Blindness prevalence and cataract surgical coverage in Lumbini Zone and Chetwan District of Nepal.

AIM: To determine the prevalence of blindness, visual impairment and the cataract surgical coverage for people aged 50 years and older in the Lumbini Zone and the Chitwan District (Narayani Zone) of Nepal. METHODS: A population-based cross-sectional study in 2006 selected subjects aged 50 years and older through a random multistage cluster sampling and door-to-door enumeration. Ophthalmic examination included visual-acuity assessment and refraction, and anterior and posterior segment examination of the eyes carried out by a trained ophthalmologist and two ophthalmic assistants at centralised locations. RESULTS: The survey examined 5138 of 5196 persons enumerated (response rate of 86.8%). The mean age of the subjects was 61 (SD 9.2) years, and 2701 (52.6%) subjects were women. The age-sex-adjusted prevalence of blindness (best presenting vision <6/60) and visual impairment (better-eye presenting visual acuity of <6/18 to > or = 6/60) were 4.6% (95% CI 3.4 to 5.8) and 18.9% (95% CI 16.4 to 21.4), respectively. Blindness was significantly lower in the hill (3.3%) compared with the plain (5.8%) regions (OR 0.6; 95% CI 0.4 to 0.9). The primary causes for blind eyes were cataract (n = 228, 48.1%), refractive error (n = 149, 31.4%), retinal disorders (n = 19, 4.0%) and corneal opacity (n = 18, 3.8%). The overall cataract surgical coverage was 66.6%. Cataract surgical coverage was not significantly associated with age, sex, literacy or District. CONCLUSION: Although the prevalence of blindness and visual impairment is lower than 10 years ago, particularly among women, correctable blindness due to cataract and refractive error (79.5% of blind people) remains a significant population health problem in Lumbini Zone and Chitwan District.

Development of a population-based microsimulation model of osteoarthritis in Canada.

OBJECTIVES: The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN: We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS: Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS: We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature.

Antagonistic roles of neurofilament subunits NF-H and NF-M against NF-L in shaping dendritic arborization in spinal motor neurons.

Dendrites play important roles in neuronal function. However, the cellular mechanism for the growth and maintenance of dendritic arborization is unclear. Neurofilaments (NFs), a major component of the neuronal cytoskeleton, are composed of three polypeptide subunits, NF-H, NF-M, and NF-L, and are abundant in large dendritic trees. By overexpressing each of the three NF subunits in transgenic mice, we altered subunit composition and found that increasing NF-H and/or NF-M inhibited dendritic arborization, whereas increasing NF-L alleviated this inhibition. Examination of cytoskeletal organization revealed that increasing NF-H and/or NF-M caused NF aggregation and dissociation of the NF network from the microtubule (MT) network. Increasing NF-H or NF-H together with NF-M further reduced NFs from dendrites. However, these changes were reversed by elevating the level of NF-L with either NF-H or NF-M. Thus, NF-L antagonizes NF-H and NF-M in organizing the NF network and maintaining a lower ratio of NF-H and NF-M to NF-L is critical for the growth of complex dendritic trees in motor neurons.

Electrophysiological responses of receptor neurons in mosquito maxillary palp sensilla to carbon dioxide.

Sensilla basiconica on the maxillary palps of female Aedes aegypti contain a receptor neuron which produces a phasic-tonic pattern of action potential response to low concentrations (150-300 ppm) of carbon dioxide (CO2), a stimulus known to be involved with host seeking behavior. These receptor neurons respond reliably to small increments in CO2 concentration (e.g., 50 ppm). We were particularly interested in evaluating the possibility that the sensitivity to step increases in CO2 concentration could be modulated by alterations in the background levels of CO2, over a range which might be encountered during host-seeking behavior. We report here that the response (impulses/s) to a single pulse of a given concentration of CO2 appears to be independent of the background level of CO2, unless that level is equal to or greater than the concentration of the stimulus pulse. Females of other mosquito species, including: Anopheles stephensi, Culex quinquefasciatus, Culiseta melanura, and Aedes taeniorhynchus, also possess sensilla with receptor neurons that respond with comparable sensitivity to CO2 stimulation. However, there is much interspecific variation in both the external morphology of the maxillary palp and the distribution of sensilla along the palp. Male Ae. aegypti have morphologically similar sensilla which also contain a receptor neuron that responds to CO2.

Electron micrographic studies of transport of oligodeoxynucleotides across eukaryotic cell membranes.

