Effects of intraocular rifampicin on retinal ganglion cell structure: a stereological and histopathological study.

AIM: To determine the histopathological changes of rifampicin applied intravitreally on retinal ganglion cells by means of stereological and histopathological methods. METHODS: For this study twenty-four New Zealand adult rabbits were divided into four groups (n=6 for each group). 50µg/0.1mL (group 1), 100µg/0.1mL (group 2), 150µg/0.1mL (group 3) and 200µg/0.1mL (group 4), rifampicin were injected into the vitreous of the right eyes of animals, their left eyes were used as control (group 5). After the 28(th) day of application, animals were anesthetised with xylazine (8mg/kg, IM) and then their eyes were enucleated immediately. Patterns were taken away and eyes were prepared for both stereological and electromicroscopic observation. RESULTS: Depending on the high dose of rifampicin, some histopathological changes such as cytoplasmic dilatation and damaged membrane were observed on the electromicroscopic level. Using quantitative examination, which was done at the light microscopic level, it was shown that the number of neurons decreased linearly as rifampicin dose increased when compared with the control group. CONCLUSION: Based on these findings, low-dose rifampicin (50µg/0.1mL) may be useful for treatment of the ocular diseases.

A new hypothesis about hematopoietic Pbx-interaction protein (HPIP): can it be a key factor in neurodegeneration in the post-menopausal period?

Neuronal degeneration in the post-menopausal term leads to cognitive symptoms such as anxiety, difficulty in concentrating, overreacting to minor upsets, quickly becoming irritated and forgetfulness in approximately 70-80% of all women around the world. These symptoms, which result from microtubule damage in the axon extensions of hippocampal neurons in during menopause, greatly reduce individuals' life quality. Thus, an investigation of the estrogen receptor-signaling pathway-microtubule dynamic triangle and the possible links between them is important when it comes to explaining the possible mechanism of neurodegeneration. Hematopoietic Pbx-interaction protein (HPIP), a microtubule-binding protein, is a novel scaffolding protein. The detection of this protein on neurons represents the most important step in our hypothesis. The importance of the hypothesis is that it might provide important clues about the possible role of HPIP and its mechanism through in vivo and in vitro studies of estrogen receptors-microtubules and the HPIP triangle in terms of neuronal degeneration in the post-menopausal period. A preliminary study was performed to test the main part of our hypothesis using real-time PCR. According to the results, the mRNA expression of HPIP was found in hippocampal neurons. After the detection of this novel protein in neurons, it was observed that there were differences in the experimental groups when compared with the control group relating to the mRNA expression of this protein. An important scientific question remains concerning the mechanisms of neurodegeneration appearing in the post-menopausal period and the receptors, proteins, and signaling pathways that play a role in this degeneration. In consideration of the data from in vivo and in vitro studies used to test our hypothesis, we will try to address the relevant questions. As this issue is resolved, new studies and treatment procedures that can help to prevent the possible difficulties in the menopausal period will be illuminated.

Peripheral 5-HT7 receptors as a new target for prevention of lung injury and mortality in septic rats.

Sepsis is a complex pathophysiological event involving metabolic acidosis, systemic inflammatory response syndrome, tissue damage and multiple organ dysfunction syndrome. Although many new mechanisms are being investigated to enlighten the pathophysiology of sepsis, there is no effective treatment protocol yet. Presence of 5-HT7 receptors in immune tissues prompted us to hypothesize that these receptors have roles in inflammation and sepsis. We investigated the effects of 5-HT7 receptor agonists and antagonists on serum cytokine levels, lung oxidative stress, lung histopathology, nuclear factor κB (NF-κB) positivity and lung 5-HT7 receptor density in cecal ligation and puncture (CLP) induced sepsis model of rats. Agonist administration to septic rats increased survival time; decreased serum cytokine response against CLP; decreased oxidative stress and increased antioxidant system in lungs; decreased the tissue NF-κB immunopositivity, which is high in septic rats; and decreased the sepsis-induced lung injury. In septic rats, as a result of high inflammatory response, 5-HT7 receptor expression in lungs increased significantly and agonist administration, which decreased inflammatory response and related mortality, decreased the 5-HT7 receptor expression. In conclusion, all these data suggest that stimulation of 5-HT7 receptors may be a new therapeutic target for prevention of impaired inflammatory response related lung injury and mortality.

Comparative study of three angiotensin II type 1 receptor antagonists in preventing liver fibrosis in diabetic rats: stereology, histopathology, and electron microscopy.

The presence of liver disease in patients with progressively worsening insulin resistance may not be recognized until patients develop manifestations of the metabolic syndrome such as diabetes, hypertension, hyperlipidemia, and vascular disease. It was aimed to investigate whether three angiotensin II type 1 receptor antagonists (ARBs) (olmesartan, losartan, and valsartan) had preventive effect against hepatic fibrosis and this was a common characteristic among ARBs. In current study, 25 adult male rats were used and divided into five groups: the non-diabetic healthy group, alloxan induced diabetic (AID) control group, AID losartan group, AID valsartan group and AID olmesartan group. According to numerical density of hepatocytes, significant difference was found between the non-diabetic healthy group and diabetic control group. All treatments groups were significant when compared to diabetic control group. In diabetic control group it was examined swelling, irregular cristae arrangement in some of mitochondria. It was also determined mitochondria membrane degeneration in some areas of section profiles. In diabetic rats treated with losartan group, there were necrotic hepatocytes. In diabetic rats treated with valsartan group, predominantly, findings were similar to losartan group. In diabetic rats treated with olmesertan group, plates of hepatocytes were quite regular. There were hardly necrotic cells. Not only other organelles such as RER, SER and lysosom but also mitochondrial structures had normal appearance. In the diabetic control group electron microscopy revealed edema in both the cytoplasm and perinuclear area and the nuclear membranes appeared damaged. In conclusion, it was established that the most protective ARB the liver in diabetic rats was olmesartan, followed by losartan.

