Comparison of Arterial and Venous Interposition Grafting for Arterial Defects in a Rat Model.

BACKGROUND: Interposition microvascular grafting may be required to bridge arterial defects during digital replantation or revascularization and has traditionally been performed utilizing a venous autograft. Arterial interposition grafting has been shown to be superior in maintaining patency in large vessel surgery; there are case reports of its use in microsurgery. METHODS: Six fellowship-trained hand and microsurgeons performed arterial and venous interposition grafts on the femoral arteries of 40 Wistar rats. After sectioning one femoral artery a segment of the contralateral femoral artery or vein was obtained. The time was recorded per graft and patency tested 10 minutes following grafting by an independent assessor. Each surgeon also completed a questionnaire detailing regular microsurgical volume, technical ease, and conceptual preference for either graft. RESULTS: Time for arterial interposition (median time 51.7 minutes) was longer than venous grafting (median time 45.9 minutes, p = 0.075). Arterial grafts were more likely to be patent or questionably patent (odds ratio [OR] = 6.77, p = 0.031). All surgeons found arterial interposition grafting technically easier and preferred it conceptually. Improvements were noted in patency rates (OR = 11.29, p = 0.018) and avoidance of anastomotic leak (OR = 0.19, p = 0.029) when surgeons performed moderate levels or greater of microsurgery within their regular practice. CONCLUSION: Greater immediate patency was noted with arterial interposition grafting in a rodent model when compared to venous grafting, although procedural time was greater. All surgeons found arterial grafting technically easier. Arterial microvascular grafting may be useful in the setting of digital replantation or revascularization with an arterial defect.

Palliative Radiation Therapy for Treatment of Cutaneous T-cell Lymphoma in a Double Yellow-headed Amazon Parrot (Amazona oratrix).

A 17-year-old captive female double yellow-headed Amazon parrot (Amazona oratrix) was presented to the Kansas State University Zoological Medicine Service (Manhattan, KS, USA) for a 2-month history of a left sided facial swelling. On examination, a red, raised mass was noted on the left side of the face. A whole-body computed tomography scan of the bird was performed to assess the extent of the mass and evaluate the patient for obvious evidence of disseminated disease. No systemic involvement was detected, and the swelling was localized to the cutaneous and subcutaneous tissues overlying the left rhamphotheca. Two punch biopsies were collected, and histopathology was consistent with cutaneous lymphoma, with strong positive CD3 staining congruous with a T-cell origin. Because of a lack of evidence for disseminated disease, the authors elected to pursue localized radiation therapy, and a single fraction of 8 Gray was administered. The swelling had resolved by the time of the recheck examination 4 weeks post-radiation therapy, and the patient remained clinically normal 52 weeks after radiation therapy.

Adolescent Wrist Pain.

Adolescence is a difficult time, both physically and emotionally. Rapid growth coupled with physical changes in the background of high levels of activity can be overwhelming. Meanwhile, unfamiliar life stressors coupled with undeveloped compensatory mechanisms can lead to overwhelming anxiety and emotional distress. Emotional factors can make injuries and overuse syndromes feel more catastrophic. Occasionally, an adolescent's emotional distress can manifest physically, without antecedent injury or physiologic cause. Understanding the psychological milieu is as important as understanding the disease processes that can affect adolescents if one hopes to manage these patients effectively.

Characterization of the variability in the extent of nonalcoholic fatty liver induced by a high-fat diet in the genetically diverse Collaborative Cross mouse model.

Interindividual variability and sexual dimorphisms in the development of nonalcoholic fatty liver disease (NAFLD) are still poorly understood. In the present study, male and female strains of Collaborative Cross (CC) mice were fed a high-fat and high-sucrose (HF/HS) diet or a control diet for 12 weeks to investigate interindividual- and sex-specific variations in the development of NAFLD. The severity of liver steatosis varied between sexes and individual strains and was accompanied by an elevation of serum markers of insulin resistance, including increases in total cholesterol, low-density lipoproteins, high-density lipoproteins, phospholipids, and glucose. The development of NAFLD was associated with overexpression of the critical fatty acid uptake and de novo lipogenesis genes Pparg, Mogat1, Cd36, Acaab1, Fabp2, and Gdf15 in male and female mice. The expression of Pparg, Mogat1, and Cd36 was positively correlated with liver triglycerides in male mice, and Mogat1 and Cd36 expression were positively correlated with liver triglycerides in female mice. Our results indicate the value of CC mice in combination with HF/HS diet-induced alterations as an approach to study the susceptibility and interindividual variabilities in the pathogenesis of nonalcoholic fatty liver and early nonalcoholic steatohepatitis at the population level, uncovering of susceptible and resistant cohorts, and identifying sex-specific molecular determinants of disease susceptibility.

