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Biomedical subjects

N C Kar

Publications and source records attributed to N C Kar.

At least 19 recordsLinked to original sources
PubMed2000

Recurrent alternating facial paralysis and malignant hypertension.

A previously healthy 11-year old girl with three episodes of alternating facial palsy is described. On examination during the third relapse a severe essential hypertension was diagnosed, accompanied by abnormalities on cerebral imaging, cardiac and fundoscopic investigations. Antihypertensive treatment normalized the hypertension. No relapse of the facial palsy occurred since. The objective of this communication is to draw the attention to hypertension as a possible cause of recurrent facial paralysis in children, to stress the importance of measuring the blood pressure and taking a thorough family history in every patient presenting with facial palsy.

Antihypertensive Agents↗
PubMed1981

Muscle adenylate deaminase deficiency. Report of six new cases.

We describe six adult patients (five men and one woman) out of 364 whose muscle biopsy specimens disclosed muscle adenylate deaminase deficiency. Two men had an associated dermatomyositis and another man had an associated progressive systemic sclerosis. Although the patients were different clinically, all complained of muscular weakness or poor exercise tolerance. The occurrence of muscle adenylate deaminase deficiency in both sexes suggests a possible autosomal mode of inheritance.

AMP Deaminase↗
PubMed1980

Methylthioadenosine nucleosidase in normal and dystrophic human muscle.

Human skeletal muscle homogenate was found to contain a nucleosidase that catalyzes the hydrolysis of 5'-methylthioadenosine, a known inhibitor of many methyl transfer reactions. When the levels of methylthioadenosine nucleosidase in muscle of patients were compared with those of controls, no significant alterations in its activity were noted in patients with various forms of muscular dystrophies, polymyositis and certain denervating diseases.

Adenosine↗
PubMed1980

Muscle fructose 1,6-diphosphatase deficiency associated with an atypical central core disease.

A 25-year-old woman with a non-familial congenital nonprogressive myopathy was found to have atypical core-like lesions in type 1 muscle fibers. Typical core lesions (approximately 13 micrometers in diameter) and smaller, PAS positive (4.1 micrometers in diameter) atypical core were associated with a predominant type 1 fibre myopathy. A specific deficiency of fructose 1, 6-diphosphatase was found with normal values for nine other muscle glycolytic and mitochondrial marker enzymes. The data provide evidence for a specific muscle enzyme deficiency in a patient with atypical central core disease.

Adenosine Triphosphatases↗
PubMed1979

Catalase, superoxide dismutase, glutathione reductase and thiobarbituric acid-reactive products in normal and dystrophic human muscle.

The level of thiobarbituric acid-reactive products and the specific activities of catalase and glutathione reductase were significantly higher in muscles from patients with major forms of muscular dystrophies over those of control subjects. Superoxide dismutase activity was not altered in dystrophic muscles. These findings indicate the occurrence in human dystrophic muscles of an increased level of lipid peroxidation and the possible activation of certain enzymes that could conceivably inhibit lipid peroxidation in vivo.

Catalase↗
PubMed1979

Activity of some proteolytic enzymes in normal and dystrophic human muscle.

1. The following proteolytic enzymes were measured in muscles of control subjects and patients with muscular dystrophies and related neuromuscular diseases: an elastase-like enzyme, carboxypeptidase A, carboxypeptidase B and pyroglutamyl peptidase. 2. Elastase-like enzyme and carboxypeptidase B did not show significant alterations in various disease conditions that were examined. 3. Carboxypeptidase A was moderately elevated in dystrophic as well as other diseased muscles. 4. Pyroglutamyl peptidase was not markedly altered in any disease condition except that is was slightly lower in dystrophic muscles.

Carboxypeptidases↗
PubMed1979

Muscle breakdown and lysosomal activation (biochemistry).

Muscle tissue levels of lysosomal catheptic enzymes, such as cathepsins D, A, B1, C, and dipeptidyl peptidase II, were measured in control subjects and patients with muscular dystrophies, polymyositis, and certain denervating diseases. The results show that, in general, the activities of these enzymes are increased in muscles of patients with muscular dystrophies and other diseases. The increases in cathepsin D and autolytic activities are not significant until the late stage of the disease process. Cathepsins A, B1, and C are, however, significantly elevated in mildly affected dystrophic and other diseased muscles. Of these catheptic enzymes, cathepsin B1 displays the highest rise at an early stage, suggesting that it may be one of the rate-controlling enzymes of proteolysis. Dipeptidyl peptidase II is increased slightly in dystrophic and other myopathic muscles but is unchanged in denervated muscle. These data clearly implicate the lysosomal group of proteinases as largely responsible for mediating muscle breakdown in the muscular dystrophies and certain other muscle and neuromuscular diseases in man.

Animals↗
PubMed1978

Dipeptidyl peptidases in human muscle disease.

