A Novel and Efficient Feature Extraction Method for Iris Recognition

With a growing emphasis on human identification, iris recognition has recently received increasing attention. Iris recognition includes eye imaging, iris segmentation, verification, and so on. In this letter, we propose a novel and efficient iris recognition method which employs a cumulative‐sum‐based grey change analysis. Experimental results demonstrate that the proposed method can be used for human identification in efficient manner.     

Mercury in alligators (Alligator mississippiensis) in the southeastern United States

Mercury methylation may be enhanced in wetlands and humic-rich, blackwater systems that crocodiles and alligators typically inhabit. Given their high trophic level and long life-spans, crocodilians could accumulate significant burdens of Hg. Our objectives were to survey Hg concentrations in alligators from several areas in the southeastern United States to test their utility as sentinels of Hg contamination, to examine relationships among Hg concentrations in various tissues and to look for any differences in tissue Hg concentrations among locations. We measured total Hg concentrations in alligators collected in the Florida Everglades (n = 18), the Okefenokee National Wildlife Refuge, Georgia (n = 9), the Savannah River Site (SRS), South Carolina (n = 49) and various locations in central Florida (n = 21), sampling tissues including blood, brain, liver, kidney, muscle, bone, fat, spleen, claws and dermal scutes. Alligators from the Everglades were mostly juvenile, but Hg concentrations in tissues were high (means: liver 41.0, kidney 36.4, muscle 5.6 mg Hg/kg dry wt.). Concentrations in alligators from other locations in Florida were lower (means: liver 14.6, kidney 12.6, muscle 1.8 mg Hg/kg dry wt.), although they tended to be larger adults. Alligators from the Okefenokee were smallest and had the lowest Hg concentrations (means: liver 4.3, kidney 4.8, muscle 0.8 mg Hg/kg dry wt.). SRS alligators had the greatest size range and intermediate Hg levels (means: liver 14.9, muscle 4.8 mg Hg/kg dry wt.). At some locations, alligator length was correlated with Hg concentrations in some internal organs. However, at three of the four locations, muscle Hg was not related to length. Tissue Hg concentrations were correlated at most locations however, claw or dermal scute Hg explained less than 74% of the variation of Hg in muscle or organs, suggesting readily-obtained tissues, such as scutes or claws, have limited value for non-destructive screening of Hg in alligator populations.     

Choroidal blastomycosis. A report of two cases

Isolated resting platelets are able to limit neutrophil activation and then can control the tissue-damaging potential of activated neutrophils. In the present study, platelet-neutrophil interactions have been evaluated in 10 uremic patients; the blood samples have been collected before the hemodialysis session. Twelve normal subjects served as controls. Platelets and neutrophils have been isolated and recombined in an autologous ex vivo system. Anion superoxide production and chemiluminescence (which is related to hypochlorous acid production) have been evaluated after stimulation with N-formyl-methionyl-leucyl-phenylalanine. Coincubation of platelets from normal subjects with autologous neutrophils led to a dose-dependent inhibition of both superoxide anion generation induced by N-formyl-methionyl-leucyl-phenylalanine and chemiluminescence. Instead, platelets from uremic patients have not affected superoxide anion production by autologous neutrophils. The chemiluminescence was reduced by coincubation with autologous platelets only at the highest platelet-neutrophil ratio (100:1). In conclusion, the modulation exerted by platelets towards neutrophil activation can be impaired in chronic uremia. Therefore, the tissue-damaging potential of circulating neutrophils, due to toxicity by superoxide anion and hypochlorous acid, may be increased.     

