Modulation of matrix metalloprotease-2 levels by mechanical loading of three-dimensional mesenchymal stem cell constructs: impact on in vitro tube formation

Angiogenesis is essential to tissue reconstitution, is sensitive to mechanical stresses, and currently represents one of the major challenges in tissue engineering. The pro-angiogenic matrix metalloprotease-2 (MMP-2) is upregulated in mechanically loaded mesenchymal stem cells (MSCs). Therefore, MMP-2 may provide a regulating link between angiogenesis and the surrounding mechanical conditions. This study aimed to modulate MMP-2 levels by mechanical loading of MSCs embedded in a three-dimensional matrix as well as to investigate the mechanism of MMP-2 regulation along with its contribution to angiogenesis stimulation. MMP-2-inducing conditions (30% compression, 1 Hz, 72 h) were defined after varying loading parameters. Addition of the Golgi-disturbing agent Brefeldin A suppressed this mechanical upregulation of MMP-2. Analysis of enzymatic activities demonstrated an enhancement of pro-MMP-2, mature MMP-2, and tissue inhibitor of metalloproteases-2. Further, mechano-regulation of MMP-14 and mature MMP-2 was dependent upon the activity of furin, a proprotein processing endoprotease. Angiogenesis was stimulated by conditioned media from MSCs loaded at inducing conditions. This augmentation of angiogenesis was hindered by inhibition of pro-MMP-2 and mature MMP-2. In conclusion, mechanical stimulation of MSCs in a three-dimensional matrix induces pro-MMP-2 secretion and MMP-2 activation, potentially via the activation complex consisting of MMP-2/-14/tissue inhibitor of metalloproteases-2. Mechano-regulated pro-MMP-2 and mature MMP-2 seem to contribute to angiogenesis stimulation. Thus, an application of these loading parameters could augment vascularization of tissue-engineered constructs based on the described MMP-2-dependent mechanism.

Insights into mesenchymal stem cell aging: involvement of antioxidant defense and actin cytoskeleton

Progenitor cells such as mesenchymal stem cells (MSCs) have elicited great hopes for therapeutic augmentation of physiological regeneration processes, e.g., for bone fracture healing. However, regeneration potential decreases with age, which raises questions about the efficiency of autologous approaches in elderly patients. To elucidate the mechanisms and cellular consequences of aging, the functional and proteomic changes in MSCs derived from young and old Sprague-Dawley rats were studied concurrently. We demonstrate not only that MSC concentration in bone marrow declines with age but also that their function is altered, especially their migratory capacity and susceptibility toward senescence. High-resolution two-dimensional electrophoresis of the MSC proteome, under conditions of in vitro self-renewal as well as osteogenic stimulation, identified several age-dependent proteins, including members of the calponin protein family as well as galectin-3. Functional annotation clustering revealed that age-affected molecular functions are associated with cytoskeleton organization and antioxidant defense. These proteome screening results are supported by lower actin turnover and diminished antioxidant power in aged MSCs, respectively. Thus, we postulate two main reasons for the compromised cellular function of aged MSCs: (a) declined responsiveness to biological and mechanical signals due to a less dynamic actin cytoskeleton and (b) increased oxidative stress exposure favoring macromolecular damage and senescence. These results, along with the observed similar differentiation potentials, imply that MSC-based therapeutic approaches for the elderly should focus on attracting the cells to the site of injury and oxidative stress protection, rather than merely stimulating differentiation.

Weak localization in ferromagnetic (Ga,Mn)as nanostructures

We report on the observation of weak localization in arrays of (Ga,Mn)As nanowires at millikelvin temperatures. The corresponding phase coherence length L phi is typically between 100 and 200 nm at 20 mK. Strong spin-orbit interaction in the material is manifested by a weak antilocalization correction around zero magnetic field.

