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Biomedical subjects

W E Rempel

Publications and source records attributed to W E Rempel.

At least 19 recordsLinked to original sources
PubMed1993

Relative accuracy of the halothane challenge test and a molecular genetic test in detecting the gene for porcine stress syndrome.

Pietrain swine homozygous for the hal gene (n) associated with porcine stress syndrome (PSS) and a Pietrain-derivative breed, Near Pietrain (NP), with a frequency of .31 for n, were mated to produce reciprocal F1, F2, and purebred NP litters. The halothane challenge test was performed on all 40 parents and 240 progeny to predict their hal genotype and PSS susceptibility. The DNA-based assay for a C to T mutation at base pair 1,843 of the skeletal muscle ryanodine receptor (ryr1) cDNA, which is very highly correlated with PSS, was also determined for these animals. The predicted hal genotypes observed in the progeny differed significantly from the expected Mendelian ratios, and the halothane challenge test consistently overestimated the n/n hal genotype. However, the ryr1 genotypes observed in the progeny did not differ significantly from the expected Mendelian ratios, and this DNA-based assay apparently misidentified only one of the 40 parents. The results of this study indicate that the assay for the ryr1 mutation more accurately predicts both the homozygous and heterozygous forms of the PSS gene than does the halothane challenge test.

Animals↗
PubMed1992

Structural and functional correlates of a mutation in the malignant hyperthermia-susceptible pig ryanodine receptor.

The skeletal muscle ryanodine receptor of malignant hyperthermia-susceptible (MHS) pigs contains a mutation at residue 615 that is highly correlated with various abnormalities in the regulation of sarcoplasmic reticulum (SR) Ca2+ channel activity. In isolated SR membranes the Arg615 to Cys615 ryanodine receptor mutation is now shown to be directly responsible for an altered tryptic peptide map, due to the elimination of the Arg615 cleavage site. Furthermore, trypsin treatment released 86-99 kDa ryanodine receptor fragments encompassing residue 615 from the SR membranes. We conclude that the 86-99 kDa domain containing residue 615 is near the cytoplasmic surface of the ryanodine receptor and likely near important Ca2+ channel regulatory sites.

Amino Acid Sequence↗
PubMed1992

Halothane gene and swine performance.

One hundred thirty-one pigs representing seven different breed groups (Minnesota No. 1 [M], Pietrain [P], Yorkshire [Y], and crosses PY, P[PY], P[NP], and P[YP]P) and three halothane gene genotypes (NN, Nn, and nn) were tested for breed, sex, and halothane gene (HAL) effects on growth and carcass performance. Breed effects were significant for all traits measured. Sex effect was significant for most traits except for meat scores. The HAL-locus linkage group explained 20 to 30% of the total variation for meat quality scores and 1 to 10% for meat quantity and growth traits. Pietrain x Yorkshire was the fastest growing breed group and had relatively good carcass quality. Pietrain and its related crosses had the most lean muscle but the lowest meat quality. The HN (HAL negative, genotype Nn) individuals within the PPY and PNP groups grew more quickly and had higher meat quality scores and less muscling than HP (HAL positive, genotype nn) individuals. A second experiment with 40 pigs showed significant differences in fat concentration in the loin muscle between breeds (M, Y, and P) and between genotypes within the NP population (NP[HP] and NP[HN]). The phenotypic correlation between fat percentage and marbling was .59 (P less than .01). The NP(HP) had higher water percentage in lean than the NP(HN). The water percentage was negatively correlated with meat quality scores of color, firmness, and marbling with phenotypic correlations of -.10, -.23, and -.57 (P less than .01), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1989

Halothane-sensitivity gene and muscle contractile properties in malignant hyperthermia.

