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At least 757 records · Page 42Linked to original sources
PubMed1989

Zinc uptake in human seminal spermatozoa: characterization and effects on cell membranes.

Human ejaculated spermatozoa take up zinc in a time- and concentration-dependent manner. The kinetics of 65Zn2+ uptake is suggestive of an at least partly carrier-mediated transport. The lack of effect of the respiratory chain inhibitor antimycin A could mean that mitochondrial ATP is not required as an energy source for the uptake. The failure of nonpermeant SH reagent mersalyl to modify zinc uptake indicates that functional membrane sulfhydryl groups are not involved in the process. A dose-dependent inhibition of 65Zn2+ uptake was induced by the "anticalmodulin" drug trifluoperazine, suggesting that the calcium-binding protein calmodulin could have a role in zinc transport. In in vitro experiments this cation brought about a powerful effect in protecting the spermatozoa from being damaged by hypo-osmosis.

Antimycin A↗
PubMedDate not supplied

Phagolysosomal morphology and dissolution of cobalt oxide particles by human and rabbit alveolar macrophages.

The effect of phagolysosomal size on dissolution of cobalt oxide particles was evaluated in two different macrophage systems: alveolar macrophages (AM) of human smokers with phagolysosomes enlarged by ingested cigarette smoke products, and rabbit AM incubated in vitro with sucrose, which causes swelling of the phagolysosomes by osmosis. Human AM from smokers and nonsmokers were studied in vitro. There was no significant difference in particle dissolution between AM obtained from smokers and nonsmokers, although there was a clear difference in the morphological appearance of AM, including significantly larger phagolysosomes in smokers. Rabbit AM were incubated for 24 or 72 h with or without 80 mM sucrose in the medium. The sucrose-treated cells had 3-4 times larger phagolysosomes than untreated cells, with no major change in phagolysosomal pH. The increased size of the phagolysosomes did not affect the ability of the AM to dissolve cobalt oxide particles. Furthermore, rabbit AM showed the same ability as human AM to dissolve the cobalt oxide particles, in spite of the fact that they had markedly smaller phagolysosomes. Another difference between human and rabbit AM was that phagolysosomes in human AMs increased in size with time in culture, while rabbit AM phagolysosomes decreased in size.

Adult↗
PubMed1994

Cellular aspects of transvascular exchange: a 40-year perspective.

Study of the microcirculation began with microscopic anatomy in the 17th century, but it was not until the mid-19th century that the concept of microcirculatory exchange was developed, in association with the great expansion in knowledge of physical chemistry and cell biology. In the first half of the 20th century, the roles of diffusion and osmosis (ultrafiltration) were put on a quantitative foundation and the physiological basis for regulation of the microcirculation was established. During the past 40 years, our understanding of transvascular exchange has been deepened and widened through two major developments: 1) the application of electron microscopy to the study of microvascular structure and 2) the use of sophisticated physical and mathematical models of passive transport processes to analyze and interpret experimental data. In the past few years, the focus of microvascular research has been returning to cell biology and the role of endothelial cells in controlling transvascular exchange. The 21st century holds promise of many exciting new developments.

Animals↗
PubMed1993

An outbreak of Heinz body positive hemolytic anemia in chronic hemodialysis patients.

During the four month period, from December 1988 to March 1989, there was an outbreak of Heinz body positive hemolytic anemia in 34 patients undergoing hemodialysis in a 500-bed hospital, Seoul, Korea. The episodes of hemolysis were not reduced by changing the charcoal column and reverse osmosis system, or by adding ascorbic acid to the dialysate. The concentrations of nitrate, copper, aluminum and zinc in the treated water were all within the standards for hemodialysis. The chloramine concentration of the treated water was over 0.6 mg/L, markedly exceeding the allowable level of 0.1 mg/L. This high level of chloramine was proved to be due to the contamination of the water source by raw sewage. After we changed the source of water supply to another, no more episodes of hemolytic anemia occurred. It is concluded that chloramine is one of the major contaminants causing dialysis-induced hemolytic anemia and regular determinations are necessary, especially during winter and dry seasons.

Anemia, Hemolytic↗
PubMed1994

[Immunohistological investigation of proteoglycans and collagens in experimental facial nerve palsy].

