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Biomedical subjects

L Taylor

Publications and source records attributed to L Taylor.

At least 253 records · Page 14Linked to original sources
PubMed1985

Use of heat-treated clotting-factor concentrates in patients with haemophilia and a high exposure to HTLV-III.

In a group of 126 Australian patients with haemophilia, who were receiving lyophilized clotting-factor concentrates prepared from locally collected plasma, a high prevalence of antibody to human T-cell lymphotropic virus III (HTLV-III) was demonstrated in those with severe disease. Patients with moderate or mild disease had a much lower prevalence of HTLV-III antibody. After heat treatment of lyophilized factor VIII and factor IX concentrates (60 degrees C for 72 hours) to inactivate the virus, the losses of activity of an intermediate-purity and of a fibrinogen-poor factor VIII concentrate, and of the coagulant activity of a factor IX concentrate, were within acceptable limits. The solubility of the intermediate-purity factor VIII concentrate was markedly decreased; the fibrinogen-poor factor VIII concentrate and the factor IX concentrate were readily soluble. In-vivo recovery and survival of heated concentrates were equivalent to those of the unheated products, and they were effective in the treatment of spontaneous and traumatic haemorrhages.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Adverse effects of iron supplementation: a comparative trial of a wax-matrix iron preparation and conventional ferrous sulfate tablets.

The acceptability of supplemental iron delivered from a wax-matrix tablet of ferrous sulfate was compared with that of a conventional ferrous sulfate tablet in a single-blind, parallel-group study. Both tablets were formulated to deliver 50 mg of elemental iron. The incidence of adverse effects was found to be significantly greater among 272 subjects taking the conventional tablets than among 271 subjects taking the wax-matrix preparation. Eighty-one percent of the subjects taking the wax-matrix preparation experienced no severe or moderate side effects as compared with only 50% of those taking the conventional tablets.

Adolescent↗
PubMed1984

Reference sera with graded levels of high density lipoprotein cholesterol.

A two-step procedure for the separation of low density lipoprotein (LDL)-rich fractions and high density lipoprotein (HDL)-rich fractions from human serum is presented. The isolated precipitates are combined separately with small volumes of human serum in order to stabilize the lipoproteins. Calculated volumes of concentrates are added to human serum or to delipidated human serum [1], so that reference sera with graded levels of high density lipoprotein cholesterol (HDLC) can be prepared. These reference sera resemble human serum in appearance, composition and fractionation by ultracentrifugation. Our evaluations of the materials described in this communication have shown them to be suitable for HDLC determinations, using the precipitation procedure with heparin-manganese chloride. Properties of these reference materials are discussed.

Chemical Precipitation↗
PubMed1984

Ca2+-calmodulin-, cyclic AMP- and cyclic GMP-induced phosphorylation of proteins in purified microvillus membranes of rabbit ileum.

Evidence is available to suggest that Ca2+-calmodulin and cyclic nucleotides are involved in the regulation of ion transport in rabbit ileum. Since both Ca2+-calmodulin and cyclic nucleotides exert many of their effects by phosphorylation, the effects of Ca2+-calmodulin and cyclic nucleotides on phosphorylation of purified microvillus membrane from rabbit ileal mucosa were evaluated. Ca2+-calmodulin increased phosphorylation of five microvillus-membrane peptides, with Mr values of 137000, 77000, 58000, 53000 and 50000. The increases in phosphorylation caused by Ca2+-calmodulin were: Mr-137000 peptide, 111 +/- 26%; Mr-77000 peptide, 71 +/- 17%; Mr-58000 peptide, 51 +/- 8%; Mr-53000 peptide, 113 +/- 20%. These increases were maximal at 1 microM-calmodulin and 0.3-0.9 microM free Ca2+; concentrations of Ca2+ causing half-maximal effects on phosphorylation for the different peptides were 0.06-0.12 microM. Cyclic AMP and cyclic GMP increased phosphorylation of two peptides, of Mr 137000 and 85000. The concentrations of cyclic nucleotides giving half-maximal phosphorylation of the Mr-137000 peptide were 0.3 microM-cyclic AMP and 4.6 microM-cyclic GMP, and for the Mr-85000 peptide, 3.9 microM-cyclic AMP and 0.05 microM-cyclic GMP. The maximal increase in phosphorylation of the Mr-137000 peptide was 200% for cyclic AMP and 95% for cyclic GMP, and that of the Mr-85000 peptide was 220% for cyclic AMP and 120% for cyclic GMP. These studies demonstrate the existence of Ca2+-calmodulin-, cyclic AMP- and cyclic GMP-dependent protein kinases and substrate proteins in purified rabbit ileal microvillus membranes and that Ca2+ can regulate phosphorylation of these proteins over the presumed physiological concentration range of cytosol free Ca2+.

