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Biomedical subjects

M Sabatini

Publications and source records attributed to M Sabatini.

At least 19 recordsLinked to original sources

Specificity and timing of neocortical transcriptome changes in response to BDNF gene ablation during embryogenesis or adulthood.

Brain-derived neurotrophic factor (BDNF) has been reported to be critical for the development of cortical inhibitory neurons. However, the effect of BDNF on the expression of transcripts whose protein products are involved in gamma amino butric acid (GABA) neurotransmission has not been assessed. In this study, gene expression profiling using oligonucleotide microarrays was performed in prefrontal cortical tissue from mice with inducible deletions of BDNF. Both embryonic and adulthood ablation of BDNF gave rise to many shared transcriptome changes. BDNF appeared to be required to maintain gene expression in the SST-NPY-TAC1 subclass of GABA neurons, although the absence of BDNF did not alter their general phenotype as inhibitory neurons. Furthermore, we observed expression alterations in genes encoding early-immediate genes (ARC, EGR1, EGR2, FOS, DUSP1, DUSP6) and critical cellular signaling systems (CDKN1c, CCND2, CAMK1g, RGS4). These BDNF-dependent gene expression changes may illuminate the biological basis for transcriptome changes observed in certain human brain disorders.

Animals↗

Effects of transforming growth factor-beta on aggrecanase production and proteoglycan degradation by human chondrocytes in vitro.

OBJECTIVE: Aggrecan is degraded by Aggrecanases (ADAMTS-4 and -5) and MMPs, which cleave its core protein at different sites. Transforming growth factor (TGF)beta is known to stimulate matrix formation in cartilage, and ADAMTS-4 production in synoviocytes. The aim of this in-vitro study was to examine the effects of TGFbeta on aggrecanase production in human cartilage. DESIGN: Expression of ADAMTS-4 and -5 in chondrocyte cultures from normal or osteoarthritic cartilage was studied at mRNA level by RT-PCR. Aggrecanase activity was examined by western blot of aggrecanase-generated neoepitope NITEGE, and by measure of proteoglycan degradation in cartilage explants. RESULTS: TGFbeta strongly increased mRNA levels of ADAMTS-4, while ADAMTS-5 was expressed in a constitutive way in chondrocytes from normal and osteoathritic cartilage. TGFbeta also increased NITEGE levels and proteoglycan degradation. Addition of an aggrecanase inhibitor blocked the increase of NITEGE, and partially inhibited proteoglycan degradation. CONCLUSIONS: TGFbeta stimulates ADAMTS-4 expression and aggrecan degradation in cartilage. This catabolic action seems to be partially mediated by aggrecanases. It is, therefore, proposed that the role of TGFbeta in cartilage matrix turnover is not limited to anabolic and anti-catabolic actions, but also extends to selective degradation of matrix components such as aggrecan.

ADAM Proteins↗

Effects of agonists of peroxisome proliferator-activated receptor gamma on proteoglycan degradation and matrix metalloproteinase production in rat cartilage in vitro.

OBJECTIVE: To examine the effects of agonists of peroxisome proliferator-activated receptor (PPAR) gamma on proteoglycan degradation induced by interleukin (IL)-1beta or tumor necrosis factor (TNF)alpha in cartilage in vitro. DESIGN: Proteoglycan degradation was measured as release of radioactivity from rat cartilage explants previously labeled with (35)SO2-4. Western blots were used to examine tissue levels of aggrecan neoepitopes NITEGE and VDIPEN, generated by aggrecanases and matrix metalloproteinases (MMP), respectively. Production of MMP-2, -3 and -9 by cultured rat chondrocytes was measured by zymography and by fluorimetric assay. RESULTS: IL-1beta-induced proteoglycan degradation was likely due to aggrecanase, since it was associated with a strong increase of NITEGE signal. MMP-dependent VDIPEN signal increased only after further incubation with pro-MMP activator APMA. PPAR agonists 15d-PGJ(2) and GI262570 (10 microM) inhibited IL-1beta- and TNFalpha-induced proteoglycan degradation measured both before and after addition of APMA. The agonists also inhibited cytokine-induced MMP production by isolated chondrocytes. CONCLUSION: This study shows that PPARgamma agonists inhibit cytokine-induced proteoglycan degradation mediated by both aggrecanase and MMP. This effect is associated with inhibition of production of MMP-3 and -9. These results support the interest for PPARgamma agonists as candidate inhibitors of pathological cartilage degradation.

