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Biomedical subjects

S Mathews

Publications and source records attributed to S Mathews.

13 recordsLinked to original sources
PubMed1992

A trial of desmopressin to reduce blood loss in patients undergoing spinal fusion for idiopathic scoliosis.

Desmopressin (DDAVP) has been reported to reduce bleeding in patients undergoing spinal fusion. To evaluate its efficacy in normal patients, 30 healthy young patients (ASA physical status I or II) undergoing spinal fusion for idiopathic scoliosis were randomly allocated to receive either 100 mL of physiologic saline solution (placebo group) or DDAVP (10 micrograms/m2 of body surface area) (DDAVP group) in a prospective, double-blind trial. Intraoperative blood loss was measured by weighing sponges and suction drainage and postoperative bleeding by wound drainage. The amount of blood loss expressed as a percent of the estimated blood volume was similar in both groups during the intraoperative period (67.0% +/- 28.8% [mean +/- SD] placebo group vs 57.4% +/- 26.5% DDAVP group), the postoperative period up to 24 h (32.5% +/- 6.4% placebo group vs 31.1% +/- 10.6% DDAVP group), and both periods (94.3% +/- 29.4% placebo group vs 88.2% +/- 30.7% DDAVP group). With the dose used in our study, we conclude that DDAVP does not reduce surgical bleeding in patients undergoing spinal fusion for idiopathic scoliosis.

Adolescent↗
PubMed1992

The differentiation pathway of HL60 cells is a model system for studying the specific regulation of some myeloid genes.

During granulopoiesis, certain myeloid genes encoding products of azurophilic granules are specifically down-regulated. The myeloid specific enzyme myeloperoxidase belongs to this group of genes. It is responsible for the production of hypochlorous acid, a potent microbicidal agent which is involved in host defense. During induced differentiation of promyelocytic leukemic HL60 cells to granulocyte- or monocyte-like cells, myeloperoxidase RNA is depressed. We studied this depression process in more detail by limiting the exposure to the inducer phorbol 12-myristate 13-acetate to 24 h. During this time period, no significant decrease in cell number and cell viability could be observed. Analysis of these in vitro differentiated HL60 cells on the protein and RNA levels showed that they can be used under defined conditions as a cell system to study the specific depression of myeloid genes. Under the described conditions, both the transcriptional rate of the myeloperoxidase gene as well as the stability of its transcript was reduced.

Actins↗
PubMed1992

What is the utility of the psychophysical 'light scattering factor'?

It has been suggested by Sjöstrand and his colleagues that an index of scatter by the ocular media may be derived from contrast sensitivity measured with and without a glare source. This index was tested under different conditions of stimulus luminance and found not to be constant and thus to not reflect a property of the media.

Adult↗
PubMed1991

Arterial catheter-related infections in children. A 1-year cohort analysis.

To determine the incidence of infection secondary to arterial catheterization in children as well as the risk markers, we prospectively evaluated, during a 1-year period, all arterial catheters installed in children admitted to the pediatric intensive care unit. A total of 340 cannulas were placed in 310 children aged 80 +/- 4 months (mean +/- SEM) for a period of 64 +/- 4 hours. Most catheters were inserted percutaneously (99%) in the radial artery (86.5%). Ninety-two percent (313/340) of the catheters were sterile (group 1), 5% (17/340) were contaminated (less than 10 colony-forming units on semiquantitative culture) (group 2), and 3% (10/340) were considered either locally infected (ie, greater than or equal to 10 colony-forming units) (eight of 10) or associated with a possible catheter-related sepsis (two of 10) (group 3, or infected group). The incidence of local inflammation at the insertion site was higher in group 2 than in group 1 (18% vs 2.9%) but not statistically different between groups 3 and 1 (10% vs 2.9%). The duration of arterial catheterization was longer in group 3 than in group 1 (125 +/- 31 vs 61 +/- 4 hours). The risk of infection was nonexistent in the first 48 hours of catheterization. Thereafter it was calculated as being 6.2% (10/161), but it correlated poorly with the duration of arterial catheterization. These results confirm the very low incidence of infection related to arterial catheterization in children. Thus, routine catheter reinsertion is, in our opinion, unjustified.

Adolescent↗
PubMed1988

Multiple divergent mRNAs code for a single human calmodulin.

