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Biomedical subjects

A Keynan

Publications and source records attributed to A Keynan.

At least 37 records · Page 2Linked to original sources
PubMed1988

"Intermittent" and transient ST-segment elevation following direct current cardioversion.

Transient ST-segment elevation immediately following direct current cardioversion is a clearly documented occurrence in a small percentage of cases. Two main explanations have been suggested: myocardial injury or coronary vasospasm. We report two cases of "intermittent" and transient ST-segment elevation after cardioversion. Such intermittent elevation of the ST segment has not been reported previously. We hypothesize that this electrocardiographic observation is explained by a timing difference induced by electroshock in the action potential between the epicardium and endocardium.

Action Potentials↗
PubMed1988

Membrane binding and release of Bacillus subtilis DNA as a function of the cell cycle.

The presence of origin-region DNA in preparations containing bacterial cell wall and cytoplasmic membrane is well established, but little is known about the relationship between this association and events of the cell cycle. We have observed, during renewed growth of stationary-phase cultures of Bacillus subtilis, an association of DNA, including newly synthesized regions, with a specific region of the plasma membrane. Attachment was transitory, occurring once per replication cycle, and was prevented by inhibitors of cell wall synthesis.

Acetylglucosamine↗
PubMed1988

Bacteria of the genus Bacillus have a hydrolase stereospecific to the D isomer of benzoyl-arginine-p-nitroanilide.

A stereospecific enzyme activity capable of cleaving the amide bond of the synthetic substrate N-benzoyl-D-arginine-p-nitroanilide (D-BAPA) has been found in all aerobic and anaerobic members of the family Bacillaceae tested by us. Cells of nonsporeforming gram-positive or gram-negative bacteria contain a hydrolase activity stereospecific to N-benzoyl-L-arginine-p-nitroanilide. The D-BAPA-hydrolyzing enzymes (D-BAPAases) of mid-logarithmic-phase cells of Bacillus subtilis 168 and B. cereus T were compared. These enzymes had the same molecular weight of approximately 66,000 in gel filtration and the same electrophoretic mobility after electrophoresis on polyacrylamide gels. The D-BAPAases of B. subtilis 168 and B. cereus T differed in the effect of inhibitors on enzymatic activity. While both hydrolases were inhibited by tosyl-L-lysine chloromethyl ketone and tosyl-L-arginine-methyl ester as well as leupeptin, only the D-BAPAase of B. cereus T was inhibited by p-chloromercuribenzene sulfonic acid. The D-BAPAases of B. subtilis and B. cereus T had a Michaelis constant for D-BAPA of 2.9 x 10(-5) M and 1.4 x 10(-4) M, respectively. D-BAPAase is an intracellular enzyme localized in the protoplast (80 to 90% in soluble form in the cytoplasm). The ability to cleave D-BAPA is suggested as an additional chemotaxonomic characteristic of sporeforming bacteria of the genera Bacillus and Clostridium.

Bacillus↗
PubMed1987

Virus-specific serum IgG, IgM, and IgA antibodies in cytomegalovirus mononucleosis patients as determined by immunoblotting technique.

The immune response to individual human cytomegalovirus (CMV) structural polypeptides was studied in paired sera from 15 adult CMV mononucleosis (CMV-MN) patients and healthy controls by immunoblotting technique (IB). IgM and IgG antibodies to at least 11 structural polypeptides with molecular weights of 28K, 49K, 55K, 57K, 66-70K, 82K, 87K, 110K, 150K, 205K, and 235K were detected in the patients' sera in the serum sample obtained in the acute phase of the disease. IgA antibodies to polypeptides with molecular weights of 66-70K, 82K, 110K, and 150K were also detected in these sera. In healthy seropositive adults, IgG antibodies with the same molecular weight polypeptides, excluding the 205K and 235K polypeptides, were detected as in convalescent CMV-MN patients. A prominent reactivity of IgM and IgA antibodies to the 66-70K and 150K polypeptides was noted in the acute sera from all the CMV-MN patients examined, but not in a number of late convalescent sera. The potential implications of these findings in the development of specific serological tests are discussed.

Acute Disease↗
PubMed1987

Reliability of global rating scales in the assessment of clinical competence of medical students.

Undergraduate medical students of the Ben Gurion University were evaluated upon completion of their fourth- and sixth-year medical clerkships by a 17-item rating scale, a multiple choice question (MCQ) test and a patient-oriented oral examination by two academic staff members. Pearson's correlation coefficient between the fourth-and sixth-year global ratings was r = 0.44 (P less than or equal to 0.001), while that between the fourth- and sixth-year MCQ scores was r = 0.54 P less than or equal to 0.001). Pearson's coefficient between the global ratings and the MCQ scores in the sixth year was r = 0.25 (P less than or equal to 0.05). Stepwise regression analysis revealed that the ratings on the parameters 'reliability', 'knowledge', 'organization', 'diligence' and 'case presentation' were the most predictive of the overall global rating. It is concluded that the reproducibility of 'subjective' expert assessment of performance through global rating scales is comparable to that of 'objective' evaluation through written MCQ, even though these measures assess different domains of competence at different levels of simulations. It is recommended that the clinical performance of undergraduate medical students should be assessed by a combination of subjective and objective measures.

