Accountability: assessing student outcomes for budget dollars.
Explore the source record for details and available documents.
Education, Graduate↗
Biomedical subjects
J D Skinner
Publications and source records attributed to J D Skinner.
Estimation of iron bioavailability in adolescents' meals and snacks.
Dietary iron bioavailability was calculated from 24-hour food records of 224 adolescents. Eating patterns related to high iron bioavailability were identified. Indicators of dietary iron adequacy calculated in this study were the amount of total iron, the amount of available iron, and the percent bioavailability. Mean daily iron intakes were 16.1 mg for boys and 11.1 mg for girls. Estimation of daily iron bioavailability showed that mean available iron from boys' diets, 1.38 mg, and from girls' diets, 0.91 mg, was not only below recommended levels but also below 10% bioavailability, the basis of the RDA for iron. Diets that met recommended levels of available iron had unusually high amounts of energy, ascorbic acid, and animal tissue foods. Patterns of iron bioavailability differed among eating occasions but were similar for boys and girls. The breakfast meal was lowest in the three indicators of dietary iron adequacy; the evening meal was highest. Snacks contributed substantial amounts of food energy but little available iron to the adolescents' diets. If, at each eating occasion, adolescents include foods that enhance iron absorption and foods that are rich in iron, they will increase amounts of available iron in their diets.
Adolescent↗
Two human repetitive DNA elements: a new interspersed repeat found in the factor IX gene, and a satellite 11 tandem repeat sequence.
Explore the source record for details and available documents.
DNA↗
Reproductive biology of the male Cape porcupine, Hystrix africaeaustralis.
The reproductive tract of the male Cape porcupine is morphologically and histologically similar to that of New World hystricomorph rodents. Males are reproductively active throughout the year and attained sexual maturity (complete spermatogenesis) at an age of 8-18 months. Testes weight, epididymides weight and seminiferous tubule diameter attained asymptotic values at the age of 23-30 months. A tendency towards seasonality in the activity of accessory glands, preceded and accompanied by an increase in circulating plasma testosterone values, may be considered as a factor enforcing seasonal breeding in females. Testosterone concentrations in pubertal males were significantly higher than those recorded in sexually mature males.
Animals↗
Functional anatomy of the ovaries of pregnant and lactating Cape porcupines, Hystrix africaeaustralis.
The constituent cell types of the ovary of the porcupine were similar to those of New World hystricomorph rodents and accessory corpora lutea and luteal bodies were formed through the luteinization of the membrana granulosa or theca interna of antral follicles. All luteal bodies were histologically similar. The total volume of luteal tissue per female was not affected by fetal age and was unrelated to circulating concentrations of maternal plasma progesterone. Maternal plasma progesterone concentrations were correlated with fetal age. Follicular activity occurred throughout pregnancy but was not affected by fetal age or related to circulating values of oestradiol-17 beta. The formation of accessory corpora lutea during pregnancy is regarded as important in supplementing progesterone during pregnancy.
Animals↗
Adrenal and gonadal contribution to circulating androgens in spotted hyaenas (Crocuta crocuta) as revealed by LHRH, hCG and ACTH stimulation.
Single venous blood samples were collected from 52 hyaenas and serial samples via indwelling jugular catheters from 8 hyaenas. Social status of the hyaenas was unknown. Radioimmunoassay estimations were specific for testosterone, androstenedione, cortisol and LH. No significant differences could be found between the sexes for concentrations of testosterone (adult males 2.9 +/- 1.3 nmol/l; adult females (non-pregnant) 1.6 +/- 0.3 nmol/l). Androstenedione concentrations in sub-adult males were significantly lower than those in females (2.3 +/- 0.05 and 5.5 +/- 1.2 nmol/l). Testosterone and androstenedione concentrations were significantly higher in parous pregnant than in parous non-pregnant females (4.3 +/- 1.4 and 1.6 +/- 0.3; and 23.7 +/- 11.6 and 6.7 +/- 0.9 nmol/l respectively). Both LHRH and hCG elicited elevated androgen concentrations in females in different reproductive categories. Androgens are produced by the ovary in the absence of follicular or luteal structures, indicating androgen production by the interstitial tissue of the ovarian stroma.
Adrenal Glands↗
Nutrient intakes and foods selected by college students: comparisons among subgroups divided by energy intake.
Food consumption patterns of college students, divided into subgroups of men (no. = 58), women with mean energy intakes greater than 1,200 kcal (no. = 192), and women consuming less than 1,200 kcal (no. = 53), were studied using 3-day food records. Patterns of nutrient intakes, eating frequency, and types of food eaten differed among subgroups. Women with less than 1,200 kcal had lower intakes of protein, carbohydrate, fat, calcium, iron, thiamin, riboflavin, and niacin; they ate less frequently; and they ate less meat and eggs, legumes, bread, cooked starchy vegetables, milk products, desserts, added fat, and added sugar than did men and women whose mean energy intakes exceeded 1,200 kcal. There were differences between the latter two groups for 10 nutrients and for intakes of fluid milk, meat and eggs, legumes, bread, cooked starchy vegetables, alcoholic beverages, and noncarbonated, sweetened beverages. Diets of men met the RDAs for all nutrients calculated, and diets of women whose intakes exceeded 1,200 kcal met all RDAs except that for iron. Group mean intakes of women with less than 1,200 kcal did not meet the RDAs for calcium, iron, thiamin, riboflavin, and niacin. However, the subgroup with intakes less than 1,200 kcal consumed food of greater nutrient density than did other college students.
