Gene admixture in the silk road region of China: evidence from mtDNA and melanocortin 1 receptor polymorphism

Mitochondrial DNA control region segment I sequences and melanocortin 1 receptor (MC1R) gene polymorphism were examined in ethnic populations in the silk road region of China. Both the frequencies of the MC1R variants and the results of mtDNA data in this region presented intermediate values between those of Europe and East and Southeast Asia, which suggested extensive gene admixture in this area and was in general agreement with previous studies. Phylogenetic analysis of the ethnic populations in the Silk Road region that based on mtDNA data didn't show expected cluster pattern according to their ethnogenesis. We suspect that a high migration rate in female among these closely related populations and other three demographic events might account for it.

Depressed renal and vascular nitric oxide synthase expression in cyclosporine-induced hypertension

BACKGROUND

Introduction of cyclosporine (CsA) for clinical use has greatly enhanced the outcome of organ transplantation. However, CsA can cause nephrotoxicity and hypertension (HTN). This study was designed to test the hypothesis that CsA-induced HTN is related to depressed nitric oxide (NO) production.

METHODS

Urinary excretion of NO metabolites (NOx) and endothelial and inducible NO synthase (eNOS and iNOS) proteins were determined in thoracic aortas and kidneys of CsA-treated (given CsA 18 mg/kg/day for 3 weeks) and placebo-treated rats. In addition, renal tissue eNOS and iNOS mRNA and aorta iNOS activity were measured.

RESULTS

CsA administration resulted ina significant rise in arterial blood pressure (BP) coupled with a steady decline in urinary NOx excretion, suggesting depressed NO production. This was accompanied by a significant reduction in iNOS protein abundance in the kidney and thoracic aorta but no change in eNOS protein abundance. The fall in renal iNOS protein in CsA-treated rats was accompanied by a parallel decline in iNOS mRNA abundance and enzymatic activity.

CONCLUSION

Administration of CsA for three weeks resulted in a significant rise in BP together with marked reductions in urinary NOx excretion, and renal and vascular iNOS expression. These observations suggest that CsA-induced HTN may be, in part, related to impaired NO production. If true, strategies designed to restore NO availability may mitigate HTN and other vascular complications of CsA therapy.

Phylogenetic relationships of bears (the Ursidae) inferred from mitochondrial DNA sequences

The phylogenetic relationships among some bear species are still open questions. We present here mitochondrial DNA sequences of D-loop region, cytochrome b, 12S rRNA, tRNA(Pro), and tRNA(Thr) genes from all bear species and the giant panda. A series of evolutionary trees with concordant topology has been derived based on the combined data set of all of the mitochondrial DNA sequences, which may have resolved the evolutionary relationships of all bear species: the ancestor of the spectacled bear diverged first, followed by the sloth bear; the brown bear and polar bear are sister taxa relative to the Asiatic black bear; the closest relative of the American black bear is the sun bear. Primers for forensic identification of the giant panda and bears are proposed. Analysis of these data, in combination with data from primates and antelopes, suggests that relative substitutional rates between different mitochondrial DNA regions may vary greatly among different taxa of the vertebrates.

Risk factors for suicide in China's youth: a case-control study

BACKGROUND

Suicide is the most common cause of death among youth in China.

METHOD

A case-control psychological autopsy study in 23 geographically representative disease surveillance points around China collected information from family members and close associates of 114 persons aged 15-24 years who died by suicide (cases) and 91 who died of other injuries (controls).

RESULTS

Among the 114 suicides 61% were female, 88% lived in rural villages, 70% died by ingesting pesticides (most commonly stored in the home), 24% previously attempted suicide, and 45% met criteria of a mental illness at the time of death. Multivariate logistic regression identified several independent risk factors: severe life events within 2 days before death (OR 31.8, 95% CI 2.6-390.6), presence of any depressive symptoms within 2 weeks of death (OR 21.1, 95% CI 4.6-97.2), low quality of life in the month before death (OR 9.7, 95% CI 2.8-34.1), and acute stress at time of death (moderate: OR 3.1, 95% CI 0.8-11.9; high: OR 9.1, 95% CI 1.2-66.8). A significant interaction between mental illness at time of death and gender indicated that diagnosis was an important predictor of suicide in males (OR 14.0, 95% CI 2.6-76.5) but not in females (OR 0.3, 95% CI 0.0-3.6). Prior suicide attempt was related to suicide in the univariate analysis (OR 57.5) but could not be included in the multivariate model because no controls had made prior attempts.

