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Biomedical subjects

W C Huang

Publications and source records attributed to W C Huang.

At least 73 records · Page 4Linked to original sources
PubMed1992

Antidiuresis and natriuresis induced by gastric distension in water-loaded rats.

Antidiuretic and natriuretic responses were observed following gastric distension in anesthetized, water-loaded rats. An increase of intragastric pressure to 25, 30, 35, and 40 cm H2O of 2-minute duration respectively elicited 11, 35, 45, and 55% inhibition of water diuresis with concomitant, graded increase of sodium excretion by the kidney. These antidiuretic and natriuretic responses to gastric distension persisted and sustained the same intensity after acute bilateral cervical vagotomy, indicating that the sensory input conveyed from the gastric mechanoreceptors to central nervous system during gastric distension should involve afferent fibers other than vagus nerve. Rats with diabetes insipidus (D1) produced by hypothalamic lesions were also tested, but neither antidiuresis nor natriuresis in response to gastric distension was observed in these D1 rats whose neurohypophysis contained little antidiuretic hormone (ADH). In conclusion, gastric distension may induce liberation of ADH and probably other neurohypophysial hormone which affects renal handling of sodium and water in anesthetized, water-loaded rats.

Animals↗
PubMed1991

Reduction of calcium excretion in the stone-forming kidney in unilateral ureteral obstruction.

Thirteen urolithiasis patients with unilateral obstructive uropathy were treated with percutaneous nephrostomy (PCN) either for urinary diversion, endopyelotomy, nephrolithtotmy or chemolysis. After percutaneous nephrostomy, the individual urine volume, creatinine clearance (Ccr), urinary absolute and fractional excretions of sodium, potassium, calcium, magnesium and inorganic phosphate were measured separately in timed urine collections from a pigtail catheter and from the urethra. The data showed that Ccr and the absolute urinary excretions of sodium, potassium, calcium, magnesium and inorganic phosphate were significantly lower in the PCN kidney immediately or 2 days after relief of obstruction. The ratio of total urinary calcium excretion to urinary creatinine excretion in the obstructed kidney was significantly greater than that in the contralateral kidney. The fractional excretions of calcium and magnesium increased as renal function decreased. The results showed that when the total Ccr is below normal, the apparent excretion of urinary calcium will be underestimated. However, when the total Ccr of patients is within normal range, hypercalciuria may be detected adequately and thus favors early implementation of an appropriate therapeutic strategy.

Calcium↗
PubMed1991

A bronchial response comparison of exercise and methacholine in asthmatic subjects.

The authors compared the inhaled methacholine and exercise responses in 22 stable unmedicated asthmatic patients. The exercise and methacholine challenges were performed at one to three week intervals. Bronchial responsiveness to methacholine was measured in relation to the concentration of methacholine (PC20M). The response to exercise was expressed as the percentage of fall in FEV1 from the pre-exercise FEV1. The findings showed that 21 of 22 subjects demonstrated a fall in FEV1 of more than 20% after methacholine challenge, while only 9/22 subjects experienced a similar decrease in FEV1. All 9 of these positive response exercise cases completed three consecutive exercise challenges prior to the methacholine challenge. Of these cases, five were refractory to the repeated exercise challenge, and the PD20M at the nonexercise stage was significantly lower than the postexercise state. In fact, the methacholine challenge sensitivity actually decreased (PD20 increased) after repeated exercise. The authors concluded that methacholine seems to be a more sensitive bronchial provocation test than exercise. Second, only 55.6% of the exercise test-positive subjects were refractory to the second exercise challenge. Therefore, other factors besides the release of mediators should be considered in exercise-induced asthma. Third, methacholine sensitivity actually decreased (PD20 increases) after repeat exercise challenge.

Adult↗
PubMed1991

[The use of rifampin in the treatment of infection due to Staphylococcus aureus].

