Biomedical subjects

C K Kim

Publications and source records attributed to C K Kim.

At least 181 records · Page 10Linked to original sources

PubMed1996

Mosaic single plasma sample method for measuring glomerular filtration rate.

Seven single plasma sample methods for measuring glomerular filtration rate (GFR) were evaluated. When compared with GFRs calculated from a slope/intercept method proposed by Russell et al. [6] (using 1 h and 3 h plasma samples) as a reference standard, each single-sample method produced better results in different ranges of GFR (3 h plasma sample was used for all seven single-sample methods). Combining the best single-sample method in each range (mosaic) resulted in a regression line of y = 0.98x + 1.0, with a correlation coefficient of 0.980 and a standard error of estimate of 6.5 ml min-1 in 294 samples. This mosaic method yielded more accurate and realistic GFR values than any other individual single-sample method.

Adolescent↗

PubMed1996

Pharmacokinetics of four metabolites of DA-125, a new anthracycline antineoplastic agent after single and multiple intravenous administration to rats.

The tissue distribution, and biliary and urinary excretion of four metabolites (M1-M4) of a new anthracycline antineoplastic agent (DA-125) were compared after single and multiple (7 consecutive days) intravenous (i.v.) administration to rats. The mean pharmacokinetic parameters of M1, such as area under the plasma concentration-time curve (AUC: 56.4 micrograms/ml vs. 69.0 micrograms min/ml), terminal half-life (t1/2: 3.51 h vs. 3.01 h), total body clearance (Cl: 70.9 ml/min/kg vs. 58.0 ml/min/kg), renal clearance (ClR: 0.193 ml/min/kg vs. 0.336 ml/min/kg) and nonrenal clearance (ClNR: 70.7 ml/min/kg vs. 57.7 ml/min/kg); of M2, such as plasma AUC (39.4 micrograms min/ml vs. 41.9 micrograms min/ ml), t1/2 (6.15 h vs. 7.34 h) and ClR (10.5 ml/min/ kg vs. 13.8 ml/min/kg); and of M4, such as plasma AUC (4.82 micrograms min/ml vs. 6.54 micrograms min/ml) and t1/2 (3.33 h vs 4.02 h), were comparable between single and multiple administrations of DA-125. M3 was detected in plasma for up to 1-5 min, and M3 and M4 were below the detection limit in 24-h urine after both single and multiple administrations of DA-125. M2 was the main metabolite of DA-125 excreted (among M1-M4) in 24-h urine after both single and multiple administrations of DA-125; approximately 12.3% and 20.1% (P < 0.01) of i.v. dosage (expressed in terms of DA-125) was excreted as M2 after single and multiple administrations of DA-125, respectively. Corresponding values for M1 were 0.326% and 0.694% (P < 0.05). The mean levels of M1 (229 micrograms vs. 175 micrograms) and M2 (1330 micrograms vs. 1120 micrograms) excreted in 24-h bile after single and multiple administrations of DA-125 were not significantly different; the percentages of i.v. dosage excreted in 24-h bile as M1 (expressed in terms of DA-125) were 4.83% and 3.58% after single and multiple administrations, respectively. The corresponding values for M2 were 27.8% and 22.5%. M3 and M4 were below the detection limit in 24-h bile after both single and multiple administrations of DA-125. Mean AUAts (area under the amount-time curves from time zero to last measurement time t) (or AUCts-area under the plasma concentration-time curves from time zero until the last measurement time t) of M1-M4 in each tissue after single and multiple administrations of DA-125 were also comparable except in the bone marrow and thymus. The data suggest that 7 consecutive days of i.v. administration of DA-125 (4 mg/kg) to rats does not lead to considerable accumulation of M1-M4 in the tissues, except in the bone marrow and thymus.

Animals↗

PubMed1996

Effects of polyglactin mesh combined with resorbable calcium carbonate or replamineform hydroxyapatite on periodontal repair in dogs.

