[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.

[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.

Solution structure of the transforming growth factor beta-binding protein-like module, a domain associated with matrix fibrils

Here we describe the high resolution nuclear magnetic resonance (NMR) structure of a transforming growth factor beta (TGF-beta)-binding protein-like (TB) domain, which comes from human fibrillin-1, the protein defective in the Marfan syndrome (MFS). This domain is found in fibrillins and latent TGF-beta-binding proteins (LTBPs) which are localized to fibrillar structures in the extracellular matrix. The TB domain manifests a novel fold which is globular and comprises six antiparallel beta-strands and two alpha-helices. An unusual cysteine triplet conserved in the sequences of TB domains is localized to the hydrophobic core, at the C-terminus of an alpha-helix. The structure is stabilized by four disulfide bonds which pair in a 1-3, 2-6, 4-7, 5-8 pattern, two of which are solvent exposed. Analyses of MFS-causing mutations and the fibrillin-1 cell-binding RGD site provide the first clues to the surface specificity of TB domain interactions. Modelling of a homologous TB domain from LTBP-1 (residues 1018-1080) suggests that hydrophobic contacts may play a role in its interaction with the TGF-beta1 latency-associated peptide.

Comparative gene mapping of the human and mouse TEP1 genes, which encode one protein component of telomerases

The chromosomal locations of the human TEP1 (telomerase protein component 1) and mouse Tep1 genes, which were originally named TLP1 (telomerase protein 1) or TP1 (telomerase-associated protein 1), were determined by direct R-banding FISH and a molecular linkage analysis with interspecific backcross mice. The human TEP1 and mouse Tep1 genes were mapped by FISH to human chromosome 14q11.2 and to the C2D1 band of mouse chromosome 14, respectively. By means of genetic linkage mapping, the mouse gene was further localized as being 2.7 cM distal to D14Mit18 and D14Mit134 and 2.0 cM proximal to D14Mit5 on mouse chromosome 14, where conserved linkage homology with human chromosome 14q11-q12 has been identified.

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.

Purification, biochemical characterization and protein-DNA interactions of the I-CreI endonuclease produced in Escherichia coli

I- CreI is a member of the LAGLI-DADG family of homing nucleases; however, unlike most members of this family it contains only a single copy of this signature motif. I- CreI was over-expressed in Escherichia coli, and a simple purification protocol developed that gave reasonably pure protein in high yield. Size-exclusion chromatography and chemical cross-linking indicated that the protein is a dimer in solution. DNA cleavage by I- CreI was absolutely dependent on Mg2+(or Mn2+), and was inhibited by monovalent cations. I- CreI displayed a surprisingly high temperature optimum (>50 degrees C), with full activity occurring even at 70 degrees C. Interestingly, SDS was needed for efficient release of the cleavage products from the protein, indicating formation of very stable DNA-protein complexes. In contrast to these robust characteristics, purified I- CreI was unstable; however, it could be stabilized by the addition of either target or non-target DNA. Mobility shift assays revealed that I- CreI binds to DNA in the absence of Mg2+. Hydroxyl radical footprinting showed that I- CreI strongly protected the backbone of a continuous stretch of at least 12 nt on each strand that were shifted, relative to each other, by 2 bp in the 3'direction. Methylation protection and interference analyses were also performed, and together with the hydroxyl radical footprinting, indicate that I- CreI binds in both the major and minor grooves of its target DNA.

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.

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.

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.

[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.

