[Distribution specificity of human fucosyltransferase 5 and its expression and localization in spermatids]

OBJECTIVE

To investigate distribution specificity of human fucosyltransferase 5 (FUT5) as well as its expression and localization in spermatids.

METHODS

Human semen, vaginal swab, saliva and venous blood from healthy individuals were collected. The spermatids were isolated and the spermatid membrane protein was then extracted. Expression levels of FUT5 from human spermatid membrane, seminal plasma, vaginal fluid, saliva and serum were detected by immunoblotting technique. The expression and localization of FUT5 in spermatids were analyzed by immunofluorescent method.

RESULTS

Immunoblotting technique showed that FUT5 was expressed on spermatid membranes and in serum, but not in seminal plasma, vaginal fluid and saliva. The expressed FUT5 on spermatids was mostly localized on head of spermatids by fluorescent microscopy, suggesting that there was certain amount of FUT5 on human spermatid membrane, and the spermatids might be isolated from mixed stains with vaginal fluid by antigen-antibody reaction.

CONCLUSION

Human FUT5 shows a characteristic distribution specificity, and this feature may be used for identification of mixed stain involved in criminal sexual offence in future forensic practice.

Optimally enhanced optical emission in laser-induced breakdown spectroscopy by combining spatial confinement and dual-pulse irradiation

In laser-induced breakdown spectroscopy (LIBS), a pair of aluminum-plate walls were used to spatially confine the plasmas produced in air by a first laser pulse (KrF excimer laser) from chromium (Cr) targets with a second laser pulse (Nd:YAG laser at 532 nm, 360 mJ/pulse) introduced parallel to the sample surface to re-excite the plasmas. Optical emission enhancement was achieved by combing the spatial confinement and dual-pulse LIBS (DP-LIBS), and then optimized by adjusting the distance between the two walls and the interpulse delay time between both laser pulses. A significant enhancement factor of 168.6 for the emission intensity of the Cr lines was obtained at an excimer laser fluence of 5.6 J/cm(2) using the combined spatial confinement and DP-LIBS, as compared with an enhancement factor of 106.1 was obtained with DP-LIBS only. The enhancement mechanisms based on shock wave theory and reheating in DP-LIBS are discussed.

Stress and phase purity analyses of diamond films deposited through laser-assisted combustion synthesis

Diamond films were deposited on silicon and tungsten carbide substrates in open air through laser-assisted combustion synthesis. Laser-induced resonant excitation of ethylene molecules was achieved in the combustion process to promote diamond growth rate. In addition to microstructure study by scanning electron microscopy, Raman spectroscopy was used to analyze the phase purity and residual stress of the diamond films. High-purity diamond films were obtained through laser-assisted combustion synthesis. The levels of residual stress were in agreement with corresponding thermal expansion coefficients of diamond, silicon, and tungsten carbide. Diamond-film purity increases while residual stress decreases with an increasing film thickness. Diamond films deposited on silicon substrates exhibit higher purity and lower residual stress than those deposited on tungsten carbide substrates.

Enhancement of optical emission from laser-induced plasmas by combined spatial and magnetic confinement

To enhance optical emission in laser-induced breakdown spectroscopy, both a pair of permanent magnets and an aluminum hemispherical cavity (diameter: 11.1 mm) were used simultaneously to magnetically and spatially confine plasmas produced by a KrF excimer laser in air from pure metal and alloyed samples. High enhancement factors of about 22 and 24 in the emission intensity of Co and Cr lines were acquired at a laser fluence of 6.2 J/cm2 using the combined confinement, while enhancement factors of only about 11 and 12 were obtained just with a cavity. The mechanism of enhanced optical emission by combined confinement, including shock wave in the presence of a magnetic field, is discussed. The Si plasmas, however, were not influenced by the presence of magnets as Si is hard to ablate and ionize and hence has less free electrons and positive ions. Images of the laser-induced Cr and Si plasmas show the difference between pure metallic and semiconductor materials in the presence of both a cavity and magnets.

