[Studies on the antifertility effect of bis-trichloromethyl sulfone and its reversibility in male rats]

Bis-trichloromethyl sulfone(BTS) given p.o. to male Sprague-Dawley rats at a dose of 10 mg.kg-1.d-1, 6 days a week for 8 weeks(or 30 mg.kg-1.d-1 for 4 weeks), was found to lead to infertility. The density and, in particular, the motility of the spermatozoa in the cauda epididymidis were significantly lower than those of the controls (P < 0.001). The body weight, the sex behavior, the blood testosterone level and the histology of important organs were not significantly different from those of the control rats. Fertility started to recover 4 weeks after cessation of medication and was entirely recovered 2 more weeks later in rats having received BTS for 8 weeks at the dose of 30 mg.kg-1.d-1. In vitro study showed that BTS at a concentration of 0.31 mg.ml-1 would make rat spermatozoa immobile within 20 seconds. These results indicate that BTS has both antifertility effect in male rats and direct inhibitory effect on rat spermatozoa. We conclude that nontoxic doses of BTS can induce reversible infertility in male rats.

[Genome mapping in aquatic animals: progress and future perspectives]

The genome of aquatic animals is poorly understood and information from different taxonomic groups is sketchy. While there have been intensive genomic studies on some fish models, investigations on other fishes and invertebrates have been scarce. Yet there are recently some coordinated studies on genome mapping in a number of aquaculture animals of economic importance. This review summarizes information available on genome mapping of the important fish models and aquaculture animals. The future perspectives of this field of studies are discussed.

Family cognitive behaviour therapy for chronic fatigue syndrome: an uncontrolled study

AIM

To examine the efficacy of family focused cognitive behaviour therapy for 11-18 year olds with chronic fatigue syndrome.

METHODS

Twenty three patients were offered family focused cognitive behaviour therapy. The main outcome was a fatigue score of less than 4 and attendance at school 75% of the time.

RESULTS

Twenty patients completed treatment. Eighteen had completed all measures at six months follow up; 15 of these (83%) improved according to our predetermined criterion. Substantial improvements in social adjustment, depression, and fear were noted.

CONCLUSIONS

Family focused cognitive behaviour therapy was effective in improving functioning and reducing fatigue in 11-18 year olds. Gains were maintained at six months follow up.

Netrin stimulates tyrosine phosphorylation of the UNC-5 family of netrin receptors and induces Shp2 binding to the RCM cytodomain

Caenorhabditis elegans UNC-5 and its mammalian homologues such as RCM are receptors for the secreted axon guidance cue UNC-6/netrin and are required to mediate the repulsive effects of UNC-6/netrin on growth cones. We find that C. elegans UNC-5 and mouse RCM are phosphorylated on tyrosine in vivo. C. elegans UNC-5 tyrosine phosphorylation is reduced in unc-6 null mutants, and RCM tyrosine phosphorylation is induced by netrin-1 in transfected HEK-293 cells, demonstrating that phosphorylation of UNC-5 proteins is enhanced by UNC-6/netrin stimulation in both worms and mammalian cells. An activated Src tyrosine kinase induces phosphorylation of RCM at multiple cytoplasmic tyrosine residues creating potential binding sites for cytoplasmic signaling proteins. Indeed, the NH2-terminal SH2 domain of the Shp2 tyrosine phosphatase bound specifically to a Tyr(568) RCM phosphopeptide. Furthermore, Shp2 associated with RCM in a netrin-dependent manner in transfected cells, and co-immunoprecipitated with RCM from an embryonic mouse brain lysate. A Y568F mutant RCM receptor failed to bind Shp2 and was more highly phosphorylated on tyrosine than the wild type receptor. These results suggest that netrin-stimulated phosphorylation of RCM Tyr(568) recruits Shp2 to the cell membrane where it can potentially modify RCM phosphorylation and function.

