Expression of the extracellular domain of the human immunodeficiency virus type 1 envelope protein and its fusion with beta-galactosidase in Saccharomyces cerevisiae

Two envelope glycoprotein gene fragments were cloned from the proviral genome of the HXB2 isolate of human immunodeficiency virus (HIV). For the production of the two domains of the envelope gene product these cloned gene fragments were inserted into an Escherichia coli-yeast inducible shuttle vector fused to the galactokinase (GAL1) promoter. Cell extracts from strains of Saccharomyces cerevisiae harboring these two vectors (pYENV1 and pYENV2) were found to contain a specific protein with a size of 50 kDa when induced by galactose, while the protein could not be detected in extracts from control cells containing only the E. coli-yeast vector in the presence of galactose. Furthermore, another expression plasmid coding for fusion proteins from the majority of the external envelope glycoprotein (gp120) moiety and a large part of the beta-galactosidase was constructed. Antibodies from HIV type 1-positive sera could react with recombinant fusion polypeptides. Transformants could produce this fusion protein to a level of about 1.6% of the total protein content, as deduced from beta-galactosidase activity.

Binding affinity of Cu(II)-VP-16 (etoposide) complex and its analogues to DNA and hydroxyl radical generation during DNA strand breaks

Conformational effects and affinities of VP-16 (etoposide) and its derivatives to DNA in the presence of Cu(II) ion were examined by circular dichroic (CD) spectra. The Cu(II)/Cu(I) redox kinetics and the hydroxyl radical (.OH) generation from the Cu(II)-complexes were estimated by the stopped-flow kinetics. Based on the results, DNA-cleaving activity of Cu(II)-complexes of VP-16 has been shown to be related with binding affinity of the complex to DNA, Cu(II)/Cu(I) redox and .OH generation, emphasising the mechanism of generated .OH attack to DNA.

[Long-term results of combined splenorenal shunt and porta-azygos devascularization in patients with portal hypertension]

OBJECTIVE

To investigate the long-term effects of combined splenorenal shunt and porta-azygos devascularization in patients with portal hypertension.

METHOD

We analysed retrospectively the follow-up results of 140 portal hypertensive patients undergoing the combined therapy in our hospital from April 1978 to April 1997. Changes of portal hemodynamics were studied by Doppler Flowmeter and DSA pre- and-postoperatively and direct FPP measurement intraoperatively.

RESULT

The operative mortality was 3.6%. No rebleeding was noted in a short period and rebleeding rate was 8.3% in a long term follow-up. The rate of postoperative hepatic encephalopathy was 5.0%. The long-term survival rate of 5-, 10- and 15-years was 83.6%, 64.5% and 54.5%, respectively. After operation FPP and PVP decreased significantly (P < 0.01) and FPP maintained at the level of 3.2 +/- 0.4 kPa.

CONCLUSION

The combined procedure is a rational and practical procedure for the treatment of patients with portal hypertension.

[Comparative research on two different killer strains of Saccharomyces cerevisiae]

Using two different killer strains SK4(K1 type) and ERR1(K2 type), their killer characters were analysed and find two strains compete with each other when they are mixed and killer characters are related with the growth of strains. Different M-dsRNA plasmids in different killer strains have different molecular lengths, being 1.7 kb and 1.5 kb in SK4 and ERR1, respectively. L-dsRNA plasmids in both strains have the same molecular lengths, 4.0 kb. Cured by high temperature (38 degrees C) and U.V. (15 W, 30 cm, 5 min), killer strains lose their killer characters with the disappearance of M-dsRNA, the curing rate of killer activity is associated with strains and curing conditions. Killer toxins produced by two strains have different killer effects. Toxins of SK4 and ERR1 have the different highest killer activity at pH 4.8, 16 degrees C and pH4.2, 22 degrees C, but both of two toxins have the greatest effect on the sensitive strain in the late-log phase.

[The timing and mode of surgery in patients with severe acute pancreatitis]

OBJECTIVE

To investigate the timing and mode of surgical management in patients with severe acute pancreatitis (SAP).

