Increased SGLT1 expression in salivary gland ductal cells correlates with hyposalivation in diabetic and hypertensive rats

Abstract Background: Oral health complications in diabetes and hypertension include decreased salivary secretion. The sodium-glucose cotransporter 1 (SGLT1) protein, which transports 1 glucose/2 Na+/264 H2O molecules, is described in salivary glands. We hypothesized that changes in SGLT1 expression in the luminal membrane of ductal cell may be related to an altered salivary flow. Findings: By immunohistochemistry, we investigated SGLT1 expression in ductal cells of parotid and submandibular glands from Wistar Kyoto rats (WKY), diabetic WKY (WKY-D), spontaneously hypertensive rats (SHR) and diabetic SHR (SHR-D), as well as in parotid glands from WKY subjected to sympathetic stimulation, with or without previous propranolol blockade. Diabetes and hypertension decreased the salivary secretion and increased SGLT1 expression in the luminal membrane of ductal cells, and their association exacerbated the regulations observed. After 30 min of sympathetic stimulation, SGLT1 increased in the luminal membrane of ductal cells, and that was blocked by previous injection of propranolol. Conclusions: SGLT1 expression increases in the luminal membrane of salivary gland ductal cells and the salivary flow decreases in diabetic and hypertensive rats, which may be related to sympathetic activity. This study highlights the water transporter role of SGLT1 in salivary glands, which, by increasing ductal water reabsorption, may explain the hyposalivation of diabetic and hypertensive subjects.

A survey of owner attitudes and experiences in managing diabetic dogs

A survey of the experiences of owners of diabetic dogs was carried out by distributing questionnaires to veterinary clinics in São Paulo, Brazil. A total of 93 dog owners were surveyed over a 4 month period and descriptive statistical analysis, frequency distribution and correlations were performed. In most cases the clinical condition of the dogs had improved following treatment and owners were largely satisfied with veterinary intervention. Injection of neutral protamine hagedorm twice daily was the most commonly prescribed treatment and respondents found this procedure easy to perform, although it did pose some difficulties when the owners were away from their animals. Cost was considered an important factor at the initiation of treatment programs. The information gleaned from this survey, in providing useful insights into the attitudes and experiences of owners of diabetic animals, will contribute to improvements in the treatment and management of such patients.

Hepatocyte nuclear factors 1α/4α and forkhead box A2 regulate the solute carrier 2A2 (Slc2a2) gene expression in the liver and kidney of diabetic rats

AIMS: Solute carrier 2a2 (Slc2a2) gene codifies the glucose transporter GLUT2, a key protein for glucose flux in hepatocytes and renal epithelial cells of proximal tubule. In diabetes mellitus, hepatic and tubular glucose output has been related to Slc2a2/GLUT2 overexpression; and controlling the expression of this gene may be an important adjuvant way to improve glycemic homeostasis. Thus, the present study investigated transcriptional mechanisms involved in the diabetes-induced overexpression of the Slc2a2 gene. MAIN METHODS: Hepatocyte nuclear factors 1α and 4α (HNF-1α and HNF-4α), forkhead box A2 (FOXA2), sterol regulatory element binding protein-1c (SREBP-1c) and the CCAAT-enhancer-binding protein (C/EBPβ) mRNA expression (RT-PCR) and binding activity into the Slc2a2 promoter (electrophoretic mobility assay) were analyzed in the liver and kidney of diabetic and 6-day insulin-treated diabetic rats. KEY FINDINGS: Slc2a2/GLUT2 expression increased by more than 50% (P<0.001) in the liver and kidney of diabetic rats, and 6-day insulin treatment restores these values to those observed in non-diabetic animals. Similarly, the mRNA expression and the binding activity of HNF-1α, HNF-4α and FOXA2 increased by 50 to 100% (P<0.05 to P<0.001), also returning to values of non-diabetic rats after insulin treatment. Neither the Srebf1 and Cebpb mRNA expression, nor the SREBP-1c and C/EBP-β binding activity was altered in diabetic rats. SIGNIFICANCE: HNF-1α, HNF-4α and FOXA2 transcriptional factors are involved in diabetes-induced overexpression of Slc2a2 gene in the liver and kidney. These data point out that these transcriptional factors are important targets to control GLUT2 expression in these tissues, which can contribute to glycemic homeostasis in diabetes.

