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Biomedical subjects

M S Alexander

Publications and source records attributed to M S Alexander.

At least 19 recordsLinked to original sources
PubMed1992

Impaired left lower lobe ventilation in patients with cardiomegaly. An isotope study of mechanisms.

Reduced left lower lobe ventilation (V) in patients with enlarged hearts has been commonly observed on routine isotope ventilation-perfusion lung scanning, and there is evidence to show that this reduction is dependent on posture. Clinically, it may have a role in posture-dependent dyspnea and postoperative left lower lobe changes in cardiomegaly. Previous studies have shown improvement in left lower lobe V in the prone compared with the supine position. In 11 patients showing this phenomenon in krypton 81m V scanning, a mean relative reduction in V of 53 percent occurred at the left base. No significant change in perfusion or in the signal from preinjected technetium 99m macroaggregated albumin was observed between the two positions. No significant change in ventilatory turnover (measured with intravenous xenon 133) was seen either, suggesting that no air trapping takes place. By combining the data from the intravenous 133Xe (which gives the ratio, V/lung volume) and continuously inhaled 81mKr (which reflects regional V), an index of relative volume between the two sides was derived and shown to be significantly reduced at the left base on moving from the prone to supine positions (a mean reduction of 40 percent; p less than 0.02 by Wilcoxon signed rank test). Thus, the mechanism of postural left lower lobe hypoventilation in cardiomegaly is predominantly a regional loss of alveolar volume.

Cardiomegaly↗
PubMed1991

The use of radionuclide imaging in the evaluation of suspected biliary damage during laparoscopic cholecystectomy.

Laparoscopic cholecystectomy offers a reliable and effective alternative to the standard operative cholecystectomy with reduced morbidity and patient recovery time. We report three cases in which radionuclide hepatobiliary imaging was utilized to evaluate the integrity of the extrahepatic biliary ducts following suspected biliary damage during the procedure, documenting bile leakage in two of the patients.

Adult↗
PubMed1990

Incidence of pulmonary embolism in elderly patients newly admitted to an acute geriatric unit: a prospective study.

To study the incidence of pulmonary embolism (PE) in elderly patients newly admitted to an acute geriatric unit, the authors carried out ventilation perfusion scans on 33 patients, 25 women and 8 men, mean age 79 years, consecutively admitted to the geriatric wards. The first scan was done within 5 days of admission and repeated between days 10 and 20. Where possible, patients with a positive second scan had a repeat scan at 2-3 months. Six (18%) patients were found to have a high probability of PE, 4 (12%) at the time of admission and two (6%) after admission. Three patients (9%) were considered to suffer from chronic pulmonary artery disease. Mortality was 5 for the whole group (15%) and 1 of 6 (17%) with a high probability of PE; this patient was suffering from carcinomatosis. The only patient who was anticoagulated suffered serious side effects. In no patient was PE clinically suspected. The authors conclude that PE is common in sick elderly patients newly admitted to acute geriatric wards, that rehabilitation with mobilization may precipitate new PE, and that nonanticoagulated PE does not seem to appreciably shorten the prognosis for life. Treatment with anticoagulants may be more dangerous than not treating PE in this older age group.

Aged↗
PubMed1989

Dysphagia after fast neutron therapy to the head and neck.

Nine patients presenting with dysphagia following successful treatment for head and neck cancer with neutron radiotherapy are reviewed. Combined clinical and videofluoroscopic investigation is used to analyse their deficits and provide indications for management. All patients show impairment of both the oral and pharyngeal phases of the swallow, with the exception of one subject who shows signs of focal neurological damage. It is suggested that fibrosis is the underlying cause of dysphagia in the remainder.

Adult↗
PubMed1986

Spontaneous subarachnoid hemorrhage and negative cerebral panangiography. Review of 140 cases.

One hundred and forty consecutive patients who sustained proven spontaneous subarachnoid hemorrhage (SAH) with negative cerebral panangiography were studied retrospectively. Attention was directed to the presence, amount, and distribution of subarachnoid blood on computerized tomography (CT) scans. It was determined that the finding of blood on CT had a significant association with clinical grade, loss of consciousness, ventricular ratio, fixed ischemic deficit, and total of all complications, but not with epilepsy, hypertension (previously known or detected on admission), treated hydrocephalus, rebleeding, angiographic spasm, and eventual outcome (which was generally excellent on follow-up examination). The distribution of blood, predominantly around the basal cisterns, suggests leakage from ventriculostriate and thalamoperforating vessels as the cause of SAH, and closer study of these vessels is suggested.

Adolescent↗
PubMed1985

Interspecies variation in ritodrine metabolism.

The metabolism of ritodrine has been studied in the rat, both in vitro and in vivo, and in the in vivo pregnant baboon, with the use of tritium-labeled drug as a probe. Combined enzymatic degradation and radiochromatography of the radioactive components of bile and urine show that ritodrine undergoes significant Phase l metabolism in addition to conjugation to both sulfate and glucuronide, as previously reported. The presence of more than one conjugate is shown, and evidence for major interspecies variation in patterns of metabolism and conjugation is presented, with comments on the applicability of results to human clinical use.

Animals↗
PubMed1985

Metabolism and disposition of ritodrine in a pregnant baboon.

Relatively little is known about the detailed metabolism of ritodrine. The aim of this study was to examine ritodrine metabolism and pharmacokinetics in the maternal and fetal baboon. A fetal-maternal model was made with use of Papio anubis at 144 days of gestation. Tritiated ritodrine was injected as an intravenous bolus into the mother. Maternal and fetal blood samples, amniotic fluid, and maternal urine were collected at time intervals. Samples were analyzed by a combination of high-pressure liquid chromatography and radiochromatography. Conjugated metabolites were recovered and characterized by cleavage studies with use of beta-glucuronidase and sulfatase. The distribution half-life of ritodrine in the mother was 6 minutes and the elimination half-life was 61 minutes. Metabolites were found in both fetal serum and amniotic fluid. The concentrations of ritodrine and its metabolites in fetal serum were at or above the concentrations in maternal serum at 2 hours after maternal intravenous injection. The principal metabolite identified was the sulfate conjugate. The fetus appears to accumulate metabolites. These data indicate that ritodrine crosses the placenta and, in the baboon, achieves levels in the fetus equal to or higher than those in the mother.

Amniotic Fluid↗
PubMed1979

Reliability of a schedule for rating personality disorders.

The inter-situational, inter-rater and temporal reliability of a schedule for rating personality disorders is described. In an initial study with a simplified form of the schedule in patients from different wards of a psychiatric hospital inter-situational reliability between raters was higher for patients with personality disorders than with no personality disorder. Using the full schedule, inter-rater reliability, using audiotaped and separate interviews, and temporal reliability at interviews conducted a mean of 12.5 months apart all reached a satisfactory level, suggesting that the schedule may be a useful instrument for measuring deviant personality traits. The interview may be used with a subject or an informant but agreement between ratings made with informants and psychiatric patients during illness was low, and the schedule is not recommended for use with patients alone during acute episodes of illness.

Humans↗
PubMed1976

Hernia through the foramen of Winslow.

This is a report of a hernia through the foramen of Winslow in which the right half of the colon was herniated. It was gangrenous and perforated. Following hemicolectomy the patient recovered.

Aged↗