Management of canine diabetes

The majority of diabetic dogs appear to have a form of type 1 diabetes analogous to the latent autoimmune diabetes of adults (LADA) in humans. Evidence of acute or chronic pancreatitis occurs in about 40% of diabetic dogs. Blindness caused by cataract formation eventually occurs in the majority of diabetic dogs and is not dependent on glycemic control. Insulin is the mainstay of therapy for diabetic dogs, and a conservative approach to insulin therapy is crucial. Most diabetic dogs require twice-daily dosing with lente or NPH insulin to adequately control their clinical signs. The diet fed should primarily be palatable and nutritionally balanced. Improved glycemic control may be achieved in some dogs if the diet contains increased insoluble fiber.

IRS-1 regulation in health and disease

The global incidence of diabetes is increasing at epidemic rates. Estimates suggest there are currently 150 million people with diabetes and this number is expected to double in the next 20 years. Type 2 diabetes accounts for 95% of all cases and is characterized in part by impaired sensitivity to insulin or 'insulin resistance'. Defects in the insulin signalling pathways underpin this resistance. In the current article we discuss the regulation of Insulin Receptor Substrate-1 (IRS-1), a protein that plays a pivotal role in insulin signalling and whose function is impaired in subjects with insulin resistance. Coordination of IRS-1 function is multi-faceted, involving phosphorylation of IRS-1 at multiple serine/threonine residues. This controls many aspects of IRS-1, including its interaction with the insulin receptor and subsequent tyrosine phosphorylation, as well as its subcellular distribution and targeting for degradation by the proteasome. Such tight control ensures appropriate transduction and attenuation of the insulin signal, thereby regulating insulin action in healthy individuals. Emerging evidence indicates that `diabetogenic factors' associated with insulin resistance, such as TNFalpha and elevated circulating fatty acids, impact on insulin signalling at the level of IRS-1 serine/threonine phosphorylation. The expression and/or activity of several kinases, such as IkappaB kinase beta (IKKbeta) and salt-induced kinase 2 (SIK2), and the phosphorylation of IRS-1 at key sites, such as Ser307 and Ser789, are increased in states of insulin resistance. Identifying the pathways by which such factors activate these and other kinases, and de. ning the precise roles of specific serine/threonine phosphorylation events in IRS-1 regulation, represent important goals which may eventually provide a rationale for therapeutic intervention.

Use of umbilical artery Doppler velocimetry in the monitoring of pregnancy in women with pre-existing diabetes

Background: The usefulness of umbilical artery Doppler velocimetry for the monitoring of diabetic pregnancies is controversial. The aim of the present study was to assess whether umbilical artery Doppler velocity waveform analysis can predict adverse perinatal outcomes for pregnancies complicated by pre-existing diabetes mellitus. Methods: All diabetic pregnancies (type 1 and 2) delivered at Mater Mothers' Hospital, Queensland, between 1 January 1995 and 31 December 1999 were included. All pregnant diabetic women were monitored with umbilical artery Doppler velocimetry at 28, 32, 36, and 38 weeks' gestation. Adverse perinatal outcome was defined as pregnancies with one or more of the following: small-for-gestational age, Caesarean section for non-reassuring cardiotocography, fetal acidaemia at delivery, 1-min Apgar of 3 or less, 5-min Apgar of less than 7, hypoxic ischaemic encephalopathy or perinatal death. Abnormal umbilical artery Doppler velocimetry was defined as a pulsatility index of 95th centile or higher for gestation. Results: One hundred and four pregnancies in women with pre-existing diabetes had umbilical arterial Doppler studies carried out during the study period. Twenty-three pregnancies (22.1%) had an elevated pulsatility index. If the scans were carried out within 2 weeks of delivery, 71% of pregnancies with abnormal umbilical Doppler had adverse outcomes (P < 0.01; likelihood ratio, 4.2). However, the sensitivity was 35%; specificity was 94%; positive predictive value was 80%; and negative predictive value was 68%. Only 30% of women with adverse perinatal outcomes had abnormal umbilical arterial Doppler flow. Conclusion: Umbilical artery Doppler velocimetry is not a good predictor of adverse perinatal outcomes in diabetic pregnancies.

Canine and Feline Diabetes Mellitus: Nature or Nurture?

