Base stacking: pH-mediated on-column sample concentration for capillary DNA sequencing

An on-column sample concentration method for capillary-based DNA sequencing was studied. This base-stacking method allows direct injection of unpurified products of dye-primer sequencing reactions onto capillaries without any pretreatment. On-column concentration of DNA fragments is achieved simply by electrokinetic injection of hydroxide ions. A neutralization reaction between these OH- ions and the cationic buffer component Tris+ results in a zone of lower conductivity, within which field focusing occurs. DNA fragments are concentrated at the front of this low-conductivity zone. With sample injection times as long as 360 s at 50 V/cm, resolution could still be restored by the stacking process. Using a 36/47-cm-long uncoated capillary, with poly(dimethylacrylamide) as the separation matrix, and electric field of 160 V/cm, a resolution of at least 0.5 could be generated for fragments up to 650 nucleotides long. Both resolution and signal strength are excellent relative to conventional injection of highly purified samples. No significant degradation of the capillary performance was observed over at least 20 sequencing runs using this new sample injection methods.

Regulation of cyclin-dependent kinase 4 during adipogenesis involves switching of cyclin D subunits and concurrent binding of p18INK4c and p27Kip1

Terminal differentiation of many cell lineages involves an exit from the mitotic cycle and entry into, and maintenance of, a permanent state of G1 arrest. We found that during terminal differentiation of mouse 3T3-L1 preadipocytes, the level of cyclin-dependent kinase 4 (CDK4) remained constant, but the subunit composition of the CDK4 complex underwent a dynamic rearrangement. As 3T3-L1 cells differentiated, the levels of cyclin D1 and cyclin D1-CDK4 complexes declined to negligible levels. Meanwhile, cyclins D2 and D3 levels and their associations with CDK4 increased transiently and persistently, respectively, with cyclin D3 becoming the predominant cyclin partner of CDK4 in mature adipocytes. At least five CDK inhibitors are expressed during the differentiation program of 3T3-L1 cells. Both p15INK4b and p16INK4a continuously declined to undetectable levels immediately after differentiation induction. p21 was transiently expressed during the exit of 3T3-L1 cells from mitotic clonal expansion and then decreased to undetectable levels in mature adipocytes. The level of p27KiP1 and p27-CDK4 complexes remain high during differentiation and in mature adipocytes. Distinctly, there is a remarkable induction of p18INK4c mRNA and protein that was not seen in the closely related nondifferentiating 3T3-C2 cell line, suggesting that p18 induction in 3T3-L1 cells is related to cell differentiation, not cell cycle arrest. The pRb kinase activity of cyclin D3 and CDK4 was not detected in quiescent 3T3-L1 cells and was then induced as the cells entered the mitotic clonal expansion phase. Unexpectedly, cyclin D3 and CDK4 pRb kinase activity remained high after 3T3-L1 cells completed their mitotic division and was still readily detectable in mature adipocytes. Our study reveals an active regulation, rather than passive inhibition, of CDK4 activity during adipocyte differentiation. Two central features of this complex regulation are switching of activating cyclin D subunits and concurrent binding by the p18 and p27 CDK inhibitors.

Mitochondrial dysfunction after experimental traumatic brain injury: combined efficacy of SNX-111 and U-101033E

We recently demonstrated that posttraumatic administration of the N-type calcium channel blocker SNX-111 (S) and a novel blood-brain barrier penetrating antioxidant U-101033E (U), significantly alleviated mitochondrial dysfunction induced by traumatic brain injury (TBI) in rats. The present study was designed to determine whether a combination of S and U, which act on different biochemical mechanisms of secondary brain injury, would be more efficacious than either drug alone. Brain mitochondria from injured and uninjured hemispheres were isolated and examined at 12 h post TBI induced by a severe controlled cortical impact injury. S at 1.0 mg/kg significantly increased both State 3 and 4 rates and produced a slight increase in P/O ratio, and there was virtually no change in RCI. U at 1.0 mg/kg did not show any protection. However, the combined treatment of S at 1.0 mg/kg and U at 1.0 mg/kg eliminated the uncoupling effect of S, and restored not only State 3 rates and P/O ratios but also RCI to near sham values. These results provide further evidence that both reactive oxygen species and perturbation of cellular calcium homeostasis participate in the pathogenesis of TBI-induced mitochondrial dysfunction, and support the idea of using combined therapy with lower drug doses.