The extracellular matrix (EM) has various important functions. The basement membrane, which is part of the EM, has major components such as type IV collagen (C-IV), laminin, and heparan sulfate proteoglycan (HSPG). The basement membrane controls osmosis of various molecules, as well as the approach of growth factors, hormones, and neurotransmitters, etc. to the cellular surface. Thus, in this study, distributions of HSPG and C-IV and associated changes were investigated immunohistologically using monoclonal antibody against HSPG and polyclonal antibody against C-IV in mice models of experimental facial nerve palsy. In normal tissues, HSPG and C-IV were stained slightly in the basement membrane of the myelin sheath, moderately in the perineurium and slightly in the epineurium of the nerve. In the model of extratemporal facial nerve palsy, these stained components became more apparent, i.e., moderate or stronger, in the basement membrane of the myelin sheath, one week after the experiment. HSPG was perceptibly stained even at a later period of observation, while staining of C-IV became weak in the early period of observation. In the model of intratemporal facial nerve palsy, the staining of HSPG and C-IV of the basement membrane in the myelin sheath, also became more apparent (became moderate) one week after the experiment. But in this model, the degree of staining in the basement membrane was uniformly increased throughout the nerve fascicle. This is a characteristic feature of intratemporal facial nerve palsy, and requires further investigation. These results suggest that the basement membrane may play an important role in facial nerve regeneration, and that HSPG may maintain control over the degree of nerve regeneration.

Animals↗
PubMed2004

Hydrodynamic consequences of glycolysis: thermodynamic basis and clinical relevance.

Since Warburg's original description of aerobic and anaerobic glycolysis in 1924, the biochemical and molecular bases of glucose metabolism in cells have been characterized. However, its thermodynamic implications have found little attention. Van't Hoff's law of thermodynamics was applied here to describe how glucose metabolism affects intracellular osmotic pressure, hence revealing how glucose metabolism provides cells with osmotic energy as well as chemical energy. Ensuing osmosis-driven movement of free water across membranes affects cell volume and shape, hydration of intracellular components, and interactions of cells with their environment. Comparative analysis of extant data revealed strong evidence for clinically relevant glycolysis-driven effects under hypoxic conditions known to occur in cancer, vascular disease as well as intensive care, including critical and preventable ones affecting treatment effectiveness and thus, clinical outcome. These findings provide the first evidence confirming the existence of glycolysis-driven hydrodynamic effects and suggest that high levels of aerobic and anaerobic glycolysis provide a common biophysical basis in seemingly unrelated medical conditions.

Cell Hypoxia↗
PubMed2004

Survival of Cryptosporidium parvum oocysts after prolonged exposure to still natural mineral waters.

The survival kinetics of purified Cryptosporidium parvum oocysts of both human and ovine origin, immersed in four still natural mineral waters (total dissolved salts ranging from 91 mg/liter to 430 mg/liter) and reverse osmosis water was assessed by inclusion or exclusion of the fluorogenic vital dyes 4',6-diamidino-2-phenylindole and propidium iodide over a 12-week period. Semipermeable chambers were used to contain the oocysts while immersed in each mineral water type, permitting both intimate interactions between oocysts and matrices and straightforward sampling for viability assessments. The viability of both oocyst types, assessed at weekly intervals, remained unaltered after 12 weeks at 4 degrees C, whereas a progressive decline in the viability of both oocyst isolates was observed when immersed in mineral waters at 20 degrees C. At 20 degrees C, approximately 30% of oocysts remained viable after 12 weeks incubation. Here, temperature was the major factor that adversely affected oocyst survival, although higher mineral content was also proportionally and significantly associated with this increased oocyst inactivation. The prolonged survival of oocysts at 4 degrees C in our studies indicates that they could survive for prolonged periods of time in U.K. groundwaters (average temperature approximately 10 degrees C) and thus represent a potential public health hazard if contamination of mineral water sources by viable oocysts were to occur.

Animals↗
PubMed1976

Pathophysiology in the acute afferent loop syndrome. A study in rats.

The afferent loop syndrome, i.e. occlusion of an afferent intestinal loop after a Billroth II partial gastrectomy, was induced in rats. After various time intervals the animals were killed and the haematocrit and serum osmolality were determined. The content of the occluded loop was analysed with respect to volume, bacterial flora and osmolality. In some cases a sample of the content was incubated at 37 degrees C and the osmolality determined at regular intervals. Groups of animals were studied in this way after 30 min or 1, 4, 8 or 12 h of occlusion. The haematocrit rose with time after the occlusion. The osmolality of the plasma and of the content of the occluded loop did not increase. The volume of fluid in the occluded loop increased continuously with time--from an average of 0.5 ml in the control cases to 6.1 ml after 12 h of occlusion. Experiments in vitro showed that the initial osmolality of the content of the loop was 300 mOsm. After incubation of the samples this increased by 43 to 146 percent. The bacterial content of the loop, including Clostridium perfringens, increased significantly. The results indicate that a marked breakdown of substances takes place in such an occluded intestinal loop, which increases the osmolality. As a result fluid is immediately attracted to the loop to keep the osmolality constant. A combination of this fluid increase due to osmosis and contractions of the intestinal wall leads to a pressure in the occluded loop which considerably exceeds the pressure in the common bile duct due to secretions from the pancreas and liver.

