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Biomedical subjects

Y F Lin

Publications and source records attributed to Y F Lin.

101 records · Page 6Linked to original sources
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Influence of rapid correction of metabolic acidosis on serum osteocalcin level in chronic renal failure.

Metabolic acidosis induces a combination of inhibited osteoblastic and stimulated osteoclastic activity. To determine the role of alkali therapy in osteoblast function in chronic renal failure, serum bone isoenzyme of alkaline phosphatase (BAP) and osteocalcin were assessed before and after bicarbonate infusion. Eighteen patients with mild to moderate metabolic acidosis, none of whom had received dialysis therapy, were enrolled in this study. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was monitored at 5 min intervals and held at the preinfusion level by calcium solution infusion during the entire procedure. The end-point of the study was reached when the plasma bicarbonate was approximately 24 mmol/l or pH was approximately 7.4 and plasma ionized calcium was clamped at the preinfusion level with only a 0.01 mmol/l fluctuation. The plasma pH (7.31 +/- 0.04 vs. 7.40 +/- 0.03, P < 0.001), bicarbonate (18.46 +/- 2.49 vs. 23.66 +/- 2.72 mmol/l, P < 0.001), serum total calcium, and osteocalcin (15.61 +/- 6.45 vs. 18.79 +/- 6.71 mg/l, P < 0.05) levels were significantly increased, whereas serum concentrations of alkaline phosphatase and albumin levels were significantly decreased after bicarbonate infusion. The serum BAP (1.85 +/- 1.29 vs. 1.79 +/- 1.18 mukat/l, P = 0.252), and inorganic phosphorus levels showed no significant differences before and after bicarbonate infusion. These results demonstrate that rapid correction of metabolic acidosis improves osteoblast function and may underline the importance of maintaining normal acid-base homeostasis in chronic renal failure.

Acid-Base Equilibrium↗
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Increased nitric oxide production in hypotensive hemodialysis patients.

A subset of patients on long-term hemodialysis have sustained hypotension, defined as a predialysis systolic pressure of < 100 mmHg. To determine the role of nitric oxide (NO), an important vasodilator, in this condition, the authors measured the plasma levels of nitrite (NO2-) and nitrate (NO3-), the known NO metabolites taken as an index of NO production, in 10 hypotensive patients on long-term hemodialysis. None of them had diabetes, cirrhosis of the liver, congestive heart failure, or infection. Fifteen age and gender-matched normotensive patients on hemodialysis were selected as control subjects. Measurements of plasma levels of nitrite and nitrate based on the Greiss reaction were made. There was no significant difference in hematocrit, serum intact parathyroid hormone, total calcium, inorganic phosphorus, albumin, heart rate, cardiac index, or interdialysis weight gain between these two groups. Plasma nitrite and nitrate levels did not correlate with either predialysis serum creatinine or blood urea nitrogen. The mean arterial pressure (MAP) was significantly lower and plasma nitrite and nitrate levels were significantly higher in chronic hypotensive patients than in normotensive patients (MAP: 68.30 +/- 3.24 mmHg vs 95.20 +/- 2.44 mmHg, p < 0.001; plasma nitrite and nitrate: 72.49 +/- 14.41 mumol/L vs 36.42 +/- 5.45 mumol/L, p < 0.05). In addition, MAP from hypotensive and normotensive patients on hemodialysis was inversely correlated with plasma levels of nitrite and nitrate (r = -0.54, p < 0.01). It was concluded that enhanced NO production in this subset of patients on hemodialysis may contribute to their chronic hypotension.

Adult↗
PubMedDate not supplied

Prediction of dry weight through changes in blood volume and plasma cyclic 3',5'-guanosine monophosphate in patients under maintenance hemodialysis.