Infection due to Staphylococcus aureus continues to be a source of significant morbidity and mortality. However, its treatment is increasingly complicated by the rising prevalence of resistance to antibiotics. Apart from the two recognized modes of staphylococcal resistance, namely, penicillinase production and intrinsic resistance, Sabath and associates have described a third type in which resistance is manifested by susceptibility to growth inhibition but tolerance to the lethal action of bactericidal agents. The mechanism of tolerance is attributed to a deficiency of autolytic enzyme activity in the part of bacteria, possibly secondary to an inhibition of autolysins in the tolerant staphylococcal strains. These strains are found in patients with infections responding poorly to treatment with cell-wall active antibiotics including vancomycin. Because of its unique mechanism of action and pharmacokinetic properties, rifampin has been reported to be the most active among 65 antistaphylococcal agents tested and have the capacity to kill intraleukocytic staphylococci. We present 2 cases who were cured following the addition of rifampin to previously established regimens. Case 1 was a 40-year-old male who had fever, cough, dyspnea, a right elbow abscess and left leg swelling for 2 weeks prior to admission. Culture of purulent material from the elbow abscess grew staphylococcus aureus. Chest X-ray showed bilateral septic embolism and phleborheography showed partial deep vein occlusion of the left ileofemoral vein. Case 2 was 22-year-old female with fever, chills and cough for 3 weeks. Blood culture grew staphylococcus aureus, and Chest X-ray revealed bilateral septic embolism with pneumonia. Neither of them responded to standard antibiotics which were judged adequate by in vitro sensitivity tests. Clinical cure was later obtained after rifampin was added to the regimens. These results suggest that rifampin may be a useful adjunct in the therapy of staphylococcal infections.

Adult↗
PubMed1991

Polymorphonuclear neutrophil function in Kartagener's syndrome--report of two cases.

The clinical triad of Kartagener's syndrome (KS) includes situs inversus, sinusitis and bronchiectasis or at least chronic bronchitis. Immotile cilia with various ultrastructural defects have been seen in KS. Because the enhanced susceptibility to infections seen in KS it had been suspected due to significant abnormality of neutrophil function in addition to a defect of ciliary function. In this report, neutrophil functions such as PMN phagocytosis, PMN chemotaxis, Migration inhibition test and PMN bacterial killing test were studied in two cases of KS at a time when they were free of infection. The defects observed by us were only slight. We conclude that although neutrophil motility of patients is normal, the bactericidal activity is depressed in the early stage. Whether this abnormality enhances patient susceptibility to bacterial infections is not yet clear. The significance and actural mechanism for his delayed killing are now under investigation.

Adult↗
PubMed1991

[Effects of nasal continuous positive airway pressure on patients with obstructive sleep apnea syndrome].

To evaluate the efficacy of nasal continuous positive airway pressure (CPAP) on patients with obstructive sleep apnea syndrome, 20 patients with moderate to severe obstructive sleep apnea syndrome (respiratory disturbance index greater than or equal to 20) were studied. The patients were evaluated using the Grass polysomnograph model 78 during an overnight sleep one to two weeks apart with and without a nasal CPAP produced by 10 to 15 cm of water. The results showed that nasal CPAP significantly reduced the respiratory disturbance index (RDI) (p less than 0.001) and the desaturation index (p less than 0.001), and significantly raised the lowest oxygen saturation level. Nasal CPAP not only reduced RDI, but also improved the respiratory patterns during obstructive apnea events by shifting the obstructive apnea events to hypopnea events. Nasal CPAP also significantly decreased the relative time spent in stage 1 NREM sleep (p less than 0.001), and increased the relative time spent in stages 3+4 NREM and REM sleep (p less than 0.05). Most of the patients also felt better the morning after using nasal CPAP. Nasal CPAP significantly reduced the frequency and duration of apnea and the degree of nocturnal oxygen desaturation, and improved the respiratory patterns during obstructive apnea events, as well as the sleep architecture in obstructive sleep apnea patients. We conclude that nasal CPAP is effective in moderate to severe obstructive sleep apnea syndrome patients.

