摘要:

THE protein kinase C (PKC) activity of human glioma cells correlates with their rate of proliferation. We report here that the down-regulation of the predominant PKC isoform of glioma cells,α, by antisense phosphorothioate oligonucleotides (AS PTO) significantly reduced the rate of proliferation of three human glioma cell lines. This reduction in growth rate was attributed to apoptosis, as assessed by terminal deoxynucleotidyl transferase (TdT) assay. Unexpectedly, when low concentrations of the protein synthesis inhibitor cycloheximide (CHX) were administered to A172 cells immediately prior to AS PTO treatment, a marked enhancement in the number of apoptotic cells was observed. These findings suggest that PKCα plays a pivotal role in the ability of gliomas to avoid apoptotic cell death.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE studied the trophic requirements of neonatal rat sensory neurons in single neuron and standard culture (9400 neurons/cm2). In agreement with previous studies, we found that survival of sensory neurons in standard culture is strictly dependent on nerve growth factor (NGF). Contrary to this, however, no difference between NGF-treated and untreated cultures with respect to survival and neurite formation was evident when neurons were plated as single cells. Approximately 70% of singly-seeded sensory neurons survived for 2 days independent of supply with NGF. Survival of large, mid-sized, and small sensory neurons in single neuron culture demonstrated that this phenomenon is not confined to a neuronal subpopulation. We speculate that survival in single neuron culture is due to the absence or inactivation of yet unidentified cell death-inducing factors that in standard culture are overridden or suppressed by NGF.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE perception of tactile stimuli is facilitated when subjects look towards the stimulated body site: this facilitation even takes place when visual information is unavailable, as when orienting in the dark. It is not known whether the facilitation is due entirely to such proprioceptive orienting of eye and head, or whether visual information of the body site can also facilitate touch. An experiment is reported which dissociates vision and proprioception, and demonstrates for the first time that vision of a body part, independent of proprioceptive orienting, can indeed effect somatosensation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CURRENT magnetic coil stimulators can efficiently activate neural structures without deep electrode placement and the local discomfort associated with transcutaneous electrical stimulation used in pain control. We tested the possibility of reducing pain in patients with localized musculoskeletal processes by applying repetitive magnetic stimulation on the tender body region. Thirty patients were randomized to receive 40 min of real or sham magnetic stimulation. After a single session, real magnetic stimulation significantly exceeded the sham effect: a 101-point pain score decreased by 59% in the treated group and 14% in sham-treated patients (z = −3.26,p= 0.001). The pain relief attained regularly persisted for several days. Results indicate that powerful magnetic coil stimulation can efficiently reduce pain originating from localized musculoskeletal injuries.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE aim of the present study was to determine whether amyloid β-peptide (Aβ) induces mitochondrial dysfunction. Mitochondrial function was reported to be affected following Aβ exposure, as demonstrated by depolarization of the mitochondrial membrane, decrease of oxygen consumption and by the inhibition of complexes I, III and IV of the mitochondrial respiratory chain. Aβ25-35 and Aβ1-40 peptides also inhibited MTT reduction in a dose-dependent manner in undifferentiated and differentiated PC12 cells. Several antioxidants prevented this inhibitory response, suggesting that oxidative stress is involved in Aβ-induced cytotoxicity. These data suggest that mitochondrial dysfunction contributes to amyloid β-protein cytotoxicity and may play a major role in the abnormalities of energy metabolism observed in Alzheimer's disease.