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Biomedical subjects

L Kelly

Publications and source records attributed to L Kelly.

At least 91 records · Page 5Linked to original sources
PubMed1997

Perception and control of altitude: splay and depression angles.

In 3 experiments altitude control was examined as a function of texture type and forward speed. Four texture types were used: grid (rectangular grid with neutral colored cells); dot (small triangles distributed randomly on the ground surface); splay (rows of colored texture parallel to the direction of motion); and depression (rows of colored texture extending perpendicular to the direction of motion). The first 2 experiments required participants to track a constant altitude. Experiment 3 required participants to descend as low as possible without crashing. Results showed an interaction between texture type and forward speed. At low speeds, there was little difference between performance with the depression and splay textures. However, performance with the depression texture deteriorated with increasing forward speeds. Performance with the splay texture was independent of forward speed.

Altitude↗
PubMed1997

Chemical lesion of visceral afferents causes transient overconsumption of unfamiliar high-fat diets in rats.

Because it is commonly assumed that the major role of visceral afferents in food intake control is to terminate meals by carrying negative-feedback signals to the brain, we hypothesized that overconsumption should occur in rats with chemically lesioned visceral afferents if they were presented with an unfamiliar diet. Adult male Sprague-Dawley (SD) rats were treated with multiple doses of capsaicin or vehicle as a control. Five weeks later, a series of 3-h feeding tests after 24-h deprivation was carried out, first with chow and then with either a solid (vegetable shortening) or liquid (Ensure) unfamiliar high-fat diet. Both groups consumed similar amounts of their powdered chow maintenance diet, but capsaicin-treated rats consumed at least 50% more of either high-fat diet than vehicle controls (P < 0.01) at the beginning of the first trial. During second and third trials with the now-familiar high-fat diet, intake was no longer significantly different between the two groups, suggesting rapid engagement of redundant control mechanisms. These results support a role of capsaicin-sensitive visceral afferents in providing negative feedback for early meal termination during the ingestion of unfamiliar diets.

Afferent Pathways↗
PubMed1997

Integrating family medicine residents into a rural practice.

PROBLEM: Integrating residents into community family practices can be challenging for busy doctors, especially when new preceptors have no formal preparation or teaching experience. OBJECTIVE OF PROGRAM: To develop an organized and practical approach to teaching residents in our busy rural group practice. Our seven northern Ontario family doctors have been training elective residents and clerks for 15 years. Recently, we have gone from hosting elective residents and students to teaching core family medicine residents. Our precepting plan allows us to dedicate a reasonable time to teaching while fulfilling our primary care duties. MAIN COMPONENTS: The program involves contracting, teaching, monitoring, feedback, and evaluation. CONCLUSION: We think we have developed a sustainable, workable set of teaching parameters that is applicable by various preceptors in different settings. It has simplified our teaching role and lessened our anxieties. Residents have benefited from the consistent protocol, which can be flexible enough to adapt to individual residents and preceptors, and have valued this teaching approach.

Clinical Protocols↗
PubMed1996

Short-term stimulation-induced decreases in brown fat temperature.

Electrical stimulation of the ventromedial hypothalamus (VMH) has been shown to activate brown adipose tissue (BAT) thermogenesis; we hypothesized that functional links between the VMH and other hypothalamic areas may serve to regulate intrinsic VMH control of brown fat heat production. Moveable electrodes were implanted in regions surrounding the VMH in adult male rats in order to assess any acute effect of activation of these structures alone on brown fat temperature. Stimulation in the area of the ventral lateral thalamic nucleus and the zona incerta (ZI) elicited a 0.2 to 0.8 degrees C drop from brown fat baseline temperature in 48 of 55 rats; the effective sites in the ZI area are restricted to the actual band of the nucleus. Application of the alpha-adrenergic blocker phentolamine prior to restimulation of active sites yielded mixed results; these findings are compatible with a role for the vasoconstrictive action of alpha-adrenergic receptors in the regulation of BAT temperature drops. The mechanisms underlying thermoregulatory responses or diurnal temperature cycling may provide a physiological context for the findings reported here.

Adipose Tissue, Brown↗
PubMed1996

Absence of negative attitudes toward childbearing among pregnant teenagers. A risk factor for a rapid repeat pregnancy?

