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Biomedical subjects

B Meyerson

Publications and source records attributed to B Meyerson.

At least 19 recordsLinked to original sources
PubMed2002

Chronic treatments with tacrine and (-)-nicotine induce different changes of nicotinic and muscarinic acetylcholine receptors in the brain of aged rat.

The present study evaluated effects of chronic treatment with tacrine and (-)-nicotine for 21 days on nicotinic and muscarinic acetylcholine receptors in the brains of old rats (24-25 months) by receptor autoradiography. The nicotinic receptor (nAChR) binding sites were measured by (-)-[3H]nicotine and [3H]epibatidine, and the muscarinic receptor (mAChR) binding sites by [3H]pirenzepine and [3H]AFDX 384. No change in (-)-[3H]nicotine binding was observed in all of the brain regions analysed following chroinic treatment with tacrine (10 mg/kg). Similarly, the [3H]epibatidine binding was not changed in most of the brain regions analysed except for a few brain regions where a decrease was observed in tacrine treated animals compared to control animals. Chronic treatment with (-)-nicotine (0.45 mg base/kg) significantly increased both (-)-[3H]nicotine and [3H]epibatidine bindings in every brain regions analysed except for the hippocampus when measured by (-)-[3H]nicotine. A significant decrease in [3H]AFDX 384 binding, but not in [3H]pirenzepine binding was observed in all of the brain regions analysed following the treatment with tacrine. These data suggest that chronic treatments with tacrine and (-)-nicotine differentially interfere and regulate the subtypes of nAChRs and mAChRs in the brain of aged rat. These data differ from what have been earlier observed in the brain of young adult rat following tacrine treatment, revealing some dynamic changes in receptor properties in the brain during aging.

Aging↗
PubMed2001

[Peripheral and central nervous system stimulation in chronic therapy-resistant pain. Background, hypothetical mechanisms and clinical experiences].

Severe neurogenic pain still constitutes a major problem since it is often resistant to conventional therapy. During the last 30 years electric activation of pain inhibitory mechanisms through stimulation both of peripheral nerves and of central nervous circuits has been used to great advantage. The simplest method of stimulation, transcutaneous electric nerve stimulation (TENS), is extensively used by physiotherapists as well as in pain clinics. The patient should always get his own stimulator for use at home. TENS originally served as a screening method to identify patients suitable for spinal cord stimulation therapy (SCS). The main indication is severe neuropathic pain of peripheral origin, but SCS has also been found valuable in extremity ischemia as well as in refractory angina pectoris. The most severe cases of neuropathic pain may benefit from intracranial stimulation via electrodes placed stereotactically in the posteromedial thalamus or epidurally over the motor cortex.

Animals↗
PubMed2001

Androgen-linked control of carbonic anhydrase III expression occurs in rat perivenous hepatocytes; an immunocytochemical study.

Carbonic anhydrase (CA) isozymes CAII and CAIII were assayed by a radioimmunosorbent technique in liver cytosolic fractions and in isolated hepatocytes of adult male and female rats. Male livers contained 0.16 mg of CAII and 57 mg of CAIII per g cytosolic protein. Corresponding values for female livers were 0.34 mg CAII and 4 mg CAIII. Similar values and differences between CAII and III were found in isolated hepatocytes. Neonatal and adult castration of males reduced the CAIII levels to those of the females. Treatment with testosterone for three weeks restored the copulatory behaviour in the males castrated at adult age, but restored only partially the levels of CAIII. No significant effects of the endocrine manipulations were seen on CAII. Oophorectomy, with or without testosterone substitution, had no significant effect on CAII and CAIII levels in female rats. Immunohistochemistry and histochemistry showed that the regulation of CAIII is confined to perivenous hepatocytes. CAIII can therefore serve as a useful marker in the separation of these cells. CAIII appears to belong to the proteins and enzymes of the rat liver, known to be regulated via the hypothalamo-pituitary-liver axis. It may be used as a model of gene regulation in perivenous hepatocytes.

