Surgical aspects of renal transplantation in children

Incubation of the acutely dissected rat hippocampal slices in calcium-containing media resulted in spontaneous activation-translocation of classical PKC isoforms and their subsequent (especially gamma-type) proteolytic degradation. These changes were blocked by calpain inhibitor MDL 28 170 in 100 microM concentration. Rat hippocampal slices were metabolically prelabelled with 32Pi and stimulated with NMDA/glycine, depolarization or phorbol dibutyrate (PDBu) treatment. The basal phosphorylation of specific PKC substrates (MARCKS, neuromodulin and neurogranin) was significantly reduced in non-stimulated slices by MDL pretreatment. In contrast, only the slices where calpain activity was inhibited responded to further NMDA or phorbol dibutyrate stimulation by a substantial increase of PKC-dependent protein phosphorylation. It is concluded that the PKC phosphorylation system is severely affected by non-specific activation and a subsequent, calpain-dependent proteolysis in the acutely prepared hippocampal slices. Calpain inhibition by 100 microM MDL partially prevented these changes and increased stimulus-dependent phosphorylation of PKC-specific protein substrates.     

Quantitation of age-related mitochondrial DNA deletions in rat tissues shows that their pattern of accumulation differs from that of humans

We studied the postnatal development of the release of acetylcholine (ACh) and of presynaptic, release-inhibiting muscarinic autoreceptors in the rat hippocampus. To this end, hippocampal slices (350 microns thick) from rats of various postnatal ages (postnatal day 3 [P3] to P16) were preincubated with [3H]choline and stimulated twice (S1, S2: 360 pulses, 2 ms, 3 Hz, 60 mA) during superfusion with physiological buffer containing hemicholinium-3 (10 microM). In parallel, the activities of hemicholinium-sensitive high-affinity choline uptake (HACU, in synaptosomes) and of choline acetyltransferase (ChAT, in crude homogenates) were determined as markers for the cholinergic ingrowth. In hippocampal slices preincubated with [3H]choline, the electrically evoked overflow of 3H at S1 increased from 0.11 (P3) to 0.81% of tissue 3H (P16), the latter value being still much lower than that of hippocampal slices from adult rats (2.89% of tissue 3H). Already at P3 the evoked overflow of 3H was Ca(2+)-dependent and sensitive to tetrodotoxin, indicating an action potential-evoked exocytotic mechanism of ACh release. The muscarinic agonist oxotremorine (1 microM) significantly inhibited the evoked ACh release in hippocampal slices with increasing effectivity from P4 to P16; no significant effect was detectable at P3. The ACh esterase inhibitor physostigmine and the muscarinic antagonist atropine (1 microM, each) exhibited significant inhibitory and facilitatory effects, respectively, only at P15-16. The specific activities of both hippocampal HACU (pmoles/mg protein/min) and ChAT (nmoles/mg protein/min) continuously increased from P3 to P16. It is concluded (1) that cholinergic nerve terminals arriving at the hippocampal formation during postnatal ingrowth are already endowed with the apparatus for action potential-induced, Ca(2+)-sensitive (exocytotic) ACh release; (2) that, in contrast, the expression of presynaptic muscarinic autoreceptors on these cholinergic axon terminals is delayed; and (3) that autoinhibition due to endogenous ACh develops even later, probably when the density of presynaptic terminals in the hippocampus and hence, the concentration of released ACh has reached a suprathreshold value.     

Loss of biological activity due to Glu-->Arg mutation at residue 11 of the B subunit of cholera toxin

