Biomedical subjects

J C Peterson

Publications and source records attributed to J C Peterson.

At least 19 recordsLinked to original sources

PubMed1992

An infant with trisomy 9 mosaicism presenting as a complete trisomy 9 by amniocentesis.

We present a case in which amniocentesis performed at 33 weeks' gestation because of symmetrical intrauterine growth retardation and decreased amniotic fluid volume led to the prenatal diagnosis of a fetus with a karyotype of 47,XX,+9,t(1;20)(q42;p11.2) pat, i.e., with an extra chromosome 9 and a balanced translocation between chromosomes 1 and 20. At delivery, the baby showed clinical features of trisomy 9, yet chromosome analysis of the cord blood revealed no trisomy 9 cells, a finding confirmed by neonatal blood karyotyping. The balanced translocation was present in all cells. A skin biopsy confirmed trisomy 9 mosaicism with 10 per cent trisomy 9 cells. The baby died at 6 weeks and an autopsy was obtained. Chromosome analysis of different organs demonstrated different frequencies of the mosaicism of trisomy 9. The possible underlying mechanism for the discrepancy between the karyotype results by amniocentesis and those of other tissues is discussed.

Adult↗

PubMed1992

Fentanyl and sufentanil increase intracranial pressure in head trauma patients.

Although opioids frequently are administered to patients with severe head trauma, the effects of such drugs on intracranial pressure are controversial. Nine patients with severe head trauma were studied for the effects of fentanyl and sufentanil on intracranial pressure (ICP). In all patients, ICP monitoring was instituted before the study. Full neuromuscular blockade was achieved with vecuronium bromide before the administration of either fentanyl (3 micrograms.kg-1) or sufentanil (0.6 microgram.kg-1) as an intravenous bolus over a 1-min period in a masked and random fashion. Patients received the other opioid in the same fashion 24 h later. Arterial blood pressure, heart rate, and ICP were recorded continuously for the 1 h after drug administration. Fentanyl was associated with an average ICP increase of 8 +/- 2 mmHg, and sufentanil with an increase of 6 +/- 1 mmHg. These increases were statistically significant. Both drugs produced clinically mild decreases in mean arterial blood pressure (fentanyl, 11 +/- 6 mmHg; sufentanil, 10 +/- 5 mmHg) that nevertheless were statistically significant. No significant changes in heart rate occurred. These results indicate that modest doses of potent opioids can significantly increase ICP in patients with severe head trauma.

Adult↗

PubMed1992

Immunosuppression without prophylactic antilymphocyte preparations.

1. Triple-drug immunosuppression following third party transfusion can result in graft survival equal to protocols that employ prophylactic antilymphocyte preparations. 2. T1/2 was statistically improved in cadaveric and living-related donor grafts in the CsA era. 3. Patients 65 years and older had an excessive death rate. Younger groups were admixed. Extreme youth was not a risk factor. 4. Black recipients had excessive late graft loss. 5. Diabetic recipients had only a slight decline in graft and patient survival rates. 6. First and multiple graft recipients had similar transplant survival rates. 7. Delayed graft function remains costly in this immunosuppressive scheme.

Academic Medical Centers↗

PubMed1991

High-performance liquid chromatographic determination of 4,4'-methylenedianiline in human urine.

A method is described for the determination of urinary 4,4'-methylenedianiline (MDA) by high-performance liquid chromatography (HPLC). MDA was extracted from hydrolyzed urine using C18 solid-phase extraction columns. The extract was analyzed by reversed-phase HPLC with electrochemical detection at a cell potential of 0.8 V. The method was very sensitive (detection limit 2.5 micrograms/l) and quantitation using 4,4'-ethylenedianiline as an internal standard correlated well with results by gas chromatography-mas spectrometry. Run-to-run precision (n = 25) averaged 8.9%. In analysis of more than 160 potentially exposed workers, MDA was detected in less than 20% of the urines and concentrations ranged up to 210 micrograms MDA per g of creatinine.

Aniline Compounds↗

PubMed1991

Autonomic control of heart rate during exercise studied by heart rate variability spectral analysis.