Increased SGLT1 expression in salivary gland ductal cells correlates with hyposalivation in diabetic and hypertensive rats

Background Oral health complications in diabetes and hypertension include decreased salivary secretion. The sodium-glucose cotransporter 1 (SGLT1) protein, which transports 1 glucose/2 Na+/264 H2O molecules, is described in salivary glands. We hypothesized that changes in SGLT1 expression in the luminal membrane of ductal cell may be related to an altered salivary flow. Findings By immunohistochemistry, we investigated SGLT1 expression in ductal cells of parotid and submandibular glands from Wistar Kyoto rats (WKY), diabetic WKY (WKY-D), spontaneously hypertensive rats (SHR) and diabetic SHR (SHR-D), as well as in parotid glands from WKY subjected to sympathetic stimulation, with or without previous propranolol blockade. Diabetes and hypertension decreased the salivary secretion and increased SGLT1 expression in the luminal membrane of ductal cells, and their association exacerbated the regulations observed. After 30 min of sympathetic stimulation, SGLT1 increased in the luminal membrane of ductal cells, and that was blocked by previous injection of propranolol. Conclusions SGLT1 expression increases in the luminal membrane of salivary gland ductal cells and the salivary flow decreases in diabetic and hypertensive rats, which may be related to sympathetic activity. This study highlights the water transporter role of SGLT1 in salivary glands, which, by increasing ductal water reabsorption, may explain the hyposalivation of diabetic and hypertensive subjects

Renal GLUT1 reduction depends on angiotensin-converting enzyme inhibition in diabetic hypertensive rats

Aims: Angiotensin-converting enzyme (ACE) inhibitors are used in diabetic kidney disease to reduce systemic/intra-glomerular pressure. The objective of this study was to investigate whether reducing blood pressure (BP) could modulate renal glucose transporter expression, and urinary markers of diabetic nephropathy in diabetic hypertensive rats treated with ramipril or amlodipine. Main methods: Diabetes was induced in spontaneously-hypertensive rats (~210 g) by streptozotocin (50 mg/kg). Thirty days later, animals received ramipril 15 μg/kg/day (R, n =10), or amlodipine 10 mg/kg/day (A, n= 8,) or water (C, n = 10) by gavage. After 30-day treatment, body weight, glycaemia, urinary albumin and TGF-β1 (enzyme-linked immunosorbent assay) and BP (tail-cuff pressure method) were evaluated. Kidneys were removed for evaluation of renal cortex glucose transporters (Western blotting) and renal tissue ACE activity (fluorometric assay). Key findings: After treatments, body weight (p = 0.77) and glycaemia (p = 0.22) were similar among the groups. Systolic BP was similarly reduced (p < 0.001) in A and R vs. C (172.4 ± 3.2; 186.7 ± 3.7 and 202.2 ± 4.3 mm Hg; respectively). ACE activity (C: 0.903 ± 0.086; A: 0.654 ± 0.025, and R: 0.389 ± 0.057 mU/mg), albuminuria (C: 264.8 ± 15.4; A: 140.8 ± 13.5 and R: 102.8 ± 6.7 mg/24 h), and renal cortex GLUT1 content (C: 46.81 ± 4.54; A: 40.30 ± 5.39 and R: 26.89 ± 0.79 AU) decreased only in R (p < 0.001, p < 0.05 and p < 0.001; respectively). Significance:We concluded that the blockade of the renin–angiotensin systemwith ramipril reduced earlymarkers of diabetic nephropathy, a phenomenon that cannot be specifically related to decreased BP levels.

Metabolic control of type 1 diabetic patients followed at the University Children's Hospital in Berne: Have we reached the goal?

In type 1 diabetes (T1DM), a good metabolic control is important to reduce and/or postpone complications. Guidelines regarding how to achieve this goal are published by the American Diabetes Association (ADA) and the International Society of Paediatric and Adolescence Diabetes (ISPAD). The aims of this study were to determine the current level of metabolic control in T1DM patients on different treatment regimens, followed at the diabetes outpatient unit of the University Children's Hospital Bern, Switzerland, and to compare it with both the reported data from ten years ago (1998) and with the current guidelines of the ADA and ISPAD.

