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Biomedical subjects

A Riva

Publications and source records attributed to A Riva.

At least 145 records · Page 8Linked to original sources
PubMed1995

The main excretory duct (Stensen's) of the human parotid gland: a transmission and scanning electron microscope study.

The epithelial cells of the human parotid main excretory duct (Stensen) were studied by transmission (TEM) and scanning (SEM) electron microscopy through a variety of procedures that allowed the visualization of their three-dimensional microanatomy. Stensen's duct in humans is lined, in its distal portion, with a pseudostratified epithelium with tall principal cells and smaller basal cells, while the epithelium becomes progressively stratified cylindrically toward the oral stoma. Goblet cells are scattered among the other epithelial cells. The principal cells exhibit, on their lateral surfaces, numerous flattened laminar folds probably involved in transporting processes. A well-developed smooth endoplasmic reticulum intermingled with mitochondria occupies the cellular apices. Some vesicles are recognized on the cytoplasmic surfaces of the apical and lateral plasmalemma when cytoplasmic organelles are removed. All these features are interpreted as being involved in the process of endocytosis. In both TEM and SEM, the principal cells show a relevant number of irregular apical protrusions that may represent a kind of apocrine secretion. Thus, with regard to function, the human Stensen's duct seems to modify the composition of saliva by processes of resorption and secretion, the latter coming from goblet cells as well. The basal cells have a surface microanatomy completely different from that of principal cells. They exhibit, in fact, only sparse microvillosities and smooth areas on their lateral aspect, while their stromal surface is greatly augmented by irregular thin ramified processes. The role of basal cells is also discussed.

Adult↗
PubMed1995

The intracellular structure of secretory and ductal epithelia of human major salivary glands. A scanning electron microscopic study.

The secretory and ductal cells of human salivary glands have been studied at Scanning Electron Microscopy (SEM) by our modification of the Aldehyde-Osmium-DMSO-Osmium (A-ODO) maceration method which enables the analytical study of human bioptical specimens. The most interesting results are those concerning the visualization of the cytoplasmic aspect of intercellular canaliculi of serous cells and of mitochondria of ductal cells. The canaliculi appear as elongated cylindrical structures fenestrated by holes correspohding to the bases of microvilli deprived of the cytoskeleton. Mitochondria of principal cells are longer and more complex than previously reported.

Adult↗
PubMed1995

[Ultrasonography-guided identification of the lumbar epidural space].

The study was designed to assess the reliability of sonographic evaluation in the prediction of the depth of the lumbar epidural space. Forty males, scheduled for epidural anesthesia for surgical repair of inguinal hernia, were prospectively studied. Patients were placed in a sitting position and sagittal scanning of the lumbar spine was performed with a 5-MHz transducer over the fourth or fifth interspace in order to identify the deeper hyperechogen interface, which represents the landmark between the ligamentum flavum and the epidural space. Ultrasound depth was measured and transducer removed. A Tuohy needle 18 G was then introduced percutaneously according to the standard technique and a rubber slide placed over it, so that it depth of insertion could be accurately measured. The potential for using ultrasounds for prediction of the distance from skin to epidural space was analyzed using a simple linear regression analysis; p values < 0.05 were considered significant. Mean values of ultrasound depth and needle depth were respectively 51 mm (SD 6.3) and 50.9 mm (SD 6.2); the correlation coefficient was 0.99. Ultrasound scanning of the lumbar spine provides an accurate measurement of the depth of the epidural space, which can facilitate the performance of the epidural anaesthesia and may decrease the complication rate, particularly in those patients in which anatomic landmarks are obscured.

Adult↗
PubMed1995

Primary cerebellar and spino-cerebellar ataxia an MRI study on 63 cases.

63 patients with primary cerebellar and spinocerebellar ataxia have been studied with MRI. This method allows to identify in vivo different groups of diseases such as that characterized by atrophy of cerebellum alone; that with atrophy of cerebellum associated with brainstem changes; the forms with associated changes of basal ganglia; the forms with spinal cord atrophy alone, as well as transitional forms. An interesting correlation between the varying groups and the type of inheritance was found, while no correlation with other clinical aspects was observed.

Adolescent↗
PubMed1995

A compared TEM/SEM investigation on the pericytic investment in developing microvasculature of the chick optic tectum.

