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Biomedical subjects

W C Smith

Publications and source records attributed to W C Smith.

At least 91 records · Page 5Linked to original sources
PubMed1996

Pediatric sphenoidotomy.

The posterior ethmoid air cells and the sphenoid sinuses have a complex anatomy that is surrounded by vital structures. To more easily protect these structures, three approaches are presented that make pediatric sphenoidotomy a safer procedure. The approaches include measuring the distance from the anterior nasal spine to the anterior and surgical posterior faces of the sphenoid sinus intraoperatively and comparing these to the patient's height and age, the use of the "ridge" to ensure a safe entry into the sphenoid, and, in patients where isolated sphenoid disease is present, the use of a powered instrument to enlarge the sphenoid ostium. The availability of measurements relating the height of the patient to the location of the sphenoid sinus, the use of the "ridge," and the use of powered instrumentation, should help the surgeon enter the sphenoid with greater confidence and achieve a more effective result.

Adolescent↗
PubMed1996

Eliminating leprosy as a public health problem--is the optimism justified?

Systematic use of multidrug therapy has proved to be so effective that leprosy can be eliminated as a public health problem by the end of the century. However, because of the long incubation period of this disease, together with the time-lag in case detection, the factors involved in achieving and sustaining its elimination have to be very carefully defined.

Communicable Disease Control↗
PubMed1996

[Prevention of disabilities and physical rehabilitation of leprosy].

A survey of the prevention of disability policy and activities in a random sample of 200 ILEP assisted projects was conducted in 1995. This was followed by a workshop of field experts in different aspects of prevention of disability who work in different geographical regions. The survey findings and state of current knowledge on prevention of disability were reviewed during the workshop and recommendations on the planning, implementation, and evaluation of simple and effective prevention of disability developed. Prevention of disability includes complex activities, such as nerve decompression and reconstructive surgery, however these recommendations focus on the simple techniques and approaches which can be implemented through leprosy control programmes, primary health care and community-based rehabilitation. These recommendations have been approved by the ILEP Medical Commission, and reported in the ILEP Medical Bulletin (N degree 8, December 1995).

Persons with Disabilities↗
PubMed1996

Prevention of disability and rehabilitation--results from a collaborative project in China.

Eight different geographical districts in China varying in urban and rural characteristics from 6 provinces and 2 municipalities were selected as pilot areas of the project. The interventions included early detection and treatment of neuritis, self-care training, adapted footwear, surgery, comprehensive treatment of complicated ulcers, and prostheses. Main changes in eye, hand and foot impairments between baseline assessment and assessment at 2 years have been presented in this paper.

China↗
PubMed1995

The sequence of arrestins from rod and cone photoreceptors in the frogs Rana catesbeiana and Rana pipiens. Localization of gene transcripts by reverse-transcription polymerase chain reaction on isolated photoreceptors.

Members of the arrestin protein family are known to participate in the inactivation of rhodopsin and other heptahelical receptors. Arrestins bind to the activated and phosphorylated state of these receptors, consequently blocking the ability of the receptors to activate the guanine-nucleotide-binding protein (G protein). We have determined the sequences of four retinal arrestins from two species of frog, Rana catesbeiana and Rana pipiens. Using polymerase chain reaction on reverse-transcribed mRNA isolated from single photoreceptor cells, we show that two of these arrestins are from rod photoreceptors and two rod photoreceptors and two are from cone photoreceptors. Comparison of these arrestins with the twenty known arrestin sequences identifies three regions of the protein that are well conserved across all phylogenetic groups. These regions may function in the binding of the arrestin to the heptahelical receptors. In addition, the Rana arrestins contain a uniquely acidic C-terminal sequence.

Amino Acid Sequence↗
PubMed1995

The deduced amino-acid sequence of opsin from rabbit rod photoreceptors.

The amino acid (aa) sequence of rabbit opsin from rod photoreceptor cells was determined by direct aa sequencing and conceptual translation from the cDNA. The cDNA (1198 bp) containing the complete coding region encodes a 348-aa opsin protein. Of the 16 rod cell opsins that are known, rabbit opsin is most similar to human opsin (96.3% identity at the aa level).

Amino Acid Sequence↗
PubMed1995

A nodal-related gene defines a physical and functional domain within the Spemann organizer.

A functional screen for gene products that rescue dorsal development in ventralized Xenopus embryos has yielded Xenopus nodal-related 3 (Xnr3), a diverged member of the TGF beta superfamily. Xnr3 is specifically expressed in the Spemann organizer and is only expressed in the epithelial layer of the organizer immediately preceding and extending through gastrulation. Like noggin, Xnr3 can induce muscle in ventral mesoderm explants, consistent with a role in patterning the gastrula. In other ways, the activity of Xnr3 is different from noggin. Embryos receiving injections of Xnr3, particularly in the animal pole, send out tube-like extensions of tissue from the site of injection. These protrusions usually contain no axial mesoderm and only occasionally are positive for neural markers. It has previously been proposed that the epithelial layer of the organizer initiates and coordinates the morphogenetic movements at gastrulation. The protrusions observed may reflect an activity of Xnr3 in promoting morphogenesis.