Clinical Clerkship↗
PubMed1987

Cytomegalovirus mononucleosis--a report of 70 cases in a community hospital.

Seventy consecutive cases of cytomegalovirus mononucleosis (CMV-MN) were examined retrospectively from their clinical, epidemiological and serological aspects. The mononucleosis syndrome was complicated by various specific organ involvement in 15 (21%) of the patients. Serial serum samples were examined for specific CMV IgG, IgA and IgM antibodies by either the immunoperoxidase or enzyme-linked immunoassay techniques, or both. Specific anti-CMV IgM antibodies were found in 57 patients whose blood samples were collected for the first time at the second week of illness. In seven patients, CMV infection was diagnosed by a rise of specific IgG antibodies and the presence of specific IgA antibodies. These seven patients were generally older (mean age 68 years); four of them had a malignant disease and probably represent cases of recurrent CMV infection. An association between malignancy and recurrent CMV infection in the older age-group is suggested. Prompt diagnosis of CMV infection may exclude CMV-MN from the list of fevers of unknown origin, thus avoiding laborious patient workups.

Adolescent↗
PubMed1987

Persistence of a positive test for IgM antibodies to hepatitis A virus in late convalescent sera.

We had the opportunity to carry out a long-term follow up of 15 patients with viral hepatitis Type A. The serum IgM response to hepatitis A virus (HAV) was investigated with a commercially available kit (HAVAB-M). IgM antibodies were detected in all specimens collected during the acute phase of the disease and during early convalescence (first 3 months). However, there was a clear decrease in the "sample-to-cutoff" ratio (s/co ratio) after the first 2 months. Serum samples were available from six patients 30 to 32 months after onset of illness. Two of these were positive for IgM anti-HAV, but the s/co ratios were low. These results point to the need for careful evaluation of the diagnosis of acute or recent viral hepatitis Type A when low s/co ratios are obtained.

Acute Disease↗
PubMed1987

Selective right ventricular dysfunction following doxorubicin therapy.

Cardiotoxicity is one of the major side effects of doxorubicin therapy. The side effect presents in an acute and chronic form. It has been observed mainly when the cumulative dosage exceeds 450 mg/m2 of body surface. The cardiotoxicity presents with a low left ventricular ejection fraction. We report three patients who developed selective right ventricular dysfunction, expressed by low right ventricular ejection fraction as measured by radionuclide angiography. This complication was observed with rather low cumulative dosages of the drug (105 to 318 mg/m2). Two of the patients received concurrent mitomycin-C chemotherapy and the third patient underwent prior mediastinal irradiation. The possible mechanism for this selective cardiotoxicity is discussed. Monitoring of right ventricular performance by radionuclide angiography during doxorubicin therapy is recommended so that therapy can be discontinued before the left ventricle is damaged.

Adult↗
PubMed1986

Scabies-associated angioimmunoblastic lymphadenopathy.

A systemic disorder characterized by fever and reactive lymphadenopathy developed in a patient with scabies infestation. Regression of all clinical symptoms and signs occurred after antiscabies therapy. Two months later, the whole clinical picture reappeared concomitantly with scabies reinfestation. Subsequent lymph node biopsy demonstrated typical angioimmunoblastic lymphadenopathy (AILD). It is plausible that persistent antigenic stimulation caused by scabies infection was of pathogenetic importance in the induction of the syndrome of AILD. Infectious agents should be considered and looked for in patients with AILD, since they may play a role in the evolution of this disease.

Aged↗
PubMed1986

Treatment of congenital immune deficiencies with a thymic hormone--thymic humoral factor.

Five infants with congenital immune defects are presented. Three had various combined immune deficiencies (CID) and two had thymic deficiencies only. As bone marrow or thymus transplantations were not feasible in these patients, we attempted treatment with thymic humoral factor (THF), a thymic hormone, by daily i.m. injections during biweekly courses. In one CID patient, a partial improvement in immune indices and temporary clinical improvement were achieved. In the other two, THF did not arrest the patients' demise. The two patients with thymic dysplasia benefitted repeatedly from THF treatment, as exemplified by the disappearance of wasting, diarrhea and infections and by reconstitution of T cell parameters. Nevertheless, the patients relapsed after prolonged periods without THF administration. We therefore propose the administration of long-term, continuous or intermittent thymic hormone replacement therapy in infants with congenital thymic defects. Early diagnosis and immediate institution of treatment will probably improve prognosis.

Female↗
PubMed1986

Echis colorata bites: clinical evaluation of 42 patients. A retrospective study.

A retrospective study of 42 patients bitten by Echis colorata in the last 26 years is reported. Twenty-eight patients received and 14 patients did not receive specific antivenin. The clinical findings, laboratory studies, and course of hospitalization revealed hemostatic disturbances in most of the patients. One of the untreated patients died in the period when antivenin was not available. We recommend that antivenin be given, following appropriate clinical and laboratory assessment, to patients bitten by E. colorata who have progressive local signs and major alterations in the clotting mechanism. The usual precautions against allergic reactions should be taken.