Retinal overexpression of angiopoietin-2 mimics diabetic retinopathy and enhances vascular damages in hyperglycemia

Our previous data suggested that angiopoietin-2 (Ang-2) is linked to pericyte loss, thereby playing an important role in diabetic retinopathy. In this study, we investigated the effect of retinal overexpression of human Ang-2 (mOpsinhAng2 mouse) on vascular morphology in non-diabetic and streptozotozin-induced diabetic animals. Pericyte (PC) coverage and acellular capillary (AC) formation were quantitated in retinal digest preparations after 3 and 6 months of diabetes duration. The degree of retinopathy in non-diabetic mOpsinhAng2 mice at 3 months (-21% PC, +49% AC) was comparable to age-matched diabetic wild type mice. Diabetic mOpsinhAng2 mice exhibited significantly worse vascular pathology than wild type counterparts at 6 months. Quantitative PCR revealed that human Ang-2 mRNA was highly overexpressed in retinas of transgenic mice. Our data demonstrate that overexpression of Ang-2 in the retina enhances vascular pathology, indicating that Ang-2 plays an essential role in diabetic vasoregression via destabilization of pericytes.

[Right-sided lower abdominal pain and diarrhea of a young diabetic woman]

We report the case of a 24-years old diabetic women hospitalised because of right-sided lower abdominal pain and diarrhea. She fulminantly developed shock before appendectomy could be performed and was transferred to intensive care unit. Hypotension remained and laparoscopy revealed primary peritonitis and toxic shock syndrome by Group A Streptococcus which was cultivated in blood and ascites. Therapy with penicilline and clindamycine resolved symptoms. During hospitalisation Clostridium difficile colitis occurred. This complication leaded to prolonged hospitalisation.

Safety and Efficacy of Ranibizumab in Diabetic Macular Edema (RESOLVE Study): A 12-month, randomized, controlled, double-masked, multicenter phase II study

The expression of vascular endothelial growth factor (VEGF) is elevated in diabetic macular edema (DME). Ranibizumab binds to and inhibits multiple VEGF variants. We investigated the safety and efficacy of ranibizumab in DME involving the foveal center.

Plaque characteristics of nonobstructive coronary lesions in diabetic patients: an intravascular ultrasound virtual histology analysis

Patients with diabetes mellitus are known to be at increased risk for acute cardiovascular events. We used intravascular ultrasound virtual histology (IVUS-VH) to examine whether nonobstructive coronary artery lesions of diabetic patients have distinct plaque composition and morphology compared with nondiabetic patients.

Delayed osteoblast differentiation and altered inflammatory response around implants placed in incisor sockets of type 2 diabetic rats

Objective: Central to the process of osseointegration is the recruitment of mesenchymal progenitor cells to the healing site, their proliferation and differentiation to bone synthesising osteoblasts. The process is under the control of pro-inflammatory cytokines and growth factors. The aim of this study was to monitor these key stages of osseointegration and the signalling milieu during bone healing around implants placed in healthy and diabetic bone. Methods: Implants were placed into the sockets of incisors extracted from the mandibles of normal Wistar and diabetic Goto-Kakizaki rats. Mandibles 1-12 weeks post-insertion of the implant were examined by histochemistry and immunocytochemistry to localise the presence of Stro-1- positive mesenchymal progenitor cells, proliferating cellular nuclear antigen proliferative cells, osteopontin and osteocalcin, macrophages, pro-inflammatory cytokines interleukin (IL)-1 , IL-6, tumour necrosis factor (TNF)- and tumour growth factor (TGF)- 1. Image analysis provided a semi-quantification of positively expressing cells. Results: Histological staining identified a delay in the formation of mineralised bone around implants placed in diabetic animals. Within the diabetic bone, the migration of Stro-1 mesenchymal cells in the healing tissue appeared to be unaffected. However, in the diabetic healing bone, the onset of cell proliferation and osteoblast differentiation were delayed and subsequently prolonged compared with normal bone. Similar patterns of change were observed in diabetic bone for the presence of IL-1 , TNF- , macrophages and TGF- 1. Conclusion: The observed alterations in the extracellular presence of pro-inflammatory cytokines, macrophages and growth factors within diabetic tissues that correlate to changes in the signalling milieu, may affect the proliferation and differentiation of mesenchymal progenitor cells in the osseointegration process. To cite this article: Colombo JS, Balani D, Sloan AJ, St Crean J, Okazaki J, Waddington RJ. Delayed osteoblast differentiation and altered inflammatory response around implants placed in incisor sockets of type 2 diabetic rats Clin. Oral Impl. Res22, 2011; 578-586 doi: 10.1111/j.1600-0501.2010.01992.x.