Actins↗
PubMed1995

Beliefs and attitudes as determinants of cervical cancer screening: a community-based study in Singapore.

BACKGROUND: The investigation of cervical cancer screening acceptance in relation to health beliefs and attitudes presents a challenge in a multiethnic population such as Singapore's, where the uptake is currently suboptimal in high-risk groups. This study attempts to identify cognitive barriers to screening activity in order to suggest possible directions for cervical cancer prevention efforts. METHODS: A cross-sectional survey consisting of a household interview of 640 randomly selected women ages 21-65 years was performed. The screening history and future intention to have a Pap smear were elicited, and attitudes toward cancer and the Pap smear as expressed in 14 statements were measured on a five-point scale. RESULTS: Of the respondents, 73.1% were aware of the Pap smear, and about half (49.7%) had obtained the information from a doctor or nurse. Overall, the belief in personal susceptibility to cancer was low (58.9%) and a substantial proportion (48.7%) of women were of the attitude that cancer could not be prevented. The effect on a future intention to have a smear varied between women who had had and women who had not had a smear. Among the former, perceived barriers such as discomfort and embarrassment had a significant influence, while a belief in personal susceptibility was an important determinant for the latter group. CONCLUSIONS: The means of increasing the acceptance of the Pap smear, both for the first time and subsequently, are culture-specific and must address the appropriate health beliefs and attitudes. In Singapore, such efforts should include not only influencing awareness and perceptions through public education but also reducing barriers by creating an appropriate environment for the delivery of this important health service.

Adult↗
PubMed1995

Alligator rhodopsin: sequence and biochemical properties.

We sequenced selected peptides of alligator rhodopsin that accounted for about half of the total protein. These sequences were confirmed when the total primary structure of alligator rhodopsin was deduced from the cDNA sequence. Differences in the amino-terminal region, compared to that of bovine rhodopsin, account for failure of cross-reactivity of several anti-bovine rhodopsin monoclonal antibodies. Differences in the carboxyl-terminal region give rise to limited antibody cross-reactivity and may also account for a slightly reduced ability of alligator rhodopsin to be phosphorylated by bovine rhodopsin kinase. Alligator rhodopsin regenerates much faster than bovine rhodopsin. The pseudo-first-order rate constant for alligator rhodopsin regeneration is approximately 25 times that of bovine. Phylogenetic analysis of 17 rhodopsin sequences indicates that the alligator is more closely related to the chicken than to the other species examined.

Alligators and Crocodiles↗
PubMed1995

Isolation and expression of an arrestin cDNA from the horseshoe crab lateral eye.

Electrophysiological studies of photoreceptors from the horseshoe crab Limulus polyphemus continue to provide fundamental new knowledge of the photoresponse in invertebrates. Therefore, it is of particular interest to characterize the molecular components of the photoresponse in this system. Here we describe an arrestin cloned from a cDNA library constructed using poly(A)+ RNA isolated from Limulus lateral eyes. The protein, deduced from the arrestin cDNA, is most similar to arrestin from locust antennae (56% identity) and Drosophila phosrestin I (53% identity). Limulus arrestin was expressed in a heterologous system, and its properties were compared with those of a 46-kDa light-regulated phosphoprotein (pp46A) in Limulus photoreceptors described in previous studies from this laboratory. Arrestin and pp46A (a) have the same apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (b) have an isoelectric point in the basic pH range, (c) require calmodulin and elevated Ca2+ levels for phosphorylation, (d) are immunoreactive with monoclonal antibody C10C10 directed against a sequence in bovine arrestin (S-antigen) that is perfectly conserved in the deduced arrestin protein, and (e) are associated with photoreceptors. We conclude that the arrestin described here and pp46A are the same protein. The results of this and previous studies show that in Limulus photoreceptors, light regulates the phosphorylation of arrestin in complex ways.

Amino Acid Sequence↗
PubMed1995

Prevention of impairment in leprosy; results from a collaborative project in China.