Difference in topology and numbers of barosensitive catecholaminergic and cholinergic neurons in the medulla between SHR and WKY rats

We hypothesized that there may be a significant difference in the neuronal composition of the baroreceptor reflex pathway between normotensive Wistar Kyoto (WKY) and spontaneously hypertensive SHR rats. Using the double-immunoreactive (IR) method, the topology and numbers of barosensitive neurons that contain glutamate (Glu), glutamic acid decarboxylase (GAD), tyrosine hydroxylase (TH), phenylethanolamine N-methyltransferase (PNMT) and choline acetyltransferase (ChAT) were compared between the two strains. The control rats were sham-operated only for cannulation of the trachea and femoral artery/vein. The test rats were injected with the pressor agent phenylephrine to raise blood pressure and stimulate arterial baroreceptors. In both the control and test experiments, the c-Fos/Glu-, GAD-, TH- and PNMT-IR neurons were found in the nucleus tractus solitarii (NTS) and ventrolateral medulla (VLM), while the FosB/ChAT-IR neurons were found in the NTS, dorsal motor nucleus of the vagus (DMX) and nucleus ambiguus (AMB). In the control experiment, no significant difference in numbers was recognized in any of the double-IR neurons between the two strains. In the test experiment, the numbers of FosB/ChAT-IR neurons in the NTS, DMX and AMB were significantly smaller in SHR than in WKY. The numbers of c-Fos/TH-IR neurons in the caudal VLM were significantly larger in SHR than in WKY. These results suggest that a smaller number of barosensitive cholinergic neurons in the DMX and AMB in SHR causes the weaker baroreceptor-cardiac vagal reflex in SHR, and that a larger number of barosensitive catecholaminergic neurons in the caudal VLM in SHR are involved in the stronger baroreceptor-vasopressin reflex in SHR.

Human CUL-1, but not other cullin family members, selectively interacts with SKP1 to form a complex with SKP2 and cyclin A

The budding yeast gene product, CDC53p, forms E3-like SCF complexes with SKP1 and F-box-containing proteins to mediate the ubiquitin-dependent degradation of G1 cyclins and cyclin-dependent kinase (CDK) inhibitors. Cdc53 represents a multigene family, the human homologues of which, the cullin family, include at least six distinct members. We have found that human cullin 1, but not the other closely related cullins 2, 3, 4A, and 5, selectively interacts with human SKP1. This CUL1-SKP1 interaction is mediated by the NH2-terminal domains of both proteins, and the association appears to be required for the interaction of CUL1 with SKP2, an essential element of the S-phase cyclin A-CDK2 kinase. In an asynchronous population of dividing cells, a minor amount of CUL1 specifically associates with cyclin A but not with other cyclins or CDK inhibitors. The steady-state levels of both CUL1 and SKP1 as well as their association with one another remain relatively constant throughout the cell cycle and in postmitotic cells. Our findings indicate that the SCF pathway, although similarly used by the mammalian cullin 1, is not shared by other cullin members. This implies that most cullins may use a SKP1/F-box-independent pathway to facilitate protein degradation.

