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Biomedical subjects

G Baldini

Publications and source records attributed to G Baldini.

At least 37 records · Page 2Linked to original sources
PubMed1997

Rab 3D in rat adipose cells and its overexpression in genetic obesity (Zucker fatty rat).

Members of the Rab 3 subfamily of low-molecular-mass GTP-binding proteins have been functionally implicated in regulated exocytosis. The aim of the present study was to examine the subcellular distribution of a member of this family, Rab 3D, in rat adipose cells, given the hypothesis that this protein might be involved in insulin-stimulated GLUT4 exocytosis. We show that Rab 3D immunoreactivity is associated predominantly with the high-density microsomal fraction, where the signal intensity is 3- and 7-fold greater than that in plasma membranes and low-density microsomes respectively. Rab 3D does not co-localize with GLUT4 on immuno-isolated intracellular vesicles and, unlike GLUT4, it is not redistributed in response to insulin. Thus, if Rab 3D plays a role in GLUT4 trafficking, it relies on mechanisms independent of relocation. We observed that Rab 3D is overexpressed in adipose cells of obese (fa/fa) Zucker rats, in a tissue- and isoform-specific manner. The pathophysiological significance of this defect remains elusive. This could form the molecular basis for altered adipose secretory function in obesity.

Adipose Tissue↗
PubMed1997

Spontaneous epidural emphysema and pneumomediastinum during an asthmatic attack in a child.

CT revealed the presence of epidural emphysema as an incidental finding in a 13-year-old boy in whom mild infrequent coughing during an asthmatic attack resulted in a pneumomediastinum and subcutaneous emphysema. Epidural emphysema was not associated with neurological symptoms. The CT images demonstrated the pathway of air leakage from the posterior mediastinum through the intervertebral foramina into the epidural space. Repeat CT showed spontaneous resolution of the epidural emphysema.

Adolescent↗
PubMed1997

Syndet is a novel SNAP-25 related protein expressed in many tissues.

SNAP-25 is a synaptosomal associated protein localized at the plasma membrane of nerve terminals. SNAP-25 associates with syntaxin 1 and vesicle-associated membrane protein-2 (VAMP-2) and is thought to form a complex essential for neurotransmitter release. We have identified syndet, a novel protein related to the family of SNAP-25 isoforms. Like SNAP-25, syndet has regions with high probability of forming coiled coils, a cysteine rich-domain, and lacks a signal sequence or transmembrane domains. Syndet is tightly bound to membranes, possibly by acylation within the cysteine-rich domain. Syndet is expressed in non-neuronal tissues. In adipocytes, syndet is found at the plasma membrane and in an intracellular compartment. The identification of syndet supports the hypothesis that multiple SNAP-25 related proteins ensure specificity of vesicle fusion at the cell surface.

3T3 Cells↗
PubMed1996

Cab45, a novel (Ca2+)-binding protein localized to the Golgi lumen.

We have identified and characterized Cab45, a novel 45-kD protein from mouse 3T3-L1 adipocytes. Cab45 is ubiquitously expressed, contains an NH2-terminal signal sequence but no membrane-anchor sequences, and binds Ca2+ due to the presence of six EF-hand motifs. Within the superfamily of calcium-binding proteins, it belongs to a recently identified group of proteins consisting of Reticulocalbin (Ozawa, M., and T. Muramatsu. 1993. J. Biol. Chem. 268:699-705) and ERC 55 (Weis, K., G. Griffiths, and A.I. Lamond. 1994. J. Biol Chem. 269:19142-19150), both of which share significant sequence homology with Cab45 outside the EF-hand motifs. In contrast to reticulocalbin and ERC-55 which are soluble components of the endoplasmic reticulum, Cab45 is a soluble protein localized to the Golgi. Cab45 is the first calcium-binding protein localized to the lumenal portion of a post-ER compartment; Cab45 is also the first known soluble protein resident in the Golgi lumen. Cab45 can serve as a model protein to determine the mechanism of retention of soluble proteins in the Golgi compartment.

3T3 Cells↗
PubMed1995

A novel serum protein similar to C1q, produced exclusively in adipocytes.

We describe a novel 30-kDa secretory protein, Acrp30 (adipocyte complement-related protein of 30 kDa), that is made exclusively in adipocytes and whose mRNA is induced over 100-fold during adipocyte differentiation. Acrp30 is structurally similar to complement factor C1q and to a hibernation-specific protein isolated from the plasma of Siberian chipmunks; it forms large homo-oligomers that undergo a series of post-translational modifications. Like adipsin, secretion of Acrp30 is enhanced by insulin, and Acrp30 is an abundant serum protein. Acrp30 may be a factor that participates in the delicately balanced system of energy homeostasis involving food intake and carbohydrate and lipid catabolism. Our experiments also further corroborate the existence of an insulin-regulated secretory pathway in adipocytes.

