Biomedical subjects

A Ruggeri

Publications and source records attributed to A Ruggeri.

At least 37 records · Page 2Linked to original sources

PubMed2000

Qualitative assessment of natural apatite in vitro and in vivo.

Among the natural and synthetic materials investigated as bone graft substitutes, much interest has been focused on natural apatite obtained from low temperature heat-deproteinated compact bone. Previous research demonstrates that, when treated at a temperature below 500 degrees C, this material maintains its characteristic ultrastructural features, with a high surface/volume ratio, while as an implant material, it offers the host tissue a large surface of interaction. In vitro and in vivo tests showed that natural apatite is well tolerated and is a good osteoconducing material. The present in vivo study in rabbits was carried out to first investigate the behavior and capacity of natural apatite implants to stimulate bone ingrowth, and then to analyze the cells located at the bone/material interface. Synthetic hydroxyapatite was used as a control material. In a parallel in vitro study, we investigated the activity of differentiated osteoblasts and periosteal cells obtained from rats and new-born rabbits, incubated with natural apatite and synthetic hydroxyapatite. The in vivo study showed that natural apatite allows osteoblasts to form new bone tissue, adhering to the implant with ingrowth into the implant structure. In the presence of synthetic hydroxyapatite, a less pronounced osteoblastic activity was observed. In agreement with these observations, the in vitro study showed that natural apatite is more effective in attracting cells, favoring their proliferation and stimulating alkaline phosphatase activity. These findings suggest that natural apatite is more suitable for bone filling or bone regeneration than synthetic hydroxyapatite.

Animals↗

PubMed2000

A histological and electron-microscopic study of the architecture and ultrastructure of human periodontal tissues.

The structure of periodontal tissues is still far less understood than their clinical relevance would demand. Here the periodontal ligament and radicular cementum in healthy human teeth were studied by light microscopy, transmission and scanning electron microscopy. These observations showed that the extracellular matrix of periodontal ligament is composed of a loose plexus of wavy collagen fibrils immersed in a highly hydrated interfibrillar matrix. Only close to their cemental insertion do these fibrils gather in thick, parallel fascicles (Sharpey's fibres). As these cross the mineralization front, they become infiltrated by the mineral phase and continue directly with the cementum matrix. Sharpey's fibres, "extrinsic" and "intrinsic" fibres all appear to be the same fibres, which bend and branch repeatedly during their course within the thickness of the cementum. Because of its physical continuity with the cementum, a limited portion of the periodontal ligament approximately corresponding to the length of Sharpey's fibres remains unaffected by enzymatic digestion of the interfibrillar matrix while the rest of the ligament is completely dissolved. The findings here indicate that the periodontal ligament and dental cementum join by a continuity rather than a contiguity of structures; that the collagen-mineral relation in cementum has distinctive features in comparison to other hard tissues; that extrinsic and intrinsic fibres of cementum and the adjoining portion of periodontal ligament form a structural, mechanical and metabolic unit distinct from the central, more metabolically active portion of the periodontal ligament.

Collagen↗

PubMed2000

A program for the optimization of cyclosporine therapy using population kinetics modeling.

Cyclosporine is one of the most widely used immunosuppressive agents in organ transplantation. Due to large inter- and intra-individual variations, its behavior in the specific patient is still difficult to predict. Dosage optimization is thus mainly performed on a trial-and-error basis. In this paper, we present a new program based on the population kinetics approach, which was designed to help physicians in the difficult task of adjusting patient specific cyclosporine dosing regimens. Dose optimization is carried out by model simulation, using a two-compartment mathematical model of cyclosporine kinetics to predict the drug behavior in the patient. Two of the model parameters are assumed from the literature, the other two are estimated from the patient data through a Bayesian estimation procedure. Previous information needed by the Bayesian algorithm is derived by a population analysis, performed beforehand and based on a nonlinear mixed effect model. A user-friendly graphical interface written in Delphi under Windows makes the program easily accessible to physicians. A preliminary retrospective validation of the program, performed on data from 18 renal transplanted patients, yielded very satisfactory results.

