L-arginine: nitric oxide pathway in endotoxemia and human septic shock

OBJECTIVE

To investigate the relationship between nitric oxide production, endotoxemia, and hemodynamic alterations in human septic shock.

DESIGN

Prospective study.

SETTING

A 32-bed intensive care unit in a university referral hospital.

PATIENTS

Two groups of septic patients with shock (n = 13) or without shock (n = 16) and an additional group of nonseptic patients as control group (n = 25).

MEASUREMENTS

Plasma nitrite and nitrate concentrations were measured as an index of nitric oxide generation. Nitrite and nitrate concentrations were correlated with plasma endotoxin and hemodynamic variables.

MAIN RESULTS

Increased plasma nitrite and nitrate concentrations were found in patients with septic shock (p < .01). Nitrite and nitrate correlated directly with endotoxin concentration (r2 = .21, p < .05) and cardiac output (r2 = .49, p < .05), and inversely with systolic blood pressure (r2 = .24, p < .01).

CONCLUSIONS

This study demonstrated the activation of the L-arginine:nitric oxide pathway in human endotoxemic septic shock, suggesting that nitric oxide may be an important mediator of the hemodynamic disturbances in this pathophysiologic situation.

Angiocentric cutaneous T-cell lymphoma of childhood (hydroa-like lymphoma): a distinctive type of cutaneous T-cell lymphoma

BACKGROUND

Angiocentric cutaneous T-cell lymphomas of childhood (ACTCLC) are an unusual type of T-cell lymphomas that present with a vesiculopapular eruption mimicking hydroa vacciniforme. Most patients have been children from Asia and Latin America.

OBJECTIVE

The purpose of this study was to describe four cases of ACTCLC; to discuss its clinical, histopathologic, and immunohistochemical features; to consider its possible relationship to the Epstein-Barr virus (EBV); and to clarify its classification within the spectrum of angiocentric lymphomas.

METHODS

The clinical, histopathologic, and immunohistochemical features of four cases of ACTCLC were identified and analyzed. In addition in situ hybridization for EBV was performed in all cases.

RESULTS

The clinical features were similar to previous cases reported under different names, such as hydroa-like lymphomas, edematous, scarring vasculitic panniculitis. Histologically, all showed angiocentric infiltrates composed mainly of T cells. In all cases there were variable numbers of CD30+ cells. The EBV was present in three of the cases.

CONCLUSION

ACTCLC is a distinct type of T-cell lymphoma. It affects mainly children, and the EBV appears to play a role in the pathogenesis of this disease.

Factors predictive of outcome on admission to an acute geriatric ward

AIM

To investigate which factors predict outcome of elderly patients on discharge and at 6 months.

METHODS

A prospective study in an acute geriatric ward. Within 48 h of admission, patients were assessed for social factors, geriatric problems, admission diagnoses, medication, function and mental ability. Outcome measures were mortality, length of stay, institutionalization, readmissions and attendance at accident and emergency within 6 months.

RESULTS

353 patients were studied, with a mean age of 81.8 years. Logistic regression analyses showed that variables predicting hospital mortality were Barthel index on admission, pre-morbid disability and polypharmacy. The only variable independently predictive of prolonged stay in hospital was a Barthel score of <45 on admission. Functional disability on admission was predictive of institutionalization on discharge. Variables predicting mortality within 6 months of discharge were Barthel index on admission <65, presence of pressure sores, malnutrition and polypharmacy. Variables independently predictive of institutionalization were mental state and a low pension. Those who took more than five drugs on admission were more likely to attend accident and emergency and be readmitted.

CONCLUSION

Limited activities of daily living and geriatric problems on admission are the strongest predictive factors of outcome, independent of diagnoses.

