Modulatory Role of Gamma-Aminobutyric Acid (GABA) in the Regulation of Gonadotropin Secretion in Patients with Chronic Renal Failure

The role of gamma-aminobutyric acid (GABA) in the regulation of gonadotropin secretion in renal failure, was studied in 5 patients with chronic renal failure who were on maintenance dialysis. Di-n-propylacetic acid (valproic acid-VA), a GABA-transaminase inhibitor which has been shown to increase brain GABA levels, was used in the study.

VA produced no significant change in the basal serum LH and FSH concentrations, or in E2 or T concentrations in the renal failure patients, or the E2 and P concentrations in normal controls, but augmented the Δ LH (maximum increment above baseline) and Δ FSH response to LHRH. Δ LH rose from 30.4 ± 12.7 mlU/ml ([Formula: see text]) to 41.1 ± 16.8 mlU/ml (p < 0.01) after VA, while Δ FSH rose from 2.8 ± 1.8 mlU/ml to 3.8 ± 1.6 mlU/ml (p < 0.05). The findings support a modulatory role for GABA in gonadotropin secretion in chronic renal failure.

Parasites as drivers of key processes in aquatic ecosystems: Facts and future directions

Despite the advances in our understanding of the ecological importance of parasites that we have made in recent years, we are still far away from having a complete picture of the ecological implications connected to parasitism. In the present paper we highlight key issues that illustrate (1) important contributions of parasites to biodiversity, (2) their integral role in ecosystems, (3) as well as their ecological effects as keystone species (4) and in biological invasion processes. By using selected examples from aquatic ecosystems we want to provide an insight and generate interest into the topic, and want to show directions for future research in the field of ecological parasitology. This may help to convince more parasitologists and ecologists contributing and advancing our understanding of the complex and fascinating interplay of parasites, hosts and ecosystems.

Zur Bildung von He2 + und Ne2 + in der stationären positiven Niederdrucksäule

Mit einer kürzlich beschriebenen Apparatur (Entladungsrohr mit angeschlossenem Massenspektrometer) werden Ioneneffusionsströme aus der stationären positiven Säule in He- und Ne-Glimm-entladungen gemessen. Der Effusionsstrom einer bestimmten lonensorte ist proportional zu deren Bildungsgeschwindigkeit im Plasma. Die Bildungsraten von He2 +/He+ und Ne2 +/Ne+ werden in Abhängigkeit vom Totaldruck (0,1 —5 Torr) angegeben und die Meßkurven diskutiert.

Massenspektrometrische Untersuchungen an der positiven Säule in Ar, Ar-He- und Ar-H2-Gemischen

Im Druckbereich 0,05 — 1,2 Torr wird mittels einer früher schon mitgeteilten Effusionsmethode die Ionenbildung in der stationären positiven Niederdrucksäule untersucht. Verbesserungen der Meßmethode werden beschrieben und Fehlerquellen diskutiert. In reinem Argon ergibt sich für den HORNBECK—MOLNAR-Prozeß Ar′ +Ar → Ar2 ++e- ein Wert τ k=0,84·10-16 cm3 in befriedigender Übereinstimmung mit Ergebnissen in der konventionellen Elektronenstoßkammer. Sichere Anzeichen für einen trimolekularen Prozeß Ar++2 Ar → Ar2 ++Ar werden nicht gefunden. Die Suche nach He Ar+ hatte keinen Erfolg. In Ar—H2-Gemischen wurden die Reaktionen Arm+H → Ar H+ +e- sowie Ar H++ H2 → H3 ++Ar sichergestellt. Ein Gesamt-Reaktionsschema wird diskutiert.

Zur Bildung von Molekülionen in stationären Edelgasentladungen

Im Anschluß an kürzlich beschriebene massenspektrometrische Messungen von Ionen-Effusionsströmen aus der stationären positiven Niederdruck-Säule in He und Ne werden nach gleicher Methode gewonnene neue Resultate beim Argon mitgeteilt. Während beim He und Ne die gemessenen Effusionsströme der Atomionen X⁺ im wesentlichen den Erwartungen der SCHOTTKYSCHEN Theorie der ambipolaren Diffusion entsprechen, werden beim A kleinere Werte gefunden. Die Bildungsrate X2 +/X+ in Abhängigkeit vom Druck ist in He und Ne annähernd gleich, in A ist sie erheblich größer. Aus den Meßergebnissen geht hervor, daß in der stationären positiven Säule (p ≦ 5 Torr) die Bildung der Molekülionen X2⁺ vorwiegend nach dem von HORNBECK und MOLNAR bei niedrigeren Drucken gefundenen Prozeß X′+ X → X2 ++e stattfindet.