METHOD

The timing, mode of operation and mortality were reviewed retrospectively in 50 SAP cases undergoing laparotomy in our hospital from 1985 to 1994.

RESULT

The overall mortality was 14% and 85.7% of the mortality falls on the age between 40 to 60 years, with no difference in etiology and sex. The operative mortality reduced gradually in patients with longer duration of illness (P > 0.05). The operative mortality of 31.8% in patients undergoing laparotomy within 12 h after hospitalization was significantly higher (P < 0.05) than in these operated on later. When the number of injured extra-pancreatic organs increased, the mortality also increased significantly (chi(2) = 5.99, P < 0.05). The related mortality with shock, pancreatic necrosis and multiorgan failure (MOF) was 31.8%, 31.6% and 28%, respectively (P < 0.05). The main procedures of surgical management were pancreatic debridement and/or drainage, and combined surgical measures.

CONCLUSION

The laparotomy timing is an important factor influencing mortality as well as the severity of pancreatic necrosis, sepsis, and MOF. Delayed laparotomy and 24 h preoperative management is recommended. Surgery adopted should be simple, efficient in drainage and debridement.

Intermolecular Force-Field Parameters for Boron Hydrides

Intermolecular atom–atom force-field parameters of the (exp-6-1) type for B and H atoms in boron hydrides were determined. They were obtained by full-weighted least-squares minimization of 116 forces in 15 observed crystal structures of boranes, the heat of sublimation of B10H14 and data from ab initio wavefunction calculations for diborane. Net atomic charges were obtained by fitting them to molecular electric potentials calculated from ab initio wavefunctions. Charges of terminal hydrogens were usually negative and those of bridging hydrogens usually positive. Repulsion-energy calculations for the B2H6 dimer provided the exponential dependence of H...H repulsion. Using the resulting force field, minimum-energy crystal structures were found with structural parameter values close to those of the observed structures. For diborane, energy minimization beginning with randomly oriented molecules placed initially in an 8 × 8 × 8 body-centered orthogonal cell led to the observed crystal structure and monoclinic space group.

[An experimental study on effects of biomembrane on prevention of filtering bleb adhesion in trabeculectomy]

OBJECTIVE

The study was designed to investigate the effects of biomembrane on experimental trabeculectomy.

METHODS

A biomembrane was implanted under the scleral flap and the conjunctival flap in trabeculectomy in one eye of rabbits, while the fellow eye of the same rabbit without biomembrane implantation was the control.

RESULTS

(1) The wound healing of the procedure reached its peak at 2-3 weeks after surgery, while the absorption of the biomembrane began at 6 weeks after surgery, and there was no tight adhesion between the biomembrane and the scar tissue, thus the filtering fistula was prevented from obstruction. (2) From the 2nd to the 7th week after surgery, the percentage of existing functional bleb in the experimental group was significantly higher than that in the control group (P < 0.05). (3) From the 1st to the 5th postoperative week, the decreasing of intraocular pressure in the experimental group was significantly greater than that in the control group (P < 0.05).

CONCLUSION

The use of biomembrane in trabeculectomy can prevent the adhesion of filtering bleb and decrease intraocular pressure more effectively, and this study can provide experimental reference for the clinical use of biomembrane.

Water and DMSO membrane permeability characteristics of in-vivo- and in-vitro-derived and cultured murine oocytes and embryos

