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Biomedical subjects

A Carano

Publications and source records attributed to A Carano.

At least 37 records · Page 2Linked to original sources
PubMed1989

Cytoplasmic pH is regulated in isolated avian osteoclasts by a Cl-/HCO3- exchanger.

Osteoclast resorb bone in an acid compartment formed by the bone-attachment site. The low pH of the resorption compartment provides a lysosome-like milieu suitable for acid proteases to degrade collagen. Solubilization of the hydroxyapatite that makes up bone mineral consumes about 2 moles of protons per moles of calcium dissolved, requiring a massive proton flux to maintain a low pH in the resorption compartment. In order to determine how the osteoclast maintains a physiological cytoplasmic pH while secreting massive amounts of acid, we studied the intracellular pH of osteoclasts using esterified fluorescein derivatives while controlling the electrolyte composition of the medium. The principal finding is that osteoclasts have a high capacity for chloride/bicarbonate exchange which enables them to maintain normal intracellular pH in the face of a large loading of base equivalents. Thus, the overall process of proton secretion during bone resorption is similar to the polarized acid elimination by renal epithelia, involving a proton pump on one surface of the cell, and a Cl-/HCO3- exchange to maintain cytoplasmic pH.

Acid-Base Equilibrium↗
PubMed1989

Immunolocalization of beta 3 subunit of integrins in osteoclast membrane.

Utilizing isolated and cultured osteoclasts it has been possible to establish that they adhere to the substrate through specialized close contact areas, the podosomes, that in fully spread osteoclasts in vitro or in vivo are located within the clear zone. The cytochemical organization of podosomes has further been investigated in order to elucidate their possible involvement in the control of substrate recognition, that precedes bone resorption. An immunofluorescence investigation, performed utilizing human osteoclasts, shows that the beta 2 integrin subunit that in human monocytes is expressed and located in podosomes is absent in human osteoclasts, while the beta 3 subunit of the vitronectin receptor is expressed by osteoclasts, but not by other monocyte-derived cells and colocalizes with vinculin around the actin core of the podosome. The beta 1 subunit of the fibronectin receptors is also found, but with a diffuse pattern, in the osteoclast membrane. These results indicate that podosomes, while present in different cell types, may have in the osteoclast an unique cytochemical organization related to the peculiar function of this cell.

Bone Resorption↗
PubMed1988

Effect of vitamin A on bone resorption: evidence for direct stimulation of isolated chicken osteoclasts by retinol and retinoic acid.

The effects of retinol (vitamin A) and retinoic acid on primary cultures of isolated chicken osteoclasts have been studied. The experiments were performed to establish the direct actions of these two agents on the organization of cytoskeletal structures, on the acid phosphatase contents, and on the bone resorption activities of these cells. The results showed that by treating the cultures with retinol or retinoic acid, from 10(-8) to 10(-5) M, there were dose-related responses of the osteoclasts. Adhesion to the substratum was stimulated by increasing the number of cells exhibiting the specialized dot-like adhesion structures, or podosomes, which represent the active part of the sealing zone. The treatments also induced rearrangement of the microtubular patterns with reversible depolymerization of microtubules. Acid phosphatase activity was significantly higher both in vitamin A-treated osteoclasts and in their media. When [3H]proline-labeled bone particles were added to the retinoid-treated osteoclasts, the release of [3H]proline was increased significantly compared to controls. These results suggest that the two vitamin A metabolites cause several modifications of the metabolic status of isolated osteoclasts that result in augmented rates of bone resorption.

Acid Phosphatase↗
PubMed1988

The distribution of podosomes in osteoclasts cultured on bone laminae: effect of retinol.