Spectral analysis of heart rate variability (HRV) might provide an index of relative sympathetic (SNS) and parasympathetic nervous system (PNS) activity during exercise. Eight subjects completed six 17-min submaximal exercise tests and one resting measurement in the upright sitting position. During submaximal tests, work rate (WR) was increased for the initial 3 min in a ramp fashion until it reached constant WRs of 20 W, or 30, 60, 90, 100, and 110% of the predetermined ventilatory threshold (Tvent). Ventilatory profile and alveolar gas exchange were monitored breath by breath, and beat-to-beat HRV was measured as R-R intervals of an electrocardiogram. Spectral analysis was applied to the HRV from 7 to 17 min. Low-frequency (0-0.15 Hz) and high-frequency (0.15-1.0 Hz) areas under power spectra (LO and HI, respectively) were calculated. The indicator of PNS activity (HI) decreased dramatically (P less than 0.05) when the subjects exercised compared with rest and continued to decrease until the intensity reached 60% Tvent. The indicator of SNS activity (LO/HI) remained unchanged up to 100% Tvent, whereas it increased abruptly (P less than 0.05) at 110% Tvent. The results suggested that (cardiac) PNS activity decreased progressively from rest to a WR equivalent to 60% Tvent, and SNS activity increased only when exercise intensity exceeded Tvent.

Adult↗

PubMed1990

Gallium scan in the diagnosis and treatment of renal malacoplakia.

A middle-aged female was admitted with a presumptive diagnosis of pyelonephritis that failed to respond to conventional antibiotic therapy. Multiple investigations to define the etiology of the persistent fever and accompanying acute renal failure were negative. A gallium scan revealed intense uptake in the renal parenchyma. Percutaneous renal biopsy revealed malacoplakia. Six weeks of therapy with ciprofloxacin resulted in resolution of fever, improvement in the follow-up gallium scan, and reversal of the acute renal failure.

Ciprofloxacin↗

PubMed1990

A prospective evaluation of a simplified captopril test for the detection of renovascular hypertension.

Renovascular hypertension is potentially curable but of low prevalence. A previous retrospective study has demonstrated the use of a potentiated increase in plasma renin activity after captopril administration as a diagnostic test for renovascular hypertension; this requires two blood samples for plasma renin activity determination and three inclusive criteria for a positive test result. We applied this test prospectively to screen 100 hypertensive patients for renovascular hypertension. We evaluated 29 patients with renovascular hypertension; the remainder were diagnosed as having essential hypertension. In our patient population, a postcaptopril plasma renin activity of 5.7 ng of angiotensin per milliliter per hour (ngAl.mL-1.h-1) or greater had a 100% sensitivity and an 80% specificity for renovascular hypertension. An absolute increase in plasma renin activity with captopril of 4.7 ngAl.mL-1.h-1 or greater had a lower sensitivity of 90% and a specificity of 87%, whereas a fractional increase in plasma renin activity after captopril of 150% or higher had the lowest sensitivity of 69% and a specificity of 86%. A subgroup analysis of 38 patients who were receiving diuretic therapy demonstrated that the test sensitivity was unchanged but the specificity was reduced. In conclusion, a single postcaptopril plasma renin activity value of 5.7 ngAl.mL-1.h-1 or greater is a simplified screening test for renovascular hypertension, with excellent sensitivity and acceptable specificity. This test is well tolerated, inexpensive, and easy to perform.

Captopril↗

PubMed1989

Renal transplantation: a 20-year experience at the University of Florida.

Substantial gains have been made in both patient and graft survival during 20 years of transplanting kidneys at the University of Florida. The number of transplant recipients yearly has increased from six in 1966 to more than 100 in 1986. The use of immunosuppression reflects our evolving understanding of transplant immunology, with current morbidity and mortality rates considerably improved over those of the early years. This paper summarizes our transplantation experience over the past two decades.

Adolescent↗

PubMed1989

Incidental and purposeful random donor blood transfusion. Sensitization and transplantation.

