Treating dyslipidaemia in the setting of diabetes mellitus and cardiovascular disease: a less commonly perceived therapeutic perspective in clinical practice.

Diabetes mellitus and cardiovascular disease are being managed more belligerently in recent times, with multifactorial cardiovascular risk reduction being the focus of therapeutic interventions. We review some of the caveats to be exercised in the treatment of these patients that are pertinent to clinicians in daily clinical practice.

An assessment of the coverage of a district-wide diabetic retinopathy screening service.

AIMS: To assess the coverage of the diabetes retinopathy screening service (DRSS) in North Staffordshire, to identify patient characteristies associated with non-attendance and to assess the proportion of patients with diabetic retinopathy who achieved glycaemic and blood pressure (BP) control targets. METHODS: Data for all patients who underwent annual retinal screening between 1 May 2000 and 30 April 2001 were obtained from the North Staffordshire Diabetes Register. Age, gender, ethnicity, socio-economic status, type and duration of diabetes were compared between patients who underwent eye screening and those who did not. Frequencies of patients who achieved glycaemic and BP targets in these groups of patients were compared to the remaining patients. RESULTS: 5646 of the 11682 (48%) patients on the diabetes register underwent retinal screening during the year. Patients with Type 2 diabetes, older patients, patients belonging to ethnic minorities and those wholly managed in primary care were less likely to attend for eye screening (P < 0.05 for all groups) with ethnic minority or primary care management demonstrating independent influence (P < 0.001). The percentage of patients with retinopathy achieving HbA1c and systolic BP targets was significantly lower than in their unaffected counterparts (chi2 = 63, P < 0.001 and chi2 = 71, P < 0.001 respectively). CONCLUSIONS: The efficacy of the DRSS in North Staffordshire is low and might be improved by targeting specific patient groups. Glycaemic control and systolic BP control needs to be improved in patients with diabetic retinopathy.

A case of thoracic aortic dissection presenting as lateral pleuritic chest pain.

An unusual presentation of thoracic aortic dissection in a 73 year old man is described. He was admitted to hospital with severe left sided pleuritic chest pain. Examination on admission was normal apart from minor tenderness on palpation of the left lower chest wall. Chest x ray showed cardiomegaly with right lung shadowing, and ventilation/perfusion scan was negative. Spiral computed tomography done on the fourth day showed a false lumen on the ascending aorta. He underwent surgery but deteriorated postoperatively because of intrathoracic bleeding and developed cardiac tamponade from which resuscitation was not possible.

Evidence that protein kinase Cdelta is not required for palmitate-induced cytotoxicity in BRIN-BD11 beta-cells.

Chronic exposure of pancreatic beta-cells to saturated fatty acids leads to loss of viability, an effect that has been implicated in the process of beta-cell 'lipotoxicity' associated with the progression of type 2 diabetes. The mechanisms involved are unknown but recent evidence has implicated the delta isoform of protein kinase C (PKCdelta) in mediating fatty acid toxicity. We have investigated this proposition in the clonal insulin-secreting cell line, BRIN-BD11. BRIN-BD11 cells were found to undergo apoptosis when exposed to palmitate and this response was attenuated by the purportedly selective inhibitor of PKCdelta, rottlerin. However, activation of PKCdelta with the phorbol ester, phorbol-12-myristate-13-acetate (PMA), failed to promote cell death and down-regulation of PKCdelta did not prevent the cytotoxic effects of palmitate. Moreover, rottlerin remained effective as a blocker of the palmitate response in cells depleted of PKCdelta. Since rottlerin can inhibit various other kinases in addition to PKCdelta, a range of additional kinase inhibitors was also tested. Of these, only the putative Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) inhibitor, KN-62, was found to inhibit palmitate-induced cell death. However, this effect was not reproduced by a more selective pseudo-substrate inhibitor of CaM kinase II. Therefore, the present results reveal that palmitate induces cell death in BRIN-BD11 cells and suggest that this may involve the activation of a rottlerin (and KN-62)-sensitive kinase. However, it is clear that PKCdelta is not required for this response.