Effects of guanine nucleotide depletion on cell cycle progression in human T lymphocytes

Depletion of guanine nucleotide pools after inhibition of inosine monophosphate dehydrogenase (IMPDH) potently inhibits DNA synthesis by arresting cells in G1 and has been shown to induce the differentiation of cultured myeloid and erythroid cell lines, as well as chronic granulocytic leukemic cells after blast transformation. Inhibitors of IMPDH are also highly effective as immunosuppressive agents. The mechanism underlying these pleiotropic effects of depletion of guanine nucleotides is unknown. We have examined the effects of mycophenolic acid (MPA), a potent IMPDH inhibitor, on the cell cycle progression of activated normal human T lymphocytes. MPA treatment resulted in the inhibition of pRb phosphorylation and cell entry into S phase. The expression of cyclin D3, a major component of the cyclin-dependent kinase (CDK) activity required for pRb phosphorylation, was completely abrogated by MPA treatment of T cells activated by interleukin-2 (IL-2) and leucoagglutinin (PHA-L), whereas the expression of cyclin D2, CDK6, and CDK4 was more mildly attenuated. The direct kinase activity of a complex immunoprecipitated with anti-CDK6 antibody was also inhibited. In addition, MPA prevented the IL-2-induced elimination of p27(Kip1), a CDK inhibitor, and resulted in the retention of high levels of p27(Kip1) in IL-2/PHA-L-treated T cells bound to CDK2. These results indicate that inhibition of the de novo synthesis of guanine nucleotides blocks the transition of normal peripheral blood T lymphocytes from G0 to S phase in early- to mid-G1 and that this cell cycle arrest results from inhibition of the induction of cyclin D/CDK6 kinase and the elimination of p27(Kip1) inhibitory activity.

Coupled transcriptional and translational control of cyclin-dependent kinase inhibitor p18INK4c expression during myogenesis

Terminal differentiation of many cell types involves permanent withdrawal from the cell division cycle. The p18INK4c protein, a member of the p16/INK4 cyclin-dependent kinase (CDK) inhibitor family, is induced more than 50-fold during myogenic differentiation of mouse C2C12 myoblasts to become the predominant CDK inhibitor complexed with CDK4 and CDK6 in terminally differentiated myotubes. We have found that the p18INK4c gene expresses two mRNA transcripts--a 2.4-kb transcript, p18(L), and a 1.2-kb transcript, p18(S). In proliferating C2C12 myoblasts, only the larger p18(L) transcript is expressed from an upstream promoter. As C2C12 cells are induced to differentiate into permanently arrested myotubes, the abundance of the p18(L) transcript decreases. The smaller p18(S) transcript expressed from a downstream promoter becomes detectable by 12 h postinduction and is the predominant transcript expressed in terminally differentiated myotubes. Both transcripts contain coding exons 2 and 3, but p18(L) uniquely contains an additional noncoding 1.2-kb exon, exon 1, corresponding exclusively to the 5' untranslated region (5' UTR). The expression pattern of the shorter p18(S) transcript, but not that of the longer p18(L) transcript, correlates with terminal differentiation of muscle, lung, liver, thymus, and eye lens cells during mouse embryo development. The presence of the long 5' UTR in exon 1 attenuated the translation of p18(L) transcript, while its absence from the shorter p18(S) transcript resulted in significantly more efficient translation of the p18 protein. Our results demonstrate that during terminal muscle cell differentiation, induction of the p18 protein is regulated by promoter switching coupled with translational control.

ARF promotes MDM2 degradation and stabilizes p53: ARF-INK4a locus deletion impairs both the Rb and p53 tumor suppression pathways

The INK4a-ARF locus encodes two unrelated proteins that both function in tumor suppression. p16INK4 binds to and inhibits the activity of CDK4 and CDK6, and ARF arrests the cell cycle in a p53-dependent manner. We show here that ARF binds to MDM2 and promotes the rapid degradation of MDM2. This interaction is mediated by the exon 1beta-encoded N-terminal domain of ARF and a C-terminal region of MDM2. ARF-promoted MDM2 degradation is associated with MDM2 modification and concurrent p53 stabilization and accumulation. The functional consequence of ARF-regulated p53 levels via MDM2 proteolysis is evidenced by the ability of ectopically expressed ARF to restore a p53-imposed G1 cell cycle arrest that is otherwise abrogated by MDM2. Thus, deletion of the ARF-INK4a locus simultaneously impairs both the INK4a-cyclin D/CDK4-RB and the ARF-MDM2-p53 pathways.