Adult↗
PubMed1991

Renal dopamine not renal nerve mediates diuretic and natriuretic effect of ANF in rats.

Our previous study demonstrated that acutely or chronically unilateral renal denervation did not blunt intravenous ANF--induced hypotensive and ipsilateral renal effects. The present study was further to examine the permissive role of renal nerve and dopamine in the renal action of ANF. Experiments were conducted on anesthetized rats with either acute unilateral ureter ligation (n = 8), reserpine pretreatment (10 mg/kg, n = 7), mechanically controlled renal arterial pressure (n = 8) or blockade of dopamine D1 receptors by SCH23390 (n = 8, 0.8 micrograms/kg.min). The arterial blood pressure and renal clearance responses to intravenous (0.30-0.45 micrograms/kg.min) or intrarenal (0.10-0.15 micrograms/kg.min) infusion of ANF were measured. The results showed that unilateral ligation of the ureter to physiologically inhibit the contralateral renal efferent nerve activity did not alter the depressor, diuretic and natriuretic effects of ANF. Reserpine pretreatment blunted the diuretic and natriuretic response to intravenous administration of ANF. However, ANF-induced diuresis and natriuresis was persistently observed in both kidneys of rats with the left renal arterial pressure being controlled at a level comparable to that seen in the reserpine-pretreated group. Blockade of intrarenal dopamine D1 receptors by SCH23390 completely abolished the diuretic and natriuretic response to intrarenal infusion of ANF. These results support the notion that the diuretic and natriuretic effect of ANF is not resulted from a decrease in renal sympathetic efferent nerve activity, and further indicate that a mechanism associated with activation of the renal dopamine D1 receptors mediates the renal effect of ANF in rats.

Animals↗
PubMed1991

Renal hemodynamic and tubular effects of angiotensins II and III.

Angiotensin II (ANG II) plays an important role in the regulation of renal vascular resistance, glomerular function and tubular reabsorption. Systemic infusion of ANG II produces dose-dependent decreases in renal blood flow (RBF), glomerular filtration rate (GFR) and filtration coefficient, and increases in filtration fraction. Intrarenally generated ANG II is also critical to alterations in cortical and juxtamedullary glomerular ultrafiltration. On the other hand, pharmacological blockade of the systemical and intrarenal generation or action of ANG II elicits increases in RBF and pressure-associated changes in GFR. In vivo micropuncture experiments demonstrate that peritubular capillary microperfusion of 10(-7) M ANG II results in decreases in single nephron GFR and glomerular capillary pressure. Blockade of ANG II activity by ANG converting enzyme (ACE) inhibitor markedly attenuates, whereas intravenous or peritubular capillary infusion of exogenous ANG II enhances tubuloglomerular feedback (TGF) mediated changes in the stop flow pressure. Moreover, infusion of exogenous ANG II during conditions of ACE blockade partially restores the feedback responsiveness, suggesting a specific role of ANG II as a modulator of TGF system. Besides its effects on intrarenal hemodynamics, ANG II directly or indirectly affects renal sodium excretion. Micropuncture and microperfusion studies have shown that ANG II exerts a dose-dependent biphasic effect on proximal tubular sodium reabsorption via apical Na(+)-H+ exchange. A stimulatory effects of ANG II at low dose (10(-12)-10(-9) M) and an inhibitory effect at higher dose (10(-7)-10(-5) M) have been observed in the cortical and juxtamedullary nephron preparations. The stimulatory effect of ANG II on proximal tubular reabsorption of sodium seems associated with reduction in cAMP and/or activation of protein kinase C, whereas cytosolic free calcium surge activated by ANG II may be part of the cellular message that inhibits proximal tubular reabsorptive function. ANG III, a metabolite of ANG II, also enters substantial influence on renal function. In contrast to the systemic pressor effect, the two peptides are approximately equipotent in their actions on the renal vasculature. Superimposed administration of either ANG II or ANG III during ACE inhibition completely reverses the GFR and renal excretory responses to ACE inhibition. Furthermore, intracerebroventricular injections of ANG II and ANG III in rats inhibit renal nerve activity and cause a comparable renal effect which can be blocked by Ile7-ANG III and potentiated by bestatin, suggesting that the heptapeptide may also play an active role in the regulation of sodium excretion by actions on renal hemodynamics and tubules.

