Regulation of corticotropin-releasing factor secretion from Leydig cells by serotonin

CRF is produced in the Leydig cells and acts as a negative autocrine regulator of Leydig cell function. To clarify the hormonal control of CRF secretion by Leydig cells, we evaluated the participation of serotonin (5HT) and serotonin agonists in the release of CRF from Leydig cells and their effects on hCG-induced cAMP generation and steroidogenesis. Serotonin stimulated CRF secretion up to 4-fold above basal levels and inhibited basal and hCG-stimulated cAMP generation and testosterone production (ID50, 1 nM). The inhibitory action of 5HT was prevented by a CRF antibody and the alpha-helical CRF-(9-41) antagonist. The selective 5HT2 receptor agonist (+-)1-[2,5-dimethoxy-4-iodophyryl]2-amino propane hydrochloride (DOI) also stimulated CRF secretion and inhibited hCG-stimulated cAMP generation and testosterone production to control levels (ID50, 7 microM). Serotonergic 5HT1A, 5HT1B/1C, 5HT1D, and 5HT3/5HT2 agonists were less effective inhibitors of hCG-stimulated cAMP and testosterone production, while agonists for the 5HT3 receptor had no effect. [125I]DOI binding studies in Leydig cells demonstrated two sets of receptors with Kd values in the nanomolar and micromolar range, with low and high capacities, respectively. The low affinity site differed from that of brain receptors (Kd, 4.2 nM) and displayed higher binding capacity (50-fold). The selective 5HT2 receptor antagonist ketanserin prevented CRF stimulation and blocked the inhibitory actions of 5HT and DOI, while the alpha 1-adrenergic antagonist prazosin had no effect. Also, treatment of cells with ketanserin increased sensitivity to hCG and raised maximal cAMP and testosterone production. 5HT was a more effective stimulus than hCG in stimulating CRF secretion, and gonadotropin-induced CRF release was inhibited by ketanserin. Inhibitory effects of exogenous CRF were demonstrable after blockade of 5HT action by ketanserin. The inhibitory actions of 5HT were unaffected by pertussis and cholera toxins and were reversed by the addition of 8-bromo-cAMP. These results demonstrate that 5HT acts on 5HT2 receptors in Leydig cells that are distinct from those in the brain to stimulate CRF secretion through a pertussis toxin-insensitive G-protein. This action of 5HT is predominantly mediated by the low affinity 5HT2-binding site and requires full occupancy for maximal CRF stimulation, indicating the absence of spare receptors. 5HT-stimulated CRF inhibits basal and hCG-induced cAMP generation and steroidogenesis. Furthermore, 5HT mediates the stimulatory action of LH/hCG on CRF secretion from Leydig cells and, thus, participates in a negative autoregulatory loop to limit the testosterone response to the gonadotropic stimulus.

Increased sodium-lithium countertransport activity in red cells of IgA nephropathy patients

The aim of this work was to analyze Na,Li countertransport activity in the erythrocytes from patients with IgA nephropathy, in relationship with their blood pressure status and lipid profile. Forty-nine patients (32 males, 17 females) with biopsy-proven IgA nephropathy and without significant impairment of renal function (serum creatinine less than or equal to 1.4 mg/dl) and 36 normal subjects (21 males, 15 females) were evaluated. Twenty-nine patients with IgA nephropathy were normotensive and 20 hypertensive (diastolic pressure greater than or equal to 95 mm Hg or treated by antihypertensive drugs). Na,Li countertransport was significantly higher in red cells from hypertensive than from normotensive patients (P = 0.002) and normal subjects (P = 0.0001), (values respectively 309 +/- 17; 241 +/- 12 and 211 +/- 11 mumol/liter RBC/hr); normotensive patients with IgA nephropathy did not differ from controls regarding the Na,Li countertransport rate. A multiple stepwise logistic regression analysis with blood pressure status as the dependent variable and Na,Li countertransport activity, age, serum creatinine, proteinuria, cholesterol, triglycerides, plasma potassium and time from onset as independent variables, indicated an independent significant association for Na,Li countertransport (P = 0.002) proteinuria (P = 0.006), plasma potassium (P = 0.006) and age (P = 0.029). Other tested variables were not independently related to blood pressure status. Hyperlipidemic patients (plasma total cholesterol concentration greater than 200 mg/dl and/or plasma triglycerides greater than 172 mg/dl) had an erythrocyte Na,Li countertransport activity significantly higher than normolipidemic (P = 0.005) and controls (P = 0.001) (values respectively 295 +/- 14; 226 +/- 12 and 211 +/- 11 mumol/liter RBC/hr).(ABSTRACT TRUNCATED AT 250 WORDS)

