Search PubMed⌕ Search

Biomedical subjects

H Santos

Publications and source records attributed to H Santos.

At least 109 records · Page 6Linked to original sources
PubMed1987

Proton NMR studies of horse ferricytochrome c. Completion of the assignment of the well resolved hyperfine shifted resonances.

1H NMR saturation transfer and nuclear Overhauser effect (NOE) measurements have been used together with two-dimensional spectra to complete the assignment of the well resolved hyperfine shifted resonances in the spectrum of horse ferricytochrome c and obtain their shifts in the reduced protein. New assignments include the beta-CH2 protons of Met-80, both ring protons of His-18, and the alpha-CH2 of Gly-29 and delta-CH2 of Pro-30, which resonate surprisingly far upfield despite the absence of any Fermi contact contribution to the shift.

Animals↗
PubMed1987

Syringosubarachnoid shunt for treatment of syringomyelia.

The experiences with a series of 9 patients with syringomyelia treated by syringosubarachnoid shunt (SSS) are presented. All of the cases were evaluated by myelography, CT scan or MNR. The cases showed satisfactory results which consisted in stabilization of the symptoms (55%) or clinical improvement (44%). These results should be continuously evaluated, due to the short follow-up period and to the variable natural history of the illness. Treatment by SSS is a technique of low morbidity. It is recommended for patients with syringomyelia without significant descent of the tonsils or in those cases where posterior fossa operations have failed to obtain good results.

Adolescent↗
PubMed1986

13C and proton NMR studies of horse cytochrome c. Assignment and temperature dependence of methyl resonances.

The 13C and proton chemical shifts of the 55 methyl groups of horse cytochrome c have been determined over a range of temperatures both in the diamagnetic ferrocytochrome and in the paramagnetic ferricytochrome. Specific assignments of many proton resonances have been published previously and all of the remaining methyl proton resonances are now specifically assigned. The corresponding 13C assignments follow directly, including those of contact shifted 13C resonances which are reported for the first time.

Animals↗
PubMed1986

Clinical and CT scan assessment of benign versus fatal spontaneous cerebellar haematomas.

We have studied 15 cases of spontaneous intracerebellar haematomas in 9 males and 6 females. A significant correlation between the clinical presentation and the CT scan features of benign and fatal haemorrhages of the cerebellum is presented. Diagnostic computerized tomographic studies were performed in a mean interval of 31 hours after the initial symptoms. 60% were diagnosed and treated in less than 24 hours; 11 patients had haematomas larger than 3 cm, and 5 (45%) of these cases died with evidence of irreversible brain-stem damage. Twelve (80%) showed compression of the fourth ventricle, 9 (60%) obliteration of the brain-stem cisterns and 8 (53%) ventricular dilatation. 8 cases were treated with surgery; 50% of them showed neurological improvement, including two cases with signs of brain-stem compression. 7 patients who were treated conservatively were followed closely with repeated CT scans, which showed that resolution of the mass effect and isodensity of the haematomas larger than 3 cm (73%), hydrocephalus (45%) and intraventricular haemorrhage (40%). Smaller haematomas without CT scan evidence of obliteration of the brain-stem cisterns or hydrocephalus had a better outcome.

Adult↗
PubMed1986

Traumatic false aneurysms of the middle meningeal artery.

The authors report a rare case of traumatic false aneurysm of the middle meningeal artery associated with a delayed contralateral extradural hematoma. The extradural hematoma was evacuated, and the pseudoaneurysm was removed to avoid delayed rupture. The literature on traumatic aneurysms is reviewed.

Adult↗
PubMed1985

13C-NMR studies of horse ferrocytochrome c. Assignment and temperature dependence of methyl resonances.

The 13C and proton chemical shifts of 53 of the 55 methyl resonances of horse ferrocytochrome c have been determined by editing natural abundance 13C spectra according to the number of attached protons, observing the temperature dependence of the chemical shifts, and correlating 13C and proton chemical shifts in two-dimensional spectra. Previous assignments of proton shifts allow 16 of the 13C resonances to be assigned firmly.

Animals↗
PubMed1984

NMR studies of electron transfer mechanisms in a protein with interacting redox centres: Desulfovibrio gigas cytochrome c3.

The proton NMR spectra of the tetrahaem cytochrome c3 from Desulfovibrio gigas were examined while varying the pH and the redox potential. The analysis of the NMR reoxidation pattern was based on a model for the electron distribution between the four haems that takes into account haem-haem redox interactions. The intramolecular electron exchange is fast on the NMR time scale (larger than 10(5) s-1). The NMR data concerning the pH dependence of the chemical shift of haem methyl resonances in different oxidation steps and resonance intensities are not compatible with a non-interacting model and can be explained assuming a redox interaction between the haems. A complete analysis at pH* = 7.2 and 9.6, shows that the haem-haem interacting potentials cover a range from -50 mV to +60 mV. The midpoint redox potentials of some of the haems, as well as some of their interacting potentials, are pH-dependent. The physiological relevance of the modulation of the haem midpoint redox potentials by both the pH and the redox potential of the solution is discussed.

Chemical Phenomena↗
PubMed1984

Thermodynamics of all-or-none water channel closure in red cells.