With the use of selective inhibitors of arylamidase, four dipeptyl peptidases (I, II, III, and IV) capable of hydrolyzing the beta-naphthylamides of Gly-Arg, Lys-Ala, Arg-Arg and Gly-Pro, respectively, were distinguished in homogenates of human muscle. Dipeptidyl peptidase I showed maximum activity at pH 5.0-6.0. Dipeptidyl peptidase II was maximally active at pH 5.0 and inhibited by cations. Dipeptidyl peptidases III and IV were most active at pH 8.5 and 7.5, respectively. When compared to controls, significant increases in muscle dipeptidyl peptidases I and II were observed in patients with muscular dystrophies and polymyositis. Dipeptidyl peptidase III was not altered in the neuromuscular disease examined. Dipeptidyl peptidase IV showed marked increase in a variety of muscle wasting conditions. The increase in dipeptidyl peptidases I and II may be attributed to lysosomal activation that is known to occur in conditions of muscle degeneration. However, the striking increase in a variety of muscle diseases of dipeptidyl peptidase IV, an enzyme shown to be associated with microsomal membranes in other tissues, suggest that in addition to lysosomes other sources also contribute to the total hydrolytic potential of diseased muscles. Dipeptidyl peptidases II and IV were found to be present in human serum. Their levels were not altered in serum of patients with Duchenne dystrophy.

Dipeptidases↗
PubMed1978

Recurrent myoglobinuria due to muscle carnitine palmityl transferase deficiency.

Three new cases of carnitine palmityl transferase deficiency are described. The syndrome consists of recurrent attacks of muscle cramps, weakness, malaise, and myoglobinuria. These attacks are especially likely to occur during prolonged exercise after fasting, eating a high-fat diet, or during cold weather. Occasionally after fasting alone, spontaneous muscle breakdown may occur. One patient studied in detail was excessively slow in producing ketones when he fasted. His mylagias and weakness appeared to be alleviated by beta-hydroxybutyrate. Of eight other patients thought to have idiopathic recurrent myoglobinuria, three were found to have myophosphorylase deficiency, whereas five did not have deficiency of either enzyme. Carnitine palmityl transferase deficiency may be more common than previously supposed, may be in part amenable to dietary therapy, can be easily distinguished from myophosphorylase deficiency, and may provide insight into the metabolism of fatty acids and ketone bodies as well as energy requirements of skeletal muscle.

Acyltransferases↗
PubMed1976

Arylamidases in normal and diseased human muscle.

Human skeletal muscle homogenates were found to contain enzymes that catalyze the hydrolysis of beta-naphthylamides of leucine, arginine and lysine, known substrates for neutral and basic arylamidases. They also contained a trace of activity towards alpha-aspartyl-beta-naphthylamide. The muscle arylamidases were found to be inhibited by p-chloromercuribenzoate, Hg2+ and puromycin. Leucyl, arginyl and lysysl arylamidases were slightly activated by cobalt ions. When compared to controls, no significant differences in muscle arylamidase activities were observed in patients with muscular dystrophies and certain denervating diseases.

Aminopeptidases↗
PubMed1976

Acid, neutral, and alkaline hydrolases in arthritic synovium.

The levels of six lysosomal enzymes (acid phosphatase, beta-acetylglucosaminidase, cathepsin D, beta-galactosidase, arylsulfatase A, and beta-glucuronidase) and four neutral and alkaline hydrolases (esterase, inorganic phyrophosphatase, alkaline phosphatase, and 5'-nucleotidase) were measured in osteoarthritic, rheumatoid and control synovia. All enzyme levels in diseased synovium except esterase values in osteoarthritis were significantly elevated compared with controls. The mean values of the group of acid hydrolases and the group of neutral and alkaline hydrolases in osteoarthritic synovia were 1.9- and 2.0-fold greater than those of control specimens. In rheumatoid synovia, the values were 4.2- and 4.5 fold greater than control for the same enzymes. Levels in rheumatoid synovia were significantly higher than those in osteoarthritic synovia with the exception of 5'-nucleotidase. Only a limited correlation between the extents of inflammation present in the synovia and the levels of a lysosomal marker enzyme (cathepsin D) was observed. These results demonstrate that whatever the mechanism, increased levels of acid hydrolases as well as certain neutral and alkaline hydrolases are present in osteoarthritic and rheumatoid synovia, and these enzymes are probably contained in the synovial lining cells.

Acetylglucosaminidase↗
PubMed1976

Arylamidase and cathepsin-A activity of normal and dystrophic human muscle.

Human skeletal muscle homogenate has been shown to contain enzymes that catalyze the hydrolysis of L-leucyl p-nitroanilide and carbobenzoxyglutamyl-L-tyrosine, known substrates, respectively, for arylamidase and cathepsin A. The muscle arylamidase was found to be inhibited by p-chloromercuribenzoate. Addition of Co2+ resulted in slight stimulation of its activity. Neither ethylenediamine tetraacetate nor thiol compounds had any appreciable effect on the enzyme. When compared to controls, no significant differences in muscle arylamidase levels were observed in patients with muscular dystrophies and certain selected neuromuscular diseases. Cathepsin A was, however, increased in muscles moderately affected by muscular dystrophy and denervating diseases.

Adolescent↗