PURPOSE: To determine the maximum tolerated dose, toxicities, and potential antitumor activity of edatrexate (E), an antifolate agent with enhanced in vitro antitumor activity as compared with methotrexate (M), when given in combination with vinblastine, doxorubicin, cisplatin, and filgrastim (G-CSF) to patients with advanced malignancies. PATIENTS AND METHODS: Thirty-seven patients with advanced malignancies were treated with escalating doses of edatrexate in combination with vinblastine (V), doxorubicin (A), cisplatin (C), and filgrastim (EVAC/G-CSF) following three different subsequently developed schedules. Schedule 1 was patterned after the MVAC regimen, a combination chemotherapy program with activity against different epithelial malignancies, and consisted of E, 40 mg/m2/day, days 1/15/22; V, 3 mg/m2/day, days 2/15/22; A, 30 mg/m2/ day, day 2; C, 70 mg/m2/day, day 2; repeated every 28 days. Schedules 2 and 3 were designed to avoid observed dose-limiting toxicity on schedule 1 consisting of transient elevation of serum creatinine levels and delayed myelosuppression. Schedule 2 consisted of E, 40 or 60 mg/ m2/day, days 1 and 15; V, 3 mg/m2/day, days 2 and 15; A, 30 mg/m2/day, day 2; C, 30 mg/m2/day, days 1 and 2; cycled every 28 days. Schedule 3 consisted of E, 60 to 120 mg/m2/day, day 1; V, 3 mg/m2/day, day 2; A, 30 mg/m2/day, day 2; C, 30 mg/m2/day, days 1 and 2; cycled every 21 days. Filgrastim 5 micrograms/kg/day was given to all patients subcutaneously until the absolute neutrophil count was greater than 10,000/microL postnadir. Three patients were treated on schedule 1, 10 on schedule 2 (four at an E dose of 40 mg/m2/day and six at an E dose of 60 mg/m2/day), and 24 on schedule 3 (six at each of the following E dosages: 60, 80, 100, and 120 mg/m2/day). RESULTS: Dose-limiting toxicities of grade 3 to 4 leukopenia and transient elevation of serum creatinine values were observed in two of three patients treated on schedule 1. A dose-limiting toxicity of grade 3 to 4 leukopenia was noted in two of six patients treated on schedule 2 at an edatrexate dose of 60 mg/m2/day. Two of six patients treated on schedule 3 at an edatrexate dose of 120 mg/m2/day had a dose-limiting toxicity of grade 3 stomatitis (one patient) and grade 3 cytopenia (one patient). Nineteen of 37 patients with evaluable or measurable disease had a response to treatment (response rate 51%, 95% confidence intervals = 35%-67%). Nine of 15 patients with metastatic non-small cell lung cancer responded, including one complete remission (response rate 60%, confidence intervals = 35%-85%). A median survival of 517 days (confidence interval = 163-808 days) and a 1-year survival rate of 60% (confidence interval = 35%-85%) was seen in patients with advanced non-small cell lung cancer. CONCLUSIONS: The maximum tolerated dose and the recommended phase II dose of edatrexate is 100 mg/m2/day when administered as part of the EVAC/G-CSF program following schedule 3. Promising antineoplastic activity against non-small cell lung carcinomas was observed, and a phase II study is planned.     

The non-competitive AMPA antagonist LY 300168 (GYKI 53655) attenuates AMPA-induced hippocampal injury in neonatal rodents

In contrast with the neuroprotective efficacy of competitive and non-competitive N-methyl-D-aspartate (NMDA) antagonists versus NMDA neurotoxicity, reported neuroprotective effects of non-NMDA antagonists in limiting alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) toxicity have been less robust. We tested the effect of the non-competitive AMPA receptor antagonist LY 300168 (GYKI 53655; E. Lilly) (0.25 or 2.5 mg/kg per dose i.p. x 3 doses vs. vehicle) on AMPA-induced excitotoxic injury in postnatal day 7 (P7) rats. To assess specificity, we tested the effect of LY 300168 (2.5 mg/kg per dose x 3 doses) on NMDA-induced excitotoxic injury. P7 rats received right intrahippocampal injections of either (S)-AMPA (2.5 nmol, n = 67) or NMDA (12.5 nmol, n = 11). Injection of AMPA resulted in right hippocampal atrophy with pyramidal cell loss. LY 300168 treatment produced dose-dependent attenuation of AMPA-induced right hippocampal injury; based on comparisons with left hippocampal volumes, 2.5 nmol AMPA resulted in 42 +/- 3% (mean +/- SEM) right hippocampal volume loss in controls, but only 10 +/- 5% after LY 300168 2.5 mg/kg per dose (P < 0.001; ANOVA). LY 300168 had no effect on NMDA-induced hippocampal injury. The data support the hypothesis that drugs that allosterically regulate AMPA receptor activity can modulate the response of immature brain to AMPA-mediated injury.     

