[Preparation of beta-1,3-glucan synthase and its application to the screening of antifungal antibiotics]

beta-1,3-glucan synthase was obtained as a particulate fraction from cell-free extracts prepared after mechanical breakage cells of Candida albicans. Some properties of the glucan synthase were investigated. Using it as a target for screening for novel antifungal compounds, we obtained strains whose products showed differential enzyme inhibition.

Differential expression of ob mRNA in rat adipose tissues in response to insulin

The recently cloned obese (ob) gene encodes a fat-specific mRNA and a protein which is believed to regulate satiety and metabolic rate so as to control fat storage. In the present study we investigated rat ob mRNA levels in different fat depots and the effects of insulin infusion on ob mRNA expression. Northern blot analysis showed the abdominal fat (epididymal and perirenal fat pads) had higher ob mRNA levels than subcutaneous fat. After a 2.5-hr infusion of insulin into fasted rats, ob mRNA levels were increased by 3.0 and 1.9-fold in epididymal and perirenal fat pads, respectively. However, no change of ob mRNA level was observed in the subcutaneous fat depot. These data demonstrate adipose depot site-specific expression of ob mRNA and support the hypothesis that insulin plays an important role in the expression of ob mRNA.

[The mRNA expression of CD2, CD4 and CD8 in peripheral blood lymphocytes from the patients with acute lymphoblastic leukemia and non-Hodgkin's lymphoma]

The paper for the first time reports the detection of the levels of CD2, CD4 and CD8 mRNA expression in peripheral blood lymphocytes from 9 cases with T-acute lymphoblastic leukemia (ALL) and 10 cases with T-non-Hodgkin's lymphoma (NHL) by using RNA dot blotting technique. It was found that the levels of CD2 mRNA in the two groups of patients were significantly higher than those in the normals. The ratios of the CD4 to CD8 mRNA were also increased in patients with NHL. The significance of this study was discussed.

[Clinical and angiographic characteristics of renovascular hypertension]

Clinical and angiographic characteristics of renovascular hypertension were studied in 95 patients. The patients were divided into 3 groups: 55 cases with aortic arteritis (group AA), 27 with fibromuscular dysplasia (group FMD) and 9 with atherosclerosis (group AS). The patients in group AS were significantly older in age and had longer history of hypertension. Abdominal bruit was heard significantly more often in group AA and serum potassium was significantly lower in group FMD. Angiographic data showed that in group AA lesions in thoracic aorta and abdominal aorta was found in 81.4% and those involving both renal arteries in 52.5%. In group FMD, 82.5% of patients had lesion in renal artery on one side and none had lesion in thoracic and abdominal aorta. In group AS, lesions were found mainly in thoracic and abdominal aorta, accounting for 77.7% and lesions in renal arteries were mainly unilateral. In group AA, lesions were found in 90 renal arteries altogether. Among them, 58.9% was in the proximal part of the renal artery; the lesion was either localized stenosis (67.8%) or obstruction (17.7%). In group FMD, lesions were found in 33 renal arteries altogether. Among them, 48.5% was in the middle or distal part of the renal artery and 27.3% resembled string of beads. In group AS, a total of 10 renal arteries were involved with 4 (40%) of ostial stenosis and 4 (40%) total obstruction.

Characterization of microbial communities in anaerobic bioreactors using molecular probes

The microbial community structure of twenty-one single-phase and one two-phase full-scale anaerobic sewage sludge digesters was evaluated using oligonucleotide probes complementary to conserved tracts of the 16S rRNAs of phylogenetically defined groups of methanogens and sulfate-reducing bacteria. These probe results were interpreted in combination with results from traditional chemical analyses and metabolic activity assays. It was determined that methanogens in "healthy" mesophilic, single-phase sewage sludge digesters accounted for approximately 8-12% of the total community and that Methanosarcinales and Methanomicrobiales constituted the majority of the total methanogen population. Methanobacteriales and Methanococcales played a relatively minor role in the digesters. Phylogenetic groups of mesophilic, Gram-negative sulfate-reducing bacteria were consistently present at significant levels: Desulfovibrio and Desulfobulbus spp. were the dominant sulfate-reducing populations, Desulfobacter and Desulfobacterium spp. were present at lower levels, and Desulfosarcina, Desulfococcus, and Desulfobotulus spp. were absent. Sulfate reduction by one or more of these populations played a significant role in all digesters evaluated in this study. In addition, sulfate-reducing bacteria played a role in favoring methanogenesis by providing their substrates. The analysis of the two-phase digester indicated that true phase separation was not accomplished: significant levels of active methanogens were present in the first phase. It was determined that the dominant populations in the second phase were different from those in the single-phase digesters.