Unmodified oligodeoxynucleotides (ODNs) were synthesized and tested for their ability to cross external eukaryotic cell membranes and to enter the cytosol and nucleus in tissue cultures. The ODNs were labeled with high-specific-activity [3H]thymidine (> or = 100 Ci/mmol), or [ alpha-32P]ATP or [ gamma-32P]ATP (300-1000 Ci/mmol; 1 Ci = 37 GBq), and the label was either in the central portion of the molecule or at the 3' or 5' end. The cells employed were for the most part 3T6 murine fibroblasts, grown in monolayers, either semiconfluent or confluent, but some experiments were carried out with chicken embryo fibroblasts or human HeLa cells. Parallel wells in the same experiment were prepared for electron microscopy or for cell fractionation and radioactivity assays. Electron microscopic autoradiography indicated that ODNs cross the external cell membrane, traverse the cytosol, and begin to enter the cell nucleus within a few seconds to 5 min at 37 degrees C in Dulbecco's medium without added serum. After 30-60 min of incubation with ODNs, abundant silver grains were observed at or just inside the nuclear membrane or well distributed across the nucleus, particularly in association with euchromatin. There was a paucity of silver grains associated with nucleoli. Cell entry of oligomer was related to cell cycling events and was energy dependent. Degradation of oligomer to monomers, with reincorporation into DNA, does not appear to explain these results. No sequestration of labeled oligomer in cytoplasmic vesicles en route from the exterior of the cell to the nucleus was observed. The observations are more suggestive of internalization of oligonucleotide by a mechanism as yet unclear or, alternatively, by a caveolar, potocytotic mechanism rather than by endocytosis.

Dynamin, a GTPase involved in the initial stages of endocytosis.

Dynamin is a high molecular mass (100 kDa) GTPase which binds to and co-purifies with microtubules. Molecular cloning of rat brain dynamin has revealed the three well-established consensus sequence elements for GTP binding within the N-terminal third of the protein, as well as sequence similarity within this region to the interferon-inducible antiviral Mx proteins, the product of the yeast membrane sorting gene VPS1, and the product of the yeast mitochondrial replication gene MGM1. More extensive sequence similarity between rat dynamin and the product of the Drosophila gene shibire, which is involved in endocytosis, has also been found. In in vitro assays microtubules strongly stimulate the dynamin GTPase. This effect can be reversed by removal of the dynamin C-terminus using papain, which abolishes microtubule binding. Overexpression of mutant forms of dynamin in vivo using Cos-7 cells inhibits transferrin uptake and alters the distribution of clathrin and of alpha-adaptin, but not gamma-adaptin. Deletion of the C-terminus of mutant forms of dynamin abolishes these effects. Together these results suggest a critical role for dynamin in the early stages of endocytosis. It is uncertain whether microtubules interact with dynamin in vivo or whether the in vitro effects of microtubules mimic the effects of other regulatory elements in vivo.

Structure-function relationships of interleukin-3. An analysis based on the function and binding characteristics of a series of interspecies chimera of gibbon and murine interleukin-3.

IL-3 is a glycoprotein cytokine involved in the hematopoietic response to infectious, immunologic, and inflammatory stimuli. In addition, clinical administration of recombinant IL-3 augments recovery in states of natural and treatment-related marrow failure. IL-3 acts by binding to high affinity cell surface receptors present on hematopoietic cells. To determine the site(s) at which IL-3 binds to it receptor, we analyzed a series of interspecies chimera of the growth factor for species-specific receptor binding and biological activity. The results suggest that IL-3 binds to its receptor and triggers a proliferative stimulus through two noncontiguous helical domains located near the amino terminus and the carboxy terminus of the molecule. To corroborate these findings, we have also mapped the binding epitopes of 10 mAb of human or murine IL-3, and have defined four distinct epitopes. Two of these epitopes comprise the amino-terminal receptor binding domain. A third epitope corresponds to the carboxy-terminal receptor interactive domain, and the fourth epitope, apparently not involved in the interaction of IL-3 and its receptor, lies between these sites. And on the basis of sandwich immunoassays using pairs of these mAbs, the two receptor interactive regions appear to reside in close juxtaposition in the tertiary structure of the molecule. These results provide a correlation of the structure-function relationships of IL-3 that should prove useful in evaluating the details of IL-3-IL-3 receptor interaction and in the rational design of clinically useful derivatives of this growth factor.

Macrophage colony-stimulating factor enhances monocyte and macrophage antibody-dependent cell-mediated cytotoxicity.