There is evidence for the role of genetic and environmental factors in feline and canine diabetes. Type 2 diabetes is the most common form of diabetes in cats. Evidence for genetic factors in feline diabetes includes the overrepresentation of Burmese cats with diabetes. Environmental risk factors in domestic or Burmese cats include advancing age, obesity, male gender, neutering, drug treatment, physical inactivity, and indoor confinement. High-carbohydrate diets increase blood glucose and insulin levels and may predispose cats to obesity and diabetes. Low-carbohydrate, high-protein diets may help prevent diabetes in cats at risk such as obese cats or lean cats with underlying low insulin sensitivity. Evidence exists for a genetic basis and altered immune response in the pathogenesis of canine diabetes. Seasonal effects on the incidence of diagnosis indicate that there are environmental influences on disease progression. At least 50% of diabetic dogs have type 1 diabetes based on present evidence of immune destruction of P-cells. Epidemiological factors closely match those of the latent autoimmune diabetes of adults form of human type 1 diabetes. Extensive pancreatic damage, likely from chronic pancreatitis, causes similar to28% of canine diabetes cases. Environmental factors such as feeding of high-fat diets are potentially associated with pancreatitis and likely play a role in the development of pancreatitis in diabetic dogs. There are no published data showing that overt type 2 diabetes occurs in dogs or that obesity is a risk factor for canine diabetes. Diabetes diagnosed in a bitch during either pregnancy or diestrus is comparable to human gestational diabetes.

E2F-1 induces proliferation-specific genes and suppresses squamous differentiation-specific genes in human epidermal keratinocytes

Squamous differentiation of keratinocytes is associated with decreases in E2F-1 mRNA expression and E2F activity, and these processes are disrupted in squamous cell carcinoma cell lines. We now show that E2F-1 mRNA expression is increased in primary squamous cell carcinomas of the skin relative to normal epidermis, To explore the relationship between E2F-1 and squamous differentiation further, we examined the effect of altering E2F activity in primary human keratinocytes induced to differentiate. Promoter activity for the proliferation-associated genes, cdc2 and keratin 14, are inhibited during squamous differentiation. This inhibition can be inhibited by overexpression of E2F-1 in keratinocytes, Overexpression of E2F-1 also suppressed the expression of differentiation markers (transglutaminase type 1 and keratin 10) in differentiated keratinocytes, Blocking E2F activity by transfecting proliferating keratinocytes with dominant negative E2F-1 constructs inhibited the expression of cdc2 and E2F-1, but did not induce differentiation. Furthermore, expression of the dominant negative construct in epithelial carcinoma cell lines and normal keratinocytes decreased expression from the cdc2 promoter. These data indicate that E2F-1 promotes keratinocyte proliferation-specific marker genes and suppresses squamous differentiation-specific marker genes. Moreover, these data indicate that targeted disruption of E2F-1 activity may have therapeutic potential for the treatment of squamous carcinomas.

Association between HIV-1 infection, the etiology of genital ulcer disease, and response to syndromic management

Background: Reports on the effect of HIV-1 infection on healing rates of ulcers are conflicting. Goal: The goal was to determine the etiology and response to treatment of genital ulcer disease (GUD) in relation to HIV-1 infection. Study Design: This was a cohort study of patients with GUD treated with local syndromic management protocols. Results: Among the 587 recruited, the prevalences of infections due to HSV, Treponema pallidum, Chlamydia trachomatis (lymphogranuloma venereum [LGV]), Haemophilus ducreyi, Calymmatobacterium granulomatis, and HIV-1 were 48%, 14%, 11%, 10%, 1%, and 75%, respectively. The prevalence of T pallidum was higher among men (P = 0.03), and an association was seen among HIV-1-seronegatives on univariate and multivariate analyses (P < 0.001; P = 0.01). The prevalence of C trachomatis (LGV) was higher among females (P = 0.004), and an association was seen among HIV-1-seropositives on univariate analysis (P = 0.04). At follow-up, 40/407 (10%) showed a decreased healing tendency, not associated with ulcer etiology or HIV-1 seropositivity. Conclusion: Response to syndromic management of GUD was acceptable and not associated with HIV-1 coinfection.