Phosphoramidate derivatives of d4T as inhibitors of HIV: the effect of amino acid variation

Phosphoramidate derivatives of the nucleoside analogue, 2',3'-dideoxy-2',3'-didehydro thymidine (d4T) have been prepared as potential membrane-soluble pro-drugs of the big-active free phosphate forms. In particular phenyl phosphates, linked via nitrogen to methyl-esterified amino acids, were studied. All compounds were fully characterised by a range of methods (high-field multinuclear NMR, mass spectrometry and high performance liquid chromatography (HPLC)) and were subjected to in vitro evaluation of their anti-HIV efficacy. The nature of the amino acid appeared to be extremely important for the eventual antiviral action. Of the amino acids studied, L-alanine was the most efficacious, whilst L-proline and glycine were particularly poor. However, an unnatural amino acid moiety, dimethylglycine, could substitute for alanine with little or no loss of activity.

Interleukin-10 and the monocyte/macrophage-induced inflammatory response in septic shock

Interleukin (IL)-10 is a potent immunosuppressant of monocyte/macrophage function and may help control the inflammatory response induced by bacterial infection. To analyze whether IL-10 is detectable in plasma of patients with septic shock and to evaluate its relationship with endotoxin (lipopolysaccharide [LPS])-induced and monocyte/macrophage-induced inflammatory response, plasma IL-10, tumor necrosis factor (TNF)-alpha, IL-1 beta, IL-6, IL-8, LPS, and neopterin were studied in 24 patients with septic shock and in 12 critically ill patients. Eighty-three percent of patients with septic shock and 25% of critically ill patients had detectable levels of IL-10 (P < .001). There was a significant correlation between plasma IL-10, neopterin (r = .72), TNF-alpha (r = .76), IL-6 (r = .68), and IL-8 (r = .61) levels in patients with septic shock. Monocyte/macrophage activation leads to massive secretion of IL-10, which, however, seems to be unable to control the increased production of proinflammatory mediators during septic shock.

Immunoprophylactic trial with combined Mycobacterium leprae/BCG vaccine against leprosy: preliminary results

In an attempt to find a vaccine that gives greater and more consistent protection against leprosy than BCG vaccine, we compared BCG with and without killed Mycobacterium leprae in Venezuela. Close contacts of prevalent leprosy cases were selected as the trial population since they are at greatest risk of leprosy. Since 1983, 29,113 contacts have been randomly allocated vaccination with BCG alone or BCG plus 6 x 10(8) irradiated, autoclaved M leprae purified from the tissues of infected armadillos. We excluded contacts with signs of leprosy at screening and a proportion of those whose skin-test responses to M leprae soluble antigen (MLSA) were 10 mm or more (positive reactions). By July, 1991, 59 postvaccination cases of leprosy had been confirmed in 150,026 person-years of follow-up through annual clinical examinations of the trial population (31 BCG, 28 BCG/M leprae). In the subgroup for which we thought an effect of vaccination was most likely (onset more than a year after vaccination, negative MLSA skin-test response before vaccination), leprosy developed in 11 BCG recipients and 9 BCG/M leprae recipients; there were 18% fewer cases (upper 95% confidence limit [CL] 70%) in the BCG/M leprae than in the BCG alone group. For all cases with onset more than a year after vaccination irrespective of MLSA reaction the relative efficacy was 0% (upper 95% CL 54%; 15 cases in each vaccine group). Retrospective analysis of data on the number of BCG scars found on each contact screened suggested that BCG alone confers substantial protection against leprosy (vaccine efficacy 56%, 95% CL 27-74%) and there was a suggestion that several doses of BCG offered additional protection. There is no evidence in the first 5 years of follow-up of this trial that BCG plus M leprae offers substantially better protection against leprosy than does BCG alone, but the confidence interval on the relative efficacy estimate is wide.

Burnout among Portuguese radiographers during the COVID-19 pandemic

INTRODUCTION

The COVID-19 pandemic has had a global impact, including in health services, placing health professionals under enormous tension, pressure, and stress. Professionals involved in the care, diagnosis, and treatment of COVID-19-infected patients have been subject to emotional and physical distress that can potentially enhance the development of occupational diseases. The aim of this study was to assess the impact of the COVID-19 pandemic on the incidence of burnout among Portuguese radiographers.

