An optimised split-and-recombine micro-mixer with uniform chaotic mixing

A second generation micro-mixer, being a further optimised version of a first prototype, relying on the consequent utilisation of the split-and-recombine principle is presented. We show that the mixing can be characterized by a positive finite-time Lyapunov exponent although being highly regular and uniform. Using computational fluid dynamics (CFD) we investigate the mixing performance for Reynolds numbers in the range of about 1 to about 100. In particular for low Reynolds numbers (Re < 15) the CFD results predict an almost ideal multi-lamination. Thus, the developed mixer is especially suited for efficient mixing of highly viscous fluids. Furthermore, the numerical results are experimentally validated by investigations of mixing of water-glycerol solutions. The experimental results are found to be in excellent agreement with the numerical data and prove the high mixing efficiency.

[Influence of processing and sterilization on the mechanical properties of pins made from bovine cortical bone]

In a biomechanical study pins made of xenogenous cortical bone were tested in vitro. Forty pins of 3 mm diameter and 60 mm length were made of eight different cattle tibiae and allocated to five different treatment groups. Freeze-dried pins served as control group. Pins of the second group were preserved in concentrated sodium chloride solution and defatted with acetone (Tuto-plast processing). Pins of groups three to five were treated with sodium chloride and acetone and afterwards sterilized by different means (ethylene oxide, autoclavation, or gamma radiation). All pins were subjected to a three-point-bending test and a shear test. We found that bending strength and shearing strength were most increased after sodium chloride and acetone treatment, whereas after sterilization with ethylene oxide or autoclaving, the stability of the pins was similar to the control group. The stability was considerably diminished after gamma radiation. Taking into account possible toxic side effects of ethylene oxide, we conclude that Tutoplast processing followed by autoclavation presents a reliable preparation method for the clinical use of implants made of bovine cortical bone.

Bioengineered human bone tissue using autogenous osteoblasts cultured on different biomatrices

Surgical treatment of critical-size posttraumatic bone defects is still a challenging problem, even in modern bone and joint surgery. Progress in cellular and molecular biology during the last decade now permits novel approaches in bone engineering. Recent conceptual and technical advances have enabled the use of mitotically expanded, bone-derived cells as a therapeutic approach for tissue repair. Using three different tissue carrier systems, we successfully cultivated human osteoblasts in a newly developed perfusion chamber. We studied cell proliferation and the expression of osteocalcin, osteopontin, bone morphogenetic protein-2A, alkaline phosphatase, and vascular endothelial growth factor as parameters for osteoblast function and viability. Adherence of highly enriched human osteoblasts had already started after 1 h and resulted in completely overgrown human bone pieces after 10 days. Expression analysis of bone-specific alkaline phosphatase indicated differentiating osteoblasts, whereas the high mRNA expression of osteocalcin and osteopontin revealed terminally differentiated osteoblasts and the process of mineralization. Additionally, gene expression was significantly higher when demineralized bone was used as biomatrix, compared to autoclaved bone and hydroxyapatite ceramics. We conclude that with our newly developed perfusion culture system, vital autogenous bone implants of clinically applicable size can be generated within 17 days in order to manage critical-size bone defects.

[Hypophyseal hyperplasia in primary hypothyroidism]

Fallbeispiel einer Hyperplasie der Hypophyse aufgrund eines sekundären TSH-Exzesses bei Enthemmung der TRH-Sekretion aufgrund einer primären Hypothyreose bei St.n. Autoimmunthyreoiditis. Normalisierung der Befunde nach drei Monaten adäquater Hormonsubstitution.

Chances and shortcomins of adenovirus-mediated ATP7B gene transfer in Wilson disease: proof of principle demonstrated in a pilot study with LEC rats

BACKGROUND & AIMS

Wilson disease (WD) is an autosomal recessively inherited copper storage disease due to mutations in the ATP7B gene. It results in impaired biliary copper excretion followed by liver injury leading to cirrhosis. In parallel, copper accumulates in other tissues e. g. basal ganglia of the brain inducing motoric disorders. Phenotypical cure of Wilson disease by liver transplantation raised the question whether gene therapy may represent a successful alternative treatment procedure. To examine the principle feasibility of this approach we investigated the effects of gene transfer using an adenoviral vector construct expressing the human ATP7B cDNA in an established rodent model for WD, the Long-Evans Cinnemon rat (LEC).