Fast growth of branched nickel monosilicide nanowires by laser-assisted chemical vapor deposition

Branched nickel monosilicide (NiSi) nanowires (NWs), for the first time, have been synthesized on Ni foams by laser-assisted chemical vapor deposition using disilane precursor molecules. Studies indicate that 600 °C is the threshold temperature for the growth of a large number of branched NiSi NWs with 100-500 nm long branches extending from the main stems. Below the threshold temperature, unbranched NiSi NWs were obtained. The density of the branched NiSi NWs is relatively higher in comparison to that of the unbranched ones. The growth rate of the branched NiSi NWs at 700 °C is estimated up to 10 µm min(-1). High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy of the branched NiSi NWs suggest that the formation of these branched nanostructures is ascribed to the Ni-dominant diffusion process. These NiSi NWs with branched nanostructures could bring them new opportunities in nanodevices.

Resonant excitation of precursor molecules in improving the particle crystallinity, growth rate and optical limiting performance of carbon nano-onions

A catalyst-free and highly efficient synthetic method for growing carbon nano-onions (CNOs) in open air has been developed through the laser resonant excitation of a precursor molecule, ethylene, in a combustion process. Highly concentric CNO particles with improved crystallinity were obtained at a laser wavelength of 10.532 µm through the resonant excitation of the CH(2) wagging mode of the ethylene molecules. A higher growth rate up to 2.1 g h( - 1) was obtained, compared with that without a laser (1.3 g h( - 1)). Formation of the CNOs with ordered graphitic shells is ascribed to the decomposition of polycyclic aromatic hydrocarbons (PAHs) into C(2) species. The optical limiting performances of the CNOs grown by the combustion processes were investigated. CNOs grown at 10.532 µm laser excitation demonstrated improved optical limiting properties due to the improved crystallinity.

Diameter modulation by fast temperature control in laser-assisted chemical vapor deposition of single-walled carbon nanotubes

Diameter modulation by fast temperature control in laser-assisted chemical vapor deposition (LCVD) was successfully achieved to tune the diameters of single-walled carbon nanotubes (SWNTs) in different segments. Due to the inverse relationship between the SWNT diameter and the growth temperature, SWNTs with ascending diameters were obtained by reducing the LCVD temperature from high to low. The diameter-modulated SWNTs were integrated in electrodes to form field-effect transistors (FETs) and to investigate their electronic transport properties. The SWNTs in the FET structures have electronic properties similar to Schottky diodes, indicating clear evidence of different bandgap structures at the two ends of the SWNTs. Raman spectroscopy, transmission electron microscopy, and electronic transport characteristics were studied to investigate the influence of temperature variation on the structural and electronic characteristics of the SWNTs.

Optical and field-emission properties of ZnO nanostructures deposited using high-pressure pulsed laser deposition

ZnO nanostructures were deposited on GaN (0001), Al2O3 (0001), and Si (100) substrates using a high-pressure pulsed laser deposition (PLD) method. Vertically aligned hexagonal-pyramidal ZnO nanorods were obtained on the Al2O3 and Si substrates whereas interlinked ZnO nanowalls were obtained on the GaN substrates. A growth mechanism has been proposed for the formation of ZnO nanowalls based on different growth rates of ZnO polar and nonpolar planes. Both ZnO nanorods and nanowalls exhibit a strong E2H vibration mode in the micro-Raman spectra. The corresponding fluorescence spectra of ZnO nanorods and nanowalls showed near band emission at 3.28 eV. The ZnO nanorods grown on the Si substrates exhibited better crystalline and optical properties compared with the ZnO structures grown on the GaN and Al2O3 substrates. The high aspect ratio, good vertical alignment, and better crystallinity of the ZnO nanorods with tapered tips exhibited promising field emission performance with a low turn-on field of 2 V/μm, a high current density of 7.7 mA/cm2, and a large field enhancement factor.