METHODS

This was a cross-sectional, quantitative study. Burnout levels were estimated using the Maslach Burnout Inventory-Human Services Survey, composed of 22 questions. Specific questions were developed to characterize the socio-demographic situation and the impact of the pandemic on the radiographers. Data were descriptively analyzed and Mann-Whitney and Kruskal-Wallis tests were used for correlation analysis.

RESULTS

The study sample comprised 386 radiographers, 68.7% of whom where female and 31.3% male. The mean sample age was 36.3 (±9.1) years. A total of 43.5% and 45.5% of subjects had a high level of emotional exhaustion and depersonalization, respectively, and 59.8% experienced low personal accomplishment. Altogether, 23.3% of study participants were at high risk of burnout in the three dimensions assessed and 77.2% in at least one.

CONCLUSION

Study results showed that radiographers were at high risk of developing burnout in the COVID-19 pandemic setting. Health institutions should actively monitor these professional's mental health and develop restorative strategies that enable their emotional wellbeing, preventing absenteeism and increasing patients' quality of care.

IMPLICATIONS FOR PRACTICE

Burnout of health professionals has a strong impact on health services organization, resulting in increased absenteeism and error probability, frequent work delays, low productivity and job satisfaction, inter- and intra-professional conflicts, high job turnover, high job quit, and decreased quality of care perceived by users.

Lack of effect of the ghrelin gene-derived peptide obestatin on cardiomyocyte viability and metabolism

Obestatin is a recently discovered peptide encoded by the ghrelin gene that opposes ghrelin effects on food intake and gastrointestinal function. The biological activity of obestatin depends on amidation at its carboxyl terminus and on its postulated binding to the orphan G protein-coupled receptor 39 (GPR39). We have previously demonstrated that ghrelin is synthesized by cardiomyocytes and has direct effects on its viability. Our aim was to know if obestatin, derived from the same gene as ghrelin, also affects cardiomyocyte physiology. By RT-PCR and immunocytochemistry we have demonstrated that murine cardiomyocytes cultured in vitro and human atrial tissue express GPR39 receptor. Competitive binding studies with radioiodine 125I-labeled obestatin recognized specific binding sites for this peptide in the murine cardiomyocyte cell line HL-1. However, obestatin did not modify the cell cycle or viability of these cells, and it was not able to prevent the cytosine arabinoside-induced apoptosis of HL-1 cardiomyocytes, as assessed by Hoechst dye vital staining, flow cytometry analysis and determination of lactate dehydrogenase in the culture media. Finally, treatment with obestatin did not affect fatty acid or glucose uptake by HL-1 cardiomyocytes. In conclusion, obestatin is not a relevant metabolic or viability modifier for cardiomyocytes.

Feasibility and Safety of Endoscopic Ultrasound-Guided Biliary Drainage (EUS-BD) for Malignant Biliary Obstruction Associated with Ascites: Results of a Pilot Study

BACKGROUND

It has been suggested that EUS-BD may be a feasible and safer alternative to percutaneous transhepatic biliary drainage (PTBD) after failed ERCP in patients with ascites. To date, no study has specifically evaluated the performance of EUS-BD in this context.

METHODS

Retrospective analysis was done for patients with and without ascites who underwent EUS-BD for malignant biliary obstruction after failed ERCP between July 2010 and September 2014. Complications and technical and clinical successes between the two groups were compared.

RESULTS

A total of 31 patients were included: 20 patients without ascites (group 1) and 11 with ascites (group 2). Nineteen patients underwent EUS-hepaticogastrostomy (six in group 2), and 12 underwent EUS-choledochoduodenostomy (five in group 2). Technical success was achieved in all patients. Clinical success was observed in 95% (n = 19) in group 1 and 64% (n = 7) in group 2 (p = 0.042). In three out of four patients without clinical success in group 2, the follow-up period was not long enough to observe the clinical response because of early death within the 2 weeks after EUS-BD secondary to disease progression or preprocedural unresponsive sepsis. No significant differences were observed between groups 1 and 2 either in the overall rates of procedural-related complications (20 and 9%, respectively, p = 0.63) or in the rates of major complications (15 vs 9%, respectively, p = 0.639). Stent migration occurred in one patient in each group, intra- or post-procedural bleeding occurred in two patients in group 1, which was conservatively managed, and one patient in group 1 presented biliary leakage. Stent patency and the number of re-interventions were not significantly different.