Über die Stabilität organischer Moleküle bei Elektronenstoß

Aus den Daten des „Catalog of Mass Spectral Data“ werden die Werte für die Zerfalls-Wahrscheinlichkeit Wz bei Elektronenstoß und für den „mittleren Frakturquotienten“ Q̄B aller bis zum 30. 6. 1952 untersuchten organischen Moleküle berechnet und in Kurven- oder Tabellenform mitgeteilt. Es ergibt sich dabei eine deutliche Systematik der Stabilität gegen Elektronenstoß im Zusammenhang mit der Molekülstruktur. Der Einfluß verschiedener Substituenten auf die Stabilität zeigt eine deutliche Parallele zu emissionsspektroskopischen Ergebnissen von Schüler und Mitarbeitern.

Über die Stabilität der geraden Alkohole, Mercaptane und Alkylbenzole bei Elektronenstoß

Aus den Angaben des „Catalog of Mass Spectral Data“ wird empirisch eine quantitative Beziehung zwischen der Stabilität der Mutterionen (WM) und der Anzahl der Bindungs- Elektronen ζ des Alkylrestes gefunden. Sie lautet im Falle der S-Alkohole WM · ζ = const und hat bei den Alkylbenzolen dieselbe Form, wenn hierbei WM nur auf den Zerfall des Alkylrestes ohne die Ringaufspaltung bezogen wird. Bei den Alkanen und O-Alkoholen nimmt WM rascher ab, etwa mit WM · ζ2 = const′. Die Stabilität WM hängt nicht mit der Form der Massenspektren zusammen, sondern ist offenbar bestimmt durch einen Prozeß, der innerhalb ≦10-14 sec das gesamte System der Bindungs-Elektronen im Molekül erfaßt.

Zur Massenspektrometrie an Glimmentladungen

Der Anschluß eines richtungsfokussierenden 60°-Massenspektrometers an die stationäre positive Niederdruck-Säule zum Zwecke quantitativer Messungen von Ionenstromraten wird beschrieben. Die lonengewinnung aus dem Plasma erfolgt durch ambipolare Effusion. Ionen, die stark verschiedene Beweglichkeiten besitzen, effundieren nicht mit gleicher Energie. Mittels einer Gegenfeldmethode werden solche Energiedifferenzen festgestellt und gemessen zwischen Ne+—Ne2 +, Ne+ —NeH+, He+—He2 +. Die Isotope des Neons haben innerhalb der erreichten Meßgenauigkeit gleiche Energie. Eine quantitative Abschätzung zeigt, daß Volumen-Rekombinationsprozesse unter den gewählten Bedingungen in He und Ne noch nicht merkbar werden.

Ambipolare Effusion aus der positiven Säule

Durch eine ideale Kreislochblende in der nichtleitenden Wand eines Entladungsgefäßes effundieren die Ladungsträger aus der stationären positiven Säule ambipolar zusammen mit dem neutralen Gas in ein anschließendes Hochvakuum. Im Hinblick auf die massenspektrometrische Analyse der Ladungsträger wird versucht, theoretisch die Frage zu klären, inwieweit die Messung der Effusionsströme verschiedener Ionenarten eine Aussage über die relativen Trägerkonzentrationen im Plasma erlaubt. Ausgehend von der ScHOTTKYSchen Theorie der positiven Säule und ihrer Erweiterung von SPENKE um die „quadratische“ Ionisierung werden zunächst Gleichungen für den Betrag des Effusionsstromes abgeleitet, die experimentell geprüft werden können. Sodann wird die Diffusionstheorie erweitert durch Einbezug der quadratischen Volumen-Rekombination und endlicher Trägerdichten vor der Wand.

Die theoretisch möglichen Trägerdichteverteilungen ergeben sich aus den Lösungen der Differentialgleichung (13)

D[n″(r) +1/r·n′(r)] +η n(r) + (ϰ—a) n2(r) = 0

mit den Anfangsbedingungen n(0) =n0 und n′(0) =0 sowie verschiedenen — als experimentell bestimmbar angesehenen — Randwerten n (R)/n0. Für die Wand (Effusions) -Stromdichten werden, ausgehend von der gewonnenen Dichteverteilungsfunktion, auf zwei Wegen äquivalente Gleichungen [ (27) und (30)] abgeleitet. Zuletzt werden noch einige Effekte an der nichtidealen Lochblende diskutiert, die Abweichungen von der Theorie hervorrufen können.