Androgens↗
PubMed2000

Cross-tolerance in drug response and differential changes in central nicotinic and N-methyl-D-aspartate receptor binding following chronic treatment with either (+)- or (-)-nicotine.

The present study compared the effects of chronic treatment (21 days) with (+)-nicotine and (-)-nicotine on exploratory behaviours and body temperature in rats. Chronic treatment with either (+)- or (-)-nicotine induced tolerance in exploratory behaviours. A cross-tolerance between the two stereoisomers was also observed. Body temperature was differentially affected by chronic (+)- and (-)-nicotine, but cross-tolerance was still observed. In addition, nicotinic acetylcholine receptor (nAChR) and N-methyl-D-aspartate (NMDA) receptor binding in rats treated with (+)- and (-)-nicotine were measured by receptor autoradiography. Chronic treatment with (+)- and (-)-nicotine significantly increased nAChR binding in different brain regions. Furthermore, significant differences in the induction of nAChR binding by chronic (+)- and (-)-nicotine were detected in several brain regions. Chronic treatment with (+)-nicotine significantly increased NMDA receptor binding in the CA1 region of the hippocampus. However, (-)-nicotine had no effect on NMDA receptor binding in any of the regions analysed. These results demonstrate differences between chronic treatment with (+)- and (-)-nicotine in physiological responses such as body temperature and biochemical changes such as changes in nAChRs and NMDA receptor binding, although a cross-tolerance between the two enantiomers in behaviour and body temperature is also observed.

Animals↗
PubMed1999

The behavior of spontaneously hypertensive and Wistar Kyoto rats under a paced fixed consecutive number schedule of reinforcement.

Spontaneously hypertensive (SHR) and Wistar Kyoto rats (WKY) were trained under paced FCN schedules of reinforcement to complete a minimum number of consecutive responses on one lever, before responding on a second. The levers were retracted from the test chamber for a short period after each response to control the speed at which the rats could complete the sequence (paced FCN). Changes in the average chain length may reflect the influence of impulsivity on the execution of behavioral patterns. Although they quickly learned to press the levers, SHR rats performed poorly compared to the WKY rats when the chain length requirement was increased to FCN 6 and FCN 8. Eventually stable performance was obtained under paced FCN 6, although the SHR rats continued to have a consistently lower average chain length. Both strains of rats were treated with imipramine (10 mg/kg), chlordiazepoxide (3 and 10 mg/kg), d-amphetamine (0.4 and 0.8 mg/kg), haloperidol (0.05 and 0.1 mg/kg), 8-OH-DPAT (0.1 mg/kg), WAY-100635 (0.1 mg/kg), and DOI (0.3 and 1.0 mg/kg). The SHR rats were less sensitive to the effects of d-amphetamine, chlordiazepoxide, and DOI and slightly more sensitive to the effects of haloperidol. All of these drugs reduced the average chain length. There was no difference in the response of the two strains to imipramine and 8-OH-DPAT, both of which increased the average chain length. These results support the suggestion that SHR rats may more impulsive than WKY rats. The data with d-amphetamine and haloperidol support biochemical findings that these rats have a deficit in dopaminergic function, and the strain differences in response to chlordiazepoxide and DOI suggest that that there may be differences in GABAergic and 5-HT2-mediated neurotransmission relevant to regulating impulse control in the rat.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1999

Perceived monogamy and type of clinic as barriers to seeking care for suspected STD or HIV infection: results from a brief survey of low-income women attending Women, Infants, and Children (WIC) clinics in Missouri.

BACKGROUND AND OBJECTIVES: Barriers to seeking care for sexually transmitted diseases (STDs) have not been assessed for low-income women. We sought to determine barriers to seeking care for STDs among women receiving Women, Infants, and Children (WIC) benefits in 21 Missouri counties. GOAL OF THIS STUDY: Provide information for promoting care-seeking behavior among low-income women suspecting STD infection. STUDY DESIGN: A survey of 2,256 women was conducted; 491 reported a history of at least one STD. These women indicated possible barriers to seeing a doctor about a suspected STD and preference for type of clinic providing STD services. RESULTS: More than one fifth (21.3%) of those reporting an STD also reported at least one barrier to seeing a doctor about suspected STD or human immunodeficiency virus infection. Among those reporting barriers, the most common barrier was "I only have sex with my steady" (36.2%) followed by being asymptomatic (33.3%), embarrassment (22.8%), and cost (25.7%). Most (63.8%) preferred seeing their own doctor, with others reporting preference for community health centers (14.8%), family planning clinics (16.8%), and STD clinics (4.6%). CONCLUSIONS: Low-income women experience multiple barriers to seeking care including perceptions about a protective value of monogamy. Also, STD services in locations providing other health services for women were preferred.

