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Biomedical subjects

P Lund

Publications and source records attributed to P Lund.

At least 109 records · Page 6Linked to original sources
PubMed1982

Binding of branched-chain 2-oxo acids to bovine serum albumin.

1. Binding of branched-chain 2-oxo acids to defatted bovine serum albumin was shown by gel chromatography and equilibrium dialysis. 2. Equilibrium-dialysis data suggest a two-side model for binding in Krebs-Henseleit saline at 37 degrees C with n1 = 1 and n2 = 5. Site association constants were: 4-methyl-2-oxovalerate, k1 = 8.7 x 10(3) M-1, k2 = 0.09 x 10(3) M-1; 3-methyl-2-oxovalerate, k1 = 9.8 x 10(3) M-1, k2 = 0.08 x 10(3) M-1; 3-methyl-2-oxobutyrate, k1 = 1.27 x 10(3) M-1, k2 = less than 0.05 x 10(3) M-1. 3. Binding of 4-methyl-2-oxovalerate to defatted albumin in a phosphate-buffered saline, pH 7.4, gave the following thermodynamic parameters: primary site delta H0(1) = -28.6kJ . mol-1 and delta S0(1) = -15.2J . mol-1 . K-1 (delta G0(1) = -24.0kJ . mol-1 at 37 degrees C) and secondary sites delta H0(2) = -25.4kJ . mol-1 and delta S0(2) = -46.1J . mol-1 . K-1 (delta G0(1) = -11.2kJ . mol-1 at 37 degrees C). Thus binding at both sites is temperature-dependent and increases with decreasing temperature. 4. Inhibition studies suggest that 4-methyl-2-oxovalerate may associate with defatted albumin at a binding site for medium-chain fatty acids. 5. Binding of the 2-oxo acids in bovine, rat and human plasma follows a similar pattern to binding to defatted albumin. The proportion bound in bovine and human plasma is much higher than in rat plasma. 6. Binding to plasma protein, and not active transport, explains the high concentration of branched-chain 2-oxo acids leaving rat skeletal muscle relative to the concentration within the tissue, but does not explain the 2-oxo acid concentration gradient between plasma and liver.

Animals↗
PubMed1982

Adaptation of urate synthesis in chicken liver.

1. Urate synthesis was measured in hepatocytes from chickens after starvation or high-protein feeding. Adaptation occurred only on the high-protein diet. 2. The theoretical balances of reactions from alanine (5 alanine + 3 O2 = urate + 1.5 glucose + glycine) and asparagine (3 asparagine + 2 O2 = urate + ammonia + 0.5 glucose + glycine) agree reasonably well with the experimental results. 3. Enzymes directly involved in urate synthesis from these amino acids increase up to 12-fold on the high-protein diet; only amidophosphoribosyltransferase activity appears to be rate-limiting for urate synthesis. 4. The processes of nitrogen disposal in chicken and rat are compared and discussed.

Alanine↗
PubMed1982

Acid glycosaminoglycans in myxoedema.

Acid glycosaminoglycans were measured in the tissues of a virtually untreated 83-year-old woman with myxoedema. Intercellular oedema was demonstrated histologically in the tongue, myocardium, striated muscles, and in the skin. Tissue oedema was absent in two female control patients. All tissues from the patient with myxoedema, apart from the stomach, showed high concentrations of hyaluronic acid, but there was no consistent elevation of chondroitin-4,6-sulphate, heparan sulphate or dermatan sulphate. The accumulation of hyaluronic acid might contribute to the oedema formation in myxoedema.

Aged↗
PubMed1981

Depression, anhedonia and anxiety in temporomandibular joint and other facial pain syndromes.

Depression, anhedonia, state anxiety (A-state), trait anxiety (A-trait), and self-reported pain estimate were measured in almost 500 facial pain patients. These patients were divided into 3 diagnostic categories: myofacial pain dysfunction syndrome (MPD) [18], arthritis of the temporomandibular joints (TMJ arthritis), and trigeminal neuralgia. Three control groups were measured for comparison. They consisted of an normal, or non-patient group, a group of arthritis patients, and a group of movement disorder patients attending a neurology clinic. Among the facial pain patients and the normal controls few differences were found with regard to anhedonia and depression, The arthritis and neurology patients produced significantly higher depression and anhedonia scores than did several of the facial pain groups. Pain estimate ranged from 0 for control, to a mean of 67.6 +/- 31.3 for the trigeminal neuralgia patients with the MPD (means = 56.2 +/- 32.5) and the TMJ arthritis patients (means = 46.7 +/- 30.8) somewhat lower. Clinical variables such as duration of pain, help seeking behavior and total number of symptoms were correlated with depression but not with anhedonia scores, It is hypothesized that anhedonia is a measure separate from depression and may be more closely linked to suffering behavior that to pain behavior. Psychological variables did not discriminate among facial pain patients and in particular did not distinguish between so-called functional and organic illness.