Der Einfluß von Zweierstößen auf die molekulare Gasströmung

Die im I. Teil entwickelte Näherungsmethode, die Kinetik relativ seltener Zweierstöße in molekularen Strömungen zu behandeln, wird in geeigneter Abwandlung auf weitere Formen von Strömungswiderständen ausgedehnt: Spaltkanal zwischen ebenen, parallelen Platten, kreisrunde Lochblende, kurze Röhre sowie poröse Medien. Der Leitwert F eines Spaltkanals nimmt (im molekularen Strömungsbereich) mit zunehmendem Gasdruck p viel stärker ab als der einer langen Röhre; dagegen ergibt sich bei der Lochblende eine lineare Zunahme von F mit p. Beide Ergebnisse stimmen mit Messungen von Gaede14 bzw. Knudsen30 überein. Bei kurzen Röhren und bei geknickten Röhren mit kurzer Teilstücklänge ist stets lineare Druckabhängigkeit für F gegeben; Vorzeichen und Betrag des Proportionalitätsfaktors hängen jedoch in empfindlicher Weise vom Verhältnis Röhrenlänge/Durchmesser ab. Die voneinander abweichenden Meßwerte verschiedener Autoren für diesen Proportionalitätsfaktor bei der molekularen Durchströmung von porösen Medien lassen sich demnach auf Unterschiede in der Porenstruktur zurückführen.

Sonographic reproducibility of a novel approach in the assessment of centralised access in end-stage renal disease

A reliable and accurate non-invasive test is needed to help determine grafts and/or fistulae in end-stage renal disease (ESRD) patients. Sonographic scanning to assess the state of the fistula and AV shunt seems underused. To find out what role B-mode and Doppler play in the assessment of fistula and shunt, we scanned nine patients with a fistula as central access and nine patients with a graft several times over a period of a month. Diameters were measured before and after the AV shunt and Doppler measurements were made pre, inter and post shunt. We established that B-mode measurements are reliable in predicting the future and integrity of both fistulae and grafts. Doppler measurements were less consistent and therefore less reliable. The average initial measurement showed a screen of 5.766 mm and a second measurement of 5.890 mm; The coefficient of variation (CV)/reproducibility was 1.58% for first measurement. The average first and second measurements post graft were 6.317 mm and 6.365 mm, respectively. The CV/reproducibility was 0.48%. First and second peak flow measurements averaged 149 m/s and 112 m/s, respectively, resulting in a CV of 14.0%. We conclude that morphological changes may be more reliable than Doppler values, indicating a potentially greater use for B-mode ultrasound in predicting an open shunt and/or fistula.

A randomized clinical trial of continuous versus intermittent dialysis for acute renal failure

BACKGROUND

Acute renal failure (ARF) requiring dialysis in critically ill patients is associated with an in-hospital mortality rate of 50 to 80%. The worldwide standard for renal replacement therapy is intermittent hemodialysis (IHD). Continuous hemodialysis and hemofiltration techniques have recently emerged as alternative modalities. These two therapies have not been directly compared.

METHODS

A multicenter, randomized, controlled trial was conducted comparing two dialysis modalities (IHD vs. continuous hemodiafiltration) for the treatment of ARF in the intensive care unit (ICU). One hundred sixty-six patients were randomized. Principal outcome measures were ICU and hospital mortality, length of stay, and recovery of renal function.

RESULTS

Using intention-to-treat analysis, the overall ICU and in-hospital mortalities were 50.6 and 56.6%, respectively. Continuous therapy was associated with an increase in ICU (59.5 vs. 41.5%, P < 0.02) and in-hospital (65.5 vs. 47.6%, P < 0.02) mortality relative to intermittent dialysis. Median ICU length of stay from the time of nephrology consultation was 16.5 days, and complete recovery of renal function was observed in 34.9% of patients, with no significant group differences. Despite randomization, there were significant differences between the groups in several covariates independently associated with mortality, including gender, hepatic failure, APACHE II and III scores, and the number of failed organ systems, in each instance biased in favor of the intermittent dialysis group. Using logistic regression to adjust for the imbalances in group assignment, the odds of death associated with continuous therapy was 1.3 (95% CI, 0.6 to 2.7, P = NS). A detailed investigation of the randomization process failed to explain the marked differences in patient assignment.

