Effects of whole-body hypoxic preconditioning on hypoxia/reoxygenation-induced intestinal injury in newborn rats.

PURPOSE: The precise cause of necrotizing enterocolitis (NEC) is elusive. Ischemia and reperfusion injury of the intestine has been considered to be a major contributing factor for NEC. Ischemic preconditioning is defined as one or more brief periods of ischemia with intermittent reperfusion that protects tissues against a sustained period of subsequent ischemia. Contribution of preconditioning to hypoxia/reoxygenation-induced intestinal injury in newborn rats has not been evaluated previously. METHODS: The study was carried out on 1-day-old Wistar albino rat pups. Whole-body hypoxia and reoxygenation (H/R) was achieved by 10 min hypoxia using 95 % N (2) + 5 % CO (2) followed by 10 min reoxygenation with 100 % oxygen. Whole body hypoxic preconditioning (HP) cycles were performed with 3 min hypoxia and 5 min reoxygenation. Thirty-three pups were randomly allocated into 4 groups. Group 1 served as untreated controls. The pups in group 2 were subjected to H/R only. In groups 3 and 4, 1 cycle and 3 cycles of HP were performed prior to H/R, respectively. Animals were killed at the end of the protocols. Intestine specimens were obtained to determine the histological changes, as well as to measure the tissue malondialdehyde (MDA) and nitric oxide (NO) levels, and xanthine oxidase (XO) and myeloperoxidase (MPO) activities. RESULTS: The microscopic lesions in H/R rat pups were virtually the same as those seen in neonatal NEC, with severe destruction of villi and crypts, in some cases extending to the muscularis. In both HP groups, the lesions were found to be milder. H/R resulted in a marked elevation in MDA and NO levels, and XO and MPO activities compared to the untreated controls. Both 1 cycle and 3 cycles of HP prior to H/R resulted in an obvious decrease in all biochemical parameters. Differences of the biochemical results between both HP groups were not statistically significant. CONCLUSION: This study revealed that whole-body hypoxic preconditioning is beneficial for hypoxia/reoxygenation-induced intestinal injury in newborn rats.

Determination of plasma fibronectin and serum C-reactive protein in patients with cerebrovascular events.

The relationship between the levels of C-reactive protein (CRP) and fibronectin (FN) and atherosclerotic diseases such as coronary heart disease has already been studied, but their relationship with cerebrovascular events has not. The aim of this study was to determine the levels of plasma FN and serum CRP in cerebrovascular events, and their relationship with the outcome of the disease. CRP and FN levels were analysed in 133 patients with acute cerebrovascular disease, together with 66 healthy controls. Cerebrovascular event patients were divided into subgroups according to disease severity. FN and CRP levels in patients with cerebrovascular disease were found to be significantly elevated compared with the control group (p<0.001). CRP levels correlated with disease severity, in contrast to FN levels. We conclude that FN is not a clinically useful marker in patients with acute differentiative cerebrovascular events, in contrast to CRP which may be useful in such cases.

Effects of unilateral uterine artery ligation on skin development.

BACKGROUND: It has been previously demonstrated that intrauterine growth retardation (IUGR) due to vascular insufficiency in humans results in newborn infants with marked loss of subcutaneous fat and decreased content of differentiation-specific epidermal structural proteins. OBJECTIVE: In this study, the teratogenic effects of impaired maternal blood flow were investigated histologically on rat skin. MATERIALS & METHODS: Twenty Spraque-Dawley female rats were separated into two groups (n = 10), a control (sham-operated) and an experimental group. The experimental group of fetal rats were subjected to IUGR by unilateral ligation of the maternal uterine artery on the 18th day of pregnancy. The maternal rats were subjected to cesarean hysterectomy on the 21st day of pregnancy and a skin biopsy was taken from the respective litters of both groups. RESULTS: In histopathological examination, normal epidermis and dermis were observed in the control group of litters and littermate rats from the opposite uterine horn (non-ligated side). A statistically significant reduced body weight and height were noted in the ligated side of the litters. CONCLUSION: Our findings give further evidence to the concept that normal maternal blood flow is essential for fetal growth and decreased maternal blood flow may create an impairment in skin development.

Evaluation of the effects of different biomaterials on bone defects.

Studies concerning natural and synthetic graft materials that have been used in different medical procedures have focused on freeze-dried bone, coral, hydroxylapatite, and tricalcium phosphate. This study histologically investigates the effects of these materials on the healing of bone defects. The experiments were performed on 30 albino rabbits. Cavities were drilled in the posterior right tibias of rabbits and were filled with coral, freeze-dried bone, hydroxylapatite, or calcium hydroxide. One cavity was left unfilled as a control. The bone in which the materials were implanted was excised at 7, 15, 30, 45, and 60 days. After the histological staining procedures, the prepared materials were observed using a light microscope. Although all materials showed good bone remodeling at the end of 60 days, coral and hydroxylapatite materials could be seen in the bone structure. The most effective materials within bone defect improvement were freeze-dried bone and calcium hydroxide.