Association between Ala54Thr substitution of the fatty acid-binding protein 2 gene with insulin resistance and intra-abdominal fat thickness in Japanese men

Alanine to threonine substitution at codon 54 of the fatty acid-binding protein 2 (FABP2) gene was recently shown to be associated with insulin resistance in Pima Indians. It has been hypothesized that the mutation may result in enhanced intestinal up-take of fatty acids, and thereby an impairment of insulin action. We analysed the association of the Ala54Thr substitution with insulin sensitivity and abdominal fat thickness in 395 Japanese men aged 50.5 +/- 8.8 years (mean +/- SD) with a body mass index of 24.4 +/- 3.0 kg/m2. The frequency of the Thr54 allele was 0.34. Although the polymorphism was not significantly associated with diabetes or impaired glucose tolerance, subjects homozygous for the Thr54 allele had higher basal insulin levels. Analysis by homeostasis model assessment showed an association between the amino acid substitution and greater insulin resistance, and slightly higher beta-cell function. Oral glucose tolerance tests performed in 392 subjects without fasting hyperglycaemia showed higher 2-h insulin concentrations in individuals homozygous for the Thr54 allele when compared with heterozygotes or homozygotes for the Ala54 allele. No significant association was obtained between the polymorphism of the FABP2 gene and body mass index. However, ultrasound measurements of abdominal fat thickness revealed a greater accumulation of intra-abdominal fat in subjects homozygous for the Thr54 allele, whereas subcutaneous fat thickness was not associated with the polymorphism. These observations suggest that the Ala54Thr substitution in the FABP2 gene is associated with insulin resistance in Japanese men, and that visceral fat accumulation might be involved in the impaired insulin action associated with the substitution.

[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.

Expression, purification and kinetic characterization of wild-type human ornithine transcarbamylase and a recurrent mutant that produces 'late onset' hyperammonaemia

Ornithine Transcarbamylase Deficiency, an X-linked disorder, is the most common cause of inherited urea cycle disorders. Approx. 90 mutations that produce reduced levels of ornithine transcarbamylase (OTCase) activity have been identified in patients [Tuchman (1993) Hum. Mutat. 2, 174-178; Tuchman and Plante (1995) Hum. Mutat. 5, 293-295]. A model of the three-dimensional structure of OTCase, developed on the basis of its homology to the catalytic subunit of Escherichia coli aspartate transcarbamylase (ATCase) [Tuchman, Morizono, Reish, Yuan and Allewell (1995) J. Med. Genet. 32, 680-688], and in good agreement with the crystal structure of Pseudomonas aeruginosa OTCase [Villeret, Tricot, Stalon and Dideberg (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 10762-10766], indicates that many mutations that produce severe clinical symptoms are at the active site or buried in the interior of the protein. However, one of the few recurrent mutations, R277W, an alteration that produces a milder phenotype of ornithine transcarbamylase deficiency, is located in the model in a loop remote from the active site that is analogous to a similar loop (the 240's loop, a flexible loop of the catalytic chain of Escherichia coli aspartate transcarbamylase, comprised of residues 230-250) of ATCase. Human wild-type OTCase and the R277W mutant have been cloned and overexpressed in E. coli and a rapid and efficient purification method utilizing the bisubstrate analogue, Ndelta-(phosphonacetyl)-L-ornithine, has been developed and used to purify both proteins. Gel chromatography indicates both are trimeric. The pH dependence of the kinetic parameters of the wild-type enzyme is similar to that of E. coli OTCase [Kuo, Herzberg and Lipscomb (1985) Biochemistry 24, 4754-4761], suggesting that its catalytic mechanism is similar, although its maximal activity is approx. 10-fold less. Compared with the wild-type, the R277W mutant has nearly 70-fold lower affinity for L-ornithine, shows no substrate inhibition, and its thermal stability is reduced by 5 degrees C. Its reduced affinity for L-ornithine, which in turn results in lower activity at physiological concentrations of ornithine, as well as its reduced stability, may contribute to the clinical effects that it produces.

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.

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.

[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.

[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%.

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.

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.

