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At least 847 records · Page 47Linked to original sources
PubMed1980

Malignant transformation of BALB/3T3 cells by residue organic mixtures from drinking water.

Malignant transformation of BALB/3T3 1-13 cells results following treatment with complex mixtures of residue organic chemicals from drinking water samples of five U. S. cities. The U. S. Environmental Protection Agency provided the residues which were obtained by liquid-liquid solvent extraction, and sorption-desorption on XAD-2 resin of samples concentrated by reverse osmosis from drinking water of Philadelphia, PA; New Orleans, LA; Miami, FL; Seattle, WA; and Ottumwa, IA. Transformation was observed using a focus formation assay following 72-hr exposure of cells to residues from one or more samples from each city. Malignancy of several transformed and normal clones was evaluated in athymic (nu/nu) mice. The usefulness of such a transformation assay in detecting potential carcinogenic compounds contained in complex mixtures and the evaluation of possible health effects of residue organics in drinking water are discussed.

Animals↗
PubMed1995

Technologies for in situ cleanup of contaminated sites.

Groundwater contamination by non-aqueous phase liquids (NAPLs) and denser than water non-aqueous phase liquids (DNAPLs) poses one of the greatest remedial challenges in the field of environmental engineering. Due to low water solubilities and aqueous diffusivities, conventional pump-and-treat technologies have a poor record of success in remediation of DNAPL contaminated aquifers. Better success has been found with the removal of volatile LNAPLs due to higher gaseous diffusivities, propensity for aerobic biodegradation, and ease of pumping and handling large quantities of gas. An evaluation of in situ cleanup technologies on the basis of their applicability to in situ treatment of NAPL contaminated aquifers is presented. Emphasis is placed on treatment of the separate phase occurring in the saturated zone. Soil washing, air sparging, biodegradation, electro-osmosis, enhanced steam extraction, stabilization/solidification, treatment walls, radio frequency heating, and containment systems and barriers are among the in situ technologies reviewed. In the context of the governing contaminant fate and transport processes, the relative merits of each technology are assessed on the basis of its theoretical background, field implementability, level of demonstration and performance, waste, technical and site applicability/limitations, commercial availability, and cost and residuals management.

Decontamination↗
PubMed1994

[Evaluation of bone mineralization in patients on maintenance hemodialysis].

Bone loss and bone formation and mineralization abnormalities resulting from disturbances in calcium and phosphorus metabolism are frequent in chronic renal failure. Haemodialysis permits long-term survival of patients with end-stage renal disease. This is the reason, why renal osteodystrophy became an important diagnostic and therapeutical problem. Very low occurrence of fractures among haemodialysed patients in our clinic, stimulated our efforts to elucidate the causes of this phenomenon. The aim of this study was to compare bone mineral densities in haemodialysed patients and healthy volunteers. 47 patients on maintenance haemodialysis (16 F, 31 M) and 55 healthy volunteers (33 F, 22 M) with normal renal function were investigated. Endocrinopathy or any other diseases that could cause changes in bone metabolism were excluded. Age distribution in both groups was similar. Patients maintained on low sodium and phosphorus diet additionally were supplemented with large doses of calcium carbonate. Haemodialyses were performed using reverse-osmosis water. BMD (Bone Mineral Density) was measured using QCT (Quantitative Computed Tomography) and was expressed as an average hydroxyapatite content in lumbar vertebraes L1-L4. The obtained results indicate high BMD of vertebral bones in haemodialysed patients from our Dialysis Department. BMD was similar to that observed in healthy volunteers. This could at least partially explain low occurrence (2 in 142 pts-years) of fractures in ou uraemic patients. However we were unable to point exactly the simple factor responsible for this positive phenomenon. We hope that introduction of our haemodialysis scheme can help patients to avoid renal osteodystrophy.

Adult↗
PubMed1995

Does impaired transcellular water transport contribute to net ultrafiltration failure during CAPD?