Malignant hyperthermia (MH) results from the presence of the halothane-sensitivity gene and is characterized by abnormalities in muscle function. Populations of genetically defined pigs were used to determine the in vivo and in vitro expression of this gene in both the homozygous and the heterozygous condition. On exposure to halothane, isolated muscle bundles from the homozygous halothane-sensitive pigs exhibited decreased tetanus tension and increased tetanus half-relaxation time and contracture and were clearly distinguished from homozygous normal muscles. The heterozygous and homozygous normal muscles were similar in contractile responses except for the occurrence of halothane-induced contractures in the heterozygotes. The heterozygous halothane-negative pigs did not exhibit the characteristic signs of an MH episode in response to halothane succinylcholine, although some metabolic responses were significantly altered (e.g., increased venous partial pressure of CO2 and arterial and venous K+ concentration). Thus the heterozygous pigs were not MH susceptible but did represent a phenotype distinct from the homozygous normal pigs both in vitro and in vivo. These data provide the first convincing evidence for the expression of the halothane-sensitivity gene in heterozygotes.

Animals↗
PubMed1989

Effects of the halothane-sensitivity gene on sarcoplasmic reticulum function.

Pigs heterozygous for the halothane-sensitivity gene exhibit a distinct phenotype with regard to both in vivo and in vitro muscle responses to halothane (E. M. Gallant, J. R. Mickelson, B. D. Roggow, S. K. Donaldson, C. F. Louis, and W. E. Rempel. Am. J. Physiol. 257 (Cell Physiol. 26): C781-C786, 1989). In this paper heavy sarcoplasmic reticulum (SR) preparations were isolated from the muscles of pigs of all three genotypes. The rate of calcium release from SR of pigs homozygous for the halothane-sensitivity gene was approximately twice that of SR from pigs homozygous for the normal allele. Furthermore, in the presence of 6 microM Ca2+, the binding of [3H]ryanodine to SR isolated from the homozygous halothane-sensitive pigs was of a higher affinity than was the binding to SR isolated from the homozygous normal pigs (Kd = 70-90 vs. 265 nM, respectively). The SR from pigs heterozygous for the halothane-sensitivity gene, however, demonstrated intermediate values for the rate of calcium release and the affinity for [3H]ryanodine (Kd = 192 nM). Thus the alterations in heavy SR calcium release and [3H]ryanodine binding in the pigs containing one copy of the halothane-sensitivity gene demonstrate a distinct heterozygote phenotype. These data also suggest that the protein product of this gene is closely associated with, and perhaps identical to, the SR calcium release channel-ryanodine receptor protein.

Adenosine Triphosphate↗
PubMed1988

Abnormal sarcoplasmic reticulum ryanodine receptor in malignant hyperthermia.

Previous studies have demonstrated that skeletal muscle from individuals susceptible to malignant hyperthermia (MH) has a defect associated with the mechanism of calcium release from its intracellular storage sites in the sarcoplasmic reticulum (SR). In this report we demonstrate that the [3H]ryanodine receptor of isolated MH-susceptible (MHS) porcine heavy SR exhibits an altered Ca2+ dependence of [3H]ryanodine binding at the low affinity Ca2+ site as well as a lower Kd for ryanodine (92 versus 265 nM) when compared to normal porcine SR. The Bmax of the normal and MHS [3H] ryanodine receptor (9.3-12.6 pmol/mg) was not significantly different, and analysis of MHS and normal SR proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis did not reveal a significant difference in the intensity of Coomassie Blue staining of the spanning protein/ryanodine receptor region of the gels (Mr greater than 300,000). We also find that MHS porcine muscle intact fiber bundles exhibit a 5-10-fold lower ryanodine threshold for twitch and tetanus inhibition, and contracture onset when compared to normal muscle. Since the SR ryanodine receptor is a calcium release channel as well as a component intimately involved in transverse tubule-SR communication, abnormalities in the skeletal muscle ryanodine receptor may be responsible for the abnormal SR calcium release and contractile properties demonstrated by MHS muscle.

Alkaloids↗
PubMed1987

Porcine malignant hyperthermia: false negatives in the halothane test.