Animals↗

YKL-40 (cartilage gp-39) induces proliferative events in cultured chondrocytes and synoviocytes and increases glycosaminoglycan synthesis in chondrocytes.

YKL-40 (cartilage gp-39), is a mammalian glycoprotein related in sequence to chitinases. Its function is unknown, but it is thought to be involved in tissue remodeling. Immunocytochemical staining of YKL-40 in guinea pig chondrocytes (GPC), rabbit chondrocytes (RC), and rabbit synoviocytes (RS) was higher in dividing cells than in confluent cells, suggesting a participation of YKL-40 in cell cycle events. As assessed by the MTT assay, YKL-40 at 1.9-7.6 nM had dose-dependent mitogenic activity toward the three cell types. At 7.6 nM, YKL-40 increased the number of cells of 42% in GPC, 75% in RC, and 86% in RS after 72 h. YKL-40 also stimulated total proteoglycan synthesis by chondrocytes in a dose-dependent manner as assessed by Na[35SO4] incorporation and cetylpyridinium chloride precipitation. At 9.4 nM, YKL-40 increased proteoglycan synthesis of 42% in GPC and 58% in RC after 24 h. The growth factor properties of YKL-40 may explain the increased tissue remodeling associated with high levels of YKL-40 in joint diseases, and possibly, in malignant pathologies such as breast cancer or colorectal cancer.

Adipokines↗

Effects of ceramide on aggrecanase activity in rabbit articular cartilage.

Ceramide participates in signal transduction of IL-1 and TNF, two cytokines likely involved in cartilage degradation in osteoarthritis. We previously showed that ceramide stimulates proteoglycan degradation, mRNA expression of matrix metalloproteinase (MMP)-1, -3, and -13, and pro-MMP-3 production in rabbit cartilage. Since aggrecan, the main cartilage proteoglycan, can be cleaved by metalloproteinases both of MMP and aggrecanase type, the aim of this study was to determine if ceramide stimulates aggrecanase action and, if that is the case, in which measure aggrecanase mediates the degradative effect of ceramide. To this end, antibodies were used against the C terminal aggrecan neoepitopes generated by aggrecanases (NITEGE(373)) and MMPs (DIPEN(341)). Ceramide C(2) at 10(-5) to 10(-4) M dose-dependently increased NITEGE signal, without changing that of DIPEN, in cultured explants of rabbit cartilage. The effects of 10(-4) M C(2) on NITEGE signal and proteoglycan degradation were similarly antagonized by the metalloproteinase inhibitor batimastat, with return to the basal level at 10(-6) M. These results show that, similarly to IL-1 and TNF, ceramide-induced aggrecan degradation is mainly due to aggrecanases. That no increase of MMP activity was detected, despite stimulation of MMP expression, was probably due to lack of proenzyme conversion to mature form, since addition of a MMP activator to C(2)-treated cartilage increased both DIPEN signal and proteoglycan degradation. These findings support the hypothesis that cytokine-induced ceramide could play a mediatory role in situations of increased degradation of cartilage matrix.

Aggrecans↗

Effects of ceramide on apoptosis, proteoglycan degradation, and matrix metalloproteinase expression in rabbit articular cartilage.

Cartilage loss in osteoarthritis is characterized by matrix degradation and chondrocyte death. The lipid messenger ceramide is implicated in signal transduction of the catabolic cytokines tumor necrosis factor (TNF) and interleukin-1 (IL-1), as well as in apoptosis. The aim of this study was to examine the in vitro effects of ceramide on proteoglycan degradation, matrix-metalloproteinase (MMP) expression and activity, and chondrocyte apoptosis in rabbit articular cartilage. Cell-permeant ceramide C(2) stimulated proteoglycan degradation in cartilage explants starting from 3 x 10(-5) M, with 100% increase at the dose of 10(-4) M. This effect was probably due to MMPs since it was blocked by the MMP inhibitor batimastat. Furthermore, in isolated chondrocytes, C(2) stimulated the expression of MMP-1, 3, and 13 at the mRNA level, MMP activity, and MMP-3 production. Ceramide also caused chondrocyte apoptosis at doses ranging from 10(-5) to 10(-4) M. This study supports the hypothesis that ceramide might play a mediatory role in both matrix degradation and apoptosis in processes of cartilage loss such as those observed in osteoarthritis.

