Mindfulness-based stress reduction adapted to pregnant women with psychosocial vulnerabilities-a protocol for a randomized feasibility study in a Danish hospital-based outpatient setting.

BACKGROUND: This protocol is for a feasibility study of a mindfulness-based stress reduction (MBSR) program adapted for pregnant women with psychosocial vulnerabilities. The rationale for the study is the need for a wider array of evidence-based options to address prenatal mental health care needs in pregnant women. MBSR is a promising mental health intervention but has not yet been adapted for pregnant women with the aim of addressing prenatal mental health. The purpose is thus to evaluate the feasibility, acceptability, and clinical outcomes of an adapted MBSR program, prenatal MBSR, compared to usual care to inform a randomized controlled trial. METHODS/DESIGN: Pregnant women (n = 60) referred to an outpatient clinic at Copenhagen University Hospital, Amager and Hvidovre, Denmark, will be recruited for the study. The design is a single-center feasibility trial, with prenatal MBSR, as an add-on to usual care. The primary outcome is to assess the feasibility of a full-scale randomized controlled trial. The secondary feasibility outcome includes possible effects of the adapted MBSR program estimated by self-report questionnaires measuring stress, anxiety, depression, well-being, decentering, reflective functioning, mindfulness, and compassion. Participants will be randomized in a 1:1 ratio to prenatal MBSR or usual care. DISCUSSION: The study is part of the Good Start to Family Life study anchored at Copenhagen University Hospital, Amager and Hvidovre, Denmark. Teaching the skills of mindfulness meditation to a psychosocially vulnerable group of pregnant women could prove a viable and non-pharmacological approach to reduce stress, improve mental health, and provide support in the transition to parenthood. The outcomes of the feasibility study will inform the design of a fully powered randomized controlled trial. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04571190 . Registered on September 30, 2020.

Differentiated activities of decorin and biglycan in the progression of post-traumatic osteoarthritis.

OBJECTIVE: To delineate the activities of decorin and biglycan in the progression of post-traumatic osteoarthritis (PTOA). DESIGN: Three-month-old inducible biglycan (BgniKO) and decorin/biglycan compound (Dcn/BgniKO) knockout mice were subjected to the destabilization of the medial meniscus (DMM) surgery to induce PTOA. The OA phenotype was evaluated by assessing joint structure and sulfated glycosaminoglycan (sGAG) staining via histology, surface collagen fibril nanostructure and calcium content via scanning electron microscopy, tissue modulus via atomic force microscopy-nanoindentation, as well as subchondral bone structure and meniscus ossification via micro-computed tomography. Outcomes were compared with previous findings in the inducible decorin (DcniKO) knockout mice. RESULTS: In the DMM model, BgniKO mice developed similar degree of OA as the control (0.44 [-0.18 1.05] difference in modified Mankin score), different from the more severe OA phenotype observed in DcniKO mice (1.38 [0.91 1.85] difference). Dcn/BgniKO mice exhibited similar histological OA phenotype as DcniKO mice (1.51 [0.97 2.04] difference vs control), including aggravated loss of sGAGs, salient surface fibrillation and formation of osteophyte. Meanwhile, Dcn/BgniKO mice showed further cartilage thinning than DcniKO mice, resulting in the exposure of underlying calcified tissues and aberrantly high surface modulus. BgniKO and Dcn/BgniKO mice developed altered subchondral trabecular bone structure in both Sham and DMM groups, while DcniKO and control mice did not. CONCLUSION: In PTOA, decorin plays a more crucial role than biglycan in regulating cartilage degeneration, while biglycan is more important in regulating subchondral bone structure. The two have distinct activities and modest synergy in the pathogenesis of PTOA.

Training in Bariatric Surgery: a National Survey of German Bariatric Surgeons.

