Scaling the temperature-dependent boson peak of vitreous silica with the high-frequency bulk modulus derived from Brillouin scattering data.

The position and strength of the boson peak in silica glass vary considerably with temperature T. Such variations cannot be explained solely with changes in the Debye energy. New Brillouin-scattering measurements are presented which allow determining the T dependence of unrelaxed acoustic velocities. Using a velocity based on the bulk modulus, scaling exponents are found which agree with the soft-potential model. The unrelaxed bulk modulus thus appears to be a good measure for the structural evolution of silica with T and to set the energy scale for the soft potentials.

[Surveillance of infections in chronic hemodialysis patients]. / Surveillance des infections chez les hémodialysés chroniques en centre.

OBJECTIVE: To confirm rates of infections from a previous survey in chronic hemodialysis patients; to get information about incidents and manipulations of vascular access-site, number and reasons of hospitalisation; to asses a relationship between the frequency of vascular access-site infections (VASI) and quality of care during the procedures of vascular access-site use. DESIGN: Prospective, multicenter survey performed from February 2000 to January 2001, including all patients underwent chronic hemodialysis in 5 participating centers. Standardized definitions used and different clinical and biological risk factors recorded. RESULTS: 429 patients for a total of 4273 dialysis months (DM) were enrolled. 245 infections in 164 infected patients were reported. The overall rate was 5.73 infections per 100 DM (18 VASI, 25 bacteraemia, 84 respiratory, 29 urinary tract, 1 endocarditis and 88 other infections). 50% of infections were microbiologically documented. 19 of 21 antibiotics resistant microorganisms were meticillin resistant Staphylococcus aureus. Compared to the incidence rate of fistula (0.05 per 1000 days of follow-up) or prosthesis related VASI (0.11), the incidence rate of catheter related VASI (0.65) was significantly higher. Poor hygiene and duration of catheter use were the significant risk factors for VASI showed by logistic analysis regression. VASI and bacteraemia occurred more frequently after incident or manipulation of the vascular access-site. The decrease of VASI between the 2 periods of survey was significantly higher in centers having reduced the catheter use and implemented written protocols. CONCLUSIONS: This second period of surveillance has confirmed the frequency of infections rate in chronic hemodialysis patients and particularly bacteraemia and VASI. This study has allowed to establish risk factors for infections and showed that VASI in hemodialysis are related to factors in part preventable.

Observation of the onset of strong scattering on high frequency acoustic phonons in densified silica glass.

The linewidth of longitudinal acoustic waves in densified silica glass is obtained by inelastic x-ray scattering. It increases with a high power alpha of the frequency up to a crossover where the waves experience strong scattering. We find that alpha is at least 4, and probably larger. Resonance and hybridization of acoustic waves with the boson-peak modes seems to be a more likely explanation for these findings than Rayleigh scattering from disorder.

[Evaluation of the needs of a population of hemodialysis patients in Rhône-Alpes]. / Evaluation des besoins en soins d'une population de patients hémodialysés en Rhône-Alpes.

The evaluation of the needs of patients with terminal renal insufficiency is necessary to determine the appropriate care programme. An evaluation of the medical and nursing needs, as well as those related to handicap (a total of 47 items) was undertaken on all hemodialysis patients in the Rhône-Alpes region. Only 34.4% were free of co-morbidity and 35.7% of significant handicap, 63.7% needed no other nursing care than that related to supervision of the dialysis and 16.9% were free of all the conditions studied. The patients treated in the centre required care needs than those treated in all other structures. The autodialysis population differs from that treated at home by a greater need for care due to handicaps, and from that treated in a dialysis centre by a lesser degree of handicap and less need for medical treatment. A level of theoretical unsuitability (needs incompatible with the statutory provisions for each type of treatment) was defined: it concerns 5% of the population in a dialysis centre and to 33% of the population on home dialysis. The needs evaluation grid could be used to quantify the requirements of a dialysis population and to arrange for the necessary resources.

[A tool to predict the resources necessary for the whole hemodialysis population]. / Un outil de prédiction des moyens requis pour l'hémodialyse à l'échelon d'une population.

