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Biomedical subjects

W L Hasler

Publications and source records attributed to W L Hasler.

At least 37 records · Page 2Linked to original sources
PubMed1999

Motility of the small intestine.

Motility of the small intestine is controlled by myogenic, neural, and hormonal mechanisms and is modulated by external influences such as meals, central nervous system activation, and immune factors. Small-bowel dysmotility is recognized in a number of diseases, but its precise role in symptom generation remains unclear in many instances. We review publications that in the year under review added to the basic understanding of small-intestinal motility as well as its alteration in disease.

Journal Article↗
PubMed1999

Protein meals reduce nausea and gastric slow wave dysrhythmic activity in first trimester pregnancy.

First trimester nausea is associated with gastric slow wave dysrhythmias (tachygastria, bradygastria). We tested the roles of meal composition and caloric content on nausea and slow wave rhythm in 14 nauseated pregnant women. Electrogastrography quantified dysrhythmic activity and signal power responses to meals. Symptomatic women reported mild to moderate nausea and exhibited increased dysrhythmias during fasting (P < 0.05). Protein-predominant meals reduced nausea and dysrhythmic activity to greater degrees than equicaloric carbohydrate and fat meals and noncaloric meals (P < 0.05). Meal consistency did not affect symptom responses, although liquid meals decreased dysrhythmias more than solids (P < 0.05). Carbohydrates and fats increased electrogastrographic power to similar degrees as proteins, whereas responses to noncaloric meals were less. In conclusion, protein meals selectively reduce nausea and gastric slow wave dysrhythmias in first trimester pregnancy. Meal consistency is a limited factor in the favorable effects of protein. Electrogastrographic power changes do not explain the symptom response to protein. Thus dietary modulation of gastric myoelectric rhythm with protein supplementation may provide symptomatic benefit in nausea of pregnancy.

Adult↗
PubMed1999

Novel approaches to the treatment of nausea and vomiting.

Nausea and vomiting are debilitating symptoms complicating many clinical conditions. Conventional antiemetic agents act as muscarinic, histamine, and dopamine receptor antagonists in the central nervous system. In a retrospective analysis, tricyclic antidepressant drugs demonstrated efficacy in long-term treatment of functional nausea. Some cases of vomiting result from impaired gastrointestinal motor activity. Agents which act on gastric serotonin (5-HT4), dopamine, and motilin receptors accelerate gastric emptying and relieve symptoms in gastroparesis. Recent investigations suggest that some patients with refractory gastroparesis may benefit from gastric electrical pacing. The treatment of acute chemotherapy-induced emesis was revolutionized by 5-HT3 receptor antagonists; however, these agents are less efficacious in delayed vomiting. Neurokinin (NK-1) receptor antagonists show promise in treating delayed chemotherapy-evoked emesis. Furthermore, animal studies indicate a broad spectrum of action for NK-1 antagonists in treating diverse causes of nausea and vomiting. The cyclic vomiting syndrome is characterized by discrete episodes of relentless vomiting separated by asymptomatic intervals and is associated with migraine headaches. Antimigraine therapies including the 5-HT1D receptor agonists sumatriptan reduce the severity of cyclic vomiting attacks. Investigations into these and other novel treatments may provide important advances in the care of difficult cases of nausea and vomiting resulting from disparate illnesses.

Antidepressive Agents↗
PubMed1999

Serotonin receptor physiology: relation to emesis.

Several serotonin (5-HT) receptor subtypes have been defined by pharmacological responses to selective agonists and antagonists and by pathways of receptor-effector coupling. Using molecular techniques, additional receptor subtypes have been described. 5-HT receptors are prevalent in the central nervous system and gut and participate in induction of emesis. 5-HT3 antagonists are used to prevent emesis from cancer chemotherapy and also demonstrate efficacy in radiation-induced nausea, postoperative nausea, hyperemesis gravidarum, and nausea and vomiting with the acquired immunodeficiency syndrome. 5-HT4 agonists exhibit prokinetic properties in nauseated patients with gastroparesis and functional dyspepsia. Conversely, 5-HT4 antagonists have antiemetic activity in some experimental models. The 5-HT1D receptor agonist sumatriptan reduces emesis with migraine headaches and in cyclic vomiting syndrome, most likely via action on central nervous system sites. In other models, 5-HT1A and 5-HT2A/5-HT2C agonists exhibit antiemetic properties. The utility of 5-HT receptor ligands in treating emesis is the subject of active investigation.

Adolescent↗
PubMed1998

Measurement of gastrointestinal motility in the GI laboratory.

