Grafted monolayers of the neutral Cu(ii) complex of a dioxo-2,3,2 ligand: surfaces with decreased antibacterial action

A monolayer of the neutral Cu²⁺ complex of a silane-bearing diamino–diamido ligand is formed on glass, exhibiting (decreased) antibacterial properties.

Removal Torque Values of Titanium Implants Inserted into Bone Defects Filled with Hydroxyapatite: A Histologic and Histomorphometric Analysis in Rabbit

The successful clinical use of implants with microrough titanium surfaces has paved the way for the further development of surface topographies to promote enhanced peri-implant bone apposition during the early stages of bone regeneration. The aim of this study is to determine the torque resistance of the implant-bone interface of plasma sprayed titanium endosseous implants placed in the rabbit tibia in three different situations. Hydroxyapatite (HA) particles with a size ranging from 250 to 450 microm were used in the present study to fill out 6 mm bony defects created in rabbit tibia. Fourteen mature New Zealand white male rabbits, weighing about 2.5 Kg., were used in this study. The test sites were filled with HA and the non-grafted sites were used as control. A total of 28 bone defects (14 without HA and 14 with HA.) were created. Implants with plasma-spray surface were subsequently inserted. Six additional rabbits were used; in these animals no bone defects were created. The implant sites were divided into three groups: 1) implants inserted in the tibia without bone defects; 2) implants inserted in the tibia with bone defects not filled with HA; 3) implants inserted in the tibia with bone defects filled with HA particles. The purpose of this study is to measure reverse-torque in three different situations of clinically similar implant geometry in the articulation of rabbits. The null hypothesis stated that there is a difference in reversal torque between the bone regeneration with HA, native bone and bone defect without bone regeneration. Additionally, comparison between these 6-month data and the 3-month data from a previous study led to the following conclusions: a significant difference exists in the removed torque for the TPS implants in the bone regenerated by HA and native bone; increase in removal torque values was seen for the implant inserted in bone regenerated by HA compared to the implant nated in bone without biomaterials. In conclusion, bone regenerated with biomaterials possesses different mechanical characteristics to native bone.

Intrusive luxation of primary upper incisors and sequelae on permanent successors: a clinical follow-up study

AIM

The purpose of this report is to evaluate the epidemiological aspects of intrusion that occur against upper incisors in primary dentition, to determine the statistic correlation of developmental disturbances to permanent teeth in relation to age of children at the time of trauma.

MATERIALS AND METHODS

A retrospective study was performed based on radiographic and clinical data of 34 intruded incisors in 30 patients aged between 12 and 60 months. Baseline data were collected in a questionnaire designed following the guidelines of the IADT-Italy. The descriptive statistical analysis between the different variables was performed with the Chi-squared test and the level of significance was set at 5%. The following parameters were considered: gender, age of patient at the time of injury, emergency treatment, clinical signs (vitality, mobility, spontaneous pain, colour change), presence of complications, degree of spontaneous re-eruption and possible developmental disorders to the following tooth.

RESULTS

Intrusive luxation is not statistically related to gender. During the first 6-month follow-ups, 20 incisors belonging to 12 subjects aged between 12-24 months at the time of intrusion exhibited pulpal necrosis. The highest rate of total spontaneous re-eruption occurred in incisors intruded at 12-24 months. The likelihood of spontaneous re-eruption decreased with the child's age. A significant correlation between mobility at clinical follow-up and developmental disorders in permanent teeth was found, whereas a statistical correlation between age of patient at the time of trauma and sequelae was not pointed out, even if 17 primary incisors intruded at 12-24 months did not develop an arrest of root formation.

CONCLUSION

The most traumatic intrusions in primary dentition occurs between 12 and 24 months of age, the most common cause being fall while walking. Intruded incisors with moderate mobility developed enamel hypoplasia and ectopic eruption. There was no significant correlation between age at the time of intrusion and type of subsequent developmental disturbances.

