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Biomedical subjects

J F Feldman

Publications and source records attributed to J F Feldman.

53 records · Page 3Linked to original sources
PubMed1976

Signal processing: from mathematical theory to clinical acceptance or vice-versa?

Signal processing in physiology and medicine hasn't developed as well as one could have hoped in spite of important efforts in research. The bases for present techniques in signal processing are evaluated for the two types of signals encountered in physiology, namely, continuous signals and point processes. It seems that morphological analysis ought to be adapted to the study of continuous physiological signals and that point processes constitute an important form of signals. The principal areas where industrial development can be expected are explored.

Action Potentials↗
PubMed1976

Complementation analysis of linked circadian clock mutants of Neurospora crassa.

A fourth mutant of Neurospora crassa, designated frq-4, has been isolated in which the period length of the circadian conidiation rhythm is shortened to 19. +/- 0.3 hours. This mutant is tightly linked to the three previously isolated frq mutants, and all four map to the right arm of linkage group VII about 10 map units from the centromere. Complementation tests suggest, but do not prove, that all four mutations are allelic, since each of the four mutants is co-dominant with the frq+ allel--i.e., heterokaryons have period lengths intermediate between the mutant and wild-type--and since heterokaryons between pairs of mutants also have period lengths intermediate between those of the two mutants.

Alleles↗
PubMed1975

Circadian periodicity a neurospora: alteration by inhibitors of cyclic AMP phosphodiesterase.

Three methyl xanthine inhibitors of adenosine 3',5'-monophosphate phosphodiesterase-theophylline, aminophyline, and caffeine-lengthen the period of the circadian conidiation rhythm of Neurospora. The effect are seen in wild-type strains and in three mutant strains with genetically altered period lengths. These results suggest the possible involvement of adenosine 3', 5'-monophosphate in the control of circadian rhythmicity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1974

A Direct Comparison between Circadian and Noncircadian Rhythms in Neurospora crassa.

A method has been devised for observing both circadian and noncircadian rhythms in a single wild type strain of Neurospora crassa. This method allows a direct comparison of the properties of the two types of rhythm. The circadian rhythm of conidiation always entrains to a light-dark cycle, damps out in constant light, and has a temperature-compensated period length. The noncircadian rhythm of hyphal branching, expressed by the same strain under different environmental conditions, does not entrain to a light-dark cycle, persists in constant light, and its period length is temperature-dependent. These results suggest that the two rhythms have different underlying mechanisms and demonstrate that the differences in the rhythms previously observed in different strains (patch, band, and clock) are not due to genetic differences between these strains but rather are inherent properties of the rhythms themselves.

Journal Article↗
PubMed1973

Isolation of circadian clock mutants of Neurospora crassa.

Three mutants of Neurospora crassa have been isolated which have altered period lengths of their circadian rhythm of conidiation. The strains, designated "frequency" (frq), were obtained after mutagenesis of the band (bd) strain with N-methyl-N'-nitro-N-nitrosoguanidine. In continuous darkness at 25 degrees bd has a period length of 21.6 +/- 0.5 hours; under the same conditions the period length of frq-1 is 16.5 +/- 0.5 hours; frq-2, 19.3 +/- 0.4 hours; and frq-3, 24.0 +/- 0.4 hours. Each of the mutants segregates as a single nuclear gene. All three mutants appear very tightly linked to each other, but it has not yet been determined whether the mutants are allelic. No major changes in the responses to light and temperature have been observed in any of the mutants. It is suggested that these mutants represent alterations in the basic timing mechanism of the circadian clock of Neurospora.

Alleles↗
PubMedDate not supplied

Sexual activity level and sexual functioning in women prenatally exposed to diethylstilbestrol.

