Polymerization stress, flow and dentine bond strength of two resin-based root canal sealers.

AIM: To compare two resin-based root canal sealers (AH Plus and dual cure Epiphany) in terms of flow, polymerization stress and bond strength to dentine. METHODOLOGY: Flow was evaluated by measuring the diameter of uncured discs of sealer (0.5 mL) after 7 min compression (20N) between two glass plates (n = 5). Polymerization stress was monitored for 60 min in 1-mm thick discs bonded to two glass rods (Ø = 5 mm) attached to a universal testing machine (n = 3). Bond strength was analyzed through micropush-out test (n = 10) and failure mode was examined with scanning electron microscope (100x and 2500x). Data were statistically analyzed using the Student's t-test (alpha = 0.05). RESULTS: Polymerization stress was 0.32 +/- 0.07 MPa for Epiphany self-cure, 0.65 +/- 0.08 MPa for Epiphany light-cure and zero for AH Plus (P < 0.05). Flow data and bond strength values were 30.9 +/- 1.1, 28.6 +/- 0.7 mm and 6.3 +/- 5.3, 17.8 +/- 7.5 MPa for Epiphany and AH Plus, respectively (P < 0.001). Failure mode was predominantly cohesive in the sealer for both materials. CONCLUSIONS: Epiphany had higher flow and polymerization stress and lower bond strength values to dentine than AH Plus. In view of these findings it can be implied that AH Plus would provide a better seal.

Duplications in addition to terminal deletions are present in a proportion of ring chromosomes: clues to the mechanisms of formation.

BACKGROUND AND METHODS: Ring chromosomes are often associated with abnormal phenotypes because of loss of genomic material at one or both ends. In some cases no deletion has been detected and the abnormal phenotype has been attributed to mitotic ring instability. We investigated 33 different ring chromosomes in patients with phenotypic abnormalities by array based comparative genomic hybridisation (CGH) and fluorescence in situ hybridisation (FISH). RESULTS: In seven cases we found not only the expected terminal deletion but also a contiguous duplication. FISH analysis in some of these cases demonstrated that the duplication was inverted. Thus these ring chromosomes derived through a classical inv dup del rearrangement consisting of a deletion and an inverted duplication. DISCUSSION: Inv dup del rearrangements have been reported for several chromosomes, but hardly ever in ring chromosomes. Our findings highlight a new mechanism for the formation of some ring chromosomes and show that inv dup del rearrangements may be stabilised not only through telomere healing and telomere capture but also through circularisation. This type of mechanism must be kept in mind when evaluating possible genotype-phenotype correlations in ring chromosomes since in these cases: (1) the deletion may be larger or smaller than first estimated based on the size of the ring, with a different impact on the phenotype; and (2) the associated duplication will in general cause further phenotypic anomalies and might confuse the genotype-phenotype correlation. Moreover, these findings explain some phenotypic peculiarities which previously were attributed to a wide phenotypic variation or hidden mosaicism related to the instability of the ring.

CNGA3 mutations in hereditary cone photoreceptor disorders.

We recently showed that mutations in the CNGA3 gene encoding the alpha-subunit of the cone photoreceptor cGMP-gated channel cause autosomal recessive complete achromatopsia linked to chromosome 2q11. We now report the results of a first comprehensive screening for CNGA3 mutations in a cohort of 258 additional independent families with hereditary cone photoreceptor disorders. CNGA3 mutations were detected not only in patients with the complete form of achromatopsia but also in incomplete achromats with residual cone photoreceptor function and (rarely) in patients with evidence for severe progressive cone dystrophy. In total, mutations were identified in 53 independent families comprising 38 new CNGA3 mutations, in addition to the 8 mutations reported elsewhere. Apparently, both mutant alleles were identified in 47 families, including 16 families with presumed homozygous mutations and 31 families with two heterozygous mutations. Single heterozygous mutations were identified in six additional families. The majority of all known CNGA3 mutations (39/46) are amino acid substitutions compared with only four stop-codon mutations, two 1-bp insertions and one 3-bp in-frame deletion. The missense mutations mostly affect amino acids conserved among the members of the cyclic nucleotide gated (CNG) channel family and cluster at the cytoplasmic face of transmembrane domains (TM) S1 and S2, in TM S4, and in the cGMP-binding domain. Several mutations were identified recurrently (e.g., R277C, R283W, R436W, and F547L). These four mutations account for 41.8% of all detected mutant CNGA3 alleles. Haplotype analysis suggests that the R436W and F547L mutant alleles have multiple origins, whereas we found evidence that the R283W alleles, which are particularly frequent among patients from Scandinavia and northern Italy, have a common origin.