METHODS

Transduction efficiency was assessed by RT-PCR, Western blot and immunofluorescence analysis. The therapeutic effect was estimated by analyzing holoceruloplasmin and its ferroxidase activity in serum, and the copper content of excrements. Changes in copper homeostasis were determined by positron emission tomography (PET).

RESULTS

Successful, but temporary gene transfer was clearly detectable on RNA and protein levels. In parallel the temporary therapeutic effect was documented by restoration of serum holoceruloplasmin and of its ferroxidase activity. Additionally the Ad-ATP7B treated LEC rat revealed a higher (64)Cu content in stool. PET was able to visualize differences in (64)Cu distribution between wild type and LEC rats, indicating its principle usefulness as analytical tool.

CONCLUSION

The data demonstrate proof of principle of successful gene therapy in an experimental model of WD. As a consequence of successful but only transient therapeutic effect of adenoviral gene transfer we can now focus more efficient and permanent gene transfer strategies.

[Living organ donation vs. cadaveric donation - study of liver transplanted children and their families]

There is only scarce information on the quality of life of child recipients of liver transplants and their families. Particularly children with a living related graft and their families never have been compared to children who received a cadaveric graft and their families. We investigated the following issues in our study: How do parents and children from participating families rate their strain, their quality of life and their relationships within their family? Do families with a living - related donor differ from those with a cadaveric donor? What do living donors and their partners think about the donation retrospectively? The study was conducted with 106 participants from 50 families (42 mothers, 40 fathers, and 24 children older than 6 years). In 20 of these families, a living transplantation had been performed. Participants were interviewed and asked to fill out several questionnaires. School-aged children with a liver transplant show good social integration among their peers and in school. The child's disease, however, has a great impact on the family. Family members show a reduction in social contact, and an increase in marital crises, and problematic relations amongst siblings. Families in which a cadaveric graft was performed, are less satisfied with life, and show more symptoms of exhaustion. Every family studied possessed or acquired - a high degree of internal or external coping resources. Living - related donors tried hard to obtain an understanding of the medical context. The partner, rather than the donor himself, feels anxious before the donation. The limited time available for the decision to donate is not perceived by the donors to be critical. Ten percent of living donors feel "a little" that their health is affected. The decision to donate is supported "strongly" or "very strongly" by the partners in 80 % of the cases. A possible strain on the child through the expectation of gratitude by the donor is stated by 20 %. All of the donors agree that if they were to be asked today, they would donate again, only one of the partners raised objections. In summary, as a retrospective pilot study, this study primarily generates hypotheses rather than testing them and helps to develop research tools for the field. Results suggest that a psychological support be made available both prior to and following the operation, not only for the children but also for their families, with particular attention to the partners of the living donors and the siblings of the affected children.

Sequential expression of annexin A5 in the vasculature and skeletal elements during mouse development

Annexin A5 (annexin V, anchorin CII) represents the prototype member of the large annexin family, characterized by its ability to interact with phospholipids in a calcium-dependent manner and to form calcium-specific ion channels. Despite intense biochemical analysis, the in vivo expression and function of this annexin during mouse development, still remains unclear. Immunohistochemistry, in situ hybridization and reporter gene expression were used to define expression of annexin A5 during early mouse development. First, annexin A5 expression is associated with the developing vascular system. Later, expression is detected within the notochord and found in parallel to the differentiation of cartilage and bone. Therefore, expression of the Anxa5 gene may represent a novel marker characterizing cell lineages involved in the development of the vascular as well as the skeletal system.

The role of the urokinase-type plasminogen activator (uPA) and its receptor (CD87) in lipodermatosclerosis

BACKGROUND

Lipodermatosclerosis refers to a sclerosing panniculitis and dermopathy of the lower extremities sometimes seen in association with venous ulceration. Matrix metalloproteinases are implicated in the pathogenesis of venous leg ulcers and the in vitro activation of recombinant MMP-2 is controlled by the plasminogen activation system. To better understand the role of plasminogen activation in the pathogenesis of venous leg ulcers we investigated fibrinolytic factors and their inhibitors in tissue samples of lipodermatolsclerosis.