Animals↗

[Significance of ultrasonography in the diagnosis of appendicitis].

AIM: The authors aim to evaluate the sensitivity and specificity of abdominal ultrasonography in 183 in-patients (113 females--70 males), aged between 3 and 78 years old, in the General Surgery department of Pugliese Hospital in Catanzaro, for abdominal pain and possible acute appendicitis, using a retrospective study. All patients underwent ultrasonography at the Division of Radiology in the same hospital. METHODS: The technique used was graded-compression US (useful to eliminate gas artifacts and to reduce the distance from the appendix) using a linear transducer between 3.5 and 7.5 MHz. The method lasted an average of 15 minutes and was performed by specially trained radiologists. The transducer was held between the forefinger and thumb and pushed into the abdomen using both palms, as if palpating the abdomen. When compression is applied slowly and gently, the pain is surprisingly well tolerated by the patient. The radiologist records whether the inflamed appendix is visualised ultrasonographically and with what degree of certainty, and whether perforations or the formation of abscesses and other pathological processes can be seen. In this case, clinical diagnosis was confirmed by radiological imaging and eventually by surgical evidence. RESULTS: Of the 183 patients examined, 135 showed positive US findings, 11 refused surgery and pain was resolved by pharmacological treatment, and 9 presented other pathologies (3 gastric ulcers, 4 acute cholecystitis and 2 extrauterine pregnancies). Therefore, 115 patients were effectively positive. Of the 183 patients, 48 were negative but of these, only 39 were effectively negative because 3 were false negatives and 6 revealed other pathologies when examined using other methods of diagnosis. Even if the diagnosis of appendicitis was confirmed by clinical examination in most cases, US is of value both to confirm the clinical diagnosis and to rule out any complications. In this particular case it was also useful for the surgeon as a means of locating the position of the appendix. Even if this method is partly conditioned by the patient's clinical conditions, the results were excellent. CONCLUSIONS: The authors conclude that US of the appendix is a valuable aid in the diagnosis of appendicitis, especially in the case of acute or subacute forms in which other radiological imaging might worsen the pathology and lead to the onset of further complications. US offers undeniable advantages using a non-invasive, low cost technique with a specificity of around 80% and sensitivity between 85 and 93%. It also provides a means of identifying other sources of low abdominal pain. However, we still regard clinical examination as being essential for diagnosis.

Adolescent↗

[Antero-posterior lesions of the superior glenoid labrum. Magnetic resonance evaluation].

PURPOSE: To assess MR potentials in the evaluation of superior glenoid labrum disease and possible associated conditions of the rotator cuff and of the anterior mechanism of the shoulder. MATERIAL AND METHODS: We retrospectively evaluated 51 patients (age range 18 to 53 years) with a diagnosis of anteroposterior lesion of the superior glenoid labrum. MR examinations were performed with a 0.2 T permanent magnet and a dedicated coil, using T1- and T2-weighted SE sequences on mostly coronal-oblique planes. Slice thickness was 4 mm. In 8 cases, the examination was completed with intra-articular injection of contrast agent. Twenty-eight patients were submitted to surgery (arthrotomy in 7 cases; arthroscopy in 21 cases). RESULTS: We considered only the cases with surgical confirmation and divided them into 2 groups: 15 patients with isolated alteration of the superior glenoid labrum and 13 patients with an anteroposterior lesion of the glenoid labrum associated with disease of the rotator cuff or of the anterior mechanism of the shoulder. MRI demonstrated 5 cases of superior labrum irregularities at the level of its glenoid insertional portion (type I lesion); 6 cases of detachment of the superior portion of the labrum (type II); 9 cases of bucket handle tear of the superior labrum with involvement of the insertional portion of the long head of the biceps tendon (type III); 8 cases of superior labrum tear extending within the long head of the biceps tendon (type IV). In the patients with associated disease MRI demonstrated supraspinatus tendon tear in 5 cases, lesion of the labrum also in its anteroinferior portion in 1 case, Hill-Sachs intraspongious fracture with involvement of the inferior glenohumeral complex in 1 case, and complete tear of the rotator cuff in 7 cases. Subsequent surgery always confirmed the presence of associated lesions, while the superior labrum lesion was not confirmed in 3 patients. In 4 cases, surgical findings provided a different classification of the lesion type than MRI. DISCUSSION: In the presence of a type I anteroposterior lesion of the superior glenoid labrum, coronal MRI can depict the loss of the triangular shape of the labrum. Type II lesions show detachment of the labrum, which appears on the MR images as a high signal intensity band passing through the labrum with caudocranial orientation. A superior glenoid labrum tear with a low signal intensity area within the joint indicates a type III lesion. Complete tear of the superior glenoid labrum with involvement of the long head of the biceps tendon demonstrated on the coronal T1-weighted SE and T2-weighted GE sequences is a sign of a type IV lesion. CONCLUSIONS: MRI can be a valuable diagnostic technique in type III and IV lesions of the superior glenoid labrum. It often provides important information about the possible presence of associated diseases, especially of the rotator cuff, which are helpful for treatment planning.