Adult↗
Appalachian adolescents' eating patterns and nutrient intakes.
Meal and snack patterns of 114 male and 111 female adolescents in a southern Appalachian state were examined from 24-hour food records kept on a school day. Breakfast was skipped by 34% of the respondents, and 27% either skipped lunch or ate a snack-type lunch. The evening meal and snacks, each of which contributed about one-third of the daily energy intake, were eaten by 94% and 89%, respectively. Girls' mean intakes of vitamin A, calcium, and iron were low at all eating occasions throughout the day. Boys' mean intakes of iron were low at breakfast, lunch, and snacks; their vitamin A intakes were low at lunch and snacks. Adolescents who prepared their own breakfasts consumed less energy, protein, fat, and niacin at that meal than did adolescents who ate breakfasts prepared by their mothers. However, adolescent-prepared breakfasts were higher in nutrient density for calcium, riboflavin, and thiamin. Evening meals prepared by adolescents were similar in total nutrient content to meals prepared by their mothers but lower in nutrient density for iron and thiamin. Evening meals prepared by adolescents were more likely to include a sandwich and less likely to include a vegetable than were meals prepared by mothers.
Adolescent↗
Appalachian adolescents' snack patterns: morning, afternoon, and evening snacks.
The snack patterns of 225 adolescents selected from four metropolitan and three rural schools in eastern Tennessee were examined with the use of 24-hour food records kept on a school day. Most (89%) of the respondents ate at least one snack on the day of the survey. Morning snacks, most of which were obtained from school stores or school vending machines, were more likely to include candies and salty snack foods than were afternoon and evening snacks, most of which were eaten at home. Breads and cereals were popular choices for afternoon and evening snacks. Carbonated beverages and desserts were popular during all time periods. Nutrient densities of snacks were low in all time periods but lowest in morning snacks. Nutrients present in lowest amounts were iron, calcium, and vitamin A. Snack patterns of boys and girls were similar, although boys' intakes of energy, calcium, and riboflavin were higher than those of girls.
Adolescent↗
Nutrition knowledge of teen-agers.
Nutrition knowledge tests were administered to 1,193 teen-agers in Oregon prior to units on nutrition in health and home economics classes. Mean scores on the test were low, 39.4 +/- 11.6% correct. Teen-agers generally knew the Four Food Groups, appropriate snacks, a single "best" source of nutrients and the basics of weight control. They overestimated the importance and necessary amounts of dietary protein and vitamin C. Most of these teen-agers did not know food sources of nutrients other than the commonly known "best" source. They also had difficulty selecting a nutritious meal unless the meal followed traditional patterns. The nutrition units taught to these teen-agers generally included the Four Food Groups, the relationship of diet to health and food sources of various nutrients. Less than one-third of the units had major emphasis on nutritional needs during pregnancy, nutrition and athletics, retention of nutrients in food preparation or food fads and myths.
Adolescent↗
Resistance of chromatin superstructure to tryptic digestion modulated by conjugated polyacrylamide.
Soluble polyacrylamide conjugates have been used to modulate tryptic digestion of chromatin. Digestion of histones H1/H5 and H3 are mutually dependent and relatively independent of that of the core histones which are not significantly digested until 50-60% of H3 is degraded. H1/H5 and H3 are most exposed, H3 behaves as a "non-core' histone, its destruction appears to be the critical factor in the collapse of the chromatin superstructure during tryptic digestions. The digestion kinetics are explained by proposing that the initial sites of attack are in cavities much larger than the diameter of trypsin (4-5 nm). Procedures for the preparation of soluble polyacrylamide and its conjugation to trypsin are described.
Acrylic Resins↗
Avian erythrocyte chromatin degradation: the progressive exposure of the dinucleosomal repeat by bovine-pancreatic-DNAase-I-armed probes and free DNAase-I.
Bulky probes composed of glutaraldehyde-cross-linked-complexes of ferritin or bovine serum albumen armed with bovine pancreatic DNAase-I have been used to generate the typical dinucleosome-based series of native or denatured DNA fragments from chicken erythrocytes. Double stranded DNA fragments have shown that the 2N series extends to at least 10N without any clearly defined end-point. The susceptible nucleosomes were observed to be nucleolysed by two major, different methods of attack that generated multiple peaks in the dinucleosomal size class and some characteristics of the digestion patterns have been taken as indications of the presence of another level of structure above that of the alternating structure. The chromatin structure becomes resistant to the probes when the average fragment length falls to approximately 4N but this 'core' is not a single integral multiple of nucleosomes.
Animals↗
Fetal androgens and sexual mimicry in spotted hyaenas (Crocuta crocuta).
