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Biomedical subjects

A C Peters

Publications and source records attributed to A C Peters.

At least 73 records · Page 4Linked to original sources
PubMed1989

Characterization of virus infected cell cultures by pyrolysis/direct chemical ionization mass spectrometry.

The supernatants of Vero cell cultures after infection with a herpes simplex virus or a poliomyelitis virus as well as a blank were analysed by pyrolysis/direct chemical ionization mass spectrometry (Py/DCI MS). Informative pyrogrammes were obtained and used for characterization of viral proteins by applying pattern recognition methods. Differentiation of viral proteins was evaluated by analysing 'blind' samples. Herpes viruses could be classified correctly but the observed differences between the blank and the polio virus supernatants were too small for reliable classification of the polio viruses. Purification of the samples seems to be a prerequisite for further studies. The potential value of Py/DCI MS as a rapid non-invasive diagnostic method for viral meningoencephalitis is stressed.

Animals↗
PubMed1989

Somatic pairing of chromosome 1 centromeres in interphase nuclei of human cerebellum.

Interphase nuclei isolated from paraffin-embedded tissue of four normal brains were hybridized with biotinated repetitive DNA probes specific for the (peri)centromeric regions of chromosomes 1 and 7. Hybridization results were visualized with a peroxidase-DAB system after which the number of specific signals per nucleus was counted using bright field microscopy. Using the probe specific for chromosome 7 (p7t1), both the cerebral and the cerebellar samples showed 2 spots in 82% and 83%, respectively, of the nuclei. In situ hybridization with the chromosome 1 probe (pUC1.77) showed two spots in 69% of the cerebral nuclei. In cerebellar samples, hybridization with pUC1.77 resulted in only one large spot per nucleus in 82% of the cells. The average spot size in nuclei with one signal was about 1.6 times as large as that in nuclei with two signals. These observations suggest that the single large spot in the cerebellar cells is not the result of monosomy of chromosome 1 but that it reflects somatic pairing of the two chromosome 1 centromeres. Based on the size and the fraction of nuclei with one large spot, the small granular neuron is the most likely candidate. The difference between cerebral and cerebellar samples indicates that this somatic pairing of chromosome 1 is a cell-type-dependent phenomenon.

Cell Nucleus↗
PubMed1989

Polymerase chain reaction and viral culture techniques to detect HSV in small volumes of cerebrospinal fluid; an experimental mouse encephalitis study.

A technique is described for the detection of HSV-DNA in very small volumes (5-10 microliters) of cerebrospinal fluid (CSF). The method was evaluated in CSF samples of 4-6-week-old mice inoculated with HSV-1 via the corneal route. The sensitivity of the PCR assay was compared with results of spin-amplified viral culture with immunofluorescent visualization (SAC/IF), routine viral culture (RVC) and radioactive dot-blot hybridization (DBA) in CSF samples obtained from other mice. The results show the PCR to be superior over the other techniques: infectious virus or viral DNA in CSF was demonstrated by PCR, SAC/IF, RVC and DBA in 68, 55, 20 and 2.5%, respectively. These results show the feasibility of the PCR for a rapid, non-invasive diagnosis of human HSV-encephalitis.

Animals↗
PubMed1989

Diagnosis of progressive multifocal leucoencephalopathy by hybridisation techniques.

In situ hybridisation with acetyl-aminofluorene (AAF) and 35S-labelled DNA probes for polyomaviruses, was used to detect JC virus DNA in brain necropsy material in a patient with progressive multifocal leucoencephalopathy (PML). In a second patient PML was diagnosed from a brain necropsy specimen using the same technique. The main infected cell type were oligodendrocytes; dot hybridisation was used to estimate the number of viral copies in each infected cell. Southern blot hybridisation for further analysis of the viral genome was also carried out. In situ hybridisation with non-radioactive labelled polyomavirus DNA provides a simple and specific means for studying viral DNA in formaldehyde fixed tissue sections from patients with suspected PML. Even in small biopsy samples hybridisation results can be correlated with standard histopathological, immunocytochemical, and electron microscopic findings.

Adult↗
PubMed1989

Multiple-site carcinogenicity of benzene in Fischer 344 rats and B6C3F1 mice.

