Functional connectivity in the rodent trigeminal pathway grown in vitro

In explant cocultures of the rat trigeminal pathway, embryonic trigeminal ganglion cells grow their axons into peripheral cutaneous and central nervous system targets (R.S. Erzurumlu, S. Jhaveri, Target influences on the morphology of trigeminal axons, Exp. Neurol, 135 (1995) 1-16; R.S. Erzurumlu, S. Jhaveri, H. Takahashi, R.D.G. McKay, Target-derived influences on axon growth modes in explant cocultures of trigeminal neurons, Proc. Natl. Acad. Sci. USA 90 (1993) 7235-7239). In heterochronic cocultures, composed of embryonic trigeminal ganglion, embryonic whisker pad and postnatal brainstem slice, trigeminal axons develop arbors and terminal boutons in the brainstem trigeminal nuclei. To determine whether these terminal arbors establish functional connections with the brainstem neurons, we examined the electrophysiological properties of brainstem neurons and their responsiveness to trigeminal ganglion stimulation. Intracellular recordings were done in vitro on cells of the trigeminal subnucleus interpolaris (SPI) in trigeminal pathway cocultures (E15 whisker pad, E15 trigeminal ganglion, and postnatal day (PND) 0-2 brainstem slice) or in the SPI of acutely prepared brainstem slices. Electrophysiological properties of SPI cells in both preparations were virtually identical. The voltage responses of SPI neurons to intracellular current injection were highly linear suggesting they lacked a number of voltage-dependent conductances. Depolarizing current injection produced trains of action potentials with a frequency that varied with stimulus intensity. In explant cocultures, electrical activation of the trigeminal ganglion evoked EPSPs, and EPSPs coupled with IPSPs in SPI cells. Bicuculline blockade of IPSP activity resulted in long lasting EPSPs whose duration increased with membrane depolarization. These results show that brainstem trigeminal neurons can retain their functional properties in culture and establish functional connections with primary sensory afferents.     

Behavior of the polymorphonuclear leukocyte membrane fluidity and cystolic Ca2+ content in vascular atherosclerotic disease with and without non-insulin-dependent diabetes mellitus

In 71 subjects with vascular atherosclerotic disease (VAD), in 32 VAD subjects with non-insulin-dependent diabetes mellitus (NIDDM) and in 31 normal controls, we evaluated polymorphonuclear leukocyte (PMN) membrane fluidity and PMN cytosolic Ca2+ content. The PMN membrane fluidity was obtained by marking intact and unstimulated PMN cells with fluorescent probe 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH) and the PMN cytosolic Ca2+ content was obtained by marking intact and unstimulated PMN cells with the fluorescent probe Fura 2-AM. From the obtained results, it is evident that PMN membrane fluidity does not differentiate normals from VAD subjects and VAD subjects with NIDDM, and normals from subjects with monovascular disease (MVAD) and polyvascular disease (PVAD) with and without NIDDM. The PMN cytosolic Ca2+ content is significantly increased in VAD subjects and VAD subjects with NIDDM, and also in MVAD and PVAD subjects with and without NIDDM. A positive correlation is present between PMN membrane fluidity and PMN cytosolic Ca2+ content in normals and VAD subjects, but not in VAD subjects with NIDDM. In conclusion, in VAD subjects with and without NIDDM, an increase of the PMN cytosolic Ca2+ content is present; this increase might be related to the PMN spontaneous activation.     

Opposing roles for endogenous BDNF and NT-3 in regulating cortical dendritic growth

Neurons within each layer of cerebral cortex express multiple members of the neurotrophin family and their corresponding receptors. This multiplicity could provide functional redundancy; alternatively, different neurotrophins may direct distinct aspects of cortical neuronal growth and differentiation. By neutralizing endogenous neurotrophins in organotypic slices of developing cortex with Trk receptor bodies (Trk-IgGs), we found that BDNF and NT-3 oppose one another in regulating the dendritic growth of pyramidal neurons. In layer 4, both endogenous and exogenous NT-3 inhibited the dendritic growth stimulated by BDNF. In contrast, in layer 6 both endogenous and exogenous BDNF inhibited dendritic growth stimulated by NT-3. These antagonistic actions of endogenous BDNF and NT-3 provide a mechanism by which dendritic growth and retraction can be dynamically regulated during cortical development, and suggest that the multiple neurotrophins expressed in developing cortex represent distinct components of an extracellular signaling system for regulating dendritic growth.     

Can optimal acid suppression prevent rebleeding in peptic ulcer patients with a non-bleeding visible vessel: a preliminary report of a randomized comparative study

