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Biomedical subjects

S Stewart

Publications and source records attributed to S Stewart.

At least 235 records · Page 13Linked to original sources
PubMed1989

Long-term stepwise sustained improvement in left ventricular ejection fraction after myocardial infarction.

Radionuclide left ventricular ejection fraction, end-diastolic volume, and exercise capacity were determined in 34 selected patients who survived a first Q wave anterior infarction. Patients were included in the study if they had no subsequent cardiac events (unstable angina or myocardial infarction) during the average follow-up period of 47 months (range = 36 to 70 months); none was treated with thrombolysis, coronary angioplasty, or bypass grafting. Overall, mean left ventricular ejection fraction increased from 28 +/- 10% 1 month after infarction to 33 +/- 10% at 3 years (p less than 0.01); mean end-diastolic volume decreased from 217 +/- 99 ml to 171 +/- 80 ml (p less than 0.002). Stepwise improvement in left ventricular ejection fraction occurred in 15 of these patients (group B) and was associated with a significant increase in exercise capacity. Mean ejection fraction in group B was 26 +/- 7% at 1 month and 41 +/- 10% at 3 years (p less than 0.001). In all of these patients there was improved regional wall motion in the noninfarct zone, whereas five patients also showed improvement in the infarct zone. The results indicate a progressive improvement in left ventricular function that occurs over time in some patients after first Q wave anterior infarction, independent of intervention.

Adult↗
PubMed1989

Heart-lung transplantation at Papworth Hospital.

Combined heart-lung transplantation has been performed in 51 patients since 1984. A pulmonary preservation fluid preceded by prostacyclin infusion has allowed distant procurement. Early organ function has been good in all cases. Maintenance immunosuppression is cyclosporine and azathioprine. Steroids are given to treat rejection episodes. Transbronchial biopsy has allowed the accurate, early and safe diagnosis of rejection. Acute cardiac rejection has not occurred in these patients. Thirty-seven patients are alive between 1 and 54 months following transplantation. The actuarial survival at 1 year is 76% and 68% at 2 years. Four patients died in the early postoperative period as a result of primary Cytomegalovirus (CMV). Other causes of early death were bacterial infection (4), cerebrovascular event (1), tracheal dehiscence (1) and small bowel infarction following retransplantation for obliterative bronchiolitis. Three other patients have died as a result of obliterative bronchiolitis. Patients and donors have been carefully selected to ensure that this scarce resource is utilised most effectively.

Adolescent↗
PubMed1989

Identification and sequence analysis of a gene encoding gp67, an abundant envelope glycoprotein of the baculovirus Autographa californica nuclear polyhedrosis virus.

Monoclonal antibodies with specificity for the abundant envelope surface glycoprotein (gp67) of Autographa californica nuclear polyhedrosis virus (AcMNPV) were used to screen a lambda gt11 expression library of AcMNPV DNA fragments. The gp67 gene was mapped to the left end of the EcoRI H fragment in a right-to-left orientation on the consensus map of AcMNPV. A 2.1-kilobase transcript which hybridized to the region was first detected in cell extracts at 2 h postinfection; it peaked in abundance at 18 h postinfection and thereafter was present at lower levels. The nucleotide sequence of the region was determined, and a 1,590-nucleotide open reading frame flanked by an AT-rich sequence was identified that could encode a polypeptide with 529 amino acid residues (molecular mass of 60,167 daltons). Computer analysis indicated that the peptide possesses two hydrophobic regions near the N and C termini as well as six potential N-linked glycosylation sites. We suggest that following cleavage of a signal peptide, the polypeptide undergoes further processing and becomes anchored at its C terminus in the virus envelope. The final seven amino acid residues at the C terminus contain basic amino acids and may have a role in virion assembly.

Amino Acid Sequence↗
PubMed1989

Toxoplasmosis in heart and heart and lung transplant recipients.

Of the first 250 heart and 35 heart and lung transplant recipients at Papworth Hospital, Cambridge, who survived for more than one month after transplantation, 217 heart and 33 heart and lung patients were investigated serologically for evidence of Toxoplasma gondii infection. Six patients acquired primary T gondii infection, most probably from the donor organ. Five patients experienced T gondii recrudescence, two of whom had recovered from primary infection a few years earlier. Two patients died from primary T gondii infection and the severity of symptoms in the other patients with primary infection was related to the amount of immunosuppressive treatment. Prophylaxis with pyrimethamine (25 mg a day for six weeks) was introduced for T gondii antibody negative transplant recipients who received a heart from a T gondii antibody positive donor after the first four cases of primary toxoplasmosis. Of the seven patients not given pyrimethamine, four (57%) acquired primary T gondii infection. This compared with two of the 14 patients (14%) given prophylaxis.

Adult↗
PubMed1989

Lung rejection and bronchial hyperresponsiveness to methacholine and ultrasonically nebulized distilled water in heart-lung transplantation patients.