CONCLUSIONS

Suicide prevention efforts for youth in China must focus on restricting access to pesticides, early recognition and management of depressive symptoms and mental illnesses, improving resiliency, and enhancing quality of life.

Human papillomavirus infection in Beijing, People's Republic of China: a population-based study

Background:

No recent data exist on human papillomavirus (HPV) infection in Beijing, People's Republic of China.

Materials and method

We interviewed and examined a representative, randomly selected sample of 5552 sexually active women aged 25–54 years. Cervical cell samples were analysed for HPV DNA by a MY09/11-based PCR assay.

Results:

Human papillomavirus prevalence was 6.7% overall and 4.8% among women without cervical abnormalities. Of the 21 subtypes identified, HPV16 was the commonest type (2.6% overall; 39.1% of HPV-positive women), followed by HPV 58 (1.0%), 33 (0.8%), 43 (0.7%) and 56 (0.7%). High-risk HPV types predominated in all age groups. Human papillomavirus prevalence was highest in young to middle-aged women. Marital status, number of husband's sexual partners, age at sexual debut and nulligravidity were all associated with being HPV positive.

Conclusions:

In our survey, HPV 16, HPV 58 and HPV 33 were the most prevalent HPV types in Beijing, indicating the potential for the prophylactic HPV 16/18 vaccine in China.

Mini review roles of the bZIP gene family in rice

The basic leucine zipper (bZIP) genes encode transcription factors involved in the regulation of various biological processes. Similar to WRKY, basic helix-loop-helix, and several other groups of proteins, the bZIP proteins form a superfamily of transcription factors that mediate plant stress responses. In this review, we present the roles of bZIP proteins in multiple biological processes that include pathogen defense; responses to abiotic stresses; seed development and germination; senescence; and responses to salicylic, jasmonic, and abscisic acids in rice. We also examined the characteristics of the bZIP proteins and their genetic composition. To ascertain the evolutionary changes in and functions of this supergene family, we performed an exhaustive comparison among the 89 rice bZIP genes that were previously described and those more recently listed in the MSU Rice Genome Annotation Project Database using a Hidden Markov Model. We excluded 3 genes from the list, resulting in a total of 86 bZIP genes in japonica rice.

Serum lactic dehydrogenase strongly predicts survival in metastatic nasopharyngeal carcinoma treated with palliative chemotherapy

BACKGROUND AND OBJECTIVE

The survival outcomes of patients with metastatic nasopharyngeal carcinoma (NPC) differ significantly between individuals. This study aimed to evaluate whether serum lactic dehydrogenase (S-LDH) level had a clinical value in predicting clinical response and survival outcome for patients with metastatic NPC.

METHODS

S-LDH level was measured at baseline and then before every cycle of treatment in 689 NPC patients with distant metastases. Correlations of pre-treatment and post-treatment S-LDH levels to response of treatment and survival were analysed retrospectively.

RESULTS

Patients with elevated values of pre-treatment S-LDH (>245 IU/L) had significantly worse survival than those with normal values of pre-treatment S-LDH (≤245 IU/L) (P<0.001). Patients with elevated values of post-treatment S-LDH had worse survival compared with those with normal values of post-treatment S-LDH (P<0.001). Patients with normal values of pre-treatment and post-treatment S-LDH showed the highest response rate and the most favourable prognosis.

CONCLUSION

S-LDH appears to be a significant independent prognostic index in patients with disseminated NPC that should be considered in the comparison of the results achieved with different therapies and in planning new randomised clinical therapeutic trials.

The role of directly applied hypothermia in spinal cord injury

STUDY DESIGN

The effect of intense local hypothermia was evaluated in a precision model of spinal canal narrowing and spinal cord injury in rats. The spinal cord injury was cooled with a custom cooling well used over the epidural surface. Basso, Beattie, and Bresnahan (BBB) motor scores and transcranial magnetic motor-evoked potential (tcMMEP) responses were used after injury to accurately evaluate neurologic recovery.

OBJECTIVE

This study was undertaken to determine whether the prognosis for neurologic recovery in a standardized rat spinal cord injury model is altered by the direct application of precisely controlled hypothermia to the area of injury.

