The Frequency of Germline BRCA and Non-BRCA HR-Gene-Variants in a Cohort of Pancreatic Cancer Patients

Germline DNA alterations affecting homologous recombination pathway genes have been associated with pancreatic cancer (PC) risk. BRCA2 is the most studied gene and affects the management of PC patients and their families. Even though recent reports have suggested a similar role of germline ATM pathogenic variants (PV) in familial PC, there is still a disagreement between experts on how it could affect patient management given the lack of proper PC risk estimates. We retrospectively analyzed the germline data of 257 PC patients among whom nearly 50% were sporadic cases. We showed similar frequencies of BRCA2 (4.9%) and ATM (4.4%) PV or likely pathogenic variants, which were not related to familial history. Based on our findings and that of the literature, we suggest including ATM gene among the panel of genes analyzed in PC patients pending the publication of prospective studies.

Le taux d’anticorps anti-COVID19 à distance de la troisième dose de vaccin en hémodialyse

Introduction

Les hémodialysés chroniques sont parmi les patients les plus vulnérables à l’infection COVID-19. La vaccination dans ce groupe à risque est absolument une priorité vitale. Cependant, la persistance d’anticorps à distance de la 3^e dose de vaccin n’est pas complètement établie en HD.

Description

Nous avons examiné le taux d’anticorps 10 mois après la vaccination complète. L’objectif secondaire est de comparer les taux d’IgG anti-SPIKE selon les différents types de filtres de dialyses.

Méthodes

Nous avons évalué la réponse à long terme d’un Vaccin anti-covid-19 (BNT162b2 mRNA COVID-19, Pfizer-BioNTech), chez 110 patients hémodialysés chroniques 10 mois après la vaccination complète. Le titre des anticorps neutralisant IgG contre la protéine S (Spike) est quantifié par ELISA, 10 mois après avoir reçu le schéma. Les facteurs associés avec le niveau de la réponse : (taux < 218 BAU/ml- Taux entre 506 et 218 BAU/ml et > 506 BAU/ml) sont identifiés.

Résultats

La réponse vaccinale a été observée chez 70 sur 110 patients après avoir appliqué les critères de l’exclusion. 84,3 % ont un taux d’IgG anti-SPIKE satisfaisant. 15,7 % ont un taux moins ou non satisfaisant. Les patients ayant eu un antécédent de SARS COV2 ont mieux répondu au vaccin. Nous avons constaté une association significative entre le filtre de dialyse et la réponse vaccinale, (p = 0,01). Un filtre PMMA était associé avec un taux d’AC IgG anti-spike >506 BAU/ml (Fig. 1).

Conclusion

En HD, la réponse globale au vaccin à base d’ARNm est de 84,3 %, 10 mois après le rappel. L’utilisation du filtre PMMA semble améliorer cette réponse.

Safety, Reactogenicity and Patient Perceptions of COVID-19 Vaccination in Solid Organ Transplant Recipients at a Quaternary Referral Center

Purpose

Solid organ transplant recipients (SOTR) are at high-risk for poor health outcomes following COVID-19. Several studies have evaluated the antibody response to the vaccine amongst SOTR, yet there is a need to better understand peri-vaccination reactogenicity and patient behavior in SOTR. Our study reports the side effects, safety and the patient perceptions of the Pfizer vaccine amongst our center's SOTR.

Methods

In this single-center study, SOTR (heart, kidney, liver, lung, combined) who received the Pfizer (BNT162b2) vaccine in February-March 2021 completed an online survey about their side effects (SE) after the first and second dose of the vaccine, co-morbidities, masking behaviors, breakthrough infection, and perceptions regarding sense of protection and safety after vaccination. Descriptive and logistical regression analyses were performed.

Results

The survey was sent to 550 SOTR, of which 210 SOTR completed it thus far. Median age is 62 years, 154 (72%) are males and 61 (28 %) are females. 81 (39%) experienced SE after both doses. After dose one, 53% patients experienced a SE, the most common being injection site pain (79%). After dose two, 53% patients experienced a SE, including injection site pain (61%) followed by systemic SE (39%). No patient hospitalization after either dose was reported. Within a 6-month period post vaccination, only 1 patient tested positive for COVID-19 after the first dose. Increased age reduced the risk for SE for both first and second doses (0.95 (0.92-0.97, p<0.001 and 0.96 (0.94-0.99), p<0.002). SOTR without diabetes had a significant increase in injection site pain (1.92 (1.05-3.49),p=0.033). For masking behaviors, 83% plan to continue masking in healthcare settings while 10% will no longer mask in any setting. Regarding sense of worry of receiving the vaccine, 66% did not feel worried while 10% felt very worried. After vaccination, 53% felt very protected while 15% did not feel protected at all.

