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Biomedical subjects

M A Long

Publications and source records attributed to M A Long.

At least 19 recordsLinked to original sources
PubMed2004

Strong coupling of nonlinear electronic and biological oscillators: reaching the "amplitude death" regime.

Interaction between an electronic and a biological circuit has been investigated for a pair of electrically connected nonlinear oscillators, with a spontaneously oscillating olivary neuron as the single-cell biological element. By varying the coupling strength between the oscillators, we observe a range of behaviors predicted by model calculations, including a reversible low-energy dissipation "amplitude death" where the oscillations in the coupled system cease entirely.

Animals↗
PubMed2003

Treatment of mesothelioma in Bloemfontein, South Africa.

OBJECTIVE: Two different surgical methods for treating mesothelioma (pleurectomy and pleuro pneumonectomy) were reviewed. METHODS: This was a retrospective study from 1976 to 2001. Forty-six patients, aged 35-80 years, received one of the following procedures: pleurectomy (n=29), or pleuro pneumonectomy (n=17). Pleurectomy was indicated in symptomatic patients with pain or pleural effusion while pleuro pneumonectomy was indicated in patients with Butchart stage I or II disease and an acceptable cardiopulmonary reserve. Patients received either chemotherapy, radiation, or in combination after surgery. RESULTS: The mortality rate was 3.8% for pleurectomy patients and 5.8% for pleuro pneumonectomy patients. The median survival rate for pleurectomy patients was 9 months, and 12 months for pleuro pneumonectomy patients. Pleuro pneumonectomy patients experienced less morbidity and had a shorter hospital stay than pleurectomy patients. CONCLUSIONS: Improved survival was obtained with both procedures. Morbidity was higher in the patients who underwent pleurectomy. Important prognostic factors include tumor stage, tumor histology, duration of symptoms, and weight loss or pain as a presenting symptom. Patients with a low tumor stage, epithelial histology, absence of pain or weight loss, and a longer onset of symptoms had the best survival rate. A trend towards improved survival in patients undergoing pleuro pneumonectomy and receiving radiation as adjuvant therapy was observed.

Adult↗
PubMed2003

True acquired left ventricular aneurysms in childhood.

AIM: True left ventricular aneurysms are rarely encountered in childhood. Etiological factors are varied and often indeterminable. There is a paucity of literature detailing the surgical techniques used to repair pediatric aneurysms. METHODS: Three children aged 21 months, 19 months and 5 years with true left ventricular aneurysms underwent surgical repair in our unit. The clinical details, surgical technique, histological review, hospital outcome and short term follow-up is discussed. RESULTS: Two patients underwent repair of their aneurysms by means of the Cooley endoaneurysmorraphy technique, and 1 patient underwent repair using the aneurysm resection and linear plication technique. Histological examination revealed tuberculosis to be the etiological factor in one patient, while a non-specific vasculitis was present in the other 2 patients. Immediate postoperative course was uneventful and all 3 patients were discharged from hospital within one week. Two patients were recatheterized during follow-up visits. All patients were asymptomatic at 1 year follow-up. Echocardiography demonstrated good left ventricular function with disappearance of preoperative mitral regurgitation. CONCLUSION: Pediatric left ventricular aneurysms may be successfully repaired using standard operative techniques. These techniques render excellent short-term RESULTS: Longer follow-up is needed to fully evaluate the outcome of these children.

Cardiac Surgical Procedures↗
PubMed1999

Features of unusual metastases from prostate cancer.

A retrospective study of CT examinations on 508 patients with prostate carcinoma was performed in order to document the presence or absence of uncommon nodal and extranodal metastases according to pre-defined criteria. 45 atypical metastases were demonstrated in 36 patients. There were 23 atypical nodal metastases including unusual distribution (19/23), large volume (7/23) and atypical morphology or contrast enhancement pattern (8/23). 22 atypical extranodal metastases included orbit/skull base (11), pulmonary (4), liver (3), intracranial (2), ocular (1) and adrenal (1). Atypical prostate carcinoma metastases are usually encountered in the presence of known advanced disease but can be the presenting feature of malignancy or the only sign of distant spread. Knowledge of atypical manifestations of metastatic disease will reduce diagnostic delay, allow accurate staging and lead to the effective and timely delivery of appropriate treatment.

Adult↗
PubMed1997

Evaluation by magnetic resonance imaging of the inferior vena cava in patients with non-seminomatous germ cell tumours of the testis metastatic to the retroperitoneum.