OBJECTIVES: To assess the contribution of transcellular water transport in net ultrafiltration failure during continuous ambulatory peritoneal dialysis (CAPD). DESIGN: Retrospective. SETTING: Renal Unit, Academic Medical Center, Amsterdam. PATIENTS: One group of 6 patients with clinical severe ultrafiltration loss and a group of 10 stable CAPD patients without ultrafiltration problems. INTERVENTION: In all patients, two peritoneal permeability tests were done within one week, using glucose 1.36% dialysate on one day and glucose 3.86% on the other day. Dextran 70 was used as a volume marker. RESULTS: The difference in net ultrafiltration between 3.86% glucose and 1.36% glucose dialysate was 569 +/- 51 mL (control) and 153 +/- 103 mL (poor ultrafiltration group; p < 0.005). The dialysate/plasma (D/P) concentration ratios increased in both groups with glucose 1.36%. When using 3.86% glucose, the D/P ratio decreased in the control group with a median minimum value one hour after completion of inflow. It is possible that sieving of sodium was due to transcellular water transport by crystalloid osmosis during the hypertonic dwell, as a dissociation between the transport of water and sodium is unlikely to occur in transport through the much larger intercellular pores. The D/P sodium ratio after one hour was related to the mass transfer area coefficient (MTC) of creatinine and the percentage of glucose absorption in the control group. No decrease in D/P ratio was found in the poor ultrafiltration group. This suggests impairment of transcellular water transport. No significant differences were present between both groups with regard to MTC creatinine (10.2 and 14.0 mL/min), glucose absorption (71% and 71%), effective lymphatic absorption rate (1.34 and 1.01 mL/min), and residual volume (248 and 178 mL). Only 1 patient in the ultrafiltration loss group continued with CAPD. The others had to be transferred to hemodialysis; 1 of them developed sclerosing peritonitis. CONCLUSION: The sieving of sodium during CAPD may be caused by transcellular water transport. Deficient sieving as assessed by the absence of a decreased D/P ratio after one hour of a hypertonic dwell suggests impairment of transcellular water transport. This is associated with severe ultrafiltration failure. It indicates that failure of transcellular water transport, possibly by glycosylation of specific proteins on the cell membrane, may be considered one of the causes of ultrafiltration failure during CAPD.

Biological Transport↗
PubMed1994

Streptomycin perfusion of the labyrinth through the round window plus intravenous streptomycin.

Streptomycin perfusion of the labyrinth through the round window membrane in the middle ear is a simple, safe, and effective way to stop the dizzy spells, fullness, and tinnitus of Ménière's disease without making the hearing worse. My results with 24 patients in the last 8 months are presented. Although the long-term effect of this operation remains to be seen, my experience with streptomycin perfusion of the labyrinth through the lateral semicircular canal leads me to believe these good results will be maintained in the future. Although the caloric response is not usually eliminated completely in the operated ear, it is reduced enough that the patient no longer has dizzy spells. Because the vestibular receptors are not completely destroyed, and the afferent and efferent nerves coming to and from them are undamaged, the patient compensates after this operation more quickly than when the vestibular receptors are completely destroyed by intramuscular or middle ear aminoglycoside, or when the afferent and efferent nerves of the vestibular receptors are cut as in labyrinthectomy or vestibular neurectomy. Hyaluronan is used to carry the streptomycin into the inner ear because it is known to penetrate the round window easily, and because being hygroscopic, it may reduce the amount of endolymph by osmosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Ear, Inner↗
PubMedDate not supplied

Zeta potential of hollow fiber dialysis membranes and its effects on hydrogen phosphate ion permeability.

To clarify ion transport, dialysis membranes are evaluated in terms of zeta potential calculated by the Helmholtz-Smoluchowski equation from data on streaming potential delta E and pressure drop delta P, depending upon the operating conditions at which the values are measured. The objective of the current study is to design an improved method for measurement of delta E and delta P of hollow fiber dialysis membranes and to clarify the diffusive permeability of hydrogen phosphate ion. A polytetrafluoroethylene cylindrical cell with an inside diameter of 14 mm and a height of 10 mm was packed with 2,000-3,000 pieces of hollow fibers, and glass filters were set on either side of the cell. Deaerated water purified by ion exchange and reverse osmosis with an electric conductivity of approximately 150 microS/m was caused to flow in the hollows at 293 K to determine delta E and delta P. A good linear relationship between delta E and delta P and the reproducibility of the data was obtained and is shown in Figures 5 and 6, demonstrating the utility of the improved method to measure delta E and delta P, and the validity of the Helmholtz-Smoluchowski equation to calculate zeta potential from data on delta E and delta P. Hydrogen phosphate ion permeability increased with zeta potential for the membranes at about the same rate as pure water permeability. This indicates that hydrogen phosphate ion permeability depends upon the charge and internal structure of dialysis membranes.

Dialysis Solutions↗
PubMed1993

The gentle art of feedback.

In itself giving feedback effectively is not difficult. However, it requires time, planning and good communication skills. It is labour-intensive. It is an essential part of supervision. Adequate supervision needs to be a high priority in all our teaching institutions. People do not learn by 'osmosis' as many claim. Learning can be accelerated and enhanced to a great degree by improving our feedback skills.