CONCLUSIONS

A randomized controlled trial of alternative dialysis modalities in ARF is feasible. Despite the potential advantages of continuous techniques, this study provides no evidence of a survival benefit of continuous hemodiafiltration compared with IHD. This study did not control for other major clinical decisions or other supportive management strategies that are widely variable (for example, nutrition support, hemodynamic support, timing of initiation, and dose of dialysis) and might materially influence outcomes in ARF. Standardization of several aspects of care or extremely large sample sizes will be required to answer optimally the questions originally posed by this investigation.

Nephrotic syndrome associated with Kimura disease

Kimura disease presents as benign subcutaneous swelling predominantly around the head and neck region. It has a high incidence of renal involvement. However, the pathogenesis of this association remains elusive. Only 2 pediatric cases and 11 adult cases of Kimura disease with renal involvement have been reported in the literature. In recent years many immunopathogenetic features suggesting an underlying T-cell and related cytokine defect have been noted in Kimura disease. We describe a unique case of an Asian boy who presented with nephrotic syndrome resistant to steroid and cytotoxic therapy, and 5 years later developed cervical lymphadenopathy consistent with Kimura disease. We also review the literature, summarizing the presentation, differential diagnosis, incidence of renal disease, prognosis, immunopathogenetic features, and therapy.

Effect of a low calcium dialysate on parathyroid hormone secretion in diabetic patients on maintenance hemodialysis

Diabetic patients on maintenance dialysis often are characterized by a relative parathyroid hormone (PTH) deficiency and a form of renal osteodystrophy with low bone turnover known as adynamic bone. The goal of the present study was to determine whether a reduction in the dialysate calcium concentration would increase the predialysis (basal) PTH and maximal PTH level. Thirty-three diabetic maintenance hemodialysis patients with basal PTH values less than 300 pg/ml were randomized to be dialyzed with either a regular (3.0 mEq/liter or 3.5 mEq/liter, group I) or low (2.25 mEq/liter or 2.5 mEq/liter, group II) calcium dialysate for 1 year. At baseline and after 6 months and 12 months of study, low (1 mEq/liter) and high (4 mEq/liter) calcium dialysis studies were performed to determine parathyroid function. At baseline, basal (I, 126+/-20 vs. II, 108+/-19 pg/ml) and maximal (I, 269 pg/ml+/-40 pg/ml vs. II, 342 pg/ml+/-65 pg/ml) PTH levels were not different. By 6 months, basal (I, 98+/-18 vs. II, 200+/-34 pg/ml, p = 0.02) and maximal (I, 276 pg/ml+/-37 pg/ml vs. II, 529 pg/ml+/-115 pg/ml; p = 0.05) PTH levels were greater in group II. Repeated measures analysis of variance (ANOVA) of the 20 patients who completed the entire 12-month study showed that only in group II patients were basal PTH (p = 0.01), maximal PTH (p = 0.01), and the basal/maximal PTH ratio (p = 0.03) different; by post hoc test, each was greater (p < 0.05) at 6 months and 12 months than at baseline. When study values at 0, 6, and 12 months in all patients were combined, an inverse correlation was present between basal calcium and both the basal/maximal PTH ratio (r = -0.59; p < 0.001) and the basal PTH (r = -0.60; p < 0.001). In conclusion, in diabetic hemodialysis patients with a relative PTH deficiency (1) the use of a low calcium dialysate increases basal and maximal PTH levels, (2) the increased secretory capacity (maximal PTH) during treatment with a low calcium dialysate suggests the possibility of enhanced parathyroid gland growth, and (3) the inverse correlation between basal calcium and both the basal/maximal PTH ratio and the basal PTH suggests that the steady-state PTH level is largely determined by the prevailing serum calcium concentration.

Parinaud syndrome caused by Bartonella henselae: case report

The authors report a case of Parinaud syndrome (conjunctivitis with pre-auricular satellite adenitis) caused by Bartonella henselae, the etiologic agent of Cat Scratch Disease. The etiologic assessment of this case was performed by serum indirect immunofluorescence reaction and allowed for a better therapeutics and follow up, avoiding ineffective antibiotics and surgical interventions.