Matrix metalloprotease activity is an essential link between mechanical stimulus and mesenchymal stem cell behavior

Progenitor cells are involved in the regeneration of the musculoskeletal system, which is known to be influenced by mechanical boundary conditions. Furthermore, matrix metalloproteases (MMPs) and tissue-specific inhibitors of metalloproteases (TIMPs) are crucial for matrix remodelling processes that occur during regeneration of bone and other tissues. This study has therefore investigated whether MMP activity affects mesenchymal stem cell (MSC) behavior and how MMP activity is influenced by the mechanical stimulation of these cells. Broad spectrum inhibition of MMPs altered the migration, proliferation, and osteogenic differentiation of MSCs. Expression analysis detected MMP-2, -3, -10, -11, -13, and -14, as well as TIMP-2, in MSCs at the mRNA and protein levels. Mechanical stimulation of MSCs led to an upregulation of their extracellular gelatinolytic activity, which was consistent with the increased protein levels seen for MMP-2, -3, -13, and TIMP-2. However, mRNA expression levels of MMPs/TIMPs showed no changes in response to mechanical stimulation, indicating an involvement of post-transcriptional regulatory processes such as alterations in MMP secretion or activation. One potential regulatory molecule might be the furin protease. Specific inhibition of MMP-2, -3, and -13 showed MMP-13 to be involved in osteogenic differentiation. The results of this study suggest that MSC function is controlled by MMP activity, which in turn is regulated by mechanical stimulation of cells. Thus, MMP/TIMP balance seems to play an essential role in transferring mechanical signals into MSC function. Disclosure of potential conflicts of interest is found at the end of this article.

Impact of age on the short-term postoperative outcome of patients undergoing surgery for colorectal carcinoma

BACKGROUND

Patient age has a decisive impact on the short-term postoperative results in surgery for carcinoma.

PATIENTS AND METHODS

This prospective multicenter study involved 75 German hospitals and 3756 patients undergoing treatment in 1999: 1447 aged under 65 years, 1847 aged 65-79 years, and 458 aged over 80 years.

RESULTS

In the oldest patient group, there was a significantly higher proportion of extensive, localized tumors (UICC stage II: 25.9%, 28.4%, and 36.1%, respectively) and significant differences were found among the three groups in operation rates (98.8%, 98.6%, and 96.5%), resection rate (94.2%, 93.2%, and 83.9%), general postoperative complications (21.5%, 28.6%, and 41.2%), morbidity (36.5%, 42.6%, and 50.0%) and mortality (2.7%, 6.6%, and 11.8%).

CONCLUSION

In the elderly, locally advanced tumors, but not metastasizing tumors, are to be expected. The increase in postoperative morbidity and mortality rates with increasing age was due to the increase in general postoperative complications. Surgery for colorectal carcinoma in patients of advanced age is not associated with any increase in intraoperative or specific postoperative complications.

[Prospective multi-center study colon/rectum carcinoma (primary tumors)--Results of the year 2000]

INTRODUCTION

Surgical quality control in the form of multicentre studies make it possible to analyse the treatment status of a given surgical illness under quality assurance aspects.

MATERIAL/METHODS

On 1. 1. 2000, under the patronage of the Convent of Hospital Chief Surgeons a project (ongoing) - organised and conducted by the Institute for Quality Management in Operative Medicine at the Otto-von-Guericke University of Magdeburg - was initiated to document and collect the data of patients with colorectal cancer throughout the whole of Germany. This work is supported by the German Society of Surgery, and the Surgical Working Group, Quality Assurance within the German Society of Surgery. Currently, some 282 hospitals throughout the country are involved in establishing a prospective documentation of colorectal carcinoma. Participation in this study is on a voluntary basis. The anonymity of both patients and hospitals is guaranteed, and no hospitals wishing to participate are excluded. Both operatively and conservatively treated patients are being documented, and no randomization takes place.

RESULTS

In the year 2000, the participating hospitals documented a total of 9 477 patients with a colorectal carcinoma, including 6 975 patients with a carcinoma of the colon, and 3 402 with a rectal carcinoma. The average age of the patients was 68.5 years, and there were 5 010 men and 4 467 women. The operation rate was 99.2 %, the resection rate 95.6 %. The abdominoperineal resection rate was 27.4 %. The indicators for diagnostic quality as set out by Hermanek were largely complied with, but some deviations were noted.

DISCUSSION

On the basis of the data collected, structures were established for a uniform Germany-wide quality management for a clinical condition with a major health policy impact. This information make it possible for the hospitals to identify and eliminate deficits in the structural and process quality in the diagnosis and treatment of colorectal cancer, and in this way to improve outcome quality. This means that the results of medical care research have an immediate impact on the individual treatment received by a given patient.

