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Biomedical subjects

J Stiles

Publications and source records attributed to J Stiles.

At least 37 records · Page 2Linked to original sources
PubMed1997

Hemispheric asymmetries in global and local processing: evidence from fMRI.

Functional magnetic resonance imaging (fMRI) was used to explore the brain substrate associated with global and local processing of visuospatial patterns. Systematic differences in activation, consistent with differences observed in reaction time data collected under conditions of visual hemifield presentation, were found in occipitotemporal regions of the right and left hemispheres. Within the right hemisphere, area of activation and fractional signal changes were greater under conditions of global processing than under local processing conditions. In the left hemisphere, activation to global and local input was high and comparable.

Adult↗
PubMed1997

The development of drawing in children with congenital focal brain injury: evidence for limited functional recovery.

Children with pre- or perinatal injury to right hemisphere (RH) brain regions show impairment of spatial integrative functions similar to that observed among adults with comparable injury. Unlike adults, children show considerable improvement with development on a range of spatial construction tasks which require spatial integration. Such gains could reflect true recovery of spatial integrative abilities. Alternatively, the improvement could be more limited in scope, reflecting the development of compensatory strategies which are task specific and allow the children to circumvent, rather than overcome, their primary spatial disorders. The studies presented here examined this distinction within the context of drawing tasks in which the child was first asked to draw a house and then an impossible house. The impossible house task was designed to examine the extent to which children rely on graphic formulas in generating organized drawings. The results showed that while all of the children with RH injury make considerable progress in free drawing into the school age period, they are very reliant on the use of graphic formulas. When given a task which requires them to alter their drawings, they did not change the spatial configuration of the depicted object. Rather they found alternate ways to render the object 'impossible'.

Adolescent↗
PubMed1997

Use of nested polymerase chain reaction to identify feline herpesvirus in ocular tissue from clinically normal cats and cats with corneal sequestra or conjunctivitis.

OBJECTIVE: To use a nested polymerase chain reaction (PCR) to detect feline herpesvirus (FHV-1) DNA in conjunctiva or cornea from clinically normal cats and cats with conjunctivitis or corneal sequestra. SAMPLES: Conjunctival snip biopsy specimens from 50 cats with conjunctivitis and 50 clinically normal cats; 28 keratectomy specimens from 26 cats with sequestra, and 13 specimens from clinically normal cats. PROCEDURE: Tissue specimens were digested, and FHV-1 DNA was amplified, using a double round of PCR. Products were visualized by use of agarose gel electrophoresis. RESULTS: Polymerase chain reaction was positive in 27 of 50 (54%) conjunctival specimens from cats with conjunctivitis and 6 of 50 (12%) specimens from clinically normal cats. Difference in the results between cats with conjunctivitis and clinically normal cats was statistically significant. Polymerase chain reaction was positive in 5 of 28 (18%) corneal specimens from cats with sequestra and 6 of 13 (46%) clinically normal cats. Distribution of positive results between clinically normal cats and those with sequestra was not significant. CONCLUSION: Cats with conjunctivitis were more likely to have a positive PCR result than were clinically normal cats, making it likely that FHV-1 was associated with the disease state. Herpesvirus DNA could not be detected in most corneas from cats with sequestra. CLINICAL RELEVANCE: Polymerase chain reaction is a useful clinical test for identifying FHV-1 DNA in cats with conjunctivitis, yielding greater sensitivity over that of current available tests. Herpesvirus may be less of a cause of corneal sequestration in the commonly affected breeds, Himalayan and Persian, than other factors, such as lagophthalmos or corneal metabolic defects.

Acute Disease↗
PubMed1997

Comparison of nested polymerase chain reaction, virus isolation, and fluorescent antibody testing for identifying feline herpesvirus in cats with conjunctivitis.

