Clinical Research Strategies for Fructose Metabolism

Fructose and simple sugars are a substantial part of the western diet, and their influence on human health remains controversial. Clinical studies in fructose nutrition have proven very difficult to conduct and interpret. NIH and USDA sponsored a workshop on 13–14 November 2012, “Research Strategies for Fructose Metabolism,” to identify important scientific questions and parameters to be considered while designing clinical studies. Research is needed to ascertain whether there is an obesogenic role for fructose-containing sugars via effects on eating behavior and energy balance and whether there is a dose threshold beyond which these sugars promote progression toward diabetes and liver and cardiovascular disease, especially in susceptible populations. Studies tend to fall into 2 categories, and design criteria for each are described. Mechanistic studies are meant to validate observations made in animals or to elucidate the pathways of fructose metabolism in humans. These highly controlled studies often compare the pure monosaccharides glucose and fructose. Other studies are focused on clinically significant disease outcomes or health behaviors attributable to amounts of fructose-containing sugars typically found in the American diet. These are designed to test hypotheses generated from short-term mechanistic or epidemiologic studies and provide data for health policy. Discussion brought out the opinion that, although many mechanistic questions concerning the metabolism of monosaccharide sugars in humans remain to be addressed experimentally in small highly controlled studies, health outcomes research meant to inform health policy should use large, long-term studies using combinations of sugars found in the typical American diet rather than pure fructose or glucose.     

Use of spleen organ cultures to monitor hemopoietic progenitor cell regeneration following irradiation and marrow transplantation

After lethal irradiation of C57BL mice followed by the injection of 10(7) marrow cells, total cellularity and progenitor cell levels exceeded pretreatment levels within 12 days in the spleen, but regeneration remained incomplete in the marrow. The exceptional regenerative capacity of progenitor populations in the spleen was observed in organ cultures of spleen slices prepared 24 hr after irradiation and transplantation, excluding continuous repopulation from the marrow as a significant factor in splenic regeneration.     

Using Remote Communication Technology in Insulin Pump Training: A Feasibility Study

Purpose:

This feasibility study was designed to examine if remote communication technology can be used in the technical training of an insulin pump in adults with diabetes who were familiar with insulin pump therapy.

Methods:

Surveys were emailed to 69 individuals who purchased an insulin pump and had been trained by the manufacturer’s diabetes educators. In consultation with providers, participants were given the choice of receiving training in a face-to-face meeting or via remote communication technology. The survey consisted of 27 questions asking participants’ characteristics, device proficiency, confidence, and their satisfaction with the insulin pump and the training method. Differences between the 2 groups were examined using bivariate analyses.

Results:

There were 17 participants in the remote group and 20 participants in the face-to-face group. Participants had a mean age of 40.9 ± 14.3 years, had diabetes for 24.3 ± 13.8 years, and used an insulin pump for 9.8 ± 4.9 years. The participants in both groups were not statistically different in age, diabetes history, years on insulin pump, device proficiency, confidence, or satisfaction with the training method. The remote group reported less graduate-level education (P < .05) and higher satisfaction scores with the insulin pump training (P < .05).

Conclusion:

Although this study has limitations associated with the small sample size and self-selection bias, the results suggest that remote communication technology may be an effective tool to provide technical training to adults who are familiar with insulin pump therapy. Additional research is required to determine the effectiveness of the remote insulin pump training.     

Ischaemic colitis in the experimental animal. II. Role of hypovolaemia in the production of the disease.

Hypovolaemia alone did not lead to ischaemic colitis but when venesection was induced immediately after the acute ligation of the common colic artery large bowel ischaemia ensued. Similarly, hypovolaemia induced one month after two major blood vessels had been occluded led to ischaemic colitis. These findings suggest that states of low blood flow in the presence of previous arterial constriction or blockage may lead to enough reduction in mesenteric perfusion for intestinal ischaemia to develop. Using an electromagnetic flowmeter placed in the cranial mesenteric artery of the dog, it was shown that hypovolaemia may lead to 50-75% reduction in mesenteric blood flow without producing any significant change in the systemic blood pressure.     

Tumor acceptance modified by passage in hybrids with graft-versus-host reaction.

A graft-versus-host reaction (GVHR) was produced in adult F1 hybrid mice by the injection of 10(8) parental strain spleen cells and 8 days later they were challenged with allogeneic third-party tumor. BALB/c Leydig cell tumor (C4092), C57BL/6 sarcoma (30795), and DBA/1 melanoma (S91) often grew progressively in B6D1F1, CD1F1, B6CF1 or their reciprocal hybrid recipients, respectively, when GVHR had been induced in these animals. Control, without GVHR, hybrids always rejected the tumor. The C4092 tumor was serially transplantable in untreated hybrids after its initial passage in unrelated GVHR-treated mice; the S91 grew in its first passage into untreated B6CF1 mice but thereafter was rejected by these hybrids; while the B6 tumor 30795 grew progressively only in the initial GVHR-treated CD1F1 or reciprocal hybrids. Reduced immunogenicity of tumors resulting from passage in unrelated recipients immunosuppressed in association with a GVHR is comparable to allograft adaptation achieved by such techniques as organ culture pretreatment and presents an additional method for attenuating rejection of allotransplants.     

