Biomedical subjects

G Santarelli

Publications and source records attributed to G Santarelli.

At least 19 recordsLinked to original sources

PubMed2005

Long-distance frequency dissemination with a resolution of 10(-17).

We use a new technique to disseminate microwave reference signals along ordinary optical fiber. The fractional frequency resolution of a link of 86 km in length is 10(-17) for a one day integration time, a resolution higher than the stability of the best microwave or optical clocks. We use the link to compare the microwave reference and a CO2/OsO4 frequency standard that stabilizes a femtosecond laser frequency comb. This demonstrates a resolution of 3 x 10(-14) at 1 s. An upper value of the instability introduced by the femtosecond laser-based synthesizer is estimated as 1 x 10(-14) at 1 s.

Journal Article↗

PubMed2004

New limits on the drift of fundamental constants from laboratory measurements.

We have remeasured the absolute 1S-2S transition frequency nu(H) in atomic hydrogen. A comparison with the result of the previous measurement performed in 1999 sets a limit of (-29+/-57) Hz for the drift of nu(H) with respect to the ground state hyperfine splitting nu(Cs) in 133Cs. Combining this result with the recently published optical transition frequency in 199Hg+ against nu(Cs) and a microwave 87Rb and 133Cs clock comparison, we deduce separate limits on alpha/alpha=(-0.9+/-2.9) x 10(-15) yr(-1) and the fractional time variation of the ratio of Rb and Cs nuclear magnetic moments mu(Rb)/mu(Cs) equal to (-0.5+/-1.7) x 10(-15) yr(-1). The latter provides information on the temporal behavior of the constant of strong interaction.

Journal Article↗

PubMed2003

Search for variations of fundamental constants using atomic fountain clocks.

Over five years, we have compared the hyperfine frequencies of 133Cs and 87Rb atoms in their electronic ground state using several laser-cooled 133Cs and 87Rb atomic fountains with an accuracy of approximately 10(-15). These measurements set a stringent upper bound to a possible fractional time variation of the ratio between the two frequencies: d/dt ln([(nu(Rb))/(nu(Cs))]=(0.2+/-7.0)x 10(-16) yr(-1) (1sigma uncertainty). The same limit applies to a possible variation of the quantity (mu(Rb)/mu(Cs))alpha(-0.44), which involves the ratio of nuclear magnetic moments and the fine structure constant.

Journal Article↗

PubMed2001

Mucin histochemistry of the digestive tract of the red-legged frog Rana aurora aurora.

Mucous cells from the digestive tract of the red-legged frog, Rana aurora aurora, were examined by standard histochemical methods and by lectin histochemistry. Two different goblet cell types were found in the oesophageal epithelium. Type I cells produced acidic glycoproteins with beta1,4GlcNAc oligomers, Gal beta1,3GalNAc sequences, sulphated esters on internal residues and abundant non-O-acylated terminal sialic acid bound to penultimate GalNAc. These cells also reacted with Con-A after periodate oxidation-borohydride reduction (PCS). Type II goblet cells mainly differed from type I cells in their negative reaction with PCS. Oesophageal glands consisted of mucous and serous cells. Mucous cells produced neutral stable class III mucosubstances with GalNAc, beta1,4GlcNAc and Gal beta1,3GalNAc residues. Gastric surface cells produced sulpho-sialoglycoproteins with Gal beta1,3GalNAc residues and Gal beta1,3GalNAc-sialic acid as terminal sequences. These cells did not contain stable class III mucosubstances. The mucus produced by foveolar cells was similar in composition but did not contain sulphated groups and was rich in GalNAc residues. The fundic glands consisted of mucous neck cells, endocrine cells and oxyntic cells. The neck cells produced neutral mucins containing D-mannose and/or D-glucose, beta1,4GlcNAc oligomers and Gal beta1,3GalNAc terminal dimers and were PCS-positive. Pyloric glands were of the mucus-secreting type, which produced glycoproteins with the same basic features as those produced in fundic neck cells. A single type of intestinal goblet cells produced acidic glycoproteins rich in beta1,4GlcNAc oligomers, sulphated esters on oligosaccharide chains and terminal O-acylated sialic acid bound to penultimate Gal beta1,3GalNAc. The different carbohydrate structures observed along the digestive tract of the frog may reflect specific functions of the mucus.

