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Biomedical subjects

W L Stone

Publications and source records attributed to W L Stone.

At least 37 records · Page 2Linked to original sources
PubMed1994

Lipoprotein alterations in the spontaneously hypertensive rat fed diets deficient in selenium and vitamin E.

Both vitamin E and selenium (Se) are antioxidant nutrients that play important roles in preventing in vivo lipid peroxidation. In this investigation, Se and vitamin E were found to influence lipoprotein levels in the spontaneously hypertensive rat (SHR). Four-week-old inbred SHRs were fed a basal (B) diet with 1% cholesterol deficient in both selenium and vitamin E (B+cho diet) or identical diets to which either vitamin E (B+E+cho) or selenium (B+Se+cho) or both micronutrients were added (B+Se+E+cho). Plasma-cho and lipoprotein-cho levels were measured after 6, 12, 16, and 18 weeks of feeding the experimental diets. Rats fed the B+cho diet for at least 12 weeks had plasma-cho levels about twice that observed for rats fed the B+E+Se+cho diet. Plasma-cho levels for rats in the two Se deficient groups (B+cho and B+E+cho) were, however, similar at any time point. Se deficiency was associated with increased plasma-cho, very low density lipoprotein-cho (VLDL-cho) and low-density lipoprotein-cho (LDL-cho). Vitamin E supplementation interacted with Se deficiency to increase plasma VLDL-cho levels. Neither vitamin E alone nor the interaction between vitamin E and Se consistently influenced LDL-cho levels. The percent cholesteryl ester in LDL from rats fed the Se-deficient diets (B+cho or B+E+cho) was at least twice that observed for rats fed the B+E+Se+cho diet. Plasma lipid peroxidation products were highly elevated in rats fed the B+cho diet compared with values for the B+E+cho or the B+E+Se+cho fed rats (which were not significantly different). These results suggest that dietary Se deficiency increases plasma-cho, VLDL-cho, and LDL-cho levels by a mechanism that may be unrelated to its role as an antioxidant nutrient.

Animals↗
PubMed1993

A structured parent interview for identifying young children with autism.

This study evaluated the psychometric properties of the Parent Interview for Autism (PIA), a structured interview for gathering diagnostic information from parents of young children with autism. Internal consistency was evaluated in a sample of 165 children under 6 years old, and test-retest reliability and construct validity were evaluated in subsamples of the original group. Results revealed internal consistency and test-retest reliability above .60 for 9 of the 11 dimensions constituting the PIA, as well as significant correlations between the PIA and other measures of autism. Six of the PIA dimensions differentiated a group of young children with autism from a developmentally comparable group with mental retardation. Implications of these findings and suggestions for future research are discussed.

Autistic Disorder↗
PubMed1992

Structural alterations in retinal tissues from rats deficient in vitamin E and selenium and treated with hyperbaric oxygen.