SUMMARY OF BACKGROUND DATA

The role of hypothermia in the treatment of spinal cord injuries with neurologic deficits remains undefined. Hypothermia may decrease an area of spinal cord injury and limit secondary damage, therefore improving neurologic recovery. However, it has been difficult to consistently apply localized cooling to an area of spinal cord injury, and the use of systemic hypothermia is fraught with complications. This fact, along with the unavailability of a precise spinal cord injury model, has resulted in inconsistent results, both clinically and in the laboratory. In a rat model of spinal cord injury, 37 C and 19 C temperatures were used to study the role of hypothermia on neurologic recovery.

METHODS

Male Spraque-Dawley rats (n = 52; weight, 277.7 g) were anesthetized with pentobarbital and subjected to laminectomy at T10. The rats were divided into three groups: 1) placement of a 50% spacer in the epidural space (16 rats), 2) severe (25 g/cm) spinal cord injury (16 rats), 3) 50% spacer in combination with spinal cord injury (16 rats). Eight rats in each group were tested at two temperatures: normothermic (37 C) and hypothermic (19 C). With the use of a specially designed hypothermic pool placed directly over the spinal cord for 2 hours, epidural heating to 37 C, and epidural cooling to 19 C was accomplished. Simultaneous measurements of spinal cord and body temperatures were performed. The rats underwent behavior testing using the BBB motor scores and serial tcMMEPs for 5 weeks. Statistical methods consisted of Student's t tests, one-way analysis of variance, Tukey post hoc t tests and chi2 tests.

RESULTS

There was a significant improvement in motor scores in rats subjected to hypothermia compared with those that were normothermic after insertion of a 50% spacer. This improvement was observed during the 5-week duration of follow-up. In the severe spinal cord injury group and the spinal cord injury-spacer groups, no significant improvement in motor scores were obtained when the spinal cord was exposed to hypothermia.

CONCLUSION

The results demonstrate that there is a statistically significant (P < 0.05) improvement in neurologic function in rats subjected to hypothermia (19 C) after insertion of a spacer that induced an ischemic spinal cord injury. This indicates that directly applied hypothermia may be beneficial in preventing injury secondary to ischemic cellular damage. The data demonstrated minimal therapeutic benefit of hypothermia (19 C) after a severe spinal cord injury.

Self-assembling DNA-lipid particles for gene transfer

PURPOSE

We have demonstrated that a heteromolecular complex consisting of cationic lipids and DNA can be prepared and isolated (1). Cationic lipids bind DNA through electrostatic interactions. However, when sufficient lipids are bound to DNA the physical and chemical properties of the complex are governed by hydrophobic effects. Here we describe an approach where this hydrophobic complex is used as an intermediate in the preparation of lipid-DNA particles (LDPs).

METHODS

The approach relies on the generation of mixed micelles containing the detergent, n-octyl beta-D-glucopyranoside (OGP), the cationic lipid, N-N-dioleoyl-N, N-dimethylammonium chloride (DODAC), and selected zwitterionic lipids, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) or egg sphingomyelin (SM).

RESULTS

When these micelles were prepared at low detergent concentrations (20 mM OGP) and combined with pCMV beta DNA, LDPs spontaneously formed. The mean diameter of these particles as measured by quasielastic light scattering was 55-70 nm, a result that was confirmed by negative stain electron microscopy. Further characterization of these LDPs showed that DNA within the particles was inaccessible to the small fluorochrome TO-PRO-1 and protected against DNase I degradation. LDPs could also be prepared in high concentrations of OGP (100 mM), however particles formed only after removal of OGP by dialysis. Particles formed in this manner were large (> 2000 nm) and mediated efficient transfection of Chinese hamster ovary cells. Transfection activity was greater when the lipid composition used consisted of SM/ DODAC. Small particles (< 100 nm) prepared of SM/DODAC were, however, inefficient transfecting agents.

CONCLUSIONS

We believe that LDP formation is a consequence of the molecular forces that promote optimal hydrocarbon-hydrocarbon interactions and elimination of the hydrocarbon-water interface.

A convenient method of measuring the thermal conductivity of biological tissue

The basic principle of the thermal conductivity probe is described. Thin probes were developed based on this principle, with a reproducibility of 5.3% and relative error less than 6.0%. Each measurement can be completed in 90 s and the temperature increase can be controlled within 2 degrees C. Using the probes, the thermal conductivities of pig fat, meat, liver, kidney and live and dead snake head were measured and it was found that water content plays an important role in influencing the magnitude of the thermal conductivity of biological tissues. The probe can be used over a temperature range from -40 to 150 degrees C.

