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W N Fishbein

Publications and source records attributed to W N Fishbein.

At least 19 recordsLinked to original sources
PubMed1992

Molecular analysis of the myoadenylate deaminase deficiencies.

Myoadenylate deaminase (mAMPD) deficiency in a clinically heterogeous metabolic myopathy consisting of primary (inherited) and secondary (acquired) forms based on a variety of clinical and laboratory findings. To provide a basis for delineating the underlying molecular defects in mAMPD deficiency, and as a means to test the proposal for multiple forms of the resulting disease, Northern blot analyses were performed with RNA isolated from individual patients with classified primary and secondary deficiency utilizing human mAMPD cDNA probes isolated from adult skeletal muscle libraries. Analysis of nine patients with primary mAMPD deficiency indicates normal abundance of mAMPD transcript. No immunoreactive mAMPD polypeptide is detected in Western blot analyses of skeletal muscle extracts prepared from these patients. Specificity to mAMPD is demonstrated by normal creatine kinase (CK) activities and M-creatine kinase (M-CK) transcript abundance. Similar analyses of four individuals with secondary mAMPD deficiency reveal heterogeneity in this subgroup of patients. Whereas two of these patients exhibit normal mAMPD transcript abundance, two others associated with inflammatory myopathy display reductions in mAMPD and M-CK transcript abundance. Examination of tissue sections derived from the same biopsies utilized in the isolation of RNA demonstrates the integrity of the skeletal muscle in those patients with associated inflammatory myopathy. Combined, these data support the proposal for multiple forms of mAMPD deficiency, and indicate that the primary condition is most commonly characterized by specific point mutations or small deletions/rearrangements in the ampd1 gene, whereas some patients with secondary mAMPD deficiency display more generalized aberrations in gene expression.

AMP Deaminase↗
PubMed1990

Medical implications of the lactate and ammonia relationship in anaerobic exercise.

The genesis of the modern ischemic forearm exercise test (IFET) employing the measurement of lactate and ammonia as countervailing metabolites is briefly reviewed, along with the application of the lactate ammonia exercise ratio in the diagnosis of myoadenylate deaminase deficiency and disorders of glycolysis and glycogenolysis. Two cases are presented to illustrate the response patterns elicited, their reproducibility, the types of parameters that can be quantified, and the role the IFET may play in the differential diagnosis of fitness failures. The role of the ammonia measurement is emphasized here because the lactate response is more familiar. The roles of hypoxanthine responses and of muscle ammonia measurements in the evaluation of cases are examined, and some pertinent and recently introduced analytic methods are cited. The applications of newer approaches, such as aspiration biopsy and N-14 NMR spectroscopy, are discussed, along with an example of the new clinical defects in enzymes and membrane carriers that should be anticipated during the utilization of the IFET.

AMP Deaminase↗
PubMed1990

A glucose-6-phosphate dehydrogenase stain for frozen human skeletal muscle biopsy specimens. A sensitive indicator of fiber degeneration.

The glucose-6-phosphate dehydrogenase (G6PD) stain was adapted to skeletal muscle by using homogenate assays and quantitative cytochemical stains to determine the "correct" localization. For both feline and human skeletal muscles, the appropriate level of phenazine methosulfate eliminated fiber typing, which was falsely localizing the rate-limiting, bound reduced form of NADPH rather than the soluble G6PD. Use of a viscous solution of polyvinyl alcohol was necessary to prevent enzyme diffusion. Under these conditions, G6PD produced a mild myoplasmic stain with even sarcoplasmic reticulum granularity in human biopsy specimens. Fibers that were degenerating or regenerating by hematoxylin-eosin or alkaline phosphatase stains yielded an intense myoplasmic G6PD stain. Additional degenerating fibers were also often detectable with G6PD staining. No increased staining was found in denervated or atrophic fibers. Absence of staining (after 2 hours) was not a reliable indicator of G6PD deficiency, although it could be used for preliminary screening of muscle biopsy specimens.

Animals↗
PubMed1988

Clinical assay of the human erythrocyte lactate transporter. I. Principles, procedure, and validation.

