The influence of functional pinealectomy and exogenous melatonin application on healing of a burr hole in adult rat calvaria: a histological and immunohistochemical study.

BACKGROUND: Even today, repair of the cranial defects still represents a significant challenge in neurosurgery and various options have been used for their reconstruction to date. However, there are very few studies investigating the effects of exogenous administration of melatonin (MEL) as an agent that promotes bone regeneration. The goal of this study was to investigate the effects of functional pinealectomy (Px) and exogenous MEL administration on the bone repair properties and surrounding connective tissue alterations in a rat calvaria model. MATERIALS AND METHODS: The total of 30 adult female Wistar-Albino rats was randomly divided into three groups (n = 10): control group (CO; 12 h light/12 h dark exposure), functional Px group (24 h light exposure, light-induced functional Px), and Px+MEL group (light-induced Px + MEL, 20 mg/kg/day for 12 weeks). Critical-sized burr-hole defects (diameter: 3.0 mm) were surgically created by a single operator in the calvarium of all rats, using an electric drill. Animals in Px+MEL group received MEL 20 mg/kg/day for 12 weeks. At the end of the study, bone healing and connective tissue alterations surrounding drilled defect area in the rat calvaria were determined in haematoxylin-eosin-stained and Mallory Azan slices applied in anti-bone sialoprotein. Image Pro Express 4.5 programme was used for histomorphometric calculation of areas of new bone and fibrotic tissue. Normality control was performed by Shapiro-Wilk test. Variance homogeneities were examined by Shapiro-Wilk and Levene tests; Tukey HSD test was used as a post hoc method since there was no homogeneity problem. All hypothesis tests were performed at the 0.05 significance level. RESULTS: Histological analysis showed that the bone repair process in the Px+MEL group was similar to that of the CO group, whereas the functional Px group showed a delay. Histomorphometrically, it was found that the Px group had the largest hole diameter and the most fibrotic scar area, although no binary statistical significance was found between the CO and Px+MEL groups (p = 0.910). In terms of vascularisation, it was observed that the most vascular structure was found in the Px+MEL group among the scar tissue and ossification areas, while the vascularisation was the least in the Px group (p < 0.001). CONCLUSIONS: Our findings revealed that bone repair process was impaired in functional Px group, but exogenous MEL replacement was able to restore this response. Thus, it is concluded that utilisation of MEL may improve the bone repair in calvarial defects.

Effects of constant lightness, darkness and parachlorophenylalanine treatment on tail regeneration in the lizard Ophisops elegans macrodactylus: macroscopic, biochemical and histological changes.

A better understanding of regenerative growth is very important for the development of new potential strategies. Recently, the pineal secretory product melatonin was shown to stimulate the regeneration process. In this study, we carried out an experimental investigation of tail regeneration in young adult lizards, Ophisops elegans macrodactylus Berthold, 1842, addressing the role of melatonin on the regeneration process. Lizards were divided into three groups: constant light-exposed control group (n = 13), constant dark-exposed group (n = 15) and parachlorophenylalanine (p-CPA) treatment group exposed to constant light (n = 15). Using a tail autotomy procedure, the effects of p-CPA treatment on connective tissue together with neural tissue and vascular tissue in regenerating tail in lizards were investigated. p-CPA (400 microg/kg body mass) was injected from day 0 to 30 days after autotomy. p-CPA treatment produced a significant increase in the length of the regenerated tail compared with light-exposed control and dark-exposed lizards. Total collagen content was found to be higher in p-CPA-treated animals in comparison with other groups. Histologically, a higher percentage of connective tissue and vascular tissue and a lower percentage of neural tissue were found in the regenerated tails of the p-CPA-treated lizards. Importantly, the percentage of neural tissue in lizards in the dark-exposed animals was higher than that in animals of both light-exposed and p-CPA treatment groups. Thus, it is clear that p-CPA has a stimulatory influence on fibroblast collagen production and vascularization of the regenerated tail in the lizards. Furthermore, it seems that the neural regeneration process was markedly enhanced in lizards exposed to continuous darkness. Based on the results of our study, it is suggested that melatonin may be an active factor that speeds up the rate of tail regeneration in lacertilians.

Morphometry of the sacrum for clinical use.

Degenerative disease and instability in the lower lumbar spine may necessitate fusion and stabilization supplemented by instrumentation to the sacrum. However, screw placement in a reasonable position is more difficult to achieve because of the unique anatomy of the first sacral (S1) vertebra. Therefore, this study has been conducted to evaluate sacrum anatomy of the Western Anatolian population in terms of morphometric measurements and make a comparison with previous studies as well as giving a guidance to the surgeons. In this study, 60 dry adult sacrums (30 male and 30 female) were assessed for morphometric analysis. The measurement data for the sacrum and S1 vertebra revealed that there was no significant difference between both sexes except the sacral width and sacral canal width (p<0.05). In the present study, the ratio of S1 corpus' width to sacral width was lower in females compared with males. A detailed knowledge of the morphometric data about sacrum is very important for spinal surgery, as pedicle screw insertion is crucial in spinal instrumentation in order to prevent neurological injury and/or fixation failure.

Extremely rare type of conjoined twins: cephalothoracopagus deradelphus.

Occurrence of conjoined twins (CT) with a chromosomal abnormality is a very rare event. The case presented is that of a cephalothoracopagus Deradelphus twin with one cerebrum and two brain stems joined at the cranial end of the midbrain. This rare condition and its diagnosis and management are discussed with regard to counselling and obstetrical care.