Dual-earner families: the importance of work stress and family stress for psychological well-being

The effect of neonatal hippocampal lesions on behavioral sensitivity to amphetamine (AMPH) and dopamine (DA) release in the nucleus accumbens (NAc) were examined. The ventral hippocampus was damaged bilaterally by ibotenic acid on postnatal day 7 (PD7). Spontaneous exploration and AMPH-stimulated locomotor activity were examined on postnatal day 35 (PD35) and day 56 (PD56). Extracellular DA, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) were sampled using in vivo microdialysis while simultaneously AMPH-stimulated locomotion was examined in freely moving rats on PD56. Spontaneous exploration increased in rats with hippocampal lesions relative to controls on PD56 but not PD35. AMPH (0, 0.187, 0.375, 0.75, 1.5, and 3 mg/kg) enhanced locomotion dose-dependently in both control and lesioned groups. Locomotor activity was higher in lesioned rats than controls following AMPH at the dose of 0.75 mg/kg on PD35 and at the doses of 1.5 and 3.0 mg/kg on PD56. The basal level of DA in the NAc was not different between the hippocampal and control groups. AMPH (1.5 mg/kg) induced hyperlocomotion in lesioned rats relative to controls. DA release in the NAc for both groups was enhanced following injections of AMPH. However, neonatal hippocampal lesions had no further enhancement on AMPH-stimulated release of DA as compared to the control group. The levels of DOPAC and HVA in the NAc were altered by AMPH but not lesions. The level of 5-HIAA was not influenced by either lesions or AMPH. The results of neonatal lesion-induced hyperlocomotion suggest that an emergence of behavioral hyperresponsiveness to AMPH was dependent on an interaction of lesions, age of examination, and dose of the drug. A dissociation between the effect of AMPH on lesion-enhanced hyperlocomotion and a lack of a lesion-enhanced DA release in the NAc suggest that presynaptic release of DA had no major contribution to lesion-enhanced DA transmission in the mesolimbic DA system.     

MRI of hyperpolarized 3He gas in human paranasal sinuses

Relapsed or refractory adult acute lymphoblastic leukemia (ALL) carries a grave prognosis. The most promising strategy for curing these patients is through re-induction chemotherapy followed by successful allogeneic transplant. We studied a new high-dose induction regimen in order to improve the outcome for these patients. Eighteen adult patients with relapsed/refractory ALL were treated on a phase I study of high-dose cytarabine combined with a single escalating dose of idarubicin. Five patients had primary refractory disease and 13 were treated in refractory relapse. Nine patients (50%) had Ph+ ALL. The induction regimen was cytarabine 3 g/m2/day intravenously days 1-5 and idarubicin as a single intravenous dose on day 3. G-CSF 5 microg/kg subcutaneously every 12 h was started on day 7. The initial idarubicin dose was 20 mg/m2 with dose escalations of 10 mg m2. Cohorts of three patients were treated at each idarubicin dose level. Unacceptable toxicity was encountered at 50 mg/m2 with one death from infection and one death from cardiotoxicity in a patient with significant prior anthracycline exposure. There were no instances of grade 4 non-hematologic toxicity encountered at idarubicin doses of 20 mg/m2, 30 mg/m2, or 40 mg/m2. The data suggest a dose-response relationship for increasing doses of idarubicin with 0/3 complete responses (CR) at 20 mg/m2, 1/3 CR at 30 mg/m2, and 7/12 (58%) CR at idarubicin doses > or = 40 mg/m2. We conclude that concomitant administration of cytarabine 3 g/m2/day x 5 and high-dose idarubicin at 40 mg/m2 as a single dose on day 3 can be administered safely to patients with refractory and relapsed ALL.     

Different cytogenetic patterns in skeletal breast cancer metastases

A moderate increase in plasma level of corticosterone was induced in dams by adding the hormone (200 micrograms/ml) to the drinking water from the day after delivery to weaning. This procedure produces a parallel increase in plasma levels of the hormone in the pups (from 0.7 +/- 0.1 to 1.2 +/- 0.2 micrograms/100 ml) at 10 days of lactation. A significant (P < 0.01) reduction in the magnitude of the long-term potentiation (LTP) of the CA1 population spike occurred in hippocampal slices obtained from 30-45 day old male corticosterone-nursed rats with respect to controls, while no significant difference occurred in the magnitude of the basal CA1 evoked extracellular somatic field potentials with respect to controls. The results demonstrate that a moderate increase in plasma corticosterone during neonatal life, obtained through maternal milk, has long-lasting effects on the hippocampal CA1 synaptic plasticity. In addition, these results together with our previous findings [Catalani, A. et al., Brain Res., 624 (1993) 209-215], demonstrating that 30 day old corticosterone-nursed offsprings perform better than controls in the place learning version of the Morris water maze, show no relationships between in vitro CA1 LTP induction and spatial learning in agreement with literature data.     

