Estimation of effective pulmonary capillary pressure in intact lungs.
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Animals↗
Biomedical subjects
J Parker
Publications and source records attributed to J Parker.
Health locus of control: implications for an end stage renal disease program.
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Adult↗
Immune responses of healthy humans 83-104 years of age.
The immune responses of 19 healthy people 83-104 years of age were compared to those of younger healthy persons. A decline in mitogen response to concanavalin A and pokeweed mitogen, but not to phytohemagglutinin, was observed. Positive skin test to two recall antigens occurred in only 5 of the 19 aged people; 4 of these 5 reported a history of blood transfusion. Antibody titers were elevated for persistent DNA viruses but not for RNA viruses. An excess of ABO blood type B was found, but no human leukocyte antigen (HLA)-A or HLA-B type was found in elevated proportion.
ABO Blood-Group System↗
Specific mistranslation in hisT mutants of Escherichia coli.
Certain strains of Escherichia coli mistranslate at very high frequencies when starved for asparagine or histidine. This mistranslation is the result of misreading events on the ribosome. The introduction of a hisT mutation into such a strain decreases the frequency of mistranslation during histidine starvation but not during asparagine starvation. The most likely explanation is that the replacement of the pseudouridine residue in the anticodon loop of glutamine specific transfer ribonucleic acid by uridine in hisT mutants leads to an increase in fidelity of transfer ribonucleic acid function. The hisT gene in Escherichia coli has also been more accurately mapped, giving the gene order purF-hisT-aroC-fadL-dsdA.
Chromosome Mapping↗
The nucleotide sequence of the promoter region of hisS, the structural gene for histidyl-tRNA synthetase.
A plasmid has been constructed which carries hisS, the structural gene for histidyl-RNA synthetase of E. coli, on a 1.6-kb fragment bounded by PvuII and BstEII sites. The DNA sequence of both ends of this fragment was determined. The amino-terminal sequence of histidyl-tRNA synthetase was also determined to locate the promoter proximal coding region and the frame in which it is read. Three promoters were identified by consensus criteria. The region surrounding these promoters contains extensive twofold symmetry.
Amino Acid Sequence↗
System for umbilical artery monitoring.
A simple, safe, and effective system for umbilical artery monitoring controls continuous fluid infusion to prevent fluid overinfusion and keep the catheter from clotting. Accurate and continuous pressure measurements can be recorded simultaneously with fluid infusion. A convenient method for checking dynamic response fidelity is provided. The system is easy to set up and maintain. Because it is a closed system, contamination of the neonate is minimized.
Catheterization↗
The phenotype of ring chromosome 3.
A male child with mental retardation and poor growth was found to have a 46,XY,r3 (p26 leads to q29) karyotype in 92% of his peripheral lymphocytes and 90% of his cultured fibroblasts. Comparison of this patient's dysmorphic features with previously reported cases of ring 3 or deletion 3p suggests a clinical syndrome derived mainly from deletion of 3p26 leads to pter. The syndrome consists of mental retardation, pre- and postnatal growth retardation, microcephaly, hypertonia, digital anomalies, and a characteristic facies with ptosis, epicanthal folds, broad nasal root, down-turned corners of the mouth, and dysplastic ears.
Abnormalities, Multiple↗
Spontaneous hyperglycemia and impaired glucose tolerance in athymic nude BALB/c mice.
Basal plasma glucose, glucose tolerance, and insulin secretion were investigated in young and mature athymic nude BALB/c mice and in age-matched controls. Basal plasma glucose levels in male athymic nude mice were similar to those of controls at 1, 3, and 4 wk of age. At 6, 8, and 12 wk of age, male athymic nudes had significantly higher basal plasma glucose levels when compared with controls (P less than 0.01). Plasma immunoreactive insulin concentrations were similar in athymic nudes and controls at 1 wk of age, but at 3 wk of age and subsequently at 6, 8, and 12 wk athymic nude mice had significantly decreased insulin levels when compared with their age-matched controls (P less than 0.05). We found impaired glucose tolerance in male athymic nude mice at all age groups when compared with both female athymic nudes and control BALB/c mice. The discovery of a spontaneous diabetic syndrome (hyperglycemia, impaired glucose tolerance, and decreased insulin secretion) in a colony of athymic nude mice may provide an excellent model for studying the genetics and interactions between the immune and endocrine systems.
