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Biomedical subjects

J G Porush

Publications and source records attributed to J G Porush.

At least 55 records · Page 3Linked to original sources
PubMed1983

Use of oral clonidine for rapid titration of blood pressure in severe hypertension.

In 20 patients with severe hypertension, rapid oral clonidine titration was employed for control of blood pressure, with 0.2 mg as the initial dose followed by 0.2 or 0.1 mg at one hour and then 0.1 mg/hour, for a total dose of 0.8 mg. All 20 patients had a successful response, defined as a decrease in mean arterial pressure (MAP) of 30 mm Hg or more or attainment of a diastolic pressure of 100 mm Hg or lower. Baseline MAP was 160 +/- 4 (SEM) mm Hg (212 +/- 7/134 +/- 3) and decreased to 120 +/- 3 mm Hg (151 +/- 5/104 +/- 3). The mean dose was 0.32 +/- 0.02 mg, and mean response time 1.8 +/- 0.2 hours. Side effects were minimal, except for one patient who died of a cerebral infarct, which developed after the blood pressure was lowered with clonidine. Eighteen patients were treated in our emergency room; 14 were sent home after rapid titration. In ten who returned for a follow-up visit three to seven days later, blood pressure was reasonably well controlled, with clonidine and a diuretic only. Rapid oral clonidine titration can be effectively and, for the most part, safely used for treating severe hypertension even in an ambulatory setting. As with any other hypotensive drug, we recommended proceeding with caution, particularly in patients with symptomatic arteriosclerotic disease.

Administration, Oral↗
PubMed1982

Retroperitoneal fibrosis presenting as spontaneously reversible renal failure.

Three patients are reported who presented with severe oliguric renal failure due to retroperitoneal fibrosis and obstructive uropathy in whom spontaneous diuresis and recovery of renal function took place, a course resembling acute tubular necrosis. There were, however, several clinical and laboratory findings that provided clues to the presence of obstructive uropathy. Two of the three patients had low back or abdominal pain. All three patients presented with anemia and significant hyperkalemic, hyperchloremic metabolic acidosis with only a small increase in anion gap and two of the patients had an inappropriately high urine pH. Neither tubular cell casts nor pigmented granular casts were identified in the urine in any of the patients. In all three patients the urine output increased from oliguric levels to 1400 - 2000 ml/day within 1 day associated with rapidly improving renal function. This report demonstrates and reinforces the need to rule out obstruction in all patients with renal failure of unknown etiology and adds retroperitoneal fibrosis to the list of diseases associated with renal failure and spontaneous recovery.

Acute Kidney Injury↗
PubMed1982

Effects of diuretics on inner medullary hemodynamics in the dog.

Although the hemodynamic effects of diuretics have been studied extensively, their effects on inner medullary blood flow remain unknown. In the present study, renal hemodynamics, including papillary plasma flow measured by the albumin accumulation technique, and associated alterations in papillary tissue solute content were determined in anesthetized, hydropenic dogs and during euvolemic diuresis induced by furosemide (3 mg/kg plus 2 mg/kg per hr, iv), ethacrynic acid (3 mg/kg plus 2 mg/kg per hr, iv) or chlorothiazide (10 mg/kg plus 10 mg/kg per hr, iv). Renal blood flow increased significantly after furosemide and ethacrynic acid and decreased significantly after chlorothiazide. Sixty minutes after diuretic administration, papillary plasma flow was 10.8 +/- 1.0 (mean +/- SE) in six furosemide- and 11.3 +/- 2.6 ml/min per 100 g in six ethacrynic acid-treated dogs, both significantly lower than in eight normal or eight chlorothiazide-treated dogs [26.4 +/- 2.6 and 26.7 +/- 2.7 ml/min per 100 g, respectively (P less than 0.01)]. A similarly low papillary plasma flow was also noted 10 minutes after diuretic administration in five furosemide and four ethacrynic acid dogs (13.6 +/- 2.3 and 13.4 +/- 1.8 ml/min per 100 g, respectively). In furosemide and ethacrynic acid dogs, papillary osmolality and sodium content were significantly lower than those in normal or chlorothiazide dogs. In normal and chlorothiazide dogs, papillary sodium content was similar, with a significantly reduced papillary osmolality in the latter. At the time papillary plasma flow was measured, extracellular fluid volume was similar among the four groups of dogs; however, plasma renin activity increased significantly in furosemide and ethacrynic acid dogs (P less than 0.01) and remained unchanged in normal and chlorothiazide dogs. Furthermore, papillary plasma flow was restored to normal (25.3 +/- 3.9 ml/min per 100 g) in five dogs in which furosemide was infused during angiotensin II blockage with saralasin, despite a similar diuresis and natriuresis as the other furosemide group. These data demonstrate that after administration of furosemide, ethacrynic acid and chlorothiazide, regulation of papillary plasma flow is independent of renal blood flow, and suggest that angiotensin II may play a role in the reduced papillary plasma flow in furosemide and ethacrynic acid dogs.

