Functional respiratory morphology in the newborn quokka wallaby (Setonix brachyurus)

A morphological and morphometric study of the lung of the newborn quokka wallaby (Setonix brachyurus) was undertaken to assess its morphofunctional status at birth. Additionally, skin structure and morphometry were investigated to assess the possibility of cutaneous gas exchange. The lung was at canalicular stage and comprised a few conducting airways and a parenchyma of thick-walled tubules lined by stretches of cuboidal pneumocytes alternating with squamous epithelium, with occasional portions of thin blood-gas barrier. The tubules were separated by abundant intertubular mesenchyme, aggregations of developing capillaries and mesenchymal cells. Conversion of the cuboidal pneumocytes to type I cells occurred through cell broadening and lamellar body extrusion. Superfluous cuboidal cells were lost through apoptosis and subsequent clearance by alveolar macrophages. The establishment of the thin blood-gas barrier was established through apposition of the incipient capillaries to the formative thin squamous epithelium. The absolute volume of the lung was 0.02 +/- 0.001 cm(3) with an air space surface area of 4.85 +/- 0.43 cm(2). Differentiated type I pneumocytes covered 78% of the tubular surface, the rest 22% going to long stretches of type II cells, their precursors or low cuboidal transitory cells with sparse lamellar bodies. The body weight-related diffusion capacity was 2.52 +/- 0.56 mL O(2) min(-1) kg(-1). The epidermis was poorly developed, and measured 29.97 +/- 4.88 microm in thickness, 13% of which was taken by a thin layer of stratum corneum, measuring 4.87 +/- 0.98 microm thick. Superficial capillaries were closely associated with the epidermis, showing the possibility that the skin also participated in some gaseous exchange. Qualitatively, the neonate quokka lung had the basic constituents for gas exchange but was quantitatively inadequate, implying the significance of percutaneous gas exchange.

Distribution of intracellular and secreted surfactant during postnatal rat lung development

Pulmonary surfactant prevents alveolar collapse via reduction of surface tension. In contrast to human neonates, rats are born with saccular lungs. Therefore, rat lungs serve as a model for investigation of the surfactant system during postnatal alveolar formation. We hypothesized that this process is associated with characteristic structural and biochemical surfactant alterations. We aimed to discriminate changes related to alveolarization from those being either invariable or follow continuous patterns of postnatal changes. Secreted active (mainly tubular myelin (tm)) and inactive (unilamellar vesicles (ulv)) surfactant subtypes as well as intracellular surfactant (lamellar bodies (lb)) in type II pneumocytes (PNII) were quantified before (day (d) 1), during (d 7), at the end of alveolarization (d 14), and after completion of lung maturation (d 42) using electron microscopic methods supplemented by biochemical analyses (phospholipid quantification, immunoblotting for SP-A). Immunoelectron microscopy determined the localization of surfactant protein A (SP-A). (1) At d 1 secreted surfactant was increased relative to d 7-42 and then decreased significantly. (2) Air spaces of neonatal lungs comprised lower fractions of tm and increased ulv, which correlated with low SP-A concentrations in lung lavage fluid (LLF) and increased respiratory rates, respectively. (3) Alveolarization (d 7-14) was associated with decreasing PNII size although volume and sizes of Lb continuously increased. (4) The volume fractions of Lb correlated well with the pool sizes of phospholipids in lavaged lungs. Our study emphasizes differential patterns of developmental changes of the surfactant system relative to postnatal alveolarization.