Animals↗
Quantitation of Candida albicans polysaccharide using an enzyme-linked immunosorbent assay.
The enzyme-linked immunosorbent assay (ELISA) for candida polysaccharide antigen in serum was developed by using double antibody sandwich technique. It was found that serum constituents substantially interfered with the assay. The interference was successfully decreased by heating serum in the presence of EDTA which precipitated interfering serum protein. In addition, candida antigen may be liberated from antibody complexes. The candida polysaccharide antigen in the supernatant was precipitated with ethanol and resuspended in the buffer containing gelatin. A maximum sensitivity of 10 ng/ml was found in the assay using this procedure. This procedure of serum treatment may have potential applications for the detection of other polysaccharide antigens in serum.
Alkaline Phosphatase↗
Suture obliteration of the circumflex coronary artery in three patients undergoing mitral valve operation. Role of left dominant or codominant coronary artery.
Three patients, two undergoing mitral valve replacement and one a mitral valve annuloplasty with a Carpentier-Edwards ring, had suture obliteration of the circumflex coronary artery. Examination of the distance of the circumflex artery from the mitral anulus in 15 specimens showed a direct correlation to the type of coronary dominance. That is, left dominance (4.1 mm, range 3 to 6.5) or codominance (5.5 mm, range 4.5 to 7.5), where the posterior descending artery arises from the circumflex, was associated with greater proximity to the mitral anulus than right dominance (8.4 mm, range 6 to 11.5). Two of our patients had left dominance and one codominance, predisposing them to circumflex injury. Factors that identify patients at high risk for such injury are therefore left dominance and codominance. Surgeons forewarned with this information can now focus on the proximal third of the circumflex--the area most predisposed to injury.
Coronary Vessels↗
Mistranslated protein in Escherichia coli.
Amino acid starvation of a variety of different types of cells has been reported to induce protein degradation and also specific mistranslation. For certain amino acid starvations, the mistranslated protein, which contains specific amino acid substitutions, can be separated and quantified by two-dimensional polyacrylamide gel electrophoresis. In this paper, I show that this specifically mistranslated protein, made during amino acid starvation, does not seem to be preferentially degraded during continued starvation or renewed growth. Specifically mistranslated ribosomal protein is also assembled into ribosomes in the same proportion that it is made. These results imply that the amino acid substitutions apparently made (lysine for asparagine or glutamine or histidine) do not lead to proteins recognized as grossly "abnormal" by the cell's proteolysis systems.
Amino Acids↗
Strains of Escherichia coli carrying the structural gene for histidyl-tRNA synthetase on a high copy-number plasmid.
That portion of the Escherichia coli chromosome carried by a number of lambda transducing phages, all of which carry the gua operon, was mapped using restriction endonucleases. The DNA from one of these transducing phages was subcloned onto pBR322. We have identified two recombinant plasmids which carry the Escherichia coli gene hisS, the structural gene for histidyl-tRNA synthetase. The two plasmids, pSE301 and pSE401, have in common a 3,540 bp fragment of E. coli DNA which is bounded by BglII and SalI restriction endonuclease recognition sites. Strains carrying these plasmids overproduce histidyl-tRNA synthetase 20 to 30 fold. The growth rate of these strains is not affected although the histidine biosynthetic enzymes are derepressed. This derepression seems to be in addition to that caused by introduction of a hisT mutation on the chromosome.
Amino Acyl-tRNA Synthetases↗
Thallium chondrodystrophy in chick embryos: ultrastructural changes in the epiphyseal plate.
Using the transmission electron microscope, we sought to describe the morphology of thallium sulfate-induced chondrodystrophy in chick embryos. There was cell death and degeneration in all zones of growth cartilage, but the cells and matrix of the hypertrophic zone were the most severely affected. Ultrastructural changes of the hypertrophic chondrocytes consisted of alteration of the cytoplasmic contents and of the intercellular matrix; the cell membrane was smooth and without cytoplasmic extensions. The cytoplasm was filled with dilated rough endoplasmic reticulum, vacuoles of varying sizes and contents, and lipidlike bodies with electron-dense granules; mineral crystals, collagen, and degenerating mitochondria were present. The matrix showed only spotty calcification and a reduced number of dense bodies, vesicles, and granules. The cells appeared to have failed to exteriorize cell products across the plasmalemma. Failure to exteriorize cell products and to form cytoplasmic processes reduced the number of potential nucleation sites for calcification. The ultrastructure of osteocytes was much less affected.