Identification of Sarcocystis hominis-like (Protozoa: Sarcocystidae) cyst in water buffalo (Bubalus bubalis) based on 18S rRNA gene sequences

DNA templates were extracted from isolates of Sarcocystis hominis-like cysts collected from cattle and water buffalo, as well as from Sarcocystis fusiformis cysts and Sarcocystis suihominis cysts. The 18S rRNA genes were amplified using DNA from a single cyst as the templates. Approximately 1,367-1,440 bp sequences were obtained. The sequence difference in isolates of Sarcocystis hominis-like cysts from water buffaloes, and isolates of S. hominis cysts from cattle were very low, only about 0.1%, much lower than the lowest value (1.7%) among different species. Combined with their morphological structure, these sequence data indicate that the 4 isolates from cattle and water buffalo might be the same species, i.e., S. hominis, suggesting that both cattle and water buffalo may serve as the intermediate hosts for this parasite. Apparently, this is the first report using a single cyst to do such work and is a useful way to distinguish the Sarcocystis cyst in an intermediate host that may be simultaneously infected by several different Sarcocystis species.

Identification of 'genotoxic' and 'non-genotoxic' alerts for cancer in mice: the carcinogenic potency database

A set of chemicals tested for carcinogenicity in mice that have been analyzed by Gold et al. [L.S. Gold, C.B. Sawyer, R. Magaw, G.M. Backman, M. deVeciana, R. Levinson, N.K. Hooper, W.R. Havender, L. Bernstein, R. Peto, M.C. Pike, B.N. Ames, Environ. Health Perspect. 58 (1984) 9-319; L.S. Gold, M. deVeciana, G.M. Backman, M. Lopipero, M. Smith, R. Blumenthal, R. Levinson, L. Bernstein, B.N. Ames, Environ. Health Perspect. 67 (1986) 161-200; L.S. Gold, T.H. Slone, G.M. Backman, R. Magaw, M. DaCosta, P. Lopipero, M. Blumenthal, B.N. Ames, Environ. Health Perspect. 74 (1987) 237-329; L.S. Gold, T.H. Slone, G.M. Backman, S. Eisenberg, M. DaCosta, M. Wong, N.B. Manley, L. Rohrbach, B.N. Ames, Environ. Health Perspect. 84 (1990) 215-286; L.S. Gold, N.B. Manley, T.H. Slone, T.H. Garfinkle, L. Rohrbach, B.N. Ames, Environ. Health Perspect. 100 (1993) 65-135] in the first five plots of the carcinogenic potency database (CPDB) was subjected to CASE/MULTICASE analyses. Briefly, CASE/MULTICASE is a computer-automated structure evaluation system that is capable of identifying structural features of chemicals associated with a specified biological activity (e.g., carcinogenicity or mutagenicity). These features are then incorporated into a structure-activity relationship (SAR) model for the analyzed database. The mouse CPDB used in this study consists of 627 chemicals, 289 of which are carcinogens, 11 marginal or weak carcinogens (i.e., chemicals requiring high doses to induce cancer) and 327 non-carcinogens. In an internal prediction analysis where the CASE/MULTICASE SAR model was used to predict the carcinogenicity of chemicals used to create the model, a concordance between experimental and predicted results of 96% was obtained. This indicates that the model is able to satisfactorily explain the chemicals in the learning set. In a drop-one cross-validation study where chemicals were removed one at a time and the remaining n - 1 chemicals were used in an iterative method to create a model to predict the removed chemical, CASE/MULTICASE was able to achieve a concordance between experimental and predicted results of 70%. Using a modified validation process designed to investigate the predictivity of a more focused SAR model, the system achieved a 78% concordance between experimental and predicted results. Among the major biophores identified by CASE/MULTICASE associated with cancer causation in mice several are derived from electrophilic or potentially electrophilic compounds (e.g., hydrazines, N-mustards, N-nitrosamines, aromatic amines, reactive halogens, and quinones). Other biophores however are derived from chemicals seemingly devoid of actual or potential DNA-reactivity and as such may represent structural feature of non-genotoxic carcinogens.