This study evaluates periodontal repair and biomaterial reaction following implantation of a polyglactin mesh with or without porous resorbable calcium carbonate (RCC) or porous replamineform hydroxyapatite (RHA) in conjunction with reconstructive surgery. Ligature- and surgically-induced interproximal periodontal defects of left and right mandibular premolar teeth in 7 dogs were used. Bilaterally, mesial defects of the 2nd, 3rd and 4th premolar teeth were treated with polyglactin mesh, polyglactin mesh and RHA, or polyglactin mesh and RCC, respectively. The polyglactin mesh, shaped according to the contour of the defect, was adapted to the experimental teeth; its coronal margin positioned immediately apical to the cemento-enamel junction. Gingival flap margins were adapted and sutured to cover the polyglactin mesh completely. Clinical healing was generally uneventful. The dogs were sacrificed to provide block sections for histologic evaluation at 1, 3, 6, 12, 26, 32 and 56 weeks following wound closure. Generally, cementum regeneration was observed beginning at week 6 in all groups. Bone regeneration was observed from week 3 in polyglactin mesh-treated groups, and from week 6 in polyglactin mesh+RCC or polyglactin mesh+RHA treated groups. Bone regeneration appeared enhanced in polyglactin mesh+RCC or polyglactin mesh+RHA treated defects at week 12 and 26, with little difference between the three experimental conditions at week 56. Polyglactin mesh degradation was observed at week 3 and appeared complete at week 12. The RHA did not appear to resorb, while the RCC was gradually replaced by bone from week 3. Within limitations of the study conditions, periodontal regeneration was observed following implantation of a polyglactin mesh with or without RCC or RHA in conjunction with reconstructive surgery. As a conclusion, there seems to be no significant difference in periodontal regeneration after 12 months of healing between the group treated with the membrane only, and the group treated with the membrane and the bone substitution material. Changes in connective fiber orientation over the 1st 12 weeks of healing may suggest that "fibrous encapsulation" observed in earlier studies may only represent a transient stage in periodontal regeneration.

Animals↗

PubMed1996

Genetic structures of the genes encoding 2,3-dihydroxybiphenyl 1,2-dioxygenase and 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid hydrolase from biphenyl- and 4-chlorobiphenyl-degrading Pseudomonas sp. strain DJ-12.

The pcbC and pcbD genes of Pseudomonas sp. strain DJ-12, a natural isolate degrading biphenyl and 4-chlorobiphenyl, encode the 2,3-dihydroxybiphenyl 1,2-dioxygenase and 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid hydrolase, respectively. The two genes were sequenced and appear to be present in the order pcbD-pcbC as an operon.

Base Sequence↗

PubMed1996

Periodontal repair in intrabony defects treated with a calcium carbonate implant and guided tissue regeneration.

Clinical outcome following the concurrent use of a porous resorbable calcium carbonate (CC) implant and guided tissue regeneration (GTR) in intrabony periodontal defects was evaluated in a randomized four-treatment parallel arm study. Eighty (80) patients, each contributing one interproximal intrabony defect, were assigned to the four treatments (20 patients per treatment) including the CC implant and GTR (CC + GTR), GTR alone (GTR control), CC implant alone (CC control), and gingival flap surgery alone (GFS control). Fourteen patients treated with CC + GTR, 19 patients treated with the GTR control, 13 patients treated with the CC control, and 18 patients treated with the GFS control completed the study. Clinical healing was evaluated 6 months postsurgery and included changes in probing depth, clinical attachment level, probing bone level, and gingival recession. Postsurgery probing depth reduction was 4.5 +/- 1.7 mm (CC + GTR; P < 0.01), 4.8 +/- 1.8 mm (GTR; P < 0.01), 3.7 +/- 2.2 mm (CC; P < 0.01), and 3.3 +/- 1.6 mm (GFS; P < 0.01). Clinical attachment gain amounted to 3.3 +/- 1.4 mm (CC + GTR; P < 0.01), 4.0 +/- 2.1 mm (GTR; P < 0.01), 3.0 +/- 2.4 mm (CC; P < 0.01), and 2.0 +/- 1.7 mm (GFS; P < 0.01). The CC + GTR and GTR treatments exhibited significantly greater improvements compared to GFS (P < 0.05). Postsurgery probing bone level gain amounted to 4.0 +/- 1.7 mm (CC + GTR; P < 0.01), 4.1 +/- 1.5 mm (GTR; P < 0.01), 4.0 +/- 2.2 mm (CC; P < 0.01), and 0.5 +/- 2.0 mm (GFS; P > 0.05). The CC + GTR, GTR, and CC treatments exhibited significantly greater improvements compared to GFS (P < 0.05). Gingival recession increased significantly compared to presurgery for GTR, CC, and GFS treatments (-0.9 +/- 1.2, -0.7 +/- 0.7, and -1.2 +/- 1.4 mm, respectively; P < 0.01). The results suggest that the concurrent use of a porous resorbable CC implant and GTR has limited adjunctive effect in the treatment of intrabony periodontal defects.

