Structural and functional protection of photoreceptors from MNU-induced retinal degeneration by the X-linked inhibitor of apoptosis

PURPOSE: To evaluate the neuroprotective effects of adenoassociated virus delivery of XIAP in N-methyl-N-nitrosourea (MNU)-induced retinal degeneration in Sprague-Dawley rats. METHODS: Sprague-Dawley rats were injected subretinally with recombinant adenoassociated virus (rAAV) encoding either XIAP or green fluorescent protein (GFP; injection control). Six weeks after injection, the animals received an intraperitoneal injection of MNU, a DNA methylating agent, at a dose of 60 mg/kg. Electroretinograms (ERGs) were recorded at 0, 24, 48 and 72 hours and 1 week after MNU. The rats were killed after the ERG was performed and were perfused with 4% paraformaldehyde. Eyes were then enucleated and embedded for cryosectioning. Eye sections were analyzed by TUNEL and histologic techniques. Real-time PCR and Western analysis were performed to confirm the overexpression of XIAP in injected eyes. RESULTS: Real-time PCR and Western analysis confirmed the overexpression of XIAP in virus-injected eyes in comparison to uninjected control eyes. At 24 hours after MNU injection, fewer cells had undergone apoptosis in the XIAP-treated eyes in comparison with GFP-injected or uninjected eyes. Hematoxylin and eosin staining revealed that the uninjected and GFP-injected photoreceptors were destroyed by 72 hours after injection of MNU, whereas the AAV-XIAP-injected eyes showed structural protection of the photoreceptors at all time points throughout the 1-week sampling period. ERGs showed functional protection up to 1 week after MNU injection in the AAV-XIAP-injected eye, whereas no response was observed in the control eye. CONCLUSIONS: The results suggest that XIAP is protective against this potent chemotoxic agent and holds promise as a therapeutic agent in gene therapy approaches to treating retinitis pigmentosa.     

Focal inner retinal hemorrhages in patients with drusen: an early sign of occult choroidal neovascularization and chorioretinal anastomosis

PURPOSE: To present evidence that superficial retinal hemorrhage in the macula of patients with age-related macular degeneration (ARMD) may be an early sign of occult chorioretinal anastomosis (OCRA) and type 1 occult choroidal neovascularization (OCNV). METHODS: Retrospective follow-up study of 16 patients presenting with a small focal area of superficial retinal hemorrhages and drusen in the juxtafoveolar area in 24 eyes. RESULTS: OCRA and OCNV occurred in an older subset of patients with ARMD (mean age, 75 years). Of 22 eyes with the early stages of chorioretinal anastomosis (CRA), 18 had evidence of a piggyback neovascular complex, with the smaller subsensory retinal type 2 complex lying anterior to the larger subretinal pigment epithelial type 1 complex. At initial presentation, three patients had OCRA and OCNV bilaterally, and three patients had large disciform cicatricial lesions with overt CRA in the fellow eye. Nine patients had one or more laser photocoagulation treatments for early stages of CRA. Only one patient maintained visual acuity of better than 20/200 for >1 year. At the last follow-up, 24 of 26 eyes with CRA had visual acuity of 20/200 or less. CONCLUSION: Superficial retinal hemorrhage in the paracentral area of patients with drusen is the earliest sign of OCRA and OCNV. Fluorescein angiography and indocyanine green angiography are important in detecting the dual nature of the subretinal neovascular network. Photocoagulation and photodynamic treatment is usually unsuccessful in preserving central vision.     

