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Biomedical subjects

M M Heitkemper

Publications and source records attributed to M M Heitkemper.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

Nursing research opportunities in enteral nutrition.

The concepts of individual adaptations, environmental, and person factors have been suggested as components of a framework for considering existing and potential investigations of enteral feeding as a therapeutic modality. Much of the work regarding adaptations to enteral feeding have described the pathophysiological and experimental responses of individuals--that there is less emphasis on the physiological and behavioral responses is evident in the literature. Also, little investigation has been focused on the environmental risk factors or the person vulnerability factors that are associated with less than optimal adaptations to enteral feeding. However, it is the understanding of all three of these aspects that will lead to comprehensive strategies for promoting satisfactory adaptations. To date, the majority of clinical therapeutic studies have focused on obviating or managing untoward reactions to enteral feeding by manipulating environmental physical factors. Certainly, more needs to be done, particularly with respect to temporal and rhythmicity considerations. However, there is an obvious lack of information about manipulating social circumstances or person factors (such as, knowledge deficit) for therapeutic ends. Examination of the multiple dimensions of patient responses to enteral nutrition modalities, the interaction of these various dimensions (concentrating on the social and person), and the physical elements is congruent with the holistic and caring nature of nursing practice and should guide future study.

Adaptation, Physiological↗
PubMed1987

Adrenalectomy and pentagastrin effects on gastrointestinal cholinergic enzyme activities.

The present study examined the effects of pentagastrin and adrenalectomy on choline acetyltransferase (ChAT) and acetylcholine esterase (AChE), enzymes which synthesize and degrade acetylcholine in the rat gastrointestinal tract. Adrenalectomized and non-adrenalectomized rats, 14 and 21 days old, were treated with either pentagastrin (250 micrograms/kg i.p.) or saline for 7 days. Rats were sacrificed at 21 and 28 days of age. Adrenalectomy- and pentagastrin-treated 21-day-old rats had greater ChAT activities than those treated with pentagastrin alone, while AChE activities were higher in the pentagastrin-treated group. Adrenalectomy- and pentagastrin-treated 28-day-old rats had lower levels of activity as compared to pentagastrin-treated rats. The adrenal gland does appear to influence the response of cholinergic enzyme activities to pentagastrin.

Acetylcholinesterase↗
PubMed1986

Pentagastrin on neurotransmitter enzyme activities in the rat gastrointestinal tract.

The effects of three doses (5, 100, and 250 micrograms/kg) of pentagastrin on the activities of choline acetyltransferase (ChAT) and acetylcholine esterase (AChE), the neurotransmitter enzymes that synthesize and degrade acetylcholine, and monoamine oxidase (MAO), the degradation enzyme for catecholamines, were investigated. Enzyme activities were assayed in 6 gastrointestinal segments of 21- and 28-day-old and adult rats. All animals were injected intraperitoneally for 7 days with pentagastrin, and the results were compared with age-matched controls receiving saline for 7 days. Plasma and adrenal corticosterone levels were measured. No consistent differences in adrenocortical variables existed between pentagastrin- and saline-treated animals. Similarly, no consistent pentagastrin dose responses of ChAT, AChE, and MAO activities were evident. However, at the highest dose pentagastrin generally produced increases in ChAT activities in 21- and 28-day-old rats, while producing decreases in AChE and MAO activities in 21-day-old rats and increases in 28-day-old animals. There were few significant differences in enzyme activities in adult rats receiving pentagastrin as compared to saline.

Acetylcholinesterase↗
PubMed1986

Effects of corticosterone and metyrapone on gastrointestinal neurotransmitter enzyme activities.

Adrenal glucocorticoids have been shown to produce alterations in the enzymes which synthesize and degrade cholinergic and catecholaminergic neurotransmitters in the central and peripheral nervous system. The present study examined the impact of altering plasma corticosterone levels via corticosterone or metyrapone ingestion, via the drinking water, on the developmental profile of choline acetyltransferase (ChAT), acetylcholine esterase (AChE), tyrosine hydroxylase (TH) and monoamine oxidase (MAO) in various gastrointestinal (GI) segments of rats. Three groups were studied: non-treated, corticosterone treated and metyrapone treated. Drug intake of pregnant (i.e., beginning on the 15th day of gestation), lactating and weaned rats was monitored until the male pups were sacrificed at 1, 3, 7, 14, 21, 35 and 50 days of age. Results showed that ChAT and TH activities peaked earlier in development in corticosterone treated rats as compared to non-treated and metyrapone treated rats. During the early postnatal period plasma corticosterone levels were inversely related to AChE and MAO activities in most GI segments. These results indicate that neurotransmitter enzyme activities in various GI segments are influenced by corticosterone during a critical period of development.

Acetylcholinesterase↗
PubMed1983

Development of neurotransmitter enzyme activity in the rat gastrointestinal tract.

Acetylcholine and norepinephrine play important roles in determining gastrointestinal (GI) tract motility and secretion. At this time, however, little is known concerning the postnatal developmental patterns of the enzymes that synthesize and degrade these two neurotransmitters within the GI tract. The present study examined the developmental activities, expressed per gram protein per minute, of the cholinergic enzymes choline acetyltransferase (ChAT) and acetylcholine esterase (AChE) and the adrenergic enzymes tyrosine hydroxylase (TH) and monoamine oxidase (MAO) in male rats between days 1 and 50. Seven anatomic segments of the GI tract were assayed for enzyme activities. In general, all four neurotransmitter enzymes were present throughout the length of the GI tract and increased during the early postnatal period. The synthesizing enzymes ChAT and TH displayed peak activity prior to day 21, while the degrading enzymes AChE and MAO continued to increase past day 21. Each enzyme exhibited segmental differences and unique postnatal developmental patterns. Such differences in enzyme activities may be related to developmental increases in neuronal density, hormonal factors, or direct stimulation of the GI tract by liquid and/or solid diet.