Animals↗
PubMed1981

Infusion intravenous pyelography and renal function. Effect of hypertonic mannitol in patients with chronic renal insufficiency.

In a previous prospective study, we reported that infusion intravenous pyelography (IVP) in 40 patients with chronic renal insufficiency resulted in acute renal failure (ARF) in 28 patients (70%). In an attempt to prevent this complication, we have evaluated the conditions of another group of 37 patients with chronic renal insufficiency treated in a similar manner except that each patient received 250 mL of 20% mannitol 60 minutes after infusion of the IVP dye (diatrizoate sodium, 300 mL of a 30% solution). These patients were similar to those in the previous study with regard to age, sex, renal function, and incidence of diabetes. Only eight (22%) of the 37 patients had ARF develop after infusion IVP in this study. This incidence was significantly lower compared with 70% in the previous study. We conclude that administration of hypertonic mannitol 60 minutes after administration of the radiographic contrast material is highly effective in preventing ARF after infusion IVP in patients with chronic renal insufficiency.

Acute Kidney Injury↗
PubMed1980

Uterine and renal renin release after ligation of the uterine arteries in the pregnant rabbit.

Uteroplacental ischemia is associated with uterine renin release in pregnant nephrectomized rabbits. In the present study, uterine and renal renin release after uteroplacental ischemia were investigated in 10 Australian white rabbits at 24 to 28 days' gestation. Pentobarbital was administered, and both uterine arteries were ligated close to their origins. Blood samples were taken for plasma renin activity (PRA) determinations from the femoral artery, uterine vein, and right renal vein before ligation and at 30 and 60 minutes after ligation. Mean arterial blood pressure (MAP) was monitored throughout. In five additional pregnant rabbits renal blood flow (RBF) was measured with an electromagnetic flowmeter. The preligation uterine vein-artery PRA difference was not significant (1.9 +/- 1.1 ng/ml/hr). Postligation uterine vein-artery PRA was 11.4 +/- 3.2 at 30 minutes and 6.6 +/- 1.9 ng/ml/hr at 90 minutes (p less than 0.02). Preligation renal vein-artery PRA was 32.3 +/- 10.5 ng/ml/hr (p less than 0.02) and did not change significantly after ligation. MAP remained stable and RBF was unchanged after uterine artery ligation. These observations confirm the finding that the kidney is the primary source of renin in the normal pregnant rabbit and demonstrate that following acute uteroplacental ischemia there is significant uterine renin release even when the kidneys are intact.

Animals↗
PubMed1980

Pulmonary calcification in hemodialyzed patients detected by technetium-99m diphosphonate scanning.

Metastatic pulmonary calcification, a well-known complication in patients with chronic disease, has been demonstrated postmortem in patients with a negative chest X-ray. Recently, scintigrams with bone-seeking radionuclides have been used to detect such subclinical pulmonary calcium deposits. We describe 23 patients on maintenance hemodialysis with no evidence of pulmonary calcification on chest X-ray who were prospectively studied by lung scanning with a bone-seeking radionuclide and pulmonary function testing. Of the 23 patients, 14 (61%) had a positive technetium-99m diphosphonate (99mTc-DP) scan (group 1). These patients were on dialysis 38 +/- 5 months compared with 12 +/- 4 months in 9 patients with a negative scan (group 2) (P less than 0.01). Age, sex, blood pressure, hematocrit, serum calcium, phosphorous, bicarbonate, magnesium, and calcium X phosphorus product, as well as parathyroid hormone level did not differ between the two groups. Of 10 group-1 patients tested, 7 had abnormal pulmonary diffusion capacity compared with non in 5 group-2 patients tested (P = 0.014). Histologic examination of the lung in 1 group-1 patients who expired revealed calcification (amorphous on X-ray diffraction), whereas none was found in 1 group-2 patients autopsied. These observations suggest that in patients on maintenance hemodialysis, pulmonary scanning with 99mTc-DP is a sensitive method for detecting pulmonary metastatic calcification, which may be associated with an abnormality in pulmonary diffusion capacity.