Adult↗
PubMed1981

Transient acute renal failure and functional hemispheric depression after cerebral arteriography in diabetic patients.

Cerebral angiography was carried out in two diabetic patients in the evaluation of minor vascular ischemic episodes. A transient acute renal failure following cerebral angiography was accompanied by a transient comatose episode with severe unilateral neurological deficits. A functional depression of the injected hemisphere due to a contrast induced impairment of the blood-brain barrier is suggested as the pathophysiological background of the neurological complication.

Acute Kidney Injury↗
PubMed1980

Enzymic determination of branched-chain amino acids and 2-oxoacids in rat tissues. Transfer of 2-oxoacids from skeletal muscle to liver in vivo.

1. A procedure is described for the purification of leucine dehydrogenase (EC 1.4.1.9) from Bacillus subtilis. 2. The preparation is suitable for the quantitative assay of branched-chain amino acids and their 2-oxoacid analogues. 3. The content of total branched-chain 2-oxoacids in freeze-clamped liver, kidney, heart or mammary gland of fed rats is less than 5 nmol/g fresh wt. Higher amounts are present in skeletal muscle and arterial blood (25 +/- 4 nmol per g fresh wt., and 33 +/- 6 nmol per ml respectively; means +/- S.D. of 3 and 11 animals respectively). The values are not significantly affected by starvation for 24 h. 4. Arteriovenous difference measurements show that considerable amounts of branched-chain 2-oxoacids are released by skeletal muscle into the circulation and similar amounts are removed by the liver (about 1 mmol/24 h in a 400 g rat).

Amino Acid Oxidoreductases↗
PubMed1980

Hospital variations in metastatic breast cancer.

Data from the tumor abstracts of 25,535 female breast cancer patients in California were analyzed to measure hospital differences in the rates of metastatic disease at diagnosis. For white patients the metastatic rates varied from 38 to 68 per cent as hospital affiliation varied, and for blacks they ranged from 48 to 76 per cent. Tests for normality showed that the distribution of rates for white patients in private facilities was not merely due to random variation. The metastatic rates for both racial groups tended to be inversely related to the proportion of whites among the patient populations and positively related to total patient load. Hospitals affiliated with medical schools had relatively high rates for white private patients. Several explanations of the data are suggested. They consider the possible effects of patient and physician health care practices and host vulnerability to the spread of breast cancer.

Black or African American↗
PubMed1980

Plateletpheresis with the IBM model 2997. I. Effects of ACD, NIH formula B on selected donor indices.

9 healthy subjects dosed with acid-citrate-dextrose, NIH formula B (ACD-B) while undergoing plateletpheresis with the continuous-flow IBM Model 2997 centrifuge, received on average 59.5 +/- (SD) 3.2 mg Na3 citrate.kg-1.h-1. This rate of infusion of Na3 citrate resulted in a maximum 12-fold rise in the concentration of citrate in serum (plasma) following the processing of 10 litres of whole blood, and subsequently reduced the level of total calcium in serum (plasma) by 9%. This dose of Na3 citrate produced no clinical symptoms suggestive of hypocalcaemia in these subjects, even though the use of acid-citrate-dextrose, NIH formula A (ACD-A) under identical conditions has been reported to reduce significantly the level of total calcium in serum, and concomitantly increase the number or reactions occurring in donors. From previous studies employing the intermittent-flow centrifugation system of plateletpheresis, a rate of infusion of Na3 citrate below 65 mg.kg-1.h-1 can insure maximum donor safety and this rate can be achieved with the IBM Model 2997 by the utilisation of ACD-B.

Acids↗
PubMed1980

Skin perfusion pressure on the legs measured as the external pressure required for skin reddening after blanching: a photo-electric technique compared to isotope washout.

