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Query: UMLS:C0042961 (volvulus)
 4,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A system developed in our laboratory for the in vitro cultivation of larval Onchocerca volvulus is being employed in a series of morphogenetic, physiologic, chemotherapeutic and immunologic investigations of this parasite. Because of the need for a large and readily available supply of living worms for this work, cryogenic techniques are being used for the long-term preservation of larval parasites collected in various endemic areas of Guatemala, C.A. To date, microfilariae have survived frozen storage in human cutaneous tissues (excised nodules and skin snips) for as long as 504 days, and viable larvae, in all stages of development have been recovered from the black fly vectors (Simulium ochraceum and S. metallicum) kept frozen for 396 days. That cryopreservation does not appear to affect these parasites adversely is indicated by the fact that microfilariae derived from frozen tissues do not differ from those obtained from fresh tissues on the basis of: 1) numbers and vigor of emergent microfilariae; 2) survival and morphogenesis of microfilariae during cultivation in vitro for 24 days; 3) glucose utilization during 72 hours of incubation; and 4) their incorporation of 3H-amino acids as determined after 18 hours of incubation. Details of methodology for cryopreservation and in vitro cultivation, together with resultant data, are presented herein.
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PMID:The cryopreservation and in vitro cultivation of larval Onchocerca volvulus. 50 87

Experimental closed loop small intestinal volvulus was studied in the anesthetized horse. Volvulus was simulated by ligation of the mesenterial veins to a segment of small intestine. Physical signs and hemodynamic, hematologic, clinical chemical, bacteriologic and peritoneal fluid values were examined. Compared to conscious horses anesthesia highly delayed and modified the clinical signs of shock (changes in mucosal colour, dehydration, decreased skin temperature, elevated pulse rate, low blood pressures) and of small intestinal volvulus (altered peristalsis, gastric dilation). Plasma glucose response to shock was also modified by unconsciousness. However, a dose response relationship was indicated between the extent of small intestinal damage and clinical symptoms. The same was applicable to changes in blood pressures, blood acid-base balance, lactate, potassium, chloride, glucose, inorganic phosphorus, creatinine, creatine kinase, red blood cell and total white blood cell counts and serum total protein. The relationship was also indicated in the following peritoneal fluid values: volume, lactate, pH, total white cell counts, alkaline phosphatase and bacteriology. Changes related to shock (insufficient tissue perfusion) were low blood pressures and metabolic acidosis due to anaerobic glycolysis with accumulation of lactic acid. Also low plasma glucose and elevated plasma potassium, creatinine, inorganic phosphorus and creatine kinase were regarded as consequences of shock.
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PMID:Simulated small intestinal volvulus in the anesthetized horse. 52 13

The in vitro killing of Onchocerca volvulus infective third stage larvae (L3) by components of their human hosts' defence mechanisms is not well documented, as no suitable assay exists. Motility is inappropriate as a criterion of larval viability because of the unsteady winding movements of L3. In the present study, a metabolic parameter for larval viability, the uptake of [3H]2-deoxy-D-glucose, was evaluated. To demonstrate the reproducibility and validity of this test, the oxygen radical hydrogen peroxide (H2O2) was applied to viable L3 and the death of L3 demonstrated by a 90% reduction in glucose uptake. The incorporation of glucose by the filarial larvae was also determined after in vitro exposure to lysates of the putative effector cells, i.e. eosinophilic and neutrophilic granulocytes and monocytes. Effector-cell-derived components led to a 30-80% dose-dependent decrease in deoxy-glucose uptake, with a half-maximal effect at about 500 micrograms ml-1. These experiments demonstrate, for the first time, the deleterious impact of effector cell constituents on the metabolic activity of O. volvulus L3. The assay could be used to evaluate the effect of distinct natural or recombinant effector molecules on the viability of O. volvulus infective larvae and to investigate the effect of parasite molecules which interfere with effector mechanisms.
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PMID:Inhibition of carbohydrate uptake of Onchocerca volvulus infective larvae (L3) by effector cell constituents. 132 84

We have autotransplanted highly purified cryopreserved canine islets into pancreatectomized dogs. Islets were frozen by slow cooling (0.25 degrees C/min) to -40 degrees C, stored at -196 degrees C and thawed rapidly (200 degrees C/min). A total of 7868 +/- 665 (means +/- SE) cryopreserved islets/kg body weight were implanted to the spleen (n = 7) by venous reflux, and seven other control dogs received 6811 +/- 653 fresh islets/kg (P versus cryo., NS). Fasting plasma glucose [( PG] mg/dl, +/- SEM) and intravenous glucose tolerance were determined before and at 1 and 3 months postimplantation. Six dogs that received cryopreserved islets and all seven control animals promptly became normoglycemic, with PGs of 133 +/- 23 and 110 +/- 4, respectively, at 1 week postimplantation (NS). During follow-up one normoglycemic animal from each group died due to small bowel volvulus and one recipient of fresh islets became diabetic at 14 days. The remaining dogs remained normoglycemic with PGs of 89 +/- 3 and 92 +/- 3 in dogs receiving cryopreserved and fresh islets, respectively, at 3 months postimplantation (NS). Mean K value (decline of glucose, %/min +/- SEM) at ivGTT for all dogs was 2.5 +/- 0.3 preoperatively. At 1 and 3 months postimplantation, the K values of dogs receiving cryopreserved islets were 1.3 +/- 0.1 and 1.4 +/- 0.2, respectively, compared with 1.3 +/- 0.2 and 2.0 +/- 0.2 for control dogs (NS). These data demonstrate prompt and sustained function of a defined quantity of frozen-thawed purified islets in a large mammal. Cryopreservation is an effective method for the long-term storage of purified islet tissue.
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PMID:Reversal of diabetes in dogs by transplantation of pure cryopreserved islets. 211 89