Targeted deletion of nicotinamide adenine dinucleotide phosphate oxidase 4 from proximal tubules is dispensable for diabetic kidney disease development.

BACKGROUND: The nicotinamide adenine dinucleotide phosphate oxidase isoform 4 (Nox4) mediates reactive oxygen species (ROS) production and renal fibrosis in diabetic kidney disease (DKD) at the level of the podocyte. However, the mitochondrial localization of Nox4 and its role as a mitochondrial bioenergetic sensor has recently been reported. Whether Nox4 drives pathology in DKD within the proximal tubular compartment, which is densely packed with mitochondria, is not yet known. METHODS: We generated a proximal tubular-specific Nox4 knockout mouse model by breeding Nox4flox/flox mice with mice expressing Cre recombinase under the control of the sodium-glucose cotransporter-2 promoter. Subsets of Nox4ptKO mice and their Nox4flox/flox littermates were injected with streptozotocin (STZ) to induce diabetes. Mice were followed for 20 weeks and renal injury was assessed. RESULTS: Genetic ablation of proximal tubular Nox4 (Nox4ptKO) resulted in no change in renal function and histology. Nox4ptKO mice and Nox4flox/flox littermates injected with STZ exhibited the hallmarks of DKD, including hyperfiltration, albuminuria, renal fibrosis and glomerulosclerosis. Surprisingly, diabetes-induced renal injury was not improved in Nox4ptKO STZ mice compared with Nox4flox/flox STZ mice. Although diabetes conferred ROS overproduction and increased the mitochondrial oxygen consumption rate, proximal tubular deletion of Nox4 did not normalize oxidative stress or mitochondrial bioenergetics. CONCLUSIONS: Taken together, these results demonstrate that genetic deletion of Nox4 from the proximal tubules does not influence DKD development, indicating that Nox4 localization within this highly energetic compartment is dispensable for chronic kidney disease pathogenesis in the setting of diabetes.

Sustainability Challenges and Opportunities in Oligonucleotide Manufacturing.

With a renewed and growing interest in therapeutic oligonucleotides across the pharmaceutical industry, pressure is increasing on drug developers to take more seriously the sustainability ramifications of this modality. With 12 oligonucleotide drugs reaching the market to date and hundreds more in clinical trials and preclinical development, the current state of the art in oligonucleotide production poses a waste and cost burden to manufacturers. Legacy technologies make use of large volumes of hazardous reagents and solvents, as well as energy-intensive processes in synthesis, purification, and isolation. In 2016, the American Chemical Society (ACS) Green Chemistry Institute Pharmaceutical Roundtable (GCIPR) identified the development of greener processes for oligonucleotide Active Pharmaceutical Ingredients (APIs) as a critical unmet need. As a result, the Roundtable formed a focus team with the remit of identifying green chemistry and engineering improvements that would make oligonucleotide production more sustainable. In this Perspective, we summarize the present challenges in oligonucleotide synthesis, purification, and isolation; highlight potential solutions; and encourage synergies between academia; contract research, development and manufacturing organizations; and the pharmaceutical industry. A critical part of our assessment includes Process Mass Intensity (PMI) data from multiple companies to provide preliminary baseline metrics for current oligonucleotide manufacturing processes.

Inhibitors of Advanced Glycation End Product (AGE) Formation and Accumulation.