ERM-dependent movement of CD43 defines a novel protein complex distal to the immunological synapse

The large mucin CD43 is actively excluded from T cell/APC interaction sites, concentrating in a membrane domain distal to the site of TCR engagement. The cytoplasmic region of CD43 was necessary and sufficient for this antipodal movement. ERM cytoskeletal adaptor proteins colocalized with CD43 in this domain. An ERM dominant-negative mutant blocked the distal accumulation of CD43 and another known ERM binding protein, Rho-GDI. Inhibition of ERM function decreased the production of IL-2 and IFNgamma, without affecting PKC(theta) focusing or CD69 upregulation. These results indicate that ERM proteins organize a complex distal to the T cell/APC interaction site and provide evidence that full T cell activation may involve removal of inhibitory proteins from the immunological synapse.

Structural basis for autoinhibition of the Ephb2 receptor tyrosine kinase by the unphosphorylated juxtamembrane region

The Eph receptor tyrosine kinase family is regulated by autophosphorylation within the juxtamembrane region and the kinase activation segment. We have solved the X-ray crystal structure to 1.9 A resolution of an autoinhibited, unphosphorylated form of EphB2 comprised of the juxtamembrane region and the kinase domain. The structure, supported by mutagenesis data, reveals that the juxtamembrane segment adopts a helical conformation that distorts the small lobe of the kinase domain, and blocks the activation segment from attaining an activated conformation. Phosphorylation of conserved juxtamembrane tyrosines would relieve this autoinhibition by disturbing the association of the juxtamembrane segment with the kinase domain, while liberating phosphotyrosine sites for binding SH2 domains of target proteins. We propose that the autoinhibitory mechanism employed by EphB2 is a more general device through which receptor tyrosine kinases are controlled.

[Selective isolation of anethole from volatile oil of Foeniculum vulgare Mill by inclusion crystalline with chela-shape host]

AIM

To isolate the components from the volatile oil of Foeniculum vulgare Mill.

METHODS

According to the function of molecular recognition of supramolecular chemistry, chela shape molecule, trans-1, 2-biphenyl-1, 2-acenaphthendiol was used as host molecule and the volatile oil of Foeniculum vulgare Mill as guest molecule. Trans-1, 2-biphenyl-1, 2-acenaphthendiol can recognize the components that endowed with interactional complementarity and form inclusion compound as crystals.

RESULTS

The anethole in the volatile oil was selectively included as trans-1,2-biphenyl-1,2-acenaphthendiol which was obtained in pure state from the inclusion compound by Kugelrohr vacuum technology. The formation of inclusion compound was confirmed by means of IR and powder XRD. The structure of the selectively isolated component was elucidated as trans-anethole by means of IR, 1HMMR and MS.

CONCLUSION

The experimental results showed that the method is simple, rapid and selective for isolation anethole from volatile oil of Foeniculum vulgare Mill.

Dopamine D1-stimulated adenylyl cyclase activity in cerebral cortex of autopsied human brain

Although the cerebral cortical dopamine D(1) receptor is considered to play a role in normal and abnormal brain function, little information is available on its characteristics in human brain. We compared dopamine-stimulated adenylyl cyclase (AC) activity in homogenates of cerebral cortex (frontal, temporal, parietal, occipital and cingulate cortex) of autopsied brain of neurologically normal subjects to that in striatum. Cerebral cortical AC activity was modestly and dose-dependently stimulated by dopamine (maximal 20-30%) with low microM EC50s and such stimulation was inhibited by the selective dopamine D1 receptor antagonist SCH23390. The magnitude of the maximal stimulation by dopamine was similar in autopsied and biopsied cerebral cortex. The extent of maximal stimulation was similar to that in dopamine-rich striatum (caudate, putamen and nucleus accumbens), despite much lower density of dopamine D1 receptors in cerebral cortex vs. striatum. The EC50 for dopamine stimulation in cerebral cortex (approximately 1 microM) was lower than that for caudate and putamen (approximately 3 microM). No detectable dopamine stimulation was observed in cerebellar cortex, thalamus or hippocampus. Dopamine stimulation in both cerebral cortex and striatum was independent of calcium activation. We conclude that dopamine stimulated AC can be measured in cerebral cortex of human brain allowing for the possibility that this process can be examined in human brain disorders in which dopaminergic abnormalities are suspected.

