Search PubMed⌕ Search

Biomedical subjects

M M Thompson

Publications and source records attributed to M M Thompson.

At least 109 records · Page 6Linked to original sources
PubMed1997

TUR syndrome and endoscopic transanal resection: no evidence for a clinically important association in 38 procedures.

BACKGROUND: The TUR syndrome is well described after transurethral resection of the prostate. Endoscopic transanal resection (ETAR) is increasingly used to remove rectal lesions. METHODS: A prospective study of 38 ETARs in 21 patients was carried out over 2 years. Each patient was observed for symptoms and signs of TUR syndrome, and each had serial venous blood sampling and subsequent biochemical and haematological analysis during the perioperative period. RESULTS: No symptoms or signs typical of TUR syndrome were recorded. However, analysis of the biochemical variables using the Kruskal-Wallis one-way analysis of variance showed that there were statistically significant (P < 0.05) subclinical changes during the 24 h following the procedure affecting levels of serum sodium, potassium, total protein, albumin, lactate dehydrogenase, glycine, ammonia and serum osmolality. CONCLUSION: The changes in the electrolyte concentrations, although statistically significant, were not of the same magnitude as described previously in the TUR syndrome. The risk of a TUR-type syndrome in ETAR is small and serial blood tests, as detailed above, may safely be omitted.

Adenoma↗
PubMed1997

Career aspirations and expectations of vascular trainees in 1996. The Rouleaux Club.

Sub-specialisation within general surgery has now become accepted as part of surgical training and consultant posts are being increasingly advertised for surgeons with a special interest. Transplantation surgery is currently losing trainees and proposals have been made to combine vascular and transplant surgery to a greater or lesser degree. The Rouleaux Club is a society for junior vascular surgeons in Great Britain and Ireland. Questionnaires were sent to 78 non-consultant members in July 1996 and 67 were returned and analysed. A reasonable cross-section of all training grades was obtained. Of this number 44 (65.7 per cent) did not want to spend any period of their higher surgical training in full-time transplantation training, although 32 (47.8 per cent) would accept some time in transplantation training if it were combined with another surgical specialty. Training in vascular access work was welcomed by 51 (76.1 per cent) but this contrasts with 40 (59.7 per cent) who would not want to offer this as a service once appointed to consultancy. Almost all of the trainees (60/64 = 93.8 per cent) ideally wanted to be appointed to consultant posts with > 50 per cent commitment to vascular surgery and most thought that they would realistically get such positions. Most trainees ideally wanted consultancies in academic/ university departments or teaching hospitals but many thought that in reality they would be appointed to posts in district general hospitals.

Attitude of Health Personnel↗
PubMed1996

Endovascular repair of abdominal aortic aneurysm: an initial experience.

Endovascular repair of abdominal aortic aneurysm (AAA) was attempted in ten patients over a 12-month period. Median age was 72 (range 61-82) years and median AAA diameter was 5.5 (range 5.2-6.0) cm. An aortoaortic (tube) graft was used in seven patients and a tapered aortoiliac reconstruction in three. There were two failures requiring conversion to open repair. Additional procedures included iliac artery angioplasty (two), coil embolization of an associated common iliac aneurysm (one) and femorodistal bypass (one). Median operating time was 162 (range 95-270) min and median blood loss was 1200 (range 800-2000) ml. Median hospital stay was 9 (range 5-21) days. Complications included death (one), reversible acute tubular necrosis (one) and prolonged ventilation (one). Postoperative evaluation with duplex ultrasonography and computed tomography demonstrated three perigraft leaks (two proximal and one distal). It is concluded that endovascular repair of AAA is feasible but is associated with significant complications and requires careful evaluation before widespread use.

Aged↗
PubMed1996

Elastase-induced matrix degradation in arterial organ cultures: an in vitro model of aneurysmal disease.

