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Biomedical subjects

C E Chambers

Publications and source records attributed to C E Chambers.

32 records · Page 2Linked to original sources

Effects of pyrazinoylguanidine on the glucose-fatty acid cycle in normal subjects and patients with non-insulin-dependent diabetes mellitus.

Pyrazinoylguanidine (PZG) reduced the hyperglycemia, hyperinsulinemia, and hyperlipidemia of patients with non-insulin-dependent diabetes mellitus (NIDDM) as well as of normal subjects receiving hydrochlorothiazide (HCTZ). Mechanisms are proposed by which PZG downregulated the elevated glucose-fatty acid cycle toward a more normal level in NIDDM patients and in non-diabetic subjects maintained on HCTZ. Despite maintenance of these NIDDM patients on their current antihypertensive medication, PZG reduced further their systolic and diastolic pressures. PZG was well tolerated by both normal and NIDDM patients.

Adult↗

Digital blunt dissection technique to assist laparoscopic gonadectomy in inguinally located/adhered gonads.

Laparoscopic gonadal removal in two patients, one with XY gonadal dysgenesis and the other with complete androgen insensitivity is described. In both cases, the gonads were either located deep in the inguinal canal or adherent in that area. Digital blunt dissection using a finger passed through the lateral lower abdominal trocar incision site (12 mm) at the mid-clavicular line of the lower abdomen, combined with external palpation/elevation of the inguinal ring, allowed rapid dissection and isolation of the desired structures and vascular pedicles.

Adolescent↗

Pyrazinoylguanidine: antihypertensive, hypocholesterolemic, and renin effects.

In a single-blind, placebo-controlled study of 12 subjects diagnosed as having mild to moderate hypertension and hypercholesterolemia, pyrazinoylguanidine (PZG) in a dose of 600 mg twice daily for 4 weeks reduced systolic blood pressure and heart rate. Pyrazinoylguanidine also reduced diastolic pressures, but to a lesser extent. Pyrazinoylguanidine reduced total serum cholesterol and low-density lipoprotein (LDL). Regression analysis indicated a dose-dependent reduction of both total cholesterol and LDL by PZG, i.e., the higher the presenting serum concentration, the greater the reduction by PZG. The extent of the reductions produced by PZG in elevated cholesterols and LDLs was highly correlated (r = .949). Normal high-density lipoprotein levels were unchanged by PZG. Pyrazinoylguanidine increased 24-hour urine volume and urinary excretion of sodium. Serum Na+, K+, or Cl- concentrations were unaltered. Means for plasma aldosterone and renin activities tended to decrease, but these trends did not attain statistical significance. Pyrazinoylguanidine was well tolerated. An activity profile that includes antihypertensive effects as well as reduction in hypercholesterolemia without major impact on serum renin or electrolyte balance makes PZG an attractive candidate for the management of hypertension.

Aged↗

Ability of dipyridamole-thallium-201 imaging one to four days after acute myocardial infarction to predict in-hospital and late recurrent myocardial ischemic events.

The ability of dipyridamole-thallium-201 imaging to predict in-hospital and late cardiac events when performed very early (62 +/- 21 hours, range 23 to 102) after acute myocardial infarction (AMI) was tested in 50 patients. During hospitalization, 1 patient developed recurrent AMI and 8 patients developed recurrent angina after MI associated with ST-segment depression at 60 +/- 42 hours after the dipyridamole-thallium-201 imaging; of these, 6 required urgent coronary revascularization. No patient died in-hospital. There were no serious adverse effects during the dipyridamole protocol. Using stepwise multivariate logistic regression analysis, the best and only statistically significant predictor of in-hospital ischemic cardiac events was the presence of thallium-201 redistribution within the infarct zone (p = 0.0001). Of 20 patients with infarct zone thallium-201 redistribution, 9 (45%) developed in-hospital ischemic cardiac events compared to 0 of 30 patients without infarct zone thallium-201 redistribution (p less than 0.0001). During a follow-up 12 +/- 7 months after discharge, 3 additional patients with infarct zone thallium-201 redistribution developed recurrent AMI or unstable angina, whereas no patient without infarct zone thallium-201 redistribution developed ischemic cardiac events. These data suggest that dipyridamole-thallium-201 imaging performed very early after AMI may identify a subgroup of patients at high risk for in-hospital and late ischemic cardiac events. Such patients may benefit from early cardiac catheterization and revascularization. Patients without infarct zone thallium-201 redistribution appear to be at very low risk for in-hospital and late ischemic cardiac events and may be candidates for early discharge.