Although embryo cryopreservation is routine for many mammalian species, it is important to know how the fundamental cryobiology of these cells changes with development. Progressive cleavage divisions result in a reduction in the blastomere surface area available for water and cryoprotectant mass transport. Therefore, the membrane permeability of murine oocytes, zygotes, 2-cell, 4-cell, and 8-cell embryos to water (Lp), and dimethylsulphoxide (PDMSO), and the reflection coefficient, sigma (sigma) were determined. Oocytes or zygotes were recovered, cumulus cells removed, then cultured until use. Oocytes and embryos were immobilized and perfused with treatment solutions at 24 degrees C. Osmotically induced cell volume changes over time were videotaped followed by image analysis. The Lp values in the presence of dimethylsulphoxide (DMSO) were 0.77, 0.81, 0.94, 0.86, and 1.10 microm/min/atm, and the PDMSO values were 1.85, 2.04, 2.41, 1.95, and 1.25x10(-3) cm/min for oocytes, zygotes, 2, 4, and 8-cell embryos respectively. The Lp values in the presence of DMSO were significantly (P < 0.05) higher than those in the absence of DMSO. Treating the whole embryo as a single osmotic entity leads to significantly (P < 0.05) elevated PDMSO estimates relative to those based upon measurements of individual blastomeres. These data indicate that both Lp and PDMSO estimates are lower when predicted on an individual blastomere basis. The data also show that neither Lp nor PDMSO differ among oocytes, zygotes, 2-cell and 4-cell embryos. However, the significantly higher Lp and lower PDMSO of the 8-cell stage support the hypothesis that fundamental cryobiological differences may require developmental stage-specific embryo cryopreservation protocols.

Functional domains of LAG-2, a putative signaling ligand for LIN-12 and GLP-1 receptors in Caenorhabditis elegans

The LAG-2 membrane protein is a putative signaling ligand for the LIN-12 and GLP-1 receptors of Caenorhabditis elegans. LAG-2, like its Drosophila homologues Delta and Serrate, acts in a conserved signal transduction pathway to regulate cell fates during development. In this article, we investigate the functional domains of LAG-2. For the most part, mutants were constructed in vitro and assayed for activity in transgenic animals. We find a functional role for all major regions except one. Within the extracellular domain, the N-terminal region, which bears no known motif, and the DSL domain are both required. By contrast, the region bearing epidermal growth factor-like repeats can be deleted with no apparent reduction in rescuing activity. The intracellular region is not required for activity but instead plays a role in down-regulating LAG-2 function. Finally, membrane association is critical for mutant rescue.

Roles of GABA, glutamate, acetylcholine and STN stimulation on thalamic VM in rats

The effects of high frequency stimulation of the subthalamic nucleus (STN) and of iontophoretic application of different neurotransmitters on neuronal activities of the ventromedial thalamic nucleus (VM) were investigated in rats. GABA, when applied iontophoretically, inhibited VM neuronal activity while bicuculline, L-glutamic acid and acetylcholine enhanced the firing rates of the same VM neurons. High frequency stimulation of the STN increased VM neuronal activity in a frequency-dependent manner, which could be blocked by MK801. These results suggest that GABAergic, cholinergic and glutamatergic input information converge in the same VM neurons and that an increase in the delivery of glutamatergic neurotransmitter activities in the VM is involved in the process of high frequency stimulation of the STN.

Solidification Processes of Solutions

Recent progress in modeling pure liquid and dendritic alloy solidification is reviewed to lay the groundwork for freezing of solutions relevant to cryopreservation of biological materials. The classical Stefan problem of freezing/melting a pure substance is discussed first to introduce some of the fundamental concepts, and then the framework for modeling the freezing of solutions is reviewed. The formalism is extended to the freezing of a solution-saturated porous media. As an application of the methodologies developed by engineers, freezing of a sodium chloride solution in a flat bag is simulated, and then using the temperature and salt concentration data calculated the kinetics of water loss from a model cell is predicted.

Novel microwave technology for cryopreservation of biomaterials by suppression of apparent ice formation