Improving survival with metformin: the evidence base today.

Establishing and maintaining control of glycaemia is a key step in the reduction of diabetic microvascular complications. By contrast, macrovascular disease which is the most important complication and shortens the lives of many people with type 2 diabetes is not reduced by glycaemic control alone. The landmark UK Prospective Diabetes Study (UKPDS) showed that intensive glycaemic management with metformin significantly reduced the risk of a range of debilitating and/or life-threatening macrovascular complications, compared with other oral agents, diet and insulin who achieved similar overall glycaemic control. The benefits observed included diabetes-related mortality (reduced by 42%, compared with diet treatment, p=0.017), all-cause mortality (reduced by 36%, p=0.011), myocardial infarction (reduced by 39%, p=0.01), and any diabetes-related endpoint (reduced by 32%, p=0.002). Other clinical and experimental studies have shown metformin to be associated with improved outcomes and support the conclusions from the UKPDS. In addition, a well-designed retrospective analysis has shown significantly lower mortality rates in patients receiving metformin compared with patients treated with sulphonylurea monotherapy. Metformin provides a greater degree of cardiovascular protection than would be expected from its antihyperglycaemic actions alone and is the first drug of choice for the treatment of type 2 diabetes unless there are contraindications in the individual patient.

Differential effects of genistein on apoptosis induced by fluoride and pertussis toxin in human and rat pancreatic islets and RINm5F cells.

Clonal pancreatic beta-cell lines have been used widely for the study of the factors involved in the regulation of apoptosis but it has not been firmly established that the response of normal islets mirrors that found in transformed beta-cells. In the present work, the role of pertussis toxin (Ptx)-sensitive G-proteins in the control of beta-cell apoptosis was studied in isolated rat and human islets of Langerhans and compared with the clonal beta-cell line, RINm5F. Annexin-V and deoxycarboxyfluoroscein diacetate staining was used to identify viable, apoptotic and necrotic cells directly, under fluorescence illumination. Treatment of human and rat islet cells with the G-protein activator fluoride (NaF; 5 mM) caused a marked increase in apoptosis that was further potentiated in islets pretreated with Ptx. The tyrosine kinase inhibitor genistein (100 microM) also increased islet cell apoptosis and the combination of 100 microM genistein and 5 mM NaF did not lead to any diminution of the apoptotic response. This latter effect was quite different from that seen in RINm5F cells where the combination of 100 microM genistein and 5 mM NaF resulted in much less apoptosis than was observed with either agent alone. In islets treated with a lower concentration of genistein (25 microM; that did not, itself, increase cell death), the drug attenuated NaF-induced apoptosis and also blocked the enhancement mediated by Ptx. These results revealed that human (and rat) islets are equipped with a Ptx-sensitive pathway that may be regulated by tyrosine phosphorylation and is anti-apoptotic. However, they also define conditions under which marked differences in response between RINm5F cells and normal islets were observed and they suggest that care should be taken when extrapolating data obtained with clonal cell lines to the situation in normal islet cells.

Effects of tyrosine kinase inhibitors on cell death induced by sodium fluoride and pertussis toxin in the pancreatic beta-cell line, RINm5F.

1. Sodium fluoride causes apoptosis of pancreatic beta-cells and this response is enhanced by pre-treatment with pertussis toxin. In the present study, tyrosine kinase inhibitors were used to investigate the mechanisms of action of NaF and pertussis toxin in the beta-cell line, RINm5F. 2. Exposure of RINm5F cells to low concentrations of genistein or tyrphostin A25 resulted in significant inhibition of cell death induced by 5 mM NaF. Higher concentrations (>25 microM) were cytotoxic in the absence of NaF but, paradoxically, the combination of genistein and NaF induced less cell death than when each agent was used alone. 3. The increase in cell death induced by 100 microM genistein was markedly inhibited by ciprofloxacin, a drug which binds to topoisomerase II. Etoposide (which inhibits topoisomerase II but has no effect on tyrosine kinase activity) also caused an increase in RINm5F cell death. Neither etoposide nor ciprofloxacin altered the response to 5 mM NaF. 4. Pertussis toxin markedly enhanced the extent of RINm5F cell death induced by NaF and this effect was completely prevented by 25 microM genistein. The inhibition caused by genistein was not affected by ciprofloxacin but was reproduced by a structurally dissimilar tyrosine kinase inhibitor, herbimycin A. 5. The results demonstrate that RINm5F beta-cells express a pertussis toxin sensitive pathway that is anti-apoptotic. The activity of this pathway is most evident in cells exposed to pro-apoptotic stimuli where the effects of pertussis toxin can be blocked by inhibitors of tyrosine kinase enzymes. A genistein-sensitive tyrosine kinase does not appear to be involved in RINm5F cell survival under basal conditions.