T-loop deletion of CDC2 from breast cancer tissues eliminates binding to cyclin B1 and cyclin-dependent kinase inhibitor p21

The eukaryotic cell cycle is regulated by a highly conserved family of protein kinases, the cyclin-dependent kinases (CDKs). Monomeric free CDKs do not possess enzymatic activity, largely due to the steric hindrance caused by the T-loop at the entrance of the catalytic cleft, making ATP inaccessible to the substrate. Binding of a cyclin, primarily to the NH2-terminal lobe of the CDK that surrounds the PSTAIRE helix, induces a large conformational change in the PSTAIRE helix of the CDK and also causes the T-loop to move out of the way of the catalytic cleft. We identified from breast cancer tissues a novel variant of human CDC2, termed CDC2deltaT, that lacks 171 nucleotides corresponding to 57 amino acids, which compose most of the T-loop. CDC2deltaT was detected in 10 of 14 breast cancer tissues analyzed, whereas it was not detectable in diploid human fibroblast cell lines or in interleukin 2-stimulated normal human lymphocytes. CDC2deltaT protein is unable to complex with cyclin B1 and lacks histone H1 kinase activity. CDC2deltaT also fails to bind to the CDK inhibitor p21. These results indicate that the T-loop not only plays a key role in keeping a free CDK in its inactive state but also in facilitating CDK activation by promoting cyclin binding.

Suppression of cell transformation by the cyclin-dependent kinase inhibitor p57KIP2 requires binding to proliferating cell nuclear antigen

Proper control of the mammalian cell cycle requires the function of cyclin-dependent kinase (CDK) inhibitors. The p21 family currently includes three distinct genes, p21, p27(Kip1), and p57(Kip2), that share a common N-terminal domain for binding to and inhibiting the kinase activity of CDK-cyclin complexes. The p21 protein also binds to proliferating cell nuclear antigen (PCNA) through a separate C-terminal domain affecting DNA replication and repair. The p27 and p57 proteins also each contain unique C-terminal domains whose functions are unknown. Here we show that the human p57 protein, like p21, contains a PCNA-binding domain within its C terminus that, when separated from its N-terminal CDK-cyclin binding domain, can prevent DNA replication in vitro and S phase entry in vivo. Disruption of either CDK/cyclin or PCNA binding partially reduced p57's ability to suppress myc/RAS-mediated transformation in primary cells, while loss of both inhibitory functions completely eliminated p57's suppressive activity. Thus, control of cell cycle and suppression of cell transformation by p57 require both CDK and PCNA inhibitory activity, and disruption of either or both functions may lead to uncontrolled cell growth.

Development of a method for quantitation of retinol and retinyl palmitate in human serum using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry

A method for the quantitative analysis of the vitamin A compounds all-trans-retinol and all-trans-retinyl palmitate was developed using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (APCI-LC-MS). Unlike previous quantitative mass spectrometric methods for vitamin A, HPLC separations were carried out using a C30 reversed-phase column instead of GC separation. Because no sample hydrolysis or derivatization was necessary, retinyl palmitate was preserved for analysis instead of being hydrolyzed to retinol. Human serum was analyzed following simple hexane extraction without saponification or any additional purification. A comparison of APCI and electrospray ionization showed that only APCI produced a linear response over all four orders of magnitude of retinol and three orders of magnitude of retinyl palmitate concentrations. Selected ion monitoring of the fragment ion of m/z 269 was used for APCI quantitation of both retinol and retinyl palmitate, since it was the base peak and the only abundant ion in the mass spectra of both compounds and the internal standard, retinyl acetate. The ion of m/z 269 corresponded to loss of water, loss of palmitic acid, or elimination of acetic acid from the protonated molecules of retinol, retinyl palmitate and retinyl acetate, respectively. The limit of detection of APCI-LC-MS for all-trans-retinol and all-trans-retinyl palmitate was determined to be approximately 34 fmol/microliter and 36 fmol/microliter (0.670 pmol all-trans-retinol and 0.720 pmol all-trans-retinyl palmitate injected in 20 microliters on-column), respectively. The limit of quantitation was approximately 500 fmol/microliter and 250 fmol/microliter (10 pmol and 5 pmol injected in 20 microliters on-column) for retinol and retinyl palmitate, respectively.

