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Biomedical subjects

J Nelson

Publications and source records attributed to J Nelson.

At least 217 records · Page 12Linked to original sources
PubMed1991

Fat and cholesterol avoidance among Mexican-American and Anglo preschool children and parents.

Is a fat-avoidance scale a useful tool for monitoring and tracking dietary fat selections of adults and children? Using a seven-point scale, we addressed this question with 341 preschool children and 421 of their parents participating in a longitudinal study of childhood behaviors in San Diego County, California. Milk type and cooking fat reported in the fat-avoidance scale was compared with data reported in a 24-hour food intake record. An overall 86% agreement for milk type and a 78% agreement for cooking fat were noted. Anglo preschoolers (n = 143) had significantly greater mean scores for fat and cholesterol avoidance than did Mexican-American preschoolers (n = 198). Anglo, but not Mexican-American, women avoided fat and cholesterol more often than did their male counterparts. A significantly higher sum score was noted for Anglo men and women and Mexican-American men as education increased. These findings indicate that the fat-avoidance scale has a relative validity compared with a 1-day food record, that fat avoidance can be measured, that differences can be noted in a biethnic sample of children and adults, and that the scale has potential for monitoring success in achieving a lower fat and cholesterol intake.

Adult↗
PubMed1991

Saccades simulated with rhesus monkey innervation data.

Extracellular single-unit data from the vicinity of the abducens nucleus from rhesus monkeys recorded during horizontal saccades are used as input to an updated oculomotor plant to simulate saccades to test the robustness of the model. Cells recorded from include: Long Lead Burst neurons, Medium Lead Burst neurons, and Burst Tonic neurons. Eye movement position data was collected using the magnetic coil technique. The oculomotor plant used in this study consists of the lateral and medial rectus muscle, and the eyeball. The muscles are modeled as a viscoelastic parallel combination connected to a parallel combination of active state tension generator, viscosity element and length tension elastic element. The eyeball is modeled as a sphere, connected to two parallel viscoelastic elements, connected in series. Each of the elements is linear. All parameters and initial conditions are estimated or directly measured from physiological data. The active state tension generator waveforms are the low-passed filtered motoneural signals. The extracellular single-unit data is used to drive the agonist portion of a neural circuit, consisting of burst, tonic and pause cells. The antagonist portion of the neural activity is based on previously reported characteristics. Simulation results for eye position and higher derivatives are in good agreement with the eye position data and the data derived estimates of higher derivatives.

Animals↗
PubMed1990

Oxygen and temperature dependence of stimulated insulin secretion in isolated rat islets of Langerhans.

The effects of lowered O2 tension on insulin secretion and changes in cellular energy parameters were investigated in isolated rat pancreatic islets perifused with buffers equilibrated with 21, 9, 5, and 1% oxygen and containing 5 mM glucose. Decreasing the external [O2] reduced the amount of insulin released in response to 16 mM glucose, 20 mM alpha-ketoisocaproic acid, and 40 mM KCl. Secretion elicited by high glucose or KCl had declined significantly at 9% oxygen, whereas that caused by alpha-ketoisocaproic acid became inhibited below 5% O2. Lowering the oxygen tension also decreased the ability of islets to respond with a rise in [ATP]/[ADP] upon stimulation with metabolic secretagogues. This reduction in the evoked increase in the nucleotide ratios paralleled the inhibition of stimulated insulin secretion. Addition of 2 mM amytal markedly decreased the islet energy level and eliminated the secretory response to 16 mM glucose. The results suggest that enhancement of B-cell energy production and a consequent rise in [ATP] (or [ATP]/[ADP]) are a necessary event for the hormone release elicited by high glucose and alpha-ketoisocaproic acid. A decrease in temperature inhibited insulin secretion with all three secretagogues tested. The energies of activation were similar for high glucose and KCl-induced secretion, about 20 kcal/mol, but were higher for alpha-ketoisocaproic acid, about 35 kcal/mol. At 28 degrees C, the [ATP]/[ADP] was larger than that at 38 degrees C (8 versus 5) and was not increased further upon addition of 16 mM glucose. It is suggested that a decrease in the rate of energy production at lowered temperatures may contribute to the inhibition of insulin release caused by metabolic secretagogues.