A range of chemically different compounds are known to inhibit the formation and accumulation of advanced glycation end products (AGEs) or disrupt associated signalling pathways. There is evidence that some of these agents can provide end-organ protection in chronic diseases including diabetes. Whilst this group of therapeutics are structurally and functionally different and have a range of mechanisms of action, they ultimately reduce the deleterious actions and the tissue burden of advanced glycation end products. To date it remains unclear if this is due to the reduction in tissue AGE levels per se or the modulation of downstream signal pathways. Some of these agents either stimulate antioxidant defence or reduce the formation of reactive oxygen species (ROS), modify lipid profiles and inhibit inflammation. A number of existing treatments for glucose lowering, hypertension and hyperlipidaemia are also known to reduce AGE formation as a by-product of their action. Targeted AGE formation inhibitors or AGE cross-link breakers have been developed and have shown beneficial effects in animal models of diabetic complications as well as other chronic conditions. However, only a few of these agents have progressed to clinical development. The failure of clinical translation highlights the importance of further investigation of the advanced glycation pathway, the diverse actions of agents which interfere with AGE formation, cross-linking or AGE receptor activation and their effect on the development and progression of chronic diseases including diabetic complications. Advanced glycation end products (AGEs) are (1) proteins or lipids that become glycated as a result of exposure to sugars or (2) non-proteinaceous oxidised lipids. They are implicated in ageing and the development, or worsening, of many degenerative diseases, such as diabetes, atherosclerosis, chronic kidney and Alzheimer's disease. Several antihypertensive and antidiabetic agents and statins also indirectly lower AGEs. Direct AGE inhibitors currently investigated include pyridoxamine and epalrestat, the inhibition of the formation of reactive dicarbonyls such as methylglyoxal as an important precursor of AGEs via increased activation of the detoxifying enzyme Glo-1 and inhibitors of NOX-derived ROS to reduce the AGE/RAGE signalling.

Empagliflozin modulates renal sympathetic and heart rate baroreflexes in a rabbit model of diabetes.

AIMS/HYPOTHESIS: We determined whether empagliflozin altered renal sympathetic nerve activity (RSNA) and baroreflexes in a diabetes model in conscious rabbits. METHODS: Diabetes was induced by alloxan, and RSNA, mean arterial pressure (MAP) and heart rate were measured before and after 1 week of treatment with empagliflozin, insulin, the diuretic acetazolamide or the ACE inhibitor perindopril, or no treatment, in conscious rabbits. RESULTS: Four weeks after alloxan administration, blood glucose was threefold and MAP 9% higher than non-diabetic controls (p < 0.05). One week of treatment with empagliflozin produced a stable fall in blood glucose (-43%) and increased water intake (+49%) but did not change RSNA, MAP or heart rate compared with untreated diabetic rabbits. The maximum RSNA to hypotension was augmented by 75% (p < 0.01) in diabetic rabbits but the heart rate baroreflex was unaltered. Empagliflozin and acetazolamide reduced the augmentation of the RSNA baroreflex (p < 0.05) to be similar to the non-diabetic group. Noradrenaline (norepinephrine) spillover was similar in untreated diabetic and non-diabetic rabbits but twofold greater in empagliflozin- and acetazolamide-treated rabbits (p < 0.05). CONCLUSIONS/INTERPRETATION: As empagliflozin can restore diabetes-induced augmented sympathetic reflexes, this may be beneficial in diabetic patients. A similar action of the diuretic acetazolamide suggests that the mechanism may involve increased sodium and water excretion. Graphical abstract.

Differential sympathetic response to lesion-induced chronic kidney disease in rabbits.

Chronic kidney disease (CKD) is associated with greater sympathetic nerve activity but it is unclear if this is a kidney-specific response or due to generalized stimulation of sympathetic nervous system activity. To determine this, we used a rabbit model of CKD in which quantitative comparisons with control rabbits could be made of kidney sympathetic nerve activity and whole-body norepinephrine spillover. Rabbits either had surgery to lesion 5/6th of the cortex of one kidney by electro-lesioning and two weeks later removal of the contralateral kidney, or sham lesioning and sham nephrectomy. After three weeks, the blood pressure was statistically significantly 20% higher in conscious rabbits with CKD compared to rabbits with a sham operation, but their heart rate was similar. Strikingly, kidney nerve activity was 37% greater than in controls, with greater burst height and frequency. Total norepinephrine spillover was statistically significantly lower by 34%, and kidney baroreflex curves were shifted to the right in rabbits with CKD. Plasma creatinine and urine output were elevated by 38% and 131%, respectively, and the glomerular filtration rate was 37% lower than in sham-operated animals (all statistically significant). Kidney gene expression of fibronectin, transforming growth factor-ß, monocyte chemotactic protein1, Nox4 and Nox5 was two- to eight-fold greater in rabbits with CKD than in control rabbits. Overall, the glomerular layer lesioning model in conscious rabbits produced a moderate, stable degree of CKD characterized by elevated blood pressure and increased kidney sympathetic nerve activity. Thus, our findings, together with that of a reduction in total norepinephrine spillover, suggest that kidney denervation, rather than generalized sympatholytic treatments, may represent a preferable management for CKD associated hypertension.