Flexible bronchoscopy insufflated and high-flow nasal oxygen pilot trial (BUFFALO protocol pilot trial)

BACKGROUND

Hypoxaemia occurs in approximately 30% of children during anaesthesia for flexible bronchoscopy. High-flow nasal oxygen (HFNO) can prolong safe apnoea time and be used in children with abnormal airways. During flexible bronchoscopy, there is limited evidence if HFNO confers advantages over current standard practice in avoiding hypoxaemia. The aim is to investigate feasibility of HFNO use during anaesthesia for flexible bronchoscopy to reduce frequency of rescue oxygenation and hypoxaemia.

METHODS

BUFFALO is a bi-centre, unmasked, randomised controlled, parallel group, protocol for a pilot trial comparing HFNO techniques to standard practice during anaesthesia. Children (n = 81) aged > 37 weeks to 16 years presenting for elective bronchoscopy who fulfil inclusion but not exclusion criteria will be randomised prior to the procedure to HFNO or standard care oxygenation post induction of anaesthesia. Maintenance of anaesthesia with HFNO requires total venous anaesthesia (TIVA) and with standard, either inhalational or TIVA at discretion of anaesthetist in charge of the patient. Outcomes will include the feasibility of recruitment and adherence to trial procedures, acceptability of the intervention of the protocol and completion rates of data collection methods.

DISCUSSION

Findings of this trial will determine feasibility to plan for a larger multicentre randomised clinical trial and support the feasibility of the proposed study procedures.

TRIAL REGISTRATION

BUFFALO trial was registered with Australia and New Zealand Clinical Trials Registry (TRN12621001635853) on 29 November 2021 and commenced recruitment in May 2022. https://www.anzctr.org.au/ . The primary manuscript will be submitted for publication in a peer-reviewed journal.

Predicting obstructive sleep apnoea and perioperative respiratory adverse events in children: role of upper airway collapsibility measurements

BACKGROUND

Obstructive sleep apnoea (OSA) and perioperative respiratory adverse events are significant risks for anaesthesia in children undergoing adenotonsillectomy. Upper airway collapse is a crucial feature of OSA that contributes to respiratory adverse events. A measure of upper airway collapsibility to identify undiagnosed OSA can help guide perioperative management. We investigated the utility of pharyngeal closing pressure (PCLOSE) for predicting OSA and respiratory adverse events.

METHODS

Children scheduled for elective adenotonsillectomy underwent in-laboratory polysomnography 2-12 weeks before surgery. PCLOSE measurements were obtained while the child was anaesthetised and breathing spontaneously just before surgery. Logistic regression was used to assess the predictive performance of PCLOSE for detecting OSA and perioperative respiratory adverse events after adjusting for potential covariates.

RESULTS

In 52 children (age, mean [standard deviation] 5.7 [1.8] yr; 20 [38%] females), airway collapse during PCLOSE was observed in 42 (81%). Of these, 19 of 42 (45%) patients did not have OSA, 15 (36%) had mild OSA, and eight (19%) had moderate-to-severe OSA. All 10 children with no evidence of airway collapse during the PCLOSE measurements did not have OSA. PCLOSE predicted moderate-to-severe OSA (odds ratio [OR] 1.71; 95% confidence interval [CI]: 1.2-2.8; P=0.011). All children with moderate-to-severe OSA could be identified at a PCLOSE threshold of -4.0 cm H2O (100% sensitivity), and most with no or mild OSA were ruled out (64.7% specificity; receiver operating characteristic/area under the curve=0.857). However, there was no significant association between respiratory adverse events and PCLOSE (OR 1.0; 95% CI: 0.8-1.1; P=0.641).

CONCLUSIONS

Measurement of PCLOSE after induction of anaesthesia can reliably identify moderate or severe OSA but not perioperative respiratory adverse events in children before adenotonsillectomy.

CLINICAL TRIAL REGISTRATION

ANZCTR ACTRN 12617001503314.

A review of pediatric fasting guidelines and strategies to help children manage preoperative fasting

Fasting for surgery is a routine step in the preoperative preparation for surgery. There have however been increasing concerns with regard to the high incidence of prolonged fasting in children, and the subsequent psycho-social distress and physiological consequences that this poses. Additionally, the past few years have yielded new research that has shown significant inter-individual variation in gastric emptying regardless of the length of the fast, with some patients still having residual gastric contents even after prolonged fasts. Additionally, multiple large-scale studies have shown no long-term sequalae from clear fluid aspiration, although two deaths from aspiration have been reported within the large Wake Up Safe cohort. This has led to a change in the recommended clear fluid fasting times in multiple international pediatric societies; similarly, many societies continue to recommend traditional fasting times. Multiple fasting strategies exist in the literature, though these have mostly been studied and implemented in the adult population. This review hopes to summarize the recent updates in fasting guidelines, discuss the issues surrounding prolonged fasting, and explore potential tolerance strategies for children.