Prolonged inactive phases during the discontinuous pattern of prematurity in the electroencephalogram of very-low-birthweight infants

A consecutive cohort of 46 very-low-birthweight infants, who had routine electroencephalograms (EEGs) while in the neonatal intensive care unit, were studied. Two infants were lost to follow-up and were excluded, leaving a study population of 44 infants. Their mean birthweight was 945 +/- 166 g, gestation 27.1 +/- 1.7 weeks. Thirteen infants died before discharge. The remaining 31 had a mean corrected age of 26.1 +/- 8.7 months at the time of the last visit. Three groups were distinguished: normal survivors, handicapped survivors and non-survivors. The longest inactive phase encountered in the discontinuous EEG was the yardstick of the study with 3 subdivisions: less than 20 sec. 20-29 sec and equal to or more than 30 sec. The data showed a relative increase in poor outcome with increasing duration of inactivity (P less than 0.05) and, conversely, a favorable outcome with the absence of 20 sec or longer inactivity (P less than 0.001). All infants received therapeutic doses of phenobarbital during the early part of their illness which could have affected their EEG. Mean phenobarbital levels, obtained close to the time of the EEG, however, did not differ significantly and failed to show a significant relationship between the duration of the inactive phase and drug level observed. Inactive phases greater than or equal to 30 sec were more common (P less than 0.01) in infants with intraventricular hemorrhage. We conclude: although full recovery and normal outcome have been documented, prolonged isoelectric phases beyond 30 sec are more common in infants with fatal outcome.

Structural analysis of Sindbis virus capsid mutants involving assembly and catalysis

Sindbis virus core protein (SCP) has been isolated from virus and crystallized. The X-ray crystallographic structure showed that the amino-terminal 113 residues appeared to be either disordered or truncated during crystallization and that the carboxy-terminal residues 114 to 264 had a chymotrypsin-like structure. The carboxy-terminal residues 106 to 264 and 106 to 266 of SCP have now been expressed in Escherichia coli. Most crystal forms of the truncated proteins were isomorphous with those of the virally extracted protein. There are only small structural differences between the truncated recombinant protein and the ordered part of the wild-type virus-extracted protein. Hence, E. coli-expressed SCP can be used to study proteolytic properties and the contribution of SCP to nucleocapsid assembly, interaction with the E2 glycoprotein and interaction with RNA. The same dimer that was found in two different crystal forms of the virus-extracted SCP was present also in some of the crystals of the truncated recombinant protein. The monomer-monomer interface is maintained by two pairs of hydrogen bonds and by hydrophobic interactions. Removal of the hydrogen bonds by single substitutions did not prevent dimer formation. However, a mutation that reduced the hydrophobic contacts did inhibit dimer formation. The wild-type truncated SCP is active in E. coli, as evidenced by proteolytic processing of a series of progressively longer precursors that extend beyond residue 264. Unlike the virus-extracted capsid protein, the E. coli-expressed SCP described here is terminated following the carboxy-terminal residue and, therefore, does not require autocatalysis. Nevertheless, the E. coli-expressed protein folds with the carboxy-terminal tryptophan residue in the specificity pocket. Two crystallographically independent molecules of SCP(106 to 266), which had two additional downstream residues and had the essential S215 mutated to alanine, showed two distinct modes of binding the uncleaved carboxy-terminal residues. These may represent successive steps of binding substrate prior to catalytic cleavage. Refinement of the various crystal structures of SCP showed that the amino-terminal arm from residues 107 to 113 was not disordered, but is associated with neighboring molecules. Residues 108 to 111 bind into a hydrophobic pocket composed primarily of Y180, W247 and F166. It had been shown that the double mutant (Y180S; E183G), with the Y180S substitution in this pocket, produced a large number of non-infectious virions, possibly because of modification in the interaction of the glycoprotein spikes with core proteins. The crystal structure of this double mutant showed that there was a large positional change in the side-chain of W247, which moved into the space created by the replacement of Y180 with serine. These conformational changes may alter the stability of the virion and, thus, regulate its functional requirements during cell entry.

Evolutionary history of the mtDNA 9-bp deletion in Chinese populations and its relevance to the peopling of east and southeast Asia

In total, 1218 Chinese from twelve ethnic groups and nine Han geographic groups were screened for the mtDNA 9-bp deletion motif. The frequency of the 9-bp deletion in all samples was 14.7% but ranged from 0% to 32% in the various ethnic groups. Three individuals had a triplication of the 9-bp segment. Phylogenetic and demographic analyses of the mtDNA hypervariable segment 1 (HVS 1) sequences suggest that the 9-bp deletion occurred more than once in China. The majority of the Chinese deletion haplotypes (about 90%) have a common origin as a mutational event following an initial expansion of modern humans in eastern Asia. Other deletion haplotypes and the three haplotypes with a 9-bp triplication may have arisen independently in the Chinese, presumably by replication error. HVS1 haplotype analysis suggests two possible migration routes of the 9-bp deletion in east and southeast Asia. Both migrations originated in China with one route leading to the Pacific Islands via Taiwan, the other to southeast Asia and possibly the Nicobar Islands. Along both routes of peopling, a decrease in HVSI diversity of the mtDNA haplotypes is observed. The "Polynesian motif (16217T/C, 16247A/G, and 16261C/T)" and the 16140T/C, 16266C/A, or C/G polymorphisms appear specific to each migration route.