Dry weight evaluation is generally made from clinical observation of body weight (BW) changes, edema, blood pressure, and chest radiograph. In fact, 25-50% of patients on chronic hemodialysis had an incorrectly determined dry weight. To predict dry weight, twenty stable patients on regular hemodialysis were enrolled to investigate the correlation among dry weight, hematocrit, blood volume (BV), and vasoactive hormones including plasma renin activity (PRA), aldosterone (PA), and cyclic 3',5'-guanosine monophosphate (cGMP) values. BV was estimated by an infrared light reflection method. PRA, PA, and plasma cGMP were determined by commercial radioimmunoassay kits. The results showed significantly decreasing plasma cGMP values toward the end of hemodialysis compared with before hemodialysis (15.76 +/- 3.56 pmol/ml vs 33.57 +/- 3.98 pmol/ml; p < 0.05). A significant correlation exists between changes in plasma cGMP values and BV (p < 0.05). In addition, no significant correlation exists between changes in plasma cGMP and BW. A good correlation was found between changes in BV and hematocrit throughout dialysis (r = -0.774; p < 0.001). PRA and PA values predict neither BV nor BW changes. All patients were treated to attain a further ultrafiltration of 0.5 to 1.0 L after reaching dry weight, and we found that the critical point in blood pressure drop occurred when BV decreased by 8% or when plasma cGMP values decreased by 50% from their initial values. Continuous BV monitoring with infrared light reflection and detecting of cGMP throughout hemodialysis could help predict dry weight and avoid dialysis hypotension.

Blood Volume↗
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Characterization of denitrification and nitrification in a step-feed alternating anoxic-oxic sequencing batch reactor.

This study was conducted to characterize the denitrification and nitrification in a bench-scale sequencing batch reactor operating with a three-stage, alternating anoxic-oxic sequence and step feed (SAOSBR) for treating synthetic wastewater. The results of long-term operation and dynamic studies showed that the SAOSBR increased the availability of organic matter in wastewater for exogenous denitrification in anoxic periods, and subsequently allowed nitrification to occur under a lower organic loading in oxic periods. Comparatively high kinetic rates of 1.2 to 6.6 mg nitrate/g mixed liquor suspended solids (MLSS) x h for denitrification and 1.0 to 2.8 mg nitrogen/g MLSS x h for nitrification were found in dynamic studies. With sufficient influent organics and alkalinity, complete denitrification and full nitrification could be achieved sequentially in the alternating anoxic and oxic periods, resulting in an average total nitrogen removal efficiency up to approximately 90%. Alkalinity recovery because of exogenous denitrification was experienced, and a minimum influent alkalinity to total Kjeldahl nitrogen (TKN) ratio of 2.4 was required to reach complete TKN removal. The pH value would be a better parameter other than oxidation-reduction potential or dissolved oxgyen to determine the completeness of nitrification and denitrification in the SAOSBR.

Aerobiosis↗
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Effect of erythropoietin on neutrophil chemiluminescence in hemodialyzed patients.

Erythropoietin (EPO) has been used widely for correcting anemia in hemodialyzed (HD) patients. Enhancement of phagocytic function during EPO treatment of HD patients has been studied, but no data have been available on the effect of EPO on neutrophil chemiluminescence (CL) after challenge with phorbol myristate acetate (PMA). CL was measured in prehemodialysis whole blood samples from 15 stabilized patients and 15 normal healthy control subjects (C) after challenge with PMA. Before EPO treatment, CL was noted to be significantly higher in HD patients than in C, which changed significantly after 5 weeks of treatment (Rx) and continued for 13 weeks of Rx. There was a significant increase in hematocrit in these HD patients after 5 weeks that persisted until the 13th week. It was concluded that there is a significant decrease in whole blood CL in response to challenge with PMA during correction of anemia in HD patients treated with EPO. This study demonstrated that EPO could decrease enhanced PMA-activated reactive oxygen metabolite production and suggested that this decrease may protect against tissue damage, including red blood cell hemolysis in the uremic milieu.

Adult↗
PubMedDate not supplied

Outcome and cost of intensive care for very low birth weight infants.