Towards carbon-nanotube integrated devices: optically controlled parallel integration of single-walled carbon nanotubes

Where it starts and where it goes? Controlled integration of single-walled carbon nanotubes (SWNTs) into pre-designed nano-architectures is one of the major challenges to be overcome for extensive scientific research and technological applications. Various serial assembly techniques have been proposed and developed. However, they are still a long way from practical applications due to the drawbacks on reliability, yield and cost. Here we demonstrate a laser-based strategy to achieve parallel integration of SWNTs into pre-designed nano-architectures through an optically controlled in situ growth process. Optical driving forces originated from tip-induced optical near-field enhancement and laser beam polarization were applied in this study to realize the controlled placement of SWNTs at designated sites following wanted orientations on the nanometer scale. Parallel integration of SWNT arrays was achieved by adjusting laser beam diameter to cover interested nano-architectures. The laser-based process suggests an efficient and cost-effective approach for fabricating and integrating SWNT-based devices and circuits.

Laser induced selective removal of metallic carbon nanotubes

Distinguishing between carbon nanotubes (CNTs) according to their individual electronic properties is of significant importance for developing CNT-based electronics and devices. In this study, selective removal of metallic CNTs from CNT mixtures on silicon substrates was investigated using controlled laser irradiation. Free electron movement and eddy currents are induced within the metallic CNTs by the strong electric field and optical near-field effects caused by the laser irradiation. Selective heating of metallic CNTs in air results in selective removal of metallic CNTs when the laser fluence and wavelength are properly selected. Through this process, metallic nanotubes are successfully removed from the CNT mixtures. This technique provides an efficient single-step approach for selective removal of metallic CNTs from CNT mixtures.

An ab initio study of the interaction between an iron atom and graphene containing a single Stone-Wales defect

The interaction between an iron atom and graphene containing a single Stone-Wales (SW) defect has been investigated by ab initio density functional calculations. The top site on the core defective bond-rotated carbon atom turns out to be the most favorable for iron atom adsorption. The local magnetic moment of the iron atom is 2.24  μ(B) in this adsorbed system, and it can be interpreted by an effective Fe 3d(8)4s(0) configuration caused by the strong interaction between the adatom and the core defective bond-rotated carbon atom. The defect minimizes the binding energy with respect to the adsorption of iron atoms on defect-free graphene and consequently makes the adsorbed systems more stable. Additionally, the adsorption of iron atoms on the defective graphene induces the adsorbed structures to be distorted evidently along the direction perpendicular to the graphene sheet. In particular, the band structures of these adsorbed systems, with some spin-polarized gap states lying between the π and π(*) bands, are modulated by Fe 3d states in the vicinity of the Fermi level, and the gap between the valence band maximum and conduction band minimum is decreased to almost zero due to the interaction of Fe 3d states with C 2p states.

Self-aligned growth of single-walled carbon nanotubes using optical near-field effects

Self-aligned growth of ultra-short single-walled carbon nanotubes (SWNTs) was realized by utilizing optical near-field effects in a laser-assisted chemical vapor deposition (LCVD) process. By introducing the optical near-field effects, bridge structures containing single suspended SWNT channels were successfully fabricated through the LCVD process at a relatively low substrate temperature. Raman spectroscopy and I-V analyses have been carried out to characterize the SWNT-bridge structures. Numerical simulations using a high-frequency structure simulator revealed that significant enhancement of local heating occurs at metallic electrode tips under laser irradiation; it is about one order of magnitude higher than that in the rest of the electrodes. This technique suggests a novel approach to in situ low-temperature fabrication of SWNT-based devices in a precisely controlled manner, based on the nanoscale heating enhancement induced by the optical near-field effects.