Animals↗

PubMed2000

Measurement of the hydrogen 1S- 2S transition frequency by phase coherent comparison with a microwave cesium fountain clock

We report on an absolute frequency measurement of the hydrogen 1S-2S two-photon transition in a cold atomic beam with an accuracy of 1.8 parts in 10(14). Our experimental result of 2 466 061 413 187 103(46) Hz has been obtained by phase coherent comparison of the hydrogen transition frequency with an atomic cesium fountain clock. Both frequencies are linked with a comb of laser frequencies emitted by a mode locked laser.

Journal Article↗

PubMed2000

Lectin histochemistry and ultrastructure of microgranular cells in Cinachyra tarentina (Porifera, Demospongiae).

A histochemical study is described that characterizes microgranular cells of the demosponge Cinachyra tarentina (C. tarentina) with the use of routine staining methods for mucosubstances, lectin histochemistry and electron microscopy. Microgranular cells are rare or absent in other species of sponges, but abundant in this species. Microgranular cells are present in both ectosome and mesohyl, particularly along the canal of the aquiferous system and around spicule holes. Inclusions of microgranular cells and the extracellular matrix were particularly positive for acidic glycoproteins with abundant sulfated ester groups and glycosidic residues containing GalNAc and Galbeta1,3GalNAc. Terminal L-fucose bound to the penultimate GalNAc residues and/or difucosylated oligosaccharides were present as well. Our results suggest that soybean lectin (SBA), peanut lectin (PNA), and winged pea lectin (WPA) are valuable markers for identifying microgranular cells of C. tarentina. Electron microscopy revealed some of the microgranular cells to contain small smooth cytoplasmic vesicles originating from the Golgi complex and few electron-dense granules, others were characterized by numerous secretory granules and vacuoles formed by vesicle fusion and connected with the plasma membrane. Our results suggest that microgranular cells in C. tarentina contribute to the synthesis of glycoprotein components of the extracellular matrix.

Animals↗

PubMed2000

Color-Doppler sonography in ophthalmology.

BACKGROUND: With the present study we considered ocular blood flow by the use of color Doppler ultrasound. We compared the most clinically important arteries of both eyes. We valued the central retinal artery, the posterior long ciliary arteries, the posterior brief ciliary arteries and the central retinal vein. METHODS: We submitted to an ecd examination of the ophthalmic arteries 50 patients, of whom 30 were healthy, 4 presented a pallor of the optic disk, 6 were affected by chronic simple glaucoma and 10 were affected by arterial hypertension. RESULTS: This study has allowed us to define the normal and pathologic anatomic findings at the ecd tracing therefore qualitative and quantitative standards of this examination, repeatable and comparable. CONCLUSIONS: Currently the different techniques used to study ocular blood flow, do not allow its exact detection, but only a morphological evaluation of the eye artero-venous system. Acquisition of morphological and velocimetric data, at the same time, allows a more exact evaluation of the pathology. Therefore the ecd is a simple rapid and non-invasive approach, useful in the acquisition of important data concerning diagnostic confirmation, prognosis, and above all pharmacological follow-up of many pathologies such as diabetes, glaucoma and arterial hypertension. The diagnosed vascular alterations are correlated to the degree retinopathy and to the effectiveness of the pharmacological treatment.

Adult↗

PubMed1998

Implant placement in large edentulous ridges expanded by GBR using a bioresorbable collagen membrane.

The purpose of this study is to evaluate the possibility of expanding an edentulous ridge spanning two or more teeth by a two-step technique with bioresorbable collagen membranes. Sixteen healthy patients were treated, four in the mandible and 12 in the maxilla. The borderline of the crest width was less than or equal to 4 mm. In each patient only one ridge augmentation was performed. After elevation of a full-thickness flap, a surgical stent was positioned to identify the area of ideal implant positioning. The width of the crest at the location of the surgical stent was measured at the time of GBR procedure and 7 to 12 months later during implant insertion. Native collagen sponges were placed buccally and lingually, and a collagen membrane was shaped and trimmed to completely cover the edentulous ridge. The flaps were sutured to achieve primary closure. Antibiotic and clorhexidine mouthrinse were prescribed, and the patients were recalled every 2 weeks. At implant placement, the mean increase in the size of the crest was 2.49 mm (+/- 1.61 mm). In 12 out of 16 patients (75%) it was possible to insert 27 implants according to the prosthetic need established previously. All implants were successfully loaded, and in the four cases where no appreciable results were obtained, no clinical complications or loss of hard and soft tissue were observed.