Conclusion

In SOTR who received the Pfizer vaccine, 39% of patients reported side effects after both doses. Injection site pain was most common after first dose and systemic side effects were more after the second dose. The study reinforces the safety profile of the vaccine and SOTR with reactogenicity similar to other studies. Even after vaccination, majority of SOTR plan to wear masks in various settings.

The impact of insomnia disorder on adult attention-deficit/hyperactivity disorder severity: A six-month follow-up study

BACKGROUND AND OBJECTIVES

The longitudinal relationship between insomnia disorder and adult attention-deficit/hyperactivity disorder (ADHD) has been scarcely investigated. This study aimed to evaluate the relationship between the remission of insomnia disorder and adult ADHD clinical severity, psychiatric and medical comorbidities, and the health-related quality of life (HRQoL) in a 6-month follow-up.

METHODS

Ninety-two adult patients with ADHD and insomnia disorder (52.2% males; mean age 39.5 ± 11.0 years) were comprehensively assessed at baseline, 3 months, and 6 months of a follow-up period. The evaluation included semi-structured interviews (for ADHD and comorbidity assessment), the Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Epworth Sleepiness Scale. The diagnosis of ADHD and insomnia disorder was performed according to DSM-5 criteria. At baseline and follow-up, psychoeducation/sleep hygiene and, if necessary, pharmacological were prescribed for insomnia.

RESULTS

Eighty-seven patients completed the 6-month follow-up. Insomnia disorder remission was reported in 72.4% of cases and was related to a greater improvement in ADHD symptoms and severity throughout the follow-up period. Additionally, an improvement in psychiatric comorbidities and better HRQoL were associated with insomnia disorder remission.

CONCLUSION

The current study highlights that the treatment of insomnia disorder in ADHD adult patients may have an important role in the outcome of ADHD therapeutic approaches by reducing their severity.

Clearance of Hepatitis C Virus Prior to Lung Transplantation: A Case Report

Hepatitis C virus (HCV) continues to be considered a relative contraindication to lung transplantation due to concerns of progression of liver disease with the introduction of immunosuppression. Since the recent introduction of effective antiviral therapy for HCV, new approaches in the management of the HCV-positive recipient are being utilized in liver transplantation to clear HCV pre- and post-transplant. Herein, we report use of ledipasvir/sofosbuvir for HCV clearance prior to lung transplantation in a patient with usual interstitial pneumonia. Listing for transplant was delayed until completion of HCV treatment, and he subsequently required extracorporeal membrane oxygenation as a bridge to transplantation due to progressive hypoxia. With antiviral cure rates exceeding 90%, HCV should no longer be considered a relative contraindication to lung transplant, and timing of antiviral treatment should consider the progressive nature of the recipient's lung disease.

Ascorbic Acid Derivatives in Two Different Fractions of Uremic Toxins

The middle-molecular-weight uremic toxins which accumulate in uremic plasma seem to be associated with various uremic disorders such as uremic neuropathy and defects in the sodium pump. By a multi-step chromatographic method, two fractions of these toxins were isolated and studied because one inhibits microtubule formation in vitro (fraction 2-5), and the other impairs the sodium pump in living erythrocytes (fraction 2-3). An additional chromatographic method allows the separation of these fractions and isolation of two components: fractions 2-3-V and 2-5-III. Analyses by UV and 1H NMR spectrometry identified these compounds as two different ascorbic acid derivatives. 2-3-V is not yet totally identified and 2-5-III corresponds to ascorbic acid 2-sulfate. These two metabolites exert no toxic effects but they have the same chromatographic behavior as uremic toxins.

Sodium Pump Activity in Uremic Erythrocytes: A Microcalorimetric Study

Erythrocyte thermogenesis was studied by flow microcalorimetry in 25 healthy subjects and 27 uremic patients. The heat production (HP) from cells in plasma, decrease in HP induced by ouabain (a specific sodium pump inhibitor) and index of rate response to ouabain action were measured. HP was higher in uremic patients than controls. Sodium pump inhibition with ouabain induced the same decrease in HP in the two groups. The index of rate response to ouabain action was lower in uremic patients than in controls. The difference in total HP may be due to a different age distribution of erythrocytes. Mean sodium pump activity was identical in the two groups, but some patients had lower activity than controls. Ouabain seems to act more slowly in many patients than in controls, perhaps because of hindered binding of the inhibitor.