Software scripts for quality checking of high-throughput nucleic acid sequencers

We have developed a graphical interface to allow the researcher to view and assess the quality of sequencing results using a series of program scripts developed to process data generated by automated sequencers. The scripts are written in Perl programming language and are executable under the cgibin directory of a Web server environment. The scripts direct nucleic acid sequencing trace file data output from automated sequencers to be analyzed by the phred molecular biology program and are displayed as graphical hypertext mark-up language (HTML) pages. The scripts are mainly designed to handle 96-well microtiter dish samples, but the scripts are also able to read data from 384-well microtiter dishes 96 samples at a time. The scripts may be customized for different laboratory environments and computer configurations. Web links to the sources and discussion page are provided.

Production of cysteinyl-dopamine during intravenous dopamine therapy

BACKGROUND

Oxidized dopamine rapidly forms thiol-conjugates with --SH groups on cysteine, glutathione, and proteins. We used cysteinyl-dopamine production as an index of thioester production during intravenous dopamine treatment of critically ill patients.

METHODS

Cysteinyl-dopamine and catecholamines were measured by high-performance liquid chromatography with electrochemical detection. The production of cysteinyl-dopamine by purified human neutrophils was measured using dopamine (1 micromol/L) and cysteine (1 mmol/L) concentrations similar to those found during dopamine treatment. To examine the impact of endotoxic shock on cysteinyl-dopamine production, anesthetized rats were given dopamine (12 to 15 microg/kg/min intravenously) with or without endotoxin (50 mg/kg intravenously).

RESULTS

In vitro, neutrophils converted 26% of dopamine to cysteinyl-dopamine (30 min at 37 degrees C). Activating neutrophils with zymogen increased dopamine consumption from 26 to 68%, but only 36% appeared as cysteinyl-dopamine. The remainder may have been oxidized to other cysteinyl derivatives. Endotoxin increased cysteinyl-dopamine in rat plasma from 2.5 nmol/L (range <0.2 to 11) to 9.7 nmol/L (range <0.3 to 31, P = 0.1). After four hours, with or without endotoxin, cysteinyl-dopamine was <0.3 nmol/L in cerebrospinal fluid. In the plasma of eight patients receiving dopamine (6 to 20 microg/kg/min for 1 to 3 days), dopamine was 0.5 to 9.9 micromol/L, and cysteinyl-dopamine was 48 to 1660 nmol/L. Cysteinyl-dopamine was 4.3 to 22.6% of dopamine and correlated with leukocyte count (r(2) = 0.388, P = 0.099).

CONCLUSIONS

A significant fraction of exogenously administered dopamine reacts with -SH groups of cysteine and probably also with -SH groups on peptides and proteins. During brief dopamine treatment of endotoxic shock in rats, neither dopamine nor cysteinyl-dopamine crossed the blood-brain barrier.

[An autopsy case of Ehlers-Danlos syndrome showing various types of cerebrovascular disease]

We report a 73-year-old woman with Ehlers-Danlos syndrome (EDS) and hypertension who had developed various types of cerebrovascular disease. She had suffered from cerebral hemorrhage of the left putamen at the age of 58, of the left parietal lobe at 64 and cerebral infarction of right internal capsule at 71. EDS type II or III was suggested by two times of skin biopsies. A brain CT at the age of 73 revealed a comparatively large cerebral aneurysm in the territory of the anterior cerebral artery. The patient was treated conservatively, but died due to rupture of the aneurysm. The wall of the aneurysm was made up thin collagen fibers without elastic fibers. There were other multiple small aneurysms in the cerebral arteries, but none in other organs. Deposition of acid mucopolysaccharides was noted in the media of the abdominal aorta. Finally, the present case was thought most likely to be of EDS type IV. It was suggested that one of the causes of the cerebral hemorrhage at the ages of 58 and 64 and the infarction at 71 was related to hypertension, since brain MR angiography at 71 showed no clear aneurysms. In cases of EDS, one should consider the possible formation or rupture of cerebral aneurysm even though the course is favorable.