Coronary Disease↗

Management of acute chest pain syndrome.

In differentiating the various etiologies of acute chest pain syndromes, the clinician is faced with identifying life-threatening situations. This article has presented a diagnostic approach for establishing the cardiovascular and noncardiovascular etiologies of acute chest pain syndromes. Cardiovascular etiologies must be identified early upon presentation in order to minimize morbidity and mortality. Myocardial ischemia and particularly necrosis is time dependent: early intervention preserves myocardium, particularly when initiating thrombolytic therapy. Aortic valvular disease, particularly critical aortic stenosis, if unrecognized, can precipitate rapid patient deterioration if inappropriately treated with nitrate therapy for presumed ischemic disease. Aortic dissection, if not properly diagnosed, can progress to stroke, MI, paralysis, and death. Noncardiovascular etiologies are similarly complex but often have less potential for life-threatening consequences. In identifying gastrointestinal bleeding, a careful rectal exam may be safely performed even in the setting of MI. A tension pneumothorax can suddenly compromise vascular return and progress to sudden death if unrecognized. Finally, chest wall symptoms, though seldom life-threatening, can be debilitating to the patient and often respond to anti-inflammatory therapy. In conclusion, the goals of this article were to present a step-wise approach to the diagnosis and management of an often complex presentation. By systematically approaching these patients with a thorough understanding of etiologies, diagnostic options, and therapeutic considerations, both physician anxiety as well as patient complications will be greatly diminished.

Angina Pectoris↗

Dipyridamole-induced ST segment depression during thallium-201 imaging in patients with coronary artery disease: angiographic and hemodynamic determinants.

To examine the angiographic and hemodynamic determinants of dipyridamole-induced ST segment depression in patients with coronary artery disease, 41 patients with angiographically documented coronary disease who underwent dipyridamole-thallium-201 myocardial scintigraphy were studied. Dipyridamole-induced ST depression occurred in 14 (34%) of the 41 patients. Stepwise multivariate logistic regression was performed to compare the predictive value of angiographic findings (good coronary collateral vessels, jeopardized collateral vessels, multivessel disease), hemodynamic changes (changes in heart rate, systolic pressure, diastolic pressure and rate-pressure product), thallium-201 results (perfusion defect, thallium-201 redistribution) and demographic data (age, gender, medications). Only the presence of good coronary collateral vessels (p less than 0.02) and increases in rate-pressure product after dipyridamole infusion (p less than 0.02) were significant multivariate predictors of dipyridamole-induced ST depression. Good collateral vessels were more common in the group with ST depression (11 [79%] of 14) than they were in the group without ST depression (6 [22%] of 27; p less than 0.001). Rate-pressure product increased 2,835 +/- 1,648 beats/min.mm Hg in the group with ST depression compared with 1,179 +/- 1,417 beats/min.mm Hg in patients without ST depression (p less than 0.005). In conclusion, dipyridamole-induced ST segment depression in patients with coronary artery disease appears to be related to 1) the presence of good coronary collateral vessels, which may act by facilitating "coronary steal", and 2) increases in rate-pressure product, reflecting increased myocardial oxygen demand. These observations may explain the lack of prognostic value of dipyridamole-induced ST segment depression described in previous reports.

Aged↗

Quantitation of HeLa cell monolayer invasion by Shigella and Salmonella species.