The influence of aging on muscle strength and muscle fiber characteristics with special reference to eccentric strength

It is well established that aging seriously reduces isometric and concentric muscle strength due to atrophy, deterioration of mechanical properties, and motor unit loss. However, there is limited information on the impact of aging on eccentric strength despite the fact that such forces play an equally important role during daily activities. The purpose of this study was to examine the influence of aging on three expressions of muscle strength (isometric, concentric, and eccentric) in relation to muscle fiber characteristics, with special emphasis on eccentric force. Sedentary but healthy men (age range 18-80 years, n = 60) and women (20-74 years, n = 30) were tested for maximal effort isometric, concentric, and eccentric (1.05, 2.09, 3.14 rads.s-1) quadriceps strength, body composition, and muscle fiber characteristics of the vastus lateralis (men only). There was a significant (p < .05) approximately 30 N per decade decline in isometric and concentric forces, but only 9 N per decade reduction in eccentric strength. There was a significant reduction in Type II muscle fiber area with aging (p < .05). Isometric, eccentric, and concentric force correlated r = .33, r = .32 (p < .05), and r = .12 (p > .05) with Type II muscle fiber area, respectively. The correlation between age and fat-free mass/force ratio ranged from r = .39 to .43 in men and r = .27 to .50 in women. The data suggest a relative preservation of eccentric strength with aging in men and women that seems to be independent of muscle mass or muscle fiber type or size.

Impairment of synaptic vesicle clustering and of synaptic transmission, and increased seizure propensity, in synapsin I-deficient mice

Synapsin I has been proposed to be involved in the modulation of neurotransmitter release by controlling the availability of synaptic vesicles for exocytosis. To further understand the role of synapsin I in the function of adult nerve terminals, we studied synapsin I-deficient mice generated by homologous recombination. The organization of synaptic vesicles at presynaptic terminals of synapsin I-deficient mice was markedly altered: densely packed vesicles were only present in a narrow rim at active zones, whereas the majority of vesicles were dispersed throughout the terminal area. This was in contrast to the organized vesicle clusters present in terminals of wild-type animals. Release of glutamate from nerve endings, induced by K+,4-aminopyridine, or a Ca2+ ionophore, was markedly decreased in synapsin I mutant mice. The recovery of synaptic transmission after depletion of neurotransmitter by high-frequency stimulation was greatly delayed. Finally, synapsin I-deficient mice exhibited a strikingly increased response to electrical stimulation, as measured by electrographic and behavioral seizures. These results provide strong support for the hypothesis that synapsin I plays a key role in the regulation of nerve terminal function in mature synapses.

The insulin action-fiber type relationship in humans is muscle group specific

The purpose of the present investigation was to determine the relationship between skeletal muscle characteristics, adiposity, and in vivo insulin action. Percutaneous muscle biopsies of the vastus lateralis (VL) and gastrocnemius (G) muscles were obtained from twenty-two sedentary male subjects. Insulin sensitivity (SI) and glucose effectiveness (SG) were determined from minimal model analysis, and indexes of regional and overall adiposity were obtained. SI was positively related to the citrate synthase activity from the VL (r = 0.50, P < 0.01) but unrelated to the citrate synthase activity from the G (r = 0.28). Similarly, SI was inversely related to the percentage of type IIb fibers in the VL (r = -0.47, P < 0.01) but unrelated to the percentage of type IIb fibers in the G (r = 0.06). SG was unrelated to fiber type, oxidative capacity, or adiposity. These data suggest that oxidative capacity and other characteristics related to VL skeletal muscle fiber type are determinants of in vivo insulin action but that this relationship cannot be extended to all muscle groups. Finally, neither skeletal muscle characteristics nor adiposity appears to be a determinant of SG in sedentary males.

[Reason and management of posterior capsular breaks during cataract extraction and lens implantation]

PURPOSE

To study the reason and management of posterior capsular bresks during cataract extraction and lens implantation.

METHODS

The authors analyse the reasons of posterior capsular brseaks during cataract extraction and lens implantation on 55 eyes and discuss the management according to the different situations.