Predicting the resources necessary for the treatment of terminal renal insufficiency requires an understanding of the needs of the whole dialysis population. This study evaluates the advantages of a complete evaluation grid for care needs (CG, 47 items) compared with a simplified version (SG) and with the data obtained from REIN (R) as a tool for predicting the required resources. Compared to CG, the two other classifications under-estimate the level of care needed and the prevalence of patients who have at least one condition resulting in an 'excess' of needs. In a system with three types of structures, the theoretical distribution of patients according to the CG is: in structure A (permanent medical presence): 43.4% (vs 39 for SG and 21% for R); in structure B (intermediate): 34% (vs 31.5 and 24.7% respectively); and in structure C (independent): 22.3% (vs 29.5 and 53.5%) of patients. The care needs scores of populations assigned by R to home dialysis are incompatible with the resources allocated to it. With a certain number of adjustments and qualifications, a population study using a simplified needs grid could enable a prediction of the resources which need to be provided. The patients' records which take precedence in the future REIN should be modified in order to make possible a regular evaluation of the appropriateness of the resources allocated.

Olmsted syndrome: report of two new cases and literature review.

Olmsted syndrome is a rare keratinization disorder; 18 cases have been published so far. It associates a mutilating cogenital palmoplantar keratoderma with periorificial erythematokeratotic lesions. We report herein two new unrelated male children with Olmsted syndrome (OS), one of whom was studied by light and electron microscopy. Our histological, immunohistochemical, and ultrastructural findings suggest that this disease is related to epidermal hyperproliferation. We present herein a review of the twenty cases published so far and discuss the major clinicopathological and genetic features of this disease.

[Dialysis in octagenarians: search for mortality risk factors. Consecutive series of 30 patients]. / La dialyse des octogénaires: recherche de facteurs de risque de mortalité. Série consécutive de 30 patients.

OBJECTIVE: To assess renal replacement therapy in elderly subjects aged 80 years or more in order to depict factors predicting mortality. PATIENTS AND METHODS: We retrospectively studied 30 consecutive patients at the time of starting dialysis from January 1995 to August 1995 and followed this population though March 1996. RESULTS: Only past ischemic heart disease and emergency situations were emphasized as predictor factors of mortality risk. No difference according to mortality between hemodialysis and peritoneal dialysis subgroups was found. CONCLUSION: Excepting usual contraindications for uremic populations, no objective medical criteria are at present time sufficient for excluding chronic renal replacement therapy in very old patients. However, its effect on quality of life must be estimated in order to determine the cost/benefit ratio.

Direct determination of blood recirculation rate in hemodialysis by a conductivity method.

Blood recirculation is one of the key factors of decreasing dialysis efficiency. Determination of recirculation rate (R) is necessary to optimize effective dialysis delivery and to monitor vascular access function. R can be directly measured by a conductivity method in paired filtration dialysis (PFD), a double-compartment hemodiafiltration system that permits direct access to plasma water via the ultrafiltration stream. Measurement of R, in this system, involves the first of two conductivity sensors integrated in a urea monitor (UMS, BelIco-Sorin, Mirandola, Italy), and two saline injections. The rise in conductivity (deltaC1) induced by a 2.7 ml bolus of hypertonic saline 20% (mg/dl) in the arterial line serves for calibration, and is followed by an equivalent injection into the venous line, giving rise to deltaC2. The ratio deltaC2/deltaC1 equals R. A comparison between R values obtained with this method and with the low-flow technique in 31 chronic dialysis patients during 138 PFD sessions is reported. Mean R+/-SD by the conductivity method was 5.1+/-2.0 and 5.7+/-2.0% after 65 and 155 minutes of PFD (correlation coefficient, r = 0.75), whereas it was 6.4+/-4.9% and 5.5+/-4.6% after 30 sec of low blood pump flow for urea and creatinine markers, respectively (r = 0.35). After 120 sec of low flow, mean R increased to 9.0+/-5.1 and 8.8+/-4.6% for urea and creatinine, respectively (r = 0.45). Considerable discrepancies were found in R values measured simultaneously with the two blood markers. Statistically significant differences were found between the two measurement modalities (blood-side and conductivity); the correlation coefficients (r) varied between 0.28 and 0.41. The observed differences in mean R results do not seem considerable from a clinical perspective. The best agreement between blood-side and conductivity R measurements was obtained with Rcreat after 30 sec of low flow. Overall, a wider distribution was found in R values from blood-side determinations, most likely consequent to variability in the dosing method. The conductivity method appears more accurate and simple in assessing total R, and can be readily automated and integrated into the dialysis machine. The authors, therefore, recommend evaluation of R using methods not based on chemical blood concentration values.