Mouse islet cell lysis mediated by interleukin-1-induced Fas

This study was conducted to investigate the possible involvement of Fas in beta-cell death in insulitis of Type 1 (insulin-dependent) diabetes mellitus. Although primary cultured Balb/c mouse islet cells did not express Fas mRNA, 4-12 hours of treatment with 10(2)-10(3) U/l of mouse interleukin-1 alpha (IL-1 alpha) induced the expression of Fas mRNA. Surface Fas expression was detected by immunofluorescence flow cytometry using a non-cytolytic anti-Fas monoclonal antibody after 6 or 12 h of incubation with 10(3) U/l of IL-1 alpha. Primary islet cells were resistant to an agonistic anti-Fas monoclonal antibody. However, 12 h pretreatment with IL-1 alpha sensitized islet cells to its cytolytic effect. Significant cell death was observed 24 h after the addition of anti-Fas, and progressively increased until 72 h, when specific 51Cr release was 72 +/- 6%. Agarose gel electrophoresis of DNA extracted from cells exposed to IL-1 alpha and agonistic anti-Fas showed internucleosomal DNA fragmentation, a hallmark of apoptotic cell death. Since the Fas antibody showed no cross-reactive activity of tumour necrosis factor (TNF), the cytotoxic effect was not mediated by TNF receptors. A protein synthesis inhibitor cycloheximide augmented Fas-mediated islet cell death. The Fas-mediated killing of islet cells was not L-arginine-dependent, or blocked by N(G)-monomethyl-L-arginine. beta-TC1 cells also expressed Fas mRNA when exposed to IL-1 alpha or IL-1 alpha plus interferon-gamma. These observations suggest that Fas-mediated apoptosis may be a mechanism of islet cell death in autoimmune insulitis.

Duplicated proteasome subunit genes in Drosophila melanogaster encoding testes-specific isoforms

Using the previously cloned proteasome alpha-type subunit gene Pros28.1, we screened a Drosophila melanogaster genomic library using reduced stringency conditions to identify closely related genes. Two new genes, Pros28.1A (map position 92F) and Pros28.1B (map position 60D7), showing high sequence similarity to Pros28.1, were identified and characterized. Pros28.1A encodes a protein with 74% amino acid identity to PROS28.1, while the Pros28.1B gene product is 58% identical. The Pros28.1B gene has two introns, located in exactly analogous positions as the two introns in Pros28.1, while the Pros28.1A gene lacks introns. Northern blot analysis reveals that the two new genes are expressed only in males, during the pupal and adult stages. Tissue-specific patterns of expression were examined using transgenic flies carrying lacz-fusion reporter genes. This analysis revealed that both genes are expressed in germline cells during spermatogenesis, although their expression patterns differed. Pros28.1A expression is first detected at the primary spermatocyte stage and persists into the spermatid elongation phase of spermiogenesis, while Pros28.1B expression is prominent only during spermatid elongation. These genes represent the most striking example of cell-type-specific proteasome gene expression reported to date in any system and support the notion that there is structural and functional heterogeneity among proteasomes in metazoans.

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.

Renal cell carcinoma development in the rat independent of alterations at the VHL gene locus

Germline alterations of the human von Hippel-Lindau (VHL) tumor suppressor gene predispose to renal cell carcinoma and a constellation of other tumor types found in VHL disease. This gene is also mutated or deleted in a high proportion of sporadic nonpapillary renal cell carcinomas. In the Eker rat model, spontaneous renal cell carcinoma develops with a high frequency. We therefore investigated the role of this tumor suppressor gene in the development of these hereditary rat tumors. By using reverse transcriptase (RT)-polymerase chain reaction (PCR) analysis, the sequence of the rat VHL gene was determined over the portion of the gene homologous to regions where most mutations in the human VHL gene occur. The sequence homology was 90% and the amino-acid identity 99% between the rat and human genes. A developmental and tumor-specific pattern of expression for the VHL gene was found; a ubiquitous 3.2-kb transcript was expressed in all rat tissues examined (neonatal kidney, lung, liver, brain, heart, kidney, spleen, testis, and stomach), and an additional 4.5-kb transcript was expressed in neonatal kidney and cell lines derived from Eker rat renal cell carcinomas (ERC cell lines). To determine whether mutations in the VHL gene were involved in tumor development in the Eker model, RT-PCR, single-strand conformation polymorphism (SSCP) analysis, and direct sequencing were used to search for alterations in this gene in the ERC cell lines. Alterations in the VHL gene were not detected by SSCP, and these data were confirmed by direct sequencing. Transformed rat kidney epithelial cell lines derived from Fisher rats also expressed the VHL gene but like the ERC cell lines did not contain mutations in the VHL gene. These data indicate that in the rat, transformation of kidney epithelial cells and the development of solid, nonpapillary renal cell carcinoma can occur via pathways that are independent of alterations at the VHL gene locus.