Acetylcholinesterase↗
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

Morningness-eveningness and early-morning salivary cortisol levels.

The purposes of this exploratory study were: (1) to describe a 2-h segment of the early-morning salivary cortisol levels of morning (M) and evening (E) types of healthy, day-active adults on one morning; and (2) to compare selected demographic and sleep characteristics. The sample consisted of 20 subjects, aged 23-39 years, 10 of each type. Measures included: morningness-eveningness questionnaire score, demographic information, self-report sleep characteristics, and self-report of well-being. Beginning with time of arising, seven salivary samples were collected at approximately 20-min intervals. Among the sleep variables, bedtime (p = 0.005), time of mid-sleep (p = 0.002), and arising time (p = 0.043) were later in the E group as compared to the M group. Six M and one E subject awoke spontaneously on the morning of sampling without an awakening aid (p = 0.018). Even though total hours of sleep were comparable between groups, E subjects reported feeling less rested in the morning (p = 0.019). Although mean M group salivary cortisol levels were greater than mean E group levels for each sampling time, there were no significant group differences. Eight M subjects reached a sampling period salivary cortisol peak by 50 min after arising, contrasted with six E subjects who reached their peak at that time. These preliminary findings suggest that E types demonstrate lower morning arousal and a delay in their early-morning peak of salivary cortisol relative to M types. Further study is needed to explore the relationship between M and E types, their sleep-wake patterns, and cortisol secretion patterns.

Adult↗
PubMedDate not supplied

Modifying perfusion, nutrition, and stress to promote wound healing in patients with acute wounds.

Tissue injury is common among patients in acute care settings. The subsequent response to injury, wound healing, follows an intricate but well-defined sequence that, under normal conditions, proceeds to satisfactory repair. However, because of the complexity of the healing response, several factors can intervene to impair normal healing. As a better understanding of how diverse factors influence healing is gained, the use of interventions that modulate these factors becomes possible and potentially beneficial. This article reviews knowledge of perfusion, nutrition, and stress as they relate to healing in patients experiencing acute wounds. Therapeutic implications based on current research are discussed.

Animals↗
PubMedDate not supplied

Symptoms and self-care strategies in women with and without dysmenorrhea.

We compared the self-reports of women who reported either none-mild (N = 34) or moderate-extreme (N = 27) pain from uterine cramping regarding, (a) gastrointestinal, perimenstrual, and other symptoms during the 5 days before and after the beginning of menstrual flow; (b) smoking, alcohol use, exercise behaviors, and number of reported stressors; and (c) self-care strategies used for symptom management. Although there were significant differences between the two groups in reported symptoms, there were no significant between groups differences in smoking, alcohol use, exercise behaviors, and number of stressors reported. Despite the number of symptoms reported, relatively few self-care strategies were used. The most commonly reported strategy was the use of medication for cramping pain. The results confirm prior observations that dysmenorrhea is associated with a variety of symptoms and extend our understanding of how women manage these symptoms.

Adult↗
PubMedDate not supplied

Women with gastrointestinal symptoms: implications for nursing research and practice.

Irritable bowel syndrome and functional bowel disorder are diagnoses used to describe chronic GI symptoms for which no overt pathological condition can be identified. Symptoms are more common in women and are frequently followed in gastroenterology clinics. The purpose of this article is to provide an overview of the research linking GI symptoms and reproductive cycling and to discuss implications for practice. GIGl symptoms such as stomach pain and nausea are highest during menses compared with other cycle phases; also, stool consistency is loosest at menses. This pattern is present in control subjects. In women with irritable bowel syndrome the same pattern is seen but with higher symptom intensity. Although animal studies have demonstrated that estrogen and progesterone modulate contractile function of some GI segments. In humans, symptoms are highest when these hormones are at the lowest levels. Thus, symptoms in women may be related to decreasing ovarian hormone levels or to other circulating hormones or factors which vary with the menstrual cycle. Additionally, other factors such as stress aggravate symptoms. Therapeutics directed toward increasing patient awareness of cyclic patterns in symptom complaints, for example, via the use of daily symptom diaries may be a useful adjunct to dietary, pharmacological, and other therapies.

Clinical Nursing Research↗
PubMedDate not supplied

Gastric emptying and gastric-intestinal transit in rats with varying ovarian hormone status.

Basal and stimulated gastric emptying and gastrointestinal (GI) transit in rats of varying ovarian hormone status were compared to define direct ovarian hormone effects on GI function. Thyrotropin-releasing hormone (TRH) was used to evoke vagal GI motility stimulation. Adult female Sprague-Dawley rats were anesthetized (equithesin), ovariectomized, and implanted with 28-day estrogen (E), progesterone, (P), E+P, or vehicle (V) pellets; males were also studied. On Day 26, fasted rats were anesthetized (urethane). Nonabsorbable 14C polyethylene glycol-4000 in saline was gavaged at t = 0. At t = 5 minutes, TRH or saline was administered intracisternally. At t = 30 or 60 minutes, the GI tract was removed, ligated, sectioned, and counted. Gastric emptying was expressed as 100% minus the ratio of gastric to total counts; GI transit was expressed as geometric center of radioactivity. In saline-treated rats, gastric emptying and GI transit at 60 minutes varied significantly among ovarian hormone-treated groups, with E lower and males elevated. TRH-significantly increased both variables at both times in all groups. Results are consistent with acceleration of upper GI function in the absence of E, possibly contributing to GI symptoms during menopause and late luteal phase.

Animals↗
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↗