RESULTS

The posterior capsular disruption occurred most frequently during cortical cleanup on 21 eyes (38.2%) and lens implantation on 21 eyes (38.2%). The diameter of the tears was about 3 mm on 39 eyes (70.9%), about 5 mm on 13 eyes (23.6%) and larger than 6 mm on 3 eyes (5.5%). The tears with central defined borders were on 12 eyes (21.8%), with peripheral defined border in one side on 39 eyes (71%), with pooly defined borders on 3 eyes (5.5%). Final visual acuity of 0.5 or better was achieved on 35 eyes (63.6%).

CONCLUSIONS

When the complication occurs during the operation, we should use the suitable management according to the different situations in order to reduce the loss of the complication.

Skeletal muscle GLUT4 protein concentration and aging in humans

The insulin resistance of aging has been attributed to a postreceptor defect in skeletal muscle. The present study examined whether a reduction in the concentration of the insulin-stimulated glucose transporter (GLUT4) in skeletal muscle was associated with advancing age in men (n = 55) and women (n = 29). Insulin sensitivity (minimal model) was negatively associated (P < 0.001) with age (range, 18-80 years) in men (r = -0.44) and women (r = -0.58). GLUT4 protein concentration in the vastus lateralis was also negatively associated (P < 0.05) with age (men, r = -0.28; women, r = -0.51). There was no relation (P > 0.15) between GLUT4 content in the gastrocnemius and age. GLUT4 concentration in the vastus lateralis was positively associated (P < 0.01) with insulin sensitivity in both sexes (r = 0.42); this relationship persisted in the men after adjusting for overall adiposity, regional adiposity, and cardiorespiratory fitness. These findings suggest that a decrement in GLUT4 protein concentration in skeletal muscle may at least partially contribute to the insulin resistance of aging in humans.

[Isolation, purification and characterization of human proteinase inhibitor, alpha 2-macroglobulin]

A study of the isolation, purification and characterization of human proteinase inhibitor, alpha 2-macroglobulin (alpha 2-M) is presented. The alpha 2-M, with a purity of more than 90% and subunit molecular weight of 185kDa, was isolated by ammonium sulfate fractionated precipitation from human blood plasma and purified by DEAE cellulose DE52 column chromatography. It was found to be the same as the standard counterpart provided by sigma company. This purification procedure of alpha 2-M can be done with low cost, high efficiency and in large scale preparation.

Effects of increased neural activity on brain growth

We have measured the effects of regionally increased metabolic activity--and by inference electrical activity--on cortical growth in the developing rat brain. Cortical growth is significantly and specifically greater in regions of chronically increased activity. This effect of activity on cortical growth may help explain the permanent storage of early experience in the developing nervous system.

Isolation and characterization of an in vitro DNA replication system from maize mitochondria

An in vitro DNA replication system from maize mitochondria has been isolated and characterized. Maize mtDNA polymerase activity was purified about 1100-fold through DEAE cellulose and Heparin-Sepharose columns. In addition to the DNA polymerase activity, this in vitro replication system also contained topoisomerase I, DNA primase and RNA polymerase activities. Optimal conditions for enzyme activity, preferred templates and inhibitors were determined in order to further characterize this in vitro replication system; this system was devoid of any detectable extramitochondrial activity as determined by: a) the mt origin of the DNA polymerase activity as evidenced by studies using different templates and inhibitors, b) absence of chloroplast or nuclear DNA, glucose -6-P-dehydrogenase (known to be present only in the cytosol and chloroplasts) and photosynthetic pigments in the mitochondrial fraction and c) the ability of maize mt topoisomerase I to relax positively supercoiled DNA.