Paired cloning of the T cell receptor alpha and beta genes from a single T cell without the establishment of a T cell clone

T cell receptors, which recognize antigen peptides on MHC molecules, are essential probes for the analysis of T cell antigen specificity. The identification of paired T cell receptor (TCR) chains, alpha/beta or gamma/delta, usually requires the establishment of T cell clones, which is not always available. In this study, we tried, as an alternative method, the paired cloning of TCR alpha/beta genes directly from a single T cell. T cells were sorted as a single cell from which RNA was extracted. Then, TCR alpha/beta CDR3 regions were amplified from the single cell-derived cDNA by reverse transcriptase-polymerase chain reaction to determine their sequences. We successfully identified pairs of TCR alpha/beta genes, and reconstructed the TCR molecule by a bacterial expression system. This strategy makes it possible to obtain recombinant TCR molecules from a single T cell without cellular cloning and promotes the investigation of T cell antigen specificity.

Effect of advanced glycosylation end products on activity of protein kinase C in human peripheral blood mononuclear cells

OBJECTIVES

To investigate the effect of advanced glycosylation end products (AGEs) on the activity of protein kinase C (PKC) in human peripheral blood mononuclear cells (PBMC) and to observe whether aminoguanidine (AG) can influence the effect of AGEs.

METHODS

After PBMC were isolated from human peripheral blood and incubated with different concentrations of AGEs-BSA for various periods, total PKC activity in PBMC was determined by measuring the incorporation of 32P from [gamma-32 P] ATP into a special substrate using Promega PKC assay kit.

RESULTS

AGEs-BSA increased the total PKC activity in PBMC from 83.43 +/- 6.57 pmol/min/mg protein to 116.8 +/- 13.82 pmol/min/mg protein with a peak at 15 min. AGEs-BSA also increased the total PKC activity in a concentration-dependent manner from 83.1 +/- 6.4 pmol/min/mg protein (control) to 119.1 +/- 13.3 pmol/min/mg protein (control vs AGEs-BSA 400 mg/L, P < 0.01). Furthermore, AGEs-BSA induced an elevation of PKC activity in a glycosylating time-related manner, from 80.9 +/- 8.2 (control) to 118.3 +/- 11.5 pmol/min/mg protein (glycosylation for 12 wk, P < 0.01). The total PKC activity stimulated by AGEs-BSA pretreated with AG (100, 200 mg/L) was markedly lower than that of AGEs-BSA group not pretreated with AG (P < 0.05, P < 0.01).

CONCLUSIONS

AGEs-BSA increased the total PKC activity in PBMC in a concentration and incubation time dependent manner. The ability of AGEs-BSA to stimulate PKC activity was markedly decreased by pretreatment of AGEs-BSA with AG.

[Studies on cell transformation and cell cycle in human embryo lungs induced by nickel compounds]

OBJECTIVE

To elucidate the association between nickel compounds and occupational lung cancer.

METHODS

Human embryo lung cells (MRC-9 and IMR-90) were transformed by water-insoluble nickel oxide and nickel subsulfide, and changes in cell cycle of these transformed cells were analyzed by flow cytometric technique.

RESULTS

Morphological transformation in MRC-9 and IMR-90 cells were induced after exposure to nickel compounds for 3 - 5 months, including formation of transforming foci, overlaying growth and epithelium-like changes in cells, etc. Some transformed cells could form colonies in soft agar media. Changes in cell cycle of the transformed cells were observed with flow cytometry. Proportions of cells at G(1) phase and G(2)/M phase were 62.61% and 16.37%, respectively, in the untreated MRC-9 cells and hyperploid cells were hardly seen in cell cycle plots. But, in the transformed MRC-9 cells, proportion of cells at G(1) phase reduced to about 50%, and that at G(2)/M phase increased to over 20% and that of hyperploid cells to over 10%. The same phenomenon was observed in the IMR-90 cells.

CONCLUSIONS

Water-insoluble nickel compounds can induce morphological transformation of human embryo lung cells and those transformed cells appeared certain biological characteristics of tumor cells.