A clinically applicable method for the assay of lactate efflux from human red cells has been developed and described in detail. It requires only small volumes of blood and routine chemicals, and evaluates the process under physiological conditions and direction of lactate loading and transport. The decline of red cell lactate level fit a first order decay curve reasonably well, and better than the fit to zero order or second order plots. Bias is controlled by the use of least-squares curve fitting for all assays, and constraints on the elimination of outlier points. The assay shows a variety of inhibitor effects that may be considered typical for this transporter: potent inhibition by p-hydroxymercuribenzoate, but not by other types of sulfhydryl reagents; marked inhibition by phloretin, quercitin, and 1-fluoro-2,4-dinitrobenzene; lack of inhibition by the amine-reactive agents that block the chloride/carbonate exchanger, DIDS and SITS; and reversible competitive inhibition by alpha-cyano-4-OH-cinnamic acid. Harmaline and N-I-succinimide also produced effective inhibition. The assay also demonstrated transacceleration of L-lactate efflux in the presence of external additions of D-lactate, glycollate, iodoacetate, fluoropyruvate, and bromopyruvate, which are substituted monocarboxylates like lactate, but not by iodoacetamide or L-alanine. Such activation is a manifestation of a macromolecular carrier in operation, and cannot be explained by a pore or channel. These findings satisfy all reasonable criteria for a satisfactory and sensitive lactate transporter assay, which should be adequate to evaluate volunteers and patients for the normal range of this carrier, and to seek possible deficient states.

Carrier Proteins↗
PubMed1988

Clinical assay of the human erythrocyte lactate transporter. II. Analysis and display of normal human data.

We have applied a lactate efflux assay to human red cells at two temperatures and with initial lactic acid loads up to 8 mM, metabolically generated. Efflux was about 1.5 times faster at external pH of 8.5 than at 7.5; the latter was the standard pH used thereafter. Multiple lactate loads in a single blood specimen demonstrated clear evidence of saturation kinetics at both pH levels, since the efflux rate did not increase proportionally with the lactate load. Best-fitting rectangular hyperboles were determined for 129-131 assays from 43 volunteers at 20 degrees and 30 degrees. In most cases high and low lactate loads permitted a two-point evaluation of saturation kinetics, and a positive indication was obtained in 88 of 89 tests. The apparent efflux Km and Vm values may be influenced by pH as well as by lactate levels and cannot be taken as rigorous, although they agree reasonably well with literature data on influx and exchange velocities. The data displayed a Hill constant of 1, a 30 degrees/20 degrees velocity ratio of 2.7, and no significant clustering by sex or age. A single assay with initial lactate level above 5 mM at 30 degrees should be sufficient to identify cases with a defective transporter, using the 95% tolerance limits developed in this report.

Carrier Proteins↗
PubMed1987

Calcium uptake in frozen muscle biopsy sections compared with other predictors of malignant hyperthermia susceptibility.

The frozen-section Ca45 uptake procedure of Mabuchi and Sreter has been applied to 51 frozen human muscle biopsies previously tested for halothane and for caffeine contracture responses. In preliminary tests with cat muscle, uptake varied with skeletal muscle fiber type, was absent from smooth muscle, and was blocked by agents which damage or extract sarcoplasmic reticulum. In the human biopsies, however, the calcium uptake values showed no significant correlation with any of the following parameters: time of frozen-biopsy storage up to 5 yr; fiber type distribution; positive versus negative response in the halothane contracture test; positive versus negative response in the caffeine contracture test; positive versus negative response in the combined halothane/caffeine contracture test; and presence of a documented clinical episode of malignant hyperthermia. In contrast, a positive halothane or caffeine contracture test each correlated highly with the presence of a prior clinical episode. We conclude that the evidence fails to support the use of the Ca45 uptake procedure in frozen sections of skeletal muscle biopsies as a valid indicator of malignant hyperthermia susceptibility.

Animals↗
PubMed1986

Lactate transporter defect: a new disease of muscle.

New methods were used to identify the abnormality in a patient who showed evidence of neuromuscular dysfunction on extensive clinical examination. The methods revealed that the lactate content of the patient's skeletal muscle does not decline normally after exercise and that his red cells are defective in lactate transport. These results suggest that skeletal muscle and erythrocyte membranes share the same genetic lactate transporter (or a common subunit), which is deficient in this patient. This defect may be a common cause of elevated serum creatine kinase levels, as seen in the patient described here and of unexplained episodes of rhabdomyolysis and myoglobinuria.

Adult↗
PubMed1986

Myoadenylate deaminase deficiency: primary and secondary types.