Algorithms↗

PubMed2000

A simulation study for the design of a control system for the blood concentration process in autotransfusion.

Autotransfusion is the process in which a patient serves as his or her own blood donor; its most important application is the intraoperative blood salvage, in which the blood collected during a surgical operation is filtered, concentrated, washed, and then reinfused. In an automatic autotransfusion device, such as the DIDECO Compact Advanced, red blood cells (RBCs) are separated from the other unwanted components and concentrated by using a rotating bowl and the effect of centrifugal force. An important characteristic of concentrated RBCs is their hematocrit (Hct), i.e., percent RBC volume divided by total blood volume. The aim of this study is to assess the feasibility of a controller, based on the artificial neural network approach, which is able to provide a closed loop control of the hematocrit of the blood in the bowl at the end of the concentration phase. A simulation approach was adopted both for training the network and for assessing its performances. The results obtained are quite satisfactory, since the target Hct was typically reached within a 3% error, and always within 6% in highly challenging situations.

Biomedical Engineering↗

PubMed2000

Different patterns of collagen-proteoglycan interaction: a scanning electron microscopy and atomic force microscopy study.

The extracellular matrix of unfixed, unstained rat corneal stroma, visualized with high-resolution scanning electron microscopy and atomic force microscopy after minimal preliminary treatment, appears composed of straight, parallel, uniform collagen fibrils regularly spaced by a three-dimensional, irregular network of thin, delicate proteoglycan filaments. Rat tail tendon, observed under identical conditions, appears instead made of heterogeneous, closely packed fibrils interwoven with orthogonal proteoglycan filaments. Pre-treatment with cupromeronic blue just thickens the filaments without affecting their spatial layout. Digestion with chondroitinase ABC rids the tendon matrix of all its interconnecting filaments while the corneal stroma architecture remains virtually unaffected, its fibrils always being separated by an evident interfibrillar spacing which is never observed in tendon. Our observations indicate that matrix proteoglycans are responsible for both the highly regular interfibrillar spacing which is distinctive of corneal stroma, and the strong interfibrillar binding observed in tendon. These opposite interaction patterns appear to be distinctive of different proteoglycan species. The molecular details of proteoglycan interactions are still incompletely understood and are the subject of ongoing research.

Animals↗

PubMed1999

Structural and functional macrophages alterations by ceramics of different composition.

Biomaterials may initiate several and complex biological reactions in host tissues, and the cell-biomaterial interactions can determine the release of mediators including monocytes and lymphocytes chemotactic factors. The present work was aimed to investigate in vitro the macrophage biological reactions of a natural apatite obtained by heat treatment at 400 degrees C of bovine bone, compared to other ceramics usually used for dental and orthopedic applications, using synthetic apatite and three types of alumina as controls. Particles chemotactic activity and powders oxidative burst evidenced no monocyte macrophages sensitivity reaction for natural and synthetic hydroxyapatite powders at great granulometry (> 50 microm); data were confirmed by ultrastructural observations; electron microscopy analysis showed macrophages with the features of healthy cells in the presence of both natural and synthetic apatites while macrophages grown in the presence of alumina seemed to be negatively affected. In conclusion, among all ceramics tested, natural apatite displayed a good compatibility with living cells, being better tolerated than synthetic hydroxyapatite which in turn is better tolerated than alumina.

Aluminum Oxide↗

PubMed1999

Magnetic resonance imaging findings of Kernohan-Woltman notch in acute subdural hematoma.