Parkin deletions in a family with adult-onset, tremor-dominant parkinsonism: expanding the phenotype.

A gene for autosomal recessive parkinsonism, PARK2 (parkin), has recently been identified on chromosome 6q and shown to be mutated in Japanese and European families, mostly with early-onset parkinsonism. Here we present a large pedigree from South Tyrol (a region of northern Italy) with adult-onset, clinically typical tremor-dominant parkinsonism of apparently autosomal dominant inheritance. Haplotype analysis excluded linkage to the chromosome 2p, 4p, and 4q regions that harbor genes associated with autosomal dominant parkinsonism, but implicated the parkin locus on chromosome 6q. Compound heterozygous deletions in the parkin gene (one large and one truncating) were identified in 4 affected male siblings. The patients were clinically indistinguishable from most patients with idiopathic Parkinson's disease. None of them displayed any of the clinical hallmarks described in patients with previously reported parkin mutations, including diurnal fluctuations, benefit from sleep, foot dystonia, hyperreflexia, and early susceptibility to levodopa-induced dyskinesias. Two affected female individuals carried one (truncating) of the two deletions in a heterozygous state with an apparently normal allele. We conclude that the phenotypic spectrum associated with mutations in the parkin gene is broader than previously reported, suggesting that this gene may be important in the etiology of the more frequent late-onset typical Parkinson's disease.

Parental origin and mechanisms of formation of cytogenetically recognisable de novo direct and inverted duplications.

Cytogenetic, FISH, and molecular results of 20 cases with de novo tandem duplications of 18 different autosomal chromosome segments are reported. There were 12 cases with direct duplications, three cases with inverted duplications, and five in whom determination of direction was not possible. In seven cases a rearrangement between non-sister chromatids (N-SCR) was found, whereas in the remaining 13 cases sister chromatids (SCR) were involved. Paternal and maternal origin (7:7) was found almost equally in cases with SCR (3:4) and N-SCR (4:3). In the cases with proven inversion, there was maternal and paternal origin in one case each. Twenty three out of 43 cytogenetically determined breakpoints correlated with common or rare fragile sites. In five cases, including all those with proven inverse orientation, all breakpoints corresponded to common or rare fragile sites. In at least two cases, one with an interstitial duplication (dup(19)(q11q13)) and one with a terminal duplication (dup(8) (p10p23)), concomitant deletions (del(8) (p23p23.3) and del(19)(q13q13)) were found.

Terminal deletion, del(1)(p36.3), detected through screening for terminal deletions in patients with unclassified malformation syndromes.

We report on a 4 year-old girl with a 1p36.3-pter deletion. Clinical findings included minor anomalies of face and distal limbs, patent ductus arteriosus, the Ebstein heart anomaly, and brain atrophy with seizures. Conventional GTG-banded chromosome analysis revealed a normal (46,XX) result. Subsequent analysis by fluorescent in situ hybridization (FISH) using distal probes demonstrated a deletion of 1p36.6-pter. Molecular investigations with microsatellite markers showed hemizygosity at three loci at 1p36.3 with loss of the paternal allele. The deletion of 1p36.3 is difficult to identify by banding alone; indeed, our patient represents the third reported case with a del(1)(p36.3) that was detected only after more detailed analysis. In all three cases the deletion was detected through screening of patients with multiple congenital anomalies/mental retardation syndromes suggestive of autosomal chromosome aberrations for subtelomeric submicroscopic deletions by means of FISH or microsatellite marker analysis. On the basis of these observations we highly recommend that FISH with a subtelomeric 1p probe be routinely performed in patients with similar facial phenotype, severe mental retardation and seizures, and a heart malformation, particularly the Ebstein anomaly.

Rapid immunoblot and kinase assay tests for a syndromal form of X linked mental retardation: Coffin-Lowry syndrome.

