A Solid Zn-Ion Conductor from an All-Zinc Metal-Organic Framework Replete with Mobile Zn2+ Cations

We describe the synthesis and properties of Zn3[(Zn4Cl)3(BTT)8]2 (ZnZnBTT, BTT3- = 1,3,5-benzenetristetrazolate), a heretofore unknown member of a well-known, extensive family of metal-organic frameworks (MOFs) with the general formula MII3[(MII4Cl)3(BTT)8]2, which adopts an anionic, sodalite-like structure. As with previous members in this family, ZnZnBTT presents two crystallographically distinct metal cations: a skeletal Zn2+ site, fixed within Zn4Cl(tetrazole)8 secondary building units (SBUs), and a charge-balancing Zn2+ site. Self-assembly of ZnZnBTT from its building blocks has remained elusive; instead, we show that ZnZnBTT is readily accessed by quantitative postsynthetic exchange of all Mn2+ ions in MnMnBTT with zinc. We further demonstrate that ZnZnBTT is a promising Zn-ion conductor owing to the mobile charge-balancing extra-framework Zn2+ cations. The new material displays a Zn-ion conductivity of σ = 1.15 × 10-4 S/cm at room temperature and a relatively low activation energy of Ea = 0.317 eV, enabling potential applications in the emerging field of quasi-solid-state zinc-ion batteries.

Tunable Low-Relative Humidity and High-Capacity Water Adsorption in a Bibenzotriazole Metal-Organic Framework

Materials capable of selectively adsorbing or releasing water can enable valuable applications ranging from efficient humidity and temperature control to the direct atmospheric capture of potable water. Despite recent progress in employing metal-organic frameworks (MOFs) as privileged water sorbents, developing a readily accessible, water-stable MOF platform that can be systematically modified for high water uptake at low relative humidity remains a significant challenge. We herein report the development of a tunable MOF that efficiently captures atmospheric water (up to 0.78 g water/g MOF) across a range of uptake humidity (27-45%) employing a readily accessible Zn bibenzotriazolate MOF, CFA-1 ([Zn5(OAc)4(bibta)3], H2bibta = 1H,1H'-5,5'-bibenzo[d][1,2,3]triazole), as a base for subsequent diversification. Controlling the metal identity (zinc, nickel) and coordinating nonstructural anion (acetate, chloride) via postsynthetic exchange modulates the relative humidity of uptake, facilitating the use of a single MOF scaffold for a diverse range of potential water sorption applications. We further present a fundamental theory dictating how continuous variation of the pore environment affects the relative humidity of uptake. Exchange of substituents preserves capacity for water sorption, increases hydrolytic stability (with 5.7% loss in working capacity over 450 water adsorption-desorption cycles for the nickel-chloride-rich framework), and enables continuous modulation for the relative humidity of pore condensation. This combination of stability and tunability within a synthetically accessible framework renders Ni-incorporated M5X4bibta3 promising materials for practical water sorption applications.

Nitrene transfer from a sterically confined copper nitrenoid dipyrrin complex

Despite the myriad Cu-catalyzed nitrene transfer methodologies to form new C-N bonds (e.g., amination, aziridination), the critical reaction intermediates have largely eluded direct characterization due to their inherent reactivity. Herein, we report the synthesis of dipyrrin-supported Cu nitrenoid adducts, investigate their spectroscopic features, and probe their nitrene transfer chemistry through detailed mechanistic analyses. Treatment of the dipyrrin CuI complexes with substituted organoazides affords terminally ligated organoazide adducts with minimal activation of the azide unit as evidenced by vibrational spectroscopy and single crystal X-ray diffraction. The Cu nitrenoid, with an electronic structure most consistent with a triplet nitrene adduct of CuI, is accessed following geometric rearrangement of the azide adduct from κ1-N terminal ligation to κ1-N internal ligation with subsequent expulsion of N2. For perfluorinated arylazides, stoichiometric and catalytic C-H amination and aziridination was observed. Mechanistic analysis employing substrate competition reveals an enthalpically-controlled, electrophilic nitrene transfer for primary and secondary C-H bonds. Kinetic analyses for catalytic amination using tetrahydrofuran as a model substrate reveal pseudo-first order kinetics under relevant amination conditions with a first-order dependence on both Cu and organoazide. Activation parameters determined from Eyring analysis (ΔH‡ = 9.2(2) kcal mol-1, ΔS‡ = -42(2) cal mol-1 K-1, ΔG‡298K = 21.7(2) kcal mol-1) and parallel kinetic isotope effect measurements (1.10(2)) are consistent with rate-limiting Cu nitrenoid formation, followed by a proposed stepwise hydrogen-atom abstraction and rapid radical recombination to furnish the resulting C-N bond. The proposed mechanism and experimental analysis are further corroborated by density functional theory calculations. Multiconfigurational calculations provide insight into the electronic structure of the catalytically relevant Cu nitrene intermediates. The findings presented herein will assist in the development of future methodology for Cu-mediated C-N bond forming catalysis.