Combined free toe and free deep inferior epigastric perforator flap for reconstruction of the thumb and thumb web space

To repair a complexly injured hand with composite loss of the thumb and the thumb web space in one stage, the combined transfer of a free second toe and a free deep inferior epigastric perforator flap was designed. It was used to simultaneously reconstruct the thumb and thumb web space of the injured hand in five cases. All flaps survived and there were no complications at any donor site after the reconstructions. In follow-up averaging 35.6 months, the final functional and cosmetic outcomes of the reconstructed thumbs and thumb web spaces were satisfactory. Results demonstrated that the combined transfer of a free second toe and a free deep inferior epigastric perforator flap is a valid method for simultaneous reconstruction of the thumb and the thumb web space of the injured hand.

Preparation of Monodispersed Solid Lipid Microspheres Using a Microchannel Emulsification Technique

Monodispersed solid lipid microspheres consisting of high melting point edible oil were prepared as a novel sophisticated material. To prepare the monodispersed solid lipid microspheres a temperature-controlled microchannel (MC) emulsification process was devised. The prepared microspheres had diameters of approximately 20 µm or more and the standard deviation of the diameters was less than 1 µm. The effects of different surfactants, the pressure and the shape of the MC on the MC emulsification, and the diameter of the prepared droplet were studied. The experimental results are discussed using the new mechanism of droplets formation which is caused by the interfacial tension. Copyright 2000 Academic Press.

Prevalence of methylenetetrahydrofolate reductase C677T and its association with arterial and venous thrombosis in the Chinese population

Moderate hyperhomocysteinaemia (MHH) is associated with arterial and venous thrombosis. A main genetic defect related to MHH is a C to T substitution at nucleotide 677 of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. A prothrombin 20210A mutation was recently identified as a risk factor for arterial and venous thrombosis. However, studies on the prevalence of mutant MTHFR C677T and prothrombin G20210A and their association with thrombosis were controversial and seldom reported in the Chinese population. We investigated the prevalence of MTHFR C677T and prothrombin G20210A genotypes by polymerase chain reaction (PCR) followed by restriction enzyme digestion in 420 Chinese subjects: 53 with deep venous thrombosis (DVT); 145 with cerebrovascular disease [115 cerebral infarction, 30 cerebral haemorrhage (CH)]; 100 with coronary artery disease (CAD); and 122 control subjects. The prevalence of the mutated MTHFR 677TT genotype and the 677T allele in normal controls was 12.3% and 30.7% respectively, similar to that in Caucasians and Japanese. The mutant 677T homozygotes and alleles were more frequent in patients with DVT than in controls (18.9% vs. 12.3%, 0.01 < P < 0. 025; 48.1% vs. 30.7%, P < 0.005). The relative risk of DVT among the carriers of 677TT and 677T were significantly increased [odds ratios: 3.4, 95% confidence interval (CI) 1.3-9.5, and 3.6, 95% CI 1. 7-7.7, respectively). The mutant MTHFR heterozygous 677C/T carriers were increased in patients with cerebral infarction compared with controls (53.9% vs. 36.9%, 0.01 < P < 0.025). Relative risk of cerebral infarction was 0.96 (95% CI 0.4-2.3) for 677TT homozygotes and 1.99 (95% CI 1.2-3.4) for 677C/T heterozygotes. However, the distribution of the MTHFR TT genotype was less frequent in patients with CAD with coronary artery stenosis of > 50% than in controls (2. 8% vs. 12.3%, 0.025 < P < 0.05). Relative risk of CAD was not increased among the carriers of 677TT and 677T (odds ratios: 0.2, 95% CI 0-1.1, and 0.97, 95% CI 0.5-1.8, respectively). There were no differences in the distribution of the MTHFR genotypes among CH, CAD with coronary artery stenosis of < 50% and controls. The prothrombin 20210A mutation was not found in any patients or controls. These results demonstrated that MTHFR 677T was associated with DVT and cerebral infarction but was less associated with CAD in the Chinese population.