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.

The molecular basis of ornithine transcarbamylase deficiency: modelling the human enzyme and the effects of mutations

Human ornithine transcarbamylase is a trimer with 46% amino acid sequence homology to the catalytic subunit of E coli aspartate transcarbamylase. Secondary structure predictions, distributions of hydrophilic and hydrophobic regions, and the pattern of conserved residues suggest that the three dimensional structures of the two proteins are likely to be similar. A three dimensional model of ornithine transcarbamylase was generated from the crystal structure of the catalytic subunit of E coli aspartate transcarbamylase in the holoenzyme, by aligning the sequences, building in gaps, and minimising the energy. The binding sites for carbamyl phosphate in both enzymes are similar and the ornithine binding site in ornithine transcarbamylase appears to be in the same location as the L-aspartate binding site in aspartate transcarbamylase, with negatively charged side chains replaced by positively charged residues. Mutations in the ornithine transcarbamylase gene found in patients with hyperammonaemia of the "neonatal type" are clustered in important structural or functional domains, either in the interior of the protein, at the active site, or at the interchain interface, while mutations found in patients with milder "late onset" disease are located primarily on the surface of the protein. The predicted effects of all known missense mutations and in frame deletions in the ornithine transcarbamylase gene on the structure and function of the mature enzyme are described.

Preoperative segmental localization of focal hepatic lesion on MRI

In order to evaluate the accuracy of preoperative segmental localization of hepatic mass lesions, 68 cases were prospectively studied and evaluated by the correlation of magnetic resonance imaging (MRI) and surgical findings. Right, middle and left hepatic veins were seen in 100%, 97% and 94% of the subjects respectively on MRI. The right and left portal veins were seen in 100% and 95.6% respectively. The accuracy in determining the segmental location of hepatic lesions was 89.7%. The accuracy could be increased to 91.3% if the lesion was located at single segment whereas it was only 86.4% when the lesion extended across several segments. It is possible to say that MRI is an important modality in the preoperative segmental localization of masses.

[Pulmonary function detection in newborn infants]

We studied 120 full-term newborn infants and 20 pre-term infants by means of recording tidal breathing flow volume loops, passive flow volume technique and open circuit N2 washout technique. In the preterm infants, ventilatory function, FRC and Crs were lower than those in full-term infants, and Rrs were higher than those of full-term infants. TV, MV and PTEF were positively corelated with age (day), weight and height FRC, Crs and Trs were positively corelated with weight and height. TBFV loop in normal newborn infants did not show round or ellipse curve. The curve of expiration rose quickly, the position of expiration peak closed to the front, and decending line of expiration was relatively tilting. RR, Ti/Ttot, VPF, TPF, PF25, PTEF/TV, ME/MI, FRCkg, Crskg, sCrs, Rrs and sRrs were valuble indices in neonatal pulmonary function test. The results of our study are important in the establishment of normal values of pulmonary function indices for newborn infants in China.

[Primary tumour of the trachea with a report of 24 cases]

Twenty-four cases of primary tumour of trachea are reported in this article. In the 23 operated cases, 19 received curative excision (82.6%) and 4 cases palliative excision with tracheostomy. In these 24 cases, 21 cases were malignant and 3 cases benign. Tumour located at upper trachea in 8 cases, at median trachea in 6 cases and at lower trachea in 10 cases. The 19 operated patients all recovered. The survival rates in 1, 3, 5 and 10 years were 82.3% (14/17), 75% (9/12), 75% (6/8) and 50% (2/4), respectively. The authors suggested that early diagnosis should be paid more attention because misdiagnosis rate was high. The operation condition and procedures are discussed.

