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Biomedical subjects

R L Stephens

Publications and source records attributed to R L Stephens.

At least 19 recordsLinked to original sources

Thyrotropin-releasing hormone analogue and serotonin interact within the dorsal vagal complex to augment gastric acid secretion.

The effects of serotonin (5HT) and a thyrotropin-releasing hormone (TRH) analogue, RX77368, on vagal control of gastric acid secretion were studied. Microinjection of RX77368 (0.66 pmol in 10 nl), but not 5HT (8 pmol in 10 nl), into the dorsal vagal complex (DVC) evoked a significant increase in acid output. When the same doses of RX77368 and 5HT were co-injected, the amount of acid secreted was significantly greater than that due to RX77368 alone. Thus, 5HT and the TRH analogue interact within the DVC to enhance vagal stimulation of acid secretion. The study suggests a possible functional significance of raphe TRH/serotonergic tracts projecting to the DVC.

Animals

Fluoxetine pretreatment potentiates intracisternal TRH analogue-stimulated gastric acid secretion in rats.

Central injection of TRH or its metabolically stable analogue RX 77368 has been demonstrated to produce a vagal-dependent stimulation in gastric acid secretion. Accumulating evidence exists regarding the interaction of serotonin (5HT) with TRH containing neuronal systems. This study was performed to assess the effect of pretreatment with the 5HT uptake inhibitor fluoxetine on the TRH analogue-induced gastric acid secretory response. Systemic fluoxetine (30 mumol/kg, i.v.) produced a 43-85% increase in the intracisternal RX 77368 (78-780 pmol)-induced gastric acid output, while not affecting the basal acid response. The acid response to a lower dose of RX 77368 (26 pmol) was not altered. In addition, intracisternal fluoxetine (180 nmol) produced a 71% augmentation of the acid secretory response of i.c. RX 77368 (260 pmol). Intracisternal injection of lower doses (60, 120 nmol), or intravenous injection of 180 nmol of fluoxetine was ineffective in altering the intracisternal RX 77368-induced acid response. Pretreatment with the noradrenergic or dopaminergic uptake inhibitor desipramine or GBR 12909 did not alter the RX 77368-stimulated gastric acid secretory response. The results show that fluoxetine pretreatment potentiates the effect of intracisternal RX 77368 on acid secretion. The effect appears to be impulse dependent, and central sites of action are involved. The data suggest an interaction of synaptic serotonin with a RX 77368-elicited event (activation of TRH receptors, second messenger systems and/or firing of the motor vagus) results in potentiation of the RX 77368-induced gastric response.

Animals

Phase II evaluation of didemnin B in advanced adenocarcinoma of the kidney. A Southwest Oncology Group study.

The Southwest Oncology Group studied the response rate and toxicity of didemnin B (3.47 mg/m2 i.v. q 28 days) in patients with advanced renal cell carcinoma. There were no responses in 22 response evaluable patients. Toxicity was significant with 10 patients having grade 3 or 4 toxicity. Toxicity seen included nausea and vomiting, exacerbation of coronary artery disease, hyperglycemia, anorexia, diarrhea and hepatitis. Didemnin B was toxic but inactive in patients with renal cell treated at this dose.

Adenocarcinoma

Treatment of stages B3 and C seminoma with chemotherapy followed by irradiation therapy. Southwest Oncology Group Study.

Beginning in 1981, 28 patients with advanced seminoma were treated with combination chemotherapy followed by irradiation to evaluate the possibility of improved survival using both modalities. The treatment protocol consisted of two courses of vincristine, actinomycin-D, and cyclophosphamide followed by reassessment. Those initially presenting with Stage B3 disease who achieved a complete response to two cycles of chemotherapy then underwent irradiation. All others were given a third course of chemotherapy before undergoing irradiation. The pre-radiation portion of this protocol produced a complete response rate of only 25 percent, substantially less than other, more recent, protocols. Radiation therapy produced a complete response in 69 percent of those who did not achieve a complete response from chemotherapy, increasing the complete response rate from 25 percent to 64 percent. Given this response rate to radiation therapy and the difficulty of dissection and associated morbidity with the surgical excision of postchemotherapy residual masses, the best option at this time may be observation with salvage chemotherapy and/or radiation reserved for those with disease progression.