Tip-enhanced near-field Raman spectroscopy with a scanning tunneling microscope and side-illumination optics

Conventional Raman spectroscopy (RS) suffers from low spatial resolution and low detection sensitivity due to the optical diffraction limit and small interaction cross sections. It has been reported that a highly localized and significantly enhanced electromagnetic field could be generated in the proximity of a metallic tip illuminated by a laser beam. In this study, a tip-enhanced RS system was developed to both improve the resolution and enhance the detection sensitivity using the tip-enhanced near-field effects. This instrument, by combining RS with a scanning tunneling microscope and side-illumination optics, demonstrated significant enhancement on both optical sensitivity and spatial resolution using either silver (Ag)-coated tungsten (W) tips or gold (Au) tips. The sensitivity improvement was verified by observing the enhancement effects on silicon (Si) substrates. Lateral resolution was verified to be below 100 nm by mapping Ag nanostructures. By deploying the depolarization technique, an apparent enhancement of 175% on Si substrates was achieved. Furthermore, the developed instrument features fast and reliable optical alignment, versatile sample adaptability, and effective suppression of far-field signals.

Increased glycophorin A somatic cell variant frequency in arsenic-exposed patients of Guizhou, China

Exposure to arsenic through domestic burning arsenic-containing coal causes various tumors in a population of Guizhou, China. The glycophorin A (GPA) assay is a human mutation assay detecting somatic variation in erythrocytes expressing the MN blood type, and was used to assess genotoxicity of arsenic-exposed patients. Peripheral blood was collected from 18 adult healthy subjects and 40 arsenic-exposed patients in heparin-treated tubes. Erythrocytes were isolated, fixed in formalin and immuno-labeled with fluorescent antibodies against GPA, followed by flow cytometry analysis. Arsenic exposure increased the variant frequency (expressed as the number of variant red cells per 10(6) erythrocytes): NN, 3.7 in healthy subjects versus 21.2 in arsenic-exposed patients; N phi, 12.6 versus 33.1; MM, 13.1 versus 110; and M phi, 5.2 versus 20.3. The total GPA variant frequency was increased about five-fold (34.7 in healthy subjects versus 185 in arsenosis patients). Furthermore, the variant frequency was significantly higher in skin tumor-bearing patients: NN, 19.4 in arsenic-exposed non-tumor patients versus 31.5 in tumor-bearing patients; N phi, 29.5 versus 54.5; MM, 102 versus 159; M phi, 15.9 versus 45.1. Total GPA variant frequency in arsenic-exposed patients bearing skin tumors was significantly increased compared to patients without skin tumors (167 versus 290). The relationship between arsenic exposure history and GPA variant frequency was less evident. These data demonstrate that arsenic exposure is associated with mutations at the GPA locus, an effect exaggerated in patients bearing arsenic-induced skin tumors. The variant frequency of GPA could be a useful biomarker for arsenic exposure and arsenic carcinogenesis.

A new medical microrobot for minimal invasive surgery

A new medical microrobot to drive endoscopes into endocoeles is presented. The structure of the microrobot is very simple; it consists of a right spirally grooved micromotor, a left spirally grooved cylinder and a flexible coupling. When the micromotor rotates, a hydrodynamic mucus film is formed because highly viscous mucus exists in endocoeles. The mucus film can prevent direct contact between the microrobot and the endocoele, and the injury to organic tissues may be avoided. The locomotion speed and the hydrodynamic mucus film thickness formed when the microrobot drives endoscopes into endocoeles have been calculated according to hydrodynamic lubrication theory. The results indicate that the microrobot can be suspended to drive endoscopes quickly into endocoeles. This has been confirmed by experiments.