Interaction of a peptide model of a hydrophobic transmembrane alpha-helical segment of a membrane protein with phosphatidylethanolamine bilayers: differential scanning calorimetric and Fourier transform infrared spectroscopic studies

High-sensitivity differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to study the interaction of a synthetic alpha-helical hydrophobic transmembrane peptide, Acetyl-Lys2-Gly-Leu24-Lys2-Ala-Amide, and members of a homologous series of n-saturated diacylphosphatidylethanolamines (PEs). In the lower range of peptide mol fractions, the DSC endotherms exhibited by the lipid/peptide mixtures consist of two components. The temperature and cooperativity of the sharper, higher-temperature component are very similar to those of pure PE bilayers and are almost unaffected by variations in the peptide/lipid ratio. However, the fractional contribution of this component to the total enthalpy change decreases with increases in peptide concentration, and this component completely disappears at higher peptide mol fractions. The other component, which is less cooperative and occurs at a lower temperature, predominates at higher peptide concentrations. These two components of the DSC endotherm can be attributed to the chain-melting phase transitions of peptide-nonassociated and peptide-associated PE molecules, respectively. Although the temperature at which the peptide-associated PE molecules melt is progressively decreased by increases in peptide concentration, the magnitude of this shift is independent of the length of the PE hydrocarbon chain. In addition, the width of the phase transition observed at higher peptide concentrations is also relatively insensitive to PE hydrocarbon chain length, except that peptide gel-phase immiscibility occurs in very short- or very long-chain PE bilayers. Moreover, the enthalpy of the chain-melting transition of the peptide-associated PE does not decrease to 0 even at high peptide concentrations, suggesting that this peptide does not abolish the cooperative gel/liquid-crystalline phase transition of the lipids with which it is in contact. The FTIR spectroscopic data indicate that the peptide remains in a predominantly alpha-helical conformation, but that the peptide alpha-helix is subject to small distortions coincident with the changes in hydrophobic thickness that accompany the chain-melting phase transition of the PE bilayer. These data also indicate that the peptide significantly disorders the hydrocarbon chains of adjacent PE molecules in both the gel and liquid-crystalline states relatively independently of lipid hydrocarbon chain length. The relative independence of many aspects of PE-peptide interactions on the hydrophobic thickness of the host bilayer observed in the present study is in marked contrast to the results of our previous study of peptide-phosphatidylcholine (PC) model membranes (Zhang et al. (1992) Biochemistry 31:11579-11588), where strong hydrocarbon chain length-dependent effects were observed. The differing effects of peptide incorporation on PE and PC bilayers is ascribed to the much stronger lipid polar headgroup interactions in the former system. We postulate that the primary effect of transmembrane peptide incorporation into PE bilayers is the disruption of the relatively strong electrostatic and hydrogen-bonding interactions at the bilayer surface, and that this effect is sufficiently large to mask the effect of hydrophobic mismatch between the lengths of the hydrophobic core of the peptide and its host bilayer.

Crystal structure of the neutral form of fructose-1,6-bisphosphatase complexed with the product fructose 6-phosphate at 2.1-A resolution

The crystal structure of fructose-1,6-bisphosphatase (EC 3.1.3.11) complexed with the product fructose 6-phosphate (F6P) has been refined at 2.1-A resolution to an R factor of 0.177 with root-mean-square deviations of 0.014 A and 2.9 degrees from the ideal geometries of bond lengths and bond angles, respectively. The secondary structures but not the trace of the unligated enzyme have been slightly revised in the F6P complex at this higher resolution. Helix H4 in the unligated structure has been refined to a helix-like coil, and two very short 3(10) helices have been found, one in H4 and one in H5. F6P at 10 mM concentration in the absence of divalent metals in our study shows major binding at the active site and minor binding at the AMP site. The major site has almost equal full occupancy in the C1 and C2 chains of the crystallographic asymmetric unit, while the minor site shows occupancy only in the C1 chain at about 50%. The electron density in both (2Fo - Fc) and (Fo - Fc) maps calculated by omitting F6P slightly favors the beta anomer of D-F6P over the alpha anomer. Possible functions of the active-site residues are discussed, and candidates are suggested for site-directed mutagenesis.