3T3 Cells↗
PubMed1995

Diffuse vesicular distribution of Rab3D in the polarized neuroendocrine cell line AtT-20.

The neuroendocrine cell line AtT-20 has two types of storage vesicles: dense core granules and synaptic vesicles, both sequestered at the tip of the processes. Here we show that Rab3D protein, which is abundant in fat cells, is also expressed in AtT-20 cells. Differently from Rab3A, which is localized in secretory vesicles accumulated at the tips, Rab3D has a diffuse vesicular distribution in the cytoplasm of the cell body, the processes and the tips. In AtT-20 cells, Rab3D may define a regulated secretory pathway which functions independently from cell polarity.

Amino Acid Sequence↗
PubMed1995

Nonneuronal expression of Rab3A: induction during adipogenesis and association with different intracellular membranes than Rab3D.

Rab3A is a small GTP-binding protein expressed predominantly in brain and neuroendocrine cells, in which it is associated with synaptic and synaptic-like vesicles, respectively. Here we report that adult mouse fat cells and 3T3-L1 adipocytes also express Rab3A mRNA and protein. They do not express synaptophysin, an abundant protein in synaptic vesicles or synaptic-like vesicles. The amount of Rab3A mRNA and protein, like that of the highly homologous isoform Rab3D, increases severalfold during differentiation of 3T3-L1 fibroblasts into mature adipocytes. In fat cells, most Rab3D and Rab3A protein is bound to membrane, irrespective of insulin addition. Rab3A and Rab3D are localized in different subcellular compartments, since about half of the Rab3A, but none of the Rab3D, is associated with a low-density organelle(s). Rab3D and Rab3A may be involved in different pathways of regulated exocytosis in adipocytes. Moreover, in adipocytes Rab3A may define an exocytic organelle that is different from synaptic vesicles or synaptic-like microvesicles found in neuronal and endocrine cells.

3T3 Cells↗
PubMed1995

Conformation of short DNA fragments by modulated fluorescence polarization anisotropy.

The technique of fluorescence polarization anisotropy (FPA) decay of intercalated ethidium has been used to study DNA conformation and dynamics, which are being recognized as primary determinants in transcription control and other cellular processes. Frequency modulated FPA when applied to two DNA molecules, a "straight" 50 base-pairs duplex fragment, and a bent fragment of similar length, has yielded different rotational diffusion coefficients for the two fragments. The data have been processed with an analytical model and with Brownian dynamics simulations, obtaining a good fit and a quantitative agreement between the two models. Both analyses have confirmed that one fragment can be described as a straight cylinder, while the other fragment is bent, with an angle estimated to be 45 degrees +/- 3 degrees. FPA has proved to be very powerful in determining simple conformations of short DNA duplexes and also particularly apt to probe the dynamical features of DNA fragments where conventional methods are either too cumbersome or fail to give quantitative results. In addition, the ligand no longer behaves ideally due to its complex structure and charge distribution. Thus for the protein the slope is no longer related simply to the net ligand charge, and the PB model gives a much larger slope than the LL model.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Composition↗
PubMed1995

Mandibular growth rates in human fetal development.

A morphometric analysis of changing proportions in the developing mandible was undertaken in 18 human embryos and fetuses of both sexes (developmental age from 8 to 14 weeks, crown-rump length, CRL, from 34 to 110 mm), previously cleared and stained with a specific method for bone (alizarin red S). Reference points were located on the mandible, i.e. condylar process (Pcl), coronoid process (Pco), gnathion (GN), gonion (GO), superior symphyseal point (SSP), for measuring linear dimensions, i.e. Pcl-GN, Pcl-Pco, Pco-GN, GO-GN, SSP-GN. The gonial (Pcl-GO-GN) and the (Pcl-GN-Pcl) angles were also measured. All linear dimensions were correlated with the CRL by bivariate allometry (1n y = 1n a+b 1n x): they all grew with positive allometry, except GO-GN with isometry. The mandibular ramus grew relatively faster than the body, both in length and height, and the greatest growth rate was found for ramus height. The relation between mandibular shape and the craniofacial structures was investigated using scale drawings obtained from photographs of fetal skulls in lateral view. In the youngest fetuses the mandible was prognathic, then became retrognathic. During the period investigated the zygomatic process and squama of the temporal bone were in a lower and more inclined position in relation to the transverse plane passing through the zygomatic arch than in the newborn and adult. This study identifies parameters fitting changing trends in height, length and shape of the human mandible during the prenatal period (8-14 weeks); moreover, it emphasizes that the mandibular growth patterns differ significantly from those of successive development periods.

