Technical hitches in rat MHC class I gene mapping. Response. A genetic version of "The Voyage of Ulysses".
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Animals↗
Biomedical subjects
X Yuan
Publications and source records attributed to X Yuan.
Error propagation for relative motion determined from marker positions.
In this paper, the error propagation for relative motion reconstructed from noisy marker position data was investigated, particularly the influence of the distance between two rigid bodies was explored. Based on a mathematical derivation, an error propagation model for relative motion was proposed and computer simulations were used to validate the proposed model. The results indicated that the error in the translation components for relative motion between two rigid bodies are proportional to the distance between the rigid bodies. The maximum absolute difference between the model and the simulation is 0.58% which strongly validated the accuracy of the error propagation model.
Computer Simulation↗
Beta 3-adrenergic receptor gene polymorphism is not a major genetic determinant of obesity and diabetes in Japanese general population.
To assess the contribution of a replacement of Trp at codon 64 of beta 3-adrenergic receptor by Arg to fat distribution and metabolic disturbances in Japanese general population, we examined the missense mutation in 1122 persons consisting of 817 men aged 50.0 +/- 8.9 years and 305 women aged 50.8 +/- 8.5 years in Kyushu, Japan. The incidence of Arg64 allele was 0.21; no age-dependent decrease of the allele frequency was observed, suggesting that the mutation was not associated with early mortality. The genotype was not significantly correlated with body mass index or the thickness of visceral fat estimated by ultrasonography. Glucose tolerance and glucose-induced insulin secretion were not significantly different among subjects with Trp/Trp, Trp/Arg and Arg/Arg at codon 64. Although in obese persons the ratio of heterozygotes for the mutation tended to be higher in subjects with impaired glucose tolerance than in subjects with normal glucose tolerance, the tendency was not observed in non-obese persons. Furthermore none of 39 non-obese individuals homozygous for the mutation was diabetic, whereas two out of six obese homozygous persons were diabetic. These observations suggest that the missense mutation may not be a main determinant of obesity in populations taking low fat/low energy Japanese-style diet and it may not be deleterious at least in non-obese individuals.
Adipose Tissue↗
Combined measurements of GAD65 and ICA512 antibodies in acute onset and slowly progressive IDDM.
Autoantibodies to 65 kD glutamic acid decarboxylase (GADAA) and ICA512 (ICA512AA) were measured by radioimmunoassays using as antigens in vitro transcribed and translated [35S]-methionine-labeled human GAD65 and ICA512 (IA-2). The prevalence of GADAA and ICA512AA in sera from 87 patients with IDDM was 39 and 23%, respectively. The frequency and titer of ICA512AA declined sharply within 5 years after the onset of IDDM. Among patients tested within 4 years after diagnosis, the prevalence of ICA512AA was significantly higher in acute onset IDDM than in slowly progressive IDDM (37 versus 6%, P < 0.025) irrespective of age, while there was no difference in GADAA frequency between acute onset and slowly progressive subtypes (51 versus 63%). A total of two patients out of 121 patients with NIDDM were positive for GADAA, and two other NIDDM patients, who were suffering from sarcoidosis, were positive for ICA512AA. Neither of the antibodies were positive in sera from four atypical NIDDM patients, aged < 20 years, who showed ketosis at onset and required insulin followed by excellent metabolic control with diet restriction alone. These observations suggest that ICA512AA are associated with rapid progression of beta cell damage in IDDM. ICA512 radioassay, in combination with GAD assay may provide a useful diagnostic marker for IDDM especially in youth.
Adolescent↗
Clinical characteristics of Japanese men with glucokinase gene beta-cell promoter variant.
OBJECTIVE: To study the association between a variant at the position of -30 of beta-cell-specific promoter of the glucokinase gene and glucose tolerance in the Japanese general population and to assess the clinical characteristics of subjects with the variant. RESEARCH DESIGN AND METHODS: The genotype of 657 Japanese men aged 51.0 +/- 8.8 years (mean +/- SD) was analyzed by an allele-specific assay using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: The variant allele frequency was 0.188 in subjects with normal glucose tolerance, 0.211 in subjects with impaired glucose tolerance, and 0.176 in diabetic subjects. In subjects with fasting plasma glucose levels <140 mg/dl, homozygous subjects for the promoter variant had significantly higher plasma glucose levels 60 min after oral glucose administration when compared with subjects without the variant allele. A cross-sectional analysis showed age-related elevation of basal glucose levels only in subjects without the promoter variant. Individuals heterozygous for the variant had significantly lower levels of HDL cholesterol than normal subjects. HDL cholesterol values were lower in homozygous people than in normal and heterozygous subjects, although the differences were not statistically significant. CONCLUSIONS: The beta-cell promoter variant in homozygous state was associated with impaired glucose tolerance, but not with diabetes, and low HDL cholesterol levels in Japanese men. It is unlikely that the glucose intolerance associated with the promoter variant is progressive with age.
