Constraints on long range interactions mediating contour detection

Contour detection may be mediated by lateral interactions between neighboring cortical neurons whose receptive fields have collinear axes of preferred orientation. This hypothesis was tested in psychophysical experiments and computer simulations using a contour detection task in which observers searched for groups of Gabor patches that followed spatially extended contour paths embedded in noise consisting of several hundred Gabor patches with random positions and orientations. The orientation-selective units in the simulated neural network were linked by facilitatory interconnections whose strength depended on the geometry (distance, curvature, change in curvature) of smooth curves connecting the orientation axes of units in a pairwise fashion. Psychophysical detection performance was much higher for contour signal groups that followed closed rather than open-ended paths. However, just two sudden changes in orientation of neighboring Gabor patch elements in closed-path contours reduced detection performance to the same levels obtained with open-ended contours. These psychophysical data agreed with the results of the neural network simulations. Furthermore, the simulations also accounted for previous findings that removal of a single Gabor patch element from a closed-path contour group significantly degraded detection performance. We conclude that closure alone is not sufficient to enhance the visibility of a contour. However, if a closed contour meets certain geometric constraints, then lateral interactions based on these constraints can generate facilitation that reverberates around the closed path, thereby enhancing the contour's visibility.     

Specificity in social support: Perceptions of helpful and unhelpful provider behaviors among irritable bowel syndrome, headache, and cancer patients.

Perceived social support was assessed among 53 patients suffering from non-life-threatening chronic illnesses (i.e., irritable bowel syndrome or recurrent headache). Ss recalled predominantly helpful support interactions and reported the 3 major types of social support as equally helpful. In addition, irritable bowel syndrome patients, who experience embarrassing physical symptoms, reported fewer instances of tangible assistance than chronic headache patients. Comparisons to cancer patients studied by G. A. Dakof and S. E. Taylor (see record 1990-15055-001) revealed differences in perceived social support as a function of diagnosis. These results offer insight into the needs of patients with noncatastrophic illnesses and suggest that the challenges and tasks confronting these individuals are unique from those encountered by patients with catastrophic diseases. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Birth order in homosexual versus heterosexual sex offenders against children, pubescents, and adults

OBJECTIVE: The selection of patients amenable to treatment with a bladder neck sling remains a controversy. In this paper we review our experience with this technique and describe our patient selection criteria. METHODS: Since 1991, 30 patients (24 females and 6 males) aged 4 to 20 years (mean 10) received a bladder neck sling as part of the surgical treatment for their urinary incontinence. The cause of incontinence was neurogenic in 28 of the 30 patients. The 6 male patients were prepuberal. All patients had a preoperative video urodynamic study. The criteria for increasing cervico-urethral resistance included a passive leak point pressure of < 50 cm H2O, stress leak point pressure of < 100 cm H2O, radiological evidence of an open bladder neck and stress incontinence regardless of the other urodynamic and radiologic parameters. The technical aspects of the procedure are described in detail. Augmentation cystoplasty was performed concomitantly in 29 patients. RESULTS: Patient follow-up ranged from 2 to 70 months (mean 37.6). Twenty-eight patients (93%) were continent postoperatively. Two female patients remained incontinent at low leak point pressures. All patients emptied the bladder by intermittent catheterization. Twelve patients perform catheterization through the urethra without difficulty. CONCLUSION: The rectus fascia sling has several advantages over other surgical methods for increasing the cervico-urethral resistance. It is simple, effective, low-cost and has a low complication rate. In our view, the sling is the technique of choice for increasing cervico-urethral resistance in female and prepuberal male patients requiring a cystoplasty concomitantly.     

Water soluble antioxidants in mammalian aqueous humor: interaction with UV B and hydrogen peroxide

HPLC/electrochemical detection was used to identify five major low MW water soluble electrochemically active molecules from the aqueous humor of three species of mammals: New Zealand White rabbits and humans (diurnal) and Sprague-Dawley rats (nocturnal). These molecules are L-cysteine (CYS), L-ascorbic acid (AA), glutathione (GSH), uric acid (UA) and L-tyrosine (TYR); all of these molecules have known antioxidant properties. Nocturnal rat aqueous humor is concentrated in two thiols: GSH (125 microM; n = 24 pooled eyes) and CYS (63 microM), in contradistinction to diurnal species which have high concentrations of AA. No deterioration of any of these antioxidants occurs in a synthetic aqueous humor mixture irradiated with a physiologically relevant spectral UV B dose of 30 mJ/cm2/h (5.5 UV equivalent sunlight hours). The same result occurred with addition of the endogenous aqueous humor UV B photosensitizer L-tryptophan. In a second set of experiments, human synthetic aqueous humor was subjected to hydrogen peroxide induced oxidant stress. The decay of antioxidants was CYS > GSH > AA > UA > TYR. The second highest concentrated antioxidant in human aqueous humor is TYR. Yet TYR failed to protect AA against H2O2-induced free radical damage in a synthetic aqueous humor model system (P = 0.10; ANOVA). The existence of multiple electrochemically active constituents and their thermodynamic interactions must be recognized when choosing animal models to evaluate human aqueous humor antioxidant defense.     