Nociceptive quality of the orbicularis oculi reflexes as evaluated by distinct opiate- and benzodiazepine-induced changes in man

The corneal reflex and the three components of the blink reflex (R1, R2, and R3) were recorded electromyographically in volunteers. The area of these responses was measured before and after administration of the narcotic-analgesic fentanyl (1.5 mg i.m.) and its antagonist naloxone, and after administration of the benzodiazepine diazepam (10 mg i.v.) and its antagonist flumazenil. Saline was given as a control placebo. The corneal reflex was 71% reduced by fentanyl, 43% by diazepam. R1 was 35% reduced and R2 was 60% reduced by diazepam. R3 was abolished by both drugs. Whereas the fentanyl-induced changes were completely reversed by naloxone, the diazepam-induced changes were only partly reversed by flumazenil. The corneal reflex appears to be a 'nociceptive' reflex under all points of view. Recording of the orbicularis oculi reflexes in man may be valuable in the evaluation of central-acting neurotropic drugs.

Ceftazidime plus amikacin versus ceftazidime plus vancomycin as empiric therapy in febrile neutropenic children with cancer

Two antibiotic regimens, ceftazidime plus amikacin and ceftazidime plus vancomycin, were compared in a prospective, randomized clinical trial as empiric therapy in febrile granulocytopenic children with cancer. The rate of response was similar in the two groups (66% vs. 77%). The prevalence of secondary gram-negative bacteremia was higher--but not significantly higher--in the group receiving vancomycin. Adverse reactions also occurred more often in the latter group (35% vs. 4%). Mortality did not differ significantly in the two groups. Adjustment for independent predictors of response to treatment by means of multivariate analysis confirmed the lack of any remarkable difference between the responses to the two regimens. We conclude that the use of vancomycin instead of amikacin in combination with ceftazidime does not significantly improve the outcome of treatment of fever and infection in granulocytopenic children with cancer and that the use of vancomycin is associated with an increased frequency of both secondary infections due to gram-negative bacteria and adverse reactions.

Hepatic amino-nitrogen clearance to urea-nitrogen in control subjects and in patients with cirrhosis: a simplified method

The functional hepatic nitrogen clearance during amino acid infusion is a measure of liver cell mass. The clinical feasibility of the test has so far been limited by methodological problems. A simplified procedure was used to measure the urea-nitrogen synthesis rate and functional hepatic nitrogen clearance in nine subjects with normal liver function and in nine patients with cirrhosis. The method was based on only four consecutive 2-hr urine collections and five blood samples. Total body water was calculated from a nomogram based on age and anthropometric data, whereas the gut urea hydrolysis was assigned one fixed fraction of synthesis (0.17 in control subjects and 0.26 in patients with cirrhosis). Finally, a solution of a single amino acid, alanine, was infused as substrate for urea synthesis. Urea-nitrogen synthesis rate increased linearly with increasing alpha-amino-nitrogen concentration, and the slope of the regression (functional hepatic nitrogen clearance) was reduced in cirrhosis from 37.5 +/- 7.0 L/hr to 18.4 +/- 6.7 L/hr; p less than 0.005. The hepatic nitrogen clearance was linearly related to the clinical status (Child-Pugh score), to routine liver function tests and to galactose elimination capacity (r = 0.869), a well-established, quantitative, liver function measure. The simplified method makes the measurement of hepatic nitrogen clearance suitable for routine clinical use. The test might prove useful to study the alterations of nitrogen metabolism in cirrhosis, with special reference to hepatic encephalopathy.