INTRODUCTION: Skill in bariatric surgery has been associated with postoperative outcome. Appropriate surgical training is of paramount importance. In order to continuously improve training strategies, it is necessary to assess current practices. AIM: To determine how German bariatric surgeons have been trained and to assess current training strategies. METHODS: Between February 2017 and March 2017, an online census of surgeons registered as members of the German Society for Bariatric and Metabolic Surgery was conducted. A total of three reminders were sent out. Data were analyzed using descriptive statistics. Data was reported as median (interquartile range); percentages were adjusted for completed answers only. RESULTS: A response rate of 51% (n = 214) was achieved. Surgeons reported a median of 14.5 (8-20) years of surgical experience after initial training, with a specific bariatric experience of 7 (4-13) years. The total cumulative bariatric case volume was 240 (80-500) cases, with an annual case volume of 50 (25-80). The most commonly applied approaches to bariatric skills acquisition were "learning by doing" (71%), "course participation" (70%) and "observerships" (70%). Fellowships and the use of operating videos were less frequently applied strategies (19%/ 47%). Interestingly, observerships (94%) and course participation (89%) were rated as very important/important, whereas "learning by doing" (62%), watching operation videos (59%), and fellowships (48%) were less frequently perceived as important/very important training strategies. CONCLUSIONS: The majority of surgeons performing bariatric cases were senior surgeons with more than 10 years of post-training experience; nevertheless, the survey revealed a lack of structured approaches to bariatric specialization training.

[Barriers to the German Society for General and Visceral Surgery (DGAV) accreditation "Center for bariatric and metabolic surgery"]. / Barrieren auf dem Weg zur DGAV-Zertifizierung "Zentrum für Adipositas- und metabolische Chirurgie".

INTRODUCTION: The certification and accreditation process of the German Society for General and Visceral Surgery (DGAV) aims to improve the quality of care and enhance transparency in accredited centers. To achieve these goals a high level of infrastructural and staffing requirements are set out by the DGAV. AIMS: The Surgical Working Group on Obesity Treatment and Metabolic Surgery (CAADIP) survey 2017 of the members of the German Bariatric Society aimed to identify the perceived and encountered barriers in the DGAV accreditation process. METHODS: Between February and March 2017 an online poll was conducted of all members of the CAADIP on topics pertaining to the accreditation process. RESULTS: A total of 214 (51%) CAADIP members participated in the poll, 47% reported that they worked at a non-certified center and 53% worked at a DGAV certified center. Of these, 68% reported employment in a unit with the lowest accreditation level, 21% in an intermediate level center, 11% reported employment in a unit with the highest accreditation level (Center of Excellence) and 86% of those currently working in non-accredited units stated that they aimed for future accreditation. Reasons stated for not having obtained accreditation were recent establishment of the new bariatric specialty (54%), lack of bariatric case numbers (71%), lack of human resources and infrastructure (28% and 13%, respectively). Of those surgeons in non-accredited centers 24% stated that the hospital management had no interest in a certification and 12% of the surgeons themselves felt that accreditation was unnecessary. CONCLUSION: The majority of CAADIP members strived for DGAV certification. The main barriers encountered and perceived were the specific time (reference years) and caseload requirements.

Achilles tendons from decorin- and biglycan-null mouse models have inferior mechanical and structural properties predicted by an image-based empirical damage model.

Achilles tendons are a common source of pain and injury, and their pathology may originate from aberrant structure function relationships. Small leucine rich proteoglycans (SLRPs) influence mechanical and structural properties in a tendon-specific manner. However, their roles in the Achilles tendon have not been defined. The objective of this study was to evaluate the mechanical and structural differences observed in mouse Achilles tendons lacking class I SLRPs; either decorin or biglycan. In addition, empirical modeling techniques based on mechanical and image-based measures were employed. Achilles tendons from decorin-null (Dcn(-/-)) and biglycan-null (Bgn(-/-)) C57BL/6 female mice (N=102) were used. Each tendon underwent a dynamic mechanical testing protocol including simultaneous polarized light image capture to evaluate both structural and mechanical properties of each Achilles tendon. An empirical damage model was adapted for application to genetic variation and for use with image based structural properties to predict tendon dynamic mechanical properties. We found that Achilles tendons lacking decorin and biglycan had inferior mechanical and structural properties that were age dependent; and that simple empirical models, based on previously described damage models, were predictive of Achilles tendon dynamic modulus in both decorin- and biglycan-null mice.

