Intracellular Abeta is increased by okadaic acid exposure in transfected neuronal and non-neuronal cell lines.

Intracellular Abeta was examined in both a neuronal cell line (B103) expressing human APP with Swedish mutation and a non-neuronal cell line (Chinese hamster ovary, CHO) expressing wild human APP. Exposure of the APP695sw-transfected B103 cells to okadaic acid for 3 h, Abeta immunostaining was enhanced, as demonstrated by two independent anti-Abeta antibodies. The confocal microscopic study revealed that the immunoreactivity of Abeta was mainly colocalized with a Golgi marker and partially with an ER marker. Quantitative analyses, using Abeta sandwich ELISA, showed significantly increased intracellular Abeta. False positive detection of Abeta by antibody cross-reaction with APP was ruled out by extracting the fraction with formic acid and making it alkaline before subjecting it to ELISA. This procedure resulted in a fraction that contained little APP. Using CHO cells, OA treatment was also shown to be effective in increasing Abeta, as demonstrated by Western blot. The increased full-length APP and decreased APPC99 were also observed. This is the first study to demonstrate that OA treatment significantly increases intracellular Abeta.     

High frequency of altered HLA class I phenotypes in invasive breast carcinomas

We studied 105 tumor samples obtained from patients diagnosed as having breast carcinomas for HLA class I and II (DR) antigen expression, using a panel of mAbs defining HLA-monomorphic, locus-specific and allele-specific determinants. Peripheral blood lymphocytes from patients were also typed for HLA alleles. The results indicated total HLA class I losses in 55 patients (52.3%), HLA-A locus losses in four patients (3.8%), HLA-B locus losses in eight patients (7.6%), and A, B, locus losses in 10 patients (9.5%). The remaining 28 patients whose tissues reacted positively with monomorphic- and locus-specific mAbs were tested for HLA allelic losses using several anti-HLA mAbs defining A2, A3, A9, B8, B12, etc. Of these 28 patients, 16 (57%) showed one or more losses of HLA reactivity. These results indicated that in 88.5% of patients we detected a particular HLA-altered tumor phenotype. The downregulation of HLA class I antigens in breast carcinomas may thus be more frequent than previously reported, and patients without HLA class I downregulation may be the exception rather than the rule. It cannot be ruled out that HLA alterations are present in some of the 12 patients with an apparently normal HLA phenotype, as some HLA alleles could not be studied because of the lack of appropriate mAbs. These HLA alterations could represent an important step associated with tumor invasion, conferring to the tumor cells the ability to escape from T-lymphocyte recognition.     

Siberian hamster: a new indoor source of allergic sensitization and respiratory disease

BACKGROUND: The identification of 'unknown' allergic sensitizations may determine the prognosis and treatment of patients with respiratory airway disease. Currently, the presence in homes of 'exotic' animals as pets is increasing. In this article the Siberian hamster or dwarf hamster (Phodopus sungorus) was identified as a new indoor source of aeroallergens and respiratory disease. METHODS: The subjects were six outpatients who were treated for asthma and rhinitis. Siberian hamster hair extract was prepared with a standard wt/vol method, and patients were skin-prick tested with the extract. Serum-specific immunoglobulin (Ig)E against the Siberian hamster, common hamster (Cricetus cricetus) and golden hamster (Mesocricetus auratus) was determined. IgE-immunoblotting was also performed for all six sera. Specific bronchial challenge was carried out with the Siberian hamster extract. RESULTS: Skin prick tests (SPT) with the Siberian hamster extract, and specific IgE-antibodies against Siberian hamster, were strongly positive in all six patients. Determinations of specific IgE-antibodies against C. cricetus and M. auratus were negative in all patients. IgE-immunoblotting of the sera revealed two IgE-binding fractions (MW 18 and 32 kDa) in five of the six sera. Specific bronchial provocation tests resulted in early asthmatic responses in the two patients who were challenged. CONCLUSIONS: The present study reveals the Siberian hamster to be able to induce both sensitization and disease, and this species of hamster should be taken into consideration as a cause of respiratory disease in exposed subjects. A noteworthy finding was the lack of sensitization in our patients to common hamster allergens (M. auratus and C. cricetus) that are usually tested when hamster allergy is suspected.     

The role of cartilage canals in endochondral and perichondral bone formation: are there similarities between these two processes?