OBJECTIVE: To compare nested polymerase chain reaction (PCR), virus isolation (VI), and fluorescent antibody (FA) testing to detect feline herpesvirus (FHV) in cats with naturally acquired conjunctivitis or respiratory tract disease, or both. SAMPLES: Swab and microbrush specimens from the conjunctiva and throat were taken from 46 cats, allotted to 3 groups (conjunctivitis only, respiratory tract disease and conjunctivitis, and clinically normal). PROCEDURE: Cells from microbrush specimens were digested and herpesvirus DNA was amplified, using a double round of PCR. Products were detected by use of agarose gel electrophoresis. The VI and FA tests were performed in routine manner. RESULTS: Of 16 cats with conjunctivitis only, conjunctival specimens from 8 and throat specimens from 8 were FHV positive by PCR. None had positive results of VI or FA testing. Of 15 cats with respiratory tract disease and conjunctivitis, conjunctival specimens from 13 and throat specimens from 12 were FHV positive by PCR. A conjunctival specimen from 1 cat and throat specimens from 3 cats were FHV positive by VI. A conjunctival specimen from 1 cat was FHV positive by FA testing. Of 15 clinically normal cats, conjunctival and throat specimens from 2 cats were FHV positive by PCR; neither conjunctival nor throat specimens from these cats were FHV positive by VI or FA testing. CONCLUSION: For cats with respiratory tract disease and conjunctivitis, or with conjunctivitis only, nested PCR was more sensitive at detecting FHV than was VI or FA testing. CLINICAL RELEVANCE: Nested PCR is a more sensitive test than the currently available VI and FA tests for identifying FHV in cats with conjunctivitis.

Animals↗
PubMed1996

Developmental change in spatial grouping activity among children with early focal brain injury: evidence from a modeling task.

Spatial construction skills were assessed in children with left (LH) or right (RH) hemisphere focal brain injury and control children. Children copied simple and complex block models which were rated on accuracy and spatial strategy. The accuracy of simple and complex constructions for 4- to 5-year-old children with LH injury was indistinguishable from 4-year-old controls. However, although they were able to produce accurate complex constructions, the processes used by children with LH injury differed from those of normal children. On both simple and complex constructions, 4- to 5-year-old children with RH injury showed evidence of developmental delay. For both accuracy and process measures, children with RH injury performed at a level comparable to normal children at 3 years. A second group of children with LH and RH injury were tested at 5 to 6 years of age. Both lesion groups were indistinguishable from 4-year-old controls in terms of accuracy. However, both children with LH and RH injury used different spatial processes than did controls. This study emphasizes the importance of distinguishing between products of behavior and the processes which underlie them. It is in the dissociation of products and process of behavior that the subtle spatial construction deficits in this population of brain-injured subjects is revealed.

Brain Injuries↗
PubMed1996

Children's analysis of hierarchical patterns: evidence from a similarity judgment task.

Three experiments in this study examined the development of young children's analysis of spatial patterns, specifically hierarchical letter and geometric forms. In a forced choice task, 4- and 6-year-olds and adult subjects chose one of two choice forms as most similar to a target form. Specific stimulus manipulations were introduced to assess children's ability to segment and integrate hierarchically organized information under different conditions. In Experiment 1 adults served as subjects in a computerized version that provided both choice and response latency data. In Experiments 2 and 3 children and adults participated in a pencil and paper version of the forced choice task. Results showed that although children as young as 4 years of age demonstrated substantial analytic competence, their ability to integrate the parts of the spatial array to form a coherent whole was weaker and more easily disrupted than that of the older children and adults.

Age Factors↗
PubMed1996

The influence of pattern type on children's block design performance.

This study sought to determine what factors contribute to normal developmental changes in performance on the block design task. The target models were systematically varied to emphasize global, intermediate, and local pattern structures. One hundred children between 4.5 and 9 years of age were tested in the first experiment. Correct performance and error types differed significantly as a function of age and pattern type. Broken configuration errors were particularly common for the global patterns. In the second experiment, 48 children between 4.5 and 8 years of age were tested using designs with a superimposed grid (cued condition). Error rates were lower in the cued condition and broken configuration errors were less frequent. These results suggest that children have more difficulty parsing more cohesive patterns, but they can modify their strategies when the square matrix is provided by the pattern structure.

Child↗
PubMed1996

Detection of Toxoplasma gondii in feline and canine biological samples by use of the polymerase chain reaction.

