Faculty Bibliography

BACKGROUND AND AIMS:Circulating lipoprotein (a) [Lp(a)] level relates inversely to apolipoprotein (a) [apo(a)] size. Both smaller apo(a) isoforms and higher Lp(a) levels have been linked to coronary heart disease and stroke, but their independent contributions are less well defined. We examined the role of Lp(a) in younger adults with cryptogenic stroke. METHODS:Lp(a) and apo(a) isoforms were evaluated in a prospectively designed case-control study of patients with unexplained ischemic stroke and stroke-free controls, ages 18 to 64. Serum Lp(a) was measured among 255 cases and 390 controls with both apo(a)-size independent and dependent assays. Apo(a) size was determined by agarose gel electrophoresis. RESULTS:Cases and controls were similar in socio-demographic characteristics, but cases had more hypertension, diabetes, smoking, and migraine with aura. In race-specific analyses, Lp(a) levels showed positive associations with cryptogenic stroke in whites, but not in the smaller subgroups of blacks and Hispanics. After full adjustment, comparison of the highest versus lowest quartile in whites was significant for apo(a)-size-independent (OR = 2.10 [95% CI = 1.04, 4.27], p = 0.040), and near-significant for apo(a)-size-dependent Lp(a) (OR = 1.81 [95% CI = 0.95, 3.47], p = 0.073). Apo(a) size was not associated with cryptogenic stroke in any race-ethnic subgroup. CONCLUSIONS:This study underscores the importance of Lp(a) level, but not apo(a) size, as an independent risk factor for unexplained ischemic stroke in young and middle-aged white adults. Given the emergence of effective Lp(a)-lowering therapies, these findings support routine testing for Lp(a) in this setting, along with further research to assess the extent to which such therapies improve outcomes in this population.

Brain magnetic resonance imaging is widely used as a diagnostic and monitoring tool in multiple sclerosis and provides a non-invasive, sensitive and reproducible way to track the disease. Topological characteristics relating to the distribution and shape of lesions are recognized as important neuroradiological markers in the diagnosis of multiple sclerosis, although these have been much less well characterized quantitatively than have traditional measures such as T2 hyperintense or T1 hypointense lesion volumes. Here, we used voxel-level 3 T magnetic resonance imaging T1-weighted scans to reconstruct the 3D topology of lesions in 284 subjects with multiple sclerosis and tested whether this is a heritable phenotype. To this end, we extracted the genotypes from a published genome-wide association study on these same individuals and searched for genetic associations with lesion load, shape and topological distribution. Lesion probability maps were created to identify frequently affected areas and to assess the overall distribution of T1 lesions in the subject population as a whole. We then developed an original algorithm to cluster adjacent lesional voxels (cluxels) in each subject and tested whether cluxel topology was significantly associated with any single-nucleotide polymorphism in our data set. To focus on patterns of lesion distribution, we computed the first 10 principal components. Although principal component 1 correlated with lesion load, none of the remaining orthogonal components correlated with any other known variable. We then conducted genome-wide association studies on each of these and found 31 significant associations (false discovery rate <0.01) with principal component 8, which represents a mode of variation of lesion topology in the population. The majority of the loci can be linked to genes related to immune cell function and to myelin and neural growth; some (SYK, MYT1L, TRAPPC9, SLITKR6 and RIC3) have been previously associated with the distribution of white matter lesions in multiple sclerosis. Finally, we used a bioinformatics approach to identify a network of 48 interacting proteins showing genetic associations (P < 0.01) with cluxel topology in multiple sclerosis. This network also contains proteins expressed in immune cells and is enriched in molecules expressed in the central nervous system that contribute to neural development and regeneration. Our results show how quantitative traits derived from brain magnetic resonance images of patients with multiple sclerosis can be used as dependent variables in a genome-wide association study. With the widespread availability of powerful computing and the availability of genotyped populations, integration of imaging and genetic data sets is likely to become a mainstream tool for understanding the complex biological processes of multiple sclerosis and other brain disorders.