OBJECTIVE: to evaluate programs of prevention and treatment of impairments due to leprosy in 8 geographical areas in the People's Republic of China. DESIGN: follow up of cohorts of leprosy patients receiving a range of different interventions. SETTING: 8 different geographical areas in China, varying in urban and rural characteristics from 6 provinces and 2 municipalities. SUBJECTS: leprosy patients who were receiving or had completed a course of antileprosy chemotherapy. INTERVENTIONS: a range of interventions, including steroids, self-care training, adapted footwear, surgery and provision of prostheses. MAIN OUTCOME MEASURES: changes in eye, hand and foot impairments between baseline assessment and assessment at 2 years. RESULTS: 232 out of 3571 patients assessed monthly over 2 years developed acute neuritis and, in most areas, were promptly and adequately treated. Regular self care of eyes was established in 238 out of 313 patients with lagophthalmos and was associated with reduction in the prevalence of conjunctivitis. Regular self care of hands was established in 730 out of 1010 patients with neurological impairment of the hand; this was associated with a reduction (80%) in hand cracks and wounds. Regular self care of feet was established in 745 out of 1094 patients with neurological impairment of the feet; this was associated with a 83% reduction in patients with cracks and a 33% reduction in patients with sole wounds. A footwear program was established in all 8 areas providing footwear to 4698 patients over the 2-year period; this was associated with a reduction of 61% and 21% in patients with cracks and wounds, respectively. Management of complicated sole wounds in 256 patients resulted in 69% of these patients being free of sole wounds at 2 years. Targets for reconstructive surgery and amputations were not fully attained, but lower limb prostheses were provided for 306 patients. CONCLUSIONS: leprosy is a chronic disease characterized by peripheral neuropathies which can result in increasing secondary impairments and disabilities. The emphasis, in countries such as China where the chemotherapy programs have been effectively implemented, is shifting to prevention and treatment of impairments. This innovative program in China has successfully demonstrated that it is possible to prevent and reverse impairments due to leprosy.

Artificial Limbs↗
PubMed1994

A splice variant of arrestin. Molecular cloning and localization in bovine retina.

Inactivation of photolyzed rhodopsin requires phosphorylation of the receptor and binding of the 48-kDa regulatory protein arrestin. We recently isolated a novel form of arrestin, termed p44, that is truncated at the COOH terminus (Palczewski, K., Buczylko, J., Ohguro, H., Annan, R. S., Carr, S. A., Crabb, J. W., Kaplan, M. W., Johnson, R. S., and Walsh, K. A. (1994) Protein Sci. 3, 319-329) and strongly inhibits Gt activation by non-phosphorylated rhodopsin. p44 is identical to arrestin except at the COOH terminus, where the 35 amino acids of arrestin are replaced by a single alanine residue. p44 is identified as a splice variant of arrestin based on the identical cDNA sequence of p44 with arrestin (except the 3' non-coding regions), the presence of an exon/intron junction at the Ser369 codon, and identical Southern hybridization patterns generated by the 3' non-coding portion of arrestin and p44. Immunocytochemistry reveals that p44 is localized in the photoreceptor outer segment, whereas arrestin is present throughout the cell. This specificity of localization to the outer segment is consistent with a role of p44 in the phototransduction cascade.

Alternative Splicing↗
PubMed1994

Evaluation of a multidrug therapy programme of leprosy control.

MDT programmes for leprosy control have two objectives, controlling leprosy in populations and controlling leprosy in individuals. Evaluation of such programmes needs to address both objectives and this can be done by a review of the trends in key indicators and by site visits. Site visits are more expensive and should be done less frequently, but they can reveal issues not apparent in routinely produced statistics. Evaluation on an annual basis is the responsibility of programme managers and programme funders. Evaluation by programme staff themselves should be encouraged and supported. Evaluation of an MDT programme's effectiveness in controlling leprosy in a population should be by analysis of case detection as a proxy for incidence. Prevalence rates will continue to be monitored because of the WHO elimination goal, but these do not reflect disease transmission. Case detection is a proxy measure of incidence and depends on consistency in case detection activities. Case detection data by age, gender, mode of detection, disability ratio and lepromatous (MB) rate need to be analysed over at least 5 years and preferably 10 years to give an indication of trends in incidence. Caution is needed, however, as the pattern seen when case detection deteriorates may resemble the pattern expected when transmission is reduced. The site visit is important in this situation in allowing examination of the case detection activities, as well as in looking for new, undetected cases in the population.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Neural induction by the secreted polypeptide noggin.

The Spermann organizer induces neural tissue from dorsal ectoderm and dorsalizes lateral and ventral mesoderm in Xenopus. The secreted factor noggin, which is expressed in the organizer, can mimic the dorsalizing signal of the organizer. Data are presented showing that noggin directly induces neural tissue, that it induces neural tissue in the absence of dorsal mesoderm, and that it acts at the appropriate stage to be an endogenous neural inducing signal. Noggin induces cement glands and anterior brain markers, but not hindbrain or spinal cord markers. Thus, noggin has the expression pattern and activity expected of an endogenous neural inducer.

Animals↗