Adolescent↗
PubMed1998

Bridging the gap between science and practice: insight to researchers from practitioners.

Five policy advocates and practitioners provide recommendations to researchers to make research data more usable, accessible, and applicable for the field of human immunodeficiency virus (HIV) prevention among injecting and other drug users. Translating research into usable information will facilitate its use within political and policy discussions. When researcher and practitioners truly work together in a common enterprise, the result will be powerful HIV prevention programs that will save lives.

Communication Barriers↗
PubMed1996

Photochemically induced ischaemic lesion of the rat sciatic nerve. A novel method providing high incidence of mononeuropathy.

The incidence of behavioural signs of mononeuropathy in rats subjected to chronic constriction injury (CCI) of the sciatic nerve is unpredictable and often low. In the present study, an ischaemic lesion of the rat sciatic nerve was induced photochemically using a low power laser. In these rats tactile allodynia developed with a considerably greater incidence (95%) than in control rats subjected to CCI (45%). The allodynia lasted longer and was more prominent. Responses to thermal stimulation did not markedly differ between the two groups. The ischaemic lesions displayed marked degeneration, particularly of large myelinated fibres. The results suggest that laser irradiation of a peripheral nerve inducing a local photochemical reaction followed by Wallerian degeneration may be a convenient and reproducible experimental method of producing signs of peripheral mononeuropathy.

Animals↗
PubMed1994

Role of growth factors in degeneration and regeneration in the central nervous system; clinical experiences with NGF in Parkinson's and Alzheimer's diseases.

Neurotrophin-mediated mechanisms are integral to development and maintenance of the adult central nervous system. Neurotrophin expression has been shown to change rapidly in response to many different types of neuronal stress such as excitotoxic injury, mechanical lesions, epileptogenesis and ischemia. It therefore appears as if they are not only to be regarded as target-derived trophic factors in the classical sense, but also as providers of local trophic support and neuronal protection. These discoveries suggest that neurotrophins or compounds with neurotrophin-like actions might become useful in developing new treatment strategies, not only for neurodegenerative diseases, but also for other diseases and injuries to the nervous system including stroke.

Alzheimer Disease↗
PubMed1994

Photochemically induced spinal cord ischaemia in rats: assessment of blood flow by laser Doppler flowmetry.

A photochemical technique was used to create central nervous system ischaemia in rats. Changes in blood flow in the spinal cord were assessed by laser Doppler flowmetry. The Th11 spinal cord segment was irradiated by an argon ion laser after intravenous injection of an organic dye, erythrosin B, to rats with or without a laminectomy. In the group of laminectomized rats, laser irradiation for 5 s did not influence cord blood flow, but 10 s irradiation caused a 25% decrease of blood flow, which normalized within 20 min. Decreases of 50 and 80% in spinal cord blood flow were noted after 20 s and after 1 min of laser irradiation, respectively, with no recovery observed after 20 min. In the group of rats without a laminectomy, 1 min of laser irradiation caused approximately a 25% decrease of spinal cord blood flow, which gradually recovered within 12 min, whereas 5 min of laser irradiation caused a more severe reduction of spinal cord blood flow (45%) with some recovery was observed 30 min later. We could thus confirm that the interaction between a photosensitizing dye and laser irradiation reduced the regional spinal cord blood flow and the extent of this effect could be modified by varying the duration of laser irradiation. The present results therefore provide further support for using this photochemical technique to create animal models of central nervous system ischaemia.

Animals↗