A multi-scale model of the interplay between cell signalling and hormone transport in specifying the root meristem of Arabidopsis thaliana.

The growth of the root of Arabidopsis thaliana is sustained by the meristem, a region of cell proliferation and differentiation which is located in the root apex and generates cells which move shootwards, expanding rapidly to cause root growth. The balance between cell division and differentiation is maintained via a signalling network, primarily coordinated by the hormones auxin, cytokinin and gibberellin. Since these hormones interact at different levels of spatial organisation, we develop a multi-scale computational model which enables us to study the interplay between these signalling networks and cell-cell communication during the specification of the root meristem. We investigate the responses of our model to hormonal perturbations, validating the results of our simulations against experimental data. Our simulations suggest that one or more additional components are needed to explain the observed expression patterns of a regulator of cytokinin signalling, ARR1, in roots not producing gibberellin. By searching for novel network components, we identify two mutant lines that affect significantly both root length and meristem size, one of which also differentially expresses a central component of the interaction network (SHY2). More generally, our study demonstrates how a multi-scale investigation can provide valuable insight into the spatio-temporal dynamics of signalling networks in biological tissues.

Emergency coronary revascularization in a liver transplant recipient.

A liver transplant recipient in cardiogenic shock from an acute myocardial infarction and failed coronary angioplasty underwent successful emergency coronary artery bypass graft surgery. Our case is only the fourth documented report of a coronary artery bypass graft in a liver transplant patient and the first conducted on an emergency basis in a patient in cardiogenic shock. Preservation of both cardiac and liver function has been evident in all cases. Based on these findings, liver transplantation should not be a deterrent or contraindication to coronary artery bypass or cardiac surgery.

Human pulmonary dirofilariasis presenting as a solitary pulmonary nodule.

A case of human pulmonary dirofilariasis had positive serologic testing postoperatively. Increased awareness of this entity as a cause of solitary pulmonary nodules may lead to preoperative serologic and intradermal testing, and to the possibility of arriving at a preoperative diagnosis.

Spontaneous disruption of Ionescu-Shiley bovine pericardial xenograft in the mitral position.

We report a case of spontaneous disruption of the Ionescu-Shiley pericardial xenograft in the mitral position at 3 years and its successful management.

Delayed recurrent massive thromboembolism through a vena caval clip after pulmonary embolectomy.

A case of recurrent massive pulmonary embolization through a modified Miles' clip two weeks after successful emergency pulmonary embolectomy is reported. Vena caval ligation is probably a safer alternative in these critically ill patients.

Primary cardiac tumors: experience with 25 cases.

The case histories of patients with primary cardiac neoplasms are presented. The mean age was 49.6 years and females predominated (17:8). Nineteen of the tumors were benign (76%), 18 myxomas and one mesenchymal hamartoma. There were six malignant neoplasms; two myxosarcomas, two rhabdomyosarcomas, one skeletal angiomatosis, and one malignant melanoma. The clinical presentation was congestive heart failure in 17 patients and peripheral embolization in five (one patient with both). There were four asymptomatic patients. Antemortem diagnosis was made in 20 patients and five were discovered at autopsy. After 1970, almost 95% of the patients were diagnosed preoperatively while only 14% of the patients had preoperative diagnosis before 1970. Cardiac catheterization and echocardiography were the most useful diagnostic procedures performed but a computed tomographic scan of the heart performed in a patient with right ventricular hamartoma was of great value in delineating the lesion. Twenty-one patients underwent a total of 26 operations but complete excision of the lesion was possible in only 16 patients. Three patients underwent extensive resection and reconstruction. Associated procedures consisted of coronary artery bypass grafts in two patients, mitral valve annuloplasty in one, and a right lung biopsy. Although there was no operative mortality following the original procedure, one patient died after a third operation for recurrence and another underwent unsuccessful emergency pericardiectomy. All patients with malignant lesions died from recurrence 6 to 13 months postoperatively while only three patients in the benign group died and these of unrelated causes. Surgical resection is the treatment of choice for all primary cardiac neoplasms since it is curative in the benign tumors and may prolong life for up to a year with malignant tumors.

