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Biomedical subjects

B Wolfson

Publications and source records attributed to B Wolfson.

13 recordsLinked to original sources
PubMed1992

Identification of motile sperm in caput epididymis. Intraoperative observations and clinical correlations.

This retrospective review of patients who underwent vasoepididymostomy demonstrates that motile sperm may be identified in the most proximal portion of the epididymis, and implies that induction of sperm motility may be independent of transit through the epididymis. Although further studies are needed, the data imply that it may not be necessary to identify motile sperm in the epididymal fluid to achieve a successful vasoepididymostomy.

Adult↗
PubMed1989

Electrophysiological characteristics of neurons in neocortical explant cultures.

We examined the electrophysiological and morphological properties of neocortical neurons maintained in explant cultures prepared from the parietal cortex of newborn Sprague-Dawley rats. After 3-6 weeks in vitro, cultures showed regional differences in cellular density reminiscent of cortical layering, and an abundance of axonal processes. Pyramidal-shaped neurons with spinous dendrites were the dominant elements revealed by Lucifer yellow injections. Intracellular recordings revealed that many electrophysiological properties of neurons in the explants resembled those of neocortical neurons in vivo and in slice preparations. In response to depolarizing current injection, neurons in the explants showed the same three patterns of repetitive firing described in neocortical slices, as well as a similar array of responses. Spontaneous synaptic potentials were recorded from all neurons and complex PSPs were evoked in response to focal extracellular stimulation. GABAa receptors mediated a significant component of the evoked responses. Fifteen of sixty neurons generated action potentials that arose spontaneously from resting potentials. Neurons in many slices generated large, prolonged depolarizing potentials that reflected coordinated synaptic activity within the explants. These results underscore the usefulness of the neocortical explant as a valuable model for studying aspects of the behavior of circuits of cortical neurons.

Action Potentials↗
PubMed1989

Synchronized neuronal activities in neocortical explant cultures.

Intracellular recordings revealed that in neocortical explant cultures prepared on the day of birth and examined 3-6 weeks later, neurons mature and establish complex synaptic relationships that lead to spontaneous and triggered synchronous discharge. The spontaneous synchronous activity took several forms, including periodic generation of epileptiform depolarizing waves, prolonged periods of seizure-like discharge, and periodic, intense barrages of IPSPs. Synchronous depolarizations were associated with a marked increase in membrane conductance. Intracellular injection of currents of varying polarity and intensity affected their amplitudes and polarities without influencing the probability of their occurrence, indicating that the discharge reflected the synchronous activities of a neuronal population. This conclusion was confirmed with simultaneous recordings from pairs of neurons. Effects of the GABAa receptor antagonist, bicuculline, and the NMDA receptor antagonist, 2-aminophosphonvalerate (2APV), were used to assess the contributions of impairment of inhibition and enhancement of excitation to the initiation of synchronous discharge. The frequency with which spontaneous depolarizations were generated in normal medium was markedly reduced by 2APV. Moreover, seizure-like activity was induced by removing Mg++ from the medium, a condition that enhances conductance through NMDA receptor-coupled channels. This behavior was also attenuated by 2APV. Perfusion of bicuculline was potently epileptogenic. 2APV cut short the late, voltage-dependent phase of bicuculline-induced paroxysmal depolarizations, indicating a role of NMDA receptors in generating this component of the wave. Epileptiform activities induced by withdrawal of Mg++ were greatly augmented by bicuculline, indicating that blockade of inhibition was not a prerequisite for seizure-like activity. This conclusion is supported by the finding that in many neurons in untreated cultures, paroxysmal generation of trains of IPSPs was the primary manifestation of spontaneous, synchronous population discharge.

2-Amino-5-phosphonovalerate↗
PubMed1985

Postsynaptic actions of neurotensin on preoptic-anterior hypothalamic neurons in vitro.

This study examines the effects of neurotensin (NT) on single neurons in explants of the preoptic-anterior hypothalamus (POAH) in vitro. Standard in vitro electrophysiological techniques were employed. Cultures were prepared from newborn rats and maintained in roller tubes for 3-4 weeks. NT was administered either through the superfusion fluid or via micropressure ejection (0.5-10 psi). Pressure ejection of NT produced a consistent, dose-related, excitatory effect on 71% of the cells studied. The remaining cells were either unresponsive to NT or inhibited by it. In addition, the excitatory effects of microiontophoretically applied glutamate (10-100 nA) were markedly enhanced by NT applied at concentrations that did not alter spontaneous rate. The effects of NT at higher concentrations were additive with glutamate. The effects of NT persisted in Ca2+-free medium when synaptic activity was suppressed. These data indicate that NT exerts a potent excitatory effect on single neurons in the POAH in vitro. Moreover, this effect proved to be additive with that of glutamate. The persistence of these effects in Ca2+-free medium suggests that the actions of NT are postsynaptic in nature.

Animals↗
PubMed1985

In situ hybridization of putative somatostatin mRNA within hypothalamus of the rat using synthetic oligonucleotide probes.