Vitamin E and selenium play key roles in preventing in vitro lipid peroxidation and free radical damage to retinal tissues. In this research, we studied the effects of hyperbaric oxygen on retinal structure in rats fed diets deficient in vitamin E and/or selenium. We also correlated any alterations in retinal structure with previously measured alterations in electroretinograms (ERGs). Age-matched rats were fed a basal diet deficient in both vitamin E and selenium (B diet), a basal diet supplemented with vitamin E alone (B+E diet), or selenium alone (B+Se diet), or with both micronutrients (B+E+Se). Half the rats in each group were treated (+HBO) with hyperbaric oxygen (100% O2 at 3 ATA for 1.5 per hr day, 5 days per week) and half were not (-HBO). We previously found that the rats fed the B diet for 6 weeks and treated with HBO for 4 weeks (B+HBO group) had diminished a-wave ERG amplitudes. At this time point all rats in the B group and half of the rats in the B+E+Se group were killed for the structural studies reported here. Surprisingly, we found no evidence of photoreceptor cell necrosis [i.e. a decreased thickness of the outer nuclear layer (ONL)] in retinas from rats in the B+HBO group despite the diminished amplitude of the a-wave which arises from this retinal layer. Quantitative structural analyses of retinas from rats in the B+HBO, B-HBO, B+E+Se-HBO and B+E+Se+HBO groups also failed to reveal any significant differences in the cell height of the retinal pigmented epithelium (nasal, central or temporal regions) or the number of mitochondria, phagosomas or inclusion bodies in the central retinal pigment epithelium (RPE). The inner nuclear layer (INL) thickness was, however, consistently decreased in all retinal regions for the rats in the B+HBO group. Our previous work also showed that only rats fed the B+Se diet for 17 weeks and treated with HBO for 15 weeks (B+Se+HBO group) showed diminished a-wave and b-wave ERG amplitudes. At this time point rats in the B+E+Se, B+E, and B+Se groups were killed for structural studies reported here. Only rats in the B+Se+HBO group showed a significantly decreased (about 20%) thickness of the central ONL. This evidence of photoreceptor cell necrosis correlated very well with our previous observation of diminished a- and b-wave amplitudes only in the B+Se+HBO group (at week 17).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

The role of selenium in the secretion of very-low-density lipoprotein in the isolated perfused rat liver.

A recirculating liver perfusion system was used to study the effects of dietary selenium (Se) on the hepatic secretion of very-low-density lipoprotein (VLDL). The perfusate from livers of rats fed on a Se-deficient diet incorporated about 50% more [1-14C]oleic acid into triacylglycerol (TG) and cholesteryl esters (ChoEs) than did the perfusate from livers of rats fed on a Se-supplemented diet. Similarly, livers from rats fed the Se-deficient diet secreted more VLDL and incorporated about 60% more [1-14C]oleic acid into VLDL TG and ChoEs than did livers from rats fed the Se-supplemented diet. The liver perfusate from rats in the Se-deficient group also showed significantly decreased fatty acid oxidation. We conclude that Se is a potent modulator of lipoprotein metabolism. A primary action of Se deficiency appears to be a decrease in fatty acid oxidation and a stimulation of fatty acid esterification, leading to increased VLDL TG and ChoEs formation and secretion.

Animals↗
PubMed1991

The importance of parents' concerns about their child's behavior.

Parents often complain about children's behavior. Pediatricians may be unsure whether to ignore these complaints, counsel parents in-office or refer them to mental health services. This study shows a close relationship between parents' concerns and measurably significant behavior problems. Methods are provided for responding to parents' concerns. These should be useful to pediatricians who are often criticized for failing to detect and refer children with mental health problems including behavior disturbances.

Child↗
PubMed1990

Naturalistic observations of spontaneous communication in autistic children.

Thirty children with autism were observed during their everyday school activities in order to examine patterns of spontaneous communication. The forms, functions, and targets of their communication were recorded by trained observers. The prototypical communicative event consisted of a child directing a motoric form of communication toward the teacher to request something or to attract attention to himself or herself. However, communication patterns were found to vary as a function of the child's cognitive level and severity of autism. Deficits in joint attention functions were observed, and were most striking in the subgroup of children who did not use speech. Results are discussed with reference to Wetherby's (1986) model for the development of communicative functions in autistic children.

Adolescent↗
PubMed1990

Parental report of social behaviors in autistic preschoolers.

The aim of this study was to identify specific social behaviors that differentiate autistic preschoolers from other children at comparable developmental levels. A parent report measure, the Preschool Social Behavior Checklist (PSBC), was developed for this purpose. The PSBC consists of 22 items representing social milestones usually achieved within the first 4 to 5 years of life. Results obtained from a sample of 20 parents of children with autism and 14 parents of children with mental retardation revealed group differences in specific aspects of imaginative play, peer play, and imitation skills. The importance of examining the specific manifestations of social deficits and implications for the diagnosis of autism are discussed.

