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Biomedical subjects

M McConnell

Publications and source records attributed to M McConnell.

At least 55 records · Page 3Linked to original sources
PubMed1990

Family practice obstetric ultrasound in an urban community health center. Birth outcomes and examination accuracy of the initial 227 cases.

The initial 227 consecutive prenatal ultrasound examinations by two family physicians in an urban community health center were compared with actual birth outcomes. Of 186 examinations for which follow-up information was available, 162 infants were represented. The sampling rate was 81%. No serious anomalies were noted by ultrasound. One placenta previa, one fetal death, and two unsuspected cases of twins were detected by ultrasound. These data represent one of the first detailed reports of outcomes reflecting family physicians' psychomotor and cognitive skill in the use of obstetric ultrasound. The high accuracy (92% to 96%) of correct ultrasound dating suggests that a short postgraduate continuing medical education course was effective for these two family physicians. The accuracy rate compares favorably to more rigorous training. This structured format utilizing the average of four direct measurements for ultrasound-estimated gestational age and three anatomy ratios for assessing proper imaging relationships or growth symmetry may be useful as other family physicians develop educational methods and quality-assurance protocols in this area.

California↗
PubMed1989

Heat shock-induced appearance of RNA polymerase II in karyoskeletal protein-enriched (nuclear "matrix") fractions correlates with transcriptional shutdown in Drosophila melanogaster.

Heat shock in vivo or brief incubation at moderately elevated temperatures (15 min at 37 degrees C) in vitro is required for the structural stability of proteinaceous karyoskeletal elements purified from Drosophila melanogaster (McConnell, M., Whalen, A. M., Smith, D. E., and Fisher, P. A. (1987) J. Cell Biol. 105, 1087-1098). We have found that the appearance of the two largest subunits of RNA polymerase II in karyoskeletal preparations is promoted by conditions identical to those which promote in vitro stability of karyoskeletal elements overall. Increased levels of polymerase II in karyoskeletal protein-enriched fractions correlate with decreased levels of nucleotide incorporation in nuclear transcription run-on assays. These results are not easily reconciled with the proposal that putative karyoskeletal elements such as the internal nuclear "matrix" are sites of active transcription in vivo.

Animals↗
PubMed1989

mRNA stabilizing signals encoded in the genome of the bacteriophage phi x174.

In Escherichia coli cells infected with bacteriophage phi x174, mRNAs initiated by promoters PB and PD terminate after genes J, F, G, or H (TJ, TF, TG, or TH). These RNAs are relatively stable and contain mRNA-stabilizing signals at their 3' ends. These signals were cloned after gene D of phi x174 in an expression vector plasmid. The cloned signals stabilize mRNA of the upstream gene D and the stabilized mRNA is translationally functional. When these signals are inserted in reverse, no stabilizing effect on mRNA is observed indicating that the correct sequences at the 3' ends of transcripts determine their stability. When a stabilizing signal (+) and a mutated stabilizing signal (-) which has reduced stabilizing activity are tandemly inserted after gene D, two sets of 3' termini of the transcript are observed indicating that both signals also function as terminators. The amount of gpD synthesized from these constructs varies depending upon the relative positions of the (+) or (-) signals after gene D. The stabilizing function seems to act by preventing mRNA degradation from the 3' to 5' direction. Several common features of these stabilizers are described.

Bacteriophage phi X 174↗
PubMed1987

Heat shock-induced changes in the structural stability of proteinaceous karyoskeletal elements in vitro and morphological effects in situ.

Karyoskeletal protein fractions prepared from Drosophila melanogaster embryos contain morphologically identifiable remnants of nuclear pore complexes and peripheral lamina as well as what appears to be an internal nuclear "matrix" (Fisher, P. A., M. Berrios, and G. Blobel, 1982, J. Cell Biol., 92: 674-686). Structural stability of these proteinaceous assemblies is dependent on thermal incubation in vitro (37 degrees C, 15 min) before subfractionation of nuclei. In the absence of such incubation, greater than 90% of the total karyoskeletal protein including major polypeptide components of internal "matrix," pore complexes, and the peripheral lamina, is solubilized by 1 M NaCl. In vivo heat shock induces karyoskeletal stabilization resembling that resulting from thermal incubation in vitro. Immunocytochemical studies have been used to establish the effects of heat shock on the organization and distribution of major karyoskeletal marker proteins in situ. Taken together, these results are consistent with the notion that in vivo, regulation of karyoskeletal plasticity (and perhaps form) may be a functionally significant component of the Drosophila heat shock response. They also have broad practical implications for studies pertaining to the structure and function of karyoskeletal protein (nuclear "matrix") fractions isolated from higher eukaryotic cells.

