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Biomedical subjects

R L Peters

Publications and source records attributed to R L Peters.

At least 19 recordsLinked to original sources
PubMed1999

Ebola (subtype Reston) virus among quarantined nonhuman primates recently imported from the Philippines to the United States.

In April 1996, laboratory testing of imported nonhuman primates (as mandated by quarantine regulations) identified 2 cynomolgus macaques (Macaca fascicularis) infected with Ebola (subtype Reston) virus in a US-registered quarantine facility. The animals were part of a shipment of 100 nonhuman primates recently imported from the Philippines. Two additional infected animals, who were thought to be in the incubation phase, were identified among the remaining 48 animals in the affected quarantine room. The other 50 macaques, who had been held in a separate isolation room, remained asymptomatic, and none of these animals seroconverted during an extended quarantine period. Due to the rigorous routine safety precautions, the facility personnel had no unprotected exposures and remained asymptomatic, and no one seroconverted. The mandatory quarantine and laboratory testing requirements, put in place after the original Reston outbreak in 1989-1990, were effective for detecting and containing Ebola virus infection in newly imported nonhuman primates and minimizing potential human transmission.

Animals↗
PubMed1999

Behavioral specificity of effects of 2-mercaptoacetate on independent ingestion in developing rats.

Blockade of fatty acid oxidation in rat pups using 2-Mercaptoacetate (MA) produces increases in independent ingestion by 12 days of age. In the present experiments, the behavioral specificity of the effects of MA on ingestion were examined. In the first experiment, administration of MA to pups aged 9 and 12 days of age failed to increase intake of an oral infusion of a milk diet. In the second experiment, administration of MA did enhance intake of a milk diet in a short-term test of consuming from the floor of a test container and the level of gastric fill appeared to determine intake during the test. Finally, administration of MA did not affect intake of water in 9- or 12-day-old pups. These results suggest that MA produces increases in intake through specific effects on selective ingestive responses and not through nonspecific behavioral arousal.

Animals↗
PubMed1994

Screening donors for xenotransplantation. The potential for xenozoonoses.

Xenotransplantation is a potential solution to the current donor shortage for solid organ transplantation. The transmission of infectious agents from donor organs or bone marrow to the recipient is a well-recognized phenomenon following allotransplantation. Thus the prospect of xenotransplantation raises the issue of xenozoonoses--i.e., the transmission of animal infections to the human host. Anticipating an increasing number of baboon to human transplants, 31 adult male baboons (Papio cynocephalus) from a single colony in the United States were screened for the presence of antibody to microbial agents (principally viral) that may pose a significant risk of infection. Antibody to simian cytomegalovirus, simian agent 8 and Epstein-Barr virus, was found in 97% of animals tested. Antibody to simian retroviruses and Toxoplasma gondii was found in 30% and 32% respectively. Discordant results were found when paired samples were examined by two primate laboratories. This was particularly noted when methodologies were based on cross-reaction with human viral antigens. These results highlight the need to develop specific antibody tests against the species used for xenotransplantation.

Animals↗
PubMed1992

Histopathologic observations in weanling B6C3F1 mice and F344/N rats and their adult parental strains.

Weanling Fischer 344/N (F344) rats and the first filial hybrid of C57BL/6 x C3H (B6C3F1) mice and retired breeders from the parental stocks of these strains were monitored over a 5-yr-period by examining the histopathology of selected organs and comparing those results to viral and mycoplasmal serology and the intestinal tract bacterial flora of each animal on an individual basis. Serology gave no evidence of viral infection, but Mycoplasma arthriditis antibodies were detected. Reactivity of serum of adult C57BL/6 female mice with control cells or media (tissue culture, TC) was seen in a significant number of mice. TC reactivity correlated positively with lymphoid perivascular infiltrates, predominantly of the lungs, suggesting an allergic response in development of the lesions. Other lesions of note consisted of Harderian gland inflammation of rats, focal necrotizing lesions of the liver of both species, and thickening of the pleura and adjacent pulmonary interstitium of weanling rats. Embolization of bacteria from the gastrointestinal tract to the liver was considered a possible cause of the liver necrosis in both species. Although lesions of the lung and Harderian gland of the rats are similar to those caused by known viral agents, the cause of the latter could not be determined as these animals were negative for viral antibodies and the former was considered to be related to incomplete pulmonary development in the young rat. Features differentiating the lesions observed in animals of this survey from those caused by viral infection are discussed.

