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Biomedical subjects

M Greco

Publications and source records attributed to M Greco.

At least 19 recordsLinked to original sources
PubMed2003

Biologic effects of surface roughness and fluorhydroxyapatite coating on osteointegration in external fixation systems: an in vivo experimental study.

The concomitant influence of surface roughness and fluorhydroxyapatite (FHA) coating of titanium (Ti) implants on bone response was investigated. For this purpose, titanium screw-shaped implants with a lower degree (Y371) and a higher degree (TiPore300) of surface roughness, coated with FHA and uncoated, were transversally inserted into the diaphyses of sheep tibiae for 12 weeks. Four sheep received Y371 (group A) and Y371 + FHA (group B) screws and four sheep received TiPore300 (group C) and TiPore300 + FHA (group D) screws. For each type of material, the morphology and microstructure of implant-facing bone were evaluated. The host bone of each tibia was used as a control. In all groups the bone tissue did not reach a complete maturation. The higher degree of roughness, perhaps due to an excessive irregularity of the surface, induced the worst osteointegration: a fibrous tissue layer between screw and new bone tissue was often present. Nevertheless, as viewed by XRD, no crystallographic change of the apatite lattice was observed in any of the implants. In contrast, the microhardness value, an index of bone mineralization, was higher in the uncoated screws and decreased progressively in the following order: group C > group A > group B > group D. The association of plasma spraying with roughness treatment constitutes a complex system that seems to interfere with bone mineralization. A chemical change of the surface, perhaps with more Ti release or more coating degradation, could be responsible for such impairment. The authors emphasize the necessity for simultaneous evaluation of surface topography and chemistry as well as an improvement in plasma-spraying and post-processing techniques and in standard procedures for materials characterization.

Animals↗
PubMed2003

Ion release in stable hip arthroplasties using metal-on-metal articulating surfaces: a comparison between short- and medium-term results.

The use of metallic heads articulating with metallic cups could solve the problem of polyethylene (PE) wear in total hip replacement (THR) with metal-on-PE bearings. A conspicuous release of metal ions from new models of metal-on-metal bearings has been found in the short-term, but it is yet unclear whether the medium-term corrosion rate is high or, on the contrary, it becomes negligible, because of the continuous surface finishing. Our purpose was to compare the serum ion values (nanograms per milliliter) in 15 patients with metal-on-metal stable prosthesis (Group A), in the short-term (subgroup A(1); mean follow-up: 24 mo) and medium-term (subgroup A(2); mean follow-up: 52 mo), in order to determine whether the ion release decreased with time of implant. Chromium (Cr), cobalt (Co), molybdenum (Mo) and aluminum (Al) were analyzed. Twenty-two presurgical patients were used for comparison (Group B). The reference range was obtained from a population of 27 healthy subjects (Group C). Co and Cr levels in the medium-term (subgroup A(2)) were not decreased in comparison with the short-term values (subgroup A(1)) and were significantly higher (p < 0.001) than presurgical and reference values. Otherwise, Mo and Al concentrations were not significantly increased in comparison with reference values. In conclusion, despite the apparent advantage of metal-on-metal coupling, especially in younger patient populations, there is a major concern about the extent and duration of the relevant "internal" exposure to Cr and Co ions. This exposure should be carefully monitored, in order to clarify the biologic effects of ion dissemination and, consequently, to identify risks concerning long-term toxicity of metals.

Adult↗
PubMed2003

Factors influencing hospital infection control policies in Italian hospitals.

A study was undertaken to determine the resources available in Italian hospitals for the control of nosocomial infections and the factors favouring a successful approach. During January-May 2000 a questionnaire about infection control was sent to the hospital health director of all Italian National Health System hospitals treating acute patients and with more than 3500 admissions in 1999. An active programme was defined as a hospital infection control committee (HICC) meeting at least four times in 1999, the presence of a doctor with infection control responsibilities, a nurse employed in infection control and at least one surveillance activity and one infection control guideline issued or updated in the past two years. There was a response rate of 87.5% (463/529). Almost fifteen percent (69/463) of hospitals had an active programme for Infection Control and 76.2% (353/463) had a HICC. Seventy-one percent (330/463) of the hospitals had a hospital infection control physician and 53% (250/463) had infection control nurses. Fifty-two percent (242/463) reported at least one surveillance activity and 70.8% (328/463) had issued or updated at least one guidance document in the last two years. The presence of regional policies [odds ratio (OR) 8.7], operative groups (OR 4.2), at least one full-time nurse (OR 4.6) and a hospital annual plan which specified infection control (OR 2.1) were statistically associated with an active programme in the multivariate analysis.