Process balance and product quality in the production of natural indigo from Polygonum tinctorium Ait. applying low-technology methods

Indigo is the most important blue component in the class of natural dyes for cellulose and protein fibres. In the moderate European climate Polygonum tinctorium Ait. could be an interesting source for natural indigo (Vat blue 1). Following a cultivation of the plant material a simple procedure for the extraction of the indigo precursor indican was investigated with regard to crop and quality of dye obtained. The dependence of the crop on the storage conditions of the harvested plant material was investigated. The results quantify the distinct sensitivity of the fresh material to the time of storage before extraction with regard to the amount of natural indigo obtained, the photometrically determined indigo content in the product and the shade and colour depth observed in standardised dyeing experiments. A basic set of data is presented, which describes the process in terms of consumption of energy, water and chemicals and organic waste released from the extraction step.

["Colon-/rectal carcinoma" prospective studies as comprehensive surgical quality assurance]

INTRODUCTION

Currently, only a small percentage of the diagnostic and therapeutic data on colonic carcinomas has been confirmed by data obtained in randomized controlled studies. For this reason, the results of prospective multicentre observational studies are extremely important.

METHOD

Within a multicentre observational study involving 75 surgical departments carried out between 01.01. and 31.12.1999, 3,756 patients with a colorectal carcinoma (2,293 carcinoma of the colon; 1,463 carcinomas or the rectum) were investigated prospectively using a standardised questionnaire.

RESULTS

The OP rate was 98.4%, the resection rate 92.5% (colon 94.1%, rectum 89.9%). The rate of rectal extirpations was relatively high at 30.3%. General postoperative morbidity was 27.4% (colon 27.0%, rectum 27.9%); the specific postoperative morbidity was 24.6% (colon 21.8%, rectum 29.1%). The anastomotic insufficiency rate was 5.2% (colon 3.7%, rectum 9.5%). The 30-day mortality rate was 4.7%, and the postoperative mortality rate 5.7%.

CONCLUSIONS

Surgical quality control in the form of prospective multicentre observational studies make possible the analysis of the therapeutic situation of a surgical disease under quality assurance aspects. At the same time, the comprehensive data material available will serve the specific planning of prospective randomized studies. With the aid of the present study, a basis for a thorough and complete evaluation of colorectal carcinoma has been created.

Effect of caseload on the short-term outcome of colon surgery: results of a multicenter study

This prospective multicenter study investigated the effect of hospital caseload on early postoperative outcome of surgery for carcinoma of the colon in 75 German hospitals and included 2293 patients. The hospitals were divided into those with a caseload of 1-30 (group A), 31-60 (group B), and more than 60 (group C) operations. Increasing caseload was associated only with fewer general postoperative complications. It was also associated with significantly greater use of antibiotic prophylaxis. No significant differences between the groups were found in resection rates, intraoperative complications, specific postoperative complications, overall postoperative morbidity, hospital mortality, or 30-day mortality. The significance of hospital caseload for the short-term postoperative outcome following surgery on the colon should not be overestimated. Basing conclusions about the results to be expected simply on the case volume is impermissible. On the basis of the available data it is not possible to establish a threshold value, that is, a minimum number of required operations.

Anorexia in rats infected with the nematode, Nippostrongylus brasiliensis: experimental manipulations

Nippostrongylus brasiliensis induces a biphasic anorexia in laboratory rats, the first phase coincident with lung invasion (ca day 2) and the second when the worms mature in the intestine (ca day 8). Using the anthelminthic, mebendazole (MBZ), N. brasiliensis infections of the rat were eliminated between the first and second anorexic episodes. This intervention prevented the expression of the second phase of anorexia. Rats exposed to a second infection with N. brasiliensis, 3 weeks after the primary infection, exhibited only a first phase anorexic response which was not influenced by MBZ termination of the primary infection. The lower cumulative food intake and weight gain of all infected rats after 8 days of infection were accompanied by elevated plasma insulin and, in some individuals, by elevated plasma leptin, compared with uninfected controls and previously-infected MBZ-treated rats. Messenger RNA levels for neuropeptide Y were higher in the hypothalamic arcuate nucleus of 8-day infected rats than in recovering MBZ-treated animals. Inoculation of rats with heat-killed N. brasiliensis larvae failed to induce anorexia and did not alter the severity of biphasic anorexia on subsequent injection of viable larvae. The first anorexic episode is therefore dependent upon viable migrating larvae. The second phase of anorexia clearly requires the continuing presence of the parasite beyond the lung phase. Viable migrating larvae are also required to confer 'resistance' to reinfection.