Adult↗

PubMed1996

Thallium-201 and iodine-131 scintigraphy in differentiated thyroid carcinoma.

UNLABELLED: The purpose of this study was to determine the concordance and discordance between diagnostic 131I and 201TI whole-body scintigraphy in patients with differentiated carcinoma of the thyroid. METHODS: Following thyroidectomy for differentiated thyroid carcinoma, 50 patients underwent whole-body 131I and 201TI scanning (60 pairs of scans in total). Fifteen pairs of studies were obtained before ablative therapy, 30 pairs after ablative therapy and 15 pairs after 131I therapy for metastatic disease. Serum thyroglobulin levels were concurrently determined by radioimmunoassay. RESULTS: Thirty-six 131I whole-body scans (in 34 patients) showed residual uptake in the neck, but only six (17%) of the corresponding whole-body thallium studies had detectable uptake in the neck. Fourteen 131I scans (in nine patients) identified multiple metastatic lesions, whereas the thallium scans were interpreted as either negative, nonspecific or showing fewer lesions. In four study pairs, the thallium scans showed solitary lesions that were not detected by the corresponding radioiodine scans. In 16 scans, the thallium studies gave false-positive results. CONCLUSION: Iodine-131 scintigraphy for differentiated thyroid carcinoma is more sensitive and more specific than 201TI scintigraphy for detection of distant metastases and residual activity in the neck following thyroidectomy.

Adenocarcinoma, Follicular↗

PubMed1995

Cholesterol biosynthesis from lanosterol: regulation and purification of rat hepatic sterol 14-reductase.

We have previously characterized the membrane-bound sterol 14-reductase (14-reductase) that catalyzes anaerobically NADPH-dependent reduction of the 14-double bond of delta 8,14-diene or delta 7,14-diene sterols that are sterol intermediates in cholesterol biosynthesis in mammals (Paik et al. (1984) J. Biol. Chem. 259, 13413-13423). To elucidate the regulatory mechanism as well as molecular characteristics of the 14-reductase, we extended our investigation on the consequences of alteration of the enzymic activity under various physiological conditions. The enzymic activity of rat hepatic sterol 14-reductase was induced more than 11-fold by feeding 5% cholestyramine plus 0.1% lovastatin (the CL-diet) for 7 days but was severely suppressed by feeding 5% cholesterol or 0.01% AY-9944 (an inhibitor of 14-reductase) for the same period. The increase or decrease in the 14-reductase activity also parallels the same change in the cholesterol synthetic rate in hepatocytes from rats that had been fed either the CL-diet or 0.01% AY-9944. In vitro inhibition studies revealed that AY-9944 acts as a competitive inhibitor of the 14-reductase (Ki = 0.26 microM). A diurnal variation was observed for the 14-reductase with peak activity near the middle of the dark cycle (10 p.m.), which was abolished by administration of cycloheximide. With induced enzyme conditions 14-reductase has been further purified with chromatographic procedures to near homogeneity. Purified 14-reductase appears to be a M(r) = 70,000 protein that is composed of two equally-sized subunits having a M(r) = 38,000. All properties of the purified 14-reductase suggest that the solubilized enzyme is the principal 14-reductase of microsomes. Taken together, our results provide the first evidence in support of a previously unknown regulatory role for the 14-reductase in the overall cholesterol synthetic pathway.

Animals↗

PubMed1995

Cloning of salicylate hydroxylase gene and catechol 2,3-dioxygenase gene and sequencing of an intergenic sequence between the two genes of Pseudomonas putida KF715.