Current tests of gastric and small intestinal motor function provide relevant physiological information, but their clinical utility is controversial. This article reviews the current procedures, indications, significance, pitfalls, and guidelines for gastrointestinal motility measurements by scintigraphy, gastroduodenojejunal manometry, and surface electrogastrography in humans. Methods included review of literature and discussions in closed and open fora among investigators, including presentations for peer review at focused (Iowa City American Motility Society Symposium, December 1995) and national meetings (American Gastroenterological Association, May 1996, and American Motility Society, September 1996). The current tests are generally complementary; scintigraphy is typically the first test in the evaluation of gastric motor function and often confirms the clinical suspicion of dysmotility. Manometry identifies patterns suggestive of myopathy, neuropathy, or obstruction but may be most helpful when it shows entirely normal findings, because manometry helps in part to exclude dysmotility as a cause of symptoms. Electrogastrography may identify dysrhythmias or failure of signal power to increase postprandially; rhythm abnormalities may be independent of impaired emptying among dyspeptic patients. The best validated and clinically most significant results pertain to transit tests; manometry may contribute importantly to the diagnostic process; and the significance of electrogastrography remains to be fully elucidated.

Digestive System↗
PubMed1998

Low- versus high-dose azithromycin triple therapy for Helicobacter pylori infection.

BACKGROUND: We report a clinical trial which evaluated the effectiveness of triple therapy containing low- and high-dose azithromycin to treat Helicobacter pylori infection. METHODS: From March 1997 to March 1998, patients infected with H. pylori were assigned to receive either: Treatment 1: ranitidine bismuth citrate (RBC) (400 mg b.d.) and amoxycillin (1 g b.d.) for 10 days with azithromycin 500 mg o.m. for 3 days: or Treatment 2: RBC and amoxycillin for 10 days with azithromycin 1 g o.m. for 3 days. H. pylori eradication was established by a urea breath test at least 4 weeks after therapy. Side-effects and compliance were assessed using a diary. RESULTS: Sixty-eight patients were enrolled. Fifty-seven per cent of patients were treated for active peptic ulcer disease or a history of peptic ulcer disease. Treatment 1 cured H. pylori in 44% and 44% by per protocol and intention-to-treat analysis, respectively. The corresponding eradication rates for Treatment 2 were 79% and 75%. Two patients taking Treatment 2 dropped out of the study because of side-effects. CONCLUSIONS: With RBC and amoxycillin for 10 days, azithromycin at a dose of 1 g/day for 3 days was significantly better at curing H. pylori infection than azithromycin 500 mg/day for 3 days.

Adult↗
PubMed1998

Differential symptomatic and electrogastrographic effects of distal and proximal human gastric distension.

Nausea and gastric dysrhythmias occur in conditions associated with gastric distension. The roles of distal and proximal gastric mechanoreceptors in these responses are unexplored. Because antral distension induces vomiting in animals and antral and fundic vagal afferent discharges differ, we hypothesized that distal gastric distension in humans leads to greater symptomatic and dysrhythmic responses than proximal distension. Symptoms and electrogastrograms were recorded in healthy humans during distal and proximal gastric distension with a barostat. Distal but not proximal distension induced nausea and a 747 +/- 250% increase in dysrhythmic power (P < 0.05), responses not affected by granisetron, indomethacin, or atropine, agents that block dysrhythmias in other settings. In the distal stomach, bloating and pain developed at lower pressures (P < 0.05) not modified by granisetron, and compliance was significantly lower (P < 0.05). In conclusion, gastric mechanoreceptor activation in the less-compliant distal stomach produces nausea and dysrhythmias via non-5-hydroxytryptamine3 (5-HT3), non-prostaglandin-dependent, and noncholinergic pathways. Distal mechanoreceptor activation induces greater bloating and pain than proximal mechanoreceptor activation via 5-HT3-independent pathways.

Adult↗
PubMed1998

Differential effects of amitriptyline on perception of somatic and visceral stimulation in healthy humans.

Tricyclic antidepressants treat chronic pain both in patients with somatic illness and with functional bowel disorders. We compared the effects of amitriptyline on perception of cutaneous and gastrointestinal stimulation to assess differential analgesic effects of tricyclics on somatic and visceral pain. Cutaneous electrical stimulation and rectal and esophageal distension were performed before and after 21 days of double-blind 50 mg amitriptyline vs. placebo in healthy volunteers. Amitriptyline increased currents that elicited cutaneous threshold, moderate discomfort, and moderate pain compared with basal (P < 0.05), whereas placebo had no effect. Amitriptyline had no effect on perception of rectal and esophageal distension and did not alter luminal compliance; thus the lack of effect on perception is not due to altered visceral elastic wall properties. In conclusion, amitriptyline reduces perception of cutaneous stimulation but does not alter visceral perception or compliance. This investigation demonstrates differential effects of tricyclics on somatic and visceral afferent function in healthy humans and provides insight into mechanisms of action in chronic pain both from somatic disease and from functional bowel disorders.