The skin perfusion on the calf was measured photo-electrically and by isotope washout technique using external counter pressure by a blood pressure cuff. By the photocell the skin blanching threshold external pressure (BTEP) was recorded on histamine flared red skin. By isotope washout technique the skin blood flow cessation external pressure (FCEP) was recorded using intra-dermal [131I-]-antipyrine mixed with histamine in estimating the skin blood flow. The external pressure was measured with an airfilled plastic cushion connected to a mercury manometer. Over a wide range of pressures as obtained from twenty patients with occlusive arterial disease of the legs, five normal subjects and eleven patients treated for arterial hypertension the values of the two different methods were highly significantly correlated (r = 0.97, P < 0.001). On average the BTEP was equal to the FCEP: 83.9 mmHg (range 18-187) compared to 80.8 mmHg (range 18-158) (P > 0.1). A normal material was obtained from twenty-four subjects measured on the thigh, calf and ankle; the average gradients between the auscultatory brachial mean blood pressure and the BTEP were: thigh 10.7 mmHg (SD 12.7); calf 4.0 mmHg (SD 12.1); ankle 5.1 mmHg (SD 8.7). As compared to the intra-arterial blood pressure the BTEP was found to lie close to the mean blood pressure in normal subjects as well as in hypertensive subjects. The present data indicate that the skin perfusion pressure on the legs can be measured by the rapid photo-electric technique. The clinical application and sources of error are discussed.

Adult↗
PubMed1979

A role for bicarbonate in the regulation of mammalian glutamine metabolism.

1. The concentration of HCO3- (independent of any change of pH) exerts different effects on glutamine metabolism in rat kidney-cortex tubules, hepatocytes and enterocytes.2. In kidney tubules HCO3- (10.5-50 MM) has no effect on glutaminase (EC 3.5.1.2), whereas glutamate dehydrogenase (EC 1.4.1.3) is inhibited as HCO3- concentration is increased. The result is that flux through the entire glutamate-to-glucose pathway is inhibited by increasing HCO3- concentrations. A large proportion (more than 30%) of the glutamine removed undergoes complete oxidation. 3. In hepatocytes, and to a smaller extent in enterocytes, HCO3- is an accelerator of glutaminase. Synthesis of glucose and urea from glutamine in hepatocytes increases as HCO3- concentration is increased. Calculations show that fumarate, formed via aspartate aminotransferase and arginino-succinate lyase, is the precursor of the glucose. There is no complete oxidation of the carbon skeleton of glutamine in hepatocytes. 4. Leucine at near-physiological concentrations (0.1-1 mM) is an accelerator of glutaminase in hepatocytes, but not in kidney tubules or in enterocytes. 5. The results are discussed in relation to regulation of acid/base balance in vivo.

Animals↗
PubMed1979

Isolation and metabolic characteristics of rat and chicken enterocytes.

1. The recent recognition of the metabolic, as opposed to absorptive, functions of the small intestine prompted efforts the improve the preparation of metabolically competent columnar absorptive cells ('enterocytes') and to study their metabolic properties. 2. With this preparation, linear rates of O2 consumption are obtained for 40 min at 37 degrees C that are more than 50% higher than rates reported by other authors. 3. Among added substrates, glucose, glutamine and glutamate are the preferred fuels of respiration. The main nitrogenous products of glutamine metabolism are NH3, alanine and glutamate. Glutamine carbon was not detectable in citrulline or proline, in contrast with the findings of Windmueller & Spaeth [(1974) J. Biol. Chem. 249, 5070-5079] in the vascularly perfused small intestine. 4. The rates of O2 uptake in the presence of glutamine or glutamate are sufficient to account for the formation of the carbon skeleton of alanine from the amino acid substrate, i.e. the ratio of O2 used/alanine formed is greater than 1.5. 5. Added ADP and ATP are rapidly degraded to AMP and IMP to a large extent by release of hydrolytic enzymes from the enterocytes into the medium. 6. Chicken enterocytes isolated by the same method are more stable; linear rates of O2 uptake are maintained for 60-70 min.

Adenine Nucleotides↗
PubMed1979

Dose dependent uptake of 125I-toluidine blue of 75Se-selenomethionine in the parathyroids of rabbits.

Different dosages of 125I-toluidine blue and 75Se-selenomethionine were injected intravenously into rabbits, and the concentration of radioactivity was measured in the parathyroids and surrounding tissues. The response of i.v. injected glucagon was also determined. It was found that 0.16 mg 125I-toluidine blue gave a concentration ratio of parathyroid/thyroid and parathyroid/muscle which was significantly higher than both lower and higher doses at 1 minute after i.v. injection of the labelled dye. Glucagon had little or no effect on the uptake of 125I-toluidine blue and 75Se-selenomethionine.

Animals↗