The set point of calcium and the reduction of parathyroid hormone in hemodialysis patients

Since in some studies in hemodialysis patients calcitriol treatment has resulted in a reduction of both parathyroid hormone (PTH) levels and the set point of calcium, it has been suggested that that the set point of calcium reflects a reduction in the magnitude of hyperparathyroidism. However, others have maintained that the set point of calcium is primarily an indicator of the serum calcium at which PTH is secreted and may be dissociated form the magnitude of hyperparathyroidism. The present study was designed to evaluate how a reduction in PTH levels associated with an increase in the predialysis (basal) serum calcium would affect the set point of calcium. Two different treatments were used to produce a reduction in PTH that was associated with an increase in predialysis serum calcium. In the first group, hemodialysis patients received 2 micrograms of intravenous calcitriol and were dialyzed with a 3.5 mEq/liter calcium dialysate for six weeks; in the second group, hemodialysis patients were dialyzed with a 4 mEq/liter calcium dialysate and had oral calcium supplementation increased for six weeks. In both groups, low and high calcium studies were performed to determine the PTH-calcium relationship before treatment, at the end of six weeks of treatment, and six weeks after the discontinuation of treatment. In the calcitriol group the predialysis calcium increased form 9.62 +/- 0.34 to 10.56 +/- 0.31 mg/dl, P < 0.05 and the set point of calcium increased from 9.34 +/- 0.23 to 9.79 +/- 0.25 mg/dl, P < 0.05 at the same time as maximally stimulated PTH decreased from 2637 +/- 687 to 1555 +/- 617 pg/ml, P < 0.05. In the high calcium dialysate group, the predialysis serum calcium increased from 9.19 +/- 0.31 to 9.84 +/- 0.28 mg/dl, P < 0.05, and set point of calcium increased form 9.01 +/- 0.28 to 9.39 +/- 0.22 mg/dl, P < 0.05 at the same time as maximally stimulated PTH decreased from 1642 +/- 450 to 1349 +/- 513 pg/ml, P < 0.05. Discontinuation of treatment for six weeks resulted in a return to pretreatment values. In conclusion, our results would suggest that (1) the set point of calcium may not be a reliable indicator of the magnitude of hyperparathyroidism during calcitriol treatment, and (2) PTH secretion may adapt to the ambient serum calcium concentration.

Differences in the dynamics of parathyroid hormone secretion in hemodialysis patients with marked secondary hyperparathyroidism

Hemodialysis patients with predialysis intact parathyroid hormone (PTH) levels of more than 500 pg/mL are generally considered to have marked secondary hyperparathyroidism. Because the serum calcium level in these patients varies from low to high, it is not clear whether every hemodialysis patient with a PTH level > 500 pg/mL is part of a uniform group. The dynamics of PTH secretion in 21 hemodialysis patients with predialysis (basal) intact PTH levels > 500 pg/mL (range, 506 to 1978 pg/mL) has been evaluated. The basal/maximal PTH ratio, an indicator of the degree of relative PTH stimulation in the baseline state, was inversely correlated with the maximal PTH (r = -0.71), the basal serum calcium (r = -0.70), and the difference between the serum calcium at basal and maximal PTH (r = 0.81); the latter is the decrement in serum calcium from baseline necessary to maximally stimulate PTH. Because the basal PTH level appeared to be disproportionately influenced by hypocalcemia, the 21 patients were separated into two groups on the basis of the basal serum calcium (Group I < 9 mg/dL and Group II > 9 mg/dL). Basal PTH was not different between the two groups, even though maximally stimulated PTH (1,219 +/- 204 versus 2,739 +/- 412 pg/mL; P < 0.01) as induced by hypocalcemia and maximally suppressed PTH (217 +/- 37 versus 528 +/- 104; P = 0.05) as induced by hypercalcemia were less in Group I with the low basal calcium; moreover, the ratio of basal/maximal PTH was higher (73 +/- 6 versus 47 +/- 5%; P < 0.01) in Group I with the low basal calcium. These results suggest that the reason for a basal PTH > 500 pg/mL may be different among hemodialysis patients. In hypocalcemic patients, the low serum calcium appeared to be a major impetus for the high basal PTH level. In conclusion, (1) the maximally stimulated PTH appears to provide a better means of separating patients with marked secondary hyperparathyroidism than the basal PTH and (2) hemodialysis patients with basal PTH levels > 500 pg/mL may not be a uniform group.

