Expression and functional assessment of a truncated cardiac troponin T that causes hypertrophic cardiomyopathy. Evidence for a dominant negative action

Mutations in the beta-myosin heavy chain gene are believed to cause hypertrophic cardiomyopathy (HCM) by acting as dominant negative alleles. In contrast, a truncated cardiac troponin T (TnT) that causes HCM implies that altered stoichiometry of contractile proteins may also cause cardiac hypertrophy. Wild-type and HCM-mutant (truncated) TnT were studied in a novel quail myotube expression system. Unexpectedly, antibody staining demonstrated incorporation of both forms of human cardiac TnT into the sarcomeres of quail myotubes. Functional studies of wild type and mutant transfected myotubes of normal appearance revealed that calcium-activated force of contraction was normal upon incorporation of wild type TnT, but greatly diminished for the mutant TnT. These findings indicate that HCM-causing mutations in TnT and beta-myosin heavy chain share abnormalities in common, acting as dominant negative alleles that impair contractile performance. This diminished force output is the likely stimulus for hypertrophy in the human heart.     

Sequence of the gene encoding a highly thermostable neutral proteinase from Bacillus sp. strain EA1: expression in Escherichia coli and characterisation

Ammonium assimilation was studied by feeding [15N]ammonium to actively growing mycelium of Agaricus bisporus. Products of ammonium assimilation were analysed using 15N-NMR. Participation of glutamine synthetase, glutamate synthase and NADP-dependent glutamate dehydrogenase was determined by inhibiting glutamine synthetase with phosphinothricin and glutamate synthase with azaserine. Our results clearly indicate that, under the conditions used, ammonium assimilation is mainly catalysed by the enzymes of the glutamine synthetase/glutamate synthase pathway. No indications were found for participation of NADP-dependent glutamate dehydrogenase. Furthermore, 15N-labelling shows that transamination of glutamate with pyruvate to yield alanine is a major route in nitrogen metabolism. Another major route is the formation of N-acetylglucosamine. Compared to the formation of N-acetylglucosamine there was only a limited formation of arginine.     

A male-specific nuclease-resistant chromatin fraction in the mealybug Planococcus lilacinus

BACKGROUND: The domestic mites Euroglyphus maynei and Blomia tropicalis frequently co-inhabit homes in subtropical/tropical regions around the world. Both species are the source of substances that cause allergic reactions in patients. OBJECTIVE: The purpose of this study was to examine the immunologic cross-reactivity between E. maynei and B. tropicalis. METHODS: Sera of 19 mite-sensitive patients who were skin test positive to B. tropicalis and/or RAST positive to E. maynei were used to probe immunoblots or crossed radioimmunoelectrophoresis (CRIE) gels. RESULTS: Western blotting showed that individual sera had IgE that bound to 0 to 17 and 2 to 15 proteins in E. maynei and B. tropicalis extracts, respectively. Corresponding IgE-binding proteins of 105, 75, 57, 18, and 14 kD were detected in both E. maynei and B. tropicalis extracts. The majority of IgE-binding proteins did not show corresponding bands in both extracts. Heterologous CRIE showed IgE binding to six of the nine E. maynei antigens precipitated by anti-B. tropicalis serum with individual sera recognizing 0 to 4 of the six allergens. In the reciprocal reaction, 10 of the 12 proteins of B. tropicalis that were precipitated by anti-E. maynei serum bound IgE with individual sera binding to 0 to 5 proteins. CONCLUSION: This study indicated that E. maynei and B. tropicalis are the source of both species-specific and cross-reactive allergens, but most allergens in each extract were species-specific.     

Preoperative ultrasound Doppler study and clinical correlation of free posterior interosseous flap

Age-related loss of strength contributes to impaired mobility and increases the risk of falls. Recent research has focused on 2 approaches to preventing age-related loss of strength--promoting physical activity and exercise (especially strength training) and using trophic factors to enhance muscle performance. Epidemiologic evidence strongly supports a role of regular physical activity in successful aging by preserving muscle performance, promoting mobility, and reducing fall risk. Randomized controlled trials provide convincing evidence that strength and endurance training improve muscle performance in older adults. Evidence is rapidly accumulating from randomized trials that endurance, strength, and balance training promote mobility and reduce fall risk, though exercise effects differ according to the type of exercise, details of the exercise program, and the target group of older adults. Because lifetime regular physical activity is recommended for all older adults, a reasonable strategy (especially for weak adults) is an activity program that includes strength training. In contrast, insufficient evidence exists to recommend the long-term use of trophic factors to preserve muscular performance. An intervention that merits additional study is avoiding the use of psychoactive drugs because drugs like benzodiazepines appear to be risk factors for inactivity and may have unrecognized direct effects on muscular performance. Because chronic illness is a risk factor for inactivity and disuse muscle atrophy, randomized trials comparing strength training with other interventions would be useful in understanding whether strength training has advantages in preserving muscle performance and improving health-related quality of life in a variety of chronic illnesses such as depressive illness.     

High incidence of precipitins in sera of heroin addicts

We analyzed sera of 50 consecutively hospitalized heroin-abuse patients for precipitins against several antigens. Forty-seven addicts had precipitins against extracts from moldy hay, and 34 against extracts from bagasse. Thirty-six showed precipitin bands against extracts from one or more of the following: Aspergillus, Micropolyspora faeni, and Thermoactinomyces vulgaris. These findings were significantly different from those of a control population (P less than .0001 for all antigens tested). The recent culture identification of bacteria and fungi from street heroin suggests that the addicted population may be injecting antigenic material intravenously, with subsequent antibody formation.     

Bilateral subclavian artery aneurysm associated with idiopathic cystic medial necrosis

Although cystic medial necrosis, either idiopathic or associated with Marfan's syndrome, usually becomes manifest as an ascending aortic aneurysm, aortic insufficiency, aortic dissection, or a combination of these disorders, a rare case of bilateral subclavian artery aneurysm secondary to idiopathic cystic medial necrosis has occurred. Subclavian artery aneurysms most commonly represent poststenotic dilatation from anterior scalene or cervical rib compression, occasionally are associated with generalized arteriosclerotic peripheral vascular disease, and rarely are secondary to syphilitic or mycotic infections. Subclavian artery aneurysms have a major risk of rupture, embolus, or thrombosis, and therefore should be repaired. A reverse saphenous vein or prosthetic bypass graft from the carotid to the axillary artery provides adequate flow to the upper extremity. The aneurysm should be completely excised if possible, since reexpansion through small collaterals or through insufficient closure by ligation can occur and compress the brachial plexus after successful bypass. The clinical presentation, angiographic findings, and operative repair of a subclavian artery aneurysm secondary to cystic medial necrosis are described.