Amelioration of mitochondrial function by a novel antioxidant U-101033E following traumatic brain injury in rats

In the present study, a severe traumatic brain injury (TBI) was produced over the right parietal cortex of rats using the controlled cortical impact injury (CCII) model. TBI perturbed calcium homeostasis and impaired electron transfer and energy coupling activities of forebrain mitochondria isolated from injured hemispheres with a maximal injury at 12-72 h. Efficacy of the blood-brain barrier penetrating antioxidant U-101033E on TBI-induced mitochondrial impairment was evaluated. In the dose-response experiment, two i.v. boluses (vehicle or 1-10 mg/kg of U-101033E) were administered at 5 min and 2h post-TBI. Forebrain mitochondria from each hemisphere were examined at 12 h post-injury. With respect to forebrain mitochondrial dysfunction, the drug showed a bell-shaped dose-response curve with an optimal dose of 3 mg/kg (n = 5, p < 0.05 vs. vehicle). In the time-course experiment, two i.v. boluses of 3 mg U-101033E/kg (the optimal dose) were given at 5 min and 2 h post-injury and forebrain mitochondria were examined at 6 h-14 days post-injury. U-101033E significantly restored electron transfer, energy coupling capacity, and Ca2+ transport capacity during 6 h to 14 days post-injury. Our data indicate that the antioxidant U-101033E administered post-injury at proper dosage can effectively restore TBI-induced mitochondrial dysfunction and support the contention that oxidative stress plays an important role in the pathogenesis of TBI.

[Observation on the changes of lipid peroxidation in neonates with sclerema]

Thirty-six hospitalized newborn infants with sclerema (case group), which were divided into mild group(n = 18) and severe group(n = 18), and 28 normal neonates (normal control group) were selected to measure the changes of blood lipid peroxidation (LPO) and superoxide dismutase(SOD) so as to study the role of free radicals and lipid peroxide injury the pathogenesis of the entity. The results showed that the plasma LPO contents were significantly increased and SOD were significantly decreased in the case group when compared with those in the normal group (P < 0.01). The plasma LPO was significantly higher and SOD activity was significantly lower in the severe group than those in the mild group (P < 0.01). The study indicates that the free radicals produced in sclerema neonatorum are great in amount and suggests that free radicals possibly participate in the pathogenesis of the disease.

Differential effects of tumor necrosis factor-alpha and interleukin-1 on 3 beta-hydroxysteroid dehydrogenase/delta 5-->delta 4 isomerase expression in mouse Leydig cells

Immune-endocrine interactions are important to the regulation of Leydig cell steroidogenesis. We have shown previously that both tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1-beta) inhibit 8-bromo-cAMP-(8-Br-cAMP)-stimulated steroidogenesis in mouse Leydig cells. TNF and IL-1 both inhibit cAMP-stimulated testosterone production as well as mRNA and protein levels of cholesterol side chain cleavage enzyme (P450scc) and 17 alpha-hydroxylase/C17,20 lyase (P450c17) in mouse Leydig cells. Neither TNF nor IL-1 affects basal levels of P450scc mRNA and protein. In the present study, we tested the effects of TNF and IL-1 on basal testosterone production and 8-Br-cAMP-stimulated 3 beta-hydroxysteroid dehydrogenase/delta 5-->delta 4 isomerase (3 beta HSD) expression in Leydig cells. Purified and macrophage-depleted Leydig cells were cultured for 5 d with daily changes of media, and then treated with increasing concentrations of recombinant mouse TNF or IL-1 in the presence or absence of 8-Br-cAMP (50 microM) for 24 h. The media were collected for testosterone RIA and RNA and protein were extracted from cells. Basal testosterone production was inhibited by TNF, but not IL-1. Treatment of Leydig cells with 8-Br-cAMP alone caused a marked increase in 3 beta HSD mRNA, and protein levels. Both TNF and IL-1 inhibited cAMP-stimulated 3 beta HSD mRNA and protein levels, but only TNF inhibited basal 3 beta HSD expression. These results demonstrate that TNF and IL-1 have different effects on basal steroidogenesis in Leydig cells and suggest that TNF-mediated inhibition of basal testosterone production may be owing to the inhibition of basal 3 beta-HSD expression in Leydig cells.

