[Rehabilitation of the anterior portions of the maxilla and mandible by means of implants and bone grafts]

This article describes the possibilities and difficulties of reconstruction in the front regio by means of implants and bone transplants in five patients. First of all, planning is the most important step. Sometimes the class III relationship is a real challenge. Different bone transplants, the inlay and onlay technique, the number of the implants, the importance of the way the implants are uncovered in the second stage are discussed. In the front region, we aim for functional and esthetic reconstruction.

[Vertical augmentation of the alveolar process by distraction osteogenesis]

This article describes the treatment of a boy with Class II deep bite and hypoplasia of the alveolar process due to agenesis of the canines and premolars. At first, the occlusion has been adjusted by advancement of the mandible and opening of the bite after bilateral sagittal split osteotomy. Later, under local anaesthesia, a segmental osteotomy of the hypoplastic alveolar process has been performed. Distraction of the hypoplastic alveolar process has been achieved by orthodontic traction on the residual dentition in the segments. After sufficient augmentation of the alveolar process, 6 implants for two bridges have been placed.

[Treatment of a congenitally missing upper lateral incisor with an implant]

The presentation of a case where an agenetic lateral tooth was replaced by an oral implant, has been described. The following parameters are important: oral hygiene, the moment of implant surgery, presurgical orthodontic treatment, alternative prosthetic treatment possibilities and recall of the patient.

Tumor necrosis factor alpha induces the adenovirus early 3 promoter by activation of NF-kappaB

The early transcription unit 3 (E3) of human adenoviruses encodes proteins which appear to subvert host defense mechanisms. For example, the E3/19K protein inhibits the transport of major histocompatibility complex (MHC) class I molecules to the cell surface and thereby prevents cell lysis by cytotoxic T cells. Tumor necrosis factor alpha (TNF) stimulates expression of MHC molecules on the cell surface of normal cells but not of E3(+) cells, rather, a further reduction of MHC expression is evident. This was attributed to the increased expression of E3/19K upon TNF treatment, an effect also observed for other E3 proteins. We investigated the mechanism of the TNF-mediated up-regulation of E3 products. We show that TNF stimulates expression of a luciferase reporter gene driven by the E3 promoter. Mutation of individual transcription factor binding sites within the E3 promoter reveals the importance of the NF-kappaB binding site kappa2 for TNF inducibility. Electrophoretic mobility shift assays using antibodies directed against various members of the NF-kappaB family demonstrate that stimulation by TNF is mediated by the p50-p65 NF-kappaB complex. TNF inducibility does not depend on coexpression of E1A and can be observed during infection. Interestingly, the E3 promoter seems to be the only early promoter responsive to TNF and the only adenovirus promoter containing an NF-kappaB site. The implications of this regulatory mechanism for the adenovirus life cycle and its pathogenesis are discussed.

Hepatocyte nuclear factor 4 (HNF4) binding sites in the salmon HNF1 promoter

We report the isolation and sequencing of a 1100-bp DNA fragment containing the salmon Hepatocyte Nuclear Factor 1 gene (sHNF1) promoter. The sHNF1 promoter cloned upstream of the chloramphenicol acetyl transferase (CAT) encoding gene is shown to be active in two cell lines of hepatic origin. DNasel footprint analysis of the proximal 400 bp reveals several protein-binding sites, including a CCAAT box, a potential site for Sp1, and three potential HNF4 binding sites. The sequence does not contain any canonical TATA box or initiator and sHNF1 transcription is initiated at four different sites spanning a region of 56 bp. Sequence comparison with the Xenopus laevis HNF1 promoter sequence did not show any significant similarity except in the region overlapping two of the potential HNF4 binding sites.

Early region 3 of adenovirus type 19 (subgroup D) encodes an HLA-binding protein distinct from that of subgroups B and C

Early region 3 (E3) of human adenoviruses (Ads) codes for proteins that appear to control viral interactions with the host. For example, the most abundant E3 protein, E3/19K, inhibits the transport of newly synthesized class I major histocompatibility molecules to the cell surface, thereby interfering with antigen presentation. So far, the E3 regions of Ad subgroups A, B, C, and F have been characterized. We have cloned the E3A region of Ad type 19a (Ad19a), which belongs to the largest subgroup, D, and causes epidemic keratoconjunctivitis in humans. The sequence reveals five open reading frames (ORFs) with the potential to encode the Ad19 equivalent of pVIII, as well as proteins 12.2K, 16.2K, and 18.6K. The last ORF predicts a novel 49K protein which has no counterpart in other subgroups. Both the sequence and the overall organization of the E3 region from Ad19a shows a closer relationship to group B than to group C Ads. The 18.6K ORF represents the Ad19 homolog of the Ad2 E3/19K protein. By using 293 cells stably transfected with the Adl9a E3A region, we showed by immunoprecipitation, pulse-chase experiments, and fluorescence-activated cell sorter analysis that the Ad19 E3/19K protein binds to and prevents the transport of major histocompatibility complex molecules to the cell surface. The similar but distinct functional activity of the Ad19 E3/19K protein, combined with the new sequence which differs from those of subgroup B and C proteins, allows a more precise definition of amino acids essential for HLA binding.

