Vascular deficits contributing to skeletal fragility in type 1 diabetes.

Over 1 million Americans are currently living with T1D and improvements in diabetes management have increased the number of adults with T1D living into later decades of life. This growing population of older adults with diabetes is more susceptible to aging comorbidities, including both vascular disease and osteoporosis. Indeed, adults with T1D have a 2- to 3- fold higher risk of any fracture and up to 7-fold higher risk of hip fracture compared to those without diabetes. Recently, diabetes-related vascular deficits have emerged as potential risks factors for impaired bone blood flow and poor bone health and it has been hypothesized that there is a direct pathophysiologic link between vascular disease and skeletal outcomes in T1D. Indeed, microvascular disease (MVD), one of the most serious consequences of diabetes, has been linked to worse bone microarchitecture in older adults with T1D compared to their counterparts without MVD. The association between the presence of microvascular complications and compromised bone microarchitecture indicates the potential direct deleterious effect of vascular compromise, leading to abnormal skeletal blood flow, altered bone remodeling, and deficits in bone structure. In addition, vascular diabetic complications are characterized by increased vascular calcification, decreased arterial distensibility, and vascular remodeling with increased arterial stiffness and thickness of the vessel walls. These extensive alterations in vascular structure lead to impaired myogenic control and reduced nitric-oxide mediated vasodilation, compromising regulation of blood flow across almost all vascular beds and significantly restricting skeletal muscle blood flow seen in those with T1D. Vascular deficits in T1D may very well extend to bone, compromising skeletal blood flow control, and resulting in reduced blood flow to bone, thus negatively impacting bone health. Indeed, several animal and ex vivo human studies report that diabetes induces microvascular damage within bone are strongly correlated with diabetes disease severity and duration. In this review article, we will discuss the contribution of diabetes-induced vascular deficits to bone density, bone microarchitecture, and bone blood flow regulation, and review the potential contribution of vascular disease to skeletal fragility in T1D.

An Unexpected Case of Cutaneous Vasculitis Following Zoledronic Acid Infusion.

We report a case of isolated cutaneous small vessel vasculitis (SVV) occurring after zoledronic acid (Zol) infusion in a 58-year-old postmenopausal woman with a history of sleeve gastrectomy. This was the patient's first exposure to a bisphosphonate medication. Within minutes of the Zol infusion, she developed an episode of diffuse watery diarrhea. Although the diarrheal symptoms resolved quickly, she experienced nonsteroidal anti-inflammatory drug-responsive generalized myalgias and skin tenderness in her abdomen and extremities within a few hours. These symptoms progressed in severity over the next 5 days, and she developed nonblanching, palpable purpura extending from the ankles to the knees. Prior to Zol, labs showed sufficient 25-hydroxyvitamin D and calcium as well as normal renal and liver function. On day 10, laboratory tests revealed aspartate transaminase twice and alanine transaminase thrice the upper limit of normal. The patient was diagnosed with cutaneous SVV, with a timeline highly suggestive of an idiosyncratic reaction to Zol. She was successfully treated with a prednisone taper. No prior cases of Zol-induced cutaneous vasculitis have been reported, although there are a handful of reported cases of giant cell arteritis and urticarial vasculitis after bisphosphonate therapy. Clinicians should be aware that isolated cutaneous SVV may be a rare complication of Zol.

The PYY/Y2R-deficient male mouse is not protected from bone loss due to Roux-en-Y gastric bypass.