Aging↗
PubMed1989

Risk lesions in cirrhosis and development of hepatocellular carcinoma: an autopsy study.

Non-neoplastic morphologic changes in various types of cirrhosis were evaluated in relationship to the presence or absence of hepatocellular carcinoma (HCC), using autopsy livers from Hokuriku (Japan) and Los Angeles (USA). Macronodular cirrhosis was closely related to HCC in B-viral cirrhosis, alcoholic cirrhosis and cirrhosis of uncertain type. Liver cell dysplasia was most frequently seen in cases with and without HCC in B-viral cirrhosis but was significantly more frequent with HCC in cases of alcoholic cirrhosis and cirrhosis of uncertain type. Nodular bulging activity within regenerative nodules was closely related to HCC in alcoholic cirrhosis. A positive relationship between HCC and Mallory bodies was found in non-alcoholic cirrhosis. These data suggest that patients with macronodular cirrhosis, liver cell dysplasia, nodular bulging activity and Mallory bodies may have an increased risk of developing, or having HCC dependent on the etiology of cirrhosis. The geography and race differences had some relationship to the incidence of HCC.

Autopsy↗
PubMed1987

Effects of sodium tetradecyl sulfate endoscopic variceal sclerotherapy on the esophagus. A prospective clinical and histopathologic study.

A prospective clinical, endoscopic, and histopathologic study of the esophagus was carried out in 24 patients with advanced liver disease who underwent esophageal variceal sclerotherapy (EVS) and who eventually came to autopsy. Patients were arbitrarily divided into three groups: acute (group I), intermediate (group II), and chronic (group III) based on the interval between the first EVS and death. EVS with sodium tetradecyl sulphate (STS) initially produced thrombosis with varying degrees of necrosis and inflammation followed by ulceration, recanalization, and eventually fibrosis with obliteration of varices. Recurrent variceal hemorrhage (VH) leading to death was highest in the acute group since all patients died of uncontrollable VH (100%); it ranged between 50-60% in both the intermediate and chronic groups. Despite variceal obliteration, recurrent hemorrhage developed in the chronic group due to gastric varices or other venous channels in the esophagus or stomach. Additionally, we describe findings not previously reported, such as the presence of sclerosant outside the varices after intravariceal injection, thrombosis of gastric varices after esophageal injections, and the development of muscular wall thickening.

Adult↗
PubMed1986

Alpha-1-antitrypsin deficiency in adults.

A clinicopathological examination was carried out on eight adult patients with alpha-1-antitrypsin (ATT) deficiency. Phenotyping confirmed five patients with PiMZ, two patients with PiZ-, and one patient with PiZZ. Cirrhosis was found in six of the patients, four of whom had a history of excessive ethanol consumption. Hepatitis B surface antigen was positive in two patients with cirrhosis. Dysplastic change was present in four patients, although no neoplasia in the liver was found in all patients. All patients had periodic acid-Schiff positive and diastase resistant inclusions of hepatocytes, which were identified as ATT by indirect immunoperoxidase stain. The possibility of the combined effects of ATT inclusions and such harmful stimuli such as alcohol or viral hepatitis infection may render the hepatocytes more susceptible to damage, and may contribute to development of cirrhosis.

Adult↗
PubMed1986

Pathologic features of the liver in acquired immune deficiency syndrome (AIDS).

The livers of 26 adult males with acquired immune deficiency syndrome (AIDS) were reviewed. The occurrence of portal tracts with diminished lymphocytes, probably reflecting generalized exhaustion of the lymphoid system, was a characteristic morphologic change, and was found in all cases. Kupffer cell hyperplasia was also a frequent finding and probably reflected generalized infection(s). Punched-out clusters of foamy histiocytes filled with acid-fast bacilli, typical for infection with Mycobacterium avium intracellulare (MAC), were found in three patients. In addition, MAC was cultured from two livers without the foamy histiocytic changes. Chronic viral hepatitis (three cases) and deposition of polarizable materials (one case) in the liver might be related to unusual habits of patients with AIDS. In conclusion, livers from patients with AIDS disclosed several kinds of lesions reflecting underlying or associated conditions in AIDS, but these did not contribute to the cause of death in our patients.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The kinetics of the flash-induced P515 response in relation to the H+-permeability of the membrane bound ATPase in spinach chloroplasts.

