Biomedical subjects
J Gore
Publications and source records attributed to J Gore.
Superoxide and peroxynitrite in atherosclerosis.
The role of reactive oxygen species in the vascular pathology associated with atherosclerosis was examined by testing the hypothesis that impaired vascular reactivity results from the reaction of nitric oxide (.NO) with superoxide (O2-), yielding the oxidant peroxynitrite (ONOO-). Contractility studies were performed on femoral arteries from rabbits fed a cholesterol-supplemented diet. Cholesterol feeding shifted the EC50 for acetylcholine (ACh)-induced relaxation and impaired the maximal response to ACh. We used pH-sensitive liposomes to deliver CuZn superoxide dismutase (SOD; superoxide:superoxide oxidoreductase, EC 1.15.1.1) to critical sites of .NO reaction with O2-. Intravenously injected liposomes (3000 units of SOD per ml) augmented ACh-induced relaxation in the cholesterol-fed group to a greater extent than in controls. Quantitative immunocytochemistry demonstrated enhanced distribution of SOD in both endothelial and vascular smooth muscle cells as well as in the extracellular matrix. SOD activity in vessel homogenates of liposome-treated rabbits was also increased. Incubation of beta very low density lipoprotein with ONOO- resulted in the rapid formation of conjugated dienes and thiobarbituric acid-reactive substances. Our results suggest that the reaction of O2- with .NO is involved in the development of atherosclerotic disease by yielding a potent mediator of lipoprotein oxidation, as well as by limiting .NO stimulation of vascular smooth muscle guanylate cyclase activity.
The phylogeny of the tomato leaf mould fungus Cladosporium fulvum syn. Fulvia fulva by analysis of rDNA sequences.
The nucleotide sequence of part of the ribosomal DNA from races of the fungal tomato pathogen Cladosporium fulvum and other Cladosporium species have been determined. Comparisons of the internal transcribed spacer regions (ITS1 and ITS2) of several C. fulvum races showed complete sequence homology suggesting a recent evolutionary divergence. Comparisons of these nucleotide sequences in the ITS region with those of other Cladosporium species showed the close relationship within the Cladosporium genus. Using the nucleotide sequence of part of the 18s ribosomal subunit from these isolates and comparing them with sequences of some Ascomycetes, Basidiomycetes and Chytridiomycetes, obtained from GenBank, we infer the phylogeny of the Cladosporium species studied here. Our analysis shows that the Cladosporia form a monophyletic group which falls within the order Ascomycotina.
The cost of improving the outcome for infants of birthweight 500-999 g in Victoria. The Victorian Infant Collaborative Study Group.
The aim of this study was to conduct an economic evaluation of neonatal intensive care for extremely low birthweight (ELBW) infants born in the state of Victoria. Two distinct eras (1979-80 and 1985-87) were compared. Follow-up data at 2 years of age were available for all 89 survivors from the 351 live births in 1979-80, and for 211 of 212 survivors from the 560 live births in 1985-87. The overall cost-effectiveness for ELBW infants during 1985-87 compared with 1979-80 was $104,990 ($A 1987) per additional survivor, or $5390 ($A 1987) per additional life year gained. Cost-effectiveness improved with increasing birthweight. If the quality of life of the survivors was considered, the economic outlook was more favourable. The cost per quality-adjusted life year gained was $5090 ($A 1987), approximately one-tenth of that obtained from the only previous full economic evaluation of neonatal intensive care. Although neonatal intensive care is expensive, it compares favourably with some other health care programmes, particularly as the outcome for ELBW infants continues to improve.
Synthesis of digoxigenin-labeled cRNA probes for nonisotopic in situ hybridization using reverse transcription polymerase chain reaction.
