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Biomedical subjects

L DuBois

Publications and source records attributed to L DuBois.

13 recordsLinked to original sources
PubMed2004

Optotype acuity and re-operation rate after unilateral cataract surgery during the first 6 months of life with or without IOL implantation.

AIMS: To compare optotype acuities and re-operation rates in children corrected with a contact lens (CL) compared with an intraocular lens (IOL) following unilateral cataract extraction during infancy in a non-randomised, retrospective case series. METHODS: 25 infants with a unilateral congenital cataract underwent cataract surgery with (IOL group, n = 12) or without (CL group, n = 13) IOL implantation when <7 months of age. Optotype acuities were assessed in 19 of these children at a mean age of 4.3 years (range 3.3-5.5 years). The number of re-operations were assessed in 21 children. RESULTS: The visual acuity results were similar in the two treatment groups (p = 0.99); however, two of the four (50%) children in the IOL group compared with two of the seven (28%) children in the CL group undergoing surgery during the first 6 weeks of life had 20/40 or better visual acuity. The children in the IOL group had more re-operations than the children in the CL group (mean 1.1 v 0.36). Most of the re-operations in the IOL group were membranectomies performed during the first year of life (median 8.0 months) whereas all of the re-operations in the CL group were the implantation of a secondary IOL later in childhood (mean 2.2 years). CONCLUSION: Optotype acuities were similar for the children corrected with a CL compared with IOL, while the children in the IOL group underwent more re-operations .

Cataract↗
PubMed1994

Epidemic optic neuropathy in Cuba. Eye findings.

OBJECTIVE: To characterize and establish a clinical definition of the optic neuropathy that appeared in epidemic form in Cuba in 1992 and 1993. METHODS: At the invitation of the Cuban Ministry of Health, Havana, members of ORBIS International and the Pan American Health Organization, assembled teams that traveled to Cuba in May 1993. We were initially briefed by Cuban national experts in the areas of virology, nutrition, toxicology, ophthalmology, neurology, and public health. We then examined 20 patients on our own. Thirteen of these patients underwent a comprehensive neuro-ophthalmologic examination, including neurologic examination, ophthalmologic examination, visual fields, optic nerve function studies, contrast sensitivity studies, and funduscopy. We returned 4 months later to perform an additional 12 comprehensive neuro-ophthalmologic and follow-up examinations. RESULTS: Only seven of the 13 patients who were alleged to have the optic form of the epidemic and who were rigorously and systematically examined on the first visit demonstrated a bilateral optic neuropathy. These seven patients had several features that included decreased visual acuity, poor color vision, central scotomas, decreased contrast sensitivity, saccadic eye movements, and most prominent and distinctive of all, nerve fiber layer wedge defects of the papillomacular bundle. Our clinical definition was then implemented by the Cuban ophthalmologists and epidemiologists. On returning 4 months later, we found that all newly presented patients were correctly diagnosed to have the epidemic disease. With the new case definition and the application of a few simple psychophysical tests, the false-positive rate of diagnosis became much lower. After vitamin therapy, we reexamined the patients seen on our initial visit, and all showed marked improvement. CONCLUSIONS: The Cuban epidemic was characterized by an optic neuropathy with features that were similar to those of tobacco/alcohol amblyopia and Leber's optic atrophy. Recent political, economic, and social changes in Cuba may have contributed to the nutritional and/or toxic compromise of mitochondrial function of an acquired nature, which led to selective retinal ganglion cell damage. We have termed this condition Cuban epidemic optic neuropathy.

Adult↗
PubMed1994

Factors that affect the rate of retakes for endodontic treatment radiographs.

The purpose of this study was to determine the most accurate method of taking radiographs during endodontic treatment to minimize the number of retakes. To accomplish this, the rate of retakes in an endodontic clinic at a dental school was measured. Then the effect that two factors, anatomic location and type of film holder, had on this rate were calculated and analyzed. Criteria for acceptability were that radiographs have adequate coverage and minimal distortion. Two endodontists evaluated endodontic treatment radiographs taken by undergraduate dental students to determine if these criteria were met. Of 402 films evaluated 77% were considered to be acceptable. A significantly higher rate of acceptability occurred with films taken in the mandible compared with those taken in the maxilla. The EndoRay (Rinn Corp., Elgin, Ill.) and hemostat were the only types of film holders compared. Films taken with the EndoRay in the maxilla had a significantly higher acceptability rate than those taken in the maxilla with a hemostat. No difference in acceptability existed between the two film holders when radiographs were taken in the mandible.

Clinical Competence↗
PubMed1981

An isoenzyme marker possibly associated with the susceptibility of Biomphalaria glabrata populations to Schistosoma mansoni.