Cataract surgery in patients with age-related macular degeneration: one-year outcomes

PURPOSE: To determine whether patients with age-related macular degeneration (ARMD) benefit from cataract surgery and to assess the risk of progression of preexisting maculopathy 4 and 12 months postoperatively. SETTING: Princess Alexandra Eye Pavilion, Royal Infirmary of Edinburgh, Edinburgh, Scotland. METHODS: Two groups of patients were evaluated prospectively. The study group comprised patients with ARMD scheduled to have cataract surgery (n = 40). The control group comprised patients with ARMD not having cataract surgery (n = 43). Patients were assessed at baseline (preoperatively) and 4 and 12 months postoperatively. Assessment included visual function tests and quality of life (QoL) measures. The mean values for each item tested were obtained for each group at each visit, and comparisons between visits were done using the Wilcoxon signed rank test. RESULTS: There were significant benefits of cataract surgery in terms of visual function and QoL measures at 4 and 12 months. There was no increased risk of progression of maculopathy in the study group. There were no significant differences in the items tested in the control group. CONCLUSIONS: One year postoperatively, QoL benefits were maintained in the study group and there was no increased risk of progression of maculopathy in patients with mild and moderate degrees of ARMD. Larger numbers of patients must be assessed prospectively for longer periods to determine the relative risk of progression of different stages of ARMD after cataract surgery.     

pH-induced modifications to stratum corneum lipids investigated using thermal,spectroscopic, and chromatographic techniques

The effects of nonphysiological pH on stratum corneum lipid content and structure have been studied. Human stratum corneum samples were soaked in solutions at pH 1, 2, 6, 11, or 12 for up to 24 h. After removal of the stratum corneum, the buffer solutions were analyzed for lipid composition using thin-layer chromatography analysis and the stratum corneum sheets were examined using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The results demonstrate that only buffers of pH 11 or higher affect the stratum corneum lipids. No large difference in the contents of ceramides and cholesterol extracted by buffers of varying pH was observed. In contrast, free fatty acid extraction was pH dependent; amounts removed by 24-h treatment with pH 11 or 12 buffers were comparable, and were similar to amounts extracted with a methanol-chloroform mixture for 15 min. No appreciable changes in DSC and FTIR spectra were detected between untreated stratum corneum and stratum corneum samples treated with buffers at pHs in the range 1-6. For tissue treated with pH 11 and 12, the position of the endothermal melting peak T2 shifted from 72 to 74 degrees C on the DSC thermograms. Small changes in the broadness of spectral peaks at 2855 cm(-1) [attributable to upsilon(CH(2)) stretching of stratum corneum lipids and 1655 cm(-1) upsilon(C=O) stretching amide I band] can be seen in the FTIR spectra from the treated stratum corneum samples, although no shifts in peak positions were observed. Intensity changes in peaks from extraneous lipids [upsilon(C=O) stretching mode at 1735 cm(-1)] were observed after buffer treatments. The changes provoked by the alkaline buffers are not dramatic and it may be concluded that the stratum corneum appears remarkably resilient to extended exposure in both highly acidic (pH 1) and highly alkaline (pH 12) environments.     

Modeling biotransformation reactions by combined quantum mechanical/molecular mechanical approaches: from structure to activity

An overview of the combined quantum mechanical/molecular mechanical (QM/MM) approach and its application to studies of biotransformation enzymes and drug metabolism is given. Theoretical methods to simulate enzymatic reactions have rapidly developed during the last decade. In particular, QM/MM methods provide detailed insights into enzyme catalyzed reactions, which can be extremely valuable in complementing experimental research. QM/MM methods allow the reacting groups in the active site of an enzyme to be studied at a quantum mechanical level, while the surrounding protein and solvent is included at a classical (and computationally less expensive) molecular mechanical level. Existing QM/MM implementations vary in the level of interaction between the QM and MM regions and in the way the partitioning into QM and MM regions is setup. Some general considerations concerning reaction modeling are discussed and a number of QM/MM studies related to drug metabolism are described. These studies illustrate that theoretical modeling of important metabolic reactions provides detailed insights into mechanisms of reaction and specific catalytic effects of enzyme residues as well as explaining variation in rates of conversion of different metabolites. Such information is essential in the development of methods to predict metabolism of drugs and to understand metabolic effects of genetic polymorphism in biotransformation enzymes.     