Cross Infection↗
PubMed2002

Isolated cavernous sinus extramedullary relapse of chronic myelogenous leukemia following allogeneic stem cell transplant.

Isolated extramedullary relapse of chronic myelogenous leukemia (CML) after allogeneic stem cell transplant is rare. A case is reported of a patient who developed a granulocytic sarcoma of the cavernous sinus 7 months after allogeneic transplant for CML. He presented with neurologic deficits, and a mass lesion was found on imaging. No evidence of hematologic relapse was identified by bone marrow histology or cytogenetics. A premortem diagnosis was not possible, and the patient died 2 months later of an intracerebral hemorrhage after receiving various therapies directed against a presumed infectious etiology. Granulocytic sarcoma should be considered in the differential diagnosis of mass lesions presenting after allogeneic transplant for CML, even if there is no evidence of medullary disease.

Adult↗
PubMed2002

Novel heteroplasmic mtDNA mutation in a family with heterogeneous clinical presentations.

The protean manifestations of a novel maternally inherited point mutation of the mitochondrial genome are reported. The proband showed isolated, spastic paraparesis. A brother, who had suffered from a multisystem progressive disorder, ultimately died of cardiomyopathy. Another brother is healthy. The proband's mother showed truncal ataxia, dysarthria, severe hearing loss, mental regression, ptosis, ophthalmoparesis, distal cyclones, and diabetes mellitus. A muscle biopsy performed in the proband failed to show the morphological abnormalities typical of mitochondrial disorders; the activities of respiratory chain complexes were normal. However, complex I and IV activities were low in the muscle homogenate of the affected mother and brother. Sequence analysis of mtDNA showed a heteroplasmic mutation of the tRNA(Ile) gene (G4284A). The mutation load was approximately 55%, 80%, and 90% in the muscle mtDNA of the proband, his mother, and his affected brother, respectively. Mutation was undetected in the healthy brother, as well as in 100 control samples. Several cybrid clones containing homoplasmic mutant mtDNA from the proband showed significant reductions of complex IV activity and maximum oxygen consumption rate, compared with homoplasmic wild-type clones derived from the same subject.

Adult↗
PubMed2002

Census of radiological machines in Radiodiagnostic Services of public and recognized hospitals in the Campania Region.

AIM: The present study provides a census of equipment in use by Radiodiagnostic Services in public hospitals and institutes recognized by the Region of Campania in the year 2000. The type, date of installation and distribution of the equipment were considered in relation to the number of hospital beds and the resident population. MATERIALS AND METHODS: A census was taken of all the public hospitals and institutes recognized by the Region of Campania in the period running from January 1999 to April 2000. Data were collected using an appropriate form asking for details of the number of machines and the model, manufacturer and year of installation, under six categories: traditional radiology, mammography, US, CT, MR and angiography. The data were analyzed by provinces, combining the different machines into five-year periods depending on the date of their installation. RESULTS: Traditional radiology equipment accounts for 71% of the total. The mean for the Region stands at 23 machines per 1000 beds. The mean date of installation was 1986. Mammography machines account for 8% of the total. The mean for the Region stands at 2.6 machines per 1000 beds. The mean date of installation was 1991. Echography machines account for 10.3% of the total. The mean for the Region stands at 3.4 machines per 1000 beds. The mean date of installation was 1992. Angiography machines account for 3.2% of the total. The mean for the Region stands at 1.1 machines per 1000 beds. The mean date of installation was 1985. CTs account for 6.4% of the total. The mean for the Region stands at 2.1 machines per 1000 beds. The mean date of installation was 1993. MR account for 1.1% of the total. The mean for the Region stands at 0.4 machines per 1000 beds. The mean date of installation was 1995. CONCLUSIONS: Technological and scientific improvements and growing attention to the quality of medical care expected by patients mean that constant modification and adaptation are needed to meet demands. In planning measures designed to provide new radiological equipment and modernize existing equipment in the Region it would certainly be useful to eliminate the unevenness of the services provided. In conclusion, it is crucial that the local administrations and health authorities in the Campania Region establish a regular census, with proper assessment of the obsolescence of radiological equipment and its distribution throughout the area, in order to comply with international standards.

Equipment and Supplies↗
PubMed2001

Hypocretin-2-saporin lesions of the lateral hypothalamus produce narcoleptic-like sleep behavior in the rat.