Effect of physical exercise on one-sample antipyrine clearance

Moderate physical exercise for a few hours is not expected to reduce the hepatic elimination of drugs exhibiting capacity-limited metabolism (low-clearance drugs such as antipyrine). However, previous studies have shown that antipyrine half-life, measured by the multiple-sampling technique, is increased by exercise. A simplified one-sample procedure for antipyrine clearance determination is increasingly being used as a liver function test. The effects of exercise on this measurement have never been evaluated. We measured antipyrine clearance, using the one-sample, simplified procedure in a group of 50 young Italian army soldiers, while at rest and during a 6 hour march in the mountains (extra energy expenditure: 7.43 kjoule per min). Mean antipyrine clearance was on average 46.6 (SD 10.2) ml/min (range 30.5-65.4) while resting, and 46.2 (10.5) (range 25.5-64.8) while exercising (not different). No specific advice regarding physical exercise is needed whenever liver function is measured in outpatients by the one-sample, simplified antipyrine clearance test.

[Nosocomial infections caused by methicillin-resistant Staphylococcus aureus in a pediatric intensive care unit]

We performed an epidemiological investigation owing to the appearance between February and March 1988, of subsequent MRSA infections in our ICU; we also started a checking scheme. At the same time we performed a retrospective-perspective study of 701 patients (310 newborns 391 not newborns) admitted into ICU from 1-1-1987 to 30-6-1988. This study allowed us to settle the presence of MRSA in ICU and the manner in which they become infected. From our study the 4.9% of our patients contracted hospital infections and the 34.2% of these were MRSA infections. The 39.7% of our colonized patients were MRSA. It is really significant the frequency of MRSA colonization (p less than 0.0005) among newborn patients compared with other age patients; in the meantime there is not statistical significance in the frequency of MRSA hospital infections among the two groups. The results of our study show that infections were probably transmitted by the hands of the members of staff and that the reservoir of MRSA are tracheostomized hosts or long term ventilated patients.

[Intra- and perioperative arrhythmia and ischemic signals in myocardial revascularization patients]

In order to evaluate perioperative electrical cardiac disturbances and ST segment changes, 42 patients (38 M, 4 F, aged 57 +/- 6 ys) were studied using 24-hour Holter monitoring before, during and after coronary bypass surgery. In the 4-6 hours before cardioplegic arrest, 38% of patients had ST segment changes. No patient and malignant arrhythmias. The injection of cold cardioplegic solution was followed by bradycardia, ventricular tachycardia, ventricular fibrillation and isoelectric line within 2-4 minutes. After aortic declamping, 30 patients were defibrillated. Impulse formation and conduction disturbances, found in 55% of patients, solved themselves in 1 to 60 minutes. Bundle branch block continued in just 4 cases. A total of 59% of patients had ST segment elevation for 14 +/- 14 minutes and 19% had ST segment depression for 19 +/- 20 minutes. Successive transient ST segment changes were detected in 38% of patients. Sustained ventricular tachycardia occurred during 2 ischemic episodes. Impulse formation and conduction disturbances were not related to the duration of cardiac arrest or ventricular fibrillation, but were more frequent and lasted longer in patients with incomplete revascularization. Transient ST segment depression far from aortic declamping correlated with preclamping ischemia. Transient ST segment elevation correlated with incomplete revascularization. We concluded that ECG signs of intraoperative damage were reversible. Moreover, perioperative transitory ischemia was frequent but could be prevented by coronary active drug administration. On the other hand incomplete revascularization was associated with electrical disturbances and ischemia.

