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Biomedical subjects

J T Jenkins

Publications and source records attributed to J T Jenkins.

17 recordsLinked to original sources
PubMed2007

Malignant disease in peptic ulcer surgery patients after long term follow-up: a cohort study of 1992 patients.

AIMS: To assess the effect of previous peptic ulcer surgery on subsequent malignant events, in particular in relation to previous vagotomy, a historical cohort study was conducted. METHODS: All patients undergoing surgery for peptic ulcer disease with accurate follow-up data at a large peptic ulcer clinic in the Western Infirmary, Glasgow, from 1965 to 1983 were assessed. All cancer events and specific cancer events (gastric, bronchial, laryngeal, colorectal, bladder, breast, prostate, pancreas, kidney, oesophageal cancers) were determined as outcome measures and expressed as standardised incidence ratio (SIR). RESULTS: Vagotomy and drainage accounted for 67% of all procedures for peptic ulcer disease. Eighty-three percent were habitual smokers. For all peptic ulcer surgery patients, the SIR for all cancer events was 0.86. For specific cancers, the SIRs were bronchial cancer (SIR 1.13); laryngeal cancer (SIR 2.17), colorectal cancer (SIR 0.67). For vagotomised patients the risk of gastric cancer was significantly elevated (SIR 1.50). CONCLUSIONS: An excess of cancers attributable to smoking have been found in peptic ulcer surgery patients. Vagotomised patients have a higher risk of gastric cancer after long term follow-up. This finding may have implications for screening and the safety of long term acid suppression with agents such as proton pump inhibitors.

Bronchial Neoplasms↗
PubMed2006

Prospective study of laparoscopic adjustable gastric banding in the west of Scotland.

UNLABELLED: Obesity is an increasing problem in Scotland and Laparoscopic Adjustable Gastric Bands (LAGB) are an effective method of weight reduction. Most outcome data are reported from high volume units with extensive experience or dedicated bariatric practice. We aimed to assess an experienced laparoscopic surgeon's outcome working outwith a dedicated bariatric practice in the west of Scotland. METHODS: All LAGB procedures performed by a single surgeon were prospectively assessed from 1997 to 2004. LAGB were inserted using pars flaccida approach. Patient selection was based on BMI >35 or significant obesity related co-morbidities. Outcomes included percentage excess weight loss (%EWL) and excess BMI loss (EBL). We assessed total operating time to assess the learning curve for LAGB placement. RESULTS: 125 patients were assessed (107 F:18 M). 123 patients were in regular follow-up (98%). Median age was 44 years (range 25-63). Mean follow-up was 34 months (range 11-91). Median initial BMI was 49 (range 37-73). 31% were BMI 35-45, 36% were BMI 45-50 and 33% were BMI>50. %EWL at 1,3 and 5 years was 45, 58 and 74, respectively. EBL at 1, 3 and 5 years was 11.7, 16.1, and 21.7, respectively. Complications included 4 converted procedures, 1 failed band insertion after conversion and re-operation for removal in five. Eight patients had tubing access port problems requiring intervention. The median overall total operation time was 80 minutes (range 50 - 160). CONCLUSIONS: In this cohort LAGB insertion by an experienced laparoscopic surgeon is safe with few re-operations. Satisfactory weight loss is obtained and patient compliance with follow-up is high.

Adult↗
PubMed2005

Membrane elasticity in giant vesicles with fluid phase coexistence.

Biological membranes are known to contain compositional heterogeneities, often termed rafts, with distinguishable composition and function, and these heterogeneities participate in vigorous transport processes. Membrane lipid phase coexistence is expected to modulate these processes through the differing mechanical properties of the bulk domains and line tension at phase boundaries. In this contribution, we compare the predictions from a shape theory derived for vesicles with fluid phase coexistence to the geometry of giant unilamellar vesicles with coexisting liquid-disordered (L(d)) and liquid-ordered (L(o)) phases. We find a bending modulus for the L(o) phase higher than that of the L(d) phase and a saddle-splay (Gauss) modulus difference with the Gauss modulus of the L(o) phase being more negative than the L(d) phase. The Gauss modulus critically influences membrane processes that change topology, such as vesicle fission or fusion, and could therefore be of significant biological relevance in heterogeneous membranes. Our observations of experimental vesicle geometries being modulated by Gaussian curvature moduli differences confirm the prediction by the theory of Juelicher and Lipowsky.

Biomechanical Phenomena↗
PubMed2005

A technically difficult endorectal ultrasound is more likely to be inaccurate.