METHODS

The expression and the functional state of the urokinase-type plasminogen activator (uPA), the tissue-type plasminogen activator (tPA), the urokinase receptor (CD87), the plasminogen activator inhibitors-1 and -2 (PAI-1 and PAI-2) were assayed using reverse transcription polymerase chain reaction, Western blot, fibrin zymography and immunohistochemistry analyses in tissue samples of lipodermatosclerosis.

RESULTS

Our results provide direct evidence of elevated expression of uPA (p<0.01) and CD87 (p<0.01) mRNA and protein level in lipodermatosclerosis in comparison with healthy skin. By immunohistochemistry, elevated expression of uPA and CD87 could be detected. Fibrin zymography showed significantly elevated endogenous uPA activity (p<0.01) in liposclerotic lesions compared to healthy controls.

CONCLUSION

Our findings indicate that elevated plasminogen activation in lipodermatosclerotic tissue may play a crucial role in the pathogenesis of venous leg ulceration.

Molecular basis of the neutrophil glycoprotein NB1 (CD177) involved in the pathogenesis of immune neutropenias and transfusion reactions

The human granulocyte alloantigen NB1, recently clustered as CD177, is heterogenously expressed on neutrophils of 88-97% of healthy individuals. Since its molecular nature has remained unknown, we isolated NB1 glycoprotein from granulocyte lysate by immunoaffinity chromatography. MALDI-TOF mass spectrometry identified a 50,556 Da glycoprotein which was reduced to 43,069 Da after removal of N-linked carbohydrates. Following N-terminal amino acid sequencing and NB1-specific primer construction, rapid amplification of cDNA ends PCR yielded a 1,614-bp cDNA for NB1. COS-7 cells transfected with the cDNA expressed immunoreactive NB1 glycoprotein. A 1,311-bp sequence was identified to be the entire coding region. The 5' and 3' untranslated regions consist of 27 bp and 276 bp, respectively. The open reading frame codes for 437 amino acids of which the first 21 form the signal peptide. The remaining 416 residues form a N-terminal extracellular protein with two cysteine-rich domains, three N-linked glycosylation sites and short transmembrane and cytoplasmic segments including a glycosyl-phosphatidylinositol attachment (omega) site. Database searches revealed homology to Ly-6 (uPAR) domain, suggesting that NB1 belongs to urokinase plasminogen activator receptor/CD59/Ly-6 snake toxin superfamily.

Incorporation of decay-accelerating factor into the baculovirus envelope generates complement-resistant gene transfer vectors

Baculovirus vectors are an efficient means to deliver genes into hepatocytes in vitro. In experiments that exclude components of the complement system, gene transfer is facilitated. Therefore, the complement system has been defined to represent a potent primary barrier to direct application of baculoviruses in vivo. Here we have genetically manipulated baculoviruses so that the complement-regulatory protein human decay- accelerating factor (DAF) is incorporated into the viral envelope. We found that this modification protected baculovirus vectors against complement-mediated inactivation. Complement-resistant baculovirus vectors were additionally analyzed by immunoblotting and electron microscopy, showing the extent of envelope-incorporated DAF and shape of complement-resistant baculoviruses after exposure to complement. This modified baculovirus vector allowed for an enhanced gene transfer into complement-sufficient neonatal rats in vivo, and thus represents a step in the development of improved alternative viral vectors for gene therapy.

[Strength testing of pins made of human femur cortical bone]

For biomechanical evaluation of cortical bone as a potential source for internal fixation devices, pins of 2 and 3 mm in diameter were made from fresh human femora and subjected to bending loads. Some of the pins were tested without further treatment; others were defatted and dried in acetone solution. Of the acetone-treated pins, some were autoclaved either at 121 degrees C for 20 min or at 134 degrees C for 8 min. Acetone treatment of the pins caused a 5.5% increase in bending strength (p < or = 0.05) and a 6.6% increase in the elastic modulus (p < or = 0.05). The mean bending strength of the acetone-treated pins was 257 +/- 52 N/mm2 and the mean elastic modulus was 18,346 +/- 1292 N/mm2. Autoclaving of the pins at the lower temperature for a longer time led to a decrease in the bending strength of up to 16% and at the higher temperature for a shorter time to a decrease of up to 41%. To compare the strengths of the cortical and synthetic pins, 2-mm Biofix pins were also tested. The Biofix pins showed a 25% higher bending strength than the acetone-treated pins but a 12.5% lower elastic modulus. It should be noted that in animal studies the synthetic Biofix pins showed a 20% loss of strength within 2 days after implantation in situ.

