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Biomedical subjects

R C Rogers

Publications and source records attributed to R C Rogers.

At least 73 records · Page 4Linked to original sources
PubMed1991

Uterine electromyographic activity in horse mares as measured by radiotelemetry.

The objective of this study was to determine if radiotelemetry could be used to measure myometrial electromyographic (EMG) activity. A radio transmitter with one pair of biopotential leads was implanted in the flank ipsilateral to the pregnant uterine horn at least five weeks prior to the expected date of parturition in two mares. The biopotential leads were implanted in the base of the pregnant uterine horn. Telemetered data were received by a pair of antennae placed at right angles in a 3.3 by 6.6-m stall. Data were recorded on VHS format videocassette tapes continuously for the 24h prior to and following parturition. Simultaneous physiograph recordings were made as a hard copy reference. In addition, 10 mg of prostaglandin F(2 alpha) was administered to two mares in the luteal phase of the estrous cycle. Myometrial EMG during parturition was increased similarly to that of previously published reports that used myometrial electrodes wired directly to a physiograph. Prostaglandin F(2 alpha) also caused an increase in myometrial EMG activity within 8 min of administration. This study demonstrated that radiotelemetry can be used for measuring myometrial EMG activity.

Journal Article↗
PubMed1990

Labetalol pharmacokinetics in pregnancy-induced hypertension.

Pharmacokinetic parameters of oral labetalol were studied in eight women with pregnancy-induced hypertension in the third trimester of pregnancy. Labetalol exhibited rapid absorption; peak serum concentrations of 881 +/- 219 ng/ml occurred at 20 minutes after labetalol ingestion. The terminal elimination half-life (mean, 1.7 +/- 0.27 hours) was found to be shorter than that reported for normotensive volunteers or nonpregnant hypertensive patients (mean, 6 to 8 hours). A mean apparent oral elimination clearance of 21.8 ml/min/kg compared favorably with that seen in other pregnant and nonpregnant populations. Food delayed the time to peak serum concentration to approximately 60 minutes. Labetalol was detected in fetal cord samples and amniotic fluid samples at concentrations approximately 50% and 16% that of simultaneous maternal vein samples, respectively.

Adolescent↗
PubMed1990

Activation of the bed nucleus of the stria terminalis increases gastric motility in the rat.

The diencephalic bed nucleus of the stria terminalis is known to make direct, peptide-containing axonal connections with the brainstem dorsal vagal complex, i.e., the nucleus of the solitary tract and the dorsal motor nucleus of the vagus. Given these anatomical data, one would predict that the bed nucleus, like other forebrain nuclei with similar connections, should function to alter parasympathetic autonomic functions. To examine this possibility, we activated the bed nucleus via electrical microstimulation and glutamate microinjections while monitoring gastric motility with miniature extraluminal strain gauges. We found that activation of the bed nucleus produced an increase in gastric motility that was atropine sensitive. This finding raises the possibility that the bed nucleus may be a significant forebrain regulator of gastrointestinal function.

Animals↗
PubMed1990

Oxytocin excites gastric-related neurones in rat dorsal vagal complex.

1. Dorsal medullary injections of oxytocin (OT) influence gastric motor and secretory function via a vagally mediated mechanism. Thus, it was hypothesized that OT altered the firing rate of brain stem vagal neurones that were specifically related to gastric function. 2. To study this, glass microelectrode/injection pipette arrays were used to record the activity of gastric-related neurones in the dorsal vagal complex (DVC), which includes vagal sensory neurones in the nucleus tractus solitarius (NTS) and motor neurones in the dorsal motor nucleus (DMN). After identifying such a neurone, spontaneous activity was monitored before and after micropressure injection of OT and vehicle solutions from the pipettes. 3. Two methods were used to identify neurones that were related to gastric function. One method employed a gastric balloon to identify DVC neurones that were responsive to gastric inflation. The second method employed a gastric vagal stimulating electrode, which permitted the identification of gastric-related NTS and DMN cells via orthodromic or antidromic activation, respectively. 4. Twenty-four of forty-two gastric-inflation-related neurones responded to administration of OT (100-400 fmol in 100-400 pl). The majority of those responding to OT were activated by this peptide (21/24). All the cells tested (n = 13) remained sensitive to gastric inflation after administration of OT. Also, OT was found to excite the majority of cells that were identified as gastric-related NTS (nine excited; one no effect) or DMN cells (eleven excited; two no effect). 5. These studies support the hypothesis that central oxytocinergic neurones influence gastric motility and secretion by increasing the excitability of central vagal neurones in the NTS and DMN that are related to gastric function.

Action Potentials↗
PubMed1989

Effects of TRH on the activity of gastric inflation-related neurons in the solitary nucleus in the rat.