[Studies on hydrolysis of anti-HRV IgY and its oral passive immunity effect to human rotavirus]

In this paper, hens of fine breed were immunized with human rotavirus (HRV), and the anti-HRV IgY was isolated and purified from their eggs collected daily. In addition, the resistance of anti-HRV IgY to hydrolysis of gastric juice and proteases in human digestive tract, the safety of IgY and the effectiveness of IgY in clinical use were observed as well. The results showed that anti-HRV IgY has a fairly good resistance to gastroinstestinal proteases. The safety of using anti-HRV IgY was affirmed by oral administration to mice of a solution of IgY. In clinical test the IgY has been proved to be anti-HRV and, therefore, effective against infections of infant diarrhea induced by HRV.

Elevation of an endogenous inhibitor of nitric oxide synthase in diabetic rat serum

AIM

To study the endogenous inhibitor of NO synthase NG,NG-dimethyl-arginine (DMA) in the diabetic rat serum.

METHODS

In streptozocin-induced diabetic rats, the serum DMA level and endothelium-dependent vasorelaxation to acetylcholine (ACh) were determined.

RESULTS

The serum DMA concentration was increased in the diabetic rats compared with their age-matched controls (5.4 +/- 1.0 vs 0.7 +/- 0.3 mumol.L-1, P < 0.01). The serum malondialdehyde (MDA) level was also increased in the diabetic rats compared with controls (2.5 +/- 0.3 vs 1.5 +/- 0.1 mumol.L-1, P < 0.01). Vasodilator response to ACh was impaired in diabetic thoracic aortas, which was improved by preincubation with L-arginine 1 mmol.L-1.

CONCLUSION

Hyperglycemia elevated the endogenous DMA content, which contributed to attenuated endothelium-dependent vasorelaxation in streptozocin-induced diabetic rats.

Extracellular cysteines of the corticotropin-releasing factor receptor are critical for ligand interaction

The corticotropin-releasing factor receptor (CRF-R) contains six conserved cysteines in its amino-terminal domain (C30, C44, C54, C68, C87, and C102) and one cysteine in its first and second extracellular loops (C188 and C258, respectively). Additionally, several other cysteines are located in the transmembrane domains (C128, C211, C233, and C364) and first intracellular loop (C150). Reduction of disulfide bonds with DTT decreased CRF binding to detergent-solubilized membranes, suggesting an important role for disulfide bonds in ligand recognition. Therefore, site-directed mutagenesis was used to introduce single and paired Cys (C) to Ser (S) or Ala (A) mutations. A silent nine amino acid tag from c myc was introduced in the amino terminus of the mouse CRF-R. With the exception of C258S and C188S/C258S mutations, all C to S or to A receptor mutants had good surface expression that was at least 52.5% of control. C30S, C54S, and C30S/C54S mutations had good CRF binding and CRF-stimulated cAMP accumulation. No CRF binding was detected for the C44S, C68S, C87S, C102S, C188S, C258S, C30S/C44S, C30S/C68S, C54S/C68S, C87S/C102S, and C188S/C258S mutants, while CRF-stimulated cAMP accumulation occurred with high EC50 values. In particular, receptors carrying double mutations, C44S/C102S and C68S/C87S, had an improved signaling property as compared to receptors carrying the respective single cysteine mutations. These data, together with the effects of DTT on CRF binding, indicate that disulfide bridges are important for receptor functions. Functional data from single and paired cysteine mutations suggest potential pairings between C44 and C102, C68 and C87, and C188 and C258 that are critical for ligand-receptor interactions.