Over-expression of CD3 epsilon transgenes blocks T lymphocyte development

We have reported previously that mice carrying > 30 copies of the human CD3 epsilon transgene completely lose their T lymphocytes and NK cells (36). Here we demonstrate by immunohistology that in the most severely immunodeficient mouse, tg epsilon 26, the thymus is very small, has sizeable vacuoles and does not contain recognizable T lymphocytes except for a small percentage of Thy-1+ cells and B cells. Cell surface phenotyping and TCR alpha and -beta rearrangement studies confirm that the arrest in T lymphocyte development precedes the arrest in rag-1null, rag-2null and TCR beta nuli mice. Since the T cell progenitors in which the arrest occurred were absent in the transgenic mice, indirect approaches were taken to examine the causes of the block in T cell development. Analyses of 12 independently established mutant mouse lines, generated with five different transgenic constructs, revealed that the severity of the abrogation in T cell development was dependent on the number of copies of transgenes. Since the number of transgene copies generally correlated with the levels of expression of the transgenic CD3 epsilon proteins, we concluded that over-expression of the CD3 epsilon protein was the likely cause of the block in T lymphocyte development. The T cell immunodeficiency was caused by either the human or the murine CD3 epsilon protein. Since transgene coded mRNAs were found in significantly higher quantities than endogenous CD3 epsilon mRNAs in fetal thymi on days 13 and 14 of gestation, over-expression took place very early in development, probably prematurely. Over-expression of the CD3 epsilon transgene in thymocyte precursors may therefore affect T lymphocyte development in the absence of TCR and possibly in the absence of the other CD3 proteins. More importantly, over-expression of the CD3 epsilon protein in thymocytes of mice with a low copy number of transgenes had a significant effect on late thymic development. Over-expression of the CD3 epsilon protein in immature thymocytes mimicked the effects caused by exposure of CD4- CD8- thymocytes to anti-CD3 epsilon treatment: apoptosis and lack of TCR beta expression. We therefore speculate that in the homozygous tg epsilon 26 animals the arrest in T cell development was caused by excessive signal transduction events rather than by a toxic effect of the transgenic protein.

Differential metabolic and electrical activity in the somatic sensory cortex of juvenile and adult rats

We have examined relative levels of metabolic and electrical activity across layer IV in the primary somatic sensory cortex (S1) of the rat in relation to regions of differential postnatal cortical growth. Each of several indices used--mitochondrial enzyme histochemistry, microvessel density, Na+/K+ pump activity, action potential frequency, and deoxyglucose uptake--indicate regional variations of metabolic and electrical activity in this part of the brain in both juvenile (1-week-old) and adult (10-12-week-old) animals. At both ages, areas of the somatic sensory map related to special sensors such as whiskers and digital pads showed evidence of the most intense activity. Thus, mitochondrial enzyme staining, blood vessel density, and Na+/K+ ATPase activity were all greatest in the barrels and barrel-like structures within S1, and least in the adjacent interbarrel cortex and the cortex surrounding S1. Multiunit recordings in and around the posteromedial barrel subfield of anesthetized animals also showed that the average ratio of evoked to spontaneous activity was greater in barrels than in the surrounding, metabolically less active cortex. Furthermore, autoradiograms of labeled deoxyglucose accumulation in awake behaving animals indicated systematic differences in neural activity across S1 barrels and barrel-like structures showed more deoxyglucose accumulation than interbarrel, nonbarrel, or peri-S1 cortex. These regional differences in neural activity correspond to regional differences in neocortical growth (Riddle et al., 1992). The correlation of greater electrical activity, increased metabolism, and enhanced cortical growth during postnatal maturation suggests that neural activity foments the elaboration of circuitry in the developing brain.

ATP induces large quaternary rearrangements in a cage-like chaperonin structure

BACKGROUND

The chaperonins, a family of molecular chaperones, are large oligomeric proteins that bind nonnative intermediates of protein folding. They couple the release and correct folding of their ligands to the binding and hydrolysis of ATP. Chaperonin 60 (cpn60) is a decatetramer (14-mer) of 60 kD subunits. Folding of some ligands also requires the cooperation of cpn10, a heptamer of 10 kD subunits.

RESULTS

We have determined the three-dimensional arrangements of subunits in Rhodobacter sphaeroides cpn60 in the nucleotide-free and ATP-bound forms. Negative stain electron microscopy and tilt reconstruction show the cylindrical structure of the decatetramer comprising two rings of seven subunits. The decatetramer consists of two cages joined base-to-base without a continuous central channel. These cages appear to contain bound polypeptide with an asymmetric distribution between the two rings. The two major domains of each subunit are connected on the exterior of the cylinder by a narrower bridge of density that could be a hinge region. Binding of ATP to cpn60 causes a major rearrangement of the protein density, which is reversed upon the hydrolysis of the ATP. Cpn10 binds to only one end of the cpn60 structure and is visible as an additional layer of density forming a cap on one end of the cpn60 cylinder.

CONCLUSIONS

The observed rearrangement is consistent with an inward 5-10 degrees rotation of subunits, pivoting about the subunit contacts between the two heptamers, and thus bringing cpn60 domains towards the position occupied by the bound polypeptide. This change could explain the stimulation of ATPase activity by ligands, and the effects of ATP on lowering the affinity of cpn60 for ligands and on triggering the release of folding polypeptides.