O6-methylguanine-DNA methyltransferase activity in human tumors

The distribution of O6-methylguanine-DNA methyltransferase (MGMT) activity in extracts of tumors from 74 patients was measured. The results demonstrated that there was considerable variation of MGMT activity in different human tumor tissues as well as in different individuals. The mean values (X +/- SD, pmol/mg of protein) in breast cancer, stomach cancer, small cell lung cancer, non-small cell lung cancer, renal cell carcinoma, esophageal carcinoma, brain tumors, colon carcinoma and malignant melanoma were 1.071 +/- 0.374 (9), 0.515 +/- 0.107 (5), 0.509 +/- 0.251 (5), 0.461 +/- 0.227 (24), 0.329 +/- 0.246 (5), 0.273 +/- 0.376 (5), 0.244 +/- 0.175 (14), 0.242 +/- 0.308 (5) and 0.201 +/- 0.161 (2) respectively. It was notable that six samples (1/24 non-small cell lung cancer, 3/5 esophageal carcinoma, 1/14 brain tumors and 1/5 colon carcinoma) did not have any detectable level of MGMT activity. Activity of glutamine pyruvic transaminase (GPT) was also measured in the same extracts used for the assay of MGMT activity. The activity of GPT in these samples with undetectable level of MGMT activity was similar to those with significant MGMT activity. These results further strengthen the assumption that a certain fraction of human tumors are Mer-.

Anesthetic effects on motor evoked potentials in dogs

The effects of the various anesthetic agents on the production of transcranial magnetic motor evoked potentials (tcMMEP) were studied in a canine model. Pre-anesthetic baseline tcMMEPs demonstrated consistency in onset latency measurements and variability in measurement of peak-to-peak amplitudes. Changes in tcMMEPs were evaluated following the individual administrations of sodium pentothal, etomidate, halothane, fentanyl, and ketamine. For induction of anesthesia, etomidate was compatible with tcMMEP production, whereas sodium pentothal resulted in loss of hindlimb potentials for a period of 45 minutes. For maintenance of anesthesia, halothane was incompatible with the measurement of tcMMEPs. Fentanyl administration was consistent with the recording of reliable tcMMEPs, with consistent onset latencies but widely variable peak-to-peak amplitudes. Ketamine was compatible with stable and reproducible tcMMEP production. The results of this study suggest that anesthetic agents have a predictable and consistent effect on tcMMEP responses.

Nucleotide sequence and rt-PCR detection of a virus associated with grapevine rupestris stem-pitting disease

ABSTRACT Grapevine rupestris stem pitting (RSP) is a graft-transmissible disease of unknown etiology. We have characterized a virus associated with this disease. The entire genomic sequence (GenBank accession number AF026278) consisted of 8,725 nucleotides excluding a poly(A) tail. Six open reading frames (ORF) were found. ORF1 potentially encodes a polypeptide with a methyltransferase domain, a papain-like proteinase domain, a helicase domain, and a RNA-dependent RNA polymerase domain; ORF2, ORF3, and ORF4 compose a triple-gene block; ORF5 encodes a coat protein; and ORF6 is located near the 3' end with unknown function. Sequence analysis indicated that the virus is most similar to apple stem-pitting virus and may be allied with the carla- and potexviruses and grouped with other viruses that infect woody hosts. A specific reverse-transcription polymerase chain reaction (RT-PCR)-based detection method was developed. Among 62 grapevine sources known to be infected with rupestris stem-pitting disease, 60 sources tested positive by RT-PCR. Among 43 healthy vines tested, all were negative. The name grapevine rupestris stem-pitting-associated virus is proposed.

Local blockade of Rydberg excitation in an ultracold gas

In the laser excitation of ultracold atoms to Rydberg states, we observe a dramatic suppression caused by van der Waals interactions. This behavior is interpreted as a local excitation blockade: Rydberg atoms strongly inhibit excitation of their neighbors. We measure suppression, relative to isolated atom excitation, by up to a factor of 6.4. The dependences of this suppression on both laser irradiance and atomic density are in good agreement with a mean-field model. These results are an important step towards using ultracold Rydberg atoms in quantum information processing.

