The connection between absence-like seizures and hypothermia induced by penicillin: possible implication on other animal models of petit mal epilepsy

In this study we investigated the relationship between penicillin-induced hypothermia and petit mal epilepsy induced by this proconvulsant antibiotic. In order to find a possible dose-dependent relationship, we used two doses: 1500.000 and 1000.000 U/kg b.wt., both known as being sufficient to induce absence-like attacks with subsequent spike and wave discharges (SWD) in electrocorticogram (ECoG). Because of experimental data suggesting penicillin binding to benzodiazepine receptor recognition site, we also studied penicillin-induced changes in body temperature after diazepam pretreatment. Results of this study clearly show that penicillin in doses known to induce petit mal-like epilepsy concomitantly induces statistically significant dose-dependent decrease in body temperature. Pretreatment with diazepam completely prevents both penicillin-induced hypothermia and SWDs. On the other hand, both the diazepam and mixed diazepam + penicillin treatments did not significantly alter body temperature. These results suggest, however, that at least some of the penicillin effects described could be assigned to its binding to the benzodiazepine receptor recognition site at GABA(A) ionophore. This may have an important clinical implication because the inhibitory action of penicillin at the benzodiazepine receptor recognition site could account for the mechanism of penicillin-induced unspecific encephalopathies in humans. The relationship between petit mal epilepsy and hypothermia sheds new light on the action mechanisms of penicillin-induced absence seizures.     

Expression and function of recombinant endothelial nitric oxide synthase gene in canine basilar artery after experimental subarachnoid hemorrhage

BACKGROUND AND PURPOSE: Gene transfer with recombinant viral vectors encoding vasodilator proteins may be useful in therapy of cerebral vasospasm after subarachnoid hemorrhage (SAH). Relaxations mediated by nitric oxide are impaired in cerebral arteries affected by SAH. The present study was designed to determine the effect of SAH on the efficiency of ex vivo adenovirus-mediated gene transfer to canine basilar arteries and to examine whether expression of recombinant endothelial nitric oxide synthase (eNOS) gene may have functional effects on vasomotor reactivity of spastic arteries affected by SAH. METHODS: Replication-deficient recombinant adenovirus vectors encoding bovine eNOS (AdCMVeNOS) and Escherichia coli beta-galactosidase (AdCMVbeta-Gal) genes were used for ex vivo gene transfer. Rings of basilar arteries obtained from control dogs and dogs exposed to SAH were incubated with the vectors in minimum essential medium. Twenty-four hours after gene transfer, expression and function of the recombinant genes were evaluated by (1) histochemical or immunohistochemical staining, (2) beta-galactosidase protein measurement, and (3) isometric tension recording. RESULTS: Transduction with AdCMVbeta-Gal and AdCMVeNOS resulted in the expression of recombinant beta-galactosidase and eNOS proteins mostly in the vascular adventitia. The expression of beta-galactosidase protein was approximately 2-fold higher in SAH arteries than in normal arteries. Endothelium-dependent relaxations caused by bradykinin and substance P were suppressed in SAH arteries. The relaxations to bradykinin were significantly augmented in both normal and SAH arteries after AdCMVeNOS transduction but not after AdCMVbeta-Gal transduction. The relaxations to substance P were augmented by AdCMVeNOS transduction only in normal arteries. Bradykinin and substance P caused relaxations even in endothelium-denuded arteries, when the vessels were transduced with AdCMVeNOS. These endothelium-independent (adventitia-dependent) relaxations to bradykinin observed after AdCMVeNOS transduction were similar between normal and SAH arteries, whereas those to substance P were significantly reduced in SAH arteries compared with normal arteries. CONCLUSIONS: These results suggest that expression of recombinant proteins after adenovirus-mediated gene transfer may be enhanced in cerebral arteries affected by SAH and that successful eNOS gene transfer to spastic arteries can at least partly restore the impaired nitric oxide-mediated relaxations through local (adventitial) production of nitric oxide.     