[A study of accuracy of multiple-unit one-piece castings of fixed bridge]

We studied how the accuracy of the three-unit and four-unit bridges is affected by the three different sprue programmes and heat-treatment. The results of experiments are as follows. 1. In the two types of fixed bridge the accuracy of the lateral pouring sprue programme is greater than that of the top-pouring and bottom-pouring sprue programmes. 2. After the heat-treatment of the casting, the stresses are distributed again, so the accuracy of the casting becomes lesser. 3. The change in the measurement of the total and pontic lengths of multiple-unit fixed bridges generally causes a "fork shape" deformity.

Subchronic toxicity studies of fenbendazole in rats

The effects of prolonged exposure of rats to fenbendazole were investigated. Fenbendazole was given daily by gavage for 14 consecutive days. These dosages (3000, 500 or 50 mg/kg/d) produced reductions in body weight gains. Renal tubular hyperemia or hemorrhage and glomerular capsule dilation, increased serum creatinine and hepatocellular granular degeneration occurred at dosages of 500 and 3000 mg/kg/d. Renal tubular epithelial cell granular degeneration and tubular dilation, increased serum glutamic pyruvic transaminase, cardiac hemorrhage and granular degeneration also occurred at 3000 mg/kg/d.

[Effects of zinc deficiency and vitamin D deficiency on bone calcification and development of rats]

Zinc deficiency rat model was made by feeding zinc deficiency diet. The level of bone calcium of the zinc deficiency rats was significantly lower than that of the control rats. Their bone cortex was thinner and bone density decreased. The counts of their cartilage cells and hypertrophic cells of epiphyseal plate were less frequent, and the diameter of their hypertrophic cells was smaller than that of the controls. It suggested that zinc deficiency caused defective bone calcification which was similar to that in vitamin D deficiency. Zinc deficiency seemed to hinder the linear growth of long bone and might be the cause of dwarf.

T-complex polypeptide-1 is a subunit of a heteromeric particle in the eukaryotic cytosol

The murine t-complex encodes t-complex polypeptide-1 (TCP1), which is constitutively expressed in almost all cells, and upregulated during spermatogenesis. Mammalian sequences have greater than 96% identity with each other, and greater than 60% identity with Drosophila melanogaster and yeast orthologues. TCP1 is essential in yeast, and is postulated to be the cytosolic mammalian equivalent of groEL. We report here that, in the native state, murine and human TCP1 is distributed throughout the cytosol as an 800K-950K hetero-oligomeric particle in association with four to six unidentified proteins and two Hsp70 heat-shock proteins. Negative-stain electron microscopy indicates that the structure is two stacked rings, 12-16 nm in diameter. Therefore, despite similarities with the chaperonin 60 proteins, these data indicate that TCP1 is biochemically and structurally unique. We suggest that TCP1 may represent one of a family of molecules in the eukaryotic cytosol involved in protein folding and regulated in part by their heteromeric associations.

Cardiovascular mechanisms of thyrotropin-releasing hormone against experimental hemorrhagic shock

Thyrotropin-releasing hormone (TRH) improved mean arterial pressure (MAP) and myocardial contractility (dp/dtmax, -dp/dtmax, Vpm, and Vmax) and increased plasma epinephrine levels significantly at 10 min after TRH treatment in rabbits following shock, but the effects of TRH on MAP and myocardial contractility disappeared in reserpinized rabbits (4 mg/kg, 24 hr pre-treatment, iv). TRH had no effect on myocardial contractility and MAP at 20 and 30 min post-treatment in rabbits pre-treated with the beta adrenergic blocker propranolol (1 mg/kg, 1 hr before TRH treatment, iv), but the alpha adrenergic blocker phenoxybenzamine did not affect these responses to TRH. Experiments in vitro show that although TRH (10(-3) to 10(-8) M) had no direct effects on the isolated heart, left atrium, and aortic strip, it did potentiate the inotropic effects of isoprenaline and dopamine on the left atrium. These results suggest that the antishock effects of TRH are related to adrenergic systems, perhaps acting on the sympathomedullary system to secrete epinephrine and sensitize the beta receptors, but not alpha receptors. Thus, TRH improves cardiac contractility, cardiac output, and hemodynamics during hemorrhagic shock. The sensitization of the beta adrenergic and dopamine receptors may play an important role in the direct peripheral cardiovascular mechanism of TRH effects.