Optic neuropathy endemic in secondary school children in Dar es Salaam, Tanzania.

AIM: To investigate the prevalence and causes of optic neuropathy, reported as epidemic in 1997, among secondary school students in Dar es Salaam, Tanzania. PATIENTS AND METHODS: First year students (n = 10,892) from 63 secondary schools located within 30 km from the base hospital were interviewed and had a visual acuity (VA) screening test. Students failing the 6/12-line in either eye were defined as having "poor eyesight" and referred to the base hospital where an optometrist re-tested VA and refracted them. An ophthalmologist examined students with VA of 6/12 or worse in either eye and visual impairment was defined as VA of worse than 6/12 with best correction. Associations between optic neuropathy, socioeconomic status and educational results were investigated. RESULTS: Students' ages ranged from 12 to 22 (mean 15.2) years; 50.6% were male. The prevalence of optic neuropathy was 0.3 (SD 0.051)%. The condition affected older students and was associated with the family having fewer economic possessions (car, computer, television). Optic neuropathy accounted for 19/33 (58%) of bilateral visual impairment cases. No effect of the disease on educational performance was identified. CONCLUSION: Optic neuropathy remains a significant problem in this population and can now be termed endemic rather than epidemic. Further research into its causes is required.

Combined cataract and trabeculectomy surgery for advanced glaucoma in East Africa; visual and intra-ocular pressure outcomes.

AIM: To investigate visual and intra-ocular pressure (IOP) outcomes of combined cataract and glaucoma surgery at a high-volume centre in East Africa carried out over a 1-year period (2006). METHODS: A retrospective analysis of patient records. RESULTS: A total of 163 patients were identified. Mean age was 67 years (SD 11, range 21-86 years) and 113 (69%) were men. Presenting visual acuity in the operated eye was 6/60 or worse in 135/163 (93%) and was <3/60 in 76 of 163 (47%) patients. Mean presenting IOP was 28 mm Hg (SD 9, range 12-60). Pre-operative cup disc ratios were 0.8 or worse in 131 of 163 (85%) patients. Phacotrabeculectomy (PT) was carried out in 130 (80%) cases, small incision cataract surgery trabeculectomy (SICST) in 10 (6.1%) cases, and extra-capsular cataract extraction trabeculectomy (ECCET) in 23 (14.1%) cases. In all, 107 (66%) attended for follow-up (mean interval 104 days, range: 6-390 years, SD 88) and at follow-up 75 (70%) patients had improved visual acuity pre-operatively. Pre-operative cup disc ratio of 0.9 or greater predicted failure to improve VA at follow-up (OR 4.0 95% confidence interval (CI) 1.30-12.1). Fifty-nine (62% (95%CI 52-71%)) patients had follow-up IOPs of 6-15 mm Hg and 82 (85% (95% CI 78-92%)) had follow-up IOPs of 6-20 mm Hg. CONCLUSION: Combined surgery produces visual benefit for most patients with similar pressure control to pure trabeculectomy and is therefore a useful option in practises where follow-up may be doubtful.

Therapeutic effects of cysteine protease inhibition in allergic lung inflammation: inhibition of allergen-specific T lymphocyte migration.

OBJECTIVE AND DESIGN: We have evaluated the effects of the broad-spectrum cysteine protease inhibitor E64 on allergic lung inflammation in the mouse ovalbumin model of human asthma. We have also characterised membrane-associated cathepsin enzyme activity on a range of cell types. MATERIALS: Balb/C mice, E64 and CA074, various cell lines. TREATMENT: E64 was administered by subcutaneous minipump into ovalbumin-sensitised mice prior to intranasal ovalbumin challenge. The effect of E64 on ovalbumin-induced inflammation in vivo and ovalbumin-specific T cell proliferation in vitro and ex vivo was examined. Membrane-associated cathepsin activity on various cell types was measured. RESULTS: E64 treatment (0.36-0.48 mg/day) led to a significant reduction in eosinophil numbers and lung weights in the mouse model. Histological examination of lungs confirmed the anti-inflammatory effect. E64 greatly reduced ovalbumin-specific T cell numbers in the lymph nodes draining the lung following intranasal challenge whilst an accumulation of these T cells was found in the 'priming' lymph nodes. An analysis of various cells involved in lymphocyte priming and migration revealed that monocytes, dendritic cells and endothelial cells express high levels of membrane-associated cathepsin B activity. CONCLUSIONS: Since E64 is not cell permeable and does not inhibit antigen-induced T cell proliferation in vitro or in vivo, the data indicate that membrane-associated cysteine proteases, possibly cathepsin B, may regulate T lymphocyte migration in vivo.

1,6-interactions between dimethylamino and aldehyde groups in two biphenyl derivatives.