Corticotropin-releasing factor is produced by rat Leydig cells and has a major local antireproductive role in the testis

Cultured rat Leydig cells secreted considerable amounts of corticotropin-releasing factor (CRF). A major stimulus for Leydig cell-derived CRF was the trophic hormone LH/hCG, which released the peptide in a dose dependent fashion. Incubation of Leydig cells with a CRF antagonist revealed tonic suppression of basal and hCG-stimulated testosterone production by endogenously produced CRF. These findings demonstrate that CRF acts via functional Leydig cell receptors to exert autocrine inhibitory actions on Leydig cell steroidogenesis. In the testis CRF acts as an antireproductive hormone and as a major local inhibitory regulator of Leydig cell function.

The effect of fresh human serum on ofloxacin bactericidal activity

We have studied the possibility of an increase in ofloxacin bactericidal activity when it is combined with fresh human serum. The tested strains were 10 clinical isolates of Klebsiella pneumoniae. From among our strains 5 were susceptible to serum bactericidal activity and 5 were found to be resistant. We selected two serum concentrations (15 and 35%) to test against susceptible strains and two (55 and 75%) to test against resistant strains in combination with the minimum inhibitory concentration (MIC), 1/2MIC and 1/4MIC of ofloxacin. The results show a slight variability among the tested strains depending on microbiological characteristics of single strains, however, the serum + ofloxacin combination was advantageous. Only one exception was observed: a resistant strain that had an increased survival percentage against ofloxacin and serum in combination.

[Non-epidermidis coagulase-negative staphylococci in infectious diseases of the compromised host]

Today Staphylococcus epidermidis has been recognized as the etiological agent of infectious diseases such as endocarditis, sepsis and meningitis that mainly come out in compromised hosts because of the breaching of the mechanical barrier (cardiosurgical, neurosurgical patients and central venous catheter carriers). Other "non-epidermidis coagulase negative Staphylococci" are more and more frequently isolated from patients at high risk of infection. Faced with these isolations, it is difficult for the clinician and the microbiologist to give these microorganisms their effective pathogenic role. The Authors present a case list of seriously compromised patients in whom non-epidermidis coagulase negative Staphylococci were repeatedly isolated: hemato-oncological patients: the Authors mark out 6 cases of sepsis that is, likely, to be linked to a central venous catheter. The isolated microorganisms were: S. warneri (3 cases); S. haemolyticus (1 case); S. hominis (1 case); S. xylosus (1 case); neurosurgical patients: in whom 3 cases of cerebro-spinal fluid infection were observed; 3 patients carried a ventriculo-peritoneal derivation; 1 patient carried an Ommaya's device. The etiological agents were S. haemolyticus in 2 cases, S. capitis in 1 case. The Authors point out the multiresistance of some strains (S. haemolyticus) and the oxacillin-methicillin resistance phenomenon. They also underline the need for a specific identification of coagulase-negative Staphylococci and the importance of a strict collaboration between clinicians and microbiologists in order to get a correct interpretation of the role played by these microorganisms in infectious diseases of the compromised host.

Immunohistochemical localization of growth hormone-releasing hormone in human gonads

Human gonads were examined for the presence of ir growth hormone-releasing-hormone. We demonstrated the presence of immunostainable cells both in ovarian and in testicular tissue using a non-crossreactive anti-GRH antiserum and the immunoperoxidase detection technique. In ovaries from ovulating women, GRH immunoreactivity was localized in the corpora lutea; granulosa cells, theca cells and cells of primary follicles did not stain. In premenopausal ovaries, staining was detectable in scattered luteinized stromal cells. In testes from post-puberal men GRH immunoreactivity was localized in the Leydig cells; cells of the germinal epithelium did not stain. These results demonstrate the presence of GRH in human gonads and suggest that this peptide may exert regulatory function at the testicular and ovarian levels.