Reversible O-O Bond Scission and O2 Evolution at MOF-Supported Tetramanganese Clusters

The scission of the O-O bond in O₂ during respiration and the formation of the O-O bond during photosynthesis are the engines of aerobic life. Likewise, the reduction of O₂ and the oxidation of reduced oxygen species to form O₂ are indispensable components for emerging renewable technologies, including energy storage and conversion, yet discrete molecule-like systems that promote these fundamental reactions are rare. Herein, we report a square-planar tetramanganese cluster formed by self-assembly within a metal-organic framework that reversibly reduces O₂ by four electrons, facilitating the interconversion between molecular O₂ and metal-oxo species. The tetranuclear cluster spontaneously cleaves the O-O bond of O₂ at room temperature to generate a tetramanganese-bis(μ₂-oxo) species, which, in turn, is competent for O-O bond reformation and O₂ evolution at elevated temperatures, enabled by the head-to-head orientation of two oxo species. This study demonstrates the viability of four-electron interconversion between molecular O₂ and metal-oxo species and highlights the importance of site isolation for achieving multi-electron chemistry at polynuclear metal clusters.

Conceptual and Practical Aspects of Metal-Organic Frameworks for Solid-Gas Reactions

The presence of site-isolated and well-defined metal sites has enabled the use of metal-organic frameworks (MOFs) as catalysts that can be rationally modulated. Because MOFs can be addressed and manipulated through molecular synthetic pathways, they are chemically similar to molecular catalysts. They are, nevertheless, solid-state materials and therefore can be thought of as privileged solid molecular catalysts that excel in applications involving gas-phase reactions. This contrasts with homogeneous catalysts, which are overwhelmingly used in the solution phase. Herein, we review theories dictating gas phase reactivity within porous solids and discuss key catalytic gas-solid reactions. We further treat theoretical aspects of diffusion within confined pores, the enrichment of adsorbates, the types of solvation spheres that a MOF might impart on adsorbates, definitions of acidity/basicity in the absence of solvent, the stabilization of reactive intermediates, and the generation and characterization of defect sites. The key catalytic reactions we discuss broadly include reductive reactions (olefin hydrogenation, semihydrogenation, and selective catalytic reduction), oxidative reactions (oxygenation of hydrocarbons, oxidative dehydrogenation, and carbon monoxide oxidation), and C-C bond forming reactions (olefin dimerization/polymerization, isomerization, and carbonylation reactions).

Reversible Scavenging of Dioxygen from Air by a Copper Complex

We report that exposing the dipyrrin complex (^EMindL)Cu(N₂) to air affords rapid, quantitative uptake of O₂ in either solution or the solid-state to yield (^EMindL)Cu(O₂). The air and thermal stability of (^EMindL)Cu(O₂) is unparalleled in molecular copper-dioxygen coordination chemistry, attributable to the ligand flanking groups which preclude the [Cu(O₂)]¹⁺ core from degradation. Despite the apparent stability of (^EMindL)Cu(O₂), dioxygen binding is reversible over multiple cycles with competitive solvent exchange, thermal cycling, and redox manipulations. Additionally, rapid, catalytic oxidation of 1,2-diphenylhydrazine to azoarene with the generation of hydrogen peroxide is observed, through the intermittency of an observable (^EMindL)Cu(H₂O₂) adduct. The design principles gleaned from this study can provide insight for the formation of new materials capable of reversible scavenging of O₂ from air under ambient conditions with low-coordinate Cu^I sorbents.