The pericytes have been ultrastructurally and morphometrically analyzed in the neural vessels of the chick embryo optic tectum, under the transmission and scanning electron microscopes. The observations demonstrated that shape and surface features of pericytes, as well as their spatial relation with the endothelium, remarkably change during development, whereas their ultrastructure does not substantially modify from the early to the late embryonic stages. The pericytes have an ovoid body, broad processes, smooth surfaces, and are closely applied to the endothelial tube on days 5-7; they show convolute shape, highly irregular surfaces, and are complicately interdigitated with the endothelial cells, when a vivacious vessel growth takes place, on days 12-14; finally, they are flattened, smooth, highly branched, and completely enclosed in the basement lamina on days 20-21, when a definitive vascular pattern is established. The contribution of pericytes to the formation of the basement lamina has been confirmed by the detection of exocytotic vesicles discharging their content toward the subendothelial cleft. The morphometric evaluations revealed that pericytes provide the growing neural microvessels with an almost continuous coverage which, however, undergoes a significant reduction within hatching time. On the whole, the results suggest that the pericytes are as active as the endothelial cells during the vessel growth and play an inhibitory role on the endothelial proliferation only later on, when they are closely adherent to the endothelium and are encompassed by the basement lamina.

Animals↗
PubMed1995

Interferon alpha treatment of relapsing-remitting multiple sclerosis: long-term study of the correlations between clinical and magnetic resonance imaging results and effects on the immune function.

Interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) are proinflammatory cytokines which may be involved in the pathogenesis of MS. IFN-alpha counteracts many of the proinflammatory actions of IFN-gamma and TNF-alpha. We treated 20 patients with relapsing-remitting (RR) MS with 9 MIU of recombinant IFN-alpha-2a (rIFN-alpha) (n = 12) or placebo (n = 8) intramuscularly every other day for 6 months. Clinical exacerbations or new or enlarging lesions at serial MRI occurred in 2/12 rIFN-alpha-treated and in 7/8 placebo-treated patients (P < 0.005). Only one new MRI lesion was detected in the rIFN-alpha group, while 27 new or enlarging lesions were detected in placebo group (P < 0.01). Baseline lymphocyte IFN-gamma (19.10 +/- 7.12 U ml-1) and TNF-alpha (18.05 +/- 5.34 pg ml-1) production significantly decreased to 3.03 +/- 0.66 (P < 0.04) (for IFN-gamma) and to 5.78 +/- 0.90 (P < 0.04) (for TNF-alpha) after rIFN-alpha treatment. IFN-gamma and TNF-alpha production was unchanged in the placebo group. rIFN-alpha was tolerated without drop-outs or serious side-effects, but fever, malaise, fatigue (interfering with daily activities in two patients) and leukopenia frequently occurred. High-dose chronic systemic rIFN-alpha might reduce clinical and MRI signs of disease activity in RRMS. The changes in cytokine production suggest that the effect is probably mediated by a down-regulation of proinflammatory cytokine.

Adolescent↗
PubMed1994

Ultrastructure and histochemistry of human anterior lingual salivary glands (glands of Blandin and Nuhn).

BACKGROUND: Specimens of human anterior lingual salivary glands obtained by surgery and by dissection of cadavers were studied ultrastructurally and histochemically. METHODS: Specimens were obtained by surgery for ultrastructural study. Other specimens for histochemistry were obtained by dissection of fresh cadavers. Tissues for electron microscopy were fixed and processed by conventional means. Formalin-fixed cadaver specimens were subjected to a battery of tests for glycoconjugates. RESULTS: The anterior lingual salivary glands are composed predominantly of mucous tubules (which come in two distinct sizes: large and small), seromucous demilunes, and rare seromucous acini. Regardless of tubule size, mucous cells are typical in appearance and, like mucous cells in other human salivary glands, contain filamentous bodies. Histochemically, the larger tubules contain neutral glycoproteins, low concentrations of sialoglycoproteins, and large amounts of sulfated glycoproteins. The small mucous tubules contain neutral glycoproteins, much sialoglycoprotein, and relatively small amounts of sulfated glycoprotein. The seromucous cells, whether demilunar or acinar, are identical. They contain numerous secretory granules, which show a spectrum of internal patterns from one individual to another. These cells have considerable concentrations of neutral- and sialoglycoproteins and lower concentrations of sulfated glycoproteins. Contrary to previously published reports, we could find no differences in the ratio of mucous to seromucous cells along the anterior-posterior lingual axis: there was no gradient of seromucous cells in our specimens. The ducts in the anterior lingual salivary glands are not precise counterparts of those in the major salivary glands, since the former have no capsules, hence lack lobulation. Without these familiar structural landmarks, the only duct that can be identified with certainty is the intercalated duct, and then only if it is in continuity with or lies close to a secretory endpiece. Such ducts consist of simple cuboidal epithelium of prosaic appearance. The ductular epithelium gradually thickens and gives rise to what appear to be excretory ducts consisting of columnar cells with few mitochondria. Scattered within the walls of the larger ducts are patches of typical striated ducts wherein the taller cells display basal striations resulting from highly folded basal plasma membranes and numerous, vertically oriented, virgulate mitochondria. In other atypical regions of the excretory duct, basal cells may have a primary cilium that juts into the intercellular space. CONCLUSIONS: There is a high degree of structural variability in human anterior lingual salivary glands. Because of the technical difficulties in collecting pristine saliva from these glands, the precise function(s) of these organs remains unknown.