Adolescent↗

[Magnetic resonance imaging of hepatic focal lesions: dynamic contrastographic evaluation with gadolinium versus reticulo-endothelial hepato-specific contrast media].

PURPOSE: To compare the potentials of AMI-25 (Endoren) to those of Gadolinium with the dynamic contrast-enhanced technique in the differential diagnosis of focal liver lesions. MATERIAL AND METHODS: Forty patients with at least one focal liver lesion diagnosed at US underwent MRI. We used a 1.5 T unit and employed single-shot half-Fourier T2-weighted FSE and spoiled gradient-echo T1-weighted sequences before and after Gadolinium injection. Multiple acquisitions were obtained during the arterial, portal and delayed phases. Twenty-four to 48 hours later T2*-weighted GRE and SPGR/90 degrees sequences were obtained after AMI-25 administration. In the characterization of solid lesions the gold standard was biopsy performed with a shearing needle; for the diagnosis of angiomas and of 11 metastatic lesions we considered follow-up and clinical data as important diagnostic elements. RESULTS: We found 12 hepatocarcinomas, 14 metastases, 4 cases of focal nodular hyperplasia (FNH), 4 adenomas and 6 angiomas. The diagnosis was correct and confirmed by the conventional examination in all cases but 2 adenomatous lesions and 2 angiomas. Precontrast studies showed slight hyperintensity in 2 of 4 cases of FNH, while the other 2 lesions appeared isointense and were therefore detected only on postcontrast images, where there was contrast agent uptake during the arterial phase and rapid washout. We found only one central scar hyperintense on T2- and hypointense on T1-weighted images. After AMI-25 administration all lesions appeared isointense to surrounding parenchyma on T2* GRE sequences. Adenomas were isointense in the precontrast phase and postcontrast 3 of them showed strong Gadolinium uptake and rapid washout. After AMI-25 two of the 4 lesions were hyperintense while the other two were isointense to the parenchyma. Four of 6 angiomas exhibited a typical pattern characterized by signal hyperintensity on T2-weighted sequences and on AMI-25-enhanced T1- and T2-weighted sequences. Two angiomas were supposed to be of malignant nature but histology showed the presence of a strong fibrotic component. Hepatocarcinomas could be detected on precontrast images. After Gadolinium administration 10 lesions appeared hyperintense in the arterial phase and 2 were hypointense. After AMI-25 all lesions exhibited homogeneous signal hyperintensity and appeared slightly bigger than on Gadolinium-enhanced images. The metastases were only partly demonstrated by MRI. Postgadolinium studies showed 13 lesions with hyperintense signal in the portal phase. AMI-25 administration detected 14 lesions that appeared slightly bigger than on Gadolinium-enhanced images. CONCLUSIONS: AMI-25 can help also in characterizing primary lesions with an atypical signal pattern after contrast agent administration thanks to its intrinsic capability of accumulating in benign lesions. However it remains difficult to characterize well differentiated hepatocarcinomas and adenomas. Finally, AMI-25 improves MR capabilities in detecting secondary lesions and possible satellite nodules.