Low recurrence rate and low chronic pain associated with inguinal hernia repair by laparoscopic placement of Parietex ProGrip™ mesh: clinical outcomes of 220 hernias with mean follow-up at 23 months.

INTRODUCTION: The aim of this study was to demonstrate the safety and the efficacy of the self-gripping Parietex ProGrip™ mesh (Sofradim Production, Trévoux, France) used with the laparoscopic approach for inguinal hernia repair. The incidence of chronic pain, post-operative complications, patient satisfaction and hernia recurrence at follow-up after 12 months was evaluated. METHODS: Data were collected retrospectively from patient files and were analyzed for 169 male and female patients with 220 primary inguinal hernias. All patients included had undergone surgical repair for inguinal hernia by the laparoscopic transabdominal preperitoneal approach using Parietex ProGrip™ meshes performed in the same clinical center in Germany. Pre-, per- and post-operative data were collected, and a follow-up after 12 months was performed prospectively. Complications, pain scored on a 0-10 numeric rating scale (NRS), patient satisfaction and hernia recurrence were assessed. RESULTS: The only complications were minor and were post-operative: hematoma/seroma (3 cases), secondary hemorrhage through the trocar's site (2 cases), hematuria, emphysema in the inguinal regions (both sides) and swelling above the genital organs (1 case for each). At mean follow-up at 22.8 months, there were only 3 reports of hernia recurrence: 1.4 % of the hernias. Most patients (95.9 %) were satisfied or very satisfied with their hernia repair with only 1.2 % reporting severe pain (NRS score 7-10) and 3.6 % reported mild pain. CONCLUSION: This study demonstrates that in experienced hands, inguinal hernia repair surgery performed by laparoscopic transabdominal preperitoneal hernioplasty using Parietex ProGrip™ self-gripping meshes is rapid, efficient and safe with low pain and low hernia recurrence rate.

Evidence of thromboembolism prophylaxis in bariatric surgery-results of a quality assurance trial in bariatric surgery in Germany from 2005 to 2007 and review of the literature.

BACKGROUND: Since January 1st, 2005, the current situation for bariatric surgery has been examined by means of a voluntary quality assurance study in Germany with a multicenter design in which 38 hospitals and surgical departments participated. The data are registered in cooperation with the Institute of Quality Assurance in Surgery at the Otto-von-Guericke University of Magdeburg (Germany). METHODS: Data describing peri-interventional characteristics were prospectively documented in an internet online data registry. All primary bariatric procedures performed since January 1st, 2005, were registered. In addition, reoperations in patients who had previously undergone primary surgical intervention were included. As a representative excerpt from the overall prospective multicenter observational study on obesity surgery, data on the type, regimen, and time course of deep venous thrombosis (DVT) prophylaxis were documented. From the number and spectrum of complications, the incidences of clinically manifest DVT or pulmonary embolism (PE) were derived during the in-hospital course and follow-up in conjunction with the type of surgical procedure and body mass index (BMI). RESULTS: Overall, 3,122 bariatric procedures were performed at 38 German hospitals between January 2005 and December 2007. These procedures were subdivided into 2,869 primary operations and 253 revisions (sex ratio, male to female = 25.6:74.4%). The average BMI of all patients was 48.5 kg/m(2) in 2005, 48.4 kg/m(2) in 2006, and 48.0 kg/m(2) in 2007. In 2005 and 2006, gastric banding (GB) was the most commonly performed operation, followed by Roux-en-Y gastric bypass (RYGBP). In 2007, RYGBP was carried out in 42.1% of all bariatric procedures. Interestingly, the incidence of deep venous thrombosis (DVT) was only 0.06%, whereas PE occurred in 0.06% of patients only after hospital discharge. The DVT prophylaxis protocol used has been changed for the last 2 years: the majority of patients with a BMI above 50 kg/m(2) received low-molecular-weight heparin twice a day. CONCLUSION: In Germany, a trend from GB to sleeve gastrectomy (SG) and malabsorptive approach has been evaluated. This trend is associated with differences of the DVT prophylaxis regimen in the profile of bariatric surgical patients depending on BMI and the type of bariatric procedure. Despite the low incidence of DVT and pulmonary embolism (PE) detected, there is a lack of evidence on a reasonable regimen for sufficient DVT prophylaxis in bariatric surgery; instead, there are only recommendations from the guidelines and statements of a specific medical society. Therefore, prospective studies are necessary to determine the optimal DVT prophylaxis for bariatric surgical patients as well as obese patients undergoing surgery.