Intraamniotic ethyl docosahexaenoate administration protects fetal rat brain from ischemic stress

Studies were conducted on the prenatal rat given a single intraamniotic injection of ethyl docosahexaenoate (Et-DHA; 9.6-12 mmol per fetus) or subjected to an n-3 fatty acid-deficient diet to assess the role of docosahexaenoate on oxidative stress during episodes of ischemia. A time-dependent decrease in the ability of brain slices from animals treated with Et-DHA to produce thiobarbituric acid-reactive substance (TBARS), most pronounced after 1 day (from 58.1 +/- 4.22 to 15.9 +/- 1.6 nmol/mg of DNA), was noticed on stimulation with Fe2+. Brain slices from fetuses treated for 1 day with Et-DHA and those from untreated fetuses produced TBARS levels of 46.7 +/- 6.5 and 114.8 +/- 10.8 nmol/mg of DNA, respectively, after a 20-min occlusion of the fetal-maternal circulation at embryonic day 20, suggesting a protective effect of Et-DHA. The protective effect of a single dose of Et-DHA in utero remained high up to 3 days after injection (p < 0.001) and was long-lasting, yet not significant, up to 3 days following birth. In agreement with a reduction in TBARS production by slices, the endogenous levels of TBARS in brains of Et-DHA-treated animals were lower than in the controls. Et-DHA-injected fetuses exhibited significantly higher levels of esterified DHA than the noninjected controls. n-3-deficient diet given to dams for 2 weeks before birth did not affect the levels of TBARS production in control fetal brain slices but abolished the increase caused by ischemia. Et-DHA administration for 24 h to n-3-deficient fetuses reduced the amount of TBARS produced by the fetal brain slices from 49.1 +/- 8.5 to 31.7 +/- 4.1 nmol/mg of DNA. A protective effect from oxidative damage after postischemic oxidative stress in fetal brain following DHA supplements is suggested, whereas the effect of n-3 fatty acid deficiency in this regard is more ambiguous.     

Effects of caerulein and CCK antagonists on tolerance induced to morphine antinociception in mice

Different groups of mice received one daily dose (50 mg/kg) of morphine subcutaneously (SC) for 3, 4 or 5 days to develop tolerance to the opioid. The antinociceptive response of morphine (9 mg/kg) was tested in the hot-plate test 24 h after the last dose of the drug. Tolerance to morphine was obtained in all groups. The group of mice that received morphine for 4 days was employed for the rest of the experiments. Pretreatment of animals with a single dose of caerulein (0.025, 0.05, and 0.1 mg/kg, SC) 30 min prior to receiving morphine (50 mg/kg; during the development of tolerance to the opioid) on day 1, 2, 3, 4 or 5 of morphine administration potentiate antinociception induced by morphine (test dose of 9 mg/kg). The dose of 0.05 mg/kg of caerulein, used 30 min before morphine administration on day 3, was also used to evaluate the effects of antagonists on caerulein-induced decrease in tolerance. The selective cholecystokinin (CCK) receptor antagonists, MK-329 [1-methyl-3-(2 indoloyl)amino-5-phenyl-3H-1,4-benzodiazepin-2-one; 0.25 and 0.5 mg/kg] or L-365,260 [3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H- 1,4-benzodiazepin-3-yl)-N-(3-methyl-phenyl)urea: 0.25 and 0.5 mg/kg] decreased potentiation of morphine response induced by caerulein. MK-329 or L-365,260, when were injected 35 min before morphine injection during the development of tolerance and on day 3, decreased the tolerance to morphine. A single administration of MK-329 or L-365,260 (in the absence of caerulein) 35 min and 48 h before the test dose of morphine (9 mg/kg) potentiated the antinociception of morphine in nontolerant animals. In conclusion, CCK mechanism(s) may interact with morphine tolerance.     