Test-tube simulated lipofuscinogenesis. Effect of oxidative stress on autophagocytotic degradation

Cysteine-stimulated oxidation of a rat liver lysosomal-mitochondrial fraction (LMF) was studied. The process would simulate oxidative stress-related events during the degradation of autophagocytosed material within secondary lysosomes, which may contribute to the formation of lipofuscin or age pigment. Millimolar concentration of cysteine was needed to stimulate LMF lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS). The amount of endogenous LMF iron was 545 micrograms/l and was enough to initiate peroxidation, probably through the reduction of ferric to ferrous iron by cysteine with induction of Fenton chemistry. Peroxidation could be completely inhibited by the addition of the iron chelator desferal or the antioxidant BHT. A substantial amount of the formed TBARS was associated with trichloroacetic acid (TCA) precipitable proteins. Elevated protein carbonyls was observed 1-2 h after the increase of TBARS. The tryptophan-tyrosine related protein autofluorescence (280/335 nm) decreased sharply during the first few hours of incubation. In contrast, a lipofuscin-type autofluorescence (345/430 nm) appeared only after a few days, suggesting that the latter fluorophore is not an immediate product of protein oxidation. The sequential formation of TBARS, protein carbonyls and lipofuscin-type autofluorescence as well as their dependence on iron and reducing agent add further support to the concept that lipofuscin forms in secondary lysosomes as a result of iron-catalyzed oxidative reactions involving autophagocytosed materials.

Measurement of the forefoot with roentgen stereophotogrammetry in hallux valgus surgery

Eight hallux valgus patients were marked with tantalum markers in conjunction with hallux valgus surgery (seven proximal osteotomies and one chevron osteotomy). Changes on weightbearing before surgery as well as corrective changes after surgery were analyzed with roentgen stereophotogrammetry (RSA) and with standard x-rays. RSA is accurate to 0.6 degrees in rotational changes and 0.3 mm in translation. Weightbearing changes were inconsistent, and minimal with both standard x-rays and RSA. It was possible to analyze the correction at the osteotomy site with RSA. In half the cases, the correction measured by RSA corresponded with that measured with standard x-rays, within measurement error; in the other cases, RSA showed that the correction was of a different size or direction than that measured on standard x-rays. Corrective changes in hallux valgus surgery are complex, including angular and translational changes at several levels and in several joints in order to produce a clinical resultant. Rotational changes can be evaluated with RSA. Although RSA in an optimal situation is very accurate, it is still limited to a laboratory setting.

Determination of the molecular lesions associated with loss-of-function transformer alleles of Drosophila melanogaster

Three mutant alleles of the transformer locus, trav1, trav2 and traenu, were analyzed genetically, and all were found to be functionally null alleles. The DNA sequences of these mutants revealed that they represent nonsense mutations that potentially encode truncated Tra polypeptides of 12, 61, and 90 amino acids, respectively.

The stability of three different cementless tibial components. A randomized radiostereometric study in 45 knee arthroplasty patients

We conducted a prospective, randomized study of 45 patients to evaluate 3 different uncemented tibial component designs in total knee arthroplasty. The stability of the components was assessed by radiostereometry (RSA), both as migration during 2 years and as inducible displacement at 2 years. The PCA resurfacing, the Tricon stem and the Tricon-M prosthesis groups showed a similar level of migration at 2 years, about 1.4 mm. In response to externally applied rotatory forces, the Tricon groups rotated more than the PCA group, interpreted as a consequence of the more conforming articular surface in the Tricon design. The series was divided into one group of continuously migrating prostheses with a poor prognosis (unstable, one third) and another group of prostheses in which migration stopped after 1 year (stable, two thirds). With this classification, no differences between the prostheses design groups were revealed. However, the unstable group showed a larger inducible displacement by provocation, an association hitherto not established.