OBJECTIVE: To develop a polymerase chain reaction (PCR) technique to identify Toxoplasma gondii DNA in biological samples from cats and dogs. DESIGN: To artificially create samples that would mimic those acquired in a clinical setting from animals with naturally acquired toxoplasmosis. Using these samples, a PCR test to identify T gondii DNA was developed. SAMPLE POPULATION: Feline and canine aqueous humor, CSF, serum, and blood samples. PROCEDURE: Tachyzoites of several strains of T gondii grown in cell culture were added to feline and canine aqueous humor, CSF, serum, and blood samples. Protocols for identifying T gondii DNA by use of the PCR were developed. RESULTS: The DNA from as few as 10 tachyzoites of T gondii could be identified in feline and canine aqueous humor, CSF, and serum samples. One hundred tachyzoites could be identified in blood samples. CONCLUSIONS: Toxoplasma gondii can be identified in feline and canine biological samples by use of the PCR. CLINICAL RELEVANCE: Correlation of clinical disease to T gondii serum antibodies provides only a presumptive diagnosis of toxoplasmosis. Use of PCR to detect T gondii DNA in biological samples from cats and dogs may provide a sensitive tool for the antemortem diagnosis of toxoplasmosis and may be most beneficial when used in conjunction with serum antibody titers.

Animals↗
PubMed1995

Treatment of cats with ocular disease attributable to herpesvirus infection: 17 cases (1983-1993).

Medical records of 17 cats with ocular disease attributable to herpesvirus injection were reviewed. Herpesvirus infection was confirmed by a positive result on an immunofluorescent antibody test or by detection of dendritic corneal ulcers. Cats were 3 months to 23 years old (mean, 4.8 years). Sex or breed predilections were not evident. Vaccination history was available for 13 cats, 9 of which had been adequately vaccinated against feline viral rhinotracheitis, calici, and panleukopenia viruses. Six cats had a history of respiratory tract disease. Twelve cats were tested for FeLV, and 3 had positive results; 7 cats were tested for feline immunodeficiency virus, with 1 positive result. The most common ocular abnormality seen was conjunctivitis (13/17 cats), followed by dendritic corneal ulcers (10/17 cats). Keratitis was detected in 6 of 17 cats, and nondendritic corneal ulcers in 3 of 17 cats. Corneal sequestra were evident on initial examination or developed during the follow-up period in 4 of 17 cats. Keratoconjunctivitis sicca was diagnosed in 2 of 17 cats, and anterior uveitis was evident in 1 of 17 cats. All cats had 2 or more clinical ocular abnormalities associated with herpesvirus infection. Treatment with topically applied antiviral medications was instituted in 14 cats, including idoxuridine in 7, vidarabine in 4, and trifluridine in 3. Antibiotics were used topically in 10 cats, and atropine was used in 3 cats. Topical administration of corticosteroids was used in 2 cats. Recombinant human alpha-interferon was given orally to 3 cats in conjunction with topical administration of antiviral agents. In addition to medical treatment, 4 cats were treated surgically.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗
PubMed1995

Affective facial expression in infants with focal brain damage.

Children are fluent affective communicators by their first birthday. The development of affective facial expression in infants with focal brain damage thus provides a promising context in which to investigate the developing neural substrates of emotions. We examined both positive and negative affective expression in 12 infants (6-24 months) with pre- or perinatal unilateral focal brain damage (6RHD and 6LHD) and their age- and gender-matched controls. Infants were videotaped in free and semi-structured tasks. Interactions were microanalytically coded, including the use of FACS. Both normal and babies with posterior LHD exhibited the full range of appropriate affective expressions. In contrast, infants with posterior RHD showed marked affective impairment to positive, but not to negative simulation.

Affect↗
PubMed1994

Arterial hypertension associated with topical ocular use of phenylephrine in dogs.

In 3 dogs scheduled for surgical removal of cataracts, systemic and topical treatment with antibiotics and topical ocular treatment with prednisolone, atropine, flurbiprofen, and phenylephrine were used to achieve maximal mydriasis, with minimal risk of pupillary constriction in response to surgery. Each dog developed arterial hypertension, with systolic, diastolic, and mean arterial pressures ranging from 170 to 205, 90 to 112, and 123 to 148 mm of Hg, respectively. Hypertension was treated with acepromazine maleate (0.001 to 0.005 mg/kg of body weight) i.v., decreasing arterial pressures to reference values. Phenylephrine dosages for topical use ranged from 50 to 367 times greater than the i.v. dose required to increase arterial pressure by 50% in anesthetized dogs. Although adverse sequelae to these episodes of hypertension were not noticed, this report documents the uptake of phenylephrine from topical ocular application and suggests the need for dose-response measurements for this adjunct to mydriatic treatment in dogs.