Application of cDNA microarray to the study of arsenic-induced liver diseases in the population of Guizhou, China

Arsenic is an environmental toxicant and a human carcinogen. Epidemiology studies link human arsenic exposure to various diseases and cancers, including liver diseases and hepatocellular carcinoma. However, the molecular mechanisms for arsenic toxicity and carcinogenicity are poorly understood. To better understand these mechanisms, we used the human cancer cDNA expression array to profile aberrant gene expression in arsenic-exposed populations in Guizhou, China. The selected patients had a history of exposure to environmental arsenic for at least 6-10 years, and had arsenic-induced skin lesions and hepatomegaly. Samples were obtained by liver needle biopsy. Histology showed degenerative liver lesions, such as chronic inflammation, vacuolation, and focal necrosis. The University of North Carolina Hospitals provided normal human liver tissues from surgical resection or rejected transplants. Microarray was performed with total RNA from liver samples, and signal intensities were analyzed with AtlasImage software and normalized with 9 housekeeping genes. Means and SEM were calculated for statistical analysis. Approximately 60 genes (10%) were differentially expressed in arsenic-exposed human livers compared to controls. The differentially expressed genes included those involved in cell-cycle regulation, apoptosis, DNA damage response, and intermediate filaments. The observed gene alterations appear to be reflective of hepatic degenerative lesions seen in the arsenic-exposed patients. This array analysis revealed important patterns of aberrant gene expression occurring with arsenic exposure in human livers. Aberrant expressions of several genes were consistent with the results of array analysis of chronic arsenic-exposed mouse livers and chronic arsenic-transformed rat liver cells. Clearly, a variety of gene expression changes may play an integral role in arsenic hepatotoxicity and possibly carcinogenesis.

Cimetidine absorption and elimination in rat small intestine

The purpose of this study was to determine the characteristics of intestinal absorption and metabolism of cimetidine. The initial finding of the appearance of cimetidine sulfoxide in rat and human jejunum from cimetidine perfusions had prompted an isolation of mucosal membrane transport and enterocyte metabolism contributions in earlier membrane vesicle and microsomal studies, respectively. In this report, perfusion studies in rat small intestine detail regional differences in intestinal elimination. Cimetidine S-oxide appears to a significantly greater extent in the jejunum compared with the ileum. Jejunal metabolite appearance is shown to be a function of the pH-dependent intracellular uptake of cimetidine. Cimetidine permeability decreases with increasing perfusion concentration in both jejunum and ileum. Similar permeability magnitudes and concentration dependence are observed in both regions. Perfusion studies with inhibitors of cimetidine mucosal transport and inhibitors of microsomal S-oxidation provide an inhibition profile suggesting that jejunal cimetidine permeability decreases with increasing intracellular cimetidine concentration. The data support a reduction in paracellular cimetidine absorption as controlled by intracellular cimetidine. This inference is drawn on the basis of mass balance. Because significant appearance of cimetidine S-oxide was previously found in human jejunal perfusions, this region-dependent intestinal elimination process detailed in rats may be relevant to drug plasma-level double peaks observed in clinical studies. Saturation of jejunal metabolism at typical oral doses may limit paracellular absorption of cimetidine in the jejunum and contribute to the double peak phenomenon and to absorption variability.

[Two-site absorption model fits to pharmacokinetic data of gemfibrozil in man]

The plasma concentration-time data of gemfibrozil in 8 male subjects were determined after an oral dose of 600 mg. Two-peak concentrations in plasma were observed. A kind of one-compartment model with two-sites of drug absorption was proposed and used to fit these data. A good agreement between observed and predicted data was found in all subjects with correlation indexes (gamma 2) > 0.99. The corresponding pharmacokinetic parameters were estimated as follows: Tmax1, 1.10 +/- 0.46 h; Tmax2, 2.60 +/- 0.73 h; Cmax1, 13.62 +/- 4.30 micrograms.ml-1; Cmax2, 17.22 +/- 3.83 micrograms.ml-1; T1, 0.06 +/- 0.06 h; T2, 1.42 +/- 0.57 h and T3, 1.79 +/- 0.60 h.