Influence of biological matrix and artificial electrospun scaffolds on proliferation, differentiation and trophic factor synthesis of rat embryonic stem cells

Two-dimensional vs three-dimensional culture conditions, such as the presence of extracellular matrix components, could deeply influence the cell fate and properties. In this paper we investigated proliferation, differentiation, survival, apoptosis, growth and neurotrophic factor synthesis of rat embryonic stem cells (RESCs) cultured in 2D and 3D conditions generated using Cultrex® Basement Membrane Extract (BME) and in poly-(L-lactic acid) (PLLA) electrospun sub-micrometric fibres. It is demonstrated that, in the absence of other instructive stimuli, growth, differentiation and paracrine activity of RESCs are directly affected by the different microenvironment provided by the scaffold. In particular, RESCs grown on an electrospun PLLA scaffolds coated or not with BME have a higher proliferation rate, higher production of bioactive nerve growth factor (NGF) and vascular endothelial growth factor (VEGF) compared to standard 2D conditions, lasting for at least 2 weeks. Due to the high mechanical flexibility of PLLA electrospun scaffolds, the PLLA/stem cell culture system offers an interesting potential for implantable neural repair devices.

Custom-made, selective laser sintering (SLS) blade implants as a non-conventional solution for the prosthetic rehabilitation of extremely atrophied posterior mandible

The treatment of severely atrophied posterior mandibles with standard-diameter root-form implants may present a challenge. Bone reconstructive surgery represents the treatment of choice; however, it may not be accepted by some patients for economic reasons or due to higher morbidity. Computer-aided design/computer-aided manufacturing (CAD/CAM) technologies have recently opened new frontiers in biomedical applications. Selective laser sintering (SLS) is a CAD/CAM technique that allows the fabrication of complex three-dimensional (3D) structures created by computer-generated image-based design techniques. The aim of this study is to present a protocol for the manufacture and clinical use of custom-made SLS titanium blade implants as a non-conventional therapeutic treatment for the prosthetic rehabilitation of extremely atrophied posterior mandibles. Computed tomography datasets of five patients were transferred to a specific reconstruction software, where a 3D projection of the atrophied mandible was obtained, and custom-made endosseous blade implants were designed. The custom-made implants were fabricated with SLS technique, placed in the extremely atrophied posterior (<4 mm width) mandible, and immediately restored with fixed partial restorations. After 2 years of loading, all implants were in function, showing a good esthetic integration. Blade implants can be fabricated on an individual basis as a custom-designed device. This non-conventional approach may represent an option for restoring the atrophied posterior mandible of elderly patients.

Maxillary sinus augmentation using computer-aided design/computer-aided manufacturing (CAD/CAM) technology

BACKGROUND

Maxillary sinus augmentation is a common method for increasing bone height for insertion of dental implants. In most cases, the graft is manually cut into a roughly appropriate shape by visual estimation during the operation; accordingly, the shape of the graft depends considerably on the experience of the surgeon. We have developed a computer-aided design/computer-aided manufacturing (CAD/CAM) technique to generate custom-made block grafts for sinus augmentation, and a customized cutting guide to precisely position the lateral wall and facilitate membrane elevation, using cone-beam computed tomography (CBCT).

METHODS

Custom-made blocks of hydroxyapatite (HA) were preoperatively cut to the required shape, based on a three-dimensional (3D) simulation, using CAD/CAM technology. The custom-made HA blocks were used for sinus augmentation.

RESULTS

Five patients underwent bilateral sinus elevation with custom-made HA blocks. Six months later, implants were placed. Two years after placement, all implants were in function. No clinical or prosthetic complications were encountered.

CONCLUSIONS

We present a CAD/CAM technique for the fabrication of custom-made block grafts for sinus augmentation.