Structural organization and sequence analysis of the globin locus in Atlantic salmon

Preliminary analysis of Atlantic salmon alpha- and beta-globin genes indicated that these genes are linked in a 3' to 3' orientation, with the RNA-coding sequences located on opposite strands. In this report, we show that two different alpha-globin genes have the same orientation and are encoded on the same strand whereas two different beta-globin genes are encoded on the opposite strand and also have the same orientation. This cluster of globin genes is divided into two subclusters: one for the Bohr globin genes and one for the non-Bohr globin genes. This is the first evidence for this type of arrangement found for globin genes. DNase I footprint analysis of two of the globin promoters show erythroid-specific transcription factor binding sites that have also been found in human and other mammalian globin genes.

Tumor necrosis factor alpha increases expression of adenovirus E3 proteins

Human adenovirus can cause persistent infections in man. Implicated in this phenomenon is the early transcription unit 3 (E3) of the virus which encodes proteins that are primarily devoted to counteract the lytic attack by the host immune system: Several E3 proteins (14.7K, 10.4K and 14.5K) protect infected cells from the lytic activity of tumor necrosis factor alpha (TNF) while the most abundant E3 protein, E3/19K, inhibits lysis by cytotoxic T cells. E3/19K interacts with class I histocompatibility (MHC) antigens in the rough endoplasmic reticulum, thereby preventing transport of MHC molecules to the cell surface and, consequently, MHC-restricted T cell recognition. In addition, the 10.4K and 14.5K proteins downregulate cell surface expression of the epidermal growth factor receptor. Interestingly, adenovirus-mediated pneumonia in mice is accompanied by induction of TNF, a cytokine known to enhance MHC expression. We previously showed that TNF is unable to restore MHC class I expression in E3/19K transfected cells but rather leads to a further reduction of MHC antigens. This effect correlated with an increased production of E3/19K mRNA and protein. We now find in addition an upregulation of other E3 proteins in transfected as well as in infected cells. This coordinated upregulation of E3 proteins indicates that TNF stimulates the E3 promoter, probably by activating the transcription factor NF-kappa B. Thus, a novel interaction between the immune system and adenovirus is described in which the virus takes advantage of an immune mediator to promote expression of several immunosubversive proteins supporting its escape from immunosurveillance.

Presence of an extended duplication in the putative low-density-lipoprotein receptor-binding domain of apolipoprotein B. Cloning and characterization of the domain in salmon

The sequence of the C-terminal 1058 amino acids of atlantic salmon (Salmo salar) apolipoprotein (apo) B was deduced from the nucleotide sequence of cloned cDNA. In comparison with chicken or mammals apoB-100, salmon apoB is C-terminally truncated and extended gaps are found. The two clusters of positively charged residues, previously identified as part of the putative low-density-lipoprotein (LDL) receptor-binding domain of apoB, are brought into close proximity in salmon apoB. This is achieved by the absence between the two clusters of the proline-rich area with the potential to form an amphipathic beta sheet, present in higher vertebrates. In addition, analysis of apoB amino acid sequences currently available in vertebrates revealed the presence of an extended internal duplication in the putative LDL receptor-binding domain. Thus, the two basic clusters would have been duplicated resulting in the presence, except for salmon apoB, of two homologous sites in the C-terminal part of the molecule. The results described here together with earlier biochemical and genetic evidence support the view that Arg3500, a residue mutated in familial defective apoB-100, could be included in a folded critical region of the putative LDL receptor-binding domain of human apoB-100. This region possibly brings the two sub-domains that arise from the duplication close to each other.