Osteoclasts, isolated and purified from the medullary bone of calcium-deficient egg-laying hens, adhere to glass coverslips in vitro by means of specialized protrusions of the ventral membrane, denoted podosomes. These structures represent dotlike close-contact adhesion sites in which most cytoskeletal proteins involved in linking the plasma membrane to microfilaments are organized according to a specific and previously described pattern also shared by many oncogene-transformed cells. We show now that podosomes are not only a feature of osteoclasts adhering to artificial glass surfaces but are also present in the ventral membrane of osteoclasts adhering to bone laminae. Moreover, the quantity and the topography of podosomes may be modulated by retinol, which increases bone-resorbing activity of osteoclasts both in vivo and in vitro. A comparative transmission electron microscopy study of osteoclasts adhering on bone laminae in vitro or in vivo indicates that podosomes with identical features are present in the clear zone of the osteoclasts in either condition. Since podosomes are the sealing structures of the clear zone, podosome formation may represent one of the modifications involved in the reorganization process of the osteoclast that precedes bone resorption.

Acid Phosphatase↗
PubMed1988

The effects of parathyroid hormone or 1,25-dihydroxyvitamin D3 on monocyte-osteoclast fusion.

3H-thymidine-labeled blood monocytes were cultured with osteoclasts in the presence or absence of parathyroid hormone or 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in order to evaluate (1) the percentage of monocytes capable of fusing with osteoclasts, (2) if parathyroid hormone or 1,25(OH)2D3 influences the contribution of blood monocytes to osteoclast nuclear turnover. We found that within 24 hours of culture, about 8% of blood monocytes fuse with osteoclasts regardless of the presence of parathyroid hormone (PTH) or 1,25(OH)2D3. On the other hand, formation of non-osteoclastic giant cells by fusion of monocytes is enhanced by 5 x 10(-9) M 1,25(OH)2D3 but only in the presence of the bone resorptive cells.

Acid Phosphatase↗
PubMedDate not supplied

Effect of mirtazapine on thyroid hormones in adult patients with major depression.

Hypothalamic pituitary thyroid (HPT) axis abnormalities and alterations in major depression are reported in the literature. The aim of our study was to evaluate the effect of mirtazapine on thyroid hormones after 6 months of therapy in a sample of adult outpatients with Major Depression (MD). 17 adult outpatients (7 men, 10 women) with MD according to DSM-IV criteria, were included in the study. All participants had to have met criteria for a major depressive episode with a score of at least 15 on the Hamilton Depression Rating Scale (HAM-D). Fasting venous blood samples were obtained for determination of serum Thyroid Stimulating Hormone (TSH), Free T3 (FT3) and Free T4 (FT4) concentrations both at baseline and after 6 months of therapy. HAM-D scores decreased significantly from the first day of treatment to the end of the treatment period (P<0.001) and twelve patients (70.6%) were classified as responders. A significant increase in FT3 concentrations was found between baseline and the end of the treatment period (P=0.015), whereas FT4 concentrations decreased (P=0.046). No significant changes were found in TSH levels. Higher FT4 concentrations at baseline predicted higher HAM-D scorers both at baseline and at the end of the treatment period. Furthermore, higher FT3 concentrations at endpoint were found to be predictors of lower HAM-D scores. Long-term treatment with mirtazapine increases FT3 levels and decreases FT4 maybe involving the deiodination process of T4 into T3.

Adult↗
PubMedDate not supplied

The role of C-reactive protein in mood disorders.

Recently, a possible relationship between C-Reactive Protein (CRP), a marker of underlying low-grade inflammation, and mood disorders has been proposed by some researchers. The aim of this review is to elucidate the current facts and views about CRP in mood disorders such as Depressive and Bipolar Disorders. Several studies have examined the relationship between affective disorders and CRP, but the majority of the studies in literature have been limited by retrospective, case-controlled study design, and very few studies have examined the relationship between depression and CRP in large study samples. In conclusion, the role of CRP in mood disorders is, to date, intriguing but somewhat unclear. Further prospective studies are needed to introduce the CRP in clinical settings as a marker of affective states and suicidability.

C-Reactive Protein↗
PubMedDate not supplied

[Use of the perpendicular vertical in cephalometric analysis].

Cephalometric analysis is a useful diagnostic tool in orthodontics. The intracranial planes, commonly used as reference lines for cephalometric measurements, are not constant in the population. The variation of these references could constitute source of diagnostic error. On the light of this potential errors, the use of the vertical to the ground (or of its perpendicular line, orizzontal to the ground) constitutes a better reference for cephalometric measurements. The advantage of the vertical as reference is represented by its consistency in the same individuals and between different subjects.