The rates of commitment to renaturation of rhodanese and glutamine synthetase in the presence of the groE chaperonins

Current models of chaperonin-assisted folding suggest that proteins undergo multiple rounds of binding and release before they are released in a form that is committed to folding to the native state. Using immunoprecipitation techniques, we have determined the rates at which rhodanese and glutamine synthetase (GS) are released from groEL in a form committed to refold to active enzyme. Rhodanese and glutamine synthetase were chosen as substrates because they exhibit different solution requirements for the chaperonin system and they form stable "folding arrested" complexes with groEL. At various times during the groE-dependent renaturations, groEL was rapidly removed from the renaturation mixture by immunoprecipitation and centrifugation (30 s). The conformers that are committed to the native state remained in the supernatant and were assayed after 1 h. At 25 degrees C, the rate profiles indicate the release and commitment to folding of GS to its native state occurs far earlier (t1/2 < 1 min) than for rhodanese (t1/2 = 5 min). In light of previous results, it appears that GS monomers can attain a groE-independent assembly competent conformation after a brief interaction with the chaperonin. In contrast, the renaturation rate for rhodanese with the groE chaperonins mirrored the committed renaturation rates following groEL depletion. This suggests that rhodanese must interact with groEL throughout most of its folding reaction before it acquires a folding competent (groE independent) state. If current models of chaperonin mechanism are correct, rhodanese undergoes more rebinding and release cycles than does GS. Structurally, the degree of cycling and hence the rate of commitment to folding to the active form are probably dictated by the hydrophobic nature, number, and lifetimes of the folding intermediates that interact with the chaperonins.

Enterokinase, the initiator of intestinal digestion, is a mosaic protease composed of a distinctive assortment of domains

Enterokinase is a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin. This cleavage initiates a cascade of proteolytic reactions leading to the activation of many pancreatic zymogens. The full-length cDNA sequence for bovine enterokinase and partial cDNA sequence for human enterokinase were determined. The deduced amino acid sequences indicate that active two-chain enterokinase is derived from a single-chain precursor. Membrane association may be mediated by a potential signal-anchor sequence near the amino terminus. The amino terminus of bovine enterokinase also meets the known sequence requirements for protein N-myristoylation. The amino-terminal heavy chain contains domains that are homologous to segments of the low density lipoprotein receptor, complement components C1r and C1s, the macrophage scavenger receptor, and a recently described motif shared by the metalloprotease meprin and the Xenopus A5 neuronal recognition protein. The carboxyl-terminal light chain is homologous to the trypsin-like serine proteases. Thus, enterokinase is a mosaic protein with a complex evolutionary history. The amino acid sequence surrounding the amino terminus of the enterokinase light chain is ITPK-IVGG (human) or VSPK-IVGG (bovine), suggesting that single-chain enterokinase is activated by an unidentified trypsin-like protease that cleaves the indicated Lys-Ile bond. Therefore, enterokinase may not be the "first" enzyme of the intestinal digestive hydrolase cascade. The specificity of enterokinase for the DDDDK-I sequence of trypsinogen may be explained by complementary basic-amino acid residues clustered in potential S2-S5 subsites.

Wilms' tumor suppressor gene expression in rat and human mesothelioma

Induction of mesothelioma in the rat is an important animal model for assessing the carcinogenic potential of fibers and for understanding the molecular basis underlying the development of these tumors. Mesotheliomas and nephroblastoma (Wilms' tumor) have many developmental, biochemical, and histological similarities; however, the expression of the Wilms' tumor suppressor gene, WT-1, has not been well characterized in the rat, and its expression pattern in rat or human mesothelioma has not been described. We report that WT-1 transcripts (3.2 kilobases) could be detected by Northern analysis in adult rat testis, spleen, kidney, lung, heart, and glomerular mesangial cells. Normal adult mesothelial cells also expressed this gene. Rat mesothelioma cell lines expressed WT-1 transcripts of 3.2 kilobases and an additional 2.8-kilobase transcript, previously only reported to be expressed in the testis. Normal and transformed rat mesothelial cells expressed all four of the WT-1 splice variants, except testis, which only expressed WT-1 splice variants containing exon 5. Seven of seven human mesothelioma cell lines examined also expressed WT-1 transcripts, suggesting that expression of this gene may be useful in the diagnosis of these tumors.