Results of sleeve gastrectomy-data from a nationwide survey on bariatric surgery in Germany.

BACKGROUND: Beginning January 1, 2005, the status and outcomes of bariatric surgery were examined in Germany. Data are registered in cooperation with the An-Institute of quality assurance in surgery at the Otto-von-Guericke-University Magdeburg. The objective of this study was to examine the morbidity and mortality rates secondary to sleeve gastrectomy (SG) in Germany since 2006. METHODS: Data collection occurred prospectively in an online data bank. All primary bariatric procedures performed were recorded as were all re-operations in patients that had already undergone a primary operation. Specific data compiled on the sleeve gastrectomy procedure were evaluated with a focus on operative details and complication rates. RESULTS: The total study cohort contains 3,122 patients. From January 2006 to December 2007, 144 sleeve gastrectomy procedures were performed in the 17 hospitals participating in the study. The mean body mass index (BMI) of all patients was 48.8 kg/m(2). The BMI of patients undergoing SG was 54.5 kg/m(2). In total, 73.8% of the patients were female and 26.2% of the patients were male. There were no significant differences between patients undergoing SG. The general complication rate after SG was 14.1%, and the surgical complication rate was 9.4%. The postoperative mortality rate was 1.4%. CONCLUSIONS: The complication rate during the first 2 years after SG in Germany is similar to that published in the literature. In order to improve the quality of bariatric surgery, an evaluation of data from a German multicenter trial is necessary to evaluate the position of SG in the bariatric algorithm.

A nationwide survey on bariatric surgery in Germany--results 2005-2007.

BACKGROUND: Most studies on bariatric surgery outcomes are performed as clinical trials or reflect the clinical experience in single centers. The status of bariatric surgery in Germany has been examined since January 1st, 2005 with the cooperation of clinics and hospitals at the Institute of Quality Assurance in Surgery at the Otto-von-Guericke University of Magdeburg (Germany). METHODS: In this prospective multicenter observational study, the data obtained for all primary bariatric procedures, including all repeated operations, performed on consecutive patients with morbid obesity at participating hospitals from 2005 to 2007 were prospectively collected using an Internet online data registry. In particular, perioperative characteristics, such as the spectrum of diagnostic measurements, type of surgical procedures, and short- and long-term outcomes, were investigated. RESULTS: During the study period, 629 surgical procedures were performed at 21 hospitals in 2005, 828 procedures at 32 hospitals in 2006, and 1,666 procedures at 35 hospitals in 2007. In 2005 and 2006, gastric banding was the most frequently performed operation, followed by the Roux-en-Y gastric bypass (RYGBP). In 2007, a RYGBP was carried out in 42.1% of all bariatric procedures. Among all patients, 74.4% were female. The mean body mass index (BMI) was 48.5 kg/m(2) in 2005, 48.4 kg/m(2) in 2006, and 48.0 kg/m(2) in 2007. Follow-up data after 12 months were available for 63.8% of the patients in 2005 and 2006; these data showed greater reduction of BMI after malabsorptive rather than restrictive bariatric procedures. The mortality was 0.1% (30 days) and 0.16% (overall). CONCLUSION: As indicated by the worldwide trend, there is an ongoing change from restrictive bariatric procedures to malabsorptive procedures and sleeve gastrectomy. Although the BMIs of German patients undergoing bariatric surgery appear to be substantially higher than those of patients from most other countries, there were no differences in intraoperative and short-term complications or in overall outcomes during follow-up when compared with published studies.