Achondroplasia↗
On the accuracy of protein synthesis in Drosophila melanogaster.
We have investigated the accuracy of protein synthesis in somatic tissue of young and senescent Drosophila melanogaster by means of two-dimensional electrophoresis. Electrophoretic heterogeneity characteristic of translational error could not be detected at either age, placing the error frequency below about 4 X 10(-4) per codon. As a positive control on the efficacy of the technique, we showed that electrophoretic heterogeneity is detectable in bacterial cells grown in streptomycin, and that the error frequency calculated from these data is in good agreement with independent measurements. Such cells can tolerate an error frequency of about 3 x 10(-3) without cell lethality, or error catastrophe. Since the Drosophila somatic error frequency is at least eight times lower, even in senescent organisms, translational error is unlikely to be a cause of senescence in Drosophila.
Aging↗
Simplified pulmonary artery/right atrial pressure monitoring system.
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Atrial Function↗
Electron microscopic demonstration of the presence of amplified sequences at the 5'-ends of the polyoma virus late mRNAs.
Electron microscopic techniques were used to examine the structure of the leader sequences at the 5'-ends of the late polyoma virus mRNAs. The three late mRNA's were partially purified and hybridized to an E. coli plasmid containing two polyoma virus genomes inserted in tandem. The hybrids were spread by the cytochrome c-formamide technique and visualized in the electron microscope. These studies revealed that whereas the body of a given mRNA molecule can hybridize with only one of the two corresponding body sequences in the two adjacent viral genomes, the leader of the same mRNA molecule can hybridize with both copies of the leader sequence-specific DNA. The mVP1 and mVP3 RNA species thus generated hybrids containing two loops, while mVP2 molecules formed hybrids containing one loop. Hence, the leaders of the three polyoma virus late mRNA species must contain two or more repeats of a sequence transcribed from a unique DNA segment. Length measurements showed that most leaders in the late mRNA's consist of at least 200 nucleotides and some contain up to 500 nucleotides, whereas the basic repeat sequence contains about 60 nucleotides.
Base Sequence↗
Clinical and enzymological studies in a child with type I glycogen storage disease associated with partial deficiency of hepatic glucose-6-phosphatase.
1. GSD-I is described in a child with partial deficiency of hepatic glucose-6-phosphatase. 2. Growth retardation and hepatosplenomegaly were major clinical features. 3. Hyperlipidaemia, lactic acidaemia, hyperuricaemia and reduced uric acid clearance were major biochemical findings. 4. Although the glucose response to glucagon and galactose was impaired, there was a striking absence of hypoglycaemia which may be attributable to residual catalytic activity of the enzyme. 5. Preliminary studies of the crude liver enzyme showed it to have a normal pH inactivation profile and apparent Km with a reduced Vmax. 6. No evidence of increased PP-ribose-P availability in fresh liver tissue was detected. 7. Continuous glucose feeding resulted in accelerated growth without complete correction of lactic acidosis or hyperuricaemia. 8. GSD-I with partial deficiency of hepatic glucose-6-phosphatase should be considered in patients with gout or hyperuricaemia associated with hypertriglyceridaemia and lactic acidaemia even in the absence of hypoglycaemia.
Blood Glucose↗
"Two out of three" codon reading leading to mistranslation in vivo.
Strains of Escherichia coli were starved for asparagine or lysine in order to increase the in vivo level of mistranslation. In a relA strain, asparagine starvation increased the error frequency in elongation factor Tu to 0.12 mistake per asparagine codon, while with lysine starvation in the same strain the error frequency per lysine codon was 0.008. The pattern of isoelectric point changes in the altered protein produced is consistent with third position misreading in the AAN codon group. This high level of mistranslation is not seen in streptomycin resistant (rpsL) strains or in most relA+ strains.
Asparagine↗