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Biomedical subjects

R B Lynn

Publications and source records attributed to R B Lynn.

At least 37 records · Page 2Linked to original sources
PubMed1991

Thyrotropin-releasing hormone-immunoreactive projections to the dorsal motor nucleus and the nucleus of the solitary tract of the rat.

Thyrotropin-releasing hormone-immunoreactive nerve terminals heavily innervate the dorsal motor nucleus and nucleus of the solitary tract, whereas cell bodies containing thyrotropin-releasing hormone residue most densely in the hypothalamus and raphe nuclei. By using double-labeling techniques accomplished by retrograde transport of Fluoro-Gold following microinjection into the dorsal motor nucleus/nucleus of the solitary tract combined with immunohistochemistry for thyrotropin-releasing hormone, it was demonstrated that thyrotropin-releasing hormone-immunoreactive neurons projecting to the dorsal motor nucleus/nucleus of the solitary tract reside in the nucleus raphe pallidus, nucleus raphe obscurus, and the parapyramidal region of the ventral medulla, but not in the paraventricular nucleus of the hypothalamus. The parapyramidal region includes an area along the ventral surface of the caudal medulla, lateral to the pyramidal tract and inferior olivary nucleus and ventromedial to the lateral reticular nucleus. Varying the position of the Fluoro-Gold injection site revealed a rostral to caudal topographic organization of these raphe and parapyramidal projections.

Animals↗
PubMed1991

Representation of the cecum in the lateral dorsal motor nucleus of the vagus nerve and commissural subnucleus of the nucleus tractus solitarii in rat.

Motor fibers of the accessory celiac and celiac vagal branches are derived from the lateral columns of the dorsal motor nucleus of the vagus nerve. These branches also contain sensory fibers that terminate within the nucleus of the tractus solitarii. This study traces the innervation of the intestines by using the tracer cholera toxin-horseradish peroxidase. In 53 rats, the tracer was injected into either the stomach, duodenum, jejunum, terminal ileum, cecum, or ascending colon. With all cecal injections, prominent retrograde labeling of cell bodies occurred bilaterally in the lateral columns of the dorsal motor nucleus of the vagus nerve above, at, and below the level of the area postrema. Dendrites of laterally positioned neurons projected medially and rostrocaudally within the dorsal motor nucleus of the vagus nerve and dorsomedially into both the medial subnucleus and parts of the commissural subnucleus of the nucleus of the tractus solitarii. Sensory terminal labeling occurred in the dorsolateral commissural subnucleus at the level of the rostral area postrema and the medial commissural subnucleus caudal to the area postrema. Additionally, there was sensory terminal labeling within a small confined area of the dorsomedial zone of the nucleus of the tractus solitarii immediately adjacent to the fourth ventricle at a level just anterior to the area postrema. Stomach injections labeled motoneurons of the medial column of the entire rostrocaudal extent of the dorsal motor nucleus of the vagus nerve and a sensory terminal field primarily in the subnucleus gelatinosus, with less intense labeling extending caudally into the medial and ventral commissural subnuclei. Dendrites of gastric motoneurons project rostrocaudally and mediolaterally within the dorsal motor nucleus of the vagus nerve and dorsolaterally within the nucleus of the tractus solitarii. They are most pronounced at the level of the rostral area postrema where many dendrites course dorsolaterally terminating primarily within the subnucleus gelatinosus. Injections of the duodenum labeled a small number of the cells within the medial aspects of the dorsal motor nucleus of the vagus nerve. Jejunal, ileal, and ascending colon injections labeled cells sparsely within the lateral aspects of the dorsal motor nucleus of the vagus nerve bilaterally. No afferent terminal labeling was evident after injection of these areas of the bowel.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1991

Gastric effects of thyrotropin-releasing hormone microinjected into the dorsal vagal nucleus in cats.

We investigated the gastric acid secretory and motility responses to microinjection of thyrotropin-releasing hormone (TRH) into the dorsal motor nucleus of the vagus (DMV) in anesthetized cats. Gastric acid output was collected every 15 min through a gastric cannula after saline flush and titrated to pH 7.0. Antral and corpus contractions were continuously recorded by extraluminal force transducers. TRH dissolved in 200 nl of saline and microinjected unilaterally into the DMV induced a dose-dependent (50-200 ng) increase in gastric acid secretion. The acid secretory response began in the first 15 min collection and lasted 45 min. TRH frequently increased the force of contractions of the antrum and corpus within one minute of microinjection. The minimal effective dose for eliciting increased motility was lower than for inducing acid secretion. These results demonstrate that TRH acts in the DMV of cats to stimulate gastric acid secretion and contractions.

Animals↗
PubMed1990

Gastric effects of TRH analogue and bicuculline injected into dorsal motor vagal nucleus in cats.

