Anna Dover

Inducible nitric oxide synthase activity contributes to the regulation of peripheral vascular tone in patients with cirrhosis and ascites

Background: Overexpression of inducible nitric oxide synthase (iNOS) and increased nitric oxide generation may be associated with the hyperdynamic circulation of patients with cirrhosis. We have, for the first time, used the highly selective iNOS inhibitor, 1400W, to determine whether iNOS activity contributes to the regulation of vascular tone in patients with cirrhosis and ascites. Methods: Bilateral forearm blood flow was measured using strain gauge plethysmography in eight patients with cirrhosis and ascites, and eight matched healthy volunteers during intrabrachial infusion of 1400W (0.1–1 μmol/min), NG-monomethyl-L-arginine (L-NMMA, a non-selective NOS inhibitor; 2–8 μmol), and norepinephrine (a control vasoconstrictor; 60–480 pmol/min). Results: In patients with cirrhosis, 1400W, L-NMMA, and norepinephrine caused dose dependent reductions in forearm blood flow: peak reductions of 11 (5)%, 37 (4)%, and 48 (5)%, respectively (p<0.05 for all). In contrast, 1400W had no effect on blood flow (+4 (8)%; NS) in healthy controls despite similar reductions in blood flow with L-NMMA and norepinephrine (39 (5)% and 49 (5)%, respectively; p<0.05 for both). Conclusions: We have, for the first time, demonstrated that 1400W causes peripheral vasoconstriction in patients with cirrhosis but not healthy matched controls. This suggests that iNOS contributes to the regulation of peripheral vascular tone in patients with cirrhosis and ascites, and may contribute towards the hyperdynamic circulation associated with this condition.

Intra-vascular glucocorticoid metabolism as a modulator of vascular structure and function.

Abstract.The ability of glucocorticoids to directly alter arterial function, structure and the inflammatory response to vascular injury may contribute to their well-established link with the development of cardiovascular disease. Recent studies have emphasised the importance of tissue-specific regulation of glucocorticoid availability by the 11 β-hydroxysteroid dehydrogenase (11HSD) isozymes, which inter-convert active glucocorticoids and their inactive metabolites. The expression of both type 1 and type 2 11HSDs in the arterial wall suggests that prereceptor metabolism of glucocorticoids may have a direct impact on vascular physiology. Indeed there is evidence that 11HSDs influence glucocorticoid-mediated changes in vascular contractility, vascular structure, the inflammatory response to injury and the growth of new blood vessels. Hence, inhibition of 11HSD isozymes may provide a novel therapeutic target in vascular disease.

Flash Glucose Monitoring Improves Outcomes in a Type 1 Diabetes Clinic

The Freestyle Libre flash glucose monitoring (FGM; Abbott Diabetes Care, Witney, UK) system was introduced in the United Kingdom in 2013. Although similar to conventional continuous glucose monitoring (CGM) systems, a few significant differences exist. FGM sensors are factory calibrated and therefore do not require calibration with blood glucose testing over their 14-day lifespan. FGM is also considerably cheaper than conventional CGM but lacks alarm features and connectivity with continuous subcutaneous insulin infusion (CSII) devices, such as low-glucose suspend. The accuracy and usability of FGM have been validated in patients with both type 1 and type 2 diabetes. We sought to prospectively assess the impact of introducing FGM to patients attending our type 1 diabetes clinic in a university teaching hospital, over a 16-week period. In particular, we assessed the impact on HbA1c, hypoglycemia (recorded and self-reported) and quality of life measures (Diabetes Distress Scale). The only inclusion criteria were a diagnosis of type 1 diabetes and a willingness to upload FGM data at least monthly. Data were analyzed as intention-to-treat. Of the 25 participants, 13 were men, and the mean age was 39.8 ± 2.0 years. Mean duration of diabetes was 19 ± 2 years. A total of 8 patients were treated with CSII, and 17 used multiple daily injections. Immediately prior to commencement of FGM, the mean HbA1c of participants was 8.0 ± 0.14%, which did not differ from the mean of the previous 4 clinic recorded HbA1c values (8.0 ± 0.2%, P = .833). Mean HbA1c fell from 8.0 ± 0.14% to 7.5 ± 0.14% (–0.48%, P = .001) following 16 weeks of FGM. The number of people with an HbA1c of 7.5% or below more than doubled after FGM use (Figure 1). The mean reduction in HbA1c was greater in those with a baseline HbA1c > 7.5%: –0.59 ± 0.15% compared to −0.2 ± 0.11% in those with HbA1c <7.5% at baseline (P = .005). Female participants had greater mean reduction in HbA1c (–0.74 ± 0.19%) compared to men (–0.23 ± 0.15%, P = .049) despite no significant difference in baseline HbA1c (8.2 ± 0.25% vs 7.8 ± 0.14%, P = .174). Of participants, 24% (6/25) achieved an HbA1c reduction of greater than 1.0%. Episodes of hypoglycemia (glucose <72 mg/dl), as determined from FGM glucose data, reduced from 17 (IQR 10-20) in the first 2 weeks of use to 12 (IQR 8.5-16) in the final 2 weeks (P = .019). Significant reductions were observed in the Diabetes Distress Scale mean score (P = .006), as well as emotional burden (P = .035) and regimen-related distress subscores (P = .005). FGM use was associated with a significant increase in delivering bolus insulin 15-20 minutes in advance of meals (compared to immediately before or after meals), from 16% to 44% (P = .026). In summary, these results support the wider use of FGM to improve outcomes in people with type 1 diabetes. Benefits are realized across a number of important domains including improved HbA1c, hypoglycemia, and quality of life. 661560 DSTXXX10.1177/1932296816661560Journal of Diabetes Science and TechnologyDover et al letter2016

Acute effects of glucocorticoids on endothelial fibrinolytic and vasodilator function in humans.

