Lower median nerve block impairs precision grip.

The purpose of this study was to investigate precision grip impairment caused by a lower median nerve block at the wrist. The median nerve block was achieved by injecting bupivacaine hydrochloride into the carpal tunnel, which acutely simulated a median neuropathy. Seven healthy male subjects were instructed to grip, lift, and hold an instrumented handle within 60s using precision grip. The same tasks were performed before and after the nerve block. Force and torque data were recorded using two miniature 6-component force/torque transducers. The precision grip was quantified by the safety margin (i.e. the difference between the actual grip force and the minimal grip force to keep the object from dropping), the variation of grip force, and the migration area of center of pressure (i.e. the area defined by the center of pressure at a digit-transducer surface while holding the handle). Two subjects were unable to complete the precision grip tasks after the nerve block, and their data were excluded from the analyses. The median nerve block caused significant increases (P<0.05) in the safety margin of the grip force (>50%), the grip force variation (>80%), and the area of center of pressure migration (>250%). Median nerve block at the wrist impairs the fine motor control during precision grip. Our results corroborate the important role played by sensory function in hand fine motor control. Clinically, the measures related to precision grip have the potential to quantify impairment of hand function caused by neuromuscular disorders, to monitor the progress of a hand disorder, and to evaluate the efficacy of a treatment or rehabilitation procedure.     

Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Effects of solution polarity and viscosity on peptide deamidation.

Deamidation kinetics were measured for a model hexapeptide (L-Val-L-Tyr-L-Pro-L-Asn-Gly-L-Ala, 0.02 mg/mL) in aqueous solutions containing glycerol (0-50% w/w) and poly(vinyl pyrrolidone) (PVP, 0-20% w/w) at 37 degrees C and pH 10 to determine the effects of solution polarity and viscosity on reactivity. The observed pseudo-first order deamidation rate constants, k(obs), decreased markedly when the viscosity increased from 0.7 to 13 cp, but showed no significant change at viscosities >13 cp. Values of k(obs) also increased with increasing dielectric constant and decreasing refractive index. Molecular dynamics simulations indicated that the free energy associated with Asn side-chain motion is insensitive to changes in dielectric constant, suggesting that the observed dielectric constant dependence is instead related primarily to the height of the transition state energy barrier. An empirical model was proposed to describe the effects of the viscosity, refractive index and dielectric constant on k(obs). Analysis of the regression coefficients suggested that both permanent and induced dipoles of the medium affect the deamidation rate constant, but that solution viscosity is relatively unimportant in the range studied.     

BJ-HCC-20, a potential novel cancer-testis antigen.

In an effort to identify novel Cancer-Testis genes, we analyzed the sequence in the q26-28 region of human X chromosome by several on-line tools. The candidate sequences were then confirmed by experiments. We have obtained a novel Cancer-Testis gene, BJ-HCC-20. In vivo, it was found to have two isoforms. In samples of liver, colon, gastric and lung cancer tested, the expression frequency of BJ-HCC-20 is 25%, 17%, 21% and 15%, respectively. Full-length cDNAs of both BJ-HCC-20 isoforms were isolated and their gene structures and promoter regions were characterized. BJ-HCC-20 might have implications in theoretical and practical tumor biology.     

不同海拔地区种植的水稻地上部干物质的生产和分配

根据1983—1985年“高原水稻高产栽培的生理生态规律研究”中低热的元江(海拔400米左右)、温凉的昆明(约1900米)和冷凉的丽江(约2400米)的资料,以六个处理、十八个小区、三年总平均值,比较了不同海拔地区种植的水稻中地上部干物质生产和分配的总趋势。主要结果如下: 1.全生育期总的干物质生产量以温凉地区最高,低热地区居中,冷凉地区最低。 2.抽穗前干物质生产速率和齐穗期干物重占黄熟期干物重的比例随海拔降低而增加;抽穗期至黄熟期干物质生产速率,以温凉地区最高,低热地区居中,冷凉地区最低,但低热地区低于前期,高海拔地区高于前期,不过冷凉的丽江增加的更多。 3.抽穗前(旗叶完全展开后)叶干重占当时植株总干重的比例,随海拔升高而降低。 4.抽穗期至黄熟期的次库(茎 叶鞘)干重的改变,不同海拔地区种植的水稻表现不同:低热地区减重,温凉地区稍增,冷凉地区明显增加。 5.与高海拔地区种植的水稻相比,在黄熟期低海拔地区的有较高的穗重/总重和穗增重/总增重的比例。另外低海拔地区的穗增重超过总增重。结实率和谷/草比例均随海拔增高而减低。     