CONCLUSIONS

EUS-BD is technically feasible in patients with ascites. Our results suggest that EUS-BD may be a clinically effective and safe alternative after failed ERCP in patients with ascites.

Inflammatory mediators and their influence on haemostasis

Sepsis is the most important cause of mortality in the Intensive Care Units. At present, sepsis is understood to be the inflammatory response of the host to infection, rather than a direct effect of microbial aggression. From the clinical standpoint, this inflammatory response is known as systemic inflammatory response syndrome (SIRS). Pathophysiologically, SIRS is characterized by the activation of several groups of cell (monocytes/macrophages, PMNs, and endothelial cells) and by the release of inflammatory mediators (cytokines and others). Tumor necrosis factor (TNF) is the first cytokine released by endotoxin action over monocyte/macrophage. TNF secretion, modulated by interferon gamma (IFN gamma) and interleukin 10 (IL-10), is followed by release of other cytokines such as interleukins (IL) (IL-1, IL-6 and IL-8). These mediators are able to act over hemostasis activating the extrinsic pathway through tissue factor expression. The action of the mediators over endothelial cells induces an increase in plasminogen activator inhibitor type 1 (PAI-1) levels with inhibition of fibrinolysis. Both coagulation activation and fibrinolysis blockade result in fibrin deposit in the microvascular system. The complexity of the mechanisms implicated in systemic inflammatory response make a general rule so difficult to establish, because patient response is highly individualized and it is not possible to know which moment of this dynamic process is being analyzed.

Multiphasic action of glucose and alpha-ketoisocaproic acid on the cytosolic pH of pancreatic beta-cells. Evidence for an acidification pathway linked to the stimulation of Ca2+ influx

Glucose stimulation raises the pHi of pancreatic beta-cells, but the underlying mechanisms are not well understood. We have now investigated the acute effects of metabolizable (glucose and the mitochondrial substrate alpha-ketoisocaproic acid, KIC) and nonmetabolizable (high K+ and the K-ATP channel blocker tolbutamide) insulin secretagogues on the pHi of pancreatic beta-cells isolated from normal mice, as assessed by BCECF fluorescence from single cells or islets in the presence of external bicarbonate. The typical acute effect of glucose (22-30 mM) on the pHi was a fast alkalinization of approximately 0.11 unit, followed by a slower acidification. The relative expression of the alkalinizing and acidifying components was variable, with some cells and islets displaying a predominant alkalinization, others a predominant acidification, and others yet a mixed combination of the two. The initial alkalinization preceded the [Ca2+]i rise associated with the activation of voltage-sensitive Ca2+ channels. There was a significant overlap between the glucose-evoked [Ca2+]i rise and the development of the secondary acidification. Depolarization with 30 mM K+ and tolbutamide evoked pronounced [Ca2+]i rises and concomitant cytosolic acidifications. Blocking glucose-induced Ca2+ influx (with 0 Ca2+, nifedipine, or the K-ATP channel agonist diazoxide) suppressed the secondary acidification while having variable effects (potentiation or slight attenuation) on the initial alkalinization. KIC exerted glucose-like effects on the pHi and [Ca2+]i, but the amplitude of the initial alkalinization was about twice as large for KIC relative to glucose. It is concluded that the acute effect of glucose on the pHi of pancreatic beta-cells is biphasic. While the initial cytosolic alkalinization is an immediate consequence of the activation of H+-consuming metabolic steps in the mitochondria, the secondary acidification appears to originate from enhanced Ca2+ turnover in the cytoplasm. The degree of coupling between glucose metabolism and Ca2+ influx as well as the relative efficacies of these processes determines whether the acute pHi response of a beta-cell (or of a tightly coupled multicellular system such as an islet of Langerhans) is predominantly an alkalinization, an acidification, or a mixed proportion of the two.