Adult↗
Concentrations of selected vitamins and selenium in bison cuts.
We analyzed individual cuts from clod (Triceps brachii), ribeye (Longissimus thoracis), top round (semimembranosus), and top sirloin (Gluteus medius) from 12 fed bison bulls for content of selected vitamins and selenium. The bulls came from producers in the United States and Canada and had consumed concentrate diets plus hay free choice for at least 180 d. The mean nutrient concentrations of all of the bison cuts combined were as follows (per 100 grams of wet weight): .045 mg thiamin, .253 mg vitamin B6, 2.131 microg vitamin B12, no detectable vitamin C, .848 microg vitamin A, .047 mg alpha-tocopherol, .013 mg tau-tocopherol, and 25.464 microg selenium. The nutrient content values did not differ (P > .05) among the cuts of meat. Cuts from individual bulls were different (P < .05) with regard to alpha- and tau-tocopherols, selenium, and vitamin A but not with regard to thiamin, vitamin B6, and vitamin B12. Nutrient concentrations, with the exception of one nutrient, of five bison from the same producer were similar. Great variation was observed between the alpha- and tau-tocopherols, selenium, and vitamin A contents among bison bulls but not among cuts of meat.
Analysis of Variance↗
Effects of lamination on the strength of bone cement.
To improve cement penetration into the cancellous bone of the acetabulum in hip arthroplasty, sequential cementation of each anchoring hole may be feasible. Since this procedure creates laminations in the cement, we have determined the conditions under which such laminations affect the strength of the cement. Cement bars made at 2, 3 or 4 minutes after the start of cement mixing and with either dry laminations or laminations including blood or saline were tested for tensile strength. Solid unlaminated bars were used as references. Dry and saline laminations made up to 4 minutes after the start of cement mixing did not reduce the strength of the cement. However, there was a time-dependent decrease in cement strength if blood was entrapped in the interface. In such cases, there was a decrease in strength for laminations made at 4 minutes, at 3 minutes this was less pronounced and at 2 minutes no weakening at all was noted. Our findings indicate that a sequential cementation procedure is permissible as regards cement strength, provided it is performed with 2-3 minutes after the start of cement mixing. If the cement area is kept free from blood, the time may be prolonged up to 4 minutes, without the risk of weakening the cement strength.
Biomechanical Phenomena↗
[Effects of cold exposure on some endocrine activities in rats].
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Animals↗
[Immunobiological significance of S-100 protein positive dendritic cells (S-100+DC) in patients with oral squamous cell carcinoma].
The purpose of this study is to investigate the role and clinical significance of S-100+DC in oral squamous cell carcinoma. Distribution of S-100+DC in the tumor tissues and regional lymph nodes (LN) of 60 patients with oral squamous cell carcinoma was detected by immunohistochemistry (ABC). The results showed that the S-100+DC density in tumor tissues was correlated with the tumor histologic grade (P < 0.05). The density of S-100+DC was significantly higher in regional LN without tumor than those with metastases (P < 0.05). However, there was no difference of S-100+DC in tumor tissues between patients with and without regional LN metastases. The distribution of S-100+DC in tumor tissues and regional LN could be considered as a reference indicator of tumor histologic grade and clinical prognosis of patients.
Adult↗
[A study on three dimensional modeling of human body in man-machine system simulation].
Modeling of the human body is a basic problem in human-machine system simulation. In this study a B-spline surface model of the human body was established. In the modeling, human body is split into several segments and each segment is a cubic B-spline surface. A blend surface was used to link two jointed segments. It is easy to simulate the motion of the human body by using the algorithm of axial deformation.
Computer Simulation↗
[Comparative study on three different methods in typing hepatitis C virus].