OBJECTIVE: To assess the role of magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) in evaluating suspected occlusion of the inferior vena cava (i.v.c.) in patients with abdominal nodal metastases from non-seminomatous germ cell tumours, thus giving information that may be helpful in planning surgery and for determining the need for anticoagulant therapy. PATIENTS AND METHODS: Five patients with abdominal nodal metastases in whom occlusion of the i.v.c. was suspected on computed tomography (CT) were imaged using a 1.5 T MRI scanner. The MRI findings were compared with those from CT. RESULTS: The MR images successfully and clearly detected partial and total occlusions of the i.v.c. by both intraluminal thrombus and extrinsic compression. The technique also clearly detected extensive collateral venous circulation in several cases and in one a cavernous transformation of the i.v.c. In all patients, the MRI studies provided better information than that from CT. CONCLUSION: MRI, and particularly MRA, is a comparatively new technique that is non-invasive and offers the potential of evaluating vascular structures with no need for ionizing radiation or contrast media. This technique, if available, should be chosen for imaging the i.v.c. in patients suspected of having compression or occlusion of the i.v.c.

Adolescent↗
PubMed1995

Ruptured abdominal aortic aneurysms--prognostic indicators and complications affecting mortality. A local experience.

Although elective abdominal aortic aneurysm (AAA) repair can be done with a less than 5% mortality rate, ruptured AAAs have a 32-85% mortality rate. The aims of this study were: (i) to identify prognostic factors affecting mortality; (ii) to identify and assess the impact of postoperative complications on mortality; and (iii) to try to identify a subgroup of patients who would not benefit from surgery. The records of 54 patients presenting with ruptured AAAs were reviewed; 49 of these patients were operated on, 43 of them males and 6 females (mean age 67 years). The operative mortality rate was 44%, most patients who died doing so in the intensive care unit. In 14 cases AAA was diagnosed before rupture--6 of these patients died. Factors that had a significant effect on mortality were: (i) associated ischaemic heart disease--83% of these patients died postoperatively; (ii) the degree of shock on admission--66% of patients with a blood pressure on admission of 85 mmHg or less died; and (iii) the number of postoperative complications per patients--those with 2 or more complications had an 83% mortality rate. Factors that did not correlate statistically with mortality were age, time interval to surgery, volume and composition of intra-operative fluid therapy, and length of surgery. The most important correctable error was failure to operate electively. From the factors assessed it was not possible clearly to identify a subgroup of patients in this study who should have been excluded from surgery.

Aged↗
PubMed1995

A study of dental anxiety in a Belfast population.

BACKGROUND AND DESIGN: This study was undertaken to assess the levels and behavioural consequences of dental anxiety in a Belfast population. Fear is associated with poor attendance, leading to neglect and so Northern Ireland, with the highest caries rate in the United Kingdom, seemed a good place to examine dental anxiety and its relation to dental health status. A questionnaire was used to examine the prevalence and accompanying effects of dental anxiety. The results were statistically analysed.

Adolescent↗
PubMed1994

An evaluation of the antirhinoviral activity of acetylfuran replacements for 3-methylisoxazoles. Are 2-acetylfurans bioisosteres for 3-methylisoxazoles?

As a probe of the 3-methylisoxazole portion of our broad-spectrum antipicornaviral series, a panel of 2-acetylfuran analogues was prepared as replacements for the 3-methylisoxazole ring. Comparison of the two series showed remarkable similarity in potency, spectrum of activity, logP, and electrostatic parameters. X-ray studies of 21b bound to human rhinovirus-14 showed that the 2-acetyl group adopted a syn conformation and the carbonyl oxygen acts as a hydrogen bond acceptor with ASN219 in much the same way as the nitrogen of the isoxazole. The importance of the syn conformation and the hydrogen-bonding capability was confirmed by the reduced antiviral activity of the 2-methylfuran and 2-formylfuran analogues. From the results of this study, it is apparent that the syn-2-acetylfuran ring is acting as a bioisostere for the 3-methylisoxazole.

Antiviral Agents↗
PubMed1994

Oxadiazoles as ester bioisosteric replacements in compounds related to disoxaril. Antirhinovirus activity.

A series of 1,2,4-oxadiazoles has been prepared as ester bioisosteres and tested against 15 human rhinovirus serotypes, and the MIC80, the concentration which inhibits 80% or 12 of the serotypes tested, was determined. Homologation of the alkyl group attached to the oxadiazole ring resulted in a reduction in activity with increased chain length. Introduction of hydrophilic groups in this position rendered the compounds inactive. Increasing the length of the side chain attached to the isoxazole ring resulted in an increase in activity. Replacement of the methyl with alkoxyalkyl substituents retained activity; however, introduction of a hydroxyl group on to the side chain reduced activity. Compound 8a, where both the isoxazole and oxadiazole rings were substituted with methyl groups, was one of the most active compounds in the series. A comparison was made between 8a and the two isomeric oxadiazoles 41 and 46, and an attempt was made to explain the difference in activity by examining electrostatic potential maps and by an energy profiling study. No conclusive results were obtained from these studies.

