The impact of cardiovascular co-morbidities and duration of diabetes on the association between microvascular function and glycaemic control.

BACKGROUND: Good glycaemic control in type 2 diabetes (T2DM) protects the microcirculation. Current guidelines suggest glycaemic targets be relaxed in advanced diabetes. We explored whether disease duration or pre-existing macrovascular complications attenuated the association between hyperglycaemia and microvascular function. METHODS: 743 participants with T2DM (n = 222), cardiovascular disease (CVD = 183), both (n = 177) or neither (controls = 161) from two centres in the UK, underwent standard clinical measures and endothelial dependent (ACh) and independent (SNP) microvascular function assessment using laser Doppler imaging. RESULTS: People with T2DM and CVD had attenuated ACh and SNP responses compared to controls. This was additive in those with both (ANOVA p < 0.001). In regression models, cardiovascular risk factors accounted for attenuated ACh and SNP responses in CVD, whereas HbA1c accounted for the effects of T2DM. HbA1c was associated with ACh and SNP response after adjustment for cardiovascular risk factors (adjusted standardised beta (ß) -0.096, p = <0.008 and -0.135, p < 0.001, respectively). Pre-existing CVD did not modify this association (ß -0.099; p = 0.006 and -0.138; p < 0.001, respectively). Duration of diabetes accounted for the association between HbA1c and ACh (ß -0.043; p = 0.3), but not between HbA1c and SNP (ß -0.105; p = 0.02). CONCLUSIONS: In those with T2DM and CVD, good glycaemic control is still associated with better microvascular function, whereas in those with prolonged disease this association is lost. This suggests duration of diabetes may be a better surrogate for "advanced disease" than concomitant CVD, although this requires prospective validation.

Exercise intensity and the protection from postprandial vascular dysfunction in adolescents.

Acute exercise transiently improves endothelial function and protects the vasculature from the deleterious effects of a high-fat meal (HFM). We sought to identify whether this response is dependent on exercise intensity in adolescents. Twenty adolescents (10 male, 14.3 ± 0.3 yr) completed three 1-day trials: 1) rest (CON); 2) 8 × 1 min cycling at 90% peak power with 75 s recovery [high-intensity interval exercise (HIIE)]; and 3) cycling at 90% of the gas exchange threshold [moderate-intensity exercise (MIE)] 1 h before consuming a HFM (1.50 g/kg fat). Macrovascular and microvascular endothelial function was assessed before and immediately after exercise and 3 h after the HFM by flow-mediated dilation (FMD) and laser Doppler imaging [peak reactive hyperemia (PRH)]. FMD and PRH increased 1 h after HIIE [P < 0.001, effect size (ES) = 1.20 and P = 0.048, ES = 0.56] but were unchanged after MIE. FMD and PRH were attenuated 3 h after the HFM in CON (P < 0.001, ES = 1.78 and P = 0.02, ES = 0.59). FMD remained greater 3 h after the HFM in HIIE compared with MIE (P < 0.001, ES = 1.47) and CON (P < 0.001, ES = 2.54), and in MIE compared with CON (P < 0.001, ES = 1.40). Compared with CON, PRH was greater 3 h after the HFM in HIIE (P = 0.02, ES = 0.71) and MIE (P = 0.02, ES = 0.84), with no differences between HIIE and MIE (P = 0.72, ES = 0.16). Plasma triacylglycerol concentration and total antioxidant status concentration were not different between trials. We conclude that exercise intensity plays an important role in protecting the vasculature from the deleterious effects of a HFM. Performing HIIE may provide superior vascular benefits than MIE in adolescent groups.

Measures of atherosclerotic burden are associated with clinically manifest cardiovascular disease in type 2 diabetes: a European cross-sectional study.

BACKGROUND: There is a need to develop and validate surrogate markers of cardiovascular disease (CVD) in subjects with diabetes. The macrovascular changes associated with diabetes include aggravated atherosclerosis, increased arterial stiffness and endothelial dysfunction. The aim of this study was to determine which of these factors is most strongly associated with clinically manifest cardiovascular events. METHODS: Vascular changes were measured in a cohort of 458 subjects with type 2 diabetes (T2D) and CVD (myocardial infarction, stroke or lower extremity arterial disease), 527 subjects with T2D but without clinically manifest CVD and 515 subjects without T2D and with or without CVD. RESULTS: Carotid intima-media thickness (IMT) and ankle-brachial pressure index were independently associated with the presence of CVD in subjects with T2D, whereas pulse wave velocity and endothelial function provided limited independent additive information. Measurement of IMT in the carotid bulb provided better discrimination of the presence of CVD in subjects with T2D than measurement of IMT in the common carotid artery. The factors most significantly associated with increased carotid IMT in T2D were age, disease duration, systolic blood pressure, impaired renal function and increased arterial stiffness, whereas there were no or weak independent associations with metabolic factors and endothelial dysfunction. CONCLUSIONS: Measures of atherosclerotic burden are associated with clinically manifest CVD in subjects with T2D. In addition, vascular changes that are not directly related to known metabolic risk factors are important in the development of both atherosclerosis and CVD in T2D. A better understanding of the mechanisms involved is crucial for enabling better identification of CVD risk in T2D.

