Ultrasound evaluation of piglet diaphragm function before and after fatigue

Clinically, a noninvasive measure of diaphragm function is needed. The purpose of this study is to determine whether ultrasonography can be used to 1) quantify diaphragm function and 2) identify fatigue in a piglet model. Five piglets were anesthetized with pentobarbital sodium and halothane and studied during the following conditions: 1) baseline (spontaneous breathing); 2) baseline + CO2 [inhaled CO2 to increase arterial PCO2 to 50-60 Torr (6.6-8 kPa)]; 3) fatigue + CO2 (fatigue induced with 30 min of phrenic nerve pacing); and 4) recovery + CO2 (recovery after 1 h of mechanical ventilation). Ultrasound measurements of the posterior diaphragm were made (inspiratory mean velocity) in the transverse plane. Images were obtained from the midline, just inferior to the xiphoid process, and perpendicular to the abdomen. M-mode measures were made of the right posterior hemidiaphragm in the plane just lateral to the inferior vena cava. Abdominal and esophageal pressures were measured and transdiaphragmatic pressure (Pdi) was calculated during spontaneous (Sp) and paced (Pace) breaths. Arterial blood gases were also measured. Pdi(Sp) and Pdi(Pace) during baseline + CO2 were 8 +/- 0.7 and 49 +/- 11 cmH2O, respectively, and decreased to 6 +/- 1.0 and 27 +/- 7 cmH2O, respectively, during fatigue + CO2. Mean inspiratory velocity also decreased from 13 +/- 2 to 8 +/- 1 cm/s during these conditions. All variables returned to baseline during recovery + CO2. Ultrasonography can be used to quantify diaphragm function and identify piglet diaphragm fatigue.     

Laboratory studies in cross-species lung transplantation

The lack of sufficient suitable human donor lungs for the many patients requiring pulmonary transplantation as life-saving therapy for end-stage lung diseases has generated extensive interest in cross-species lung transplantation. Ethical concerns and those of animal rights advocates have prompted studies of nonprimate species as potential solid organ donors for humans. This paper provides an overview of some of the laboratory studies of cross-species pulmonary transplantation performed over the past 20 years and focuses, in particular, on more recent work (from our laboratory and others) in the area of porcine-to-primate pulmonary xenotransplantation.     

The arterioportal fistula syndrome: clinicopathologic features, diagnosis, and therapy

BACKGROUND & AIMS: Arterioportal fistulas (APFs) are rare vascular disorders of the mesenteric circulation. The aim of this study was to determine the etiology, anatomical location, and main symptom at presentation of APFs, and analyze the various modes of treatment. METHODS: The etiology, clinical presentation, radiographs, and treatment of 12 patients with APFs are reported in detail, and another 76 cases published since 1980 are reviewed. RESULTS: APFs result from trauma (n = 25, 28%), iatrogenic procedures (n = 14, 16%), congenital vascular malformations (n = 13, 15%), tumor (n = 13, 15%), aneurysm (n = 12, 14%), and other causes (n = 11, 12%). The origin of APFs is the hepatic artery in the majority of patients (n = 56, 65%). The main symptoms at presentation are lower or upper gastrointestinal bleeding (n = 29, 33%), ascites (n = 23, 26%), heart failure (n = 4.5%), or diarrhea (n = 4.5%). Radiological intervention provides definitive treatment in 42% (n = 33) of patients, whereas the remainder are treated by surgery alone (n = 27, 31%) or a combination of radiological intervention and surgery (n = 8, 9%). CONCLUSIONS: APFs result in a protean syndrome variously combining portal hypertension and other hemodynamic imbalances (heart failure, intestinal ischemia). Single or multiple interventional radiological procedures using arterial and/or venous approaches allow definitive treatment of most APFs. With increasing technological advances, it is anticipated that surgery will only be indicated in rare instances after failure of radiological intervention(s).     

A phase II trial of weekly infusional 5-fluorouracil in combination with low-dose leucovorin in patients with advanced colorectal cancer

We examined 59 breast cancers for p53 and bcl-2 protein expression by immunohistochemistry. The results were correlated with Ki-67 immunostaining. p53-negativity was noted in 40 cases and the remaining 19 tumours were p53-positive. Thirty-six tumours showed strong expression of bcl-2 and in 23 no staining for this protein was observed. We found statistically significant reverse correlation between expression of p53 and bcl-2 in majority of carcinomas: 31 cases were bcl-2 positive and p53-negative, and 14 tumours were bcl-2-negative and p53-positive. Six carcinomas showed no nuclear staining for Ki-67 and in the remaining 53 the percent of cancer cells positive for Ki-67 ranged from 1 to 60 (mean: 14.6). In these 53 cases we found that bcl-2-positive tumours were characterized by lower proliferation than bcl-2-negative tumours, the mean value of Ki-67 immunostaining being 10.7% and 23.0%, respectively. p53-negative tumours showed lower proliferation than p53-positive tumours: mean Ki-67 index was 10.2% and 23.9%, respectively. We conclude that immunohistochemically detected p53 and bcl-2 proteins show a significant inverse relationship in majority of breast carcinomas and their expression correlates with tumour proliferation (Ki-67 immunostaining).     

