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Direct Evidence for Insulin-Induced Capillary Recruitment in Skin of Healthy Subjects During Physiological Hyperinsulinemia Erik H. Serné 1 2 , Richard G. IJzerman 1 2 , Reinold O.B. Gans 3 , Robin Nijveldt 1 , Greetje de Vries 1 , Reinder Evertz 1 , Ab J.M. Donker 1 2 and Coen D.A. Stehouwer 1 2 1 Department of Medicine, Academic Hospital Vrije Universiteit, Amsterdam, the Netherlands 2 Institute for Cardiovascular Research-Vrije Universiteit, Amsterdam, the Netherlands 3 Department of Medicine, University Hospital Groningen, Groningen, the Netherlands Abstract It has been proposed that insulin-mediated changes in muscle perfusion modulate insulin-mediated glucose uptake. However, the putative effects of insulin on the microcirculation that permit such modulation have not been studied in humans. We examined the effects of systemic hyperinsulinemia on skin microvascular function in eight healthy nondiabetic subjects. In addition, the effects of locally administered insulin on skin blood flow were assessed in 10 healthy subjects. During a hyperinsulinemic clamp, we measured leg blood flow with venous occlusion plethysmography, skin capillary density with capillaroscopy, endothelium-(in)dependent vasodilatation of skin microcirculation with iontophoresis of acetylcholine and sodium nitroprusside combined with laser Doppler fluxmetry, and skin vasomotion by Fourier analysis of microcirculatory blood flow. To exclude nonspecific changes in the hemodynamic variables, a time-volume control study was performed. Insulin iontophoresis was used to study the local effects of insulin on skin blood flow. Compared to the control study, systemic hyperinsulinemia caused an increase in leg blood flow (−0.54 ± 0.93 vs. 1.97 ± 1.1 ml · min −1 · dl −1 ; P < 0.01), an increase in the number of perfused capillaries in the resting state (−3.7 ± 3.0 vs. 3.4 ± 1.4 per mm 2 ; P < 0.001) and during postocclusive reactive hyperemia (−0.8 ± 2.2 vs. 5.1 ± 3.7 per mm 2 ; P < 0.001), an augmentation of the vasodilatation caused by acetylcholine (722 ± 206 vs. 989 ± 495%; P < 0.05) and sodium nitroprusside (618 ± 159 vs. 788 ± 276%; P < 0.05), and a change in vasomotion by increasing the relative contribution of the 0.01- to 0.02-Hz and 0.4- to 1.6-Hz spectral components ( P < 0.05). Compared to the control substance, locally administered insulin caused a rapid increase (∼13.5 min) in skin microcirculatory blood flow (34.4 ± 42.5 vs. 82.8 ± 85.7%; P < 0.05). In conclusion, systemic hyperinsulinemia in skin 1 ) induces recruitment of capillaries, 2 ) augments nitric oxide−mediated vasodilatation, and 3 ) influences vasomotion. In addition, locally administered insulin 4 ) induces a rapid increase in total skin blood flow, independent of systemic effects. Footnotes Address correspondence and reprint requests to Dr. C.D.A. Stehouwer, Department of Medicine, Academic Hospital Vrije Universiteit, De Boelelaan 1117, P.O. Box 5057, 1007 MB, Amsterdam, the Netherlands. E-mail: cda.stehouwer{at}vumc.nl . Received for publication 17 January 2001 and accepted in revised form 15 February 2002. CV, coefficient of variation; DBP, diastolic blood pressure; M, whole-body glucose uptake; MAP, mean arterial pressure; M/I, whole-body glucose uptake per unit of plasma insulin concentration; PRH, postocclusive reactive hyperemia; PU, arbitrary perfusion units. DIABETES

Free Fatty Acid Levels Modulate Microvascular Function Relevance for Obesity-Associated Insulin Resistance, Hypertension, and Microangiopathy Renate T. de Jongh 1 , Erik H. Serné 1 , Richard G. IJzerman 1 , Greetje de Vries 1 and Coen D.A. Stehouwer 1 2 1 Department of Internal Medicine and Institute for Cardiovascular Research, Vrije Universiteit University Medical Center, Amsterdam, the Netherlands 2 Department of Internal Medicine and Cardiovascular Research Institute Maastricht, Maastricht University Hospital, Maastricht, the Netherlands Address correspondence and reprint requests to Prof. Dr. Coen D.A. Stehouwer, Department of Medicine, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, Netherlands. E-mail: cda.stehouwer{at}vumc.nl Abstract To test the hypothesis that free fatty acids (FFAs) modulate microvascular function and that this contributes to obesity-associated insulin resistance, hypertension, and microangiopathy, we examined the effects of both FFA elevation in lean women and FFA lowering in obese women on skin microvascular function. A total of 16 lean and 12 obese women underwent, respectively, Intralipid plus heparin (or saline) infusion and overnight acipimox (or placebo) treatment. We measured capillary recruitment with capillaroscopy and endothelium-(in)dependent vasodilation by iontophoresis of acetylcholine and sodium nitroprusside before and during hyperinsulinemia (40 mU · m −2 · min −1 ). FFA elevation impaired capillary recruitment and acetylcholine-mediated vasodilation before (44.6 ± 16.8 vs. 56.9 ± 18.9%, P < 0.05; and 338 ± 131 vs. 557 ± 162%, P < 0.01, respectively) and during (54.0 ± 21.3 vs. 72.4 ± 25.4%, P < 0.01; and 264 ± 186 vs. 685 ± 199%, P < 0.01, respectively) hyperinsulinemia. FFA lowering improved capillary recruitment before (50.9 ± 14.6 vs. 37.4 ± 9.3%, P < 0.01) and during (66.8 ± 20.6 vs. 54.8 ± 15.4%, P < 0.05) hyperinsulinemia. Changes in FFA levels were inversely associated with changes in capillary recruitment and insulin sensitivity in lean ( r = −0.46, P = 0.08; and r = −0.56, P = 0.03) and in obese ( r = −0.70, P = 0.02; and r = −0.62, P = 0.04) women. Regression analyses showed that changes in capillary recruitment statistically explained ∼29% of the association between changes in FFA levels and insulin sensitivity. In conclusion, FFA levels modulate microvascular function and may contribute to obesity-associated insulin resistance, hypertension, and microangiopathy. FFA, free fatty acid PI, phosphatidylinositol Footnotes Accepted August 6, 2004. Received May 20, 2004. DIABETES