[Quality assurance in bariatric surgery in Germany--results of the German multicentre trial 2005 and 2006]. / Studie zur Qualitätskontrolle der operativen Therapie der Adipositas--Ergebnisse der Jahre 2005 und 2006.

BACKGROUND: Since January 1st 2005, the situation of bariatric surgery in Germany has been examined. The data are registered in cooperation with the Institute of Quality Assurance in Surgery at the Otto-von-Guericke-University Magdeburg. METHODS: The data registration took place prospectively in an internet online data base. All primary bariatric procedures performed since January 1st 2005 were detected as well as re-operations in patients who had been operated before. RESULTS: 629 patients underwent bariatric surgery in 21 hospitals in 2005 and 828 patients were operated in 32 hospitals in 2006. The mostly performed operation was gastric banding with 46.8 %, followed by Roux-Y gastric bypass with 38.5 %. 74.4 % of the patients were female. The medium BMI of all patients was 48.5 kg/m2 in 2005 and 48.4 kg/m2 in 2006. Follow-up data were available for 71.2 % of the patients operated in 2005. These data show a higher reduction of BMI after malabsorptive than after restrictive bariatric procedures. CONCLUSION: A trend from restrictive bariatric procedures to a malabsorptive approach could be observed. In Germany the BMI of patients undergoing bariatric surgery is higher than in most countries world-wide. No differences could be detected in intraoperative and short-term complications as well in the complication rate in the first year of follow-up in comparison with the literature.

Development of tendon structure and function: regulation of collagen fibrillogenesis.

In the tendon, the development of mature mechanical properties is dependent on the assembly of a tendon-specific extracellular matrix. This matrix is synthesized by the tendon fibroblasts and composed of collagen fibrils organized as fibers, as well as fibril-associated collagenous and non-collagenous proteins. All of these components are integrated, during development and growth, to form a functional tissue. During tendon development, collagen fibrillogenesis and matrix assembly progress through multiple steps where each step is regulated independently, culminating in a structurally and functionally mature tissue. Collagen fibrillogenesis occurs in a series of extracellular compartments where fibril intermediates are assembled and mature fibrils grow through a process of post-depositional fusion of the intermediates. Linear and lateral fibril growth occurs after the immature fibril intermediates are incorporated into fibers. The processes are regulated by interactions of extracellular macromolecules with the fibrils. Interactions with quantitatively minor fibrillar collagens, fibril-associated collagens and proteoglycans influence different steps in fibrillogenesis and the extracellular microdomains provide a mechanism for the tendon fibroblasts to regulate these extracellular interactions.

Intrinsic aging vs. photoaging: a comparative histopathological, immunohistochemical, and ultrastructural study of skin.