Animals↗
PubMed1984

The F plasmid origin of transfer: DNA sequence of wild-type and mutant origins and location of origin-specific nicks.

The DNA sequence of the F plasmid origin of conjugal DNA transfer, oriT , has been determined. The origin lies in an intercistronic region which contains several inverted repeat sequences and a long AT-rich tract. Introduction of a nick into one of the DNA strands in the oriT region precedes the initiation of conjugal DNA replication, and the position of the strand-specific nicks acquired by a lambda oriT genome upon propagation in Flac-carrying cells has been determined. The nicks were not uniquely positioned, rather there was a cluster of three major and up to 20 minor sites: the biological significance of this observation is not yet fully clear. Nine independent point mutations which inactivate oriT function have been sequenced and found to alter one or other of two nucleotide positions which lie 14 and 19 bp to one side of the rightmost (as drawn) major nick site. These key nucleotides may lie in a recognition sequence for the oriT endonuclease, since mutations at these sites prevent nicking at oriT .

Base Sequence↗
PubMed1984

Factor VIII procoagulant antigen recovery is a dose-related response to Factor VIII concentrate infusions.

The recovery and initial half-disappearance rate of factor VIII procoagulant activity (VIIIC) and procoagulant antigen (VIIICAg) were studied in 9 haemophilia A patients following infusion of factor VIII concentrates to varying plasma VIIIC levels. While VIIIC recovery was independent of dose, the VIIICAg recovery varied in a dose-dependent fashion. The excess of VIIICAg relative to VIIIC found in the factor VIII concentrates (VIIICAg/VIIIC ratios of 1.9-3.1) was not observed in plasma samples taken after low level infusions (plasma VIIIC less than 1 U/ml) but a significant excess of VIIICAg was observed in higher level infusions. The VIIICAg recovery of post-infusion plasma was not increased by treatment with phospholipase C.

Antigens↗
PubMed1984

Portal hypertension and hypersplenism in pregnancy secondary to chronic schistosomiasis. A case report.

In this country, Schistosoma mansoni infections are seen rarely since the distribution of schistosomes in humans is governed by the range of their molluscan hosts. The snail hosts of S. mansoni reside in fresh waters of tropical zones. A native of Brazil was seen in her second trimester of pregnancy with marked splenomegaly and hypersplenism. Thirteen years before she had been treated for schistosomiasis, and she had been well until her pregnancy. Studies were done to rule out other causes of splenomegaly and hypersplenism. Esophageal endoscopy confirmed the presence of esophageal varices. The main risk to these patients is severe, sometimes fatal gastrointestinal bleeding. In our patient this risk was compounded by marked thrombocytopenia. Splenectomy was performed, and a liver biopsy confirmed the presence of S. mansoni eggs.

Adult↗
PubMed1983

The participation of hydroperoxides and oxygen radicals in the control of prostaglandin synthesis.

Our results demonstrate that the organic hydroperoxide t-butyl-hydroperoxide (TBHP) influences the synthesis of prostaglandins in the human embryo lung fibroblast. TBHP inhibits or stimulates prostaglandin synthesis as a function of its concentration. Regardless of the concentration employed in these experiments however, TBHP stimulated the release of arachidonate from lipid stores. When the arachidonate release step in prostaglandin (PG) synthesis was bypassed by the addition of free arachidonate to the cell cultures, t-butyl hydroperoxide further stimulated PG synthesis, indicating that the hydroperoxide activates arachidonate conversion to prostaglandins. 4-Hydroxy-2,2,6,6-tetramethylpiperidinoxy radical, a scavenger of oxygen radicals, when added to cell cultures alone had no measurable effect on either arachidonate release or prostaglandin synthesis. When 4-hydroxy-2,2,6,6-tetramethylpiperidinoxy radical was administered to cell cultures in combination with t-butyl hydroperoxide, it increased prostaglandin synthesis while inhibiting arachidonate release by the hydroperoxide. The participation of hydroperoxides and trappers of oxygen radicals in the regulation of PG synthesis is not unique to lung fibroblasts. Endothelial cells from the vasculature as well as fibroblasts from the cornea also appear to be affected by these compounds with respect to prostaglandin synthesis.

