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Biomedical subjects

E F Bond

Publications and source records attributed to E F Bond.

15 recordsLinked to original sources
PubMed1992

Mediation of thyrotropin-releasing hormone induced gastric motility increases in developing rats.

Centrally administered thyrotropin-releasing hormone (TRH) induces vagally mediated gastrointestinal effects which may be cholinergic, serotonergic or a combination. This study investigated mediation of TRH-stimulated gastric motility in developing rats. A serotonin (5-HT) antagonist (5-HT2, ketanserin or xylamidine; 5-HT3, MDL 72222) or an acetylcholine receptor blocker (atropine) was administered intraperitoneally 30 min prior to intracisternal TRH (5-10 micrograms). The 5-HT-depleting para-chlorophenylalanine (p-CPA) was administered 48 or 72 h prior to TRH. Gastric motility, monitored via extraluminal strain gauge, was not increased with TRH in atropine-pretreated rats. MDL 72222 had a significant age-related effect on TRH-induced gastric motility increases while 5-HT2 antagonists and p-CPA treatment did not. Thus, acetylcholine receptor blockade inhibits TRH-stimulated gastric motility in young and adult rats while 5-HT3 antagonism eliminates the motility response in young (7 and 10 days) rats.

Aging↗
PubMed1992

A possible 5-HT3 component of thyrotropin-releasing hormone-induced increases in gastric motility in developing rats.

Intracisternal injection of thyrotropin-releasing hormone (TRH) increases gastric motility primarily via a vagal cholinergic mechanism. However, a serotonergic (5-HT) component may also exist. Rats (7, 10, 14, and > or = 50 days of age) were anesthetized and gastric motility monitored via an extraluminal strain gauge. Following baseline, ICS 205-930 which blocks 5-HT3 and 5-HT4 receptors (0.01, 0.10, or 1.0 mg/kg) was administered intraperitoneally, then 30 min later intracisternal TRH (5 or 10 micrograms). ICS 205-930 0.1 and 1.0 mg/kg blocked TRH-induced motility in 7-day-old rats. Results support a 5-HT3 or 5-HT4 receptor contribution to TRH-induced gastric motility stimulation, and suggest that receptor expression is dynamic during development.

Animals↗
PubMed1991

Morphine inhibits TRH-induced gastric contractile activity.

This study investigated the effect of centrally and peripherally administered thyrotropin releasing hormone (TRH) on gastric contractile activity of rats 14, 21, 28 and adult (greater than or equal to 50) days (D) of age, and the effect of morphine pretreatment on that response. Rats were anesthetized with urethane, then a tension transducer was implanted on the anterior gastric corpus. Following baseline recording, rats were pretreated with intraperitoneal morphine (2 mg/kg). TRH (5 micrograms) in saline or saline alone (0.6 microliters) was then injected into the cisternum magnum. Additionally, dose response to TRH was examined in 14- and 50-day-old rats. Intracisternal TRH induced a dose-related increase in gastric contractile activity in both 14- and 50-day-old rats. Higher doses of TRH (10 and 30 micrograms) prolonged the response as compared to low doses. Peripheral morphine pretreatment blocked the TRH-induced increase in gastric contractile activity in all age groups although a higher morphine dose (10 mg/kg) was needed to block the effect in 28D rats. Intravenous TRH (5, 10, 30 micrograms) produced an increase in gastric contractile activity in 14D rats which was blocked by vagotomy.

Animals↗
PubMed1990

Age-related variations in jejunum and distal colon contractile response to thyrotropin-releasing hormone in vitro.

The effects of thyrotropin-releasing hormone (TRH) on the contractile activity of the proximal jejunum and distal colon of 3-, 7-, 14-, 21-, 28-, 50-day-old and adult male Sprague-Dawley rats were examined. Longitudinal segments were mounted in force displacement transducers and bathed in oxygenated, buffered Krebs' solution. In the proximal jejunum TRH 10(-6) M produced a tetrodotoxin (TTX)-sensitive tension increase in 3- to 14-day-old rats and a TTX-resistant biphasic response in older rats. TRH 10(-6) M produced a transient tension in the distal colon of rats less than or equal to 21 days old. Incubation with TRH 10(-6) M for 30 min increased responsiveness to acetylcholine 10(-7) M in approximately 50% of tissues studied. Direct and indirect effects of TRH are developmentally determined.

Acetylcholine↗
PubMed1981

A new approach to the study of the E. coli nucleoid.

E. coli were examined by the freeze-fracture thaw-fix technique, embedded in thin fibrin gels. After glutaraldehyde fixation the bacterial nucleoid was found spread out over the surrounding fibrin. Addition of calcium and uranyl acetate to the fixative preserved the nucleoid in compact form. The spread nucleoid was then examined against a smooth mica background after freeze-thaw and osmotic lysis. These spreads were critical-point dried, rotary shadowed with platinum-carbon and viewed as stereo-pair micrographs. Structures seen are tentatively interpreted as clusters of polyribosomes, extended DNA, and supercoiled DNA complexed with proteins or polyamines. After osmotic lysis, glutaraldehyde alone preserves the nucleoid in compact form. Only where strands are broken, in freeze-fracture or freeze-thaw lysis, must uranyl acetate be added to the fixative to preserve a compact structure.