Prenatal ethanol exposure decreases GAP-43 phosphorylation and protein kinase C activity in the hippocampus of adult rat offspring

Consumption of moderate quantities of ethanol during pregnancy produces deficits in long-term potentiation in the hippocampal formation of adult offspring. Protein kinase C (PKC)-mediated phosphorylation of the presynaptic protein GAP-43 is critical for the induction of long-term potentiation. We tested the hypothesis that this system is affected in fetal alcohol-exposed (FAE) rats by measuring GAP-43 phosphorylation and PKC activity in the hippocampus of adult offspring of rat dams that had consumed one of three diets throughout gestation: (a) a 5% ethanol liquid diet, which produced a maternal blood ethanol concentration of 83 mg/dl (FAE); (b) an isocalorically equivalent 0% ethanol diet (pair-fed); or (c) lab chow ad libitum. Western blot analysis using specific antibodies to PKC-phosphorylated GAP-43 revealed that FAE rats had an approximately 50% reduction in the proportion of phosphorylated GAP-43. Similarly, we found that PKC-mediated incorporation of 32P into GAP-43 was reduced by 85% in hippocampal slices from FAE rats compared with both control groups. FAE animals also showed a 50% reduction in total hippocampal PKC activity, whereas the levels of six major PKC isozymes did not change in any of the diet groups. These results suggest that GAP-43 phosphorylation deficits in rats prenatally exposed to moderate levels of ethanol are not due to alterations in the expression of either the enzyme or substrate protein, but rather to a defect in kinase activation.     

Substrate phosphorylation in the protein kinase Cgamma knockout mouse

The phosphorylation state of three identified neural-specific protein kinase C substrates (RC3, GAP-43/B-50, and MARCKS) was monitored in hippocampal slices of mice lacking the gamma-subtype of protein kinase C and wild-type controls by quantitative immunoprecipitation following 32Pi labeling. Depolarization with potassium, activation of glutamate receptors with glutamate, or direct stimulation of protein kinase C with a phorbol ester increased RC3 phosphorylation in wild-type animals but failed to affect RC3 phosphorylation in mice lacking the gamma-subtype of protein kinase C. Our results suggests the following biochemical pathway: activation of a postsynaptic (metabotropic) glutamate receptor stimulates the gamma-subtype of protein kinase C, which in turn phosphorylates RC3. The inability to increase RC3 phosphorylation in mice lacking the gamma-subtype of protein kinase C by membrane depolarization or glutamate receptor activation may contribute to the spatial learning deficits and impaired hippocampal LTP observed in these mice.     

Examination of persistent effects of repeated administration of pentylenetetrazol on rat hippocampal CA1: evidence from in vitro study on hippocampal slices

The early and long-lasting effects of pentylenetetrazol-kindling on hippocampal CA1 synaptic transmission were investigated. Experiments were carried out in the hippocampal slices from control and kindled rats at two post-kindling periods, i.e. 48-144 h (early phase) and 30-33 days (long-lasting phase). Field potentials, i.e. population excitatory postsynaptic potential (pEPSP) and population spike (PS) were recorded at the stratum pyramidale following stimulation of the stratum radiatum. Kindling-induced changes in synaptic transmission were assessed by stimulus-response functions and paired-pulse responses. The results showed that 48-144 h after kindling, the PS amplitude in the CA1 of kindled slices enhanced, and a second PS appeared compared to control slices. But at 30-33 days after kindling, the pEPSP slope in the CA1 of kindled slices enhanced without any change in the PS compared with those in the control slices. Evaluation of paired-pulse responses showed a significant reduction in paired-pulse inhibition for PS 48-144 h after kindling and a significant increase in paired-pulse inhibition for pEPSP 30-33 days after kindling. Our results suggest that pentylenetetrazol-kindling is accompanied by enhanced excitability and a reduction of paired-pulse inhibition in hippocampal CA1. The increased paired-pulse inhibition one month after kindling, may be interpreted as an adaptive process to cope with subsequent seizures.     

Analysis of potential risk factors associated with the development of pancreatitis in phase I patients with AIDS or AIDS-related complex receiving didanosine

Phase I dose-escalating trials of didanosine revealed dose-limiting toxicities, including pancreatitis, and established a total daily dose of 12.5 mg/kg/day as the maximum tolerated dose. Clinical and pharmacokinetic data of 61 patients from two trials were analyzed to further evaluate the risk of pancreatitis: 1 (6.3%) of 16 patients who received < 500 mg/day didanosine, 2 (13.3%) of 15 who received 500-750 mg/day, and 15 (50%) of 30 who received > 750 mg/day developed pancreatitis (P < .001). A relationship between risk of pancreatitis and steady-state plasma concentrations of didanosine and age was also observed, suggesting that knowledge of didanosine pharmacokinetics provided additional information regarding risk of toxicity. Further confirmation of these findings will be necessary to determine if the risk factors for pancreatitis remain the same at lower doses currently used.     