Endothelin A-receptor blockade in experimental diabetes improves glucose balance and gastrointestinal function

Secondary complications of diabetes mellitus often involve gastrointestinal dysfunction. In the experimental Goto Kakizaki rat, a model of Type II diabetes, hyperglycaemia and reduced glucose clearance is associated with elevated plasma endothelin (ET)-1 levels and selective decreases in nitric oxide synthase in circular muscle, longitudinal muscle and neuronal elements of the gastrointestinal tract. Functionally, this is accompanied by decreased nitrergic relaxatory responses of jejunal longitudinal muscle to tetrodotoxin-sensitive electrical field stimulation. Long-term treatment with a selective ET A-type receptor antagonist, markedly reduced hyperglycaemia and restored plasma glucose clearance rates towards normal. This was associated with a restoration of N(G)-nitro-L-arginine methyl ester-sensitive relaxatory responses of jejunal longitudinal muscle to electrical field stimulation. The results indicate that beneficial effects of ETA receptor blockade on gastrointestinal function may result from an improvement in insulin sensitivity with concomitant reduction of the severity of hyperglycaemia. ETA receptor blockade may represent a new therapeutic principle for improving glucose tolerance in Type II diabetes and could be beneficial in alleviating or preventing hyperglycaemia-related secondary complications in this condition.

Chondrogenic potential of human synovial mesenchymal stem cells in alginate

OBJECTIVE: In a recent study, we demonstrated that mesenchymal stem cells (MSCs) derived from the synovial membranes of bovine shoulder joints could differentiate into chondrocytes when cultured in alginate. The purpose of the present study was to establish the conditions under which synovial MSCs derived from aging human donors can be induced to undergo chondrogenic differentiation using the same alginate system. METHODS: MSCs were obtained by digesting the knee-joint synovial membranes of osteoarthritic human donors (aged 59-76 years), and expanded in monolayer cultures. The cells were then seeded at a numerical density of 4x10(6)/ml within discs of 2% alginate, which were cultured in serum-containing or serum-free medium (the latter being supplemented with 1% insulin, transferrin, selenium (ITS). The chondrogenic differentiation capacity of the cells was tested by exposing them to the morphogens transforming growth factor-beta1 (TGF-beta1), TGF-beta2, TGF-beta3, insulin-like growth factor-1 (IGF-1), bone morphogenetic protein-2 (BMP-2) and BMP-7, as well as to the synthetic glucocorticoid dexamethasone. The relative mRNA levels of collagen types I and II, of aggrecan and of Sox9 were determined quantitatively by the real-time polymerase chain reaction (PCR). The extracellular deposition of proteoglycans was evaluated histologically after staining with Toluidine Blue, and that of type-II collagen by immunohistochemistry. RESULTS: BMP-2 induced the chondrogenic differentiation of human synovial MSCs in a dose-dependent manner. The response elicited by BMP-7 was comparable. Both of these agents were more potent than TGF-beta1. A higher level of BMP-2-induced chondrogenic differentiation was achieved in the absence than in the presence of serum. In the presence of dexamethasone, the BMP-2-induced expression of mRNAs for aggrecan and type-II collagen was suppressed; the weaker TGF-beta1-induced expression of these chondrogenic markers was not obviously affected. CONCLUSIONS: We have demonstrated that synovial MSCs derived from the knee joints of aging human donors possess chondrogenic potential. Under serum-free culturing conditions and in the absence of dexamethasone, BMP-2 and BMP-7 were the most potent inducers of this transformation process.

Site-1 protease is essential for endochondral bone formation in mice

Site-1 protease (S1P) has an essential function in the conversion of latent, membrane-bound transcription factors to their free, active form. In mammals, abundant expression of S1P in chondrocytes suggests an involvement in chondrocyte function. To determine the requirement of S1P in cartilage and bone development, we have created cartilage-specific S1P knockout mice (S1P(cko)). S1P(cko) mice exhibit chondrodysplasia and a complete lack of endochondral ossification even though Runx2 expression, Indian hedgehog signaling, and osteoblastogenesis is intact. However, there is a substantial increase in chondrocyte apoptosis in the cartilage of S1P(cko) mice. Extraction of type II collagen is substantially lower from S1P(cko) cartilage. In S1P(cko) mice, the collagen network is disorganized and collagen becomes entrapped in chondrocytes. Ultrastructural analysis reveals that the endoplasmic reticulum (ER) in S1P(cko) chondrocytes is engorged and fragmented in a manner characteristic of severe ER stress. These data suggest that S1P activity is necessary for a specialized ER stress response required by chondrocytes for the genesis of normal cartilage and thus endochondral ossification.