Coffin-Lowry syndrome (CLS) is a syndromal form of X linked mental retardation, in which some associated facial, hand, and skeletal abnormalities are diagnostic features. Accurate diagnosis, critical for genetic counselling, is often difficult, especially in early childhood. We have recently shown that Coffin-Lowry syndrome is caused by mutations in the gene encoding RSK2, a growth factor regulated protein kinase. RSK2 mutations are very heterogeneous and most of them lead to premature termination of translation or to loss of phosphotransferase activity or both. In the present study, we have evaluated immunoblot and RSK2 kinase assays as a rapid and simple diagnostic test for CLS, using cultured lymphoblastoid or fibroblast cell lines. Western blot analysis failed to detect RSK2 in six patients, suggesting the presence of truncated proteins in these patients. This conclusion was confirmed in four patients, in whom the causative mutations, all leading to premature termination of translation, were identified. Of four patients showing a normal amount of RSK2 protein on western blot and tested for RSK2 phosphotransferase activity, one had a dramatically impaired activity. Analysis of the RSK2 cDNA sequence in this patient showed a mutation of a putative phosphorylation site that would be critical for RSK2 activity. Preliminary results show that, at least, the western blot protocol can be successfully applied to lymphocyte protein extracts prepared directly from blood samples. These assays promise to become important diagnostic tools for CLS, particularly with regard to very young patients with no family history of the condition.

Clinical and genetic evaluation of a family with a mixed dystonia phenotype from South Tyrol.

The gene causing early-onset torsion dystonia (DYT1) has recently been identified, and two new dystonia genes, one for adult-onset focal dystonia (DYT7) and one for a mixed dystonia phenotype (DYT6), have been mapped. We evaluated clinically a family from South Tyrol (Northern Italy) with 6 definitely affected individuals who display an unusually large phenotypic range of dystonic symptoms. We excluded the GAG deletion in the DYT1 gene and linkage to any of the above-mentioned dystonia loci, thus suggesting an as yet undefined dystonia gene in our family.

Isochromosome 18p results from maternal meiosis II nondisjunction.

Microsatellite analysis with 13 microsatellites spread over 18p was performed to determine the origin of the marker chromosome in 9 patients with additional metacentric marker chromosomes. Phenotypes and banding patterns suggested that the markers were isochromosomes 18p. Maternal origin was determined in all 8 cases where both parents were available for study. Six cases showed 3 alleles (one paternal, one maternal each in single and double dose) of informative markers located close to the telomere while markers close to the centromere on 18p were reduced to homozygosity (one paternal allele in single dosage and one maternal allele presumably in triple dosage). A similar result was obtained in the patient with no parents available for examination. The other 2 patients were uninformative for maternal hetero- versus homozygosity, but at some loci the maternal band was clearly stronger than the paternal one whereas the opposite was never observed. Trisomy 18 differs from trisomy 21, XXX and XXY of maternal origin through a preponderance of meiosis II versus meiosis I nondisjunction. Thus, the results of our study and the advanced mean maternal age at delivery of patients with additional i(18p) indicate that in most if not all cases the marker chromosome originates from maternal meiosis II nondisjunction immediately followed by isochromosome formation in one of the 2 maternal chromosomes 18. Possible explanations of these results include a maternally imprinted gene on 18q with a lethal effect if the paternal homologue is lost and a mechanism through which nondisjunction in some cases could be connected with isochromosome formation.

Trisomy 2p: analysis of unusual phenotypic findings.

We present three probands with partial trisomies 2p21-23 due to ins(4;2)(q21;p21p23) pat, 2p23-pter due to t(2;4)(p23;q35)mat, and 2p21-pter due to t(2;11)(p21;q23.3)mat. More than 50 cases of partial trisomy 2p have been reviewed and some abnormalities, unusual for most other types of structural autosomal imbalance, have been found in patients with inherited forms of 2p trisomy and in their non-karyotyped sibs. Neural tube defects (anencephaly, occipital encephalocele, and spina bifida) were found in five probands and 4/6 affected non-karyotyped sibs. The only triplicated segment common to all was 2p24. Different forms of "broncho-pulmonary a/hypoplasia" (including two cases of lung agenesis) were described in four patients (overlapping triplicated segment was 2p21-p25). Three patients (with overlapping triplicated segment 2p23-p25) had diaphragmatic hernia. Abnormal rotation of the heart or L-transposition of large vessels (with or without visceral heterotaxia) was found in two infants (overlapping triplicated segment 2p23-p24). In two patients with common triplicated segment 2p22.3-p25, neuroblastoma has been described. The occurrence of all these defects may be explained either by the action of the same gene(s) mapped to 2p24 or by action of some independent factors located in different segments of the short arm. Although the latter hypothesis is much less probable, it can not be rejected at the present time. We propose the existence of a genetic system controlling surveillance of an abnormal embryo to explain the phenotypic differences between patients with the same imbalance within a family. In some "restrictive" combinations the abnormal embryos will die, although in "permissive" combinations they can survive.