A novel root analogue dental implant using CT scan and CAD/CAM: selective laser melting technology

Direct laser metal forming (DLMF) is a new technique which allows solids with complex geometry to be produced by annealing metal powder microparticles in a focused laser beam, according to a computer-generated three-dimensional (3D) model. For dental implants, the fabrication process involves the laser-induced fusion of titanium microparticles, in order to build, layer by layer, the desired object. Modern computed tomography (CT) acquisition and 3D image conversion, combined with the DLMF process, allows the fabrication of custom-made, root-analogue implants (RAI), perfect copies of the radicular units that need replacing. This report demonstrates the successful clinical use of a custom-made, root-analogue DLMF implant. CT images of the residual non-restorable root of a right maxillary premolar were acquired and modified with specific software into a 3D model. From this model, a custom-made, root-analogue, DLMF implant was fabricated. Immediately after tooth extraction, the root-analogue implant was placed in the extraction socket and restored with a single crown. At the 1-year follow-up examination, the custom-made implant showed almost perfect functional and aesthetic integration. The possibility of fabricating custom-made, root-analogue DLMF implants opens new interesting perspectives for immediate placement of dental implants.

Direct laser metal sintering as a new approach to fabrication of an isoelastic functionally graded material for manufacture of porous titanium dental implants

OBJECTIVES

This work focuses on a titanium alloy implants incorporating a gradient of porosity, from the inner core to the outer surface, obtained by laser sintering of metal powder. Surface appearance, microstructure, composition, mechanical properties and fractography were evaluated.

METHODS

All the specimens were prepared by a selective laser sintering procedure using a Ti-6Al-4V alloy powder with a particle size of 1-10 microm. The morphological and chemical analyses were performed by SEM and energy dispersive X-ray spectroscopy. The flexure strength was determined by a three-point bend test using a universal testing machine. The surface roughness was investigated using a confocal scanning laser microscope. The surface roughness variation was statistically evaluated by use of a Chi square test. A p value of <0.05 was considered statistically significant.

RESULTS

The original surface microstructure consisted of roughly spherical particles, diameter range 5-50 microm. After exposure to hydrofluoric acid some of these were removed and the microsphere diameter then ranged from 5.1 microm to 26.8 microm. Following an organic acid treatment, particles were replaced by grooves 14.6-152.5 microm in width and 21.4-102.4 microm depth. The metal core consisted of columnar beta grains with alpha and beta laths within the grains. The alloy was composed of 90.08% Ti, 5.67% Al and 4.25% V. The Young's modulus of the inner core material was 104+/-7.7 GPa; while that of the outer porous material was 77+/-3.5 GPa. The fracture face showed a dimpled appearance typical of ductile fracture.

SIGNIFICANCE

In conclusion, laser metal sintering proved to be an efficient means of construction of dental implants with a functionally graded material which is better adapted to the elastic properties of the bone. Such implants should minimize stress shielding effects and improve long-term performance.

A new EGFR inhibitor induces apoptosis in colon cancer cells

The use of agents targeting EGFR represents a new frontier in colon cancer therapy. Among these, mAbs and EGFR tyrosine kinase inhibitors seemed to be the most promising. However they have demonstrated scarce utility in therapy, the former being effective only at toxic doses, the latter resulting inefficient in colon cancer. This paper presents studies on a new EGFR inhibitor, FR18, a molecule containing the same naphthoquinone core as shikonin, an agent with great anti-tumor potential. In HT29, a human colon carcinoma cell line, flow cytometry, immunoprecipitation, and Western blot analysis, confocal spectral microscopy have demonstrated that FR18 is active at concentrations as low as 10 nM, inhibits EGF binding to EGFR while leaving unperturbed the receptor kinase activity. At concentration ranging from 30 nM to 5 microM, it activates apoptosis. FR18 seems therefore to have possible therapeutic applications in colon cancer.

Physical and chemical aspects of a new porous hydroxyapatite

The new engineered porous hydroxyapatite (EP-HA) described in this paper seems to be suitable as a bone substitute. Its physico-chemical characteristics and morphology are similar to those of natural bone. Study of its histological behaviour in humans revealed bone formation within and around the porous hydroxyapatite that is markedly resorbed.