Antiproteinuric effect of angiotensin-converting-enzyme inhibitors in patients with primary glomerular disease and normal renal function

The antiproteinuric efficacy of angiotensin-converting-enzyme inhibitors (ACEI) has been extensively investigated in patients with several types of nephropathy, but there are few data on the use of ACEI in patients with primary glomerular disease without renal function impairment. We evaluate the effect of long-term therapy with captopril on arterial pressure and proteinuria in 13 patients with primary glomerular disease, selected on the following criteria: persistent proteinuria greater than 600 mg/day, serum creatinine less than or equal to 1.5 mg/dl, no dietary restriction or antihypertensive or immunosuppressive therapy for at least 9 months prior to enrolment. Ten of 13 patients were normotensive. The treatment with captopril induced an early and persistent decrease in proteinuria (41%), and a significant increase in serum albumin. We did not find a significant correlation between changes in MAP and changes in protein loss or between variations in serum creatinine and in proteinuria. Our results demonstrate that captopril is effective in reducing proteinuria in patients with primary glomerular disease with normal renal function. Since the antiproteinuric effect is not associated to a concomitant decrease in arterial pressure, we presume that it might be due to a specific intrarenal action of captopril.

Analysis of the deterioration rates of liver function in cirrhosis, based on galactose elimination capacity

The prognosis of cirrhotic patients may depend on their liver function, but very few data are available to predict life expectancy in individual subjects on the basis of their liver function tests. The yearly changes in liver function, based on galactose elimination capacity (GEC), were retrospectively analyzed in 76 cirrhotic patients. The first GEC measurement had always been performed at the time of diagnosis. From that time on, mean GEC changes (in mmol/min per year) were +0.13 [SD 0.60] in the 1st year (range: +1.42/-1.35), and -0.03 [0.30] in the 2nd year (P = ns). Only after 36 months could a significant deterioration in liver function be demonstrated, but GEC changes still ranged from +0.14 to -0.35. The trend in liver function was similar in patients with alcoholic and non-alcoholic cirrhosis, but in alcoholics a favourable effect of abstinence was proved. In individual subjects, 2 consecutive GEC measurements, at least 6 months apart, failed to predict the following GEC values. The coefficients of determination between expected and measured GEC or delta GEC were 0.13 and 0.36, respectively (n = 58). When forecasting was limited to 2 years (n = 38), still only 31% and 55% of GEC values and delta GEC variance was predictable on the basis of preceding GEC values. The study shows that no definite trends in liver function deterioration rates can be observed in cirrhosis. This limits the usefulness of liver function tests in predicting prognosis in cirrhotic patients.

A novel mechanism of action of corticotropin releasing factor in rat Leydig cells

We have recently demonstrated the presence in the rat Leydig cells of a corticotropin releasing factor (CRF) receptor and an inhibitory action of the peptide on human chorionic gonadotropin (hCG)-induced cAMP generation and steroidogenesis. The inhibitory action of CRF was unaffected by pertussis toxin and was completely reversed by 8-bromo-cAMP (Ulisse, S., Fabbri, A., and Dufau, M. L. (1989) J. Biol. Chem. 264, 2156-2163). In this study, we have evaluated the participation of protein kinase C in CRF action in the Leydig cells and the level of the gonadotropin signal pathway affected by CRF. Binding of 125I-labeled ovine CRF to Leydig cell membranes was reduced by GTP and guanyl-5'-yl imidodiphosphate (Gpp(NH)p), in a dose-dependent manner. Phorbol 12-myristate 13-acetate, like CRF, caused time-dependent inhibition of hCG-induced cAMP generation and steroidogenesis. This inhibitory action was reversed by 8-bromo-cAMP. Both CRF and 12-O-tetradecanoylphorbol-13-acetate did not affect 125I-hCG binding. No additive effects of CRF and the phorbol ester were observed in these studies. CRF caused a rapid translocation of protein kinase C in Leydig cells. Preincubation of cells with protein kinase C inhibitors or TPA-induced depletion of protein kinase C prevented the inhibitory actions of CRF and TPA. CRF and TPA were able to inhibit the stimulation of cAMP and testosterone production by cholera toxin and forskolin. Adenylate cyclase stimulation by Gpp(NH)p, luteinizing hormone + Gpp(NH)p, and NaF in crude membranes or by forskolin and manganese in solubilized membranes, prepared from CRF- and TPA-treated cells, was also markedly inhibited. We conclude that CRF receptors interact with a pertussis toxin-insensitive G protein (possibly Gp) in the Leydig cell and that the inhibitory action of CRF on Leydig cell function is exerted mainly on the catalytic subunit of adenylate cyclase through a direct or indirect action of protein kinase C.

