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Biomedical subjects

A C Nichols

Publications and source records attributed to A C Nichols.

At least 19 recordsLinked to original sources
PubMed2000

A chlorodiazirine analog of pentamidine with anti-trypanosomal activity.

A chlorodiazirine derivative of pentamidine was synthesized and tested for anti-trypanosomal activity using EATRO stock 164 trypanosomes in cell culture. Anti-trypanosomal activity was measured as a decrease in [3H]hypoxanthine incorporation by the organisms. The derivative, 3,3'-[1,5-pentanediylbis(oxy-4,1-phenylene)]bis(3-chloro-3H-diazir ine), at a treatment level of 0.1 microM inhibited isotope incorporation by 40-50% compared to nontreated controls. At this concentration, pentamidine inhibited incorporation only 10-15%. The derivative is a nonionic molecule with much different solubility properties than the parent compound and should readily cross the blood-brain barrier.

Animals↗
PubMed1999

Nasalance statistics for two Mexican populations.

OBJECTIVES: This study was undertaken (1) to obtain nasalance statistics for 152 Spanish-speaking normal males and females in three age groups (young children, older children, and adults) from two cities in central Mexico, (2) to determine the reliability of nasalance statistics, and (3) to test whether cities, age group, and/or gender significantly affected nasalance scores. DESIGN/PARTICIPANTS: Randomly selected volunteers, screened for normal speech and hearing, in two middle-class neighborhoods in each city participated. SETTINGS: Measures were made in private homes. MEASURES: Eight nasalance measures were obtained: means, "deviations," maxima, and minima for two sets of sentences; one set that contained no nasals (NN); and another set that included sentences containing several words with nasal sounds (N). RESULTS: Reliability (Cronbach's alpha) of the measures was demonstrated to be very high (0.87 to 0.95). Eight multivariate analyses of variance, one for each type of measure, were performed. Significant differences among subgroups were limited to four: (1) cities differed in their NN means, (2) age groups differed in their NN minima, (3) cities differed in their N minima, and (4) genders differed in their N minima. (Bonferroni adjusted alphas = 0.05).

Adolescent↗
PubMed1993

Anticonvulsant activity of antagonists for the NMDA-associated glycine binding site.

Coupled to the N-methyl-D-aspartate (NMDA) receptor-channel complex is a strychnine-insensitive binding site for glycine. Pharmacological antagonism of glycine binding at this site can produce anticonvulsant activity. Derivatives of the glycine antagonists kynurenic acid and 2-carboxy-indole were synthesized and evaluated for anticonvulsant effects. Compounds were tested in mice against seizures induced by electroshock and pentylenetetrazole, and in the rotorod assay for neurological deficit. The derivatives were also assayed for binding at the NMDA-associated glycine site. The most potent anticonvulsant was ethyl 4-methylamino-5,7-dichloro-2-quinoline carboxylate. This compound provided protection against maximal electroshock (MES) induced seizures at a dose level including 5-fluoro-2-indole carboxylic acid and the diethyl ester of 2,6-pyridine dicarboxylic acid.

Animals↗
PubMed1992

gamma-Hydroxybutyric acid binding sites: interaction with the GABA-benzodiazepine-picrotoxin receptor complex.

The effect of three compounds known to allosterically modulate binding to the GABA/benzodiazepine/picrotoxin receptor complex on 4-hydroxy-2,3 [3H]butyric acid (GHB) binding was investigated. Pentobarbital, pentylenetetrazole, and picrotoxin enhanced [3H]GHB binding in a dose dependent fashion. Pentobarbital enhanced 4-hydroxy-2,3 [3H]butyric acid binding was associated with an increase in Bmax while pentylenetetrazole and picrotoxin altered the affinity of GHB for its binding site producing a decrease in Kd. These findings suggest that the GHB and GABA receptor complex may share certain moieties in common.

Animals↗
PubMed1992

The development of procedures for the measurement of vocal loudness behaviors.

Vocal loudness productions of five similar groups of speakers were analyzed. The groups differed significantly in "comfortable" loudness, in multiples (2x, 4x, and 0.5x) of comfortable loudness, and in ranges (4x -0.5x) of comfortable loudness. Interclass reliabilities for sets of measures were high and highly significant. Implications for the specification of vocal loudness behaviors are discussed.

Adult↗
PubMed1988

Esophageal intelligibility training: back consonants and clusters.

Seven esophageal speakers recorded multiple choice intelligibility lists loaded with words beginning with +BACK consonants and clusters. (A third of the items began with -BACK consonants and clusters). After recording several lists, they played them back and scored them, noting their errors for independent practice. After eight sessions (four weeks) of practice, prepractice and postpractice recordings were randomized and presented to a group of naive listeners. The group scores for the +BACK words improved significantly from prepractice to postpractice (84.1% to 90.6%). The average gain per session for +BACK practice was 0.81%, a result that was in close agreement with prior research. The average gain for the less-practiced -BACK items was 0.46%.

Adult↗
PubMed1987

gamma-Hydroxybutyric acid binding sites: evidence for coupling to a chloride anion channel.

The effect of eight anions, including chloride, on the binding of gamma-hydroxy[2,3-3H]butyric acid (GHB) to synaptosomal membranes of rat and human brain was ascertained, as was the effect of a number of other allosteric modulators of the GABA/benzodiazepine/picrotoxin complex. All ions which were active at the chloride ion channel, inhibited the binding of [3H]GHB in a dose-dependent manner, with maximum inhibition of binding being 60% of 300 mM concentration of anion. Inactive ions in this binding system included sulfate, acetate and fluoride, all impermeable to the chloride ion channel. The inhibition of binding was temperature-dependent, being abolished at 37 degrees C and was independent of the cation used. The binding of [3H]GHB was also enhanced by pentobarbital, picrotoxin and diazepam but unchanged in the presence of GABA, muscimol, bicuculline, baclofen or strychnine. These data raise the possibility that the epileptogenic effect of GHB may be modulated by an action on the chloride ion channel, that is tightly coupled to the GABA/benzodiazepine/picrotoxin and/or GHB receptor complex.

