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Biomedical subjects

K H Thompson

Publications and source records attributed to K H Thompson.

35 records · Page 2Linked to original sources
PubMed1989

Effects of dietary protein on food and water intake in spontaneously hypertensive rats.

We have been studying the development of hypertension in spontaneously hypertensive rats (SHR) fed a low protein diet. The effects of a low protein diet upon food and water intake were examined. Body weight gain, food and water intake were measured in three to twenty-three week-old SHR and Wistar Kyoto rats (WKY) fed diets containing 8%, 15% or 25% casein. Body weights of SHR and WKY fed an 8% casein diet were significantly lower at 23 weeks than rats on the higher protein diets, although both groups on the 8% diet consumed more food and water per g of body weight. In addition, SHR fed an 8% casein diet drank less water per gram of food than WKY or SHR fed 15% and 25% casein diets. These results indicate that changes in food and water intake, as a consequence of low protein diets, should be an additional consideration when examining the effects of dietary protein on the development of hypertension.

Animals↗
PubMed1988

Arabinofuranosyl nucleosides induce common fragile sites.

The capacities for fragile site induction of three inhibitors of semiconservative DNA synthesis and DNA repair synthesis, aphidicolin, arabinofuranosyl cytosine, and arabinofuranosyl adenosine were compared. Aphidicolin is known to induce type 4 fragile sites, the largest recognized group of common fragile sites. Although the modes of action of these inhibitors vary, both arabinofuranosyl analogs induce type 4 aphidicolin-sensitive fragile sites. An analysis of variance demonstrates that the three inhibitors are not equally capable of inducing significant breakage (P less than 0.01) at all type 4 fragile sites. Induction of type 4 fragile sites appears to be a general consequence of inhibition of DNA polymerization.

Aphidicolin↗
PubMed1988

Gene mapping with recombinant inbreds in maize.

Recombinant inbred lines of maize have been developed for the rapid mapping of molecular probes to chromosomal location. Two recombinant inbred families have been constructed from F2 populations of T232 X CM37 and CO159 X Tx303. A genetic map based largely on isozymes and restriction fragment length polymorphisms has been produced that covers virtually the entire maize genome. In order to map a new gene, an investigator has only to determine its allelic distribution among the recombinant inbred lines and then compare it by computer with the distributions of all previously mapped loci. The availability of the recombinant inbreds and the associated data base constitute an efficient means of mapping new molecular markers in maize.

Chromosome Mapping↗
PubMed1983

Lack of secretion of retinyl ester by livers of normal and cholesterol-fed rabbits.

The use of retinyl ester as a tracer for chylomicrons and chylomicron remnants depends on the observation that newly absorbed dietary retinol is transported as retinyl ester in plasma chylomicrons or chylomicron remnants and also on the assumption that organs other than intestine do not contribute retinyl ester to plasma. To measure the secretion of retinyl ester by rabbit liver, the liver was labeled by injecting labeled retinol intravenously 1) as a colloidal dose, 2) incorporated into liposomes or 3) dispersed in a solution of Tween 20. Depending on the dose, between 63 and 80% of the labeled retinol in the liver was esterified and was found in both parenchymal and nonparenchymal cells. For all types of doses in both normal and cholesterol-fed rabbits, less than 1% of the injected dose was present in the plasma as retinyl ester during the 24-hour time period after injection. The secretion of retinyl ester by liver in response to the uptake of retinyl ester-enriched chylomicrons was also measured. This was done by feeding a diet enriched in retinol followed by a retinol-free diet. Only an insignificant quantity of retinyl ester accumulated in plasma during a 24-hour period after blocking the removal of triglyceride-rich lipoproteins with Triton WR 1339. Apparently, there is little, if any, secretion of retinyl ester by the liver of normal or cholesterol-fed rabbits.

Animals↗
PubMed1983

Plasma very low density lipoprotein (VLDL) in cholesterol-fed rabbits: chylomicron remnants or liver lipoproteins?

When iodinated hypercholesterolemic plasma very low density lipoprotein (VLDL), chylomicrons or chylomicron remnants were injected intravenously, the apoB of chylomicrons and chylomicron remnants was removed more rapidly than apoB of hypercholesterolemic VLDL. In perfused livers from normal or cholesterol-fed rabbits, chylomicron remnants were removed 69% and 125% more rapidly, respectively, than hypercholesterolemic VLDL. Chylomicron remnants were removed equally well by perfused livers from normal and cholesterol-fed rabbits, but hypercholesterolemic plasma VLDL was removed more slowly by perfused livers of cholesterol-fed than by those of normal rabbits. Chylomicron remnant removal by livers from normal and cholesterol-fed rabbits was inhibited by high levels of hypercholesterolemic plasma VLDL in the perfusate. Twenty-four hours after a single dose of retinyl ester was fed to cholesterol-fed rabbits, less than 1% of the absorbed retinol remained in the plasma as retinyl ester. Thus, increases in plasma VLDL cholesterol levels in cholesterol-fed rabbits cannot be accounted for by the accumulation of chylomicron remnants. Apparently, a cholesterol-rich VLDL, probably of hepatic origin, accumulates in the postabsorptive plasma of the cholesterol-fed rabbit.