Purebred Pietrain pigs presumed (on the basis of pedigree) to be homozygous for malignant hyperthermia (MH) susceptibility were subjected to a 3% halothane challenge test. A few (6%) pigs that should have been MH susceptible on the basis of parental genotype did not develop muscle rigidity in response to repeated halothane tests. Three of these animals were brought into the laboratory, and muscle biopsy specimens were obtained for in vitro analysis. Bundles of intact muscle cells dissected from biopsy specimens were electrically stimulated, and mechanical responses were monitored during exposure to halothane. In all instances, the muscle bundles from the halothane-negative (ie, not sensitive to halothane), but genetically susceptible, pigs gave in vitro responses that were similar of those of halothane-positive MH-susceptible pigs in that tetanic tension was depressed, tetanus relaxation was slowed, and small contractures were produced upon halothane exposure. Thus, the presence of a halothane-sensitive abnormality in the skeletal muscles, in and of itself, is not always sufficient for development of in vivo muscle rigidity during a brief halothane test. Furthermore, when the halothane testing of pigs is conducted by recommended techniques, false negatives still occur in a small percentage of the genetically MH-susceptible animals.

Animals↗
PubMed1987

Malignant hyperthermia susceptibility: cardiac histomorphometry of dogs and young and market-weight swine.

The defect causing malignant hyperthermia has been proposed to involve cardiac as well as skeletal muscle. We tested the hypothesis that histomorphometric parameters for ventricular wall from malignant hyperthermia-susceptible swine and dogs were abnormal. Hearts were obtained from: mature dogs, age- and weight-matched young swine (89 +/- 15 days, 30 +/- 3 kg); and market-weight swine (102 +/- 10 kg). Using light microscopy, estimates were made for muscle nuclear dimensions and the volume-fraction of nuclei, sarcoplasm, blood vessels, and interstitial space. Cardiac maturation in both MH and normal swine was accompanied by decreased myocyte volume-fraction due to decreased nuclear volume-fraction and increased interstitial space volume-fraction. Sarcoplasm and vasculature volume-fraction were unchanged after maturation. Nuclear volume-fraction was slightly greater (p less than 0.05) in the right ventricle than the left for malignant hyperthermia and normal swine. Myocyte nuclear dimensions were generally similar among animals. Dogs and the oldest group of swine were not significantly different. Myocytes of all swine contained multiple nuclei, closely spaced in rows of 2 to 12. In contrast, most myocytes of mature dogs apparently contained one or two nuclei. Histomorphometric values were not significantly different between normal and malignant hyperthermia young swine and dogs. However, within the market-weight swine, volume-fraction for malignant hyperthermia myocytes and myocyte nuclei was decreased and interstitial space was increased compared to normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Porcine malignant hyperthermia: cell injury enhances halothane sensitivity of biopsies.

A possible relationship between muscle cell injury or deterioration and enhanced halothane sensitivity was studied by monitoring mechanical responses of skeletal muscles from normal pigs and pigs susceptible to malignant hyperthermia (MH). Increased time postbiopsy and decreased maximum control tetanic tension both correlated significantly with enhanced sensitivity to halothane. In both normal and MH-susceptible (MHS) muscles, greater halothane sensitivity was observed in cut cell than in intact cell bundles and in low tetanic tension as compared to high tension preparations. Subsequent to halothane exposure, twitches of high tension (greater than or equal 1.75 kg . cm-2) intact bundles of both normal and MHS muscles were potentiated. Tetani of normal intact bundles were not altered, whereas those of MHS bundles were depressed after halothane exposure. Control twitch-to-tetanus ratios (twitch ratios) were higher in MHS (0.23) than in normal (0.12) intact bundles. According to discriminant analysis, the best distinction between normal and MHS muscles, either cut or intact, was obtained by comparing halothane-induced changes in tetanic tension and control twitch ratios.

Animals↗
PubMed1985

Verapamil is not a therapeutic adjunct to dantrolene in porcine malignant hyperthermia.

