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Biomedical subjects

M Mathis

Publications and source records attributed to M Mathis.

At least 19 recordsLinked to original sources
PubMed2001

Abnormal hemoglobins: laboratory methods.

Laboratory methods allowing the detection and characterization of hemoglobin variants are reviewed. Protein chemistry techniques such as isoelectrofocusing, electrophoreses under various experimental conditions, cation exchange and reversed phase high performance liquid chromatography, are the most frequently used for the detection of variants. When associated with a few additional data they may lead to a presumptive diagnosis. DNA studies are also developed in many laboratories. Final identification of a variant may be achieved either by molecular biology techniques or by protein sequence analysis in which mass spectrometry now occupies a key position.

Chemistry Techniques, Analytical↗
PubMed2001

Aberrant methylation during cervical carcinogenesis.

We studied the pattern of aberrant methylation during the multistage pathogenesis of cervical cancers. We analyzed a total of 73 patient samples and 10 cervical cancer cell lines. In addition, tissue samples [peripheral blood lymphocytes (n = 10) and buccal epithelial cells (n = 12)] were obtained from 22 healthy volunteers. On the basis of the results of preliminary analysis, the cervical samples were grouped into three categories: (a) nondysplasia/low-grade cervical intraepithelial neoplasia (CIN; n = 37); (b) high-grade CIN (n = 17); and (c) invasive cancer (n = 19). The methylation status of six genes was determined (p16, RARbeta, FHIT, GSTP1, MGMT, and hMLH1). Our main findings are as follows: (a) methylation was completely absent in control tissues; (b) the frequencies of methylation for all of the genes except hMLH1 were >20% in cervical cancers; (c) aberrant methylation commenced early during multistage pathogenesis and methylation of at least one gene was noted in 30% of the nondysplasia/low-grade CIN group; (d) an increasing trend for methylation was seen with increasing pathological change; (e) methylation of RARbeta and GSTP1 were early events, p16 and MGMT methylation were intermediate events, and FHIT methylation was a late, tumor-associated event; and (f) methylation occurred independently of other risk factors including papillomavirus infection, smoking history, or hormone use. Although our findings need to be extended to a larger series, they suggest that the pattern of aberrant methylation in women with or without dysplasia may help identify subgroups at increased risk for histological progression or cancer development.

Acid Anhydride Hydrolases↗
PubMed2001

Preterm delivery and the severity of violence during pregnancy.

OBJECTIVE: To determine the severity and consequences of physical violence during pregnancy among participants in a health department prenatal care coordination program. STUDY DESIGN: The prospective cohort study included all program participants from 1994 to 1996. Care coordinators screened participants for physical violence during pregnancy using a validated, systematic assessment protocol three times during prenatal care. The protocol was linked with prenatal records, delivery records and infant records to document complications and infant outcomes. Multiple logistic regression was used to assess the relationship between severe physical violence during pregnancy and pregnancy outcome while controlling for confounding factors. RESULTS: Among the 550 participants, 13.5% reported violence during pregnancy; it included 6.7% severe violence (hitting, kicking, injury with a weapon and abdominal injury) and 6.7% moderate violence (threats, slapping, shoving and sexual abuse). Severe physical prenatal violence was significantly associated with spontaneous preterm labor, preterm delivery, very preterm delivery, very low birth weight, preterm/low birth weight, mean birth weight, mean newborn hospital charges, five-minute Apgar < 7, neonatal intensive care unit admission, and fetal or neonatal death. Body site injured, timing of violence and number of violent incidents were significant factors associated with violence during pregnancy and preterm delivery. CONCLUSION: Because severe physical violence during pregnancy was a significant problem in this population, intervention programs are needed to reduce prenatal violence and its consequences.

Adolescent↗
PubMed1998

[Management of children with low vision].

Presentation of the Lausanne school for blind and visually impaired children. 38 children were admitted in the school in 1996-1997. 16 have a visual acuity of less than 3/60. Ocular malformations of various origins are the main reason of the handicap, followed by visual lesions of central origin. Comparing the study with those of 1992 and 1993, it seems that the number of retrolental fibroplasia and cataracts (operated or not) is decreasing. The authors present the educational care of these children. At present, the goal is to maintain the children in their own family. Most of them are day pupils and the transportation organisation is therefore very important. In special cases, it is possible to leave the children in a non-specialized school, provided the children receive a good educational support by one of our specialized low-vision teachers.

Adolescent↗
PubMed1997

Cation-exchange HPLC evaluated for presumptive identification of hemoglobin variants.

A battery of relatively simple tests allows the presumptive identification of hemoglobin (Hb) variants, making unnecessary structural analysis by protein chemistry methods or DNA sequencing. The primary step in this strategy involves the use of a matrix of electrophoretic mobilities obtained under various experimental conditions. This leads to an unambiguous result in approximately 90% of the cases. Additional tests are required to characterize with more confidence the remaining 10%. We describe here the use of cation-exchange HPLC on the Bio-Rad Variant automated analyzer with the "beta Thalassemia Short" program. By comparing the elution time of 125 human Hb mutants, we found that some variants with almost identical pI values or produced by the same type of amino acid substitution displayed different elution times. We present several examples in which use of the HPLC profile helped establish the diagnosis.