[Mesenteric ischemia in hemodialyzed patients]. / L'ischémie mésentérique chez le sujet dialysé.

OBJECTIVES: Mesenteric ischemia is uncommon in the general population but is frequently encountered in chronic hemodialysis patients. We present here four cases which occurred in our unit within one year while only six cases had been observed in the preceding twenty years. OBSERVATIONS: Four chronic hemodialysis patients (age: 57 to 76 years) with renal failure due to diffuse atheromatous disease, presented non-occlusive mesenteric ischemia. One patient died and one underwent resection of the colon. For the final two patients, prophylactic therapy was initiated. DISCUSSION: Mesenteric ischemia is a severe condition which appears to occur more frequently in end-stage renal disease. In the chronic hemodialysis patient excessive ultrafiltration or a too rapid filtration rate can favor ischemia. Prophylactic measures must be taken at the first sign of ischemia, especially since clinical and biological features of mesenteric ischemia remain largely non-specific.

[Twenty one years of hemodialysis in a patient with primary hyperoxaluria]. / Vingt et un ans d'hémodialyse chez un patient atteint d'hyperoxalurie primitive.

We report a male patient with primary hyperoxaluria from childhood who survived more than 21 years on conventional haemodialysis. Despite the severity of his bone disease, he was married and actively employed up until 2 years before his death. His condition really worsened a few months before his death. He presented with only renal and bone involvement and had hardly any cardiovascular complications, that was probably a reason for his prolonged survival. Such an evolution is very unusual and we speculate that the length of haemodialysis sessions in addition to the large surface of the membrane probably contributed to such an outcome. During the time period on HD, anemia was transiently controlled by recombinant erythropoietin despite oxalate involvement of the marrow. He was refused a liver-kidney transplant and died from malnourishment at 43 years of age. To our knowledge, such an outcome has not yet been reported. It shows that careful prolonged hemodialysis sessions should be helped in admet patients without severe cardiovascular involvement.

[Ophthalmologic manifestations of dialysis. Retrospective study on 81 patients]. / Manifestations ophtalmologiques du dialysé. Etude rétrospective sur 81 patients.

In this work, we looked at the results of a retrospective study carried out in our unit on the ocular manifestations in the dialysed chronic renal failure patient. Eighty-one of our 189 patients had an ophtalmic examination. Thirty-six showed a retinopathy, 26 suffered from a corneoconjunctival alterations, 19 from a cataract, 6 a vascular thrombosis, 4 a glaucoma and one motor-ocular paralysis. There was no significant difference for age and sex between the 81 patients and the group of 108 who did not have an ophtalmic examination. But this difference was positive for duration of time on dialysis (p = 0.01). There is a correlation between the presence of a cataract and the age of the patients (p = 0.01). There was no link between the different types of ophtalmic problems on the one hand, and the age, sex, time on dialysis, type of dialysis, original nephropathy, hypertensive history or anterior renal transplantation on the other hand.

[What are the prerequisites for establishing a peritoneal dialysis treatment? (Training center, the place of private practice nurses, the administrative structure of management)]. / Quels sont les pré-requis à la mise en place d'un traitement par dialyse péritonéale? (Le centre de formation, la place des infirmiers libéraux, les structures administratives de gestion).

In spite of the same quality of results in term of five year survival by peritoneal dialysis (PD) compared to hemodialysis (HD), this method of renal substitutive therapy is concerning no more than 7% ESRF patients in France. What structural inadaptations could account for such striking differences between the two modalities? We present here the results of a French multi-center survey and our proposal for improving the actual tendency. Nonante PD centers were included representing a total number of 1592 patients, among them 90% were on continuous ambulatory peritoneal dialysis. We could observe a predominant proportion of public district services and non-profit associations. Sixty per cent of PD units were part of hemodialysis centers and 20% were totally independent. Patient mean age was very old, with limited autonomy, necessitating frequent visits of liberal nurses for 57% patients. We suggest to reinforce the role of non-profit making associations and to reorganize the existing centers on two levels in term of facilities, personal services and on functional modalities according to the number of treated patients.