Parathyroid tumor suppressor on 1p: analysis of the p18 cyclin-dependent kinase inhibitor gene as a candidate

Loss of chromosome arm 1p DNA is the most common molecular defect thus far observed in human parathyroid adenomas, suggesting that 1p is the location of a putative tumor suppressor gene (or genes) whose inactivation contributes frequently to parathyroid tumorigenesis. To narrow the genomic location of this tumor suppressor gene, we analyzed 25 sporadic parathyroid adenomas for allelic loss of polymorphic DNA loci on chromosome 1 using 11 microsatellite markers not previously scored for this set of tumors. Allelic loss on chromosome arm 1p DNA was observed in 8 of 25 adenomas. Marker deletion patterns showed some complexity, with the regions most commonly deleted in these tumors being 1p36 and 1p35-p31. The 1p35-p31 region contains an excellent candidate tumor suppressor gene, p18, whose product is a cell cycle regulator that inhibits the cyclin D1-associated kinase CDK6. Given that cyclin D1 is a parathyroid oncogene, inactivation of an inhibitor of cyclin D1 function, like p18, might also cause excessive parathyroid growth. To examine the involvement of p18 in parathyroid tumorigenesis, we analyzed 25 parathyroid adenomas for mutations of the p18 coding exons by single strand conformational polymorphism analysis and sequencing. No point mutations were found in any of the 25 adenomas. These observations indicate that inactivating mutation of the p18 gene occurs uncommonly, if at all, in parathyroid adenomas. In addition, the data raise the important possibility that more than a single tumor suppressor gene on 1p could contribute to parathyroid neoplasia.

Trimeresurus stejnegeri snake venom plasminogen activator. Site-directed mutagenesis and molecular modeling

The specific plasminogen activator from Trimeresurus stejnegeri venom (TSV-PA) is a serine proteinase presenting 23% sequence identity with the proteinase domain of tissue type plasminogen activator, and 63% with batroxobin, a fibrinogen clotting enzyme from Bothrops atrox venom that does not activate plasminogen. TSV-PA contains six disulfide bonds and has been successfully overexpressed in Escherichia coli (Zhang, Y., Wisner, A., Xiong, Y. L., and Bon, C. (1995) J. Biol. Chem. 270, 10246-10255). To identify the functional domains of TSV-PA, we focused on three short peptide fragments of TSV-PA showing important sequence differences with batroxobin and other venom serine proteinases. Molecular modeling shows that these sequences are located in surface loop regions, one of which is next to the catalytic site. When these sequences were replaced in TSV-PA by the equivalent batroxobin residues none generated either fibrinogen-clotting or direct fibrinogenolytic activity. Two of the replacements had little effect in general and are not critical to the specificity of TSV-PA for plasminogen. Nevertheless, the third replacement, produced by the conversion of the sequence DDE 96a-98 to NVI, significantly increased the Km for some tripeptide chromogenic substrates and resulted in undetectable plasminogen activation, indicating the key role that the sequence plays in substrate recognition by the enzyme.

[Immuno-enhancing effect of gebie oral liquid on mice]

Gebie Oral Liquid can increase the weight of thymus and spleen of the mouse, damaged by prednisone and cytoxan, enhance the phagocytosis of monocytes and DHT, and promote the blastogenesis of splenic lymphocytes as well as the activity of NK cells.

Mitochondrial dysfunction after experimental and human brain injury and its possible reversal with a selective N-type calcium channel antagonist (SNX-111)