Hypocretins (Hcrts) are recently discovered peptides linked to the human sleep disorder narcolepsy. Humans with narcolepsy have decreased numbers of Hcrt neurons and Hcrt-null mice also have narcoleptic symptoms. Hcrt neurons are located only in the lateral hypothalamus (LH) but neither electrolytic nor pharmacological lesions of this or any other brain region have produced narcoleptic-like sleep, suggesting that specific neurons need to be destroyed. Hcrt neurons express the Hcrt receptor, and to facilitate lesioning these neurons, the endogenous ligand hypocretin-2/orexin B (Hcrt2) was conjugated to the ribosome-inactivating protein saporin (SAP). In vitro binding studies indicated specificity of the Hcrt2-SAP because it preferentially bound to Chinese hamster ovary cells containing the Hcrt/orexin receptor 2 (HcrtR2/OX(2)R) or the Hcrt/orexin receptor 1 (HcrtR1/OX(1)R) but not to Kirsten murine sarcoma virus transformed rat kidney epithelial (KNRK) cells stably transfected with the substance P (neurokinin-1) receptor. Administration of the toxin to the LH, in which the receptor is known to be present, eliminated some neurons (Hcrt, melanin-concentrating hormone, and adenosine deaminase-containing neurons) but not others (a-melanocyte-stimulating hormone), indicating specificity of the toxin in vivo. When the toxin was administered to the LH, rats had increased slow-wave sleep, rapid-eye movement (REM) sleep, and sleep-onset REM sleep periods. These behavioral changes were negatively correlated with the loss of Hcrt-containing neurons but not with the loss of adenosine deaminase-immunoreactive neurons. These findings indicate that damage to the LH that also causes a substantial loss of Hcrt neurons is likely to produce the multiple sleep disturbances that occur in narcolepsy.

Adenosine Deaminase↗
PubMed2001

Axillary lymph node staging in breast cancer by 2-fluoro-2-deoxy-D-glucose-positron emission tomography: clinical evaluation and alternative management.

BACKGROUND: Surgical removal of axillary lymph node and histologic examination for metastases are used to determine whether adjuvant treatment is necessary for patients with breast cancer. Axillary lymph node dissection (ALND) is a costly procedure associated with various side effects, and 80% or more of patients with tumors of 20 mm or less are lymph node negative and might avoid ALND. In this study, we evaluated whether an alternative, noninvasive method--i.e., positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-- could be used to determine axillary lymph node status in patients with breast cancer. METHODS: One hundred sixty-seven consecutive patients with breast cancers of 50 mm or less (range = 5-50 mm; mean = 21 mm) scheduled for complete ALND were studied preoperatively with FDG-PET, and then PET and pathology results from ALND were compared. All statistical tests were two-sided. RESULTS: The overall sensitivity, specificity, and accuracy of lymph node staging with PET were 94.4% (PET detected 68 of 72 patients with axillary involvement; 95% confidence interval [CI] = 86.0% to 98.2%), 86.3% (82 of 95 patients without axillary involvement; 95% CI = 77.8% to 91.9%), and 89.8% (150 of 167 patients with breast cancer; 95% CI = 84.2% to 93.6%), respectively. Positive- and negative-predictive values were 84.0% (68 patients with histologically positive lymph nodes of 81 patients with positive FDG-PET scan; 95% CI = 74.2% to 90.5%) and 95.3% (82 patients with histologically negative lymph nodes of 86 patients with negative FDG-PET scan; 95% CI = 88.2% to 98.5%), respectively. When PET results for axillary metastasis were analyzed by tumor size, the diagnostic accuracy was similar for all groups (86.0%-94.2%), with higher sensitivity for tumors of 21-50 mm (98.0%) and higher specificity for tumors of 10 mm or less (87.8%), and the range was 93.5%-97.3% for negative-predictive values and 54.5%-94.1% for positive-predictive values. Among the 72 patients with axillary involvement, PET detected three or fewer metastatic lymph nodes in 27 (37.5%) patients, about 80% of whom had no clinically palpable axillary lymph nodes. CONCLUSIONS: Noninvasive FDG-PET appears to be an accurate technique to predict axillary status in patients with breast cancer and thus to identify patients who might avoid ALND. These results should be confirmed in large multicenter studies.

Adult↗
PubMed2001

Growth kinetics and structure of fibrin gels.