Additive vs. Subtractive CAD/CAM Procedures in Manufacturing of the PMMA Interim Dental Crowns. A Comparative in vitro Study of Internal Fit

CAD/CAM procedures are increasingly used to the manufacturing of 3D-designed PMMA interim dental crowns. The aim of this in vitro study was to compare the internal fit of interim PMMA crowns fabricated by subtractive versus additive CAD/CAM procedures. Starting from a Co-Cr CAD/CAM master abutment model, 20 standardized dental models of dental stone were done by double impression technique. Subsequently two groups of interim PMMA interim crowns, each of them having 10 specimens, were CAM obtained either by milling or 3D printing, using Exocad software package, milling machine Rolland DWX-50, and the 3D printer MoonRay S 100 respectively. An electronic digital caliper Powerfix Profi+ was used for measurements of the chrome cobalt abutment and crowns inner diameter in 4 directions (mesial-distal gingival, buccal-lingual gingival, mesial-distal occlusal, and buccal-lingual occlusal). The null hypothesis that the internal dimensional accuracy of interim PMMA crowns fabricated by DLP additive method would not be different compared to those obtained by milling procedure was rejected since the printed PMMA interim crowns were more accurate. This study concluded that the milled PMMA interim crowns show larger internal dimensional variations than the 3D printed ones. However, the fit variation among interim crowns fabricated by both procedures was statistically non significant, so that both CAM technologies may be equally used in manufacturing process.

P713 An incidental finding of a completely thrombosed left ventricular pseudoaneurysm: what is the next step?

Introduction

Left ventricular pseudoaneurysm is a rare complication of myocardial infarction. It is the result of ventricular rupture contained by the pericardial adhesions or thrombus. Although echocardiography is suitable as the initial method for diagnosis, multimodality imaging is often required in order to further characterize the pseudoaneurysm morphology and to plan the treatment.

Case report

A 56-year-old male patient with an old inferior myocardial infarction treated conservatively 6 years ago, was admitted in our department for atypical left laterothoracic pain. Three months before he had the same symptoms and an unexplained paracardiac mass was incidentally diagnosed by transthoracic echocardiography. At that time, he was evaluated by coronary angiography which showed no epicardial coronary artery stenosis. During admission, the ECG showed sinus rhythm, inferior myocardial scarring and right bundle branch block. The laboratory tests revealed cardiac enzymes within normal range, increased D-dimeri and elevated inflammatory markers. The echocardiography showed a nondilated left ventricle (LV) with preserved ejection fraction and akinesia of the inferolateral(IL) LV wall. Attached to the basal IL LV wall, an extensive mass was documented with an echogenic appearance and no color Doppler flow, suggesting a thrombosed pseudoaneurysm. A contrast enhanced computed tomography (CT) scan confirmed the diagnosis, but it was not able to establish whether the pseudoaneurysm was partially or completely thrombosed. For a more accurate morphologic and tissue characterization, a cardiac magnetic resonance imaging(CMR) was subsequently performed, that confirmed the presence of a completely thrombosed pseudoaneurysm, measuring 82x38mm. In this case, a conservative approach was initially suggested by the completely thrombosed chronic pseudoaneurysm (older than 3months and with no Doppler color flow). However, according to the literature a surgical approach should be considered when the pseudoaneurysm dimension is larger than 3 cm. Since the patient refused the surgical intervention, medical treatment was initiated with anticoagulants due to the high embolic risk, betablockers and angiotensin-receptor antagonists to maintain the blood pressure less than 120/80mmHg. At 1 month, his condition was stable. He will be reevaluated in 3 months, to monitor the possible pseudoaneurysm expansion. According to our knowledge, this is the first case of a completely thrombosed pseudoaneurysm described in the literature. Its echocardiographic, CT and CMR appearance is important for the differential diagnosis of all paracardiac masses (tumors, hiatus hernias, etc).

Conclusion

Completely thrombosed left ventricle pseudoaneurysm remains a challenging diagnosis since its echocardiographic appearance is atypical. Cardiac magnetic resonance imaging has a higher diagnostic yield and can provide important information that may influence the course of treatment.

Abstract P713 Figure. LV Pseudoaneurysm-multimodality imaging

Toward a Putative Paradigm Shift in Direct Pulp Capping?