Acute Disease↗
PubMed1976

Motion picture: transpubic total prostatectomy.

The transpubic approach for total prostatectomy is ideal in cases involving small glands that have been resected and reported as stage A tumors. The approach also is ideal for stage B1 and B2 tumors. It allows great ease in the osmosis of the bladder to the urethra and dissection of the lymph nodes in the obturator and iliac areas.

Humans↗
PubMed1999

A simple and fast method to estimate peritoneal membrane transport characteristics using dialysate sodium concentration.

BACKGROUND: The peritoneal equilibration test (PET) is widely used to classify a patient's peritoneal transport characteristics. However, PET is laborious and the prediction of fluid removal based on PET is generally poor. It is believed that osmosis by glucose occurs partially through transcellular water channels, resulting in sieving of sodium and decrease of dialysate sodium concentration when using hypertonic glucose dialysate. OBJECTIVE: In this study, we investigated the possibility of using dialysate sodium concentration to classify the patient's peritoneal transport characteristics. METHODS: A 6-hour dwell study with frequent dialysate and plasma sampling was performed in 46 patients using 2 L of 3.86% glucose dialysate with 131I-albumin as an intraperitoneal volume (IPV) marker. The peritoneal transport of sodium, creatinine, glucose, and fluid was evaluated. RESULTS: The dialysate sodium concentration at 240 min (D(Na240)) significantly correlated with D/P creatinine (r = 0.76, p < 0.001) and D/D0 glucose (r = -0.83, p < 0.001) at 240 min of the dwell (better than dialysate sodium concentration at any other time of the dwell). DNa240 also significantly correlated with IPV at 240 min of the dwell (r = -0.61, p < 0.001)(better than D/P creatinine and D/D0 glucose). There were significant correlations between D(Na240) and the sodium-sieving coefficient (r = 0.71, p < 0.001) and the diffusive mass transfer coefficient for sodium (r = 0.50, p < 0.001). When using D(Na240) to divide the patients into four groups, as in the PET method, no significant difference was found between the two methods. CONCLUSION: Using 3.86% glucose solution, D(Na240) can be used instead of D/P creatinine to classify patients into different transport groups. D(Na240) provides a better prediction of peritoneal fluid transport and reflects both the diffusive and convective transport properties of the membrane. As only one dialysate sample (and no blood sample) is needed, D(Na240) may offer important clinical advantages compared with PET.

Biological Transport↗
PubMedDate not supplied

Water treatment for haemodialysis: not as safe as anticipated.

"It is not exaggerated to state that inadequate water treatment is one of the gravest risks posed to the health of the patient on dialysis". PR Keshaviah. Water purification for haemodialysis relies on a combination of filtration, carbon adsorption, ion exchange and Reverse Osmosis (RO). This procedure is commonly considered safe and adequate (1).

Europe↗
PubMed1999

Hypochromic anaemia in chronic renal failure--role of aluminium.

BACKGROUND: Anaemia is a cardinal feature of chronic renal failure and classically it is normochromic normocytic. Hypochromic anaemia in these patients is often attributed to iron deficiency. AIM: This study was aimed to find the contribution of aluminium in causation of anaemia in CRF patients. METHODS: Dialysis dependent patients of chronic renal failure with adequate dietary intake (> 1500 Cals/day) and no apparent source of blood loss were evaluated for type of anaemia. (During period of this study centre didn't have reverse osmosis plant for water treatment). Evaluation included upper GI endoscopy, complete hemogram, serum proteins, serum iron, total iron binding capacity, and bone marrow iron status. For aluminium evaluation serum aluminium levels were done. RESULTS: Sixty-four patients were evaluated for type of anaemia. Mean age of patients was 41.19 years (15-76 years) with male:female ratio 2.3:1. Classical normochromic picture was seen in 28.5% while rest had hypochromic picture. On bone marrow aspiration study two patients had zero iron stores while all others had normal/excessive iron stores. In 10 patients with hypochromic picture, mean serum aluminium levels were 170 micrograms/L (30-310 micrograms/L). CONCLUSIONS: This study highlights the high prevalence of hypochromic anaemia in patients with adequate dietary intake and aluminium overload in Indian CRF patients.

