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Biomedical subjects

G M Graeber

Publications and source records attributed to G M Graeber.

At least 73 records · Page 4Linked to original sources
PubMed1987

Intrathecal dynorphin A1-13 and dynorphin A3-13 reduce rat spinal cord blood flow by non-opioid mechanisms.

Radiolabeled microspheres were used to examine the effects of paralytic intrathecal doses of dynorphin A (Dyn A1-13) and Dyn A3-13 on rat brain and spinal cord blood flows and cardiac output. Dyn A1-13 produced significant dose-related reductions in blood flow to lumbosacral and thoracic spinal cord without altering cardiac output and blood flow to brain and cervical spinal cord. Naloxone failed to block these effects. Dyn A3-13, which lacks opioid activity, also significantly reduced blood flow in lumbosacral spinal cord. Thus, the paralytic effects of Dyn A in the rat may involve reductions in spinal cord resulting from non-opioid actions of Dyn A.

Animals↗
PubMed1987

Bayesian diagnostic theory using a programmable pocket calculator.

A programmable pocket calculator program has been written to serve as an aid in diagnosis. The program uses a Bayesian statistical algorithm to calculate the relative probability of two diagnostic alternatives. The ability to carry out Bayesian statistical calculations at the bedside should make the use of such techniques more attractive to clinical practitioners.

Algorithms↗
PubMed1987

Prevention of ventricular fibrillation after myocardial revascularization.

Ventricular fibrillation during reperfusion after aortic cross-clamping for coronary artery bypass grafting may cause subendocardial injury. We investigated the use of lidocaine to prevent ventricular fibrillation during this period. In a blind, prospective, randomized trial, 91 consecutive patients undergoing elective coronary artery bypass graft procedures were given lidocaine (2 mg/kg) or normal saline immediately before removal of the aortic cross-clamp. The groups were similar with respect to demographic, clinical, and intraoperative variables. Myocardial preservation techniques were similar in both groups. Of 47 patients receiving lidocaine, 38 recovered a supraventricular rhythm without ventricular fibrillation, compared with only 5 of 44 patients in the control group (p less than .001). When ventricular fibrillation occurred, patients in the control group required a greater number of direct-current countershocks (2.31 versus 1.86) to convert to sinus rhythm. Transient heart block, requiring temporary pacing, developed in 3 patients in the lidocaine group, compared with 1 patient in the control group. There was no significant difference between the groups in the requirement for perioperative inotropic support (6 of 47 versus 6 of 44) or the number of myocardial infarctions (2 of 47 versus 1 of 44), and there were no deaths in either group. Lidocaine infusion immediately before removal of the aortic cross-clamp significantly reduces the incidence of ventricular fibrillation during the reperfusion period after cardiopulmonary bypass.

Aorta↗
PubMed1987

Serum creatine kinase and lactate dehydrogenase isoenzyme levels in patients after major esophageal surgery, esophageal dilation, and acute myocardial infarction.

All three isoenzymes of creatine kinase (CK), including MB, the fraction used in diagnosing acute myocardial infarction (AMI), have been found in the esophagus. Clinical reports suggest that injuries to the esophagus can cause changes in peripheral serum CK. This prospective study was designed to delineate whether esophageal dilation or major esophageal surgery would cause changes in serum CK and lactate dehydrogenase isoenzymes that might be consistent with the diagnosis of an AMI. Two groups of patients admitted to a coronary care unit were used as controls: patients with electrocardiographically proved AMI and those who had chest pain but who had AMI ruled out by sequential electrocardiograms. The coronary care unit patients had serum enzymes determined on admission, then every 8 hours for four samples, and then daily for 3 days. The surgical patients had determinations preoperatively, in recovery, every 8 hours for four samples, and daily for 5 days. The patients who had esophageal dilations had serum enzyme levels drawn before the procedure and every 8 hours for 2 days after dilation. Serum total CK and lactate dehydrogenase levels were determined by automated spectrophotometry. Isoenzyme levels were determined by agarose gel electrophoresis. The data suggest that small serum CK-MB bands that may be generated by esophageal surgery or dilation can be differentiated from those seen in AMI and that AMI can be confirmed by simultaneous analysis of serum lactate dehydrogenase isoenzymes.

Clinical Enzyme Tests↗
PubMed1987

A laboratory model for studying blast overpressure injury.

Blast injury remains an important source of trauma in both civilian and military settings. We have studied a recently developed blast wave generator to evaluate its effectiveness for laboratory study of blast injury. In order to determine the reliability of the device and the pathology of the lesions caused by the short duration (0.5-1.0 msec), and high intensity (60-375 psi) pressure wave, laboratory rats were exposed to the pressure waves generated by the machine. The animals were divided into three groups: the first exposed to midthoracic blasts, the second to abdominal blasts, and a group of controls exposed to a gentle stream of gas. Group I showed gross and microscopic evidence of lung blast injury of "rib imprint" hemorrhages, intra-alveolar hemorrhage, marked increase in lung weight, prolonged apnea, and bradycardia. Group II showed typical blunt abdominal trauma at the closest ranges, but characteristic submucosal hemorrhages up to 4.0 cm from the blast nozzle. In both groups, a protective effect was seen in heavier animals. The blast wave generator permits reproducible blast injury in the laboratory that is safer and faster than current methods. The lung and bowel lesions induced are grossly and microscopically similar to injuries of blast exposure seen in clinical patients.