Body fat distribution and flow-mediated endothelium-dependent vasodilation in older men

OBJECTIVE

Recent studies indicate that abdominal fat accumulation, in particular intra-abdominal fat, is related to impaired endothelial function in young healthy volunteers. The aim of this study was to examine whether the distribution of body fat depots is related to impaired endothelial function in older men.

METHODS

Cross-sectional sample of 38 older (68+/-1 y) sedentary (VO(2max)=2.4+/-0.1 l/min) men. Flow-mediated endothelial dependent vasodilation (EDD) was assessed in the brachial artery in response to reactive hyperemia using high-resolution ultrasound. Abdominal subcutaneous and visceral fat depots were assessed by computed tomography scan (CT-scan) at the L(4)-L(5) region in the supine position. Percentage body fat was assessed via dual-energy X-ray absorptiometry (DEXA).

RESULTS

Flow-mediated percentage change in brachial artery was 7.6+/-0.7%, suggesting an impaired flow-mediated EDD. Using simple linear regression analysis, there were no statistically significant relationship observed between flow-mediated EDD and the indices of total and abdominal adiposity (percentage body fat=29.3+/-0.9%, r=-0.11; total abdominal fat area=465+/-23 cm(2), r=-0.1; intra-abdominal fat area=200+/-14 cm(2), r=-0.14; subcutaneous fat area=265+/-13 cm(2), r=-0.05; BMI=29.3+/-0.9 kg/m(2), r=-0.07; and waist to hip ratio=0.98+/-0.01, r=-0.20).

CONCLUSION

These findings suggest that in older sedentary men there is no clear correlation between adiposity and body fat distribution and impairment of flow-mediated endothelium dependent vasodilation.

Single tooth replacement by Morse taper connection implants: a retrospective study of 80 implants

The goal of this study was to provide data relative to the use of a new implant system (Mac System, Cabon, Milan, Italy) with a Morse taper implant-abutment connection for single implant restorations. The implant system is composed of an endosseous screw made of commercially pure titanium grade 2, while the abutment is titanium alloy (Ti-6Al-4V). A total of 80 single implants were placed in 69 patients (36 women and 33 men, mean age 42 years, range 16 to 61). All patients gave their informed consent and received a thorough clinical and radiographic examination. Smokers and diabetics were excluded from the study. Three implants were placed in areas of previous tooth impaction, 5 were placed in posttraumatic edentulous areas, 2 were used in situations involving tooth agenesis, and 60 replaced teeth lost because of caries or periodontal disease. All patients were edentulous for at least 1 year prior to treatment. The implants received a definitive prosthesis and had been in function for a mean period of 3.5 years. At second-stage surgery, 2 implants were removed because of lack of osseointegration. After 2 years of loading, 1 implant showed evidence of peri-implantitis and was removed. In addition, 2 fractured abutments and 1 loosened abutment were observed. Few mechanical or infectious complications were seen, and this may have been the result of high stability of the conical connection.