BACKGROUND/AIMS: The hypothesis that profound acid suppression might prevent clot lysis and thus benefit patients with a non-bleeding visible vessel has not been confirmed. Omeprazole can suppress gastric acid remarkably and may be beneficial for patients with peptic ulcer bleeding. METHODOLOGY: Fifty-two patients with a non-bleeding visible vessel at the ulcer base were enrolled and randomized into four groups (N = 13 in each group). In the cimetidine group, the patients received cimetidine 300 mg i.v. bolus followed by 300 mg i.v. every 6 hr during hospitalization. In the heater probe thermocoagulation + cimetidine group, the patients received heater probe thermocoagulation and cimetidine 300 mg i.v. bolus followed by 300 mg i.v. every 6 h during hospitalization. In the omeprazole q.d. group, the patients received omeprazole 40 mg i.v. bolus followed by 40 mg i.v. daily for two days. In the omeprazole q 12 h group, the patients received omeprazole 40 mg i.v. bolus followed by 40 mg i.v. every 12 h for two days. A 24 hr intragastric pH was recorded for every case. RESULTS: The mean 24 hr intragastric pH were higher in the omeprazole q.d. (mean 5.8) and the omeprazole q 12 h groups (mean 6.4) than in the cimetidine (mean 4.3) and the heater probe thermocoagulation + cimetidine groups (mean 4.9) (p < 0.05). Rebleeding occurred in 5, 2, 2 and 2 patients in the cimetidine, heater probe thermocoagulation + cimetidine, omeprazole q.d., and omeprazole q 12 h groups, respectively (p > 0.05). Volume of blood transfusion and number of days in hospital were not statistically different among the four groups. CONCLUSIONS: Omeprazole can remarkably suppress gastric acid when it is compared to that of the H2 receptor blocker. Patients with a non-bleeding visible vessel using omeprazole do not exhibit a decrease in the rebleeding rate as compared with those patients using cimetidine.     

Troglitazone increases the resistance of low density lipoprotein to oxidation in healthy volunteers

The oxidative modification of low density lipoprotein is of importance in atherogenesis. Antioxidant supplementation has been shown, in published work, to increase low density lipoprotein resistance to oxidation in both healthy subjects and diabetic subjects; in animal studies a contemporary reduction in atherogenesis has been demonstrated. Troglitazone is a novel oral antidiabetic drug which has similarities in structure with vitamin E. The present study assessed the effect of troglitazone 400 mg twice daily for 2 weeks on the resistance of low density lipoprotein to oxidation in healthy male subjects. Ten subjects received troglitazone and ten received placebo in a randomised, placebo-controlled, parallel-group design. The lag phase (a measure of the resistance of low density lipoprotein to oxidation) was determined by measurement of fluorescence development during copper-catalysed oxidative modification of low density lipoprotein. The lag phase was increased by 27 % (p < 0.001) at week 1 and by 24% (p < 0.001) at week 2 in the troglitazone treated group compared with the placebo group. A number of variables known to influence the resistance of low density lipoprotein to oxidation were measured. They included macronutrient consumption, plasma and lipoprotein lipid profile, alpha-tocopherol, beta-carotene levels in low density lipoprotein, low density lipoprotein particle size, mono and polyunsaturated fatty acid content of low density lipoprotein and pre-formed low density lipoprotein hydroperoxide levels in low density lipoprotein. Troglitazone was associated with a significant reduction in the amount of pre-formed low density lipoprotein lipid hydroperoxides. At weeks 1 and 2, the low density lipoprotein hydroperoxide content was 17% (p < 0.05) and 18% (p < 0.05) lower in the troglitazone group compared to placebo, respectively. In summary the increase in lag phase duration in the troglitazone group appeared to be due to the compound's activity as an antioxidant and to its ability to reduce the amount of preformed low density lipoprotein lipid hydroperoxides. This antioxidant activity could provide considerable benefit to diabetic patients where atherosclerosis accounts for the majority of total mortality.     

Attenuated neurotransmitter release and spreading depression-like depolarizations after focal ischemia in mutant mice with disrupted type I nitric oxide synthase gene

Nitric oxide (NO) plays a complex role in the pathophysiology of cerebral ischemia. In this study, mutant mice with disrupted type I (neuronal) NO synthase (nNOS) were compared with wild-type littermates after permanent focal ischemia. Cerebral blood flow in the central and peripheral zones of the ischemic distribution were measured with laser doppler flowmetry. Simultaneously, microdialysis electrodes were used to measure extracellular amino acid concentrations and DC potential in these same locations. Blood flow was reduced to <25 and 60% of baseline levels in the central and peripheral zones, respectively; there were no differences in nNOS mutants versus wild-type mice. Within the central ischemic zone, DC potentials rapidly shifted to -20 mV in all mice. In the ischemic periphery, spreading depression (SD)-like waves of depolarization were observed. SD-like events were significantly fewer in the nNOS mutant mice. Concurrent with these hemodynamic and electrophysiological perturbations, extracellular elevations in amino acids occurred after ischemia. There were no detectable differences between wild-type and mutant mice in the ischemic periphery. However, in the central zone of ischemia, elevations in glutamate and GABA were significantly lower in the nNOS mutants. Twenty-four hour infarct volumes in the nNOS mutant mice were significantly smaller than in their wild-type littermates. Overall, the number of SD-like depolarizations and the integrated efflux of glutamate were significantly correlated with infarct size. These results suggest that NO derived from the nNOS isoform contributes to tissue damage after focal ischemia by amplifying excitotoxic amino acid release in the core and deleterious waves of SD-like depolarizations in the periphery.     

Loss of heterozygosity for chromosome 1p in familial neuroblastoma

Loss of heterozygosity (LOH) and deletion of chromosome 1p are very often found in sporadic neuroblastoma. Nevertheless, very few data are available concerning 1p LOH in familial neuroblastoma. Families with recurrent neuroblastoma are rare and analysis of chromosome 1p in these families might give useful information for identifying the putative neuroblastoma suppressor gene. We used combined cytogenetic and molecular techniques to study 1p LOH in two neuroblastoma families. Family M has 2 out of 3 children with neuroblastoma and family C has 2 children, 1 of whom has neuroblastoma and type 1 neurofibromatosis (NF1). All patients of both families showed tumour cells with chromosome 1p deletion (1pdel), but only the patient from family C also had MYCN gene amplification. In all cases the deleted chromosome 1 was of maternal origin.