The title compounds, 2-(dimethylamino)biphenyl-2'-carboxaldehyde, C15H15NO, and 2-(dimethylamino)biphenyl-2',6'-dicarboxaldehyde, C16H15NO2, show similar 1,6-interactions [N...C=O 2.929 (3) to 3.029 (3) A] between the dimethylamino and aldehyde groups located in the ortho positions of the two rings, which lie at 58.1 (1)-62.4 (1) degrees to each other.

Statistical analysis of spatial pattern: a comparison of grid and hierarchical sampling approaches.

Previous studies have combined random-site hierarchical sampling designs with analysis of variance techniques, and grid sampling with spatial autocorrelation analysis. We illustrate that analysis techniques and sampling designs are interchangeable using densities of an infaunal bivalve from a study in Poverty Bay, New Zealand. Hierarchical designs allow the estimation of variances associated with each level, but high-level factors are imprecisely estimated, and they are inefficient for describing spatial pattern. Grid designs are efficient for describing spatial pattern, and are amenable to conventional analysis. Our example deals with a continuous spatial habitat, but our conclusions also apply in disjunct or patchy habitats. The influence of errors in positioning is also assessed. The advantages of systematic sampling are reviewed, and more efficient hierarchical approaches are identified. The distinction between biological and statistical significance in all analyses is emphasised.

Fast measurements of the motion and velocity spectrum of blood using MR tagging.

A new method is presented for tracking the motion of blood and determining its velocity spectrum from magnetic resonance data collected within a single heartbeat. The method begins by tagging a column of blood in a vessel by combining a 1D SPAMM excitation with a 2D cylindrical excitation. A series of 1D projections of the tagging pattern is acquired from a train of gradient echoes. The influence of specific excitation profiles and velocity profiles on the motion of the tags is explored for steady flow. It is shown mathematically, and confirmed with phantom experiments, that the velocity of a tag equals the mean velocity of the excited fluid when the velocity spectrum is symmetric about its mean velocity. The velocity spectrum is derived by analyzing the interference between tags moving at different velocities. This appears to be the first use of magnitude tagging to obtain velocity spectra. Representative measurements in a human aorta are presented to assess feasibility in vivo. Magn Reson Med 45:461-469, 2001.

Partial discrete Fourier transform (PDFT) multiband encoding.

For conventional multiband encoding techniques such as Hadamard encoding, scan time scales linearly with the number of slices encoded simultaneously. In this work, a new multiband encoding technique called partial discrete Fourier transform (PDFT) encoding is introduced, which overcomes this restriction. This technique incorporates the principle of partial Fourier imaging, allowing the tradeoff of SNR and imaging time without changing the number of slices. The theory behind PDFT encoding and its inherent sensitivity to phase errors are outlined. The theory was validated through simulations, showing that phase errors result in degraded slice localization. The feasibility of PDFT encoding of 12 slices was tested with experimental excitation profile measurements and heart images of a human subject using commercial MRI equipment. Imaging time was reduced to 66% with SNR reduced to 82%. Magn Reson Med 45:118-127, 2001.

Open reduction and cementation for femoral head fracture secondary to avascular necrosis: preliminary report.

Current treatment for femoral head avascular necrosis has shown good results in early stages of disease, but are not as impressive after progression to collapse. We treated 19 patients (20 hips) with Stage III avascular necrosis (AVN) by open reduction augmented by methylmethacrylate cementation. Follow up ranges from 6 months to 2 years (average = 8.7 months). We followed patient progress with pre- and post-operative Harris Hip Scores, Womac Osteoarthritis Index and a Health Status Questionnaire (SF36). All patients realized immediate post-operative pain relief and improvement in function. Harris Hip, Womac Osteoarthritis Index and SF36 physical health scores improved significantly from 54.0 to 79.5 (p < 0.05), 54.3 to 29.8 (p < 0.05) and 28.4 to 42.4 (p < 0.05), respectively. Three patients had a conversion to total hip arthroplasty. Cementation is technically simple, burns no bridges and enables patients a rapid recovery. The long term results, in regards to progression of disease and secondary arthritis, are unknown.

Photo-cross-linkable oligonucleotide probes for in situ hybridization assays.

In situ hybridization techniques have been an important research tool since first introduced 30 years ago, and more recently clinical applications have been expanding greatly. Still, further improvements in the assay sensitivity and protocols that are amenable to routine clinical use are desired. We use a novel photo-cross-linking technology to irreversibly bind short oligonucleotide probes to the target sequence following a hybridization period. The cross-linking agent is incorporated into the backbone of the probe and is activated to react with pyrimidines in the opposite strand by near-UV (300-370 nm) irradiation. By locking the probe to the target, very stringent wash conditions can be used that would otherwise completely remove probes that are hybridized but not cross-linked to the target. Consequently, the probe-specific signal is maximized, while the background signal is minimized to the greatest extent possible with the stringency of the wash. The use of short, photo-cross-linkable probes presents a new strategy for maximizing the sensitivity of probe hybridization or signal amplification-based in situ techniques.