To test the hypothesis that free fatty acids (FFAs) modulate microvascular function and that this contributes to obesity-associated insulin resistance, hypertension, and microangiopathy, we examined the effects of both FFA elevation in lean women and FFA lowering in obese women on skin microvascular function. A total of 16 lean and 12 obese women underwent, respectively, Intralipid plus heparin (or saline) infusion and overnight acipimox (or placebo) treatment. We measured capillary recruitment with capillaroscopy and endothelium-(in)dependent vasodilation by iontophoresis of acetylcholine and sodium nitroprusside before and during hyperinsulinemia (40 mU . m(-2) . min(-1)). FFA elevation impaired capillary recruitment and acetylcholine-mediated vasodilation before (44.6 +/- 16.8 vs. 56.9 +/- 18.9%, P < 0.05; and 338 +/- 131 vs. 557 +/- 162%, P < 0.01, respectively) and during (54.0 +/- 21.3 vs. 72.4 +/- 25.4%, P < 0.01; and 264 +/- 186 vs. 685 +/- 199%, P < 0.01, respectively) hyperinsulinemia. FFA lowering improved capillary recruitment before (50.9 +/- 14.6 vs. 37.4 +/- 9.3%, P < 0.01) and during (66.8 +/- 20.6 vs. 54.8 +/- 15.4%, P < 0.05) hyperinsulinemia. Changes in FFA levels were inversely associated with changes in capillary recruitment and insulin sensitivity in lean (r = -0.46, P = 0.08; and r = -0.56, P = 0.03) and in obese (r = -0.70, P = 0.02; and r = -0.62, P = 0.04) women. Regression analyses showed that changes in capillary recruitment statistically explained approximately 29% of the association between changes in FFA levels and insulin sensitivity. In conclusion, FFA levels modulate microvascular function and may contribute to obesity-associated insulin resistance, hypertension, and microangiopathy.

Obese patients are more likely to develop periprosthetic joint infection (PJI) after primary total joint arthroplasty. This study compared the clinical and microbiological characteristics of non-obese, obese and severely obese patients with early PJI, in order to ultimately optimize antibiotic prophylaxis and other prevention measures for this specific patient category. We retrospectively evaluated patients with early PJI of the hip and knee treated with debridement, antibiotics and implant retention (DAIR) between 2006 and 2016 in three Dutch hospitals. Only patients with primary arthroplasties indicated for osteoarthritis were included. Early PJI was defined as an infection that developed within 90 days after index surgery. Obesity was defined as a BMI ≥30kg/m2 and severe obesity as a BMI ≥35kg/m2. A total of 237 patients were analyzed, including 64 obese patients (27.0%) and 62 severely obese patients (26.2%). Compared with non-obese patients, obese patients had higher rates of polymicrobial infections (60.3% vs 33.3%, p<0.001) with more often involvement of Enterococcus species (27.0% vs 11.7%, p = 0.003). Moreover, severely obese patients had more Gram-negative infections, especially with Proteus species (12.9% vs 2.3%, p = 0.001). These results were only found in periprosthetic hip infections, comprising Gram-negative PJIs in 34.2% of severely obese patients compared with 24.7% in obese patients and 12.7% in non-obese patients (p = 0.018). Our results demonstrate that obese patients with early periprosthetic hip infections have higher rates of polymicrobial infections with enterococci and Gram-negative rods, which stresses the importance of improving preventive strategies in this specific patient category, by adjusting antibiotic prophylaxis regimens, improving disinfection strategies and optimizing postoperative wound care.

Background: Iron deficiency (ID) and anemia in patients with Inflammatory Bowel Disease (IBD) are associated with a reduced quality of life. We assessed the prevalence of ID and anemia in Dutch outpatients with IBD and compared routine ID(A) management among medical professionals to the European Crohn’s and Colitis Organisation (ECCO) treatment guidelines. Methods: Between January and November 2021, consecutive adult outpatients with IBD were included in this study across 16 Dutch hospitals. Clinical and biochemical data were extracted from medical records. Additionally, medical professionals filled out questionnaires regarding routine ID(A) management. Results: In total, 2197 patients (1271 Crohn’s Disease, 849 Ulcerative Colitis, and 77 IBD-unclassified) were included. Iron parameters were available in 59.3% of cases. The overall prevalence of anemia, ID, and IDA was: 18.0%, 43.4%, and 12.2%, respectively. The prevalence of all three conditions did not differ between IBD subtypes. ID(A) was observed more frequently in patients with biochemically active IBD than in quiescent IBD (ID: 70.8% versus 23.9%; p < 0.001). Contrary to the guidelines, most respondents prescribed standard doses of intravenous or oral iron regardless of biochemical parameters or inflammation. Lastly, 25% of respondents reported not treating non-anemic ID. Conclusions: One in five patients with IBD suffers from anemia that—despite inconsistently measured iron parameters—is primarily caused by ID. Most medical professionals treat IDA with oral iron or standard doses of intravenous iron regardless of biochemical inflammation; however, non-anemic ID is often overlooked. Raising awareness about the management of ID(A) is needed to optimize and personalize routine care.