Epithelial Cells↗
PubMed1994

Increased intragallbladder pressure stimulates gallbladder eicosanoid release.

The stimulus for increased gallbladder eicosanoid synthesis during cholecystitis is unknown. This study examines the hypothesis that increased intragallbladder pressure stimulates endogenous gallbladder eicosanoid release. Rabbit gallbladders were perfused in vitro at 1 ml/minute with oxygenated Krebs-Henseleit buffer and subjected to 0, 12 or 24 mm Hg of intraluminal gallbladder pressure. Release of 6-keto-PGF1 alpha infinity PGE2 and thromboxane B2 were measured in all groups after 15 and 30 and 60 minutes of perfusion by enzyme immunoassay and gallbladders were examined histologically. Increasing intraluminal gallbladder pressure concomitantly increased gallbladder 6-keto-PGF1 alpha release 2 fold or more at all time of perfusion and altered gallbladder mucosal architecture by increasing basolateral edema in the submucosal space. Infusion of indomethacin (10 micrograms/ml in the perfusion media) decreased 6-keto-PGF1 alpha release from the in vitro perfused gallbladders subjected to 24 mm Hg by 70%. Increased gallbladder eicosanoid release during early cholecystitis may in part be related to the physical force of increased gallbladder intraluminal pressure on the gallbladder mucosa.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Molecular mechanisms regulating CD19, CD20 and CD22 gene expression.

The CD19, CD20 and CD22 genes encode transmembrane proteins that are of vital importance to B-cell function. Similar to the immunoglobulin (Ig) genes, they are expressed in a lineage-specific and developmentally regulated manner. Here, John Kehrl and colleagues describe how an understanding of the transcriptional regulation of the CD19, CD20 and CD22 genes is leading to valuable insights into some of the important molecular events that occur in B-cell development and differentiation.

Animals↗
PubMed1994

Differentiation of breast cancer cells in vitro is promoted by the concurrent influence of myoepithelial cells and relaxin.

Our previous studies showed that relaxin promotes differentiation of MCF-7 breast adenocarcinoma cells. In the current investigation, we aimed to elucidate whether the effect of the hormone is potentiated when MCF-7 cells are grown together with myoepithelial cells, thus creating a microenvironment reminiscent of the organised tissue architecture of the mammary parenchyma in vivo. The findings obtained reveal that most MCF-7 cells cultured alone have an undifferentiated, blast-like phenotype, only a minority showing a more differentiated phenotype with more organelles and rudimentary intercellular junctions. When co-cultured with myoepithelial cells more MCF-7 cells acquire ultrastructural features consistent with a more differentiated phenotype, such as a rich organellular complement, apical microvilli and intercellular junctions. When relaxin was added to the co-cultures, the ultrastructural signs of differentiation could be observed in even more MCF-7 cells and became more pronounced than in the absence of the hormone, judged by the appearance of a clear-cut polarisation of cytoplasmic organelles, an almost continuous coat of apical microvilli and numerous intracellular pseudolumina.

Adenocarcinoma↗
PubMed1994

An electron microscopic study of apoptosis induced by cycloheximide in rat liver.

A histological and ultrastructural study, coupled with transmission and scanning electron microscopy of the early changes in the liver following a single administration of cycloheximide (CHX), was carried out in male Wistar rats. At the histological level, apoptosis was already present in the liver 2 h after treatment. By scanning electron microscopy, the following sequential changes were observed: brightness and progressive detachment of hepatocytes from neighbouring cells, formation of surface infolds with multiple blebs and, finally, release of several membrane-bounded apoptotic bodies (ABs) in the extracellular space and into the sinusoidal lumen. Three hours after CHX administration, the apoptotic cycle was completed, as shown by the presence of phagocytosed ABs inside the cytoplasm of intact liver cells. Light microscopic examination of the liver 6 h after CHX administration showed ABs mainly located in the cytoplasm of intact hepatocytes and inside activated Kupffer cells. By transmission electron microscopy, it was possible to demonstrate that cells undergoing apoptosis were hepatocytes. At 24 h, the livers of treated animals appeared normal, with no evidence of apoptosis.