Autistic Disorder↗
PubMed1990

The social status of children with learning disabilities: a reexamination.

Although the low social status of children with learning disabilities (LD) has been well documented, little is known about the specific types of peer status problems that characterize these children. The present study utilized current sociometric procedures in order to clarify the nature of social status difficulties encountered by children with LD. Consistent with previous studies, results revealed that children with LD obtain significantly lower sociometric scores relative to their nondisabled peers. Moreover, children with LD were found to be disproportionately overrepresented in the rejected and neglected sociometric groups, and underrepresented in the popular and average groups. Over half of the total LD sample was classified into one of the low status categories, with approximately equal numbers in the rejected and neglected groups. Implications of these findings and suggestions for future research are discussed.

Child↗
PubMed1990

LD status and achievement: confounding variables in the study of children's social status, self-esteem, and behavioral functioning.

The purpose of the present study was to examine the role of achievement in explaining the poor social and behavioral functioning associated with LD status, and to evaluate potential gender differences in patterns of interpersonal functioning among youth with learning disabilities (LD) and nondisabled (NLD) youth. Thirty-two students with learning disabilities (21 boys, 11 girls) were matched with same-sex, same-race classmates whose reading achievement was low (LA) or average (AA), and these groups were compared on peer ratings of liking and disliking, perceptions of self-worth and social acceptance, and teacher ratings of conduct problems, anxiety-withdrawal, and attention problems. Students with learning disabilities were less accepted and less well-liked than children in the LA or AA groups and also perceived their self-worth and social acceptance to be lower than LA or AA students. Group by Sex interactions were apparent for several of the peer rating and behavioral variables, indicating that different patterns of social and behavioral functioning distinguished LD boys and LD girls from their NLD peers. The findings highlight the potential role of low achievement in peers' dislike of LD girls and suggest the importance of investigating well-defined subgroups of youth with LD in future research.

Achievement↗
PubMed1990

Plasma-vitamin E and low plasma lipoprotein levels in sickle cell anemia patients.

Increasing evidence suggests that in vivo lipid peroxidation may be an important factor in sickle cell anemia (HbSS). Vitamin E is the major lipid-soluble antioxidant in plasma, and this vitamin, as well as cholesterol, is transported in plasma almost exclusively by lipoproteins. The purpose of this investigation was to determine if vitamin E and plasma lipoprotein-cholesterol levels in sickle cell anemia (SCA) patients are interrelated. We found that low plasma-vitamin E levels in SCA patients were accompanied by low levels of plasma-cholesterol. The mean plasma-vitamin E/plasma-cholesterol ratio was similar in 12 SCA patients (6.1 +/- 0.7 micrograms vitamin E per mg plasma-cholesterol) and 21 controls (6.5 +/- 0.7 micrograms/mg). Our results suggest that the low levels of plasma-vitamin E in SCA patients may be related to decreased levels of lipoprotein carriers. The low plasma-cholesterol levels in SCA patients (139.1 +/- 9.9 mg/dL) were due to low levels of both high density lipoprotein-cholesterol (HDL-cholesterol of 35.0 +/- 1.0 mg/dL) and low density lipoprotein-cholesterol (LDL-cholesterol of 97.8 +/- 9.2 mg/dL). The "atherogenic index," defined as LDL-cholesterol/HDL-cholesterol, was similar in the SCA patients (2.9 +/- 0.2) and the controls (3.0 +/- 0.4).

Adult↗
PubMed1990

Play and imitation skills in the diagnosis of autism in young children.

Play behaviors and motor imitation skills of 91 children between the ages of 3 and 6 years were investigated to determine their utility in distinguishing autism from mental retardation and other communication disorders. The performance of 22 autistic children was compared with that of 15 mentally retarded, 15 hearing-impaired, 19 language-impaired, and 20 non-handicapped children. Play behaviors were assessed using structured observations of free-play activities, and imitation skills were measured using a set of 12 individually administered tasks. The autistic group spent less total time interacting with toys and using toys appropriately, engaged in fewer functional play acts, and obtained lower imitation scores compared with all other groups. Discriminant function analysis revealed that the latter three variables discriminated the autistic children from the nonautistic handicapped children, with motor imitation emerging as the most important differentiating measure. These results suggest that measuring play and imitation skills may be useful in the clinical diagnosis of autism.