Cutaneous aging is a complex biological phenomenon affecting the different constituents of the skin. To compare the effects of intrinsic and extrinsic aging processes, a total of 83 biopsies were collected from sun-exposed and protected skin of healthy volunteers representing decades from the 1st to the 9th (6-84 years of age). Routine histopathology coupled with computer-assisted image analysis was used to assess epidermal changes. Immunoperoxidase techniques with antibodies against type I and type III collagens and elastin were used to quantitatively evaluate changes in collagen and elastic fibers and their ultrastructure was examined by transmission electron microscopy. Epidermal thickness was found to be constant in different decades in both sun-exposed and protected skin; however, it was significantly greater in sun-exposed skin (P = 0.0001). In protected skin, type I and III collagen staining was altered only after the 8th decade, while in sun-exposed skin the relative staining intensity significantly decreased from 82.5% and 80.4% in the 1st decade to 53.2% and 44.1% in the 9th decade, respectively (P = 0.0004 and 0.0008). In facial skin the collagen fiber architecture appeared disorganized after the 4th decade. The staining intensity of elastin in protected skin significantly decreased from 49.2% in the 1st decade to 30.4% in the 9th decade (P = 0.05), whereas in sun-exposed skin the intensity gradually increased from 56.5% in the 1st decade to 75.2% in the 9th decade (P = 0.001). The accumulated elastin in facial skin was morphologically abnormal and appeared to occupy the areas of lost collagen. Collectively, the aging processes, whether intrinsic or extrinsic, have both quantitative and qualitative effects on collagen and elastic fibers in the skin.

Ki-67 immunostaining in pancreatic cancer and chronic active pancreatitis: does in vivo FDG uptake correlate with proliferative activity?

UNLABELLED: PET with 18F-FDG has been shown to be useful in the detection and staging of pancreatic cancer. However, whether FDG uptake is dependent on proliferative activity is still unclear. The aim of this prospective study was to evaluate a probable correlation between FDG uptake and proliferative activity in benign and malignant pancreatic tumors. METHODS: Our series consisted of 23 patients with pancreatic cancer and 9 patients with chronic active pancreatitis (CAP). FDG PET was performed within 2 wk before surgery, and standardized uptake values (SUVs) were calculated for benign and malignant pancreatic tumors. Patients were selected when focally increased FDG uptake in previously known pancreatic tumors was present. Proliferation fraction was measured in tissue specimens using the anti-Ki-67 antibody MIB-1. A computer-assisted imaging system was used for quantification of nuclear Ki-67 immunostaining. Immunohistochemical findings were correlated to SUVS: RESULTS: Pancreatic cancer showed both intense nuclear staining of Ki-67 (39% +/- 16%) and high FDG uptake (SUV = 3.6 +/- 1.6). However, no significant correlation was found between in vivo FDG uptake and Ki-67 immunoreactivity (P = 0.65). By contrast, Ki-67 nuclear staining was significantly lower (3.8% +/- 2.7%, P < 0.05) in CAP, whereas FDG uptake was in the same range as for pancreatic cancer (SUV = 3.5 +/- 1.8). CONCLUSION: FDG uptake did not correlate with proliferative activity in pancreatic cancer. Proliferative activity was tenfold higher in malignant pancreatic tumors than in benign tumors associated with CAP, whereas FDG uptake in vivo did not differ significantly. Thus, a PET tracer indicating cellular proliferation should better differentiate between cancer and inflammatory lesions than do metabolic markers such as FDG.

Type IIA procollagen: expression in developing chicken limb cartilage and human osteoarthritic articular cartilage.

