Biomedical subjects

Ming-Shiou Wu

Publications and source records attributed to Ming-Shiou Wu.

5 recordsLinked to original sources

PubMed2002

Enhanced expression of nitric oxide synthase in the early stage after increased pulmonary blood flow in rats.

OBJECTIVE: Evidence that vasodilator nitric oxide mediates normal pulmonary vascular tone has led to the hypothesis that endothelial injury induced by congenital heart disease with increased pulmonary blood flow disrupts these regulatory mechanisms and its associated altered vascular reactivity. Therefore, we hypothesized that increased pulmonary blood flow results in altered expression of endothelial nitric oxide synthase (eNOS). METHODS: We created an arteriovenous shunt in female Wistar (5-week-old) and measured the change of pulmonary blood flow and pressure immediately after and 1 month after the shunt operation. The protein levels of eNOS in the lung tissues of rats were assessed. RESULTS: The shunt immediately resulted in a significant increase in pulmonary blood flow (16.5 +/- 11.8% , pulmonary artery pressure (2.3 +/- 0.7 mm Hg), and blood O(2) saturation (16.1 +/- 11.8%) in the pulmonary artery. After 4 weeks, there was a significant increase in pulmonary blood flow (30.7 +/- 1.6%), pulmonary artery pressures (4.3 +/- 1.1 mm Hg), and blood O(2) content (43.3 +/- 17.5%). Western blot analysis demonstrated that eNOS protein was increased in the shunt lung 72 h after surgery and recovered to the control level 1 week later. CONCLUSION: This simple shunt model can induce early upregulation of eNOS expression with increased pulmonary blood flow and pulmonary artery pressure in rats.

Analysis of Variance↗

PubMed2002

Impaired renal sensory responses after renal ischemia in the rat.

Renal sensory responses and reflex function were examined in rats 24 h after 45 min of ischemic injury caused by unilateral renal arterial occlusion (RAO). The integrity of renal pelvic mechanoreceptor (MRu)-mediated renorenal reflex was examined. An increase in ipsilateral afferent renal nerve activity (ARNA) and a reflex decrease in efferent renal nerve activity (ERNA) and contralateral diuresis and natriuresis produced by increasing the intrapelvic pressure were seen in sham-operated (Sham) rats, but it was largely attenuated in RAO rats. Using single-fiber recordings of the renal MRu discharge, graded increases in intrapelvic pressure or renal pelvic administration of substance P (SP) resulted in pressure- or concentration-dependent increases in ARNA in the control kidney of Sham rats, whereas attenuated responses were seen in the postischemic kidney of RAO rats. The unresponsiveness of renal MRus in RAO rats was accompanied by an insufficient release of SP. However, the baseline SP release is higher in RAO kidneys due to a reduced neutral endopeptidase (NEP) activity in the renal pelvis of the postischemic kidney. No changes in NK-1 receptor mRNA levels were demonstrated; however, the expression of NK-1 receptors in the plasma membrane of RAO pelvis were decreased, possibly resulting from the internalization of the receptors associated with beta-arrestin trafficking. Renal excretory responses after saline loading were significantly lower in the postischemic kidney of RAO rats than in Sham rats. Responses of ARNA and ERNA were also lower. It is concluded that the defective activation of renal sensory mechanoreceptors in the postischemic kidney results from an inadequate release of SP after mechanostimulation and the reduced functional NK-1 receptors.

Animals↗

PubMed2002

Temporal decrease in renal sensory responses in rats after chronic ligation of the bile duct.

Renal responses to renal sensory receptor activation were examined in rats after 1 and 4 wk of common bile duct ligation (CBDL). Compared with sham-operated rats (Sham), urine and sodium excretion after acute saline loading was significantly reduced at both times after CBDL. The blunted excretory responses in CBDL rats, accompanied by less activation of afferent renal nerve activity (ARNA), were already apparent at 1 wk and became severe at 4 wk. The defect in ARNA activation in CBDL rats was further studied using specific stimuli to activate renal sensory receptors. Graded increases in intrapelvic pressure or renal pelvic perfusion of substance P (SP) elicited an increase in ARNA in Sham rats, these responses being temporally attenuated in CBDL rats. Despite no significant change in renal pelvic SP release, no renorenal reflex was demonstrable in 4-wk CBDL rats. Immunoblotting showed that expression of renal pelvic neurokinin 1 (NK-1) receptors was 32 and 47% lower in 1- and 4-wk CBDL rats, respectively, than in Sham rats, this decrease correlating well with plasma SP levels. The quantitative real-time RT-PCR showed similar levels of NK-1 receptor mRNA in the renal pelvis in the Sham and 4-wk CBDL groups. We conclude that impairment of renal excretory and sensory responses increases with the duration of cirrhosis. An impaired renorenal reflex in cirrhotic rats is involved in the defective activation of the renal sensory receptors could be due, in part, to the low expression of NK-1 receptors, which is dependent on the duration of CBDL. The decrease in NK-1 receptor protein levels is not due to a decrease in mRNA levels.

Animals↗

PubMed2002

Thrombotic microangiopathy in hemophagocytic syndrome: a case report.

A rare case of thrombotic microangiopathy in a patient with hemophagocytic syndrome is reported. An 18-year-old girl was admitted following prolonged fever, watery diarrhea, abdominal discomfort, and a 2-week history of rhinorrhea, cough, and painful cervical lymph nodes. Anemia, thrombocytopenia, jaundice, hepatomegaly, and mild azotemia developed within 2 weeks of admission. The diagnosis of a reactive hemophagocytic syndrome, probably secondary to infection, was made based on the findings of bone marrow examination. Extensive investigation failed to identify a causative agent. The disease initially responded rapidly to intravenous steroids and high-dose immunoglobulin therapy but relapsed soon after tapering of the steroids. Although her condition improved again on resumption of treatment with high-dose steroids, nephrotic range proteinuria and microscopic hematuria developed after the steroids were tapered. Fragmented erythrocytes were seen in peripheral blood with elevated serum lactate dehydrogenase and decreased serum haptoglobin concentrations. The results of subsequent renal pathology examination were also compatible with thrombotic microangiopathy. The disease course finally stabilized after a course of pulse methylprednisolone therapy. Immune hyperactivity, particularly hypercytokinemia and monocyte hyperactivity, could have accounted for the development of thrombotic microangiopathy in this case. Only strong immunosuppressive therapy can control such disease activity.

Adolescent↗

PubMed2002

Rhabdomyolysis associated with Streptococcus pneumoniae bacteremia in a splenectomized patient.

Invasive infection due to Streptococcus pneumoniae associated with rhabdomyolysis is rare. We report the case of a 31-year-old splenectomized man with pneumococcal bacteremia and paranasal sinusitis who presented with flu-like symptoms preceding a fulminant course of sepsis and rhabdomyolysis with acute renal failure and elevated creatinine phosphokinase. Although the possible mechanisms of rhabodomyolysis associated with pneumococcal infection remain unclear, this report may serve to alert clinicians of the need to prevent fulminant pneumococcal infection by vaccination and treatment with antibiotic prophylaxis in splenectomized patients.

Acute Kidney Injury↗