Adult↗
PubMed1998

Differential 5-HT3 mediation of human gastrocolonic response and colonic peristaltic reflex.

Colonic motor function is modulated by extended and local neural reflexes involving unknown mediators. To test the role of serotonin (5-HT3) pathways, increases in colonic tone during antral distension and duodenal lipid perfusion (gastrocolonic responses) and changes in orad and caudad colonic tone in response to local colonic distension (peristaltic reflex) were measured after double-blind granisetron (10 microg/kg) or placebo infusion in healthy human volunteers. Antral distension evoked increases in colonic tone, which were blunted by granisetron (P < 0.05) without effects on antral compliance. Intraduodenal lipid perfusion also evoked increased colonic tone, which was reduced by granisetron (P < 0.05). In contrast, orad colonic contractions and caudad relaxations and contractions during colonic distension were unaffected by granisetron. In conclusion, 5-HT3 receptor antagonism blunts both the mechano- and chemoreceptor components of the human gastrocolonic response without altering antral compliance. In contrast, 5-HT3 pathways play no role in the ascending or descending components of the colonic peristaltic reflex. These findings demonstrate different roles for 5-HT3 receptors in the control of colonic motor function by the proximal gastrointestinal tract and by local neural reflexes.

Adult↗
PubMed1997

Role of plasma vasopressin as a mediator of nausea and gastric slow wave dysrhythmias in motion sickness.

The possible role of vasopressin in nausea and gastric dysrhythmias in motion sickness was tested by electrogastrography in 14 subjects during circular vection (60 degrees/s) and vasopressin infusion. Tachygastria was expressed as the signal percent >4.5 cycles/min. Vection evoked nausea scores of 2.6 +/- 0.2 (0 = none to 3 = severe) in 10 subjects with increases in tachygastric activity (15 +/- 2 to 45 +/- 3%) and plasma vasopressin (4.5 +/- 1.5 to 8.4 +/- 2.5 pg/ml) that were blocked by atropine but not indomethacin. Four asymptomatic subjects had no tachygastria or vasopressin release. Vasopressin at 0.2 U/min (plasma level = 322.1 +/- 10.3 pg/ml) evoked nausea (2.6 +/- 0.4) and increases in tachyarrhythmic activity (41 +/- 5%) that were blunted by atropine but not indomethacin. There were no differences in nausea or dysrhythmias with vasopressin infusion in subjects who noted nausea during vection versus those who did not. To conclude, vection evokes nausea, dysrhythmias, and vasopressin release in motion sickness-susceptible humans via cholinergic prostaglandin-independent pathways. Supraphysiological vasopressin infusions evoke nausea and dysrhythmias by similar pathways to equal degrees in motion sickness-susceptible and -resistant subjects. Thus central but not peripheral actions of vasopressin may contribute to nausea and slow wave disruption with vection. Blunting of both the release and action of vasopressin by atropine may explain its beneficial action in motion sickness.

Adult↗
PubMed1997

Bismuth subsalicylate instead of metronidazole with lansoprazole and clarithromycin for Helicobacter pylori infection: a randomized trial.

OBJECTIVE: We evaluated the efficacy of lansoprazole, clarithromycin, and metronidazole (LCM) administered twice daily for 7 days. Because there is growing concern about the development of metronidazole-resistant H. pylori (HP) strains, we also tested a novel regimen consisting of lansoprazole, clarithromycin, and bismuth subsalicylate (LCB). METHODS: Patients with active HP infection and peptic ulcer, a history of peptic ulcer, or nonulcer dyspepsia were randomized to either lansoprazole 30 mg b.i.d., clarithromycin 500 mg b.i.d., and metronidazole 500 mg b.i.d. or lansoprazole 30 mg b.i.d., clarithromycin 500 mg b.i.d., and bismuth subsalicylate 524 mg b.i.d. (LCB) for 7 days. Compliance and side effects were recorded by using a diary. RESULTS: "Per protocol" eradication with LCM was achieved in 41 of 47 (87%). By using "intention to treat" analysis, LCM eradicated HP infection in 43 of 53 patients (81%). By using "per protocol" analysis, LCB eradicated HP infection in 40 of 47 patients (85%). On an "intention to treat" basis, LCB led to HP eradication in 42 of 52 (81%). The most common significant side effects observed with LCM were altered taste (39%) and abdominal pain (19%). With LCB, the most common significant side effects were altered taste (23%) and dark stools (23%). CONCLUSIONS: LCB for 7 days was as effective in eradicating HP infection as a 7-day course of LCM. Further studies evaluating the role of bismuth compounds in proton-pump inhibitor based triple therapy are warranted. Such therapy may have particular importance in areas where high metronidazole resistance is a concern.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1996

Nicotine effects on prostaglandin-dependent gastric slow wave rhythmicity and antral motility in nonsmokers and smokers.

