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Biomedical subjects

M Burke

Publications and source records attributed to M Burke.

At least 307 records · Page 17Linked to original sources
PubMed1987

Family system and individual child correlates of sibling behavior.

In this study of the connections between marital adjustment and sibling behavior, the best predictor of younger siblings' prosocial behavior was found to be low interparental conflict. Older siblings' prosocial behavior was most associated with the mothers' marital adjustment. Younger siblings' agonistic behavior was related to marital adjustment and to the older children's activity level.

Child↗
PubMed1987

Sarcoidosis presenting with acute pleurisy, hemoptysis, pruritus and eosinophilia.

Sarcoidosis carries a low prevalence in Israel, and acute pleural involvement in sarcoidosis is uncommon throughout the world. We report a case of a young Israeli male of Yemenite origin who presented with atypical manifestations of sarcoidosis: pleuritic pain, hemoptysis, pruritus and alcohol-induced pain. The differential diagnosis from Hodgkin's disease was involved. Various aspects of diagnosis are discussed.

Acute Disease↗
PubMed1987

Cardiac rupture in patients with acute myocardial infarction.

The occurrence of myocardial rupture was evaluated in an unselected population of 1,737 patients with acute myocardial infarction (AMI). Patients with cardiac rupture after AMI were compared with age- and sex-matched control patients with fatal AMI not related to rupture and with AMI survivors discharged home. Rupture was found in 40 patients (15.7 percent of hospital deaths), or 2.3 percent of all cases of AMI. At the highest risk for rupture were women aged 60 to 69, although the age distribution did not differ significantly from that of patients dying of other causes. More patients with myocardial rupture had hypertension during hospitalization, persistent pain, and inferior wall myocardial infarction when compared with controls. The majority (95 percent) of cardiac ruptures occurred within the first six days, 40 percent within the first 24 hours after the onset of symptoms. Approximately 20 percent of ruptures were diagnosed as subacute; in only two was surgical intervention attempted unsuccessfully. The high-risk group of patients should be carefully monitored within the first six days after the onset of symptoms of AMI in an effort to prevent myocardial rupture.

Adult↗
PubMed1986

Substructure of skeletal myosin subfragment 1. Preferential destabilization of a domain by methanol and its effect on catalytic activity.

Evidence is presented that in increasing concentrations of methanol the structure of the subfragment 1 is perturbed in such a way that the Mr = 50,000 central portion of the associated heavy chain is preferentially unfolded. This unfolding is accompanied by the loss in ATPase function where the rate of inactivation can be correlated with the loss in the amount of the Mr = 50,000 fragment generated under standard tryptic digestion conditions. The residual protein appears to be a soluble aggregate of a complex of the Mr = 27,000, 21,000, and light chain with no intact Mr = 50,000 fragment. Tryptic digestions in the presence of MgATP are restricted to the usual linker regions and the Mr = 50,000 fragment is completely protected from attack. Binding of actin to subfragment 1 also results in the protection of the Mr = 50,000 segment and of the Mr = 50,000/21,000 junction from tryptic attack. The data suggest that, in terms of methanolic perturbation, the subfragment 1 appears to be comprised of two domains with differential stability. One domain appears to be the central Mr = 50,000 segment of the heavy chain which is preferentially unfolded by methanol and requires the presence of MgATP or of actin for stabilization. The other domain is more stable and appears to consist of the interacting Mr = 27,000, 21,000, and light chain. The results also suggest that the integrity of the Mr = 50,000 segment is essential for the ATPase function of the protein.

Animals↗
PubMed1986

Stability and substructure of cardiac myosin subfragment 1 and isolation and properties of its heavy-chain subunit.