Behavioral sensitization following repeated intravenous nicotine administration: gender differences and gonadal hormones.

Repeated intermittent administration of stimulants is well known to produce behavioral sensitization in male animals. The present studies explored whether 1) behavioral sensitization occurred with the i.v. route of administration, 2) sensitization was greater in females than in males, 3) sensitization was modulated by gonadectomy, 4) intact adult female rats maintained normal estrous cytology patterns in response to repeated nicotine administration, and 5) the pharmacokinetics of i.v. nicotine dosing. Adult male, female, castrated, and ovariectomized Sprague-Dawley rats (n = 48) were surgically implanted with an intravenous access port. Animals received 50 microg/kg i.v. nicotine once/day for 14 days. Immediately after the initial nicotine injection and the final day 14 nicotine injection, animals were placed in IR photocell activity chambers for 60 min. Observational time sampling of behavior was also simultaneously performed by an observer blind to treatment condition. An increase in behavioral activity of greater than 120% occurred across the 14-day time course of i.v. nicotine injections. The magnitude of the increase, however, varied as a function of component of activity, gender, and gonadectomy. The behavioral observation data further suggested that the females demonstrated an increased sensitivity to repeated nicotine, as evidenced in a more rapid response, for example, grooming. These behavioral observations were associated with peak arterial levels of nicotine (approximately 25 ng/ml) no greater than the average venous levels of nicotine commonly maintained by cigarette smokers. Repeated i.v. nicotine, at a dose of 50 microg/kg, did not interfere with intact female vaginal cytology or body weight; the failure to detect such alterations were not due to inadequate statistical power. Moreover, no nicotine-treated animals displayed persistent vaginal estrous or were acyclic. Collectively, these data suggest that the i.v. nicotine model may be particularly useful in exploring the gender-dependent effects of nicotine.

Repetitive high G exposure is associated with increased occurrence of cardiac valvular regurgitation.

BACKGROUND: Exposure to repeated high +Gz loads and the methods to prevent loss of consciousness cause unique stresses on the cardiovascular system. The purpose of this study was to determine if the +Gz environment is associated with an increased occurrence of valvular regurgitation in pilots of high performance aircraft. METHODS: There were 247 subjects who were divided into pilot (n = 46) and non-pilot (n = 201) groups. Pilots were defined as those individuals who had flown at least 1000 h in high performance aircraft. The echocardiographic data of these subjects were examined retrospectively. RESULTS: We found a statistically significant association between pulmonic insufficiency and exposure to high +Gz stress in pilots vs. non-pilots (chi2 = 13.09, p = 0.0002). In addition, there was a greater incidence of tricuspid regurgitation (chi2 = 4.97, p = 0.025) and concurrent pulmonic insufficiency and tricuspid regurgitation (chi2 = 14.1, p = 0.0002) in the pilot group. CONCLUSIONS: There is a direct relationship between repetitive exposure to a +Gz environment and pulmonic insufficiency, tricuspid regurgitation, or concurrent pulmonic insufficiency and tricuspid regurgitation. This may be secondary to the transient increase in right ventricular pressure due to acceleration forces or straining maneuvers utilized to prevent or postpone +Gz induced loss of consciousness (G-LOC).

Estrous cyclicity and behavioral sensitization in female rats following repeated intravenous cocaine administration.

Repeated intermittent administration of cocaine is well known to produce behavioral sensitization in male animals. The present studies explored whether intact adult female rats maintained normal estrous patterns in response to repeated IV cocaine administration and whether behavioral sensitization occurred with this route of administration. Adult female Sprague-Dawley rats (N = 48) were surgically implanted with an intravenous access port. Animals received 3.0 mg/kg IV cocaine once/day for 14 days. Daily vaginal lavages indicated that female rats continued to cycle normally throughout the experiment. Estimates of statistical power for detecting alterations in estrous cycle length ranged from 0.61-0.95 for small (0.1) to large (0.4) effect sizes. Moreover, no cocaine-treated animals displayed persistent vaginal estrus or were acyclic and cocaine treatment did not decrease body weight. Immediately after the cocaine injection, animals were placed in IR photocell activity chambers for 60 min. Female rats displayed a significant 75% increase in locomotor activity across the 14-day time course of IV cocaine injections. These data indicate that 3.0 mg/kg of IV cocaine does not interfere with normal estrous cyclicity, and that behavioral sensitization occurs in female rats following repeated daily IV cocaine dosing. Collectively, these data suggest that the IV cocaine-dosing model may be particularly useful in exploring the gender-dependent effects of cocaine using intact female rats.