Nonisotopic methods of mRNA in situ hybridization have distinct advantages over isotopic techniques. Nonisotopically labeled probes are stable and nontoxic, have short detection times, demonstrate excellent spatial resolution of their signals and have sensitivities comparable to radiolabeled probes. We developed a simple method of generating nonisotopically labeled cRNA probes which is based on the reverse transcription polymerase chain reaction (RT-PCR) and used it to synthesize a panel of probes for various murine extracellular matrix genes. Engelbreth-Holm-Swarm (EHS) tumor RNA was reverse transcribed and PCR was used to amplify defined regions of multiple extracellular matrix protein genes from the resulting first strand cDNAs. Bacteriophage promoters which had been incorporated into the PCR products were then used to generate digoxigenin-conjugated antisense and sense cRNAs. The antisense probes were employed to detect the specific extracellular matrix protein mRNAs in the EHS tumor by in situ hybridization. This technique provides a rapid and efficient alternative to conventional transcription systems which use plasmid vectors for the synthesis of digoxigenin-labeled cRNA probes.
Demonstration of endothelial adhesion of sickle cells in vivo: a distinct role for deformable sickle cell discocytes.
Different morphologic and density classes of sickle cells (SS) may play distinct roles in the generation of vasoocclusion, explaining the complexity of this phenomena. The densest SS red blood cells (RBCs) (SS4) can induce vasoocculsion in ex vivo microcirculatory preparations as well as in an intact animal model. Previous studies of the interaction of SS deformable discocytes with endothelial monolayers or the rat ex vivo mesocecum preparation have shown adhesion that is desmopressin (dDAVP)-stimulated, von Willebrand factor (vWF)-mediated, and limited to the small venules. However, in vivo adhesion of SS RBCs to the endothelium has neither been demonstrated nor characterized; and, in particular, the relation of adhesion to vasoocclusion is unknown. Using an intact animal model that involves injecting saline-washed, density-defined SS RBCs into the femoral artery of a rat, we find that: (1) Quantitative studies of RBCs retained in the rat thigh using 99mTc-labeled RBCs and gamma camera imaging showed that dDAVP induces a threefold increase in retention of normal (AA) cells and deformable SS discocytes (SS2). (2) electron microscopy and Microfil injection show that the retention of SS2 cells is due to adhesion to the vascular endothelium with no evidence of obstruction. (3) H-1 magnetic resonance imaging showed that retention of SS4 cells induced a dose-dependent increase in tissue edema (presumable secondary to tissue hypoxia), while retention of AA or SS2 cells produced no change. We conclude that endothelial adhesion of deformable SS discocytes can be demonstrated in an in vivo animal model, that this adhesion is enhanced by dDAVP (presumably related to, but not necessarily limited to the release of vWF), and that this phenomenon per se does not lead to vasoocclusion. Nevertheless, adhesion of deformable SS discocytes may have consequences. We hypothesize that adhesion of SS discocytes could narrow the lumen of postcapillary venules and facilitate secondary trapping of SS4 cells and lead to subsequent vasoocclusion.
The effect of a novel inhibitor of aldehyde dehydrogenase on viral replication.
The effect of AMPAL (4-amino 4-methyl 2-pentyne 1-al), an inhibitor of aldehyde dehydrogenase, on adenovirus type 5 (Ad5) replication was studied. AMPAL at 2 x 10(-4) M clearly reduced the cytopathic effect on HeLa cells but had no effect on cell growth at this concentration. Viral adsorption, penetration and protein synthesis were not affected by adding AMPAL at 2 hr post infection. When viral DNA synthesized in the presence of AMPAL was investigated, no significant inhibition was observed on either synthesis or the physicochemical properties of the neosynthesized DNA. However, there was a 4-fold increase in the amount of condensed DNA. In addition, AMPAL inhibited intracellular viral production (40%) and brought about concomitant inhibition of virus release (70%) into the medium. The absence of a quantitative relationship between the inhibition of viral DNA synthesis on one hand and that of viral production on the other may imply that the antiviral effect of AMPAL is indirectly mediated by the action of the malondialdehyde which has accumulated on some, as not yet identified, membrane constituent.
Magnetic field modulation of receptor binding.
Although it is widely held that the magnetic fields encountered during magnetic resonance imaging (MRI) and other procedures have no discernible effect on biological systems, we find that at early times of incubation, the amount of binding of the neurotoxin, alpha-bungarotoxin, to nicotinic acetylcholine receptor is significantly reduced in a constant 2.0-T magnetic field. This finding suggests that steady magnetic fields can directly affect the functional activity of biologically important macromolecules, in this particular case a neurotransmitter receptor.