Antigens and antibodies in sera from human cases of epilepsy or taeniasis from an area of Mexico where Taenia solium cysticercosis is endemic

Human neurocysticercosis is an important parasitic disease in developing countries. Most epidemiological studies on the disease have used antibody-based assays that allow the detection of transmission 'hot spots' and the identification of the main risk factors for transmission. However, such assays have low predictive value in the detection of active cases of neurocysticercosis. The screening potential of the most commonly used antibody-detection technique, the electroimmunotransfer blot assay (EITB), has now been compared with an antigen-capture assay, in an endemic region of Mexico. The subjects were 68 patients with late-onset epilepsy, 35 cases of taeniasis and a randomly selected, control group of 133 individuals from the same region. Parasite-specific antibodies and antigens were more common among the epileptics and taeniasis cases than among the controls. The antigens appeared to be associated with late-onset epilepsy and the antibodies with the presence of subcutaneous nodules. The sensitivities of both tests, to detect epilepsy or taeniasis, were low, but the specificity and the positive predictive value of the antigen-capture assay was high when used with the epileptics. As late-onset epilepsy and neurocysticercosis seem to be associated in endemic regions, antigen-capture assays are probably the most reliable method of detecting active cases of neurocysticercosis in epidemiological studies.

Thapsigargin-sensitive cationic current leads to membrane depolarization, calcium entry, and insulin secretion in rat pancreatic beta-cells

Glucose-induced insulin secretion by pancreatic beta-cells depends on membrane depolarization and [Ca2+]i increase. We correlated voltage- and current-clamp recordings, [Ca2+]i measurements, and insulin reverse hemolytic plaque assay to analyze the activity of a thapsigargin-sensitive cationic channel that can be important for membrane depolarization in single rat pancreatic beta-cells. We demonstrate the presence of a thapsigargin-sensitive cationic current, which is mainly carried by Na+. Moreover, in basal glucose concentration (5.6 mM), thapsigargin depolarizes the plasma membrane, producing electrical activity and increasing [Ca2+]i. The latter is prevented by nifedipine, indicating that Ca2+ enters the cell through L-type Ca2+ channels, which are activated by membrane depolarization. Thapsigargin also increased insulin secretion by increasing the percentage of cells secreting insulin and amplifying hormone secretion by individual beta-cells. Nifedipine blocked the increase completely in 5.6 mM glucose and partially in 15.6 mM glucose. We conclude that thapsigargin potentiates a cationic current that depolarizes the cell membrane. This, in turn, increases Ca2+ entry through L-type Ca2+ channels promoting insulin secretion.

Receptor-interacting protein 2 is a marker for resolution of peritoneal dialysis-associated peritonitis

There are no predictive factors for peritoneal dialysis-associated peritonitis; however, its resolution correlates with a cell-mediated Th1 immune response. We tested the hypothesis that induction of receptor-interacting protein 2 (RIP2), an assumed kinase linked with Th1 responses, is a useful marker in this clinical setting. Basal RIP2 expression was measured in human immune cells and during dialysis-associated peritonitis. RIP2 increased with bacterial toxin cell activation and the temporal profile for this differed depending on immune cell involvement in the innate or adaptive phases of the response. Importantly, RIP2 expression increased in peritoneal immune cells during dialysis-associated peritonitis and this upregulation correlated with clinical outcome. An early induction in peritoneal CD14(+) cells correlated with rapid resolution, whereas minimal induction correlated with protracted infection and with catheter loss in 36% of patients. These latter patients had higher levels of MCP-1 consistent with a delayed transition from innate to adaptive immunity. Our study shows that upregulation of RIP2 is a useful marker to monitor dialysis-associated peritonitis and in predicting the clinical outcome of these infections.

