Biomedical subjects
Publications and source records attributed to J F Peters.
"Canadian families are pluralistic and varied, with a mix of traditional, modern, and post-modern characteristics. This paper looks at families into the immediate future.... Consideration is given to ethnicity, cohabitation, fertility, childrearing, sexuality, family policy, adolescence, and general family life. The state will continue to influence family life. Non-familial associations will affect family values and activity."
While gender socialization and practice have been investigated in education, work, and children within the family, there has been minimal research on adolescents and parents. The present research focused on male and female adolescents' perceptions of their mothers' and fathers' behavior in six common family routines: allowances, gifts, use of the family car, curfew, and chores inside and outside the home. Data were gathered from 448 senior high school students, Gender-equal behavior toward sons and daughters was clearly evident in the parental practice of allowances and gift giving, and less evident in permission to use the family car. Traditional behavior was strongly evident in sons' performing outside chores and, to a lesser degree, in daughters' keeping an earlier curfew and doing more inside chores. Fathers were more traditional than mothers in allowance and gift giving to sons, and less traditional than mothers in giving sons permission to use the car. It is evident from the perspective of the teenager, that stereotypical gender roles are being perpetuated in North American home life.
This study explored adolescent gender differences in possessions and parental financial assistance. Eight common adolescent possessions were analyzed, as well as expected parental contributions to their children's postsecondary education. The issues of gender inequality in the home and gender differences in the process of adolescent independence are addressed.
The chromosomal fragile-site mapping to Xq27.3 is associated with a frequent form of mental retardation and is prone to breakage after induced deoxyribonucleotide pool perturbation. The human hypoxanthine phosphoribosyltransferase (HPRT) and glucose-6-phosphate dehydrogenase (G6PD) genes flank the fragile X chromosome site and can be used to monitor integrity of the site in human-hamster somatic cell hybrids deficient in the rodent forms of these activities. After induction of the fragile X site, negative selection for HPRT and positive enrichment for G6PD resulted in 31 independent colonies of HPRT-,G6PD+ phenotype. Southern blot analysis demonstrated the loss of all tested markers proximal to the fragile X site with retention of all tested human Xq28 loci in a majority of the hybrids. In situ hybridization with a human-specific probe demonstrated the translocation of a small amount of human DNA to rodent chromosomes in these hybrids, suggesting chromosome breakage at the fragile X site and the subsequent translocation of Xq28. Southern blot hybridization of hybrid-cell DNA, resolved by pulsed-field gel electrophoresis, for human-specific repetitive sequences revealed abundant CpG-islands within Xq28, consistent with its known gene density. The electrophoretic banding patterns of human DNA among the hybrids were remarkably consistent, suggesting that fragile X site breakage is limited to a relatively small region in Xq27-28. These somatic cell hybrids, containing Xq27.3-qter as the sole human DNA, will aid the search for DNA associated with the fragile X site and will augment the high resolution genomic analysis of Xq28, including the identification of candidate genes for genetic-disease loci mapping to this region.
This article reviews the basic concepts underlying the balance system, describes the information provided by dynamic posturography, and explains how the technique complements and expands on the information provided by traditional tests of vestibular function.
Fragile X syndrome is a common form of mental retardation associated with a fragile site on the human X chromosome. Although fragility at this site is usually evident as a nonstaining chromatid gap, it remains unclear whether or not actual chromosomal breakage occurs. By means of somatic cell hybrids containing either a normal human X or a fragile X chromosome and utilizing two genes that flank the fragile site as markers of chromosome integrity, segregation of these markers was shown to be more frequent if they encompass the fragile site under appropriate culture conditions. Hybrid cells that reveal marker segregation were found to contain rearranged X chromosomes involving the region at or near the fragile site, thus demonstrating true chromosomal breakage within this area. Two independent translocation chromosomes were identified involving a rodent chromosome joined to the human X at the location of the fragile site. DNA analysis of closely linked, flanking loci was consistent with the position of the breakpoint being at or very near the fragile X site. Fragility at the translocation junctions was observed in both hybrids, but at significantly lower frequencies than that seen in the intact X of the parental hybrid. This observation suggests that the human portion of the junctional DNA may contain part of a repeated fragility sequence. Since the translocation junctions join heterologous DNA, the molecular cloning of the fragile X sequence should now be possible.