Animals↗
PubMed1994

Spinal dural arteriovenous fistulas: an underestimated cause of myelopathy.

13 patients with spinal dural arteriovenous fistulas (DAVF) diagnosed in our Institution have been the object of this study. The necessity to include the disease in the differential diagnosis with other pathologies affecting the lower thoracic cord, particularly in middle-aged and old males, is emphasized. Involvement of the spinal cord was always demonstrable on magnetic resonance studies, but pathologic vessels suggesting the possibility of DAVF were seldom recognizable. Myelography still remains an important complementary method. Spinal angiography is essential, taking into account that the fistula can be located far from the spinal cord. The therapy consisting in embolization in 7 cases and embolization associated with surgery in 6 cases led to improvement or stabilization of the disease in all cases. Our cases are discussed in comparison with the literature.

Adult↗
PubMed1994

Chronic systemic high-dose recombinant interferon alfa-2a reduces exacerbation rate, MRI signs of disease activity, and lymphocyte interferon gamma production in relapsing-remitting multiple sclerosis.

We report a randomized, double-blind, placebo-controlled pilot trial of systemic high-dose recombinant interferon alfa-2a (rIFNA) in 20 patients with relapsing-remitting (RR) multiple sclerosis (MS). Patients received 9 million IU rIFNA (n = 12) or placebo (n = 8) intramuscularly every other day for 6 months. Clinical exacerbations or new or enlarging lesions on serial MRI occurred in two of 12 rIFNA-treated and in seven of eight placebo-treated patients (p < 0.005). There was only one enlarging MRI lesion in the rIFNA group, whereas 27 new or enlarging lesions were present in the placebo group (p < 0.01). Baseline lymphocyte interferon gamma production of 19.10 +/- 7.12 IU/ml significantly decreased to 3.03 +/- 0.66 IU/ml (p < 0.04) in the rIFNA group, whereas production was unchanged in the placebo group. The rIFNA was tolerated without dropouts or serious side effects, but fever, malaise, fatigue (interfering with daily activities in two patients), and leukopenia occurred frequently. Neuropsychological tests excluded neurotoxicity. High-dose systemic rIFNA might reduce clinical and MRI signs of disease activity in RR MS and should be investigated in larger trials.

Adolescent↗
PubMed1994

Scanning electron microscopy of chronic hepatitis C. An OsO4 maceration study on human biopsies.

A study at the scanning electron microscope (SEM) on the liver changes in chronic hepatitis C was carried out in human needle biopsies from four patients. Intracellular structures were visualized by a novel modification of the OsO4 maceration method that allows to investigate human pathological specimens. At low magnification we observed both sinusoidal and hepatic cells alterations: sinusoids appeared occluded by lymphocytes, hypertrophic Kupffer cells, activated perisinusoidal cells, necrotic material and apoptotic bodies. Some hepatocytes showed ballooning, arrangement in rosettes, and structural changes related to apoptosis: cell rounding, detachment from neighbouring cells, clustering of cytoplasmic organelles and cell fragmentation. We also found periterminal, sinusoidal, and pericellular severe fibrosis, and bile duct damage of moderate degree. At higher magnification, after removing the intracellular matrix, all the intracellular structures appeared normal, except for focal dilatation of smooth endoplasmic reticulum. Our findings clearly demonstrate the usefulness of the OsO4 maceration method for the study of chronic hepatitis and of liver disease in general. Thank to this technique, in fact, SEM becomes a diagnostic tool complementary to light microscopy and transmission electron microscopy (TEM), for its unique ability to give both low magnification panoramic views and detailed high magnification 3D images of cell organelles.

Biopsy, Needle↗
PubMed1994

[Trazodone versus flunitrazepam in premedication in day-care surgery].

