Long-term follow-up of patients with recessive dystrophic epidermolysis bullosa in the Netherlands: expansion of the mutation database and unusual phenotype-genotype correlations

BACKGROUND

The current classification of recessive dystrophic epidermolysis bullosa (RDEB) comprises two major subtypes: 'severe generalized RDEB' (RDEB-sev gen) with early-onset, extensive, generalized blistering and scarring, complete absence of type VII collagen, and bi-allelic COL7A1 null mutations; milder 'generalized other RDEB' (RDEB-O) with reduced-to-normal type VII collagen expression, and non-null genotypes.

OBJECTIVE

To search for previously unrecognized phenotype-genotype correlations in 33 Dutch RDEB families.

METHODS

We analyzed extensive clinical follow-up data, available for all patients up to 19 years, detailed type VII collagen immunostaining and genotypes, and correlated clinical phenotype to molecular phenotype and genotype.

RESULTS

We identified 20 novel COL7A1 mutations. In 14 of 15 RDEB-sev gen patients type VII collagen was completely absent, one had strongly reduced type VII collagen, and all carried bi-allelic null mutations. Five of 11 RDEB-O patients developed pseudosyndactyly of the fingers preceded by skin atrophy and flexion contractures later in childhood and adolescence. All five had esophageal involvement and growth retardation. Type VII collagen immunostaining ranged from strongly reduced to slightly reduced in RDEB-O patients with pseudosyndactyly, whereas RDEB-O patients without pseudosyndactyly had slightly reduced to normal type VII collagen staining. There was no difference in genotypes between both groups, although we unexpectedly found bi-allelic null mutations in two of five RDEB-O patients with pseudosyndactyly.

CONCLUSION

Pseudosyndactyly occurs in approximately half of RDEB-O patients when type VII collagen is strongly reduced. The prognosis in RDEB cannot always be simply predicted from the COL7A1 genotype.

Isomorphous substitution in bimetallic oxide clusters

The geometric and electronic structure of bimetallic oxide clusters is studied as a function of their composition with gas phase vibrational spectroscopy. Infrared multiple photon dissociation spectra of titanium-vanadium oxide cluster anions are measured in the 500 to 1200 wave number range and assigned on the basis of harmonic frequencies calculated using density functional theory. Singly substituted (V(2)O(5))(n-1)(VTiO(5))(-) (n=2-4) cluster anions are shown to form polyhedral caged structures similar to those predicted for their isoelectronic counterparts, the neutral (V(2)O(5))(n) clusters. Upon systematic exchange of V by Ti atoms in V(4-n)Ti(n)O(-)(10) (n=1-4), the structure does not change. The stress induced by the isomorphous substitution results in an increased number of unpaired electrons (n-1) for the Ti-rich systems, leading to a quartet ground state for Ti(4)O(-)(10).

Structure determination of small vanadium clusters by density-functional theory in comparison with experimental far-infrared spectra

The far-infrared vibrational spectra for charged vanadium clusters with sizes of 3-15 atoms have been measured using infrared multiple photon dissociation of Vn+Ar-->Vn(+)+Ar. Using density-functional theory calculations, we calculated the ground state energy and vibrational spectra for a large number of stable and metastable geometries of such clusters. Comparison of the calculated vibrational spectra with those obtained in the experiment allows us to deduce the cluster size specific atomic structures. In several cases, a unique atomic structure can be identified, while in other cases our calculations suggest the presence of multiple isomers.

Osteointegration of biomimetic apatite coating applied onto dense and porous metal implants in femurs of goats

Biomimetic calcium phosphate (Ca-P) coatings were applied onto dense titanium alloy (Ti6Al4V) and porous tantalum (Ta) cylinders by immersion into simulated body fluid at 37 degrees C and then at 50 degrees C for 24 h. As a result, a homogeneous bone-like carbonated apatitic (BCA) coating, 30 microm thick was deposited on the entire surface of the dense and porous implants. Noncoated and BCA-coated implants were press-fit implanted in the femoral diaphysis of 14 adult female goats. Bone contact was measured after implantation for 6, 12, and 24 weeks, and investigated by histology and backscattered electron microscopy (BSEM). After 6 weeks, bone contact of the BCA-coated Ti6Al4V implants was about 50%. After 12 and 24 weeks, bone contact was lower in comparison with the 6-week implantations at, respectively 24 and 39%. Regarding the BCA-coated porous Ta implants, bone contacts were 17, 30, and 18% after 6, 12, and 24 weeks, respectively. However, bone contact was always found significantly higher for BCA-coated dense Ti6Al4V and porous Ta cylinders than the corresponding noncoated implants. The results of this study show that the BCA coating enhances the bone integration as compared to the noncoated implants.