Using Ultrapure Water in Hemodialysis Delays Carpal Tunnel Syndrome

Since 1977, our patients have undergone chronic HD with ultra-pure dialysate (UPD), defined as having endotoxin levels below 0.008 ng/ml and less than 1 bacteria/ml of dialysate. We evaluated the incidence of carpal tunnel syndrome (CTS) in three groups of patients. Group I (GI), 84 patients, dialysed for 6.1 ± 3.2 years (mean ± SD) with UPD only; Group II (GII), 39 patients, first dialysed for 3.7 ± 2.3 years with non-UPD and afterwards for 8.4 ± 2.1 years with UPD; Group III (G III), 103 patients treated for 6 ± 5.9 years exclusively with non-UPD. All patients were dialysed with cuprophan or cellulose acetate membranes.

Results, expressed by Kaplan-Meier actuarial survival curves as the percent of patients without CTS, show that CTS occurred significantly less in GI than in GIII. This may be due to less stimulation of monocytes resulting from the absence of bacteria, endotoxins and pyrogens in the dialysate which would reduce the stimulation of cytokines release, interleukin 1 and 6, and tumor necrosis factor, known to stimulate β2 microglobulin synthesis.

Insecticidal activity of a Moroccan strain of Streptomyces phaeochromogenes LD-37 on larvae, pupae and adults of the Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

The Mediterranean fruit fly (medfly), Ceratitis capitata, is considered the most important fruit pest worldwide. Its management is mainly based on the use of chemical insecticides. Although these conventional pesticides are effective at high doses, they cause considerable human health and environment problems. Thus, the aim of this study was to assess insecticidal activity of Moroccan actinobacteria against C. capitata. A total of 12 preselected actinobacteria isolated from various Moroccan habitats were screened for their insecticidal activity against larvae, pupae and adults of C. capitata. Four actinobacteria isolates were significantly active against the first-instar larvae, and nine were active against the medfly adult, while no significant mortality was obtained against the third-instar larval and pupal stages. Among the selected isolates, the biological screening revealed that strain Streptomyces LD-37, which showed 99.4% similarity with Streptomyces phaeochromogenes, exhibited the maximal corrected larval mortality of 98%. Moreover, the isolates AS1 and LD-37 showed the maximum significant corrected mortality against adults of 32.5 and 28.2%, respectively. The crude extract obtained from a fermented culture of strain S. phaeochromogenes LD-37 was separated into six fractions by thin layer chromatography. Fractions F3 and F4 caused a significant corrected larval mortality of 66.7 and 53.3%, respectively; whereas the maximum reduction in adult emergence was obtained with fraction F4. This finding could be useful for utilizing S. phaeochromogenes LD-37 as an alternative to chemical insecticides in pest management of C. capitata.

Dynamic laryngeal narrowing during exercise: a mechanism for generating intrinsic PEEP in COPD?

INTRODUCTION

Patients with COPD commonly exhibit pursed-lip breathing during exercise, a strategy that, by increasing intrinsic positive end-expiratory pressure, may optimise lung mechanics and exercise tolerance. A similar role for laryngeal narrowing in modulating exercise airways resistance and the respiratory cycle volume-time course is postulated, yet remains unstudied in COPD. The aim of this study was to assess the characteristics of laryngeal narrowing and its role in exercise intolerance and dynamic hyperinflation in COPD.

METHODS

We studied 19 patients (n=8 mild-moderate; n=11 severe COPD) and healthy age and sex matched controls (n=11). Baseline physiological characteristics and clinical status were assessed prior to an incremental maximal cardiopulmonary exercise test with continuous laryngoscopy. Laryngeal narrowing measures were calculated at the glottic and supra-glottic aperture at rest and peak exercise.

RESULTS

At rest, expiratory laryngeal narrowing was pronounced at the glottic level in patients and related to FEV1 in the whole cohort (r=-0.71, p<0.001) and patients alone (r=-0.53, p=0.018). During exercise, glottic narrowing was inversely related to peak ventilation in all subjects (r=-0.55, p=0.0015) and patients (r=-0.71, p<0.001) and peak exercise tidal volume (r=-0.58, p=0.0062 and r=-0.55, p=0.0076, respectively). Exercise glottic narrowing was also inversely related to peak oxygen uptake (% predicted) in all subjects (r=-0.65, p<0.001) and patients considered alone (r=-0.58, p=0.014). Exercise inspiratory duty cycle was related to exercise glottic narrowing for all subjects (r=-0.69, p<0.001) and patients (r=-0.62, p<0.001).

