Evidence for spatial aliasing effects in the Y-like cells of the magnocellular visual pathway

Several lines of evidence are provided indicating that our visual percept can be dominated by spatial aliasing for viewing conditions near those needed to see the spatial frequency doubled illusion. The apparent aliasing effect indicates that the underlying sampling array has a density 15-30% of that of M-cells, in agreement with the known proportion of Y-like M-cells (M(y)-cells). The presence of aliasing indicates, that there is a separate irregular array of M(y)-cells, and that their role is to rapidly convey information on retinal gain control to the brain rather than to act primarily as inputs to image motion computation.     

A novel model of venous thrombosis in the vena cava of rabbits

RATIONALE AND OBJECTIVES: After intraarticular application of gadolinium (Gd)-DTPA the visualization cartilage surface roughness is limited because of diffusion into the cartilage. To improve the sensitivity of magnetic resonance (MR) arthrography to diagnose cartilage surface abnormalities, the authors have tested liposome-entrapped contrast agents. METHODS: Using paramagnetic contrast agents (Gd-DTPA and manganese chloride) free and entrapped in liposomes, respectively, high resolution MR imaging investigations were performed at 7.1 tesla on intact pig temporomandibular and rabbit knee joints. RESULTS: After intraarticular injection of the liposome-entrapped contrast agents an excellent contrast between cartilage surface and joint space was achieved. Diffusion of the contrast agent into the cartilage layer was prevented and the visualization of the cartilage surface was improved markedly. Small mechanically and enzymatically induced cartilage lesions could be assessed reliably. CONCLUSIONS: Intraarticular injection of liposome-entrapped contrast agents can improve the potential of MR arthrography concerning the detection of early osteoarthritic cartilage changes.     

Mycophenolate mofetil in pancreas transplantation

We report the use of a bone graft harvested from the palmar and ulnar aspect of the distal radius and vascularized by the palmar carpal artery for the treatment of scaphoid nonunion in 17 patients, ten of whom had already had unsuccessful surgery. Union was obtained in all cases at an average of 60 days (range, 45-90 days). The average follow-up was 16 months (range, 12-36 months). There were no failures.     

In vivo pressure profiles of thigh-length graduated compression stockings

BACKGROUND: The aim of the study was to assess whether the appropriate pressure profile is generated by thigh-length graduated compression stockings in human subjects. The effect of leg posture on the pressure profile was assessed in three commonly used brands of graduated compression stockings. METHODS: The study involved 17 human volunteers from the Department of Orthopaedic Surgery. Three different brands of stockings commonly recommended for the prevention of deep vein thrombosis were applied to each individual and the interface pressure profile under the stocking was measured. The effect of posture was assessed by comparing the interface pressure profile with the subject supine and in standing and sitting positions. RESULTS: Appropriate median pressure profiles were achieved only with the subject standing or supine. In the sitting position with the knee flexed, a high median interface pressure in excess of 28 mmHg was generated at the popliteal fossa. Overall, inconsistent performance was found in all three brands of stockings; fewer than 30 per cent of the pressure readings fell within 20 per cent of the 'ideal'. Reversed pressure profile was observed in over 70 per cent of subjects. CONCLUSION: Thigh-length graduated compression stockings may be most effective in bedridden patients. Knee-length stockings may be more suitable for the prevention of deep vein thrombosis in ambulant patients.     

Differential reactivities of hypochlorous and hypobromous acids with purified Escherichia coli phospholipid: formation of haloamines and halohydrins

Hypochlorous (HOCl) and hypobromous (HOBr) acids are strong oxidants derived from myeloperoxidase and eosinophil peroxidase, the major antimicrobial enzymes of neutrophils and eosinophils, respectively. These oxidants are highly reactive with a wide range of biomolecules. At physiological pH, both HOCl and HOBr react readily with amines to form haloamines and with the unsaturated bonds of fatty acids to form halohydrins. We have investigated which of these reactions occur with phosphatidylethanolamine (PE), the predominant phospholipid of Escherichia coli. The formation of haloamines was determined by TLC and colorimetrically and the formation of halohydrins was determined by TLC and GC-MS. With HOCl, chloramines were much the preferred product and chlorohydrins were formed in substantial amounts only when HOCl was in excess of the amount required to convert the amine to the dichloramine. With HOBr at all concentrations, bromamines and bromohydrins were formed concurrently, indicating a greater relative reactivity with unsaturated fatty acids than with HOCl. The bromamine derivatives of PE, and other primary amines, were found to be more reactive than the equivalent chloramines, and were able to brominate the unsaturated bonds of fatty acids. Bromohydrins (formed directly or through the action of bromamines) may, therefore, be suitable biomarkers for the production of HOBr in vivo.     

A discrete choice model of drug abuse treatment location

OBJECTIVE: To identify short-term drug abuse treatment location risk factors for ten large, self-insured firms starting January 1, 1989 and ending December 31, 1991. DATA SOURCES/STUDY SETTING: Study population selected from a large database of health insurance claims for all treatment events starting January 1, 1989 and ending December 31, 1991. STUDY DESIGN: A nested binomial logit method is used to estimate firm-specific patterns of treatment location. The differences in treatment location patterns among firms are then decomposed into firm effects (holding explanatory variables constant among firms) and variable effects (holding firm-specific parameters constant). PRINCIPAL FINDINGS: Probability of inpatient drug treatment is directly related to the type of drug diagnosis. The most important factors are diagnoses of drug dependence (versus drug abuse) and/or a cocaine dependence. Firm-specific factors also make a substantive difference. Controlling for patient risk factors, firm-specific probabilities of inpatient treatment vary by as much as 87 percent. Controlling for practices of firms and their insurance carriers, differing patient risk profiles cause probabilities of inpatient treatment to vary by as much as 69 percent among firms. Use of the outpatient setting increased over the three-year period. CONCLUSIONS: There are two plausible explanations for the findings. First, people beginning treatment later in the three-year period had less severe conditions than earlier cases and therefore had less need of inpatient treatment. Second, drug abuse treatment experienced the same trend toward the increased use of outpatient care that characterized treatment for other illnesses in the 1980s and early 1990s.     

Isolation and partial characterization of a polypeptide from Phoneutria nigriventer spider venom that relaxes rabbit corpus cavernosum in vitro

The venom of the Brazilian spider Phoneutria nigriventer was fractionated using a C18 microBondapack reverse-phase high-performance liquid chromatography column. The resulting fractions were assayed in the rabbit perfused corpus cavernosum tissue to identify those fractions responsible for the corpus cavernosum relaxation. Two fractions (A and B) with retention times of 18.1 and 36.7 min, respectively, induced relaxation of corpus cavernosum strips. Fraction A was selected for further biochemical characterization. Repurification of this fraction revealed the presence of a polypeptide (named PNV4) which migrates in sodium dodecyl sulphate-polyacrylamide gel electrophoresis as a single band consistent with a mol. wt close to 16,600. The amino acid composition of PNV4 showed the presence of 147 residues, a high content of Cys and a calculated mol. wt of 17,213 + Trp. The N-terminal amino acid sequence of PNV4 determined for its first 48 residues was AELTSCFPVGHECDGDASNCNCCGDDVYCGCGWGRWNCKCKVADQSYA.