Polymorphisms of the renin-angiotensin system in patients with multifocal renal arterial fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is an important cause of renal artery stenosis, particularly in young females. Polymorphisms of the renin-angiotensin (RA) system have been implicated in the pathogenesis of hypertension and atherosclerotic vascular disease, and may play a role in the development of FMD. Examination of polymorphisms by PCR for angiotensin-converting enzyme (ACE) I/D, angiotensin II type 1 receptor (AT(1)R) A1166C and angiotensinogen (AGT) M235T and T174M was undertaken in 43 patients with typical multifocal renal arterial FMD (MF-FMD) and in 89 controls. The age of NIF-FMD patients at the time of diagnosis of hypertension did not differ (38.6 + 11.1 years vs 35.5 +/- 10.3 years, P = 0.12) from controls and the proportion (95% vs 86%, P = 0.14) of females was similar. Allele frequencies did not differ significantly between groups, except that MF-FMD patients had a significantly higher frequency of the ACE I allele than control subjects (0.62 vs 0.47, P = 0.026). Since the ACE I allele is associated with lower circulating ACE levels and possibly lower tissue levels of angiotensin II (Ang II), and since Ang II modulates vascular smooth muscle cell growth and synthetic activity, the I allele might predispose to defective remodelling of the arterial media, and thus to the development of MF-FMD. This contrasts with atherosclerotic renal artery stenosis, coronary stent restenosis and carotid intimal thickening, which are diseases affecting the arterial intima, and which are associated with increased frequency of the D allele.

Suppression of keratinocyte growth and differentiation by transforming growth factor beta 1 involves multiple signaling pathways

Transforming growth factor beta1 treatment of keratinocytes results in a suppression of differentiation, an induction of extracellular matrix production, and a suppression of growth. In this study we utilized markers specific for each of these functions to explore the signaling pathways involved in mediating these transforming-growth-factor-beta1-induced activities. In the first instance, we found that the induction of extracellular matrix production (characterized by 3TP-Lux reporter activity) was induced in both keratinocytes and a keratinocyte-derived carcinoma cell line, SCC25, in a dose-dependent manner. Furthermore, transforming growth factor beta1 also suppressed the differentiation-specific marker gene, transglutaminase type 1, in both keratinocytes and SCC25 cells. In contrast, transforming growth factor beta1 inhibited proliferation of keratinocytes but did not cause growth inhibition in the SCC25 cells. Transforming-growth-factor-beta1-induced growth inhibition of keratinocytes was characterized by decreases in DNA synthesis, accumulation of hypophosphorylated Rb, and the inhibition of the E2F:Rb-responsive promoter, cdc2, and an induction of the p21 promoter. When the negative regulator of transforming growth factor beta1 signaling, SMAD7, was overexpressed in keratinocytes it could prevent transforming-growth-factor-beta1-induced activation of the 3TP-Lux and the p21 promoter. SMAD7 could also prevent the suppression of the transglutaminase type 1 by transforming growth factor beta1 but it could not inhibit the repression of the cdc2 promoter. These data indicate that the induction of 3TP-Lux and p21 and the suppression of transglutaminase type 1 are mediated by a different proximate signaling pathway to that regulating the suppression of the cdc2 gene. Combined, these data indicate that the regulation of transforming growth factor beta1 actions are complex and involve multiple signaling pathways.

Design of a polyepitope construct for the induction of HLA-A0201-restricted HIV 1-specific CTL responses using HLA-A*0201 transgenic, H-2 class IKO mice

HLA-A*0201 transgenic, H-2D(b)/mouse beta2-microglobulin double-knockout mice were used to compare and optimize the immunogenic potential of 17HIV 1-derived, HLA-A0201-restricted epitopic peptides. A tyrosine substitution in position 1 of the epitopic peptides, which increases both their affinity for and their HLA-A0201 molecule stabilizing capacity, was introduced in a significant proportion, having verified that such modifications enhance their immunogenicity in respect of their natural antigenicity. Based on these results, a 13-polyepitope construct was inserted in the pre-S2 segment of the hepatitis B middle glycoprotein and used for DNA immunization. Long-lasting CTL responses against most of the inserted epitopes could be elicited simultaneously in a single animal with cross-recognition in several cases of their most common natural variants.

Mechanistic aspects of HIV-1 reverse transcription initiation

During reverse transcription, the positive-strand HIV-1 RNA genome is converted into a double-stranded DNA copy which can be permanently integrated into the host cell genome. Recent analyses show that HIV-1 reverse transcription is a highly regulated process. The initiation reaction can be distinguished from a subsequent elongation reaction carried out by a reverse transcription complex composed of (at least) heterodimeric reverse transcriptase, cellular tRNA(lys3) and HIV-1 genomic RNA sequences. In addition, viral factors including Tat, Nef, Vif, Vpr, IN and NCp7, cellular proteins, and TAR RNA and other RNA stem-loop structures appear to influence this complex and contribute to the efficiency of the initiation reaction. As viral resistance to many antiretroviral compounds is a continuing problem, understanding the ways in which these factors influence the reverse transcription complex will likely lead to novel antiretroviral strategies. Copyright (C) 2001 John Wiley Sons, Ltd.