The substructure and the thermal stability of the subunit interactions of bovine cardiac myosin subfragment 1 (SF1) have been examined. The results are in agreement with previous reports that the cardiac protein is cleaved in a very similar manner [Flink, I. L., & Morkin, E. (1982) Biophys. J. 37, 34; Korner, M., Thiem, N. V., Cardinaud, R., & Lacombe, G. (1983) Biochemistry 22, 5843-5847] but at a much faster rate [Applegate, D., Azarcon, A., & Reisler, E. (1984) Biochemistry 23, 6626-6630] than the skeletal protein. Additionally, it is found that the long-lived, steady-state intermediates formed by these proteins with MgATP at high ionic strength differ in their susceptibilities to tryptic attack especially at the 27K/50K junction of the associated heavy chains, suggesting a different conformation for these intermediates of the cardiac and skeletal SF1's. The thermal stability of the subunit interactions under conditions approaching the physiological state was examined by thermal ion-exchange chromatography of cardiac SF1 at 39.5 degrees C in the presence of MgATP. This results in the separation of part of the protein as the isolated heavy chain which is found to exhibit high levels of ATPase activity in the absence and presence of actin. Tryptic digestion of cardiac SF1 prior to thermal ion-exchange chromatography produces greater dissociation, with the heavy chain in this case being isolated as a complex of 27K, 50K, and 18-20K fragments.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1986

Isolation of heavy chain isoenzymes of myosin subfragment 1 by high performance ion exchange chromatography.

The procedure of high performance ion-exchange chromatography has been used to fractionate subfragment 1 of myosin (SF1) into its isoenzymic forms. In contrast to conventional ion-exchange procedures which yield two fractions corresponding to SF1(A1) and SF1(A2), the high performance liquid chromatography (HPLC) procedure resolves SF1 into four discrete fractions. The first pair that is eluted appears to be A1-containing isoenzymes while the latter pair corresponds to the A2 forms based on their polypeptide compositions by gel electrophoresis in the presence of sodium dodecyl sulfate. By gel electrophoresis under nondenaturing conditions it is not possible to differentiate between the two fractions corresponding to each isoenzyme. Although very minor differences between the fractions can be seen by the presence of extraneous peptides, these are present in far below stoichiometric amounts and, therefore, make it very unlikely that the superior fractionation by the HPLC procedure is based on their presence. An examination of the heavy chain heterogeneity in each of these fractions by peptide mapping revealed that the extra separation was based on this factor. Thus the HPLC procedure is capable of providing separation of SF1 into heavy chain-based isozymes as well as the light chain forms. ATPase measurements of these fractions reveal only minor differences in the Ca2+- and EDTA-activated ATPase.

Adenosine Triphosphatases↗
PubMed1986

Perinatal listeriosis. A report of six cases.

The clinical and pathological findings in six patients with perinatal listeriosis are presented. One pregnancy resulted in a live-born infant who developed listerial septicaemia but made a complete recovery following prompt treatment. The other pregnancies ended in intrauterine death. Often antecedent maternal prodromal illness preceded expulsion of a macerated fetus by only a matter of hours making early diagnosis difficult. In all cases the diagnosis of listerial infection was apparent only after the birth of the fetus or new born.

Adult↗
PubMed1986

Postseptal cellulitis: CT in diagnosis and management.

Thirteen orbital computed tomographic (CT) scans were obtained in 12 patients with postseptal (orbital) cellulitis. Sinus radiographs, which were also obtained, were not helpful in diagnosis or management. The location and extent of the inflammatory process was accurately demonstrated with axial CT scans in all cases. A protocol using CT in the management of postseptal cellulitis is proposed.

Adolescent↗
PubMed1986

Cardiac size and VO2max do not decrease after short-term exercise cessation.