Animals↗
PubMed1990

Single maxillary central incisor in association with mid-line anomalies.

A single maxillary central incisor may occur as an isolated dental finding. However, it has also been reported to occur in association with autosomal dominant holoprosencephaly, in association with growth retardation with or without growth hormone deficiency and occasionally in association with other mid-line developmental defects. Holoprosencephaly and pituitary dysfunction are two specific examples of mid-line defects and this report emphasises that other mid-line defects may be associated with a single maxillary central incisor. We recommend that patients with this dental anomaly should be referred for a detailed medical examination.

Abnormalities, Multiple↗
PubMed1990

Children's television-viewing habits and the family environment.

Pediatricians are encouraged to modify the impact of television on children, based on the assumption that parents mediate children's viewing habits through the home environment. Sixty-six parents of children aged 3 to 8 years responded to an interviewer-administered questionnaire. Responses to questions on family environment were compared with reported childhood viewing of educational programming (Public Broadcasting Service) and the child's television-viewing hours. Most homes surveyed had a videocassette recorder, cable television, and more than one television set. Frequent parental discussion of program content with children was reported by 38% of respondents. Availability of television and parent-child discussion of content were not correlated with viewing hours or viewing Public Broadcasting Service. Frequent use of television as a distraction for the child correlated positively with viewing hours. Viewing Public Broadcasting Service correlated negatively with parent-child coviewing and with use of television as a form of entertainment. Children's own television viewing content correlated positively with viewing Public Broadcasting Service. Of all measured factors in the home environment, parental attitudes were most closely associated with children's viewing habits.

Attitude↗
PubMed1990

Postnatal development of the skin of the marsupial native cat Dasyurus hallucatus.

Skin development of the Northern native cat was examined from birth to weaning at 150 days post partum. An outer layer of cells, termed the periderm or epitrichium, is present on the epidermis of the newborn. This layer of cells is not discernible at 7 days post partum. Skin development of the native cat differs from that of the eutherian mammal. The periderm of the eutherian is no longer discernible when the developing hairs first penetrate the epidermis. In the marsupial, this loss of the periderm occurs well before the appearance of follicles. Melanocytes and Langerhans cells are seen at day 23 post partum, follicles at day 30, sebaceous glands at day 59, and sweat glands at day 67. Thus, when the mother first leaves her young in the nest at about days 60 to 70 of lactation, the skin is at a stage of development that will assist the young with thermoregulation. The skin continues to develop throughout lactation and attains an adult appearance by day 150 post partum.

Animals↗
PubMed1990

Dental findings in mucopolysaccharidosis type IV A (Morquio's disease type A).

Dental examinations on nine patients with mucopolysaccharidosis type IV A (MPS IV A, Morquio's disease type A) were carried out. Detailed medical, radiologic, and biochemical studies of each case were also performed independently. Dental changes were present in all cases, although the severity varied. The severity of the dental changes did not correlate with the clinical or biochemical findings in all cases. These dental changes are seen only in MPS IV A (N-acetylgalactosamine-6-sulphate sulphatase deficiency) and are not found in MPS IV B (beta-galactosidase deficiency) or the recently delineated MPS IV C (enzyme defect unknown). The dental changes can aid in the diagnosis of patients affected by MPS IV A and are especially useful in mild atypical cases.

Child↗
PubMed1990

Depletion of myocardial adenosine triphosphate during prolonged untreated ventricular fibrillation: effect on defibrillation success.