Sigmoid volvulus in the young. A case following cesarean section.

Sigmoid volvulus occurs more frequently in the younger patient than is presently thought. It is not infrequent in females. It usually presents with "colicky" abdominal pain, long-standing constipation or obstipation, and increasing distention of several days' duration. A history of similar attacks strengthens the suspicion for this diagnosis. Abdominal x-ray films will usually reveal severe colonic dilation down to a low point in the sigmoid, without gas in the rectum. The classic "horseshoe" sign is seldom seen, but when present, strengthens the diagnosis. Surgical manipulation and pregnancy may be contributing factors. Treatment should be surgical unless contraindicated by specific circumstances.

Trocar cannulation of the ascending aorta: a new technique.

An improved technique for cannulating the ascending aorta has been developed and used in 229 consecutive open-heart procedures without complication. Advantages of the method include speed and ease of cannula insertion, elimination of the need for partial-occlusion clamping of the aorta, minimization of the risk of introducing air, minimization of blood loss, and facilitation of distal cannulation in patients with short aortas.

Strut fracture and disc embolization of a Björk-Shiley mitral valve prosthesis: localization of embolized disc by computerized axial tomography.

The case of a patient who survived strut fracture and embolization of a Björk-Shiley mitral prosthetic disc is presented. Prompt surgical treatment was directly responsible for survival. In addition, computerized axial tomography of the abdomen aided in localizing and retrieving the embolized disc, which was lodged at the origin of the superior mesenteric artery. A review of similar case reports from the literature supports our conclusions that the development of acute heart failure and absent or muffled prosthetic heart sounds in a patient with a Björk-Shiley prosthetic heart valve inserted prior to 1978 should raise the possibility of valve dysfunction and lead to early reoperation.

The Blalock-Taussig shunt in the first two years of life: a safe and effective procedure.

Many surgeons have been reluctant to perform Blalock shunts in patients who are in infancy or early childhood (less than 24 months old) and have done instead direct aortopulmonary anastomoses. Recently, others have advocated complete repair of tetralogy of Fallot in early infancy because of the high mortality of direct aortopulmonary shunts. We believe the Blalock-Taussig anastomosis is a safe and effective palliative procedure for all infants with inadequate pulmonary blood flow regardless of size. During the past nine years, 24 babies less than 2 years old who were followed had construction of Blalock-Taussig anastomosis for inadequate pulmonary blood flow. There were no operative deaths and no shunt-related late deaths. Of the 24 babies, 12 were less than 12 months old. Eighteen of the 24 had tetralogy of Fallot. The remaining 6 had a variety of lesions with inadequate pulmonary blood flow. The mean weight of the entire group was 7.3 +/- 1.6 kg. Of those infants less than 12 months old, the mean weight was 6.8 +/- 2.0 kg. More than 6 months following construction of the shunt, 2 babies died from sepsis unrelated to cardiovascular status. All infants had adequate but not excessive pulmonary blood flow after shunting. There were no late shunt failures.

Pericardial substitutes: delayed reexploration and findings.

Four patients' experience with two varieties of pericardial substitutes has been evaluated. Two patients received glutaraldehyde-preserved, formalin-fixed bovine bioprosthetic pericardial substitutes. These were associated with dense prosthesis-to-epicardium adhesions and the formation of a thick gelatinous peel. Two other patients received glutaraldehyde-preserved, ethanol-fixed bovine bioprosthetic pericardial substitutes. One patient had minimal prosthesis-to-epicardium adhesions, and the remaining patient demonstrated moderate prosthesis-to-epicardium adhesions with giant-cell and lymphocyte fibrosis. In all patients prosthesis-to-sternum adhesions were minimal. These observations suggest that careful washing is essential in all bioprosthetic implants to eliminate residual preservatives and fixatives. In addition, preservation in ethanol is associated with less prosthesis-epicardium reaction than is formalin preservation. Both products are successful in easing reentry, and no episode of infection has been associated with either prosthesis.