Animals↗
PubMed1982

Exchange of retinyl and cholesteryl esters between lipoproteins of rabbit plasma.

Normal or hypercholesterolemic rabbit plasma stimulates the transfer of retinyl ester as well as cholesteryl ester from rabbit lymph chylomicrons, chylomicron remnants or from cholesteryl ester-rich plasma VLDL to the d greater than 1.019 lipoprotein fractions. The presence of p-chloromercuriphenylsulfonate does not inhibit the transfer of these esters. Partially purified lipid transfer protein from rabbit or from human plasma also accelerates the transfer of the above esters. Whereas the rabbit plasma transfer protein preferentially accelerates the transfer of retinyl ester, the human plasma transfer protein appears to have a somewhat greater stimulating effect on the transfer of cholesteryl ester from low- to high-density lipoproteins.

Animals↗
PubMed1980

Cyclic oscillation of blood neutrophils in a patient with multiple myeloma.

A patient with multiple myeloma developed periodic blood neutropenia (periodicity of 15-25 days) after 3 yr of intermittent treatment with cytotoxic agents. Peaks of serum colony-stimulating activity (CSA) level coincided with valleys of blood neutrophils. Fraction of marrow neutrophils in the multiplicative pool was high during blood neutrophil valleys and low during neutrophil peaks. In contrast, the maturation storage pool exhibited the reverse pattern. An increased fraction of marrow neutrophilic cells in the multiplicative pool was in active proliferation during a blood neutrophil valley and a decreased fraction during a blood neutrophil peak. These findings suggest that the marrow granulopoiesis was regulated through CSA. The defect causing the periodicity was probably related to the reduced number of neutrophils in the marrow maturation storage pool, which in turn may be related to a reduced and/or defective granulocytic stem cell pool size consequent to the long-term administration of cytotoxic drugs and/or infiltration of the marrow by myeloma cells.

Agranulocytosis↗
PubMed1978

HbAlc--an indicator of diabetic control.

Hemoglobin Alc levels were determined on 16 nondiabetic and 115 diabetic subjects. Twelve of the diabetic patients were newly diagnosed and 12 were in the remission phase. The mean percentage of HbAlc in the nondiabetic subjects was 4.33 +/- 0.39 (SE), in those with long-standing diabetes 8.34 +/- 0.23 SE, in newly diagnosed diabetic patients 8.99 +/- 0.50 SE, and in those undergoing partial remission 5.16 +/- 0.18 SE. The mean HbAlc levels of these four groups differed significantly (0.001 less than P less than 0.025). Among the diabetic subjects there was a good correlation between HbAlc level and such measures as fasting blood sugar, urinary sugar, and degree of diabetic control, whereas the correlations between HbAlc and age, sex, or duration of the disease were not significant. The obtained data show that HbAlc measurement can serve as an objective measure of glucose control in diabetic subjects.

Adolescent↗
PubMed1976

Exciton interaction among chlorophyll molecules in bacteriochlorophyllaproteins and bacteriochlorophyllareaction center complexes from green bacteria.

Absorption and CD spectra of bacteriochlorophyll a proteins and bacteriochlorophyll a reaction center complexes from two strains of Chlorobium limicola were recorded at 77 degrees K. Visual inspection showed that the Qy-band of chlorophyll in either protein was split into at least five components. Analysis of the spectra in terms of asymmetric Gaussian component pairs by means of computer program GAMET showed that six components are necessary to fit the spectra from strain 2K. These six components are ascribed to an exciton interaction between the seven bacteriochlorophyll a molecules in each subunit. The clear difference between the exciton splitting in the two bacteriochlorophyll a proteins shows that the arrangement of the chlorophyll molecules in each subunit must be slightly different. The spectra for the bacteriochlorophyll a reaction center complexes have a component at 834 nm (absorption) and 832 nm (CD) which does not appear in the spectra of the bacteriochlorophyll a proteins. The new component is ascribed to a reaction center complex which is combined with bacteriochlorophyll a proteins to form the bacteriochlorophyll a reaction center complex. The complete absorption (or CD) spectrum for a given bacteriochlorophyll a reaction center complex can be described to a first approximation in terms of the absorption (or CD) spectrum for the corresponding bacteriochlorophyll a protein plus the new component ascribed to the reaction center complex.