The salicylate hydroxylase can convert the salicylate to catechol, and catechol 2,3-dioxygenase catalizes the conversion of catechol to 2-hydroxymuconic semialdehyde. A salicylate hydroxylase gene and a catechol 2,3-dioxygenase have been cloned from chromosomal DNA of P. putida KF715. The two genes have different promoters. An open reading frame with 339 nucleotides preceded by a putative ribosome-binding sequence (GGAGG) was identified in the intergenic sequence between salicylate hydroxylase gene and catechol 2,3-dioxygenase gene of P. putida KF715 and its sequence analyzed. This open reading frame can encode a polypeptide of molecular weight 13 kDa containing 112 amino acids, whose sequence exhibited 87% homology with that of ferredoxin encoded in NAH7 of P. putida PpG7 and significant homology with those of redox components in phenol hydroxylase, benzoate 1,2-dioxygenase, toluate 1,2-dioxygenase, xylene monooxygenase, and toluene 4-monooxygenase.

Amino Acid Sequence↗

PubMed1995

Pharmacokinetics of methotrexate after intravenous and intramuscular injection of methotrexate-bearing positively charged liposomes to rats.

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated after intravenous (IV) and intramuscular (IM) injection of free MTX (treatment I), freshly prepared MTX-bearing positively charged liposomes (large unilamellar vesicles), PLUVs (treatment II), and empty PLUVs mixed manually with free MTX (treatment III), 4 mg kg-1 as free MTX to rats, using HPLC assay. After 1 min IV infusion, the plasma concentrations of MTX (Cp), the area under the plasma concentration-time curve (AUC, 173 against 314 micrograms mL min-1), the terminal half-life (t1/2, 24.0 against 412 min), the mean residence time (MRT, 13.0 against 324 min), and the apparent volume of distribution at steady state (VSS, 289 against 3370 mL kg-1) were significantly larger, but the total body clearance (CL, 23.1 against 12.8 mL min-1 kg-1), the renal clearance (CLR, 8.38 against 3.09 mL min-1 kg-1), the non-renal clearance (CLNR, 14.6 against 9.56 mL min-1 kg-1), and the amount of MTX excreted in urine (Xu, 415 against 275 micrograms) were significantly lower in treatment II than in treatment I. This could be due to the fact that some of the MTX-bearing PLUVs were entrapped in tissues and the rest were present in plasma (larger MRT and Vss in treatment II), and MTX is slowly released from MTX-bearing PLUVs (longer t1/2 in treatment II). In the present HPLC assay, the concentrations of MTX represent the sum of free MTX and MTX in MTX-bearing PLUVs (larger Cp and AUC and slower CL in treatment II). Saturable formation of 7-hydroxymethotrexate from MTX was reported in rabbit blood and nonlinear disposition of MTX was also reported in rats and rabbits (lower Xu and CLR in treatment II). After 1 min IV infusion, some pharmacokinetic parameters of MTX, such as AUC, CL, CLR, CLNR, and Xu, were significantly different between treatments I and III, but nonetheless the differences were smaller than those between treatments I and II. After both IV and IM administration, the amount of MTX remaining per gram of tissue or organ in the kidney, stomach, small intestine, and large intestine was significantly smaller in treatment II than in treatment I.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Pharmacokinetics and antitumour activity of a new anthracycline, DA-125, after intravenous administration to subcutaneously implanted Lewis-lung-carcinoma-bearing mice.