The effect of dicyclohexylcarbodiimide (DCCD) on the kinetics of the flash-induced P515 response and on the activity of the ATPase was investigated in isolated spinach chloroplasts. It was found that after the addition of 5 X 10(-8)mol DCCD the rate of ATP hydrolysis induced by a period of 60 sec illumination was decreased to less than 5% of its original value. At this concentration, hardly any effect, if at all, could be detected on the kinetics of the flash-induced P515 response, neither in dark-adapted nor in light-activated chloroplasts. It was concluded that the presence of concentrations of DCCD, sufficiently high to affect the ATPase activity, does not affect the kinetics of the flash-induced P515 response. Since DCCD decreases the H+ permeability of the membrane-bound ATPase, it was concluded that this permeability coefficient for protons is not an important factor in the regulation of the flash-induced membrane potential and, therefore, does not affect the kinetics of the flash-induced P515 response.

Adenosine Triphosphatases↗
PubMed1985

Morphologic and immunohistochemical features of fulminant delta hepatitis.

Recent studies have indicated that some cases of fulminant hepatitis that were ostensibly type B were actually acute viral hepatitis, types B and delta, or persistent hepatitis, type B with superimposed acute delta infection. Histologic characterization of the various types has not yet been undertaken. Within ten to 37 days of the onset of initial symptoms, liver tissues from a total of 16 patients who had acute delta hepatitis with fulminant clinical courses were examined. Tissues were from biopsies in nine cases and from autopsies in seven. Based on the serologic absence of IgM hepatitis B core antibody, chronic forms of hepatitis B with acute delta infection were diagnosed in five of the 16 patients. The underlying liver disease in three of these five patients was identifiable as chronic active hepatitis with fibrosis, and that in the others was apparently persistent hepatitis B. Coded liver tissues from these seven autopsies were evaluated without the knowledge of serologic diagnosis for qualitative and quantitative light microscopic features, together with autopsy liver tissues from five patients with fulminant B hepatitis without serologic evidence of delta infection and five patients with fulminant non-A, non-B hepatitis. No specific features that would allow discrimination among these three types of hepatitis were found.

Acute Disease↗
PubMed1985

Membranous obstruction of the inferior vena cava in the United States.

The pathogenesis of membranous obstruction of the inferior vena cava (MOVC) is unclear. Although the lesion is rare in the United States compared to Japan, India, and black South Africa, it has been responsible for 23% of cases of hepatic outflow obstruction we have encountered in the ethnically heterogeneous indigent population of Los Angeles. Most patients with MOVC are male. In contrast, recent series of patients with Budd-Chiari Syndrome (BCS) have demonstrated a female predominance. Compared to BCS without involvement of the inferior vena cava (IVC), patients with MOVC have more chronic symptoms. Large truncal collaterals, particularly on the back, strongly suggest MOVC. In patients without this sign, a high index of diagnostic suspicion is required. Chronic hepatitis B infection occurs with increased frequency in these patients. Chest radiograph may show an enlarged azygous shadow. Liver-spleen scan is not helpful, and the liver biopsy is frequently nondiagnostic. A useful screening procedure for hepatic outflow block is transhepatic portal pressure measurement demonstrating aberrant hepatic veins with pressures higher than in the portal vein and, occasionally, hepatofugal portal flow. Transcardiac membranotomy appears to be symptomatically effective in patients with MOVC and at least one patent hepatic vein. It is not known whether this operation will prolong life and prevent the development of hepatocellular cancer, which may occur in up to 48% of these patients. The correct therapeutic approach has not been established for those patients whose lesion is not amenable to surgery because of extensive IVC occlusion or absence of patent hepatic veins.

Adult↗