The reactive extraction of phenylalanine with Aliquat 336: buffer co-extraction equilibrium and mass transfer kinetics.

The occurrence of significant co-extraction of buffer anions by the ion exchanger Aliquat 336 is unavoidable when high levels of system buffering is required. The co-extraction will result in inaccurate equilibrium and mass-transfer characterization of such a system unless its occurrence is taken into account, making process design and control difficult. A study of the equilibrium of phenylalanine extraction using Aliquat 336, a system where high levels of hydroxyl co-extraction occurs, was used as a model case to develop a method of accounting for co-extraction in mass-transfer modeling. Analysis of the equilibrium between bulk-aqueous-phase chloride and phenylalanine concentrations during mass transfer in a stirred-transfer cell showed there to be linear equilibrium relationships between the two parameters for a given extraction system of the form C(Cl,t) = alpha(C(A,t) - C(A,0)) for forward extraction and C(Cl,t) = epsilon C(A,t) + C(Cl,0) for backward extraction. The constants of proportionality of these relationships, or the "co-extraction constants," alpha and epsilon, were shown to be related to the selectivity of Aliquat 336 for the phenylalanine anion by the relationships alpha = -(1/S + 1) and epsilon; = -(1/S(-1) + 1). The linear equilibrium relationships were used to develop two-film theory mass-transfer models for both forward and backward extraction that account for co-extraction. These showed much higher accuracy in modeling stirred-transfer-cell data than the equivalent models which ignored co-extraction.

Dissociation between Fas expression and induction of apoptosis in human islets of Langerhans.

There is increasing evidence that inappropriate induction of apoptosis in pancreatic beta-cells may precede the development of type 1 diabetes in animal models and in man. One mechanism by which this has been proposed to occur involves up-regulation of the death receptor Fas on beta-cells, resulting in apoptosis of the Fas-bearing beta-cells upon ligation of the receptor. We have examined this hypothesis in isolated human islets of Langerhans and show that--in contrast to data obtained with rodent beta-cells--expression of Fas per se is not sufficient to allow induction of apoptosis upon addition of agonistic anti-Fas serum.

Effect of metformin on bile salt circulation and intestinal motility in type 2 diabetes mellitus.

Gastrointestinal symptoms can be a limiting factor in optimizing metformin therapy, particularly at the onset of treatment. The underlying cause remains unclear. We have investigated whether metformin changes oral-caecal transit and if it causes bile salt malabsorption using the lactulose breath test and orally administered 14C-glycocholate followed by breath 14CO2 measurement over 6 h and stool collection for 72 h, respectively. Twenty-four diet and/or sulphonylurea treated patients underwent 7 days of baseline investigations before entering a randomized double-blind crossover study of 21 days duration with either metformin (850 mg bd) or placebo. No difference was observed in the oral-caecal transit time but a change in fasting plasma glucose was observed of 2.6 mmol l-1 (95% CI 1.3, 3.8). Significant increases in percentage 14CO2 breath elimination were observed during treatment with metformin (9.7 +/- 6.3) compared with placebo (3.1 +/- 1.9) p = 0.020. In addition, percentage faecal 14C bile salt excretion was increased with metformin (17.2 +/- 9.9 vs 10.1 +/- 6.9) p = 0.037. A significant association (p = 0.002) emerged for stool bile salt content and liquidity of the stool. We conclude that metformin may cause gastrointestinal disturbances by reducing ileal bile salt reabsorption leading to elevated colonic bile salt concentrations.