Role of oxygen radicals in ischemia-induced lesions in the cat stomach

Ischemia in a stomach that contains acid may produce severe gastric mucosal injury. The extent to which oxygen-derived free radicals are involved in the pathogenesis of this injury was investigated in the present study. Local gastric ischemia was achieved by reducing celiac artery pressure to 30 mmHg for 1 h. Ischemic injury was assessed by recording the loss of 125I-albumin and 51Cr-red cells across the gastric mucosa. Cats were treated with a xanthine oxidase inhibitor (allopurinol), a superoxide radical scavenging enzyme (superoxide dismutase), and a scavenger of hydroxyl radicals (dimethyl sulfoxide). The damage associated with ischemia only occurred during reperfusion of the stomach and was worst in the antrum. The level of xanthine oxidase in the antrum was twice that of the corpus. Treatment with allopurinol, superoxide dismutase, and dimethyl sulfoxide reduced 51Cr-red cell loss to 15%, 25%, and 21% of control (untreated) animals, respectively. The data indicate that oxygen-derived free radicals play a role in ischemic injury to the stomach and that the hydroxyl radical, a secondary radical produced from the superoxide anion, appears to be the major oxygen radical contributing to ischemic damage.     

Xanthine oxidase inhibitors attenuate ischemia-induced vascular permeability changes in the cat intestine

Previous reports indicate that allopurinol, a xanthine oxidase inhibitor, largely prevents the injury produced by reperfusion of ischemic tissues. In order to further assess the role of xanthine oxidase in ischemia-reperfusion injury, we examined the influence of another inhibitor of the enzyme (pterin aldehyde) on the increased vascular permeability produced by intestinal ischemia. Vascular permeability estimates in autoperfused segments of cat ileum were derived from the relationship between lymph-to-plasma protein concentration ratio and lymph flow. One hour of intestinal ischemia increased vascular permeability to 0.43 +/- 0.02 from a control (nonischemic) value of 0.08 +/- 0.005. In ischemic ileal segments pretreated with purified pterin aldehyde, vascular permeability increased to only 0.15 +/- 0.02. Pretreatment with commercially prepared folic acid, which is contaminated with pterin aldehyde, also attenuated the ischemia-induced increase in vascular permeability (0.16 +/- 0.04). These findings support the hypothesis that xanthine oxidase is a major source of oxygen-free radicals produced during reperfusion of the ischemic small bowel.     

An adenoviral vector deleted for all viral coding sequences results in enhanced safety and extended expression of a leptin transgene

Adenoviral (Ad)-mediated in vivo gene transfer and expression are limited in part by cellular immune responses to viral-encoded proteins and/or transgene immunogenicity. In an attempt to diminish the former responses, we have previously developed and described helper-dependent (HD) Ad vectors in which the viral protein coding sequences are completely eliminated. These HD vectors have up to 37 kb insert capacity, are easily propagated in a Cre recombinase-based system, and can be produced to high concentration and purity (>99.9% helper-free vector). In this study, we compared safety and efficacy of leptin gene delivery mediated by an HD vector (HD-leptin) and a first-generation E1-deleted Ad vector (Ad-leptin) in normal lean and ob/ob (leptin-deficient) mice. In contrast to evidence of liver toxicity, inflammation, and cellular infiltration observed with Ad-leptin delivery in mice, HD-leptin delivery was associated with a significant improvement in associated safety/toxicity and resulted in efficient gene delivery, prolonged elevation of serum leptin levels, and associated weight loss. The greater safety, efficient gene delivery, and increased insert capacity of HD vectors are significant improvements over current Ad vectors and represent favorable features especially for clinical gene therapy applications.     

Protocols,practices, and needs for investigating sudden unexpected infant deaths

Understanding case identification practices, protocols, and training needs of medical examiners and coroners (MEC) may inform efforts to improve cause-of-death certification. We surveyed a U.S.-representative sample of MECs and described investigation practices and protocols used in certifying sudden unexpected infant deaths (SUID). We also identified MEC training and resource needs. Of the 377 respondents, use of the SUID Investigation Reporting Form or an equivalent was 89% for large, 87% for medium, and 52% for small jurisdictions. Routine completion of infant medical history, witness interviews, autopsy, photos or videos, and family social history for infant death investigations was ≥80%, but routine scene re-creation with a doll was 30% in small, 64% in medium, and 59% in large offices. Seventy percent of MECs reported infant death investigation training needs. Increased training and use of standardized practices may improve SUID cause-of-death certification, allowing us to better understand SUID.