Abdominal Injuries↗
PubMed1987

Use of the Heimlich valve in a compact autotransfusion device.

A compact device which evacuates blood from a hemothorax and facilitates rapid autotransfusion was evaluated in dogs. Experimental hemothorax was established surgically by incising the internal mammary artery through a thoracotomy with the animals under general anesthesia. Postoperatively the blood was drained by one of two methods. In the Heimlich valve group (n = 5), blood was drained by a chest tube through a one-way flutter valve into a collapsible plastic bag. In the Sorenson group (n = 5), blood was drained by a chest tube into the Sorenson Autotransfusion System. Blood from these two groups was then autotransfused. In the control group (n = 5), the drained blood was not autotransfused. Results showed no statistical difference between the two autotransfusion groups in the volume of blood collected, circulating fibrinogen levels, platelet counts, stroma-free hemoglobin levels, prothrombin time, or 51Cr-labeled RBC survival. There was a significant drop in the circulating platelet count, which returned to normal by 24 hours, in both groups of dogs which were autotransfused. We conclude that autotransfusion of blood collected by a compact device which utilizes a Heimlich valve and requires no suction is similar to using the Sorenson Autotransfusion System. It may be safe to use the Heimlich valve to collect blood for autotransfusion in clinical situations, where its qualities of simplicity, portability and a minimum requirement for storage space are desirable.

Animals↗
PubMed1987

Hypertrophic pulmonary osteoarthropathy and breast cancer.

Hypertrophic pulmonary osteoarthropathy is an uncommon, poorly understood syndrome usually seen with bronchogenic carcinomas, and rarely with tumors metastatic to the lungs or mediastinum. In a review of the literature, we have found only 140 cases associated with nonbronchogenic intrathoracic tumors. We have reported a case associated with metastatic breast carcinoma in which surgical resection led to rapid disappearance of the syndrome and prolonged palliation for the patient.

Adenocarcinoma↗
PubMed1987

Bayesian statistical theory in the preoperative diagnosis of pulmonary lesions.

We used a computerized Bayesian algorithm to assist in the preoperative diagnosis of pulmonary lesions. One hundred consecutive patients who were undergoing exploratory thoracotomy for newly discovered pulmonary lesions were prospectively evaluated. The Bayesian model used a total of 44 preoperative clinical and roentgenographic factors to categorize the lesions as benign or malignant. The Bayesian algorithm correctly categorized 96 of the 100 lesions, thereby providing an accuracy of 96 percent. The sensitivity of the model was 98 percent and the specificity was 87 percent. All but two of the 85 malignant lesions were correctly categorized and 13 of the 15 benign lesions were correctly analyzed by the model. These results indicate that computer-assisted diagnosis using the Theorem of Bayes may provide valuable preoperative information for the management of selected patients.

Adolescent↗
PubMed1987

A comparison of patients with endoscopic esophageal perforations and patients with Boerhaave's syndrome.

A review was conducted to ascertain whether patients who suffered spontaneous postemetic esophageal rupture (Boerhaave's syndrome) experienced higher morbidity and mortality than patients who had endoscopic iatrogenic esophageal perforations. Review of the records of three medical centers from 1960 to 1985 identified 11 patients with Boerhaave's syndrome (group B) and 19 with iatrogenic perforations (group E). In group B, four patients were diagnosed greater than 24 h after perforation. Nine were treated surgically; of these one died. Two group B patients who were treated conservatively survived. In group E, only four patients were diagnosed greater than 24 h after perforation. Of 19 patients, 15 were treated surgically and four, medically. In group E, three patients died (one surgically and two conservatively treated). This study suggests that there is little difference in mortality between the two groups of patients as long as the diagnosis is made early and therapy is instituted promptly.

Adult↗
PubMed1987

The theorem of Bayes as a clinical research tool.

The theorem of Bayes is a powerful research tool that has a multitude of clinical applications. Its use has been somewhat restricted because of the intrinsic complexity of Bayesian theory and the need for computer support. We explain herein the Theorem of Bayes in practical terms that specifically apply to clinical research.

Bayes Theorem↗
PubMed1986

Evaluation of the Angelchik antireflux prosthesis using a model for esophageal reflux in rhesus monkeys.

Minimal data are available about the Angelchik antireflux prosthesis although it has been inserted in more than 14,000 patients. The present animal study was designed to evaluate the effectiveness and mechanism of action of this prosthesis. A reproducible model of esophageal reflux in primates was created using a double myotomy. Lower esophageal sphincter (LES) pressure and reflux score were improved significantly in animals by insertion of an Angelchik antireflux prosthesis, a modified antireflux prosthesis, or a Nissen fundoplication. Manometrically determined LES length was increased after insertion of an Angelchik antireflux prosthesis but not by a Nissen fundoplication or sham operation. Complications after insertion of the modified prosthesis included intraluminal erosion, fibrous stricture, and slippage of the device over the stomach.