Antiviral Agents↗
PubMed1994

Structural characterization of the micelle-vesicle transition in lecithin-bile salt solutions.

Small-angle neutron scattering (SANS) and dynamic light scattering (QLS) are used to characterize the aggregates found upon dilution of mixed lecithin-bile salt micelles. Molar ratios of lecithin (L) to taurocholate (TC) studied varied from 0.1 to 1, and one series contained cholesterol (Ch). Mixed aggregates of L and taurodeoxycholate (TDC) at ratios of 0.4 and 1 were also examined. In all cases the micelles are cylindrical or globular and elongate upon dilution. The radius of the mixed micelles varies only slightly with the overall composition of lecithin and bile salt which indicates that the composition of the cylindrical micelle body is nearly constant. The transition from micelles to vesicles is a smooth transformation involving a region where micelles and vesicles coexist. SANS measurements are more sensitive to the presence of two aggregate populations than QLS. Beyond the coexistence region the vesicle size and degree of polydispersity decrease with dilution. Incorporation of a small amount of cholesterol in the lipid mixture does not affect the sequence of observed aggregate structures.

Bile Acids and Salts↗
PubMed1994

Case report: multiple intra-cranial metastases from a prolactin-secreting pituitary tumour.

Only seven cases of metastatic prolactin-secreting pituitary tumour have been reported in world literature. The metastases were intra-cranial in five cases and extra-cranial in two cases. We report a further case with multiple intra-cranial metastases in the supra-tentorial compartment. Histologically, both primary and metastatic tumours were benign with strongly positive immuno-histochemical staining for prolactin. Our case exemplifies the inconsistent correlation between the histopathological appearance and biological behaviour of malignant pituitary tumours.

Aged↗
PubMed1993

Case report: the transabdominal ultrasound appearances of a colovesical fistula.

When the clinical manifestations of colovesical fistulae lack diagnostic features, significant diagnostic delay may result. The literature contains conflicting recommendations regarding the optimal method of imaging such fistulae. We describe the transabdominal ultrasound appearances of a colovesical fistula and review the relevant literature. The identification of the ureteric orifices with their associated urinary jets and the use of abdominal compression are essential components of the technique.

Aged↗
PubMed1992

Renal artery embolization with ethanol and gelfoam for the treatment of ureteric fistulae with one year follow-up.

Two patients with ureteric fistulae who were unfit for reconstructive surgery were treated by renal ablation using intra-arterial ethanol, gelfoam fragments and in one case coils. In both cases the fistulae dried-up on the same day and both patients are well and normotensive a year later. Our conclusion is that renal ablation by arterial embolization with ethanol can be a valuable alternative to surgery to treat ureteric fistulae in patients who are poor surgical risks.

Embolization, Therapeutic↗
PubMed1986

Outpatient treatment of hyperemesis gravidarum with stimulus control and imagery procedures.

Hyperemesis gravidarum is a frequent illness among women in their first trimester of pregnancy. This study evaluated the use of an outpatient behavioral approach to treat hyperemesis in four women. The subjects, all health care professionals, were treated with stimulus control and imagery procedures in an A-B design, with follow-up. The results demonstrated the clinical effectiveness of outpatient behavioral treatment procedures in the management of mild/moderate hyperemesis gravidarum.

Adult↗
PubMed1979

Cystic fibrosis and malnutrition.

Cystic fibrosis as a specific disease entity has been known to be associated with malnutrition for almost half a century. The importance of the malnutrition in the disease process remains unknown, as does much information about specific nutritional deficiencies in CF. Supplements for children with CF should include extra energy as fat or carbohydrate, a form of linoleic acid that can be absorbed, hydrolyzed protein, fat-soluble vitamins with vitamins A and E in a water emulsion, vitamin B12, probably B vitamins and vitamin C, and trace minerals. Routine measurements of nutritional status, particularly in children with growth failure, should be made at regular intervals and should include a three-day diet record and a simultaneous 72-hour stool fat determination. If fat malabsorption is not controlled by pancreatic enzymes, the use of antacids or cimetidine should be considered. The true role of nutrition in patients with CF will not be known until the appropriate studies are completed.

Cystic Fibrosis↗