Reducing inequities through participatory research and community empowerment

PURPOSE: To analyze the indocyanine green angiographic findings of drusen in the early stages of age-related macular degeneration. METHODS: Sixty-nine eyes of 53 consecutive patients with drusen but without exudative complications of age-related macular degeneration were studied. Drusen were classified into four groups: hard drusen, drusen derived from clusters of hard drusen (hard cluster-derived drusen and soft cluster-derived drusen), membranous drusen, and regressing drusen. An additional category was constituted by reticular pseudodrusen that could be associated with drusen of either the inner or outer macula. Results of contact lens biomicroscopy and fluorescein angiography were compared with findings on indocyanine green angiography. RESULTS: Hard drusen, either isolated hard drusen or hard cluster-derived drusen, were hyperfluorescent during indocyanine green angiography; in contrast, all sizes of soft drusen derived from clusters of hard drusen were hypofluorescent throughout the angiogram. Membranous drusen, visible on biomicroscopy and fluorescein angiography, were not visible during indocyanine green angiography. Regressing drusen may have showed hyperfluorescence at the early stages of indocyanine green angiography, but associated calcium and pigmentation were hypofluorescent. Reticular pseudodrusen were visible on red-free photographs; on midphase and late-phase indocyanine green angiography using the scanning laser ophthalmoscope only, reticular pseudodrusen were seen as a pattern of hypofluorescent dots. CONCLUSION: The indocyanine green angiographic findings add to and support the clinicopathologic classification of drusen. Indocyanine green angiography may help to distinguish the different types of drusen and may thus be of use in evaluating the risk of progressive age-related macular degeneration in patients with drusen.     

Step-gradient capillary electrochromatography

The analytical benefits of using a step-gradient in capillary electrochromatography (CEC) are demonstrated. The application of step-gradient CEC to the analysis of six diuretics of widely differing lipophilicities was evaluated and shown to result in a marked reduction in the analysis time and an improvement in the peak shape for later-eluting lipophilic components. When the step-gradient approach was performed in an automated mode, the retention time RSD for repeated injections was below 1%.     

Effects of protein-surface interactions on protein ion signals in MALDI mass spectrometry

The influence of polymer surface-protein binding affinity on protein ion signals in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is examined. The surfaces of poly(vinylidene fluoride) and poly(ethylene terephthalate) polymer substrates are modified by pulsed rf plasma deposition of allylamine. By varying the on/off duty cycle of the pulsed rf plasma, the polymer substrate surfaces are coated with thin films having varying densities of surface amine groups. The varying surface amine density is shown to lead to systematic changes in the surface binding affinity for the 125I-radiolabeled peptides angiotensin I and porcine insulin. Unlabeled angiotensin I and porcine insulin are then deposited on the pulsed rf plasma-modified substrates and analyzed by MALDI mass spectrometry. The experimental approach involves applying the peptide to the modified polymer surface in an aqueous phosphate-buffered saline solution and allowing the peptide solution to dry completely under ambient conditions. Subsequently, the MALDI matrix alpha-cyano-4-hydroxycinnamic acid in methanol and 10% trifluoroacetic acid in water are added to the peptide-coated modified polymer surfaces. The results of these studies demonstrate that, for the sample preparation method employed, increases in the surface peptide binding affinity lead to decreases in the peptide MALDI ion signal.     

Monitoring of impurities using high-performance liquid chromatography with diode-array detection: eigenvalue plots of partially overlapping tailing peaks

The chromatogram of ropinirole in the presence of about 5% of a closely eluting impurity, obtained by HPLC with diode-array detection, was analysed by chemometric procedures. Log eigenvalue plots were used to determine the relative composition of regions of the chromatogram. It is shown that since the peaks exhibit tailing, unusual behaviour is found in the plots. This is verified by performing simulations, in which it is demonstrated that peak asymmetry has a pronounced influence on this chemometric approach. In many cases of liquid chromatographic analysis, asymmetric peak shapes are encountered and methods for peak purity assessment should be re-evaluated in the light of these asymmetries.     

The sensory innervation of the hip joint--an anatomical study

Typically obturator nerve blockade is used to relieve hip pain. It sometimes only has a minor effect in resolving symptoms. This clinical observation led us to examine comprehensively the sensory nerve innervation of formalin-fixed hip joint capsules. Following macroscopic preparation, the area of the hip joint capsule was inspected with the aid of an operating microscope. We discovered a separation between the anterior and posterior sensory innervation of the hip joint capsule. The anteromedial innervation was determined by the articular branches of the obturator n. Additionally, the anterior hip joint capsule was innervated by sensory articular branches from the femoral n. In the posterior part we found articular branches from the sciatic n., which in addition to the articular branches from the nerves to the quadratus femoris m., innervate the postero-medial section of the hip joint capsule. Moreover, articular branches of the superior gluteal n. were found, which innervate the posterolateral section of the hip joint capsule. This anatomical study demonstrates that the obturator n. block is insufficient for the treatment of hip pain. Further investigations will determine if these nn. can be reached percutaneously. Effective neural blockade of the hip joint must include the femoral n., the sciatic n. and the superior gluteal n.     

Mesh inguinal herniorrhaphy: a ten-year review

Inguinal herniorrhaphy remains one of the most common surgical operations, with approximately 10 to 20 per cent performed for recurrence. Reviews by specialized hernia centers show mesh repair has a recurrence rate of 0.2 per cent. Detractors of this repair include increased cost, technical difficulty, and risk for infection. The purpose of this study was to compare mesh versus nonmesh inguinal herniorrhaphy at a large teaching institution. From 1985 to 1994, 892 patients underwent primary repair for inguinal hernia at the Veterans Administration Hospital at Memphis, TN. Patients were stratified by repair [Lichtenstein (Mesh), open anterior (Bassini, Marcy, McVay, and Shouldice), laparoscopic (Lap), and preperitoneal (Post)]. Operative time for Mesh repair (111 +/- 2 minutes) was longer than for Bassini or McVay (91 +/- 2 and 98 +/- 2 minutes; P < 0.05), and Lap repairs were longer than all others (192 +/- 16 minutes; P < 0.05). Hospital stay averaged 2.2 +/- 0.1 days for Mesh versus 2.6 +/- 0.1 days for all repairs combined (P = not significant). Mesh patients developed four wound infections (1.0%), none requiring mesh removal, versus nine infections (1.8%) in other groups (P = not significant). One Mesh patient (0.3%) developed recurrence, compared with 16 (3.5%) with open anterior repair (P < 0.01). Inguinal herniorrhaphy using an open mesh repair technique provides superior recurrence rates without increasing risk for infection, length of stay, or technical difficulty.     

Preparative separation of plasmid and bacterial artificial chromosome DNA by density gradient electrophoresis in the presence of linear polymers

A density gradient apparatus was used to examine the separation of different physical forms and sizes of DNA. A gradient of sucrose was used to stabilize thermal convection during electrophoresis in the column (2.2 cm in diameter). Linear polymers were added to the density gradient and screened for their ability to separate the supercoiled, nicked circular, and linear forms of the plasmid pBR 322. The influence of different concentrations and molecular weights of the polymers was examined on the separation. Polyethylene oxide with a molecular weight of 5,000,000 and a concentration of 0.2% w/v achieved the best separation results for the different physical forms of the plasmid. The order of separation of the different physical forms of the plasmid were linear (fastest), supercoiled, and nicked circular (slowest). These conditions were also used to separate a preparation of bacterial artificial chromosome (BAC) DNA. A rapidly moving form, presumably the supercoiled form, was resolved from a large amount of E. coli genomic DNA and from sheared forms of the BAC DNA.