Mitochondrial DNA variation in cattle of south China: origin and introgression

Ten restriction endonucleases were used to investigate the mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) of 11 native cattle breeds and one cultivated cattle breed in South China. Twenty-three restriction morphs were detected, which can be sorted into five haplotypes. A phylogenetic tree of the haplotypes was constructed by using the 'upgMa' method. Our study showed that haplotype I and II are identical to the zebu (Bos indicus) and taurine (Bos taurus) haplotypes, respectively. Zebu and taurine were the two major origins of cattle populations in South China, and the zebu probably had more influence on the native cattle population than taurine did. Haplotype III is identical to haplotype I of yak (Bos grunniens), which was only detected in the Diqing cattle breed. Haplotype IV was detected for the first time. This haplotype, found only in Dehong cattle, might be from an independent domestication event, probably from another Bos indicus population. Divergence of haplotypes I and IV occurred about 268,000-535,000 years ago, much earlier than the 10,000-year history of cattle husbandry. Our results also suggest a secondary introgession of mtDNA from yak to Diqing cattle.

Isolation and characteristics of autoreactive T cells specific to aggrecan G1 domain from rheumatoid arthritis patients

Our previous work showed that the cartilage proteoglycan aggrecan could induce an erosive polyarthritis and spondylitis in BALB/c mice and the G1 globular domain of the aggrecan (G1) contained the arthritogenic region. To elucidate whether autoreactive T cells to G1 are expressed in rheumatoid arthritis patients, we analyzed the frequency of human G1-specific T cells in the peripheral blood of five rheumatoid arthritis patients and tried to establish G1-reactive T cell lines from these rheumatoid arthritis patients. The results showed that the G1-specific T cells in PBL were detectable at the range of 4.97 +/- 0.5 x 10(-6) in peripheral blood lymphocytes. We have also generated 15 G1-specific T lymphocyte lines from these patients with a standard split-well method. All these cells expressed fine specificity to human recombinant G1, but not to unrelated antigen. All the 15 lines expressed a pan-T cell marker and 13 of them selectively used the alphabeta T cell receptor. Two of them used gammadelta T cell receptor. The 13 of these T cell lines was CD4 positive. One line expressed CD8. One line expressed both CD4 and CD8. Moreover, 14 out of 15 lines expressed the Th-1 cytokine profile, characterized by interferon-gamma positivity and IL-4 negativity. No Th-2 type cell line was generated. These data provide strong evidence in favor of the presence of autoreactive T cells in the rheumatoid arthritis patients. What is the mechanism(s) that these autoreactive T cells attack self-target and whether these G1-specific, Th-1 type T cell lines can induce arthritis in immune deficiency mice are currently under investigation.

Adaptive evolution of the mitochondrial ND6 gene in the domestic horse

Mitochondria play a crucial role in energy metabolism through oxidative phosphorylation. Organisms living at high altitudes are potentially influenced by oxygen deficits and cold temperatures. The severe environmental conditions can impact on metabolism and direct selection of mitochondrial DNA. As a wide-ranging animal, the domestic horse (Equus caballus) has developed various morphological and physiological characteristics for adapting to different altitudes. Thus, this is a good species for studying adaption to high altitudes at a molecular level. We sequenced the complete NADH dehydrogenase 6 gene (ND6) of 509 horses from 24 sampling locations. By comparative analysis of three horse populations living at different altitudes (>2200 m, 1200-1700 m, and <900 m), we found that the high-altitude population had the lowest genetic diversity and significant negative Tajima's D; both values declined with increasing elevation. Moreover, non-directional selection was identified for the ND6 gene by a tree-based relative ratio test (P = 0.007); the highest proportion of high-altitude horses was found distributed on the selected branches. We conclude that the high-altitude environment has directed adaptive evolution of the mitochondrial ND6 gene in the plateau horse.

Development, characterization and application of predictive-toxicology models

The adoption of SAR techniques for risk assessment purposes requires that the predictive performance of models be characterized and optimized. The development of such methods with respect to CASE/MULTICASE are described. Moreover, the effects of size, informational content, ratio of actives/inactives in the model on predictivity must be determined. Characterized models can provide mechanistic insights: nature of toxicophore, reactivity, receptor binding. Comparison of toxicophores among SAR models allows a determination of mechanistic overlaps (e.g., mutagenicity, toxicity, inhibition of gap junctional intercellular communication vs. carcinogenicity). Methods have been developed to combine SAR submodels and thereby improve predictive performance. Now that predictive toxicology methods are gaining acceptance, the development of Good Laboratory Practices is a further priority, as is the development of graduate programs in Computational Toxicology to adequately train the needed professional.