An audit of the management of thyroid cancer in a district general hospital.

OBJECTIVE: Thyroid cancer is the commonest endocrine malignancy yet it appeared to present infrequently to the endocrinologists at this large District General Hospital. The management of well-differentiated thyroid cancer remains controversial with a wide variation in clinical practice. The aim of this survey was to determine the characteristics of the patients diagnosed with thyroid cancer and whether any deficiencies existed in the management of subjects diagnosed with thyroid cancer over a five-year period using standards of care based upon long-term outcome data and recently published USA guidelines. DESIGN AND PATIENTS: Retrospective case-note survey of all patients newly registered with thyroid cancer from 1990 to 1994 in North Staffordshire (estimated total population 450,000). RESULTS: The annual incidence of all thyroid cancer was two per 100,000 of which well-differentiated tumours comprised 70%. Medical records were obtained in 48 new cases (91% of total) identified. Fifteen subjects who presented as surgical emergencies received only palliative treatment and had a poor outcome. Two patients presented with metastatic medullary thyroid carcinoma (3% of total). Thirty-one patients (97% of whom presented with a thyroid nodule) were referred electively to either surgical (n = 22), ENT (n = 2) or endocrinology (n = 7) outpatients with well-differentiated papillary (n = 17) and follicular (n = 14) tumours. Thirteen patients (42%) had fine-needle aspiration cytology performed preoperatively. Of the 22 tumours (71%) greater than 1.5 cm, five (27%) had a total thyroidectomy and two (9%) also had radioiodine ablation. There was inadequate serum thyrotrophin suppression postoperatively in 12 patients (39%) and only five (16%) were being monitored for recurrence with serum thyroglobulin measurements. CONCLUSIONS: Deficiencies in the optimum management of small, well-differentiated thyroid cancers were identified. Improved communication between specialties has led to the development of an agreed management protocol to increase the quality of care offered to patients with thyroid cancer and for auditing the coordinated service in the future.

Human islets of Langerhans express Fas ligand and undergo apoptosis in response to interleukin-1beta and Fas ligation.

IDDM results from a progressive loss of pancreatic beta-cells that, in humans, may be triggered by a combination of genetic and environmental factors. Recently, attention has been focused on the hypothesis that the loss of beta-cells is initiated by inappropriate induction of apoptosis. We now demonstrate that human islets of Langerhans undergo apoptosis upon exposure to interleukin-1beta. The cytokine also sharply increases the number of cells that enter apoptosis on treatment with a stimulatory anti-Fas antibody. Western blotting and immunocytochemistry clearly show for the first time that human pancreatic beta-cells normally express Fas ligand. The results suggest that human islet cells are primed to undergo apoptosis by interleukin-1beta and that this involves the close association between cell-surface Fas and its ligand.

Evidence for the involvement of cGMP and protein kinase G in nitric oxide-induced apoptosis in the pancreatic B-cell line, HIT-T15.

Intracellular production of nitric oxide (NO) is thought to mediate the pancreatic B-cell-directed cytotoxicity of cytokines in insulin-dependent diabetes mellitus, and recent evidence has indicated that this may involve induction of apoptosis. A primary effect of NO is to activate soluble guanylyl cyclase leading to increased cGMP levels and this effect has been demonstrated in pancreatic B-cells, although no intracellular function has been defined for islet cGMP. Here we demonstrate that the NO donor, GSNO, induces apoptosis in the pancreatic B-cell line HIT-T15 in a dose- and time-dependent manner. This response was significantly attenuated by micromolar concentrations of a specific inhibitor of soluble guanylyl cyclase, ODQ, and both 8-bromo cGMP (100 microM) and dibutyryl cGMP (300 microM) were able to fully relieve this inhibition. In addition, incubation of HIT-T15 cells with each cGMP analogue directly promoted cell death in the absence of ODQ. KT5823, a potent and highly selective inhibitor of cGMP-dependent protein kinase (PKG), abolished the induction of cell death in HIT cells in response to either GSNO or cGMP analogues. This effect was dose-dependent over the concentration range of 10-250 nM. Overall, these data provide evidence that the activation of apoptosis in HIT-T15 cells by NO donors is secondary to a rise in cGMP and suggest that the pathway controlling cell death involves activation of PKG.