Type IIA procollagen is an alternatively spliced product of the type II collagen gene and uniquely contains the cysteine (cys)-rich globular domain in its amino (N)-propeptide. To understand the function of type IIA procollagen in cartilage development under normal and pathologic conditions, the detailed expression pattern of type IIA procollagen was determined in progressive stages of development in embryonic chicken limb cartilages (days 5-19) and in human adult articular cartilage. Utilizing the antibodies specific for the cys-rich domain of the type IIA procollagen N-propeptide, we localized type IIA procollagen in the pericellular and interterritorial matrix of condensing pre-chondrogenic mesenchyme (day 5) and early cartilage (days 7-9). The intensity of immunostaining was gradually lost with cartilage development, and staining became restricted to the inner layer of perichondrium and the articular cap (day 12). Later in development, type IIA procollagen was re-expressed at the onset of cartilage hypertrophy (day 19). Different from type X collagen, which is expressed throughout hypertrophic cartilage, type IIA procollagen expression was transient and restricted to the zone of early hypertrophy. Immunoelectron microscopic and immunoblot analyses showed that a significant amount of the type IIA procollagen N-propeptide, but not the carboxyl (C)-propeptide, was retained in matrix collagen fibrils of embryonic limb cartilage. This suggests that the type IIA procollagen N-propeptide plays previously unrecognized roles in fibrillogenesis and chondrogenesis. We did not detect type IIA procollagen in healthy human adult articular cartilage. Expression of type IIA procollagen, together with that of type X collagen, was activated by articular chondrocytes in the upper zone of moderately and severely affected human osteoarthritic cartilage, suggesting that articular chondrocytes, which normally maintain a stable phenotype, undergo hypertrophic changes in osteoarthritic cartilage. Based on our data, we propose that type IIA procollagen plays a significant role in chondrocyte differentiation and hypertrophy during normal cartilage development as well as in the pathogenesis of osteoarthritis.

Neoadjuvant, adjuvant, and palliative treatment of pancreatic cancer.

Pancreatic cancer remains a highly malignant disease. Curative treatment is only possible for patients diagnosed at a very early stage. Therefore, the vast majority of pancreatic cancer patients receive palliative treatment. Surgical palliation is offered to patients who are found not to have a resectable tumor. The treatment of obstructive jaundice is managed by stenting of the common bile duct or by a surgical bypass. The best possible surgical procedure should be based on the factors that influence hospital mortality, length of survival, and quality of life. In patients with a life expectancy of longer than 3 months, surgical bypass is recommended, with hepaticojejunostomy the treatment of choice. In the same surgical procedure, the relief of duodenal obstruction with a gastroenteric bypass should be achieved. Chemotherapy, radiotherapy, or a combination of both is employed as a neoadjuvant measure, as an adjuvant treatment, or, in most patients, as palliation. As palliative chemotherapy alone, 5-fluorouracil (5-FU) plus folinic acid is still the treatment of choice; however, newer drugs, such as gemcitabine, seem to have similar or marginally better results. Palliative radiochemotherapy with external-beam radiation plus 5-FU and folinic acid seems to lead to better local control of tumor progression but not to better survival, for which distant metastases are the limiting factor.

Production of human type I collagen in yeast reveals unexpected new insights into the molecular assembly of collagen trimers.

Substantial evidence supports the role of the procollagen C-propeptide in the initial association of procollagen polypeptides and for triple helix formation. To evaluate the role of the propeptide domains on triple helix formation, human recombinant type I procollagen, pN-collagen (procollagen without the C-propeptides), pC-collagen (procollagen without the N-propeptides), and collagen (minus both propeptide domains) heterotrimers were expressed in Saccharomyces cerevisiae. Deletion of the N- or C-propeptide, or both propeptide domains, from both proalpha-chains resulted in correctly aligned triple helical type I collagen. Protease digestion assays demonstrated folding of the triple helix in the absence of the N- and C-propeptides from both proalpha-chains. This result suggests that sequences required for folding of the triple helix are located in the helical/telopeptide domains of the collagen molecule. Using a strain that does not contain prolyl hydroxylase, the same folding mechanism was shown to be operative in the absence of prolyl hydroxylase. Normal collagen fibrils were generated showing the characteristic banding pattern using this recombinant collagen. This system offers new opportunities for the study of collagen expression and maturation.

Type V collagen: heterotypic type I/V collagen interactions in the regulation of fibril assembly.