In vitro resistance of articular chondrocytes to 5-Aminolevulinic acid based photodynamic therapy

OBJECTIVE: 5-Aminolevulinic acid based photodynamic therapy (5-ALA-PDT) has revealed promising results in the treatment of inflammatory joint diseases due to the sensitivity of inflamed synovial tissue. For 5-ALA-PDT to be safe and beneficial for intra-articular applications, resistance of chondrocytes is essential to prevent cartilage damage. As no data yet exist, the aim of the present study was to assess in vitro the response of the chondrocytes to 5-ALA-PDT and to compare with osteoblasts and synovial tissue derived cells. METHODS: Bovine articular chondrocytes, osteoblasts, and synovial cells were subjected to 5-ALA-PDT in cell culture. The PpIX accumulation and the function of the cells were assessed for up to 12 days. RESULTS: Bovine chondrocytes showed lower PpIX fluorescence upon incubation with 5-ALA (0.0-2.0 mM) for 4 hours as compared to osteoblasts and synovial cells suggesting a low PpIX accumulation. After incubation with 0.5 mM 5-ALA and application of light at a dose of 20 J/cm2, chondrocytes were functionally not affected (collagen type II and aggrecan mRNA, glycosaminoglycan synthesis) whereas a decrease in the proportion of viable cells was observed in osteoblasts and synovial cells (2+/-2% and 14+/-8%, respectively; chondrocytes 91+/-13%). Chondrocytes showed a 58% reduction of 5-ALA uptake using [3H]5-ALA as compared to osteoblasts and a lower mitochondrial content as assessed by the activity of the mitochondrial marker enzyme citrate synthase (9.2+/- 3.6 mU/mg protein) than osteoblasts (32.6+/-10.5 mU/mg) and synovial cells (60.0+/-10.8 mU/mg). The reduced uptake of 5-ALA and/or the low mitochondrial content, an adaptation to their in vivo environment and the site of PpIX synthesis, presumably explains the lower PpIX content in chondrocytes and their resistance against 5-ALA-PDT. CONCLUSION: 5-ALA-PDT might represent a treatment strategy in inflammatory joint diseases without endangering the cartilage function. However, further in vitro and in vivo experiments are required to confirm this data in the authentic environment of chondrocytes, the articular cartilage.

Hypoxic expansion promotes the chondrogenic potential of articular chondrocytes

For cell-based cartilage repair strategies, an ex vivo expansion phase is required to obtain sufficient numbers of cells needed for therapy. Although recent reports demonstrated the central role of oxygen for the function and differentiation of chondrocytes, a beneficial effect of low oxygen concentrations during the expansion of the cells to further improve their chondrogenic capacity has not been investigated.Therefore, freshly harvested bovine articular chondrocytes were grown in two-dimensional monolayer cultures at 1.5% and 21% O2 and redifferentiation was subsequently induced in three-dimensional micromass cultures at 1.5%, 5%, and 21% O2. Cells expanded at 1.5% O2 were characterized by low citrate synthase (aerobic energy metabolism)--and high LDH (anaerobic energy metabolism-activities,suggesting an anaerobic energy metabolism. Collagen type II mRNA was twofold higher in cells expanded at 1.5% as compared to expansion at 21% O2. Micromass cultures grown at 21% O2 showed up to a twofold increase in the tissue content of glycosaminoglycans when formed with cells expanded at 1.5% instead of 21% O2. However, no differences in the levels of transcripts and in the staining for collagen type II protein were observed in these micromass cultures. Hypoxia (1.5% and 5% O2) applied during micromass cultures gave rise to tissues with low contents of glycosaminoglycans only. In vivo, the chondrocytes are adapted to a hypoxic environment. Taking this into account, by applying 1.5% O2 in the expansion phase in the course of cell-based cartilage repair strategies, may result in a repair tissue with higher quality by increasing the content of glycosaminoglycans.