A prospective single-blind study was conducted to compare flunitrazepam vs trazodone in the premedication of patients undergoing day-case surgery for termination of pregnancy, with particular regard to the degree of preoperative sedation, intraoperative analgesia and postoperative recovery. 86 patients were randomly allocated to receive orally 45 minutes before the surgical procedure either flunitrazepam 2 mg (group F) or trazodone 50 mg (group T). In both groups anaesthesia was achieved by i.v. fentanyl 2.5 micrograms/kg and ketamina 250 micrograms/kg. Patients in group F showed a deeper degree of preoperative sedation. There were no significant differences in intraoperative analgesia and in the immediate arousal time. In the postoperative period, the incidences of emetic symptoms and dizziness were similar in both groups; the incidence of drowsiness was significantly higher in group F at 120 minutes but not at 180 minutes of observation. Psychomotor performance was assessed preoperatively two days before the surgical procedure and 60, 120 and 180 minutes after surgery, using the Toulouse-Pieron test and the reaction time to a luminous stimulus with the aid of a computerized analogic tachystoscope (Neurometer). Trazodone allowed a more rapid recovery of psychomotor performance and it can represent a valid alternative to the use of benzodiazepines in the premedication of day-case surgical patients.

Abortion, Induced↗
PubMed1993

3D-structure of cells of human salivary glands as seen by SEM.

To demonstrate by SEM the topography and cytoarchitecture of the different parenchymal components of human salivary glands, we have employed a number of techniques that allow either the exposure of internal and lateral cell surfaces or, following the removal of connective tissue, the visualization of endpieces, ducts, and myoepithelial cells. Serous glands consist of indented acini attached to the ducts in a grape-like fashion, whereas mucous and mixed glands are made up of smooth tubuli. Myoepithelial cells (mecs), which are abundant on the surfaces of acini, tubuli, and intercalated ducts, are sparse on striated ducts. They are star-shaped on acini, striated ducts, and most of the tubuli. Spindle-shaped mecs are seen, instead, on intercalated ducts and, occasionally, on mucous and mixed tubuli as well. Cells of striated ducts split into a number of large basal portions whose surface is covered by long laminated processes responsible for the striations seen with TEM. Excretory ducts are lined by small cup-shaped basal cells and by tall cylindrical cells, which are completely covered by short processes oriented at random. When observed from below, after removal of the basal lamina, the basal surfaces of cells of excretory ducts exhibit polygonal areas delimited by short reliefs. Those of striated ducts show, instead, long laminar processes arranged radially. Results presented here are discussed and put in relationship to the mechanism of saliva production.

Adolescent↗
PubMed1993

Post-translational control of collagen fibrillogenesis in mineralizing cultures of chick osteoblasts.

Cultured osteoblasts from chick embryo calvaria were used as a model system to investigate the post-translational extracellular mechanisms controlling the macroassembly of collagen fibrils. The results of these studies demonstrated that cultured osteoblasts secreted a collagenous extracellular matrix that assembled and mineralized in a defined temporal and spatial sequence. The assembly of collagen occurred in a polarized fashion, such that successive orthogonal arrays of fibrils formed between successive cell layers proceeding from the culture surface toward the media. Mineralization followed in the same manner, being observed first in the deepest and oldest fibril layers. Collagen fibrillogenesis, the kinetics of cross-link formation, and collagen stability in the extracellular matrix of the cultures were examined over a 30 day culture period. Between days 8 and 12 in culture, collagen fibril diameters increased from < 30 nm to an average of 30-45 nm. Thereafter, diameters ranged in size from 20 to 200 nm. Quantitation of the collagen cross-linking residues, hydroxylysyl pyridinoline (HP) and lysyl pyridinoline (LP), showed that these mature cross-links increased from undetectable levels to concentrations found in normal chick bone. Analysis of the kinetics of their formation by pulse-chase labeling the cultures with [3H]lysine showed a doubling time of approximately 5 days. The relationships between cross-link formation, fibrillogenesis, and collagen stability were examined in cultures treated with beta-aminopropionitrile (beta-APN), a potent inhibitor of lysyl oxidase and cross-link formation. In beta-APN-treated cultures, total collagen synthesis was increased twofold, with no change in mRNA levels for type I collagen, whereas the amount of collagen accumulated in the cell layer was decreased by 50% and mineral deposition was reduced. The rate of collagen retention in the matrix was assessed by pulse-chase analysis of [3H]proline over a 16 day period in control and beta-APN-treated cultures. In control cultures, about 20% of the labeled collagen was lost from the cell layers over a 16 day period compared with > 80% in the presence of beta-APN. The beta-APN-treated cultures also showed a wider diversity of fibril diameters with a median in the > 45-60 nm range. In summary, these data suggest that cross-linking and assembly of collagen fibrils secreted by osteoblasts in vitro occur in a fashion similar to that found in vivo. The rate of cross-link formation is relatively constant and may be correlated with increasing collagen mass.(ABSTRACT TRUNCATED AT 400 WORDS)

Aminopropionitrile↗