Toxoplasma gondii infection: analysis of serological response by 2-DE immunoblotting

Toxoplasma gondii is known to cause a variety of diseases ranging from asymptomatic infections to serious conditions in immunocompromised hosts such as AIDS-patients or transplant recipients. In addition they may cause abortion or fetal abnormalities during pregnancy. Despite the clinical importance, diagnosis, treatment and prevention still remain unsatisfactory. Analysis of the parasitic cell determinants, recognized by specific humoral and cellular immune responses, may have important implications for diagnosis, therapy and vaccination strategies. Two-dimensional electrophoresis (2-DE) was used to resolve and compare protein patterns from Toxoplasma gondii strains RH and BK (mouse virulent strains). Comparison of silver-stained gels showed that 35.2% to 60.3% of the spots had the same position. In a second series of experiments, the reactivity of the spots with human sera was tested. Proteins were transferred to PVDF membranes and were detected with sera from different patient groups. Depending upon the immunoglobulin class (IgG, IgM, IgA or IgE) different epitope patterns were observed. Some of the spots seemed to be recognized in different stages of infection. Sera of two patients with similar serology and comparable stage of infection were compared in order to demonstrate an individual immune response.

A novel protein complex promoting formation of functional alpha- and gamma-tubulin

We describe the identification of GIM1/YKE2, GIM2/PAC10, GIM3, GIM4 and GIM5 in a screen for mutants that are synthetically lethal with tub4-1, encoding a mutated yeast gamma-tubulin. The cytoplasmic Gim proteins encoded by these GIM genes are present in common complexes as judged by co-immunoprecipitation and gel filtration experiments. The disruption of any of these genes results in similar phenotypes: the gim null mutants are synthetically lethal with tub4-1 and super-sensitive towards the microtubule-depolymerizing drug benomyl. All except Deltagim4 are cold-sensitive and their microtubules disassemble at 14 degrees C. The Gim proteins have one function related to alpha-tubulin and another to Tub4p, supported by the finding that the benomyl super-sensitivity is caused by a reduced level of alpha-tubulin while the synthetic lethality with tub4-1 is not. In addition, GIM1/YKE2 genetically interacts with two distinct classes of genes, one of which is involved in tubulin folding and the other in microtubule nucleation. We show that the Gim proteins are important for Tub4p function and bind to overproduced Tub4p. The mammalian homologues of GIM1/YKE2 and GIM2/PAC10 rescue the synthetically lethal phenotype with tub4-1 as well as the cold-sensitivity and benomyl super-sensitivity of the yeast deletion mutants. We suggest that the Gim proteins form a protein complex that promotes formation of functional alpha- and gamma-tubulin.

The spindle pole body component Spc97p interacts with the gamma-tubulin of Saccharomyces cerevisiae and functions in microtubule organization and spindle pole body duplication

Previously, we have shown that the gamma-tubulin Tub4p and the spindle pole body component Spc98p are involved in microtubule organization by the yeast microtubule organizing centre, the spindle pole body (SPB). In this paper we report the identification of SPC97 encoding an essential SPB component that is in association with the SPB substructures that organize the cytoplasmic and nuclear microtubules. Evidence is provided for a physical and functional interaction between Tub4p, Spc98p and Spc97p: first, temperature-sensitive spc97(ts) mutants are suppressed by high gene dosage of SPC98 or TUB4. Second, Spc97p interacts with Spc98p and Tub4p in the two-hybrid system. Finally, immunoprecipitation and fractionation studies revealed complexes containing Tub4p, Spc98p and Spc97p. Further support for a direct interaction of Tub4p, Spc98p and Spc97p comes from the toxicity of strong SPC97 overexpression which is suppressed by co-overexpression of TUB4 or SPC98. Analysis of temperature-sensitive spc97(ts) alleles revealed multiple spindle defects. While spc97-14 cells are either impaired in SPB separation or mitotic spindle formation, spc97-20 cells show an additional defect in SPB duplication. We discuss a model in which the Tub4p-Spc98p-Spc97p complex is part of the microtubule attachment site at the SPB.