Adipose tissue as an endocrine organ

Adipose tissue is a highly active endocrine organ secreting a range of soluble products with both local and distant actions. These hormones have important roles in metabolism, reproduction, cardiovascular function and immunity. It is now evident that adipose endocrine function directly influences other organ systems, including the brain, liver and skeletal muscle. The endocrine function of adipose tissue is significantly regulated by nutritional status, and both are inextricably linked to the energy storage role of adipose tissue. This chapter highlights the endocrinology of adipose tissue by concentrating on functional aspects of the secreted products. The data of particular relevance to humans are highlighted, and areas in need of future research are suggested.

Development of a selective photoactivatable antagonist for corticotropin-releasing factor receptor, type 2 (CRF2)

A novel photoactivatable analog of antisauvagine-30 (aSvg-30), a specific antagonist for corticotropin-releasing factor (CRF) receptor, type 2 (CRF2), has been synthesized and characterized. The N-terminal amino-acid D-Phe in aSvg-30 [D-Phe11,His12] Svg((11-40)) was replaced by a phenyldiazirine, the 4-(1-azi-2,2,2-trifluoroethyl) benzoyl (ATB) residue. The photoactivatable aSvg-30 analog ATB-[ His12] Svg was tested for its ability to displace [I-125-Tyr0] oCRF or [I-125-Tyr0]Svg from membrane homogenates of human embryonic kidney (HEK) 293 cells stably transfected with cDNA coding for rat CRF receptor, type 1 ( rCRF(1)) or mouse CRF receptor, type 2beta (mCRF(2beta)). Furthermore, the ability of ATB- [His12] Svg((12-40)) to inhibit oCRF- or Svg-stimulated cAMP production of transfected HEK 293 cells expressing either rCRF(1) (HEK-rCRF(1) cells) or mCRF(2beta) (HEK-mCRF(2beta) cells) was determined. Unlike astressin and photo astressin, ATB- [His12]Svg((12-40)) showed high selective binding to mCRF(2beta) (K-i = 3.1 +/- 0.2 nM) but not the rCRF(1) receptor (K-i = 142. 5 +/- 22.3 nM) and decreased Svg-stimulated cAMP activity in mCRF(2beta)-expressing cells in a similar fashion as aSvg-30. A66-kDa protein was identified by SDS/PAGE, when the radioactively iodinated analog of ATB- [His12]Svg((12-40)) was covalently linked to mCRF(2beta) receptor. The specificity of the photoactivatable I-125-labeled CRF2beta antagonist was demonstrated with SDS/PAGE by the finding that this analog could be displaced from the receptor by antisauvagine-30, but not other unrelated peptides such as vasoactive intestinal peptide (VIP).

Routine ultrasound screening in diabetic pregnancies

Objectives To assess the detection rate of congenital fetal malformations and specific problems related to routine ultrasound screening in women with pre-existing diabetes. Methods A retrospective study was carried out to assess the performance of routine ultrasound screening in women with pre-existing diabetes (Types 1 and 2) within a tertiary institution. The incidence, type and risk factors for congenital fetal malformations were determined. The detection rate of fetal anomalies for diabetic women was compared with that for the low-risk population. Factors affecting these detection rates were evaluated. Results During the study period, 12 169 low-risk pregnant women and 130 women with pre-existing diabetes had routine ultrasound screening performed within the institution. A total of 10 major anomalies (7.7%) and three minor anomalies (2.3%) were present in the fetuses of the diabetic women. Central nervous system and cardiovascular system anomalies accounted for 60% of the major anomalies. Peri-conceptional hemoglobin A 1 c of more than 9% was associated with a high prevalence of major anomalies (14311000). Women who had fetuses with major anomalies bad a significantly higher incidence of obesity (78% vs. 37%; P < 0.05). Ultrasound examination of these diabetic pregnancies showed high incidences of suboptimal image quality (37%), incomplete examinations, and repeat examinations (17%). Compared to the 'low-risk' non-diabetic population from the same institution, the relative risk for a major congenital anomaly among the diabetic women was 5.9-fold higher (95% confidence interval, 2.9-11.9). The detection rate for major fetal anomalies was significantly lower for diabetic women (30% vs. 73%; P < 0.01), and the mean body mass index for the diabetic group was significantly higher (29 vs. 23 kg/m(2); P < 0.001). Conclusion The incidence of congenital anomalies is higher in diabetic pregnancies. Unfortunately, the detection rate for fetal anomalies by antenatal ultrasound scan was significantly, worse than that for the low-risk population. This is likely to be related to the maternal body habitus and unsatisfactory examinations. Methods to overcome these difficulties are discussed.