Uterine junctional zone: MR study of water content and relaxation properties.
Weighted samples of uterine myometrium, junctional zone, and endometrium were excised for determination of T1 and T2 in a 20-MHz spectrometer and then dried for determination of water content. The remainder of each uterus, examined with special histopathologic stains, demonstrated no significant difference in the number of blood vessels, smooth muscle cells, fibroblasts, elastin, iron, collagen, mucin, polysaccharide, or amyloid. The junctional zone water content (79.28%) was significantly lower than that of endometrium (82.88%, P = .004) and myometrium (81.05%, P = .005). The T1 of the junctional zone (ie, 643) was significantly lower than that of endometrium (ie, 836; P = .004) and myometrium (ie, 709; P = .01). The T2 of the junctional zone (ie, 58) was significantly lower than that of endometrium (ie, 87; P = .003) and myometrium (ie, 67; P = .006). The low signal intensity of the junctional zone on T2-weighted MR images is accounted for by its lower water content and T2, while the brightness on T1-weighted images is due to its reduced T1.
A comparison of accessibility of ribosomal proteins on free and membrane-bound ribosomes: the ribosomal proteins potentially involved in ribosome-membrane binding.
The relative accessibility of rat liver ribosomal proteins to reductive methylation was examined using membrane-bound and free ribosomes. Comparisons indicated that 12-13 large ribosomal proteins are masked by ribosomal association with membranes. These consisted of L8, L10, L17, L26-28, L31 and L36, and probably also include L4, L5, L7 and L29. These proteins seem to surround a region centered about L3 and may partly define a ribosomal channel through which the nascent peptide emerges. Approx. 10-20% of the large ribosomal subunit surface area is shielded by the membrane.
Malondialdehyde production from spermine by homogenates of normal and transformed cells.
The oxidation of spermine in vitro by a mixture of polyamine oxidase and diamine oxidase from pig kidney gives rise to malondialdehyde via 3-aminopropanol as the intermediate. Conversely, with spermidine, under similar experimental conditions, no evidence could be obtained for malondialdehyde formation within the limits of sensitivity of the assay (2.0 nmol). The activities of both these enzymes show about a 2-fold increase in normal rat kidney cells (LA31 NRK) transformed by the temperature sensitive mutant of Rous sarcoma virus (LA31) and incubated at the non permissive temperature (39 degrees C) compared to the activities in LA31 NRK at the permissive temperature (33 degrees C). These same enzymatic activities show no temperature dependent changes in normal rat kidney cells (NRK) or in these same cells infected by the wild type virus (NRK B77). In extracts derived from Friend erythroleukemic cells induced to differentiate by dimethyl sulfoxide or hexamethylene bis acetamide, spermine oxidation takes place more efficiently than in non induced cells. A rise in diamine oxidase activity is seen in LA31 NRK (39 degrees C) 12 h after the temperature shift, whereas morphological manifestations of normalcy are seen only at 48 h. The Km of diamine oxidase is 10(-6) M for putrescine and 10(-3) M for 3-aminopropanol. A possible mechanism involving the well documented acetylation of putrescine [23,26] is proposed for diverting intracellular putrescine away from cytosolic diamine oxidase and towards intramitochondrial monoamine oxidase.
Evidence for facilitated transport of biotin by hamster enterocytes.
The uptake of biotin by isolated hamster intestinal cells was investigated in the zone of physiological concentrations. Uptake of the vitamin was not a linear function of the external concentrations and kinetics could be saturated [Km = 1.12 microM, Vmax = 33.9 pmol/(mg protein X min)]. Metabolic inhibitors (antimycin A, 2,4-dinitrophenol) had no effect, so uptake is not energy dependent. Ouabain and N-ethylmaleimide, inhibitors of cation gradients, had no effect on biotin uptake, thus showing the absence of cotransport. The inhibition of uptake by analogs of biotin, that is, biocytin and DL-thioctic acid, indicates that the terminal carboxyl group and the thiophane ring play a role in the recognition of biotin. Counterflow experiments showed competitive inhibition of efflux when excess biotin was present in the cells. These findings are consistent with biotin uptake by isolated hamster enterocytes being a process of facilitated diffusion.