Adult↗
PubMed2000

Reversible changes in size of cell nuclei isolated from Amoeba proteus: role of the cytoskeleton.

Micrurgically isolated interphasal nuclei of Amoeba proteus, which preserve F-actin cytoskeletal shells on their surface, shrink after perfusion with imidazole buffer without ATP, and expand to about 200% of their cross-sectional area upon addition of pyrophosphate. These changes in size may be reproduced several times with the same nucleus. The shrunken nuclei are insensitive to the osmotic effects of sugars and distilled water, whereas the expanded ones react only to the distilled water, showing further swelling. The shrinking-expansion cycles are partially inhibited by cytochalasins. They are attributed to the state of actomyosin complex in the perinuclear cytoskeleton, which is supposed to be in the rigor state in the imidazole buffer without ATP, and to dissociate in the presence of pyrophosphate. Inflow of external medium to the nuclei during dissociation of the myosin from the perinuclear F-actin may be due to colloidal osmosis depending on other macromolecular components of the karyoplasm.

Actins↗
PubMedDate not supplied

The effects of water filtration systems on fluoride: Washington, D.C. metropolitan area.

According to the U.S. Environmental Protection Agency (EPA), approximately one in eight Americans is exposed to potentially harmful microbes, pesticides, lead, or radioactive radon whenever they drink a glass of tap water or take a shower. One reason for this exposure is that the water plants are aging or ill equipped to process the huge amounts of raw sewage and agricultural pollutants that are still being discharged into our drinking-water sources. Other compounds such as fluoride and chloride have been added to the community water supplies for health benefits. Water filtration systems are becoming more popular as people become concerned with pollutants in the public water supply and questions are being raised as to whether fluoride is affected by these filters. The aim of this pilot study was to assess the efficacy of three types of water filtration systems and to determine their impact on fluoride content of the water in the Washington, D.C. metropolitan area. One sample of water was collected daily for fourteen days, from one location. The sample was divided to use as a control and the test samples which were processed through various filter systems. With the use of a fluoride ion specific electrode, the fluoride concentration level was tested in all samples in order to determine the percentage of fluoride removed. This study was intended to prove that the water filtration systems did not affect the advantage offered by optimum water fluoride levels. The experimental samples were ascertained and compared to the control group, resulting in three of the four carbon filters showing statistically significant amounts of fluoride removed from the water. Both Reverse Osmosis and Distillation, as expected, removed the fluoride at a high rate.

District of Columbia↗
PubMed2001

Analysis of estrogenic hormones in municipal wastewater effluent and surface water using enzyme-linked immunosorbent assay and gas chromatography/tandem mass spectrometry.

Although the estrogenic hormones 17 beta-estradiol and 17 alpha-ethinyl estradiol can be quantified in polluted waters by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/tandem mass spectrometry (GC/MS/MS), the compounds often are present at concentrations below detection limits. Enzyme-linked immunosorbent assays (ELISAs) provide a sensitive and robust means of quantifying estrogenic hormones in wastewater effluents and surface waters. Results from ELISA analysis of estrogenic hormones in secondary wastewater effluent indicate concentrations comparable to those that cause vitellogenesis in fish. Confirmatory analyses by GC/MS/MS are consistent with ELISA results. Effluent filtration, using sand filtration or microfiltration, removes approx. 70% of the hormones from secondary effluent, while advanced treatment, using reverse osmosis, removes more than 95% of hormones. The detection limits for estrogenic hormones are approx. 0.1 ng/L in wastewater effluent and 0.05 ng/L in surface water. The ELISA technique provides a relatively simple and practical method of assessing the fate of estrogenic hormones in engineered and natural systems.

Chromatography, High Pressure Liquid↗
PubMed2001

The effects of water reclamation technologies on biological stability of industrial water.

A modified Assimilable Organic Carbon (AOC) procedure was adopted in conjunction with Heterotrophic Plate Count (HPC) method to assess the effect of Single Effect Distillation (SED) and Reverse Osmosis (RO) lab-scale systems on the biological stability of industrial water. Industrial water was collected from a local Industrial Water Works, pre-treated with alum coagulation and cartridge filtration, before being subjected to advanced water treatment. The results obtained in this study indicated that AOCs in the SED product water were in the range of 70-80 micrograms acetate-C/L, while those in the RO product water ranged from 30-40 micrograms acetate-C/L in the 15-min permeate to 55-65 micrograms acetate-C/L in the 3-hr permeate. The above findings suggested that product water of both systems were potentially biologically unstable and would likely lead to bacteria regrowth during its distribution and storage. Removal efficiencies of lab-scale RO and SED systems on AOC were as high as 90%, dependent on the concentration of AOC-NOX in the industrial water. The RO system had much higher organic removal efficiencies in terms of AOC and DOC than the SED system. Organics removed from both feed waters were found to be concentrated in the brine water and rejected water in SED and RO systems respectively.