OBJECTIVE AND IMPORTANCE: We report the case of a 73-year-old patient who presented a right motor deficit caused by an ipsilateral acute subdural hematoma. A magnetic resonance imaging (MRI) demonstration of Kernohan-Woltman notch phenomenon was obtained. CLINICAL PRESENTATION: The woman sustained a major head injury at home, followed by loss of consciousness. On admission to the emergency room, she was comatose, anisochoric (left > right), and showed a reaction to pain with decerebrating movements of left limbs (Glasgow Coma Scale (GCS) 4/15). A right severe hemiparesis was observed. Cerebral computed tomography scan showed a large right hemispheric subdural hematoma. INTERVENTION AND POST-OPERATIVE COURSE: A wide right craniotomy was performed and the subdural hematoma evacuated. During the post-operative period, the level of consciousness gradually improved. A MRI performed about 2 weeks after operation showed a small area of abnormal signal intensity in the left cerebral peduncle. On discharge, the woman was able to communicate with others, but her right hemiparesis was still severe.

Aged↗

PubMed1999

Anterior clinoidal meningiomas: report of a series of 33 patients operated on through the pterional approach.

Between 1985 and 1995, 33 cases of clinoidal meningioma were surgically treated by pterional approach. In 6 cases, according to the grading scale of Al-Mefty, the lesions were group I, having originated from the lower part of the clinoid; in 22 cases, the lesions were group II, having originated from the upper or lateral part of the clinoid process; and in 5 cases, the lesions were group III since they arose from the optic foramen. Postoperatively, 17 patients showed an improvement, 4 were unchanged, and 6 presented further deficits. Five patients died after surgery: two from pulmonary thromboembolism, one from myocardial infarction, one from hematoma of the operative field, and one from cerebral ischemia after severe vasospasm of the internal carotid artery (unresponsive to treatment). The mean follow-up was 53.7 months (range 12-108 months) and included 19 patients. During this period, there were five recurrences, and three patients underwent resection again and showed no signs of tumor regrowth 1 year later; one patient who did not undergo resection again due to his age and poor general conditions died 3 years after onset of the recurrence; the last patient has so far refused a second operation. The clinical, diagnostic, and therapeutic aspects of this not infrequent pathology are discussed in the light of our experience and the pertinent literature.

Adolescent↗

PubMed1999

The role of MRI in the surgical selection of cerebral metastases.

BACKGROUND: About one third of patients operated on for a "single" cerebral metastasis diagnosed by CT scan have probably more than one lesion. In fact, Gd-DTPA enhanced MRI has proved to be more sensitive than CT in detecting the number of cerebral metastases, reducing the number of patients candidate to surgery. METHODS: Thirty-five patients with a CT scan picture of a single cerebral neoplasm of presumable metastatic nature performed a Gd-DTPA enhanced cerebral MRI. In 25 cases MR images confirmed a single lesion, while in other 10 (28.6%) showed a number of metastases ranging from 2 to 6. In order to assess the utility of MRI in surgical selection of patients and then to reconsider the concept of operability limited to single brain metastases only, we compared the survival of the 25 cases who preoperatively performed MRI (MRI group) with that of other 25 consecutive patients operated on in pre-MR era (during a 24-month period), with a CT picture of single cerebral metastasis (non-MRI group). RESULTS: The median survival was 36 +/- 5 weeks for MRI group and 40 +/- 15 for non-MRI group. The Kaplan-Meier product-limit survival analysis and the log-rank test do not reveal any statistically significative difference of survival between the two groups. CONCLUSIONS: Even if the number of patients is limited for definitive considerations, our preliminary results seem to suggest that the further selection of surgical cases obtained with MRI could not impact significatively the survival. Therefore, in selected patients with multiple cerebral metastases a surgical treatment could be reasonable.

Adult↗

PubMed1999

Intramedullary increased MR signal intensity and its relation to clinical features in cervical myelopathy.

BACKGROUND: Areas of intramedullary hyperintensity in patients with cervical spondylogenetic myelopathy (CSM) have been described and studied by several authors. METHODS: In the present study, 100 patients were reappraised and divided into 2 groups according to whether or not MRI detected areas of hyperintensity on T2-weighted images. RESULTS: Statistical analysis demonstrated that intramedullary hyperintensity is most frequently associated with severe impairment of deambulation, muscular hypotonus-hypotrophy and hypoesthesias of the upper limbs. CONCLUSIONS: These radiological findings probably correspond to various types of lesions which, when irreversible, may influence postoperative neurological recovery.