We investigated the gastric acid secretory and motility responses to microinjection into the dorsal motor nucleus of the vagus (DMV) of RX 77368, a stable thyrotropin-releasing hormone (TRH) analogue, and bicuculline, a gamma-aminobutyric acid (GABAA) receptor antagonist in ketamine-chloralose-anesthetized cats. Gastric acid output was collected every 15 min through a gastric cannula after saline flush and titrated to pH 7.0. Antral contractions were continuously recorded by an extraluminal strain gauge force transducer. The chemicals were dissolved in saline and unilaterally microinjected in volumes of 200 nl. RX 77368 or bicuculline microinjected into the DMV induced significant dose-dependent (50-500 ng) increases in gastric acid secretion and significant dose-dependent (50-200 ng) increases in the force of antral contractions. In response to both chemicals the gastric acid output increased in the first 15 min and peaked in the second and third collections. RX 77368 (500 ng) had a second greater peak 90 min after microinjection. The motility responses were rapid in onset and lasted 60 min for RX 77368 and 30 min for bicuculline. The minimal effective dose for eliciting increased motility was consistently lower than inducing acid secretion. Electrical stimulation of the DMV with 100 microA, 50-Hz, and 0.2-ms pulse duration increased the force of antral contractions but had no effect on gastric acid secretion. Our results demonstrate that the DMV exerts important control over both gastric acid secretion and motility in cats. TRH exerts a stimulatory influence, while GABAA receptors mediate an inhibitory influence on this vagal control.

Animals↗
PubMed1988

Cholangiocarcinoma. Role of percutaneous transhepatic cholangiography in determination of resectability.

Exploratory laparotomy is frequently used to diagnose, treat, or palliate cholangiocarcinoma although surgery is rarely curative. In light of newly developed percutaneous and endoscopic approaches to diagnosis and therapy, we reviewed our experience with 35 cases of cholangiocarcinoma diagnosed and treated at the University of Michigan Medical Center from 1979 to 1984. Percutaneous transhepatic cholangiography (PTCA) was performed in 34 cases of which only four were resectable. All 22 patients who had preoperative cholangiograms suggesting unresectability had confirmation of this at surgery. Surgical palliation was accomplished with a combination of internal and percutaneous drainage in most cases. Angiographic, cytologic, and laboratory data are presented. PTCA accurately predicted unresectability of cholangiocarcinoma and is superior to angiography in this respect. In patients with cholangiocarcinoma, percutaneous and endoscopic approaches offer alternatives to surgery for diagnosis and palliation.

Adenoma, Bile Duct↗
PubMed1987

Acute sensory neuropathy-neuronopathy from pyridoxine overdose.

We report two patients who developed an acute, profound, and permanent sensory deficit after treatment with massive doses of parenteral pyridoxine. Aside from rapid onset, their clinical picture resembles that described in chronic pyridoxine neurotoxicity. It also is consonant with experimental models of acute pyridoxine intoxication and is probably secondary to a sensory ganglion neuronopathy. These patients also had transient autonomic dysfunction, mild weakness, nystagmus, lethargy, and respiratory depression. These previously undocumented features may be attributable to either the preservative used in the parenteral pyridoxine preparation or to the exceptionally high doses of pyridoxine these patients received.

Acute Disease↗
PubMed1983

Delayed post-traumatic pneumopericardium producing acute cardiac tamponade.

Cardiac tamponade is a well-known result of fluid collection within the pericardial sac. That air in the pericardial sac can produce a similar clinical picture is not so well known. The author describes the case of a 38-year-old patient with acute cardiac tamponade produced by air within the pericardial sac after trauma.

Acute Disease↗
PubMed1983

Intrapericardial teratoma: a continuing challenge.

Intrapericardial teratoma is a rare entity that presents a diagnostic and therapeutic challenge. The authors describe the case of an 18-month-old boy with this condition who was successfully managed by resection of the mass. Computerized axial tomography, radionuclide scanning and angiography are important aids in the preoperative assessment of intrapericardial masses. However, all are nonspecific. Definitive diagnosis can only be established by thoracotomy, resection and microscopic examination of the specimen. The long-term prognosis is good.

Angiography↗
PubMed1982

Type A behavior and the thallium stress test.

Several recent studies have examined the association between Type A personality and coronary artery disease (CAD) by coronary angiography. Most of these studies have reported a significant association. The present study is an attempt at further confirmation, using a new non-invasive technique for measuring CAD. Subjects were 53 patients undergoing routine exercise stress tests with concomitant thallium-201 myocardial perfusion studies. Five aspects of Type A behavior were assessed by the use of the Rosenman-Friedman Semistructured Interview, and each was rated on a three-point scale. Severity of CAD was independently estimated on a four-point scale. Pearson correlation coefficients were separately computed for patients with and without reported history of myocardial infarction (MI). For 37 patients without reported MI, CAD severity was significantly correlated with Overall Type A (r = -0.53), Vocal Characteristics (r = -0.53), Job Involvement (r = -0.36) and Aggressiveness (r = -0.48), but not Time Urgency (r = -0.25). For 16 patients with reported MI, CAD severity was significantly correlated with Job Involvement only (r = +0.49). The data are consistent with the association of Type A personality and coronary atherogenesis, but may also reflect Type A psychological and physiological characteristics. Future studies may be able to examine these and other aspects of Type A behavior using this noninvasive technique in more diverse patient populations.

Adult↗
PubMed1982

Fate of omental graft after revascularization of the heart.