Conventionally the cases accepted for direct pulp capping are the inadvertently exposed normal pulps and carious exposures in teeth without apical radiolucency. The recent advances in dental materials, namely the bioceramics, allowed successful vital therapy by direct pulp capping even in young permanent teeth with irreversible pulpitis. The choice of pulp capping material is pivotal in pulp vital therapy of carious exposures as tricalcium silicates shift the balance inflammation-healing toward the regeneration of damaged dentin-pulp complex. Anticipating a reliable outcome, the high anti-inflammatory potential and modulating capacity of cytokines and growth factors proved by bioactive endodontic cements in direct pulp capping should be associated with new molecular diagnostic tests and cautious clinical evaluation. However, it seems that a paradigm shift is expected in the decision of direct pulp capping.

Chemical Processes in Endodontic Failure Due to Incidents and Accidents

The fundamental principle that must guide the activity of each dentist is the conservative, hence the task of preserving, as much as possible, the teeth in the arches, knowing what important injury brings extractions to the individual. An essential concern of endodontic therapy is the thorny problem of infected canals. At present, it is essential for any practitioner to recognize the relationship between microbial oral and pulpal and periapical tissue, the notions of endodontic microbiology being the key to understanding the basic methods of debriding, modeling and obstructing canals. Among the pathological conditions that overrun the clinical picture of pulp sickness, not only at the local and general level, the simple or complicated pulp gangrene has a well-established role. The endodontic treatment has three basic stages: diagnosis, preparation of the channel that follows the debridement, its modeling and sterilization, and the root filling. The rationale behind the treatment of this disease is that the devital pulp does not have defense mechanisms, the endocannicular microbial flora finding under these conditions a favorable environment of development. Regardless of the degree of expertize, the accumulated experience, the responsibility and the correctness of medical care, certainly no dental practitioner has been circumvented by failures in endodontic therapy. The relatively high percentage of failures has led to countless attempts to improve the tools and materials made available to the dentist. Currently, he faces a new problem, that of choosing the most correct method of endodontic treatment. Material and Method: The structure of the study material was 240 cases taken into account, from 2012-2017. Results and Discussion:Because endodontic therapy requires very precise working techniques, it implies rigorous records, both in terms of the sequence of treatment phases, but also in relation to some technical aspects - such as - data on root canals, the chronology of the radiological examinations, the instruments and the substances used - the neglect of the correct records resulting in unnecessary time losses and traumatisations of the periodontal-apical area.Conclusions: Starting from the assumption that the radiological examination is the only objective way of initial assessment of dental morphology, the certification of the existing pathology and the establishment of a diagnosis, the orientation of the treatment plan and the verification of the correctness of the therapeutic variant chosen through a monitoring of the results over time, we sought to clarify the actual role and the actual value of the radiological examination in endodontic therapy.

Chemical Interactions among Some Antimicrobial Solutions and Chelating Agents Used in Endodontics for Irrigation of Infected Root Canals

The root canal irrigants are of utmost importance in the soft tissue dissolving, the removal of microorganisms, hard-tissue debris, and smear layer. This study sets forth to investigate the stability and synergic interactions of different systems with various combinations among antimicrobial substances and chelating agents, frequently used in endodontics for the irrigation of the infected root canals through electrochemical evaluation, physicochemical and spectrophotometric analysis. The pharmaceutical products indicated as the antiseptic solutions (sodium hypochlorite - NaOCl, chlorhexidine - CHX) and chelating agents (EDTA, citric acid - CA) have large pH variations on the entire pH domain. The physicochemical parameters� (pH, conductivity) assessment at the CHX and CA solutions shown good stability in time and also electrochemical behaviour (OCP, CV). There is a dissociation of ions in aqueous medium and a competition of the chemical balances among the structures, as an intense electrochemical activity between the functional groups through the intensification of the anodic current currents, and a shift of the potential registered. This allows the formulation that chemical interactions are not always possible among diverse types of antimicrobial solutions and chelating agents for endodontic use.

Characterization of the novel HLA-C*16:97 allele in an Italian bone marrow donor

The HLA-C*16:97 allele differs from HLA-C*16:01:01:01 at position 666 of exon 4.

