Rectal cancer: prognostic indicators of long-term outcome in patients considered for surgery.

PURPOSE: Patients and clinicians seek an accurate prognosis after resectional surgery for rectal cancer. The aim of this study was to determine long-term outcomes after potentially curative surgery for rectal cancer with particular focus on factors associated with longer-term survival that are available to surgeons in the early post-operative setting. METHODS: We conducted a retrospective review of a prospectively gathered database of all primary rectal adenocarcinomas considered for surgery in the University Hospitals of Leicester National Health Service (NHS) Trust between 1998 and 2007. Survival was calculated using a Kaplan-Meier method. Factors thought to be associated with survival were subjected to univariate analysis followed by Cox proportion regression. RESULTS: One thousand and twelve patients with primary rectal adenocarcinoma diagnosed between 1998 and 2007 were identified. Eight hundred and fifty three patients did not have metastases at the time of presentation and 726 patients underwent major resectional surgery. Five-year survival was 66 %. Patients' age, Dukes' stage, UICC stage, nodal involvement and circumferential resection margin status were independently associated with long-term survival on multivariate analysis. CONCLUSION: This is one of the largest series of rectal cancers from a single NHS trust. We have demonstrated that age, Dukes' stage and CRM status are associated with long-term survival. These clinical factors are readily available to the surgeon at the time of first post-operative review and can provide a good clinical guide to prognosis.

Linkage analysis of glucokinase gene with NIDDM in Caucasian pedigrees.

NIDDM has a strong genetic component, as evidenced by the high level of concordance between identical twins. The nature of the genetic predisposition has remained largely unknown. Recently, the glucokinase gene locus on chromosome 7p has been shown to be linked to a subtype of NIDDM known as MODY in French and British pedigrees, and glucokinase mutations have been identified. To study the relationship between the glucokinase gene and NIDDM, we performed a linkage analysis in 12 Caucasian pedigrees ascertained through a proband with classical NIDDM. The LINKAGE program was used under four models, including autosomal dominant and recessive, with individuals with glucose intolerance counted as either affected or of unknown status. Linkage was significantly rejected with the dominant models (LOD scores -4.65, -4.25), and was unlikely with the recessive model when glucose intolerance was considered as affected (LOD score -1.38). These findings suggest that mutations in or near the glucokinase gene are unlikely to be the major cause of the inherited predisposition to NIDDM in Caucasian pedigrees, but do not exclude a role for this locus with a polygenic model, or a major role in some pedigrees.

Capillary and venous blood glucose measurements using a direct glucose-sensing meter.

The aim of the study was to evaluate the precision and accuracy of the ExacTech home blood glucose meter when used with either capillary or venous blood and to compare this with a reference whole blood glucose assay. Non-fasting glucose measurements were used since a validation study showed no capillary-venous differences between fasting and post-prandial states. In a cross-sectional study, blood was taken from 182 patients and measured in duplicate on three batches of strips. Altogether we analysed 1089 readings. The regression of the data from capillary blood samples (meter vs reference method) had a correlation coefficient, of 0.93, and a mean bias of 0.2 mmol l-1. The corrected 90% confidence interval was +/- 1.5 mmol l-1 overall, and +/- 0.9 mmol l-1 for readings under 7.0 mmol l-1. Regression of the data from venous blood samples (meter vs reference method) had a correlation coefficient of 0.93 and a slope of x 1.1. The corrected 90% confidence interval was +/- 1.7 mmol l-1. Thus venous blood may be used even though the meter is calibrated for capillary samples but the value must be corrected by dividing by 1.1. Error-grid analysis showed that day-to-day clinical decisions could be made on the basis of ExacTech readings, although a diagnosis of borderline diabetes may not be possible.

Dose-dependent increase in in vitro platelet sensitivity to adenosine-5'-diphosphate in young complication-free diabetic males.