Adult↗
PubMed1979

Low-dose heparin in routine hemodialysis monitored by activated partial thromboplastin time.

To evaluate the use of the activated partial thromboplastin time (APTT), as measured by the Coag-A-Mate semi-automatic unit, in lowering the dosage of heparin in stable chronic hemodialysis patients, four protocols for anticoagulation were utilized. Ten patients were dialyzed five times with each protocol. In protocol I, clotting time was performed baseline, 2 and 4 hours and in protocol II, baseline and every 30 minutes, with heparin administered by bolus to keep the clotting time at 2-2 1/2 times normal. In protocols III and IV the APTT was performed every 30 minutes, with heparin given by bolus in protocol III and infusion in protocol IV, to keep the APTT 1 1/2-2 times normal. Protocol I required 6000 +/- 543 U of heparin with the dose decreasing significantly to 3694 +/- 158 U in protocol II, 2634 +/- 139 U in protocol III and 2013 +/- 117 U in protocol IV (P less than 0.05- less than 0.001). Three episodes of clotting occurred, one in protocol III and two in protocol IV. There was no bleeding, and clearances of urea, creatinine, phosphate and uric acid at 1 and 5 hours were similar in all protocols. APTT, as measured by the Coag-A-Mate unit, provides a simple means of lowering heparin requirements in routine dialysis patients.

Blood Coagulation↗
PubMed1978

Infusion intravenous pyelography and renal function. Effects in patients with chronic renal insufficiency.

Acute renal failure (ARF) following infusion intravenous pyelography (IVP) has been reported in patients with chronic renal insufficiency, particularly diabetics. Renal function was evaluated before and after infusion IVP in 40 patients with chronic renal insufficiency. In 11 of 12 (92%) diabetics and 17 of 28 (61%) nondiabetics, a 25% or greater increase in serum creatinine values and/or decrease in creatinine clearance was noted after IVP despite adequate hydration in all patients. The maximum decrease in kidney function occurred within three days and usually returned to or near pre-IVP levels in seven to ten days. At least 70% of the patients had hypertension and/or evidence of vascular disease. The data suggest that preexisting vascular disease in the kidney, possibly associated with the known vasoconstricting effects of contrast media, may be an important factor in the ARF following infusion IVP.

Creatinine↗
PubMed1977

Effects of acetazolamide on proximal tubule C1, Na, and HCO3 transport in normal and acidotic dogs during distal blockade.

It has been suggested that the establishment of a tubular fluid to plasma chloride gradient in the late proximal tubule by the reabsorption of bicarbonate (and other anions) in the early proximal tubule is responsible for a significant part of sodium chloride and water reabsorption in the proximal tubule. In the present study the effects of acetazolamide on proximal tubule water and electrolyte excretion were examined in 6 normal dogs and 10 chronic ammonium chloride-loaded dogs during distal blockade produced by ethacrynic acid and chlorothiazide administration. During distal blockade control urine/plasma osmolality and urine/plasma sodium were close to unity in all experiments. Urine/plasma chloride and urine/plasma bicarbonate were 1.21+/-0.02 and 0.75+/-0.07 in normal and 1.24+/-0.01 and 0.04+/-0.01 in acidotic dogs, respectively. After the administration of acetazolamide (20 mg/kg i.v.), there was a significant increase in urine flow, absolute and fractional excretion of sodium, bicarbonate, and chloride in all animals. Associated with these effects, urine/plasma osmolality and urine/plasma sodium remained unchanged but urine/plasma chloride decreased significantly to 1.15+/-0.01 in normal and to 1.19+/-0.01 in acidotic dogs. In acidotic dogs there was a significant correlation between the increase in bicarbonate, sodium, or chloride excretion after acetazolamide and the plasma bicarbonate level (range 6.8-12.5 meq/liter). These data demonstrate a significant effect of acetazolamide on bicarbonate, sodium, and chloride reabsorption in the proximal tubule even in the face of severe acidosis. Moreover, the data suggest that the decrease in chloride reabsorption (and accompanying sodium) after acetazolamide is related to the decrease in bicarbonate reabsorption and the associated decrease in the transtubular chloride gradient.

Acetazolamide↗