Adult↗

PubMed1999

Relationship between Ki-67 labeling index and survival in high-grade glioma patients treated after surgery with tamoxifen.

BACKGROUND: The Ki-67 is a nuclear antigen expressed in the G1, S, G2, and M phases of the cell cycle recognizable by the monoclonal antibody MIB-1. The Ki-67 labeling index (LI) is considered as a marker of proliferation (growth fraction rate), even if its use as prognostic indicator of cerebral high-grade gliomas is still debated. The aim of this study is to correlate the Ki-67 LI with survival in patients operated on for a malignant glioma and treated postoperatively with tamoxifen. METHODS: Using the MIB-1 antibody, the Ki-67 antigen staining of surgical specimens was obtained in 26 patients operated on for a malignant cerebral glioma. After operation, 9 patients started to receive 40 mg/day, 8 patients 80 mg/day, and 9 patients 120 mg/day of tamoxifen. In 20 cases one or more cycles of i.v. carboplatin was administered. All patients received radiotherapy (4500-6000 cGy). RESULTS: The overall mean survival rate was 19.8 months and the median 12 months; the 12-month and 24-month survival rates were 47% and 23%, respectively. The Ki-67 LI ranged from 2.3% to 62% (mean 24.1%, median 20.5%). Excluding 2 patients who died during the postoperative period, we analyzed the survival rates of the remaining 24 patients in relation to the value of Ki-67 LI. In relation to the index, patients have been divided into 3 groups, with different survival rates: L) Ki-67 LI < or =10%, with mean survival rate of 30.7 months, M) from 10.1% to 30%, with mean survival rate of 15.8 months, and H) >30%, with mean survival rate of 20.2 months. CONCLUSIONS: Our preliminary observations seem to confirm the efficacy of TAM in modifying the survival of malignant gliomas and seem to indicate that tumors with a lower LI and those with a LI >30% could be associated, if treated with TAM, with a better survival than gliomas belonging to group M, who could have a higher tumor proliferation rate in comparison to group L and a lower response to protein-kinase-C antagonists than group H.

Adult↗

PubMed1998

Cytochemical and microbiological testing of CSF and catheter in patients with closed continuous drainage via a lumbar subarachnoid catheter for treatment or prevention of CSF fistula.

A study was performed to evaluate the efficacy of closed continuous drainage (CCD) via a lumbar subarachnoid catheter for prevention or treatment of CSF fistulas. In addition to the analysis of the physical, chemical and biological properties of the CSF obtained, the catheters themselves were tested on removal to identify any microorganisms contaminating them. Other factors taken into consideration were the symptoms reported by the patients during positioning of the catheter and while it was in place, any variations in body temperature and local inflammatory effects on the nerve roots of the cauda equine and surrounding tissues. The low percentage of systemic and local infections observed testifies to the safety of this method, regardless of the duration of treatment.

Adult↗

PubMed1998

Early surgical treatment of intracerebral hemorrhages caused by AVM: our experience in 10 cases.

Between February, 1980, and April, 1993. 10 patients with intraparenchymal hemorrhage due to the bleeding of an arteriovenous malformation (AVM) underwent emergency surgical procedures within an average time of 3 hours (min. 2-max. 7) from casualty to admission. Rapid neurological worsening and mass effect of the extensive intracerebral hemorrhage prompted early surgical treatment. Post-operative angiography was performed to confirm that the malformation had been excluded from the circulation. The aim of this study is to evaluate the role of early surgery in patients requiring emergency surgical procedures for severe neurological injury induced by extensive intracerebral hematoma produced by AVM bleeding.

Adolescent↗

PubMed1998

Intracranial actinomycosis in juvenile patients. Case report and review of the literature.