Can we know the immunization status of healthcare workers? Results of a feasibility study in hospital trusts, England, 2008.

In England, there is no surveillance system for vaccines offered to healthcare workers apart from that in place annually for the seasonal influenza vaccine. To inform the feasibility of a general vaccine uptake surveillance system and to understand which policies are currently in place, we conducted a survey in the 162 National Health Service Foundation and Acute Hospital trusts in England, by submitting a questionnaire to their occupational health departments on immunization policies and methods of storing vaccine uptake data. In total, 104 hospital trusts (64.2%) responded. All responders offer hepatitis B, tuberculosis, measles-mumps-rubella, and influenza vaccines to healthcare workers; 0.9% reported not offering varicella and 13.5% not offering tetanus-diphtheria-polio; 66.4% record staff eligible for immunizations and 68.2% record staff they have immunized. Our study suggests that setting up a surveillance system to monitor vaccine uptake in healthcare workers is possible but would be challenging, given the variation in current systems.

Could exercise be a new strategy to revert some patients with atrial fibrillation?

BACKGROUND: This study is the result of the anecdotal observation that a number of patients with atrial fibrillation (AF) had noted reversion to sinus rhythm (SR) with exercise.We aimed to evaluate the potential role of exercise stress test (EST) for the reversion of AF. METHODS: Patients with AF who were scheduled to undergo electrical cardioversion (DCR) underwent EST using a modified Bruce protocol. RESULTS: Eighteen patients (16 male); aged 36-74 years (mean 58 years) were studied. Five patients (27.7%) had successful reversion with exercise (group 1). Thirteen patients remained in AF (group 2). No patient who failed to revert with exercise did so spontaneously before DCR 3 h to 7 months later (median 20 days). Comparison between group 1 and group 2 did not reveal any significant difference CONCLUSION: This small preliminary study suggests that in some patients it may be possible to revert AF to SR with exercise and avoid DCR and concomitant general anaesthesia. The authors suggest that a larger multicentre randomized trial is warranted to confirm or refute these initial results and if correct identify those who might benefit.

Newt myotubes reenter the cell cycle by phosphorylation of the retinoblastoma protein.

Withdrawal from the cell cycle is an essential aspect of vertebrate muscle differentiation and requires the retinoblastoma (Rb) protein that inhibits expression of genes needed for cell cycle entry. It was shown recently that cultured myotubes derived from the Rb-/- mouse reenter the cell cycle after serum stimulation (Schneider, J.W., W. Gu, L. Zhu, V. Mahdavi, and B. Nadal-Ginard. 1994. Science (Wash. DC). 264:1467-1471). In contrast with other vertebrates, adult urodele amphibians such as the newt can regenerate their limbs, a process involving cell cycle reentry and local reversal of differentiation. Here we show that myotubes formed in culture from newt limb cells are refractory to several growth factors, but they undergo S phase after serum stimulation and accumulate 4N nuclei. This response to serum is inhibited by contact with mononucleate cells. Despite the phenotypic parallel with Rb-/- mouse myotubes, Rb is expressed in the newt myotubes, and its phosphorylation via cyclin-dependent kinase 4/6 is required for cell cycle reentry. Thus, the postmitotic arrest of urodele myotubes, although intact in certain respects, can be undermined by a pathway that is inactive in other vertebrates. This may be important for the regenerative ability of these animals.

The electronic, 'paperless' medical office; has it arrived?

Modern information technology offers efficiencies in medical practice, with a reduction in secretarial time in maintaining, filing and retrieving the paper medical record. Electronic requesting of investigations allows tracking of outstanding results. Less storage space is required and telephone calls from pharmacies, pathology and medical imaging service providers to clarify the hand-written request are abolished. Voice recognition software reduces secretarial typing time per letter. These combined benefits can lead to significantly reduced costs and improved patient care. The paperless office is possible, but requires commitment and training of all staff; it is preferable but not absolutely essential that at least one member of the practice has an interest and some expertise in computers. More importantly, back-up from information technology providers and back-up of the electronic data are absolutely crucial and a paperless environment should not be considered without them.