Animals↗
PubMed1983

Aggressive treatment with pulse methylprednisolone or plasma exchange is justified in rapidly progressive glomerulonephritis.

Rapidly progressive crescentic glomerulonephritis (RPGN) carries a poor prognosis, but early immunosuppression may reverse renal impairment. We have given intensive therapy to 27 patients with biopsy proven RPGN from 1977-1981. Fourteen patients received pulse methylprednisolone (PMP) and 13 patients plasma exchange (Px). These patients fared significantly better than 17 patients seen from 1972-1979 who had neither PMP nor Px. Both groups received oral prednisolone and other immunosuppressive agents. PMP and Px were equally effective in prolonging survival without dialysis and had no serious side effects; prognostic factors affecting the outcome of treatment were identified. Early aggressive immunosuppressive therapy is indicated in RPGN.

Adolescent↗
PubMed1979

Variation in the structure and bacteriophage-inactivating capacity of Salmonella anatum lipopolysaccharide as a function of growth temperature.

Growth temperature affects both the structure and the phage-inactivating capacity of Salmonella anatum A1 lipopolysaccharide. Whereas S. anatum cells normally synthesize smooth lipopolysaccharide when grown at physiological temperature (37 degrees C), a partial smooth-rough transition occurs when cells are grown at low temperature (20 to 25 degrees C). The synthesis at low growth temperature of lipopolysaccharide molecules lacking O-antigen was detected both by increased sensitivity of cells to the rough-specific bacteriophage Felix O-1 and by fractionation of oligosaccharides derived from lipopolysaccharide by mild acid hydrolysis. Growth temperature-induced changes in the structure of S. anatum A1 lipopolysaccharide also affected its ability to inactivate epsilon15, a bacteriophage that binds initially to the O-antigen portion of the molecule. Purified lipopolysaccharide prepared from cells grown at low growth temperature exhibited a higher in vitro phage-inactivating capacity than did lipopolysaccharide prepared from cells grown at physiological temperature (37 degrees C).

Chemical Phenomena↗
PubMed1975

Regulation of Membrane Flexibility in Human Erythrocytes.

We have used spin-labels to detect prostaglandin E induced changes in erythrocyte membranes. The observed changes in spin-label resonance spectra can be mimicked in erythrocyte ghosts by loading them with cAMP or cGMP. These changes can also be observed by adding either of these cyclic nucleotides to intact cells. This entry of cyclic nucleotides into intact cells is blocked by an inhibitor of the anion channel. We suggest that the observed changes in paramagnetic resonance spectra are due to changes in lipid "fluidity" that are brought about by changes in the biochemical state of membrane-associated proteins (such as spectrin) and in the direct or indirect biophysical interactions of these proteins with membrane lipids.

Benzenesulfonates↗
PubMed1975

Fusion of dipalmitoylphosphatidylcholine vesicle membranes induced by concanavalin A.

The temperature dependence of fatty acid spin label resonance spectra and freeze fracture micrographs of sonicated dipalmitoylphosphatidylcholine vesicles in the absence and presence of concanavalin A demonstrate a strong interaction of concanavalin A with these lipid membranes, which results in fusion of the vesicles. The rate of this reaction as followed with use of magnetic resonance exhibits a pronounced maximum at 36 degrees, the midpoint of the phase transition range of dipalmitoylphosphatidylcholine vesicles. This maximum is discussed in terms of structural fluctuations, which are maximal in the phase transition range of the membranes.

Binding Sites↗
PubMed1972

Mapping of rod mutants of Bacillus subtilis.

Nine class A salt-dependent rod mutants were mapped on the Bacillus subtilis genome by PBS1-mediated transduction. They are distributed into two small linkage groups designated rod B and rod C; mutations in rod B are over 80% cotransducible with pheA and different mutations in rod C are 12 to 21% cotransducible with hisA. It is established that neither rod B nor rod C is linked by transformation to the other identified rod mutations present in 168-ts-200B and 8332 glu(-). It is hypothesized that salt-dependent mutations are due to enzyme alterations which are corrected by high salt concentrations.

Amino Acids↗