Bacteria↗
PubMed1975

Quantitative dose-response of growth and development in Arabidopsis thaliana exposed to chronic gamma-radiation.

The response of Arabidopsis thaliana (L.) Heynh. (Cruciferae) to a gradient of chronic gamma-radiation was examined under field conditions. Plants that were initially introduced to the gamma field as dry seeds received exposures of 1-34 to 18 800 R/20 hour day from the time of seed germination. Regression analysis demonstrated a significant, but non-linear, response for three variables, number of seedlings emerging, number of plants flowering, and plant volume; the response of a fourth variable, number of leaves per plant, was not related to daily exposure. LD50 values ranged from 66 R/20 hour day for plant volume to 1231 R/20 hour day for seedling emergence. Flowering and plant volume were the most sensitive indicators of radiation exposure. The demonstration of a variable threshold at low levels of exposure indicates that in nature A. thaliana may be exposed to environmental radiation throughout its life-cycle without significant modification of growth or development.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

Myocardial lipid turnover in dilated cardiomyopathy: a dual in vivo tracer approach.

BACKGROUND: Myocardial lipid metabolism appears abnormal in dilated cardiomyopathy (DCM). A dual-tracer approach with two different fatty acid analogs may allow us to observe such alteration in vivo. 15-(Ortho-123I-phenyl)-pentadecanoic acid (oPPA) and 15-(para-123I-phenyl)-pentadecanoic acid (pPPA) have similar kinetics in circulation, diffusion, and transport. However, pPPA in normal myocardium undergoes beta-oxidation and may also be lost from myocardial cells through back-diffusion; oPPA is hardly catabolized and normally retained mainly in the cytosolic lipid pool. Use of both pPPA and oPPA in the dual-tracer approach focuses observation on the turnover of myocardial lipids (with pPPA) that is scaled against loss of fatty acid through back-diffusion into circulation (with oPPA). METHODS AND RESULTS: Fifteen patients with idiopathic DCM and five control subjects were given oPPA and pPPA sequentially for dynamic planar scintigraphy. Uptake and elimination rates were determined for both substrates from three myocardial regions per individual; the corresponding six elimination rate constants and the three differences between them were analyzed for significant alterations in patients from control values. At least 66% of the patients had a significant alteration in myocardial lipid turnover in three types of patterns: (1) increased beta-oxidation, (2) decreased beta-oxidation, and (3) increased back-diffusion, in part associated with decreased beta-oxidation. Even with the limited number of patients and control subjects, the pattern of abnormality of lipid turnover in DMC appeared to be consistent individually but heterogeneous in the patient group. Moreover, a highly significant increase in beta-oxidation was observed for the posterolateral region of the myocardium compared with the anteroseptal and apical regions in control subjects and patients. CONCLUSION: The dual-tracer approach uncovered in vivo that in at least two thirds of the patients with DCM myocardial lipid turnover was significantly altered compared with control values.

Cardiomyopathy, Dilated↗
PubMedDate not supplied

Improvement in cardiac dysfunction in streptozotocin-induced diabetic rats following chronic oral administration of bis(maltolato)oxovanadium(IV).

Decreased cardiac function in streptozotocin-diabetic rats has been used as a model of diabetes-induced cardiomyopathy, which is a secondary complication in diabetic patients. The present study was designed to evaluate the therapeutic effect of a new organic vanadium complex, bis(maltolato)oxovanadium(IV), (BMOV), in improving heart function in streptozotocin-diabetic rats. There were four groups of male, Wistar rats: control (C), control treated (CT), diabetic (D), and diabetic treated (DT). Treatment consisted of BMOV, 0.5 mg/mL (1.8 mM) for the first 3 weeks and 0.75 mg/mL (2.4 mM) for the next 22 weeks, in the drinking water of rats allowed ad libitum access to food and water. BMOV lowered blood glucose to < 9 mM in 70% of DT animals without any increase in plasma insulin levels, and mean blood glucose and plasma lipid levels were significantly lower in DT vs. D rats. Tissue vanadium levels were measured in plasma, bone, kidney, liver, muscle, and fat of BMOV-treated rats. Plasma vanadium levels averaged 0.84 +/- 0.07 microgram/mL (16.8 microM) in CT rats and 0.76 +/- 0.05 microgram/mL (15.2 microM) in DT animals. The highest vanadium levels at termination of this chronic feeding study were in bone, 18.3 +/- 3.0 micrograms/g (0.37 mumol/g) in CT and 26.4 +/- 2.6 micrograms/g (0.53 mumol/g) in DT rats, with intermediate levels in kidney and liver, and low, but detectable levels in muscle and fat. There were no deaths in either the CT or DT group, and no overt signs of vanadium toxicity were present. Tissue vanadium levels were not correlated with the glucose-lowering effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