The structure and kinetics of fibrin gels grown from fibrinogen solutions under quasiphysiological conditions, but in absence of Ca++, were investigated by means of elastic light scattering. By combining classical light scattering and low-angle elastic light scattering, an overall wave-vector range of about three decades was spanned, from q approximately 3 x 10(2) to q approximately 3 x 10(5) cm(-1). The scattered intensity distribution of the gels was measured in absolute units and fitted to a single function, which was able to reproduce accurately the data over the entire wave-vector range. From the fitting, it was possible to estimate the average diameter d of the fibrin fibers, the average crossover length xi of the gel, and establish the fractal nature of the gel structure, with a measure of its fractal dimension D(m). The measure of the intensity in absolute units also allowed the estimate of the density rho of the fibrin fibers and provided an independent measure of their size. The kinetics of formation of the gel was described in terms of a simple growth model: the scaffold of the network is formed very early in the course of the gelation process, at a "networking time," t(n), which is much smaller than the time required to form the final gel. At times t>t(n), the gel structure remains substantially unchanged and the successive growth consists only in a thickening of the gel fibers. Gels prepared under the same physical-chemical conditions, but at different fibrinogen concentrations, exhibited rather similar structures and kinetics, showing that the modalities of the gelation process are mainly governed by the solution conditions, and only secondarily by the fibrinogen concentration. For gels at fibrinogen concentration of approximately 0.24 mg/ml, the gel parameters were d approximately 130 nm, xi approximately 27 microm, D(m) approximately 1.3, and rho approximately 0.4 g/cm(3). Our d and rho values are in very good agreement with electron microscopy- and turbidity-derived literature data, respectively, while xi seems to be related to the mesh size of the initial scaffold formed at t(n), rather than to the mesh size of the final aged gel.

Fibrin↗
PubMed2001

Helium-Neon laser irradiation of hepatocytes can trigger increase of the mitochondrial membrane potential and can stimulate c-fos expression in a Ca2+-dependent manner.

BACKGROUND AND OBJECTIVE: To gain some insight into the photostimulation of isolated hepatocytes irradiated with Helium-Neon (He-Ne) laser light certain biochemical events were studied with respect to two mechanisms: i) the direct light dependent activation of certain biochemical events investigated in intact cells and isolated mitochondria, ii) the indirect stimulation of processes per se light independent. STUDY DESIGNS/MATERIALS AND METHODS: Irradiation of either isolated hepatocytes or isolated rat liver mitochondria was carried out with He-Ne laser (wavelength, 632.8 nm; fluence, 0.24 J cm-2; fluence rate, 12 mW cm-2). Changes in mitochondrial membrane potential in isolated hepatocytes were monitored using the cationic probe safranine. The c-fos expression was studied by Northern blot and immunoblot analysis. RESULTS: As a result of irradiation, increase of the mitochondrial membrane potential was found to occur in irradiated hepatocytes both in the presence or in the absence of CaCl2. The hyperpolarization of the mitochondrial membrane is assumed to cause an increase in mitochondrial Ca2+ uptake that was measured in isolated mitochondria. Finally, an increase in c-fos expression was found in irradiated hepatocytes when incubated in the presence of CaCl2. CONCLUSION: This paper gives additional information on the mechanism by which He-Ne laser light, either directly or in a cascade-like effect dependent on increase in cell Ca2+, can cause cell stimulation.

Animals↗
PubMed2001

Hypothalamic regulation of sleep.

The recent discovery linking narcolepsy, a sleep disorder characterized by very short REM sleep latency, with a neuropeptide that regulates feeding and energy metabolism, provides a way to understand how several behaviors may be disrupted as a result of a defect in this peptide. In this chapter we review the evidence linking hypocretin and sleep, including our own studies, and propose that a defect in the lateral hypothalamus that also involves the hypocretin neurons is likely to produce a disturbance in sleep, mood, appetite, and rhythms.

Animals↗
PubMed2001

Impact of patient feedback on the interpersonal skills of general practice registrars: results of a longitudinal study.

CONTEXT: A general practice vocational training program. OBJECTIVES: To examine the impacts and implications of different models of systematic patient feedback on the development of general practice (GP) registrars' interpersonal skills as they progressed through a GP vocational training program. DESIGN: A longitudinal study in which GP registrars were randomly assigned to three models of patient feedback: a control group and two intervention groups. The major source of data gathering was through the Doctors' Interpersonal Skills Questionnaire (DISQ) which was administered to patients immediately after their consultation. SUBJECTS: 210 GP registrars, 104 GP supervisors and 28 156 patients. RESULTS: Multivariate analysis techniques (including repeated-measures analysis) tested the effectiveness of the interventions. Findings showed that systematic patient feedback at regular intervals throughout GP training resulted in sustained levels of interpersonal skills. The most significant gains in interpersonal skills for both intervention groups occurred in the earlier stages of general practice training. Most registrars found the experience of patient feedback useful for gaining a better understanding of their interpersonal skills and for identifying areas in which they needed to improve. GP supervisors valued the opportunity to receive patient feedback themselves and found the activity a useful adjunct to their preceptor role. CONCLUSIONS: Patients, by providing feedback on doctors' interpersonal skills, have been able to contribute to improving the quality of the patient-doctor interaction. GP registrars and their supervisors value highly the role of patient feedback in interpersonal skill development.