Slowing heavy, ground-state molecules using an alternating gradient decelerator

We have decelerated a supersonic beam of 174YbF molecules using a switched sequence of electrostatic field gradients. These molecules are 7 times heavier than any previously decelerated. An alternating gradient structure allows us to decelerate and focus the molecules in their ground state. We show that the decelerator exhibits the axial and transverse stability required to bring the molecules to rest. Our work significantly extends the range of molecules amenable to this powerful method of cooling and trapping.

Influence of octacalcium phosphate coating on osteoinductive properties of biomaterials

In this study, we investigated the influence of octacalcium phosphate (OCP) coating on osteoinductive behaviour of the biomaterials. Porous titanium alloy (Ti6Al4V), hydroxyapatite (HA), biphasic calcium phosphate (BCP) and polyethylene glyco terephtalate/polybuthylene terephtalate (PEGT-PBT) copolymer, all uncoated and coated with biomimetically produced OCP, were implanted in back muscles of 10 goats for 6 and 12 weeks. Uncoated Ti6Al4Vand HA did not show any bone formation after intramuscular implantation. All OCP coated implants, except PEGT-PBT, did induce bone in the soft tissue. The reason for the non-inductive behaviour of the copolymer is probably its softness, that makes it impossible to maintain its porous shape after implantation. Both uncoated and OCP coated BCP induced bone. However, the amount of animals in which the bone was induced was higher in the coated BCP implants in comparison to the uncoated ones. Osteoinductive potential of biomaterials is influenced by various material characteristics, such as chemical composition, crystallinity, macro- and microstructure. OCP coating has a positive effect on osteoinductivity of the biomaterials. The combination of the advantages of biomimetic coating method above traditional methods, and a good osteoinductivity of OCP coating that is produced by using this method, opens new possibilities for designing more advanced orthopaedic implants.

Genomics and proteomics in cancer

Cancer development is driven by the accumulation of DNA changes in the approximately 40000 chromosomal genes. In solid tumours, chromosomal numerical/structural aberrations are common. DNA repair defects may lead to genome-wide genetic instability, which can drive further cancer progression. The genes code the actual players in the cellular processes, the 100000-10 million proteins, which in (pre)malignant cells can also be altered in a variety of ways. Over the past decade, our knowledge of the human genome and Genomics (the study of the human genome) in (pre)malignancies has increased enormously and Proteomics (the analysis of the protein complement of the genome) has taken off as well. Both will play an increasingly important role. In this article, a short description of the essential molecular biological cell processes is given. Important genomic and proteomic research methods are described and illustrated. Applications are still limited, but the evidence so far is exciting. Will genomics replace classical diagnostic or prognostic procedures? In breast cancers, the gene expression array is stronger than classical criteria, but in endometrial hyperplasia, quantitative morphological features are more cost-effective than genetic testing. It is still too early to make strong statements, the more so because it is expected that genomics and proteomics will expand rapidly. However, it is likely that they will take a central place in the understanding, diagnosis, monitoring and treatment of (pre)cancers of many different sites.

Infrared spectra of gas-phase V(+)-(benzene) and V(+)-(benzene)(2) complexes

The organometallic ions V+-(benzene) and V+-(benzene)2 are produced by laser vaporization in a pulsed nozzle source. They are trapped and mass selected in an ion-trap/time-of-flight mass spectrometer, and their infrared spectra are measured with resonance-enhanced multiphoton photodissociation (IR-REMPD) spectroscopy with a tunable free-electron laser. Vibrational bands in the 600-1800 cm-1 region are characteristic of the benzene molecular moiety perturbed by the metal cation bonding. Experimental data are compared to the IR spectra derived from density functional calculations. Vibrational patterns in V+-(C6H6) indicate that the metal is bound in an eta6 pi-bonding configuration, while V+-(C6H6)2 is a sandwich. Trapped-ion IR-REMPD is a general method to access the vibrational spectroscopy of organometallic ions and their clusters.

Fungal genotype controls mutualism and sex in Brachypodium sylvaticum infected by epichloë sylvatica

The fungal endophyte Epichloë sylvatica (Clavicipitaceae, Ascomycota) may obligatorily infect the woodland grass Brachypodium sylvaticum, on which it can display two alternative modes of reproduction. During the sexual cycle, external stromata suppress host flowering and production of seed (choke disease), whereas in the asexual cycle the fungus remains asymptomatic and transmits vertically by seeds. Variation in the reproductive system thus determines whether the symbiosis is mutualistic or parasitic. In order to assess the relative effects of each genotype on fungal reproduction, we used naturally infected seed families of B. sylvaticum and experimentally infected plants with different combinations of plant and fungal genotypes. The results of one experiment suggested a maternal effect of the host association on the choke rate in the offspring, while the results of a second experiment clearly indicated that the fungal genotype determines stroma formation and thus the mode of reproduction. Since sexual reproduction of the fungus is closely tied with disease expression on the host, the fungal genotype may also be responsible for whether an endophyte association is beneficial or pathogenic. We discuss the results in the light of current theories about the evolution of mutualism and the maintenance of sex.