Biomedical subjects
M Sigman
Publications and source records attributed to M Sigman.
Vocal output in preterm infants.
Data on vocal output of 51 preterm infants and 16 term infants were obtained during naturalistic home observations at 1, 3, and 8 months; during the administration of a preference-for-novelty paradigm in the laboratory at 8 months; and by the administration of the Gesell Developmental Schedules at 9 months. Preterm and term infant groups were found to show both similarities and differences: both groups vocalized a similar amount in the preference-for-novelty situation; both groups earned similar scores on the language subtest of the Gesell; both groups increased the percentage of awake time they spent in nondistress vocalization from 1 to 8 months. Term infants showed an earlier increase than did preterm infants: term infants significantly increased during the 1-3 month period, whereas preterm infants only increased significantly during the 3-8 month period. The developmental differences suggest a link between vocal output and perinatal conditions in that caregiver behavior was not found to be different among groups. Within the preterm groups, some relationships were found between vocal output and later test performance: infants who vocalized more during mutual gazing with the mother earned significantly higher scores on the language subtest of the Gesell.
Neurological organization and visual fixation in infants at 40 weeks conceptional age.
Neurological organization and visual fixation were found to be unrelated in a group of premature infants tested at their term date. These results are discrepant with those obtained with a sample of full term infants. Separate comparisons made of the neurological and fixation data revealed one significant group difference from the fixation data; all other analyses were nonsignificant. The discrepant findings may have occurred because prematures are subject to developmental disparities in the regulation of arousal, neuromuscular, and visual systems due to differential impact of preterm extrauterine life.
Visual preferences of four-month-old premature and full-term infants.
Explore the source record for details and available documents.
Visual attention and neurological organization in neonates.
Explore the source record for details and available documents.
Ordinality and sensory-motor series.
Explore the source record for details and available documents.
Helping mothers discuss sexuality and AIDS with adolescents.
The current study was designed to alter experimentally mothers' style when discussing sexuality and AIDS with their adolescent children. Mothers of 11- to 15-year-olds (N = 50) were assigned to an intervention or control group, resulting in 20 dyads in each group. All dyads were assessed twice, on self-reported and observed communication, AIDS knowledge, and perceived vulnerability to AIDS. Intervention group mothers received two training sessions. Observational data revealed that intervention group mothers reduced their amount of speaking, asked more open-ended questions, acted less judgmental, and discussed dating and sexuality more than did control group mothers. Intervention group adolescents reported increased discussions of birth control and increased daily comfort talking to their mothers. There was some evidence that intervention group girls increased in AIDS knowledge. There was no change in AIDS-related beliefs.
Transmembrane versus soluble stem cell factor expression in human testis.
The interaction between stem cell factor (SCF), a ligand produced by Sertoli cells, and its c-kit receptor on germ cells is necessary for successful spermatogenesis in animal models. SCF can be alternatively spliced into soluble and transmembrane forms, and it is the transmembrane form that is required for spermatogenesis in rodents. c-Kit receptors are also present on Leydig cells, and soluble SCF has been implicated in the regulation of testosterone production. This study had two goals: To test the hypothesis that the extent of germ cell production in human males is correlated with the expression of transmembrane SCF, and to examine the relationship between testosterone production and the expression of soluble SCF in humans. Reverse transcriptase polymerase chain reaction was used to determine the ratio of transmembrane-to-soluble SCF in testicular tissue. Clinical analysis, hormonal measurements, and histological methods were used to evaluate the causes of infertility and to seek correlations with the pattern of SCF expression. SCF was preferentially expressed as the transmembrane type in all testicular samples, regardless of the state of germ cell production. Furthermore, the percent of transmembrane SCF expression was independent of clinical and histopathological diagnosis (r(s) = 0.111, n = 28) and unrelated to the extent of spermatogenesis. This contrasts with rat models of testicular injury that exhibit a decreased proportion of transmembrane SCF with atrophy. A significant correlation (r(s) = 0.665, P < .02, n = 16) was found between testosterone levels and percent soluble SCF, which suggests that, in humans, there may be a regulatory interaction between soluble SCF and testosterone.