Animals↗
PubMed1986

Evaluation of serum creatine kinase and lactate dehydrogenase in experimental myocardial infarction, atriotomies, and thoracotomies.

Myocardial infarction causes elevation of the serum myocardial-associated isoenzyme of creatine kinase (CK-MB) and a serum isoenzyme of lactate dehydrogenase (LDH1). Since atrial myocardium has as much CK-MB as ventricular myocardium, surgical manipulation of the atrium could cause elevation of serum CK-MB in the postoperative period. The distribution of LDH isoenzymes is different between atrial and ventricular myocardium. Hence, surgical procedures on the atrium could, theoretically, cause different changes in serum LDH isoenzymes than those seen after acute myocardial infarction. This study was conducted to ascertain whether surgical manipulation of the atrium could cause changes in these two serum enzyme systems that might be confused with those seen after acute myocardial infarction. Right thoracotomies were performed on 20 dogs. Each dog then was assigned randomly to one of four groups: thoracotomy (control), placement of atrial pursestring sutures, atriotomy, or acute perioperative myocardial infarction. Serum total and isoenzyme distributions of CK and LDH were measured for 48 hours in all animals. The results suggest that significant elevations of serum CK-MB occurred even after small atriotomies. Confirmation of a ventricular myocardial origin of postoperative serum CK-MB bands was obtained by analysis of serum LDH isoenzymes in that the ratio of LDH1 to LDH2 and the absolute value of serum LDH1 became elevated only after acute perioperative myocardial infarction and not after atriotomy.

Animals↗
PubMed1986

Development of circulating antiheart antibodies as a result of coronary bypass surgery.

Antiheart antibodies have been implicated as a marker of postcardiotomy syndrome in patients undergoing coronary artery bypass. To assess the frequency of and contributory factors in the development of antiheart antibodies after coronary bypass procedures, 33 patients were examined for evidence of antiheart antibodies before and for seven days after routine coronary artery bypass operations. Overall titers of antiheart antibodies rose in approximately 66% of the patients. However, this rise was not accompanied by any major clinical symptoms. History of previous myocardial infarction or myocardial injury did not correlate with a higher frequency of development of antibodies. Antiheart antibodies appear to be a common consequence of coronary artery bypass operations and are not routinely associated with the development of postcardiotomy syndrome.

Adult↗
PubMed1986

Surgical implications of intraoperative postinfarction ventricular rupture.

This case report documents that ventricular myocardial rupture after acute infarction may seal with clot, only to rupture again with potentially lethal consequences. At exploration, the clot over a fresh rupture was intact. As closure was started, the clot disrupted, causing severe hemorrhage. Rupture was successfully repaired and the patient survived.

Cardiopulmonary Bypass↗
PubMed1986

Acute diverticulitis following cardiac surgery.

Gastrointestinal complications requiring surgical correction following cardiopulmonary bypass most frequently involve the upper gastrointestinal tract. Surgical diseases of the colon are quite unusual in this setting. We recently performed cardiac surgery on three patients who developed acute diverticulitis requiring laparotomy in the early postoperative period. The presentation and management of this disorder after open heart surgery are discussed.

Acute Disease↗
PubMed1986

Coronary artery bypass grafting in young patients under 36 years of age.

Results of coronary artery bypass graft (CABG) surgery in patients under age 36 who were operated upon between 1970 and 1980 at two large medical centers were compared to matched control patients, age 45 to 59 years, and 60 years and over. Patient follow-up ranged from one to 13 years (average five years). Event-free survival was significantly worse in the young group (37 percent) vs the middle aged group (61 percent, p less than 0.01) and vs the elderly group (59 percent, p less than 0.02). Failure of the operation was due to failure to improve or worsening of Canadian Cardiovascular Society anginal class, need for reoperation, subsequent myocardial infarction, or death due to cardiac causes. Risk of failure of CABG surgery in young patients was increased with the presence of cardiac risk factors. Because of the high rate of long-term failure of CABG surgery in young patients, its use in this group needs to be reevaluated relative to current aggressive medical therapy for angina.

Actuarial Analysis↗
PubMed1986

Intrathecal dynorphin A (1-13) and (3-13) reduce spinal cord blood flow by non-opioid mechanisms.

Dynorphin A (Dyn A)-related peptides have been implicated in the pathophysiology of spinal cord injury in part because their intrathecal (i.t.) injection causes hindlimb paralysis. The effects of paralytic doses of i.t. Dyn A (1-13) and Dyn A (3-13) on spinal cord blood flow and cardiac output were examined in rats using radiolabeled microspheres. Both Dyn A (1-13) and Dyn A (3-13) significantly reduced blood flow in lumbosacral spinal cord without altering cardiac output. Pretreatment with naloxone failed to block these reductions in blood flow. Thus, the paralytic effects of Dyn A may result from non-opioid actions of Dyn A to reduce spinal cord perfusion.

Animals↗