Secretion in yeast of human lysozymes with different specific activities created by replacing valine-110 with proline by site-directed mutagenesis.

Computer graphics indicate that a steric hindrance exists between valine-110 side chain of human lysozyme (EC 3.2.1.17) and an acetyl group of a modified substrate that contains N6,O-diacetylmuramic acid. To alter the substrate specificity of human lysozyme to be effective on the modified substrate, we replaced the valine-110 residue with various amino acids by site-directed mutagenesis. One of the mutant proteins (valine residue replaced with proline:P110) was secreted in Saccharomyces cerevisiae as at least four components (P110-A, P110-B, P110-C, and P110-D) with different specific activities. Two components, P110-B and P110-D, were isolated in a pure form and structurally characterized. The results suggest that this mutation lowered the lytic activity against Micrococcus lysodeikticus by changing a local conformation of the catalytic site while keeping almost the same substrate binding sites. Our results also indicate that cis/trans isomerization of prolyl peptide bonds probably occurs in vivo and that the conformational change of protein as well as point mutations in genes might influence the molecular evolution of the protein.     

Enhanced clearance of lactic dehydrogenase-5 in severe combined immunodeficiency (SCID) mice: effect of lactic dehydrogenase virus on enzyme clearance.

The lactic dehydrogenase (LDH) level in plasma and the clearance of LDH in C.B-17 scid (severe combined immunodeficiency; SCID) mice were compared with those in C.B-17 or BALB/cCrSlc mice with or without lactic dehydrogenase virus (LDV) infection. The resting enzyme level in SCID mice showed little difference from that in C.B-17 or BALB/cCrSlc mice. The degree of increased plasma LDH level in SCID mice was lower than that in C.B-17 and BALB/cCrSlc mice after LDV infection. To assess the mechanisms of decrease in LDH elevation in SCID mice infected with LDV, virus replication was compared in SCID and BALB/cCrSlc mice. The infectivity titre of plasma in SCID mice was higher (more than 10 times) than that in BALB/cCrSlc mice. Moreover, the percentage of virus antigen positive Kupffer cells was higher in SCID mice than that in BALB/cCrSlc mice. The level of endogenous LDH release as a result of carbon tetrachloride treatment was similar in the SCID and BALB/cCrSlc mice. The clearance rate of endogenous LDH was greater in SCID mice than in BALB/cCrSlc mice with or without LDV infection. The rate of clearance of intravenously injected porcine LDH-5, but not porcine LDH-1, was enhanced in SCID mice as compared with that in BALB/cCrSlc mice. Furthermore, carbon clearance was higher in SCID mice than that in BALB/cCrSlc mice. These results suggest that the smaller increase of plasma LDH after infection might be due, at least in part, to the enhanced LDH-5 clearance function by macrophages in SCID mice.     

Acute myocardial infarction: comparison of results of Tl-201, Tc-99m pyrophosphate and In-111 antimyosin Fab imagings]

To evaluate the extent and characteristics of infarct areas, we performed indium-111 monoclonal antimyosin Fab (InAM), thallium-201 (TL) and Tc-99m pyrophosphate (PYP) imagings in 17 patients with acute myocardial infarction, and tried to find out the mechanism that causes difference of these imagings. In each study, the extent scores as an index of the infarct area were obtained by single photon emission computed tomography (SPECT), and comparisons were made between the results obtained. The overlap between InAM and TL imagings obtained by SPECT was evaluated. Location, severity, extent and patterns of accumulation were compared between InAM and PYP with both planar image and SPECT. The extent scores of InAM correlated well with those of TL (r = 0.73, p < 0.01). However, the overlap of both methods was recognized in 8 of 17 patients, in whom wall thickness of the infarct area as obtained by echocardiography was well preserved. The left ventricular regional asynergy was mild in 6 of these 8 patients. Coronary angiography showed poor or no collateral circulation in these cases. Although there were generally close correlations of the extent scores between InAM and PYP, discrepancy was noted in 2 cases for location; 2 for severity, 5 for extent, and 3 for patterns of accumulation. These differences may be attributed to the timings of imaging, coronary reperfusion and different mechanisms of accumulation. In conclusion, the extent of acute myocardial infarction obtained by InAM correlates well with those obtained by TL and PYP, with some exceptions.     

Nodular fasciitis of the upper labial fascia: cytometric and ultrastructural studies

The rare case of nodular fasciitis in the upper labial fascia is reported. Light microscopic, electron microscopic and cytometric studies were performed. The histopathology corresponded to intermediate and reactive types in the Price and Bernstein classification. Cytometric study of evaluating DNA of fibroblasts revealed a high distinct peak in myxoid and inflammatory areas. Ultrastructurally, fibroblasts and myofibroblasts were identified in the lesion. Reported Japanese cases of orofacial nodular fasciitis are reviewed and compared with the European-American literature.     