Electrochemical assembling/disassembling of helicates with hysteresis

A series of eight tetradentate, ditopic, bisimino bisheterocyclic ligands (1-8), and their complexes with Cu(I) and Cu(II), have been studied in CH(3)CN solution, by means of (1)H NMR, mass, and UV/vis spectroscopy, while the crystal and molecular structure of the Cu(II) complexes [Cu(3)](CF(3)SO(3))(2) and [Cu(4)](CF(3)SO(3))(2) and of the Cu(I) complexes [Cu(2)(4)(2)](ClO(4))(2) and [Cu(2)(5)(2)](ClO(4))(2) have been determined by X-ray diffraction methods. The Cu(II) complexes are monomeric, almost square-planar structures, both in solution and in the solid state, while the Cu(I) complexes are two-metal, two-ligand dimers which can be both helical and "box-like" in the solid, while they adopt a simple helical configuration in acetonitrile solution. The systems made of ligands 1-8 and copper are bistable, as under the same conditions either the Cu(I) helical dimers or the Cu(II) monomers can be obtained and are stable. The electrochemical behavior of the 16 copper complexes has been studied in acetonitrile solutions by cyclic voltammetry. One reduction and one oxidation wave were found in all cases, which display no return wave and are separated by a 500-1000 mV interval. Irreversibility is due to the fast self-assembling process that follows the reduction of [Cu(II)(L)](2+) and to the fast disassembling process that follows the oxidation of [Cu(I)(2)(L)(2)](2+) (L = 1-8). However, the overall [oxidation+disassembling] or [reduction+self-assembling] processes, i.e., [Cu(I)(2)(L)(2)](2+) = 2[Cu(II)(L)](2+) + 2e(-), are fully reversible. Moreover, CV profiles show that solutions containing copper and L undergo hysteresis on changing the applied electrochemical potential: in the same potential interval, the systems can exist in solution as either [Cu(I)(2)(L)(2)](2+) or [Cu(II)(L)](2+), depending on the electrochemical history of the solution. Moreover, by changing the structural or donor features of the ligands it is possible to modulate the potentials at which the system undergoes a transition from one to the other of its two possible states, in the hysteresis cycle. In addition, the spectral properties of the Cu(I) and Cu(II) complexes of the considered ligands make these systems good candidates for storing information in solution, which can be electrochemically written or erased and spectroscopically read.

Molecular machines based on metal ion translocation

Transition metal ions can be moved reversibly between the two coordinatively unequivalent compartments A and B of a ditopic ligand, using as an input the variation of a bulk solution parameter, either pH or redox potential. In a redox-driven translocation, the metal moves reversibly from A to B on cycling between two consecutive oxidation states (e.g., Cu(II)/Cu(I); Fe(III)/Fe(II)) by means of auxiliary oxidation and reduction reactions. In a pH-driven process, one compartment displays also acid-base properties (AH(n)() left arrow over right arrow A(n)(-) + nH(+)), and the M(n)(+) ion is translocated between B and A(n)(-) through consecutive addition of base and acid.

M and P double helical complexes of copper(I) with bis-imino bis-quinoline enantiomerically pure chiral ligands

The enantiomerically pure bis-imino bis-quinoline ligands R,R-ImQ and S,S-ImQ have been prepared by Schiff condensation of 2-quinoline carboxyaldehyde with the pure R,R and S,S enantiomers of trans-1,2-diaminocyclohexane. Both ligands form 2:2 helical complexes with CuI perchlorate, and the crystal and molecular structure of [Cu2(R,R-ImQ)2]ClO4.H2O have been determined by X-ray diffraction methods: the [Cu2(R,R-ImQ)2]2+ molecular cation is a chiral double helix of M handedness, in which the two ligands are entertwined in such an arrangement that half of each ligand is not equivalent to the other half of the same ligand. Coupled circular dichroism and 1H NMR studies reveal that in CH3CN solution a rearrangement takes place toward a more symmetric helical structure (in which the two halves of the same ligand become equivalent), which maintains the same handedness found in the solid state and is a pure M isomer. Solid state and CH3CN solution CD experiments confirm that [Cu2(S,S-ImQ)2]ClO4.H2O, both in solution and in the solid state, is a pure double helix of P handedness, i.e., the enantiomer of the species containing the R,R ligand.

[Elevated levels of lipoprotein(a) are present in subjects with early ischemic cardiopathy and with a familial history of ischemic cardiopathy]

BACKGROUND

Elevated levels of lipoprotein(a) are associated with a greater risk of atherothrombotic cardiovascular diseases. Since the Lp(a) levels are genetically determined and fairly stable in the course of life and a family history appears to be an independent risk factor of cardiovascular diseases, we evaluated the behavior of Lp(a) levels in patients with early events of coronary heart disease (CHD) and also in subjects with positive family history of ischemic heart diseases.