Ice formation inside or outside cells has been proposed to be a factor causing cryoinjury to cells/tissues during cryopreservation. How to control, reduce, or eliminate the ice formation has been an important research topic in fundamental cryobiology. The objective of this study was to test a hypothesis that the coupled interaction of microwave radiation and cryoprotectant concentration could significantly influence ice formation and enhance potential vitrification in cryopreservation media at a relative slow cooling rate. Test samples consisted of a series of solutions with ethylene glycol (a cryoprotectant) concentration ranging from 3 to 5.5 M. A specific microwave resonant cavity was built and utilized to provide an intense oscillating electric field. Solutions were simultaneously exposed to this electric field and cooled to -196 degrees C by rapid immersion in liquid nitrogen. Control samples were similarly submerged in liquid nitrogen but without the microwave field. The amount of ice formation was determined by analysis of digital images of the samples. The morphology of the solidified samples was observed by cryomicroscopy. It was found that ice formation was greatly influenced by microwave irradiation. For example, ice formation could be reduced by roughly 56% in 3.5 M ethylene glycol solutions. An average reduction of 66% was observed in 4.5 M solutions. Statistical analysis indicated that the main effects of microwave and ethylene glycol concentration as well as the interaction between these two factors significantly (P < 0.01) influenced ice formation amount, confirming the hypothesis. This preliminary study suggests that a combined use of microwave irradiation and cryoprotectant might be a potential approach to control ice formation in cells/tissues during the cooling process and to enhance vitrification of these biomaterials for long-term cryopreservation.

[Influences of acetylcholine, glutamic acid and GABA on the neuronal firings in ventromedial thalamic nucleus]

In this study, it was shown that the neuronal spontaneous firings of ventromedial thalamic nucleus (VM) in rats were increased by acetylcholine (ACH) and glutamic acid (GLU) applied microiontophoretically with an intensity-dependent manner. Both gamma-animobutyric acid (GABA) and baclofen inhibited the spontaneous firings in majority of VM neurons, but the effect of GABA was rapid and short-lasting, while that of baclofen was slow and long-lasting. GABA could reverse the effects of ACH and GLU. The majority of VM neuronal firing rates could be enhanced by bicuculine, while atropine and MK801 had little effect. The results indicate an important convergence of GLUergic, GABAergic and cholinergic activities in the same VM neurons and GABAergic activities tonically inhibit the VM neurons.

Structure and transcription of the gene for translation elongation factor 1 subunit alpha of zebrafish (Danio rerio)

The zebrafish gene for translation elongation factor 1 alpha (EF1 alpha) was isolated from a phage Lambda genomic library and sequence and structure determined. One gene copy of EF1 alpha per haploid set of chromosomes was found and no processed pseudogenes. A highly active promoter region was localized to a 277 bp PstI/PvuII fragment beginning 240 bp upstream from the tsp, but no transcription enhancing, or silencing activity was observed within 1 kbp upstream, or downstream from the promoter. Expression of EF1 alpha appears to be developmentally regulated.

Effect on product formation in recombinant Saccharomyces cerevisiae strains expressing different levels of xylose metabolic genes

The XYL1 and XYL2 genes from Pichia stipitis encoding xylose reductase (XR) and xylilitol dehydrogenase (XDH), respectively, were transformed into Saccharomyces cerevisiae. These two genes were placed in different directions under the control of the alcohol dehydrogenase I (ADHI) and phosphoglycerate kinase (PGK) promoters and inserted into the E. coli-yeast shuttle plasmid YEp24. Different recombinant S. cerevisiae strains were constructed with different specific activities of XR and XDH. The highest XR or XDH activities were obtained when the expressed gene was controlled by the PGK promoter and located downstream after the ADHI promoter-gene-terminator sequence. The XR/XDH ratio (ratio of specific enzyme activities of XR and XDH) in these recombinant S. cerevisiae strains varied from 17.5 to 0.06. In order to enhance xylose utilization, in the XYL1, XYL2 containing S. cerevisiae strains, the native TKL1 gene encoding transketolase and the TALI gene encoding transaldolase were also overexpressed, which showed considerably good growth on the xylose plate. Fermentation of the recombinant S. cerevisiae strains containing XYL1, XYL2, TKL1, and TAL1 were studied with mixtures of glucose and xylose. The strain with XR/XDH ratio of 0.06 consumed 3.25 g/L xylose and formed no xylitol and less glycerol and acetic acid, but more ethanol compared with the strains with a higher XR/XDH ratio.