BACKGROUND & AIMS: Mechanisms of antral hypomotility with smoking are unknown. Slow wave disruption, which may be prostaglandin dependent, inhibits gastric motility. This study tested if nicotine reproduces motor effects of smoking and assessed the role of slow wave disruption in inducing hypomotility and the prostaglandin dependence of dysrhythmic responses. METHODS: Electrogastrography and antroduodenal manometry were performed in 9 nonsmokers and 9 smokers during transdermal nicotine treatment (14 mg). Studies were repeated after administration of 150 mg indomethacin daily for 3 days to test prostaglandin requirements of nicotine responses. RESULTS: Antral migrating motor complex periodicity and fasting and fed motility indices, not different in the groups under control conditions, decreased similarly in nonsmokers and smokers with nicotine. Tachygastria (> 4.5 cycle/min) increased from 2% +/- 2% to 16% +/- 3% of recording time, and arrhythmias (frequency instability index) increased from 0.5 +/- 0.1 to 1.1 +/- 0.2 cycle/min with nicotine in nonsmokers (P < 0.05), which normalized with indomethacin. Electrogastrography results were unchanged in smokers. CONCLUSIONS: Nicotine evokes antral hypomotility in nonsmokers and smokers but evokes prostaglandin-dependent gastric dysrhythmias only in nonsmokers. Smokes show desensitization to nicotine-stimulated dysrhythmias. Thus, slow wave disruption is not essential to inhibit motor activity. This provides a model for the motor and myoelectric effects of smoking.

Adolescent↗
PubMed1996

Progesterone and estrogen are potential mediators of gastric slow-wave dysrhythmias in nausea of pregnancy.

Women in pregnancy experience nausea, which correlates with gastric slow-wave rhythm disruption. Mediators of these dysrhythmias were explored. To quantitate slow-wave disruption, eight pregnant women with first-trimester nausea underwent electrogastrography after a 250-kcal meal. Results were compared with nonpregnant women with nausea during a prior pregnancy who received estradiol and/or progesterone to levels of the first trimester of pregnancy. Five pregnant women exhibited dysrhythmias, with increases in combined recording time in tachygastria plus bradygastria, as well as decreases in the percentage of electrogastrography signal power in the normal 3 cycle/min range (cpm), compared with nonpregnant women (P<0.05). Estradiol did not evoke dysrhythmias in nonpregnant women; however, progesterone induced increases in recording time in bradygastria plus tachygastria and increases in bradygastric signal power with corresponding decreases in signal power in the 3-cpm range (P<0.05). With estradiol and progesterone coadministration, an additive effect was observed at 3.3 +/- 0.8 h, with increased recording time in bradygastria alone and in bradygastria plus tachygastria with corresponding increases in bradygastric signal power and decreases in power in the 3-cpm range (P<0.05). In conclusion, women with nausea of pregnancy exhibit slow-wave rhythm disruption. Similar dysrhythmias are evoked in nonpregnant women by progesterone alone or in combination with estradiol in doses that reproduce levels in pregnancy. Thus gastric dysrhythmias in pregnancy may be due to a combination of elevated progesterone and estrogen levels.

Adult↗
PubMed1996

Mechanisms by which octreotide ameliorates symptoms in the dumping syndrome.

Octreotide reduces abdominal and vasomotor symptoms in dumping syndrome by unknown mechanisms. Effects of octreotide (50 microgram) on symptoms, hemodynamic parameters and plasma glucose and insulin levels after glucose meals were tested in double-blind, placebo-controlled, crossover fashion in eight patients with dumping syndrome. Gastric scintigraphy tested whether octreotide reduces symptoms by slowing gastric emptying. Octreotide reduced diarrhea, lightheadedness and palpitations after 75 g of glucose, compared with placebo (P < .001). Orthostatic pulse increases after glucose decreased from 36 +/- 6 beats/min after placebo to 9 +/- 5 beats/min after octreotide (P < .05), and standing blood pressure decreases after glucose were abolished (P < .05), but octreotide had no effect on increase in hematocrit or plasma osmolarity after glucose. Late hypoglycemia was prevented by octreotide, and peak fed insulin levels were reduced from 87 +/- 15 to 26 +/- 9 microU/ml after octreotide (P < .05). Times to maximal plasma glucose levels after meals were prolonged from 28 +/- 4 to 78 +/- 6 min after octreotide (P < .05). Octreotide had no effect on gastric emptying of liquids or solids. In conclusion, amelioration of dumping symptoms by octreotide is associated with reduced orthostasis, which is not a consequence of prevention of hemoconcentration. Prevention of late hypoglycemia may be due to blunted insulin release. Octreotide does not reverse rapid gastric emptying, indicating a limited role for this purported mechanism of action.

Adult↗