Myoadenylate deaminase deficiency, the most common of the known enzyme deficits of muscle, appears to occur in two forms. The primary type seems to be inherited as a complete gene block in an autosomal recessive pattern. Although occasionally diagnosed in infancy, when muscle biopsy is performed on a hypotonic but normoreflexic child, the deficiency is usually not symptomatic until adult or middle age, when muscle cramping and exercise intolerance develop. The skeletal muscle isozyme is immunologically, and presumably genetically, unique, and these patients have normal levels of adenylate deaminase in their other cells and tissues. A presumptive diagnosis can usually be made by an ischemic forearm exercise test, which shows a negligible increase in blood ammonia, despite a normal rise in lactate. Despite the absence of more than 99% of normal adenylate deaminase activity, the muscle biopsy shows no anatomic pathology, and other enzymes are at normal levels. These patients do not suffer progressive disease, and should be reassured and encouraged to maintain physical activity. The heterozygous state is probably asymptomatic, except, perhaps, on extreme exercise, but may be associated with an increased incidence of malignant hyperthermia susceptibility. Since the gene defect is not rare, it is not surprising that some cases of the deficiency will be coincidentally associated with other neuromuscular disease. However, there is also a secondary form of myoadenylate deaminase deficiency, consequent to muscle damage from other disease. In this form, the residual activity is higher (1-10% of normal), may present rare foci of positive stain in the section, and reacts normally with antibody to the muscle isozyme. Other muscle enzymes are also depleted, although not as severely, and the prognosis in such cases is dictated by the primary disease. Since the heterozygous state is common, these patients might have been carriers whose adenylate deaminase levels have been lowered to the deficient category by the advent of other neuromuscular disease.

AMP Deaminase↗
PubMed1985

Myoadenylate deaminase deficiency: inherited and acquired forms.

Myoadenylate deaminase deficiency, the most common of the known enzyme deficits of muscle, appears to occur in two forms. The primary type seems to be inherited as a complete gene block in an autosomal recessive pattern. Although occasionally diagnosed in infancy, when muscle biopsy is performed on a hypotonic but normoreflexic child, the deficiency is usually not symptomatic until adult or middle age, when muscle cramping and exercise intolerance develop. The skeletal muscle isozyme is immunologically, and presumably genetically, unique, and these patients have normal levels of adenylate deaminase in their other cells and tissues. A presumptive diagnosis can usually be made by an ischemic forearm exercise test, which shows a negligible increase in blood ammonia, despite a normal rise in lactate. Despite the absence of more than 99% of normal adenylate deaminase activity, the muscle biopsy shows no anatomic pathology, and other enzymes are at normal levels. These patients do not suffer progressive disease, and should be reassured, and encouraged to maintain physical activity. The heterozygous state is probably asymptomatic, except, perhaps, on extreme exercise, but may be associated with an increased incidence of malignant hyperthermia susceptibility. Since the gene defect is not rare, it is not surprising that some cases of the deficiency will be coincidentally associated with other neuromuscular disease. However, there is also a secondary form of myoadenylate deaminase deficiency, consequent to muscle damage from other disease. In this form, the residual activity is higher (1-10% of normal), may present rare foci of positive stain in the section, and reacts normally with antibody to the muscle isozyme. Other muscle enzymes are also depleted, although not as severely, and the prognosis in such cases is dictated by the primary disease. Since the heterozygous state is common, these patients might have been carriers, whose adenylate deaminase levels have been lowered for the deficient category by the advent of other neuromuscular disease.

AMP Deaminase↗
PubMed1985

Myoadenylate deaminase deficiency and malignant hyperthermia susceptibility: is there a relationship?