Sexual differentiation of the Müllerian duct system and gonad in female fetuses conformed to the general mammalian pattern, whereas the external genital anlage in male and female fetuses developed into the male facies. Interstitial cells occurred in the primary germinal cords of both male and female fetal gonads and are suggested to be the source of androgen production in spotted hyaena fetuses. Maternal transfer of androgens to the fetus via the placenta was negligible. Male fetuses had higher gonadal and plasma concentrations of testosterone than female fetuses, and vice versa for androstenedione. Plasma testosterone was nearly as high in a female 31-day-old fetus as in the twin male, and masculinization of the genital tubercle probably results from an episode of androgen secretion by the fetal gonad although the Wolffian ducts in the female do not respond.
Adrenal Glands↗
Chromatin superstructure: the next level of structure above the nucleosome has an alternating character. A two-nucleosome based series is generated by probes armed with DNAase-I acting on isolated nuclei.
Explore the source record for details and available documents.
Animals↗
Annual reproductive pattern in the springhaas, Pedetes capensis.
The springhaas, Pedetes capensis, is capable of breeding throughout the year in the Orange Free State province of South Africa and fetuses of all sizes were found throughout the year. The highest incidence of pregnancies was found during the winter months July and August with the majority of embryos and small fetuses occurring between April and July and most larger fetuses thereafter. Birth weight was probably 280-300 g. Juveniles stay in the burrows until they have attained a body mass of 1.5 kg. Once spermatogenesis is established at a liveweight of about 2.5 kg it appears to be continuous. There was an indication that plasma LH and progesterone concentrations were related to corpus luteum diameter.
Animals↗
Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. II. Histochemistry of the epididymis.
The three main segments of the elephant epididymis were examined for the occurrence, in the spermatozoa and lining epithelium, of carbohydrates, neutral lipids and phospholipids, ATPase, alkaline phosphatase, succinic dehydrogenase, glucose-6-phosphate dehydrogenase, diaphorases, hydroxysteroid dehydrogenases, acid phosphatase and non-specific esterase. The most distinct feature of the carbohydrate content of the epididymis was a layer of acidic, alcian blue-positive glycoprotein over the luminal surface of the epithelium, particularly in the terminal segment. PAS-positive, diastase-resistant inclusions were also found throughout the epdidymis. Neutral lipid occurred as droplets above and below the nucleus in the epithelium of the middle segment, and as supranuclear accumulations in the terminal segment. All the enzymes except the steroid dehydrogenases were detected in the epididymal epithelium, and all except the steroid dehydrogenases and acid phosphatase were detected in the spermatozoa. There was considerable variation in the intensity of the cytochemical reactions in the epithelium, but not in the spermatozoa, in different regions of the epididymis. In general, the enzymes involved in active transport showed strongest reactions in the initial and terminal segments, the reactions in the stereocilia being the most intense. The enzymes involved in energy metabolism showed strongest reactions in the middle and terminal segments, with the activity being fairly evenly distributed throughout the cytoplasm of the principal cells. However, the two lysosomal enzymes which were studied showed quite different distributions: the reactions for acid phosphatase were strongest in the initial and middle segments, whilst the reactions for non-specific esterase were strongest in the middle and terminal segments. It is suggested that the initial segment is involved in absorptive and anabolic activity, the middle segment in anabolic activity, and the terminal segment (where spermatozoa are stored ready for ejaculation) in considerable metabolic activity and active transport of substrates across the epithelium.
Acid Phosphatase↗
Probing the free space within rat and chicken chromatin with active and passive probes.
The cavity systems within chicken erythrocyte nuclei and rat liver nuclei were compared using passive probes of radioactive glycogen and active probes of nuclease-armed-glycogen. The passive probe curves have a form that indicates that they are due to passive occupation of spaces and not due to the effects of a limiting membrane. The technique of probing nuclei with glycogen armed with a small enzyme is described. The chicken erythrocytes appeared to have 11-15-nm and 4-5-nm cacity systems similar to those we have previously reported in rat nuclei. Evidence is presented to show that the bridge DNA is enclosed within the 4-5 nm cavities in both rat liver and chicken erythrocyte nuclei. Minor differences between the rat liver and chicken erythrocyte nuclear cavity systems are noted in the region of 5-8 nm. A relatively mild procedure is described for preparing chicken erythrocyte nuclei.
Animals↗
Analysis of the penetrable space within the nucleus.
Radioactive glycogen molecules have been used as passive probes to compare cavity systems within nuclei and isolated chromatin. Isolated chromatin was found to possess a narrow range of microspaces with mean effective diameters between 4.0 and 4.5 nm (40 and 45 A) depending on shape assumptions. Intact nuclei contained a far larger class of free spaces with average diameters in the order of 11.0-15.0 nm. This clearly shows that DNase-I (diam. 4.1 nm) can penetrate and occupy a large proportion of nuclear space even though this enzyme does not readily attack the undisturbed nuclear structure. A structure which simulated the pattern of penetrability and incorporated other known properties of chromatin was used to explain this DNase-I resistance of intact nuclei in terms of an ordered, compact, local structure interspersed by much larger spaces. A system for this local packing is suggested and the functional implications of this type of organization considered.
Animals↗