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Biomedical subjects

M Peters

Publications and source records attributed to M Peters.

At least 397 records · Page 22Linked to original sources
PubMed1986

Immune effects of alpha-interferon in chronic liver disease.

The effect of prolonged alpha-interferon therapy on immune function was studied in patients with chronic type B hepatitis. These patients with chronic type B hepatitis have been shown to have a defect in their in vitro response to human recombinant alpha-interferon. This defect consists of a failure to augment pokeweed mitogen-stimulated immunoglobulin production at low concentrations of interferon and an increased susceptibility to the suppressive effects of interferon. After 2 weeks therapy with interferon, immunoglobulin production was further suppressed. However, after 4 months of therapy with interferon, pokeweed mitogen-stimulated immunoglobulin production partially returned towards the pretreatment values. Antibody to hepatitis B core antigen was less affected by interferon therapy. This altered response to interferon was not specific as it was seen in some patients with other forms of liver disease. The suppression of B cell differentiation appears to be separate from its antiviral and antiproliferative effects.

Hepatitis B↗
PubMed1986

Autism as impairment in the formation and use of meaning: an attempt to integrate a functional and a neurological model.

Neurological approaches and functional approaches to impairments in autism provide different perspectives on the disorder. This study attempted an integration of the two approaches, based specifically on the role of the mesolimbic/neostriatal system in imparting adaptive meaning to percepts and problems that autistic persons have in making adaptive use of meaning.

Autistic Disorder↗
PubMed1986

Evaluation of the computing aspects of automatic analysers.

Modern automatic analysers are making increasing use of microprocessor technology, which is difficult for the user, or even computer scientists, to evaluate. This paper offers some practical advice for the prospective purchaser on how to assess the capabilities and limitations of the computer hardware and software provided in such instruments, and considers some of the problems of interfacing an analyser to a laboratory computer system.

Autoanalysis↗
PubMed1986

A short course of prednisolone in chronic type B hepatitis. Report of a randomized, double-blind, placebo-controlled trial.

Fifteen patients with chronic type B hepatitis were treated with corticosteroids in a randomized, double-blind, placebo-controlled trial lasting 28 days. Ten patients received prednisolone, 60 mg/d for 2 weeks, then 30 mg/d for another 2 weeks; 5 patients received placebo. Serum aminotransferase levels decreased significantly during prednisolone therapy but 4 to 10 weeks after abrupt withdrawal of the drug, they rebounded to levels greater than those before treatment. This exacerbation of disease lasted for several months and was prolonged and symptomatic in 3 patients. Hepatitis B virus levels did not change substantially during treatment. Follow-up examinations showed no improvement in biochemical or serologic features of the disease in any of the 15 patients; follow-up liver biopsies showed a worsening in 4 of 7 treated patients but in 0 of 5 control patients. Thus, a 28-day course of prednisolone produced no beneficial effects in patients with mild-to-moderate chronic type B hepatitis; on the contrary, such treatment may be harmful.

Adult↗
PubMed1985

Synergy of helper factors in the differentiation of in vivo-preactivated antigen-specific human B cells.

After in vivo immunization with antigen, B cells appear in the peripheral blood which can be induced in vitro by nonspecific factors found in mixed lymphocyte culture supernatants (MLC-SN) to differentiate and secrete antibody specific for the immunizing antigen. In order to further delineate the nature of the factors involved in the differentiation of these in vivo-activated B cells, various helper factors, including interleukin 1 and interleukin 2 (IL-1 and IL-2), B-cell growth factor (BCGF), and B-cell differentiation factor (BCDF) were added separately and in combination to cultures of these preactivated B cells. T-cell-depleted fractions of peripheral blood mononuclear cells were obtained from normal individuals immunized in vivo with keyhole limpet hemocyanin. MLC-SN alone, without the addition of antigen, selectively triggered an antibody response specific for the antigen used to immunize in vivo in the absence of a polyclonal B-cell response. In order to obtain responses equal to those seen with MLC-SN, a combination of BCGF, IL-2, and BCDF was required, although any two factors partially reconstituted the response. Exogenous IL-1 had the least effect but was suppressive in the presence of optimal concentrations of monocytes. Thus, for maximal in vitro differentiation of in vivo-preactivated B cells, a combination of at least three helper factors is required and acts in a synergistic manner to induce antigen-specific antibody responses.

B-Lymphocytes↗
PubMed1985

Coagulation and fibrinolytic factors in the first week of life in healthy infants.

Coagulation and fibrinolytic factors were determined daily in 74 healthy term and preterm infants to obtain a reference standard. A gestational age dependency was determined for antithrombin III, factor II, and plasminogen. The mean concentrations of antithrombin III and factor II in preterm infants increased to term values within the first week of life. Factor X levels declined independent of vitamin K administration. The values for the fibrinolytic system (alpha 2-antiplasmin and plasminogen) remained stable.

Antithrombin III↗
PubMed1984

Improved techniques for the photometric determination of partition coefficients, with particular reference to the chloroform-ammonia solvent system.