Growing skull fracture in a 2 months old child

A growing skull fracture, also called posttraumatic leptomeningeal cyst, is a rare complication of skull fractures - less than 1%, usually encountered in children younger than 3 years old. Although rare, this complication must be recognized early and treated to prevent permanent neurologic deficits. We present the case of a 2 months old child who had suffered a closed head trauma in a car accident 2 weeks before he was admitted in our clinic with a left parietal growing skull fracture. He was submitted to surgery and leptomeningeal cyst was evacuated, dural defect repaired and bone fragments fixed. Child was discharged 6 days postoperative without neurologic deficits. Growing skull fractures represent a rare complication of head trauma in small children. It is imperious to be recognized and treated in early phases to prevent debilitating permanent neurologic deficits in that category of population.

Adult quality of life in congenital hydrocephalus operated cases. A twenty years retrospective study

Congenital hydrocephalus is a health problem in many countries and in Romania the pediatric neurosurgical department of the Emergency Hospital “Bagdasar-Arseni” has a large number of such patients. This is a retrospective study and it includes the patients with congenital hydrocephalus operated between 1992 and 2012 in the pediatric neurosurgical department of the Emergency Hospital “Bagdasar-Arseni”. The functional outcome was assessed using Karnofsky Performance Scale, Hydrocephalus Outcome Questionnaire and Glasgow outcome scale. The total number of the patients was 372, with a predominance of boys (212 boys versus 160 girls) and at the time of our study 168 patients were over 16 years old. Functional outcome of the children over 16 years old assessed using Karnofsky Performance Scale, showed that 73 patients were above 80 and leading independent lives, and 95 were less than 80 points. The results would be better if all these patients would benefit from schooling for children with special needs.

A new HLA allele, HLA-B*08:122, described in an unrelated donor of Caucasian origin

A new human leukocyte antigen-B allele was found in an unrelated Italian donor.

Chewing stress developed in upper anterior teeth with root end resection. a finite element analysis study

AIM

Because pulpless teeth have a higher risk of vertical root fracture, the present study investigated the additional effect of root end resection upon their mechanical resistence.

METHODS

Finite element analysis (FEA) was used to evaluate the stress and deformations of upper anterior teeth after root end resection while loading them at 100N and 300N.

RESULTS

Loading teeth with root end resection at 100N generates a mild increase of dentin stress. Even though von Misses stress is within the elastic range the whole toothbone structure is stressed while chewing. At higher load of300N the vertical and mesiodistal deformations cannot beany longer neglected. The highest stress occurs in vertical direction and involves the whole labial surface of the tooth crown. It is expressed as a compression stress (SY = 2.8 x 109N/m2) and comes close to the value of dentine Young’s modulus.

CONCLUSION

Loading the upper anterior teeth with root end resection at 100N lowers in a mild manner their mechanical resistance. A load of 300 N induces tooth deformations and a risky stress, mostly focused at tooth cervical area. The stress in the alveolar ridge bone is under the risk threshold of Young’s modulus.

Masticatory tensile developed in upper anterior teeth with chronic apical periodontitis. A finite-element analysis study

Commonly is accepted that a non-vital tooth has a higher risk of root fracture but there is a relatively little knowledge about the specific biomechanical behavior of non-vital frontal teeth with chronic apical periodontitis. The aim of our study was to evaluate the deformation and tensile generated in these teeth while vertically loading them because it is crucial to assess the moment when the absorbed occlusal forces exceed the elasticity of root dentine. Using the method of finite-element analysis, we highlighted the distribution patterns of the compressive and tension tensile, as well as their concentration areas. The vertical forces of 100 N generate deformations of no clinical risk in teeth with chronic apical periodontitis. The tensile developed in these teeth are higher than those in the vital teeth are but do not exceed the value of the elastic modulus of the radicular dentin. By increasing the force to 300 N occur elastic deformations, which cannot be neglected anymore. Even so, the 300 N forces do not generate deformations of the alveolar bone. The highest tensile at loading with 300 N was generated in vertical direction but in the cervical area of the tooth also developed tensile in lingual and mesiodistal direction that must be taken into consideration because they are near the risk limit of the elasticity modulus. The crack lines or fractures can appear both in case of excessive or even usual but accumulative occlusal forces that gradually alter the mechanical resistance of the tooth.

