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Biomedical subjects

M Bina

Publications and source records attributed to M Bina.

At least 73 records · Page 4Linked to original sources
PubMed1982

Heavy metal-nucleotide interactions. 15. Reactions of calf thymus DNA with the electrophiles methylmercury(II) nitrate, cis-dichlorodiammineplatinum(II), and trans-dichlorodiammineplatinum(II) studied using Raman difference spectroscopy. Evidence for the formation of C-DNA upon metalation.

This study details the reactions of the electrophiles CH3Hg(NO3), cis-[PtCl2(NH3)2] (cis-DDP) and trans-[PtCl2(NH3)2] (trans-DDP) with calf thymus DNA using Raman and Raman difference spectroscopy. The order of CH2Hg(II) binding to calf thymus DNA is G greater than or equal to T greater than C greater than A. The electrophilic attack of cis- and trans-DDP on calf thymus DNA produces different orders of binding cis-DDP-G greater than C approximately A much greater than T, trans-DDP-G approximately C approximately A much greater than T. The reaction of CH3Hg(II) with DNA results in a decrease in the percentage of B-form DNA, whereas the reactions of cis-and trans-DDP with DNA decrease the percentage of B-DNA and cause the formation of C-DNA structure.

Adenosine Monophosphate↗
PubMed1980

Heparin-associated thrombocytopenia.

We studied the mechanism of platelet injury in 20 patients receiving heparin, three of whom became thrombocytopenic. Platelets from these three patients had increased levels of IgG and C3, which correlated with the presence of thrombocytopenia; their plasma caused the release of serotonin from normal platelets at concentrations of heparin within the usual therapeutic range. This reaction required IgG and an intact classic complement pathway. The 17 patients receiving heparin in whom thrombocytopenia did not develop had normal levels of platelet-associated IgG and C3. Plasma from 14 of these patients caused the release of serotonin, but only at heparin concentrations above the therapeutic range, in a reaction that also required IgG and complement. The addition of heparin to 15 normal plasma samples did not cause platelet injury in vitro. These studies indicate that heparin administration can be associated with complement-mediated platlet injury. The dose-dependent nature of this process may account for the occurrence of thrombocytopenia in some of these patients.

Aged↗
PubMed1980

Could poly(A) align the splicing sites of messenger RNA precursors?

In general, poly(A)-mRNA appears to be derived from larger nuclear RNA precursors. The maturation of these precursors involves excision of sequences of variable length from within the molecule and splicing of the remaining structural and coding sequences. The mechanism by which this process occurs is not known. It does not appear to operate solely through the recognition of a defined primary sequence or through the formation of a consistent secondary structure. We propose an alternative model in which poly(A) facilitates the splicing event by promoting the formation of triple-stranded structures within the mRNA precursor.

Animals↗
PubMed1980

Stability of DNA in nucleosomes.

Heats of thermal denaturation of chromatin core particles and core particles with covalently crosslinked histones were measured by differential scanning calorimetry. The additional stabilization of the nucleoprotein complex by crosslinking is not reflected in the transition enthalpy. The contribution of protein denaturation to the total heat was estimated by comparison of core particles with core particle DNA in a high-salt solution. By taking into account the temperature dependence of the transition enthalpy of DNA, we conclude that the enthalpy change for denaturation of DNA in core particles is nearly the same as that for naked DNA in solution.

Calorimetry↗
PubMed1979

Acidic polypeptides can assemble both histones and chromatin in vitro at physiological ionic strength.

We provide evidence that nucleosomes can assemble in vitro at physiological ionic strength (0.1-0.2 M NaCl/10 mM Tris . HCl, pH 8.0) in the absence of "assembly factors" and that poly(glutamic acid) greatly facilitates chromatin assembly under these conditions. We also show that in the presence of either poly(glutamic acid) or poly(aspartic acid), core histones assemble into octamers at physiological ionic strength. We suggest that it is a property of histones to assemble into octamers upon their interaction with macromolecules containing regions of high negative charge density, and we discuss several implications of this property.

Animals↗
PubMed1979

Infantile atlantooccipital instability. The potential danger of extreme extension.

During early infancy, adventitious sliding and slipping movements between the vertebral column and skull are possible in the cadaver. In ten of 17 infants, the posterior arch of the atlas inverted through the foramen magnum during extension of the head on the atlas, resulting in the anatomic potential of bilateral vertebral artery compression. These anatomic conditions may be the basis for a chain of events that contributes to death in some neonates and infants with conventioanl diseases and may be one source of unanticipated death.

Atlanto-Occipital Joint↗