Accurate partition coefficients K = Corg/Caq in chloroform-ammonia can be obtained by measuring the absorbance of the aqueous layer, replenishing with fresh aqueous solvent, and remeasuring the absorption after reequilibration. Provided the solute has a reasonably strong UV absorption, only 0.1-5 mg of material is required. Neither the amount, the extinction coefficient, nor (in most cases) the purity of the substrate material need be known. In general, K values ranging from 100 to 0.01 can be measured with a precision of greater than or equal to 10%. A detailed analysis of the absorbance and volumetric error sources permits the optimum combination of experimental conditions such as volume ratios, cell lengths, and absorbance (either direct or differential, or with scale expansion) to be predicted a priori. Quantitative estimates for all primary error sources, such as photometric precision, baseline error, stray light, and volumetric errors were also experimentally determined. The theoretical error model was tested by determining K for aniline under widely ranging experimental conditions and by comparing the experimental standard deviations with those calculated from the theoretical model. The agreement was found to be satisfactory. The method described appears to be of particular usefulness for the determination of extraction or chromatographic parameters of basic drugs.

Ammonia↗
PubMed1984

Persistent antithrombin III deficiency: risk factor for thromboembolic complications in neonates small for gestational age.

Coagulation and fibrinolytic factors were investigated daily in 24 SGA and 26 AGA neonates. The results were correlated with placental form and structure and with hematologic values. In the SGA infants, a higher incidence of placental infarction (P less than 0.01), polycythemia (P less than 0.005), and thrombocytopenia (P less than 0.001) was present. During the first 9 days, the mean antithrombin III level in the AGA group increased from 0.36 to 0.53 U/ml, whereas in SGA neonates this value was initially significantly lower (0.27 U/ml) and remained at that level for the entire observation period. The same pattern was found for alpha 2-antiplasmin. The persistent AT-III deficiency and reduced blood flow associated with polycythemia may explain the increased risk of thromboembolic complications in SGA infants described by others.

Antithrombin III Deficiency↗
PubMed1984

Neonatal antithrombin III.

Antithrombin III (AT-III) heparin cofactor activity and its antigen levels have been determined in 106 plasma samples from 42 term and preterm neonates. In contrast to healthy adult controls, a reduced activity/antigen (act/ag) ratio (ranging from 0.26 to 0.86) was observed in 90% of the samples and was independent of the state of health of the infant. By modifying the routine assay techniques, laboratory artefacts were excluded as the cause of the observed discrepancy. The relative increase in antigenic AT-III could not be accounted for by circulating AT-III-thrombin complexes, or by increased heparin cofactor II plasma levels in neonates.

Adult↗
PubMed1984

Mechanism of aprindine induced agranulocytosis: direct toxicity on CFU-C and CFU-GEMM.

The in vitro bone marrow growth of 2 patients with aprindine-induced agranulocytosis was studied. Granulocyte-macrophage committed stem cell (CFU-C) growth is inhibited by aprindine in a dose dependent manner. 50% inhibition of CFU-colony growth (TD50) was seen at 5.1 and 3.4 micrograms aprindine/ml medium respectively. The TD50 of control marrow CFU-C was 3.2 micrograms/ml. 100% inhibition was seen at 16 micrograms aprindine/ml, both in patients and controls. Pluripotential stem cell growth (CFU-GEMM) in control marrow was equally inhibited in a dose dependent manner by aprindine, though to a lesser extent (TD50: 9.1 micrograms/ml) and with relative sparing of pure megakaryocyte and erythroid colonies. Co-culturing of patients marrows with their respective acute phase serum did not inhibit CFU-C growth.

Aged↗
PubMed1984

Hospital blood bank laboratory data processing system.

A data processing system designed to improve the management and usage of blood and blood products has been developed as a pilot for general application throughout the West Midlands Regional Health Authority. The package provides for the routine clerical, patient record, and stock management aspects of a hospital blood bank laboratory. It can be tailored to the individual requirements of different laboratories and may be implemented in a variety of ways on a family of computer systems of differing power and capacity, thus accommodating widely varying workloads and archiving requirements. Bar code readers are included in the system design, and may be used for data input where standard Codabar labels are affixed to blood products by blood transfusion centres. The system has been installed in one hospital laboratory and preliminary results indicate a high degree of acceptability at all levels. Further refinement of the software to meet minor deficiencies and the requirements of the recent DHSS Health Circular BLD/2/13 are currently being specified.

Blood Banks↗
PubMed1984

Motor organization in pharynx of Helix pomatia.

Identified motor neurons in the buccal ganglia of Helix pomatia and pharynx muscles innervated by them were studied with intracellular recording and cobalt staining. Retrograde cobalt staining via the buccal nerves indicated that neurons occupy relatively constant positions within the ganglia. With intracellular cobalt staining it was shown that the shape of a representative motor neuron (B4) is similar in different preparations. In some cases, however, deviations from the normal pattern of axon distribution were found. Presumed motor endings of neuron B4 in the muscle were also visualized with intracellular staining. Recordings from individual motor neurons show typical phase relationships of spontaneous spike activity. Most motor neurons are active in the retraction phase of the radula. Only excitatory motor neurons were found. Most neurons directly supply more than one muscle. Amplitude of excitatory junction potentials (EJP) and plasticity at neuromuscular junctions from one neuron are similar in different muscles. Single muscle fibers receive polyneuronal innervation. Activity of single motor neurons already leads to muscle contraction even without spiking of the muscle cells. Muscle tension depends on integrated EJP size. Most motor neurons supply typical combinations of a set of muscles. Thus, several muscles can be activated synchronously by activity of a single motor neuron. In this way muscle combinations are predetermined morphologically by the peripheral branching patterns of the respective neurons.

Animals↗