OBJECTIVE: To test the hypothesis that adolescent mothers who conceive again during the first postpartum year express more positive attitudes toward childbearing while pregnant than do adolescent mothers who postpone further childbearing. METHOD: Prospective, cross-sectional, population-based survey. DESIGN: A racially diverse group of 200 consecutively enrolled, poor, pregnant 13- to 18-year-old patients in an adolescent-oriented maternity program were interviewed to determine why they had not used contraceptives prior to the index conception. The study participants were followed up prospectively for the first postpartum year. The data analysis included t tests, chi 2 tests, analysis of variance, and logistic regressions. RESULTS: The repeat pregnancy rate was 11.5% during the first postpartum year. As hypothesized, those who became pregnant again were more likely to have expressed positive attitudes toward childbearing during the index pregnancy (60.9% vs 39.6%; P = .05; odds ratio = 2.38; 95% confidence interval, 0.96-5.90). In addition, those who conceived again were more likely to have had a prior miscarriage, dropped out of school, abused illicit substances, moved away from home, and reported inadequate family support during the index pregnancy, and were less likely to plan to use levonorgestrel (Norplant) following delivery. The best model for predicting repeat pregnancy included education status, postpartum plans for Norplant use, and miscarriage history. Having a positive attitude toward childbearing during pregnancy was not included in the final model because it did not contribute to the model or affect any of the other parameters in the model. CONCLUSIONS: The sexually active teenaged mother who does not use contraception poses a perplexing diagnostic dilemma. The differential diagnosis is a long, complex one that includes ambivalent feelings about postponing future childbearing. This study demonstrates an indirect association between positive attitudes toward childbearing during pregnancy and repeat adolescent pregnancy. Our finding that this association operates through common linkages between maternal educational and contraceptive plans and both positive attitudes toward childbearing and repeat adolescent pregnancy suggests that interventions specifically targeting these underlying causes could reduce the unsafe sexual practices that persist among the participants in comprehensive adolescent-oriented maternity programs.

Adolescent↗
PubMed1996

Why pregnant adolescents say they did not use contraceptives prior to conception.

OBJECTIVE: In this study we attempted to learn why childbearing adolescents failed to use contraceptives prior to conception. We hypothesized that among adolescents who elect to bear their children, positive and/or ambivalent feelings about having a baby are the most frequently cited reasons for not having used contraceptives. STUDY DESIGN: This is a cross-sectional, clinic-based survey of a racially and ethnically diverse group of 200 consecutively enrolled, poor, pregnant, 13-18-year-old patients in an adolescent-oriented maternity program. The participants completed a self-administered questionnaire which elicited information about environmental and personal risk factors for inconsistent use of contraceptives and information about the reasons they had not used contraceptives consistently prior to conception. Student's t-tests, Chi-square, and logistic regression analyses were used. RESULTS: The most frequently cited reasons for not using contraceptives prior to conception were: "I didn't mind getting pregnant" (20%) and "I wanted to get pregnant" (17.5%), followed by "I was using birth control but it didn't work (broke)" (12%), "I thought there was something wrong with me and I couldn't get pregnant" (9%) and "I just didn't get around to it" (9%). Teenagers who cited positive and/or ambivalent attitudes toward childbearing as their primary reason for not using contraceptives at the time of conception did not differ from others with regard to age, Medicaid status, gravidity, parity, frequency of living with parents, partner's age, depressive symptoms, or perceived family support. They were, however, more likely to have known the father of the baby for more than 6 months at the time of conception [odds ratio (OR) 2.53; 95% confidence interval (CI) 1.22-5.26) and to have dropped out of school (OR) 2.15; 95% CI 1.10-4.26]. CONCLUSIONS: The study hypothesis was supported. The absence of negative attitudes toward having babies rather than negative attitudes toward contraceptives is the most commonly cited reason for nonuse of contraceptives among childbearing adolescents. The results of this study may enable health care and social service providers to design more effective programs for preventing first and subsequent adolescent pregnancies.

Adolescent↗
PubMed1996

The interaction of syntactic competence and vocabulary during reading by deaf students.

This research studied whether deaf students' component reading processes may interact with other in a competitive manner. Vocabulary and syntax, two processes known to directly and adversely affect the comprehension of many deaf readers, were studied to determine if they may influence each other, affecting the contribution that each one makes separately to reading comprehension. Multiple regression analyses were conducted on predictor variables that included measures of vocabulary and syntactic competence, as well as a variable summarizing the interaction of vocabulary and syntax. The criterion variable was a composite of comprehension performance on a cloze procedure and on a more traditional reading test. Results were cross-validated by separate regressions on data samples from three populations of profoundly deaf readers: 100 adolescents from oral school programs, 113 adolescents from total communication programs, and 211 students entering a postsecondary institution that used total communication. In each regression, the Vocabulary &times; Syntax interaction variable emerged as the most critical of the three predictors. Further analyses of the interaction revealed that among subjects in the highest quartile of syntactic competence, the correlation between vocabulary competence and reading was significantly greater than it was in the lower three syntax quartiles. In contrast, the relationship between syntax and comprehension remained stable across all four quartiles of vocabulary competence. This suggests that unless deaf readers have achieved a reasonable level of syntactic competence it may be difficult for them to capitalize fully on their vocabulary knowledge. The finding that limitations in one reading process can interfere with the application of another is consistent with the theory of Capacity Constrained Comprehension of M. Just and P. Carpenter (1992). Because syntax can exert both a direct and an indirect influence on comprehension, it should be an important focus in instructional programs.

