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Biomedical subjects

H J Simon

Publications and source records attributed to H J Simon.

At least 37 records · Page 2Linked to original sources
PubMed1985

Policy issues concerning antimicrobials: problems with the regulatory process governing their introduction.

Clinicians, representatives from industry, and independent observers have voiced complaints about the cumbersome and lengthy process employed by governmental regulatory agencies before approving new antimicrobials for marketing. The currently used drug approval process is probably not entirely appropriate for antimicrobials. In fact, the situation for antimicrobials is qualitatively so different from that of other drugs that antimicrobials should almost certainly undergo review specifically designed in accordance with such differences. Modifications in the pre- and postmarketing approval process for antimicrobials are proposed.

Anti-Bacterial Agents↗
PubMed1984

Perception of temporal differences in speech by "normal-hearing" adults: effects of age and intensity.

Many older people have greater difficulty processing speech at suprathreshold levels than can be explained by standard audiometric configurations. Some of the difficulty may involve the processing of temporal information. Temporal information can signal linguistic distinctions. The voicing distinction, for example, that separates pairs of words such as "rapid" and "rabid" can be signaled by temporal information: longer first vowel and shorter closure characterize "rabid"; shorter vowel and longer closure characterize "rapid." In this study, naturally produced tokens of "rabid" were low-pass filtered at 3500 Hz and edited to create vowel and (silent) closure duration continua. Pure-tone audiograms and speech recognition scores were used to select the ten best-hearing subjects among 50 volunteers over age 55. Randomizations of the stimuli were presented for labeling at intensity levels of 60 and 80 dB HL to this group and to ten normal-hearing volunteers under age 25. Results showed highly significant interactions of age with the temporal factors and with intensity: the older subjects required longer silence durations before reporting "rapid," especially for the shorter vowel durations and for the higher intensity level. These data suggest that age may affect the relative salience of different acoustic cues in speech perception, and that age-related hearing loss may involve deficits in the processing of temporal information, deficits that are not measured by standard audiometry.

Adolescent↗
PubMed1983

Effects of the Islamic Revolution in Iran on medical education: the Shiraz University School of Medicine.

Some consequences of the Islamic Revolution in Iran on medical education were studied utilizing the Shiraz University School of Medicine. Of the 173 full-time faculty employed in 1978, 108 (63 per cent) had left the university by the end of 1982, and 81 (47 per cent) had left the country, aggravating the chronic shortage of medical personnel in Iran. Steps taken by the Iranian authorities to counteract these trends have not proven effective.

Education, Medical↗
PubMed1978

Selective anchoring and adaptation of phonetic and nonphonetic continua.

A series of four experiments compared the effects of unequal probability anchoring and selective adaptation on phonetic and nonphonetic judgments. The basic stimulus series was a synthetic stop consonant continuum ranging from /b/ to /d/. On this continuum were superimposed covariations in fundamental frequency, intensity or vowel. In each experiment subjects listened to identical test tapes under two judgment conditions: place of articulation, and pitch or loudness or vowel judgments. The two types of judgment were significantly dissociated under both anchoring and adaptation paradigms, thus demonstrating that the former may be no less selective than the latter. From this and other evidence, it was concluded that the two paradigms are, in principle, equivalent, and that the main factors in speech adaptation effects are peripheral fatigue and central auditory contrast. If the selective processes of fatigue and contrast are taken to reflect functional channels of analysis rather than the operation of feature detectors, the same broad processes can be seen at work in both speech and nonspeech adaptation.

Adult↗
PubMed1975

Performance of medical students admitted via regular and admission-variance routes.

Twenty-three medical students from socioeconomically disadvantaged backgrounds and drawn chiefly from Chicano and black racial minority groups were granted admission variances to the University of California, San Diego, School of Medicine in 1970 and 1971. This group was compared with 21 regularly admitted junior and senoir medical students with respect to: specific admissions criteria (Medical College Admission Test scores, grade-point average, and college rating score); scores, on Part I of the examinations of the National Board of Medical Examiners (NBME); and performance in at least two of the medicine, surgery, and pediatrics clerkships. The two populations differed markedly on admission. The usual screen would have precluded admission of all but one of the students granted variances. At the end of the second year, average NBME Part I scores again identified two distinct populations, but the average scores of both groups were clearly above the minimum passing level. The groups still differ on analysis of their aggregate performances on the clinical services, but the difference following completion of two of three major clinical clerkships has become the distinction between a "slightly above average" level of performance for the regularly admitted students and an "average" level for students admitted on variances.

Achievement↗
PubMed1970

Microbioassay of antimicrobial agents.

A previously described agar-diffusion technique for microbioassay of antimicrobial agents has been modified to increase sensitivity of the technique and to extend the range of antimicrobial agents to which it is applicable. This microtechnique requires only 0.02 ml of an unknown test sample for assay, and is capable of measuring minute concentrations of antibiotics in buffer, serum, and urine. In some cases, up to a 20-fold increase in sensitivity is gained relative to other published standardized methods and the error of this method is less than +/-5%. Buffer standard curves have been established for this technique, concurrently with serum standard curves, yielding information on antimicrobial serum-binding and demonstrating linearity of the data points compared to the estimated regression line for the microconcentration ranges covered by this technique. This microassay technique is particularly well suited for pediatric research and for other investigations where sample volumes are small and quantitative accuracy is desired. Dilution of clinical samples to attain concentrations falling with the range of this assay makes the technique readily adaptable and suitable for general clinical pharmacological studies. The microassay technique has been standardized in buffer solutions and in normal human serum pools for the following antimicrobials: ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, dicloxacillin, cephaloglycin, cephalexin, cephaloridine, cephalothin, erythromycin, rifamycin amino methyl piperazine, kanamycin, neomycin, streptomycin, colistin, polymyxin B, doxycycline, minocycline, oxytetracycline, tetracycline, and chloramphenicol.

Agar↗
PubMed1970

Penicillinase Studies on L-Phase Variants, G-Phase Variants, and Reverted Strains of Staphylococcus aureus.

L-phase variants and small colony (G-phase) variants derived from penicillinase-producing Staphylococcus aureus strains were tested for penicillinase (beta lactamase) production. A refined variation of the modified Gots test for penicillinase was used to demonstrate penicillinase synthesis. Penicillinase synthesis was reduced in L-phase variants and G-phase variants when compared to parental strains. After reversion of variants to vegetative stages had been induced, revertants were tested for production of penicillinase, coagulase, and alpha hemolysin, mannitol fermentation, and pigment production, and comparisons were made between parent and reverted vegetative forms. All revertants of G-phase variants retained penicillinase activity. Most revertants of L-phase variants showed reduction or loss of penicillinase activity. Retention of coagulase activity, alpha hemolysin production, mannitol fermentation, pigmentation, and phage type varied among revertants.

Journal Article↗