Acepromazine↗
PubMed1994

Tonometry of normal eyes in raptors.

An applanation tonometer was used to estimate intraocular pressure in normal eyes of several species of raptors. No bird had active injury or illness, though some were nonreleasable to the wild because of previous injury. Mean (+/- SD) intraocular pressure was 20.6 (+/- 3.4) mm of Hg in red-tailed hawks (Buteo jamaicensis, n = 10), 20.8 (+/- 2.3) mm of Hg in Swainson's hawks (Buteo swainsoni, n = 6), 21.5 (+/- 3.0) mm of Hg in golden eagles (Aquila chrysaetos, n = 7), 20.6 (+/- 2.0) mm of Hg in bald eagles (Haliaeetus leucocephalus, n = 3), and 10.8 (+/- 3.6) mm of Hg in great horned owls (Bubo virginianus, n = 6). There was no significant difference in intraocular pressure between hawks and eagles. Mean pressure in great horned owls was significantly (P < 0.01) lower than pressure in hawks or eagles. Reliable intraocular pressure readings could not be obtained in barn owls (Tyto alba).

Animals↗
PubMed1993

Infant use of relative motion as information for form: evidence for spatiotemporal integration of complex motion displays.

Previous studies of infants' ability to integrate and to utilize relative motion as information for form in the absence of structural cues have primarily involved motions that are uniform in rate, direction, and path within the form to be constructed. In the present study, we examined infants' ability to integrate relative motion information from motions that are nonuniform along these dimensions, and from this integrative process to construct a coherently rotating two-dimensional form. Infants' ability to integrate nonuniform motion was measured with regard to their ability to discriminate the rotating form from a noncoherent control display containing the same absolute motions. The results showed that discrimination of the coherent and incoherent displays was not demonstrated until 7 months of age. Two additional experiments were conducted to rule out the possibility that this discrimination was based on the detection of local regions of coherence, rather than the perception of the global rotating form. In both experiments, the results did not support discrimination based exclusively on local cues alone. From the combined results of all three experiments, we conclude that infants demonstrate the capacity to integrate the information contained within nonuniform trajectories into a coherent structure by 7 months of age.

Age Factors↗
PubMed1992

Health and economic impact of cigarette smoking in New York State, 1987-1989.

This study provides estimates of deaths attributable to smoking, years of potential life lost (YPLL), and economic costs for each of New York's 57 counties and New York City for the period 1987 to 1989. Results show that in New York State, cigarette smoking was responsible for an average of 30,359 deaths, 409,129 YPLL, and nearly $4 billion in economic costs annually. Overall, smoking-attributable deaths comprised 17.7% of all deaths, or more than the combined total from accidents, AIDS, homicide, and suicide. Findings demonstrate the enormous health and economic burden caused by tobacco use and reinforce the need for policies that discourage smoking, such as increased cigarette taxes, limited smoking in public places, enforcement of youth tobacco access laws, and funding for tobacco education programs.

Adult↗
PubMed1991

Early lexical development in children with focal brain injury.

Early lexical development in 27 children with focal brain injury was studied cross-sectionally and longitudinally. Data were obtained from children between 12 and 35 months of age who acquired their lesion prenatally or within the first 6 months of life. Results for the group as a whole provide clear evidence for delays in lexical comprehension and production, and for a larger number of comprehension/production dissociations than would be expected by chance. In addition, a significant number of children were observed having unusual difficulty mastering predication and/or using an atypically high proportion of closed class words (suggesting reliance on holistic/formulaic speech). Analyses by lesion type revealed no effect of lesion size. Analyses according to side of lesion revealed that children with right-hemisphere damage produced a higher proportion of closed class words, suggesting heavy reliance on well-practiced but under-analyzed speech formulae. Children with left-hemisphere damage were slightly better in comprehension than children with right-hemisphere damage. In addition, left posterior lesions were associated with greater delays in expressive language, and delays were more protracted in children with left posterior damage. No differential effects of left posterior damage were found for lexical comprehension.

Brain Injuries↗