Alterations in the balance of protein kinase/phosphatase activities parallel reduced synaptic strength during aging

The current research examined the regulation of synaptic strength by protein phosphorylation during aging. Bath application of the protein phosphatase 1 and 2A (PP1 and PP2A) inhibitor calyculin A (1 microM) enhanced CA3-CA1 synaptic strength in hippocampal slices from aged male (20-24 mo) but not from young adult male (4-6 mo) Fischer 344 rats. Similarly, injection of the PP1 and PP2A inhibitor microcystin-L,R (5 microM) into CA1 cells caused an increase in the intracellular synaptic response only in slices from aged rats. In contrast, bath application of the serine/threonine kinase inhibitor H-7 (10 microM) induced a decrease in synaptic strength only in slices from the young adult group. These results demonstrate that phosphorylation dependent regulation of intrinsic synaptic efficacy changes during aging.     

The effect of fenfluramine dosage regimen and reduced food intake on levels of 5-HT in rat brain

Male Wistar rats received fenfluramine in subacute (5 mg/kg b.i.d. i.p. for 4 days) or escalating (0.5, 1, 1.5, 2, 3, 4 and 5 mg/kg b.i.d. i.p., each dose given for 4 days) doses. Saline-treated controls received food ad libitum, or were pair-fed with the fenfluramine-treated animals. Rats were killed 1, 15 and 30 days after drug withdrawal. On day 1, plasma and brain fenfluramine levels were higher, and hypothalamus norfenfluramine levels were lower following escalating compared to subacute dosing, although total active drug levels were unaltered. Both treatment regimes, and pair-feeding reduced food intake and body weight. Subacute fenfluramine reduced brain 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) levels for up to 30 days. Brain 5-HT and 5-HIAA levels were unaltered following escalating-doses of fenfluramine. Additionally, pair-feeding transiently decreased hippocampal 5-HT levels. These data suggest that escalating-doses of fenfluramine prevent the 5-HT-depleting effect of a sub-cute challenge without altering the anorexic action of the drug.     

Control of the phosphorylation of the astrocyte marker glial fibrillary acidic protein (GFAP) in the immature rat hippocampus by glutamate and calcium ions: possible key factor in astrocytic plasticity

The present review describes recent research on the regulation by glutamate and Ca2+ of the phosphorylation state of the intermediate filament protein of the astrocytic cytoskeleton, glial fibrillary acidic protein (GFAP), in immature hippocampal slices. The results of this research are discussed against a background of modern knowledge of the functional importance of astrocytes in the brain and of the structure and dynamic properties of intermediate filament proteins. Astrocytes are now recognized as partners with neurons in many aspects of brain function with important roles in neural plasticity. Site-specific phosphorylation of intermediate filament proteins, including GFAP, has been shown to regulate the dynamic equilibrium between the polymerized and depolymerized state of the filaments and to play a fundamental role in mitosis. Glutamate was found to increase the phosphorylation state of GFAP in hippocampal slices from rats in the post-natal age range of 12-16 days in a reaction that was dependent on external Ca2+. The lack of external Ca2+ in the absence of glutamate also increased GFAP phosphorylation to the same extent. These effects of glutamate and Ca2+ were absent in adult hippocampal slices, where the phosphorylation of GFAP was completely Ca(2+)-dependent. Studies using specific agonists of glutamate receptors showed that the glutamate response was mediated by a G protein-linked group II metabotropic glutamate receptor (mGluR). Since group II mGluRs do not act by liberating Ca2+ from internal stores, it is proposed that activation of the receptor by glutamate inhibits Ca2+ entry into the astrocytes and consequently down-regulates a Ca(2+)-dependent dephosphorylation cascade regulating the phosphorylation state of GFAP. The functional significance of these results may be related to the narrow developmental window when the glutamate response is present. In the rat brain this window corresponds to the period of massive synaptogenesis during which astrocytes are known to proliferate. Possibly, glutamate liberated from developing synapses during this period may signal an increase in the phosphorylation state of GFAP and a consequent increase in the number of mitotic astrocytes.     