We investigated the development of cartilage canals to clarify their function in the process of bone formation. Cartilage canals are tubes containing vessels that are found in the hyaline cartilage prior to the formation of a secondary ossification centre (SOC). Their exact role is still controversial and it is unclear whether they contribute to endochondral bone formation when an SOC appears. We examined the cartilage canals of the chicken femur in different developmental stages (E20, D2, 5, 7, 8, 10 and 13). To obtain a detailed picture of the cellular and molecular events within and around the canals the femur was investigated by means of three-dimensional reconstruction, light microscopy, electron microscopy, histochemistry and immunohistochemistry [vascular endothelial growth factor (VEGF), type I and II collagen]. An SOC was visible for the first time on the last embryonic day (E20). Cartilage canals were an extension of the vascularized perichondrium and its mesenchymal stem cell layers into the hyaline cartilage. The canals formed a complex network within the epiphysis and some of them penetrated into the SOC were they ended blind. The growth of the canals into the SOC was promoted by VEGF. As the development progressed the SOC increased in size and adjacent canals were incorporated into it. The canals contained chondroclasts, which opened the lacunae of hypertrophic chondrocytes, and this was followed by invasion of mesenchymal cells into the empty lacunae and formation of an osteoid layer. In older stages this layer mineralized and increased in thickness by addition of further cells. Outside the SOC cartilage canals are surrounded by osteoid, which is formed by the process of perichondral bone formation. We conclude that cartilage canals contribute to both perichondral and endochondral bone formation and that osteoblasts have the same origin in both processes.     

Novel osteoblast-adhesive peptides for dental/orthopedic biomaterials

Next generation dental/orthopedic biomaterials must be designed to enhance and support osteoblast adhesion. The osteoblasts use different ways to adhere, that is, integrin- and proteoglycan-mediated mechanisms. The present study reports on the synthesis and osteoblast-adhesive properties of peptides carrying RGD motifs and of sequences mapped on human vitronectin. Our data suggest that osteoblast adhesion on polystyrene plates modified with a linear peptide, in which the GRGDSP sequence is repeated four times, was significantly higher when compared to the adhesion obtained using branched peptides, interestingly containing the same motif. Osteoblast adhesion assays on acellular bone matrix using this active peptide gave very promising results. We also demonstrated that a novel peptide, carrying the X-B-B-B-X-B-B-X motif (where B is a basic amino acid and X is a nonbasic residue), promotes proteoglycan-mediated osteoblast adhesion more efficiently with respect to the KRSR sequence that was recently proposed as heparan-sulfate binding peptide.     

Effects of omalizumab, a humanized monoclonal anti-IgE antibody, on nasal reactivity to allergen and local IgE synthesis.

BACKGROUND: Treatment with omalizumab has been shown to reduce serum free IgE concentrations and to have beneficial effects on allergic airway disease. However, its effect on IgE synthesis is unknown. OBJECTIVE: To determine whether omalizumab therapy affects nasal reactivity to allergen and local IgE production. METHODS: Nineteen patients with perennial allergic rhinitis were treated with intravenous omalizumab every 2 weeks for 26 weeks in an open-label study. Serum free and total IgE concentrations were measured at baseline and every 2 weeks throughout the study. Nasal challenge to dust mite allergen was performed at baseline and after 12 and 24 weeks of treatment. Nasal lavage fluid obtained before and after each nasal challenge was evaluated for mite-specific antibodies, plaque-forming cells, and productive epsilon messenger RNA (mRNA). RESULTS: During treatment, serum free IgE concentrations were decreased by 97% to 99%, and the nasal response to allergen challenge was significantly reduced on days 80 and 164. The postchallenge increase in nasal lavage mite specific IgE was significantly reduced by treatment with omalizumab on day 168. IgE plaque-forming cells and productive epsilon mRNA were not significantly affected by omalizumab treatment. CONCLUSIONS: Omalizumab treatment markedly reduced serum free IgE and the clinical response to nasal allergen challenge. However, the absence of an effect on IgE-secreting B cells and epsilon mRNA in nasal lavage fluid suggests that omalizumab treatment for 6 months does not significantly modulate synthesis of nasal IgE.     

Profilin-mediated food-induced allergic reactions are associated with oral epithelial remodeling

1. Download high-res image (218KB)
2. Download full-size image

     

Frequent spontaneous deletions at a shuttle vector locus in transgenic mice

Transgenic mice carrying multiple copies of a recoverable lambdaphage shuttle vector (     

Fibrosis progression in chronic hepatitis C patients with occult hepatitis B co-infection.

Occult hepatitis B virus (HBV) infection in individuals without hepatitis B surface antigen (HBsAg) can be identified in hepatitis C virus (HCV) infected patients. However, its role in fibrosis progression remains uncertain. This retrospective study compared the fibrosis progression (defined as fibrosis progression by at least one stage) and progression to severe fibrosis (fibrosis stage 3 or 4) in HCV patients with occult HBV infection. Occult HBV infection was diagnosed by the detection of HBV DNA in the serum of 74 consecutive anti-HCV positive patients by PCR. Thirty-one patients (41.9%) had occult HBV infection. All 74 patients had a median of 2 (range 2-3) liver biopsies. The median time between the first and last liver biopsy was 57.7 (range 15.0-132.8) months. Eleven of the 31 patients with occult HBV infection compared with 12 of the 43 patients without occult HBV infection had fibrosis progression (35.5% versus 27.9%, respectively, p=0.608). Six of the 31 patients with occult HBV infection compared with 8 of the 43 patients without occult HBV infection developed severe fibrosis (19.4% versus 18.6%, respectively, p=0.946). In conclusion, chronic HCV patients with occult HBV co-infection does not seem to progress more than patients without occult HBV infection. However, more large-scale studies are needed before a definite conclusion can be obtained.