The pharmacokinetics and tissue distribution of M1-M4 were compared after intravenous (i.v.) administration of DA-125, 25 mg kg-1, to BDF1 mice (n = 5 at each sampling time) and subcutaneously implanted Lewis-lung-carcinoma-bearing BDF1 mice (n = 10 at each sampling time. The mean plasma concentrations of M1-M4 were not significantly different between the two groups of mice, and hence similar pharmacokinetic parameters for M1-M4 were obtained. The amount of M1 in the lung was significantly greater in the tumour-bearing mice than in the control mice, resulting in a greater AUAt in the tumour-bearing mice (18,600 against 8940 micrograms min g-1), and vice versa in the liver (962 against 3840 micrograms min g-1). However, the corresponding values for other tissues were comparable between the control and tumour-bearing mice. The amount of M1 was greatest in the lung for up to 2 h in the tumour-bearing mice. M2 was the predominant metabolite among M1-M4 excreted in 24 h urine by both groups of mice; 8.36 and 10.7% of the i.v. dose were excreted in 24 h urine as M2--expressed in terms of DA-125--by the control and tumour-bearing mice, respectively. The amount of M1 in the tumour mass reached a mean Cmax of 3.75 micrograms g-1 immediately after i.v. administration of DA-125 to the tumour-bearing mice, then declined very slowly to an amount that remained almost constant for up to 24 h. This suggested that M1 has high affinity for the subcutaneously implanted Lewis lung carcinoma. The antitumour activity, such as the increase in life span (ILS) and tumour growth inhibition (TGI) of DA-125, 6-48 mg kg-1, and adriamycin (ADM), 3-18 mg kg-1, were also compared in subcutaneously implanted Lewis-lung-carcinoma-bearing BDF1 mice after four weekly i.v. administration of the drugs on days 1,8,15, and 22 following tumour implantation. More than three out of six mice survived as tumour-free for longer than 70 d at a DA-125 dose range of 6-24 mg kg-1, but there were no tumour-free mice at any dose of ADM. Assuming ILS values higher than 30% to be effective, DA-125 doses ranging from 6 to 24 mg kg-1 were effective in increasing the life span, which ADM does only within the dose range of 6-12 mg kg-1.

Animals↗

PubMed1995

Contingent drug tolerance: differential tolerance to the anticonvulsant, hypothermic, and ataxic effects of ethanol.

The kindled-convulsion model of epilepsy was used to study contingent tolerance to ethanol's (1.5 g/kg; IP) anticonvulsant, hypothermic, and ataxic effects in adult male rats. In the present experiments, three groups of amygdala-kindled rats received a series of bidaily (one every 48 h) convulsive stimulations: one group received ethanol 1 h before each stimulation; one group received ethanol 1 h after each stimulation; and another group served as the saline control. Tolerance to ethanol's anticonvulsant effect (Experiments 1 and 2) was greatest in those rats that received ethanol before each convulsive stimulation; whereas, tolerance to ethanol's hypothermic (Experiments 1 and 2) and ataxic (Experiments 2) effects developed in both groups that received ethanol. These results were predicted on the basis of the drug-effect theory of drug tolerance: the theory that functional drug tolerance is an adaptation to the disruptive effects of drugs on concurrent patterns of neural activity, not to drug exposure per se.

Amygdala↗

PubMed1995

Tolerance to the anticonvulsant and ataxic effects of pentobarbital: effect of an ascending-dose regimen.

We assessed the effect of an ascending-dose regimen on the development of tolerance to the anticonvulsant and ataxic effects of pentobarbital in four groups of amygdala-kindled rats. Each rat received 20 bidaily (one every 48 h) trials in which an intraperitoneal (IP) pentobarbital or vehicle injection was delivered 1 h before a convulsive amygdala stimulation. On each trial, the rats in the three pentobarbital groups received either a high dose (50 mg/kg), a low dose (10mg/kg), or ascending doses of pentobarbital that began at 10 mg/kg and increased to as high as 26 mg/kg by 1 mg/kg increments as tolerance developed to its anticonvulsant effect; the rats in the vehicle group received saline. The rats in the ascending-dose condition displayed significantly more tolerance to the anticonvulsant effect of pentobarbital than did the other rats; in contrast, the high-dose rats displayed more tolerance to the ataxic effect of pentobarbital than did the other rats. These findings extend previous reports of the facilitatory effect of ascending-dose regimens on the development of tolerance to the anticonvulsant effect of benzodiazepines, and show that the facilitatory effect of ascending-dose regimens does not extend to all drug effects.

Animals↗

PubMed1995

Cholesterol biosynthesis from lanosterol: regulation and purification of rat hepatic sterol 8-isomerase.