Antineoplastic Combined Chemotherapy Protocols

Antiulcer activity of the calcium antagonist propyl-methylenedioxyindene--V. Localization of site of action.

1. Propyl-methylenedioxyindene (pr-MDI) is an intracellular calcium antagonist which inhibits cold-restraint stress ulceration at subcardiovascular doses (less than or equal to 30 mg/kg). It also inhibits gastric acid secretion evoked by RX77368 (a stable analog of thyrotropin-releasing hormone, the putative mediator of cold-restraint stress ulcers). 2. The objective of this investigation was to localize the site of the inhibitory effect of pr-MDI on gastric acid secretion stimulated by intracisternal (i.c.) administration of RX77368 (100 ng) in rats. 3. Peripheral administration of pr-MDI (30 mg/kg i.p. or i.v.) inhibited the elevated basal and the RX 77368-induced acid secretion in conscious 2-hr pylorus-ligated rats. This effect was completely blocked in anesthetized (urethane or pentobarbital) acute gastric fistula rats. 4. Intracisternal administration of pr-MDI (0.1-1 mumol) produced a dose-related inhibition of acid secretion in conscious pylorus-ligated rats. However, urethane anesthesia completely blocked the inhibitory effect of i.c.-administered pr-MDI (1 mumol) on RX77368-induced acid secretion. 5. Since previous studies indicate that anesthesia does not inhibit peripheral actions of pr-MDI (e.g. the antiarrhythmic effect), the convergent evidence suggests that the inhibitory effect of pr-MDI on gastric acid secretion is mediated primarily via the central nervous system.

Animals

Case report: breast cancer in males--a genetic consideration.

For many years, it has been recognized that a portion of female breast cancer is inherited. More recently, the probable contribution of heredity to at least a subset of male breast cancer also has surfaced. This report, which describes affected brothers, a half sister, and the common paternal grandmother, provides further support for the role of genetic factors in male breast cancer. Also noteworthy was the presence of prostate carcinoma in the sibling with bilateral disease and in the unaffected father.

Adult

TRH analogue microinjected into specific medullary nuclei stimulates gastric serotonin secretion in rats.

Brain nuclei involved in vagal release of gastric serotonin (5-HT) were investigated in urethan-anesthetized rats acutely implanted with gastric cannula. Gastric secretions were collected every 10-15 min for 2 h, and measurement of serotonin 5-HT was performed by high-performance liquid chromatography (HPLC) with electrochemical detection and that of acid by titration. The stable thyrotropin-releasing hormone (TRH) analogue, RX 77368, microinjected into the dorsal vagal complex (DVC) (1.5-77 pmol/50 nl) induced a dose-related and long-lasting increase in gastric 5-HT and acid output. TRH (276 pmol) microinjected into the DVC also stimulated gastric 5-HT secretion. TRH action was abolished by vagotomy. RX 77368 (77 pmol) increased 5-HT release after microinjection into the raphe obscurus, raphe pallidus, and nucleus ambiguus, although the responses were significantly lower compared with that induced by DVC microinjection. No changes in gastric 5-HT release were observed when the peptide was microinjected into the lateral hypothalamus, hypoglossal, paramedian reticular, inferior olive, lateral paragigantocellular or spinal trigeminal nucleus. The potent gastric 5-HT release induced by TRH or TRH analogue into the DVC added to the presence of TRH receptors and TRH-LI nerve terminals in the DVC suggest a role of medullary TRH in the vagal regulation of gastric 5-HT release.

Animals

Imagery: a treatment for nursing student anxiety.

This study examined the effectiveness of audiotaped imagery in reducing anxiety and improving test performance among first-year nursing students. Volunteer subjects were randomly assigned to three groups, imagery-only, imagery/relaxation, and a no-treatment control group. Pottest state anxiety scores in these groups were significantly lower (p = .001) than in the no-treatment control group. Test performance did not differ significantly (p = .067). Subjects using the audiotaped imagery reported an increased sense of well-being, improved ability to sleep, greater energy, and improved self-confidence.