Congenital subglottic cyst: a rare cause for sudden airway compromise in a newborn

A full-term infant developed stridor, respiratory distress and hypercarbia shortly after birth requiring urgent airway intervention. The patient underwent urgent intubation via rigid bronchoscopy. The diagnosis of congenital subglottic cyst was made. The cyst was decompressed and the patient was extubated the following day. On repeat laryngoscopy 1 month later, there was no residual disease and the patient remained symptom free. Congenital subglottic cysts are extremely rare and the diagnosis can be either missed or misdiagnosed with more common causes of stridor, such as laryngomalacia. Subglottic cysts may cause total airway obstruction and even death if they are large enough and not treated immediately.

Is there a role for lung-protective ventilation in healthy children?

Lung-protective ventilation (LPV) has been adopted in the theater environment as a strategy to reduce pulmonary complications under anesthesia. Postoperative pulmonary complications are not infrequent and may have significant implications on the postoperative length of stay as well as the morbidity and mortality of pediatric patients. There is evidence in the adult literature to suggest that intraoperative LPV strategies may reduce the risk of such complications. The utility of LPV strategies in healthy children is not well researched, and the data from critical care studies appear to be conflicting. To ascertain the value of intraoperative LPV in pediatric patients, it is important to understand the pathophysiology of pediatric ventilator-induced lung injury and the basis of LPV strategies. The current evidence in adult and pediatric populations, including pediatric intensive care, is reviewed to gain insight into the role and value of intraoperative LPV for pediatric patients.

Preoperative and intraoperative factors predictive of complications and stricture recurrence following multiple urethroplasty techniques

Objectives

To investigate factors predictive of postoperative recurrence and complications in patients undergoing urethroplasty for stricture repair at a single center.

Patients and methods

We retrospectively reviewed the records of 108 men who underwent urethroplasty for urethral stricture disease (USD) at a single center from 2016 to 2020. Demographic data, comorbidities, stricture history including etiology and prior treatments, patient‐reported symptoms, and outcomes data were collected for analysis. Data were analyzed in aggregate, then, stratified by type of urethroplasty performed. Descriptive statistics, univariate analysis, multivariate logistic regression, and intergroup comparisons were completed using STATA, with an alpha value of 0.05 and a confidence interval of 95%.

Results

The median age of our patients was 58 years (interquartile range: 42‐69; range: 29‐83), with a median stricture length of 2.0 cm (interquartile range: 1.0‐4.5; range: 0.5‐10). The most common stricture etiology was iatrogenic (n = 33, 31%) and the most common urethroplasty was anterior anastomotic urethroplasty (n = 38, 35%), followed by buccal mucosal graft (BMG) urethroplasty (n = 35, 32%). Twenty‐four patients (22%) had stricture recurrence. Within the aggregate data, recurrence was significantly predicted by obesity (BMI > 30) (Odds Ratio [OR] 3.2, 95% Confidence Interval [CI]: 1.06‐10), and the presence of postoperative complications (OR 6.3, CI: 1.9‐21). The presence of any postoperative complications within 90 days was significantly predicted by stricture length ≥ 5 cm (OR 3.5, CI 1.09‐12) and recurrence (OR 6.0, CI 1.7‐21).

Conclusion

Despite serving as the most definitive treatment for urethral stricture management, stricture recurrence and postoperative complications are not uncommon after urethroplasty. Obesity and stricture length negatively impact outcomes while a penile stricture location is associated with a lower recurrence rate, though this is not statistically significant.

TBX6 null variants and a common hypomorphic allele in congenital scoliosis

BACKGROUND

Congenital scoliosis is a common type of vertebral malformation. Genetic susceptibility has been implicated in congenital scoliosis.

METHODS

We evaluated 161 Han Chinese persons with sporadic congenital scoliosis, 166 Han Chinese controls, and 2 pedigrees, family members of which had a 16p11.2 deletion, using comparative genomic hybridization, quantitative polymerase-chain-reaction analysis, and DNA sequencing. We carried out tests of replication using an additional series of 76 Han Chinese persons with congenital scoliosis and a multicenter series of 42 persons with 16p11.2 deletions.

