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Biomedical subjects

E V Dubovsky

Publications and source records attributed to E V Dubovsky.

At least 19 recordsLinked to original sources
PubMed1992

Renal transplant hypertension caused by iliac artery stenosis.

A captopril renal study performed with both radiohippuran and 99mTc-MAG3 demonstrated the typical changes of a hemodynamically significant renal artery stenosis in a hypertensive renal allograft recipient. Arteriography demonstrated high grade stenosis not of the renal artery but of the iliac artery. After successful angioplasty, the patient's hypertension resolved.

Captopril↗
PubMed1991

Rapid loss of vertebral mineral density after renal transplantation.

BACKGROUND: Osteopenia is a major complication of renal transplantation. Immunosuppressive regimens including cyclosporine, which permit the use of lower doses of glucocorticoids, may reduce glucocorticoid-induced osteopenia. METHODS: We prospectively studied the magnitude, distribution, and mechanism of bone loss in 20 adults who received renal allografts from living related donors, who had good renal function, and who were treated with azathioprine, cyclosporine, and low doses of prednisone. We measured serum biochemical markers of bone metabolism, determined the bone mineral density of the second, third, and fourth lumbar vertebrae and the shaft of the radius, and analyzed the histomorphometric features of iliac bone at the time of transplantation and six months later. Measurements of vertebral mineral density were repeated 18 months after transplantation in 17 of the patients. RESULTS: After transplantation, the mean serum concentrations of parathyroid hormone, phosphorus, and alkaline phosphatase decreased and the serum calcitriol concentration increased. The mean (+/- SD) bone mineral density of the vertebrae had decreased 6.8 +/- 5.6 percent 6 months after transplantation (P less than 0.05) and 8.8 +/- 7.0 percent 18 months after transplantation. In contrast, the bone mineral density of the radius had increased six months after transplantation (P less than 0.05). The histomorphometric studies showed that the rate of bone formation decreased from 50.5 +/- 44.8 to 23.1 +/- 13.8 microns3 per square micrometer per year (P less than 0.05), and the formation period lengthened from 70 +/- 42 to 146 +/- 144 days (P less than 0.05). Consequently, the amount of bone replaced during a remodeling cycle diminished. CONCLUSIONS: Osteopenia associated with renal transplantation remains a problem in the cyclosporine era. The loss of vertebral bone in our subjects was due to an imbalance in bone remodeling consistent with a toxic effect of glucocorticoids.

Adult↗
PubMed1991

Short-term and long-term changes in renal function after donor nephrectomy.

We retrospectively examined the effect of nephrectomy on renal function in 55 living related donors. Renal function was measured with 131iodine-orthoiodohippurate scans. All patients were studied preoperatively, and 1 week and 1 year postoperatively. In 20 patients 10-year followup was available. Compensatory hypertrophy was complete 1 week postoperatively: effective renal plasma flow of the remaining kidney was 32.5% higher than preoperatively. The increase remained stable for at least a year. The degree of compensatory hypertrophy was significantly greater in male patients (46.9% after 1 week) than in female patients (26.7%). Compensatory hypertrophy occurred in all age groups studied and it was most pronounced in patients less than 30 years old. In the patients followed for 10 years effective renal plasma flow decreased from 387.7 ml. per minute 1 week after nephrectomy to 367.4 ml. per minute at 10 years. This result is similar to the decrease seen in the normal population. According to our results, renal donation by living related persons does not lead to long-term decrease in renal function.

Adaptation, Physiological↗
PubMed1991

Long-term follow-up of a human subject with a remnant kidney.

It has been proposed that once functioning renal mass has been reduced below a critical level, either as the result of disease, congenital absence of a kidney, or surgical ablation, that hyperfiltration and glomerular hypertension lead to progressive glomerular sclerosis and end-stage renal failure. We report the clinical course and renal function of a human subject followed for 10.8 years after extensive renal ablation. Functioning renal mass was estimated at one fourth to one fifth of normal. During the follow-up period, creatinine clearance increased from 0.27 mL/s (16 mL/min) to 0.88 mL/s (53 mL/min), the total renal plasma flow (all of which was to the left kidney) increased from 62 mL/min to 190 mL/min, and 24-hour urine protein excretion increased from 0.09 g to 0.4 g. Despite probable glomerular hyperfiltration, neither progressive glomerular dysfunction nor end-stage renal failure developed over a period of 10 years.

Adult↗
PubMed1991

Diagnosis of renovascular hypertension after renal transplantation.

Hypertension in renal transplant recipients is an important risk factor for graft function and cardiovascular morbidity and mortality. The mechanisms of posttransplant hypertension are not well understood. Most of the time, the nature of this hypertension is multifactorial. Rejection, both acute and chronic, recurrent renal disease, graft renal artery stenosis, native kidney disease and drug therapy with steroids and cyclosporin have all been implicated. Where a single cause can be identified, the therapy can be rational and often very successful. For this reason, the diagnosis of graft renal artery stenosis is important, because percutaneous transluminal angioplasty or surgery can lead to the cure of hypertension and improvement of the graft function. Noninvasive testing, using captopril renography for the diagnosis of hemodynamically significant renal artery stenosis, presently yields encouraging results.