We conducted a prospective study to gauge the frequency and degree of sensitization by transfusion and/or pregnancy in 797 candidates for first renal transplants. Sensitization was proportional to the number of blood transfusions. Multiple transfusions or a history of pregnancy without transfusions had similar effects on sensitization. The combination of transfusion and prior pregnancy resulted in sensitization of 1/3 of the candidates. Patients who were not sensitized and were accepted for 1-haplotype living-related donor grafts or first-cadaver donor grafts were transfused to receive a total of 5 units of packed red blood cells. Parous patients had an undue rate of antibody formation and alternate means of selecting and managing parous women are described. Nonparous candidates had a low rate of sensitization (8%) that did not prove an impediment to obtaining a transplant. Only 2% of prospective LRD graft recipients developed antibody against their intended donor. Transplant patients were generally managed with azathioprine and prednisone. One-haplotype LRD graft survival of protocol patients was 93.7% one year posttransplant, and 82.1% at 5 years. One-year CD graft survival was 77%. There was no reduction in graft survival when the interval between transfusion and transplantation exceeded one year. Random donor transfusion is effective in improving renal graft survival. Some recent multiinstitutional reports indicate a reduction or absence of the transfusion effect with current immunosuppression. Discarding blood transfusion as a preparation for transplantation may be ill-advised pending a prospective study.

Blood Transfusion↗

PubMed1988

Loss of corticomedullary demarcation on magnetic resonance imaging: an index of biopsy-proven acute renal transplant dysfunction.

A prospective study of 19 cadaveric renal allograft recipients with suspected graft rejection was undertaken to compare the histological findings of the renal transplant biopsy with the results of magnetic resonance imaging (MRI). All 19 patients underwent a biopsy of the transplant allograft. Biopsy results included acute cellular rejection, acute vascular rejection, chronic vascular rejection (CVR), and acute tubular necrosis (ATN). Recipients of cadaveric renal allografts with normal function served as controls. The control showed distinct corticomedullary demarcation (CMD) on T1-weighted imaging. In contrast, CMD was absent or diminished in all the patients with suspected allograft rejection. Unfortunately, the loss of CMD did not correlate with a specific biopsy diagnosis. Patients with biopsy evidence of acute and chronic rejection or ATN demonstrated loss of CMD with similar image patterns. In conclusion, MRI is capable of detecting renal allograft dysfunction, but does not permit the determination of a specific cause.

Adult↗

PubMed1988

Late results of renal transplantation.

A total of 315 (64%) of 491 primary cadaver and living-related donor transplants performed from 1975 through 1984 were still functioning at 24 months. These selected patients were examined further to assess the impact of several risk factors on late graft and patient survival. Black recipients, patients with underlying diabetes mellitus or hypertension, patients with poor renal function at 24 months, and recipients of cadaver grafts had significantly poorer long-term graft survival. Age greater than or equal to 40, diabetes or hypertension, poor 24-month function, and cadaver donor transplantation were associated with poorer long-term patient survival. Considerable improvement in graft survival at 24 months was seen in 1980-1984 compared with the earlier period, coincident with our adoption of routine pretransplant random donor blood transfusion. In contrast, long-term graft survival in patients with functioning graft at two years did not improve significantly over the same period. Although living-related donor transplants showed greater graft and patient survival than cadaver donor grafts by univariate analysis, no such advantage was demonstrated by multivariate analysis.

Actuarial Analysis↗

PubMed1988

Extracorporeal shock-wave lithotripsy: long-term complications.

Of 148 patients who had extracorporeal shock-wave lithotripsy (ESWL) for renal lithiasis in 1984, 21 (14%) returned after 17-21 months for renal function tests (21 patients) and blood pressure determination (20 patients). Quantitative radionuclide renography showed a statistically significant (p = .048) decrease in the percentage of effective renal plasma flow (ERPF) to the treated kidney. Two of these patients had developed hypertension requiring treatment but became normotensive when given medication. In the other patients there was a statistically significant increase in both systolic (p = .0002) and diastolic (p = .015) blood pressures. Information about blood pressure was also obtained from an additional 71 (48%) of the 148 patients; of the total 91 patients (61%) in whom blood pressures were obtained, seven (8%) had developed sufficiently severe hypertension to require treatment beginning within 21 months after ESWL. Side effects of ESWL for renal lithiasis include hemorrhage, edema, and acute tubular necrosis of the kidney. This form of renal trauma is associated with an immediate decrease in renal function of the treated kidney, and this decrease may be permanent. ESWL is also associated with the onset of hypertension, which may occur immediately or be delayed by several weeks or months. Although the pathogenesis remains unknown, hypertension is an important complication of ESWL in about 8% of patients.

Adult↗

PubMed1986

Chronic continuous PTH infusion results in hypertension in normal subjects.