Thyrotropin-releasing hormone (TRH) has been identified as a potent central regulator of gastrointestinal function. It has been hypothesized that TRH influences gastric function by modulating the effectiveness of gastric vago-vagal reflexes. To test this hypothesis, we studied the effects of TRH on neurons of the nucleus of the solitary tract (NTS) that respond to gastric inflation. Of the 23 inflation-sensitive neurons studied, 11 or 48% had reduced spontaneous activity after TRH injection; none were excited. These results provide evidence that a part of the TRH effect on the regulation of gastric function involves suppressing the NTS response to gastric afferent input from the vagus nerve.

Action Potentials↗
PubMed1989

Nucleus raphe obscurus (nRO) influences vagal control of gastric motility in rats.

Because the nucleus raphe obscurus (nRO) maintains a direct connection with the dorsal vagal complex in the medulla, this nucleus has the potential to influence vagal control of gastric function. Both electrical- and glutamate-induced activation of the nRO were found to enhance gastric motility and tone in the rat. The gastric responses to nRO stimulation were abolished by peripheral muscarinic blockade.

Animals↗
PubMed1989

Thyrotropin-releasing hormone: effects on identified neurons of the dorsal vagal complex.

Previous reports have demonstrated that intraventricular administration of thyrotropin-releasing hormone (TRH) markedly elevates parasympathetic efferent activity. The following study determined if this response could be attributed to an effect of TRH on the neurons in the dorsal motor nucleus of the vagus (DMN) and/or the nucleus tractus solitarius (NTS), the nuclei that comprise the dorsal vagal complex (DVC). Individual DMN or NTS units were identified electrophysiologically by using stimulating electrodes placed on the cervical vagus. Alterations in firing rate of identified cells in response to pressure injection of TRH (10-40 fmol in 10-40 pl) or equal volumes of artificial cerebrospinal fluid (ACSF) were monitored. Of the DMN cells that were responsive to TRH, all were excited, whereas all responsive NTS cells were inhibited by this peptide. TRH was characterized as potent and had long-lasting effects on cells in DMN and NTS. The action of TRH on both nuclei in the dorsal vagal complex may explain the powerful effects of this peptide on vagally mediated functions.

Animals↗
PubMed1989

Measuring workload in a newborn center pharmacy.

In order to identify and quantify tasks performed by pharmacists and technicians in the Newborn Center Satellite Pharmacy, a workload assessment using a time ladder log was performed. Two pharmacists and one technician documented their daily activities in 2-minute increments for 1 month. Tasks were divided into three categories: patient days, calendar days, and variable activities. The average time to perform each task was determined. Standard times for each category were recorded onto a monthly workload report, which was used to calculate full-time equivalents (FTEs) required to perform all tasks. The number of FTEs increased seasonally, as did the number of patient days. Therefore, this workload reporting system can be used to identify peak workload time periods and to justify staffing requirements.

Efficiency↗
PubMed1989

Fragile-X syndrome.

A fragile site on the X chromosome has been implicated in mental retardation and behavioral problems among both males and females. The fragile-X syndrome is second only to Down syndrome among causes of mental retardation associated with cytogenetic abnormalities. The clinical phenotype is extremely variable. During the early years, many affected children demonstrate normal or near-normal intellect and development. Folic acid may be of benefit before puberty.

Adult↗
PubMed1988

Dorsal medullary serotonin and gastric motility: enhancement of effects by thyrotropin-releasing hormone.

The effects of serotonin (5-HT) and thyrotropin-releasing hormone (TRH) on gastric motility patterns were investigated. Microinjection of serotonin (8 pmol in 4 nl) into the dorsal motor nucleus of the vagus produced a small increase in motility and tone, an effect which declined with repeated injections. As demonstrated previously, TRH (1 nmol in 1 microliter) applied to the surface of the dorsal medulla evoked a large increase in gastric motility and tone. After gastric motility returned to baseline following the TRH injection, we found that subsequent 5-HT injections, which previously evoked small changes in motility and tone, now evoked large increases in these indices. TRH augmentation of 5-HT-mediated effects on autonomic nuclei may be a significant feature in the alterations in gastric function that accompany the sleep-waking cycle and stress-related gastric pathology.

Animals↗
PubMed1988

Direct connections between the central nucleus of the amygdala and the nucleus of the solitary tract: an electrophysiological study in the rat.

Reciprocal connections between the central nucleus of the amygdala (CNA) and the nucleus of the solitary tract (NST) have been implied from anatomical studies in the rat and physiological studies in other species. Our work supports this conclusion in that microstimulation of the NST caused both antidromic and orthodromic activation of neurons in the CNA. The distribution of CNA neurons activated by NST stimulation suggests that the dorsomedial portion of the CNA provides input to the dorsal medulla while the ventrolateral CNA receives input from the NST.

Amygdala↗
PubMed1987

Cost savings with a new combination clindamycin-gentamicin admixture policy.