In vitro platelet aggregation in response to a wide range of final adenosine-5'-diphosphate (ADP) concentrations was assessed in 11 young, diabetic males without detectable vascular complications and in 11 closely-matched controls. First phase aggregation was assessed using a particle collision theory model and the "sigmoid Emax" dose-response equation. Platelets from the diabetics required a significantly lower ADP concentration to attain a sticking probability of 0.2 (EC20; median [95% confidence limits]; 0.38 mumol/l ADP [0.25-0.52]) than those from the controls (0.55 mumol/l [0.28-0.67]; p = 0.016). At higher concentrations (EC50, EC80), there were no significant differences between the two groups (p greater than 0.05). Second phase aggregation, assessed from threshold for initiation of the release reaction, occurred at lower ADP concentrations in the diabetic group (2.0 mumol/l [1.2-4.4] vs 3.2 mumol/l [1.6-7.0]; p = 0.009). Consistent with the multistep nature of ADP-induced aggregation, these results indicate dose-dependent platelet function abnormalities in diabetics without vasculopathy. Enhanced reversible microaggregate formation (associated with platelet shape change) at low ADP concentrations may precede other first phase changes in early diabetes and would explain apparent inconsistencies in the results of previous studies involving similar subject groups.

An amperometric needle-type glucose sensor tested in rats and man.

An amperometric glucose-measuring 25 gauge (0.5 mm diameter) needle-type sensor has been developed using a glucose oxidase and dimethyl ferrocene paste behind a semi-permeable membrane situated over a window in the needle. Electron transfer results in direct current generation. Sensors have been tested subcutaneously in the abdomen both in anaesthetized rats (40 sensors, 11 rats) and in normal, conscious man (20 sensors, 10 subjects). In rats the blood glucose was modulated by glucose and by insulin infusion. In man the glucose concentrations were rapidly changed by use of a glucose clamp at 12 mmol/l plasma concentration for 2 h, after which the glucose returned to normal. In rats the median correlation between glucose change was 0.83 with an interquartile range from 0.70 to 0.92, and in man the median correlation was 0.80 with an interquartile range 0.67 to 0.86. Hysteresis, a measure of the accuracy on the upswing and downswing, was not a problem and cross-correlation showed no phase-lag. There were quantitative differences between in vitro calibration and the performance in vivo, reflecting the different conditions of use. The current in response to a glucose concentration was stable over 6.0 h in rats and 4.5 h in man.

Normal calcium-activated potassium channel in red cells in type 2 diabetes.

The diminished insulin secretion of type 2 diabetes might result from abnormal regulation of the potassium permeability which leads to beta-cell depolarization. The possibility of a generalized defect has been investigated in vitro by the stimulation of 86Rb efflux from red cells of type 2 diabetic patients by calcium ionophore and its inhibition by quinine. Diabetic subjects and control subjects had identical 86Rb efflux stimulated by 0.2-0.6 microM calcium ionophore A23187 and identical inhibition by quinine with mean Ki 6 microM and 4 microM quinine respectively for 0.2 microM ionophore and mean Ki 38 microM and 37 microM quinine respectively for 0.6 microM ionophore.

Determinants of ADP-induced platelet aggregation in diabetes mellitus.

ADP-induced platelet aggregation was measured in 15 Type 1 (insulin-dependent) diabetic patients, 15 Type 2 (non-insulin-dependent) diabetic patients and in 15 non-diabetic control subjects. Simultaneous measurements were made of fasting blood glucose, glycosylated haemoglobin, serum insulin, total plasma cholesterol, cholesterol in the lipoprotein subfractions, total triglycerides and platelet phospholipid fatty acid levels. Regression analysis of aggregation against the biochemical variables within the three groups revealed that there was no significant difference in the associations with aggregation between the groups. When the data was pooled, blood glucose (p less than 0.01) and glycosylated haemoglobin (p less than 0.05) demonstrated significant associations with aggregation. Multiple regression analysis was then applied; only blood glucose (p less than 0.05) had an independent effect on aggregation. Platelet aggregation in diabetic patients and non-diabetic patients appears to be related directly only to blood glucose levels.

Platelet aggregation in non-insulin-dependent diabetes is associated with platelet fatty acids.

