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Biomedical subjects

R A Rubin

Publications and source records attributed to R A Rubin.

51 records · Page 3Linked to original sources
PubMed1981

Partial NH2- and cooh-terminal sequence analyses of Eco RI DNA restriction and modification enzymes.

NH2- and COOH-terminal amino acid sequences of the Eco RI restriction and modification enzymes have been determined. The results allow localization of the coding regions within the DNA segment which controls activity of both enzymes. Processing of the endonuclease is limited to removal of NH2-terminal formylmethionine whereas, in the case of the methylase, formylMet-Ala is removed.

Amino Acid Sequence↗
PubMed1980

Infant neurological abnormalities as indicators of cognitive impairment.

In a prospective longitudinal study, 1319 children who had received three neurological examinations during their first year of life were administered measures of cognitive development and academic achievement up to and including 12 years of age. With both social class and birthweight statistically controlled, children identified as neurologically suspect or abnormal on more than one of the infant examinations (N = 22) consistently performed far below control children on measures of intelligence, motor skills, language development and school achievement. Children who had been neurologically suspect or abnormal on only one infant examination (N = 165) performed significantly less well than those never suspected of neurological abnormality in infancy (N = 1132).

Achievement↗
PubMed1980

Correlation of cerebrospinal fluid serotonin and altered spinal cord blood flow in experimental trauma.

Serotonin levels in the cerebrospinal fluid (CSF) were determined at various time intervals following experimental spinal cord trauma and correlated with alterations in the intramedullary blood flow. At one hour after injury, a significant elevation of CSF serotonin was noted to parallel a marked reduction in white matter perfusion. The correlation between elevated CSF serotonin and decreased blood flow in the traumatized spinal cord suggests that serotonin may have pathogenetic importance relative to posttraumatic alterations in the intramedullary microcirculation. The possible role of serotonin in the pathophysiology of blood flow changes following experimental spinal cord injury are discussed as are the therapeutic implications.

Animals↗
PubMed1978

Substrate dependence of the mechanism of EcoRI endonuclease.

The mechanism of EcoRI endonuclease is substrate dependent. At 37 degrees dissociation of the enzyme-Form II DNA intermediates of ColE1 DNA and bacteriophage G4 RFI DNA is negligible. Therefore, both DNA strands with in the EcoRI sequence are cleaved during a single binding event. However, double strand cleavage of SV40 DNA occurs without dissociation of the enzyme in only 75% of the catalytic events. This mechanistic difference presumably reflects sequence differences about the EcoRI sites of these DNA's.

Bacteriocin Plasmids↗
PubMed1977

Role of the 2-amino group of deoxyguanosine in sequence recognition by EcoRI restriction and modification enzymes.

The dG residues within the EcoRI recognition sequence of ColE1 DNA have been selectively replaced with dI. Methylation of the altered sequence by the EcoRI modification enzyme is extremely slow as compared with methyl transfer to the natural recognition site. Since the affinity of the modification enzyme for the dI-containing sequence is considerably less than that for the natural sequence, we have concluded that the 2-amino group of dG has an important role in DNA site recognition by this enzyme. In contrast, the altered site is subject to cleavage by EcoRI endonuclease at rates essentially identical with those observed with the natural sequence. These results strongly suggest that the two enzymes utilize different contacts within the EcoRI site and are consisted with our conclusion (Rubin, R. A., and Modrich, P. (1977) J. Biol. Chem. 252, 7265-7272) that the two proteins interact with their common recognition sequence in different ways.

Base Sequence↗
PubMedDate not supplied

Fast three-dimensional time-of-flight MR angiography of the intra-cranial vasculature.

Magnetic resonance angiography is most commonly performed with the three-dimensional (3D) time-of-flight (TOF) technique. As currently practiced, this requires long image acquisition times (5-10 minutes). The authors show that the acquisition time of 3D TOF images can be reduced to less than 1 minute by using a very short TR (< 10 msec). Under normal flow conditions, the major vessels of the circle of Willis were consistently well demonstrated on these fast 3D TOF images. Signal saturation was observed in studies of patients with abnormal blood flow. In those cases, it was demonstrated that serial acquisition of fast 3D TOF data during and after contrast agent administration could be used to overcome the saturation effects. Time-resolved fast 3D TOF imaging during and after contrast agent administration can also provide qualitative assessment of flow and may depict other features that cannot be observed in TOF studies with long imaging times.

Adult↗