OBJECTIVE: Endorectal ultrasound (ERUS) is well established as an accurate modality for local staging of rectal tumours. The aim of this study was to identify reasons for inaccurate staging of tumours, and to assess whether difficulties encountered during scanning are likely to influence accuracy. PATIENTS AND METHODS: ERUS was performed by a single operator using a 10 MHz rigid instrument. One hundred and seventeen patients that had both ERUS and surgery are included in this study (patients that had pre-operative radiotherapy were excluded). During ERUS, procedural conditions and limiting factors were recorded. Data was collected prospectively. RESULTS: In 78 (66.7%) patients no technical difficulty was encountered during ERUS. In this group accuracy was 80% for T-stage and 77% for N-stage. Specific reasons for inaccuracy identified in this group were: inflammatory lymph nodes (from a tumour associated abscess and a colovesical fistula) and deep biopsy causing a submucosal defect with intramural haemorrhage in benign lesions (2 cases). In the remaining 39 (33.3%), the following problems were encountered: stenotic lesions (23), patient discomfort (8), poor bowel preparation (6), and scarring from previous surgery (2). In 11 patients from this group, the scan was considered inconclusive and no stage could be determined. For the other 28, the accuracy for T-stage was 68% and for N-stage 67%. CONCLUSION: A technically difficult ERUS is likely to give an inconclusive or inaccurate result for both T-stage (P = 0.001) and N-stage (P = 0.003). In this situation a repeat scan may be considered (where appropriate). Alternatively, further assessment by MRI or flexible endoscopic ultrasound may be considered.

Aged↗
PubMed2004

The incremental response of random aggregates of identical round particles.

This paper is concerned with a dense, randomly packed, granular material that consists of identical spheres or disks with elastic, frictional interactions, that is first isotropically compressed and subsequently loaded along an arbitrary stress path. An analytical relationship between the overall stress and strain increments is determined for the pre-failure regime. The purpose of the modelling is to understand how this relation depends upon the features of the packing and the particle interactions. From the outset it is recognised that the packing and interactive properties for these materials may vary substantially from grain to grain and the heterogeneity introduced in this manner is fully accounted for. Moment equilibrium equations are solved for each particle and force equilibrium equations are solved for each neighbourhood. Then, the heterogeneity of the aggregate is taken into account by introducing means and fluctuations in the description of the local deformations and the measures of the particles and interactions. The general development is illustrated with an example in two dimensions in which the packing and contact interactions are approximated by angular distributions and the heterogeneity is introduced by variations in these. For an isotropic medium with constant contact stiffnesses the theory provides predictions that compare well with results obtained from numerical simulations.

Journal Article↗
PubMed2002

Segregation in binary mixtures under gravity.

We employ kinetic theory for a binary mixture to study segregation by size and/or mass in a gravitational field. Simple segregation criteria are obtained for spheres and disks that are supported by numerical simulations.

Journal Article↗
PubMed2000

Secondary causes of intestinal obstruction: rigorous preoperative evaluation is required.

The clinical presentation, management and outcome of patients with small intestinal and large bowel obstruction unrelated to adhesive or primary colonic neoplastic disease is not well described. The aim of this study was to determine the clinical presentation, evaluation, operative management, and outcome in patients with secondary causes of intestinal obstruction. The medical records of 200 patients who underwent an operation for intestinal obstruction from January 1995 through December 1997 were reviewed. Seventy-three patients (37%) had secondary causes of intestinal obstruction, and these records were reviewed in detail. The cohort included 37 men and 36 women with a mean age of 52 +/- 2 years. The etiology of intestinal obstruction was metastatic neoplastic obstruction (19%), colonic volvulus (18%), Crohn's disease (14%), herniae (11%), diverticular disease (7%), and miscellaneous causes (31%). Six patients (8%) had intestinal motor disorders and a misdiagnosis of intestinal obstruction. The clinical presentation of patients with secondary causes of obstruction was similar to typical patients with adhesive small bowel obstruction. Preoperative evaluation included frequent use of CT (42%), but intestinal contrast studies were used in 13 (18%) patients only. Two-thirds of the patients required an intestinal resection, and 50 per cent of the patients with a misdiagnosis had a nontherapeutic celiotomy. Operative mortality and morbidity were 3 per cent and 48 per cent, respectively, and 15 per cent of patients required reoperation. Suspected intestinal obstruction from secondary causes requires rigorous preoperative evaluation with liberal use of intestinal contrast examinations to avoid misdiagnosis, operative complications, and reoperations.