Developmental toxicity evaluation of isopropanol by gavage in rats and rabbits

Timed-pregnant CD (Sprague-Dawley) rats, 25/group, were dosed orally with aqueous isopropanol (IPA; CAS No. 67-63-0) solutions at 0, 400, 800, or 1200 mg/kg/day, once daily on Gestational Days (GD) 6 through 15 at a dosing volume of 5 ml/kg. Artificially inseminated New Zealand white rabbits, 15/group, were dosed orally with IPA at 0, 120, 240, or 480 mg/kg/day once daily on GD 6 through 18 at 2 ml/kg. Maternal body weights, clinical observations, and food consumption were recorded throughout gestation for both species. At scheduled euthanization for both species (GD 20, rats; GD 30, rabbits), fetuses were weighed, sexed, and examined for external, visceral (including craniofacial) and skeletal alterations. For both species, the pregnancy rate was high and equivalent across all groups; no dams or does aborted, delivered early, or were removed from study. In rats, two dams (8%) died at 1200 mg/kg/day and one dam (4%) died at 800 mg/kg/day. Maternal body weights and weight gain were equivalent across all groups, except for statistically significantly reduced gestational weight gain (GD 0-20; 89.9% of control value), associated with statistically significantly reduced gravid uterine weight at 1200 mg/kg/day (89.2% of control value). There were no treatment-related clinical signs or effects on maternal food consumption. All gestational parameters evaluated were equivalent across groups, including pre- and postimplantation loss, fetal sex ratios, and litter size. Twenty-two to 25 litters were examined per group. Fetal body weights per litter were statistically significantly reduced at the two highest doses (97.3 (n.s.), 94.7, and 94.3% of controls at 800 mg/kg/day and 92.1, 91.9, and 95.4% of controls at 1200 mg/kg/day for all fetuses and males and females separately). No evidence of increased teratogenicity was observed at any dose tested in rats. In rabbits, four does (26.7%) died at 480 mg/kg/day. Maternal body weights were statistically significantly reduced during treatment (GD 6-18) at 480 mg/kg/day (45.4% of control value) with a nonsignificant reduction in gestational weight change (GD 0-30; 77.3% of control value) at this dose. Profound clinical signs of toxicity and statistically significantly reduced maternal food consumption were observed at 480 mg/kg/day. All gestational parameters were equivalent across all doses administered. Thirteen to 15 litters were evaluated per group except for the 480 mg/kg/day group with 11 litters (due to maternal deaths). There were no treatment-related effects on pre- or postimplantation loss, fetal sex ratio, litter size, or fetal body weight/litter. Moreover, no evidence was found of increased teratogenicity at any dose tested in rabbits. Therefore, IPA was not teratogenic to CD rats or to NZW rabbits. The NOAELS for both maternal and developmental toxicity were 400 mg/kg/day in rats, and were 240 and 480 mg/kg/day, respectively, in rabbits.     

Developmental toxicity evaluation of ethylene glycol by gavage in New Zealand white rabbits

Artificially inseminated New Zealand white (NZW) rabbits were administered ethylene glycol (EG) by gavage on Gestational Days (GD) 6 through 19 at doses of 0, 100, 500, 1000, or 2000 mg/kg/day, with 23-24 inseminated animals per group. Clinical signs were recorded and water consumption was measured daily; does were weighed on GD 0, 6-19, 25, and 30. At necropsy (GD 30), maternal liver, kidney, and gravid uterine weights were recorded. Histopathologic examination was performed on kidneys from 10 does/dose and for all unscheduled deaths. Ovarian corpora lutea were counted and uterine implantation sites (total sites, resorptions, dead and live fetuses) were recorded. All live fetuses were weighed, sexed, and examined for external, visceral, and skeletal malformations and variations. EG resulted in profound maternal toxicity at 2000 mg/kg/day (42% mortality; three early deliveries and one spontaneous abortion) associated with renal pathology and unaccompanied by any other indicators of maternal toxicity. Renal lesions at 2000 mg/kg/day involved the cortical renal tubules and included intraluminal oxalate crystals, epithelial necrosis, and tubular dilatation and degeneration. No dose-related maternal toxicity occurred at 100-1000 mg/kg/day. There was no indication of developmental toxicity at any dose tested, including no effects on pre- or postimplantation loss, number of fetuses, fetal body weight, or sex ratio (% male fetuses) per litter, and no evidence of teratogenicity. The "no observable adverse effect level" (NOAEL) for maternal toxicity was therefore 1000 mg/kg/day and the NOAEL for developmental toxicity was at least 2000 mg/kg/day in this study. The sensitivity of NZW rabbits relative to that of Sprague-Dawley rats and Swiss mice for maternal and developmental toxicity from gavage administration of EG during organogenesis can be determined for maternal toxicity: rabbits > mice > rats, and for developmental toxicity, mice > rats > rabbits.     