In vitro culture of either human peripheral blood monocytes or murine peritoneal macrophages for 72 hr in the presence of macrophage colony-stimulating factor (M-CSF) dramatically increased their subsequent ability to mediate antibody-dependent cellular cytotoxicity (ADCC). The M-CSF-treated cells were more effective in ADCC at lower effector to target cell ratios and in the presence of lower concentrations of tumor-specific monoclonal antibody than the untreated control cells. Two other hematopoietic cytokines, granulocyte-macrophage colony-stimulating factor and interleukin-3, reported to enhance other macrophage effector functions were ineffective in promoting the development of ADCC by cultured human monocytes. All three hematopoietic growth factors were capable of enhancing the ability of the cultured monocytes to secrete TNF alpha; however, TNF alpha is unlikely to be an important cytotoxic factor in ADCC because neutralizing antibodies against TNF alpha had no affect on ADCC in vitro. Further, much higher concentrations of M-CSF were required to augment monocyte TNF alpha release (20-100 ng/ml) than ADCC capacity (1-10 ng/ml). These results suggest that M-CSF administration might prove effective in increasing the tumoricidal activities of tumor-specific monoclonal antibodies by enhancing the capacity of monocytes and macrophages to mediate ADCC.

Organotypic culture of fetal lung type II alveolar epithelial cells: applications to pulmonary toxicology.

Techniques for isolation and culture of fetal Type II alveolar epithelial cells, as well as the morphologic and biochemical characteristics of these histotypic cultures, are described. Type II alveolar epithelial cells can be isolated from fetal rat lungs and grown in an organotypic culture system as described in this review. The fetal Type II cells resemble differentiated rat Type II cells in morphology, biochemistry, and karyotype as they grow in culture for up to 5 weeks. The cells of the mature organotypic cultures form alveolarlike structures while growing on a gelatin sponge matrix. The Type II cells also synthesize and secrete pulmonary surfactant similar in biochemical composition to that produced in vivo. This system has been used to study the effects of hormones on surfactant production and composition. The organotypic model has many potential applications to the study of pulmonary toxicology.

Isolation, culture, and preliminary characterization of mucin-producing cells from trachea of the domestic fowl.

Primary cell cultures enriched in mucin-producing cells and basal cells were established from the trachea of the domestic fowl. Epithelial cells were selectively removed from the trachea after incubation in 0.1% pronase/0.1% EDTA in Moscona's saline. The majority of the ciliated cells were removed during the initial 30 minutes of incubation. After 50 minutes of incubation, aggregates of mucin-producing cells and basal cells were removed in large numbers. The cellular aggregates rapidly attached to a collagen-coated substratum and the cells spread out on the culture surface. The mucin-producing cells retained their AB/PAS-reactive secretory granules. The basal cells replicated and as the culture approached confluency, these cells developed a fine dusting of AB/PAS-reactive material; later, larger secretory granules appeared in the cells. These observations suggest that mucin-producing cells are capable of retaining their AB/PAS-reactive secretory products in primary culture and that basal cells are capable of differentiating into mucin-producing cells in vitro.

An ultrastructural study on a new type of hepatic perisinusoidal cell in fish.

A new type of perisinusoidal cell containing numerous microfilaments is described for the first time. It is found in abundance in the livers of both marine and freshwater fish. These perisinusoidal cells are situated within the space of Disse and adhere firmly through desmosomes both to sinusoidal endothelial cells and to hepatocytes. The cytoplasmic microfilaments are striking and make these cells readily distinguishable from the perisinusoidal fat-storing cells of Ito. Although the function of these cells is not known, the observations presented here suggest that they may provide a supportive framework within the liver.

New observations on the fine structure of the liver in goldfish (Carassius auratus).

A re-examination of goldfish liver was made through the use of SEM of fractured samples and TEM of ultrathin-sections and freeze-etch replicas. Several new hepatic fine structures described in the present study are morphologically similar to those reported previously in many higher vertebrates including mammals. Hepatic sinusoids of goldfish contain fenestrations which are arranged into sieve plates. Although the hepatic plates are made up of two layers of hepatocytes, the parenchymal cells of gold fish liver are morphologically similar to mammalian hepatocytes, particularly with respect to the sinusoidal surfaces which are studded with numerous microvilli. The intercellular surfaces of hepatocytes have both nexus and demosomal junctions, similar to those found in various epithelial cells of higher vertebrates, between the openings of the intracellular bile canaliculi and the intralobular bile ductules which are situated in the center of the bicellular hepatic plate.