Clindamycin and gentamicin are frequently prescribed by obstetricians and gynecologists (OB-GYN) for various pelvic infections in women. These two antibiotics maintain chemical stability when admixed in a small-volume parenteral. The institution of an admixture policy that recommends combining these agents when both drugs are prescribed in OB-GYN patients would decrease the frequency of administration, improve patient convenience, reduce risk of administration errors and intravenous line contamination, and reduce costs of antibiotic therapy. The authors analyzed antibiotic use in OB-GYN patients over a 3-month period and found that the anticipated cost savings appeared sufficient to warrant an admixture policy change. Six months after initiating the new policy, the authors found an increase in the use of clindamycin and gentamicin, but a decrease in the overall cost for providing antibiotic therapy to OB-GYN patients. Savings for the second quarter were due to the pharmacy providing less expensive clindamycin-gentamicin therapy.

Clindamycin↗
PubMed1987

Fragile X syndrome: a common etiology of mental retardation.

Fragile X syndrome, second only to Down syndrome among etiologies of mental retardation, was discussed. Clinical, intellectual, and anthropometric characteristics from 67 fragile X positive males, 35 fragile X positive females, and 27 obligate carriers among 29 families was presented. Regression analysis showed little correlation between level of intellect and frequency of fragile sites. The mean IQ among the various age groups of male patients decreased with increasing age, and some intellectual deterioration could not be ruled out. Folic acid was suggested as a viable treatment mode among prepubescent males.

Female↗
PubMed1985

Convergence of vagal and gustatory afferent input within the parabrachial nucleus of the rat.

Our previous anatomical and electrophysiological studies demonstrated that first-order hepatic and gustatory afferents project to separate regions of the solitary nucleus (NST) and no intra-NST interaction of these two sensory systems could be demonstrated. However, iontophoretic injections of horseradish peroxidase into physiologically identified zones of the NST revealed that both of these regions send overlapping projections to the immediately subjacent parvocellular reticular formation as well as the postero-medial parabrachial nucleus (PBN). The present electrophysiological studies demonstrate that an interstitial zone of neurons in the caudal, medial PBN, indeed, receive convergent input from second-order gustatory and vagal afferents. Co-activation of these PBN units by the simultaneous arrival of both input sources frequently resulted in an additive interaction of evoked activity. PBN units lateral and caudal to this zone responded to vagal stimulation only, while units in the anterior and extreme medial portion of the PBN only responded to gustatory stimulation. By virtue of the efferent projections of the PBN, one might speculate that the convergence of information at this locus may, eventually, play a role in directing long term feeding behavior patterns such as learned taste aversion as well as the more transient changes in taste preference with visceral loading.

Animals↗
PubMed1985

Vagal afferent stimulation-evoked gastric secretion suppressed by paraventricular nucleus lesion.

Studies were performed to evaluate the possibility that the paraventricular nucleus (PVN) of the hypothalamus modulates gastric acid secretion by changing the sensitivity of the gastric secretory control mechanism to vagal afferent input. Under pentobarbital anesthesia, 17 rats were prepared with esophageal and pyloric catheters such that the stomach could be perfused continuously on a flow-through basis. Thus, acid secretion could be monitored throughout the experiment. Stimulating electrodes were attached to the central cut end of the cervical vagus nerve. Unilateral stimulation of cervical vagal afferents resulted in a substantial increase in gastric acid secretion. This vagal afferent-mediated increase in acid outflow was suppressed following a single PVN lesion ipsilateral to the side of afferent stimulated output. Given the nature of PVN connections with brainstem regions responsible for the elaboration of vago-vagal reflexes, our results suggest that the PVN may control gastric acid outflow by changing the gain of gastric vago-vagal reflexes.

Animals↗
PubMed1985

Gastric-vagal solitary neurons excited by paraventricular nucleus microstimulation.

Electrophysiological studies were performed to determine whether neurons of the nucleus of the solitary tract (NST) which receive sensory input from the stomach via vagal afferents are activated by microstimulation of the medial parvocellular division of the paraventricular nucleus of the hypothalamus (PVHmp). We found that 37% of the NST neurons orthodromically activated by gastric vagal nerve stimulation are also orthodromically excited by PVHmp microstimulation. Not only do these NST neurons receive convergent input from the PVHmp as well as gastric afferent input (vagal), but this input from the PVHmp may also bias the responsiveness of these NST neurons to incoming afferent information. This PVHmp influence on NST excitability is probably mediated by a direct, monosynaptic projection between these two nuclei. These data support the hypothesis that neurons in the PVHmp can control gastric function by altering the sensitivity of neurons which form the sensory limb of gastric vago-vagal reflexes. This ability of the PVHmp to bias the responsiveness of NST neurons to incoming vagal afferent information is probably mediated by a direct, monosynaptic projection between these two nuclei.

Afferent Pathways↗