Effects of short-term and long-term androgen treatment on the diaphragm in male and female rats

The effects of short-term (2.5 wk) and long-term (10 wk) testosterone propionate (2.5 mg/day; 5 days/wk) treatment on diaphragm contractility, fatigue resistance, and fiber type proportions were studied in male and female rats. Contractility and fatigue resistance indexes were measured in an in vitro diaphragm costal strip preparation by direct stimulation at 37 degrees C. The fatigue paradigm consisted of 30 trains/min at 5 Hz (50% duty cycle) for 10 min. Fatigue resistance indexes were calculated as postfatigue divided by baseline forces. In females but not males, testosterone treatment produced significant increases in body weight, costal diaphragm weight, and contractility and significant decreases in fatigue resistance indexes. The interaction between testosterone treatment and the duration of treatment was significant, with the increase in contractility (females) being significant after short-term but not long-term treatment. No significant difference in fiber type proportions or areas was observed, regardless of treatment duration or the preexperimental, basal circulating level of androgen.

Effects of long-term continuous respiratory resistive loading on rat diaphragm function and structure

The effects of long-term (24- to 28-wk) continuous respiratory resistive loading on diaphragm mass, contractility, fatigue, and fiber types were studied in male rats. Increased respiratory resistance was produced by extratracheal banding, and results were compared with sham-operated pair-fed controls. At the time the animals were killed, banded tracheal segment internal diameter was reduced by 57% of control values. Diaphragm surface area and muscle mass (normalized for body mass) increased by 19% of control values. Isometric diaphragm contractility and fatigue resistance indexes were measured using an in vitro diaphragm costal strip preparation at 37 degrees C. Twitch and tetanic stimulations were evoked using direct stimulation. Compared with controls, baseline tensions (normalized for diaphragm cross-sectional area) were significantly decreased at low frequencies. Fatigue resistance (endurance) indexes were significantly increased at all frequencies. These findings were consistent with observed increases in number and cross-sectional area of type I (low-tension high-endurance) fibers. We conclude that the diaphragm adapts to chronic long-term resistive loads by sacrificing peak tensions for an increase in endurance capacity.

The right approach to carcinoma of the cardia: preliminary results

Surgical treatment of carcinoma of the lower oesophagus and cardia can be compromised by technical difficulties associated with inadequate exposure of the operative field. This may lead to anastomotic failure or local recurrence. A simultaneous right abdominothoracic approach to the oesophagogastric junction without division of either the costal margin or diaphragm facilitates access, allowing radical resection and the performance of a safe anastomosis without the necessity of redraping the patient part way through the procedure. Maintaining the costal margin and diaphragm reduces the pulmonary problems associated with a conventional abdominothoracic incision. Thirty two consecutive patients who have been operated upon between 1983 and 1990 using the synchronous right abdominothoracic approach and who have had a stapled anastomosis have been reviewed. The post-operative complication rate was low and the 5 year survival figure is 17%.

Laparoscopic general surgery

Laparoscopic cholecystectomy has become the treatment of choice for symptomatic gallstones. The success of this procedure has prompted surgeons to explore the possibility of performing other procedures laparoscopically. This article describes some of these new techniques and discusses the merits of a minimally.

Surgical options for left-sided large bowel emergencies

Current choices of operation for left-sided large bowel emergencies have been established by a questionnaire sent to 218 consultant surgeons asking which operation they would perform under varying circumstances for obstructing sigmoid carcinoma and diverticular disease. A 92% response rate was obtained. Hartmann's procedure (with or without a mucus fistula) is the most popular operation for all conditions. Sigmoid colectomy with primary anastomosis is performed by 40% of surgeons for obstructing carcinomas, but less commonly in other situations. On-table lavage is rarely used, and the majority of anastomoses are not protected by a proximal stoma. Subtotal colectomy is very seldom employed, except when caecal perforation results from an obstructing carcinoma. Some surgeons perform a defunctioning colostomy alone even in the presence of a perforation.