Diagnosing the combination of renal dysgenesis, Gartner's duct cyst and ipsilateral müllerian duct obstruction

PURPOSE: We describe the differential points in the diagnosis of the combination of renal dysgenesis, Gartner's duct cyst and ipsilateral müllerian duct obstruction. Various imaging studies and urological procedures were performed. We report our experience in detecting these anomalies in 10 girls and review the literature. MATERIALS AND METHODS: Ten girls, 7 to 13 years old, with this combination of anomalies were identified in the last 10 years. Imaging studies as well as urological procedures were selectively performed, especially at puberty following menarche. Patients received long-term followup with ultrasound. RESULTS: Cystic dilation of Gartner's duct protruded into the bladder and presented as a ureterocele in 5 patients and posterior to the bladder in 5. Surgical removal of a partial portion of a Gartner's duct cyst was performed in 5 patients for alleviation of urinary symptoms. Unilateral müllerian duct obstruction was demonstrated in all 10 patients. Excision of the vaginal septum was performed in 6 patients for relief of genital obstruction. CONCLUSIONS: When cystic dilatation of the pelvis, especially a ureterocele-like cyst without ureteral dilatation, is found in girls with ipsilateral renal dysgenesis, the possibility of a Gartner's duct cyst should be considered. For early detection and treatment of unilateral obstruction of duplicated müllerian ducts pelvic sonography should be performed at puberty, especially just after menarche, in girls with renal dysgenesis and ipsilateral Gartner's duct cyst.     

Identification of two major F2 isoprostanes, 8,12-iso- and 5-epi-8, 12-iso-isoprostane F2alpha-VI, in human urine

Isoprostanes (iPs) are nonenzymatic, free radical-derived compounds isomeric with enzymatically formed eicosanoids such as prostaglandins, leukotrienes, and thromboxanes. One group formed by the auto-oxidation of arachidonic acid, the F2-iPs, consists of four classes of isomers of prostaglandin F2alpha (PGF2alpha). They are relatively abundant in human urine. This fact, along with their chemical stability and excellent characteristics for quantitation by gas chromatography/mass spectrometry, has made them attractive indices of oxidative stress in humans. We developed a specific assay using gas chromatography/mass spectrometry for the first identified F2-iP, iPF2alpha-III (previously called 8-iso-PGF2alpha or 8-epi-PGF2alpha), which demonstrated the utility of monitoring a specific isomer. Recently, we described an assay for another isomer, iPF2alpha-VI, which is present in urine in greater concentration than iPF2alpha-III and which is particularly amenable to quantitation. We now describe the identification in human urine of two more isomers, 8,12-iso-iPF2alpha-VI and 5-epi-8, 12-iso-iPF2alpha-VI, using high performance liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry. These compounds are each present in approximately 5-fold greater concentrations than iPF2alpha-VI (approximately 20-fold greater than iPF2alpha-III). They share the unique chemical characteristics of class VI compounds, which make them attractive targets for quantitation by gas chromatography/mass spectrometry and immunoassay development.     

Modulatory effects of L-DOPA on D2 dopamine receptors in rat striatum, measured using in vivo microdialysis and PET

Putative modulatory effects of L-3,4-dihydroxyphenylalanine (L-DOPA) on D2 dopamine receptor function in the striatum of anaesthetised rats were investigated using both in vivo microdialysis and positron emission tomography (PET) with carbon-11 labelled raclopride as a selective D2 receptor ligand. A single dose of L-DOPA (20 or 100mg/kg i.p.) resulted in an increase in [11C]raclopride binding potential which was also observed in the presence of the central aromatic decarboxylase inhibitor NSD 1015, confirming that the effect was independent of dopamine. This L-DOPA evoked D2 receptor sensitisation was abolished by a prior, long-term administration of L-DOPA in drinking water (5 weeks, 170mg/kg/day). In the course of acute L-DOPA treatment (20mg/kg), extracellular GABA levels were reduced by approximately 20% in the globus pallidus. It is likely that L-DOPA sensitising effect on striatal D2 receptors, as confirmed by PET, may implicate striato-pallidal neurones, hence a reduced GABA-ergic output in the projection area. Since the L-DOPA evoked striatal D2 receptor supersensitivity habituates during long-term treatment, the effects reported here may contribute to the fluctuations observed during chronic L-DOPA therapy in Parkinson's disease.     

Intensification of the bio‐processing of cotton textiles by combined enzyme/ultrasound treatment

Utilization of highly specific enzymes for various textile‐processing applications is becoming increasingly popular because of their ability to replace harsh organic/inorganic chemicals currently used by the textile industry. Thus, a significant decrease in the amount and toxicity of textile wastewater effluents is achievable. It was established that ultrasound does not inactivate the complex structures of enzyme molecules and as a consequence there was significant improvement in the performance of both cellulase and pectinase enzymes. The experimental data indicate that the maximum benefit provided by sonication occurs at relatively low enzyme concentrations. Ultrasonic energy significantly intensified enzymatic activity on various types of cotton fabrics, but it did not contribute to a decrease in tensile strength. The combined enzyme/sonication treatment of cellulosic textiles offers significant advantages such as less consumption of expensive enzymes, shorter processing time, less fiber damage and better uniformity of treatment. Published in 2002 for SCI by John Wiley & Sons, Ltd     

The design and performance of an experimental external fixation device with load transducers

It is becoming increasingly common that fracture healing is modelled in the laboratory with an osteotomy in the diaphysis of the ovine tibia. External fixation is often used to hold the bones in these models, presenting the problem that the loads on such devices are poorly understood. To help investigate this, a unilateral device has been developed which is capable of measuring the two components of load considered to be the most important, that of axial compression and bending in the plane of the fixator. The device was found to be a rigid system and easy to apply, with the in-vivo measurements being straightforward. The estimated limits of error of the compression transducer are +37.9 N and -21.4 N and those of the bending transducer are +3.6 Nm and -4.2 Nm. Preliminary measurements showed the maximum load during normal walking to 345 N compression and 28 Nm in-plane bending.