Autistic Disorder↗
PubMed1989

A novel spectrophotometric assay for lipase activity utilizing cis-parinaric acid.

A new spectrophotometric assay for determining the activity of acylglycerol hydrolases (lipases, E.C. 3.1.1.3) was developed and optimized for yeast lipase (Candida cylindracea). Studies with porcine pancreatic lipase were also conducted and the influence of various detergents and divalent cations on the assay was evaluated. The assay uses cis-parinaric acid (PnA), a naturally occurring fatty acid that has unique spectroscopic properties, and takes advantage of the reversible binding of fatty acids to bovine serum albumin (BSA). Free PnA has an ultraviolet absorption peak at 321.2 nm. When PnA is bound to BSA, however, the peak shifts to 324.2 nm. The assay mixture contains 6 microM PnA, 1 microM BSA, 75 microM triolein, and 0.3 mM taurocholate in a 50 mM tris-HCl buffer with 1 microM EDTA. The release of oleic acid from triolein is monitored over time by measuring the ratio of optical densities (OD) at 319.0 and 329.0 nm. Initially, there is maximum binding of PnA to BSA, and the OD ratio is approximately 1.0. Upon addition of lipase, PnA is displaced from the BSA by oleic acid released from triolein, and the OD ratio increases to a maximum of about 1.8. However, when calcium is present in the reaction mixture an insoluble calcium-PnA complex forms, resulting in a progressive decrease in OD at both 319.0 and 329.0 nm. The kinetic assay described here is simple, rapid, sensitive, reproducible, inexpensive, and it can be adapted to measure the activity of a variety of calcium-independent lipases. Under similar assay conditions, activities for Candida cylindracea lipase obtained with this assay are similar to those obtained with 14C-labelled triolein.

Animals↗
PubMed1989

The role of antioxidant nutrients in preventing hyperbaric oxygen damage to the retina.

Vitamin E and selenium play essential roles in preventing in vivo lipid peroxidation and free radical damage. Hyperbaric oxygen (HBO) treatment adversely affected the electroretinograms (ERGs) of rats fed a diet deficient in both vitamin E and selenium (the basal or B diet) or a diet deficient in vitamin E alone (B + Se diet). After 4 weeks of HBO treatment (3.0 ATA or 100% oxygen, 1.5 hours per day, 5 day/week) rats fed the B diet deficient in vitamin E and selenium for 6 weeks showed decreased (p less than 0.05) a-wave amplitudes, 85 +/- 9 microvolts (microV), n = 11, compared with a-waves recorded (150 +/- 10 microV, n = 21) for age matched rats fed an identical diet for 6 weeks but not treated with HBO. After 15 weeks of HBO treatment, rats fed the B + Se diet deficient in vitamin E alone showed decreased (p less than 0.01) a-wave (61 +/- 9 microV, n = 4) and b-wave (253 +/- 23 microV, n = 4) amplitudes compared with a-wave (115 +/- 7 microV, n = 4) and b-wave amplitudes (450 +/- 35 microV, n = 4) for age matched rats fed the same diet but not treated with HBO. Decreased a- or b-wave amplitudes provide evidence of retinal damage. Rats fed a diet supplemented with vitamin E and selenium or vitamin E alone showed no decreases in either a- or b-wave amplitudes after 15 weeks of HBO treatment.

Animals↗
PubMed1989

Pediatric psychology training: an analysis of graduate, internship, and postdoctoral programs.