METHODS

The levels of lipoprotein (a) [Lp(a)] were measured in 254 subjects, 138 males and 116 females with an average age of 48.6 +/- 13.8 years (range 20-76 years). Diabetic subjects, females submitted to oestrogen treatment and those already in treatment with hypolipidaemic drugs were excluded from the study. Forty of the 254 patients (15.7%), 27 males and 13 females, had CHD (29 a previous myocardial infarction and 11 a stable angina). A positive family history for CHD was considered present (102 of the 254 patients) if one or more first degree relatives had angina or myocardial infarction before the age of 60 years in men and 65 in women.

RESULTS

The levels of Lp(a) were higher (p < 0.01) in women (25.1 +/- 28.3 mg/dl) compared to men (17.6 +/- 18.4 mg/dl), without differences in relation to age. The Lp(a) plasmatic levels were not correlated with age, body mass index, total cholesterol, LDL and HDL, triglycerides, apo B, apo AI, fibrinogen and there were no differences in Lp(a) levels in presence or absence of other known cardiovascular risk factors such as hypertension and smoking. The Lp(a) levels were not different between subjects with CHD (28.15 +/- 31.7 mg/dl) and controls (20.3 +/- 22.8 mg/dl). The subjects with CHD were older and had higher levels of fibrinogen and a significantly greater prevalence of hypertension and family history of CHD. Fifteen of the 40 subjects with CHD had an early onset of CHD (before 50 years of age) and only in such patients the Lp(a) levels were significantly greater compared to controls (35.8 +/- 33.2 mg/dl vs 20.3 +/- 22.8 of the controls, p < 0.01), independently of other variables (age, BMI, smoking, hypertension, cholesterol, triglycerides, HDL-c, LDL-c, fibrinogen). Furthermore the Lp(a) plasmatic levels were higher in subjects with a family history of CHD (28.3 +/- 27.6 mg/dl vs 16.3 +/- 18.6 mg/dl of the subjects without a family history of CHD, p < 0.01) even if they had or not had a previous coronary ischemic event.

CONCLUSIONS

Such data confirm the importance of high levels of Lp(a) above all for the early events of CHD and for the subjects with a family history of CHD, which could be expression of a greater predisposition for cardiovascular events.

A histologic evaluation of eight cases of failed dental implants: is bone overheating the most probable cause?

Biomechanical overloading has been stated to be, overall, the major cause of implant failures. Very important can be, however, in the etiopathogenesis of early implant failure, the overheating of the surgical site. The authors present eight cases of implant loss most probably due to bone overheating, even if other causes cannot be excluded. The microscopical picture, in all cases, was composed by the same features: (1) presence of bone sequestra; (2) no regeneration of the peri-implant bone; (3) presence of an inflammatory infiltrate in the gap between bone and implant; (4) no organization of the peri-implant bone clot; (5) presence of a compact and mature bone around the implant; (6) presence of bacteria around the implant and the necrotic bone.

[Transmembrane sodium transport systems in various forms of hyperlipoproteinemia]