[Repair of soft tissue defects of hand with pudendo-femoral skin flaps]

Soft tissue defects of the hand have been repaired with free pudendo-femoral skin flaps in 13 patients. The results are quite satisfactory in all cases. The flaps are thin with little fat to interfere with post-operative appearance. The donor sites are well-hidden and can be primarily closed with no functional disturbances. Hence the ideal donor site for soft tissue defects of the hand.

[Experiences in thumb and finger reconstruction]

24 cases (25 thumbs) of thumb reconstruction and 14 cases (10 fingers) of finger reconstruction by second toe transplantation, 11 cases of thumb reconstruction by the big toe-nail flap, and 1 case of "hand" reconstruction by both second toes are presented. 48 cases (52 fingers and thumbs) are successful. Functions and aesthetic results are satisfactory.

Mutations in the N-terminal region of human immunodeficiency virus type 1 matrix protein block intracellular transport of the Gag precursor

The matrix domain of human immunodeficiency virus type 1 Gag polyprotein was studied for its role in virus assembly. Deletion and substitution mutations caused a dramatic reduction in virus production. Mutant Gag polyproteins were myristoylated and had a high affinity for membrane association. Immunofluorescence staining revealed a large accumulation of mutant Gag precursors in the cytoplasm, while wild-type Gag proteins were primarily associated with the cell surface membrane. These results suggest a defect in intracellular transport of the mutant Gag precursors. Thus, in addition to myristoylation, the N-terminal region of the matrix domain is involved in determining Gag protein transport to the plasma membrane. Wild-type Gag polyproteins interacted with and efficiently packaged mutant Gag into virions. This finding is consistent with the hypothesis that intermolecular interaction of Gag polyproteins might occur in the cytoplasm prior to being transported to the assembly site on the plasma membrane.

Ethanol decreases glutamatergic synaptic transmission in rat nucleus accumbens in vitro: naloxone reversal

The nucleus accumbens septi (NAcc) is a key brain region in the rewarding effects of addictive drugs such as opiates and ethanol. We recently showed that opiate peptides reduced both excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) in NAcc neurons of a slice preparation, with naloxone (Nal) reversal (Yuan et al., 1992). To test other addictive drugs, we used intracellular recording in this rat NAcc slice preparation to investigate ethanol actions on NAcc neuronal properties. Ethanol 22 to 66 mM had little reproducible effect on membrane potential or input slope resistance, but reduced the amplitude of EPSPs evoked by stimulation of the peri-tubercle region ventral to NAcc. Ethanol 22, 44 and 66 mM all significantly decreased the EPSPs evoked by half-maximal stimulation to 80, 60 and 68% of control, respectively. Superfusion of 11 mM ethanol had no effect. To confirm a direct ethanol action on EPSPs, we tested 44 mM ethanol in the presence of 30 microM bicuculline to block IPSPs. In these cells ethanol still decreased EPSP size, suggesting GABAAergic IPSPs are not involved in this effect. The glutamate receptor blocker 6-cyano-7-nitroquinoxaline-2,3-dione abolished the EPSPs evoked at resting membrane potentials. As ethanol actions mimic those of opiates in reducing EPSPs without effect on resting membrane potentials in the NAcc, we applied the opiate antagonist Nal together with ethanol. Nal 1 to 2 microM significantly reversed ethanol (44 mM) reduction of EPSP amplitude. Thus, our data suggest that a major effect of intoxicating concentrations of ethanol in NAcc is to reduce glutamatergic synaptic transmission.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of electrical stimulation of the hypoglossal nerve on airflow mechanics in the isolated upper airway