ATP-dependent glutathione conjugate export pump

KCP4 cells are resistant to cisplatin and have a GS-X pump different from MRP. The GS-X pump was suggested to be involved in reducing the accumulation of cisplatin in KCP-4 cells. The expression of cMOAT was 4-to 6-fold higher in KCP-4 cells and two other cisplatin-resistant human cell lines. It is still not clear whether the cisplatin resistance in KCP-4 cells are attributed to cMOAT. Other members of the MRP/GS-X pump family have been reported. Amino acid sequence of EBCR of rabbit is 91% identical to that of human cMOAT. On the view of cancer chemotherapy, it is very important to understand the structure and function of GS-X pumps since they may be involved in not only drug resistance but also drug metabolism and side effects.     

Seasonal changes in the activity of antioxidative defense in the kidneys of the euthermic ground squirrel (Citellus citellus)

The aim of this work was to determine the activity of the antioxidant enzymes: superoxide dismutase (EC 1.15.1.1; SOD), catalase (EC 1.11.1.6; CAT), glutathione peroxidase (EC 1.11.1.9; GSH-Px), glutathione-S-transferase (EC 2.5.1.18; GST), glutathione reductase (EC 1.6.4.2; GR) and the low molecular mass antioxidants: ascorbic acid (ASA) and vitamin E (vit E) in the kidney of ground squirrels during circannual changes. Keeping the ground squirrel at the temperature of thermic neutrality (30 degrees C) provides a stable euthermic state during the whole year and thus any change is due to the circannual rhythm. The highest specific activity of all examined antioxidative defense enzymes in the kidney was found in the spring, when ground squirrels are seasonally the most active. In the summer, lower specific activity of GSH-Px as well as of SOD and CAT were noted and, when expressed per g wet mass, only a decrease in GSH-Px activity was recorded. In the kidney of ground squirrels kept at 30 degrees C, the lowest specific activity of all examined enzymes was found during the winter and, when expressed per g wet mass, only the SOD activity was lower than in the spring and summer. Higher amounts of vitamins C and E were found in the ground squirrel kidneys in the summer. The results obtained in this work demonstrate that circannual regulation of metabolic activity, which is inherent to seasonal hibernators, is also expressed at the level of antioxidative defense in the kidneys.     

Intake and digestion by Holstein steers consuming diets based on litter harvested after different numbers of broiler growing periods or with molasses addition before deep-stacking

We determined the effects on feed intake and digestibility by Holstein steers of 1) the number of broiler growing periods before litter harvest and dietary level of broiler litter and 2) level of molasses added to broiler litter before deep-stacking. In Exp. 1, eight steers (179+/-7.4 kg average BW) were used in two simultaneous 4 x 4 Latin squares (2 x 4 factorial) with 21-d periods. Broiler litter harvested after one, three, or six 6-wk growing periods (1P, 3P, and 6P, respectively) mixed with .5 or 1.5% BW of ground corn (.5C and 1.5C, respectively) was consumed ad libitum. Bermudagrass hay was fed to 1P, 3P, and 6P steers at .5% BW and was ingested ad libitum by Control steers, along with feeding of .5 or 1.5% BW of corn (DM basis). Broiler litter was 63, 43, and 35% NDF, 2.2, 3.5, and 4.1% N, and 18, 30, and 27% ash for 1P, 3P, and 6P, respectively. Total tract digestibility of NDF was 53.7, 29.4, 50.4, 58.1, 31.3, 30.8, 34.1, and 49.5% (SE 3.50), and digestible OM intake was 2.21, 1.70, 2.27, 2.39, 2.26, 3.18, 2.93, and 3.34 kg/d (SE .160) for .5C-Control, .5C-1P, .5C-3P, .5C-6P, 1.5C-Control, 1.5C-1P, 1.5C-3P, and 1.5C-6P, respectively. In Exp. 2, five steers (228+/-6.0 kg average BW) were used in a 5 x 5 Latin square with 21-d periods. Offered diets were 15% bermudagrass hay and 60% broiler litter (6P of Exp. 1; DM). Molasses was offered at 0, 3.2, or 6.7% of total DM, with the balance of the diet composed of corn. Molasses for two treatments was mixed with litter at meals, whereas for two other treatments molasses and litter were mixed before deep-stacking. Only a few minor treatment effects on intakes and digestibilities occurred. In conclusion, digestible OM intake by growing steers was less for litter harvested after one broiler growing period than after three or six when fed with only .5% BW of corn, although the effect of the number of periods was negligible with corn given at 1.5% BW. Molasses addition before deep-stacking or at meals did not enhance feeding value of litter harvested after six broiler growing periods.     