Acute denervation of the lungs occurs after heart-lung transplantation (HLT), affecting both afferent and efferent nerves below the tracheal anastomosis. After surgery, the carina and main bronchi are perfused by mediastinal collaterals derived from the coronary arteries, and the intrapulmonary airways by retrograde blood flow from pulmonary artery collaterals. During acute rejection, the lungs are subjected to inflammation, particularly perivascular lymphocytic infiltrates. Rejection can be diagnosed by transbronchial biopsy (TBB). We report the bronchial responses to inhaled methacholine and ultrasonically nebulized distilled water (USNDW) in 16 HLT patients 2 wk to 43 months after surgery, relating them to the lung histopathology from concurrent TBB. Methacholine bronchial hyperresponsiveness was common, but it was not associated with airway epithelial or submucosal inflammation or perivascular lymphocytic infiltration. Six patients had a modest response to USNDW (fall in FEV1 greater than 10%). The responsiveness to USNDW was not associated with enhanced methacholine responsiveness or epithelial and mucosal inflammation. However, it was more commonly seen in patients with lung rejection and perivascular infiltrates. Methacholine hyperresponsiveness in HLT patients could therefore reflect denervation hypersensitivity of airway smooth muscle muscarinic receptors. The modest response to USNDW in some patients cannot be a result of a vagal reflex but could reflect a pathologic vascular response associated with lung rejection. These observations offer insight into the possible mechanisms of bronchial hyperresponsiveness in disease.

Adult↗
PubMed1989

The radiographic appearances of infection and acute rejection of the lung after heart-lung transplantation.

Thirty-two patients underwent combined heart and lung transplantation at Papworth Hospital between 1984 and 1987. The clinical and physiologic observations made at the time of episodes of infection and rejection together with the histopathology of lung tissue obtained by transbronchial lung biopsy were compared with pre- and postepisode chest radiographs. There were 45 episodes of rejection in 20 patients: 23 episodes during the first month after transplantation, and 22 after 1 month. Twenty-six episodes of infection occurred in 15 patients. The causative organisms included Aspergillus fumigatus, cytomegalovirus (CMV), herpes simplex, Pneumocystis carinii, and Staphylococcus aureus. When an abnormal chest radiograph is common during the first month after transplantation during acute rejection (74%), it may alternatively be due to lung infection (most commonly CMV pneumonitis). The chest radiograph during this period provides a useful indication for transbronchial biopsy and bronchial lavage. The chest radiograph is abnormal in the minority (23%) of episodes of rejection occurring later than 1 month after transplantation. Pulmonary function tests (FEV1 and VC) offered a more useful indication for transbronchial biopsy during this period.

Adolescent↗
PubMed1989

Airway mucosal bioelectric potential difference in cystic fibrosis after lung transplantation.

Bioelectrical potential difference (PD) across the respiratory mucosa is raised in cystic fibrosis (CF). We have recorded airway potentials from seven patients with CF who had undergone heart-lung transplantation and from eight patients without CF who had had transplants for cardiovascular disease; comparison of these populations controls for the effects of denervation and immunosuppressive treatment. Six patients without CF who had not had transplants formed an additional control. PD was recorded during routine fiberoptic bronchoscopy, using a Ringer's-perfused exploring bridge connected across a high impedance amplifier to an intravenous reference bridge. Bronchial lavage and sputum culture revealed no evidence of infection. Bronchial PD was similar in all three groups of patients at equivalent sites. However, nasal PD was raised in the CF group (mean value, 44 mV +/- 3.9 SE) compared with the patients who had transplants for cardiovascular disease (mean, 18 mV +/- 1.1 SE), and the control patients (mean, 15 mV +/- 1.2 SE). We conclude that the epithelial defects that result in raised airway potentials in CF do not recur in the transplanted lung.

Adolescent↗
PubMed1988

Heart-lung transplantation for cystic fibrosis.

13 patients with severe lung disease and cor pulmonale from cystic fibrosis were accepted for heart-lung transplantation (HLT). 6 have had the operation, of whom 5 are well, with normal lung function, 3-29 months after operation. 1 patient died from adult respiratory distress syndrome after reoperation to control persistent chest-wall bleeding: at necropsy, this patient proved to have cirrhosis. Respiratory tract infections and acute lung rejection after HLT for cystic fibrosis were no more common than in other HLT patients. Of the 7 patients for whom suitable donor organs were not found, 3 died within 3 months of assessment. Initial severity of disease had been similar to that in the transplant group. The cost of assessment, operation, and 1 year's treatment after HLT is similar to that of medical treatment for such patients.

Adult↗
PubMed1988

Antibody-guided diagnosis and therapy of malignant lesions.

Tumour associated monoclonal antibodies (MAbs) HMFG1, HMFG2 and H17E2, labelled with 123iodine or 111indium, were used to detect primary and metastatic cancer by external body scintigraphy in patients with ovarian, breast and non-small cell lung cancer (NSCC). Successful localisation was seen in all patients with primary and 80% of the metastatic NSCC, 50% of primary and 70% of metastatic breast cancer lesions and in 80% of patients with metastatic ovarian cancer. On the other hand, imaging carried with a radiolabelled non-specific MAb produced positive results in 3 out of 5 cases with primary NSCC. Therefore, non-specific imaging should be further studied in clinical research for the evaluation of the specificity of radioimmunodetection. A therapeutic procedure which has shown promise is that of intracavity administration of radiolabelled antibodies. Twenty-nine patients with resistant ovarian cancer have been treated with intraperitoneal 131I-labelled MAbs (HMFG1, HMFG2, AUA1, H17E2). There were no significant responses in 8 patients with gross disease. There were 2 responses in 15 assessable patients with tumour nodules of less than 2 cm in diameter. Out of 6 patients with microscopic disease, 4 are disease-free with follow-up time of 6-40 months (mean = 17.5 months).

Adult↗