Autologous platelet-derived wound healing factor promotes angiogenesis via alphavbeta3-integrin expression in chronic wounds

Healing of venous leg ulcers depends on the adhesive interaction and formation of new vascular cells. Angiogenesis on the surface of angiogenic blood vessels requires the vascular integrin alphavbeta3 also known as the vitronectin receptor. Autologous platelet-derived wound healing factor (autologous PDWHF) has been described to regulate the wound healing process by forming granulation tissue in the early healing phase. Here we analysed the influence of autologous PDWHF on the expression of the alphavbeta3 integrin in tissue specimen of venous leg ulcers in comparison with placebo treated controls by using reverse transcriptase-polymerase chain reaction and immunohistochemistry. Our investigations provide evidence that mRNA and protein expression of alphavbeta3 were significantly increased in healing venous leg ulcers after 96 h treatment (p<0.05), whereas the total amount of alphavbeta3 mRNA and protein was not altered in placebo treated patients. In healing leg ulcers the alphavbeta3 integrin was predominantly localized around capillary vessels preferentially at sites of newly formed granulation tissue. Placebo controlled patients displayed no altered expression of the alphavbeta3 integrin in biopsy specimen. These findings suggest that topical autologous platelet-derived wound healing factor influences the process of angiogenesis/revascularization via alphavbeta3 integrin-expression hereby promoting granulation tissue formation in healing leg ulcers.

Ovine adenovirus vectors mediate efficient gene transfer to skeletal muscle

Ovine adenovirus (OAV) vectors represent a promising tool for human gene therapy since these vectors overcome the problem of pre-existing immunity against human adenovirus vectors. In this report we investigated the in vivo characteristics of this novel vector system with respect to its potential for gene transfer into skeletal muscle. We found that moderate doses of an OAV-derived vector expressing the human alpha1-antitrypsin gene (OAVhaat) infected skeletal muscle in mice very efficiently resulting in high serum hAAT levels. The infection was restricted to skeletal muscle, but gene expression was transient and vector DNA was rapidly cleared. Vector clearance was also observed with a vector that lacked the transgene. The loss of vector DNA was accompanied by a cellular immune response in the infected muscle but was not connected with detectable expression of early or late genes of the viral backbone as analyzed by RT-PCR. A very low dose of OAVhaat (3x 10(7) infectious particles) was sufficient to produce reasonable amounts (>100 ng/ml) of serum hAAT, and this was accompanied by a weak immune response to the vector. Under these conditions, a second intramuscular injection of the same recombinant OAV vector was successful. Our study expands the known tissue tropism of OAV-derived vectors in vivo and points to the possible utility of the vector for muscle gene transfer and vaccination.

Upper esophageal sphincter function during gastroesophageal reflux events revisited

Upper esophageal sphincter (UES) function during gastroesophageal reflux events is not completely elucidated because previous studies addressing this issue yielded conflicting results. We reexamined the UES pressure response to intraluminal esophageal pressure and pH changes induced by reflux events. We studied 14 healthy, asymptomatic volunteers (age 49 +/- 6 yr) and 7 gastroesophageal reflux disease patients (age 48 +/- 5 yr). UES pressure, intraesophageal pressure, and pH were monitored at the distal, middle, and proximal esophagus concurrently in the supine position 1 h before and 2 h after a 1,000-calorie meal. A total of 321 reflux events were identified by the development of abrupt reflux-induced intraesophageal pressure increase (IPI); 285 events occurred in patients and 36 in control subjects. In control subjects 33 of 36 and in patients 252 of 285 IPI events were associated with a pH drop. Among patients and control subjects, 99% and 100%, respectively, of all IPI events irrespective of pH drop were associated with abrupt increase in UES pressure (34 +/- 2 and 27 +/- 6 mmHg, respectively). The average percentage of maximum UES pressure increase over prereflux values ranged between 66% and 96% (control subjects) and 34% and 122% (patients). IPIs induced by both acidic and nonacidic reflux events evoke strong UES contractile responses.