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Biomedical subjects

D H Kang

Publications and source records attributed to D H Kang.

125 records · Page 7Linked to original sources
PubMed1983

Patterns of wet suit diving in Korean women breath-hold divers.

Work shifts, diving pattern, diving lung volumes, and counterweights were studied in professional Korean women breath-hold divers wearing wet suits. One of the major differences, compared with their diving pattern only a few years ago when wearing cotton suits, is the prolongation of the diving shifts from 70 to 180 min in the summer and 10 to 120 min in the winter. In sustained diving the average dive and surface times in a 5-m dive are 32 and 46 s, and in a 10-m dives, 43 and 85 s, respectively. During a 3-h shift the total bottom time for harvesting is 37 min in 5-m dives and 17 min in 10-m dives. Rates of descent and ascent are 0.55 and 0.84 m/s. The wet suit divers adjust their counterweights to obtain a 12% positive buoyancy at the surface of sea water in contrast to the 8% positive buoyancy of cotton suit divers. The average lung volumes before and after a dive are 79% and 64% of their vital capacities, values similar to those of previous cotton suit divers.

Adaptation, Physiological↗
PubMed1980

Relation between intracellular Na ion activity and tension of sheep cardiac Purkinje fibers exposed to dihydro-ouabain.

The intracellular Na ion activity (aiNa) and the contractile tension (T) of sheep cardiac Purkinje fibers were simultaneously measured employing recessed-tip Na+-selective glass microelectrodes and a mechano-electric transducer. The aiNa of 6.4 +/- 1.6 mM (mean +/- SD, n = 56) was obtained in fibers perfused with normal Tyrode's solution. The changes in aiNa and T were measured during and after the exposure of fibers to a cardiac glycoside, dihydro-ouabain (DHO) in concentrations between 5 X 10(-8) M and 10(-5) M. The exposure time to DHO was 15 min. Both aiNa and T did not change in fibers exposed to 5 X 10(-8) M DHO, and the threshold concentration for the effect of DHO appeared to be around 10(-7) M. In DHO concentrations greater than the threshold, the increases in aiNa and T strongly correlated during the onset of DHO effects. The recoveries of aiNa and T were variable and slow, being dependent on the DHO concentration. In those fibers which recovered from the effects of DHO, the time-course of aiNa recovery was similar to that of T recovery. In fibers exposed to DHO of 5 X 10(-6) M or greater, the apparent toxic effects were observed in both action potential and contraction after an initial increase in T. The fibers manifesting the apparent toxic effects has a aiNa of approximately 30 mM or greater. The results of this study indicate that the increase in aiNa is associated with the positive inotropic action of the cardiac glycoside.

Animals↗
PubMed1975

Effects of diagnostic ultrasound irradiated during foetal stage on emotional and cognitive behaviour in rats.

Our previous work demonstrated that the prenatally irradiated ultrasound of even a low-intensity might affect the functional development of the brain of offspring in rats. In the present study, in order to investigate the emotional and cognitive behaviour of offspring of rats that received the irradiation of a diagnostic ultrasound on the 9th day of gestation, the following three experiments were carried out: 1) The emotional reactivity of the offspring was measured by the open-field technique. 2) The same reactivity was further evaluated in terms of the excape response from electroshock. 3) The cognitive function of the offspring was assessed through the discrimination learning and the discrimination reversal learning. The offspring of irradiated rats showed significantly more distinct vocalization response to handling in the open-field test and significantly more distinct escape response from the electroshock, when compared with the two control rats (untreated control and sham-irradiated control). From these findings it may be suggested that the emotional behaviour in rats can be influenced by a low-intensity ultrasound irradiated during foetal stage. On the other hand, as for the cognitive behaviour, the results of the present study suggest no adverse effect on it.

Animals↗
PubMedDate not supplied

Immune responses to final exams in healthy and asthmatic adolescents.

Immune responses to an academic stressor were examined in healthy and asthmatic adolescents with regard to their illness symptom reports. Eighty-seven high school students completed a health diary for 2 weeks and provided three blood samples during midsemester, final-exam, and postexam periods. During exam week, all students showed significant immunological alterations from baseline. Natural killer cell activity was significantly lower, whereas lymphocyte proliferation and neutrophil superoxide release were significantly higher. These immune changes tended to return toward baseline during the postexam period, but the enhanced neutrophil reactivity continued to rise. Overall, immunological responses were similar between asthmatic subjects and controls. Appropriate medical management may have accounted for this similarity. However, subtle group differences in the postexam recovery pattern and a continuous activation of inflammatory cell function following a stressor may warrant further investigation.

Adolescent↗
PubMedDate not supplied

High glucose solution and spent dialysate stimulate the synthesis of transforming growth factor-beta1 of human peritoneal mesothelial cells: effect of cytokine costimulation.