Angiotensin II↗
PubMed1990

[Renal effect of isoflurane].

Isoflurane is a pentafluorinated methyl ether and can be metabolized to inorganic fluoride in man. Nephrotoxicity may be developed after it's administration. The present study was carried out to evaluate the effects of isoflurane on renal hemodynamic and excretory function in 15 patients. The systolic, diastolic and mean arterial pressure and renal function were measured before, during and after induction of anesthesia by isoflurane. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were estimated by the clearances of paraaminohippuric acid and inulin, respectively. The results showed that a slight reduction in systolic pressure but no significant change in diastolic and mean blood pressures were found during anesthesia. There were 30% and 50% reductions in RPF and GFR, respectively. The filtration fraction increased significantly. Simultaneous decreases in urine flow, absolute and fractional excretions of sodium, absolute excretion of potassium, osmolar clearance and free water reabsorption rate were observed during isoflurane anesthesia. However, the blood pressure and renal function returned to pre-anesthesia levels 30-60 minutes after termination of anesthesia. These data suggest that isoflurane induces renal depressive effect which is reversible and temporary.

Adult↗
PubMed1990

Role of renal nerves in the hypotensive and the renal effects of atrial natriuretic factor in rats.

Our earlier studies have demonstrated that atrial natriuretic factor (ANF) can produce hypotensive, natriuretic and diuretic effects and that changes in the renal nerve activity can alter the renal excretory function. A few previous studies suggested that ANF could change the renal nerve activity. Thus, the present study was designed to assess the role of the renal nerve in the natriuretic and diuretic effect of ANF. Experiments were conducted on four groups of anesthetized Sprague-Dawley rats: normal control rats, unilateral acute renal denervated rats with and without ANF administration and chronic renal denervated rats. The arterial blood pressure and the renal function responses to intravenous infusion of graded doses of ANF (atriopeptin III. 0.15, 0.30 and 0.45 microgram/kg.min) were studied. In normal rats, infusion of ANF significantly decreased the mean arterial blood pressure in a dose-related pattern (from 109 +/- 2 to 107 +/- 3, 102 +/- 4 and 89 +/- 5 mmHg, respectively). The glomerular filtration rate (GFR) did not change significantly whereas the urine flow and the absolute and the fractional excretion rates of sodium and potassium were significantly increased. Renal denervation alone did not change the blood pressure and GFR, but produced ipsilateral diuresis and saluresis without changing the function of the contralateral kidney. Subsequent administration of ANF decreased the blood pressure but did not affect bilateral GFR. There were significant increments in the urine flow and the excretions of sodium and potassium in both the denervated and the contralateral kidneys. Infusion of ANF into chronic renal denervated rats also reduced the blood pressure and increased the renal excretion of water and sodium. These results indicate that the diuretic and the natriuretic effects of ANF is not resulted from a decreased activity of the renal efferent nerve and that the hypotensive and the renal effects of ANF are independent of renal innervation.

Animals↗
PubMed1989

Dynamics of bases in hydrated [d(CGCGAATTCGCG)]2.