The factors responsible for the frequent occurrence of hypertension in patients with primary hyperparathyroidism have not been elucidated. Suggested mediators have included hypercalcemia, renal insufficiency, and increased plasma renin activity. However, experimental results have not been reported in any species that test the hypothesis that sustained hypertension in this clinical syndrome is due to consequences of parathyroid hormone (PTH) excess versus unrelated factors (e.g., primary hypersecretion of other hormones, NaCl sensitivity, genetic factors). Moreover, no systematic evaluation of the renin or adrenal cortical responses to chronic PTH excess has been reported in any species. Accordingly, the present studies assessed the effects of chronic (12 days) continuous intravenous b-(1-34) PTH infusion in normal human subjects (n = 4). PTH infusion resulted in persistent hypercalcemia and hypertension, reversible during a 4-8-day recovery period. Transient but significant increases in urinary tetrahydroaldosterone excretion and plasma cortisol concentration were observed as hypercalcemia and hypertension developed. No significant changes in plasma potassium concentration or plasma renin activity were observed, suggesting that hypercalcemia-induced transient hypersecretion of ACTH was responsible for both cortisol and aldosterone responses. The present results suggest that hypertension associated with clinical primary hyperparathyroidism results from either direct or indirect effects of PTH excess, per se, and requires neither the long-term consequences/complications of the clinical disorder (e.g., severe nephrocalcinosis, renal insufficiency) nor primary hypersecretion of additional hormones. These results are consistent with the hypothesis that hypercalcemia alone or in combination with at least permissive levels of PTH can generate short-term, but persistent (12 days) hypertension in human subjects and thus may be the initiating mechanism for hypertension in clinical primary hyperparathyroidism.

Adult↗

PubMed1985

Acid-base homeostasis during chronic PTH excess in humans.

The chronic renal and systemic acid-base effects of hyperparathyroidism in humans remain controversial and unresolved. The present studies evaluated the acid-base response of normal human subjects to a 13-day intravenous infusion of synthetic b(1-34) PTH sufficient to result in sustained hypercalcemia and hypophosphatemia. The acid-base response was biphasic: an initial transient renal acidosis developed on the first day of PTH infusion, followed by a prompt increase in net acid excretion and plasma [HCO3-] of sufficient magnitude to result in a steady state of mild metabolic alkalosis. The results indicate that: 1) sustained, continuous, experimentally produced hyperparathyroidism results in a steady state of mild metabolic alkalosis; 2) the alkalosis is both generated and maintained, at least in part, by renal mechanisms; and 3) reported renal acidosis in sustained clinical conditions of primary hyperparathyroidism is not attributable to either direct or indirect effects of PTH excess when present for a 2-week period, an interval sufficient to re-establish a new steady state of renal and systemic acid-base equilibrium.

Acid-Base Equilibrium↗

PubMed1985

Renal carcinoma and dialysis in end-stage renal disease.

We describe five patients receiving long-term hemodialysis (mean duration of 6.4 years) in whom eight renal carcinomas were found. In four patients, the carcinoma was confirmed by tissue pathology, while the fifth patient had multiple (four) areas of neovascularity on selective renal arteriography. Two patients died of metastases. In four patients the diagnosis was initially made with selective renal arteriography and in the remaining one, with sonography and computerized tomography. In three of the four arteriography showed diffuse cystic degeneration; pathologic findings revealed renal carcinoma and the changes of "end-stage" disease. Two patients had brief pharmacologic immunosuppression during unsuccessful renal transplantation six years earlier. These cases demonstrate an apparently increased risk of renal carcinomas in end-stage renal disease, a risk that appears to be independent of pharmacologic immunosuppression.

Adult↗

PubMed1985

Long-term control of plasma calcitriol concentration in dogs and humans. Dominant role of plasma calcium concentration in experimental hyperparathyroidism.