BACKGROUND: Peptide YY (PYY) is an anorexigenic gut hormone that also has anti-osteogenic effects, inhibiting osteoblastic activity and inducing catabolic effects. It has been postulated that increases in PYY after Roux-en-Y gastric bypass (RYGB) contribute to declines in bone mineral density (BMD) and increases in bone turnover. The aim of this study is to determine the role of the PYY Y2-receptor in mediating bone loss post-RYGB in mice. METHODS: We compared adult male wildtype (WT) and PYY Y2 receptor-deficient (KO) C57BL/6 mice that received RYGB (WT: n = 8; KO: n = 9), with sham-operated mice (Sham; WT: n = 9; KO: n = 10) and mice that were food-restricted to match the weights of the RYGB-treated group (Weight-Matched, WM; WT: n = 7; KO: n = 5). RYGB or sham surgery was performed at 15-16 weeks of age, and mice sacrificed 21 weeks later. We characterized bone microarchitecture with micro-computed tomography (µCT) at the distal femur (trabecular) and femoral midshaft (cortical). Differences in body weight, bone microarchitecture and biochemical bone markers (parathyroid hormone, PTH; C-telopeptide, CTX; and type 1 procollagen, P1NP) were compared using 2-factor ANOVA with Tukey's adjustments for multiple comparisons. RESULTS: Body weights were similar in the WT-RYGB, WT-WM, KO-RYGB, and KO-WM: 41-44 g; these groups weighed significantly less than the Sham surgery groups: 55-57 g. Trabecular BMD was 31-43 % lower in RYGB mice than either Sham or WM in WT and KO groups. This deficiency in trabecular bone was accompanied by a lower trabecular number (19 %-23 %), thickness (22 %-30 %) and increased trabecular spacing (25 %-34 %) in WT and KO groups (p < 0.001 for all comparisons vs. RYGB). RYGB led to lower cortical thickness, cortical tissue mineral density, and cortical bone area fraction as compared to Sham and WM in WT and KO groups (p ≤ 0.004 for all). There were no interactions between genotype and bone microarchitecture, with patterns of response to RYGB similar in both WT and KO groups. CTX and P1NP were significantly higher in RYGB mice than WM in WT and KO groups. PTH did not differ among groups. CONCLUSIONS: RYGB induced greater trabecular and cortical deficits and high bone turnover than observed in weight-matched mice, with a similar pattern in the WT and Y2RKO mice. Thus, skeletal effects of RYGB are independent of weight loss, and furthermore, PYY signaling through Y2R is not a key mediator of bone loss post-RYGB.

Continuous glucose monitoring reduces pubertal hyperglycemia of type 1 diabetes.

Background Physiologic hyperglycemia of puberty is a major contributor to poor glycemic control in youth with type 1 diabetes (T1D). This study's aim was to determine the effectiveness of continuous glucose monitoring (CGM) to improve glycemic control in pubertal youth with T1D compared to a non-CGM cohort after controlling for age, sex, BMI, duration, and insulin delivery methodology. The hypothesis is that consistent CGM use in puberty improves compliance with diabetes management, leading to increased percentage (%) time in range (TIR70-180 mg/dL) of glycemia, and lowering of HbA1c. Methods A longitudinal, retrospective, case-controlled study of 105 subjects consisting of 51 T1D controls (60.8% male) age 11.5 ± 3.8 y; and 54 T1D subjects (48.1% male) age 11.1 ± 5.0 y with confirmed CGM use for 12 months. Pubertal status was determined by Tanner staging. Results were adjusted for baseline HbA1c and diabetes duration. Results HbA1c was similar between the controls and the CGM group at baseline: 8.2 ± 1.1% vs 8.3 ± 1.2%, p=0.48 respectively; but was significantly lower in the CGM group 12 months later, 8.2 ± 1.1% vs. 8.7 ± 1.4%, p=0.035. Longitudinal change in HbA1c was similar in the prepubertal cohort between the control- and CGM groups: -0.17 ± 0.98% vs. 0.38 ± 1.5%, p=0.17. In contrast, HbA1c increased with advancing age and pubertal status in the pubertal controls but not in the pubertal CGM group: 0.55 ± 1.4 vs -0.22 ± 1.1%, p=0.020. Percent TIR was inversely related to HbA1c in the CGM group, r=-0.6, p=0.0004, for both prepubertal and pubertal subjects. Conclusions CGM use significantly improved glycemic control in pubertal youth with T1D compared to non-CGM users.