Three patients who had had epicardiectomy, and internal mammary artery and omental grafts implanted as part of myocardial revascularization, recently underwent a second operation for coronary artery bypass grafting. All internal mammary artery implants were patent and appeared to revascularize the myocardium distal to the occluded segment of the coronary artery, as determined by angiography. Although adhesions were present at operation, there was no evidence of the free omental graft in two patients. The pedicled omental graft was present and viable in the remaining patient, but did not appear to have vascular communication with the epicardiectomized myocardium.

Angina Pectoris↗
PubMed1981

A 25-year experience with the closed method of treatment in 139 patients with mitral stenosis.

A 25-year experience with 139 patients undergoing closed mitral commissurotomy is reviewed. The primary indication for closed mitral commissurotomy was mitral stenosis, but 24 patients also had other less important valvular defects. Preoperatively, all patients were in New York Heart Association (NYHA) Functional Class III or IV. Average age was 46 years (range, 18 to 77 years). There were 24 men and 115 women. No further operation after initial closed mitral commissurotomy was required in 68% of the patients (95 patients), and NYHA Functional Classification was improved in 93%. Postoperative complications occurred in 3%, and operative mortality was 2.0%. Follow-up revealed restenosis in 6% of the patients, mitral regurgitation in 14%, complications in 7%, and late deaths in 3%. Reoperation, required in 32% (44 of 139 patients), included a second closed mitral commissurotomy (21 patients), open mitral commissurotomy (3), mitral valve replacement (MVR) (18), and MVR after a second closed mitral commissurotomy (2). Improvement in NYHA classification was found in 82% of these patients. Operative mortality was 9.5% for patients having a second closed mitral commissurotomy and 20% for those having MVR.

Adolescent↗
PubMed1981

Abdominal aortic aneurysm in the elderly.

Over a 20-year period, 35 consecutive patients, 78 years of age and older, underwent resection of an abdominal aneurysm. Operation was performed electively in 8 and urgently in 10 patients with intact aneurysms and in 17 patients with ruptured aneurysms. The overall mortality was 46%. The mortality for operation on intact aneurysms was 12.5% for elective resections and 20% for emergency resections. For those with ruptured aneurysms the mortality was 76.4%. The mean survival for the 19 patients who survived operation was 48.6 months. Previous cardiac disease, rupture of the aneurysm and severe blood loss increased the mortality. Age in itself is not a deterrent to resection of an abdominal aneurysm and survival after operation, as determined by life-table analysis, compares favorably with that of the general population.

Aged↗
PubMed1980

Inhalation of foreign bodies by children: a continuing challege in management.

In a review of 19 years' experience with inhalation of foreign bodies by children the 33 patients (mean age 28 months) were found to have presented most frequently with wheezing or coughing, or both, of recent onset, and to have decreased air entry, rhonchi or respiratory stridor, or a combination of these signs. Eighteen children had inhaled a nut, a pea or a bean. The other 15 had inhaled various organic and inorganic objects. All the children underwent bronchoscopy, and the foreign body was completely removed in 19 during the first procedure; the remainder required repeated bronchoscopy or direct surgical removal of the foreign body, or both. Permanent disability or death was not encountered. The findingsof the study indicate that early bronchoscopic removal is the preferred treatment when a child inhales a foreign body.

Bronchi↗
PubMed1980

Agenesis of the corpus callosum.

A father and son with agenesis of the corpus callosum are described. An 11-year-old boy underwent clinical examination because of poor school performance. On physical and mental examinations he was normal, except for an enlarged head. Computerized tomographic (CT) scan showed agenesis of the corpus callosum. The patient's father also had an enlarged head. Although he had never had any symptoms, he underwent CT scanning, which revealed agenesis of the corpus callosum. Psychological tests showed good communication between the two cerebral hemispheres. All-night sleep EEGs showed asynchronous sleep spindles.

Adult↗
PubMed1980

Kommerell's diverticulum.

Kommerell's diverticulum of an aberrant right subclavian artery is a rare embryologic anomaly. It should always be considered when a patient presents with a central mediastinal tumour. In spite of sophisticated newer investigations, aortography remains the diagnostic procedure of choice. Ligation in continuity is a safe and simple method of management.

Aortography↗
PubMed1979

Knitted Dacron ultra-lightweight grafts--a warning.

A 61-year-old man presented with gross femoral and abdominal pulsation secondary to severe ectasia of an ultra-lightweight Dacron graft. All patients who have received this particular graft should be followed up closely and probably the graft should be replaced if progressive enlargement occurs.

Aorta, Abdominal↗
PubMed1979

Cerebral surveillance during cardiac surgery.

There is at present no ideal method for determining the adequacy of cerebral blood flow during nonpulsatile cardiopulmonary bypass procedures. Clinical evaluation of cerebral function while the patient is under general anesthesia may be misleading and unsuspected cerebral damage could result if perfusion of the cerebrovascular bed is inadequate. Electroencephalography appears to be the only reliable noninvasive means of cerebral surveillance during the critical periods of nonpulsatile perfusion.

Cardiac Surgical Procedures↗