Solid-state 2H NMR spectroscopy has been used to investigate the dynamics of a DNA oligonucleotide with a defined sequence, [d(CGCGAATTCGCG)]2, which contains the EcoRI binding site. Quadrupole echo line shapes and spin-lattice relaxation times were obtained as a function of hydration on two different deuterated samples, both in the form of the Na salt. In one sample, the C8 protons of all purines in the self-complementary dodecamer were exchanged for deuterons. In the other sample, a specifically labeled thymidine (C6 deuterated) was synthetically incorporated at the seventh position (counting 5' to 3') in the sequence. The general trends for both samples were quite similar. At all levels of hydration, the data reveal the presence of a rapid, small-amplitude libration of the bases (tau c less than or equal to 1 ns, 6 degrees-10 degrees amplitude). At the higher hydration levels (80% relative humidity or higher), the results indicate the presence of a much slower motion (tau c approximately 10-100 microseconds), which at 80% relative humidity is of small amplitude (approximately 5 degrees) and at higher hydration levels may be of larger amplitude. There is no evidence for large-amplitude (greater than +/- 10 degrees) motion on a nanosecond or faster time scale under any hydration condition. The 2H NMR results were analyzed with a dynamical model which treats the oligonucleotide as a deformable filament and which can include collective torsional fluctuations. The slow motion observed at high hydration levels is attributed to the uniform twisting mode (of the entire helix).(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1989

Effect of fructose-induced hypertension on the renin-angiotensin-aldosterone system and atrial natriuretic factor.

Studies were performed to examine the effects of a high fructose intake on blood pressure, the renin-angiotensin-aldosterone system, and atrial natriuretic factor in normal rats. Sprague-Dawley rats were fed with either normal rat chow or a fructose-enriched diet for four or seven weeks. High dietary fructose consumption induced hyperinsulinemia and hypertriglyceridemia, and increased the systolic blood pressure by 19 +/- 4 mm Hg (four weeks of diet) and 24 +/- 1 mm Hg (seven weeks of diet), respectively. There were no significant changes in the plasma renin activity at either time. However, an increase in plasma atrial natriuretic factor was noted in rats treated with a high fructose diet for four weeks, and a decrease in plasma aldosterone was found in those rats fed with fructose for a longer period. There was no significant difference in body weight gain between rats fed with fructose-enriched diet and those fed with control diet. These data indicate that the increase in blood pressure associated with a high fructose intake is not due to a direct effect or the renin-angiotensin-aldosterone system.

Animals↗
PubMed1989

Chemiluminescence and antibody-dependent, cell-mediated cytotoxicity between human alveolar macrophages and peripheral blood monocytes in smokers, nonsmokers, and lung cancer patients.

Some evidence suggests a capability of peripheral blood monocytes to destroy tumor cells, while this ability by human alveolar macrophages, the main defense cells in the alveoli, is still debatable. We measured the chemiluminescence and antibody-dependent, cell-mediated cytotoxicity in the PBMs and HAMs of 12 lung cancer patients and 20 healthy subjects; the latter included ten smokers and ten nonsmokers. The PBMs were prepared by using a Ficoll-Hypaque density gradient, then separated by Petri-dish adherence. The HAMs were taken during the bronchoalveolar lavages. The chemiluminescence in the HAMs of smokers was significantly higher than nonsmokers, (p less than 0.05), which did not occur in the PBMs. Chemiluminescence in HAMs from the lung cancer patients was also significantly higher than the smoker control subjects (p less than 0.01). However, the lung cancer patients had significantly lower ADCC activity than the smokers in the control group (4.52 +/- 2.96 vs 8.27 +/- 2.83 percent; p less than 0.05). The chemiluminescence in the PBMs showed no statistical difference between the lung cancer patients and smoker control, but PBMs of the lung cancer patients had significantly lower ADCC activity than the smoker normal control group. The HAMs from lung cancer patients produced more superoxide anion, for an increased chemiluminescence reaction was noted, although ADCC activity was lower than in smokers, ie, HAMs were ineffective in killing tumors. Environmental factors such as cigarette smoking affect HAM's function by causing an increase of superoxide anion production. The chemiluminescence and ADCC activity in the PBMs does not always correspond to the HAMs findings. These results suggest that PBMs can not accurately reflect or predict the HAMs' function in lung diseases.

Adult↗
PubMed1989

Differential renal responses to atrial natriuretic peptide in two-kidney, one clip goldblatt hypertensive rats.