The isolation of a novel complementary DNA (cDNA) clone coding for human calmodulin (CaM) is reported. Although it encodes a protein indistinguishable from the only known higher vertebrate calmodulin, its nucleotide sequence varies extensively from that of two previously reported human CaM cDNAs (Wawrzynczak and Perham, 1984; SenGupta et al., 1987). Only 82 and 81% identity, respectively, is found between the newly isolated and the two known human mRNAs in their coding regions. No striking homology is present in their noncoding regions. Codon usage in the three CaM mRNAs is also surprisingly divergent. A 2.3-kilobase mRNA corresponding to the newly isolated clone is expressed to varying extents in several human tissues, together with an approximately 0.8-kilobase mRNA species presumably arising from alternative polyadenylation of the same primary transcript. The results indicate that the human genome contains at least three divergent CaM genes that are under selective pressure to encode an identical protein while maintaining maximally divergent nucleotide sequences. Partial characterization of a genomic clone specifying the 3' portion of the newly identified CaM mRNA shows that this gene contains introns at identical positions as the previously characterized bona fide vertebrate CaM genes. Evolutionary implications of the presence of a CaM multigene family are discussed.

Amino Acid Sequence↗
PubMed1988

Complete primary structure of a human plasma membrane Ca2+ pump.

cDNAs coding for a plasma membrane Ca2+ pump were isolated from a human teratoma library and sequenced. The translated sequence contained 1,220 amino acids with a calculated molecular weight of 134,683. All regions of functional importance known from other ion-transporting ATPases could be identified. The translated sequence also contained, near the carboxyl terminus, the calmodulin-binding domain and two domains which are very rich in glutamic acid and aspartic acid. These two domains resemble calmodulin somewhat and one of them may play a role in the binding of Ca2+. The enzyme also contains domains rich in serine and threonine, one of which has a sequence matching those of good cAMP-dependent protein kinase substrates. The carboxyl-terminal region is important for regulation by calmodulin, proteolysis, and phosphorylation. Near the amino terminus are two domains which are very rich in lysine and glutamic acid, as well as two domains resembling EF hands, one of which also has some resemblance to calmodulin. Comparison of the cloned sequence with peptide sequences from the erythrocyte Ca2+ pump showed that the two proteins have a very high proportion of identical residues but are not 100% identical, indicating that they represent different isozymes.

Amino Acid Sequence↗
PubMed1988

Mapping of brain areas containing RNA homologous to cDNAs encoding the alpha and beta subunits of the rat GABAA gamma-aminobutyrate receptor.

An in situ hybridization technique was used to determine the distribution in rat brain of RNA homologous to cDNA clones encoding the alpha and beta subunits of the rat brain GABAA gamma-aminobutyrate receptor. The subunit proteins were mapped in adjacent sections autoradiographically and immunohistochemically. Many brain areas containing high densities of GABAA receptors showed strong hybridization signals with both the alpha- and the beta-subunit antisense RNA probe--e.g., cerebral cortex, hippocampus, and cerebellum. On a cellular level, a dense dendritic localization of GABAA receptors was correlated with a strong hybridization in the corresponding somata--e.g., in mitral cells of the olfactory bulb, pyramidal cells of hippocampus, granule cells of the dentate gyrus, and Purkinje and granule cells of the cerebellum. In some brain areas--e.g., substantia nigra--the intensity of the hybridization signal with the beta-subunit probe was much weaker than that with the alpha-subunit probe, whereas the inverse ratio of hybridization intensity was found in others--e.g., in bed nucleus. This regional heterogeneity in the hybridization pattern may reflect regional differences in RNA stability, transcription rate, or subunit composition. The results open the way for studies on the regulation of GABAA-receptor gene expression in normal and pathological brain in situ.

Animals↗
PubMed1987

Cloning of the K+-ATPase of Streptococcus faecalis. Structural and evolutionary implications of its homology to the KdpB-protein of Escherichia coli.

The K+-ATPase of Streptococcus faecalis consists of a single polypeptide component of relative Mr = 78,000 and serves as an ATP-driven pump for the accumulation of potassium by the bacterial cell. The gene encoding this ATPase was isolated by immunological screening of an S. faecalis genomic library in the Escherichia coli/pUC8 host/vector system. Two independently derived clones express the full-size ATPase polypeptide. Transcription and translation of the cloned DNA apparently proceed by means of the respective S. faecalis signals. DNA sequencing revealed a gene encoding a protein of 583 amino acids and a calculated Mr of 63,070. This protein exhibits in its primary structure regions of homology with the KdpB-subunit of the K+-ATPase of E. coli and, to a lesser extent, with eukaryotic ion-motive ATPases. The hydropathy profiles and secondary structure predictions, respectively, for the S. faecalis ATPase and the E. coli KdpB-protein show striking similarity. Even regions with low homology in the amino acid sequence exhibit structural features that have clearly been conserved in the two proteins. This points to a fundamental role of these domains in the structure and/or function of these transport ATPases.

Adenosine Triphosphatases↗