The relation of osmotic to diffusional water permeability of human red blood cells was compared after treating the cells with different concentrations of PCMBS (p-chloromercuribenzene sulfonate). After subtracting the PCMBS-insensitive permeability (presumably the water permeability of the lipid bilayer) from each, the ratio of osmotic to diffusional permeability remains invariant (approximately equal to 11) as more and more water channels are inhibited by increasing concentrations of PCMBS. This result implies that the channels close in an all-or-none way and suggests a two-state model. Analysis of the dependence of osmotic water permeability on PCMBS concentration in terms of the model reveals a 1:1 stoichiometry and a dissociation constant for the PCMBS/membrane receptor complex of about 0.019 mM at 37 degrees C. Temperature dependence studies show that the reaction is entropically driven (delta H degrees approximately equal to 25 kcal/mol, delta S degrees approximately equal to 100 cal/mol-deg) and suggest the involvement of hydrophobic interactions.

Cell Membrane Permeability↗
PubMed1982

Ferredoxin from Methanosarcina barkeri: evidence for the presence of a three-iron center.

Methanosarcina barkeri ferredoxin was purified and characterized by electron paramagnetic resonance (EPR) and Mössbauer spectroscopy. The purification procedure included chromatographic steps on DEAE-cellulose and gel filtration. The isolated protein is unstable under aerobic conditions. The ferredoxin exhibits charge transfer bands at 283 nm and 405 nm with an absorption ratio A405/A283 = 0.73. Its molecular weight has been estimated to be 20000-22000 by gel filtration chromatography. The native ferredoxin exhibits an intense EPR signal at g = 2.02 and only a very weak g = 1.94 signal develops upon reduction with dithionite. The Mössbauer spectra of the reduced protein are characteristic of a [3Fe-3S] center. The combined EPR and Mössbauer studies show that M. barkeri ferredoxin contains only [3Fe-3S] clusters, similar to Azotobacter vinelandii Fd[Emptage, M.H., Kent, T.A., Huynh, B.H., Rawlings, J., Orme-Johnson, W.H. & Münck, M. (1980) J. Biol. Chem. 255, 1793-1796], Desulfovibrio gigas FdII [Huynh, B.H., Moura, J.J.G., Moura, I., Kent, T.A., LeGall, J., Xavier, A.V. & Münck, E. (1980) J. Biol. Chem. 255, 3242-3244] and mitochondrial beef heart aconitase [Kent, T.A., Dreyer, J.-L., Kennedy, M.C., Huynh, B.H., Emptage, M.H., Beinert, H. & Münck, E. (1982) Proc. Natl Acad. Sci. USA, 79, 1096-1100].

Chemical Phenomena↗
PubMed1982

NMR redox studies of Desulfovibrio vulgaris Cytochrome c3. Electron transfer mechanisms.

The 300-MHz proton NMR spectra of the tetrahaem cytochrome c3 from Desulfovibrio vulgaris were examined while varying the pH and the redox potential. The analysis of the complete NMR reoxidation pattern was done taking into account all the 16 redox states that can be present in the redox titration of a tetra-redox-center molecule. A network of saturation transfer experiments performed at different oxidation stages, between the fully reduced and the fully oxidized states, allowed the observation of different resonances for some of the haem methyl groups. In the present experimental conditions, some of the haems show a fast intramolecular electron exchange rate, but the intermolecular electron exchange is always slow. In intermediate reoxidation stages, large shifts of the resonances of some haem methyl groups were observed upon changing the pH. These shifts are discussed in terms of a pH dependence of the haem midpoint redox potentials. The physiological relevance of this pH dependence is discussed.

Chemical Phenomena↗
PubMedDate not supplied

Metabolism of 3-(13)C-malate in primary cultures of mouse astrocytes.

Malate, specifically labeled with carbon 13 on C(3), was synthesized by chemical means and used to study malate metabolism by primary cultures of mouse cortical astrocytes. 3-(13)C-Malate in combination with glucose as well as 3-(13)C-malate alone were used as substrates; the effect of 3-nitropropionic acid, an inhibitor of succinate dehydrogenase and fumarase was also examined. The consumption of malate was only 0.26 micromol/mg of protein, approx. 25-fold lower than the consumption of glucose. Besides lactate, glutamine and fumarate were the two major metabolites released to the medium. Very low and similar levels of isotopic enrichment were detected on C(2) and C(3) of lactate; glutamine was labeled on C(2) and C(3) to a similar extent as well and labeling on C(4) was only detected when glucose was not added. These labeling studies suggest that cytosolic malic enzyme is not active in primary astrocytes and support the occurrence of pyruvate recycling in astrocytes.

Animals↗
PubMedDate not supplied

[Psoriatic arthritis].

The Psoriasis Arthritis witch was considered for many years as a late complication of the Psoriasis, is presently known as a chronical systemic disease, resulting w from the coexistence of a chronical evolutive poliarthropaty and a skin disease, the Psoriasis. The authors make a brief revision of the etiopathogeny, clinics and treatment of the Psoriasis arthritis and show a retrospective analysis of the clinical cases of 19 patients with Psoriatic Arthritis followed at the Medicine Consultation Reumathologie.

Adult↗