Adolescent↗
PubMed1997

Vascular remodelling in intramyocardial resistance vessels in hypertensive human cardiac transplant recipients.

OBJECTIVE: Cardiac transplant recipients often develop hypertension as a side effect of immunosuppressive treatment. The aim of this study was to use the serial endomyocardial biopsies taken to monitor rejection to study the early and sequential arterial changes in human myocardial resistance arteries as hypertension develops. METHODS: At least 14 biopsies were studied from each of 23 patients, divided into a normotensive group (12 patients with a diastolic pressure never greater than 90 mm Hg) and a hypertensive group (11 patients with more than 10% of diastolic pressure measurements above 100 mm Hg). Morphometric analysis of between 30 and 50 arteries and arterioles in two widely separated histological levels from each biopsy was undertaken using an Optomax image analyser. RESULTS: There was a correlation between blood pressure, particularly diastolic pressure, and rate of medial thickening of intramyocardial coronary resistance arteries and arterioles (P = 0.0025). There was also a correlation between serum cyclosporin A concentrations and mean artery wall thickness (P = 0.003). CONCLUSIONS: Hypertension and cyclosporin A treatment are associated with significant wall thickening of intramyocardial resistance vessels in cardiac allograft recipients. These changes may be functionally and clinically important.

Arterioles↗
PubMed1984

Thermal fluctuations of large cylindrical phospholipid vesicles.

The time correlation function of the shape fluctuations of large (greater than 10 micron), cylindrical, hydrated, phospholipid-membrane vesicles consisting of one bimolecular layer was measured. The restoring force of the membrane was due to the excess curvature of a membrane element. A value for the curvature elastic modulus, Kc, was obtained from the mean-square amplitude of the normal modes of the fluctuations using the equipartition theorem. An expression for the correlation time was found by solving the dynamics of the membrane's relaxation against the low Reynolds number viscous drag of the surrounding fluid. The amplitudes and correlation times of the fundamental bending mode of the cylindrical vesicles both yield Kc = 1-2 X 10(-12) ergs.

Biophysical Phenomena↗
PubMed1984

The distribution of pressure behind a soft contact lens.

We determine the pressure distribution behind a soft contact lens that is necessary to keep the lens in conformity with an axisymmetric substrate. The substrate consists of two regions: a central portion, the cornea, supposed to be an ellipsoid; and a peripheral region, the sclera, taken to be a sphere. The pressure is obtained as part of a numerical solution of the axisymmetric equilibrium equations for an initially curved, linearly elastic membrane. The relaxed shape of the lens is assumed to be an axisymmetric ellipsoid with a central curvature and a shape factor different from those of the cornea. The variation in the thickness of the lens from its center to edge is approximated by a polynomial. Pressure distributions are obtained for several typical soft contact lens fittings.

Biomechanical Phenomena↗
PubMed1980

Maturation of calcium transport in the rat small and large intestine.

Using an in vivo perfusion technique we compared transport of calcium in segments of the proximal (duodenum + jejunum) and distal (ileum) small intestine and in the cecum + colon of suckling (2-week old), weanling (3-week-old) and adolescent (6-week-old) rats. The concentration of calcium (Ca) in the isotonic sodium chloride solution perfused through the intestinal segments was either below (0.4 and 1.4 mmoles/1) or above (3.2 mmoles/1) serum ionized calcium. In the suckling rat, in all three intestinal segments, the relationship between transport rate (mumoles/hr per g wet weight) and luminal Ca concentration was linear. Net secretion occurred when luminal Ca concentration was below serum ionized Ca, and net absorption at 3.2 mmoles/l luminal Ca. In the weanling rats the relationship between luminal Ca concentration and transport rate was curvilinear for all segments. In the adolescent rats the relationship was curvilinear in the proximal segment and linear in the distal segment and in the cecum + colon. Rates of transport in segments of the suckling rats were several fold greater than corresponding rates in the adolescent rats. The change in the relationship between transport rate and luminal Ca suggested that the mode of transport of Ca changes at the time of weaning from mainly a passive mechanism in the suckling period to mainly a carrier mediated mechanism in the adolescent rats.

Animals↗
PubMed1977

Static equilibrium configurations of a model red blood cell.

The membrane of the red blood cell is modeled as a fluid shell which resists bending and changes in area. The differential equations governing the mechanical equilibrium of such a membrane are derived and axisymmetric solutions are obtained numerically.

Biomechanical Phenomena↗