Pilot scheme for monitoring sickness absence in schools during the 2006/07 winter in England: can these data be used as a proxy for influenza activity?

During influenza epidemics, school-aged children are amongst the first affected patients. They frequently then spread the virus within their families. Recognising influenza activity in schools may therefore be an important indicator of early activity in the wider community. During 2005/06, influenza B was associated with high levels of morbidity in school-children and over 600 schools outbreaks were reported to the Health Protection Agency by local Health Protection Units. While it is not possible to directly monitor influenza in schools, the feasibility and validity of using sentinel school absenteeism data, as a proxy for influenza in the community can be investigated. From week 02/07 to 20/07, eight primary and three secondary schools from five HPA regions were able, via the Department of Health-funded Health Protection Informatics website, to report daily electronic registration data, relating to absenteeism due to illness. Aggregated absenteeism data due to illness peaked the same week as indices for the age group comparable to that used by the Royal College for General Practitioners and NHS Direct schemes. When illness-defined absenteeism data was stratified into primary and secondary schools, absence in primary schools peaked one week before that in secondary schools and the established schemes for all ages. The start time of the study meant that initial increases in activity could not be measured. These encouraging results justify expanding this sentinel scheme to collect more rigorous evidence of the usefulness of absenteeism as a proxy for influenza activity and a tool to inform policy and trigger local responses.

Symptomatic and asymptomatic carotid stenosis: just when we thought we had all the answers.

The management of symptomatic and asymptomatic carotid stenosis has been a hotly debated topic for decades. The publication of four randomized controlled trials of carotid endarterectomy has clarified many of the issues. Patients with symptomatic carotid stenosis >70% benefit most with an absolute risk reduction of 17% over 2 years with numbers needed to treat of 3-6, whereas in patients with asymptomatic carotid stenosis >60%, the absolute risk reduction is 1% per annum (numbers needed to treat = 14-17). There is doubt about the benefit in women >70 years of age with asymptomatic stenosis. Carotid angioplasty and stenting is in its infancy and may one day supplant carotid endarterectomy as the treatment of choice; however, currently indications for this procedure include participation in randomized controlled trials, surgically inaccessible stenosis, in patients with combined symptomatic carotid and symptomatic coronary artery disease or in patients with severe co-morbidities that preclude formal carotid endarterectomy.

Ru-catalysed C-H silylation of unprotected gramines, tryptamines and their congeners.

Selective Ru-catalysed C2-H silylation of heteroarenes is presented. The transformation works with or without directing group assistance and requires no protecting groups. Gramines and tryptamines may be converted efficiently whilst avoiding deleterious elimination side-reactions. Mechanistic studies reveal an unusual activation of the indole C4-H bond by an electron-rich metal.

Effect of 17 beta-estradiol on chondrocyte membrane fluidity and phospholipid metabolism is membrane-specific, sex-specific, and cell maturation-dependent.

In this study we examined the hypothesis that 17 beta-estradiol exerts both rapid and direct, nongenomic effects of cells in the endochondral pathway. To do this, we used a cell culture model in which chondrocytes at two distinct stages of cell maturation are isolated from the costochondral cartilage of male and female rats, and examined the short-term effect of 17 alpha- and 17 beta-estradiol on [14C]arachidonic acid turnover in the cell layer and phospholipase A2 specific activity in plasma membranes and extracellular matrix vesicles isolated from similarly prepared cultures. In addition, the effect of 17 alpha- and 17 beta-estradiol on plasma membrane and matrix vesicle membrane fluidity was assessed. The effect of hormone on arachidonic acid turnover was rapid, time- and concentration-dependent, stereo-specific, and cell maturation-specific. Only resting zone cells from female rats were affected, and only 17 beta-estradiol elicited a response. Similarly, only female rat resting zone chondrocytes exhibited a change in phospholipase A2 activity after a 24 h exposure to hormone, causing an increase in enzyme activity in the matrix vesicles, but not plasma membranes. When isolated membranes were incubated directly with hormone, membrane fluidity was decreased in both plasma membranes and matrix vesicles isolated from female rat resting zone chondrocyte cultures. This nongenomic effect was dose-dependent and stereo-specific and differentially expressed in the two membrane fractions with respect to time course and magnitude of response. These results support the hypothesis that 17 beta-estradiol has a rapid action on chondrocyte membrane lipid metabolism and suggest that specific membrane components, characteristic of a particular sex and state of cell maturation, are involved in the nongenomic effects of this sex hormone on isolated matrix vesicles and plasma membranes.