CONCLUSIONS

Dynamic laryngeal narrowing during expiration is prevalent in patients with COPD and is related to disease severity, respiratory duty cycle and exercise capacity.

Calcium- and ROS-mediated defence responses in BY2 tobacco cells by nonpathogenic Streptomyces sp

AIMS

The early molecular events underlying the elicitation of plant defence reactions by Gram-positive bacteria are relatively unknown. In plants, calcium and reactive oxygen species are commonly involved as cellular messengers of a wide range of biotic stimuli from pathogenic to symbiotic bacteria. In the present work, we checked whether nonpathogenic Streptomyces sp. strains could induce early signalling events leading to defence responses in BY2 tobacco cell suspensions.

METHODS AND RESULTS

We have demonstrated that nonpathogenic Streptomyces sp. OE7 strain induced a cytosolic Ca(2+) increase and a biphasic oxidative burst in the upstream signalling events, leading to defence responses in BY2 tobacco cell suspensions. Streptomyces sp. OE7 also elicited delayed intracellular free scopoletin production and programmed cell death. In agreement with scopoletin production, OE7 induced accumulation of PAL transcripts and increased accumulation of transcripts of EREBP1 and AOX genes that are known to be regulated by the jasmonate/ethylene pathway. Transcript levels of PR1b and NIMIN2α, both salicylic acid pathway-linked genes, were not modified. Moreover, Streptomyces sp. OE7 culture filtrates could reduce Pectobacterium carotovorum- and Pectobacterium atrosepticum-induced death of BY2 cells and soft rot on potato slices.

CONCLUSIONS

New insights are thus provided into the interaction mechanisms between Streptomyces sp. and plants; Streptomyces sp. could be sensed by plant cells, and through cytosolic Ca(2+) changes and the generation of reactive oxygen species, defence responses were induced.

SIGNIFICANCE AND IMPACT OF THE STUDY

These induced defence responses appeared to participate in attenuating Pectobacterium-induced diseases in plants. Thus, Streptomyces sp. OE7 could be a biocontrol agent against Pectobacterium sp.

Clinical and bacteriological efficacy of 5-day telithromycin in acute maxillary sinusitis: a pooled analysis

OBJECTIVES

To compare the efficacy and tolerability of a 5-day course of telithromycin (800 mg once daily) with a 10-day course of telithromycin or standard comparators (amoxicillin-clavulanate 500/125 mg three times daily or cefuroxime axetil 250 mg twice daily) in patients with acute maxillary sinusitis (AMS).

METHODS

Data from three randomised double blind studies were pooled. The studies included patients with clinical symptoms of AMS and sinus X-ray findings of total opacity, air-fluid levels or mucosal thickening.

RESULTS

Pooled analysis of results for 5-day telithromycin revealed overall clinical cure rates of 83.6% (383/458 patients) at post-therapy (days 17-24) and 78.9% (330/418 patients) at late post-therapy (days 31-45) in the per-protocol population. Clinical cure rates at post-therapy were equivalent to those observed with 10-day telithromycin (82.5% vs 81.7%) or comparator treatment (80.9% vs 77.4%). Moreover, clinical cure rates exceeded 80% in subgroups of patients of interest, including those with severe infection and those fulfilling more stringent criteria for bacterial AMS. A satisfactory bacteriological outcome was achieved in 87.6% of patients. The 5-day telithromycin regimen was well tolerated.

CONCLUSIONS

Telithromycin once daily for 5 days offers effective treatment for AMS and is comparable to 10-day courses of standard treatments.

Risk factor clustering in hypertensive patients: impact of the reports of NCEP-II and second joint task force on coronary prevention on JNC-VI guidelines

INTRODUCTION

Although the association of hypertension with established risk factors has been noted in several population studies, the recent redefinition of dyslipidaemia, hypertension and diabetes calls for reassessment of the prevalence and pattern of risk factor clusters in essential hypertension.

OBJECTIVE

To analyse the risk factor profile of Israeli patients with essential hypertension seen by primary care physicians and in hypertension specialty clinics, based on current definitions of dyslipidaemia hypertension and diabetes and JNC-VI guidelines for the assessment of risk factors.