PURPOSE: Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, induction of endogenous metalloproteinases (MMPs), and development of a chronic inflammatory infiltrate. Despite intensive analysis of end-stage tissue, aneurysm pathogenesis remains obscure. The aim of this study was to develop an in vitro model of aneurysmal disease. METHODS: Porcine aortic organ cultures were preincubated with pancreatic elastase before culture in standard conditions for up to 14 days. The extent of matrix degradation at various time points was determined by quantitative histologic estimation of collagen and elastin concentration. Endogenous metalloproteinase production within the tissue was quantified by gel enzymography and immunoblotting. A separate series of experiments was performed to investigate the effect of incorporating autologous leukocytes into the culture system. RESULTS: Although exogenous elastase was removed after 24 hours, substantial degradation of the aortic extracellular matrix occurred in the subsequent 13 days in tissue culture. Analysis of samples preincubated with elastase (100 U/ml) for 24 hours before tissue culture demonstrated that elastin degradation occurred in a time-dependent manner (p < 0.001) and was not confined to the initial phase of exogenous elastase activity. Gelatin gel enzymography revealed a time-related production of metalloproteinases (55 to 250 kDa) within the aortic tissue. The presence of MMPs-1, 2, 3, and 9 was determined by immunoblotting. Immunohistochemistry identified the vascular smooth-muscle cell as the source of MMPs-1, 2, and 3. Addition of autogenous leukocytes to elastase-pretreated tissue initiated an inflammatory infiltrate within the aortic wall, which further enhanced both matrix degradation and MMP production (p < 0.001). CONCLUSIONS: These data demonstrate that aortic samples pretreated with elastase before tissue culture undergo matrix degradation with MMP production and the development of an inflammatory infiltrate. These changes mirror the pathophysiological events within established aneurysms. It is suggested that this model may be useful in understanding early pathogenic events within aneurysmal tissue.

Animals↗
PubMed1996

Angiogenesis in abdominal aortic aneurysms.

OBJECTIVES: To determine the degree of neovascularisation in the wall of abdominal aortic aneurysms in comparison to atherosclerotic control aortas, and to correlate the angiogenic response with the extent of the cellular inflammatory infiltrate. DESIGN: Histopathological study. MATERIALS: Aortic samples were obtained from patients with abdominal aortic aneurysms and from atherosclerotic controls. METHODS: Samples were stained with haematoxylin and eosin, and Miller's elastin and Van Gieson stain, EVG, and a monoclonal antibody specific to human endothelial cells. Within the aortic wall three histological regions were defined, the media, the adventitia and a transition zone. The number of capillary like, thin walled vessels were measured in each region, and the cellular infiltrate was quantified. RESULTS: The number of newly formed vessels was increased in all layers of aneurysmal wall in comparison to control samples (p<0.001). The degree of neovascularisation correlated with the extent of the inflammatory infiltrate (rs=0.45, p<0.01). CONCLUSIONS: This study demonstrated that abdominal aortic aneurysms are associated with a marked angiogenic response, which is related to the degree of inflammation within the aortic wall. It is hypothesised that anti-angiogenic agents may play a role in the medical management of aortic aneurysmal disease.

Aged↗
PubMed1996

Oxygen free radical and cytokine generation during endovascular and conventional aneurysm repair.

OBJECTIVES: Endovascular aneurysm repair has been proposed as a "minimally invasive" alternative to conventional aneurysm resection. One of the most important potential benefits of endoluminal surgery is the avoidance of aortic cross clamping, which may attenuate the ischaemia-reperfusion injury that complicates open aneurysm repair. This study aimed to quantify the metabolic response to both conventional and endovascular aortic surgery. DESIGN: Prospective clinical study. SETTING: University hospital. METHODS: Femoral vein blood samples (pre-clamp, during aneurysm repair and 5 and 30 min post reperfusion) were obtained from 12 patients undergoing aortoaortic aneurysm repair, six by conventional transperitoneal inlay replacement (median age 71 years, median aneurysm diameter 5.8 cm), and six by endoluminal deployment of a straight endograft (median age 73 years, median aneurysm diameter 5.5 cm). All endovascular procedures were completed satisfactorily with no conversions to conventional surgery. OUTCOME MEASURES: Venous blood samples were analysed for oxygen free radical (OFR) production using the quantifiable oxidation of IgG in plasma, and cytokine (IL-1 beta and TNF-alpha) generation by radioimmunoassay. [table: see text] RESULTS: The results are given as median values with interquartile ranges: CONCLUSIONS: These results suggest that the ischaemia-reperfusion response associated with conventional aneurysm surgery may be largely negated by endovascular techniques. This may have significant consequences as the generation of oxygen free radicals and cytokines have been implicated in the development of systemic organ failure following aortic surgery.