The membrane bound sterol-8-isomerase (isomerase) catalyzes the anaerobic conversion of sterol-8-ene to the sterol-7-ene isomer in eucaryotes. To examine the regulatory mechanism as well as molecular characteristics of the isomerase we investigated the consequences of alteration of the enzymic activity under various diet conditions. Feeding 5% cholesterol or 0.1% AY-9944 for a minimum of 2 days caused more than a 70% decrease in microsomal isomerase activity. Feeding 5% cholestyramine plus 0.1% lovastatin (CL-diet) for 7 days led to approximately 4.0-fold induction of the isomerase activity. In addition, diurnal variation in the enzymic activity was observed with this diet. Induction of the isomerase activity by the CL-diet was quantitatively reflected in an increase in the cholesterol synthetic rate in isolated rat hepatocytes. The isomerase was highly purified from liver of rats fed the CL-diet, and its molecular mass was determined to be 21,000 Da by denaturing sodium dodecylsulfate gel electrophoresis.

Animals↗

PubMed1995

Morphine-augmented hepatobiliary scintigraphy: a meta-analysis.

The aim of this study was to compare the sensitivity and specificity of morphine-augmented hepatobiliary scintigraphy (MA-HBS) with that of conventional hepatobiliary scintigraphy (C-HBS) for acute cholecystitis. The results of most MA-HBS studies cannot be compared with C-HBS estimates, since articles describing C-HBS often include non-candidates for MA-HBS. However, using meta-analytic techniques to combine data from eligible studies (4 for C-HBS and 5 for MA-HBS), the specificity of MA-HBS (0.84; 95% CI = 0.75-0.94) was significantly greater (P = 0.008) than that of C-HBS (0.68; 95% CI = 0.61-0.75); there were no differences in sensitivity (MA-HBS; 0.96, 95% CI = 0.92-0.99; C-HBS: 0.97, 95% CI = 0.97-0.99).

Acute Disease↗

PubMed1995

Aerobic exercise capacity at sea level and at altitude in Kenyan boys, junior and senior runners compared with Scandinavian runners.

The aim of this study was to characterize Kenyan runners in regard to their oxygen uptake and blood and ammonia responses when running. Untrained Kenyan boys (14.2 +/- 0.2 years) and Scandinavian runners were included for comparison. The studies were performed at altitude (approximately 2.000 m.a.s.l.) and, for several Kenyan and Scandinavian runners, at sea level as well. At altitude sedentary adolescent Kenyan boys had a mean maximal oxygen uptake (VO2max) of 47 (44-51) ml.kg-1.min-1, whereas similarly aged boys regularly walking or running but not training for competition reached above 62 (58-71) ml.kg-1.min-1 in VO2max. Kenyan runners in active training had 68 +/- 1.4 ml.kg-1.min-1 at altitude and 79.9 +/- 1.4 ml.kg-1.min-1 at sea level, with individuals reaching 85 ml.kg-1.min-1. The best Scandinavian runners were not significantly different from the Kenyan runners in VO2max both at altitude and at sea level, but none of the Scandinavians reached as high individual values as observed for some Kenyan runners. The running efficiency, determined as the oxygen cost at a given running speed, was less in the Kenyan runners, and the difference became more pronounced when body weight was expressed in ml.kg-0.75 min-1. Blood lactate concentration was in general lower in the Kenyan than in the Scandinavian runners, and the Kenyans also had extremely low ammonia accumulation in the blood even at very high exercise intensities. It is concluded that it is the physical activity during childhood, combined with intense training as teenagers that brings about the high VO2max observed in some Kenyan runners. Their high aerobic capacity, as well as their good running economy, makes them such superior runners. In addition, their low blood lactate and ammonia accumulation in blood when running may also be contributing factors.

Adolescent↗

PubMed1995

Morphology, enzyme activities and buffer capacity in leg muscles of Kenyan and Scandinavian runners.