The viability and drug responses of cryopreserved adult Onchocerca have been examined in vitro. Male worms were cryopreserved in liquid nitrogen (-196 degrees C) using ethanediol as a cryoprotectant in a 2-step incubation procedure. After thawing, 85-90% of O. gutturosa males were normally motile. These motile worms were evaluated for viability using 4 measurements (long-term motility/survival in culture; [U-14C]adenine uptake and leakage; glucose utilization; MTT-formazan colorimetry) and were no different from unfrozen controls. Subsequent experiments demonstrated that the motility responses of cryopreserved worms exposed to the antifilarial drugs ivermectin, CGP 6140 and levamisole were virtually identical to unfrozen controls. Some success was also obtained with this technique in cryopreserving O. volvulus males, with 2 thawed specimens surviving in culture for 93 and 106 d respectively. Following collagenase isolation, female worms were cryopreserved in medium +10% serum without protectant at -79 degrees C. A batch of 8 female O. gutturosa were all motile when thawed 14 d later, with a mean survival time (based on 5 specimens) of 71 d (range 60-90). However, a batch of worms transferred from -79 degrees C to -196 degrees C were badly damaged when thawed. Female O. volvulus were cryopreserved at -79 degrees C in Guatemala and sent by air freight on solid CO2 to the UK. Most specimens were active when thawed. Survival of motile specimens ranged from 7 to 272 d in culture. It is concluded that these techniques are of practical value for the storage and transportation of adult Onchocerca.
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PMID:Onchocerca gutturosa and O. volvulus: studies on the viability and drug responses of cryopreserved adult worms in vitro. 261 29

Use was made of seven FITC labelled lectins as tools to investigate the surface of Onchocerca lienalis larvae as they develop through to the infective third-stage in a natural vector, Simulium ornatum. The lectins were derived from Canavalia ensiformis (Con A), Lens culinaris (lentil), Triticum vulgaris (wheat germ), Arachis hypogaea (peanut), Helix pomatia, Phaseolus vulgaris (kidney bean) and Tetragonolobus purpureus (asparagus pea). Between 70 and 100 living parasites were examined for each developmental stage; i.e. skin microfilariae, late first-stages, second-stages, preinfective third-stages and infective third-stages isolated from the mouth parts of the flies. None of the lectins used bound to the surface of the microfilariae. However, progressive binding to the cuticle of the first- and second-stages was observed using Con. A, lentil lectin and wheat germ agglutinin (WGA). Following moulting to the third-stage, binding of these three lectins declined. Furthermore, as these lectins decreased, peanut and Helix pomatia lectins progressively increased in their binding, despite the fact that they showed little or no binding to the first- and second-stages; stages at which Con A, lentil and WGA were at their maximum. Asparagus pea and kidney bean lectins failed completely to bind to any of the larvae examined. Carbohydrate inhibition tests showed that the lectin was indeed binding specifically to glycoconjugates on the parasite surface. WGA binding was not inhibited by prior incubation with N-acetyl-D-glucosamine, even at high concentrations, but neuraminic acid did completely inhibit its binding. Judging from the patterns of binding on the nematodes themselves, the carbohydrates may not be vector in origin, but derive from the worms. The lectin specificities indicate that initially mannose/glucose type derivatives are present on the surface. Following moulting to the third-stage these are progressively replaced, or overlaid with galactosamine type derivatives, also present on the infective third-stage as it enters the bovine host. The availability of these surface glycoconjugates to attack mediated by natural insect lectins may be of importance in the parasite regulatory mechanisms of the blackfly. Variability in these surface carbohydrates, and in the response to them could well be a contributing factor in the cytospecific variation in S. damnosum susceptibility to geographical variants of O. volvulus.
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PMID:Surface carbohydrate changes on Onchocerca lienalis larvae as they develop from microfilariae to the infective third-stage in Simulium ornatum. 314 48

