Biomedical subjects

R Urbano

Publications and source records attributed to R Urbano.

10 recordsLinked to original sources

PubMed1995

Influence of host genotype on progression to acquired immunodeficiency syndrome among children infected with human immunodeficiency virus type 1.

OBJECTIVE: To study the role of host genotype in pediatric infection with human immunodeficiency virus type 1 (HIV-1) and progression to acquired immunodeficiency syndrome (AIDS). METHODS: Human leukocyte antigen (HLA) class II and complement C4 genotypes were determined by means of molecular genetic techniques for 243 black children born to HIV-1-infected mothers in New York City and San Francisco. Survival, cumulative incidences of opportunistic infections and encephalopathy, and rates of CD4+ T cell decline were compared in children of different genotypes. RESULTS: Among HIV-1-infected children, the HLA-DR3 haplotype (DRB1*0301-DQA1*0501-DQB1*0201) was associated with increased incidence of encephalopathy, faster rate of CD4+ cell decline, and death before 2 years of age. Deletion of the C4A gene was independently associated with increased incidences of encephalopathy and early death. DPB1*0101 was associated with survival to at least 2 years of age. The presence of DQB1*0604 was associated with increased risk of HIV infection. CONCLUSIONS: These results are consistent with previously reported associations between HLA genotypes and faster progression to AIDS among HIV-infected adults. The DR3 haplotype and C4A deletion may reflect the same underlying mechanism of susceptibility in that the DR3 haplotype is in linkage disequilibrium with other C4A null alleles. In addition, the class II locus DPB1 may have an independent effect on survival.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Optimization of automated hearing test algorithms: simulations using an infant response model.

Computer simulation was used to evaluate several parameters of an automated hearing test algorithm in an attempt to optimize the algorithm for accuracy and efficiency. An infant response model was developed to guide the simulations. Test parameters of interest were starting intensity and stopping rule and their interaction with a measure that is thought to emulate infant reliability, probability of task orientation. Results indicated that stopping rule, within the ranges investigated, had little effect on accuracy but had major impact on efficiency. Starting intensity interacted with the hearing status of pseudosubjects in influencing accuracy. Accuracy was most influenced by probability of task orientation. The simulated test data are compared to data from infants and young children in the accompanying article so that the response model can be evaluated.

Algorithms↗

PubMed1991

Optimization of automated hearing test algorithms: a comparison of data from simulations and young children.

A five-up, five-down automated staircase procedure was used to explore the effects of variable starting and stopping rules as they interact with infant behavior in influencing the accuracy and efficiency of infant auditory threshold testing. Results from 146 infants were compared to results from computer simulations (see accompanying article) in order to evaluate an infant response model used in the simulations. Results indicate that the automated procedure successfully discriminated between infants with normal versus abnormal tympanograms. In addition, the model accurately predicted infant results in terms of the effects of starting and stopping rules. The model was less useful in predicting the relationship between minimum response levels and false positive rates.

Algorithms↗

PubMed1991

The stop/glide boundary shift: modelling perceptual data.

Research in speech perception has suggested that listeners often adjust category boundary locations for differing contexts. The stop/glide (e.g.,/ba/vs./wa/) boundary shift occurring with changes in syllable duration has been interpreted as reflecting 'rate normalization' by some, whereas others have suggested an auditory basis for the shift. Clarification of both the causes and the effects of the stop/glide shift is being sought through experimentation intended to expand our knowledge of variations in the shift across different experimental treatments. The present study extends research on the stop/glide shift by (1) showing that the shift is not an artifact of a particular stimulus pattern that had been present in all the previous studies of the effect, (2) further demonstrating the nonlinear character of the identification shift, (3) providing additional evidence of the role of presentation format (mixed vs. blocked) in the identification shift, and (4) exploring boundary locations in various discrimination paradigms. The complex outcomes of the studies reported here as well as a variety of previous results are interpreted as compatible with expanded versions of the durational contrast hypothesis. Two versions are considered, one in which the shift is seen as due to a mechanism of contrastive perception that applies to events of comparable duration, and one in which the shift is seen as a perceptual error that occurs when the auditory system attempts to track frequency trajectories that change (i.e., pivot) over time.

Adult↗

PubMed1989

The effects of vocoder filter configuration on tactual perception of speech.

Perception of synthetic speech continua through the sense of touch and audition was compared utilizing a 32-channel spectrally-oriented electrocutaneous vocoder display and standard auditory psychophysical procedures. Perception of a consonantal and a vocalic continuum was evaluated utilizing three vocoder filter configurations: logarithmic, linear, and average (geometric mean of logarithmic and linear). Results indicated a close correspondence between tactual and auditory discrimination and identification for the vowel (/a/-/e/) and the consonant (/sta/-/sa/) continuum regardless of the filter characteristics.

Deafness↗

PubMed1989

Conflicting and cooperating cues: perception of cues to final consonant voicing by infants and adults.

Three experiments were conducted to ascertain the relative salience of two cues for final consonant voicing in infants and adults. Experiment 1 was designed to investigate infant perception of periodicity of burst, vowel duration, and the two cues combined in a cooperating pattern. Experiment 2 was designed to examine infant perception of these same cues but in a conflicting pattern, that is, with extended duration associated with the voiceless final plosive. Experiment 3 examined perception of the stimuli from Experiments 1 and 2 with adult subjects. Results indicate that in both adults and infants combined cues facilitate discrimination of the phonemic contrast regardless of whether the cues cooperate or conflict. The three experiments taken together do not support a phonetic interpretation of conflicting/cooperating cues for the perception of final stop consonant voicing. Potential psychoacoustic explanations are discussed.

Adult↗

PubMed1988

Similarities between tactual and auditory speech perception.

Perception of synthetic speech continua through the sense of touch and audition was compared utilizing a 32-channel spectrally oriented electrocutaneous display and standard auditory psychophysical procedures. Results indicated a close correspondence between tactual and auditory discrimination and identification for a vowel (/a/-/e/) and a consonant (/sta/-/sa/) continuum. These results suggest that at least some aspects of speech perception are amodal.

Humans↗

PubMed1984

Public school satisfaction with interdisciplinary services.

Representatives from local, regional, and state educational agencies throughout the country were surveyed to determine their satisfaction with services provided by University Affiliated Programs (UAPs). Sixty-eight respondents from 26 states and the District of Columbia returned questionnaires indicating their assessment of UAP services. Overall results showed highly positive ratings regarding access to UAP services, interdisciplinary evaluations, comprehensiveness, and relevancy of written reports and in-service training activities.

Consumer Behavior↗

PubMed1982

Status of interagency cooperation between interdisciplinary clinics or hospitals and the public schools.

Since public schools are now mandated to provide a large and varied range of clinical services to handicapped school children, a survey was conducted of 26 interdisciplinary UAF clinics and hospitals in regard to the types of services which they offer to public school children and the extent in which coordination of such services has been developed. Results suggest that diagnosis of evaluation is the primary reason for referral but that a wide variety of community outreach services are both requested by the schools and offered by interdisciplinary hospital and clinic staff. These services are described and the implications for future interagency cooperation are discussed.

Child↗

PubMed1980

Identifying children with school learning and behavior problems served by interdisciplinary clinics and hospitals.

Questionnaires were sent to interdisciplinary UAF programs across the country to assess the types of handicapped school children who were receiving services at their facilities. A return rate of 65 percent was obtained and the total sample of children was 2088. Results indicated that a wide variety of ages and handicapping conditions were reported. Referral sources and services rendered were analyzed, and implications for cooperation with public school personnel were discussed.

Adolescent↗