A case of actinomycotic brain infection in a juvenile patient is described. Cases of actinomycosis affecting the head and neck are rare, particularly in juvenile patients. In this case complete resolution of the infection was achieved by means of surgical treatment and prolonged antibiotic therapy. The authors emphasize the importance of a combined approach for treatment of this unusual brain infection and stress the difficulties involved in the diagnosis of this pathology.

Abscess↗

PubMed1998

Tamoxifen modulation of carboplatin cytotoxicity in a human U-138 glioma cell line.

Glioma cells express high protein kinase C (PKC) activity, which may represent an important therapeutic target. Tamoxifen (TAM) has moderate PKC-inhibiting activity, blocking DNA synthesis and cellular proliferation in human glioma cells at concentrations that can be achieved therapeutically. Carboplatin (CBDCA), a second-generation platinum derivative, induces intra- and interstrand DNA-protein crosslinks producing inhibition of tumor-cell growth. In the present study, the effect of TAM, CBDCA, and the combination of both was evaluated against the human established U-138 glioma cell line during the exponential growth phase (48-72 h) by means of both the Biorad protein assay (BPA) method and Trypan blue exclusion study (TBES). Both TAM and CBDCA reduced the cellular growth rate, with a median 50%-inhibiting concentration (IC50) of 12.5 microM for TAM and 350 microM for CBDCA. The U-138 glioma cell line showed a moderate response to 100 microM of CBDCA, with < or = 10% reduction of the growth rate. The association of both chemotherapeutic agents induced a 98% reduction of the IC50 dose of TAM (0.1 microM), and a 71% reduction of the IC50 dose of CBDCA (100 microM). During the combinational TAM CBDCA exposure we observed a cytotoxic effect of TAM at concentrations lower than 0.1 microM, not recognized using it as a single drug. The differences observed among the IC50 doses (TAM, CBDCA, TAM-CBDCA) and among treated and untreated matched control cells were statistically significant (P < 0.01). Our results confirm previous observations about the efficacy in vitro of TAM against human glioma cell lines and show a marked enhancement of this activity by CBDCA.

Antineoplastic Agents↗

PubMed1998

Collagen fibril arrangement and size distribution in monkey oral mucosa.

Collagen fibre organisation and fibril size were studied in the buccal gingival and hard palate mucosa of Macacus rhesus monkey. Light and electron microscopy analysis showed connective papillae exhibiting a similar inner structure in the different areas examined, but varying in distribution, shape and size. Moving from the deep to surface layers of the buccal gingival mucosa (free and attached portions), large collagen fibril bundles became smaller and progressively more wavy with decreasing collagen fibril diameter. This gradual diameter decrease did not occur in the hard palate mucosa (free portion, rugae and interrugal regions) where the fibril diameter remained constant. A link between collagen fibril diameter and mechanical function is discussed.

Animals↗

PubMed1998

Tamoxifen as a potential treatment of glioma.

Cerebral gliomas have a poor survival time even after multimodal treatment, because of the unavoidable recurrence of tumor. Several trials with a combination of old and new chemotherapics have been performed, but survival time remains generally less than 12 months. Tamoxifen (TAM) has recently been shown to inhibit the growth rate of established and low-passage human glioma cell lines. Furthermore, this drug has enabled stabilization of the clinical and radiographic picture in selected patients with recurrent glioma. Here we review published data to discuss a potential role of TAM in the multimodal postoperative treatment of cerebral gliomas.

Antineoplastic Agents, Hormonal↗

PubMed1998

Actinomycosis of the central nervous system: surgical treatment of three cases.

Three cases of actinomycotic brain infection are described, 2 of which manifested as cerebral abscess, the third as epidural empyema. Complete resolution of the infection was always achieved by means of surgical treatment and prolonged antibiotic therapy. The cases reported emphasize the importance of a combined approach in the treatment of this unusual cause of brain infection.

Actinomycosis↗