Predicting the pathogen of diabetic toe osteomyelitis by two consecutive ulcer cultures with bone contact

In this study, we investigate the accuracy of two consecutive ulcer cultures with bone contact compared to bone biopsy for the diagnosis of diabetic toe osteomyelitis. The same nurse and orthopaedic surgeon obtained all samples: sample A-1: bone contact swabbing through the ulcer; sample A-2: a second culture swabbing from the bone surface within 24 h; sample B: surgical bone biopsy in the operating theatre. The kappa statistic measure between samples A-1 and A-2 (bone contact swabs) indicated 82.35% agreement. The sensitivity, specificity, positive and negative predictive values of the two samples A compared to B were 96%, 79%, 92% and 88%, respectively, for the causative pathogen. These results were similar with prior antibiotic treatment, discordant bone surface swabs or with monomicrobial infections. As a conclusion, two consecutive diabetic toe cultures with bone contact accurately predict the pathogen of diabetic toe osteomyelitis in 90% of cases.

Chapter V: Diabetic foot

Ulcerated diabetic foot is a complex problem. Ischaemia, neuropathy and infection are the three pathological components that lead to diabetic foot complications, and they frequently occur together as an aetiologic triad. Neuropathy and ischaemia are the initiating factors, most often together as neuroischaemia, whereas infection is mostly a consequence. The role of peripheral arterial disease in diabetic foot has long been underestimated as typical ischaemic symptoms are less frequent in diabetics with ischaemia than in non-diabetics. Furthermore, the healing of a neuroischaemic ulcer is hampered by microvascular dysfunction. Therefore, the threshold for revascularising neuroischaemic ulcers should be lower than that for purely ischaemic ulcers. Previous guidelines have largely ignored these specific demands related to ulcerated neuroischaemic diabetic feet. Any diabetic foot ulcer should always be considered to have vascular impairment unless otherwise proven. Early referral, non-invasive vascular testing, imaging and intervention are crucial to improve diabetic foot ulcer healing and to prevent amputation. Timing is essential, as the window of opportunity to heal the ulcer and save the leg is easily missed. This chapter underlines the paucity of data on the best way to diagnose and treat these diabetic patients. Most of the studies dealing with neuroischaemic diabetic feet are not comparable in terms of patient populations, interventions or outcome. Therefore, there is an urgent need for a paradigm shift in diabetic foot care; that is, a new approach and classification of diabetics with vascular impairment in regard to clinical practice and research. A multidisciplinary approach needs to implemented systematically with a vascular surgeon as an integrated member. New strategies must be developed and implemented for diabetic foot patients with vascular impairment, to improve healing, to speed up healing rate and to avoid amputation, irrespective of the intervention technology chosen. Focused studies on the value of predictive tests, new treatment modalities as well as selective and targeted strategies are needed. As specific data on ulcerated neuroischaemic diabetic feet are scarce, recommendations are often of low grade.

Long-term clinical and angiographic outcomes of diabetic patients after revascularization with early generation drug-eluting stents

Early generation drug-eluting stents (DESs) reduce restenosis and repeat revascularization procedures. However, the long-term safety and efficacy of early generation DES according to diabetic status are poorly established.

Behavior of SD-OCT-detected hyperreflective foci in the retina of anti-VEGF-treated patients with diabetic macular edema

Hyperreflective foci (HFs) are observable within the neurosensory retina in diabetic macular edema (DME) using spectral domain optical coherence tomography (SD-OCT). HFs have also been seen in wet age-related macular degeneration (AMD), although the origin is still unknown; however, they reduced significantly during anti-VEGF (vascular endothelial growth factor) therapy, and their baseline amount seemed to correlate with treatment success. In this study the behavior of HFs was evaluated during anti-VEGF therapy for DME.