Transfemoral removal of a chronically implanted pacemaker lead: report of a case.

A transfemoral angiographic technique was used to remove a chronically implanted, infected pacemaker wire that could not be withdrawn by using direct traction. The case and a description of the technique are detailed, and the principles of nonsurgical extraction of chronically implanted pacemaker wires are discussed.

Recent experience with tuberculous pericarditis.

Twelve patients with tuberculous pericarditis were found among 1,194 patients with tuberculosis treated at the University of Texas Medical Branch over a 10-year period, an incidence of 1%. Surgical treatment was undertaken in 4 patients, and the rest were treated medically. The surgically treated patients had no major complications, and none of them died. In the medically treated group, however, 1 patient died, 1 had an anaerobic empyema, and 1 experienced respiratory arrest. In addition, the average hospital stay was 33 days less in the surgically treated group. Early surgical intervention should be carried out in patients with tuberculous pericarditis who do not respond promptly to adequate antituberculosis chemotherapy.

Intrapleural instillation of quinacrine for treatment of recurrent spontaneous pneumothorax.

We used intrapleural instillation of quinacrine hydrochloride in 20 patients (Group A) with recurrent spontaneous pneumothorax (one bilateral) and compared their clinical course with 19 patients who underwent thoracotomy and scarification or pleurectomy (Group B) and 63 patients treated by tube thoracostomy alone (Group C). In Group A, there was one complication of treatment, a pneumothorax immediately following tube removal, which necessitated repeat tube thoracostomy, and there was one late ipsilateral recurrence 2 years after treatment. These 20 patients with 21 recurrent spontaneous pneumothoraces treated with intrapleurally administered quinacrine have been followed for from 6 months to more than 4 years with only one late recurrence on the treated side. Eight patients in Group B had postoperative complications: 2 patients who had had pleurectomy required reoperation for postoperative bleeding; lobar pneumonia developed in 3; 1 had lack of total expansion of the lung; an intrathoracic hematoma developed in 1; and an ipsilateral pneumothorax necessitating tube thoracostomy developed in 1. In Group C, the rate of recurrence of pneumothorax was 23% during the first year following treatment. Intrapleural instillation of quinacrine is a simple, low-risk, reliable, and effective treatment for recurrent spontaneous pneumothorax, and is equally as effective as thoracotomy and scarification.

Preliminary evaluation of cocarboxylase on myocardial protection of the rat heart.

The presence of cocarboxylase (CC) is essential for the oxidation of pyruvate to acetylcoenzyme A (acetyl-CoA) and its subsequent degradation by means of the Krebs cycle. We compared the effects of various concentrations of CC in a cardioplegic solution on the survival and hemodynamic and metabolic recovery of 23 isolated, working rat hearts subjected to 60 minutes of hypothermic (23 degrees C) ischemic arrest. Group 1 (N = 6) consisted of hearts infused with the basic cardioplegic solution (Tyers' solution with glucose), to which no CC was added. In group 2 (N = 6) CC was added at 0.1 ml/L to the cardioplegic solution. In group 3 (N = 5) CC was added at 1 ml/L, and in group 4 (N = 6) CC was added at 10 ml/L. The cardioplegic infusions were performed at a pressure of 40 mm Hg for 2 minutes just before arrest; 30 minutes later they were performed again for 1 minute. Only two hearts (33.3%) recovered in group 1 whereas five recovered in group 2, five (100%) in group 3, and five (83.3%) in group 4. The recovery of hemodynamic performance as a percentage of preischemic control values showed marked improvement in the CC groups, especially group 3, when compared with group 1. The metabolic variables in the CC groups were also markedly improved, with significantly (p less than .05) decreased levels of tissue lactate and increased levels of creatine phosphate compared with those in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial injuries of the legs associated with fractures and dislocations.