Appropriateness of acute medical admissions and length of stay.

OBJECTIVE: To use the Appropriateness Evaluation Protocol (AEP) to assess the extent of inappropriate utilisation of hospital beds by acute medical patients. To determine whether clinicians viewed the AEP decisions as valid. DESIGN: Retrospective review of the medical records of a 10% random sample of 8,210 patients admitted as medical emergencies. An objective independent review instrument (AEP) was used to assess the medical necessity for hospitalisation at admission and on each subsequent day. To test the validity of the screening instrument, a subsample of the reviewed records was further assessed by a panel of physicians. SETTING: A district general hospital in the West Midlands region of England. SUBJECTS: Eight hundred and twenty-one adult patients admitted to general medicine during one calendar year. MAIN OUTCOME MEASURES: Proportions of admissions and days of care for which inpatient medical care was judged appropriate. Reasons for inappropriate utilisation and potential bed-days that could be saved by the development and use of alternative services were also considered. Validity of the AEP was tested by assessing agreement between the majority decision of an expert panel and the criterion-based AEP decision. RESULTS: AEP identified 51/821 (6%) admissions and 2,195/4,885 (45%) days of care as inappropriate. Over half the patients had a hospital stay in which at least half the days were judged inappropriate. The commonest reason for inappropriate days was remaining in hospital after the medical purpose for admission had been accomplished. This accounted for 38% of inappropriate days reviewed. In validity testing there was a high level of agreement between the physicians and the AEP, with kappa values greater than 0.80 for admissions and days of care. CONCLUSIONS: The AEP is a valid and useful instrument for assessing the utilisation of acute medical beds in a NHS hospital. In this study acute medical admissions were largely appropriate at the time of admission but a substantial proportion of subsequent days of care was considered inappropriate by AEP criteria. Most inappropriate utilisation was due to organisational issues within the hospital. As a result of this study, several service and policy developments were identified that should improve the efficiency of bed utilisation at the hospital.

Heterotrimeric G-proteins are implicated in the regulation of apoptosis in pancreatic beta-cells.

Recent studies have provided evidence that apoptosis of pancreatic beta-cells is important in the early etiology of both type I and type II diabetes mellitus. The mechanisms responsible for induction of apoptosis are unknown, but we present evidence that the signal transduction pathway controlling the process in pancreatic beta-cells is regulated by G-proteins. We have employed the global G-protein activator fluoride and show that this agent induces apoptosis in clonal RINm5F pancreatic beta-cells and also in the cells of normal rat islets of Langerhans. The process is time and concentration dependent and may reflect the formation of AIF4- since it was inhibited by the aluminum chelator deferoxamine. Induction of apoptosis by fluoride was confirmed by acridine orange staining of cell nuclei, by electron-microscopic examination of chromatin condensation, and by oligonucleosomal degradation of DNA. The involvement of G-proteins was confirmed by culture of beta-cells in the presence of pertussis toxin (PTX) prior to exposure to fluoride. PTX did not affect the extent of cell death under control conditions but it consistently, and markedly, enhanced the response to fluoride. The results demonstrate that apoptosis can be induced in pancreatic beta-cells by sustained activation of a G-protein-dependent signaling pathway(s) and they further suggest that a pertussis toxin-sensitive G-protein is involved in attenuation of the response. Treatment of RINm5F pancreatic beta-cells with dibutyrylcAMP resulted in a dose-dependent, saturable increase in cell death, suggesting that a sustained rise in intracellular cAMP may form part of the effector system controlling apoptosis.