[Ductus closure in adults with the Rashkind device: comparative results]

INTRODUCTION

Catheter occlusion of the persistent ductus arteriosus with Rashkind device is an alternative to the surgical closure demonstrated in children, however a few results have been reported of occlusion in adults.

METHOD

From 1990 to 1996 in 127 patients with persistent ductus arteriosus undergoing occlusion by Raskind device. Two groups according age: 105 children (< 14 years) and 22 adults (> 14 years), were studied retrospectively. The results were analysed by immediate aortogram and follow-up at 24 hours, 6 and 12 months by color-Doppler echocardiograms.

RESULTS

The adults were frequently asymptomatic (86%) and with high incidence (59%) of silent ductus. Similar QP/QS (1.61 +/- 0.47 in adults vs 1.49 +/- 0.51) was calculated although pulmonary pressure was superior in children (12.50 +/- 2.97 vs 16.84 +/- 5.88 mmHg; p = 0.003). In group > 14 years the ductal anatomy favorable (Krichenko type A or B) was more frequent (91% vs 73%; p = 0.06) and ductal diameter significantly higher (3.03 +/- 1.50 vs 2.41 +/- 0.96 mm; p = 0.009). In adults 17 mm umbrella were used more frequently (91 vs 61%; p = 0.02). Absence complications (embolization, bacteremia, haemolysis, proximal stenosis of the left pulmonary artery) were found in adults against 4.72% in children. The occlusion were more effective in adults specially in early controls: 55% vs 34% (p = 0.09), 82% vs 69%, 91% vs 77% and 95% vs 83% (p > 0.10). Multivariate analysis identified age as an independent predictor of complete occlusion.

CONCLUSION

Our experience in transcatheter occlusion of persistent ductus arteriosus with Rashkind device in adults support the efficacy, safety and excellent early results despite higher incidence of silent asymptomatic ductus.

Effects of cyclosporin treatment on prolactin pulsatility in chronic hyperprolactinemic male rats

Neuroendocrine effects of cyclosporin (CsA) have been demonstrated, but the mechanisms involved are poorly understood. This work was designed to analyse (i) if chronic CsA administration could influence the episodic secretion of prolactin in adult male rats; and (ii) the effects of the chronic administration of the drug, in adult animals with elevated plasma prolactin levels. Male rats were implanted with one anterior pituitary gland under the kidney capsule or were sham-operated, at 30 days of age. Both pituitary-grafted and sham-operated rats were injected subcutaneously with vehicle or CsA (5 micrograms/kg/day) for 9 days beginning at the 60th day of age. In pituitary-grafted male rats, mean prolactin levels, absolute prolactin pulse amplitude and mean half-life of the hormone increased, while the pulse frequency and relative amplitude of the peaks decreased, as compared with sham-operated rats. CsA administration to sham-operated rats decreased the relative pulse amplitude of prolactin but increased the mean half-life of the hormone, the pulse duration and the mean hormone levels, as compared with rats of the same group treated with vehicle. However, CsA treatment to pituitary-grafted rats decreased mean prolactin levels and the absolute amplitude of its peaks and increased the relative amplitude of its pulses, whereas all the other parameters showed no change. When considering circulating values of prolactin in plasma from the trunk blood, CsA administration was followed by changes similar to those described when mean values of the serial samples were considered. These data suggest the existence of an interrelationship between elevated circulating prolactin levels and CsA, which probably takes place at the hypothalamic level, to regulate the pulsatile pattern of prolactin secretion in male rats, although a direct effect of the drug on the ectopic gland in pituitary-grafted male rats cannot be excluded.