Zebrafish translation elongation factor EF1 alpha mRNA: sequence and secondary structures

We have determined the complete sequence of the translation elongation factor EF1 subunit alpha (EF1 alpha) mRNA of zebrafish, and the 3'-untranslated sequence of EF1 alpha mRNA of halibut. The 5'-untranslated leader sequence of the EF1 alpha mRNA starts with a polypyrimidine tract. This feature is shared with the mRNAs for ribosomal proteins, where it affects the utilization of mRNA by ribosomes. However, the secondary structures of these leader sequences may differ. 5'-Polypyrimidine tracts of vertebrate EF1 alpha mRNAs participate in the formation of stable stem-loop structures, whereas those of 15 randomly chosen mRNAs for ribosomal proteins do not. This difference may provide a basis for differential control of translation for the two classes of mRNA. The 3'-untranslated sequences of vertebrate EF1 alpha mRNA have diverged little during evolution. Analyses of sequence and putative secondary structures suggest that both sequence-specific interactions and secondary structures may have contributed to sequence conservation.

Inhibition of microsomal lipid peroxidation by baicalein: a possible formation of an iron-baicalein complex

Baicalein decreased the production of thiobarbituric acid reactive substances, the rate of oxygen consumption and iron reduction in the reaction system of ascorbic acid with FeCl3. Superoxide dismutase, catalase and hydroxyl radical scavengers had no significant effect. Iron-chelators had an inhibitory effect similar to that of baicalein. The production of thiobarbituric acid reactive substances of baicalein-treated microsomes obtained by centrifugation after incubation with baicalein was not observed in the reaction system, but was stimulated by adding iron with increases in concentration. The amount of bound iron to microsomal membranes increased by increasing both the concentration of baicalein and iron. The amount of baicalein bound to microsomal membranes increased with increasing concentration of added baicalein. These results suggest that baicalein bound to microsomal membranes inhibits lipid peroxidation by formating an iron-baicalein complex.

[Angioimmunoblastic lymphadenopathy and angioimmunoblastic T-cell lymphoma]

To investigate the clinicopathological changes of angioimmunoblastic lymphadenopathy (AILD) and angioimmunoblastic T-cell lymphoma (AITL), 5 cases of AILD and AITL were analyzed by using immunohistochemistry and Polymerase chain reaction (PCR) methods. The clinical manifestations included general lymphadenopathy, hepatosplenomegaly, fever and hematologic abnormalities. The diagnosis and differentiation of AILD and AITL were depended on the histopathologic features of lymphnodes biopsy. The presence of clusters of clear cells with variable atypia and positivity of T-cell marker were the most important diagnostic criterion for AITL. PCR analysis of TCR-beta rearrangement and EBV-genome was performed on 4 of 5 cases. All of the cases showed clonal rearrangement of TCR-beta and 3 of them were EBV-DNA positive. The results suggest that AILD might be a prelymphomatous lesion, related to EBV infection with a high incidence of developing to malignant lymphoma.

[Study on the interrelationship between human papilloma virus infection and Langerhans cell in carcinogenesis of esophagus]

In order to find out the interrelationship between human papilloma virus (HPV) infection and Langerhans cells (LCs) during the development of esophageal carcinoma, and the mechanism of carcinogenesis during HPV infection, digoxigenine labelled HPV DNA probes of HPV 6B/11, HPV 16/18 with in situ hybridization, and anti-S-100 protein antibody with immunohistochemical LSAB-assays were used respectively in order to investigate HPV infection and the distribution of LCs in 40 cases of esophageal squamous cell carcinoma (ESCC). The results showed that there were fewer LC infiltration in HPV-positive cases in comparison with that of the HPV-negative cases. There were also changes about the morphology and distribution of LCs in HPV infected epithelia adjacent to the tumor. The results indicated that HPV infection might inhibit the number of locally LCs infiltrated, destroy the immune surveillance system, and work simultaneously with other carcinogenic factors, in favor of the development of ESCC.