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RILUZOLE, a glutamate antagonist, has been shown to be efficacious in the treatment of patients with amyotrophic lateral sclerosis (ALS), allowing prolonged survival and time to tracheostomy. The efficacy of riluzole in thought to result from reduced glutamate excitotoxicity on motor neurons of patients with ALS, but this has never been demonstrated directlyin vivo. N-acetylaspartate (NAA), a compound that is readily measuredin vivousing proton magnetic resonance spectroscopy, can be used as a surrogate marker for neuronal loss or sublethal injury. To determine whether riluzole reverses sublethal corticomotoneuron damage in patients with ALS we measured NAA/creatine (Cr) relative intensity ratios in the motor cortex before and after treatment with riluzole 50 mg bid. After 3 weeks of riluzole therapy in 11 patients NAA/Cr increased from 2.14 ± 0.26 to 2.27 ± 0.24 (p= 0.044), whereas, in 12 untreated patients NAA/Cr decreased from 2.17 ± 0.20 to 2.08 ± 0.20 (p= 0.099). Thus the change in NAA/Cr between the treated and untreated groups was 0.22 ± 0.095 (p= 0.008). The magnitude of increase in NAA/Cr in those treated was not correlated with age, sex, duration of treatment or disease, the presence of probable or definite upper motor neuron (UMN) signs, bulbar features, or pre-treatment NAA/Cr. We conclude that magnetic resonance spectroscopy can provide a novel surrogate measure of neuronal integrity that demonstrates reversal of sublethal UMN injury in patients with ALS within weeks of initiating riluzole therapy.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE present study was designed to evaluate the effect of dopamine (DA) D-1 receptor activation in the nucleus accumbens (NAC) on the locomotor sensitizing effects of repeated intra-accumbens (intra-NAC) infusions of cocaine. Repeated infusion of cocaine (10 μg/0.5 μl daily for 2 days) resulted in an enhanced locomotor response to a subsequent intra-NAC and systemic (i.p.) challenging dose of the psychostimulant. Pretreatment with the selective D-1 agonist SK&F82958 (1.0 μg) markedly enhanced the sensitizing effects of both intra-NAC and systemic cocaine. The effect of SK&F82958 was completely blocked by systemic administration of the D-1 antagonist SCH23390 (0.1 mg/kg, i.p.). These data give further support to the idea that activation of D-1 receptors plays an important role in the induction of locomotor sensitization and show that the NAC may, in fact, be an anatomical locus of initiation of behavioural sensitization.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ALCOHOL modulation of single-channel kinetics of GABAAreceptor currents was studied with rat dorsal root ganglion neurons using the excised outside-out patch clamp technique. GABA (1 μM) alone or GABA (1 μM) plus ethanol (30–300 mM) or n-Octanol (30–300 μM) were applied by pressure ejection to evoke single-channel currents. The main single-channel conductance was not changed by either ethanol or n-Octanol at 25 pS. Both alcohols exerted the same effects on the single-channel kinetics, although n-Octanol was more potent than ethanol. The frequency of openings, the mean open time, the percentage of open time, the frequency of bursts, and the mean burst duration were all increased, but the mean closed time was decreased. These changes in channel kinetics account for the increase in whole-cell current amplitude caused by ethanol and n-Octanol.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE periaqueductal gray (PAG) and rostral ventrome-dial medulla (RVM) are important brain stem pain modulating regions. Recent evidence suggests that κ opioids antagonize the effects of μ opioids in the RVM. However, the anatomical relationship between μ and κ opioid receptors in PAG and RVM is not well characterized. This study examined relationships between μ and κ opioid receptor immunoreactivity (IR) and mRNA in PAG and RVM. Brain slices were processed for either immunocytochemistry orin situhybridization. We found considerable anatomical overlap of μ and κ opioid IR and mRNA in the RVM and PAG. These results provide an anatomical basis for recent behavioral and electrophysiological findings in RVM, and suggest modulatory interactions between μ and κ opioids in PAG.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TO test the hypothesis that the pedunclopontine tegmental nucleus (PPTg) plays a role in anxiety, rats with electrolytic lesions of the PPTg were tested in two animal models of anxiety, the elevated plus maze and the social interaction tests. Histological analysis showed that lesions were concentrated on the caudal half of the PPTg. In the elevated plus maze, traditional as well as ‘risk assessment’ measures indicated significantly increased anxiety in the PPTg-lesioned ratsvssham-operated controls. In the social interaction test, behavioural scores were biased towards elevated anxiety in the PPTg-lesioned rats but only the number of social sniffs reached significance. Our results confirm that electrolytic lesions of the caudal PPTg produce increased anxiety.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID