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Biomedical subjects

J Swann

Publications and source records attributed to J Swann.

17 recordsLinked to original sources
PubMed2001

The main olfactory system mediates pheromone-induced fos expression in the extended amygdala and preoptic area of the male Syrian hamster.

Copulation in male hamsters is stimulated by exposure to vaginal secretions of conspecifics. These pheromones also stimulate fos expression in neural areas that regulate copulation including: the medial nucleus of the amygdala, the bed nucleus of the stria terminalis, and the preoptic area. The pheromones in vaginal secretions are detected by both the main and accessory olfactory systems. However, the accessory system plays the greater role in the regulation of mating behavior and has direct connections with the medial nucleus of the amygdala and bed nucleus of the stria terminalis. The goal of the present study was to determine which system mediates the effect of pheromones on the stimulation of more central areas by deafferenting these systems in experienced male hamsters before exposure to vaginal secretions. Destruction of the receptors in the main olfactory system with zinc sulfate eliminated the increase in fos immunoreactivity in the amygdala, bed nucleus of the stria terminalis and preoptic area following exposure to sexually stimulating pheromones. Deafferentation of the accessory olfactory system by removing the vomeronasal organ had no effect on pheromone-induced fos expression in these areas. We conclude that neurons expressing fos following exposure to vaginal secretions are stimulated via the main olfactory system and are not associated with the expression of copulatory behavior.

Amygdala↗
PubMed1999

Maximizing the contribution doctors make to NHS management.

Management is an increasingly important issue for many doctors. If doctors wish to influence resource allocation, they must involve themselves in health service management. This article describes the results of an enquiry action learning project involving six doctors. As part of the project, clinical directors and their business managers were interviewed. In addition, the Police Force and BAA (formerly the British Airport Authority) were visited and their management structure, out-of-hours activities and planning for emergencies assessed. This article examines the reasons why many doctors do not involve themselves in management, such as increased time commitment and negative peer pressure, and suggests some solutions to these problems, including the need for a wider understanding of the role of clinical directors. It also considers how some organizations are already starting to address these issues, and how both doctors and hospitals can benefit from greater involvement of doctors in health service management.

Attitude of Health Personnel↗
PubMed1998

Medication patterns of recurrent headache sufferers: a community study.

This community-based telephone survey determined medication patterns of 274 frequent headache sufferers who reported 12 or more headaches a year. Headaches were classified using the International Headache Society's (IHS) criteria. Participants reported on 465 types of headaches: 129 tension headaches, 158 migraine headaches, 8 chronic tension headaches, and 148 headaches which were unclassifiable using IHS criteria. Females (n = 133) reported an average of 1.9 types of headache and males (n = 141) reported 1.5 headache types. Fifty-six percent of respondents used acetaminophen for tension-type and 60% used acetaminophen for migraine. One percent used prescription medication for tension headache and 12% used prescriptions for migraine. The perceived effectiveness of over-the-counter medication was approximately 7 on a scale of 0-10 for tension headaches and 6 for migraine. Both tension-headache and migraine-headache sufferers waited about 1 h before taking any medication. Tension-headache sufferers waited until the headache was above 5 on a 0 to 10 scale (4.6 for migraine). It is possible that more aggressive use of medication might improve headache management.

Adolescent↗
PubMed1997

Sex differences in function of a pheromonally stimulated pathway: role of steroids and the main olfactory system.

Exposure to the pheromones contained in female hamster vaginal secretions (FHVS) produces stereotypic, sex-specific behaviors in Syrian hamsters. Using Fos as a marker of neuronal stimulation we have found that (1) FHVS stimulates neurons in the posterior subdivision of the medial nucleus of the amygdala (MeP), the posterior medial subdivision of the bed nucleus of the stria terminalis (BNSTpm), and the magnocellular subdivision of the medial preoptic nucleus (MPN mag); (2) this stimulation is mediated by the main olfactory system; (3) stimulation of the MPN mag is regulated by testosterone in males; (4) stimulation of the BNSTpm and MeP is regulated by testosterone in females; and (5) FHVS does not induce Fos production in the MPN mag in females regardless of the hormonal state. These results support the hypothesis that the main olfactory system plays an important role in the regulation of pheromonally driven behaviors, identifies functional sex differences in pathways that regulate these behaviors, and emphasizes the different roles of the BNSTpm, MeP, and MPN mag in the regulation of male copulatory behavior.

Amygdala↗
PubMed1993

Substance P and neurokinin A are colocalized in the central chemosensory pathway of the male golden hamster.

The medial nucleus of the amygdala, bed nucleus of the stria terminalis and medial preoptic area play critical roles in the regulation of mating behavior in the male hamster. Destruction of these nuclei or the pathways that connect them severely disrupt copulation. We have begun identifying the neuropeptides contained in these neurons as a prelude to determining the role of peptide neurotransmitters in the regulation of male copulatory behavior. We have found that substance P is localized within these neurons and is regulated by gonadal steroids. In this study we report 1) that a closely related peptide, NKA (substance K), is also present in the medial nucleus of the amygdala, the bed nucleus of the stria terminalis and the medial preoptic area; 2) that all those neurons which contain SP also contain NKA and 3) testosterone also regulates the production of NKA. Thus, NKA may also play a role in the regulation of male copulatory behavior.

Amygdala↗
PubMed1991

Sensitization to noise-mediated induction of seizure susceptibility by MK-801 and phencyclidine.

