against rotavirus in sera from children living in the Machakos District of Kenya.

207 sera from children under 5 years of age and living in the Machakos District in Kenya were tested in the Complement Fixation Test for antibodies against rotavirus. Two different antigens were used. The superiority of 'O' antigen over Nebraska calf diarrhoea virus antigen was confirmed. After a fall to 29 percent in the 6-8 months age group, the percentage of children with antibodies quickly rises with age to 80 percent at the age of 24 months and to practically 100 percent at the age of 30 months. This age-immunity curve suggests that the majority of children contract infections with rotavirus between 6 and 23 months of age. This is conform the pattern usually found in temperate climate countries.

Antibodies, Viral↗
PubMed1977

Enzyme-linked immunosorbent assay (ELISA) for detection of human reovirus-like agent of infantile gastroenteritis.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of the human reovirus-like agent of infantile gastroenteritis in human stools. The results of the assay can be read either with a simple colorimeter or the naked eye. Investigations with 143 samples from children with gastroenteritis and 75 samples from children with other illnesses showed that the ELISA was as sensitive as electron microscopy or radioimmunoassay for detection of this agent. In addition, the ELISA was simple to perform and, when read visually, did not require sophisticated technical equipment. These advantages make it suitable for field work.

Animals↗
PubMed1977

Human reovirus-like agent infection. Occurrence in adult contacts of pediatric patients with gastroenteritis.

Sixty-four adult family contacts of 61 young patients with gastroenteritis were included in a study for evidence of concurrent infection with the human reovirus-like agent (HRVLA) of infantile diarrhea. Evidence of infection was detected in 26 (41%) of the adult contacts. The HRVLA infection occurred significantly more often among adult contacts of pediatric patients infected with HRVLA (55%) than among contacts of young patients not infected with the agent (17%). Mild cases of gastroenteritis developed in only three of the contacts infected with HRVLA.

Adolescent↗
PubMed1977

Clinical immunity in acute gastroenteritis caused by Norwalk agent.

To examine immunity in viral gastroenteritis, we challenged and then rechallenged 12 volunteers with Norwalk agent and evaluated symptoms, jejunal biopsies and serum antibody. With the first challenge, gastroenteritis developed in six volunteers but not in the others. When rechallenged 27 to 42 months later, the six who became ill initially again had gastroenteritis with jejunal lesions; in the six previously immune volunteers illness or jejunal lesions did not develop. Four of five ill volunteers had increases in serum antibody to Norwalk agent after both challenges. Serum antibody did not increase in three immune volunteers after either challenge. Four volunteers who had twice become ill underwent a third challenge four to eight weeks after their second illness. In one gastroenteritis developed; in three, it did not. These findings indicate two forms of immunity for viral gastroenteritis, one of short and the other of long duration. Factors other than serum antibody appear important in immunity to Norwalk gastroenteritis.

Acute Disease↗