The effect of intravenous thrombolytic therapy on left ventricular function: a report on tissue-type plasminogen activator and streptokinase from the Thrombolysis in Myocardial Infarction (TIMI Phase I) trial.
In Phase I of the NHLBI trial of Thrombolysis in Myocardial Infarction (TIMI), 290 patients admitted within 7 hr after onset of acute infarction were randomly assigned to intravenous treatment with either streptokinase (SK) or recombinant tissue-type plasminogen activator (rt-PA). Left ventricular function was measured from contrast ventriculograms in 145 patients with both pretreatment and predischarge studies analyzable. Regional wall motion in the infarct site was measured by the centerline method and expressed in units of standard deviations (SDs) from the mean motion in 52 normal subjects. Patients treated with rt-PA (n = 77) achieved a significantly higher reperfusion rate after 90 min of treatment. Perfusion of the infarct-related artery improved from visual grade 0 or 1 (total occlusion or penetration without perfusion) to grade 2 or 3 (partial or full reperfusion) in 62% receiving rt-PA vs 31% receiving SK (n = 68) (p less than .001). However, the ejection fraction did not change significantly from before treatment to before discharge in either treatment group (+0.7 +/- 6.7% vs +1.0 +/- 8.3%, respectively). A small but significant increase in regional wall motion was observed in each of the two groups (+0.4 +/- 0.8 vs +0.3 +/- 0.8 SD/chord, respectively; each p less than .001 compared with baseline). This was countered by declines in the hyperkinesis of the noninfarct region (-0.3 +/- 1.0 SD/chord [p = .01] compared with baseline and -0.2 +/- 1.0 SD/chord [p = .23], respectively). Analysis of the combined groups revealed that the ejection fraction increased only in patients who achieved reperfusion by 90 min after onset of therapy or who had subtotal occlusions initially. There was greater recovery of left ventricular function in patients who achieved reperfusion earlier vs later than 4 hr after symptom onset and in patients with vs without some collateral circulation to the infarct-related artery.
Hospital system interfaces--a strategic advantage.
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Diffuse fatty infiltration of the liver by magnetic resonance.
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Female pelvic anatomy: MR assessment of variations during the menstrual cycle and with use of oral contraceptives.
Magnetic resonance (MR) imaging was performed on 21 women in different phases of the menstrual cycle, nine who used oral contraceptives and 12 who did not. Sagittal images in a dual spin-echo sequence were obtained to assess conspicuity and dimensions of the corpus uteri, cervix, vagina, and their component tissues. The endometrium, junctional zone, myometrium, cervical canal, fibrous stroma, and vaginal canal were seen in all cases and the vesicovaginal septum, rectovaginal septum, and levator ani in 90%, 86%, and 100%, respectively. The uterus was retrodisplaced in 19% of the women. In the nonpill group, endometrial width was significantly larger (P less than .025) in the secretory phase (mean, 5 mm) than in the follicular phase (3.1 mm). In the pill-using group, endometrial width was 1.1 mm in both phases, significantly smaller than in the nonpill group (P less than .025, follicular; P less than .0005, secretory). Junctional zone width was significantly smaller in the pill-using group (P less than .005). Qualitatively, the myometrium was relatively brighter on second echo images in the pill-using group, compatible with known edema that occurs with use of oral contraceptives. MR can reliably demonstrate gynecologic structure and anatomic changes that occur during the menstrual cycle and with use of oral contraceptives.
[Value of lyophilization in the biological study of fecal matter].
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Aspergillus flavus as a cause of thyroiditis in an immunosuppressed host.
Disseminated aspergillosis is a major complication in immunosuprressed patients. Infiltration of the thyroid with Aspergillus organisms occurs in approximately 20% of autopsies in patients dying with disseminated disease. The present report describes Aspergillus thyroiditis, Hashimoto's thyroiditis, and possible hypothyroidism in a patient with disseminated aspergillosis.