Journal Article↗
PubMed1995

Differences in laser-induced autofluorescence between adenomatous and hyperplastic polyps and normal colonic mucosa by confocal microscopy.

Laser-induced autofluorescence has been used to discriminate normal from adenomatous colonic mucosa. However, few studies to date have studied the origin of colonic autofluorescence. Using confocal microscopy (excitation wavelength 488 nm), we have shown that autofluorescence at this wavelength is present predominantly in the lamina propria of normal mucosa but in the epithelium in adenomatous and hyperplastic polyps. The intensity ratio of epithelial cell to lamina propria fluorescence was significantly lower (P < 0.0001) in normal mucosa (0.52 +/- 0.01) compared with either adenomatous (1.6 +/- 0.2) or hyperplastic polyps (1.7 +/- 0.15). However, the ratios were not significantly different between hyperplastic and adenomatous polyps. Thus, confocal microscopy enables the detection of the sites of autofluorescence within colonic mucosa and the quantitation of differences in fluorescence between different tissue types.

Adenomatous Polyps↗
PubMed1995

Improved competitive enzyme immunoassay for the diagnosis of bovine brucellosis.

A modification of the competitive enzyme-linked immunosorbent assay (C-ELISA) for differentiating the antibody response of cattle vaccinated with Brucella abortus strain 19 and B. abortus infected cattle is described. This assay utilizes lipopolysaccharide as the antigen, immobilized on a polystyrene matrix, and a monoclonal antibody (M84) with specificity for an epitope of the O-polysaccharide. A goat anti-mouse IgG antibody-enzyme conjugate is used for detection. The specificity of the modified assay was 99.7% when 1446 sera from brucellosis free herds were tested and it correctly identified 636 sera from B. abortus infected cattle as positive, using a cut-off of 30% inhibition, for a sensitivity estimate of 100%. No reactions were noted among 261 sera from vaccinated cattle. However, in testing 1147 sera that gave positive reactions in the buffered plate antigen test, the indirect ELISA, the complement fixation test or a combination of these tests from the serum bank, 31 gave positive reactions. Twenty-seven of the 31 sera originated from recently vaccinated cattle. The overall specificity for sera from vaccinated cattle was 97.3%. Because of the sensitivity and specificity of this procedure and its ease of performance, it would be a reasonable alternative as a single assay for serological diagnosis of brucellosis.

Animals↗
PubMed1995

The expression of antisense and ribozyme genes targeting citrus exocortis viroid in transgenic plants.

Four ribozyme and antisense genes targeting citrus exocortis viroid (CEVd) positive- and negative-strand RNA molecules were constructed and used to transform the tomato Lycopersicon lycopersicum cv. UC82B. The tomato is a readily transformable plant and will support replication of CEVd following mechanical inoculation. The ribozyme genes contained three hammerhead catalytic motifs with long hybridizing arms and synthetic RNA transcripts were shown to cleave the target CEVd RNA molecule in vitro. Homozygous transgenic plants were produced from independent transformants expressing either ribozymes or antisense constructs. Inoculation of transgenic seedlings expressing antisense constructs targeting the negative-strand CEVd RNA molecule with CEVd resulted in a moderate reduction in the accumulation of CEVd RNA. In contrast, similarly inoculated transgenic plants expressing constructs targeting the positive-strand CEVd RNA molecule resulted in an increase in the rate of CEVd RNA accumulation. Addition of the ribozyme motifs to the antisense genes did not enhance their efficiency in the suppression of viroid replication and a moderation or elimination of the observed antisense effects was seen in plants expressing the corresponding catalytic RNA-encoding genes.

Citrus↗
PubMed1994

Characterisation of the subgenomic RNAs of an Australian isolate of barley yellow dwarf luteovirus.