Despite great interest in the elevated circulating levels of calcitriol (1,25-[OH]2D) associated with the clinical syndrome of human primary hyperparathyroidism, the relative potencies of known and potential stimuli/suppressors of long-term calcitriol levels have not been evaluated in either clinical or experimentally induced hyperparathyroid states. Based on reports that aparathyroid animals exhibit suppressed plasma calcitriol concentration and that acute administration of parathyroid hormone (PTH) to both humans and experimental animals or to renal slices in vitro results in increased plasma calcitriol concentration/production rate, it might be predicted that a chronic experimental model of either hypercalcemic primary hyperparathyroidism or hypocalcemic secondary hyperparathyroidism would show increased plasma calcitriol concentration. Chronic alterations in plasma calcium concentration have not been implicated as modulating calcitriol levels in any species. Accordingly, we investigated the long-term response of plasma calcitriol concentration in states of sustained experimental primary and secondary hyperparathyroidism. Intact dogs (group I) undergoing continuous intravenous PTH infusion for 12 d developed sustained hypercalcemia and hypophosphatemia, and plasma calcitriol concentration decreased from 23 +/- 3 to 14 +/- 3 pg/ml (P less than 0.01). Subsequent chelator (EGTA)-induced chronic normalization of hypercalcemia during ongoing PTH infusion resulted in a large and sustained increase in plasma calcitriol concentration to supernormal levels, reversible during subsequent cessation of chelator infusion. In additional intact dogs (group II), chronic chelator-induced hypocalcemic secondary hyperparathyroidism resulted in a sustained increase in plasma calcitriol concentration despite hyperphosphatemia. In normal human subjects undergoing a 12-13-d continuous intravenous PTH infusion to result in sustained moderate hypercalcemia (12.0 +/- 0.2 mg/100 ml) and hypophosphatemia, plasma calcitriol concentration decreased significantly (P less than 0.01) as in group I dogs and was followed by reversal to normal levels in a recovery period. The present results provide strong evidence in both humans and dogs that during experimentally induced chronic PTH excess, alterations in plasma calcium concentration dictate the directional response of circulating calcitriol concentrations. The long-term potency of plasma calcium concentration as a modulator of calcitriol metabolism is sufficient to override opposing modulation by plasma phosphorus concentration and PTH.

25-Hydroxyvitamin D 2↗

PubMed1984

Renal and systemic magnesium metabolism during chronic continuous PTH infusion in normal subjects.

Renal and systemic magnesium metabolism has not been adequately characterized in states of prolonged PTH excess in humans. Whereas acute experimental PTH administration uniformly results in enhanced renal magnesium reabsorption in many species, including humans, numerous clinical reports have documented renal magnesium wasting in human primary hyperparathyroidism. The possibility has been raised, therefore, that secondary consequences of sustained hyperparathyroidism (eg, hypercalcemia, nephrocalcinosis) might override the direct renal effects of PTH. Accordingly, the present studies assessed the effects of chronic (12 days) continuous intravenous (IV) b-(1-34)-PTH infusion in four normal human subjects on plasma, urinary, and intestinal magnesium and calcium homeostasis under metabolic balance conditions. Chronic PTH infusion resulted in a steady-state of hypercalcemia, hypercalciuria, and persistent negative calcium balance, which returned to baseline values in a recovery period. In contrast to plasma calcium concentration, plasma magnesium concentration was not altered by PTH infusion. Significant hypermagnesuria was observed during the period of PTH administration (control, 8.21 +/- 0.43 mEq/24 hours; PTH days 7-12, 10.75 +/- 0.74 mEq/24 hours, P less than 0.05) resulting in an initial, but transient, negative magnesium balance. During days 7-12 of PTH administration, net intestinal magnesium absorption increased sufficiently to result in a return to control magnesium balance. These findings suggest that hypermagnesuria associated with clinical primary hyperparathyroidism results from either direct or indirect effects of PTH excess, per se, and does not require the long-term consequences or complications of the clinical disorder (eg, nephrocalcinosis, renal insufficiency, acidosis).

Adult↗

PubMed1984

Variations of phthalate ester concentrations in sediments from the Chester River, Maryland.

Phthalate esters discharged from a plasticizer-manufacturing plant were distinguished from those of other sources in the Chester River, Maryland by comparing the distinctive patterns of alkyl phthalate species of the plant to those of sediment samples from sites along the mid-river axis. The magnitude of the changes in individual phthalate species were placed in perspective by charting their concentrations with distance along the river. Short sediment cores were also analyzed to determine the profile of phthalate ester pollution in the Chester River during the previous decade in which the river experienced a significant oyster mortality. A significant level of phthalate ester pollution was found in the Chester River sediment but its source was not found to be the plasticizer plant.

Dibutyl Phthalate↗