Bone mineral density in children and adolescent females treated with high doses of L-thyroxine.

Single-photon absorptiometry was used to assess forearm bone mineral content (BMC) at a proximal site (PBMC) and at a more distal site (DBMC) of the non-dominant distal forearm in 20 children and adolescent females taking high doses of L-thyroxine (120 micrograms/m2/day) for a period of 6-96 months for endemic goiter, Hashimoto's thyroiditis or thyroid cancer. PBMC was significantly reduced compared to controls (p < 0.002). No correlation was found between PBMC, the values of circulating thyroid hormones and the indices of tissue hyperthyroidism such as TSH and systolic time intervals (STI), suggesting that bone is a very sensitive target for thyroid hormones. Further studies are necessary to confirm our findings and to verify their clinical significance. At present, we believe that suppressive doses of L-thyroxine should be reserved for cancer patients only.

[Bone density in swimmers]. / Densità ossea nei nuotatori.

Bone mineral density of the non-dominant forearm was measured by single-photon absorptiometry at a proximal site (PBMD) and at a more distal site (DBMC) in 9 competitive male swimmers, aged 18 to 23 years, who had been training for 12 +/- 2 years, 10.3 +/- 5.6 hours a week. The results were compared with 25 age-matched controls. PBMD was m +/- SD 0.57 +/- 0.02 g/cm2 in the swimmers and 0.57 +/- 0.05 g/cm2 in the controls. DBMD was 0.45 +/- 0.02 g/cm2 in the swimmers and 0.45 +/- 0.03 g/cm2 in the controls. No difference was found between the two groups. We can therefore conclude that swimming, in absence of gravity, didn't provide our athletes with an effective mechanical load capable to increase bone density of the forearm.

[Monitoring the treatment of precocious puberty with a GnRH-analog (buserelin): comparison of the GnRH-test with nocturnal pulsatility of LH, testosterone and 17-beta-estradiol]. / Monitoraggio della terapia per la pubertà precoce con un analogo del GnRH (Buserelin): confronto fra il GnRH-test e la pulsatilità notturna di LH, testosterone e 17 beta-estradiolo.

We studied in 10 children (3 boys and 7 girls), affected by precocious puberty and treated for a period of more than 6 months with the GnRH-analog Buserelin, the efficacy of the GnRH test versus the study of spontaneous nocturnal secretion of LH, testosterone and 17 beta-estradiol as a means of testing the gonadotropin suppression. All the subjects have shown a total suppression of LH during the GnRH test as well as a nocturnal profile of LH, testosterone and 17 beta-estradiol of a prepubertal pattern. Clinically all the patients were treated successfully. Considering the effectiveness of both investigations, we conclude that the GnRH test combined with clinical observation is a single and valid means of testing the pharmacological treatment for precocious puberty.

Qualidade das informaçöes das declaraçöes de óbitos em um hospital geral de Porto Alegre / Quality of the informations of the death certificates in a general hospital of Porto Alegre

Revisaram-se as mortes ocorridas no Hospital Säo Lucas da PUCRS no primeiro trimestre de 1989, comparando-se as informaçöes contidas nos prontuários médicos com as obtidas nos atestados de óbito. Somente 29 (31,18 por cento) das declaraçöes de óbitos estudadas näo apresentaram erros em seu preenchimento nos itens considerados essenciais. Em 32 (34,45 por cento) atestados, foi modificada a causa básica do óbito. Discute-se a importância do treinamento continuado de médicos e estudantes de medicina para que se obtenha estatísticas confiáveis em saúde pública.