We studied left ventricular endomyocardial adenosine triphosphate levels in 13 large mongrel dogs before and during ventricular fibrillation induced cardiac arrest to assess whether myocardial adenosine triphosphate content could predict successful cardiopulmonary resuscitation. Endomyocardial biopsies were performed during sinus rhythm (control), after 15 min of ventricular fibrillation or 10 min of ventricular fibrillation and 5 min of open chest cardiopulmonary resuscitation, after 20 min of ventricular fibrillation and 10 min of open chest cardiopulmonary resuscitation and after 40 min ventricular fibrillation and 15-20 min open chest cardiopulmonary resuscitation. Myocardial adenosine triphosphate was measured utilizing a bioluminescence method adapted for use with endomyocardial biopsies and normalized to protein content. Left ventricular endomyocardial adenosine triphosphate content fell significantly over time from a control level of 8.88 +/- 0.9 micrograms/mg protein to 5.73 +/- 0.5 micrograms/mg protein at 15 min of cardiac arrest, to 3.4 +/- 0.4 micrograms/mg protein after 30 min of cardiac arrest and to 1.98 +/- 0.3 micrograms/mg protein after 60 min of cardiac arrest (P less than 0.001). Adenosine triphosphate levels were significantly different between animals that received 10 min of ventricular fibrillation and successful open chest cardiopulmonary resuscitation and those that received 40 min of ventricular fibrillation and unsuccessful open chest cardiopulmonary resuscitation (4.35 +/- 0.48 vs. 2.11 +/- 0.43 micrograms/mg protein; P less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1990

Cerebellotectal pathways in the macaque: implications for collicular generation of saccades.

The cerebellum is thought to modulate saccadic activity in the primate in order to maintain targeting accuracy, and the cerebellotectal pathway has been posited to play a role in this modulation. However, anatomical descriptions of this pathway in primates are sketchy and conflicting. To determine whether the organization of the cerebellotectal projection in primates is similar to that found in other species, neuroanatomical tracer transport techniques were utilized in two species of macaque monkey to label cerebellotectal somata and fiber terminations. Two pathways were found. One, the fastigiotectal pathway, is derived from cells in the caudal fastigial nucleus and projects bilaterally to the rostral end of the intermediate gray layer. The other pathway is derived from cells in the posterior interposed nucleus and the adjacent posterior wing of the dentate nucleus, and it terminates contralaterally throughout the ventral half of the intermediate gray and the deep gray layers. Both of these pathways terminate within the layers of the superior colliculus containing premotor, saccade-related neurons, but the differences in the distribution of their terminals and cells of origin suggest that these two pathways have different functions. Furthermore, the pattern of connections of these two pathways indicates that they do not function as a traditional feedback circuit. We suggest that the cerebellotectal pathways may instead modulate collicular activity in a more complex manner. For example, it may provide signals necessary for corrective saccades or for maintaining spatial registry between the different sensory representations supplied to the superior colliculus and its presaccadic output, which is organized into a motor map.

Animals↗
PubMed1990

A transdominant tat mutant that inhibits tat-induced gene expression from the human immunodeficiency virus long terminal repeat.

Regulation of human immunodeficiency virus (HIV) gene expression is dependent on specific regulatory regions in the long terminal repeat. These regions include the enhancer, SP1, "TATA," and trans-activating (TAR) regions. In addition, viral regulatory proteins such as tat and rev are important in regulating HIV gene expression. The mechanism of tat activation remains the subject of investigation, but effects at both transcriptional and posttranscriptional levels seem likely. Previous mutagenesis of the tat protein revealed that the amino terminus, the cysteine-rich domain, and the basic domain were all required for complete tat activation. Mutants of other viral trans-acting regulatory proteins, including E1A, tax, and VM65, have been identified that were capable of antagonizing the activity of their corresponding wild-type proteins. We wished to determine whether mutants of the tat protein could be identified that exhibited a similar phenotype. One mutant (delta tat) that truncated the basic domain of tat resulted in a transdominant phenotype inhibiting tat-induced gene expression of the HIV long terminal repeat but not other viral promoters. This mutant exhibited its maximal phenotype in cotransfection experiments when present in an 8- to 30-fold molar excess over the wild-type tat gene. Trans-activation of the HIV long terminal repeat by delta tat was very defective at the DNA concentrations used in these experiments. RNase protection analysis indicated that this mutant decreased tat-induced steady-state mRNA levels of the HIV long terminal repeat. Second-site mutations of the delta tat gene in either the amino terminus or cysteine region eliminated the transdominant phenotype. In contrast to tat, which was localized predominantly to the nucleolus, delta tat was present in both the nucleus and cytoplasm, suggesting that it may inhibit tat function by preventing nucleolar localization. Transdominant mutants of tat may have a role in potentially inhibiting HIV gene expression.

