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Biomedical subjects

H Sick

Publications and source records attributed to H Sick.

At least 73 records · Page 4Linked to original sources
PubMed1979

Co-binding studies on Hb M Iwate. Allostery of a T state haemoglobin.

The mutant haemoglobin Hb M Iwate alpha 2Mmet87His leads to Tyr beta 2, is characterized by a stable T structure and a low ligand affinity. Sigmoidal CO-binding isotherms of symmetrical shape with Hill coefficients of n = 1.4 at pH 6 to n = 1.9 at pH 10 and the differences in the mean affinity (PCO(1/2)) and the affinity of the first ligand-binding beta subunit (1/L1 greater than Pco(1/2)) are the evidence for the cooperativity. The comparison of the Bohr effects of the two valency hybrid states (alpha 2Mmet beta met beta deoxy alpha 2Mmet beta 2deoxy) in the absence of and in the presence of polyphosphates leads to an indirect proof of pH-dependent subunit-subunit interaction. Inositol hexaphosphate-binding suppresses cooperativity in the pH range 5.5-8 (n = 1). Above pH 8 hte cooperativity increases to a final value of n = 1.9 at pH greater than 10, which is identical to that of stripped Hb M Iwate. The CO binding to the first binding site exhibits a Bohr effect. Polyphosphate anions have no influence on the CO binding of the first binding site. The heterotropic effects are discussed as intrachain effects (Bohr effect of the first binding site) and interchain effects (Bohr effect of Pco(1/2); influence of polyphosphates).

Allosteric Regulation↗
PubMed1978

Acid Bohr effects in myoglobin characterized by proton NMR hyperfine shifts and oxygen binding studies.

Proton NMR studies of sperm whale and horse deoxymyoglobin have revealed that both proteins exhibit a single, well defined, pH-induced structural change. The changes in hyperfine shifts are clearly observed not only at the heme peripheral substituents, but also at the proximal histidyl imidazole, which suggest that heme-apoprotein contacts are looser in the acidic than alkaline conformations. The hyperfine shift changes are modulated by a single titratable group with a pK of approx. 5.7 in both proteins. Oxygen binding studies of sperm whale myoglobin over a range of temperature and pH showed that, while the oxygen affinity was independent of pH at 25 degrees C, it increased below pH 7 at 0 degrees C and decreased below pH 7 at 37 degrees C. Hence, sperm whale myoglobin exhibits a small acid Bohr effect which most likely arises from the characterized structural changes in the deoxy proteins. While horse myoglobin failed to exhibit a resolvable acid Bohr effect between 0 and 37 degrees C, it did show a weak alkaline Bohr effect at 25 degrees C which disappeared at lower temperatures. Since the oxygen affinity changed smoothly over several pH units, this alkaline Bohr effect can not be associated with any well defined conformational change detected by NMR.

Animals↗
PubMed1978

Bone marrow necrosis. acute microcirculation failure in myelomonocytic leukemia.

We saw bone marrow necrosis in a case of acute myelomonocytic leukemia. The diagnosis was made during the patinet's life, and the bone marrow microcirculation was studied immediately postmortem. Histology and injection of the bone marrow arteries showed an acute microcirculation failure. The pathogenesis and possible relationship with soluble immune complexes was studied.

Adult↗
PubMed1977

[Comparative study of the regeneration of the microcirculation of rabbit femur bone marrow after curetage and at the time of experimental myelosclerosis].

Destruction and regeneration of the bone marrow microcirculation in rabbit femur have been studied after curetage and experimental myelosclerosis. Different lesions lead to comparable restoration processes such as: installation of supplying vascular networks, appearance of a neovascularisation progressively replaced by neighboring structures of normal interadipocytic networks.

Animals↗
PubMed1976

[The 7th sterno-costal articulation (author's transl)].