A major determinant in the virulence of Salmonella and Shigella spp. is the ability of these organisms to invade epithelial cells of the gastrointestinal mucosa and multiply intracellularly. The invasion of cell culture monolayers is a convenient experimental system to evaluate eucaryotic cell penetration and is correlated with the potential of a strain to cause human disease. We have developed an agarose-L agar overlay technique which allows for the convenient quantitation of the number of infected tissue culture cells in a monolayer. Bacterial strains were introduced onto antibiotic-free HeLa cell monolayers. Infected monolayers were washed, and noninternalized bacteria were counterselected with kanamycin (50 micrograms/ml). The number of infected HeLa cells present was determined by overlaying the monolayer with distilled water-agarose (0.5 to 1.5%) followed by an equal volume of 2X L agar. Bacterial colonies formed over infected cells in 24 h at 37 degrees C, and wells were counted with a dissecting microscope under X2 power. Bacterial colonies were not observed with noninvasive variants of Shigella spp. To obtain countable wells (20 to 200 CFU) the multiplicity of infection or invasion times were adjusted. With a 90-min invasion time, the invasive potential of a strain was reflected by the multiplicity of infection needed to produce countable wells. The quantitation of bacterium-invaded cells by using standard bacteriological methods is a convenient and rapid method to evaluate the invasive potential of bacterial strains. Additionally, parameters essential for the invasive process can easily be investigated.

Agar↗

Saline lavage: a rapid, safe, effective method of whole-gut irrigation for bowel preparation.

The standard preparation for cleansing the colon usually involves dietary restrictions, purgatives, and enemas. This is time-consuming, often uncomfortable, and at times unsuccessful. This study of 37 patients examines the efficacy of saline lavage as an alternative method for cleansing the bowel. Isotonic sodium chloride solution is passed into the gut via a small nasogastric tube. The flush is continued for about four hours, until clear effluent is passed per anus. There were no significant complications or variations in weight or serum electrolyte values. Patient acceptance was generally excellent. In our opinion, this rapid bowel preparation consistently provided a clean bowel so that both bowel preparation and colonscopy were accomplished the same day.

Adult↗

Immediate balloon inflation during ventricular fibrillation complicating coronary angioplasty--an alternative technique to angioplasty system withdrawal: case reports and review.

Two patients are presented in whom ventricular fibrillation occurred during otherwise uncomplicated percutaneous transluminal coronary angioplasty. Rather than withdrawing the angioplasty dilatation system in place in the coronary vessel before instituting resuscitation procedures, immediate balloon inflation was performed while a defibrillator was charged. During balloon inflation, both patients were countershocked, and they recovered stable cardiac rhythm. Postresuscitation hemodynamic and angiographic analysis revealed successful angioplasty results. This report describes an alternative technique to immediate removal of the balloon dilatation system for cardiac arrest complicating coronary angioplasty. Theoretical advantages and potential disadvantages of this technique are discussed.

Aged↗

Robotically assisted coronary artery bypass grafting: a prospective single center clinical trial.

AIM: This prospective study was performed as a Phase 1 Food and Drug Administration clinical trial to assess the safety and feasibility of robotically assisted coronary artery bypass grafting (CABG). METHODS: Eighteen patients undergoing elective CABG were enrolled in this study. Full sternotomy was performed in 17 of 18 patients, while cardiopulmonary bypass and cardioplegic arrest was used in all cases. Robotically assisted CABG of the left internal thoracic artery (LITA) to the left anterior descending artery (LAD) was performed through three ports using a robotically assisted microsurgical system. Conventional techniques were used to perform all other grafts. Blood flow in the LITA graft was measured in the operating room, and when necessary, angiography was performed. Six weeks after the operation, all patients underwent selective coronary angiography of the LITA graft. RESULTS: Robotically assisted coronary artery anastomoses were successfully completed in all patients. Blood flow through the LITA graft was adequate in 16 of 18 patients (89%). The two inadequate grafts were revised successfully by hand. Six weeks after the operation, angiography demonstrated a graft patency of 100% (13 of 13). Mean follow-up has been over 190 days. All patients remain New York Heart Association Angina Class I. CONCLUSION: Robotic assistance represents an enabling technology that may allow the surgeon to perform endoscopic coronary artery anastomoses. Further clinical trials are needed to explore the clinical potential and value of robotically assisted CABG.

Coronary Artery Bypass↗