RESULTS

We identified a total of 17 heterozygous TBX6 null mutations in the 161 persons with sporadic congenital scoliosis (11%); we did not observe any null mutations in TBX6 in 166 controls (P<3.8×10(-6)). These null alleles include copy-number variants (12 instances of a 16p11.2 deletion affecting TBX6) and single-nucleotide variants (1 nonsense and 4 frame-shift mutations). However, the discordant intrafamilial phenotypes of 16p11.2 deletion carriers suggest that heterozygous TBX6 null mutation is insufficient to cause congenital scoliosis. We went on to identify a common TBX6 haplotype as the second risk allele in all 17 carriers of TBX6 null mutations (P<1.1×10(-6)). Replication studies involving additional persons with congenital scoliosis who carried a deletion affecting TBX6 confirmed this compound inheritance model. In vitro functional assays suggested that the risk haplotype is a hypomorphic allele. Hemivertebrae are characteristic of TBX6-associated congenital scoliosis.

CONCLUSIONS

Compound inheritance of a rare null mutation and a hypomorphic allele of TBX6 accounted for up to 11% of congenital scoliosis cases in the series that we analyzed. (Funded by the National Basic Research Program of China and others.).

Abstract P1-01-02: The SentiMag study: Sentinel node biopsy with superparamagnetic iron oxide vs. radioisotope

Background:

The SentiMag study compares the “gold standard” 99mTc with a new technique, which employs superparamagnetic iron oxide particles (SPIO) for localization of sentinel lymph nodes. Aim of this study is to investigate the potential equivalency of the SentiMag® technique in comparison to the gold standard of sentinel lymph node biopsy (SLNB).

Materials and methods:

In a prospective, multicentre and multinational 2-arm study, 150 patients with histologically verified breast carcinoma are examined. For comparison, SLNs are marked initially with radioisotope following a 1- or 2-day protocol. Additionally, SPIO (Sienna+®) is injected in the operation room by the surgeon at least 20 minutes before SLNB into the subareolar interstitial tissue, followed by 5 minutes massage. SLN-detection is carried out using a magnetometer (SentiMag®) and a gamma probe. Preparation and excision of lymph nodes is conducted using both techniques in a parallel manner. All lymph nodes marked with either tracer are excised.

Results:

Interim analysis of 138 patients resulted in a detection rate concordance per patient of 97% (134/138). An average of 1.9 (radioisotope) and 2.0 (SPIO) lymph nodes were collected per patient. Nodal detection rate was 92% (250/273) for the radioisotope vs. 97% (265/273) for the SPIO tracer with magnetometer detection. The proportion of pathologically positive lymph nodes was 38/250 (15%) vs. 39/265 (15%) for the radioisotope and the SPIO tracer respectively. All pathologically positive lymph nodes detected with the conventional technique (radioisotope) were also detected with the new technique (SentiMag®).

Conclusions:

The SentiMag® provides an easy technique which can be rapidly implemented into daily routine. Due to the simple handling, preoperative efforts can be reduced to a minimum. If further and consistent results prove its efficacy, this technique may ultimately replace the standard of care.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-01-02.

Abstract P4-03-06: Non-invasive classification of microcalcifications by the use of X-ray phase contrast mammography as a novel tool in breast diagnostics

Purpose: Phase-contrast and scattering-based x-ray imaging are known to provide additional and complementary information to conventional, absorption-based methods. The goal of this study is to evaluate this method to distinguish between benign and malignant microcalcifications with the benefit to increase accuracy of early breast cancer diagnosis. Phase-contrast mammography has been shown to increase image quality of native breast samples when compared to conventional mammography.

Two major types of microcalcifications are found within breast tissue. Type I consist of calcium oxalate dehydrate and type II microcalcifications are composed of calcium phosphates. Type I is seen most frequently in benign lesions whereas type II is indicative for proliferative lesions, including carcinomas. Phase contrast mammography is shown here to distinguish between the two types of microcalcifications and therefore indicates a step forward to improve early breast cancer diagnosis.

Material and Methods: Freshly dissected breast specimens (n = 50) were imaged using a Talbot-Lau interferometer equipped with a conventional x-ray tube; the interferometer was operated at the fifth Talbot distance, tube voltage of 40 kVp with mean energy of 28 keV, and current of 25 mA. The device simultaneously recorded absorption, differential phase and small-angle scattering signals. These quantities were combined into novel, high-frequency-enhanced radiographic images. Histopathological analysis was performed and regions of interests correlated with the findings of phase contrast mammography.