A study of 200 human thoracic anterior walls (150 of adults and 50 of children) allows to distinguish 3 types of articulations at the internal extremity of the 7th costal cartilage: a lateral sterno-costal articulation, a prexiphoïdian sterno-costal articulation and an articulation between the two 7th costal cartilages. Each type may or may not have an articulating space. The only diarthrodial articulating spaces are found at the level of the articulation between the two 7th costal cartilages. All the other articulations may be considered as symphyses which, with age, may present a non-synovial space. The different types of articulations vary with age, the 7th cartilages being closer together in the child than in the adult. In the child there is a characteristic vascular network between the sternum and the 7th costal cartilages.

Adolescent↗
PubMed1976

[Vascularization of the sternoclavicular articulation (author's transl)].

The vascularization of 110 Human sternoclavicular articulations is studied after injection of China ink with gelosa. The arteries of the sternoclavicular articulation arise from the internal mammary arteria and form a periarticular arch from which start the peripheric, sub-synovial and central networks. These networks, whose architectony is in relation with the functional structure of sternoclavicular articulation, drains in peripheric venous arches which join anterior jugular and mediastinal veins.

Adolescent↗
PubMed1974

[Vascularization of the human adult sternum (author's transl)].

The study of the vascularization of the sternum allows to individualise the vascular pedicles, the anterior and posterior peripheral sternal networks and the intrasternal vascularization. 1. The numerous vascular pedicles of the sternum all come from the internal mammary arteries. The postero-superior and postero-inferior sternal arteries of one simple intercostal space or of contiguous spaces are anastomosed by systems of latero-sternal, retroarticular and retro-sternal arches. From these arches come vessels which go directly to the sternum or which form the posterior peripheral sternal network. The anterior sternal branches of perforating arteries form arches or go directly to the anterior peripheral sternal network or to the sternum. The veins are less anastomosed than the arteries and therefore their arches are less distinct. 2. The anterior and posterior peripheral sternal networks are especially developed with respect to the lower half of the body of the sternum at the level of the 4th and 5th intercostal spaces. The posterior network is more developed than the anterior network. The arteries often have a spiral course, their anastomoses occur with their contralateral and homolateral homologues. The veins, which are of larger calibre than the arteries, design a denser and more irregular network. 3. The intra-skeletal vascularization, tributary of the peripheral networks, arches and branches of the internal mammary vessels, includes a network of the compact bone and a medullary network. The network of the compact bone, situated in one plane, is composed of polyhedral elongated meshes, according to the large axe of the sternum. The medullary network may be divided into a sub-cortical and a centro-medullary part. The sub-cortical part is composed of a peripheral zone and a more central zone. The totality of the intramedullary network includes a few fine arteries, an interadipocytary network, which is very developed and is variable in form. It also include sinuses of increasing order connected into the venous system, into the network of the compact bone, or into the large trans-cortical veins, which are drained by the peripheral sternal networks or by the collateral veins or the internal mammary system.

Adolescent↗
PubMed1974

[Vascular regeneration of rabbit femoral bone marrow after curettage (author's transl)].

The curettage of a section of bone marrow in rabbit femur entails the destruction of the corresponding vascularization. Starting on the first day the undistroyed interadipocytic network is widely open. It is fed: 1. via those branches of the nutrient artery that stay connected; 2. via branches of the nutrient artery that become disconnected and then form anastomosis with the epiphysial arteries or compact bone arteries and thus become revascularized; 3. via the arteries vascularizing compact bone. By the thirds of fourth day after intervention, both poles of the hematoma are lined by vascular caps. This is composed of a rich network neo-vessels showing three distinct levels. After four or five weeks these networks will have come together and anastomosed. Between the hematoma and the compact bone tissue large vascular lacunae are formed. They receive blood from the arteries of the compact bone. The vascular networks drain into the veins of diaphyseal compact bone or are drained via intact vestiges of the central venous sinus. In those areas where the hematoma is reabsorbed, a partially reconstructed vascular tree appears. Peripheral longitudinal arteries send out centripetal rami towards the central vascular buds as well as centrifugal rami towards subcortical vascular buds. The interdipocytic network also regains its normal morphology. The central venous sinus extends from one epiphysis to the other and is usually drained into the veins of the trochanteric fossa proximally and into the popliteal veins and supra-trochlear veins distally.

Animals↗