Aged↗
PubMed1996

Sidestream smoke inhalation decreases respiratory clearance of 99mTc-DTPA acutely.

BACKGROUND: The permeability of the alveolar-capillary barrier to an inhaled aerosol of technetium 99m labelled diethylenetriamine penta-acetate (99mTc-DTPA) is used as an index of alveolar epithelial injury. Permeability is greatly increased in active smokers. AIMS: To determine the effect of sidestream smoke inhalation on permeability as this has not been described previously. METHODS: We measured lung clearance of inhaled 99mTc-DTPA aerosol in 20 normal non-smoking subjects before and after exposure to one hour's sidestream smoke inhalation. RESULTS: Measured carbon monoxide (CO) levels rose to maximum of 23.5 +/- 6.2 ppm (mean +/- SD) from baseline values of 0.6 +/- 1.3 (p < 0.001) and plasma cotinine levels to a maximum of 9.5 +/- 4.5 nmol/L (mean +/- SD). The half time (T1/2 in minutes) for 99mTc-DTPA clearance rose from baseline 69.1 +/- 15.6 (mean +/- SD) to 77.4 +/- 17.8 (p < 0.05) after smoke exposure. No effect of 99mTc-DTPA scanning or of sidestream smoke was demonstrated on lung function. CONCLUSIONS: We conclude that low level sidestream smoke inhalation decreases 99mTc-DTPA clearance acutely in humans. The mechanism of this unexpected result is not established but may include differences in constituents between sidestream and mainstream smoke, alterations in pulmonary microvascular blood flow, or changes in surfactant due to an acute phase irritant response.

Adult↗
PubMed1996

Enhanced renal sensitivity to angiotensin actions in diabetes mellitus in the rat.

The renin-angiotensin system (RAS) has been implicated in the pathogenesis of diabetic nephropathy. In diabetes, renal RAS components are dysregulated, potentially increasing renal RAS effects. To explore the renal RAS, studies were conducted in control and diabetic rats. In both groups, intravenous angiotensin (ANG) I and ANG II produced similar increases in mean arterial pressure (MAP). In contrast, glomerular filtration rate defined only in diabetic rats. Renal plasma flow fell in both groups but decreased more in diabetic rats. Additional groups were given the same dose of ANG I directly into the left renal artery, and hemodynamics were studied in the treated and untreated kidneys. In contrast to the intravenous studies, intra-arterial ANG I had no effect on MAP in either group. The renal hemodynamic effects were similar to those in intravenous studies. Additionally, diabetic rats exhibited enhanced hemodynamic sensitivity in the untreated kidney, suggesting that renal effects could occur at nonpressor concentrations of circulating ANG II. Thus renal (but not systemic) responsiveness to angiotensins is enhanced in diabetic rats.

Angiotensin I↗
PubMed1996

Proximal stent deployment without contrast during endovascular aneurysm repair: an improved technique.

PURPOSE: To describe a technique to enhance stent visibility on the fluoroscopic monitor during aortic endograft deployment. TECHNIQUE: To assist in accurate positioning and deployment of the proximal stent in a Parodi-type aortic endograft, the stent is affixed to the balloon so that the radiopaque marker sits at the stent's distal end. When the device is in position and the sheath is retracted, the stent and the radiopaque balloon markers are clearly seen on the fluoroscopic image. Using normal saline only to inflate the balloon allows the stent to remain visible throughout deployment. CONCLUSIONS: The use of saline rather than contrast medium for balloon inflation provides continuous visualization of the stent during expansion, thus facilitating accurate deployment and early recognition of balloon migration within the stent.

Angioplasty, Balloon↗
PubMed1996

Methylmalonic acid quantification by stable isotope dilution gas chromatography-mass spectrometry from filter paper urine samples.