Cations↗
PubMed1996

Perfusion chromatography on reversed-phase column allows fast analysis of human globin chains.

Human globin chain analysis provides important information on the genetics and molecular pathophysiology of hemoglobinopathies. We propose using perfusion chromatography on the reversed-phase stationary phase to perform these studies. The technique, herein described, involves a high-velocity flow of the mobile phase through a porous chromatographic stationary phase made of microspheres of poly(styrene-divinylbenzene) having throughpores of 6000-8000 A diameter with short diffusive pores of 500-1000 A diameter connected to them. The composition of fetal hemoglobin (Ggamma:Agamma ratio) is determined, using this method, as an order of magnitude faster than with conventional HPLC. Elution is performed by developing a linear gradient of acetonitrile at a flow rate of 3 ml/min (or more), easily obtained on any HPLC machine. Analyses may be done on samples containing as low as 3.0% Hb F. Results are similar to those obtained with the reference HPLC technique, which uses a C4 column. In addition, reversed-phase perfusion chromatography, using a shallow curvilinear gradient, may help in the characterization of Hb variants. This technique allowed us to discriminate several alpha and beta chain mutants from variants that have closely similar patterns of electrophoretic mobilities.

Chromatography↗
PubMed1995

A transforming growth factor beta receptor type II gene mutation common in colon and gastric but rare in endometrial cancers with microsatellite instability.

We have recently demonstrated that mutation of the transforming growth factor-beta (TGF-beta) receptor type II (RII) gene is characteristic of colon cancers exhibiting microsatellite instability or replication errors (RER+). Moreover, we have shown that RII mutations in these RER+ colon cancers are characteristically frameshift mutations within a 10-bp polyadenine repeat present in the RII-coding region. We now show that RII gene mutations in this polyadenine repeat are also commonly present in RER+ gastric cancers (71%). In contrast, we find these same RII gene mutations are distinctly uncommon in RER+ endometrial cancers (17%, P < 0.02). These results suggest that RII gene mutations confer a growth advantage and are selected for in RER+ cancers of both the upper and lower gastrointestinal tract. The genesis of RER+ endometrial tumors must, however, be by a different route.

Base Sequence↗
PubMed1995

Brain-derived neurotrophic factor induces functional expression and phenotypic differentiation of cultured fetal neuropeptide Y-producing neurons.

A series of studies from our laboratory has established an aggregate culture system of fetal rat brain cells that can serve as a model for studying regulatory processes of the developing neuropeptide Y (NPY)-producing neurons. Using aggregate cultures derived from 17-day-old fetal rat cortex, we addressed these questions: 1) Does brain-derived neurotrophic factor (BDNF) stimulate NPY production, and if so, is stimulation a function of the developmental state of the cultured NPY neuron? 2) Does BDNF induce phenotypic differentiation of NPY neurons? BDNF led to an increase in NPY production and the accumulation of NPY-mRNA in a dose dependent manner. BDNF did not alter the stability of NPY-mRNA, judged by the disappearance rate of NPY-mRNA after blockade of RNA synthesis (estimated t1/2 was 6-8 hr). BDNF stimulation of NPY production was dependent on length of exposure to BDNF and on culture-age. A continuous 8-day exposure to BDNF resulted in a significantly higher level of NPY production than a pulse of 2 days (comparing BDNF exposure on days 0-8 vs. 6-8, or days 8-17 vs. 15-17). Moreover, older neurons (age 17 days) produced twice as much NPY as younger (age 8 days) neurons in response to a 2-day pulse of BDNF (50 ng/ml). BDNF was significantly more effective than NT-3 in inducing NPY production, and NGF was ineffective. Immunocytochemical analysis of 8-day NPY neurons revealed that a 2-day pulse of BDNF induced the appearance of an abundance of morphologically well-defined neurons bearing an elaborate network of neurites. This was in contrast to the control-treated NPY neurons, which were morphologically undefined. In summary, the age-dependent effect of BDNF on NPY production is consistent with induction of functional expression, rather than promotion of survival, of cultured NPY neurons. The neurotrophin specificity for stimulation of NPY production, and the lack of effect of BDNF on the stability of NPY-mRNA, implicate the TrkB receptor in mediating transcriptional activation of the NPY gene. Thus, BDNF exerts a dual effect on developing cultured NPY neurons: induction of functional expression, and phenotypic differentiation of immature neurons into mature neurite-bearing neurons.

Animals↗
PubMed1983

[Peroperative circulatory arrest caused by a tumoral pulmonary embolism following hepatectomy for tumor. Apropos of a case].

The authors report a case of pulmonary tumor embolism during a hepatectomy for hepatoma, leading to a fatal cardiac arrest. This cause of cardiac arrest during operation has never been reported in the literature, but systematic autopsies of patients dying from liver cancer, especially primary or metastatic tumors, shows that the incidence of these embolisms is frequently underestimated. Any anomaly of the hepatic vein appearing in the X-rays implies a danger of intra- or post-operative embolism. Allowance must therefore be made for this in the surgical technique, which should include complete or partial cross-clamping of the vena cava.

Carcinoma, Hepatocellular↗