Aorta wall motion monitoring by 1-d MRI of perpendicular diameters.

A method for monitoring the cross-sectional size of blood vessels rapidly is introduced. The method creates a one-dimensional (1-D) profile of a strip along the diameter of a vessel using magnetic resonance imaging (MRI). The strips can be much wider than pixels in a typical two-dimensional (2-D) image to increase the signal-to-noise ratio. A second strip perpendicular to the first is also imaged sequentially to allow the detection, estimation, and correction of errors in diameter measurements resulting from the strip inadvertently covering a chord, rather than a diameter. Diameter measurements derived from 1-D profiles agree with measurements derived from 2-D images. This method is nearly an order of magnitude faster than 2-D MRI and has the potential for real-time implementation. J. Magn. Reson. Imaging 1999;10:833-840.

Method for improved multiband excitation profiles using the Shinnar-Le Roux transform.

A method to design multiband RF pulses for magnetic resonance imaging is described. The method is based on the Shinnar-Le Roux transform and involves a phase correction that provides control over the phase of the excited bands. The theory behind the method and this phase correction is outlined. The method is demonstrated with the design of RF pulses for Hadamard encoding and Haar wavelet encoding. Experimentally measured excitation profiles and images for RF pulses designed with the new method are compared to those designed by the conventional method. The conventional method is shown to result in distortion of the excitation profile when the bands are closely spaced. A 78% reduction in this distortion is attributed to the new method. This translates into a 52% reduction of out-of-slice signal in Haar wavelet encoding. Magn Reson Med 42:577-584, 1999.

Motion measurements from individual MR signals using volume localization.

A novel method is presented for measuring motion using individual magnetic resonance (MR) signals. This method uses a volume-localized excitation with reduced spatial encoding to measure displacement with a temporal resolution of several milliseconds. The trajectory of the excited volume is derived from the time-dependent frequency of the MR signal, which changes as the volume moves through a magnetic-field gradient. Phantom and in vivo experiments confirm that this method can monitor the trajectory of plug-like structures accurately, with T2* decay limiting the measurement period. The displacement of flowing blood in a human aorta has been measured for 65 msec from one MR signal, with a theoretical accuracy of 0.25 mm and an effective time resolution of 2 msec. The high temporal resolution of this method is useful for capturing rapid motions. An interesting property of this method is that it measures motion from the reference frame of the moving anatomy.

Community health nurses' knowledge of Lyme disease: implications for surveillance and community education.

A statewide assessment was conducted to determine the general knowledge and professional practices about Lyme disease (LD) of local health department nurses. The study sample included 226 nurses practicing in 80 health departments in Indiana. Data were collected using a self-administered questionnaire and analyzed using group independent t tests. Findings showed that nurses were most knowledgeable about personal protection against LD and least knowledgeable about symptoms, case definition, and reporting criteria. Nonbaccalaureate degreed nurses scored significantly higher on questions about LD than the baccalaureate or master's prepared nurses. Results point to the need for better dissemination of LD information among public health nurses, expanded LD education for the public, and further development of LD surveillance activities.

Nucleic acid-based cross-linking assay for detection and quantification of hepatitis B virus DNA.

A nucleic acid photo-cross-linking technology was used to develop a direct assay for the quantification of hepatitis B virus (HBV) DNA levels in serum. Cross-linker-modified DNA probes complementary to the viral genomes of the major HBV subtypes were synthesized and used in an assay that could be completed in less than 6 h. The quantification range of the assay, as determined by testing serial dilutions of Eurohep HBV reference standards and cloned HBV DNA, was 5 x 10(5) to 3 x 10(9) molecules of HBV DNA/ml of serum. Within-run and between-run coefficients of variation (CVs) for the assay were 4. 3 and 4.0%, respectively. The assay was used to determine HBV DNA levels in 302 serum samples, and the results were compared to those obtained after testing the same samples with the Chiron branched-DNA (bDNA) assay for HBV DNA. Of the samples tested, 218 were positive for HBV DNA by both assays and 72 gave results below the cutoff for both assays. Of the remaining 12 samples, 10 were positive for HBV DNA by the cross-linking assay only; the 2 other samples were positive by the bDNA assay only. Twenty-eight samples had to be retested by the bDNA assay (CV, >20% between the results obtained from the testing of each sample in duplicate), whereas only three samples required retesting by the cross-linking assay. The correlation between the HBV DNA levels, as measured by the two tests, was very high (r = 0.902; P = 0.01). We conclude that the cross-linking assay is a sensitive and reproducible method for the detection and quantification of HBV DNA levels in serum.