Toxicology and carcinogenesis studies of benzene (CAS No. 71-43-2; greater than 99.7% pure) were conducted in groups of 60 F344/N rats and 60 B6C3F1 mice of each sex for each of three exposure doses and vehicle controls. These composite studies on benzene were designed and conducted because of large production volume and widespread human exposure, because of the epidemiologic association with leukemia, and because previous experiments were considered inadequate or inconclusive for determining carcinogenicity in laboratory animals. Using the results from 17-week studies, doses for the 2-year studies were selected based on clinical observations (tremors in higher dosed mice), on clinical pathologic findings (lymphoid depletion in rats and leukopenia in mice), and on body weight effects. Doses of 0, 50, 100, or 200 mg/kg body weight benzene in corn oil were administered by gavage to male rats, 5 days per week, for 103 weeks. Doses of 0, 25, 50, or 100 mg/kg benzene in corn oil were administered by gavage to female rats and to male and female mice for 103 weeks. Ten animals in each of the 16 groups were killed at 12 months, and necropsies were performed. Hematologic profiles were performed at 3-month intervals. For the 2-year studies, mean body weights of the top dose groups of male rats and of both sexes of mice were lower than those of the controls. Survivals of the top dose group of rats and mice of each sex were reduced; however, at week 92 for rats and week 91 for mice, survival was greater than 60% in all groups; most of the dosed animals that died before week 103 had neoplasia. Compound-related nonneoplastic or neoplastic effects on the hematopoietic system, Zymbal gland, forestomach, and adrenal gland were found both for rats and mice. Further, the oral cavity was affected in rats, and the lung, liver, Harderian gland, preputial gland, ovary, and mammary gland were affected in mice. Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenicity of benzene in male F344/N rats, female F344/N rats, male B6C3F1 mice, and female B6C3F1 mice. In male rats, benzene caused increased incidences of Zymbal gland carcinomas, squamous cell papillomas and squamous cell carcinomas of the oral cavity, and squamous cell papillomas and squamous cell carcinomas of the skin. In female rats, benzene caused increased incidences of Zymbal gland carcinomas and squamous cell papillomas and squamous cell carcinomas of the oral cavity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Rett syndrome].

Diagnostic and supportive criteria for Rett syndrome (RS) and differential diagnostic considerations are presented. RS is a recognizable neurodevelopmental syndrome without a specific biologic marker. Treatment is largely supportive.

Autistic Disorder↗
PubMed1988

Immunofluorescence detection of herpes simplex virus type 1 antigen in cerebrospinal fluid cells of experimentally infected mice.

Experimentally infected mice were used to assess the value of immunofluorescence (IF) procedures in cerebrospinal fluid (CSF) cells in comparison with routine viral culture of CSF for diagnosis of herpes simplex type-1 (HSV-1) encephalitis. Virus specific antigen was detected by immunofluorescence in the majority of CSF cells in 75% of infected animals. In contrast, only 20% of infected mice had positive viral cultures, which sometimes took as long as a week to show a cytopathological effect (CPE). It is concluded that antigen detection by immunofluorescence is a rapid, specific and sensitive technique for demonstrating HSV-1 antigen in CSF cells of experimentally infected mice. Our results put forward a plea for further studies using these techniques on CSF samples from patients with suspected HSV-1 encephalitis. The prerequisites for reliable interpretation of results have been defined in this study.

Animals↗
PubMed1987

Guillain-Barré syndrome after varicella-zoster infection. Report of two cases.

Two patients developed Guillain-Barré syndrome after varicella-zoster infection; a 4-year-old boy after chickenpox and a 74-year-old man after shingles. Both had decreased CD8-positive lymphocytes in the blood during the course of their illness. These cases and others reported in the literature suggest that varicella-zoster infection is a significant but rare trigger factor of Guillain-Barré syndrome. An alteration in the balance of helper and suppressor lymphocytes may be an important pathogenetic mechanism.

Aged↗
PubMed1987

Oxygen profiles in, and in the agar beneath, colonies of Bacillus cereus, Staphylococcus albus and Escherichia coli.

The paper reports the use of microelectrodes to measure O2 penetration in different aged colonies of Bacillus cereus, Escherichia coli and Staphylococcus albus. In young (18 h) colonies of B. cereus and E. coli O2 disappeared at depths of 25-30 micron and 35-40 micron respectively. In young S. albus colonies, O2 reached a minimum but was never completely absent. As colonies aged (24-168 h) the depth to which O2 penetrated increased.

Bacillus cereus↗
PubMed1987

Discontinuation of antiepileptic therapy: a prospective study in children.

Anticonvulsant medication was stopped in a prospective study in 116 children with epilepsy who had had no seizures for a period of 2 years. A remission rate of 80.5% was found 5 years after withdrawal. The population studied was unselected, and based on children directly referred by general practitioners to the outpatient department. Among the many variables examined, such as type of epilepsy or seizure, presence of concomitant neurological or intellectual deficit, and epileptiform activity on the EEG, only the age of onset of seizures was significantly and positively correlated with the probability of recurrence after discontinuation of medication. In contrast to other recent studies, it was concluded that there are no reliable predictive factors for withholding from any individual "epileptic" child the benefit of attempts to stop medication after 2 years of seizure freedom.

Adolescent↗