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Some of the functions and dysfunctions of youth employment in contemporary society are discussed. The focus then shifts to a third variable: family dynamics. The research indicates that youth unemployment prolongs residence with parents. The younger the youth, the more tolerant are the parents of the unemployment. It was also found that a daughter's lack of employment in the summer months is more acceptable than a son's; that debts are part of the lifestyle of youth after age 18; that males incur more debts than do females; and that parents are the major source of financial loans.
The rhythms in pineal N-acetyltransferase (NAT) activity and melatonin levels were studied in the diurnally active Mexican ground squirrel and Eastern chipmunk. In the ground squirrel, both NAT activity and melatonin levels exhibited a marked nocturnal rise; these increases were not prevented by the exposure of these animals to a light irradiance of 200 microW/cm2 throughout the night. In the Eastern chipmunk, darkness at night was also associated with a marked rise in both the activity of the acetylating enzyme as well as the levels of melatonin. Again, these rhythms were not suppressed by the exposure of these animals to a light irradiance of 200 microW/cm2 for either 1 night or for 7 nights; exposure of chipmunks to light for 7 consecutive days did, however, reduce the rise in melatonin normally associated with darkness. The non-suppressibility of pineal NAT and melatonin by a 200 microW/cm2 light irradiance may relate either to the activity pattern of these animals, i.e., diurnal, or to their previous lighting history.
Respiratory pauses (3-10 sec in duration), apnea (less than 10 sex in duration), and periodic respiration observed in thoracic respirograms were measured in 226 polysomnograms obtained on 17 normal infants during the first year of life. All subjects had one or more respiratory pauses in a majority of recordings; 35% had respiratory pauses in all recordings; 75% of respiratory pauses were associated with body movement. There is marked intersubject and even intrasubject variability in respiratory pause rates. The range of mean respiratory pause rates among subjects was 2.0 - 14.4/h, and for single recordings was 0.0 - 43.6/h. Their occurrence was directly related to the occurrence of periodic respiration. Rates were higher during REM and indeterminate sleep than during slow wave sleep. There was no significant trend toward increase or decrease in respiratory pause rate during the first year post term. Apnea occurred in only one of the 226 recordings (0.4%). Periodic respiration occurred in 8 of 17 subjects (47%), and in 25 of 226 recordings (11%). Its occurrence was unrelated to sleep stage. The following conclusions are considered valid on the basis of the data presented and reports in the literature: (1) Rates of respiratory interruption are higher before than after 40 weeks conceptional age. (2) There is considerable intersubject variability in rates of respiratory interruptions. (3) Respiratory pauses are common during sleep in normal human infants. (4) Respiratory pauses occur more frequently with movements than in their absence. (5) Respiratory pause rates are higher during REM sleep than during slow wave sleep. (6) Apneas of greater than 10-15 sec duration do occur in normal infants, but are rare. From the clinical viewpoint, respiratory pauses (less than 15 sec) of the central type, regardless of abundance, and periodic respiration cannot by themselves be used as evidence that a baby is at risk of anything. The occurrence of apneas (greater than 15 sec duration), especially if any are of the obstructive or mixed types (and perhaps respiratory pauses of the obstructive and mixed types), and/or if associated with bradycardia or decrease in oxygen saturation, indicate sleep apnea syndrome and suggest risk of sudden infant death.
RMS measurements of amplitude symmetry were calculated for samples of typical active and quiet sleep periods in 12 normal full term, 5 premature and 7 Trisomy-21 infants from recordings obtained at 1, 4, 12 26 and 52 weeks post term. The frequency distributions of the symmetry data for each group did not deviate significantly from the expected normal distributions. The mean symmetry ratios were not significantly different among the 3 groups. It was concluded that the EEGs of the 3 groups are characterized by amplitude symmetry in the first year of life. The possibility that symmetry data may be used for classification of abnormal EEGs was discussed.