OBJECTIVE: To investigate the effect of high glucose and spent peritoneal dialysate on the transforming growth factor-beta1 (TGFbeta1) synthesis of cultured human peritoneal mesothelial cells (HPMCs) and to examine the effect of costimulation with high glucose or spent dialysate, and cytokines, interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNFalpha) on TGFbeta1 synthesis of HPMCs. DESIGN: HPMCs were exposed to different concentrations of glucose (30, 60, and 90 mmol/L) or spent peritoneal dialysate for 48 hours in the absence or presence of IL-1beta (1 ng/mL) and TNFalpha(1 ng/mL).TGFbeta1 mRNA expression was assessed by Northern blot analysis and TGFbeta1 protein release by Western blot analysis and enzyme-linked immunosorbent assay (ELISA). RESULTS: Exposure of HPMCs to high glucose conditions (30, 60, and 90 mmol/L of D-glucose) induced 2.3-, 3.6-, and 4.0-fold increases inTGFbeta1 mRNA expression of HPMC with enhancedTGFbeta1 protein synthesis and secretion into the media, whereas there were no significant changes in TGFbeta1 synthesis with equimolar concentrations of D-mannitol. Incubation with spent dialysate also significantly increased TGFbeta1 mRNA expression and protein secretion compared to control media (p < 0.05). Stimulation with IL-1beta (1 ng/mL) or TNFalpha (1 ng/mL) resulted in a significant increase in TGFbeta1 mRNA expression after 48 hours: 2.7 and 2.1 times the control level, respectively. However,TNFalpha-induced increase in TGFbeta1 mRNA expression was not translated intoTGFbeta1 protein secretion, while IL-1beta stimulation induced a significant increase in TGFbeta1 protein secretion as well as TGFbeta1 mRNA expression. Combined stimulation by high glucose or spent dialysate, together with IL-1beta or TNFalpha, showed a greater increase in TGFbeta1 mRNA expression and protein secretion compared to stimulation by high glucose or spent dialysate alone. CONCLUSION: Our results clearly show that high glucose solution and spent dialysate themselves might be sufficient to stimulate the production of TGFbeta1 by peritoneal mesothelial cells. In peritoneal dialysis patients, this state of chronic induction of TGFbeta1 is further exacerbated in the presence of peritonitis because of the stimulatory effect of proinflammatory cytokines, resulting in augmented TGFbeta1 synthesis, thus promoting peritoneal fibrosis.

Blotting, Northern↗
PubMedDate not supplied

Impact of peritoneal membrane transport characteristics on acid-base status in CAPD patients.

OBJECTIVE: To evaluate the role of individual peritoneal membrane transport characteristics on buffer balance through the peritoneal membrane, and thus on the final acid-base status. DESIGN: Cross-sectional assessment of peritoneal membrane transport characteristics and acid-base status in continuous ambulatory peritoneal dialysis (CAPD) patients. SETTING: Peritoneal dialysis unit in tertiary university hospital. PATIENTS: The study included 143 clinically stable patients maintained on CAPD more than 6 months using 40 mmol/L of lactate-based dialysate. MAIN OUTCOME MEASURE: Comparison of acid-base status based on arterial blood gas analysis, dialytic lactate gain, bicarbonate loss, and total base gain according to membrane transport characteristics as defined by dialysate/plasma creatinine ratio (D/P(Cr)) of standard peritoneal equilibration test (PET). RESULTS: Mean arterial bicarbonate concentration was 24.5 +/- 3.5 mmol/L (16.2-35.7 mmol/L) and mean dialytic base gain was 29.3 +/- 16.7 mmol/day. Only 15 (10.5%) patients showed metabolic acidosis, while 44 (30.8%) patients had various degrees of metabolic alkalosis. Distribution of peritoneal membrane characteristics in our subject showed the highest prevalence of low average (n = 66, 46.2%), followed by high average (n = 54, 37.8%), low (n = 13, 9.1%), and high (n = 10, 6.9%) transporters. The 4-hour D/P(Cr) was positively correlated with dialytic albumin loss, lactate gain, dialytic base gain, arterial pH, and bicarbonate concentration. Lactate gain and dialytic base gain were significantly higher in high transporters, which resulted in increased pH (7.4 +/- 0.03 vs 7.38 +/- 0.03, p < 0.05) and bicarbonate level (26.7 +/- 3.2 vs 23.4 +/- 2.8 mmol/L, p < 0.05) compared to patients with a low transport rate. Multiple regression analysis revealed that lactate gain, duration of peritoneal dialysis, CRP and normalized protein equivalent of nitrogen appearance were the independent factors determining the arterial bicarbonate level. CONCLUSION: The peritoneal membrane transport characteristics can be one of the important factors determining the acid-base status of peritoneal dialysis patients. Duration of dialysis, protein catabolic rate, and acute phase responses of patients also influence arterial bicarbonate level independently. Prospective long-term follow-up studies evaluating the potential role of membrane transport characteristics on acid-base status will be needed to further ascertain the clinical implication of this relationship.

Acid-Base Equilibrium↗