The possible interrelationships between the erythrocytic transport systems of Na+ (Na+/K+ pump, Na+/K+ cotransport, Na+/Li+ countertransport, Na+ passive permeability) and the plasmatic lipids (cholesterol, triglycerides, HDL, LDL, apoprotein A1, apoprotein B) were studied in 42 normotensive subjects with different forms of hyperlipoproteinaemia and with a negative familiarity for arterial hypertension. In subjects with hypercholesterolaemia (hyperlipoproteinaemia II A and II B) an elevated activity of the Na+/K+ pump was noticed, while in subjects with hypertriglyceridaemia (type IV) an increase in Na+ passive permeability and Na+/Li+ countertransport with a lower level of intraerythrocytic Na+ was shown. A negative correlation was observed between the total efflux of Na+ and Na+/K+ pump and the levels of cholesterol (r = -0.43, p < 0.04 and r = -0.41, p < 0.05) and the apoprotein B/A ratio (r = 0.42, p < 0.05 and r = -0.50, p < 0.01). A negative correlation was also noticed between the Na+/K+ pump and the levels of apoprotein B (r = -0.41, p < 0.05). The Na+/K+ cotransport appeared inversely correlated with the levels of HDL cholesterol (r = -0.42, p < 0.05), while the Na+ passive permeability was negatively correlated with the levels of LDL (r = -0.43, p < 0.04) and positively correlated with the plasmatic triglycerides (r = +0.54, p < 0.01). Such data show that the plasmatic lipids can influence the systems of transmembrane ionic transport of Na+ and play an important role also this way, in cardiovascular pathology.

Clinical and histologic aspects of biphasic calcium phosphate ceramic (BCP) used in connection with implant placement

A granulate of biphasic calcium phosphate ceramic (BCP), composed of 50% hydroxyapatite and 50% beta-tricalcium phosphate, was used, in man, to fill defects resulting from cyst enucleation. The defects were covered with e-PTFE membranes, and at the re-entry procedure after six months, it was possible to see that the defects were filled by a newly formed tissue with the macroscopic features of mature bone. Smooth titanium implants were inserted in the newly regenerated tissue. Histological examination of this tissue showed that most of the particles were lined by newly formed bone. Some particles were undergoing resorption processes and were being gradually substituted by newly formed bone. No inflammatory infiltrate was present. Our results point, in conclusion, to a good biocompatibility and osteoconductivity of this material.

[Chronic viral hepatitis due to the hepatitis C virus (HCV): treatment experience with lymphoblast interferon-alpha]

Ten patients affected with HCV-related chronic hepatitis received alpha lymphoblastoid-IFN, 3 mU i.m. TW, for 12 months. We obtained: 4 complete responses, 5 partial responses, 1 non-response (therapy stopped after 3 months). During the fourteen months follow-up, 4 patients (1 complete responder, 3 partial responders) relapsed.

Light and laser scanning microscopy analysis of hydroxyapatite used in periodontal osseous defects in man: evidence of a different resorption pattern in bone and soft tissues

Hydroxyapatite (HA) is a highly biocompatible material that recently has been shown to undergo biodegradation. The mechanisms of this phenomenon are unclear, and humoral and cellular events have been thought to be implicated. In the present study HA particles were put into infraosseous defects on teeth that were to be extracted for prosthetic reasons and then retrieved after a 1-year period. The specimens were processed with the cutting grinding system. Results show a very sharp difference of the biodegradation processes, related to the tissues that surround the HA particles. HA in tight contact with mineralized bone showed no evidence of degradation or resorption, while on the contrary, in the areas where bone loose connective tissue was present, it was possible to observe HA crystals detached and scattered in cells cytoplasm or extracellular fluids. This dissolution and resorption phenomenon were observed also by Laser Scanning Microscope (LSM) in fluorescent mode. These differences in degrees of degradation between bone and loose connective tissue could be due to the small amount of interstitial fluid present in mineralized bone and the greater flow of fluid through connective tissue.

Interface between hydroxyapatite and mandibular human bone tissue

Samples from intraosseous dental implants, removed from patients for mechanical failures, were examined to analyse the interaction between hydroxyapatite as plasma sprayed coating on titanium supports and human bone. The implantation time varied up to 8 years. No failures had arisen from problems at the interface between the hydroxyapatite coating and bone. The number of samples examined and the implantation times give good statistical conclusions. Histological and microchemical studies showed the good performance and compatibility of this sprayed hydroxyapatite. We present evidence from the best samples which show close bonding with the surrounding bone tissue. New bone is seen all around the coated implant. The composition of the calcium phosphate deposited on the hydroxyapatite and cellular approach were determined, and demonstrate the efficiency of the interaction between this plasma sprayed hydroxyapatite and the bone.