Hypovolemia contributes to the pathogenesis of orthostatic hypotension in patients with diabetes mellitus

PURPOSE: To investigate whether body sodium content and blood volume contribute to the pathogenesis of orthostatic hypotension in patients with diabetes mellitus. SUBJECTS AND METHODS: Exchangeable sodium, plasma and blood volumes, and catecholamine, renin, and aldosterone levels were assessed in 10 patients with Type II diabetes mellitus who had orthostatic hypotension and control groups of 40 diabetic patients without orthostatic hypotension and 40 normal subjects of similar age and sex. In subgroups, clinical tests of autonomic function and cardiovascular reactivity to norepinephrine and angiotensin II infusions were performed. RESULTS: In diabetic patients with orthostatic hypotension, mean (+/- SD) supine blood pressure was 165/98 +/- 27/12 mm Hg (P <0.05 compared with other groups) and mean upright blood pressure was 90/60 +/- 38/18 mm Hg. Compared with controls, diabetic patients with orthostatic hypotension had a 10% lower blood volume. They also had less exchangeable sodium than patients with diabetes who did not have orthostatic hypotension (P <0.01). Compared with both groups of controls, diabetic patients with orthostatic hypotension had decreased 24-hour urinary norepinephrine excretion and a reduced diastolic blood pressure response to handgrip (P <0.05). Moreover, they displayed reduced products of exchangeable sodium or blood volume and sympathetic function indexes. Cardiovascular pressor reactivity to norepinephrine was enhanced (P <0.01) and beat-to-beat variation decreased (P <0.01) in both groups of diabetic patients. Microvascular complications were more prevalent in the diabetic patients with orthostatic hypotension (90% vs 35%). CONCLUSIONS: Patients who have Type II diabetes mellitus and orthostatic hypotension are hypovolemic and have sympathoadrenal insufficiency; both factors contribute to the pathogenesis of orthostatic hypotension.

Three-dimensional consensus structure of sst2-selective somatostatin (SRIF) antagonists by NMR

The three-dimensional NMR structures of seven octapeptide analogs of somatostatin (SRIF), based on octreotide, with the basic sequence H-Cpa/Phe2-c[DCys3-Xxx7-DTrp/DAph(Cbm)8-Lys9-Thr10-Cys14]-Yyy-NH2 (the numbering refers to the position in native SRIF), with Xxx7 being Aph(Cbm)/Tyr/Agl(NMe,benzoyl) and Yyy being Nal/DTyr/Thr, are presented here. Most of these analogs exhibit potent and highly selective binding to sst2 receptors, and all of the analogs are antagonists inhibiting receptor signaling. Based on their consensus 3D structure, the pharmacophore of the sst2-selective antagonist has been defined. The pharmacophore involves the side chains of Cpa2, DTrp/DAph(Cbm)8, and Lys9, with the backbone for most of the sst2-selective antagonists comprised a Type-II' beta-turn. Hence, the sst2-selective antagonist pharmacophore is very similar to the sst2-selective agonist pharmacophore previously described.

Immunophenotypic changes of human articular chondrocytes during monolayer culture reflect bona fide dedifferentiation rather than amplification of progenitor cells