Identification of a novel HLA-C*08 variant allele, C*08:31. Sequence analysis from exons 1 through 8

A novel allele, HLA- C*08:31 has been identified by sequence based typing in an Italian hematological patient undergoing bone marrow transplantation.

Characterization of the novel allele HLA-Cw*0331 by sequence-based typing

A novel allele HLA-C allele, Cw*0331, has been identified by sequence based typing in a German individual selected as a potential bone marrow unrelated donor.

Control of blood-transmitted infections in dentistry

As knowledge has accumulated on the blood-transmitted pathogenic agents, the contact with biological fluids (blood, plasma, saliva, etc.) from apparently healthy individuals has started to be regarded as a real professional risk for dentists. Theoretically, exposure to a contaminated biological specimen may have as a consequence transmission of infection from patient to dentist, from dentist to patient and from patient to patient via inadequately decontaminated and sterilized dental equipment. The present study is concerned with the analysis of the specific conditions that favor the occurrence of the epidemic process, the estimation of the risk degree of transmission of infections caused by hepatitis B, C viruses as well as of HIV infection in Romania. The data for the study were collected using two processes. First a self reporting survey and secondly an experimental procedure were performed. The testing of dentists' knowledge of blood transmissible diseases and infection control in their offices were performed using a questionnaire with 129 questions. The professional incidents/accidents representing a potential risk were counted using a questionnaire (with 37 questions). Serological markers were tested with ELISA kits. The monitoring of sterilization was accomplished with a questionnaire and biological tests. Many conclusions result from the study. There is an extremely reduced probability and infection transmission from the dentist to the patient. The transmission of infection from the patient to the dentist represents a low risk (for all that, the risk should not be minimized). The rigorous control and observation of infection prevention measures in dental offices is necessary to stop the infection transmission from patient to patient. The dentists' postgraduate training in infection control measures should be completed with knowledge regarding the blood transmissible infections epidemiology. Learning more about the epidemiological process enables the dentists to avoid wrong attitudes and behaviors.

A new HLA-DRB1*11 allele, DRB1*1144, identified by cloning and sequencing

We report here the identification of a novel DRB1*11 allele, DRB1*1144, identified during sequence-based HLA-DRB1 typing. Molecular cloning and direct sequencing confirmed that the new allele is identical to DRB1*110401 at exon 2, except for a single nucleotide substitution (GTG-->GCG) changing codon 38 from Valine to Alanine.

Recipient mHag-HA1 disparity and aGVHD in thalassemic-transplanted patients

In order to determine the influence of HA-1 minor histocompatibility antigen mismatch on BMT outcome, we analyzed a pool of 94 thalassemic transplanted patients all selected for the presence of HLA-A(*)0201 allele. The HA-1 typing was performed using SSP analysis. All the patients received bone marrow from HLA-identical MLC nonresponsive siblings. As graft-versus-host-disease (GVHD) prophylaxis, all patients received cyclosporin and short methotrexate. Grades II-IV GVHD occurred in five (33.3%) of the 15 patients with recipient HA-1 disparity compared with 14 (17.7%) of the 79 patients without HA-1 disparity. Despite the higher incidence of acute graft-versus-host-disease (aGVHD) in the group of patients with HA-1 incompatibility, these data were not statistically significant. However, it was interesting to observe that no GVHD developed in any of the 15 cases in which the recipient was HA-1 negative and the donor HA-1 positive.

A novel HLA-A*02 allele, A*02202, identified by nucleotide sequencing

In this paper we report the identification of a new HLA-A*02 allele in two members of an Afghan family. This novel allele, designed as A*02202, differs from A*02201 by a silent substitution at codon 66 (AAC-->AAT) in the alpha1 domain. A*02202 appears to be the result of a novel mutation (Note).

