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Biomedical subjects

W Richards

Publications and source records attributed to W Richards.

At least 91 records · Page 5Linked to original sources
PubMed1982

Velocity blindness during shearing motion.

When two subjects lie at different distances from a moving observer, there is a velocity step at the occluding boundary of the nearer object. When the differential motion is tangential to the boundary, the effect is as if a shearing is taking place. If all texture cues are removed by using similar random dot patterns on each side of the boundary, then 20% of the population cannot use this differential motion to locate the boundary when it is presented to the parafovea. These observers are thus abnormally insensitive to the differential rate of texture flow at boundaries undergoing shearing motion. As no such population differences were observed for differential motion perpendicular to the occluding boundary (occluding motion), we infer that independent mechanisms process shearing and occluding motion.

Adolescent↗
PubMed1982

An allergy-clinical immunology training program for pediatric residents.

A four-week structured experience for pediatric residents in allergy-clinical immunology is described. Outlined are the educational goals and objectives developed by the teaching faculty in three areas: clinical allergy, clinical immunology and clinical laboratory aspects of allergy-immunology. Finally, assessment is made of the effectiveness of this approach to resident training.

California↗
PubMed1982

Isoetharine-isoproterenol: a comparison of effects in childhood status asthmaticus.

Eighteen children in status asthmaticus, six to 14 years of age, were systematically studied to compare the efficacy of aerosolized isoetharine and isoproterenol. The studies were conducted in a randomized, double-blind fashion. Five inhalations of 1% isoetharine and 0.5% isoproterenol were administered via a wall-mounted air/O2 nebulizing unit. Pulse, respiratory rate, blood pressure, FVC, PEFR, FEV1 and FEF25-75 were measured at the patient's bedside. Isoetharine produced significantly less cardiac side effect and tended to produce a greater improvement in pulmonary function than did isoproterenol. In addition, no change from baseline was noted in any of the parameters at 120 minutes following treatment with either medication.

Adolescent↗
PubMed1981

UV-induced changes in urinary polyamine excretion in the mouse.

Exposure of hairless mice to the light of a germicidal lamp (254 nm) under conditions which are known to induce epidermal DNA synthesis, cell proliferation, and polyamine metabolism produced a marked increase of polyamine excretion in the urine which lasted for many days. The increase was about the same for free and acetylated polyamines. Although the ratio of N1-acetylspermidine/N8-acetylspermidine increased somewhat in the urine of animals exposed to UV, the increase was not significant enough to be useful as a marker of enhanced cell proliferation. A single topical dose of alpha-difluoromethylornithine, a selective inhibitor or ornithine decarboxylase, prevented the UV-induced increase of polyamine excretion in agreement with its effect on UV-induced epidermal polyamine turnover.

Acetylation↗
PubMed1981

Lymphoid interstitial pneumonitis and hypogammaglobulinemia in children.

Lymphoid interstitial pneumonitis is an uncommon process, and an association with hypogammaglobulinemia in children is rare. Three patients, a 10-yr-old boy (Patient 1), a 17-yr-old girl (Patient 2), and a 13-yr-old boy (Patient 3) were evaluated for progressive interstitial pneumonitis and hypogammaglobulinemia. At presentation, symptoms or signs of lung disease had been present for 9, 6, and 1.5 yr and consisted of severe exertional dyspnea asymptomatic pneumonitis on roentgenogram, and mild exertional dyspnea, respectively. Serum immunoglobulin deficiencies were variable with IgG and IgA being depressed in all patients and IgM being within normal limits in Patient 2. In vitro neutrophil function and T lymphocyte number and mitogen responses were normal. Measurement of in vitro immunoglobulin production suggested a primary B lymphocyte dysfunction. Pulmonary function testing revealed restrictive lung disease in Patient 1, arterial hypoxemia in Patients 1 and 2, and increased alveolar-arterial oxygen differences in all patients. Microscopic examination of lung specimens from each patient revealed diffuse lymphoid parenchymal infiltration with formation of follicles with occasional germinal centers, varying degrees of fibrosis, and negative examinations for viruses, bacteria, and fungi. The factors responsible for the cessation of antibody production and for the striking lympho-proliferative process seen in these patients remain to be identified.

Adolescent↗
PubMed1981

A self-help program for childhood asthma in a residential treatment center.

A structured program designed to enhance self-treatment was successfully implemented in a residential center for asthmatic children. The ultimate objective of the program was to improve compliance with therapeutic regimens, which was felt to be a factor that had necessitated placement of many of the patients. The program was designed to educate the patient and the patient's family regarding the nature of asthma, its treatment and the importance of self-help. Efforts were also made to enhance the emotional maturity of the child. Patients remembered to take their medication over 90% of the time within 1 month of implementation of the program. a similar program was instituted for outpatient use.

Asthma↗
PubMed1981

Spatial bandwidth of channels for slant estimated from complex gratings.

Vertical sinusoidal gratings of slightly differing spatial frequencies presented to each eye lead to the perception of a slanted plane. If a complex pattern is created by presenting two different frequencies to one eye, while the other eye views an increment of one of those frequencies and a decrement of the other, then the stimulus is equivalent to two superimposed vertical planes slanted in opposite directions. Yet the observer generally sees only a single surface at a slant intermediate to the possible extremes. As the relative spatial-frequency content of the two opposing planes is varied, the observed slant is a measure of the strengths of the connecting interactions of the underlying stereomechanisms. From these data the bandwidth of the monocular input channels for the binocular slant mechanism can be estimated and is found to be about two octaves.