Adolescent

Effects of 2 mg and 4 mg atropine sulfate on the performance of U.S. Army helicopter pilots.

Atropine autoinjectors are issued to aviators for use in the event of organophosphate poisoning on the battlefield. This investigation assessed the effects of unchallenged 2 mg and 4 mg doses on flight performance, vision, tracking, cognitive performance, and electroencephalograms of 12 Army aviators. Effects were seen most often with the 4 mg dose in terms of aircraft control problems, vision disturbances, impaired tracking, reduced cortical activation, and decreased cognitive skill. These problems indicate helicopter tactical flight is dangerous after an unchallenged 4 mg dose. Other types of flight should also be avoided for at least 12 h after atropine.

Adult

Oncology patients and the living will.

The Patient Self-Determination Act now requires hospitals, nursing homes, and health maintenance organizations to ask patients if they have executed and are in possession of a living will. This article provides a brief historical perspective of what living wills are, how patient autonomy has contributed to their existence, and what distinguishes a living will from a durable power of attorney for health care. Included are working examples of these advance directives and a description of the University of Kansas Cancer Unit's positive experience with living wills. The final section discusses the meaning of certain pivotal terms, looks at the current under-utilization of living wills, and closes with an examination of the Blackhall thesis of futility.

Attitude to Death

Disparate effects of intracisternal RX 77368 and ODT8-SS on gastric acid and serotonin release: role of adrenal catecholamines.

Intracisternal injection of the thyrotropin releasing hormone (TRH) analogue RX 77368 (100 ng) or the somatostatin analogue ODT8-SS (1 microgram) produced an 82% and 101% increase in gastric acid secretion in 2 h pylorus-ligated rats. In contrast, dissimilar effects were produced by intracisternal injection of these peptides on the secretion of serotonin into the gastric lumen. Intracisternal RX 77368 (100 ng) produced a 496% increase in intraluminal serotonin release, while in contrast, intracisternal ODT8-SS (1 microgram) produced a 78% inhibition in intraluminal serotonin release. Bilateral adrenalectomy reversed the stimulatory effect of intracisternal RX 77368 (100 ng) on serotonin, but not acid release. The data reveal a difference in the ability of the two peptides, which act as gastric secretagogues, to produce intraluminal acid and serotonin release, and suggest that combined activation of the vagus and the adrenal gland are important in mediating basal and RX 77368-stimulated serotonin release into the gastric lumen. In particular, differential effects on adrenal catecholamine release are implicated in the divergent effects of the two peptides.

Adrenal Glands

Randomized trial of doxorubicin, bisantrene, and mitoxantrone in advanced breast cancer: a Southwest Oncology Group study.

Four hundred eleven women with metastatic breast cancer were randomly assigned to receive either 60 mg/m2 doxorubicin (130 patients), 320 mg/m2 bisantrene (146 patients), or 14 mg/m2 mitoxantrone (135 patients). The doses were given intravenously every 3 weeks with a cross-over design to determine their relative efficacy and toxicity. To be eligible, patients must have had one previous chemotherapy regimen, and patients who were estrogen receptor positive must have failed endocrine therapy. There were 365 patients assessable for response and 399 assessable for toxic effects. The median age was 57 years; 18% were premenopausal or perimenopausal. Visceral dominant disease was present in 66% of the patients. Ninety-seven percent of the patients had a disease-free interval from diagnosis to first recurrence of less than 1 year. The response rate was 28% with doxorubicin, 13% with bisantrene, and 14% with mitoxantrone (P = .004). Median time to treatment failure was 133 days with doxorubicin, 66 days with bisantrene, and 68 days with mitoxantrone (logrank P = .06). The median survival was 315 days for doxorubicin, 290 days for bisantrene, and 177 days for mitoxantrone (logrank P = .04), although survival at 2 years was similar for all three agents. There were five responses in the 66 patients crossed over to doxorubicin and one response each for patients crossed over to bisantrene (39 patients) or mitoxantrone (63 patients). Toxicity leading to discontinuance of therapy was more common with doxorubicin, and discontinuance of therapy was due primarily to patient's request or cardiotoxicity. The major dose-limiting toxic effect for all three agents was leukopenia. Nausea and vomiting, mucositis, and alopecia were more severe with doxorubicin. Congestive heart failure developed in nine patients treated with doxorubicin, zero patients treated with bisantrene, and two patients treated with mitoxantrone. A decrease in the left ventricular ejection fraction, as defined by moderate to severe Alexander grade changes, was more common in patients treated with doxorubicin (doxorubicin-treated patients = 20%, bisantrene-treated patients = 5%, and mitoxantrone-treated patients = 10%). This study demonstrates that bisantrene and mitoxantrone have only modest activity in metastatic breast carcinoma. The activity of doxorubicin is greater than that of the other two agents, but at a cost of increased toxicity.