[Pharmacokinetic and electocardiographic study of oral verapamil sustained-release tablet in 10 Chinese volunteers]

Both verapamil pharmacokinetics and electrocardio graphic changes in 10 Chinese volunteers were studied after po 240 mg of verapamil sustained release tablet. A one-compartment model with zero-order absorption gave a better fitting to concentration--time data with values of r2 > 0.96. The main pharmacokinetic parameters obtained were: Tmax, 5.9 +/- 1.6 h; Cmax, 118.9 +/- 37.2 micrograms.L-1; T1, 5.4 +/- 1.5 h; k0, 30.5 +/- 17.5 micrograms.L-1.h-1; T1/2, 10.8 +/- 4.9 h; MRT, 15.4 +/- 3.2 h and AUC. 1.96 +/- 0.82 mg.h.L-1. There were significant prolongations of PR intervals after dose. Relationships between PR interval changes and plasma concentrations of verapamil were better fitted to sigmoidal model, with r2 > 0.98. The corresponding pharmacodynamic parameters were estimated. EC50, 64.6 +/- 16.9 micrograms.L-1, Emax, 54 +/- 11 ms and s, 1.68 +/- 0.66.

Monocytes and tissue factor promote thrombosis in a murine model of oxygen deprivation

Clinical conditions associated with local or systemic hypoxemia can lead to prothrombotic diatheses. This study was undertaken to establish a model of whole-animal hypoxia wherein oxygen deprivation by itself would be sufficient to trigger tissue thrombosis. Furthermore, this model was used to test the hypothesis that hypoxia-induced mononuclear phagocyte (MP) recruitment and tissue factor (TF) expression may trigger the local deposition of fibrin which occurs in response to oxygen deprivation. Using an environmental chamber in which inhaled oxygen tension was lowered to 6%, hypoxic induction of thrombosis was demonstrated in murine pulmonary vasculature by 8 h based upon: (a) immunohistologic evidence of fibrin formation in hypoxic lung tissue using an antifibrin antibody, confirmed by 22.5-nm strand periodicity by electron microscopy; (b) immunoblots revealing fibrin gamma-gamma chain dimers in lungs from hypoxic but not normoxic mice or hypoxic mice treated with hirudin; (c) accelerated deposition of 125I-fibrin/fibrinogen and 111In-labeled platelets in the lung tissue of hypoxic compared with normoxic animals; (d) reduction of tissue 125I-fibrin/fibrinogen accumulation in animals which had either been treated with hirudin or depleted of platelets before hypoxic exposure. Because immunohistochemical analysis of hypoxic pulmonary tissue revealed strong MP staining for TF, confirmed by increased TF RNA in hypoxic lungs, and because 111In-labeled murine MPs accumulated in hypoxic pulmonary tissue, we evaluated whether recruited MPs might be responsible for initiation of hypoxia-induced thrombosis. This hypothesis was supported by several lines of evidence: (a) MP depletion before hypoxia reduced thrombosis, as measured by reduced 125I-fibrin/fibrinogen deposition and reduced accumulation of cross-linked fibrin by immunoblot; (b) isolated murine MPs demonstrated increased TF immunostaining when exposed to hypoxia; and (c) administration of an anti-rabbit TF antibody that cross-reacts with murine TF decreased 125I-fibrin/fibrinogen accumulation and cross-linked fibrin accumulation in response to hypoxia in vivo. In summary, these studies using a novel in vivo model suggest that MP accumulation and TF expression may promote hypoxia-induced thrombosis.