Adult↗
PubMed1995

Influence of ligands on the fluorescence polarisation anisotropy of ethidium bound to DNA.

The decay of the fluorescence polarisation anisotropy (FPA) of the ethidium-DNA complex has been measured by multifrequency phase fluorometry, in order to study the perturbations induced by the presence of different ligands on the torsional dynamics of DNA, a moderately flexible polymer that undergoes bending (flexure of the helix axis) and torsional (twisting of base pairs) motions. Two probes have been used together with ethidium: an intercalator, chloroquine, and a minor groove binding dye: hoechst 33258. Chloroquine is found to substantially modify the DNA torsional dynamics both in linear and in circularly closed DNAs only at high binding ratios, in agreement with previous reports [Wu et al. Biochem. 27 (1988) 8128]. The effective elastic constant becomes approximately three times larger when the dye/base pairs binding ratio is higher than 0.14. The minor groove ligand hoechst 33258, on the other hand, greatly increases the effective elastic constant to the point that at dye/base pairs ratios larger than 0.5, the effective elastic constant becomes stiffer by several orders of magnitude, suggesting a progressive hindering of internal motions. The results reported here show that DNA torsions are more effectively influenced by groove-binding molecules than by intercalators and it is expected that the large perturbation of the former ligand may be useful when describing the change in the dynamical properties induced by DNA binding proteins. FPA in the frequency domain, the technique adopted throughout this work, has proved to be very sensitive to changes of the elastic constant that describes DNA torsional dynamics. Several computer simulations performed in order to predict the FPA time decay of intercalated ethidium have led to good agreement with the observed results.

Animals↗
PubMed1994

Evidence of hemoglobin dissociation.

Bovine carbonmonoxy hemoglobin investigated with light scattering studies is found to dissociate from its native tetramer structure into dimers and monomers. The values of the hydrated tetramer radius, RT = 32.1 A, and the fractional dissociation vs pH, have been obtained at different ionic strengths from the autocorrelation function of the scattered light. The results suggest that a relevant contribution to Hb dissociation is due to electrostatic effects and, by means of a model derived by Tanford, it has been possible to predict the behavior of dissociation. Among the findings of this approach, we recall the estimates of the electrostatic energy contributions to Hb dissociation, up to congruent to 6RT, and the predicted charge of tetrameric Hb vs pH, which agrees very well with the experimental data.

Animals↗
PubMed1994

Induction of caveolin during adipogenesis and association of GLUT4 with caveolin-rich vesicles.

Caveolae, also termed plasmalemmal vesicles, are small, flask-shaped, non-clathrin-coated invaginations of the plasma membrane. Caveolin is a principal component of the filaments that make up the striated coat of caveolae. Using caveolin as a marker protein for the organelle, we found that adipose tissue is the single most abundant source of caveolae identified thus far. Caveolin mRNA and protein are strongly induced during differentiation of 3T3-L1 fibroblasts to adipocytes; during adipogenesis there is also a dramatic increase in the complexity of the protein composition of caveolin-rich membrane domains. About 10-15% of the insulin-responsive glucose transporter GLUT4 is found in this caveolin-rich fraction, and immuno-isolated vesicles containing GLUT4 also contain caveolin. However, in non-stimulated adipocytes the majority of caveolin fractionates with the plasma membrane, while most GLUT4 associates with low-density microsomes. Upon addition of insulin to 3T3-L1 adipocytes, there is a significant increase in the amount of GLUT4 associated with caveolin-rich membrane domains, an increase in the amount of caveolin associated with the plasma membrane, and a decrease in the amount of caveolin associated with low-density microsomes. Caveolin does not undergo a change in phosphorylation upon stimulation of 3T3-L1 adipocytes with insulin. However, after treatment with insulin it is associated with a 32-kD phosphorylated protein. Caveolae thus may play an important role in the vesicular transport of GLUT4 to or from the plasma membrane. 3T3-L1 adipocytes offer an attractive system to study the function of caveolae in several cellular trafficking and signaling events.

3T3 Cells↗
PubMed1994

Identification of two different HLA B49 DR4 extended haplotypes in the Sardinian population.

