A prevascularized tissue engineering chamber supports growth and function of islets and progenitor cells in diabetic mice

Recent studies have shown that type 1 diabetes can be reversed in a murine model by islet transplantation to a vascularized tissue engineering chamber. In preliminary experiments using a prevascularized chamber we observed that islet grafts not functioning initially can show a delayed onset of function several weeks after implantation. We sought to characterize this phenomenon. Islets were transplanted into prevascularized tissue engineering chambers based on the epigastric vessels in streptozotocin induced diabetic C57BL/6J mice. Animals were transplanted with 500 islets and observed at 1, 4, 8 and 16 weeks post transplantation. Weekly blood glucose (BG) measurements revealed an average onset of maintained graft function 6.8 weeks post transplantation. Graft function was proven by a return to a diabetic state following chamber removal. Mature grafts showed islet tissue clustered together within the tissue construct. The quantity of endocrine tissue staining positive for insulin correlated with graft function at 8 and 16 weeks. However, at 1 and 4 weeks, islet tissue was not evidently visible as observed by endocrine staining. All islet tissue showed dense vascularization and sporadic sympathetic innervation, irrespective of the graft's function. Immunopositive cells for Cytokeratin-7 and -19 were observed in the grafts at early time points and hormone producing cells appear to have been differentiated from these progenitors. Our data demonstrates that pancreatic duct-derived progenitors remain viable in vivo and eventually differentiate and mature to functional islets following transplantation. Our prevascularized tissue-engineering chamber in the groin supports maturation and function of the grafted tissue by two months after implantation.     

Galanin receptor 3 – a potential target for acute pancreatitis therapy

Background Galanin participates in the pathogenesis of acute pancreatitis (AP). The galanin receptor (GALR) sub‐types involved, however, are unclear. We aimed to determine GALRs messenger RNA (mRNA) expression in mouse pancreas, describe their localization, and ascertain if GALR2 and GALR3 are involved in AP. Methods Galanin receptor expression in murine whole pancreas, acinar, and islet cells was quantified by polymerase chain reaction amplification of reverse‐transcribed RNA for mRNA, Western blot analysis for protein and in situ hybridization for GALR localization. Isolated acinar cells were used to determine galanin’s effect on amylase secretion. Acute pancreatitis was induced in mice by caerulein injections. Mice, with and without AP, were treated with the highly selective GALR2 antagonist M871, or the specific GALR3 antagonist SNAP‐37889. Indices of AP were measured at 12 h. Key Results Murine pancreas expresses mRNA for GALRs. In islets the expression of all GALR are comparable, whereas in acinar cells GALR3 is predominantly expressed. Western blot analysis confirmed that the GALR proteins are expressed by acinar cells. In situ hybridization analysis confirmed that GALR3 mRNA is present in islet and acinar cells, while mRNA for GALR1 and 2 is confined to islets. Galanin did not influence basal and caerulein‐stimulated amylase release from acinar cells. M871 treatment reduced some, whereas SNAP‐37889 treatment reduced all indices of AP (by 40–80%). Conclusions & Inferences Galanin receptor mRNA and protein are expressed in mouse pancreas, with GALR3 mRNA predominating. GALR3 antagonism reduced the severity of AP whereas GALR2 antagonism was less effective. GALR3 is a potential target for treatment of AP.     

Genetic deletion of the adenosine A2A receptor in mice reduces the changes in spinal cord NMDA receptor binding and glucose uptake caused by a nociceptive stimulus

Mice lacking the adenosine A_2A receptor are less sensitive to nociceptive stimuli, and A_2A receptor antagonists have antinociceptive effects. We have previously shown a marked reduction in the behavioural responses to formalin injection in A_2A receptor knockout mice. This may be due to the presence of pronociceptive A_2A receptors on sensory nerves, and if so spinal cords from A_2A receptor knockout mice may have altered neurochemical responses to a nociceptive stimulus. We tested this hypothesis by studying two parameters known to change with spinal cord activity, NMDA glutamate receptor binding and [¹⁴C]-2-deoxyglucose uptake, following intraplantar formalin injection in wild-type and A_2A receptor knockout mice. In naïve untreated A_2A knockout mice [¹⁴C]-2-deoxyglucose uptake in all regions of the spinal cord was significantly lower compared to the wild-type, similar to the reduced NMDA receptor binding that we have previously observed. Following formalin treatment, there was an decrease in [³H]-MK801 binding to NMDA receptors and an increase in [¹⁴C]-2-deoxyglucose uptake in the spinal cords of wild-type mice, and these changes were significantly reduced in the A_2A knockout mice. In addition to altered behavioural responses, there are therefore corresponding reductions in spinal cord neurochemical changes induced by formalin in mice lacking adenosine A_2A receptors. These observations support the hypothesis that activation of A_2A receptors enhances nociceptive input into the spinal cord and suggests a possible role for A_2A antagonists as analgesics.     

