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Biomedical subjects

E James

Publications and source records attributed to E James.

At least 91 records · Page 5Linked to original sources
PubMed1980

Studies on platelet glycoproteins in Glanzmann's thrombasthenia using 125I-labelled lectins.

Glycoproteins (GP) of Glanzmann's thrombasthenia (GT) and normal platelets were separated on sodium dodecyl sulphate (SDS) polyacrylamide slab gels and identified by their binding of 125I-labelled lectins having different sugar specificities. This highly sensitive technique showed that in thrombasthenic platelets, glycoproteins in the positions of IIb and III (IIIa) were greatly reduced when compared to normal platelets. After incubation with neuraminidase, IIb became undectable. GT platelet glycoproteins I, IV (IIIb), and high molecular weight GPs bound 125I-lectins more strongly than those in normal platelets, showing that there are drastic changes in the carbohydrate moieties of these major GPs.

Blood Platelets↗
PubMed1980

Neonatal renal failure: usefulness of diagnostic indices.

Forty-two oliguric neonates were prospectively studied to evaluate the usefulness and reliability of various diagnostic indices in differentiating renal failure from functional (prerenal) oliguria. Twenty-two infants had functional oliguria, 16 had renal failure, and four infants had probable early renal failure. Statistically significant differences between functional oliguria and renal failure were found with regard to the urine sodium, urine to serum ratios of sodium, urea, and creatinine, renal failure index, and fractional excretion of sodium. However, sharp demarcation of the two groups was possible only when the renal failure index or fractional excretion of sodium was used. Fractional excretion of sodium values of 2.5 or greater seem to differentiate renal failure from functional oliguria in this study.

Acute Kidney Injury↗
PubMed1980

CSF lactate levels in high risk neonates with and without asphyxia.

Determination of CSF lactate levels were performed in 150 nonasphyxiated and 46 asphyxiated high risk neonates. Statistical analysis of log lactate levels of nonasphyxiated infants showed significant relationship to gestational and postnatal ages (P < .0001 and < .0002, respectively). CSF lactate elevation was seen in 16/29 infants studied within eight hours of asphyxia in contrast to 0/17 infants studied after eight hours (P < .001). Higher incidence of CSF lactate elevation was seen in term infants (7/8), infants with fetal distress (13/17), and very low Apgar scores (11/18). Seven of eight infants with markedly elevated lactate levels had both fetal distress and very low Apgar scores. CSF lactate determination in the immediate postasphyxial period appears to be an objective way of assessing the severity of cerebral hypoxia.

Apgar Score↗
PubMed1979

Cloning the argF gene from Escherichia coli K-12 with simian virus 40.

We have inserted a gene coding for ornithine transcarbamylase (OTCase) from Escherichia coli K-12 into the late gene region of simian virus 40 (SV40) DNA and propagated the hybrid molecules as free episomes or by co-infection with an SV40 tsA helper virus. In the first case, the E. coli argF gene was inserted via the EcoRI and BamHI termini in the late gene region of SV40 and the recombinant molecules were used to transfect monkey kidney cells. The hybrid DNA, which was too large to be encapsidated, was replicated for a short time (14 days) but was eventually lost from the surviving cells. In order to allow the argF gene to be packaged into virions, we purified two SV40 vectors containing large deletions of late gene region sequences. One was a 3325 base pair segment from a HaeII + BamHI digest. The argF gene was joined to both vectors at the BamHI site and these linear molecules were used to transfect monkey cells in the presence of SV40 tsA58 DNA as helper. These hybrid DNAs were replicated and packaged into virions. Late in the lytic infection of monkey cells, polyadenylated, cytoplasmic argF transcripts were detected, but significant translation of these trancripts was not observed.

Cloning, Molecular↗
PubMed1979

Mapping of restriction sites in the argF gene of Escherichia coli by partial endonuclease digestion of end-labeled DNA.