The HLA-B49 DR4 haplotype, which is rare in Caucasoid populations, has a frequency in Sardinia of approximately 6% and a very strong linkage disequilibrium (LD). To better understand its genetic structure, the Bf, C4A and C4B Class III alleles were studied in 56 healthy unrelated Sardinian subjects of B49 DR4 phenotype and in 24 of their families. Moreover, 14 sick subjects with the same phenotype were examined together with five of their families. A group of 285 haplotypes belonging to randomly selected individuals was used as a control population sampling. The distribution of the Bf, C4A and C4B alleles among the healthy probands revealed two main groups of association: one major group of 36 subjects (64.3%) with the BfF, C4A3 and C4B4 alleles and one minor group of 14 subjects (25%) with BfS, C4AQ0 and C4B1. A similar subdivision was also observed in the small group of patients. The family analysis confirmed these results and showed two different B49 DR4 extended haplotypes: one with the F34 complotype in 79.1% of the probands (delta x 1000 = 49.0) and the other with the S01 complotype in 20.8% of the probands (delta x 1000 = 17.3). The first one, in LD with the A1 and Cw7 alleles, has not yet been reported in other populations. The second one seems to be identical to a haplotype already reported in the Spanish population. The molecular analysis of the DRB1 locus carried out in 20 of the 70 probands demonstrated that, in both haplotypes, DR4 was represented by the DRB1*0405 allele.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

The HLA-DRB1*0101 allele is responsible for HLA susceptibility to lichen ruber planus.

Serological studies have demonstrated that lichen ruber planus is associated with the HLA-DR1 antigen. This association was also confirmed by us in the Sardinian population. To establish which DRB1 molecular alleles are involved, we studied a selected group of 14 DR1 positive patients affected by cutaneous idiopathic lichen planus and a group of DR1 positive healthy controls using PCR with sequence-specific primers (PCR-SSP). Comparisons between the allele frequencies in patients and controls showed a positive association with cutaneous idiopathic lichen planus for the DRB1*0101 allele (RR = 5.8, P = 0.0097), DRB1*0101 and DRB1*0102 are associated with the same DQA1 and DQB1 alleles and are different only for two amino acids in positions 85 and 86 of the DRB1 gene. In our case report predisposition to cutaneous idiopathic lichen planus is correlated with a valine in position 85 and a glycine in position 86 at the second exon of the DRB1 gene.

Alleles↗
PubMed1994

Airway response to a bronchodilator in healthy parents of infants with bronchiolitis.

In order to assess the role of genetic factors and environmental influences in bronchial responsiveness, we studied the airway response to an inhaled bronchodilator in 66 nonasthmatic parents (age, 30.9 +/- 5.9 years) of infants with bronchiolitis (group 1). It was a placebo-controlled double-blind study. A control group (group 2) of healthy parents of infants who did not have bronchiolitis also were investigated with the test of bronchodilator response. All subjects showed normal expiratory airflow and lung volumes (forced vital capacity [FVC], forced expiratory volume in 1 s [FEV1], and mean forced expiratory flow during the middle half of FVC [FEF25-75%] > 80 percent of predicted) at baseline forced expiratory maneuver. In 16 (24.2 percent) subjects of group 1, there was significant increase in at least one parameter after salbutamol administration, but not after placebo inhalation, with respect to baseline levels. Furthermore, no significant changes in FVC, FEV1, or FEF25-75% values were found in group 2. In conclusion, this study confirms that parents of infants with bronchiolitis have an enhanced airway responsiveness, greater than control parents. Further studies are needed to assess whether one may infer the outcome of infants with bronchiolitis from this characteristic in their parents.

Adult↗
PubMed1993

Developmental pathways of vertebral centra and neural arches in human embryos and fetuses.

The ossification pathways of both vertebral centra (i.e., vertebral bodies) and neural arches were studied in human embryos and fetuses (CR-length between 38 and 116 mm). A clearing and double-staining method for whole embryo or fetus, using alcian blue and alizarin red S, allowed an easy and precise detection of the morphology of the whole vertebral column and every single vertebra. Both cartilaginous and bony components were clearly visible. Different temporal and topographical patterns of ossification were shown for the centra and arches; the latter were respectively proximal-distal (i.e., bidirectional from a defined starting tract in T10-L1) and cranial-caudal (i.e., monodirectional). The patterns could be related to the morphogenetic processes of other structures (i.e., muscles and nerves). Moreover, the numerical survey of ossification centers provided a possible parameter for the determination of the fetal developmental age. This could be useful in the study of pathological conditions.

Alcian Blue↗