Amino Acid Sequence↗
PubMed1990

Two cases of cri-du-chat syndrome with mild phenotypic effect but with different size of 5p deletion.

The clinical and cytogenetic findings of two cases of cri-du-chat syndrome are described. Both cases were females with only slight growth delay, moderate mental disability and minimal phenotypic effects. The mild phenotype was difficult to correlate with the karyotype, which on GTG and RBG banding showed that each had a regular de novo 5p deletion. The deletion in Case 1 was terminal - 46,XX,del(5) (pter----p15.2:) and in Case 2 it was interstitial - 46,XX,del(5) (pter----p15.2::p13.3----qter). The deletion in Case 2 was considerably larger than in Case 1.

Child↗
PubMed1990

Normal mitochondrial genome in brain from patients with Parkinson's disease and complex I defect.

The mitochondrial genome codes for 13 proteins which are located in the respiratory chain. In postmortem brain of patients with Parkinson's disease, decreased activity of complex I of the respiratory chain could be demonstrated. Because seven subunits of complex I are coded by the mitochondrial genome, we analyzed the mitochondrial DNA of human postmortem substantia nigra, putamen, and frontal cortex by the Southern blot technique. No deletions of the mitochondrial genome could be demonstrated, thus indicating that either subunits which are encoded by the nuclear genome are decreased or enzyme activity is diminished by metabolites, toxins, or increase of Fe3+.

Aged↗
PubMed1990

Pharmacokinetics of cefprozil in infants and children.

Twenty pediatric patients (ages, between 8 months and 8 years) received a single oral dose of cefprozil at levels of 15 and 30 mg/kg of body weight. Cefprozil consists of cis (BMY-28100) and trans (BMY-28167) isomers in an approximately 90:10 ratio. Six plasma samples were collected from each pediatric patient and assayed for drug concentrations. As measured by a microbiological assay, peak concentrations of 11.16 and 15.93 micrograms of cefprozil per ml occurred at 1 h for patients who received the 15- and 30-mg/kg doses, respectively. The respective mean half-lives of cefprozil were 1.77 and 2.14 h, and the respective mean areas under the curve were 28.05 and 45.28 micrograms.h/ml for patients who received the 15- and 30-mg/kg doses. When measured by a high-pressure liquid chromatography method, peak concentrations of 12.09 and 18.04 micrograms of the cis isomer per ml were obtained at 1 h, with mean half-lives of 1.63 and 2.06 h and mean areas under the curve of 30.48 and 49.34 micrograms.h/ml in patients who received the 15- and 30-mg/kg doses, respectively. For the trans isomer, peak concentrations of 1.16 and 1.63 micrograms/ml occurred at 1 h, respectively, with mean half-lives of 1.61 and 1.65 h and mean areas under the curve of 2.89 and 4.34 micrograms.h/ml in patients who received the 15- and 30-mg/kg doses, respectively.

Administration, Oral↗
PubMed1990

Cardiovascular studies in the mucopolysaccharidoses.

Cardiovascular studies were performed on 22 patients with mucopolysaccharidosis ascertained from an epidemiological study on the mucopolysaccharidoses in Northern Ireland. None of the patients had attended a cardiologist before the study. The main echocardiographical findings were thickening of the interventricular septum and left ventricular posterior wall in the absence of ECG evidence of ventricular hypertrophy. Moreover, reduced QRS voltages were present in the majority of the patients (77%) and some had reduced shortening fraction (33%). These findings suggest an infiltrative cardiomyopathy owing to mucopolysaccharide deposition as a cause of the cardiac thickening rather than true ventricular hypertrophy. Thickening of the mitral valve was present in one case and thickening of the aortic valve in two cases. Involvement of the other heart valves was minimal and aortic valve disease was not found in any of the cases of Morquio's disease type A. In conclusion, the clinical, ECG, and chest x ray findings and echocardiographical evidence for valvular involvement were significantly less than in other studies. Hence, the incidence of clinically significant cardiovascular disease in patients with mucopolysaccharidosis has probably been overestimated.

Adolescent↗