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Biomedical subjects

R F Goldstein

Publications and source records attributed to R F Goldstein.

24 records · Page 2Linked to original sources
PubMed1984

Tunneling in Chromatium chromatophores: Detection of a Hopfield charge-transfer band.

We have observed a weak charge-transfer band in the cytochrome c-P(870) electron-transfer reaction in Chromatium vinosum chromatophores at 10 K and at 85 K. First, the intermediate acceptor, I, was trapped in the reduced state by lowering the redox potential at room temperature, then illuminating with white light at low temperature for 20 min. Next, illumination by broadband infrared (1-3 mum, 6.5 kW/m(2)) for 4 hr at 10 K decreased the I(-) electron spin resonance signal by 30%. One-hour infrared illumination at 85 K decreased the cytochrome c Soret band shift by 10%. The effect of infrared was to promote the system from the ground vibrational state with the electron on P(870) to an excited vibrational state with the electron on cytochrome c. The absorption band peak is near 2 mum, and the integrated cross section is approximately 6 x 10(-3) eV.M(-1).cm(-1). These values are consistent with small (0.02 nm) nuclear motion and with electron-transfer rates measured in the dark.

Journal Article↗
PubMedDate not supplied

Effect of endotracheal continuous positive airway pressure on sensitivity to carbon dioxide and on respiratory timing in preterm infants.

To determine the effects of continuous positive airway pressure (CPAP) on ventilatory response to CO2 and inspiratory and expiratory duration in preterm infants, 24 preterm infants with an average birth weight of 1220 g were studied at a mean age of 10.6 days. CPAP was applied via an uncuffed endotracheal tube. Testings were performed between ambient pressure and a positive airway pressure of 10 cm H2O. Approximately 2/3 of the applied pressure was transmitted to the esophagus. All infants demonstrated a ventilatory response to carbon dioxide of less than 50 ml/min per mm Hg Pco2 at ambient pressure, and no infant showed significant improvement at increasing levels of CPAP. Drive to breathe, as reflected in the inspiratory flow rate (Vt/Ti) also failed to change significantly. It may be concluded that in the apparent absence of significant changes in lung volume, CPAP fails to increase sensitivity to CO2 in preterm infants recovering from hyaline membrane disease.

Carbon Dioxide↗
PubMedDate not supplied

Dynamic light scattering investigations of RecA self-assembly and interactions with single strand DNA.

Dynamic light scattering (DLS) measurements were performed on self-assembled solutions of RecA as a function of assembly time under strand exchange ionic strength conditions (10 mM MgCl2, 65 mM NaCl, 10 mM Tris-HCl, pH = 7.5, 1 mM DTT, 3-4 microM RecA) in the absence of ATP. These measurements yield distributions of the translational diffusion coefficients of the changing populations of assembling protein species. Interpretations of results of DLS measurements are made in terms of model hydrodynamic calculations that indicate, under the solution conditions employed, the smallest fundamental quaternary subunit of RecA is a hexamer in a toroidal or lock-washer configuration. Interactions of M13mp19 circular single strand DNA (ssDNA) with RecA assembled to different stages were also investigated. Additions of ssDNA to self-assembled solutions of RecA acts to dissociate the associated structures into hexamer subunits. However, the effect of ssDNA on assembled RecA is highly dependent on the RecA self-assembly state. The longer the assembly time, the less reversible the self-assembled structures of RecA become. Binding isotherms of titrated mixtures of ssDNA with RecA self-assembled to various stages were also determined. Evaluated dissociation constants of RecA/ssDNA complexes were found to increase with increases of the associated state of RecA. These results strongly suggest that, under the solvent conditions employed, the active ssDNA binding form of RecA is a hexamer.

Adenosine Triphosphate↗
PubMedDate not supplied

Neurodevelopmental and health outcomes in term infants treated with surfactant for severe respiratory failure.

OBJECTIVE: Analysis of health, neurodevelopmental, and school performance outcomes in a pilot study of term and near-term infants with respiratory failure due to pneumonia or meconium aspiration treated with surfactant. STUDY DESIGN: Retrospective review of medical records, neurodevelopmental and psychosocial evaluations, and parent and teacher surveys. RESULTS: Of the 14 patients enrolled, only one was rehospitalized, for pneumonia. Three were reported to have episodes of wheezing, two of whom required bronchodilators. One patient had unilateral hearing loss, one had a full-scale intelligence quotient that was below normal, and all but one patient for whom complete results were obtained were performing at or above grade level. CONCLUSION: Term and near-term newborns with moderately severe respiratory failure treated with surfactant can, in general, be expected to recover completely and have normal general health, neurodevelopmental outcome, and school performance.

Achievement↗
PubMedDate not supplied

Behavioral characteristics of very-low-birth-weight infants of varying biologic risk at 6, 15, and 24 months of age.

OBJECTIVE: To explore the relationship between developmental outcome and behavior of very-low-birth-weight (VLBW) infants (< or = 1500 g) at high and low biologic risk. DESIGN: Descriptive, ex post facto. SETTING: Clinic for follow-up of infants at high risk. PARTICIPANTS: A convenience sample of 102 VLBW infants, free of major congenital anomalies, who completed 6-, 15-, and 24-month developmental testing and who were part of a larger study of 274 VLBW infants. MAIN OUTCOME MEASURE: Bayley Scales of Infant Development. RESULTS: Infants at high biologic risk, versus infants at low biologic risk, were less attentive and active through age 15 months and were less adept in gross and fine motor skills through age 24 months (p < or = 0.05-0.001). Infants with continuous delay were less attentive than infants with no delay or late delay through age 24 months, less active through age 15 months (p < or = 0.001-0.001), and less skilled in motor behaviors through age 24 months (p < or = 0.05-0.001). CONCLUSION: Infants at high biologic risk and infants with developmental delays are less attentive, less active, and less skilled in motor tasks during the first 15-24 months of life, suggesting an association between biologic risk and behavior and developmental delay and behavior.

Analysis of Variance↗