Nine laboratory populations and one field population of the snail host Biomphalaria glabrata were compared with respect to their electrophoretic patterns for acid phosphatase (AcP) and with their susceptibility to Schistosoma mansoni infection. A strong correlation (r = 0.98) was noted between the frequency of the isoenzymes AcP2-S and Acp2-F observed in the populations and the level of snail susceptibility as determined by bioassay. The isoenzyme AcP2-S was associated with susceptibility, AcP2-F with the refractory state. Breeding experiments between refractory and susceptible snails demonstrated that the refractory state was dominant and all F1 snails exhibited the AcP2-F isoenzyme and proved refractory to infection.

Acid Phosphatase↗
PubMed1978

Susceptibility of Bahian population of Biomphalaria glabrata to an allopatric strain of Schistosoma mansoni.

Seventeen populations of snails (Biomphalaria glabrata) from the state of Bahia, Brazil were studied with respect to their susceptibility to infection with an allopatric strain of Schistosoma mansoni. Two of the populations were from the city of Salvador, 3 from other sites in Bahia, and 12 from habitats in the municipio Castro Alves. Our data show that the Bahian snail populations are extremely variable in their susceptibility to an allopatric strain of S. mansoni and that the phenomenon is not associated solely with distantly separated strains, but is present, as well, in adjacent populations situated in a restricted geographic region. Of the 6 populations found to be completely refractory to infection when exposed at a size of 5--7 mm, only 2 were refractory when exposed at 5--12 days of age. It is suggested that the variability to infection displayed by populations in a restricted geographic area may be explained by assuming that the Founder Principle was operative.

Animals↗
PubMed1978

Spontaneous activities of female versus male newborns.

This study explored potential sex differences in all activity spontaneously emitted by newborns. 2 groups of full-term infants (14 uncircumcised males, 15 females), equally distributed along several physical and demographic variables, served as subjects. Each newborn was observed for a total of 8 hours during the 2 days following birth. Observational procedures were stringently controlled and interobserver reliability ranged from .84 to .98. Results showed higher levels of wakefulness, facial grimacing, and low-intensity motor activity for males. Of marginal significance, both low-intensity and high-intensity oral activity was higher for males. In addition, a marginally significant interaction effect (sex X interfeeding interval X day) was found for high-intensity oral activity (crying). Independent of sex, high-intensity activity increased in the evening and over an interfeeding period, and low-intensity oral activity increased over days. The pattern of results indicates that even uncircumcised males may be slightly more irritable than females, and thus more active. Potential implications of these findings are considered.

Circadian Rhythm↗
PubMed1975

The stability constants of magnesium oxalate complexes.

The stability constants of MgC204 and Mg2C204-2nCOmplexes were estimated at 37--38 C by four different techniques; there was good agreement among the results of the different techniques. The stability constant of MgC204 is (4019 plus or minus 76 M-minus 1). The stability constant of Mg2C204-2nWAS FOund to be less than 5 M-minus 1. These stability constant are needed in the evaluation of the stone-forming potential of urine.

Anions↗
PubMed1975

Intraspecific variations in the hemolymph of Biomphalaria glabrata, a snail host of Schistosoma mansoni.

An attempt was made to characterize the hemolymph of Biomphalaria glabrata with reference to "normal" intra-specific variation, i.e., both inter- and intra-strain differences. Total protein concentration, per cent hemoglobin, pH, and osmolarity were studied. Seven geographic strains of B, glabrata were examined. In addition, observations were made on the hemolymph of Biomphalaria straminea, several strains of Helisoma caribaeum, and on B. glabrata subjected to infection with Schistosoma mansoni or to periods of starvation. Intra-strain differences in total protein concentration and total hemoglobin concentration in B. glabrata appeared to be more closely related with snail size than with absolute age. Inter-strain variation in B. glabrata was also noted, but the differences were of the same magnitude as those from intra-strain samples. Significant differences in total protein concentration were observed, however, between the means of similar size B. glabrata, B. straminea and H. caribaeum. The osmolatity of the hemolymph from different size B. glabrata was similar as were the osmolalities of the hemolymph from similar size snails of different strains. However, all B. glabrata strains exhibited hemolymph osmolalities lower than observed in strains of H. caribaeum. Infection with S. mansoni reduced the protein concentration of B. glabrata hemolymph. Differences were noted as early as 1.5-24 hr post-infection, with significant alterations occurring at about 11 days post-infection. To a lesser extent, starvation also depleted the protein content of the hemolymph.

Animals↗
PubMedDate not supplied

A radiographic investigation of third-molar development.

In view of limited investigations it was considered worthwhile to determine the impact of race, age, and gender on the development and calcification of third molars. Results showed that calcification of third molars could be estimated by observing one quadrant. The crown calcification process begins and is completed earlier in blacks. There were no significant gender differences.

Adolescent↗