A detailed physical map depicting the cleavage sites generated by ten different restriction endonucleases was prepared for the argF region of the Escherichia coli K-12 genome carried on a 1650 base pair fragment capable of directing the in vitro synthesis of ornithine transcarbamylase (OTCase; ec 2.1.3.3) under the control of arginine holorepressor. The method employed was originally developed by Smith and Birnstiel (1976), and involved the electrophoretic sizing of partial endonuclease digestion products of DNA radiolabeled at one end. This novel technique proved to be rapid, simple, amenable to the simultaneous mapping of numerous cleavage sites, and provided the essential information for determining the map order of restriction fragments. A facile method which involved magnesium phosphate as the DNA-binding agent was presented for the isolation of DNA fragments. The discovery of a 117 base pair leader sequence in the argF gene is also discussed.

Arginine↗
PubMed1978

DNA cleavage of lambda and phi 80 transducing phages carrying the argA, argECBH, argF and argI operons of Escherichia coli K-12 with the restriction endonucleases EcoRI, SmaI and HindIII.

DNA isolated from each of the seven arginine transducing phages lambdaargA2cI857susS7, phi80ppc argECBH, phi80argF, phi80argF ilambdacI857, lambdaargF2, lambdaargF23 and lambdaargI valScI857susS7 has been specifically cleaved by the restriction endonucleases EcoRI, SmaI and HindIII. The DNA fragments resulting from single, and in some cases, double endonuclease digests were separated by electrophoresis in agarose and also in polyacrylamide gel. The electrophoretic patterns thus obtained were compared with those produced by digestion of DNA isolated from the corresponding lambda and phi80 parental phages. The majority of cleavage sites produced by the action of these restriction enzymes on arginine transducing DNA have been physically mapped.

Arginine↗
PubMed1978

Isolation, cloning and characterization of argF gene DNA from Escherichia coli K-12.

A 1650 base pair (BP) fragment carrying the entire argF structural gene with its associated control regions was isolated from an EcoRI/BamHI digest of phi80argFilambda cI857 DNA. This segment was cloned using the EcoRI and BamHI cleavage sites in the plasmid pBR322. A preliminary restriction map of the argF region was prepared. RNA polymerase binding studies indicated that the argF promoter is located approx. 30 base pairs from the EcoRI terminus of the cloned DNA segment.

Arginine↗
PubMed1978

Production of "rapid-harvest" Moloney murine leukemia virus by continuous cell culture on synthetic capillaries.

Moloney murine leukemia virus was harvested automatically within 60 min of release from chronically infected NIH/3T3 cells (clone 1) cultured on bundles of synthetic capillaries. Production of virus as measured by a determination of reverse transcriptase activity and by the XC syncytia assay demonstrated that highly infectious "rapid-harvest" virus was recovered from NIH/3T3 cells (clone 1) grown for periods of up to 10 days.

Cell Line↗
PubMed1977

Synthesis of the Escherichia coli K12 isoenzymes of ornithine transcarbamylase, performed in vitro.

The in vitro synthesis of enzymatically-active ornithine transcarbamylase (OTCase) directed by each of the E. coli K-12 OTCase genes (argF and argI) is described. The E. coli OTCase isoenzyme subunits are not identical, whether synthesized in vivo or in vitro, the argF-coded product being about 5% smaller. The OTCase protomers are enzymatically inactive but associate in vitro to an enzymatically active multimer. The rates of subunit association of argF and argI isoenzymes are considerably different. Utilizing the facile assay protocol presented, the regulation of in vitro OTCase synthesis by the specific holorepressor of the arginine regulon is demonstrated. Calculations based upon data presented indicate that there are about 65 molecules of argR gene product per bacterium, a substantially lower estimate than previously reported.

Arginine↗
PubMed1977

Transcription of the argF and argI genes of the arginine biosynthetic regulon of Escherichia coli K12, performed in vitro.

The cell-free transcription of the argF and argI genes of the arginine biosynthetic regions is described using an S-30 system capable of coupled in vitro transcription-translation. Template DNA isolated from two independently isolated arginine transducing phages was used in this work. Steady state mRNA synthesis was observed which was attributed to RNAase degradation. Regulation of argF mRNA synthesis, directed by the argF gene carried on the specialized transducing phage phi80dargF is effected to the extent of at least 95% by the arginine holorepressor at the transcriptional stage and at least 80% of the regulation of the expression of the argI gene is mediated at the transcriptional stage. Evidence is presented which indicates that the arginine holorepressor prevents RNA polymerase from binding to the arginine promoter and suggests that the operator and promoter sites may overlap.

Arginine↗