Preservation with 8-bromo-cyclic GMP improves pulmonary function after prolonged ischemia

BACKGROUND: Cyclic guanosine monophosphate (cGMP) is a potent second messenger for the nitric oxide pathway in the pulmonary vasculature. Increased cytosolic cGMP levels elicit pulmonary vasodilatation resulting in decreased pulmonary vascular resistance and maximized pulmonary function after ischemia-reperfusion injury. We hypothesized that the addition of a membrane-permeable cGMP analogue (8-bromo-cGMP) to a Euro-Collins (EC) preservation solution would ameliorate pulmonary reperfusion injury better than prostaglandin E1 injection alone after prolonged hypothermic ischemia. METHODS: All lungs from New Zealand White rabbits (weight, 3 to 3.5 kg) were harvested en bloc, flushed with EC solution, and reperfused with whole blood for 30 minutes. Group 1 lungs (immediate control) were immediately reperfused. Group 2 lungs (control) were stored inflated at 4 degrees C for 18 hours before reperfusion. Groups 3 and 4 lungs were flushed with EC solution containing 200 micromol/L 8-bromo-cGMP and stored at 4 degrees C for 18 and 30 hours, respectively. Fresh, nonrecirculated venous blood was used to determine single-pass pulmonary venous-arterial oxygen gradients at 10-minute intervals. Assays for cGMP, cyclic adenosine monophosphate, nitric oxide synthase activity, and myeloperoxidase were performed on all lung tissue samples. Wet to dry weight ratios were determined after 2 weeks of passive desiccation. RESULTS: Oxygenation (venous-arterial oxygen gradient), pulmonary artery pressure, pulmonary vascular resistance, and edema formation were significantly improved in groups 3 and 4 (addition of 8-bromo-cGMP to EC plus 18 or 30 hours of hypothermic ischemia). Hypothermic storage (groups 2, 3, and 4) decreased both nitric oxide synthase activity and myeloperoxidase levels compared with immediate reperfusion (group 1). CONCLUSIONS: These results suggest that the addition of a membrane-permeable cGMP analogue to an EC pulmonary flush solution improves pulmonary function after prolonged storage compared with EC and prostaglandin (E1) preservation alone. The finding of myeloperoxidase reduced levels after hypothermic storage and subsequent reperfusion may suggest a more important role for pulmonary hemodynamic control in mitigating pulmonary reperfusion injury.     

Clearance of technetium 99m N-NOET in normal, ischemic-reperfused, and membrane-disrupted myocardium

BACKGROUND: Technetium 99m-labeled bis(N-ethoxy, N-ethyl dithiocarbamato) nitrido technetium(v) (99mTcN-NOET) is a new neutral cardiac perfusion imaging agent that has been shown to have very high uptake and retention in vitro. The purpose of this study was to determine the clearance kinetics of 99mTcN-NOET in control, ischemic-reperfused, and membrane-disrupted myocardium. METHODS AND RESULTS: After a 100 microCi (3.7 x 10(6) Bq) bolus of 99mTcN-NOET was injected, myocardial clearance was monitored for 1 hour by the use of a sodium iodide detector in 30 isolated, Krebs-Henseleit (KH) perfused rat hearts. Seven hearts were used as controls (group 1). In seven ischemic-reperfused hearts, tracer administration and uptake was followed by 30 minutes of no flow and 1 hour of reflow (group 2). In six additional ischemic-reperfused hearts, tracer administration was followed by deprivation of flow for 1 hour followed by 1 hour of reflow (group 3). Six hearts were perfused with a 0.5% Triton X-100 KH perfusate for 1 hour (group 4). Four hearts were perfused with KH for 10 minutes, followed by cyanide for 10 minutes (group 5). This cycle was repeated three times. Activities remaining in each heart at the end of each experiment were quantitated, and activity at peak uptake was calculated. The 99mTcN-NOET myocardial clearance was near linear in the control (0.6 +/- 0.4) and both ischemic-reperfused groups with virtually no fractional clearance (1.2% +/- 0.6% and 2.1% +/- 0.6%, respectively; p = NS). In the Triton X-100 membrane-disrupted hearts, clearance was substantial (94.2% +/- 4.0%; p < 0.0001 compared with the control and ischemic-reperfused groups). Cyanide treatment produced rapid clearance, which was arrested by a return to the standard KH perfusate. Peak uptake as a percentage of injected dose was 74.9% +/- 1.4% for all groups combined. CONCLUSION: Thus 99mTcN-NOET has extremely high myocardial retention after 1 hour in normal myocardium and is not significantly affected by ongoing myocardial ischemia or reperfusion injury in this model. Clearance is increased markedly in extreme conditions of membrane disruption. These data are consistent with the concept that 99mTc-NOET is localized predominantly in or on cell membranes. 99mTcN-NOET is a promising, new myocardial perfusion imaging agent that exhibits a stable myocardial distribution in the setting of acute developing injury.     