Type V collagen is a quantitatively minor fibrillar collagen with a broad tissue distribution. The most common type V collagen isoform is alpha1(V)(2) alpha2(V) found in cornea. However, other isoforms exist, including an [alpha1(V)alpha2(V)alpha3(V)] form, an alpha1(V)(3) homotrimer and hybrid type V/XI forms. The functional role and fibrillar organization of these isoforms is not understood. In the cornea, type V collagen has a key role in the regulation of initial fibril assembly. Type I and type V collagen co-assemble into heterotypic fibrils. The entire triple-helical domain of the type V collagen molecules is buried within the fibril and type I collagen molecules are present along the fibril surface. The retained NH(2)-terminal domains of the type V collagen are exposed at the surface, extending outward through the gap zones. The molecular model of the NH(2)-terminal domain indicates that the short alpha helical region is a flexible hinge-like region allowing the peptide to project away from the major axis of the molecule; the short triple-helical regions serve as an extension through the hole zone, placing the tyrosine-rich domain at the surface. The assembly of early, immature fibril intermediates (segments) is regulated by the NH(2)-terminal domain of type V collagen. These NH(2)-terminal domains alter accretion of collagen molecules onto fibrils and therefore lateral growth. A critical density would favor the initiation of new fibrils rather than the continued growth of existing fibrils. Other type V collagen isoforms are likely to have an important role in non-cornea tissues. This role may be mediated by supramolecular aggregates different from those in the corneal stroma or by an alteration of the interactions mediated by tissue-specific type V collagen domains generated by different isoforms or aggregate structures. Presumably, the aggregate structure or specific domains are involved in the regionalization of fibril-associated macromolecules necessary for the tissue-specific regulation of later fibril growth and matrix assembly stages.

Differential expression of lumican and fibromodulin regulate collagen fibrillogenesis in developing mouse tendons.

Collagen fibrillogenesis is finely regulated during development of tissue-specific extracellular matrices. The role(s) of a leucine-rich repeat protein subfamily in the regulation of fibrillogenesis during tendon development were defined. Lumican-, fibromodulin-, and double-deficient mice demonstrated disruptions in fibrillogenesis. With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process. Electron microscopic analysis demonstrated structural abnormalities in the fibrils and alterations in the progression through different assembly steps. In lumican-deficient tendons, alterations were observed early and the mature tendon was nearly normal. Fibromodulin-deficient tendons were comparable with the lumican-null in early developmental periods and acquired a severe phenotype by maturation. The double-deficient mice had a phenotype that was additive early and comparable with the fibromodulin-deficient mice at maturation. Therefore, lumican and fibromodulin both influence initial assembly of intermediates and the entry into fibril growth, while fibromodulin facilitates the progression through growth steps leading to mature fibrils. The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions. These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.

Type V collagen regulates the assembly of collagen fibrils in cultures of bovine vascular smooth muscle cells.

Vascular smooth muscle cells (SMCs), the major cellular constituent of the medial layer of an artery, synthesize the majority of connective tissue proteins, including fibrillar collagen types I, III, and V/XI. Proper collagen synthesis and deposition, which are important for the integrity of the arterial wall, require the antioxidant vitamin C. Vitamin C serves as cofactor for the enzymes prolyl and lysyl hydroxylase, which are responsible for the proper hydroxylation of collagen. Here, the role of type V collagen in the assembly of collagen fibrils in the extracellular matrix (ECM) of cultured vascular SMCs was investigated. Treatment of SMCs with vitamin C resulted in a dramatic induction in the levels of the cell-layer associated pepsin-resistant type V collagen, whereas only a minor induction in the levels of types I and III collagen was detected. Of note, the deposition of type V collagen was accompanied by the formation of striated collagen fibrils in the ECM. Immunohistochemistry demonstrated that type V collagen, but not type I collagen, became masked as collagen fibrils matured. Furthermore, the relative ratio of type V to type I collagen decreased as the ECM matured as a function of days in culture, and this decrease was accompanied by an increase in the diameter of collagen fibrils. Together these results suggest that the masking of type V collagen is caused by its internalization on continuous deposition of type I collagen on the exterior of the fibril. Furthermore, they suggest that type V collagen acts as framework for the initial assembly of collagen molecules into heterotypic fibrils, regulating the diameter and architecture of these fibrils.