Adult↗

PubMed1997

Guided tissue regeneration employing a collagen membrane in a human periodontal bone defect: a histologic evaluation.

The purpose of this study is to confirm histologically whether a new attachment can be obtained around a tooth by guided tissue regeneration using bioresorbable barrier. The test tooth was a maxillary molar with an intrabony pocket. At reentry 5 months after periodontal surgery, a hard, whitish, blood-free tissue was found to fill the original defect. Histologic analysis revealed presence of new bone, cementum, and periodontal ligament compatible with the expected histologic result of guided tissue regeneration techniques with barrier membrane.

Absorption↗

PubMed1996

The use of a slowly resorbable collagen barrier in the regeneration of bone in deep wide defects: a case report.

This paper presents a case in which a resorbable collagen membrane and a collagen-based spacemaker and root surface conditioning were used in a guided tissue regeneration procedure. There was no need to disturb the healing potential of the underlying selected cells with an early reentry procedure. Clinical postoperative findings at the time of surgery and in an 18-month follow-up and the differences in density of the mineralized tissues, as detected by standardized series of juxtagingival radiographs and during surgical reentry, showed encouraging results in bone regeneration and soft tissue management.

Adult↗

PubMed1996

Application of slow-resorbing collagen membrane to periodontal and peri-implant guided tissue regeneration.

The utilization of resorbable membranes in the guided tissue regeneration technique allows unquestionable advantages for both the dentist and patient. Collagen is an important constitutive element of the human body and therefore is biodegradable. This study deals with a new slow-resorbing collagen membrane that, when used in conjunction with hydroxyapatite, brings about very interesting results for the treatment of periodontal and peri-implant defects.

Adult↗

PubMed1995

The retinoblastoma gene product in acute myeloid leukemia: a possible involvement in promyelocytic leukemia.

The retinoblastoma susceptibility gene in leukemia and lymphoma has been investigated using different approaches involving either gene or protein analysis. In this study, a novel method, which evaluates the functional status of the retinoblastoma gene product by a binding assay to an in vitro-translated viral oncoprotein, has been applied to leukemic cells from acute myeloid leukemia patients. One hundred twenty-two cases were considered, and 42 of them were also analyzed by Western blot. Results obtained with the two methods were comparable, with the exception of few cases, where the retinoblastoma protein appeared detectable but unable to bind to the viral oncoprotein. The retinoblastoma protein has been found defective mostly in the M3 promyelocytic subtype.

Adenovirus E1A Proteins↗

PubMed1994

MyoD induces retinoblastoma gene expression during myogenic differentiation.

In skeletal muscle cells permanent withdrawal from the cell cycle is a prerequisite for terminal differentiation. The muscle-specific transcription factor MyoD can activate downstream muscle structural genes and myogenic conversion in many different cell types. It has been demonstrated that the product of the retinoblastoma susceptibility gene, with its growth-suppressive activity, is involved in the myogenic function of MyoD (Caruso et al., 1993; Gu et al., 1993). The present study characterises the modulation of retinoblastoma (Rb1) mRNA levels during myogenic differentiation of the murine C2 cell line and provides evidence that the muscle-specific regulatory factor MyoD enhances Rb1 gene transcription. We demonstrate that MyoD mediates the transactivation of a CAT construct whose expression is driven by the human Rb1 gene promoter, and that this is not a consequence of direct binding of MyoD to an E-box DNA sequence motif present in the Rb1 promoter sequences. In addition we have tested the capability of several MyoD mutant proteins of inducing the Rb1 promoter CAT construct. Our results indicate that the MyoD function required for induction of Rb1 promoter activity is distinct from its myogenic function.

Animals↗

PubMed1992

[Bronchogenic carcinoma staging: comparison of magnetic resonance/computerized tomography].