Bilateral renal clearance experiments were performed to examine the effects of synthetic rat atrial natriuretic peptide (ANP, atriopeptin II) on the arterial blood pressure (BP) and individual kidney function in anesthetized 2-kidney, 1 clip Goldblatt hypertensive rats (n = 14) and normotensive rats (n = 15). Bolus administration of graded doses of ANP from 2.5 to 10 micrograms/kg produced dose-related reductions in BP in hypertensive and normotensive rats. Despite profound reductions in BP, there were significant increases in glomerular filtration rate, urine flow, absolute and fractional excretion rates of sodium and potassium, osmolar clearance, and free water clearance in the nonclipped kidney, whereas no significant changes in these renal indices occurred in the clipped kidney. The enhanced renal responses were dose-dependent. The normal kidney responded to ANP with similar magnitude. When ANP was infused intravenously (0.3 microgram/kg.min i.v.) during 2 h, BP maximally reduced by 36 +/- 2 mm Hg (24 +/- 1%) in the hypertensive group and by 27 +/- 2 mm Hg (22 +/- 2%) in the control group. Again, there were distinct renal responses between the two kidneys of hypertensive rats. These results indicate that ANP effectively reduces BP and preferentially increases the excretory function of the nonclipped kidney without compromising the function of the clipped kidney in this hypertensive model.

Animals↗
PubMed1989

[Prognosis of chronic obstructive pulmonary disease after acute respiratory failure].

We followed the course of 53 patients (male 38, female 15 and average age 66 +/- 10) with chronic obstructive pulmonary disease hospitalized in our intensive care unit due to acute episode of respiratory failure. Etiologies of acute respiratory failure, patient's clinical data and arterial blood gases analysis were recorded. Most of the results showed no significant difference between the initial survival and the non-survival group. Low hematocrit. hypoalbulinemia and severe hypoxemia were found in the dead group but relative hypercapnea in the survival group was noted. Infection was the most common cause of acute respiratory failure and following by congestive heart failure, pneumothorax and asphyxia. Intubation and mechanical ventilator were needed in all patients except 3 cases to whom only conservative treatment was given. Hospital mortality was 50.9 percent (27/53) and most of the cases (22/53) died in the intensive care unit. Twenty six cases (49.1%) were discharged from the hospital and follow-up was continued for at least two years. Fifteen patients died during two year follow-up and except for one suicide case all died of repeated respiratory failure. The two year survival was only 20.8 percent (11/53). The prognosis of patients with chronic obstructive pulmonary disease following an episode of acute respiratory failure is poor.

Acute Disease↗
PubMed1988

Effect of unilateral renal denervation on bilateral renal response to saline loading in anteroventral third ventricle-lesioned rats.

Our previous experiments demonstrated that lesions in the anteroventral third ventricle (AV3V) region of the brain attenuated natriuretic and diuretic response to saline loading in rats. To further assess if renal nerves are involved in this impaired response, we compared the effect of acute unilateral renal denervation on the response to saline loading in AV3V-lesioned and intact rats. Rats with electrolytic ablation in the AV3V region were prepared 4 weeks prior to experiments. The arterial blood pressure (BP) and bilateral renal responses to acute expansion of plasma volume by saline loading (0.388 ml/min for 1 h) were measured in rats under pentobarbital anesthesia. Saline loading before renal denervation induced a smaller increase in bilateral renal excretion of sodium and water in AV3V-lesioned rats than in control rats. Acute renal denervation produced ipsilateral natriuresis and diuresis without causing significant change in the excretory functions of the contralateral kidneys in both the lesioned and the control rats. BP and glomerular filtration rate of both groups of rats remained unaltered. The denervation-induced natriuretic and diuretic responses in the lesioned rats were not significantly different from those of the control rats. Subsequent saline loading increased bilateral renal excretion of sodium and water in both groups of rats. However, the previously observed attenuation of natriuretic and diuretic responses to saline loading in rats with AV3V lesions was abolished after renal denervation. These results suggest that the integrity of the AV3V region is necessary for normal regulation of sodium and water balance. Furthermore, there is a functional connection between the renal nerve and the AV3V region in modulating renal excretion during volume expansion.

Animals↗