The human nucleus accumbens is highly susceptible to G protein down-regulation by methamphetamine and heroin

Although the nucleus accumbens is assumed to be a critical brain "pleasure center," its function in humans is unknown. As animal data suggest that a unique feature of this small brain area is its high sensitivity to down-regulation of an inhibitory G protein by drugs of abuse, we compared G protein levels in postmortem nucleus accumbens with those in seven other brain regions of chronic users of cocaine, methamphetamine, and heroin, and of matched controls. Biochemical changes were restricted to the nucleus accumbens in which concentrations of G(alpha)1 and/or G(alpha)2 were reduced by 32-49% in the methamphetamine and heroin users. This selective responsiveness to these abused drugs implies a special role for the human nucleus accumbens in mechanisms of drug reinforcement and suggests that some features of the drug-dependent state (e.g., tolerance) might be related to inhibition of G(alpha)1-linked receptor activity.

[Mechanism of pineal and suprachiasmatic regulation on circadian rhythm of body temperature in rats]

OBJECTIVE

To investigate the mechanism of circadian rhythm of skin and core temperature as regulated by pineal and suprachiasmatic nucleus (SCN) in rats.

METHOD

Pineal destruction and melatonin interference test were employed.

RESULT

The two nuclei functioned differently in the maintenance of the temperature rhythm. Changes of the temperature level were nucleus related, i.e., up-regulated by pineal and down-regulated by SCN. In terms of initiation and daily running of the rhythmic oscillation, pineal is probably the central clock of the skin temperature rhythm, while SCN mainly controls the core temperature rhythm.

CONCLUSION

The two nuclei interlink by way of neuroendocrine signals to balance over the oscillatory system of the circadian temperature.

Ligation reaction specificities of an NAD(+)-dependent DNA ligase from the hyperthermophile Aquifex aeolicus

An NAD(+)-dependent DNA ligase from the hyperthermophilic bacterium Aquifex aeolicus was cloned, expressed in Escherichia coli and purified to homogeneity. The enzyme is most active in slightly alkaline pH conditions with either Mg(2+)or Mn(2+)as the metal cofactor. Ca(2+)and Ni(2+)mainly support formation of DNA-adenylate intermediates. The catalytic cycle is characterized by a low k (cat)value of 2 min(-1)with concomitant accumulation of the DNA - adenylate intermediate when Mg(2+)is used as the metal cofactor. The ligation rates of matched substrates vary by up to 4-fold, but exhibit a general trend of T/A < or = G/C < C/G < A/T on both the 3'- and 5'-side of the nick. Consistent with previous studies on Thermus ligases, this Aquifex ligase exhibits greater discrimination against a mismatched base pair on the 3'-side of the nick junction. The requirement of 3' complementarity for a ligation reaction is reaffirmed by results from 1 nt insertions on either the 3'- or 5'-side of the nick. Furthermore, most of the unligatable 3' mismatched base pairs prohibit formation of the DNA-adenylate intermediate, indicating that the substrate adenylation step is also a control point for ligation fidelity. Unlike previously studied ATP ligases, gapped substrates cannot be ligated and intermediate accumulation is minimal, suggesting that complete elimination of base pair complementarity on one side of the nick affects substrate adenylation on the 5'-side of the nick junction. Relationships among metal cofactors, ligation products and intermediate, and ligation fidelity are discussed.

A neurofibromatosis-1-regulated pathway is required for learning in Drosophila

The tumour-suppressor gene Neurofibromatosis 1 (Nf1) encodes a Ras-specific GTPase activating protein (Ras-GAP). In addition to being involved in tumour formation, NF1 has been reported to cause learning defects in humans and Nf1 knockout mice. However, it remains to be determined whether the observed learning defect is secondary to abnormal development. The Drosophila NF1 protein is highly conserved, showing 60% identity of its 2,803 amino acids with human NF1 (ref. 12). Previous studies have suggested that Drosophila NF1 acts not only as a Ras-GAP but also as a possible regulator of the cAMP pathway that involves the rutabaga (rut)-encoded adenylyl cyclase. Because rut was isolated as a learning and short-term memory mutant, we have pursued the hypothesis that NF1 may affect learning through its control of the Rut-adenylyl cyclase/cAMP pathway. Here we show that NF1 affects learning and short-term memory independently of its developmental effects. We show that G-protein-activated adenylyl cyclase activity consists of NF1-independent and NF1-dependent components, and that the mechanism of the NF1-dependent activation of the Rut-adenylyl cyclase pathway is essential for mediating Drosophila learning and memory.