The staging of bronchogenic carcinoma is an important factor to select the appropriate treatment. Indeed, the definition of locoregional spread and of hilar and mediastinal node involvement is essential for both correct preoperative assessment and prognostic evaluation of bronchogenic carcinoma. CT and MR imaging are the methods of choice in the evaluation of T and N, even though other techniques--e.g., US and nuclear medicine--can also provide valuable diagnostic information. The authors examined 50 patients with primary bronchogenic carcinoma by means of plain radiographs, CT and MR of the chest. MR and CT findings were compared with surgical results on the basis of TNM classification. In the evaluation of T, sensitivity and specificity were 66% and 88.6%, respectively, for CT and 76% and 92% for MR imaging. No statistically significant differences were found between the two imaging methods (p = 0.19). In the evaluation of N, sensitivity and specificity were 56% and 78%, respectively, for CT and 76% and 88% for MR imaging. A statistically significant difference was found between MR and CT accuracy rates (p = 0.934). CT and MR results were in disagreement especially in the evaluation of hilar lymph nodes. To date, MR imaging cannot be considered a substitute for or a routine adjunct to CT in the staging of bronchogenic carcinoma due to its poor spatial resolution, to the presence of artifacts (especially with high-intensity fields), its cost and limited availability. However, in the evaluation of specific anatomical regions--e.g., the pulmonary apex and the peridiaphragmatic region--MR can provide more diagnostic information than CT thanks to its multiplanarity and better contrast resolution.

Humans↗

PubMed1989

Early plaque colonization on human cementum.

We have described the morphology of developing plaque on cementum in an in vivo human model. Slabs of cementum obtained from sound teeth, rendered anorganic with 5% sodium hypochlorite, were glued to orthodontic brackets and positioned on the upper canines, premolars and molars in 8 volunteers. The brackets were removed after 2, 4, 8, 24 h and processed for scanning electron microscopy (SEM). Within 2 h, a thin pellicle covered the cementum surface, with few micro-organisms detectable. At 4 and 8 h, coccoid plaques were present. Filaments inserted perpendicularly to the plaque surface were seen at 24 h. The results indicate that early bacterial colonization of human cementum is a selective process, mediated by an organic pellicle and mainly involves cocci.

Bacteria↗

PubMed1989

Periodontitis in a patient with chronic neutropenia.

The aim of this investigation was to obtain information about the composition and the morphology of the microorganisms that inhabit the root surface of a patient with chronic neutropenia and severe and progressive periodontitis. In addition, gingival biopsies were studied by both scanning and transmission electron microscopy (SEM and TEM) to look for bacteria within the gingiva. Dark field microscopy (DFM) revealed 50% spirochetes, 30% motile rods, and 20% coccoid forms. Fourteen extracted teeth studied by SEM showed that the distribution of different bacterial morphotypes varies along the root surface and spirochetes are the prevailing bacteria on the most apically located plaque. TEM analyses of gingival tissue revealed no bacterial invasion within the gingiva. This study suggests that spirochetes may play an important role in the etiology of periodontitis associated with chronic neutropenia. In spite of neutropenic status, there was no bacterial invasion into the gingiva, suggesting that host reaction to dental plaque has not been abolished in this condition.

Adult↗

PubMed1989

[Amount of mineralized tissue removed by root planing].

The Author's aim was to determine the amount of mineralized tissues removed during root planing conducted by means of a curette, using a profilometer. Records were kept at time 0 and after 4 cycles of 5 strokes each. Mean values of final records show that the average of tissue removal, expressed in microns, was greater than the mean thickness of cementum in the instrumented areas.

Dental Cementum↗

PubMed1989

[Blood platelet count and bubble oxygenators. Changes induced by the oral administration of dipyridamole].

The changes in thrombocythemia in patients subjected to extracorporeal circulation (ECC) and pretreated with dipyridamole per os have been examined and compared with a control group in whom the drug was not used; in all patients a circuit with bubble oxygenator was employed. Measurements were carried out before sternotomy, 10' and 60' after ECG, 1 h after the start of intensive therapy and on the 1st surgical day. The variations in thrombocythemia were assessed in consideration of the thrombocythemia/Ht ratio, so as to eliminate the dilution variable. On the basis of the results obtained, it is considered that preoperative treatment with dipyridamole is effective in limiting the fall in thrombocythemia during ECC. The effect of the drug is prevalent in the initial stage of ECC, probably reducing platelet aggregation to non-biological surfaces of the circuit.

Administration, Oral↗