Studies in a hemodialysis patient indicating that calcitriol may have a direct suppressive effect on bone

Calcitriol putatively suppresses bone activity by decreasing parathyroid hormone (PTH) levels. Results of studies in a 52-year-old female maintenance hemodialysis patient suggest that calcitriol may also have a direct suppressive effect on bone. The PTH-calcium relationship was evaluated through the use of low (1 mEq/l) and high (4 mEq/l) calcium hemodialyses that were performed before the initiation of calcitriol treatment, at the end of 6 weeks of thrice-weekly intravenous calcitriol administration, and 6 weeks after the discontinuation of calcitriol. During the low-calcium dialysis, serum calcium decreased more rapidly and to a greater magnitude after calcitriol treatment despite no appreciable difference in basal and maximally stimulated PTH levels; during the high-calcium dialysis, calcitriol treatment resulted in a more rapid increase in serum calcium despite no appreciable difference in basal and maximally suppressed PTH levels. Discontinuation of calcitriol resulted in responses to the low and high calcium dialyses that were similar to those observed before calcitriol treatment. In conclusion, the results suggest that calcitriol may have a direct suppressive effect on bone that is independent of PTH.

Immunologic studies of anaphylaxis to iron dextran in patients on renal dialysis

Systemic reactions resembling anaphylaxis have occurred after intravenous (IV) iron-dextran administration, a treatment modality that has acquired increased acceptance following the use of erythropoietin for the anemia of patients with chronic renal diseases. Three such patients sustained anaphylactoid reactions immediately after receiving IV test doses of iron-dextran which were their only known exposures. In an effort to determine the mechanism of their reactions, we applied tests for (1) basophil degranulation by iron-dextran, basophil histamine release; (2) a type I anaphylactic reaction, specific IgE antibodies; and (3) an immune complex activation, specific IgG antibodies against iron-dextran. Six other patients with renal diseases served as controls, three of whom had tolerated IV iron-dextran, and three without known exposure. One patient only had any test abnormalities. Her initial positive basophil histamine release and specific IgG antibodies reversed and declined respectively at a 4-month follow-up study. She had developed anaphylaxis, and her studies had been performed at a time after anaphylaxis earlier than the other two. The mechanisms of iron-dextran anaphylaxis may be multiple and not be detectable several months after the incident. Prospective studies will probably be required for a predictive test to be developed.

Pregnancy in women with end-stage renal disease: treatment of anemia and premature labor

There is little experience with the use of various therapies in the end-stage renal disease patient who becomes pregnant. Erythropoietin for the treatment of anemia has become part of the standard treatment regimen of dialysis patients, but experience with its use in pregnancy is limited. We report five cases of its use in dialysis patients during pregnancy. We found no evidence that it crossed the placenta or that it made blood pressure control more difficult. We found that patients required a higher dose of erythropoietin to maintain hematocrit levels than they had before pregnancy. Another therapy involves the treatment for premature labor, which is the most common cause of pregnancy loss in dialysis patients. Two of our patients were successfully treated with indomethacin for premature labor. Both drugs are useful tools in the management of pregnant dialysis patients.

Profile of hospital governance: a report from the nation's hospitals

During the 1980s, hospital governing boards struggled to solve a host of new and difficult problems while attempting to meet the needs of their communities. As we enter the last decade of the 20th century, different challenges lie ahead. To meet these challenges, hospital boards must first understand their various responsibilities. The results of this survey will provide a starting point to understand how hospitals are currently dealing with issues such as governing board composition and organization, board/CEO relations, and governing board operations. (Future articles in Trustee will focus on individual aspects of the survey.) In so doing, readers may begin to unlock the key to increased effectiveness.

The effect of corticosteroids and other antineoplastic agents on the generation of leukocyte migration inhibition factor

We have shown that hydrocortisone in physiological concentrations can inhibit the production of leukocyte migration inhibition factor (LMIF), but does not diminish the action of this lymphokine. Other agents tested failed to influence LMIF production. Inhibition of LMIF production by corticosteroids was influenced by the nature of the stimulus used for the production as an effect could be seen with PHA or Con A, but not Staphylococcal enterotoxin A (SEA). Production of LMIF was promptly restored after removal of the steroids. Furthermore, addition of a calcium ionophore to PHA restored the production of LMIF even in the presence of corticosteroids. In contrast, addition of exogenous IL-2 did not correct the defect in lymphokine secretion. We believe that inhibition of the production of LMIF by steroid may lead to defective granulocytic function and thus, predispose to infection.