DESIGN AND SETTING

We analysed the risk profile of 324 Israeli hypertensive subjects using the JNC-VI risk table and risk grouping. A total of 122 consecutive patients were recruited from primary care clinics and 212 consecutive patients were recruited from a hospital based hypertension clinic.

RESULTS

Amongst hypertensive individuals with no known target organ damage, only 1.5% had no risk factors other than hypertension, whereas all hypertensives with coronary artery disease had additional risk factors. Of the six listed major JNC-VI risk factors (smoking, dyslipidaemia, diabetes, age, sex, family history of cardiovascular disease), hypertensive subjects without coronary artery disease (coronary artery disease-negative) had 3.02 +/- 0.10 risk factors, whereas hypertensive subjects with coronary artery disease (coronary artery disease positive) had 3.6 +/- 0.07 risk factors other than hypertension (P < 0.01). Dyslipidaemia defined by NCEP-II criteria was the most common associated risk factor identified in 93% of coronary artery disease-positive and 77% of the coronary artery disease-negative hypertensive subjects. The most common dyslipidaemic abnormality was an increased LDL cholesterol (79.2% of the cohort), followed by hypertriglyceridaemia (31.7%) and low HDL cholesterol (22.3%). Nevertheless, in nearly half of the coronary artery disease-negative patients, LDL cholesterol concentrations were within 30 mg dL-1 of the target levels. The most common dyslipidaemic variant was isolated hypercholesterolaemia (42%), whereas the syndrome X dyslipidaemic combination of hypertriglyceridaemia and low HDL was strikingly uncommon, observed in 2.8% of the coronary artery disease-positive and 0.8% of the coronary artery disease-negative patients.

CONCLUSIONS

(i) JNC-VI group risk A patients (no risk factors) comprise a very small minority in this cohort (< 5%); (ii) dyslipidaemia is exceedingly common with mild hypercholesterolaemia being the most prevalent variant and hypertriglyceridaemia with low HDL the least common form.

Combined beta FSH and beta LH response to TRH in patients with clinically non-functioning pituitary adenomas

OBJECTIVE

'Paradoxical' responses of LH, FSH, alpha-subunits and beta LH to TRH have previously been reported in individuals with clinically non-functioning pituitary tumours (NFT). The present study was designed to assess the in vivo and in vitro responses of beta FSH to TRH in NFT. We further examined the possibility that a TRH challenge with combined measurement of beta FSH and beta LH will identify a common anomalous secretory pattern in patients with NFT.

DESIGN, PATIENTS AND MEASUREMENTS

Forty patients with NFT underwent a standard TRH test (400 micrograms intravenously). Blood samples for the determination of beta FSH, beta LH, FSH and LH were collected prior to TRH as well as 15, 30, 45, 60 and 90 minutes following injection. Additionally, cultured adenomatous cells from eight to these patients were exposed to TRH in the absence and presence of octreotide and gonadotropin subunits were determined.

RESULTS

TRH elicited a marked rise in circulating beta FSH in 29 of 40 individuals and in beta LH in 28 of 36 patients with NFT. In a subgroup of eight individuals whose tumours were harvested during surgery and cultured for 7-21 days, TRH increased beta FSH or beta LH and alpha-subunit release in cultured adenomatous cells in all cases, including tumours from subjects not responding to TRH in vivo. In this subgroup of patients octreotide inhibited basal beta FSH secretion but not basal beta LH secretion both in vivo and in primary cultures of NFT cells. Both the in vivo and in vitro beta FSH, beta LH and alpha-subunit responses to TRH were entirely inhibited by octreotide. In all, 38 of the 40 subjects could be identified by either elevated basal beta FSH or beta LH levels and/or an abnormal rise in either beta FSH or beta LH in response to TRH.

CONCLUSION

The measurement of basal and TRH-stimulated beta-FSH and beta-LH levels identifies an abnormal hormonal secretory pattern in the vast majority (> 90%) of patients with clinically nonfunctioning pituitary tumours.

[Treatment of urinary bladder cancer--a retrospective analysis]

Data on 482 stage A-0--D2 bladder cancer patients referred between 1975-86 were analyzed. Prognosticators of survival were stage, histologic subtype and differentiation. 143 patients with disease localized to the pelvis (stage A-0--D1) received definitive radiotherapy with 60 Gy or more, and 25 underwent preoperative irradiation and cystectomy. Later, a group of 56 selected patients with stage B--D1, referred between 1988-1991, received neo-adjuvant MCV chemotherapy (methotrexate, cisplatin and vinblastine) preceding either definitive radiotherapy or surgery. The 2-year overall actuarial survival rates were similar: 63% for radiotherapy only, 72% for cystectomy and 68% for neo-adjuvant chemotherapy; they were also similar when broken down by stage and grade.