We have investigated the hypothesis that the calcium antagonist verapamil might be useful for prevention or treatment of malignant hyperthermia (MH) in MH-susceptible (MHS) swine. MH episodes were triggered in four groups of four swine with halothane alone or combined with succinylcholine (SCh) and, with and without verapamil. MH episodes were reversed by therapy with dantrolene and NaHCO3 in all groups. Verapamil did not alter MH episodes triggered by halothane alone or combined with SCh. The dantrolene-NaHCO3 requirements for reversal of MH were greater for the groups receiving halothane-SCh, but did not differ in groups pretreated with and without verapamil. In vitro verapamil (25 microM) did not reduce responses of intact muscle fibers to halothane and, in fact, exaggerated some halothane-induced responses. High concentrations of verapamil (0.5 mM) caused contractures in MHS but not in normal muscles. Neither our in vivo nor in vitro results support the use of verapamil in the treatment of MH. Further, doses of dantrolene used to reverse these MH episodes, although admittedly small (1-2 mg/kg), did not produce myocardial depression when used in combination with verapamil.

Anesthesia, Inhalation↗
PubMed1985

Porcine malignant hyperthermia susceptibility: erythrocytic osmotic fragility.

Erythrocyte osmotic fragility was determined in 27 Pietrain swine which were susceptible to malignant hyperthermia (MH), 29 Yorkshire swine which were resistant to MH (controls), and 50 crossbred swine (Pietrain x Yorkshire), half of which were MH susceptible. Halothane challenge tests and blood creatine kinase activity were used as criteria for determining MH susceptibility. Mean values for osmotic fragility of erythrocytes in concentrations of NaCl between 60 and 120 mM were significantly different for the 3 groups (P less than 0.001). Hemolysis (50%) of erythrocytes occurred at NaCl concentrations of 90 mM for Pietrains, 85 mM for crossbreds, and 78 mM for controls. Increased fragility values occurred in 96% of the Pietrains, 3% of the controls, and 42% of crossbred swine that were halothane test-positive, and 58% of halothane test-negative crossbreds (P less than 0.05). The mean time of onset of signs of MH in response to halothane challenge testing was twice as long in the crossbreds as in Pietrains (P less than 0.01). Reticulocyte counts were moderately high in blood samples from both the Pietrains (P less than 0.001) and the crossbreds (P less than 0.05). Of the swine which were tested for erythrocyte selenium-dependent glutathione peroxidase activity, values were within acceptable laboratory limits in 18 of 20 Pietrains, 14 of 14 halothane test-negative crossbreds, and 8 of 8 halothane test-positive crossbreds. In 2 of 20 Pietrains, a 35% deficiency of this enzyme was found. Heinz bodies were not detected in erythrocytes examined from 21 Pietrains, 20 crossbred swine (8 halothane test positives), and 12 controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Halothane testing for malignant hyperthermia in swine: dose-response effects.

Purebred Pietrain malignant hyperthermia (MH)-susceptible pigs (n = 102) were subjected to halothane (0%, 1%, 2%, 3%, 4%, and 5%) in oxygen. The number of pigs in each group exhibiting muscle rigidity (MH(+) reaction) and the reaction times were recorded, as were the number of deaths resulting from MH. Mortality was not affected by the halothane concentration. However, halothane concentration did markedly affect the number of MH(+) reactions and the reaction times. False-negative reactions were apparent in the pigs at halothane concentrations less than 3%. Increasing the halothane concentration incrementally to 5% (from 0%) significantly (P less than 0.05) decreased reaction times between treatment groups. The reductions in reaction times which occurred in the pigs given the 3%, 4%, and 5% halothane concentrations (62.1, 56.2, and 50.05)--although significant (P less than 0.05)--would indicate that 3% halothane would generally be sufficient for MH testing.

Animals↗
PubMed1984

Noneffectiveness of verapamil in preventing halothane-induced malignant hyperthermia in susceptible swine.

Pietrain pigs susceptible to malignant hyperthermia (MH; porcine stress syndrome) were treated with the slow-channel calcium blocker verapamil and then subjected to halothane testing. There was no significant delay in the onset of MH among pigs (3 groups) given different doses of verapamil (1, 5, and 10 mg/kg) and saline control Pietrain pigs. The mortality due to MH (83.3%) was significantly higher among the pigs given the largest dose (10 mg/kg) than in the other groups. Verapamil was not effective in preventing or delaying a MH reaction. This antiarrhythmic drug should be used cautiously during a MH reaction in susceptible individuals.