Epithelioid hemangioendothelioma and multiple thoraco-lumbar lateral meningoceles: two rare pathological entities in a patient with NF-1

Epithelioid hemangioendothelioma (EHE) is a rare vascular soft-tissue tumour of intermediate malignancy. Neurofibromatosis type I (NF-1) is a genetic syndrome associated with soft tissue sarcoma and higher risk of developing neoplasia. Lateral meningoceles are uncommon entities, being mostly associated with NF-1. We report a case of a 31-year-old woman, with NF-1 and past history of right thalamic/peduncular astrocytoma WHO grade II, admitted to the Neurosurgery Department in December 2003 due to severe low back pain, irradiating to the left leg without a radicular pattern. Thoraco-lumbar magnetic resonance imaging (MRI) showed a large left posterior paravertebral expansive lesion, bilateral and multiple thoraco-lumbar lateral meningoceles and dural ectasias with scalloping of the vertebral bodies. Biopsy of the paravertebral mass lesion disclosed EHE. We present this case because of the novel association between NF-1 and EHE, and the unusual aggressiveness of the neoplasia. Additionally, we highlight the co-existence of bilateral and multiple lateral meningoceles.

Metabolism and anti-HIV activity of phosphoramidate derivatives of D4T-MP with variations in the amino acid moiety

The metabolism of different phosphoramidate prodrugs of d4T-MP, in which the phosphate group is linked to a phenyl group and the alkyl ester of an amino acid was studied in crude CEM cell extracts. Significant (80-100%) conversion to the amino acyl d4T-MP metabolite was obtained with derivatives containing L-alanine or methyl-L-aspartic acid. A lower degree of conversion was seen with derivatives containing L-phenylalanine, L-methionine, methyl-L-glutamic acid or L-leucine. Derivatives containing D-alanine, beta-alanine, glycine, L-valine or L-lactate showed no conversion to the amino acyl d4T-MP metabolite. Overall, there was a close correlation between the anti-HIV activity of these prodrugs and their conversion rate to the amino acyl d4T-MP metabolite. Our data suggest that the enzymes involved in the formation of the amino acyl d4T-MP metabolite have a rather stringent specificity for L-alanine as the amino acid moiety. In addition, these enzymes were found to be markedly species-dependent, their activities being highest in mouse serum, followed by guinea pig serum, but only minimal in human serum. Mouse serum therefore appears to be the medium of choice to isolate and identify the enzymes that are involved in the metabolism of these phosphoramidate prodrugs.

Marked inhibitory activity of masked aryloxy aminoacyl phosphoramidate derivatives of dideoxynucleoside analogues against visna virus infection

Lipophilic masked aryloxyaminoacylphosphoramidate derivatives of 2',3'-dideoxynucleoside (ddN) analogues with potent anti-HIV activity (i.e., stavudine [d4T], azidothymidine [AZT], dideoxycytidine [ddC], 3'thio-2',3'-dideoxy cytidine [3TC], dideoxyadenosine [ddA], and 2',3'-didehydro-2',3'-dideoxyadenosine [d4A]) activity were evaluated for their activity against visna virus (VV) in sheep choroid plexus (SCP) cells. The activity of several prodrug derivatives against VV proved markedly superior to that of the corresponding free ddN analogues. In particular, the d4A and ddA prodrug derivatives were exquisitely inhibitory in this model system (50% effective concentration [EC50], < or = 0.003 microM), and their anti-VV potency exceeded by at least 200-fold the antiviral potency of the corresponding free nucleosides. Marked differences were noted in the anti-VV potencies of several of the test compounds depending on the nature of the amino acid linked to the 5'-phosphate moiety, the nature of the nucleoside, or both. In view of the stability of the prodrugs in lamb serum, the VV infection model in lambs may be considered highly useful for investigating the in vivo antiretroviral efficacy of these type of drugs, particularly the d4T, ddA, and d4A prodrug derivatives.

Transient aphasic episodes due to hypoglycemia

A 58-year-old diabetic man suffered two episodes of hypoglycemia accompanied by isolated aphasia. Prompt resolution of the language disorder followed treatment with 50% glucose IV. The day following the first event the EEG demonstrated bitemporal delta activity, more prominent over the left hemisphere. EEG repeated two weeks after the second event showed residual left temporal slowing. The differential diagnosis between hypoglycemia and transient ischemic attacks in diabetic patients presenting with transient focal neurological deficit is emphasized.