Adolescent↗
PubMedDate not supplied

[Distalization of molars with magnets: biomechanical considerations].

Repelling magnets have recently been proposed to move maxillary molars distally. Although the technique presents some clinical indications, the biomechanics of tooth movement with magnets has not been clearly investigated. The results of the Author's experience suggest that the repelling magnets mainly generate a tipping movement of the crowns on the sagittal plane. The distal-tipping of the molars represents almost 50% of the total effect, the mesial tipping of the bicuspids-cuspids-incisors constitutes the remaining 50%. Also, on the horizontal plane, the force generated by the magnets tends to rotate the crowns of the molars palatally.

Adolescent↗
PubMedDate not supplied

[Biomechanical view of the histology of the TMJ].

Several reasons could explain the confusion and controversy that reign over every aspect of temporomandibular joint dysfunction. The discord includes not only diagnosis and treatment of the dysfunction, but even involves the anatomy and the histology of the TMJ. Different data in the literature indicate the major role of the biomechanical influences on the histology of the temporomandibular joint and on the adaptability of its structures. On the basis of these concepts, the histology of the TMJ has been revisited and a new functional interpretation of the microscopic morphology of the condyle, disc and periarticular connective tissue has been described.

Biomechanical Phenomena↗
PubMedDate not supplied

[A new experimental approach to the study of mechanical force in orthodontics].

Orthodontics is based upon the cellular response to biomechanical forces. Unfortunately, however, little is known about the manner in which cells respond to such forces. We have, therefore, devised an experimental model to permit morphologic and metabolic characterization of human cells subjected to a range of cyclic or static mechanical stimuli similar to those which may prevail in orthodontic-orthopedic therapy. This system involves attachment of cells to silicon collagen coated membranes which are then subjected to continuous or cyclic stretching by a motor coupled to a movable supporting frame. Because collagenase is an enzyme likely to play an important role in the ultimate effect of orthodontic forces, we evaluated the impact of biomechanical forces on secretion of this protein in a new experimental model in vitro. We found that cyclic stretching of human fibroblasts over a four day period approximately doubles collagenase production as compared to the control. Continuous stretching, on the other hand, is only 50% as effective in enhancing the enzyme release. In contrast, secretion of the inhibitor of metalloproteinases (collagenase inhibitor) is uneffected by either form of mechanical forces. Thus, the mechanical forces applied upon fibroblasts in this system promote gene expression in favor of matrix degradation. This model, we believe, will offer major insights into the cellular basis of orthodontics.

Cells, Cultured↗
PubMedDate not supplied

[Relationship of the articular eminence and the occlusal plane in TMJ dysfunction].

Previous cephalometric studies do not adequately evaluate or determine anatomical features that characterize patients who are affected by temporomandibular dysfunction. The findings from this research appear to document a distinct correlation between the articular eminence and the posterior occlusal plane between symptomatic or asymptomatic patients. The eminence-occlusal plane angle is statistically smaller in the dysfunctional TMJ group than in the normal TMJ group. No other distinctive features are found in conventional cephalometric measurements between the two groups. The use od the eminence-occlusal plane angle could be necessary in the orthodontic practice and in the temporomandibular management to evaluate potential or actual TMJ problems.

Adolescent↗
PubMedDate not supplied

[Continuous and intermittent mechanical forces in orthodontics].

Orthodontics is based upon the cellular response to biomechanical forces. To better investigate about the manner in which cells respond to such forces, we have devised an experimental model to permit morphologic and metabolic characterization of human cells subject to a range of cyclic or static mechanical stimuli similar to those which may prevail in orthodontic-orthopedic therapy. The most recent data in the literature indicated that cyclic forces could have bigger effect on cells than continuous ones. To better understand the rationale of the cyclic force effect, a morphological study on human fibroblast was performed. We found that stretching or compression delivered an immediate and proportional deformation on cells. After 10-15 minutes the morphology of cells readapt to the new mechanical environment, this causing the lost of the biological activation. A new mechanical stimuli should be necessary to determine a new biological reaction.

Cells, Cultured↗