The spindle pole body component Spc98p interacts with the gamma-tubulin-like Tub4p of Saccharomyces cerevisiae at the sites of microtubule attachment

Tub4p is a novel tubulin found in Saccharomyces cerevisiae. It most resembles gamma-tubulin and, like it, is localized to the yeast microtubule organizing centre, the spindle pole body (SPB). In this paper we report the identification of SPC98 as a dosage-dependent suppressor of the conditional lethal tub4-1 allele. SPC98 encodes an SPB component of 98 kDa which is identical to the previously described 90 kDa SPB protein. Strong overexpression of SPC98 is toxic, causing cells to arrest with a large bud, defective microtubule structures, undivided nucleus and replicated DNA. The toxicity of SPC98 overexpression was relieved by co-overexpression of TUB4. Further evidence for an interaction between Tub4p and Spc98p came from the synthetic toxicity of tub4-1 and spc98-1 alleles, the dosage-dependent suppression of spc98-4 by TUB4, the binding of Tub4p to Spc98p in the two-hybrid system and the co-immunoprecipitation of Tub4p and Spc98p. In addition, Spc98-1p is defective in its interaction with Tub4p in the two-hybrid system. We suggest a model in which Tub4p and Spc98p form a complex involved in microtubule organization by the SPB.

gamma-Tubulin-like Tub4p of Saccharomyces cerevisiae is associated with the spindle pole body substructures that organize microtubules and is required for mitotic spindle formation

Tub4p is a novel tubulin in Saccharomyces cerevisiae that most closely resembles gamma-tubulin. We report in this manuscript that the essential Tub4p is associated with the inner and outer plaques of the yeast microtubule organizing center, the spindle pole body (SPB). These SPB substructures are involved in the attachment of the nuclear and cytoplasmic microtubules, respectively (Byers, B., and L. Goetsch. 1975. J. Bacteriol. 124:511-523). Study of a temperature sensitive tub4-1 allele revealed that TUB4 has essential functions in microtubule organization. Remarkably, SPB duplication and separation are not impaired in tub4-1 cells incubated at the nonpermissive temperature. However, SPBs from such cells contain less or misdirected nuclear microtubules. Further analysis revealed that tub4-1 cells are able to assemble a short bipolar spindle, suggesting that the defect in microtubule organization occurs after spindle formation. A role of Tub4p in microtubule organization is further suggested by an increase in chromosome loss in tub4-1 cells. In addition, cell cycle arrest and survival of tub4-1 cells is dependent on the mitotic checkpoint control gene BUB2 (Hoyt, M.A., L. Totis, B.T. Roberts. 1991. Cell. 66:507-517), one of the cell's monitors of spindle integrity.

Serine protease EpiP from Staphylococcus epidermidis catalyzes the processing of the epidermin precursor peptide

The function of serine protease EpiP in epidermin biosynthesis was investigated. Epidermin is synthesized as a 52-amino-acid precursor peptide, EpiA, which is posttranslationally modified and processed to the mature 22-amino-acid peptide antibiotic. epiP was expressed in Staphylococcus carnosus with xylose-regulated expression vector pCX15. The cleavage of the unmodified EpiA precursor peptide to leader peptide and proepidermin by EpiP-containing culture filtrates of S. carnosus (pCX15epiP) was followed by reversed-phase chromatography and subsequent electrospray mass spectrometry.

A counterselectable pACYC184-based lacZ alpha-complementing plasmid vector with novel multiple cloning sites; construction of chromosomal deletions in Klebsiella pneumoniae

We have constructed a series of small, chloramphenicol-resistance-encoding, lacZ alpha-complementing vectors with novel multiple cloning sites, based on the pACYC184 replicon. The sacB gene of Bacillus subtilis, which is lethal to Gram- organisms in the presence of sucrose, was cloned into one of these, giving the counterselectable vector pSG335. This was used to substitute a streptomycin-resistance-encoding cassette for the ntrBC genes in the Klebsiella pneumoniae chromosome.

[Current therapy of chronic arterial occlusive diseases of the lower extremities]

Angiologists, vascular surgeons, and angiographers inform about the actual state of the therapy of the arterial occlusive diseases of the legs. The degree I of therapy comprises the conservative treatment for the improvement of the macrocirculation and the normalisation of the disturbed microcirculation, taking into particular consideration the therapy with antiviscositant drugs. The main chapter ends with the possibilities of the influence on the arteriosclerotic vascular processes as well as with the necessary rehabilitative measures. In the paragraph about the degree II of therapy the indications, contraindications, methods and results of the isolated and combined percutaneous transluminal angioplasty, the systemic and local fibrinolysis as well as the reconstructive vascular operations are represented.

[Radiation dosage of the lens and gonads in selected CT studies]

The article is a compilation of data on the radiation exposure during the most important CT examinations. The influencing parameters are assessed and their effects are discussed. Conclusions are drawn to modify the practical approach. These results are compared with those reported in international literature.