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Long daytime EEG-polygraph recordings were obtained at 36, 38, and 40 weeks conceptional age, weekly thereafter for 12 weeks, and at 26 and 52 weeks post term in 5 infants born at 30--33 weeks gestation. The babies have developed normally for 18--38 months. All 74 EEGs were normal for age. Derived data were compared with similar data from 17 normal full-term infants. The tracé alternant pattern disappeared earlier in the premature than in the control group (mean ages 21.4 vs. 33.4 days post appeared earlier in the premature group (mean ages 35.4 vs. 43.8 days; P < 0.05). There were no age differences between the groups with respect to (1) the shift from active sleep onset to quiet sleep onset, (2) active sleep and quiet sleep as percentages of total sleep time, or (3) disappearance of frontal sharp waves. Overall attainment of "infantile" EEG sleep patterns occurred at 35--60 days post term (mean 43.8) for the permature group and at 27--66 days (mean 46.4) for the full-term group (difference not significant). These findings indicate that no significant errors will be made in clinical practice by applying the same maturational criteria to the post-term EEGs of prematures as to the EEGs of full-term infants.
EEG polygraph recordings of 1 to over 4 h duration were obtained during daytime sleeps weekly from birth to 11-13 weeks of age in 17 normal full-term newborns. Analysis of the recordings permitted more precise specification of the time courses of early developmental changes in EEG patterns related to the sleep cycle. The tracé alternant pattern of quiet sleep was seen up to 2 weeks post term in all subjects, but in none beyond 6 weeks. Active sleep onset occurred in 80% of daytime sleeps at 1-3 weeks and decreased rapidly over the next 5 weeks, but at 8-13 weeks was still seen in 5-10% of the recordings. Rolandic sleep spindle bursts appeared in some subjects as early as 4 weeks post term and were present in all beyond 8 weeks. Based upon these 3 criterion variables, the transition from 'perinatal' to 'infantile' EEG sleep patterns started at a mean age of 30.3 days and was completed at a mean age of 46.6.days. The earliest and latest completions of the transition were at 27 and 66 days, respectively. On the average the transition took just over 2 weeks. Frontal sleep transients were seen until 3 weeks post term in all subjects, but in none beyond 7 weeks. Active sleep decreased from just over 50% of total sleep time at birth to about 20% beyond 8 weeks. Percent-time quiet sleep increased proportionately. Indeterminate sleep remained relatively constant at 5-10 percent-time. A tendency for percent-time indeterminate sleep to be elevated in the presences of minor illnesses was observed. The usefulness of these, and other, EEG data in defining mature and immature EEGs in the neonatal period and the clinical significance of EEG immaturity are discussed.
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Cross correlations between 4 homologous pairs of ear-reference derivations were calculated for 45-sec digitized samples of typical active and quiet sleep in 19 selected normal newborns at 21--70 h after term birth. Repeat recordings were obtained in 9 subjects 24 h after the original recordings and another set of cross correlations was calculated. For comparison, similar recordings were obtained from 4 asymptomatic young adults and cross correlations were calculated for 45-sec samples of typical stage 4 and stage REM sleep and for stage W both before and after sleep. Mean cross-correlation coefficients at zero time lag were generally higher for the adult sleep data than for the newborn data, but the differences were smaller than had been anticipated. The coefficients for active sleep data in the newborns were higher than for quiet sleep data, while in the adults the coefficients were higher for stage 4 than for stage REM. Coefficients were higher for convexity derivations than for temporal derivations in both newborns and adults. A review of the small available literature suggests that recording and analysis techniques may be significant variables determining the results obtained in such studies. The cross-correlation method of measuring interhemispheric synchrony may prove useful in identifying brain disorders in the postnatal period.
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