Adult↗
PubMed2001

The "Nordstrom suture" to enhance scalp reductions.

The authors compared the results of 10 scalp reductions using the "Nordstrom suture" with the earlier published results of scalp reductions without a device to prevent stretch-back and of reductions with extenders. At 1 month postoperatively, the Nordstrom suture eliminated the stretch-back of 8.3 mm seen in earlier studies and, in fact, it shrank the bald area. The average shrinking achieved with the Nordstrom suture was 16.9 mm (i.e., 143 percent improvement over scalp reductions alone). Scalp extenders shrank the bald area, but the Nordstrom suture shrank the area about three times more than extenders at 1 month postoperatively.

Alopecia↗
PubMed2001

One-step detection and genotyping of human papillomavirus in cervical samples by reverse hybridization.

This study describes a nonisotopic polymerase chain reaction-reverse hybridization-based method (PCR-RH) for the one-step detection and genotyping of anogenital human papillomavirus (HPV) in a microwell format. HPV DNA was amplified and labeled by PCR using GP5+/GP6+ primers. Labeled amplicons were hybridized to 20 HPV type-specific capture probes anchored to the surface of plastic microwells and detected by an immunoenzymatic assay. Assay sensitivity was <50 pg labeled amplicon, and no cross-reactivity was observed, as determined by hybridizing serial dilutions of labeled PCR products to either matched or mismatched capture probes. The assay was tested on 66 clinical samples (23 specimens with normal histology, I fibropapilloma, 26 cervical intraepithelial neoplasia grade 1 [CIN1], 9 CIN2, and 7 CIN3) and compared with a method based on restriction fragment length polymorphism (RFLP) of PCR products. PCR-RH and PCR-RFLP performed equally well on clinical samples. The overall HPV detection rate was similar: 65.1% (43/66) for PCR-RH and 57.6% (38/66) for PCR-RFLP. HPV DNA was found in all CIN2 and CIN3 samples by both methods; however, PCR-RH detected more positives among normal biopsy samples and CINI cases. Overall, there was good agreement between the two genotyping methods, but RH yielded fewer cases with undetermined HPV genotype.

Consensus Sequence↗
PubMed2001

Radioimmunoassay to detect antitransglutaminase autoantibodies is the most sensitive and specific screening method for celiac disease.

OBJECTIVE: The aim of this study was to establish the most sensitive and specific screening method for celiac disease. We tested three methods based on different principles, which all detect autoantibodies against the same antigen (tissue transglutaminase). METHODS: Sixty-two celiac children at the first biopsy (group 1), 78 celiac children on a gluten-free diet (group 2), 14 celiac children on a gluten-challenge (group 3), and 56 controls with a normal duodenal mucosa (group 4) were studied. The methods used were: 1) radioimmunoprecipitation assay using recombinant tissue transglutaminase (RIA); 2) commercial enzyme immunoassay using guinea pig tissue transglutaminase (ELISA); and 3) indirect immunofluorescence method for detection of antiendomysium antibodies (IF-EMA). RESULTS: RIA antitransglutaminase autoantibodies were detected in 100% of group 1, 43.6% of group 2, 100% of group 3, and none of the control subjects. ELISA antitransglutaminase autoantibodies were detected in 90.3% of group 1, 9% of group 2, 78.6% of group 3, and in none of the control subjects. IF-EMA were detected in 95.2% of group 1, 11.5% of group 2, 92.3% of group 3, and 1.8% of the controls. CONCLUSIONS: Our results demonstrate a very high sensitivity and specificity of the RIA method to detect antitransglutaminase autoantibodies in comparison to ELISA and IF-EMA assays. We can explain this finding with the use of human recombinant antigen and the increased capacity of the RIA method to detect low titers of autoantibodies. If our data are confirmed by studies on larger series, tissue transglutaminase RIA could be proposed as the best screening method for celiac patients.

Adolescent↗