Temperature dependence of rat diaphragm muscle contractility and fatigue

The diaphragm is a skeletal muscle of mixed fiber type that is unique in its requirement to maintain contractile function and fatigue resistance across a wide range of temperatures to sustain alveolar ventilation under conditions of hypo- or hyperthermia. The direct effect of temperature (15-41 degrees C) on rat diaphragm isometric contractility and fatigue was determined in vitro. As temperature decreased from 37 to 15 degrees C, contraction and relaxation times increased, and there was a left shift of the diaphragm's force-frequency curve, with decreased contractility at 41 and 15 degrees C. Fatigue was induced by 10 min of stimulation with 30 trains/min of 5 Hz at a train duration of 900 ms. Compared with 37 degrees C, fatigue resistance was enhanced at 25 degrees C, but no difference in fatigue indexes was evident at extreme hypothermia (15 degrees C) or hyperthermia (41 degrees C). Only when the fatigue program was adjusted to account for hypothermia-induced increases in tension-time indexes was fatigue resistance evident at 15 degrees C. These findings indicate that despite the diaphragm's unique location as a core structure, necessitating exposure to in vivo temperatures higher than found in limb muscle, the temperature dependence of rat diaphragm muscle contractility and fatigue is similar to that reported for limb muscle of mixed fiber type.

Cardiac amyloidosis causing ventricular tachycardia. Diagnosis made by endomyocardial biopsy

In patients with malignant ventricular arrhythmias, endomyocardial biopsy may be helpful when all other findings from the workup are negative. A case of nonsustained polymorphic ventricular tachycardia is presented. The findings from an echocardiogram, coronary angiogram, and cardiac catheterization were negative. An electrophysiologic study showed inducible nonsustained ventricular tachycardia. A right ventricular endomyocardial biopsy was diagnostic of cardiac amyloid. The findings from a workup for systemic amyloidosis were negative. Primary cardiac amyloidosis should be considered in patients with malignant arrhythmias and no documented heart disease, and endomyocardial biopsy is helpful in making this diagnosis.

Sutures for inguinal herniorrhaphy--a comparison of monofilaments with PTFE

Polybutester (Novafil, Davis & Geck) and expanded polytetrafluoroethylene PTFE (Gore-tex, W L Gore) were compared with nylon (Ethilon, Ethicon UK) for elective inguinal herniorrhaphy. PTFE had the best handling characteristics, but is expensive, and increased wound sepsis attended its use. Polybutester had significantly better handling characteristics, and is an attractive alternative to nylon for hernia repair.

A system approach to intravenous thrombolysis in acute myocardial infarction in community hospitals: the influence of paramedics

During a 3-year period, intravenous streptokinase (IV STK) was given to 110 consecutive patients ages 34-78 in the course of acute myocardial infarction (AMI) in three community hospitals served by the same paramedic system. 1.5 million units of IV STK was given over 30 minutes. Half of the patients were brought to the hospital by paramedics. The average time from onset of pain to administration of IV STK was 107 minutes in the paramedic group and 182 minutes for the others. Of 110 patients, 98 (89%) showed clinical evidence of reperfusion and 94 of 106 patients (89%) showed angiographic reperfusion. Angiography was performed from 1 to 10 days post-AMI. Mean time to angiography was 6 days for the first 58 patients and 2 days for the last 52 patients. In-hospital mortality was 2 of 110 patients and there was 1 late death at 8 months for an overall 3-year mortality 2.7%. Of 86 patients, 83 (96%) working before their infarct are working now. Of 107 survivors, 96 (90%) are Functional Class I.

CONCLUSIONS

(1) IV STK is safely administered in a high percentage of AMI patients. (2) IV STK is safely administered in community hospitals. (3) Paramedics act as an early warning system and allow for earlier treatment than patients presenting without paramedic involvement. (4) Successful coronary reperfusion with IV STK results in low mortality rates and minimizes functional disability. (5) A system-wide approach to reducing time to treatment in AMI may be the most influential factor in affecting morbidity and mortality.

Prolonged selective urokinase infusion in totally occluded coronary arteries and bypass grafts: two case reports

Reports are presented demonstrating a technique for dissolving thrombus in coronary arteries and bypass grafts by using prolonged selective infusion of urokinase via an infusion wire. This allows one to pass a steerable guide wire through the culprit stenosis and perform angioplasty on a distal lesion which could not be previously seen.

The right approach to carcinoma of the cardia and lower oesophagus

Successful surgical palliation for carcinoma of the cardia and lower oesophagus is often compromised by anastomotic failure or local recurrence. These complications follow technical difficulty in achieving adequate resection and a safe anastomosis through inappropriate surgical exposure, often via the left chest. A technique of oesophagogastrectomy is described employing a simultaneous right abdominothoracic approach without division of either costal margin or diaphragm. Synchronous laparotomy and thoractomy facilitates both resection and anastomosis, and obviates the necessity to turn the patient over and redrape halfway through the operation. Closure of the distal stomach and the gastro-oesophageal anastomosis are performed using staplers. No anastomotic leaks were detected in the 15 patients described.