In this study, a time-course comparison of human articular chondrocytes (HAC) and bone marrow-derived mesenchymal stem cells (MSC) immunophenotype was performed in order to determine similarities/differences between both cell types during monolayer culture, and to identify HAC surface markers indicative of dedifferentiation. Our results show that dedifferentiated HAC can be distinguished from MSC by combining CD14, CD90, and CD105 expression, with dedifferentiated HAC being CD14+/CD90bright/CD105dim and MSC being CD14-/CD90dim/CD105bright. Surface markers on MSC showed little variation during the culture, whereas HAC showed upregulation of CD90, CD166, CD49c, CD44, CD10, CD26, CD49e, CD151, CD51/61, and CD81, and downregulation of CD49a, CD54, and CD14. Thus, dedifferentiated HAC appear as a bona fide cell population rather than a small population of MSC amplified during monolayer culture. While most of the HAC surface markers showed major changes at the beginning of the culture period (Passage 1-2), CD26 was upregulated and CD49a downregulated at later stages of the culture (Passage 3-4). To correlate changes in HAC surface markers with changes in extracellular matrix gene expression during monolayer culture, CD14 and CD90 mRNA levels were combined into a new differentiation index and compared with the established differentiation indices based on the ratios of mRNA levels of collagen type II to I (COL2/COL1) and of aggrecan to versican (AGG/VER). A correlation of CD14/CD90 ratio at the mRNA and protein level with the AGG/VER ratio during HAC dedifferentiation in monolayer culture validated CD14/CD90 as a new membrane and mRNA based HAC differentiation index.

P450 oxidoreductase deficiency - a new form of congenital adrenal hyperplasia

Patients with adrenal insufficiency, genital anomalies and bony malformations resembling the Antley- Bixler syndrome (a craniosynostosis syndrome), are likely to have P450 oxidoreductase (POR) deficiency. Since our first report in 2004, about 26 recessive POR mutations have been identified in 50 patients. POR is the obligate electron donor to all microsomal (type II) P450 enzymes, including the steroidogenic enzymes CYP17A1, CYP21A2 and CYP19A1. POR deficiency may cause disordered sexual development manifested as genital undervirilization in 46,XY newborns as well as overvirilization in those who are 46,XX. This may be explained by impaired aromatization of fetal androgens which may also lead to maternal virilization and low urinary estriol levels during pregnancy. A role for the alternate 'backdoor' pathway of androgen biosynthesis, leading to dihydrotestosterone production bypassing androstenedione and testosterone, has been suggested in POR deficiency but remains unclear. POR variants may play an important role in drug metabolism, as most drugs are metabolized by hepatic microsomal P450 enzymes. However, functional assays studying the effects of specific POR mutations on steroidogenesis showed that several POR variants impaired CYP17A1, CYP21A2 and CYP19A1 activities to different degrees, indicating that each POR variant must be studied separately for each potential target P450 enzyme. Thus, the impact of POR mutations on drug metabolism by hepatic P450s requires further investigation.

Limited open reduction and internal fixation of displaced intra-articular fractures of the calcaneum

The extended lateral L-shaped approach for the treatment of displaced intra-articular fractures of the calcaneum may be complicated by wound infection, haematoma, dehiscence and injury to the sural nerve. In an effort to reduce the risk of problems with wound healing a technique was developed that combined open reduction and fixation of the joint fragments and of the anterior process with percutaneous reduction and screw fixation of the tuberosity. A group of 24 patients with unilateral isolated closed Sanders type II and III fractures was treated using this technique and compared to a similar group of 26 patients managed by the extended approach and lateral plating. The operation was significantly shorter (p < 0.001) in the first group, but more minor secondary procedures and removal of heel screws were necessary. There were no wound complications in this group, whereas four minor complications occurred in the second group. The accuracy and maintenance of reduction, and ultimate function were equivalent.