Treatment of muscle invasive bladder cancer. Is there a role for neoadjuvant chemotherapy?

PURPOSE

Because 5-year survival with advanced bladder cancer is still poor, the search for optimal treatment continues as dose the necessity of clarifying goals of treatment.

PATIENTS AND METHODS

We compared the outcome of 3 different but widely accepted treatment protocols for bladder cancer in order to find which, if any, was superior, with particular emphasis upon the performance of the newest treatment, neoadjuvant chemotherapy. Data on 224 bladder patients treated at our institution (1975 to 1991) with 1 of the 3 protocols was analyzed. Those protocols were: 1. radiotherapy > 60 Gy (143 patients); 2. low dose radiotherapy followed by cystectomy (25 patients); 3. chemotherapy followed by either definitive radiotherapy or surgery (56 patients). Because the latter group was also a chronologically newer group with a shorter possible follow-up, we compared all treatments on the basis of 2-year survival, using Kaplan-Meier life tables. We briefly reviewed those modalities which are bladder-sparing because of the significance to quality of life of this factor.

RESULTS

Two-year survival figures for the patients were: 63% for those who received only radiotherapy; 72% for those undergoing cystectomy: 68% for the group to whom neoadjuvant chemotherapy was administered. The differences were not statistically significant. However, 23% of those patients treated neoadjuvantly were alive with intact bladders at 2 years.

CONCLUSION

These results do not suggest that a superior survival advantage is associated with any of these 3 protocols and neoadjuvant chemotherapy, in particular, cannot be seen as conferring a new and important survival advantage. However, neoadjuvant chemotherapy followed by radiotherapy does permit bladder conservation and, given that life span will often be reduced, the importance of helping to keep the remainder of the patient's life as comfortable as possible, can hardly be overestimated.

Anaphylactoid reactions during hemodialysis and hemofiltration: role of associating AN69 membrane and angiotensin I-converting enzyme inhibitors

Over a 20-month period, we observed 15 anaphylactoid reactions in six patients undergoing hemodialysis and three others on hemofiltration with AN69 capillary dialyzers who were receiving angiotensin-converting enzyme (ACE) inhibitors. These reactions were severe in 11 cases. In eight patients, anaphylactoid reactions stopped when AN69 membrane was replaced by polysulfone membrane and ACE inhibitors were continued. In one case, reducing the dose of ACE inhibitors was sufficient to prevent new reactions. Anaphylactoid reactions did not occur in patients undergoing dialysis with another membrane (cellulosic or synthetic), nor in those on AN69 membrane without ACE inhibitor treatment. We conclude that back-filtration of endotoxin-contaminated dialysate does not play the main role in the origin of such reactions, since they occurred in patients on hemofiltration with sterile and pyrogen-free substitution liquids.

Sodium pump activity in uremic erythrocytes: a microcalorimetric study

Erythrocyte thermogenesis was studied by flow microcalorimetry in 25 healthy subjects and 27 uremic patients. The heat production (HP) from cells in plasma, decrease in HP induced by ouabain (a specific sodium pump inhibitor) and index of rate response to ouabain action were measured. HP was higher in uremic patients than controls. Sodium pump inhibition with ouabain induced the same decrease in HP in the two groups. The index of rate response to ouabain action was lower in uremic patients than in controls. The difference in total HP may be due to a different age distribution of erythrocytes. Mean sodium pump activity was identical in the two groups, but some patients had lower activity than controls. Ouabain seems to act more slowly in many patients than in controls, perhaps because of hindered binding of the inhibitor.

Ascorbic acid derivatives in two different fractions of uremic toxins

The middle-molecular-weight uremic toxins which accumulate in uremic plasma seem to be associated with various uremic disorders such as uremic neuropathy and defects in the sodium pump. By a multi-step chromatographic method, two fractions of these toxins were isolated and studied because one inhibits microtubule formation in vitro (fraction 2-5), and the other impairs the sodium pump in living erythrocytes (fraction 2-3). An additional chromatographic method allows the separation of these fractions and isolation of two components: fractions 2-3-V and 2-5-III. Analyses by UV and 1H NMR spectrometry identified these compounds as two different ascorbic acid derivatives. 2-3-V is not yet totally identified and 2-5-III corresponds to ascorbic acid 2-sulfate. These two metabolites exert no toxic effects but they have the same chromatographic behavior as uremic toxins.