Education, Medical↗
PubMedDate not supplied

IV fluidmakers: preparation of sterile water for injection in a field setting.

Two approaches have been investigated for generating USP sterile, pyrogen-free water for injection (WFI) from potable water in the field. The first approach utilizes reverse osmosis (RO), ion exchange, a solid matrix filter containing activated carbon and zeta adsorbent, a final 0.2 microns pore size sterilizing filter and a device for transferring the WFI to an IV bag; prototype systems based on three different hand-operated RO units weigh 1.5-3.5 kg and are capable of producing WFI at rates of 1-10 L/hr. Parenteral solutions were made by adding WFI to an IV bag containing concentrated Ringer's lactate. The second approach, still in the breadboard stage, is similar but utilizes a larger ion exchange column in place of the RO unit and a multiport distribution head to fill a set of 18 1-L IV bags. This system, considered to be disposable, is capable of generating water of WFI quality at a fill rate of 0.5 L/min from a pressurized source.

Chromatography, Ion Exchange↗
PubMedDate not supplied

National surveillance of hemodialysis associated diseases in the United States, 1990.

To determine trends in several hemodialysis associated diseases and practices, the Centers for Disease Control (CDC), in collaboration with the Health Care Financing Administration (HCFA), performed a mail survey of chronic hemodialysis centers in the United States in 1990. Of 1,995 centers surveyed, 1,882 (94%) representing 140,608 patients and 36,907 staff members responded. As in recent years, the 1990 survey found that certain hemodialysis practices are increasing in frequency, including treatment of water with reverse osmosis and deionizer units; use of bicarbonate dialysate and high-flux dialysis; and reuse of disposable dialyzers (in 1990, 70% of centers reused dialyzers). Hepatitis B surface antigen (HBsAg) was present at low frequency in patients (incidence, 0.2%; prevalence, 1.2%) and staff (incidence, 0.04%; prevalence, 0.3%). Antibody to hepatitis B surface antigen was present in 20% of patients and 58% of staff, and was significantly related to levels of hepatitis B vaccine coverage. Pyrogenic reactions in the absence of septicemia were reported by 20% of centers and were associated with use of high-flux dialyzer membranes and reuse of dialyzers (particularly in centers where the maximum number of reuses was 40 or more). Septicemia among hemodialysis patients was reported by 49% of centers. Twenty-six percent of centers reported providing hemodialysis for patients infected with human immunodeficiency virus (HIV), and 1.1% of dialyzed patients had known HIV infection.

Ambulatory Care Facilities↗
PubMed1993

[A quality control for the culture system using endotoxin assays in human in vitro fertilization and embryo transfer].

The purpose of this study is to investigate the effects of endotoxin on human in vitro fertilization and embryo transfers (IVF-ET) and to evaluate a quality control system for a culture medium using endotoxin assays. Before the final water purification (in an ultra-pure water system with a depyrogen filter) of the medium, the sources of water were pre-purified as follows; (I) distillation-->deionization x 2, (II) distillation-->ultra-pure water system or (III) reverse osmosis system. The limulus amebocyte lysate gelation tests (sensitivities of 0.03 and 0.25EU/ml) were used to detect endotoxin in the medium and in pre-purified water (pre-water). No pregnancies occurred in the endotoxin-positive medium (endotoxin > or = 0.03EU/ml). The endotoxin-negative medium resulted in a 33.3% pregnancy rate and 13.4% implantation rate. No statistical differences in the implantation rate were found among these methods of pre-purification (I: 12.5%, II: 13.4% and III: 20.0%). Endotoxin was detected in all the pre-water between 0.25 and 4.0EU/ml. The clinical pregnancy rate (36.6%) and the implantation rate (16.9%) in pre-water of endotoxin < 0.25EU/ml were significantly higher than those (10.5% and 5.5%) in pre-water of endotoxin > or = 0.25EU/ml (p < 0.05). We confirmed that a very low concentration of endotoxin disturbed a human embryo implantation. Endotoxin assays, not only in the media, but also in pre-water before final purification are useful as a quality control for the IVF-ET program.

Culture Media↗
PubMed1996

[Renal disease and trace elements].

Correlation between renal disease and trace elements includes following two types; 1) Renal failure due to excess of trace element intake into the body, such as itai-itai disease or heavy metal intoxication. 2) Disturbances of trace elements in patients with chronic renal failure, such as aluminum dementia and aluminum-related bone disease. Itai-itai disease occurred by water pollution with cadmium. Cadmium causes Fanconi syndrome in the kidney and osteomalasia in person, especially in old women, who were living near the riverside. Recently, we have shown that an itai-itai disease model can be made using rats by long-term intravenous injection of cadmium chloride. In patients with chronic renal failure, aluminum dementia and aluminum related bone disease were reported. However, aluminum dementia has disappeared by using reverse osmosis system for making dialysate. Fluoride should be one of ions which must be paid attention, because excess of fluoride cause mottled tooth and osteosclerosis. It may be dangerous to add fluoride into tap water system for the purpose of preventing decayed tooth, because fluoride retention in the serum may occur in patients with chronic renal failure.