To determine the influence of electrical hypoglossal (HG) nerve stimulation on upper airway airflow mechanics, we analyzed pressure-flow relationships obtained during bilateral supramaximal HG nerve stimulation over a range of frequencies from 0 to 100 Hz in the isolated feline upper airway. Inspiratory airflow (VI), hypopharyngeal pressure (Php), and pharyngeal pressure (Pph) immediately upstream from the flow-limiting site (FLS) were recorded while Php was rapidly lowered to achieve inspiratory flow limitation in the isolated upper airway. Pressure-flow relationships were analyzed to determine the maximum in VI (VImax) and the mechanical determinants of VImax, the upper airway critical pressure (Pcrit) and the nasal resistance (RN) upstream to the FLS. In groups of decerebrate spinally anesthetized (n = 6) and unanesthetized (n = 6) cats, graded increases in VImax (p < 0.05) and decreases in Pcrit (p < 0.001) were observed as the stimulation frequency of the intact HG nerves was increased. In the cats with and without spinal anesthesia, VImax increased by 139 and 201%, and Pcrit decreased by 159 and 280%, respectively. RN was also correlated with stimulation frequency in the cats without spinal anesthesia (p = 0.01) and increased in four of six cats with spinal anesthesia. In an additional six decerebrate cats, significant increases in VImax (p < 0.001) and decreases in Pcrit (p = 0.01) were elicited by stimulating the distal cut HG nerve ends (50 Hz), whereas no changes were noted in these parameters when the proximal ends were stimulated. The findings suggest that HG stimulation increases VImax by decreasing Pcrit, which indicates a decrease in upper airway collapsibility at the FLS.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutations in the cytoplasmic domain of human immunodeficiency virus type 1 transmembrane protein impair the incorporation of Env proteins into mature virions

In-frame stop codons were introduced into the coding region of human immunodeficiency virus type 1 (HIV-1) transmembrane protein (gp41). Truncation of 147 amino acids from the carboxyl terminus of gp41 (TM709) significantly decreased the stability and cell surface expression of the viral Env proteins, while truncation of 104 amino acids (TM752) did not. Truncation of 43 or more amino acids from the carboxyl terminus of gp41 generated mutant viruses which were noninfectious in several human CD4+ T lymphoid cell lines and fresh peripheral blood mononuclear cells. Analysis of the noninfectious mutant virions revealed significantly reduced incorporation of the Env proteins compared with the wild-type virions. Comparable amounts of Env proteins were detected on the surfaces of wild-type- and TM752-transfected cells, suggesting that the structures of gp41 required for efficient incorporation of Env proteins were disrupted in mutant TM752. Truncation of the last 12 amino acids (TM844) from the carboxyl terminus of gp41 did not significantly affect the assembly and release of virions or the incorporation of Env proteins into mature virions. However, the TM844 virus had dramatically decreased infectivity compared with the wild-type virus. This suggests that the cytoplasmic domain of gp41 also plays a role in other steps of virus replication.

Cleavage and recognition pattern of a double-strand-specific endonuclease (I-creI) encoded by the chloroplast 23S rRNA intron of Chlamydomonas reinhardtii

Several group-I introns have been shown to specifically invade intron-minus alleles of the genes that contain them. This type of intron mobility is referred to as 'intron homing', and depends on restriction endonucleases (ENases) encoded by the mobile introns. The ENase cleaves the intron-minus allele near the site of intron insertion, thereby initiating gene conversion. The 23S (LSU) rRNA-encoding gene (LSU) of the chloroplast genome of Chlamydomonas reinhardtii contains a self-splicing group-I intron (CrLSU) that has a free-standing open reading frame (ORF) of 163 codons. Translation of CrLSU intron RNA in cell-free systems produces a polypeptide of approx. 18 kDa, the size expected for correct translation of the ORF. The in vitro-synthesized 18-kDa protein cleaves plasmid DNA that contains a portion of LSU where the intron normally resides, but lacking the intron itself. Cleavage by the intron-encoded enzyme (I-CreI) occurs 5 bp and 1 bp 3' to the intron insertion site (in the 3'-exon) in the top (/) and bottom (,) strands, respectively, resulting in 4-nt single-stranded overhangs with 3'-OH termini. We also show that the recognition sequence of I-CreI spans the cleavage site and is 24 bp in length (5'-CAAAACGTC,GTGA/GACAGTTTGGT).