Captopril↗
PubMed1991

Report of the Working Party Group on Determining the Radionuclide of Choice.

There are a variety of radiopharmaceuticals that can be used to perform captopril renography effectively. We examined a number of technetium and iodine compounds and the circumstances under which each radiopharmaceutical compound is the compound of choice. Considerations of cost, ease of use, reliability, dosage, and the effects of different protocols were all examined.

Captopril↗
PubMed1991

Simplified methods for renal clearance in children: scaling for patient size.

Development and validation of simplified renal clearance methods has required a research data base of multiple blood samples drawn over a substantial time interval, which is difficult to obtain for children. While the medical risks entailed in drawing multiple samples may be negligible, the problems of parental and institutional consent make such studies more difficult in the pediatric population. Scaling for patient size permits combining data from patients of different age and limits the number of studies required. A scaling technique is presented and evaluated here. With scaling, adult data can be used successfully to predict pediatric responses and to develop pediatric methods based on adult data alone. Inclusion of pediatric data improves the fit and permits development of generic methods that work with both adults and children.

Adolescent↗
PubMed1990

Measurement of renal parenchymal transit time of 99mTc-MAG3 using factor analysis.

Renal parenchymal transit time of the recently introduced radiopharmaceutical 99mTc-MAG3 (mercaptoacetylglycylglycinel) was measured in 37 kidneys, using factor analysis to separate parenchymal activity from that in the collecting system. A new factor algorithm was employed, based on prior interpolative background subtraction and use of the fact that the initial slope of the collecting system factor time-activity curve must be zero. The only operator intervention required was selection of a rectangular region enclosing the kidney (by identifying two points at opposite corners). Transit time was calculated from the factor time-activity curves both by deconvolution of the parenchymal factor curve and also by measuring the appearance time for collecting system activity from the collecting system factor curve. There was substantial agreement between the two methods. Factor analysis led to a narrower range of normal values than a conventional cortical region-of-interest method, presumably by decreasing crosstalk from the collecting system. In preliminary trials, the parenchymal transit time did not well separate four obstructed from seventeen unobstructed kidneys, but it successfully (p less than 0.05) separated six transplanted kidneys with acute rejection or acute tubular necrosis from 10 normal transplants.

Algorithms↗
PubMed1989

The kidney: imaging with Tc-99m mercaptoacetyltriglycine, a technetium-labeled analog of iodohippurate.

A new renal imaging agent, technetium-99m mercaptoacetyltriglycine (MAG3, mertiatide), is currently undergoing clinical trials. Like iodine-131 orthoiodohippurate (OIH)--and unlike all other available agents--it is avidly secreted by the renal tubules. Fifty patients underwent simultaneous renal imaging studies with I-131 OIH and Tc-99m MAG3. The superior physical properties of the Tc-99m label led to better image quality in all cases, largely due to count rates that were 50-fold better. In two patients, lesions were seen with MAG3 that were not visible with OIH. The biological properties of the two agents were found to be so similar that conventional diagnostic criteria for I-131 OIH could be used for Tc-99m MAG3 with only minor modifications.

Humans↗
PubMed1989

Measurement of renal function with radionuclides.

For the nuclear physician who wants to measure renal function, the biggest problem may be having to choose among the dozens of methods that have been proposed. An overview will be presented here. The final selection must depend upon the needs of each clinic as well as its technical and financial resources. Except at very low levels of renal function, almost any of these methods can be more reliable than creatinine clearance.

Humans↗
PubMed1988

On the mechanism by which chloride corrects metabolic alkalosis in man.

To determine whether administration of chloride corrects chloride-depletion metabolic alkalosis (CDA) by correction of plasma volume contraction and restoration of glomerular filtration rate or by an independent effect of chloride repletion, CDA was produced in normal men by the administration of furosemide and maintained by restriction of dietary sodium chloride intake. Negative sodium balance (-112 +/- 16 meq) and reduced plasma volume (2.53 versus 2.93 liters, p less than 0.05) developed. The cumulative chloride deficit of 271 +/- 16 meq was then repleted by oral potassium chloride (267 +/- 19 meq) over 36 hours with continued serial measurements of glomerular filtration rate, effective renal plasma flow, plasma volume, body weight, and plasma renin and aldosterone levels. CDA was corrected, even though body weight, plasma volume, glomerular filtration rate, and renal plasma flow all remained reduced and plasma aldosterone was elevated; urinary bicarbonate excretion increased during correction. Administration of an identical potassium chloride load to similarly sodium-depleted but not chloride-depleted normal subjects produced no change in acid-base status. It is concluded that chloride repletion can correct CDA by a renal mechanism without restoring plasma volume or glomerular filtration rate or by altering sodium avidity.

Adult↗
PubMed1978

Radionuclide kidney function evaluation in the management of urolithiasis.

Renal and ureteral stones may cause asymmetrical renal damage that is not measured accurately by serum creatinine and blood urea nitrogen studies, excretory urography, nephrotomography and arteriography. We evaluated with a renal scintillation camera study 77 patients who had renal or ureteral calculi. The radionuclide procedure provided an accurate measure of total effective renal plasma flow and differential effective renal plasma flow. It had the additional advantages of being a non-invasive procedure, causing no allergic reactions, requiring no patient preparation and producing low radiation exposure.

Adult↗