Structure and expression of a newt cardio-skeletal myosin gene. Implications for the C value paradox.

As part of our studies on the fate of the muscle lineage during amphibian limb regeneration, we have isolated genomic and cDNA sequences from a myosin heavy chain in the newt (Notophthalmus viridescens). Notwithstanding the technical problems inherent in analysing the large newt genome, genomic and cDNA sequences have been isolated and subjected to analysis by restriction mapping. Northern hybridization, Southern hybridization and DNA sequencing. We believe these to be the first single copy newt gene sequences to have been subjected to this type of analysis. The newt gene sequences showed a striking difference from mammalian myosins in both the estimated sizes of the gene and its intervening sequences; these being much larger than in the mammalian models, it is speculated that this could contribute to the exceptional size of the newt genome. By contrast, the coding sequences displayed very high levels of sequence homology to mammalian myosins. In particular, the amino acid sequence of the newt myosin was found to have greatest homology with rat and human myosin isotypes having a similar cardio-skeletal muscle expression pattern. Despite a long evolutionary separation, newt and mammalian cardio-skeletal myosins have remained more similar to each other than have the human or rat cardiac forms to skeletal myosins within their own respective species.

The expression pattern of tomoregulin-1 in urodele limb regeneration and mouse limb development.

Tomoregulin-1 (TMEFF1) was first identified as a gene implicated in pituitary secretion in Xenopus laevis. The predicted structure of TMEFF1 is that of a transmembrane protein with a highly conserved cytoplasmic tail, two follistatin domains and one modified EGF domain in its extracellular region. We report the cloning of the newt orthologue, and show that the expression of TMEFF1 is upregulated in the blastema during limb regeneration, and is also expressed in mouse embryonic limb development.

Delta retinoic acid receptor isoform delta 1 is distinguished by its exceptional N-terminal sequence and abundance in the limb regeneration blastema.

In amphibian limb regeneration memory for position in the proximal-distal axis can be respecified by retinoic acid. The favoured candidates to mediate this effect are the retinoic acid receptors (RARs) and of the RARs identified in the regeneration blastema, the delta receptor is the most abundant. The presence in blastemal mesenchyme of at least two delta receptor isoforms, delta 1 and delta 2, alternatively spliced at the A-B junction, was demonstrated in expression studies and by PCR cloning. The delta 1 receptor is abundant in regenerative structures such as the limb and tail, whereas the delta 2 and alpha receptors show a more uniform pattern of expression across adult newt tissues. Full-length cloning of the delta 1 receptor established the presence of an unusually long open reading frame and N-terminal sequence that appears unique among vertebrate retinoic acid receptors. Transient transfection of expression constructs into COS cells followed by Western blotting confirmed the existence of at least three potential initiation sites for delta 1 translation. The possibility that delta 1 RAR expression may specify positional memory directly was tested in RNase protection experiments. delta 1 receptor message is increased on amputation, but does not exhibit a pronounced differential distribution along the proximal-distal axis in normal and regenerating limbs, nor does it show a persistent alteration in expression levels following a dose of retinoic acid sufficient to respecify position. The possibility that the morphogenetic effects of RA may be mediated through receptor interactions is raised by the finding that single mesenchymal blastemal cells in culture can express multiple RAR subtypes (delta 1 and alpha) and isoforms (delta 1 and delta 2).

Cardiovascular toxicity is increased, but manageable, during high-dose chemotherapy and autologous peripheral blood stem cell transplantation for patients aged 60 years and older.

High-dose therapy (HDT) for non-Hodgkins lymphoma (NHL) and multiple myeloma (MM) is considered a feasible option for patients aged 60 years. This study compared the outcomes for all patients aged 60 years treated with HDT at the center to a matched cohort group aged <60 years. Results for patients who were 60 years at HDT between 1997--2002 were retrospectively analysed to assess efficacy and safety. Event-free (EFS) and overall survival (OS) rates were compared with a cohort group, matched by disease type, chemotherapy sensitivity, year of treatment and conditioning regimen. Patients with NHL were also matched by International Prognostic Index score. Forty patients aged 60 years were identified. Median age was 65 (range 60--76) with 22 MM and 18 NHL; 50% had 1 or more co-morbidity; 35% had cardiovascular co-morbidity vs. 18% of controls (p=0.075). Response rates (RR) following HDT for MM were: 4 (18%) complete responses (CR) and 18 (82%) partial responses (PR), giving an overall response rate (ORR) of 100%, vs. 77% for controls (p=0.02). For NHL patients there were: 8 CR (44%) and 4 PR (22%), giving an ORR of 67%, vs. 83% for controls (p=0.3). Transplant-related mortality was 8% compared to 5% in controls (p=0.6). Toxicities were similar with the exception of cardiac toxicity, which was significantly higher in patients aged 60 years vs. controls (50% grade 3 vs. 10%: p<0.0001). Atrial fibrillation was the most frequent cardiovascular toxicity (9 patients). At a median follow-up of 33 months, there is no significant difference between older vs. younger patients in median EFS (24 vs. 38 months: p=0.78) or OS (40 months vs. not reached: p=0.23). HDT is feasible and effective in selected patients 60 years with MM and NHL. Patients 60 years are more susceptible to cardiovascular toxicities, particularly atrial fibrillation, but have similar or better response rates following HDT and similar long-term outcomes to younger patients.