Distribution of methyl sulfone metabolites of polychlorinated biphenyls and p,p'-DDE in human tissues

We determined methylsulfonyl metabolites of chlorinated biphenyls (MeSO2-CBs) and 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (p,p'-DDE) in human adipose, liver, brain, and lung tissues obtained from 11 Belgian individuals (9-62 years of age). The total concentration of MeSO2-CBs (lipid weight basis) decreased in the following order: liver (mean, 9.30 ng/g; range, 1.68-27.03 ng/g lipid) > lung [mean, 2.72 ng/g; range, not detected (ND) to 11.54 ng/g lipid] > adipose tissue (mean, 1.57 ng/g; range, 0.33-4.33 ng/g lipid) > brain (mean, 0.24 ng/g; range, ND-0.56 ng/g lipid). The profiles of MeSO2-CBs and MeSO2-DDE in each tissue were similar for all 11 subjects. In adipose, brain, and lung tissues, 4'-MeSO2-CB87, 4'-MeSO2-CB101, and 3-MeSO2-CB149 (except brain) occurred at higher concentrations than did other MeSO2-CBs. However, 3'-MeSO2-CB132 was by far the most abundant congener in liver, contributing on average to approximately 60% of the sum of MeSO2-CBs. The concentrations of 3-MeSO2-DDE in different tissues were at the same or lower levels than the total concentrations of MeSO2-CBs. This study suggests that the distribution patterns of MeSO2-CBs and MeSO2-DDE in humans differ between liver and other tissues. Moreover, these profiles differ from those found in other mammals, such as polar bears, porpoises, and otters.     

Sequential compression devices as prophylaxis for venous thromboembolism in high-risk colorectal surgery patients: reconsidering American Society of Colorectal Surgeons parameters

The American Society of Colorectal Surgeons (ASCRS) recently endorsed low-molecular-weight heparin and low-dose heparin as primary prophylaxis for venous thromboembolism (VTE) in highest-risk patients. Our study evaluates the feasibility of sequential compression device (SCD) use for VTE prophylaxis in these patients. Computerized databases of discharge diagnoses from three hospitals were reviewed. All patients with colorectal cancer or inflammatory bowel disease during a 7-year period were identified. Those who underwent major abdominal surgery and received VTE prophylaxis exclusively with SCDs were selected for the study. Patients diagnosed with postoperative VTE were identified through review of the three databases and of patient records for 90 days after surgery. One thousand two hundred eighty-one patients classified as highest-risk under the published ASCRS parameters underwent major abdominal surgery and received SCDs perioperatively. The incidence of clinically detectable postoperative VTE was 0.78 per cent. There were trends toward lower incidence among patients with malignancy (0.53%) compared with inflammatory bowel disease (1.48%, P = 0.09), and those with abdominal compared to pelvic procedures (0.62% vs. 1.04%, P = 0.41). Prophylaxis for perioperative VTE solely with SCD is a viable option for patients classified as highest-risk under ASCRS parameters.     

Disaster victim identification of military aircrew, 1945-2002

BACKGROUND: Aviation accident fatalities are characterized by substantial tissue disruption and fragmentation, limiting the usefulness of traditional identification methods. This study examines the success of disaster victim identification (DVI) in military aviation accident fatalities in the Australian Defense Force (ADF). METHODS: Accident reports and autopsy records of aircrew fatalities during the period 1945-2002 were examined to identify difficulties experienced during the DVI process or injuries that would prevent identification of remains using non-DNA methods. RESULTS: The ADF had 301 aircraft fatalities sustained in 144 accidents during the period 1945-2002. The autopsy reports for 117 fatalities were reviewed (covering 73.7% of aircrew fatalities from 1960-2002). Of the 117 victims, 38 (32.4%) sustained injuries which were severe enough to prevent identification by traditional (non-DNA) comparative scientific DVI techniques of fingerprint and dental analysis. CONCLUSIONS: Many of the ADF fatalities who could not be positively identified in the past could be identified today through the use of DNA techniques. Successful DNA identification, however, depends on having a reference DNA profile. This paper recommends the establishment of a DNA repository to store reference blood samples to facilitate the identification of ADF aircrew remains without causing additional distress to family members.