The sea from 120 anti-HCV-positive patients were detected by three different methods to type HCV. In method A, PCR product of 5'-NC region was cut by restriction endonuclease. In method B, PCR with HCV core region type-specific primers was used. In method C, EIA based on HCV genotype I, II (serotype 1) and genotype III, IV (serotype 2) synthetic peptides was used to detect type-specific antibodies. It was showed that HCV genotypes were successfully identified in 96(80%) patients both by method A and method B, with HCV-II 86(89.6%), HCV-III 8(8.3%), HCV-II/III coinfection 2(2.1%). The results of these two methods were completely agreeable. HCV type-specific antibodies were detected in 78(65%) cases by method C, with serotype 1 68(87.2%), serotype 2 6(7.7%), serotype 1 plus 2 positive 4(5.1%). The comparative estimation of 66 patients who were positive for all the three methods showed a remarkable concordance (64/66, 97.0%). Our study demonstrated that the results of different HCV-typing methods mentioned above were fairly consistent and reliable. The abvantages, disadvantages and practical applicable scope of these methods were discussed in the paper.
Genotype↗
[Determination of alkali-earth metal by microwave plasma torch atomic emission spectrometry].
Determination of alkali-earth metal by microwave plasma torch atomic emission spectrometry (MPT-AES) was investigated. Operating conditions the effects of some coexistent elements were examined. Detection limits for Be, Mg, Ca, Sr and Ba are 0.47, 1.4, 0.15, 0.20 and 2.6ng/mL, respectively. Method has been applied to analyse some actual samples with satisfactory results.
English Abstract↗
[Experimental and clinical study on the blood supply of the subdermal vascular network island flap].
A comparison study on the blood supply of the buttock subdermal vascular network island skin flap and the conventional buttock island flap was undertaken in pigs. The former was created by thinning the distal half of the conventional buttock island flap, preserving the subdermal vascular network. Evaluation was made by measurement of skin temperature, laser Doppler, fluorescence stain, ink perfusion, microangiography and transparent specimen technique. It was found that the blood supply of the subdermal vascular network island skin flap was much lower than that of the conventional island flap. The reason was thought to be the change in the blood supply after the conventional island flap was thinned. The subdermal vascular network island skin flap was composed of the axial pattern and the random pattern. Fifteen subdermal vascular network island skin flaps have been successfully transferred with vessel anastomosis in 15 patients. The average area of the thinned distal part was 49% of the flap, with the maximum of 60%.
Animals↗
[The intelligence test of the patients with chronic renal insufficiency].
Thirty patients with chronic renal insufficiency (CRF) and twenty-six normal subjects were tested with Wechsler Adult Intelligence Scal (WALS). The verbal intelligence quotients (VIQ), performance intelligence quotients (PIQ), and full intelligence quotients (FIQ) of the patients were lower than those of the normal group (P < 0.01). Among them the mild and moderate intelligence damages were accounted 13.33%. Further analysis indicates that uremic posionous materials damage on the cerebral function was dose dependant. But the disease course was independant with the intelligence damage (P > 0.05). The results suggest that the plasma concentrations of uremia poisonous materials (BuN, Scr, etc.) in CRF patients should be lowered as early as possible in order to keep the normal function of the cerebrum.
Adult↗
Disappearance of body fat in normal rats induced by adenovirus-mediated leptin gene therapy.
Sustained hyperleptinemia of 8 ng/ml was induced for 28 days in normal Wistar rats by infusing a recombinant adenovirus containing the rat leptin cDNA (AdCMV-leptin). Hyperleptinemic rats exhibited a 30-50% reduction in food intake and gained only 22 g over the experimental period versus 115-132 g in control animals that received saline infusions or a recombinant virus containing the beta-galactosidase gene (AdCMV-beta Gal). Body fat was absent in hyperleptinemic rats, whereas control rats pair-fed to the hyperleptinemic rats retained approximately 50% body fat. Further, plasma triglycerides and insulin levels were significantly lower in hyperleptinemic versus pair-fed controls, while fatty acid and glucose levels were similar in the two groups, suggestive of enhanced insulin sensitivity in the hyperleptinemic animals. Thus, despite equivalent reductions in food intake and weight gain in hyperleptinemic and pair-fed animals, identifiable fat tissue was completely ablated only in the former group, raising the possibility of a specific lipoatrophic activity for leptin.