Humans↗
PubMed1981

Los Angeles air pollution and asthma in children.

Indices of air pollution, meteorological conditions and airborne allergens were correlated with emergency room census and hospitalizations for asthma at the Childrens Hospital of Los Angeles (CHLA) during a six-month period encompassing high and low periods of air pollution. In addition, patients in residence at the Sunair Home for Asthmatic Children (SHAC) were studied during a 10-day peak air pollution period. Increases in asthma emergency room visits and hospitalizations correlated significantly with increases in nitric oxide, coefficient of haze, hydrocarbons, Santa Ana wind conditions and total airborne allergen counts. Significant correlations were also found with decreases in ambient levels of O3, SO2, temperature and relative humidity. Among SHAC patients morning peak flow levels were significantly lower during the 10-day peak pollution period than during two control periods of low pollution. However, neither differences in clinical symptoms experienced by these patients nor their need for additional medication were observed.

Air Pollutants↗
PubMed1980

Immunological mechanisms in the maintenance of pregnancy.

Mmammalian pregnancy involves prolonged, intimate interactions between genetically dissimilar organisms. This dissimilarity evokes an immunological response in the gravida which promotes placental implantation and fetal viability. The nature of the immunological reactions, the factors moderating these responses and the signficance of abnormalities in the responses are discussed.

Animals↗
PubMed1980

Eosinophilia in the hospitalized neonate.

The incidence of and clinical associations with eosinophilia in a cross-section of hospitalized newborns had not been studied previously. The medical records of 200 such infants less than 29 days of age were reviewed. Total eosinophil counts were calculated and associations with a variety of clinical factors were examined. Eosinophilia (adjusted for day of age) occurred at least once in 22% of the infants studied. No significant skew could be detected in the age of onset of eosinophilia. Statistical analysis revealed eosinophilia to be significantly associated (p less than .05) with length of hospitalization, number of days of antibiotic therapy and use of parenteral alimentation. A trend toward eosinophilia was noted in lower birth weight infants (0.05 less than p less than 0.10). Eosinophilia was not associated with sex, age, Apgar score at birth, Caesarian section delivery, transfusions, phototherapy, specific diagnoses or type of oral feeding. Multiple regression analysis showed a highly positive correlation (r = .81) of associated factors with hospitalized days as the dependent variable. Eosinophilia appears to be a non-specific finding in sick neonates and is related to the severity of illness and the number of diagnostic or therapeutic procedures performed.

Aging↗
PubMed1979

Why rods and cones?

A key problem in vision is to normalize one's lightness scale so that surface reflectances are always assigned the same gray value regardless of the illumination level. The solution requires an assessment of the relation between the strength of the illuminant and the strength of the image signal-information that is not available in the image alone. However, the level of scattered light in the optical system does provide an independent measure of the illuminant strength, and can be used to solve the lightness scale normalization problem. To do this requires a comparison between two imaging systems, each of which respond differently to the internal optical scatter. The rod and cone systems have properties that are ideally suited for such a role.

Color Perception↗
PubMed1979

Fetal phenotypic expression by adult rat hepatocytes on collagen gel/nylon meshes.

Hepatocytes from adult rats were maintained in primary culture for up to 10-13 days on nylon meshes coated with a thin layer of rat tail collagen gel. Their ultrastructure closely resembled that of the liver parenchymal cell in vivo, but hepatocytes in late culture exhibited a pronounced buildup of microfilaments beneath their apical cell surface. Hepatocytes in early and late cultures secreted albumin, transferrin, and alpha1-acid glycoprotein into the medium; they exhibited a 7- to 10-fold induction of tyrosine aminotransferase activity by dexamethasone; and they expressed an alkaline phosphatase that was similar to that of normal rat liver with respect to its inhibition by the liver enzyme inhibitor L-homoarginine. In addition, the hepatocytes in culture demonstrated phenotypic changes characteristic of fetal liver parenchymal cells. These changes, which paralleled an increase in DNA synthesis, included the expression of and linear increase in the activity of the fetal liver cell enzyme gamma-glutamyl transpeptidase, an increased production of alpha1-fetoprotein, and a change in the substrate specificity of fructose-bisphosphate aldolase to that of the fetal liver isozyme.

Animals↗
PubMed1979

Review of intensive care unit admissions for asthma.

A review of ICU admissions for asthma to the Childrens Hospital of Los Angeles was conducted for the period January 1969 through July 1977. The admission rate remained relatively constant during this period. Patients requiring ICU admission tended to be young, intractable severe asthmatics whose asthma started at a very young age. There were three patients who had no previous history of asthma. The incidence of pneumonitis/atelectasis was somewhat greater than has been reported for patients hospitalized for status asthmaticus. A significant number of children received neither intravenous corticosteriods, sympathomimetics nor oxygen therapy while hospitalized prior to transfer to the ICU. Those children receiving mechanical ventilation or intravenous isoproterenol tended to be somewhat younger and had a higher incidence of pneumonitis/atelectasis and more abnormal blood gas determinations than their counterparts who were not similarly treated. Mechanical ventilation was administered to 15 patients and 19 patients received intravenous isoproterenol. Intravenous isoproterenol resulted in prompt improvement in most patients; except for one patient who experienced cardiac arrhythmia (reversed when the dosage was decreased), this medication was well-tolerated.

Adolescent↗