Physical and clinicopathologic findings from six cows with proximal duodenal obstruction (PDO) and 58 cows with abomasal volvulus (AV) were compared retrospectively. Many of the physical signs were similar in cows with PDO and cows with AV, but the two conditions differed in the type of abdominal distention, and in the findings from rectal examination and abdominal auscultation. Cows with PDO had significantly lower mean values for serum sodium (Na+) and chloride ion (Cl-), and higher mean values for plasma bicarbonate [HCO3-], base excess, carbon dioxide pressure (pCO2), serum phosphate, urea nitrogen, and total protein than AV affected cattle. Cows with PDO showed hyperglycemia (range, 263-990 mg/dl; mean, 618 mg/dl) of unexplained etiology that was significantly higher than blood-glucose concentrations in AV cows (mean, 178 mg/dl). Although all AV cows with anion gap values greater than 32 mEq/l died;PDO cows with equally elevated anion gap survived. The anion gap elevations in PDO and AV cows resulted from accumulation of different anions. Although the site of obstruction of aborad flow of ingesta is similar in both disease conditions, the differences in physical and clinicopathologic findings appear to reflect differences in the degree of reticulo-omasal orifice obstruction and the degree of abomasal vascular compromise.
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PMID:Comparison of naturally occurring proximal duodenal obstruction and abomasal volvulus in dairy cattle. 323 95

A method for the selective recovery of living microfilariae from Onchocerca volvulus nodules is described. The microfilariae migrate through solidified agar gel into overlayering Hanks balanced salt solution (HBSS). The highest recovery rates of the worms were obtained with 0.3 and 0.4% agar. Optimal conditions for in vitro cultures of the larvae in HBSS were established; pH range 7.0-7.5, glucose concentration 2-5 mg/ml for long term cultures, osmolality 200-309 mOsmoles/l, temperature 4 degrees C for prolonged cultures and 24-28 degrees C for overall best yield of excretory/secretory products (ESP). Subculturing of the larvae reduced contamination of ESP with human serum protein to minimal amounts after 9 recultures done within 96 h.
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PMID:Selective recovery of living microfilariae from Onchocerca volvulus nodules. Determination of optimal conditions for their culture in vitro for excretory/secretory products. 611 34

The survival in culture of adult female Brugia pahangi, Acanthocheilonema viteae, and Onchocerca volvulus and adult male Onchocerca gibsoni was assessed by measuring parasite motility. Survival of all species was maximal in a nutritionally complex medium (RPMI-1640). All species survived for up to 48 hr in a simpler medium in which the only energy source was 10 mM glutamine; motility in this medium was dependent upon pH. For the species of Onchocerca, motility was maintained better in the presence of glutamine as the sole energy source than in glucose-only medium. Motility of B. pahangi incubated in 10 mM succinate was equivalent to that seen with 10 mM glutamine, but no other tricarboxylic acid intermediate supported this parasite in vitro. Antimycin A (1 microM) and potassium cyanide (KCN, 100 microM) paralyzed B. pahangi incubated in 10 mM glutamine, an effect antagonized by glucose. KCN at 10 or 100 microM was effective also against Onchocerca gutturosa in glutamine-only medium. Several glutamine antimetabolites reduced motility of B. pahangi by 72 hr. This inhibition was prevented by 2 mM glutamine. However, the inhibition of motility in the species of Onchocerca caused by these compounds was attenuated only partially by glutamine. These data demonstrate that, under certain conditions, filarial nematodes can utilize non-sugar substrates as energy sources. The differential sensitivity seen among these organisms to mitochondrial toxins and glutamine antimetabolites may be related to the extent to which they can use these alternative substrates to generate energy.
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PMID:Glutamine-supported motility of adult filarial parasites in vitro and the effect of glutamine antimetabolites. 845 26

CFTR, or cystic fibrosis transmembrane conductance regulator, the gene product that is defective in cystic fibrosis, is present in the apical membrane of the epithelial cells from the stomach to the colon. In the foregut, the clinical manifestations are not directly related to the primary defect of the CFTR chloride channel. The most troublesome complaints and symptoms originate from the oesophagus as peptic oesophagitis or oesophageal varices. In the small intestinal wall, the clinical expression of CF depends largely on the decreased secretion of fluid and chloride ions, the increased permeability of the paracellular space between adjacent enterocytes and the sticky mucous cover over the enterocytes. As a rule, the brush border enzyme activities are normal and there is some enhanced active transport as shown for glucose and alanine. The results of continuous enteral feeding of CF patients clearly show that the small intestinal mucosa, in the daily situation, is not functioning at maximal capacity. Although CFTR expression in the colon is lower, the large intestine may be the site of several serious complications such as rectal prolapse, meconium ileus equivalent, intussusception, volvulus and silent appendicitis. In recent years colonic strictures, after the use of high-dose pancreatic enzymes, are being increasingly reported; the condition has recently been called CF fibrosing colonopathy. The CF gastrointestinal content itself differs mainly from the normal condition by the lower acidity in the foregut and the accretion of mucins and proteins, eventually resulting in intestinal obstruction, in the ileum and colon. Better understanding of the CF gastrointestinal phenotype may contribute to improvement of the overall wellbeing of these patients.
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PMID:Gastrointestinal manifestations in cystic fibrosis. 886 67


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