Results: Our novel imaging approach yields complementary and otherwise inaccessible information on electron density distribution and small-angle scattering power of the sample at microscopic scale. Recently we generated the world's first phase contrast mammograms of native, not-fixed human whole breast samples. Our results indicate the superiority of the new technique with respect to image quality and lesion conspicuity. A clinical reader study is currently carried out. Exploiting the multiple, complementary information obtained by grating-based interferometry, we are able to classify microcalcifications by a non-invasive technique within the clinical environment.

By considering the small-angle scattering signal as a complement to the absorption signal, our method can analyze the differences in the attenuation coefficient as well as in the crystal structure of the microcalcifications. Further, the scattering signal is used to decouple the thickness parameter. We demonstrate that type I and type II microcalcifications give opposite absorption and scattering signals and in addition the small-angle scattering signal helps to determine the type of microcalcification.

Conclusions: The potential clinical significance of phase-contrast enhanced mammography has been evaluated by our team. This technique yields improved diagnostic capabilities when compared with conventional mammography, can provide superior contrast, inaccessible and complementary information, and potentially also reduce dose deposition. The non-invasive classification of microcalcifications is an important step toward early diagnosis and differentiation of breast lesions.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-06.

Co/SixGe1-x Alloy Formation on Strained SixGe1-x Layers

The thermally-induced Co/SixGe1-x reaction has been studied for a series of isochronal (25–600°C/20 min) and isothermal (600°C/u-240 min) annealing sequences using Rutherford backscattering spectrometry, transmission electron microscopy and sheet resistance measurements. Annealing at 600°C yields a reacted surface layer comprised of Si-rich CoSixGe1-x, Ge-rich SiyGe1-y and possibly CoSi2, with the two former constituents exhibiting a degree of epitaxial alignment with the substrate. The formation of Co/SiSixGe1-x alloys is discussed in terms of the ternary phase diagram.

[Polypharmacy is an indicator for a poor prognosis, which is not altered by deprescribing in nursing home]

AIM

To examine the influence of polypharmacy ordered by the pretreating site and deprescribing (i.e. the appropriate withdrawal of prescribed drugs) by the nursing home physician on survival time.

METHODS

Retrospective Analysis of medical databasis from 1,249 patients, thereof 611 in a nursing home with practice of deprescribing.

RESULTS

70% of the patients with excessive polypharmacy (>9 drugs), 57% of those with polypharmacy (6 to 9 drugs) and 43% of the remaining patients (<6 drugs) deceased within 286 days after admission (chi-squared 2 DF = 43.72; p <0.001). Deprescribing by the nursing home physician at admission revealed no influence on survival time.

CONCLUSION

Polypharmacy is not the reason, but an indicator for a poor prognosis, which is not altered by deprescribing.

Hyperlipidemia resulting in abnormal density and signal intensity of blood in a neonate with lipoprotein lipase deficiency

We present the imaging findings in an 8-week-old infant with LPL deficiency. Due to markedly increased lipoproteins in the serum, abnormal hypodensity and abnormal T1-weighted hyperintensity were identified in the dural venous sinuses and medullary veins.

Normal skeletal development of mice lacking matrilin 1: redundant function of matrilins in cartilage?

Matrilin 1, or cartilage matrix protein, is a member of a novel family of extracellular matrix proteins. To date, four members of the family have been identified, but their biological role is unknown. Matrilin 1 and matrilin 3 are expressed in cartilage, while matrilin 2 and matrilin 4 are present in many tissues. Here we describe the generation and analysis of mice carrying a null mutation in the Crtm gene encoding matrilin 1. Anatomical and histological studies demonstrated normal development of homozygous mutant mice. Northern blot and biochemical analyses show no compensatory up-regulation of matrilin 2 or 3 in the cartilage of knockout mice. Although matrilin 1 interacts with the collagen II and aggrecan networks of cartilage, suggesting that it may play a role in cartilage tissue organization, studies of collagen extractability indicated that collagen fibril maturation and covalent cross-linking were unaffected by the absence of matrilin 1. Ultrastructural analysis did not reveal any abnormalities of matrix organization. These data suggest that matrilin 1 is not critically required for cartilage structure and function and that matrilin 1 and matrilin 3 may have functionally redundant roles.