The importance of erythroid expansion in determining the extent of apoptosis in erythroid precursors in patients with beta-thalassemia major

Beta-thalassemia major is characterized by ineffective erythropoiesis leading to severe anemia and extensive erythroid expansion. The ineffective erythropoiesis is in part due to accelerated apoptosis of the thalassemic erythroid precursors; however, the extent of apoptosis is surprisingly variable. To understand this variability as well as the fact that some patients undergoing allogeneic marrow transplantation are resistant to the myeloablative program, we attempted more quantitative analyses. Two groups of patients totaling 44 were studied, along with 25 healthy controls, and 7 patients with hemolysis and/or ineffective erythropoeisis. By 2 flow cytometric methods, thalassemic erythroid precursors underwent apoptosis at a rate that was 3 to 4 times normal. Because thalassemic marrow has between 5- to 6-fold more erythroid precursors than healthy marrow, this translated into an absolute increase in erythroid precursor apoptosis of about 15-fold above our healthy controls. In searching for the causes of the variability in thalassemic erythroid precursor apoptosis, we discovered tight direct correlations between the relative and absolute extent of apoptosis and the extent of erythroid expansion as measured either by the absolute number of marrow erythroid precursors or by serum soluble transferrin receptor levels. These results could mean that the most extreme rates of erythroid proliferation lend themselves to cellular errors that turn on apoptotic programs. Alternatively, extreme rates of erythroid hyperplasia and apoptosis might be characteristic of more severely affected patients. Lastly, extreme erythroid hyperplasia could generate such numbers of apoptotic erythroid precursors that marrow macrophages are overwhelmed, leaving more apoptotic cells in the sample.

An unusual DRB1*1503 haplotype without a detectable DRB5 locus in a black African family

A DRB1*1503 allele not associated with DRB5 locus has been detected in an African family during routine HLA typing for bone marrow transplantation. PCR/SSOP analysis showed the DR2-associated alleles in all the family members but the DRB5 locus appeared to be absent in the patient and his brother. The samples were then analyzed for the presence of DRB6 pseudogenes and we found that the unusual haplotype was associated with DRB6*0101 allele. This finding strengthen the hypothesis of a recombination hot spot between DRB1 and DRB6 genes.

[Glass ionomer cementing in stomatological practice]

Glass ionomers cements represent a cement system which develops by a reaction between a polyalchenic acid, usually a homo- or a copolymer of acrylic acid and a ion donor, usually an aluminium fluorosilicate glass. Introduction of these ionomers in the stomatological practice was determined by their remarkable adherence to dentin, by pulpal and parodontal biocompatibility, and because of the fact that they deliver continuously fluorine over a long period of time. These cements provide a good marginal sealing of the obturation. In the last years a new generation of glass ionomers cements has been introduced, that "Cormat" cements, in which the glass powder is intimately linked to a pure silver metallic powder by a synthetization process, and this provides a greatly increased resistance to abrasion, as compared to conventional glass ionomer cements. Presently glass ionomer cements have become increasingly known in the stomatological practice and they are used preferentially for base obturations, under obturations with composites on lateral teeth, in the treatment of mylolysis and for coronary erosions determined by brushing, which do not need preparation of retention cavities. They are also used for coronary reconstruction, and the treatment of atopical microcavities of occluding decay processes on the lateral teeth that have induced limited enamel losses. The perspective of these cements in the stomatological practice depends however on an improved translucency, which, for the present at least, does not match that of silicates and composites, as well as on an improved resistance to bending, and even the "Cormat" cements are inferior to silver amalgam which is used in the obturation of classical class II cavities.

[Prevalence of chronic productive cough and obstructive ventilatory dysfunction in a rural community with minimal air pollution]

Results obtained during an epidemiological investigation on chronic cough and obstructive ventilatory dysfunction in subjects without bronchopulmonary affections of known etiopathogeny, carried out in a rural environment with minimal air pollution on 282 men aged between 40 and 69 years, indicate the following: --there was a lower prevalence of chronic cough in the rural environment as compared with the urban one (12.8:21.0). The percentage of heavy smokers being approximately similar in both environments, the difference could be explained by the variable intensity of air pollution, the impact of which was exerted on the large airways (hypertrophy of the serous-mucous glands resulting in hypercrinia with dyscrinia); --similar prevalence in the two environments of the obstructive ventilatory dysfunction (11,0:8,7) suggests that this abnormality, an expression of the narrowing of the small airways, could be due to other pathogenic factors. Functional pulmonary tests with sensitivity higher than the ratio between FEV 1.0 and VC (as, for instance VEmx 50% VC) could provide higher percentages of obstructive disturbances both among chronic coughing and non-coughing subjects, revealing the latent form of the obstruction, as opposed to the manifest one as evidenced by a decrease of the FEV 1.0/VC ratio.