Higher human CD4 T cell response to novel Mycobacterium tuberculosis latency associated antigens Rv2660 and Rv2659 in latent infection compared with tuberculosis disease

One third of the world's population is infected with Mycobacterium tuberculosis (M.tb). A vaccine that would prevent progression to TB disease will have a dramatic impact on the global TB burden. We propose that antigens of M.tb that are preferentially expressed during latent infection will be excellent candidates for post-exposure vaccination. We therefore assessed human T cell recognition of two such antigens, Rv2660 and Rv2659. Expression of these was shown to be associated with non-replicating persistence in vitro. After six days incubation of PBMC from persons with latent tuberculosis infection (LTBI) and tuberculosis (TB) disease, Rv2660 and Rv2659 induced IFN-γ production in a greater proportion of persons with LTBI, compared with TB diseased patients. Persons with LTBI also had increased numbers of viable T cells, and greater specific CD4⁺ T cell proliferation and cytokine expression capacity. Persons with LTBI preferentially recognize Rv2659 and Rv2660, compared with patients with TB disease. These results suggest promise of these antigens for incorporation into post-exposure TB vaccines.     

Associations of Rural Residence With Timing of HIV Diagnosis and Stage of Disease at Diagnosis,South Carolina 2001-2005

Context: Rural areas in the southern United States face many challenges, including limited access to health care services and stigma, which may lead to later HIV diagnosis among rural residents. Purpose: To investigate the associations of rural residence with timing of HIV diagnosis and stage of disease at diagnosis. Methods: Timing of HIV diagnosis was categorized as a diagnosis of acquired immune deficiency syndrome within 1 year of a first positive HIV test or HIV-only. Stage of disease was based on initial CD4+ T-cell count taken within 1 year of diagnosis. County of residence at HIV diagnosis was classified as urban if the population of the largest city was at least 25,000; it was classified as rural otherwise. Logistic regression was used to analyze timing of HIV diagnosis, and analysis of covariance was used to analyze stage of disease. Findings: From 2001 to 2005, 4,137 individuals were diagnosed with HIV infection. Of these, 1,129 (27%) were rural and 3,008 (73%) were urban residents. Among rural residents, 533 (47%) were diagnosed late, compared with 1,258 (42%) urban residents. Rural residents were significantly more likely to be diagnosed late (OR 1.19 [95% CI, 1.02-1.38]). Rural residence was associated with lower initial CD4+ T-cell count in crude analysis (P= .01) but not after adjustment (P > .05). Conclusions: Rural residence is a risk factor for late HIV diagnosis. This may lead to reduced treatment response to antiretroviral medications, increased morbidity and mortality, and greater HIV transmission risks among rural residents. New testing strategies are needed that address challenges to HIV testing and diagnosis specific to rural areas.     

Are adolescents ready for tuberculosis vaccine trials?

Tuberculosis (TB) vaccine trials are planned in adolescents in a high tuberculosis burden rural area near Cape Town, South Africa. To determine the knowledge and attitudes of adolescents about tuberculosis, vaccines and vaccine trials, a representative sample of adolescent learners was chosen from high schools in the trial area. A questionnaire was administered and focus group discussions held with the group and a sample of their parents. The questionnaire response rate was 65%. Knowledge of tuberculosis was fair 63.7% but knowledge of vaccines poor 41.9% based on a TB and vaccine knowledge score, respectively. Willingness to participate in vaccine trials will be influenced by the type of procedures involved (60% willing to answer questions, 43% willing to be examined, 32% willing to undergo skin tests and 39% willing to undergo blood draw). In general, better knowledge was statistically associated with greater willingness to participate in study procedures except for the blood draw. The focus group discussions showed that adolescents and their parents were positive about participating in vaccine trials but concerns about safety and the provision of adequate information should be considered when planning TB vaccine trials. This study suggests that TB vaccine trials would be acceptable amongst adolescents in this community with certain provisos.     

Concordance between adolescent reports of childhood abuse and Child Protective Service determinations in an at-risk sample of young adolescents

This study examines the concordance between adolescent reports of abuse and abuse determinations from Child Protective Service (CPS) agencies. It also compares the utility of adolescent reports of abuse, relative to CPS determinations in predicting adolescent psychological adjustment. The sample included 350 early adolescents, ages 12 to 13 years, who were initially identified prior to age 2 years as being at elevated risk of maltreatment. An Audio-Computer Assisted Self Interview (A-CASI) was used to assess lifetime experiences of physical, sexual, and psychological abuse. The A-CASI interview elicited prevalence rates of abuse 4 to 6 times higher than those found in CPS records. However, 20 of 45 adolescents with CPS determinations of abuse failed to report abuse during the study interview. Adolescent psychological adjustment was more strongly associated with self-reports than with CPS determinations. The implications of these findings are discussed for validity of adolescent self-reports of childhood abuse and for the ongoing debate about disclosure patterns among victims of child sexual abuse.     

Small bowel Dieulafoy lesions: An uncommon cause of obscure bleeding in cirrhosis

Dieulafoy lesions (DLs) are an uncommon cause of gastrointestinal bleeding, accounting for up to 2% of cases overall. They are largely under recognised and difficult to treat. Up to 95% occur in the stomach, and only case reports document their occurrence in the small bowel (SB). Little is known about their pathophysiology, although there have been associations made previously with chronic liver disease, thought to be due to the erosive effects of alcohol on the mucosa overlying the abnormally dilated vessels. We present a case series of 4 patients with a long duration of obscure gastrointestinal bleeding, who were diagnosed with small intestinal DLs and incidentally diagnosed with chronic liver disease. The histories describe the challenges in both diagnosis and treatment of small intestinal DLs. Our case series suggest a previously unreported link between chronic liver disease and SB DLs which may be due to anatomical vasculature changes or a shift in angiogenic factors as a consequence of portal hypertension or liver cirrhosis.