Adenocarcinoma

Treatment of non-small-cell lung cancer with vinblastine and very high-dose cisplatin. A Southwest Oncology Group study.

Suggestions of a dose-response effect for cisplatin in non-small-cell lung cancer have contributed to the development of very high-dose cisplatin regimens (200 mg/m2 per cycle). We treated 53 eligible patients with metastatic or recurrent non-small-cell lung cancer with a combination of 100 mg/m2 cisplatin and 4 mg/m2 vinblastine, each given on days 1 and 8 of a 28-day cycle. We observed no complete response and 4 partial responses (8%). Median survival was 6 months. Toxicities of grade III or greater included leukopenia (11 cases), nausea/vomiting (6 cases), thrombocytopenia (2 cases), anemia (2 cases), and elevation of transaminase (1 case). Neurotoxicity has been reported to be a major problem in several other very high-dose cisplatin regimens. The low level of neurotoxicity observed in this study may be attributable to the median cumulative cisplatin dose of less than 600 mg/m2. This vinblastine/very high-dose cisplatin regimen showed minor activity against non-small-cell lung cancer. The level of activity did not surpass that of standard-dose (100 mg/m2 per cycle) cisplatin-containing regimens.

Antineoplastic Combined Chemotherapy Protocols

Synthesis and antibacterial activities of C-21 functionalized derivatives of (9R)-9-amino-9-deoxoerythromycins A and B.

Selective protection of (9R)-9-amino-9-deoxoerythromycin A allowed for elimination of the 12-hydroxyl group to afford a versatile 12,21-olefin intermediate. Further modifications of the intermediate led to the syntheses of (9R)-9-deoxo-9-(N,N-dimethylamino)-12,21-epoxyerythromycin B, (9R)-9-deoxo-9-(N,N-dimethylamino)-21-hydroxyerythromycin A, and (9R)-9-deoxo-9-(N,N-dimethylamino)-21-hydroxyerythromycin B. All three compounds retained antibacterial activity against several organisms normally susceptible to (9R)-9-deoxo-9-(N,N-dimethylamino)erythromycin A. However, the 21-hydroxylated erythromycin A analogue was weaker in potency than the corresponding erythromycin B congener and much weaker than the epoxy derivative. This suggests that while substitution of a polar functionality at C-21 does not abolish antibacterial activity, introduction of vicinal polar groups at both C-12 and C-21 may lead to reduction in potency. Nevertheless, these 21-functionalized derivatives of (9R)-erythromycylamine provide an entry into novel analogues of the important macrolide antibiotic erythromycin.

Bacteria

Phase II study of fludarabine phosphate (NSC-312887) in patients with advanced endometrial cancer. A Southwest Oncology Group Study.

Nineteen evaluable patients with advanced endometrial cancer refractory to one prior chemotherapeutic regimen were treated with a 5-day schedule of fludarabine phosphate. No responses were noted. The major toxicity was grade 2 or greater leukopenia in 45% of patients. Fludarabine phosphate at this dose and schedule does not appear to be an active agent for patients with refractory endometrial cancer.

Aged