Effects of diabetes mellitus on the rat liver during the postmenopausal period.

The present study investigated whether diabetes worsened the onset of liver injury/damage during the ovariectomized (OVX)-induced postmenopausal period in rats. Diabetes results in severe complications in humans, such as liver failure. Estrogen and its derivatives are medically acceptable, powerful antioxidant agents that can enable liver and other important organs to defend themselves against oxidative related injury. Estrogen deficiency, which occurs in the postmenopausal period and in individuals with diabetes, may play a significant role in the progression of liver failure. In the present study, rats were divided into four groups: control (Group I), diabetic (Group II), ovariectomy (Group III) and ovariectomy plus diabetes (Group IV). After the experiments, quantitative histopathological and immunohistochemical changes in liver were detected using light microscopy and modern stereological systems. Histopathological examinations showed that there were many necrotic and apoptotic hepatocytes in the lobules of Group II. In addition, there were a larger number of necrotic cells in Group III than Group II. In contrast to Group II, there were also apoptotic cells in the portal areas in Group III. Moreover, evidence of liver injury was higher in the sections of Group IV compared with all other groups. In biochemical findings, there were statistically significant differences between all the groups (P < 0.001) for catalase (CAT), glutathione peroxidase (GSH) and myeloperoxidase (MPx) activity. In addition, the amount of lipid peroxidation (LPO) was significantly different between groups. In stereological results, there were significant differences between Groups I and II and Groups II and IV. The present study provided novel insight into the pernicious effects of ovariectomy on liver injury following the onset of diabetes. Indeed, the present study found that increases in liver oxidative activity in OVX rats following the onset of diabetes correlates with elevated MPx, LPO and histopathological changes in rat liver.

A stereological assessment method for estimating the surface area of cycloids.

OBJECTIVE: In this study, we sought to determine differences in estimations of surface area made by classical vertical uniform random (VUR) section series and vertical section series obtained perpendicular to a fixed horizontal plane. MATERIALS AND METHODS: One volunteer subject (male, 25 years of age) with no neurological deficit was chosen at random from a bank of controls in the magnetic resonance (MR) image data library of the Department of Radiology. First, a soccer ball with known geometrical features (radius: 9.75 cm) was imaged using a T1-weighted MR scanner at 5-mm thickness (total 40 sections) to test the validity and reliability of surface area and volume measurements obtained via stereological methods. Second, T1-weighted MR section profiles were obtained from a volunteer individual. Surface area and volume estimation procedures were carried out using the Stereo Investigator 6, MicroBright-Field, Inc., USA. CONCLUSIONS: We determined that there are no differences in either surface area or volume estimations made using VUR sections and direct vertical sections. We have performed an exhaustive series analysis with a variety of objects.

Neuroprotective effects of methylprednisolone and hypothermia after experimental spinal cord injury: a histopathological and stereological study.

OBJECTIVE: Spinal cord injury is a common trauma among severe accidents in which the spinal cord has been severed; intravenous methylprednisolone and hypothermia are widely used in the treatment of traumatic spinal cord injuries. However, no common consensus has been reached on therapeutic approaches to prevent and reduce disability caused by spinal cord injuries. In this study, the efficacy of methylprednisolone and hypothermia treatments after experimental spinal cord injury made by dynamic weight-drop model in rabbits was investigated. MATERIALS AND METHODS: This experiment consists of three groups: injured, methylprednisolone-treated and hypothermia-treated groups. The methylprednisolone-treated group received intravenous methylprednisolone (30 mg/kg/day) immediately after spinal cord injury for three days. In the hypothermia-treated group, cold isotonic saline (5°C) was infused via a cannula into the epidural space at a rate of 10 ml/min. The temperature of the tissue was allowed to reach 25ºC, and then isotonic saline solution was given at a rate of 5 ml/min for 3 hours. Saline was given to the injured group following spinal cord injury. After 1 week of experimental injury, mid-thoracic level tissue was removed from the spinal cord for histopathological evaluation and subsequent stereological analysis. RESULTS: The volume of spinal cord segment, not only parenchyma of grey and white matter but also cavity, was estimated by the Cavalieri principle. Significant differences were seen between the injured group and methylprednisolone /hypothermia-treated groups in terms of the total volume cavity of spinal cord segment; cavity volume in the grey matter and cavity volume in the white matter. No significant differences were seen between methylprednisolone and hypothermia-treated groups in terms of the total volume cavity of spinal cord segment; cavity volume in the grey matter and cavity volume in the white matter. CONCLUSIONS: These results suggested that both methylprednisolone and hypothermia treatment are neuroprotective in preventing spinal cord tissue from tissue damage after experimental injury.