CD8 memory T cells: cross-reactivity and heterologous immunity

Virus-specific memory T cell populations demonstrate plasticity in antigen recognition and in their ability to accommodate new memory T cell populations. The degeneracy of T cell antigen recognition and the flexibility of diverse antigen-specific repertoires allow the host to respond to a multitude of pathogens while accommodating these numerous large memory pools in a finite immune system. These cross-reactive memory T cells can be employed in immune responses and mediate protective immunity, but they can also induce life-threatening immunopathology or impede transplantation tolerance and graft survival. Here we discuss examples of altered viral pathogenesis occurring as a consequence of heterologous T cell immunity and propose models for the maintenance of a dynamic pool of memory cells.     

Recovery of fertility after grafting of cryopreserved germinative tissue in female rabbits following radiotherapy

BACKGROUND: Many cancer survivors face infertility as a consequenceof the aggressive treatment they must undergo. Cryopreservationof ovarian tissue before chemotherapy or radiotherapy may allowfor tissue transplantation after the treatment, and restorationof fertility. We tested the potential of an orthotopic autograftingof cryopreserved germinative tissue in female rabbits with ovarianfailure following radiotherapy. METHODS: Ten adult multiparousfemale rabbits were randomly allocated into two groups, fivein group I (control) and five in group II (transplant). Allrabbits underwent right oophorectomy with cryopreservation ofthe germinative tissue, followed by sterilization of the remainingleft ovary by radiotherapy. Later, group II rabbits receivedin the irradiated left ovary an implant of the frozen germinativetissue from the right ovary, whose small pieces were freelyspread intracortically in a procedure we named ‘intracorticalsowing of germinative tissue’ (ISGT). RESULTS: All groupII rabbits conceived following spontaneous mating within 6 monthsof the transplant, whereas none of the remaining rabbits ingroup I had conceived up to 11 months after transplant. CONCLUSIONS:This study suggests that fertility can be restored in rabbitsby sowing cortical tissue in a previously irradiated ovary.The clinical feasibility of this technique remains to be determined.     

Oxidative stress and antioxidant status in patients undergoing prolonged exposure to hyperbaric oxygen

OBJECTIVES: To evaluate the condition of oxidative stress in patients undergoing prolonged exposure to hyperbaric oxygen (HBO) and the possible modifications of the antioxidant defense systems in the absence of antioxidant supplementation. DESIGN AND METHODS: Twelve patients exposed to 15 HBO treatments for pathological conditions related to hypoxia were included in the study. Oxidative stress indices as well as plasma and erythrocyte antioxidant levels were measured in blood samples collected both at the 1st and 15th HBO session. RESULTS: The repeated exposures to HBO led to a significant accumulation of plasmatic reactive oxygen metabolites (ROM) and malondialdehyde (MDA). After 15 HBO sessions, no relevant differences were detected for reduced glutathione (GSH), alpha-tocopherol, and retinol plasma levels; however, a significant decrease in erythrocyte superoxide dismutase (SOD) and catalase (CAT) activity was observed when compared to the 1st HBO exposure; glutathione peroxidase (GPx) activity remained almost unchanged. CONCLUSIONS: In the absence of antioxidant supplementation, the prolonged HBO treatment leads to a condition of oxidative stress that seems to affect in particular the response of the enzymatic antioxidant defense system; the possible relationship between the chemical modifications of the enzymes caused by oxygen reactive species and the consequent inactivation of the proteins is under investigation.     

Metabolic syndrome as a predictor of all-cause and cardiovascular mortality in type 2 diabetes: the Casale Monferrato Study

OBJECTIVE: The aim of this study was to assess in an 11-year survival follow-up of a population-based cohort of type 2 diabetes the predictive role of World Health Organization-defined metabolic syndrome, independent of conventional cardiovascular risk factors. RESEARCH DESIGN AND METHODS: During the follow-up (1991-2001), 1,565 patients were regularly examined with centralized measurements of HbA(1c). The independent role of the metabolic syndrome as a predictor of all-cause and cardiovascular mortality was assessed with multivariate Cox proportional hazards modeling. RESULTS: At baseline, the prevalence of the metabolic syndrome was 75.6% (95% CI 73.6-77.9). Results are based on 685 deaths (520 with the metabolic syndrome and 165 without it) in 10,890.2 person-years of observations. With respect to subjects without the metabolic syndrome, those with the metabolic syndrome had a similar hazard ratio (HR) of cardiovascular mortality after adjustment for age, sex, smoking, total cholesterol level, and coronary heart disease. In contrast, relative to subjects with diabetes only, the HR of subjects with only one component of the syndrome was 2.92 (1.16-7.33), independent of other risk factors. CONCLUSIONS: We found that 1) the prevalence of the metabolic syndrome in a population-based cohort of type 2 diabetes is high (75.6%); 2) the metabolic syndrome is not a predictor of 11-year all-cause and cardiovascular mortality; and 3) more than twofold higher cardiovascular risk, independent of conventional risk factors, is evident in diabetic subjects with only one component of the syndrome compared with those with diabetes only. Categorizing type 2 diabetic subjects as having or not having the metabolic syndrome does not provide further prediction compared with the knowledge of its single components.     

Polymorphisms in the pertussis toxin promoter in Bordetella bronchiseptica veterinary isolates from Argentina

Five restriction patterns (including a novel one) could be defined by polymerase chain reaction-restriction fragment length polymorphism on the pertussis toxin (PT) promoter region in local veterinary isolates, suggesting that PT gene analysis is a potential molecular marker for Bordetella bronchiseptica detection and typing.