Using ultrapure water in hemodialysis delays carpal tunnel syndrome

Since 1977, our patients have undergone chronic HD with ultra-pure dialysate (UPD), defined as having endotoxin levels below 0.008 ng/ml and less than 1 bacteria/ml of dialysate. We evaluated the incidence of carpal tunnel syndrome (CTS) in three groups of patients. Group I (GI), 84 patients, dialysed for 6.1 +/- 3.2 years (mean +/- SD) with UPD only; Group II (GII), 39 patients, first dialysed for 3.7 +/- 2.3 years with non-UPD and afterwards for 8.4 +/- 2.1 years with UPD; Group III (G III), 103 patients treated for 6 +/- 5.9 years exclusively with non-UPD. All patients were dialysed with cuprophan or cellulose acetate membranes. Results, expressed by Kaplan-Meier actuarial survival curves as the percent of patients without CTS, show that CTS occurred significantly less in GI than in GIII. This may be due to less stimulation of monocytes resulting from the absence of bacteria, endotoxins and pyrogens in the dialysate, which would reduce the stimulation of cytokines release, interleukin 1 and 6, and tumor necrosis factor, known to stimulate beta 2 microglobulin synthesis.

[Familial hyperkalemia syndrome (Gordon's syndrome)]

Hyperkaliema at 6 mmol/l was discovered in a 30-year old man during routine examination. Further investigations showed that the hyperkaliaemia was associated with hyperchloraemic acidosis, stimulable hyporeninaemia and relative hypoaldosteronism in relation to the hyperkaliaemia. Renal and adrenal functions were normal. The finding of 3 identical cases in a French family of 9 persons led to the diagnosis of Gordon's syndrome, a rare hereditary metabolic disorder with a controverted physiopathology.

Kinetic Modeling of Intracellular pH and Comparison with 31P NMR Experimental Values in Dialysed Uremic Patients

Changes in intra-erythrocytic pH values over time, during and after bicarbonate hemodialysis, were studied with 31P Nuclear Magnetic Resonance. Simultaneously, pH values of whole blood were obtained by a gazometric method. A two-compartment model appeared to be the simplest kinetic model to explain the shifts in proton concentrations in extra- and intracellular media. Non-linear regression was used to determine exchange constant values. There was a very good correlation between the experimental and calculated proton concentrations. This model can describe all patients but individual experimental constants must be determined. Under these conditions a single blood pH determination before dialysis will permit determination of the initial intra-erythrocytic pH and monitoring of intra-erythrocytic pH during hemodialysis.

Kinetic modeling of intracellular pH and comparison with 31P NMR experimental values in dialysed uremic patients

Changes in intra-erythrocytic pH values over time, during and after bicarbonate hemodialysis, were studied with 31P Nuclear Magnetic Resonance. Simultaneously, pH values of whole blood were obtained by a gazometric method. A two-compartment model appeared to be the simplest kinetic model to explain the shifts in proton concentrations in extra- and intra-cellular media. Non-linear regression was used to determine exchange constant values. There was a very good correlation between the experimental and calculated proton concentrations. This model can describe all patients but individual experimental constants must be determined. Under these conditions a single blood pH determination before dialysis will permit determination of the initial intra-erythrocytic pH and monitoring of intra-erythrocytic pH during hemodialysis.

High-resolution NMR studies of transmembrane cation transport in uremic patients

Cation transport in erythrocytes of some uremic patients is impaired. Most studies have focused on the defect of the erythrocyte Na+/K+ pump in these diseased states. Herein, this cation transport defect was studied by using nuclear magnetic resonance spectroscopy (NMR) which is a non-invasive method permitting study on living erythrocytes. Firstly, we verified that the Na+ transport defect in uremic erythrocytes was not due to non-specific causes such as membrane alteration or a modification of the intracellular metabolism. The proton relaxation data, determined using a paramagnetic doping method, are consistent with a lack of erythrocytic membrane damage in uremic patients. Also, 31P-NMR results showed that in our experimental conditions, uremic and normal erythrocytes exhibit similar variations of ATP level over time. Lastly, the use of anionic paramagnetic shift reagent in 23Na-NMR revealed a defect in the Na+/K+ pump of erythrocytes from uremic patients with high Nain concentration. This defect seems to be due to a reduced number of pump units and to the presence of an endogenous inhibitor in uremic plasma.

