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.

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.

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).

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.

Comparative pharmacokinetics of theophylline in peritoneal dialysis and hemodialysis

Dialysis clearance and drug recovery of theophylline were investigated in three peritoneal dialysis patients and the results were compared with those obtained from five hemodialysis patients. Peritoneal clearance averaged 9.5 ml/min, in contrast with the hemodialysis clearance of 84.8 ml/min, indicating a relative inefficiency of peritoneal dialysis with regard to theophylline removal. Theophylline half-life was reduced substantially during hemodialysis, 2.0 to 3.2 hours, in comparison with the normal half-life range of 4.7 to 6.8 hours during peritoneal dialysis. The fraction of theophylline recovered by peritoneal dialysis approximated 3.2 per cent of dose, while hemodialysis recovered up to 40 per cent of the administered dose. The overall observations of half-life, dialysis clearance, and drug recovery suggest a clear advantage of hemodialysis over peritoneal dialysis for theophylline detoxification. However, peritoneal dialysis may be preferred to hemodialysis for uremic patients requiring theophylline therapy. Since the removal of theophylline by peritoneal dialysis is minimal, an undesirable alteration of the theophylline dosage regimen in association with dialysis therapy can thus be avoided.

A strategy for source identification of organic pollutants in river water

Sources of organic pollution in the Oise river, France have been identified using a "mutual search" strategy. This consisted of searching the characterized discharges for compounds found in the river water and, conversely, searching river water extracts for compounds found in the discharges. The "matches" were facilitated by comparisons of retention indices on two capillary gas chromatographic columns of widely differing polarity, response factors of selective detectors, and mass spectra. These assignments were verified by the geographical correlation of the selected pollutant's point of appearance in the river with the location of the suspected source.

Severe hypernatremia complicating urinary tract obstruction

Severe hypernatremia and hyperosmolar dehydration developed in a patient with partial urinary tract obstruction. The urine was initially hypotonic, and there was no response to exogenous vasopressin. These abnormalities resolved with relief of the urinary tract obstruction and replacement of the water deficit. This case documents lower urinary tract obstruction as a cause of nephrogenic diabetes insipidus and severe hypernatremia and illustrates its reversible nature.

Water vapor-nitrogen absorption at CO(2) laser frequencies

In this paper we report the results of a series of pressure-broadened water vapor absorption measurements at 27 CO(2) laser frequencies between 935 cm(-1) and 1082 cm(-1). Both multiple traversal cell and optoacoustic (spectrophone) techniques were utilized together with an electronically stabilized cw CO(2) laser. Comparison of the results obtained by these two methods shows remarkable agreement, indicating a precision which has not been previously achieved in pressure-broadened studies of water vapor. The data of 10.59 microm substantiate the existence of the large (>200) self-broadening coefficients determined in an earlier study by McCoy. In this work we have treated the case of water vapor in N(2) at a total pressure of 1 atm. We have also studied water vapor in air and will report those results separately.

Reversible depression in myocardial performance in dogs with experimental phosphorus deficiency

The effects of phosphorus depletion on cardiac muscle function in six awake dogs were evaluated with surgically implanted transducers to serially measure ascending aortic root blood flow and high fidelity left ventricular pressure. After the animals recovered from surgery, phosphorus depletion was induced by feeding them a synthetic phosphorus-deficient diet plus aluminum carbonate gel for 35 days, followed by the same diet with phosphorus supplementation for 21 days. In addition to the cardiac studies, sequential measurements of phosphorus content in skeletal muscle and phosphorus in serum were obtained to ascertain the level of phosphorus depletion. Serum inorganic phosphorus concentration (mg/100 ml) decreased from 5.1 +/- 0.1 on day 0 to 0.9 +/- 0.1 on day 35 (P less than 0.01), and total muscle phosphorus (content mmul/100 g fat-free dry weight) decreased from 28.0 +/- on day 0 to 22.6 +/- 0.5 on day 35 (P less than 0.01). During the period of phosphorus depletion, there was no significant change in heart rate; however, stroke volume (milliliter) and peak blood flow velocity (centimeter per second) declined from 24 +/- 2 to 17 +/- 2 (P less than 0.01) and 121 +/- 12 to 98 +/- 7 (P less than 0.01), respectively. Maximum ascending aortic blood flow acceleration (centimeter per second square) and maximum left ventricular time rate of change of pressure (mm Hg per second) also decreased from 4,630 +/- 313 to 3,817 +/0 346 (P less than 0.01) and 2,582 +/- 347 to 2,120 +/- 297 (P less than 0.01) during phosphorus depletion. After repletion all values returned to control values. These results indicate that moderate diet-induced phosphorus depletion can depress myocardial performance. With repletion of phosphorus, myocardial performance improves.

Effects of oxygen addition on pressure-broadened water-vapor absorption in the 10-microm region

We have measured the monochromatic transmittances of pressure-broadened room-temperature water vapor samples at five laser frequencies of the CO(2) laser in the 10.4-microm band. Three different buffer gases were used. They were pure nitrogen, an 80:20 mixture of nitrogen and oxygen, and a 60:40 mixture of nitrogen and oxygen. The measurements at the five laser lines imply that oxygen is a less efficient broadener than nitrogen. The ratio of the oxygen-broadening coefficient to the nitrogen-broadening coefficient was measured to be 0.75 based on the data at the R(20) laser line. Results of this study demonstrate that pure nitrogen should not be used as a broadener for atmospheric modeling of monochromatic transmittances in the laboratory.

Enzymatic activities leading to pyrimidine nucleotide biosynthesis from cell-free extracts of Rickettsia typhi

Cell-free extracts from Rickettsia typhi were examined for the presence or absence of pyrimidine phosphotransferase enzymes and compared with the enzymes of mouse L cells and Salmonella typhimurium. The organisms were grown in mouse L cells and in the yolk sacs of chicken embryos, purified by Renografin density gradient centrifugation, and ruptured in a French pressure cell. The enzymes for the reutilization of uridine and thymidine, uridine kinase (EC 2.7.1.48) and thymidine kinase (EC 2.7.1.21), were not detected in R. typhi extracts with the phosphate donors effective for control enzymes. The following enzyme activities were demonstrated in R. typhi: uridine-5'-monophosphate kinase (UMPK, EC 2.7.4.4), deoxythymidine-5'-monophosphate kinase (dTMPK, EC 2.7.4.9), and nucleosidediphosphate kinase (NDPK, EC 2.7.4.6). Physicochemical and enzymatic analyses demonstrated that the pyrimidine nucleotide kinases of R. typhi were not of host origin and that the source (yolk sac and mouse L cells) did not influence the relative enzymatic activities. The specific activities of UMPK and dTMPK were higher when the rickettsiae were harvested before embryo death, whereas NDPK levels were slightly decreased. The specific activities of UMPK, dTMPK, and NDPK were comparable to those of S. typhimurium, and consequently the rickettsiae have potential for the anabolism of monophosphates, as do the host-independent bacteria. These results suggest that R. typhi cannot utilize host uridine or thymidine pools directly but must rely on themonophosphorylated molecules of the host cell or must synthesize the monophosphates de novo.

Whipple's Disease: Its Relationship to the Rheumatic State

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