A specific method for quantification of methylmalonic acid (MMA) from urine samples dried onto filter paper is described. The method involves stable isotope dilution gas chromatography-mass spectrometry with [methyl-2H3]-MMA as the internal standard. MMA is stable in dry paper samples stored at room temperature for at least 2 weeks. The extraction efficiency of MMA from paper was 56-58%. The concentration of urinary MMA in dried filter paper specimens from 190 normal controls was 1.21 +/- 1.34 (mean +/- SD) mmol/mol of urinary creatinine. Age-related reference values are also reported. The concentrations, normalized to the urinary creatinine concentration, decrease with age. The applicability of this method to rapid screening for cobalamin (vitamin B12)-related disorders and methylmalonic aciduria is demonstrated.

Adolescent↗
PubMed1995

Angiotensin II-induced hypertrophy of rat vascular smooth muscle is associated with increased 18 S rRNA synthesis and phosphorylation of the rRNA transcription factor, upstream binding factor.

Hypertrophy of vascular smooth muscle cells (VSMC) is an important adaptive response of hypertension. Drug intervention studies have implicated a role for angiotensin II (A-II) in the mediation of VSMC hypertrophy in vivo, and A-II is a potent hypertrophic agent for VSMC in culture. Our laboratory has previously shown that A-II-induced hypertrophy of cultured VSMC is due in part to generalized increases in protein synthesis and increased content of rRNA. The aim of the present study was to determine if A-II stimulates rRNA gene synthesis and whether the rRNA transcription factor, upstream binding factor (UBF), is involved. Nuclear run-on analysis demonstrated that A-II induced a greater than 5-fold increase in rRNA gene synthesis within 6 h of stimulation. A-II also stimulated a rapid increase in UBF phosphorylation as well as nucleolar localization, but no changes in the content of UBF. Phosphoamino acid analysis showed that phosphorylation occurred only on serine residue(s). Results demonstrate that increased transcription of ribosomal DNA contributes to the A-II-induced increase in protein synthesis and VSMC hypertrophy, and suggest that an important regulatory event in this pathway may be the phosphorylation and/or nucleolar localization of UBF.

Angiotensin II↗
PubMed1995

Percutaneous transluminal angioplasty for lower-limb critical ischaemia.

Percutaneous transluminal angioplasty (PTA) alone was used to treat 54 (23 per cent) of 232 lower limbs with critical ischaemia. Technical success was achieved in 49 cases (91 per cent) with an immediate symptomatic improvement in 47 (87 per cent). There was no death or limb loss attributable to PTA and three embolic complications were successfully treated by percutaneous aspiration. Symptomatic improvement and haemodynamic patency rates at 24 months were 77 and 78 per cent respectively; 27 of 34 limbs with ulceration or gangrene had healed with minor surgery by a median of 7.5 (range 3.0-18.0) months. Patient survival and limb salvage rates at the same time interval were 76 and 89 per cent respectively. These results demonstrate that, for a selected group of patients with lower-limb critical ischaemia, PTA can be a highly successful therapeutic option with a low associated morbidity.

Aged↗
PubMed1995

Trends in abdominal aortic aneurysms: a 13 year review.

AIM: To assess changing trends of abdominal aortic aneurysms 1979-1991. DESIGN: Retrospective study from the Leicestershire Health Authority. RESULTS: 727 patients with abdominal aortic aneurysm were treated. Of these 56.4% were admitted for elective repair and 43.6% presented with rupture. There was a significant increase in the number of ruptured aortic aneurysms over this period despite an increase in the number of elective repairs. The overall 30-day mortality of elective repair (including patients with symptomatic but non-ruptured aneurysms) was 8.8%. The overall 30-day mortality of ruptured aneurysms (including patients who were deemed medically too unfit for surgery) was 57.7%. There has been no significant change in elective and ruptured mortality over the study period. There was a significant increase in the median age of patients (69.5 yrs in 1979 to 74 yrs in 1991). CONCLUSION: The increasing incidence of abdominal aortic aneurysms may reflect better diagnostic methods, greater clinical awareness of the condition and increase in the proportion of elderly people in the population.

Adult↗