Adolescent↗
PubMed1985

Trypsinlike enzymes from dormant and germinated spores of Bacillus cereus T and their possible involvement in germination.

Trypsin-like enzymes were studied in dormant, activated, and germinated spores of Bacillus cereus T. Dormant spores contained two heat-labile enzyme activities. One was extractable with 2 M KCl and hydrolyzed azo-albumin. The second, a trypsinlike activity, was not extractable with 2 M KCl and hydrolyzed benzoyl-L-arginine-p-nitroanilide. Because of their heat instability, these two enzyme activities are probably not involved in the germination of heat-activated spores. Upon germination of heat-treated spores, a trypsinlike protease which was not detected in intact dormant spores was activated or exposed. This enzyme, when measured in intact germinated spores, hydrolyzed benzoyl-DL-arginine-p-nitroanilide but not azo-albumin and was inhibited in situ by sulfhydryl-blocking reagents such as p-chloromercuribenzoic acid and Hg2+. There was a correlation between the inhibition of germination and enzymatic activity by sulfhydryl-blocking reagents. The enzyme was also inhibited by leupeptin, tosyl-L-lysine chromoethyl ketone, and tosyl-L-arginine methyl ester. Good correlation existed between the inhibition of germination and enzymatic activity by these agents. Electron micrographs showed that in the presence of trypsin inhibitors, the spores did not lose their cortex. The protein extracts of the inhibited spores formed a somewhat different electrophoretic pattern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis than the protein extracts of dormant or germinated spores.

Bacillus cereus↗
PubMed1985

Acid base balance in blood and cerebrospinal fluid.

Thirty four infants were studied; 21 with acute gastroenteritis, dehydration, and metabolic acidosis and 13 who served as controls. All infants with metabolic acidosis and without neurological signs had a normal to near normal cerebrospinal fluid acid base balance, but five with metabolic acidosis and severe neurological signs had cerebrospinal fluid acid base disequilibrium. Acute metabolic acidosis in infants may lead to cerebrospinal fluid acid base imbalance causing cerebral dysfunction.

Acid-Base Imbalance↗
PubMed1984

The use of gallium-67 liver imaging for the early diagnosis of Budd-Chiari syndrome.

A gallium-67 study, performed in a rare case of Budd-Chiari syndrome (BCS) in a 6-yr-old child, showed marked concentration of the tracer in the left and caudate lobes of the liver. Ten days later, a less specific and clear-cut appearance of left- and caudate-lobe concentration of Tc-99m phytate was obtained. The possible use of Ga-67 citrate imaging to diagnose BCS in its earliest stage is suggested, although no firm conclusion can be made from this single case.

Budd-Chiari Syndrome↗
PubMed1983

Detection and persistence of specific IgA antibodies in serum of patients with hepatitis A by capture radioimmunoassay.

The serum immunoglobulin A (IgA) response to hepatitis A virus (HAV) was investigated with a sensitive capture radioimmunoassay. In serial serum samples drawn from 15 patients with viral hepatitis A, IgA anti-HAV antibodies reached their highest titer between 1-2 weeks after onset and peak titers ranged from 10,000-20,000. Serum samples were available from six patients 30-32 months after onset of illness. These samples were all positive for IgA anti-HAV and some had titers similar to peak titers during illness. However, the height of the titration curves, expressed as the binding ratio (BR) at a dilution of 1/1000, was in all cases significantly lower at 30-32 months than during acute illness and early convalescence. The significance of the persistence of the IgA anti-HAV and possible reasons for the change in the BR are discussed.

Antibodies, Viral↗
PubMed1983

Effect of inhibitors of trypsin-like proteolytic enzymes Bacillus cereus T spore germination.

The germination of Bacillus cereus T spore suspensions is partially prevented by several inhibitors of trypsin-like enzymes. Leupeptin, antipain, and tosyl-lysine-chloromethyl ketone are effective inhibitors, whereas chymostatin, elastatinal, and pepstatin are inactive. A synthetic substrate of trypsin, tosyl-arginine-methyl ester, also inhibits germination. Its inhibitory effect decreases as a function of incubation time in the presence of spores and is abolished by previous hydrolysis with trypsin. Germinating, but not dormant, spore suspensions hydrolyze tosyl-arginine-methyl ester; its hydrolysis is insensitive to chloramphenicol, sulfhydryl reagents, and EDTA. A crude extract of germinated B. cereus spores contains a trypsin-like enzyme whose activity, as measured by hydrolysis of benzoyl-arginine p-nitroanilide, is sensitive to germination-inhibitory compounds such as leupeptin, tosyl-arginine-methyl ester, and tosyl-lysine-chloromethyl ketone. Spore suspensions exposed to the above inhibitors under germination conditions lose only part of their heat resistance and some 10 to 30% of their dipicolinic acid content. Part of the germinating spore population becomes "phase grey" under phase optics. Based on a study of the inhibition of germination by protease inhibitors and the activity of a protease in germination spores and spore extracts, it is suggested that the activity of a trypsin-like enzyme may be involved in the mechanism of the breaking of dormancy in spores of B. cereus T.

Antipain↗