Muscle biopsies from 35 patients referred for possible malignant hyperthermia were subjected to contracture testing with halothane, caffeine, and the combined agents, histopathological and fiber-type-distribution analysis, and quantitative assay of three major muscle enzymes: adenylate deaminase, adenylate kinase, and creatine kinase. Adenylate kinase and creatine kinase were in the normal range in all biopsies and each averaged 92% of expected normal value when corrected for their fiber-type distribution. Of the 14 cases with a positive halothane test, 2 had primary myoadenylate deaminase deficiency, and 5 others had low levels of this enzyme (less than one-third normal). In contrast, only 3 of 21 cases negative to halothane testing had low adenylate deaminase levels, and none were deficient. This association was significant by several statistical tests, although it would not be highly predictive for an individual case. A positive halothane test also correlated with a high type 2 fiber contribution, but this was probably secondary, since cases with low enzyme levels had significantly higher type 2 fiber areas. Caffeine contractures did not correlate with either low enzyme levels or with fiber-type distribution. Sixty percent of the biopsies were entirely normal histologically, and showed a significant correlation with a negative combined contracture test. Data on the one family included in this study suggest separate inheritance of the trait for myoadenylate deaminase deficiency and the trait for positive contracture tests. The present findings suggest that patients with myoadenylate deaminase deficiency (and the carrier state as well) may be at increased risk of malignant hyperthermia when subjected to anesthesia.

AMP Deaminase↗
PubMed1985

Some practical considerations in quantitative absorbance microspectrophotometry. Preparation techniques in DNA cytophotometry.

An experimental review of the Feulgen and gallocyanine-chrome-alum stains for quantitative cytophotometry of DNA in tissue sections yielded information on the preparation and staining of tissue for quantitative absorbance microspectrophotometry. (1) Tissues routinely fixed in formalin are suitable for either stain. Specimens fixed with glutaraldehyde-containing fixatives are not satisfactory for Feulgen staining, nor are ethanol-fixed specimens, unless they are post-fixed in formalin. (2) The pararosaniline dyes, used in the Feulgen stain, are sufficiently pure to use if a solution of the dye in ethanol shows an absorbance peak at 543 to 546 nm. (3) The Feulgen stain provides good reproducibility when the staining solution is adjusted to pH 1.5. (4) Gallocyanine is the best stain to use on Bouin-fixed or glutaraldehyde-fixed tissues. (5) Where fixation is an option, Carnoy and methanol-formalin-glacial acetic acid are excellent fixatives that can be followed by either stain. (6) Selection of the thickness of a tissue section involves a compromise. Requirements of minimum nuclear overlap and sharp focusing favor a section thickness of 4 micron to 6 micron. On the other hand, the requirement for full nuclear thickness, as judged by absorbance equivalent to that of a touch preparation, demands sections as thick as 8 micron in the case of mouse liver. Within this range, the optimum thickness, therefore, is determined by the particular tissue, the range of its nuclear sizes and its packing density. (7) The refractive index of the mounting medium should be closely matched to that of the background structure of the tissue sections. For animal tissues, we found that media with refractive indices of 1.54 to 1.56 are suitable.

Animals↗
PubMed1978

Myoadenylate deaminase deficiency: a new disease of muscle.

Five cases of a new disease presented with muscular weakness or cramping after exercise; three of the cases also had an elevated serum creatine phosphokinase. Muscle biopsies were histologically normal but lacked adenylate deaminase by stain and solution assay, while the erythrocyte isozyme was normal. A clinical diagnostic test has been developed, and the human enzyme was separated by acrylamide-gel electrophoresis.

AMP Deaminase↗
PubMed1977

Electron microscopy of negatively stained jackbean urease at three levels of quaternary structure, and comparison with hydrodynamic studies.

Electron microscopy, with sodium phosphotungstate as negative stain, has been carried out on purified jackbean urease prepared at three levels of quaternary structure: (a) A1 urease, Mr = 240 000, S20,W = 11.5 S (b) alpha urease, Mr = 480 000, S20,w = 18.3 S (c) polymers of alpha urease above the tetramer stage. The compatibility of the images from level to level leaves no doubt that the enzyme itself is being visualized, and the following geometry is suggested by electron microscopy: A1 molecules are cyclic trimers, which pair up in eclipsed position across a 1-nm cleft to form the hexameric alpha, which displays D3 (or 32) symmetry of a trigonal prism. Polymers consist of alpha molecules aligned with their clefts coplanar and an angle of 120 degrees between each triplet of 3-fold axes. These features correspond reasonably well with sedimentation and electrophoretic studies of the solvated enzyme, which have indicated a hemispherical A1, a spherical alpha, and string-of-beads polymers. Sedimentation constants of the urease polymers up through the pentamer level were found to be compatible with the rosette, straight-chain, and zig-zag forms seen in the electron microscope, and with the suggested protomer arrangement in A1 and alpha urease.

Macromolecular Substances↗