Arachidonic Acid↗
PubMed1983

The control region of the F plasmid transfer operon: DNA sequence of the traJ and traY genes and characterisation of the traY leads to Z promoter.

The complete nucleotide sequence of the F plasmid transfer genes traJ and traY, together with the promoter-proximal region of the traA gene has been determined. The traJ reading frame has been confirmed by sequencing the traJ90 amber mutant allele. The predicted amino acid sequence of the TraJ protein shows that this outer-membrane protein lacks a signal sequence. The pattern of codon usage within the traJ gene is different from that of genes for abundant outer-membrane proteins and is closer to that of genes that are expressed at relatively low levels. We have located the traY leads to Z operon promoter by in vitro run-off transcription experiments and have developed in vivo assays for the activity of the promoter by fusing it to galactokinase and kanamycin-resistance genes.

Bacterial Proteins↗
PubMed1983

Coal tar phototherapy for psoriasis reevaluated: erythemogenic versus suberythemogenic ultraviolet with a tar extract in oil and crude coal tar.

Recent studies have questioned the therapeutic value of coal tar versus ultraviolet (UV) radiation and their relative necessity in phototherapy for psoriasis. In this investigation, different aspects of tar phototherapy have been studied in single-blind bilateral paired comparison studies. The effects of 1% crude coal tar were compared with those of petrolatum in conjunction with erythemogenic and suberythemogenic doses of ultraviolet light (UVB) using a FS72 sunlamp tubed cabinet. Crude coal tar was clinically superior to petrolatum with suberythemogenic ultraviolet. With the erythemogenic UVB, petrolatum was equal in efficacy to crude coal tar. Suberythemogenic UVB was also used adjunctively to compare the effects of a 5% concentration of a tar extract in an oil base to 5% crude coal tar in petrolatum or the oil base without tar. The tar extract in oil plus suberythemogenic UVB produced significantly more rapid improvement than the oil base plus UVB. The direct bilateral comparison of equal concentrations of tar extract in oil base versus crude coal tar in petrolatum in a suberythemogenic UV photo regimen revealed no statistical differences between treatments. In a study comparing tar extract in oil and the oil base without ultraviolet radiation, the tar extract in oil side responded more rapidly. This demonstrates a direct effect of tar alone in therapy. We have also studied the effects of erythemogenic and suberythemogenic UVB with and without tar extract in oil in the hairless mouse epidermal deoxyribonucleic acid (DNA) synthesis suppression assay. It was found that erythemogenic dosages of UVB produced near maximal inhibition of DNA synthesis with or without coal tars. Suberythemogenic dosages of UVB produced submaximal suppression of DNA synthesis that was enhanced by adjunctive coal tar but not by vehicle, findings which are consistent with the above clinical results. These studies suggest that coal tars combined with suberythemogenic UVB therapy is a practical alternative (to more aggressive UVB therapy without coal tar) which reduces the UVB exposure to the patient.

Animals↗
PubMed1983

Pro-dynorphin peptides are found in the same neurons throughout rat brain: immunocytochemical study.

It is known that the opioid peptide dynorphin A has a broad distribution throughout the neuraxis. Recent biochemical studies have extended the sequence of dynorphin A by 15 amino acids to include another [Leu]enkephalin-containing peptide known as dynorphin B. These sequence data have been validated by the elucidation of the structure of the hypothalamic mRNA coding for alpha- and beta-neo-endorphin, dynorphin A, and dynorphin B. Using specific antisera directed against each of the three opioid peptides, we have studied their cellular distribution in rat brain. Their distribution patterns are extremely similar, if not identical. Furthermore, all three peptide immunoreactivities can be localized to the same cells in five nuclear groups throughout the brainstem--the supraoptic nucleus, the paraventricular nucleus, a group of cells in the lateral hypothalamic area, the nucleus parabrachialis, and the nucleus tractus solitarius. The sequence of a common precursor for dynorphin A, B, and alpha- and beta-neo-endorphin was deduced from hypothalamic mRNA. The ability to localize all three peptides together within cells in widely placed nuclei strongly supports the use of the same biosynthetic precursor for the neo-endorphin and dynorphin peptides in other parts of the central nervous system as well.

Animals↗