Animals↗
PubMed1995

Increased silicon levels in dialysis patients due to high silicon content in the drinking water, inadequate water treatment procedures, and concentrate contamination: a multicentre study.

BACKGROUND: Although silicon is considered as an essential element, little is known about the basic effects and clinical significance of increased concentrations of the element in dialysis patients. METHODS AND RESULTS: In a multicentre study we found silicon levels in haemodialysis (HD) patients to be markedly increased. In these patients silicon concentrations were significantly higher than those noted in subjects with normal renal function as well as in patients with chronic renal failure not yet in dialysis and patients treated by continuous ambulatory peritoneal dialysis (CAPD). Moreover we noted that in both HD and CAPD patients mean silicon levels differed from one centre to another. Also, was there in the HD population a significant difference in serum silicon levels among patients from different countries. In HD patients differences in serum silicon levels were either due to the use of silicon contaminated dialysis fluids or an increased oral intake of the element mainly originating from the high silicon content of the drinking water. Silicon contamination of the dialysis fluid was found to be due to either the use of reverse osmosis membranes that insufficiently retain the element during water treatment or by the addition of concentrates containing high amounts of silicon. Using a recently developed high-performance liquid chromatographic/atomic absorption spectrophotometric (HPLC/ETAAS) hybrid technique, we found silicon in serum to be present as a low-molecular-weight non-protein-bound component, which in the presence of a low silicon dialysate is adequately removed during treatment. CONCLUSIONS: The clinical relevance of increased serum silicon levels is not yet known and as such deserves further investigation. In view of the controversy that exists on the element's assumed protective as well as toxic role in the development of some (aluminium-related) neurodegenerative diseases and its vital role in bone formation, monitoring of the silicon levels in serum, tap water, and dialysis fluids might become important.

Aluminum↗
PubMedDate not supplied

[The fluorosis problem in Senegal: data evaluation and presentation of a new method for defluoridating the water supply].

Fluoride intoxication is a serious public health problem in Senegal. The concentration of fluoride ions in underground water in Senegal is higher than the acceptable standard (0.7 mg/l at 25 degrees C) varying between 5 and 15 mg/l according to the season. The hydrological pattern of fluoride ions in Senegalese water is presented. The high levels of fluoride ions are due to the presence of phosphate ores. The health problems associated with the ingestion of toxic doses (about 4 mg/l) are discussed. Epidemiological investigation shows that the intoxication in Senegal is serious. In addition to fluoride in drinking water, high levels are also found in food, particularly tea and vegetables. Nanofiltration is a low cost membrane-based process which can be used to eliminate fluoride from drinking waters. Also known as low pressure reverse osmosis, this process is selective for small molecules and ions. It can thus sterilize and partially demineralize water. Furthermore, it can require only small amounts of energy, such that it can be run from photoelectric cells.

Filtration↗
PubMedDate not supplied

Icodextrin: overview of clinical experience.

OBJECTIVE: To review all clinical studies and experience gained with icodextrin to date; primarily its use in peritoneal dialysis in patients with end-stage renal failure, but also its use as an intraperitoneal vehicle. DATA SOURCES: Peer-reviewed original research articles in the literature; abstracts from international scientific meetings; data generated from the compassionate use programme. STUDY SELECTION: All published studies to date are included, some 10-20 studies being included in this review. DATA EXTRACTION: Data have not been specifically extracted from studies; results have been described in the context of overall experience. RESULTS: Over ten years of clinical experience with icodextrin have now been accumulated, in both continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). A small number of patients have received icodextrin for over five years, with no loss of effect. Icodextrin produces sustained ultrafiltration over long dwells while being iso-osmolar, by the process of colloid osmosis. CONCLUSIONS: Icodextrin represents the first viable alternative osmotic agent to glucose, for use in solutions for peritoneal dialysis. It also has a potential use as a vehicle solution for intraperitoneal drug delivery.

Dialysis Solutions↗
PubMed1997

[Ornithine induced retinopathy in the rat--1. Histopathological study on the retinal pigment epithelium].