The effect of single administrations of MK-801 (5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine) or PCP (phencyclidine) on the induction of audiogenic seizure susceptibility by noise in immature rats was examined. Treatments with these non-competitive N-methyl-D-aspartate (NMDA) receptor antagonists resulted in increases in noise exposure-dependent susceptibility. In neonatally drug-treated rats, seizures during adulthood were found to occur with significantly higher incidence and severity. Furthermore, drug treatments were found to lengthen what is normally a restricted developmental period within which susceptibility can be induced by noise exposure. The drugs, however, had no inherent ability to induce audiogenic seizure susceptibility if given alone. Moreover, in already-susceptible rats, MK-801 exhibited predictable anticonvulsant effects. These data suggest acute PCP or MK-801 exposures may transiently exacerbate risks inherent in certain forms of trauma. The mechanism underlying these effects is unknown although certain inferences are possible and may reveal much about epileptogenesis in this model.

Acoustic Stimulation↗
PubMed1988

N-methyl-D-aspartate (NMDA) receptors are inactivated by trypsin.

Acute isolation of hippocampal CA3 pyramidal cells using trypsin produces neurons which respond to kainate and quisqualate but not N-methyl-D-aspartate (NMDA). Incubation of 6- to 12-day-old cultured hippocampal neurons or slices of pyriform cortex with trypsin irreversibly removes the NMDA responses normally present without significant effect on responses to kainate or quisqualate. These data indicate that the NMDA receptor has a trypsin-sensitive component which is necessary for agonist recognition or ion channel activation.

Action Potentials↗
PubMed1982

Cycle of lordosis behavior in female hamsters whose circadian activity rhythm has split into two components.

Within 75 days of exposure to constant light (LL), the circadian activity rhythm of 21 of 32 hamsters had dissociated or "split" into two distinct components. These components were labeled either evening (E) or morning (M) depending on whether they appeared to be derived from the E or M portion of the activity phase prior to the occurrence of "splitting." Both regular (i.e., 4-day) and irregular (i.e., non-4-day) cycles in lordosis behavior were observed in all of the animals with an intact activity rhythm and in 18 of the 21 animals with a split rhythm of activity. The onset of behavioral estrus always occurred near the time of the onset of locomotor activity in animals with an intact activity rhythm. Among the females with a split activity rhythm, seven showed lordosis onsets only near the onset of the E component whereas five others began lordosis behavior only near the onset of the M component. Importantly, in five animals the onset of lordosis was associated on different days with either the E or M component. These results indicate that cycles in lordosis behavior persist even after the circadian rhythm of activity has dissociated into two components, and that at least one component of the estrous cycle, onset of lordosis behavior, can be coupled to either of two oscillators that underlie the circadian rhythm of locomotor activity in hamsters.

Animals↗
PubMed1977

Phenylethanolamine: a new putative neurotransmitter in Aplysia.

Phenylethanolamine is present in the Aplysia nervous system in concentrations similar to that of octopamine. These are receptors that are very specific for phenylethanolamine, which on different neurons mediate sodium, chlorine, or potassium conductance increase responses. These observations indicate that phenylethanolamine may act as a neurotransmitter in Aplysia.

Animals↗
PubMedDate not supplied

Ontogenetic features of audiogenic seizure susceptibility induced in immature rats by noise.

Although numerous models are currently used for systematic study of the mechanisms of epileptogenesis in mature brain, few animal models have been developed that allow similar explorations in the developing nervous system. One experimental model of epilepsy supports a premise that perinatal experience can lead to eventual seizure susceptibility, however. Audiogenic seizure (AGS) susceptibility can be induced during a critical developmental period in normal mice by auditory deprivation and therefore by cochlear trauma. We studied the developmental parameters that affect success of both induction and testing of AGS-susceptibility in the rat. Intense high-frequency noise exposure was used as the traumatizing agent. The Wistar rat strain used is inherently seizure-resistant because in greater than 400 trials, untreated rats have never exhibited susceptibility at any age. Although single prolonged exposures to high-intensity noise were administered to groups of rats at ages between postnatal days (PNDs) 12 and 36, PND 14 was the age when exposure was most likely to result in eventual seizure susceptibility. Furthermore, duration of initial exposure on PND 14 determined the rate of susceptibility when measured 2 weeks later. Accordingly, we noted that single noise exposures at an intensity of 125 dB and ranging between 6 and 10 min in duration induced susceptibility in 100% of rats tested on PND 28; nonetheless, seizures among the rats exposed for 8 min were the most severe. Typically, these seizures began as wild running attacks and were followed by tonic/clonic convulsions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMedDate not supplied

Sperm function and structure and seminal plasma prostanoid concentrations in men with IDDM.

Semen from 18 men with insulin-dependent diabetes mellitus (IDDM) aged 20-40 yr was compared with that from 15 age-matched control subjects. Although semen volume, sperm count, and spermatozoal motility were similar in the two groups, semen from diabetic men had significantly greater numbers of abnormal spermatozoa and significantly lower ability to penetrate hamster eggs. Concentrations of prostaglandins E2, F2 alpha, and I2 and thromboxane A2 were significantly elevated in the seminal plasma from semen of diabetic subjects compared with control subjects. These observations indicate the need for a careful assessment of fertility in diabetic men, the mechanisms underlying the abnormalities in spermatozoa, and the relationship of these abnormalities to the increase in prostanoid concentrations in diabetic men.

6-Ketoprostaglandin F1 alpha↗