Adenoma↗

[Symptomatic renal metastases of bronchial carcinoma].

Renal metastasis from carcinoma of the lung is rarely a clinical problem. Autopsic series however prove that the kidney is a frequent metastatic organ (20%). We report the case of a 43-years-old male patient affected with a squamous cell carcinoma of the lung, with bilateral renal extension. These secondary localizations were detected through a left flank pain prior to a systemic inflammatory response syndrome. The absence of hematuria (even microscopic) contrasted with the importance of the lesions. The age, along with the poor general state of our patient and the absence of any CT specificity justified an exploratory lobotomy. The pathologic analysis of the renal biopsies confirmed the metastatic nature of the lesion.

Adult↗

Amino derivatives of phenyl alkyl thiophene as inhibitors of bone resorption. Structure-activity relationship.

Metabolism of arachidonic acid through the 5-lipoxygenase (LO) pathway generates compounds that stimulate osteoclastic bone resorption; since LO metabolites might play a role in bone loss due to excessive resorption it was tried to develop a series of antiresorptive agents starting from an already known LO inhibitor. Of the 35 compounds synthesized, 11 strongly inhibited (10 mumol/l) retinoic acid-induced bone resorption in cultured mouse calvariae; they were also tested for their effect on LO activity using rat peritoneal neutrophils, but no correlation could be drawn between inhibition of LO and bone resorption. Other pathways, still to be identified, must therefore be targeted by these compounds even though LO inhibition might contribute to their effects on bone. Two compounds selected for further studies were found active on parathyroid hormone-induced osteolysis, while they had no effect on basal resorption; they must, therefore, act at some key point in the process of activation of osteoclastic resorption. This series of compounds may represent a new way for the treatment of bone loss due to excessive resorption.

Animals↗

Human amniotic tumor that induces new bone formation in vivo produces growth-regulatory activity in vitro for osteoblasts identified as an extended form of basic fibroblast growth factor.

Tumors occasionally stimulate bone formation and cause osteoblastic metastases. Although this occurs most frequently in widespread prostate cancer, human prostate cancer cells are difficult to grow in culture without changing their phenotype, and the few available prostatic cancer lines do not increase bone formation in vivo. To identify tumor-derived osteoblast-stimulatory factors, we studied a long-established human tumor cell line derived from human amnion that has, in the past, been reported to cause bone formation in vivo when inoculated into nude mice. Tumor cells were inoculated into nude mice and induced extensive new bone formation. To characterize osteoblast growth factors produced by these tumor cells, solid tumor was isolated from the mice and extracted at neutral pH. Biological activity, assessed by stimulation of proliferation of MG-63 osteoblast-like cells, was used to monitor purification after heparin-Sepharose column chromatography, Mono-S, and C4 reverse-phase high-performance liquid chromatography. An extend amino-terminal form of basic fibroblast growth factor (FGF) was purified by its capacity to stimulate proliferation in MG-63 cells and partially sequenced. Basic FGF is also known to stimulate proliferation in MG-63 cells and other osteoblasts in vitro and bone formation in vivo. In summary, these human tumor cells stimulate new bone formation in vivo and produce an osteoblast stimulating activity in vitro, which has been identified as a form of basic FGF.

Amino Acid Sequence↗

Kikuchi's disease associated with Hashimoto's thyroiditis.

We describe a unique association of histiocytic necrotizing lymphadenitis (Kikuchi's disease) and chronic lymphocytic (Hashimoto's) thyroiditis in a patient who presented with significant cervical lymphadenopathy and a goiter. This case illustrates the value of lymph node biopsy combined with the fine needle aspiration of the thyroid in determining the nature of the relationship between the goiter and lymphadenopathy.

Adult↗

Effects of parathyroid hormone and agonists of the adenylyl cyclase and protein kinase C pathways on bone cell proliferation.