Conservation of Natural Resources↗
PubMedDate not supplied

Icodextrin degradation products in spent dialysate of CAPD patients and the rat, and its relation with dialysate osmolality.

OBJECTIVE: Peritoneal dialysis (PD) with a 7.5% icodextrin-containing dialysis solution provides prolonged ultrafiltration compared with glucose-based dialysis solutions. Colloid osmosis is the most likely mechanism, but studies in rats suggest it is caused by an increase in osmolality due to degradation of icodextrin. Therefore, human spent dialysate was analyzed with high-performance liquid chromatography (HPLC) using gel permeation size-exclusion chromatography. An increasing peak (with a low molecular weight, < 1000 Da) was observed during the dwell. The aim of this study was to quantitate breakdown products of icodextrin (which could explain this peak) and investigate whether there was a relationship with dialysate amylase concentration and dialysate osmolality. DESIGN: Long-dwell effluents (dwell time 9.15- 14.30 hours) obtained from 12 PD patients using a 7.5% icodextrin solution during the night were analyzed. The following icodextrin breakdown products were measured: maltotetraose (G4), maltotriose (G3), maltose (G2), and glucose (G1). In 6 of these patients, the sugars maltoheptaose (G7), maltohexaose (G6), and maltopentaose (G5) were also determined in both effluent and plasma. In addition, G4, G3, G2, and G1 were measured in four Wistar rats during a 6-hour dwell study. RESULTS: In the human studies, the median distribution of the sugars in the effluent was G4,6.7%; G3,16.5%; G2, 23.1%; and G1, 53.5%. The osmolality in spent dialysate ranged between 288 and 326 mOsm/kg H2O. The median contribution of the sugars G2 - G4 was 5.4 mOsm/kg H2O. No correlation was present between dialysate osmolality and duration of the dwell (r= -0.04, p= 0.91); nor was there a relation between the concentration of G2 and duration of the dwell (r = 0.50, p = 0.10). No relationship was found between the amount of amylase and the concentration of G2 in the effluent (r = 0.49, p = 0.10), nor between the total concentration of the sugars G2 - G4 in the spent dialysate and dialysate osmolality (r = -0.31, p = 0.33). However, a strong correlation was seen between urea concentration and osmolality (r= 0.85, p < 0.001), and also between sodium concentration and dialysate osmolality in the spent dialysate (r = 0.92, p < 0.0001). The levels of the sugars G2, G3, and G4 in effluent were higher than in unused dialysate, but lower than or similar to plasma levels. Concentrations of the sugars G5, G6, and G7 were lower in spent dialysate than in unused dialysate, and higher than in plasma. In the rat study, dialysate osmolality increased with the duration of the dwell. A clear relationship was present between osmolality and concentration of the sugars G2 - G4 in the effluent. The median amount of amylase in the effluent was 1252 U/L. CONCLUSION: A 7.5% icodextrin-based dialysis solution used during the long exchange caused only a slight increase in dialysate osmolality in humans. The osmolality at the end of the dwell in the human situation was dependent mainly on concentrations of the small solutes urea and sodium in the effluent. The contribution of icodextrin degradation products was marginal. In the rat, however, a clear relationship was present between osmolality and icodextrin degradation products in spent dialysate, explaining the increased dialysate osmolality at the end of the dwell. The difference between the two species can be explained by the very high amylase concentrations in the rat, leading to a rapid degradation of icodextrin. The rat is therefore not suitable to study peritoneal fluid kinetics using icodextrin as an osmotic agent.

Animals↗
PubMed2001

Modification and quantitative analysis of the Münch model in the integrated system of water translocation in plants.

Aiming at making the Münch model more adequate to the biological reality we introduce certain modifications and complements. Considering the model within the framework of so-called integrated system of long-distance water transport in plants we present a quantitative analysis based on the Kedem-Katchalsky formalism. A new mathematical description of the reverse osmosis is also utilized. The work is a starting point for further quantitative studies and simulations of the phloem transport of water and assimilates in plants.

Kinetics↗