Kinetic modeling of intradialytic and interdialytic pH shifts during and after acetate and bicarbonate hemodialysis

A kinetic model involving intraerythrocytic and whole blood H+ concentrations during and after bicarbonate and acetate hemodialysis is proposed to account for experimental data. A two-compartment model appeared to be the simplest kinetic model to explain the decrease in proton concentration during bicarbonate hemodialysis and its increase between two dialysis sessions, whether acetate or bicarbonate. This model takes into account the hemoglobin buffer power and the cellular metabolic acidosis. During acetate hemodialysis, one must introduce a new compartment to explain the initial increase in H+ concentration in erythrocytes. This compartment, which generates protons, seems to correspond to the carbonic anhydrase cycle. The various parameters obtained show no significant variations between patients receiving bicarbonate hemodialysis. For acetate hemodialysis, the model describes equally well patients with a great initial increase in H+ concentration and those with a slight initial increase. The variations observed in the parameters are due mainly to the carbonic anhydrase compartment. It is suggested the magnitude of this initial increase and the degree of acetate intolerance are correlated.

Intraerythrocytic pH variations during hemodialysis: a 31P NMR study

Before hemodialysis, patients have an intraerythrocytic pH (pHi) and an extracellular pH, measured in whole blood (pHo), which are lower than those of healthy controls. During bicarbonate hemodialysis, pHi values continuously increase, approaching a normal value at the end of the session. Concomitantly, pHo values follow similar variations. During acetate hemodialysis, pHi values exhibit a steep initial decrease, reaching a minimum after about 15 minutes. Concurrently, however, pHo values decrease only slightly. This phenomenon seems to originate in the intraerythrocytic medium and might be due to a shift in intracellular CO2/bicarbonate equilibrium. This drop in pHi exhibits interpatient variability, suggesting that the magnitude of pH decrease would be correlated with the degree of the problems observed in some patients undergoing acetate hemodialysis.

23Na nuclear magnetic resonance study of Na+-K+ pump inhibition by a fraction from uremic toxins

An in vitro inhibitor of Na+/K+-transporting ATPase (EC 3.6.1.37) was isolated from uremic plasma and normal urine by liquid chromatography. A 23Na nuclear magnetic resonance study involving living erythrocytes showed that this inhibitor causes impairment of the Na+-K+ pump of intact erythrocytes. This finding may explain the high intra-erythrocytic sodium concentration in those uremic patients exhibiting a high concentration of this inhibitor. The presence of this same inhibitor in normal urine suggests that it may play a physiological role.

23Na nuclear magnetic resonance study of Na+-K+ pump inhibition by a fraction from uremic toxins

An in vitro inhibitor of Na+/K+-transporting ATPase (EC 3.6.1.37) was isolated from uremic plasma and normal urine by liquid chromatography. A 23Na nuclear magnetic resonance study involving living erythrocytes showed that this inhibitor causes impairment of the Na+-K+ pump of intact erythrocytes. This finding may explain the high intra-erythrocytic sodium concentration in those uremic patients exhibiting a high concentration of this inhibitor. The presence of this same inhibitor in normal urine suggests that it may play a physiological role.

Sequential sodium therapy allows correction of sodium-volume balance and reduces morbidity

We investigated whether individually adjusting Na+ dialysis levels (Na+Di) combined with Na+ and UFR (ultrafiltration rate) programming, and a sodium/volume model (sequential sodium therapy, SST) can improve the end stage renal failure (ESRD) patient's homeostatic equilibrium intra- and interdialytically. One hundred and fifty patients were included in the study over a one year period. The results show that the patients are divided into two groups: 50 patients respond according to the sodium/volume model developed by F. Gotch [1983]. In this group it is possible to predict pre- and post dialysis plasma Na+ concentration (Na+o, Na+t) as a function of Na+Di and it becomes possible to choose Na+Di to allow Na+o and Na+t to virtually coincide, eliminating severe shifts in plasma tonicity. In the second group two subgroups can be distinguished: excess Na+ or excess H2O post dialysis, without possible correction at a single sodium level. SST corrects sodium/volume balance in this group by using sequential intermittent hypo or hypertonic dialysate, combined with fluid removal adapted to each episode. In both groups there was a significant improvement in the clinical condition of the patients who previously were less equilibrated. It is possible to conclude that SST improves tolerance intradialytically and achieves better equilibrium interdialytically. Implementation of SST requires precise control of the concentrate and the water, and equipment adapted for accurate, programmable sequential control of Na+Di and ultrafiltration rate.