Thirty women with a history of prenatal exposure to diethylstilbestrol (DES) underwent a detailed sexual history and were compared to a demographically similar sample of 30 women with a history of an abnormal Pap smear. The DES women were found to have less well-established sex-partner relationships and less experience with child-bearing, to be lower in sexual desire and enjoyment, sexual excitability, and orgasmic coital functioning, but to be comparable (and low) with regard to such sexual dysfunctions as vaginismus and dyspareunia. Both potential psychosocial and neuroendocrine explanations are discussed.

Adult↗
PubMedDate not supplied

Psychopathology in prenatally DES-exposed females: current and lifetime adjustment.

This report concerns the long-term effects of prenatal exposure to diethylstilbestrol (DES) on overall psychologic functioning in females. Thirty DES-exposed women aged 17-30 years and 30 control women with a history of abnormal Pap smear findings were interviewed with the SADS-L and completed the SCL-90-R and the PRI-Q. Both DES and PAP women showed elevated symptoms on the SCL-90-R in comparison to published norms and were similar to women with cancer, but their rates of psychiatric disorders (SADS-L/RDC) at the time of the evaluation did not differ from community norms. However, both groups met criteria for Major Depressive Disorder (lifetime) significantly above expectancy, and the DES women reported slightly more episodes than the control group. The DES women also had significantly more problems than the PAP control group in social relations with spouses and other significant persons.

Adolescent↗
PubMedDate not supplied

Psychopathology and social functioning in men prenatally exposed to diethylstilbestrol (DES).

Previous research has suggested increased psychopathology in prenatally diethylstilbestrol (DES)-exposed persons. The current study compares the psychiatric histories and social functioning of 27 men with a history of high-dose prenatal DES exposure and their unexposed brothers. We expected DES subjects to show greater lifetime psychopathology and poorer social functioning than controls. Both groups showed high rates of lifetime depression, lifetime alcoholism, and current psychiatric symptoms in excess of community norms. The only diagnosis on which DES subjects exceeded their unexposed brothers was Major Depressive Disorder (MDD). DES-exposed men had almost twice the prevalence of at least one episode of MDD and had significantly more recurrent episodes. The relatively small number of subjects with concomitant lack of statistical power may have contributed to the difficulty obtaining significant effects.

Adult↗
PubMedDate not supplied

Modifying the distribution of attention in infants.

In three experiments, the distribution and malleability of infant visual attention were studied in 5-month-olds (N = 72) while they inspected large geometric designs. In Experiment 1, we established that infants maintained their distribution of attention from a pretest to a familiarization phase. We also replicated and extended our previous findings that infants who examined targets with briefer, more numerous looks and shifts-short lookers-had novelty scores above chance, whereas long lookers demonstrated chance responding. In Experiment 2, different portions of the display were successively illuminated with red light. This manipulation induced long lookers to scan like short lookers during familiarization; they then showed novelty scores well above chance. A third experiment ruled out the simple presence of a red light as the source of this effect. In sum, then, these results suggest that the distribution of attention is malleable, and that a broader distribution of attention, as reflected in briefer and more numerous looks and shifts, can improve processing.

Attention↗
PubMedDate not supplied

Visual and auditory temporal processing, cross-modal transfer, and reading.

The present study reexamined the relevance of auditory and visual cross-modal matching to reading ability, an issue first addressed in a seminal study by Birch and Belmont (1964). By presenting all patterns to be matched as temporal sequences of tones and lights, including intramodal as well as cross-modal conditions, and covarying memory, three problems with the Birch and Belmont design were corrected. Results showed that poor readers had difficulty in perceiving temporal patterns generally: They did worse than good readers not only on cross-modal conditions but also on intramodal ones. These results were replicated in two tasks. Nonetheless, hierarchical regressions provided some indication that cross-modal abilities themselves are relevant to reading. For one of the two tasks, cross-modal performance contributed to the prediction of reading ability over and above intramodal performance. Poor readers also showed slower response times--a factor that contributed marginally to the prediction of reading independent of temporal processing.

Auditory Perception↗