Adult↗
PubMed1986

The vocal tract model of placement: II. Acoustic aspects.

The technique of "placing" the voice in the throat, head, or elsewhere is used in training singers of operatic quality and in vocal rehabilitation. A vocal tract model of placement has been shown to have perceptual validity (Nichols and Shellenberger, 1985). This study tested its acoustic validity. Line spectra of vowels at different vocal placements were analyzed. We found that Formant 2 reflected changes in vocal placement for both male and female speakers.

Humans↗
PubMed1985

A vocal placement model: I. Perceptual aspects.

A study of the perception of vocal placement was carried out to determine if speakers and listeners could agree about the speakers' intents in "placing" productions of vowels and sentences at different locations in the vocal tract. The model tested divided the vocal tract into five volumes from the laryngopharynx to the lips. The results showed that naive listeners, as a group, achieved significant concordance of agreement with the speakers' intents in placement. The speakers were much superior to the naive listeners in a delayed-judgement self-listening task. It was concluded that the vocal tract model has perceptual validity.

Female↗
PubMed1985

Linking standards of care with nursing quality assurance--the SCORE method.

The SCORE method at Braddock General Hospital was designed as a mechanism for ongoing review and evaluation of nursing care as well as a means of facilitating patient care planning and documentation. Staff nurse input in both the development and the ongoing review and evaluation of each standard has provided the system with increased credibility and accountability among the staff nurses. The close link between NSCC and NQAC has provided the nursing department with a mechanism for monitoring the quality and appropriateness of care provided. The standards of care are continuously reviewed, monitored, and evaluated by NQAC. Based on the results of quarterly reports to the nursing administration, NSCC, and the Hospital Departmental QA Committee, revisions to the standards may be made to reflect current nursing practice. Changes in nursing practice may be mandated, or further evaluation of identified problems may be carried out by NQAC. Thus, the SCORE method has provided a comprehensive, ongoing, monitoring mechanism for nursing care as well as a tool through which changes and improvements in nursing care can be made.

Employee Performance Appraisal↗
PubMed1981

Effects of phonetic distance on recognition of synthetic sentences.

Phonetic replacements for the syllable initial consonants and clusters of words in sentences were made according to the scale of phonetic distance devised by Black (Perceptual Differences Between Consonants. Columbus: The Ohio State University, 1974). The impact of such replacements upon the intelligibility of synthetically produced sentences was shown to be substantial. The regression of intelligibility over distance was strong, providing support for the construct validity of Black's scaling.

Female↗
PubMed1981

Equipotentiality of function in dichotic listening.

Listeners who had demonstrated right-ear dichotic listening preference in the first of four listening sessions were randomly assigned to an experimental and control group. Both groups participated in three more dichotic listening sessions. For sessions 2 and 3, left-ear responses were reinforced for the experimental group listeners. There was a significant interaction between groups and sessions. After a drop to equal numbers of right- and left-ear responses in session 2, the control group demonstrated significant right-ear preference in sessions 3 and 4. The responses of the experimental group showed strong left-ear preferences in sessions 2 and 3. Their left-ear gains were preserved in session 4, while their right-ear responses returned to the level demonstrated in session 1. It was concluded that the experimental group had learned to attend to and report left-ear stimuli without loss of right-ear report competence. Within the experimental paradigm, equipotentiality of function has been demonstrated.

Adult↗
PubMed1980

Self-administered intelligibility practice for esophageal speakers.

Eight esophageal speakers used multiple-choice intelligibility training materials in a self-administered practice regimen. "Before" and "after" test tapes were made and scored for intelligibility. A naive group and the speakers themselves served as listeners. Both sets of scores showed proportionally similar improvements in intelligibility.

Aged↗
PubMed1977

Confusions in recognizing phonemes spoken by esophageal speakers III. Terminal consonants and clusters.

A methodology was developed to determine the patterns of phonemic errors that listeners would make in receiving the terminal consonants and clusters of monosyllables spoken by esophageal speakers. Analyses of the features preserved in the errors were performed. The identified phonemic error patterns and the features found to be poorly preserved in the errors were used to structure multiple choice intelligibility practice materials for esophageal speakers.

Adult↗
PubMed1976

Confusions in recognizing phonemes spoken by esophageal speakers: II. Vowels and diphthongs.

A methodology was developed to determine the patterns of phonemic errors that listeners would make in receiving the vowels and dipthongs of monosyllables spoken by esophageal speakers. Analyses of the features preserved in the errors were performed. The identified phonemic error patterns and the features found to be poorly preserved in the errors were used to structure multiple-choice intelligibility practice materials for esophageal speakers.

Adult↗
PubMed1976

Confusions in recognizing phonemes spoken by esophageal speakers: I. initial consonants and clusters.

A methodology was developed to determine the patterns of phonemic errors that listeners would make in receiving the initial consonants and clusters of monosyllables spoken by esophageal speakers. Analyses of the features preserved in the errors were performed. The identified phonemic error patterns and the features found to be poorly preserved in the errors were used to structure multiple-choice intelligibility practice materials for esophageal speakers.

Auditory Perception↗