[Follow-up after malignant tumours of the uterus (cancer of the uterine corpus / cervical cancer)]

Malignant uterine tumours can affect the corpus or the cervix. The endometrial carcinoma with its different histological subtypes counts for most of the malignomas of the uterine body. But the rare category of uterine sarcomas (carcinosarcomas, leiomyosarcomas as well as endometrial stromal sarcomas) also belongs to this group. Cervical cancer presents an own entitity, regarding both histology and therapeutic options. Endometrial cancer is the most common genital malignoma in Northern Europe and North America. Histologically, the endometrial cancer can be subdivided in two groups: type I is hormonal sensitive and well differentiated, type II represents an undifferenciated aggressive tumour with poor prognosis. In general, the patient is elderly. Due to the main symptom - abnormal vaginal bleeding - endometrial cancer is detected in an early stage in about 75% of all patients. First choice in therapy is stage related surgery. Follow-up schemes have not proved yet to improve survival, therefore clear guidelines are missing. National and international groups recommend regular follow-up visits to detect the early vaginal vault relapse which is curable. Cervical cancer is mainly a squamous cell carcinoma and oncogenic Human Papilloma Virus (HPV) associated. Surgery is only indicated up to stage IIA, advanced stages should be treated by radio-chemotherapy. Several studies have shown that follow-up visits can improve survival rates. Intention is the detection of the curable local relapse.

Prospective, intraindividual comparison of MRI versus MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms

This study compares MRI and MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms (EVAR). Forty-three patients with previous EVAR underwent both MRI (2D T1-FFE unenhanced and contrast-enhanced; 3D triphasic contrast-enhanced) and 16-slice MDCT (unenhanced and biphasic contrast-enhanced) within 1 week of each other for endoleak detection. MRI was performed by using a high-relaxivity contrast medium (gadobenate dimeglumine, MultiHance). Two blinded, independent observers evaluated MRI and MDCT separately. Consensus reading of MRI and MDCT studies was defined as reference standard. Sensitivity, specificity, and accuracy were calculated and Cohen's k statistics were used to estimate agreement between readers. Twenty endoleaks were detected in 18 patients at consensus reading (12 type II and 8 indeterminate endoleaks). Sensitivity, specificity, and accuracy for endoleak detection were 100%, 92%, and 96%, respectively, for reader 1 (95%, 81%, 87% for reader 2) for MRI and 55%, 100%, and 80% for reader 1 (60%, 100%, 82% for reader 2) for MDCT. Interobserver agreement was excellent for MDCT (k = 0.96) and good for MRI (k = 0.81). MRI with the use of a high-relaxivity contrast agent is significantly superior in the detection of endoleaks after EVAR compared with MDCT. MRI may therefore become the preferred technique for patient follow-up after EVAR.

Effect of reduced oxygen tension and long-term mechanical stimulation on chondrocyte-polymer constructs

We have investigated the influence of long-term confined dynamic compression and surface motion under low oxygen tension on tissue-engineered cell-scaffold constructs. Porous polyurethane scaffolds (8 mm x 4 mm) were seeded with bovine articular chondrocytes and cultured under normoxic (21% O(2)) or hypoxic (5% O(2)) conditions for up to 4 weeks. By means of our joint-simulating bioreactor, cyclic axial compression (10-20%; 0.5 Hz) was applied for 1 h daily with a ceramic ball, which simultaneously oscillated over the construct surface (+/-25 degrees; 0.5 Hz). Culture under reduced oxygen tension resulted in an increase in mRNA levels of type II collagen and aggrecan, whereas the expression of type I collagen was down-regulated at early time points. A higher glycosaminoglycan content was found in hypoxic than in normoxic constructs. Immunohistochemical analysis showed more intense type II and weaker type I collagen staining in hypoxic than in normoxic cultures. Type II collagen gene expression was slightly elevated after short-term loading, whereas aggrecan mRNA levels were not influenced by the applied mechanical stimuli. Of importance, the combination of loading and low oxygen tension resulted in a further down-regulation of collagen type I mRNA expression, contributing to the stabilization of the chondrocytic phenotype. Histological results confirmed the beneficial effect of mechanical loading on chondrocyte matrix synthesis. Thus, mechanical stimulation combined with low oxygen tension is an effective tool for modulating the chondrocytic phenotype and should be considered when chondrocytes or mesenchymal stem cells are cultured and differentiated with the aim of generating cartilage-like tissue in vitro.