Acute coronary events occur most commonly in the morning, when circadian variations dictate that endogenous fibrinolytic activity is low and cortisol levels are high. We hypothesized that glucocorticoids would impair the acute fibrinolytic capacity of the endothelium because chronic glucocorticoid excess is associated with a prothrombotic state and endothelial vasomotor dysfunction. Twelve healthy subjects attended on 3 occasions and received oral metyrapone followed by intravenous saline or low-dose or high-dose hydrocortisone. Forearm blood flow and fibrinolytic indices were measured using venous occlusion plethysmography during intrabrachial bradykinin, acetylcholine, and sodium nitroprusside infusion. Hydrocortisone infusion had no effect on systemic concentrations of plasminogen activator inhibitor type 1 (PAI-1) or tissue plasminogen activator (t-PA; P = 0.10 and 0.95, respectively). Bradykinin caused a dose-dependent increase in plasma t-PA concentrations (P < 0.0001) that was unaffected by systemic hydrocortisone administration. Intrabrachial infusions of bradykinin, acetylcholine, and sodium nitroprusside all caused dose-dependent increases in forearm blood flow (P < 0.05) that were unaltered by hydrocortisone infusions. Short-term variations in plasma cortisol concentrations within the physiological range do not affect endothelial fibrinolytic or vasomotor function in healthy volunteers. These findings suggest that glucocorticoids do not exert acute effects on endothelial function in vivo in humans.

Inducible nitric oxide synthase activity does not contribute to the maintenance of peripheral vascular tone in patients with heart failure

Enhanced iNOS (inducible nitric oxide synthase) activity may contribute to vascular dysfunction in patients with heart failure. In the present study, we aimed to determine whether iNOS activity contributes to the maintenance of vascular tone in patients with symptomatic heart failure with the use of the highly selective iNOS inhibitor 1400W {N-[3-(aminomethyl)benzyl] acetamidine}. Bilateral forearm blood flow was measured using venous occlusion plethysmography in 12 patients with New York Heart Association class II-IV heart failure and eight matched healthy control subjects during intra-brachial infusion of 1400W (0.1-1 micromol/min), L-NMMA (N(G)-monomethyl-L-arginine; a non-selective NOS inhibitor; 2-8 micromol/min) and noradrenaline (control vasoconstrictor; 60-480 pmol/min). In both patients and controls, intra-brachial infusion of L-NMMA and noradrenaline caused a dose-dependent reduction in infused forearm blood flow (P<0.05 for both): peak reduction of 32+/-6% and 37+/-4% during L-NMMA and 52+/-6% and 49+/-5% during noradrenaline respectively (P values were not significant when patients were compared with controls). In contrast, 1400W had no effect on blood flow at 1 micromol/min [-3+/-4% in patients (95% confidence intervals, -11 to 5%) and 3+/-8% in controls; P value was not significant]. In conclusion, we have demonstrated that intrabrachial selective iNOS inhibition does not influence forearm blood flow in patients with heart failure. We conclude that iNOS activity does not contribute to peripheral vascular tone in patients with symptomatic heart failure.

Diagnosis of insulin autoimmune syndrome using polyethylene glycol precipitation and gel filtration chromatography with ex vivo insulin exchange.

Insulin‐binding antibodies may produce severe dysglycaemia in insulin‐naïve patients (‘insulin autoimmune syndrome’ (IAS) or Hirata disease), while rendering routine insulin assays unreliable.

Diurnal profile of interstitial glucose following dexamethasone prophylaxis for chemotherapy treatment of gynaecological cancer

Hyperglycaemia, a side‐effect of acute glucocorticoid exposure, is associated with poor outcome in those undergoing chemotherapy. The incidence, risk factors and diurnal profile of glucocorticoid‐induced glucose dysregulation in the context of chemotherapy treatment remain incompletely understood.

Predicting outcomes and complications following radioiodine therapy in Graves’ thyrotoxicosis

Radioiodine (RAI) is an effective treatment for Graves’ thyrotoxicosis but is associated with a failure rate of 15% and may be a risk factor for thyroid eye disease (TED) and weight gain. We sought to examine predictors of RAI failure, weight gain, TED and patient satisfaction.

Resolution of Hypoglycemia and Cardiovascular Dysfunction After Rituximab Treatment of Insulin Autoimmune Syndrome

D.C. is funded by a Diabetes Research & Wellness Foundation Sutherland-Earl Clinical Fellowship (RG68554). R.W.H. is supported by the Wellcome Trust–University of Edinburgh Institutional Strategic Support Fund. N.D. is supported by a British Heart Foundation Intermediate Clinical Research Fellowship (FS/13/30/29994). R.S. is funded by the Wellcome Trust (grant WT098498).

Inhibition or deletion of 11β-HSD1 does not increase angiogenesis in ischemic retinopathy.

Diabetes & Metabolism - In Press.Proof corrected by the author Available online since jeudi 12 janvier 2017