Change in the functional properties of actin by its glycation in vitro

The influence of glycation (non-enzymatic glycosylation) on structural and functional properties of actin of rabbit skeletal muscle and the effects of the natural anti-glycating dipeptide carnosine were studied. Glucose (0.5 M), fructose (0.5 M), and glyceraldehyde (0.05 M) were used as glycating agents. Marked changes in the structural and functional properties were observed in the presence of glyceraldehyde when high-molecular-weight components appear. This was followed by a decrease in the ability of actin to activate myosin ATPase, to polymerize, and to inhibit DNase I. In the presence of 0.05 M carnosine, the quantity of high-molecular-weight products decreased and myosin ATPase activation was retained. Since muscle tissue contains millimolar quantities of carnosine, glycation of actin associated with changes in its properties is evidently more likely to occur in non-muscle cells.     

Cloning, sequencing, and expression in escherichia coli of OxlT, the oxalate:formate exchange protein of Oxalobacter formigenes

OxlT is the oxalate/formate exchange protein that represents the vectorial component of a proton-motive metabolic cycle in Oxalobacter formigenes. Here we report the cloning and sequencing of OxlT and describe its expression in Escherichia coli. The OxlT amino acid sequence specifies a polytopic hydrophobic protein of 418 residues with a mass of 44,128 daltons. Analysis of hydropathy and consideration of the distribution of charged residues suggests an OxlT secondary structure having 12 transmembrane segments, oriented so that the N and C termini face the cytoplasm. Expression of OxlT in E. coli coincides with appearance of a capacity to carry out the self-exchange of oxalate and the heterologous, electrogenic exchange of oxalate with formate. The unusually high velocity of OxlT-mediated transport is also preserved in E. coli. We conclude that the essential features of OxlT are retained on its expression in E. coli.     

High incidence of relapse after autologous stem-cell transplantation for B-cell chronic lymphocytic leukemia or small lymphocytic lymphoma

BACKGROUND: High-dose therapy followed by autologous stem-cell transplantation (autoSCT) induces complete remissions in the majority of patients with advanced B-cell chronic lymphocytic leukemia or small lymphocytic lymphoma (B-CLL). However, the long-term utility of this therapy for B-CLL is unknown. PATIENTS AND METHODS: Sixteen previously treated patients with B-CLL were transplanted using autologous blood (n = 13) or bone marrow (n = 3). The median age of the patients was 49 f1p4s (range 44-60 years), and the median number of prior chemotherapy regimens was two. Patients were eligible for transplantation if they had chemosensitive disease and no morphologic evidence of malignant cells in the graft. Preparative regimens included cyclophosphamide and total-body-irradiation, with or without cytarabine, or BEAC. RESULTS: All patients engrafted and achieved a complete remission posttransplant. Ten patients were alive at a median of 41 months (range 22-125 months), and five were disease-free. Eight patients have relapsed and six have died (three from progressive malignancy). The projected three-year overall survival, failure-free survival and relapse rates were 68%, 37%, and 56%, respectively. CONCLUSIONS: AutoSCT for advanced B-CLL is associated with a high relapse rate. Whether this therapy can prolong life or produce cures is uncertain.     

Regulation of 11beta-hydroxysteroid dehydrogenase type II in rat adrenocortical cells

The regulation of 11beta-hydroxysteroid dehydrogenase type II (11beta-HSD2) gene expression was studied in primary cultures of rat adrenocortical cells. The protein kinase A (PKA) pathway agonists forskolin, dibutyryl cAMP and ACTH caused a 5-10 fold increase in 11beta-HSD2 mRNA as determined by semiquantitative PCR. The effect of forskolin could be partially inhibited by the addition of the phorbol ester TPA, an activator of the protein kinase C (PKC) pathway. The increase in mRNA encoding 11beta-HSD2 was accompanied by increased synthesis of 11beta-HSD2 as measured by immunoprecipitation of labeled protein. It is concluded that both the PKA and PKC pathways are involved in the regulation of rat adrenal 11beta-HSD2 gene expression.