An intravitreal injection of a small amount of 1-ornithine hydrochloride damages the retinal pigment epithelium (RPE) selectively in monkey eyes. In this paper, we examined the rat eye and observed similar results. Clinically, retinal edema appeared immediately after injection and showed hyperfluorescence on a fluorescein angiograph after 3 days. Histopathologically, RPE showed marked swelling 3 hours after injection, then became necrotic and disappeared gradually. One month after injection, retinal structure was maintained in the area where RPE regenerated to cover Bruch's membrane, but in the area where RPE cells disappeared, the photoreceptor cells and choriocapillaris degenerated and finally disappeared. In the eyes injected intravitreally with NaCl solution of equivalent osmosis microvacuoles were seen but no necrotic change in RPE. Thus, a small amount of ornithine damaged RPE selectively, and induced disappearance of the photoreceptors and choriocapillaris secondarily.

Animals↗
PubMed1977

[Osmo-, iono- and volume receptors of the liver].

by dissecting very fine strands of the liver afferent nerves, in cats, it has been possible to record activity of single fibers during intraportal infusion of different test-solutions. Different fibers were found which responded specifically to increase in the intraportal volume, to change of the osmosis and of concentration of ions. The liver was found to have highly selective specific populations of receptors: mechano (volume)-, osmo-, Na+-sensitive and K+ sensitive receptors.

Animals↗
PubMed1996

[Experimental in vitro model of an artificial kidney--measurement of trace element levels using the ICP method. Preliminary studies].

Trace elements in blood serum is significantly changed in hemodialysed patients. The result of our experiment showed the manner and directions of the evaluated trace elements -Sr, Zn, Ni, Ba, B, Si, Mn and Cu movements. It was confirmed that reverse osmosis is efficient in the most tracers elimination, except Si, B, and Cu. The trace elements being present in the whole arrangement diffuse easily through the dialysers membrane used in our experiment, except Ni. In the membrane of the new, non-rinsed dialyser we detected Pb, Fe, V, Be, Ti and Al. It could possibly be the source of their contamination into the human organism. ICP-AES method of trace elements analysis reveals the possibilities of precisely, fast and simultaneous evaluation of big number various trace elements.

Hemodialysis Solutions↗
PubMed1997

Transport of water in proximal kidney tubules from whole tubules to single channels: length and section of the selectivity filter of aquaporin-1.

Proximal straight tubule (PST) were dissected from rabbit kidneys, held with crimping pipettes in a chamber bathed in a buffered mannitol isosmotic solution (MBS, 295 mOsm/kg). Tubule cell volume changes with time (dV/Adt) after steps in MBS osmolality (delta Cs) were monitored on line with an inverted microscope, a TV camera and an image processor. Reflection coefficients sigma and osmotic permeability coefficients, Pos, for several solutes were measured using two methods. Method 1: sigma was calculated from the delta Csiso of impermeant and permeant solutes at which (dV/Adt)t-->0 = 0 (i.e., by a null point method). It is denoted as sigma 1. sigma 1 = 1.00 for mannitol (M), raffinose (R), sucrose (S), glycerol (G), acetamide (A) and urea (U). With formamide (F), sigma 1, Formamide = 0.62 +/- 0.05. These findings confirm our previous value of dp = 4.5 A for the diameter of the selectivity filter of the basolateral PST cell membrane water channel AQP1. Method 2: PST were exposed for 20 s to MBS made hyperosmotic by addition of a delta Cs of 35 mOsm/kg of R, S, M, G, A and U. Cells shrunk within 500 ms of t = 0 to their osmometric volume and remained shrunk for the 20 s of the osmotic challenge. Pos was measured from the shrinking curves. P(os) = 3000 +/- 25 microns/s with R, S, M, G, A and U. Method 2 also allowed to calculate sigma, denoted as sigma 2. sigma 2 = 1.00 for R, S, M, G, A and U. By contrast, the shrinking curve produced by a delta Cs of 35 mOsm/kg F was 1/5th to 1/6th slower and smaller (i.e., subosmometric) than that produced by a delta Cs of 35 mOsm/kg R, S, M, G, A and U. Furthermore, with F cells did not remain shrunk but recovered their original volume within 3 s. P(os) (measured with F) is denoted as P(os)*, P(os)* = 480 +/- 30 microns/s. sigma 2, Formamide = 0.16 +/- 0.01. Use of sigma 1, sigma 2 and P(os)* values in Hill's equations for the bimodal theory of osmosis leads to n = 2-9. Where n is the number of water molecules single filling within the channel selectivity filter, whose length must lie within 6 to 27 A, a value significantly lower than our previous value calculated from the P(os)/Pd* ratio.

Animals↗