The distribution of mRNA with high sequence homology to somatostatin mRNA within the periventricular hypothalamus of rat was assessed using in situ hybridization techniques with synthetic oligodeoxyribonucleotide probes, complementary to the 3' coding region of rat somatostatin mRNA. The probes (22- and 24-mers) were 5'-end labeled using T4 polynucleotide kinase and gamma-32P-ATP. They were used either individually or after ligation with T4 DNA ligase to form a 46-mer. Serial tissue sections (less than 10 microns) were taken from the level of the preoptic/anterior hypothalamus through the paraventricular hypothalamus. In situ hybridizations were conducted at room temperature in hybridization buffer. Neurons immunoreactive with antiserum raised against somatostatin were identified in alternate sections using standard immunocytochemical procedures. The anatomical location of the hybridization signal was determined by autoradiography. Our results show that the peri- and paraventricular hypothalamus is rich in transcripts putatively coding for somatostatin and that these transcripts are co-distributed with neurons immunoreactive with antisomatostatin immunoglobulin.

Animals↗
PubMed1985

Actions and interactions of neurotensin on preoptic anterior hypothalamic neurons in vitro.

Considerable evidence has accumulated, suggesting that neurotensin (NT) interacts with neurotransmitter systems in the CNS. The purpose of this study was to investigate possible neurophysiological interactions between NT and putative neurotransmitters endogenous to the preoptic anterior hypothalamus (POAH). Using standard in vitro recording techniques, extracellular single unit activity was monitored in explant tissue cultures prepared from the POAH of newborn rats. Drugs were applied through the superfusion system or inotophoretically or pneumatically through micropipettes. Neurotensin produced a potent excitatory effect which enhanced lutamate induced excitations. In contrast, neurotensin reduced the effects of acetylcholine and had no effect on the actions of GABA and dopamine. These results suggest that interactions between NT and putative neurotransmitters in the POAH are highly specific.

Acetylcholine↗
PubMed1978

Anesthetic indices--further data.

Anesthetic indices for methoxyflurane, enflurane, and isoflurane in oxygen and halothane in nitrous oxide and oxygen (50:50), were determined in rats using measurements of heart and brain concentrations of the volatile agents at the endpoints of anesthesia, respiratory arrest and cardiac failure. The indices related respiratory arrest to anesthesia (respiratory index-A1r), cardiac failure to anesthesia (cardiac index-AIc) and respiratory arrest to cardiac failure (cardiorespiratory index-AIcr). Isoflurane had a significantly higher AIr (3.1) and AIc (5.7) than enflurane (AIr 1.8, AIc 3.3), methoxyflurane (AIr 2.2, AIc 3.7) and halothane in nitrous oxide and oxygen (AIr 2.4, AIc 3.7). These indices were also higher than those previously determined for halothane (AIr 2.3, AIc 3.0). Isoflurane had a higher AIcr (1.9) than halothane (1.6). Enflurane had a significantly lower AIr (1.8) than any of the other agents studied. These findings suggested a greater margin of safety for isoflurane, especially with respect to the heart, and a greater potential for respiratory depression for enflurane than for the other agents. Nitrous oxide decreased the amount of halothane necessary to produce anesthesia, but also that needed to produce respiratory arrest or cardiac failure. The addition of nitrous oxide, therefore, did not significantly enhance the overall safety of halothane anesthesia with respect to potential respiratory or cardiac depression.

Anesthesia, Inhalation↗
PubMed1975

A technique of ventilation during laryngoscopy and bronchoscopy.

A technique for ventilating patients thorugh a catheter with nitrous oxide and oxygen utilizing the venturi principle is described for patients undergoing laryngoscopy or bronchoscopy. Arterial blood-gas measurements in 34 patients reveal that ventilation was adequate.

Atropine↗
PubMedDate not supplied

Primary explants as a model of the hypothalamus in situ.

Anatomical and electrophysiological studies with neurotensin and somatostatin were performed to assess the integrity of primary explants of the preoptic anterior hypothalamus (POAH) maintained in organ culture as a model to study peptidergic neurons in vitro. POAH neurons maintained in vitro were found to be morphologically similar to those visualized histologically in situ. Somatostatin- and neurotensin-immunoreactive neurons were also present in both preparations. Additionally, electrophysiological responses of neurons in vitro to neurotensin and somatostatin were qualitatively similar to neuronal responses in situ. The striking morphological and pharmacological similarity between POAH neurons in vitro and in situ suggests that primary explants of the POAH are organotypic.

Animals↗
PubMedDate not supplied

"Precurarization" using pancuronium.

A study comparing tubocurarine and pancuronium for precurarization indicates that either successfully attenuates fasciculation after succinylcholine administration. However, if the aim is to prevent or attenuate such side effects of succinylcholine as cardiac arrhythmias, hyperkalemia, and increased intraocular pressure, there is as yet no proof that pancuronium will be effective in these areas.

Adult↗
PubMedDate not supplied

Changes in airway resistance following droperidol, hydroxyzine, and diazepam in normal volunteers.

The effects of droperidol, hydroxyzine, and diazepam on airway resistance (AR), functional residual capacity (FRC), and thoracic gas volume (TGV) were compared, using a CPI model-2000 body plethysmograph. Significant decreases in AR were seen following droperidol and hydroxyzine at all time intervals. A significant increase in AR also was noted 90 minutes after diazepam injection. FRC significantly decreased at 60, 90, 120, and 150 minutes following droperidol, and at 90 minutes following hydroxyzine, while no change was seen following diazepam. No significant changes in TGV were seen following administration of any of the drugs.

Adult↗