Anesthesia, Inhalation↗
PubMed1983

Further evidence on the inheritance of halothane reaction in pigs.

One thousand six hundred forty-one Pietrain, 163 Minnesota No. 1 and 158 Pietrain X Minnesota No. 1 crosses and their reciprocals were tested for porcine stress syndrome susceptibility using halothane gas between September 1975 and July 1981. The frequency of reactors in the Pietrain breed was 93.9%. Matings of reactor males to reactor females within the Pietrain breed resulted in 632 reactor and 14 nonreactor offspring. A boar, judged to be nonpenetrant on the basis of the halothane reaction of his parents and littermates, was shown by progeny test to be homozygous for the halothane allele. These data indicate that halothane sensitivity is due to a single autosomal recessive gene with a penetrance of about 98% and a frequency of .98 in this Pietrain herd. No halothane reactors were found in the 163 Minnesota No. 1 pigs tested. Only one Pietrain X Minnesota No. 1 gilt reacted positively to halothane and later, the same gilt produced both positive and negative offspring, indicating that she was most likely heterozygous. Blood group typing of 107 crossbred pigs provided insufficient information to predict accurately the halothane reaction, although some associations were observed between the A and H loci and halothane sensitivity. The time taken by Pietrain pigs to react to halothane was measured and recorded. Analysis of these data showed that progeny of some sires had significantly faster reaction times than others and that reaction time had decreased over the years. These results as well as other data presented here indicate the existence of certain modifier genes that influence halothane reaction.

Animals↗
PubMed1981

Porcine stress syndrome and postmortem muscle characteristics of two purebreds and three specific terminal crosses.

The incidence of Porcine Stress Syndrome (PSS), determined by halothane screening, and parameters of muscle quality and carcass leanness were studied in 108 pigs from a larger population of 658 pigs of Pietrain (P), Minnesota No. 1 (M), Hampshire (H) x (P x M), Yorkshire (Y) X (P X M) and P X (P X M) breeding. The larger population was also surveyed by the halothane screening procedure for incidence of PSS, and growth rate was measured. At 6 to 14 weeks of age, pigs were classified as PSS if they exhibited muscle rigidity within 5 min after the commencement of anesthetization with 3% halothane in oxygen. The incidences noted for the larger population were: H x (P x M) and Minnesota No. 1, 0%; Pietrain, 88%; Y x (P x M), 3%, and P x (P x M), 17%. Results demonstrated that the H x (P x M) group displayed excellent carcass meatiness combined with acceptable meat quality and freedom from PSS.

Animals↗
PubMed1981

Malignant hyperthermia (MH): porcine erythrocyte damage from oxidation and glutathione peroxidase deficiency.

Malignant hyperthermia (MH) is a severe familial disease in both the pig and the human, with 70% fatality when fully expressed in humans. MH produces rapid elevation of temperature in response to stresses, of which there are two general kinds: Societal or emotional stress, and chemical stressors. The most commonly encountered stressor is halothane, a general anesthetic in wide use. Besides large temperature increases, there occur some twenty symptoms. Much work in other laboratories has been concentrated on elevated CPK i the plasma. However, all the symptoms are consistent with a single disorder, namely oxidative damage, especially in membranes. A deficiency in the glutathione peroxidase (GPX) system is a prime factor, likely the molecular basis allowing abnormal oxidative damage in the MH pig. Catalase activities are normal in MH pigs, but they have only 20-50% normal GPX activities. The deficiency does not cause oxidative damage. It allows failure or protective mechanisms against it. The nonstressed MH animal exhibits less acute symptoms, e.g. enhanced red cell Heinz bodies, but such animals generally mature. Under stress, their inadequate protective mechanisms dependent on GPX are overwhelmed, resulting in gross symptoms and crisis. It is important to concentrate on the GPX system(s) and their adjacent pentose shunt metabolism. We propose that a deficiency in any of these two systems is the molecular basis of the disease. Many tissues are involve in MH, but the red cell obviously provides a convenient means for assay and for screening. This paper mainly pertains to porcine MH. However, preliminary work with humans indicates that human MH has a similar molecular basis.

Animals↗