Chronic electrical stimulation of the ventralis intermedius nucleus of the thalamus as a treatment of movement disorders

Tremor was suppressed by test stimulation of the thalamic ventralis intermedius (VIM) nucleus at high frequency (130 Hz) during stereotaxy in nonanesthetized patients suffering from Parkinson's disease or essential tremor. Ventralis intermedius stimulation has since been used by the authors over the last 8 years as a treatment in 117 patients with movement disorders (80 cases of Parkinson's disease, 20 cases of essential tremor, and 17 cases of various dyskinesias and dystonias including four multiple sclerosis). Chronic electrodes were stereotactically implanted in the VIM and connected to a programmable stimulator. Results depend on the indication. In Parkinson's disease patients, tremor, but not bradykinesia and rigidity, was selectively suppressed for as long as 8 years. Administration of L-Dopa was decreased by more than 30% in 40 Parkinson's disease patients. In essential tremor patients, results were satisfactory but deteriorated with time in 18.5% of cases, mainly for patients who presented an action component of their but deteriorated with time in 18.5% of cases, mainly for patients who presented an action component of their tremor. In other types of dyskinesias (except multiple sclerosis), results were much less favorable. Fifty-nine patients underwent bilateral implantation and 14 other patients received implantation contralateral to a previous thalamotomy. Thirty-seven patients (31.6%) experienced minor side effects, which were always well tolerated and immediately reversible. Three secondary scalp infections led to temporary removal of the implanted material. There was no permanent morbidity. This tremor suppression effect could be due to the inhibition or jamming of a retroactive loop. Chronic VIM stimulation, which is reversible, adaptable, and well tolerated even by patients undergoing bilateral surgery (74 of 117 patients) and by elderly patients, should replace thalamotomy in the regular surgical treatment of parkinsonian and essential tremors.

Osmotic separation of pancreatic exocrine cells from crude islet cell preparations

A novel approach is introduced here to selectively lyse exocrine cells in an islet preparation by hypo-osmotic treatment. Time to hypotonic cell lysis required for the islet cells was much longer than that for the exocrine cells, which permits a possibility of selectively killing the exocrine cells by hypotonic treatment. The first set of experiments was designed to select an appropriate osmolality for the hypotonic treatment. Kinetic changes in cell volume in response to extracellular anisosmolalities (30 to 90 mOsm/kg) were recorded using an electronic particle counter. The results indicated that, when exposed to a 30 mOsm/kg solution, islet cells swelled slowly to reach volumetric equilibrium in approximately 3 min. There was no significant hypotonic cell lysis observed even at the end of 4 min (n = 4). In contrast, pancreatic exocrine cells, when exposed to the same solution, expanded rapidly to the lytic volume and burst within 30 s. Significant exocrine cell lysis was invariably achieved within 30 s when cells were exposed to the osmolalities below 60 mOsm/kg. For osmolalities between 70 to 80 mOsm/kg, exocrine cell lysis was highly variable. When cells were exposed to 80 to 90 mOsm/kg, no significant cell lysis was observed. Thus, an osmolality of 50 mOsm/kg is recommended for hypotonic treatment, as it maximizes the lysis of exocrine cells without unnecessarily stressing (osmotically) the islet cells. The second set of experiments (time-course experiments, 20 to 120 s) was designed to determine the length of exposure time for which the exocrine cells were irreversibly damaged but the islet cells had only swollen to such a degree that cell function is restored upon returning to an isotonic condition. Viability of the hypotonic treated cells was evaluated at two different levels: membrane integrity, measured by combined fluorescent dye staining with propidium iodide (PI) and carboxyfluorescein diacetate (CFDA), and mitochondrial function, measured by colorimetric MTT assay. The results showed that hypotonic treatment in a 50 mOsm/kg solution for 30 s resulted in over 85% loss of the membrane integrity for the exocrine cells. About 90% of these membrane lysed cells lost mitochondrial function (n = 3). By contrast, under the same treatment, less than 15% of the islet cells lost membrane integrity and mitochondrial function (n = 3). In conclusion, hypotonic treatment with a 50 mOsm/kg solution for 20 to 30 s at room temperature is sufficient to lyse the majority of the contaminating exocrine cells in an islet cell preparation, while maintaining function in the islet cells.