Specific alterations in complement protein activity of little brown myotis (Myotis lucifugus) hibernating in white-nose syndrome affected sites.

White-nose syndrome (WNS) is the most devastating condition ever reported for hibernating bats, causing widespread mortality in the northeastern United States. The syndrome is characterized by cutaneous lesions caused by a recently identified psychrophilic and keratinophylic fungus (Geomyces destructans), depleted fat reserves, atypical behavior, and damage to wings; however, the proximate cause of mortality is still uncertain. To assess relative levels of immunocompetence in bats hibernating in WNS-affected sites compared with levels in unaffected bats, we describe blood plasma complement protein activity in hibernating little brown myotis (Myotis lucifugus) based on microbicidal competence assays using Escherichia coli, Staphylococcus aureus and Candida albicans. Blood plasma from bats collected during mid-hibernation at WNS-affected sites had higher bactericidal ability against E. coli and S. aureus, but lower fungicidal ability against C. albicans when compared with blood plasma from bats collected at unaffected sites. Within affected sites during mid-hibernation, we observed no difference in microbicidal ability between bats displaying obvious fungal infections compared to those without. Bactericidal ability against E. coli decreased significantly as hibernation progressed in bats collected from an affected site. Bactericidal ability against E. coli and fungicidal ability against C. albicans were positively correlated with body mass index (BMI) during late hibernation. We also compared complement activity against the three microbes within individuals and found that the ability of blood plasma from hibernating M. lucifugus to lyse microbial cells differed as follows: E. coli>S. aureus>C. albicans. Overall, bats affected by WNS experience both relatively elevated and reduced innate immune responses depending on the microbe tested, although the cause of observed immunological changes remains unknown. Additionally, considerable trade-offs may exist between energy conservation and immunological responses. Relationships between immune activity and torpor, including associated energy expenditure, are likely critical components in the development of WNS.

Retrospective review of 331 consecutive immediate single-stage implant reconstructions with acellular dermal matrix: indications, complications, trends, and costs.

BACKGROUND: Immediate single-stage direct-to-implant breast reconstruction with acellular dermal matrix optimizes aesthetics by preserving the mastectomy skin envelope. The authors report trends, early complications, and costs. METHODS: A retrospective review of three surgeons' experience was performed for immediate single-stage implant reconstruction with acellular dermal matrix and tissue expander reconstruction without it at Massachusetts General Hospital. RESULTS: Two hundred eleven patients had 331 direct-to-implant reconstructions using AlloDerm following nipple-sparing (n = 66) or skin-sparing (n = 265) mastectomy for cancer (n = 216) or prophylaxis (n = 115). The number of single-stage implant reconstructions increased from seven in 2006 to 116 in 2009. The percentage performed for prophylaxis increased from 29 percent to 41 percent. Fifty-one patients underwent preoperative (n = 33) or postoperative (n = 18) irradiation. Total complications included 10 infections (3.0 percent), five seromas (1.5 percent), four hematomas (1.2 percent), and 30 reconstructions (9.1 percent), with skin necrosis leading to five implant losses (1.5 percent). Tissue expander reconstruction without AlloDerm had a similar total complication rate (158 reconstructions) (p = 0.18), including nine infections (5.7 percent), three seromas (1.9 percent), three hematomas (1.9 percent), and 16 reconstructions (10.1 percent), with skin necrosis leading to 11 implant losses (7.0 percent). A higher complication rate occurred in the surgeons' combined first year performing single-stage implant reconstruction (21.4 percent) compared with subsequent years (10.9 percent) (p < 0.02) and in one- or two-stage reconstruction patients undergoing irradiation (p = 0.005). There was no significant difference in total overall costs (p = 0.8). CONCLUSIONS: Immediate single-stage implant reconstruction using acellular dermal matrix offers a cost-effective reconstruction with a low complication rate. This may be the procedure of choice in select patients. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.