Clinical experience with PTFE graft replacement in the descending thoracic aorta

In 6 cases, we have performed polytetrafluoroethylene (PTFE) graft replacement in the descending thoracic aorta, with all patients alive and showing good results. Fifty months have passed since the first graft replacement, but no complications due to the PTFE graft have occurred.     

Three-dimensional architecture of elastic tissue in athero-arteriosclerotic lesions of the rat aorta

The overall three-dimensional architecture of elastic tissue in athero-arteriosclerotic lesions of the ascending aorta of the rat was studied, using scanning electron microscopy (SEM), after hot-formic acid extraction followed by a freeze-drying method. The lesions were induced by feeding the rats a diet containing 2% cholesterol for 6 weeks and administering massive doses of vitamin D2 for the first 4 days. SEM revealed the synthesis of elastins mainly in the intima and the degradation in the internal elastic lamina (IEL) and medial concentric elastic lamellae. Intimal elastic elements involved in atherosclerotic lesions were composed of an intricately tangled network of fibrous elastins or a row of elastic laminae that surrounded many rectangular compartments, which were separated by fenestrated septum-like elastins and were assumed to be the sites of smooth-muscle-cell proliferation. These observations indicated remodelling of the elastic laminae in the intima. Degradation in the IEL and media was attributed to either vitamin D2 intoxication, which was characterized by the formation of a large degraded portion, or an enhanced elastolytic process. These alterations of elastic elements probably reflect the exact frame of the modes of migration of aortic smooth muscle cells in the development of athero-arteriosclerotic lesions, thereby indicating the role of smooth muscle cells in the progress of atherosclerosis.     

Correlations between bone mineral density and demographic, lifestyle, and biochemical variables in community-dwelling Japanese women 69 years of age and over

Introduction A few epidemiologic studies have comprehensively attempted to identify risk factors for low bone mineral density (BMD) in elderly Asian women. The purpose of this study was to identify demographic, lifestyle, and biochemical factors correlated with BMD in elderly Japanese women 69 years of age and over.Methods The study design was cross-sectional. The subjects were 583 ambulatory women aged 69 years and over, and their average age was 74.3 (SD 4.4) years. Predictor variables were age, reproductive history, anthropometric indices, grip strength, calcium intake, lifestyle information, and serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D (1,25(OH)₂D), osteocalcin (OC), and undercarboxylated osteocalcin (ucOC) values. The outcome variable was forearm BMD measured with a DTX-200 osteometer.Results Simple linear regression analyses showed that BMD was significantly positively associated with body height, weight, body mass index, grip strength, serum albumin concentration, and “housework,” and negatively associated with age, years since menopause, age at menarche, number of children, serum 1,25(OH)₂D concentration, serum OC concentration, and ucOC concentration. The stepwise multiple regression analysis showed that weight (β=0.00316, SE=0.00028, R²=0.180), age (β=−0.00321, SE=0.00050, R²=0.108), log-transformed serum OC (β=−0.0445, SE=0.0064, R²=0.053), log-transformed serum 1,25(OH)₂D (β=−0.0401, SE=0.0074, R²=0.050), “farmwork” (β=0.00904, SE=0.00426, R²=0.005), and serum 25(OH)D concentration (β=0.000281, SE=0.000120, R²=0.003) were significantly associated with BMD.Conclusion It was concluded that body weight is a major predictor of forearm BMD among the factors measured in this study in independent Japanese women 69 years of age and over and that serum 1,25(OH)₂D concentration may be associated with cortical BMD. Maintenance of body weight is very important for maintaining BMD in this population, unless a large weight aggravates obesity-related diseases. A follow-up study is needed to confirm these findings.     

Disc and condyle translation in patients with temporomandibular disorder.

OBJECTIVE: The purpose of this study was to elucidate causal relationship between disc and condyle range of movement and clinical signs and symptoms in patients with temporomandibular disorders (TMD), using magnetic resonance imaging (MRI). STUDY DESIGN: The subjects comprised of a study group of 191 patients with TMD and a control group of 43 asymptomatic patients. The clinical assessment consisted of range of maximum mouth opening (MMO) and preauricular pain during mandibular function. After clinical and radiographic findings assessment, disc and condyle condition were examined by MRI and the range of movement was accordingly classified. RESULTS: Disc displacement was observed in 156/191 (81.7%) of the study group and 9/43 (20.9%) of the control group. When disc and condyle mobility was presented around the eminence, wider MMO range was maintained, P < .05. Presence of osteoarthrosis (OA) was not correlated with preauricular pain, because OA variables were mild in the study group. CONCLUSION: Maintenance of disc/condyle translation is an important factor in TMJ function, irrespective of disc displacement or arthritis.