Synaptic organization of the human striatum: a postmortem ultrastructural study

Converging with psycho-social research findings, animal and human laboratory studies indicate that behavioral alternatives are important determinants of drug-taking. To investigate associations between how early adolescents spend their time, i.e. their behavioral repertoire and drug use (use of marijuana, crack/cocaine or inhalants), we analyzed data from an epidemiological sample of 1516 urban middle-school students who had completed private interviews in spring 1993. The interview included a 36-item questionnaire to assess how frequently the youth engaged in different activities; history of drug-taking was assessed separately. Multiple logistic regression was used to estimate associations between drug use and each of seven behavioral domains as well as sex, age and racial-ethnic status. Youths spending a great deal of time working for pay and assuming other adult-like roles were more likely to have initiated drug use (estimated odds ratio, OR = 3.49; p = 0.002). Those who spent much time in religious activities were less likely (OR = 0.2, p <0.001). An exploratory search for interactions disclosed other associations that merit attention in future research. These results corroborate evidence on the potential etiological significance of behavioral repertoire in relation to risk of drug use.     

Automatic detection of conserved RNA structure elements in complete RNA virus genomes

We propose a new method for detecting conserved RNA secondary structures in a family of related RNA sequences. Our method is based on a combination of thermodynamic structure prediction and phylogenetic comparison. In contrast to purely phylogenetic methods, our algorithm can be used for small data sets of approximately 10 sequences, efficiently exploiting the information contained in the sequence variability. The procedure constructs a prediction only for those parts of sequences that are consistent with a single conserved structure. Our implementation produces reasonable consensus structures without user interference. As an example we have analysed the complete HIV-1 and hepatitis C virus (HCV) genomes as well as the small segment of hantavirus. Our method confirms the known structures in HIV-1 and predicts previously unknown conserved RNA secondary structures in HCV.     

Mutations in the nucleotide-binding sites of P-glycoprotein that affect substrate specificity modulate substrate-induced adenosine triphosphatase activity

The amino- and carboxy-terminal nucleotide-binding domains (NBD1 and NBD2) of P-glycoprotein (P-gp) share over 80% sequence identity. Almost all of NBD1 can be exchanged by corresponding NBD2 segments with no significant loss of function, except for a small segment around the Walker B motif. Within this segment, we identified two sets of residues [ERGA --> DKGT (522-525) and T578C] that, when replaced by their NBD2 counterparts, cause dramatic alterations of the substrate specificity of the protein [Beaudet, L., and Gros, P. (1995) J. Biol. Chem. 270, 17159-17170]. We wished to gain insight into the molecular basis of this defect. For this, we overexpressed the wild-type mouse Mdr3 and variants bearing single or double mutations at these positions in the yeast Pichia pastoris. P-gp-specific ATPase activity was measured in yeast plasma membrane preparations after detergent solubilization and reconstitution in Escherichia coli proteoliposomes. P-gp proteoliposomes from P. pastoris showed a strong verapamil- and valinomycin-stimulated ATPase activity, with characteristics (KM, Vmax) similar to those measured in mammalian cells. Mutations did not appear to affect the KM for Mg2+ATP ( approximately 0.4 mM), but maximum velocity (Vmax) of the drug-stimulated ATPase activity was severely affected in a substrate/modulator-specific fashion. Indeed, all mutants showed complete loss of verapamil-induced ATPase, while all retained at least some degree of valinomycin-induced ATPase activity. Photolabeling studies with [125I]iodoarylazidoprazosin, including competition with MDR drugs and modulators, suggested that drug binding was not affected in the mutants. The altered drug resistance profiles of the ERGA --> DKGT(522-525) and T578C mutants in vivo, together with the observed alterations in substrate-induced ATPase activity of these proteins, suggest that the residues involved may form part of a signal pathway between the membrane regions (substrate binding) and the ATP binding sites.