Synthesis of urea after a protein-rich meal in normal man in relation to ageing

An age-related decline in the functional capacity of the liver has been repeatedly demonstrated by means of dynamic tests. We measured the urea-N synthesis rate in response to a protein-rich meal in 24 healthy subjects divided into three age-groups (less than or equal to 55 years, 56-70 years; greater than or equal to 71 years). No differences were observed in the basal state. The peak urea synthesis and the mean urea synthesis in the 5 hours after the meal were blunted with increasing age, and a negative correlation was present between mean or peak urea synthesis and age (r = -0.572 and r = -0.541, respectively). No differences in basal and post-meal total alpha-amino-nitrogen or individual plasma amino acids were observed. Hormone responses were similar. Galactose elimination capacity was also reduced with increasing age, and correlated with mean and peak urea synthesis after a protein mean (r = 0.640 and r = 0.591, respectively). These data suggest that the capacity of the liver to produce urea in response to a protein-rich meal is reduced in the elderly in relation to a decreased functional liver cell mass.

The role and regulation of testicular opioids

Endogenous opioids are present in the male gonad and may be involved in the local control of testicular function. Testicular opioids are mainly produced in Leydig cells and exert direct paracrine inhibitory actions on the tubule, which in turn may have indirect Sertoli-cell-mediated effects on Leydig cell steroidogenesis. Gonadotropins and CRF stimulate production of gonadal opioids, and the presence of a gonadotropin milieu appears to be a requisite for the inhibitory paracrine actions of opioids on steroidogenesis. The recognition of such multiple intratesticular hormonal interactions should provide insights into the mechanisms involved in idiopathic infertility in men.

Do calcium channel blockers have any influence on the immunological status of renal graft recipients on ciclosporin therapy?

We have assessed the peripheral distribution of T cells, using the monoclonal antibodies OKT3, OKT4, OKT8 and LEU7 and the proliferative response to phytohaemagglutinin (PHA), in 10 renal transplant recipients. In each patient, the immunological pattern was evaluated twice, both before and after 1 month of calcium antagonist (calcium channel blockers, CaA) treatment. During treatment with CaA, we have observed both a significant decrease in the mitogenic response to PHA and a significant increase in OKT8 cells. Our data support the hypothesis that CaAs per se may have an immunomodulatory effect on T cell distribution independently of changes in ciclosporin (CS) blood levels. These results could also provide a cellular basis for synergism between CS and CaA.

[Clinical applications of the heart-lung transplant. Clinical results 5 years after the start of the program at Papworth]