The anabolic effect of parathyroid hormone (PTH) on bone is partly due to a stimulation of osteoblast proliferation. The PTH signal is transduced by the pathways of adenylyl cyclase (AC)/protein kinase (PK) A and phospholipase C/PKC/Ca++. There is still uncertainty about the relative contribution of the two pathways to the proliferative effects of the hormone. In our study, PTH(1-34), AC/PKA agonists, and phorbol 12-myristate-13-acetate (PMA, a PKC activator) stimulated cell proliferation in cultured mouse calvariae. In isolated osteoblasts, only PMA stimulated proliferation, whereas AC/PKA agonists and PTH(1-34) inhibited it. As already known, PTH in the presence of supramaximal concentrations of transforming growth factor-beta (TGF-beta) stimulated osteoblast growth; under these same conditions, AC/PKA agonists reproduced the stimulatory effect of PTH(1-34), whereas PMA became inhibitory. PTH(1-31), which stimulates AC without affecting PKC, acted similarly to the fully active PTH(1-34) in both calvaria and isolated osteoblasts. On the contrary, midregion fragments that activate only PKC stimulated calvaria cell proliferation faintly in comparison with PTH(1-34); no effect was seen in osteoblasts, either with or without TGF-beta. Our study shows that the effects of PTH on proliferation can be mimicked by agonists of the AC/cAMP pathway. Although PMA is indeed able to stimulate cell growth in tissue explants, its effects on isolated osteoblasts markedly diverge from those of PTH. We conclude that activation of the AC/PKA pathway is the main component of the proliferative effects of PTH.

1-Methyl-3-isobutylxanthine↗

Expression of bone morphogenetic protein messenger RNA in prolonged cultures of fetal rat calvarial cells.

In addition to structural proteins of bone, such as type I collagen, bone cells synthesize a number of growth regulatory peptides that are also stored in the bone matrix, presumably as a consequence of local production by osteoblasts. Among the bone growth regulatory peptides found in the bone matrix are the recently described bone morphogenetic proteins (BMPs). These factors were purified from bone matrix by their capacity to stimulate ectopic bone formation, but it is not known whether they are produced by normal bone cells and influence normal bone formation. To determine whether they are expressed by normal osteoblasts during differentiation, we used the technique of prolonged primary culture of fetal rat calvarial osteoblasts. These cultures have been shown to be an informative model for studying expression of bone-related genes by cultured osteoblasts, since specific genes are expressed as the cells undergo proliferation and differentiation. We found that the bone morphogenetic proteins 1, 2, 4, and 6 are expressed by cultures of fetal rat calvarial osteoblasts before they form mineralized bone nodules and as they express alkaline phosphatase, osteocalcin, and osteopontin. This model can be used for study of regulation of expression of bone morphogenetic proteins by osteoblasts.

Alkaline Phosphatase↗

Effects of transforming growth factor beta on bone nodule formation and expression of bone morphogenetic protein 2, osteocalcin, osteopontin, alkaline phosphatase, and type I collagen mRNA in long-term cultures of fetal rat calvarial osteoblasts.

Transforming growth factor beta (TGF-beta) is one of the most abundant of the known growth regulatory factors stored within the bone matrix. When bone is resorbed, TGF-beta is released in an active form and is a powerful bone growth stimulant. When injected into the subcutaneous tissue over the calvarial surface of rodents, it rapidly causes proliferation of the periosteal layer and accumulation of new woven bone. In this report, we describe the effects of TGF-beta 1 on first subcultures of fetal rat osteoblasts obtained from calvarial bones and cultured from confluence with ascorbic acid and beta-glycerophosphate. Under these conditions, nodules with characteristics of normal bone appear by day 8. Similar to experiments described by Antosz et al., TGF-beta added to confluent cultures inhibited the formation of bone nodules. Both the number and total area of the nodules were quantitated and shown to be completely inhibited by 2 ng/ml of TGF-beta 1. TGF-beta also impaired the expression of genes associated with bone formation, including type I collagen, alkaline phosphatase, osteopontin, and osteocalcin. TGF-beta also inhibited the expression of mRNA for the bone morphogenetic protein 2 (BMP-2). These results, showing suppression of markers representative of osteoblast differentiation, suggest that the effects of TGF-beta to stimulate bone formation in vivo are not likely a result of effects on differentiated mineralizing osteoblasts but, as suggested by previous studies, more likely are caused by effects on osteoblast precursors. These results also suggest that endogenous BMP-2 expression in fetal rat calvaria cells is important for bone cell differentiation.

Alkaline Phosphatase↗