Serum tumor necrosis factor (TNF) in the pathogenesis of clinical hepatic failure of HCV and/or HBV infection

Serum TNF and IL-6 levels were measured in 48 patients with liver disease positive for anti-HCV only or concurrent HBV infection. High serum TNF levels were observed in patients with liver disease positive for anti-HCV and/or HBV infection (P < 0.001). Serum TNF levels varied with the severity of liver disease. Serum TNF levels of anti-HCV positive patients with hepatic failure were higher than those with CAH (P < 0.01). Serum TNF levels of patients infected with HCV or concurrent HBV were also significantly higher than those with HBV infection alone (P < 0.001). However, no difference in serum IL-6 levels was observed in either group of patients. Serum TNF in the deceased patients with hepatic failure induced by HBV and HCV infection was higher than in those who survived (P < 0.05), and it also seemed significantly different in patients with and without multiple organ failure (P < 0.05). In vitro, HSS showed marked inhibitory activity on TNF production from PBM induced by endotoxin, but had no significant effect on the TNF cytotoxicity of L929 cells. It seems that high serum TNF level is an important mediator in the pathogenesis of liver necrosis and failure of microcirculation in HCV and/or HBV infection. These observations favor the attempt to treat hepatic failure with HSS or anti-TNF. Encouraging results were achieved using HSS in the treatment of subacute liver necrosis in our institute.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of intrahippocampal injection of 6-OHDA on acquisition and retention of avoidance response in rats]

The role of hippocampal noradrenergic and dopaminergic transmission in the acquisition and retention of active conditioned avoidance behavior was investigated in rats by injection of 6-hydroxydopamine (6-OHDA) into dorsal hippocampus. The main results are as follows: (1) After injection of 6-OHDA the contents of dopamine, particularly norepinephrine (P < 0.01) in the hippocampus was decreased significantly. (2) The acquisition of conditioned avoidance behavior was markedly impaired. (3) The facilitating effect of AVP on retention of active conditioned avoidance behavior could be eliminated by prior injection of 6-OHDA bilaterally into hippocampus.

Prevalence of antibodies to hepatitis C virus in Chinese patients with viral hepatitis and hepatic failure

Anti-HCV assay with ORTHO kits was done in 100 blood donors and recipients and 374 cases of viral hepatitis, including 65 cases of fulminant, subacute and chronic hepatic failure. None of the 100 blood donors and recipients showed positive anti-HCV response. Anti-HCV was positive in 7.6% of the patients with chronic persistent hepatitis, 9.7% of the patients with chronic active hepatitis and 23.1% of the patients with liver cirrhosis. High prevalence of anti-HCV was observed in subacute hepatic failure (60.8%) and chronic hepatic failure (53.9%). Fifty-two (83.9%) of 62 anti-HCV positive cases were infected concurrently with HBV. The incidence of HBV replicating marker in patients with HCV or co-infected with HBV was lower than that of those with HBV alone. It is suggested that HCV might inhibit the replication of hepatitis B virus. The mortality rate of patients with anti-HCV positive hepatic failure was higher than that of those with HBV infection. Therefore, anti-viral therapy for anti-HCV positive hepatic failure should be considered.

[Effect of hippocampal injection of oxytocin on shuttle-box avoidance behavior of rats]

Bilateral dorsal hippocampal injection of oxytocin (Oxy, 50 pg, on each side) in rats impaired the acquisition of conditioned avoidance behavior and accelerated the extinction of conditioned avoidance behavior in shuttle-box. The data suggested that the effect of Oxy on shuttle-box conditioned avoidance behavior of rats was at least partly accomplished via the hippocampus; Oxy affected short-term memory as well as long-term memory.

[Study of factors associated with preterm delivery]

A case-control study of preterm delivery was undertaken at the district of Qiaokou in Wuhan during October, 1987 to May, 1988. The study population consisted of 130 mothers of singleton preterm infants and 260 mothers of singleton term infants. The result of logistic regression analysis showed that significant factors of preterm delivery included low maternal stature, the young age of menarche, a previous induced abortion, a history of infertility problems, vaginal bleeding during the pregnancy, low weight gain during the pregnancy, premature rupture of membranes, hyperemesis gravidarum, and lack of antenatal care. The result also showed that psychosocial stress in pregnancy might be related to preterm delivery.