In this study is reviewed the experience at Papworth Hospital, Cambridgeshire, and Great Ormond Street Hospital, London, with combined heart-lung transplantation. Between April 1984 and June 1989, 73 patients have undergone heart-lung transplantation. Donors and recipients were carefully matched with regards to serology, morphology and cytomegalovirus compatibility. Heart preservation was based on use of cold St. Thomas' cardioplegic solution; a pulmonary preservation fluid has been developed that allows distant organ procurement with a single pulmonary artery flush technique (Papworth solution). The recipients were: 21 pts with Eisenmenger's syndrome, 15 pts with pulmonary hypertension, 37 pts with pulmonary disease (including 22 cystic fibrosis). The results are: no surgical mortality; no acute cardiac rejection episodes. Twenty-three patients died (16 with infections, 3 with obliterative bronchiolitis, 2 with cerebral embolism and 2 others). The actuarial survival rate at one year is 73.2%; 63% at two years and 47.4% at four years. The use of transbronchial biopsy of the lung has provided accurate early and safe diagnosis of pulmonary rejection. Development in organ preservation and patient management, as well as careful selection of recipients and donors, have led to the effective use of resources and thereby to these good results.

[Asthma caused by Lucilia Caesar larvae: clinical and immunologic study]

Lucilia Caesar larvae (LCL) are used as live fish bait by anglers. Five cases of asthma and rhinoconjunctivitis following exposure to LCL are reported. Three had work-related asthma as they were working on a fish bait farm or shop and two had asthma when they went fishing. In one subject exposure to LCL caused asthma, rhinoconjunctivitis and contact urticaria. In four subjects peak expiratory flow rate (PEFR) was monitored during exposure to LCL. In three out of four subjects there was evidence of LCL-related asthma. In one subject it was not possible to record PEFR during exposure to LCL, as he had not gone fishing since 1985. Two extracts of LCL were prepared: one was the PBS (phosphate-buffered saline) washing fluid of LCL, the other was the PBS extract of homogenized LCL. Positive cutaneous prick tests to both LCL extracts were detected in three out of four symptomatic subjects. Specific IgE against both LCL extract antigens were found by the RAST method in four out of five subjects with LCL-related asthma. One subject had both negative skin tests and RAST. Specificity and potency of LCL-IgE binding was shown by RAST inhibition method performed on the serum pool of four patients with positive RAST results. Significant inhibition of more than 50% by LCL washing fluid at a dilution extract was found at a dilution of 1:10 and by homogenized LCL extract at a dilution of 1:100. No significant inhibition of LCL-IgE binding by dermatophagoides, parietaria and milk antigens was found. This study demonstrated that LCL emanations are potent sensitizers and elicit IgE-mediated asthma.

Immunoreactive beta-endorphin levels in cerebrospinal fluid of children with acute lymphoblastic leukemia: relationship with glucocorticoid therapy and neurological complications

Neurological disorders, such as seizures, are not infrequently associated with anti-leukemic therapy. It has been hypothesized that a disrupted peptidergic transmission between neurons could be the cellular basis of the neurological dysfunction. Since endogenous opioids have been recently found to alter neuronal function and possess anticonvulsant properties, the cerebrospinal fluid (CSF) immunoreactive beta-endorphin levels in children with Acute Lymphoblastic Leukemia (ALL) during chemotherapy and cranial irradiation have been studied. Twenty-seven children, 2 at low, 20 at medium and 5 with high risk ALL, undergoing prophylactic treatment for meningeal leukemia, entered the study. Sequential lumbar punctures with introduction of MTX combined with oral prednisone therapy were performed; each lumbar puncture sample was collected and assayed for immunoreactive beta-endorphin. All the patients studied showed a biphasic profile of the peptide with the minimum levels reached during the induction (days 14-28) and the maximum levels detected at the end of the intensification chemotherapy (days 49-55). In the 3 groups the beta-endorphin decrease corresponded to the period of prednisone therapy; the increase was concomitant with the suspension of oral glucocorticoids. 3 patients showed tonic-clonic seizures which coincided with the lowest cerebrospinal fluid beta-endorphin levels and, in the follow-up, 13 out of 27 patients displayed EEG abnormalities. From these findings a relationship between cerebrospinal fluid beta-endorphin concentrations and neuronal excitability in patients with ALL can be suggested. It is also evidenced that oral glucocorticoid therapy has profound inhibitory effects on central beta-endorphin levels.