Estrogen carcinogenesis in Syrian hamster tissues: role of metabolism

Evidence for a role of estrogen metabolism in hormonal carcinogenesis was obtained with the Syrian hamster as an in vivo model system. Both natural and synthetic estrogens are capable of inducing a high incidence of renal carcinomas in this species. A high incidence of hepatocellular carcinomas can also be induced in the hamster with synthetic estrogens such as ethinyl estradiol or diethylstilbestrol, provided alpha-naphthoflavone (ANF) is present in the diet. Although steroid receptor-mediated hormonal events appear to be intimately involved in the process of in vivo cell transformation of both tissues, certain observations strongly suggest that nonhormonal events are also important. Despite their potent estrogenic activity at the doses used, ethinyl estradiol and alpha-zearalanol induce relatively low renal tumor incidences after 9.0 and 10.0 months of continuous treatment, respectively. A role for the metabolism of estrogens to reactive intermediates is also suggested by studies showing estrogen-induced renal tumorigenesis can be partially inhibited by concomitant administration of ANF or ascorbic acid. Consistent with this is the general correlation between the amount of catechol estrogen formed by a compound, as mediated by estrogen 2-/4-hydroxylase, and renal carcinogenicity data. Recently, additional supporting evidence has been obtained from studies involving the irreversible binding of reactive metabolites of steroidal or stilbene estrogens to hamster liver microsomal proteins.     

Comparison of the tissue-specific expression and developmental regulation of two closely linked rodent genes encoding cytosolic retinol-binding proteins

Cellular retinol-binding protein (CRBP) and cellular retinol-binding protein II (CRBP II) are two highly homologous cytoplasmic proteins that bind all-trans-retinol. We have recently demonstrated that the mouse genes encoding CRBP and CRBP II are closely linked on chromosome 9 and that both human genes are located on chromosome 3 (Demmer, L.A., Birkenmeier, E.H., Sweetser, D.A., Levin, M.S., Zollman, S., Sparkes, R.S., Mohandas, T., Lusis, A.J., and Gordon, J.I. (1987) J. Biol. Chem. 262, 2458-2467). We have now used RNA blot hybridization analysis to assess the degree to which these genes are coordinately expressed in fetal, suckling, weaning, and adult rat tissues. Both genes exhibit different developmental patterns of expression in liver, intestine, lung, kidney, testes, and placenta. In the intestine, CRBP mRNA was detected during the 16th day of gestation--prior to the development of a well-differentiated absorptive epithelium--and remained essentially unchanged throughout the peri- and postpartum periods. By contrast, the pattern of intestinal CRBP II mRNA accumulation closely parallels the times of first appearance, and subsequent proliferation, of the intestinal absorptive columnar epithelium, supporting the hypothesis that CRBP II is involved in the intestinal uptake or intracellular trafficking of this hydrophobic vitamin. In the fetal liver, both genes were expressed by gestational day 16. Whereas the concentration of hepatic CRBP mRNA increased markedly during the suckling and early weaning periods, CRBP II mRNA levels fell abruptly immediately after birth. These peripartum changes were not paralleled by remarkable alterations in the steady state levels of hepatic retinol. Marked changes in the expression of CRBP in the liver and of CRBP II in the intestine were also documented in pregnant and lactating female rats. These differences in CRBP/CRBP II gene expression strongly suggest that their proteins serve different physiological functions. The peripartum liver may provide a useful model for dissecting the relative roles played by these homologous proteins in retinoid metabolism as well as the factors which modulate activation and repression their genes.     

Influx of 5'-deoxy-5'-methylthioadenosine into HL-60 human leukemia cells and erythrocytes

The influx of 5'-deoxy-5'-methylthioadenosine (MeSAdo) into human HL-60 leukemia cells and erythrocytes was characterized in order to determine whether it is facilitated by the nonspecific nucleoside carrier system or by a separate transporter, as suggested by other reports. Initial velocities were measured at room temperature by means of inhibitor-stop and oil-stop assays. MeSAdo influx was strongly inhibited by Ado, dAdo, and nucleoside transport inhibitors including nitrobenzylthioinosine and dipyridamole. Ade was inhibitory only at concentrations in excess of 1 mM. Loss of nucleoside transport capacity during differentiation of HL-60 cells was accompanied by a corresponding decrease in MeSAdo influx rates. These results indicate that MeSAdo influx was mediated by the nonspecific nucleoside transport system. The kinetic data were consistent with a single saturable carrier and yielded Km values of 74 and 184 microM and Vmax values of 424 and 48 pmols/10(6) cells/min with HL-60 cells and erythrocytes, respectively, after correction for a substantial passive diffusion component, which accounted for over 50% of the influx of 1 mM MeSAdo. The passive diffusion of MeSAdo in the presence of a transport inhibitor was not rate-limiting for the salvage of 50 microM MeSAdo to methionine when HL-60 cells were cultured in methionine-deficient medium. The large contribution of passive diffusion to the influx of MeSAdo is consistent with its unusually high octanol/water partition ratio (5.7-fold greater than that of Ado).     

A genetical model for emergenesis: in memory of Laurence H. Snyder, 1901-86.

When a phenotype is determined by a specific gene combination of several loci, it is called an emergenic trait. Such a trait, although genetically controlled, does not usually run in families, since the specific gene combination can hardly be preserved in the process of reproduction. The present paper suggests a concrete genetical model to account for the phenomenon that there is little resemblance between siblings and parent-child pairs with respect to this trait. The genetical model is multiple homozygosis for all loci involved in the gene configuration. The properties of such a trait in a random mating population for all families, as well as for the segregating families only, are investigated. Some of the difficulties in estimating the genetical parameters on the basis of empirical data are also discussed.