Platelet aggregation was measured in 15 patients having non-insulin-dependent diabetes mellitus (NIDDM) at the time of diagnosis and after three months of dietary treatment. Mean fasting plasma glucose fell from 13.0 to 8.8 mmol/l (p less than 0.0002), glycosylated haemoglobin fell from a mean of 11.3% to 9.0% (p less than 0.005) and insulin levels fell from a mean of 17.5 to 13.8 mU/l (p less than 0.005). Platelet aggregation showed a variable response and did not correlate with plasma glucose, glycosylated haemoglobin or plasma insulin. Multiple linear regression analysis was carried out on the aggregation values against the biochemical variables and platelet phospholipid fatty acid levels following logarithm transformation. Platelet linolenic acid and eicosapentaenoic acid levels were significantly inversely associated with aggregation but the difference between the relationship at diagnosis and after three months was not statistically significant. The association between platelet omega 3 fatty acids and platelet aggregation suggest that dietary change aimed at increasing the proportions of these fatty acids might favourably influence vascular disease in NIDDM via an effect on platelet function.

Glycosylated haemoglobin: comparison of five different methods, including measurement on capillary blood samples.

Glycosylated haemoglobin was measured in venous blood samples and in blood collected in 'Unistep' bottles by isoelectric focusing (IEF), as the reference method, and by electroendosmosis (EEO), the thiobarbituric acid method (TBA), ion-exchange chromatography (IEC) and affinity chromatography (AC). Isoelectric focusing, electroendosmosis and thiobarbituric acid gave similar results. Affinity chromatography gave lower results than isoelectric focusing for normal values but similar results for diabetics. Ion-exchange chromatography gave 24% lower results than isoelectric focusing across the range. Using Unistep collected blood samples and comparing multiple samples from the same patient, electroendosmosis gave the best results (coefficient of variation 4%) and thiobarbituric acid gave slightly less good precision that other methods. Re-use of affinity chromatography columns gave less good precision. Collection of blood samples into a Unistep bottle gave similar results to venous sample results. Storage of venous capillary blood samples in Unistep bottles over 1 week at 21 degrees C gave similar results to immediate assay. Electroendosmosis of blood samples in Unistep bottles gave stable results over 2 weeks. Home collection by a patient of a capillary blood sample into a Unistep bottle allows glycosylated haemoglobin results to be available when seen in the clinic.

Continuous infusion of glucose with model assessment: measurement of insulin resistance and beta-cell function in man.

Continuous infusion of glucose with model assessment (CIGMA) is a new method of assessing glucose tolerance, insulin resistance and beta-cell function. It consists of a continuous glucose infusion 5 mg glucose/kg ideal body weight per min for 60 min, with measurement of plasma glucose and insulin concentrations. These are similar to postprandial levels, change slowly, and depend on the dynamic interaction between the insulin produced and its effect on glucose turnover. The concentrations can be interpreted using a mathematical model of glucose and insulin homeostasis to assess insulin resistance and beta-cell function. In 23 subjects (12 normal and 11 with Type 2 (non-insulin-dependent diabetes) the insulin resistance measured by CIGMA correlated with that measured independently by euglycaemic clamp (Rs = 0.87, p less than 0.0001). With normal insulin resistance defined as 1, the median resistance in normal subjects was 1.35 by CIGMA and 1.39 by clamp, and in diabetic patients 4.0 by CIGMA and 3.96 by clamp. In 21 subjects (10 normal and 11 Type 2 diabetic) the beta-cell function measured by CIGMA correlated with steady-state plasma insulin levels during hyperglycaemic clamp at 10 mmol/l (Rs = 0.64, p less than 0.002). The CIGMA coefficient of variability was 21% for resistance and 19% for beta-cell function. CIGMA is a simple, non-labour-intensive method for assessing insulin resistance and beta-cell function in normal and Type 2 diabetic subjects who do not have glycosuria during the test.

Platelet sensitivity in vitro to adenosine-5'-diphosphate and prostacyclin and diabetic retinopathy.

Platelet sensitivity to adenosine diphosphate and prostacyclin in diabetes has been assessed using collision theory and the concept of 'sticking probability' (the probability of particle union). Twenty Type 1 (insulin-dependent) diabetic men (10 with no or minimal retinopathy and a matched group of 10 with proliferative retinopathy) and 10 age-matched nondiabetic men were studied. Platelets from the 20 diabetic patients required, on average, 37% less adenosine diphosphate to achieve a sticking probability of 0.5 (ED50) compared with platelets from the non-diabetic subjects (medians 1.50 and 0.95 mumol/l, respectively; p less than 0.01). The platelet prostacyclin response was assessed by the dissociation constant (Ki) for inhibition of adenosine diphosphate-induced aggregation. Platelets from the diabetic patients had similar prostacyclin sensitivity to those from the non-diabetic subjects (medians 0.42 and 0.42 respectively). Diabetic patients with and without retinopathy had similar platelet sensitivity to both adenosine diphosphate and prostacyclin.