Acute effects of dialysis on T lymphocytes in patients with end-stage renal disease

The acute effect of dialysis on T-lymphocyte responses was studied in 11 patients with end-stage renal disease (ESRD). The in-vitro mitogenic response to concanavalin A and pokeweed mitogen was decreased (p less than 0.05) after single passage of blood through the dialyzer, accompanied by a reduction in the proportion of monoclonal antibody-defined total T lymphocytes (Leu 1+ cells) (p less than 0.01), an increase in the percentage of monoclonal antibody-defined monocytes (M 2+ cells), and a decrease in interleukin 2 (IL-2) production (p less than 0.05). Depletion of adherent cells from mononuclear cells isolated from blood after single passage through the dialyzer restored the mitogenic responses to normal levels. Post dialysis mitogenic responses were comparable to pre-dialysis mitogenic responses although IL-2 production (p less than 0.05), and the proportion of T lymphocyte (Leu 1+ cells) remained depressed (p less than 0.01). Cumulative effects of long-term intermittent hemodialysis may contribute to the impaired immunity and the increased frequency of infections and neoplasms in patients with end-stage renal disease.

Renal magnesium wasting associated with amphotericin B therapy

The effect of amphotericin B on magnesium metabolism was studied in 10 patients (aged 30 to 68 years) with systemic fungal infections. Renal magnesium wasting resulting in mild to moderate hypomagnesemia was demonstrated by the second week of therapy following relatively small cumulative dosages of amphotericin B (208 +/- 40 mg). The lowest serum levels and largest fractional excretions of magnesium were observed by the fourth week of therapy after cumulative dosages of 510 +/- 118 mg. A plateauing of the renal magnesium wasting is suggested, as there were no further increases or reductions in fractional magnesium excretion and serum magnesium level, respectively, despite continued amphotericin B administration. Reversibility of the magnesium wasting is indicated by data in three of the patients approximately one year following discontinuation of amphotericin B therapy, in whom the serum magnesium level and fractional magnesium excretion had returned to pretreatment baseline values. Although the available data do not allow precise localization of this defect, increased urinary excretion of magnesium despite its reduced filtered load suggests a tubular defect in magnesium reabsorption. Therefore, routine monitoring of the serum magnesium level during treatment with amphotericin B is recommended.

Plasma and urinary catecholamines and their metabolites in chronic renal failure

The effect of chronic renal failure (CRF) on the plasma concentration and urinary excretion of catecholamines and their metabolites was studied in 14 patients with varying degrees of chronic renal failure who had creatinine clearances of 19 to 77 mL/min. The results were compared with those obtained in a group of age-matched normal controls. Plasma catecholamine concentrations were significantly higher in the CRF patients compared with age-matched normal controls (456.9 +/- 303.1 v 278.5 +/- 81.1 pg/mL). The urinary metanephrine (0.6 +/- 0.6 mg/g creatinine) and vanillylmandelic acid (VMA) (6.6 +/- 4.2 mg/g creatinine) were within the normal range. No significant correlations were found between creatinine clearance and urinary metanephrine and VMA excretion or with the plasma catecholamine concentrations. Our observations indicate that, despite the decrease in creatinine clearance, urinary VMA and metanephrine determinations are valid screening tests for pheochromocytoma in patients with compromised renal function. Plasma catecholamine concentrations, however, show moderate elevation with decreasing renal function.

Modulatory role of gamma-aminobutyric acid (GABA) in the regulation of gonadotropin secretion in patients with chronic renal failure

The role of gamma-aminobutyric acid (GABA) in the regulation of gonadotropin secretion in renal failure, was studied in 5 patients with chronic renal failure who were on maintenance dialysis. Di-n-propylacetic acid (valproic acid-VA), a GABA-transaminase inhibitor which has been shown to increase brain GABA levels, was used in the study. VA produced no significant change in the basal serum LH and FSH concentrations, or in E2 or T concentrations in the renal failure patients, or the E2 and P concentrations in normal controls, but augmented the delta LH (maximum increment above baseline) and delta FSH response to LH-RH. delta LH rose from 30.4 +/- 12.7 mIU/ml (mean +/- SD) to 41.1 +/- 16.8 mIU/ml (p less than 0.01) after VA, while delta FSH rose from 2.8 +/- 1.8 mIU/ml to 3.8 +/- 1.6 mIU/ml (p less than 0.05). The findings support a modulatory role for GABA in gonadotropin secretion in chronic renal failure.