OBJECTIVES/OBJECTIVE:The role of endogenous cannabinoids in ischemia/reperfusion induced germ cell apoptosis in rats was investigated. METHODS:Baseline group was for basal normal values. The Sham operated group served as a control group. The torsion/detorsion (T/D) group underwent torsion (1 h) and detorsion; AN1, AN2, and AN3 groups received anandamide (10 mg/kg) 30 min before torsion, 30 min after torsion, and just after detorsion, respectively. In the AM251 group, AM251 (0.5 mg/kg) was injected 45 min before torsion and in the AN/AM group, AM251 and anandamide were injected 45 and 30 min before torsion, respectively. Lipid peroxidation, antioxidant enzymes, and germ cell apoptosis was determined. RESULTS:Malondialdehyde (MDA) levels in the T/D group were significantly higher than the control group. Moreover, MDA values in the AN1, AN2, and AN3 groups were significantly lower than T/D. There were significant decreases in catalase and superoxide dismutase activities in the T/D group versus the control group. These values in the AN1, AN2, and AN3 groups were significantly higher than T/D. It was also shown that MDA levels in the AN/AM group were significantly higher than the AN1 group. In the AN/AM group, catalase and superoxide dismutase activities were significantly lower versus the AN1 group. The mean germ cell apoptosis scores in all animals with testicular T/D were significantly higher than the control group. There was no difference between the apoptotic indices in the AN1, AN2, AN3, and T/D groups. Apoptosis scores in AM251 and AN/AM were significantly higher compared with the T/D and AN1 groups. CONCLUSIONS:Although anandamide increased antioxidant markers, it failed to reduce germ cell apoptosis. AM251 worsened the antioxidant defense system, which is reflected as higher germ cell apoptosis.

PURPOSE/OBJECTIVE:We assessed the effectiveness of sildenafil administration during ischemic period in a rat model of testicular torsion/detorsion (T/D). MATERIAL AND METHODS/METHODS:Sprague-Dawley rats were divided into four groups (n = 10). In those animals that underwent T/D, right testes were rotated 720 degrees for 1 h. Base line group was for basal normal values. Sham operated group was served as a control group. T/D group underwent 1 h testicular torsion. Sildenafil group received sildenafil (0.7 mg/kg) intraperitoneally 30 min after initiation of ischemic period. For measurement of lipid peroxidation and antioxidant enzyme activities, right testes of five animals in each group were excised after 4-h reperfusion. Germ cell apoptosis indices were determined 24 h following detorsion in right testes of remaining five animals in each group. RESULTS:Malondialdehyde (MDA) levels in T/D group were significantly higher versus control and base line groups. Moreover, testicular MDA values in sildenafil group were significantly lower than T/D. There were also significant decreases in catalase and superxide dismutase activities in T/D group compared with control and base line groups. These values were significantly higher in sildenafil group versus T/D. Germ cell apoptosis indices were significantly higher in both groups that experienced T/D in comparison to control and base line groups; however, sildenafil treatment significantly reduced the apoptosis in sildenafil group compared with T/D group. CONCLUSION/CONCLUSIONS:Sildenafil administration during testicular torsion decreased ischemia/reperfusion cellular damage. The results of biochemical studies suggest that, reduction of oxidative stress by sildenafil may have a major role in its cytoprotective effects.

Recently many researchers have proposed a protective role for morphine against tumor growth and metastasis, especially through induction of apoptosis in tumoral cells. These findings may lead to underestimation of cytotoxic effects of opioid drugs which are usually expected only at high doses. The present study was conducted to clarify whether repeated morphine administration, which is commonly used for relief from chronic pain, would interfere with liver antioxidant defence and hepatocytes vitality. Morphine was injected repeatedly at doses that have been reported to relieve cancer pain and reduce tumor spread in mice (5 and 10 mg/kg/day for nine consecutive days). The changes in hepatic glutathione concentration, its synthesis pathway and enzymatic antioxidant defense revealed the pro-oxidant effects of chronic morphine treatment on the liver. None of these changes were observed in those mice that were co-treated with naltrexone (opioid antagonist) and same doses of morphine. However induction of liver conjugating enzymes following morphine treatment was not receptor mediated. Moreover, chronic morphine treatment induced hepatocytes apoptosis. Interestingly, the apoptotic changes were antagonized by co-administration of either naltrexone or thiol antioxidant. In conclusion, although hepatotoxic effects of morphine at high doses have been reported previously, our findings propose that repeated morphine administration even at lower doses would induce oxidative stress in the liver, which may contribute to induction of apoptosis in hepatocytes. Since many of the observed adverse effects were mediated by opioid receptors, our results suggest that other opioid analgesics should also be used more cautiously.