Bacterial Proteins↗
PubMed1979

Three-dimensional view of the chromatin in freeze-fractured chicken erythrocyte nuclei.

The freeze-fracture thaw-fix (FfTF) technique described in earlier papers is applied in the present work to more detailed study of the chicken erythrocyte, by transmission replicas and high resolution scanning electron microscopy (3 nm scan beam size). The three-dimensional structure of the chromatin, and possibly the non-histone protein matrix, of fractured nuclei is to a large extent retained in this method of preparation and seen in stereomicrographs. In these micrographs the helical sub-structure of the 25 nm chromatin strands can be seen at about the same resolution as that of previously published micrographs in which extracted chromatin is viewed by negative contrast or after metal shadowing. The useful resolution of the secondary electron micrographs, for a suitably mounted specimen, is shown to be as good as that of transmission micrographs of platinum-carbon replicas of the same material.

Animals↗
PubMed1976

Improved resolution in cathodoluminescent microscopy of biological material.

This paper continues work reported in an earlier paper on modification of a Cambridge Stereoscan Mk IIA to improve the quality of cathodoluminescent micrographs of biological material. In the work presently described the microscope gun has been offset laterally by 2 mm, to prevent light from the filament passing down through the column to the specimen chamber. The electron beam is brought onto the column axis by deflection coils. This modification effectively eliminates background light in the chamber, and a full parabolic mirror is fitted to maximize light collection. Results for yeasts and wheat seed sections are described.

Microscopy, Electron, Scanning↗
PubMedDate not supplied

Morphine inhibits TRH-induced intestinal transit increases.

The current study examined the effects of intraperitoneal (IP) and intracisternal (IC) administration of the opiate agonist, morphine, and an opioid, central beta-endorphin, on thyrotropin releasing hormone (TRH)-induced small intestinal transit increases. Anesthetized rats, 14-day and older, were studied to determine age-related differences. Results showed that in all age groups IP morphine (2 mg/kg) blocked TRH (15 micrograms)-induced increases in transit of a charcoal bolus. Morphine 1 microgram and beta-endorphin 1 microgram administered IC in 0.6 microliter failed to block TRH (10 microgram)-induced increases in intestinal transit in 14-day-old rats. However both morphine and beta-endorphin 1 micrograms IC blocked TRH-induced increases in adult rats. Dose-response studies demonstrated that higher doses (greater than 1 microgram) of morphine IC were required to block TRH-induced increases in preweaning rats.

Aging↗
PubMedDate not supplied

Menstrual cycle factors related to increased gastric contractile response to tube feeding.

Evidence exists that the ovarian hormones have a modulating effect on gastrointestinal (GI) motility, yet details are sketchy and little attention has been paid to the effect that fluctuating hormone levels might have on women who are receiving enteral feedings. This study compared gastric motility indices in response to tube feedings at two points in the menstrual cycle, concurrently measured ovarian hormone levels, and described three potentially related factors (ie, GI symptoms, uterine cramping pain, reports of daily stressors). Intragastric motility responses to enteral feedings were obtained on 28 women (aged 19-37) during menses and midfollicular phases of two menstrual cycles. Intragastric pressure changes were monitored by an open-tipped cannula method at rest, during and after tube feeding (Ensure, 240 ml at 8 ml/min). Serum estradiol and progesterone levels were measured by radioimmunoassay. Women completed a daily diary of symptoms and stressors throughout the two menstrual cycles. Results showed that intragastric pressure amplitudes and frequencies were higher at menses compared with midfollicular recordings. At menses, prefeeding and feeding gastric pressure amplitudes were positively correlated with uterine cramping pain and GI symptoms (ie, nausea). At menses, postfeeding contraction frequencies were also correlated with uterine cramping pain. At midfollicular phase, progesterone levels correlated with gastric motility indices; number of stressors indirectly correlated with gastric motility indices. These data suggest that gastric responses to enteral feeding are influenced by menstrual cycle phase.

Adult↗
PubMedDate not supplied

GI symptoms, function, and psychophysiological arousal in dysmenorrheic women.

In a previous study, gastrointestinal (GI) symptoms and stool characteristics were found to be influenced by menstrual cycle phase. The current study was designed to replicate initial work regarding GI symptoms and stool characteristics and to explore the relationships between GI symptoms, stool characteristics, ovarian hormone levels, and indicators of psychophysiological arousal. Fifty women (dysmenorrheic, N = 22; nondysmenorrheic, N = 28) maintained a daily dairy for recording stool characteristics, GI symptoms, and daily anxiety level. First morning void urine specimens for catecholamine assays and serum samples for ovarian hormone and cortisol determinations were obtained at menses, follicular, and luteal phases. Results showed menstrual cycle-related differences in stool characteristics and report of GI symptoms, with the greatest changes occurring at menses in the total sample. Dysmenorrheic women reported higher levels of all GI symptoms at menses as compared to nondysmenorrheic women. In addition, cycle-related differences in serum cortisol, urine catecholamines, and report of anxiety were also noted, particularly in dysmenorrheic women. However, looser stools and GI symptoms at menses were not correlated with absolute levels of ovarian hormones or indicators of psychophysiological arousal.

Adult↗