[Clinical application of artificial blood vessel graft for arteriovenous fistulization]

OBJECTIVE

To investigate the clinical application of artificial blood vessel graft for arteriovenous fistulization.

METHODS

From October 1995 to August 1998, 23 cases with renal failure received PTEF artificial vessels grafting for arteriovenous fistulization in the forearm. The PTFE artificial vessel was 6 mm in diameter, and 40 cm in length. Artificial vessel "U"-shaped loop was formed from elbow incision to wrist incision, and perfused by 20 ml heparin saline. The two ends of artificial vessel were end-to-side anastomosed with superficial cubital vein and cubital artery respectively.

RESULTS

All of arteriovenous fistulas were successfully formed, and could be performed hemodialysis periodically. The artificial vessels could be punctured repeatedly, and had sufficient volume of blood flow. It had no rejection, no formation of false aneurysm, and no ischemia in arm or exacerbated reflux to heart.

CONCLUSION

The artificial vessel grafting for arteriovenous fistulization is a safe and convenient technique in clinical practice, especially when there is no autogenous vessels for arteriovenous fistula.

Effects of cooling germinal vesicle-stage bovine oocytes on meiotic spindle formation following in vitro maturation

Attempts to cryopreserve bovine oocytes result in low survival because of their sensitivity to temperatures near 0 degrees C. This study evaluates the effects of chilling germinal vesicle-stage (GV) oocytes on their formation of microtubules and the meiotic spindle. In experiment 1, five groups of GV-stage oocytes, each consisting of approximately 90 oocytes, were held at 39 degrees C as controls, or at 31 degrees C, or cooled to 24, 4 or 0 degrees C for 10 min. After being treated, all oocytes were cultured at 39 degrees C for 24 hr. Compared to the controls, holding oocytes for 10 min at 31 or 24 degrees C did not significantly alter the formation of normal spindles, but chilling them to 4 or 0 degrees C did. After 24 hr of maturation, the respective percentages of oocytes containing normal meiotic spindles observed in the controls or those held at 31 or 24 degrees C were 69.8%, 71.9%, or 69.4% (P > 0.05). In contrast, the percentages of oocytes with normal spindles after they had been cooled to 4 or 0 degrees C were 44.0% or 29.1%, respectively. In experiment 2, approximately 90 oocytes/group were cooled to 4 degrees C for various times before being warmed and cultured. Regardless of the time of exposure, cooling oocytes to 4 degrees C reduced the formation of normal spindles. The percentages of oocytes cooled to 4 degrees C for 10, 20, 30, 45, or 60 min with normal spindles were 44.0%, 38.4%, 37.5%, 34.5% and 30.9%, respectively. In experiment 3, approximately 60 oocytes per group that had been held at 31 degrees C or cooled to 24, 4 or 0 degrees C for 10 min were allowed to mature for 24 hr before being subjected to in vitro fertilization. The cleavage rates of oocytes subjected to various chilling treatments exhibited the same pattern as that of oocytes with normal spindles. That is, there were no significant differences in cleavage rates among the control oocytes and those held at 31 or 24 degrees C (70.4%, 71.8%, and 72.4%; P > 0.05). However, only 37. 0% and 30.4% of oocytes chilled to 4 or 0 degrees C cleaved after fertilization. These results suggest that: (1) chilling bovine oocytes no lower than 24 degrees C does not reduce formation of normal meiotic spindles; (2) however, chilling oocytes to 4 degrees C or lower for as little as 10 min drastically reduces the formation of normal meiotic spindles and of fertilization; (3) the rates of fertilization and cleavage of resultant zygotes mimic that of formation of normal spindles.