Twenty-nine patients with vascular injuries of the leg associated with fractures and dislocations were reviewed. The overall limb salvage rate was 69 percent and the amputation rate 31 percent. These rates are usually directly related to delay in diagnosis and treatment. Routine arteriography is recommended in all patients with the slightest signs of ischemia. Prompt diagnosis followed by prompt vascular repair and fracture fixation will result in greater limb salvage.

Pericardiodiaphragmatic hernia.

Twenty-seven reported cases of pericardial diaphragmatic hernia are reviewed and another case is added. This entity may be congenital or traumatic in origin, the latter being more frequent at a ratio of 2:1. All patients except one were male and the mean age at diagnosis was 40 years. The patients were usually symptomatic, the most frequent complaints being of cardiac or respiratory origin. Pneumoperitoneum may be diagnostic although chest roentgenograms and contrast studies may suggest the diagnosis. Computed axial tomography and echocardiography may prove useful in the future. We believe the anterior abdominal approach is preferable to the transthoracic approach in reducing the hernia and repairing the defect because it affords better exposure and easier accessibility to other intraabdominal disease and can easily be converted into a median sternotomy if needed. The stomach and transverse colon became herniated most frequently and in only three cases was a sac found. The defect involves the central leaflet of the diaphragm and primary repair generally results in a good prognosis.

Carcinoma of the lung in patients under 40 years of age.

Bronchogenic carcinoma in the young population (40 years of age or less) is reported to present in an advanced stage and to have a virulent course. Between 1969 and 1979, 101 patients (65 men and 36 women) presented with cancer of the lung. Their mean age was 36.2 +/- 3.9 years (range 18 to 40 years). Eighty-seven percent had a history of cigarette smoking. Fifty percent of the patients had a strong familial history of malignancy of several organs. The interval between onset of symptoms and diagnosis was 4.01 +/- 3.48 months (3.56 +/- 3.34 for the surgically treated group and 4.16 +/- 3.53 for the nonoperated or unresectable group). Diagnosis was made at bronchoscopy in 32 patients, during thoracotomy in 30 patients, during nodal biopsy in 28 patients, and on cytologic examination of the sputum in 9 patients. The most common cell types were adenocarcinoma in 39 patients, squamous carcinoma in 29 patients, and oat cell carcinoma in 18 patients. Eighty-six patients (the majority) presented in stage III, whereas 9 were in stage I and 6 were in stage II. Twenty-seven patients (26.7 percent) underwent resection for cure, whereas 18 patients were inoperable at surgery. Eighteen of the surgical patients had adjuvant radiotherapy, and chemotherapy, immunotherapy, or both. The average length of survival for the nonresected patients was 7.12 +/- 5.9 months (range 1 to 36 months) and the actuarial survival was 1.5 percent at 36 months. The survival for the surgically managed patients was 56.1 +/- 52.6 months (range 3 to 168 months) or 48 percent at 36 months. At 46 to 168 months after treatment, the only survivors were 13 patients who were surgically managed. Stage III patients had longer survival after surgery (24.1 +/- 24.6 months to 7.09 +/- 5.90 months; range 3 to 74 months and 1 to 36 months, respectively). The survival at 5 years for patients with stage I disease was 78.8 percent, stage II disease 66.6 percent, and stage III disease, 3.6 percent. Early diagnosis and aggressive surgical management are necessary to improve the survival of patients with bronchogenic carcinoma under 40 years of age.

Obturator hernia: report of a case and brief review of its status.

The only case of obturator hernia in over 230,000 admissions is discussed. In the review of the recent English literature, a total of 30 cases, including our own, was collected. Characteristics of the condition were analyzed. The median age of the patients was 67 years; the majority were females in a ratio of 9:1 and both sides were equally affected. This entity occurs with the signs and symptoms of small bowel obstruction and, in almost one half of the patients, the pathognomonic Howship-Romberg sign.