Ischemic preconditioning (IPC) and pharmacologic preconditioning by morphine and adenosine may significantly decrease the amount of necrosis in rat random pattern skin flaps. We examined the role of ATP-sensitive potassium channels (K(ATP) channels) in mediating these protective phenomenon by using glibenclamide a nonspecific blocker of these channels. We also investigated whether administration of diazoxide an opener of the K(ATP) channels could mimic the same protective effect. Ninety male Sprague-Dawley rats were randomly divided into either control or treatment groups (n = 6 each). Bipedicled dorsal skin flaps (2 x 8 cm) were elevated at the midline. In pharmacologic preconditioning groups, 1 mL of morphine (5 mg/flap), adenosine (0.5 mg/flap), or different doses of diazoxide (0.5, 1, 5, and 15 mg/flap) were administered locally in the cranial half of the flap, respectively. One milliliter of saline was locally injected in the control group. In the IPC group, 1 hour after local saline injection the cranial pedicle was clamped for 20 minutes, and then 40 minutes' reperfusion was performed. In another experiment, 0.3 mg/kg of glibenclamide was injected intraperitoneally 30 minutes before local administration of saline or drug in ischemic or pharmacologic preconditioning groups. Regardless of the group, all flaps were cut at the cranial side 2 hours after elevation and were sutured back. Flap survival area was evaluated on the seventh postoperative day. IPC and pharmacologic preconditioning with morphine, adenosine, and diazoxide (in higher doses; 1, 5, and 15 mg/flap) improved survival area compared with the control group. Glibenclamide abolished their protective effect. K(ATP) channels may have a key role in anti-ischemic properties of IPC and pharmacologic preconditioning.

OBJECTIVES/OBJECTIVE:To investigate the effects of morphine on reperfusion injury due to testicular torsion-detorsion (T/D). METHODS:We divided 36 adult male Sprague-Dawley rats into six groups. Testicular ischemia was achieved by twisting the right testis 720 degrees counterclockwise for 1 hour, and reperfusion was allowed for 4 hours after detorsion. The baseline group was for basal normal values. The sham-operated group served as the control group. The T/D group underwent 1 hour of testicular torsion and 4 hours of detorsion. The morphine group received pretreatment with intravenous morphine sulfate (10 mg/kg) just before detorsion. The naltrexone group received an intravenous injection of naltrexone HCl (20 mg/kg) 15 minutes before detorsion. The naltrexone/morphine group received intravenous administration of naltrexone HCl (20 mg/kg) 15 minutes before detorsion and morphine sulfate (10 mg/kg) just before detorsion. RESULTS:The ipsilateral malondialdehyde levels in the T/D group were significantly greater than in the control and baseline groups. Moreover, the ipsilateral testicular malondialdehyde values in the morphine group were significantly lower than in the T/D and naltrexone/morphine groups. Also, significant decreases occurred in catalase and superoxide dismutase activities in the T/D group compared with the control and baseline groups. These values were significantly greater in the morphine group than in the T/D and naltrexone/morphine groups. The ipsilateral testes of all groups that underwent testicular torsion showed similar histopathologic changes. CONCLUSIONS:Morphine increased the ipsilateral intratesticular antioxidant markers during the reperfusion phase after unilateral testicular torsion, which was eventually reflected in lower testicular malondialdehyde levels. Furthermore, this effect was mediated through the opioid receptors.