The study comprises data on 12 Scandinavian runners who had either trained for two weeks in Kenya (n = 6; approximately 2000 meters above sea level (m.a.s.l.)) or in Portugal (n = 6; sea level (s.l.)) and on 13 Kenyan runners (9 junior and 4 senior) living and training at approximately 2000 m.a.s.l. Muscle biopsies were taken before and after the training camps in the Scandinavian runners and once on the Kenyan runners from the vastus lateralis (v.l.) and the gastrocnemius muscles. Muscle fiber size and composition were similar in the various groups (4.6-5.1 X 10(3) microns2; ST approximately 60-70%; FTa 30-40%; FTb < 6.0%) with a tendency for some more (approximately 5%) FTa fibers in the gastrocnemius muscle. Mean number of capillaries in v.l. varies between 405-493 cap.(mm2)-1, 2.0-2.7 cap.fiber-1, and 4.4-6.2 cap around the various fiber types, with the Kenyan seniors having the highest and the Kenyan juniors the lowest values. All runners had 10-20% more capillaries in their gastrocnemius muscle. Similar levels for citrate synthase (CS) activity were found in the v.l. of the Kenyan seniors and Scandinavian runners, whereas the Kenyan juniors were 10-15% lower. The 3- hydroxyacyl-CoA-dehydrogenase (HAD) activity was 20% higher in the Kenyan than in the Scandinavian runners. In the gastrocnemius muscle, both enzyme activities were 20-50% higher in Scandinavian and Kenyan runners. The ratio for lactate dehydrogenase (LDH) isoform1-2 and isoform4-5 was increased when training at altitude due to a lowering of LDH4-5 and became close to what was observed in the Kenyan runners.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1995

Skeletal muscle perfusion in electrically induced dynamic exercise in humans.

Leg blood flow, blood pressure and metabolic responses were evaluated in six men during incremental one-legged dynamic knee extension exercise tests (no load exercise-40 W); one performed with voluntary contractions (VOL) and one with electrically induced contractions (EMS). Pulmonary oxygen uptake was the same in both exercise modes, but the ventilatory coefficient was 2-5 L per L O2 higher in EMS than VOL (P < 0.05). Heart rate and mean arterial pressure were slightly higher with EMS than VOL at all exercise intensities reaching 138 (EMS) and 126 bpm (VOL), as well as 148 (EMS) and 137 mmHg (VOL) at 40 W, respectively (P < 0.05). Leg blood flow, oxygen uptake and conductance were similar in the two exercise modes. At 40 W, mean muscle blood flow was close to 200 (range: 165-220) mL 100 g-1 min-1, mean peak muscle oxygen uptake reached 230 mL kg-1 min-1, and mean conductance became as high as around 45 mL min-1 mmHg-1, and normalized for muscle size and arterial pressure it approached 100 mL min-1 100 g-1 100 mmHg-1. Lactate and ammonia efflux from the leg were higher with EMS than with VOL and the difference became larger with increasing exercise intensity (P < 0.05). Muscle glucose uptake was the same in each exercise mode. Femoral venous K+ concentration increased with exercise intensity and was higher with EMS than with VOL, reaching 5.1 (EMS) and 4.7 mmol L-1 (VOL) at 40 W (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Training effects of electrically induced dynamic contractions in human quadriceps muscle.

The effects of electrically induced dynamic muscle contractions on muscle endurance, strength, morphology and enzymatic adaptation were studied in seven male physical education students. The training program consisted of electrically induced one-leg extensions on a modified Krogh cycle with a 30-Watt (W) load for 60 min, 3 times a week for 4 weeks. Muscle fiber type composition was unchanged, but diffusional capacity was increased after electromyostimulation training. The endurance capacity in the trained leg increased by 82% (p < 0.01), but there were no significant changes in citrate synthase, phosphofructokinase activities, and carbonic anhydrase III and myoglobin contents, suggesting that neural adaptation and learning were more important factors for the increased endurance capacity than enzymatic adaptation. Prolyl 4-hydroxylase activity, a marker of collagen biosynthesis, increased 3-fold (p < 0.01) as a result of the training. This could be due to muscle damage caused by electrically induced muscle contractions. In conclusion, electrically induced dynamic muscle contractions can increase muscle endurance without clear concominant changes in muscle morphologic and enzymatic adaptation. Increased prolyl 4-hydroxylase activity could suggest muscle damage caused by electrically induced muscle contractions.

Adult↗