Titanium and bioactive glass-ceramic coated titanium as materials for keratoprosthesis

The current problem with keratoprosthesis is the ingrowth of corneal or conjunctival epithelium into the anterior chamber. This may lead to infections and extrusion of the prosthesis as well as to the development of retroprosthetic membrane and secondary glaucoma. Glass-ceramic coated and uncoated titanium has been tested as material for the keratoprosthesis to prevent epithelial ingrowth. Twenty-two Supra-Descemet's membrane keratoprostheses were inserted in the eyes of 22 rabbits for 1, 2, 4, 8, or 12 months. The prosthesis had an optic part made of polymethylmetacrylate (PMMA). The support for the optic part and the flange of the prosthesis were made of titanium. Eleven of the prostheses were coated with glass-ceramic. The histological sections of the enucleated eyes were prepared through the central part of the cornea and the prosthesis using a cutting-grinding method. The histological analysis was made on both halves of the implants separately giving two analysis areas in each eye. All 11 titanium prostheses were retained for the time period planned. Two glass-ceramic coated prostheses were lost at 2 and 4 weeks, respectively. This was caused by difficulties at surgery due to a thick coating. These eyes were excluded from the histological analysis. No significant ingrowth of epithelium was seen in 15/18 (83%) and in 16/22 (73%) of the analysed areas of the glass-ceramic coated and titanium prostheses, respectively. Titanium appears to be a suitable material for the keratoprosthesis. The ingrowth of the epithelium may be hindered further by coating the titanium with bioactive glass-ceramic.     

Effects of beta-carotene and other factors on outcome of cervical dysplasia and human papillomavirus infection

OBJECTIVES: The age-dependence of the development of ventricular arrhythmias was studied in German shepherd dogs with inherited ventricular arrhythmias and sudden death. BACKGROUND: A colony of German shepherd dogs has been established that exhibit inherited ventricular arrhythmias and sudden death. The incidence of arrhythmias increases with age. Because ventricular tachycardia is associated with bradycardia, it was hypothesized that the increased incidence of arrhythmias was related to age-dependent slowing of heart rate. METHODS: Arrhythmia counts and RR intervals were measured from serial ambulatory ECG recordings obtained in 71 dogs (1-48 weeks). In addition, 19 dogs were challenged with phenylephrine (10 micrograms/kg i.v.) at 15, 28, and 45 weeks of age, 10 dogs were challenged with epinephrine (1 microgram/kg i.v.) at 3, 5, 7, 9, 11, 18, and 28 weeks of age, and 10 dogs were challenged at 28 weeks with epinephrine (2.5 micrograms/kg i.v.), before and after propranolol (0.5 mg/kg i.v.). RESULTS: The incidence and severity of ventricular arrhythmias increased between 7 and 28 weeks of age and decreased between 28 and 44 weeks of age. The age-dependent increase in the incidence of ventricular tachycardia was associated with age-dependent reductions in sinus rate. Baroreflex-mediated slowing of the heart rate unmasked arrhythmias in young animals that did not spontaneously display arrthythmias and exacerbated existing arrhythmias in older animals. However, the magnitude of baroreflex-induced bradycardia was similar from 7-18 weeks of age, yet the incidence of arrhythmias increased progressively. Moreover, the waning of ventricular arrhythmias in older animals was not associated with more rapid sinus rates. CONCLUSION: The risk for sudden death in dogs with inherited ventricular arrhythmias increases with age in part because of age-dependent slowing of heart rate and in part because of other heart-rate-independent factors. The correspondence between the development of ventricular tachycardia and sinus pauses is consistent with the hypothesis that ventricular arrhythmias are initiated by early afterdepolarization-induced triggered activity.     

Aortic corset syndrome

The majority of proximal anastomotic complications of aortofemoral bypass grafts are related to the formation of pseudoaneurysms or true proximal aneurysmal dilation of the residual infrarenal aorta. The late development of occlusive disease at the proximal anastomosis is an extremely rare event. We report two patients in whom symptomatic stenoses developed involving the proximal anastomoses of aortofemoral bypass grafts originally placed for aortoiliac occlusive disease. Surgical exploration demonstrated the presence of a constricting prosthetic corset wrapped around the proximal suture line of each graft. Exuberant neointimal hyperplasia was responsible for both stenoses.