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Biomedical subjects

M Eggers

Publications and source records attributed to M Eggers.

31 records · Page 2Linked to original sources
PubMed1994

A microchip for quantitative detection of molecules utilizing luminescent and radioisotope reporter groups.

Through the marriage of microelectronics and molecular biology, a miniaturized device is presented for ultrasensitive detection of labeled molecules. The novelty of the approach is the direct integration of a charge-coupled device (CCD) and a probe-based assay. Specifically, a CCD detector serves as an active solid support that quantitatively detects and images the distribution of labeled target molecules near the spatially addressable pixels. The device exploits the inherent characteristics of microelectronics that accommodate highly parallel assays, ultrasensitive detection, high throughput, integrated data acquisition and computation. Hence, the technology presented offers substantial practical utility to both research and clinical diagnostic applications that require quantitative analysis of bound molecules. Specifically for probe-based assays such as reverse dot blots, hybridization of radiolabeled or fluorescently labeled, target DNA can be quantitatively assessed within seconds due to the high sensitivity and direct coupling employed.

DNA Probes↗
PubMed1992

Inhibition of human cytomegalovirus maturation by brefeldin A.

Brefeldin A (BFA) was found to interfere with specific events of human cytomegalovirus (HCMV) maturation in human fibroblasts. Ultrastructural as well as biochemical studies suggested that short-term exposure of infected cultures to BFA during the late infectious cycle primarily prevented Golgi-dependent processes, e.g. envelopment of naked cytoplasmic nucleocapsids in the trans-Golgi network (TGN) and normal processing of glycoprotein B. In contrast, the nuclear phase of viral morphogenesis, e.g. transport budding at the nuclear envelope, was not impaired. These observations were compatible with the interpretation that HCMV morphogenesis may involve sequential budding events at the nuclear envelope and at cisternae of the TGN. BFA treatment during the early infectious cycle efficiently inhibited HCMV-DNA synthesis and thus late viral functions, preventing production of viral progeny. Cytotoxicity was excluded as a cause for these findings.

Antiviral Agents↗
PubMed1989

Demographic conditions responsible for population aging.

This article develops and applies two expressions for the rate of change of a population's mean age. In one, aging is shown to be negatively related to contemporary birth rates and death rates. In a general sense, aging occurs when vital rates are too low, as illustrated through applications to the United States, the Netherlands, and Japan. The other expression relates the rate of aging to a population's demographic history, in particular to changes in mortality, migration, and the annual number of births. Applications to the United States and Sweden show that the dominant factor in current aging in these countries is a history of declining mortality. Migration also contributes significantly but in opposite directions in the two countries. The two approaches are integrated after recognizing that the rate of change in the mean age is equal to the covariance between age and age-specific growth rates. A decomposition of this covariance shows that the two seemingly unrelated expressions contain exactly the same information about the age pattern of growth rates.

Aging↗
PubMedDate not supplied

PA28alphabeta double and PA28beta single transfectant mouse B8 cell lines reveal enhanced presentation of a mouse cytomegalovirus (MCMV) pp89 MHC class I epitope.

PA28 is an interferon-gamma inducible modulator of proteasome function composed of two subunits, i.e. PA28alpha and PA28beta. Previously we showed that stabile overexpression of the PA28alpha subunit alone supported MHC class I antigen presentation of two viral epitopes. However, no information was obtained on the consequences when PA28alpha and PA28beta function in concert or when PA28beta is overexpressed on its own. Here we demonstrate that overexpression of PA28alpha and beta together is similarly efficient in supporting MHC class I antigen presentation of the MCMV pp89 9mer epitope as PA28alpha alone, excluding a potentially potentiating role of PA28beta. Surprisingly, and despite the fact that PA28beta alone was thought to be inactive and to only stabilize PA28 activity, overexpression of PA28beta also resulted in improved antigen presentation. However, by northernblot and immunoprecipitation experiments we show that while PA28alpha is able to act alone the observed effect in the PA28beta and PA28alphabeta transfectant cell lines is due to increased levels of PA28alphabeta complexes.

Animals↗
PubMedDate not supplied

Gps mutations in Chilean patients harboring growth hormone-secreting pituitary tumors.

Hypersecretion of GH is usually caused by a pituitary adenoma and about 40% of these tumors exhibit missense gsp mutations in Arg201 or Gln227 of the Gs, gene. We studied 20 pituitary tumors obtained from patients with GH hypersecretion. One tumor was resected from an 11 year-old boy with a 3 year history of accelerated growth, associated with increased concentrations of serum GH and IGF-I, which were not suppressed by glucose administration. The remaining 19 tumors were obtained from adult acromegalic patients, who had elevated baseline serum GH levels that did not show evidence of suppression after administration of glucose. The gsp mutations were studied by enzymatic digestion of the amplified PCR fragment of exon 8 (Arg201) and exon 9 (Gln227) with the enzymes NlaIII and NgoAIV, respectively. The tumors obtained from the boy and from nine of the 19 patients with acromegaly exhibited the gsp mutation R201H. None of the tumors had the Gln227 mutation. The gsp positive patients tended to be older, had smaller tumors, and had preoperative basal serum GH levels which were significantly lower (21 +/- 6 vs 56 +/- 16 microg/l, p<0.05) than the gsp negative patients. In this study, we documented the presence of a gsp mutation in Arg201 in a boy with gigantism and in approximately half of 19 Chilean adult patients with acromegaly, similar to other populations.

Adenoma↗
PubMedDate not supplied

[Goiter and chronic lymphocytic thyroiditis].

Sixty patients with goiter, aged 3 to 16 years, 58 girls, were studied for evidence of chronic lymphocytic thyroiditis (CLT). Thirty eight patients, 63%, presented two or more diagnostic elements of TLC, according to Fisher's criteria, with a high frequency of thyroid function involvement (47.4% had hypothyroidism and 18.4% had hyperthyroidism). The rest of the patients with diffuse goiter (37%) did not meet Fisher's criteria, they were mostly euthyroid (95%) and they were designated "non thyroiditis goiter". All patients with probable CLT had positive antimicrosomal antibodies at relatively high titer (greater than 1 x 600 in 71% of the cases) and 32% of them had both antimicrosomal and antithyroglobulin antibodies. In the "non thyroiditis goiter" group we found 28% of children with positive antimicrosomal antibodies at low titers (1 x 100 and 1 x 400, respectively). In a control group of 28 children of similar ages, without endocrine diseases neither familiar history of thyroid diseases only 3 (11%) cases showed positive antimicrosomal antibodies, always at low serum titers.

Adolescent↗