[Aggravation of anemia in a hypertensive hemodialysis patient by captopril treatment]. / Aggravation de l'anémie chez un sujet hémodialysé hypertendu par un traitement au captopril.

We report here the case of an hypertensive chronic hemodialysis patient treated by captopril. Captopril treatment has been effective in normalizing blood pressure but induced a severe anemia necessitating frequent transfusions. Captopril withdrawal eliminated transfusion needs.

Reversal of selenium and zinc deficiencies in chronic hemodialysis patients by intravenous sodium selenite and zinc gluconate supplementation. Time-course of glutathione peroxidase repletion and lipid peroxidation decrease.

In six chronic dialyzed uremic patients, an intravenous sodium selenite (Se 50 micrograms during 5 wk and then 100 micrograms) and zinc gluconate (Zn 5 mg) supplementation was performed during 20 wk at each dialysis session three times weekly. Before supplementation, plasma Se and Zn, plasma and erythrocytes (RBC) antioxidant metallo-enzymes glutathione peroxidase (GPX), and superoxide dismutase (SOD) were significantly decreased, whereas lipid peroxidation (as thiobarbituric acid reactants TBARs) was increased. To obtain a significative change in plasma selenium, we had to use an Se dose of 100 micrograms/dialysis session. Then, treatment-increased plasma Se (from 0.58 +/- 0.09 to 0.89 +/- 0.16 mumol/L) led to a repletion of RBC-GPX (from 29.6 +/- 6 to 43 +/- 5.8 U/g Hb) and increased plasma GPX levels (from 62 +/- 13 to 151 +/- 43 U/L). Plasma Zn and RBC-SOD did not vary significantly. The change of TBARs was not observed between wk 1 and 4. They decreased significantly between wk 4 (4.80 +/- 0.21 mumol/L) and wk 20 (4.16 +/- 0.26 mumol/L). We noted a low correlation between TBARs and plasma GPX. A strong correlation was observed between Se and plasma GPX. The reversal of Se deficiencies should reduce oxidative damage observed in these patients.

Effects of a heterogeneous set of xenobiotics on growth and plasma membranes of mammalian and fungal cell cultures.

A comparison of the toxicity of 45 selected, heterogenous substances on two test organisms of different taxonomic levels, the yeast Saccharomyces cerevisiae and Chinese hamster ovary (CHO) cells, was made. In addition, effects on the yeast plasma membrane-integrated H(+)-ATPase and on the CHO adenosine uptake system were investigated. For all test systems, log EC50 values highly correlated with log EC20 values. Good correlations were obtained between CHO proliferation rate and yeast growth rate (r = 0.80). However, CHO cells were about four times more sensitive than yeast. A good accordance was also found between effects on yeast cell growth and on the H(+)-ATPase, indicating a plasma membrane impairment as a major cause of cytotoxicity. These findings were supported by correlations of log EC20 values with the log Pow as a measure for lipophilicity. Although the test systems demonstrated different dependencies, the main trend reflected an increasing toxicity with increasing lipophilicity. Comparisons with data from in vivo test systems suggest that these in vitro test systems could be implemented for initial estimation of basic toxicity and the detection of outliers thereby reducing the number of tests with higher animals.

Interaction of xenobiotics on the glucose-transport system and the Na+/K(+)-ATPase of human skin fibroblasts.

The effects of individual and combined xenobiotics on functional properties of the plasma membrane of human skin fibroblasts were investigated. Good correlations between toxic effects on the D-glucose transport system or the Na+/K(+)-ATPase and the lipophilicity of the substances could be observed. The linear regression coefficients plotting log EC20 values (doses, leading to 20% inhibition) versus log Pow (octanol/water partition coefficient) were r = 0.95 (P less than 0.05). The combination of lipophilic with less lipophilic xenobiotics, such as pentachlorophenol with 4-chloroaniline, leads to additional effects. However, when the detergent sodium dodecyl benzenesulfonate was combined with the herbicide 2,4-dichlorophenoxyacetate (2,4-D), the toxic effect of 2,4-D on the Na+/K(+)-ATPase decreased considerably. The results support in general the assumption that the inhibition of integral functional proteins is based on an accumulation of xenobiotics in the plasma membrane, probably due to the enhanced membrane fluidity. Thus, the basic toxicity of xenobiotics can be predicted by their physicochemical properties.