Adenoviridae↗
Evidence from Earthquake Data for a Partially Molten Crustal Layer in Southern Tibet
Earthquake data collected by the INDEPTH-II Passive-Source Experiment show that there is a substantial south to north variation in the velocity structure of the crust beneath southern Tibet. North of the Zangbo suture, beneath the southern Lhasa block, a midcrustal low-velocity zone is revealed by inversion of receiver functions, Rayleigh-wave phase velocities, and modeling of the radial component of teleseismic P-waveforms. Conversely, to the south beneath the Tethyan Himalaya, no low-velocity zone was observed. The presence of the midcrustal low-velocity zone in the north implies that a partially molten layer is in the middle crust beneath the northern Yadong-Gulu rift and possibly much of southern Tibet.
Journal Article↗
Effects of assembly and mutations outside the active site on the functional pH dependence of Escherichia coli aspartate transcarbamylase.
Electrostatics are central to the function and regulation of Escherichia coli aspartate transcarbamylase, and modeling has suggested that long range electrostatic effects are likely to be important (Glackin, M. P., McCarthy, M. P., Mallikarachchi, D., Matthew, J. B., and Allewell, N. M. (1989) Proteins Struct. Funct. Genet. 5, 66-77; Oberoi, H., Trikha, J., Yuan, X., and Allewell, N. M. (1995) Proteins Struct. Funct. Genet., in press). To investigate this possibility from an experimental standpoint, we have examined the effects both of assembly and of removing ionizable and polar side chains outside the active site (Glu-50, Tyr-165, and Tyr-240) on the pH dependence of the kinetic parameters of aspartate transcarbamylase. The holoenzyme (c6r6) assembles from three regulatory dimers (r2) and two catalytically active trimers (c3). pH dependences of the enzyme kinetic parameters suggest that the mechanisms of productive binding of L-Asp to the binary complexes of the catalytic subunit (c3) and holoenzyme (c6r6) with carbamyl phosphate are different. In contrast, the Michaelis complex appears similar for both c3 and c6r6, except for pK shifts of approximately 1 pH unit. Results also indicate that the catalytic mechanism of the holoenzyme does not involve reverse protonation, as has recently been proposed for the catalytic trimer (Turnbull, J. L., Waldrop, G. L., and Schachman, H. K. (1992) Biochemistry 31, 6562-6569). The tyrosines at positions 165 and 240 are part of a cluster of interactions that links the catalytic subunits in the T state (the cluc4 interface) and which is disrupted in the T --> R transition. The effects of mutating the two Tyr residues are quite different: Y240F has higher than wild-type activity and affinity over the entire pH range, while Y165F has activity and affinity an order of magnitude lower than wild-type. Removal of the regulatory subunits from Y165F increases activity and affinity and restores the pH dependence of the wild-type catalytic subunit. Like Y165F, E50A has low activity and affinity over the entire pH range. Linkage analysis indicates that there is long range energetic coupling among the active site, the ear subunit interfaces, and residue Y165. The substantial quantitative difference between Y165F and Y240F, both of which are at the c1:c4 interface about 14-16 A from the closest active site, demonstrates specific path dependence, as opposed to general distance dependence, of interactions between this interface and the active site.
Amino Acid Sequence↗
Identification and analysis of long-range electrostatic effects in proteins by computer modeling:aspartate transcarbamylase.
While ion pairs are readily identified in crystal structures, longer range electrostatic interactions cannot be identified from the three-dimensional structure alone. These interactions are likely to be important in large, multisubunit proteins that are regulated by allosteric interactions. In this paper, we show that these interactions are readily detected by electrostatic modeling, using, as an example, unliganded Escherichia coli aspartate transcarbamylase, a widely studied allosteric enzyme with 12 subunits and a molecular weight of 310 kD. The Born, dipolar, and site-site interaction terms of the free energy of protonation of the 810 titratable sites in the holoenzyme were calculated using the multigrid solution of the nonlinear Poisson-Boltzmann equation. Calculated titration curves are in good agreement with experimental titration curves, and the structural asymmetry observed in the crystal structure is readily apparent in the calculated free energies and pK1/2 values. Most of the residues with pK1/2 values that differ substantially from those of model compounds are buried in the low dielectric medium of the protein, particularly at the intersubunit interfaces. The dependence of the site-site interaction free energies on distance is complex, with a steep dependence at distances less than 5 A and a more shallow dependence at longer distances. Interactions over distances of 6 to 15 A require a bridging residue and are often not apparent in the structure. The network of interactions between ionizable groups extends across and between subunits and provides a potential mechanism for transmitting long-range structural effects and allosteric signals.
Aspartate Carbamoyltransferase↗