Dual Isoflurane-induced Preconditioning Improves Neuroprotection in Rat Brain In Vitro and the Role of Extracellular Signal-regulated Protein Kinase

Objective To test the ability of isoflurane-induced preconditioning against oxygen and glucose deprivation (OGD) injury in vitro.Methods Rat hippocampal slices were exposed to 1 volume percentage (vol%),2vol% or 3vol% isoflurane respectively for 20 minutes under normoxic conditions (95% O2/5% CO2) once or twice (12 slices in each group) before OGD,with 15-minute washout after each exposure.During OGD experiments,hippocampus slices were bathed with artificial cerebrospinal fluid (ACSF) lacking glucose and perfused with 95% N2 and 5% CO2 for 14 minutes,followed by a 30-minute reperfusion in normal ACSF.The CA1 population spike (PS) was measured and used to quantify the degree of neuronal function recovery after OGD.To assess the role of mitogen-activated protein kinases (MAPKs) in isoflurane preconditioning,U0126,an inhibitor of extracellular signal-regulated protein kinase (ERK1/2),and SB203580,an inhibitor of p38 MAPK,were used before two periods of 3vol% isoflurane exposure.Results The degree of neuronal function recovery of hippocampal slices exposed to lvol%,2vol%,or 3vol% isoflurane once was 41.88%±9.23%,55.05%± 11.02%,or 63.18%±10.82% respectively.Moreover,neuronal function recovery of hippocampal slices exposed to lvol%,2vol%,or 3vol% isoflurane twice was 53.7S%±12.04%,63.50%±11.06%,or 76.25%±12.25%,respectively.Isoflurane preconditioning increased the neuronal function recovery in a dose-dependent manner.U0126 blocked the preconditioning induced by dual exposure to 3vol% isoflurane (6.13%±1.56%,P<0.01) and ERK1 /2 activities.Conclusions Isoflurane is capable of inducing preconditioning in hippocampal slices in vitro in a dose-dependent manner,and dual exposure to isoflurane with a lower concentration is more effective in triggering preconditioning than a single exposure.Isoflurane-induced neuroprotection might be involved with ERK1/2 activities.     

A randomized trial in primary biliary cirrhosis comparing ursodeoxycholic acid in daily doses of either 10 mg/kg or 20 mg/kg. Dutch Multicentre PBC Study Group

BACKGROUND: Ursodeoxycholic acid (UDCA) prolongs transplantation-free survival in primary biliary cirrhosis (PBC). However, the optimal therapeutic dose has not been established. AIM: To compare the effects of UDCA administered in daily doses of 10 vs. 20 mg/kg on symptoms, liver biochemistry and biliary UDCA enrichment. METHODS: A 6-month multicentre randomized open controlled trial was conducted to assess the effects of an increase in the dose of UDCA to 20 mg/kg/day vs. continuation of 10 mg/kg/day for patients who had not achieved biochemical normalization during treatment for at least 6 months with the 10 mg/kg dose. Clinical and laboratory evaluations were performed at entry and at 3-month intervals. The percentage UDCA in duodenal bile was assessed at entry and at 6 months. RESULTS: Sixty-one patients were enrolled. No side-effects of UDCA were observed. Within the 20 mg/kg/day group significant decreases were found for alkaline phosphatase (- 8%; P = 0.003), aspartate aminotransferase (- 11%; P = 0.01), alanine aminotransferase (- 17%; P < 0.001), gamma-glutamyl transferase (- 34%; P < 0.001), immunoglobulin M (- 11%; P = 0.002) and cholesterol (- 8.1%; P < 0.001). In the 10 mg/kg group none of these parameters differed significantly from baseline. No significant differences between dose groups for symptom scores or serum bilirubin were found. Biliary enrichment with UDCA increased from 37% to 46% in the 20 mg/kg group (P = 0.02) while remaining stable in the 10 mg/kg group. CONCLUSIONS: Liver biochemistry improved in PBC patients receiving UDCA 20 mg/kg/day compared to a dose of 10 mg/kg/day. Both doses were equally well tolerated. These results indicate that UDCA 10 mg/kg/ day is a suboptimal dose for treating PBC.