Very low birth weights (VLBW) remain the major factor contributing to neonatal mortality and morbidity. The development of Neonatal Intensive Care Units (NICU) has improved the outcome for the VLBW infants. However, outborn VLBW infants may have different outcomes, and different medical costs than those born intramurally. This study compared the mortality, morbidity and costs of inborn and outborn VLBW infants cared in the NICU of a tertiary care center. A total of 176 VLBW infants (inborn 83, outborn 93) were examined over the three years period June 1990 to May 1993. The birth weights (1131 +/- 244 g vs 1133 +/- 255 g) and gestational ages (29.0 +/- 4.0 wk vs 28.9 +/- 3.0 wk) were not different between the two groups. However, the age of admission to our wards was significantly different between the inborn infants (5.0 +/- 3.2 hr.) and outborn infants (53.6 +/- 26.8 hr.). There was no difference in mortality rates between the outborn infants (35.7%) and the inborn infants (32.9%), nor in the incidence of intraventricular hemorrhage, respiratory distress syndrome, sepsis, necrotizing enterocolitis, retinopathy of prematurity or abnormal auditory brainstem response. However the incidence of patent ductus arteriosus and chronic lung disease of the outborn infants was higher than those of the inborn (47% vs 32%, 51% vs 29% respectively). The mean duration of hospitalization and cost seemed to be longer and higher in the outborn VLBW infants. It was concluded that outborn VLBW infants have higher rates of morbidity, longer hospitalization and cost more than inborn infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Health Care Costs↗
PubMedDate not supplied

Hormonal studies and Doppler flow imaging of ovarian lipoid cell tumors: report of two cases.

Ovarian lipoid cell tumors are very rare. We report two cases with abnormal menstruation, hirsutism, clitoromegaly and marked elevations of serum testosterone. Sonography revealed unilateral adnexal solid tumors. Flow velocity wave form study showed apparent flow within the tumor with the resistance index ranging from 0.42 to 0.49 in both cases. Unilateral oophorectomy and contralateral ovarian biopsy were performed. Frozen sections showed lipoid cell tumors without malignant change. During surgery, direct ovarian venipuncture showed a discrepancy in testosterone level in the bilateral ovaries of both patients and large ovarian-peripheral venous gradients in case 2. The testosterone concentration returned to normal postoperatively in both cases. Flow velocity wave form study and direct ovarian venipuncture are useful tools for evaluation of androgen-secreting tumors preoperatively and intraoperatively.

Adult↗
PubMedDate not supplied

Role of plasma catecholamines, autonomic, and left ventricular function in normotensive and hypotension prone dialysis patients.

The current study looked at plasma catecholamines, clinical autonomic function tests, and hemodynamic parameters in 10 ESRD patients (five men and five woman, aged 56.4 +/- 3.6) with dialysis hypotension and 10 patients (five men and five women, aged 58.6 +/- 4.2) without dialysis hypotension. Catecholamines were measured using high performance liquid chromatography--electrochemical detection (HPLC-ECD). Dialysis led to a significant decrease in mean arterial pressure (MAP) in the hypotensive group as compared with the normotensive group. Significantly higher basal (predialysis) plasma norepinephrine (NE) and dopamine levels (DA) were found in the hypotensive uremic group as compared with the normotensive group. Levels of plasma epinephrine (EP) were not significantly different between the normotensive and hypotensive groups. In response to postural stimulation, blood pressure fell in both groups, but the fall in the hypotensive group was significantly greater. Percentage increments of plasma catecholamines in response to postural stimulation in both groups were similar, however. Among the measured hemodynamic parameters, including total peripheral vascular resistance and left ventricular function (cardiac index and fractional shortening), only the cardiac index showed significantly lower values in the hypotensive group after dialysis, as compared with the normotensive group. Results of four tests of autonomic function indicated that although both groups responded similarly to hand-grip and cold-pressor tests, impaired responses to orthostasis and Valsalva maneuver after dialysis were observed in the hypotensive group. The MAP changes in dialysis in the hypotension prone group correlated inversely with predialysis plasma NE, but not with EP and DA.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System↗