The field of pediatric psychology is in the early stages of formulating its own identity relative to other areas, such as clinical child and health psychology. This paper complements other recent efforts to delineate training practices and guidelines. Questionnaires regarding doctoral, internship, and postdoctoral training experiences were obtained from 89% of the membership of the Society of Pediatric Psychology. From this information, rankings of the most commonly attended programs at each training level were derived. Some overlap was apparent between doctoral programs that were conducive to training in pediatric and clinical child psychology; however, differences between programs in these areas also were noted. The most commonly attended internship and postdoctoral settings were those in major medical centers or children's hospitals. Suggestions for investigating the current status of predoctoral, internship, and postdoctoral programs that may be facilitative of training in pediatric psychology are discussed.

Adult↗
PubMed1989

The apparent association constant of calcium and bilirubinate ions in Triton X-100 micelles.

Calcium bilirubinate [Ca(HB)2], a major component of pigment gallstones, rapidly precipitates from aqueous solutions, thereby precluding an accurate determination of the apparent association constant (K') of calcium (Ca2+ and monohydrogenated bilirubinate (HB) ions. In this study, we determine the K' in solutions of Triton X-100, a nonionic detergent with a critical micellar concentration of 0.01 g/dL, by analysis of spectral shifts, using a Hewlett-Packard diode array spectrophotometer. In the absence of Ca2+, 10 microM sodium bilirubinate (NaHB) solutions were incorporated into Triton X-100 micelles in 0.15 M NaCl, 0.10 M Tris Cl, pH 8, as evidenced by a progressive shift in the wavelength maximum (lambda max) of 10 microM HB from 438 to 458 nm in 0-0.1 g/dL (0-10 microM of micelles/L) Triton. Thus the lambda max plateau occurred with 1 mole of HB per micelle of Triton. As Ca2+, 0-90 microM, was added to 100 microM NaHB in 0.5 g/dL Triton X-100, there was a progressive downward shift in the lambda max of HB from 458 to 434 nm; an isosbestic point was present at 448 nm. A calibration curve using ratios of absorbance (Abs) 420/470 for known concentrations of Ca(HB)2 or NaHB was used to determine the mole fraction of Ca(HB)2. The spectral data were consistent with the equilibrium equation: Ca2+ + 2 HB = Ca(HB)2.(ABSTRACT TRUNCATED AT 250 WORDS)

Bilirubin↗
PubMed1988

A comparison of teacher and parent views of autism.

Changing conceptualizations of autism have led to an increased focus on parents and teachers as treatment agents. In order to evaluate the views of autism held by these two groups, 47 teachers of autistic students and 47 parents of autistic children completed a survey assessing beliefs regarding various aspects of the disorder. Parent and teacher responses were compared to those obtained from a group of 22 "specialists" in autism, drawn from across the country. Both parents and teachers were found to harbor misconceptions regarding cognitive, developmental, and emotional features of autism. Furthermore, parents and teachers hold discrepant views in some areas that may have implications for their collaborative efforts.

Adolescent↗
PubMed1988

The effects of in vitro lipid peroxidation on the activity of rat liver microsomal glutathione S-transferase from rats supplemented or deficient in antioxidants.

Glutathione S-transferases are a group of multifunctional isozymes that play a central role in the detoxification of hydrophobic xenobiotics with electrophilic centers (1). In this study we investigated the effects of in vitro lipid peroxidation on the activity of liver microsomal glutathione S-transferases from rats either supplemented or deficient in both vitamin E and selenium. Increased formation of malondialdehyde (MDA), a by-product of lipid peroxidation, was associated with a decreased activity of rat liver microsomal glutathione S-transferase. The inhibition of glutathione S-transferase occurred rapidly in microsomes from rats fed a diet deficient in both vitamin E and selenium (the B diet) but was delayed for 15 minutes in microsomes from rats fed the same diet but supplemented with these micro-nutrients (B+E+Se diet). Lipid peroxidation inhibits microsomal glutathione S-transferase and this inhibition is modulated by dietary antioxidants.

Animals↗