We have characterised the subgenomic RNAs of an Australian isolate of BYDV-PAV. Northern blot analyses of infected plants and protoplasts have shown that this isolate synthesizes three subgenomic RNAs. Precise mapping of the transcription start sites of all three subgenomic RNAs and translational analyses of subgenomic RNA 2 and 3 have revealed a number of features. First, the transcription start site of subgenomic RNA 1 in this isolate differs markedly from the start site determined for an Illinois isolate of BYDV-PAV. Second, the start sites of subgenomic RNA 1 and 2 occur at a sequence that closely resembles the 5' end sequence of the genomic RNA (5'AGUGAAGA). Third, subgenomic RNA 2 appears to express ORF 6 of BYDV-PAV but the gene product is truncated due to the appearance of a new stop codon in the sequence. Last, subgenomic RNA 3, which is abundantly transcribed and encapsidated by the virus particle, appears to have no coding ability. We postulate that this novel subgenomic RNA has a regulatory function.

Australia↗
PubMed1994

Sequence variability in the genome-3'-terminal region of BYDV for 10 geographically distinct PAV-like isolates of barley yellow dwarf virus: analysis of the ORF6 variation.

Nucleotide sequence of the genome terminal region 3' to the capsid-readthrough cistron were compared for 10 PAV-like isolates of barley yellow dwarf virus (BYDV) from three continents. The sequenced region varied in length from 853 to 864 nucleotides and the extent of sequence homology among the isolates ranged from 84 to 99%. Sequence variations occur mainly in two locations, one in the ORF6 coding region and the other near the genome 3' terminus. Sequence homology grouping reveals three genetically distinct clusters of PAV isolates (A, B and C). Cluster A consists of the Australian isolates, cluster B of one Canadian and three French isolates, and cluster C of the French isolate, RG. Dissimilarities with the corresponding genome-3'- terminal region of the BYDV-MAV serotype were greater than those observed between the PAV isolates alone. Comparison with the sequence of the 3' untranslated region of soybean dwarf virus revealed two stretches of nucleotide similarity, suggesting a common ancestor. Study of the coding ability revealed that the ORF6 is present in all the sequenced PAV isolates but differs in size and deduced amino acids composition. However, the fact that the majority of nucleotide changes are restricted to the third base position of the ORF6-codons suggests that ORF6 codes for a functional protein.

Amino Acid Sequence↗
PubMed1994

The use of divalent cation chelating agents (EDTA/EGTA) to reduce non-specific serum protein interaction in enzyme immunoassay.

An indirect enzyme immunoassay (ELISA) for detection of bovine antibody to Brucella abortus was modified by the addition of divalent chelating agents to the serum diluent. This addition resulted in an increase in specificity from 96.0% in the regular assay to 99.4% in the modified procedure. Of the 15,715 sera initially tested by the indirect ELISA, 691 that had given positive reactions were selected for retesting in the indirect ELISA with EDTA/EGTA added. The buffered plate antigen test (BPAT) correctly identified 98.6% of the samples as negative. The addition of chelating agents did not alter the sensitivity of the indirect ELISA, which correctly classified 609 sera from animals from which B. abortus had been isolated as positive. The sensitivity of the BPAT was 97.8%.

Agglutination Tests↗
PubMed1994

Comparative analysis of neovascularization in primary cutaneous melanoma and Spitz nevus.

Spitz nevus is a well-known histologic simulator of malignant melanoma. Vascularity of human neoplasms has been associated with prognosis as well as propensity for metastasis. Were vascularity significantly different between melanoma and Spitz nevus, it could serve as a feature to distinguish between these two neoplasms. We evaluated the vascularity of a series of primary cutaneous melanomas ranging from thin superficial spreading to nodular lesions as well as superficial compound and nodular deep Spitz nevi by using light-microscopic evaluation of factor-VIII-stained sections. Vascularity was density graded and microvessels were counted per x200 and x400 field. Vascular density and microvessel counts were significantly different between melanomas of 2+ and 3+ vascularity compared with all types of Spitz nevi. Although nodular malignant melanomata tended to have a greater degree of vascularity than thin melanomas, there was a significant population of both of these subtypes having few or many vessels. We conclude that the number of microvessels per x200 and x400 field in areas of greatest vascularity is significantly less in Spitz nevus than in malignant melanoma. There is a subset of melanoma, however, in which the number of microvessels may be low. Nodular melanomata tended to have a greater number of vessels than did thin superficial spreading lesions. Evaluation of microvessel count may be of assistance when coupled with clinical and histologic findings in distinguishing between melanoma and Spitz nevus in selected cases.

Blood Vessels↗