Identification of newt connective tissue growth factor as a target of retinoid regulation in limb blastemal cells.

In order to analyse target genes regulated by retinoic acid in urodele limb regeneration, we have used pseudotyped retroviruses to obtain stably transfected newt limb blastemal (progenitor) cells in culture which express chimeric retinoic acid/thyroid hormone receptors delta1 or delta2. After treatment with thyroid hormone to activate the chimeric receptors, we used a polymerase chain reaction (PCR)-based subtraction method to identify target genes which are retinoid regulated. Newt connective tissue growth factor, a secreted protein recognised in several vertebrates, has been identified in this way and found to be expressed in the limb blastema and regulated by retinoic acid. This approach should permit a systematic analysis of retinoid target genes in limb regeneration.

Bilateral occlusion of vertebral artery: clinical patterns and long-term prognosis.

We studied 17 patients with atherosclerotic bilateral occlusion of vertebral arteries (VA) identified by angiography. Seven had vertebrobasilar TIAs, eight a brainstem stroke (severe in two), and two had only carotid symptoms. Brainstem strokes were more frequent with bilateral intracranial occlusion (60%) than with at least one extracranial occlusion (28.6%), but long-term prognosis did not differ in these two groups. In follow-up, the mortality rate was 4.5% per year, and the stroke rate was 1.8% per year. Major functional disability was seen in 16.7% of the survivors. Bilateral distal VA occlusion may sometimes have a better prognosis than previously assumed. These findings raise doubts about the value of extra-intracranial surgical bypass procedures in patients with these lesions.

CT metrizamide myelography in syringomyelia: sensitivity and specificity.

In a retrospective study of 32 patients with "proven" syringomyelia and 15 patients with an alternate proven diagnosis, a change in the caliber of the spinal cord with different positions ("collapsing cord sign or cord collapse") had a sensitivity of 38% and a specificity of 87%. Central cord enhancement ("bull's-eye") on delayed CT had a sensitivity and specificity of 91% and 87%, respectively. The positive predictive value of cord collapse was 87%, while the positive predictive value of central cord enhancement was 94%.

Receptor isoform specificity in a cellular response to retinoic acid.

The effects of retinoic acid on cell proliferation, differentiation and patterning are thought to be mediated by the various retinoic acid receptors. Different receptor types are encoded by distinct genes (alpha, beta, and gamma), whereas various isoforms within each type are encoded by splicing variants resulting from the use of alternative promoters. The only region that differs between isoforms is the N-terminal A region containing a transcriptional activating domain. It has been proposed that these alternative A regions confer distinct activities on the receptors, thus allowing each to mediate specific effects of retinoic acid, but it has been difficult to demonstrate such isoform specificity as most cells express a number of different retinoic acid receptors. In an attempt to test whether different isoforms can mediate distinct biological effects we are focusing on retinoic-acid-dependent growth inhibition of newt limb cells. We have constructed chimaeric receptors in which the retinoic acid binding domain of each of five newt retinoic acid receptors has been replaced with a thyroid hormone (T3) binding domain. These constructs were introduced individually into cells whose growth rate was then measured in the presence of T3. The chimaeric alpha 1 receptor mediated T3-dependent inhibition of proliferation that was comparable to that given by retinoic acid, whereas the alpha 2 isoform had no activity in this assay, nor did the delta 1A, delta 1B and Delta 2 receptors. When the A region was deleted from the alpha 1 chimaera it remained a potent T3-dependent transcriptional activator, but no longer mediated T3-dependent growth inhibition. In contrast, when the A region of alpha 1 was transferred to a delta chimaeric receptor, the resulting molecule was fully active in T3-dependent growth inhibition. This is the first direct evidence for isoform specificity in a biological response to retinoic acid, and demonstrates that the specificity of this response is confined to the A region.