We have recently demonstrated in a rat model that traumatic brain injury induces perturbation of cellular calcium homeostasis with an overload of cytosolic calcium and excessive calcium adsorbed on the mitochondrial membrane, consequently the mitochondrial respiratory chain-linked oxidative phosphorylation was impaired. We report the effect of a selective N-type calcium channel blocker, SNX-111 on mitochondrial dysfunction induced by a controlled cortical impact. Intravenous administration of SNX-111 at varying times post injury was made. The concentration titration profile revealed SNX-111 at 4 mg kg-1 to be optimal, and the time window to be administration at 4 h post-injury, in line with that reported on the effect of SNX-111 in experimental stroke. Under optimal conditions, SNX-111 significantly improved the mitochondrial respiratory chain-linked functions, such as the electron transfer activities with both succinate and NAD-linked substrates, and the accompanied energy coupling capacities measured as respiratory control indices (RCI) and ATP synthesis (P/O ratio), and the energy linked Ca2+ transport. In order to assess the applicability of these data to the clinical setting, we have initiated studies with brain tissue which has to be resected during surgical treatment. Five patients suffered from brain trauma, one from intracranial hypertension due to stroke (noninfarcted tissue was taken), and one from epilepsy. Our data revealed that brain mitochondria derived from the patient with intracranial hypertension and the patient with epilepsy were tightly coupled with good respiratory rates with glutamate and malate as substrates, and high P/O ratios. The rates of respiration and ATP synthesis were severely impaired in the brain mitochondria isolated from traumatized patients. These results indicate that investigation of brain mitochondrial functions can be used as a measure for trauma-induced impairment of brain energy metabolism. The time window for the effect of SNX-111 in mitochondrial function and the (preliminary) similarity between mitochondrial dysfunction in experimental animals and humans make the drug appear to be well suited for clinical trials in severe head injury.

Acetaminophen cytotoxicity in mouse eye: mitochondria in anterior tissues are the primary target

Acetaminophen (APAP) injected into C57BL/6 mice (cytochrome P450 inducer-responsive strain) that had been pretreated with b-naphthoflavone (BNF) produced ocular tissue damage, including cataract. Our previous histocytochemical studies showed that tissue damage spread in association with the flow of the aqueous humor and appeared first in the ciliary epithelium, followed by the iris and corneal endothelium and, finally, the lens. The neural retina, retinal pigmented epithelium and choroid remained unaffected. A close examination of the affected tissues indicated that mitochondria are the primary target of APAP cytotoxicity. In order to investigate whether the respiratory capacity of mitochondria is more sensitive to APAP cytotoxicity than mitochondrial morphology, we determined in this work the oxygen uptake by eye tissues dissected from BNF-pretreated and APAP-injected C57BL/6 mice. Oxygen uptake by the ciliary body/iris decreased about 60% at 90 min and 85% at 120 min after APAP administration. The oxygen uptake was inhibited about 50% by 10 microM rotenone. Since the earliest sign of mitochondrial damage was noted at 120 min, the result indicates that mitochondrial energy dysfunction precedes morphological alterations. It was also observed that oxygen uptake by the retina remained unaffected at least for 120 min after APAP administration; therefore, it is evident that the retina and, possibly, other posterior tissues as well are resistant to APAP cytotoxicity, not only in their morphology but, also, in their capacity of mitochondrial energy metabolism.

Purification and characteristics of recombinant mouse metallothionein-I from Escherichia coli

The mouse metallothionein-I (mMT-I) cDNA was amplified by polymerase chain reaction (PCR), inserted into vector pGEX-4T-1, and expressed in Escherichia coli as a carboxyl terminal extension of the 26-kDa glutathione-S-transferase (GST). Analyzed by SDS-PAGE, the amount of the expressed fusion protein GST-MT was over 50% of total cellular proteins. After the fusion protein had been digested with thrombin on a Glutathione-Sepharose 4B affinity chromatography column, recombinant mMT-I was purified by gel filtration on Sephadex G50. The results of molecular mass, amino acid composition and sequence of 10 amino acids at the N-terminus of the recombinant mMT-I demonstrate that the purified protein is the one we desired. The ratios of metal:protein and thiol:protein are the same as those of wild-type MT. The half-dissociation pHs of Cd, Cu, and Zn from recombinant mMT-I were 3.57, 1.40, and 5.20, respectively, which are in agreement with those from native rabbit MT-I. The ultraviolet absorbance and circular dichroism (CD) spectra at pH 8.0 and pH 2.0 were all similar to those of native MT, indicating that they have the same metal-thiolate structure even though six amino acid residues have been added at the N-terminus of the recombinant protein.