Search PubMed⌕ Search

Biomedical subjects

T Richards

Publications and source records attributed to T Richards.

At least 91 records · Page 5Linked to original sources
PubMed1994

Modified bovine surfactant (Survanta) versus a protein-free surfactant (Exosurf) in the treatment of respiratory distress syndrome in preterm infants: a pilot study.

We undertook a prospective, randomized, non-blinded pilot study to determine whether infants with respiratory distress syndrome (RDS) who were treated with protein-containing bovine surfactant (Survanta, Ross/Abbott Laboratories, Columbus, Ohio) had earlier and larger responses in gas exchange when compared with similar infants treated with a synthetic surfactant (Exosurf, Burroughs Wellcome, Research Triangle Park, North Carolina). Forty-one infants weighing between 600 g and 1750 g at birth with RDS of sufficient severity to require assisted ventilation with an FiO2 > 0.39 were enrolled in the study and treated with surfactant from 1 to 8 hours after birth. Infants were randomly selected to receive treatment with either Exosurf or Survanta. Despite randomization, the Survanta group was overrepresented with factors associated with greater severity of RDS (lower birthweight, more males, and fewer African Americans). No statistically significant difference was found in the primary outcome measure (arterial/alveolar PaO2 > 0.3 at 24 hours) by univariate or multivariate analysis. The percentage of responders in the Survanta-treated group was significantly increased 24 hours after treatment in two of four secondary measures of oxygenation when analyzed by univariate tests using one-tailed P values. Based on these results, we anticipate that acute outcomes after Survanta or Exosurf will approximate those found in this trial and that differences in measures of oxygenation between treatment groups will approximate 30% to 50% 24 hours after initial treatment.

Biological Products↗
PubMed1993

Self-reported drug use data: what do they reveal?

The purpose of this study is to examine self-reported marijuana and cocaine use responses from two nationally representative surveys. We compared prevalence rates across birth cohorts for multiple years of the National Household Survey of Drug Abuse (NHSDA) and also analyzed longitudinal inconsistencies in self-reported drug use between two waves of the National Longitudinal Survey Youth Cohort (NLS-Y). We found the percentages of respondents admitting use within the past month, year, and lifetime were comparable to other findings and were consistent with the declining trend in drug use in the late 1980s. A comparison of lifetime prevalence rates revealed seemingly inconsistent reports between 1985 respondents and their birth cohorts in 1990. Using the longitudinal NLS-Y data, we found that roughly one-fifth of the people who had admitted using marijuana or cocaine in their lifetime on the 1984 survey subsequently denied ever having used in 1988. The majority of these cases were people who reported having used infrequently. The subsample of women had similar patterns. In addition, we discovered that women who had been pregnant between the two surveys were more likely to inconsistently deny having ever used, while those who were currently pregnant responded more honestly about their past use. Overall, we found that although most people are willing to provide accurate accounts of their use, the researcher should be aware that under-reporting or complete denial does occur. Most importantly, external factors appear to contribute to the rate of inaccurate reporting.

Adolescent↗
PubMed1990

Marking times.

Explore the source record for details and available documents.

History, 19th Century↗
PubMed1990

The superior intracapsular ligament of the sacroiliac joint: presumptive evidence for confirmation of Illi's ligament.

The existence of a superior intracapsular ligament within the sacroiliac joint has been disputed for years. This study notes that the dissection technique used to open the sacroiliac joint is of critical importance in finding this ligament. A dissection technique that emphasizes an inferior approach to the joint cavity is described. A superior intracapsular ligament of the sacroiliac joint (Illi's ligament) is noted with a 75% frequency in dissected cadavers. Illi's model for motion of the sacrum was based partially on the function of this ligament. The findings of this study suggest that current models of motion at the sacroiliac joint must include the presence of a superior intracapsular ligament.

Anthropometry↗
PubMed1988

Biochemical and pathological features of a modified strain of Watanabe heritable hyperlipidaemic rabbits.

A modified strain of heritable hyperlipidaemic rabbit has been produced by crossing male albino rabbits homozygous for low density lipoprotein receptor deficiency into a coloured commercial colony with strong breeding characteristics. The genetic deficiency has been preserved in the resulting offspring through many generations. Litter numbers, live weight gains and energy intake are similar to normal rabbits. Free and esterified cholesterol in serum, and total cholesterol in very low density plus low density lipoproteins, are markedly increased in homozygote, but only slightly raised in heterozygote, animals. High density lipoprotein-cholesterols show an opposite trend but with less marked differences between the genetic strains. Liver total and esterified cholesterol levels were substantially increased in homozygotes, and the ability of liver membranes to bind human 125I-LDL was markedly reduced, owing to a reduction of the number of high-affinity binding sites. All animals with serum cholesterol values greater than 14 mmol/l at weaning developed extensive aortic atherosclerosis within 16 weeks. The early lesions had the histological appearances of fatty streaks and progressed to complicated disease at 6-12 months. A distinctive pattern of calcific arteriosclerosis, quite different from atherosclerosis, was observed in most aging heterozygote animals and was associated with extensive renal calcium deposition. Corneal arcus developed in some homozygotes but there was no evidence of cerebral atherosclerosis. We conclude that homozygotes of this modified strain can be used for macroscopic studies of the progression of aortic atherosclerosis in the first 4 months after weaning but after this period a combination of macroscopic and microscopic techniques are required. Heterozygotes are unsuitable for studies of this nature.

Animals↗
PubMed1988

NMR imaging and spectroscopy of the mammalian central nervous system after heavy ion radiation.

NMR imaging, NMR spectroscopy, and histopathologic techniques were used to study the proton relaxation time and related biochemical changes in the rodent brain after in vivo helium beam irradiation with single doses of 10, 20, 30, and 50 Gy. Two-dimensional Fourier transform spin-echo imaging and saturation recovery with projection reconstruction were used to measure the NMR relaxation parameters. These parameters were correlated with proton spectroscopy and histopathology. Additional high resolution in vitro proton spectroscopy was performed on brain extracts to observe chemical changes that could not be seen in vivo. The major findings from these experiments were that at 4-14 days postirradiation, image intensity and T1 relaxation time decreased on the irradiated side and increased on the nonirradiated side relative to nonirradiated control animals. In vivo surface coil proton spectroscopy methods demonstrated changes in lipid and phosphatidylcholine (p-choline) peaks. In vitro studies of the aqueous fraction of brain extracts showed radiation-induced changes in lactate, 4-aminobutyric acid, and p-choline peak areas. In the organic fraction, radiation-induced changes were observed in phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. With histology and Evans blue injections, blood-brain barrier alterations were seen as early as 4 days after a dose of 50 Gy.

Animals↗
PubMed1987

Seconds may count.

Explore the source record for details and available documents.

Fibrinolytic Agents↗