Preparation-induced stability of bioactive apatite coatings

The stability of the bioactive surface is a major concern in the chemical and physical design of apatite ceramic coatings. In clinical studies, no sintered-hydroxyapatite bulk coating material was present in the surrounding bone tissue after loading periods up to 11 years. In in vitro studies, hydroxyapatite plasma-sprayed coatings dissolved considerably, possibly because of loss of crystallinity during the plasma-spraying procedure. A heat treatment at 600 degrees C reconstituted the crystallinity and promoted the transformation of alpha-tricalcium phosphate into the more stable beta-tricalcium phosphate. Fluorapatite coatings did not lose their crystallinity and had the added advantage of stability as a result of the fluoride ion.

[Role of the cerebral CAT examination in the diagnosis of neurotoxoplasmosis]

A case of central nervous system toxoplasmosis is reported. Attention is called to the diagnosis of this infection; moreover, the authors emphasize the importance of the TAC brain for the diagnosis and evaluation of the clinical evolution and response to the therapy.

[On the subject of leptospirosis. Description of a case]

The Authors report a case of leptospirosis. Stress is laid on the sporadicity of this infection in their region; attention is also drawn to the variety of the clinical expression of this disease.

[Clinico-epidemiologic considerations in cases of acute viral non-A, non-B hepatitis (NANB)]

Personal experience with a series of 69 cases of non-A, non-B viral hepatitis out of 164 cases of acute viral hepatitis observed at hospital admission between January 1985 and June 1988 is reported. Agreement is expressed with other Italian series as regards the incidence of sex, of the most involved age classes, of the most affected professional categories and of the incubation period of posttransfusional forms. The prevalence of sporadic forms over those transmitted intraparenterally and more prolonged course in icterus patients and in parenteral forms is pointed out.

[Granular CHA in oral surgery. Clinical and therapeutic aspects]

The Authors report their experience and the clinical results obtained by the use of powders of calcium-hidroxylapatite (Dac Blu) as filling material for bone defects in many different cases. The positive biological response justifies a wider utilisation of this material in oral surgery.

Ventricle morphology in pelagic elasmobranch fishes

Ventricle weights of the warm-bodied great white shark, Atlantic shortfin mako, and the common thresher shark (the latter presumed to be warm-bodied) are similar to those of ectothermic blue sharks, sandbar sharks, dusky sharks, tiger sharks and scalloped hammerhead sharks. Ventricle muscularity, as estimated by the ratio of cortical to spongy layer thickness, is almost twice as great in the former three species than in the latter elasmobranchs. Measurements of ventricular volumes suggest that the ventricles of the great white, Atlantic shortfin mako and common thresher sharks are better adapted to respond to demands for increases in cardiac output via increased heartbeat frequency in comparison with ectothermic species of shark.

[Hypertriglyceridemia, IRI and platelet aggregation]

The Authors have studied in 13 patients with type IV hyperlipoproteinemie the behaviour of platelet aggregation and the response of IRI and blood nefa to an oral glucose load. Only two, in whom it has been possible to evidence a basal hypernefemia and a net hyperinsulinism in response to glucose oral load, showed platelet hyperaggregation to all inducers. These findings suggest that type IV hyperlipoproteinemia does not significantly influence platelet aggregation, in which IRI may have a possible role.

[Platelet aggregation in normal and hypertensive subjects during cold pressor test]

The Authors have studied, in 5 normal subjects and in 10 with essential arterial hypertension, the behaviour of platelet aggregation before, during and after cold pressor test. It has been possible to evidence, in hypertensive subjects, a greater responsiveness of platelets to adrenaline induced aggregation. The Authors think that such effects may be due to hyperexcitability of sympathetic nervous system, which can regulate the functional behaviour of platelets in response to cold pressor test.