Salmon HNF1: cDNA sequence, evolution, tissue specificity and binding to the salmon serum albumin promoter

cDNA clones coding for the transcription factor HNF1 have been isolated from Atlantic salmon (Salmo salar L.). The 559 amino acid residue long encoded protein shows high conservation, with respect to other species, of the domains necessary for DNA-binding: the HNF1 atypical homeodomain, the POU related sequence and the dimerisation domain. Alignment with rat HNF1 protein reveals that the transcription activation domains ADI and ADIII are relatively conserved in the fish sequence whereas ADII is not. Phylogenetic analysis indicates that higher vertebrate HNF1s and the related variant HNF1s (vHNF1s) are more closely related to each other than any of them is to Salmon HNF1, suggesting that the duplication event from which HNF1 and vHNF1 genes arose occurred after the divergence of the tetrapod and teleost ancestors. Northern blot analysis show a single transcript, of about 2.6 kb, which is not exclusive to liver but is also present in intestine, kidney and spleen. Using polymerase chain reaction (PCR) we have isolated the salmon albumin gene promoter which contains, upstream of the TATA box, a potential binding site for HNF1. The salmon HNF1 protein synthesized by in vitro transcription-translation of the full-length cDNA is able to bind specifically with equivalent affinities to either the rat or salmon albumin promoter.

Reconstruction of the extremely atrophic maxilla with onlay- and inlay bone graft techniques in combination with implants

The authors give a review of the literature on the different onlay and inlay bone graft techniques in reconstruction of the extremely resorbed maxilla. Own experiences and results of onlay and inlay bone grafting in combination with implants are described. A treatment protocol used since September 1989 and the outcome of 198 implants placed in combination with different reconstruction techniques are presented.

Tail-to-tail orientation of the Atlantic salmon alpha- and beta-globin genes

We report the cloning of a cDNA and two corresponding beta-globin genes of the Atlantic salmon (Salmo salar L.) as well as two genes for alpha-globins. Nucleotide sequence analysis of the cDNA shows that the predicted beta-globin peptide comprises 148 amino acids with a calculated molecular mass of 16,127 Da and an overall amino acid similarity of 40-50% to higher vertebrates and 60-90% to fish sequences. The study of the genomic organization of alpha- and beta-globin genes shows that, as is the case in Xenopus, the salmon genes are adjacent. Two sets of linked alpha- and beta-globin genes were isolated and restriction-enzyme polymorphisms indicate that they belong to two distinct loci, possibly as a result of the salmon tetraploidy. In each locus the alpha- and beta-globin genes are oriented 3' to 3' relative to each other with the RNA coding sequences located on opposite DNA strands. This is the first evidence for this type of arrangement found for globin genes. Moreover, while the linkage found in salmon and Xenopus supports the hypothesis of an initial tandem duplication of a globin ancestor gene, our results raise the question of the actual original orientation of the duplicated genes.

Denta Scan: CT software program used in the anatomic evaluation of the mandible and maxilla in the perspective of endosseous implant surgery

A radiological technique, using a new CT software program for the evaluation of alveolar process height and width, is presented. Irradiation is kept within acceptable limits when this technique is used. Measurements obtained with this technique were compared with those obtained on panoramic radiographs in 40 "half-jaws" (21 maxillar and 19 mandibular). We found that new indications for implantation emerge in the mandibular region because 'Denta Scan' can sometimes show possibilities to place implants on the buccal side of the canal (2 of 19 mandibular cases) when no possibilities are present above the canal on both the panoramic radiographs and Denta Scan images. In the maxillar region Denta Scan avoids unnecessary interventions by demonstrating the insufficient width of the alveolar ridge, often missed on panoramic radiographs (4 of 21 maxillar cases). Moreover the use of Denta Scan allows the use of implants with optimal length and diameter (23 of the 40 cases), giving better long-term results.

Role of the oocyte nucleus in determination of the dorsoventral polarity of Drosophila as revealed by molecular analysis of the K10 gene

In Drosophila, the establishment of dorsoventral polarity of the developing embryo depends on the expression of at least 11 maternally acting genes. Mutant females that lack any of these gene activities produce normally shaped eggs that develop into dorsalized embryos. The female sterile K10 mutation differs from these mutants, because in addition to the dorsalized development of the embryo, it causes a dorsalization of the egg shape. During oogenesis, the K10 gene is specifically expressed in the oocyte. Antibodies raised against a beta-galactosidase-K10 fusion protein were used to visualize the K10 product in ovaries by indirect immunofluorescence. The protein, which contains a putative DNA recognition helix, accumulates in the nucleus of the oocyte, where it is assumed to have a regulatory function. Our results thus indicate that the controlled expression of some of the genes of the oocyte nucleus is essential for the determination of the dorsoventral polarity of the oocyte and possibility of the developing embryo.