We measured maximum oxygen uptake, estimated changes in plasma volume, and the cardiac dimensions of 15 male competitive distance runners (28.2 +/- 5.6 yr of age, mean +/- SD) before and after 10 days of exercise cessation. Subjects were habitually active but adjusted their training to run 16 km daily for 2 wk before the study. Subjects were maintained on defined diets for the week before and during the detraining period. Average body weight decreased 1.0 +/- 0.5 kg (P less than 0.001) within 2 days of exercise cessation and was accompanied by a 5.0 +/- 5.9% (P less than 0.01) decrease in estimated plasma volume. No additional changes in body weight and plasma volume occurred during the study, and estimated percent body fat did not change. Resting heart rate, blood pressure, and cardiac dimensions were also unchanged with physical inactivity. In addition, maximum oxygen uptake was not altered although peak exercise heart rate was an average of 9 +/- 5 beats X min-1 (P less than 0.01) or 5% higher after detraining. We conclude that short periods of exercise cessation decrease estimated plasma volume and increase the maximum exercise heart rate of endurance athletes but do not alter their cardiac dimensions or maximum oxygen uptake.

Adaptation, Physiological↗
PubMed1985

Small bowel biopsy for malabsorption: comparison of the diagnostic adequacy of endoscopic forceps and capsule biopsy specimens.

Biopsy specimens of the small bowel were obtained from 40 patients suspected of having malabsorption. Four different techniques were used at a single session--namely, endoscopic biopsy of the descending duodenum using paediatric and standard size forceps and suction capsule biopsy of the descending duodenum and the proximal jejunum. Specimens were compared for size, adequacy, and ability to confirm or exclude mucosal abnormality. Fourteen patients had villous atrophy. In all patients four biopsy specimens were obtained with paediatric endoscopic forceps and four with standard endoscopic forceps. No capsule biopsy specimen was retrieved from the duodenum in three patients and from the jejunum in five patients. Specimens were considered to be adequate in 36 patients when paediatric forceps were used, in 39 when standard forceps were used, in 28 on duodenal capsule biopsy, and in 32 on jejunal capsule biopsy. This study indicates that the most reliable method for diagnosing or excluding villous atrophy is endoscopic forceps biopsy of the descending duodenum, provided that at least four specimens are obtained with standard size forceps.

Adult↗
PubMed1985

Differentiation between benign and malignant disease of the breast using digital subtraction angiography of the breast.

The authors have investigated digital subtraction angiography (DSA) for the differential diagnosis of breast lesions detected initially by mammography. Eighteen patients scheduled for biopsy first underwent digital subtraction angiography of the breast (DSAB). Criteria for malignancy included the presence of abnormal vessels and a "blush" in the area of the lesion. A total of 17 lesions are currently available for histopathologic correlation. Although this is a small series, the initial results of DSAB suggest its potential utility for differentiating between benign and malignant lesions.

Angiography↗
PubMed1985

Effect of tryptic cleavage on the stability of myosin subfragment 1. Isolation and properties of the severed heavy-chain subunit.

The procedure of thermal ion-exchange chromatography has been used to examine the effect of prior tryptic cleavage on the stability of myosin subfragment 1 (SF1). Although it is found that digestion does destabilize the subunit interactions at physiological temperatures, the heavy-chain subunit can be isolated either as an equimolar complex comprised of 50K, 27K, and 21K fragments or as one comprised of 50K, 27K, and 18K peptides. Thus, the interactions within the heavy chain are considerably more stable than those between the two subunits. Both forms of the free severed heavy chain exhibit ATPase properties similar to those of the parent tryptic SF1. The Vmax for the actin-activated MgATPase of the free severed heavy chain is the same as that for both undigested and tryptic SF1 (A2). Since its Km for actin is similar to that of tryptic SF1(A2), it may be concluded that changes in the affinity of SF1 for actin induced by trypsin [Botts, J., Muhlrad, A., Takashi, R., & Morales, M. F. (1982) Biochemistry 21, 6903-6905] are not dependent on the presence of the associated alkali light chain. Furthermore, the communication between the SH1 site and the ATPase site is also shown to be independent of the associated alkali light chain, and it persists despite the cleavages present in the free heavy chain. Studies on the ability of these severed heavy chains to reassociate with free A1 and A2 chains indicate that the binding site is retained in the 21K-severed heavy chain but is lost in the 18K form.

Adenosine Triphosphatases↗