Patient-orientated metered capillary blood collection.

A small collector bottle, with a precision-moulded top, allows capillary blood from a finger-prick to be automatically metered into a diluent for subsequent laboratory analysis. This device, which has been successfully used by patients to obtain full blood counts, glycosylated haemoglobin values and blood glucose measurements, may have wide application.

Prostaglandin synthesis inhibition reduces platelet aggregation in diabetes mellitus.

Platelet aggregation, platelet prostaglandin precursor fatty acids, glycaemia and lipid levels were studied in a group of insulin dependent diabetics whilst taking Aspirin (900 mg daily) and Dipyridamole (300 mg daily) and again two months after discontinuing this treatment.

Analysis of platelet aggregation using particle collision theory.

The aggregometer monitors changes in light transmission through stirred suspensions of aggregation platelets. Arbitrary measurements from aggregometer recorder tracings have been used to investigate platelet aggregation without regard to mechanisms involved. To determine the applicability of particle collision theory to assessment of in vitro platelet sensitivity to proaggregating agents, platelet-rich plasma (PRP) from five volunteers was used to obtain recorder tracings after addition of ADP in five doses (0.4-4.0 mumol/l PRP) to aliquots of PRP stirred and incubated in an aggregometer. Using the equation describing light transmission through particulate suspensions, particle collision theory, and s (the probability of particle union after collision), a subject- and dose-independent relationship between aggregation rate (dn/dt) and particle number (n) at the recorder tracing inflection point was found (dn/dt = -k X s X n1.56, where k is a constant dependent on particle size and speed and on the proportion of unreactive particles). Determinations of mean particle size at the tracing inflection point indicated that k was also dose independent. Dose-response curves of ADP added vs. s could therefore be constructed. This methodology provides conveniently obtainable quantitative information concerning in vitro platelet "stickiness."

Islet changes induced by hyperglycemia in rats. Effect of insulin or chlorpropamide therapy.

To investigate the effect of hyperglycemia on normal islets, rats were made diabetic by a 95% partial pancreatectomy and treated with insulin, saline, or chlorpropamide for 3 mo. Histologic examination and morphometry of the residual pancreas showed islet enlargement and fibrosis that correlated with the mean lasting plasma glucose during the experimental period. Treatment of diabetes with insulin prevented the islet disorganization. The B-cell area per islet remained constant and was not affected by hyperglycemia. Chlorpropamide had little effect on the fasting plasma glucose or islet structure, and no "beta cytotrophic" effect was seen. Chronic hyperglycemia induces islet damage that may affect residual B-cell function in diabetes.

In-vitro venous prostacyclin production, plasma 6-keto-prostaglandin F1 alpha concentrations, and diabetic retinopathy.

Previous studies have shown that vessels from diabetics produce less prostacyclin in vitro than those from normal controls. To determine whether this decreased production is related to complications elective biopsy of a superficial forearm vein was performed on 12 insulin-dependent male diabetics, six with nil or minimal and six with proliferative retinopathy, and seven male controls. Vein segments from the diabetics and controls produced similar amounts of prostacyclin in vitro (medians 0.11 and 0.19 ng/mg tissue respectively), but the segments from the diabetics with nil or minimal retinopathy produced less than those from the diabetics with proliferative retinopathy (medians 0.09 and 0.18 ng/mg respectively). Preoperative plasma immunoreactive concentrations of 6-keto-prostaglandin F1 alpha were not significantly different between the controls and the diabetics (medians 101 and 116 pg/ml respectively). In a separate study, however, 11 diabetics with duration of disease of over 10 years and nil or minimal retinopathy had significantly lower concentrations than a matched group of 16 with background or proliferative retinopathy (medians 79 and 121 pg/ml respectively). These results do not support an association between reduced prostacyclin production and diabetic retinopathy.