Matrilin-2, a large, oligomeric matrix protein, is expressed by a great variety of cells and forms fibrillar networks

Matrilin-2 is a member of the protein superfamily with von Willebrand factor type A-like modules. Mouse matrilin-2 cDNA fragments were expressed in 293-EBNA cells, and the protein was purified, characterized, and used to immunize rabbits. The affinity-purified antiserum detects matrilin-2 in dense and loose connective tissue structures, subepithelial connective tissue of the skin and digestive tract, specialized cartilages, and blood vessel walls. In situ hybridization of 35S-labeled riboprobes localizes the matrilin-2 mRNA to fibroblasts of dermis, tendon, ligaments, perichondrium, and periosteum; connective tissue elements in the heart; smooth muscle cells; and epithelia and loose connective tissue cells of the alimentary canal and respiratory tract. RNA blot hybridization and immunoblotting revealed both matrilin-2 mRNA and protein in cultures of a variety of cell types, confirming the tissue distribution. Alternative splicing affects a module unique for matrilin-2 in all of the above RNA sources. SDS-polyacrylamide gel electrophoresis and electron microscopy reveals matrilin-2 from tissue extracts and cell line cultures as a mixture of mono-, di-, tri-, and tetramers. Matrilin-2 is substituted with N-linked oligosaccharides but not with glycosaminoglycans. Because of other, yet unidentified, cell-type dependent posttranslational modifications, the monomer is heterogeneous in size. Immunofluorescence showed that matrilin-2 functions by forming an extracellular, filamentous network.

[Cartilage oligomeric matrix protein (COMP): the role of a non-collagen cartilage matrix protein as a marker of disease activity and joint destruction in patients with rheumatoid arthritis and osteoarthritis]

Today, we can assess criteria to predict the tissue destruction and progression of Rheumatoid Arthritis (RA) and Osteoarthritis (OA) only in a late stage of the disease. It would be an advantage to have biochemical markers of disease activity and joint destruction to optimize therapy.

PATIENTS AND METHODS

In this cross-sectional study with 37 RA and 20 OA patients (disease duration 119 +/- 130 months for RA and 41 +/- 73 months for OA), ESR, CRP, disease activity score (DAS), the functional status of RA (American College of Rheumatology), and the radiological scoring systems of Larsen and Kellgren/Lawrence, respectively, were used as parameters for disease activity and joint destruction. Cartilage oligomeric matrix protein (COMP) was measured with an enzyme-linked immunosorbent assay (ELISA) in serum and synovial fluid, COMP fragments with immunoblot in the synovial fluid.

RESULTS

The mean COMP value in synovial fluid was 38 ug/ml (RA) and 46 ug/ml (OA); 6.5 ug/ml (RA) and 3.4 ug/ml (OA) in serum. RA patients had a higher amount of small COMP fragments in synovial fluid than OA patients. In RA patients, there was a significant positive correlation between disease activity (DAS) and COMP in synovial fluid and serum, a negative correlation between functional status of RA and serum COMP and between radiologic joint destruction of the knee and serum COMP. In OA patients, there was a significant correlation of joint space width and synovial fluid COMP.

DISCUSSION

A high clinical disease activity (DAS) correlated with high COMP values in serum and synovial fluid and with increasing proteolytic activity (higher amount of small COMP fragments especially in RA). An increased turnover of cartilage matrix in joint inflammation might explain this correlation. The correlation of decreased COMP with decreased functional status in RA and increased joint destruction is compatible with a loss of cartilage and less turnover. The correlation between joint space width and increased COMP in OA patients with short disease duration might be explained with a higher turnover of the cartilage matrix in the early stage of the disease.

Analysis of cartilage oligomeric matrix protein (COMP) in synovial fibroblasts and synovial fluids

We investigated the expression of cartilage oligomeric matrix protein (COMP) in normal and rheumatoid arthritis (RA) synovial fibroblasts. In situ hybridization (ISH) was conducted on synovial specimens from five RA patients applying specific probes for COMP or fibroblast collagen type I. ISH was combined with immunohistochemistry, applying antibodies to the macrophage marker CD68. Ribonuclease protection assay (RPA) and rapid amplification of 3'-cDNA ends (3'-RACE) were performed on total RNA from normal and RA synovial fibroblast cultures. Protein extracts from fibroblasts and culture supernatants were compared with synovial fluids and protein extracts from isolated chondrocytes by Western blot utilizing polyclonal and monoclonal antibodies (18-G3 mAb) to COMP. COMP mRNA was detected in fibroblasts of RA synovium by ISH, and in normal and RA synovial fibroblast cultures by RPA. 3'-RACE demonstrated sequence homology of chondrocyte and synovial fibroblast COMP along the coding sequence. COMP protein was detected in synovial fibroblasts and culture supernatants by immunoblot. Using polyclonal antibodies, the major portion of COMP from fibroblasts and culture supernatants was present as low-molecular-weight (LMW) bands, corresponding to those found in synovial fluids. These LMW COMP bands, however, were not detected in any of the cells or tissues tested using 18-G3 mAb. In protein extracts from chondrocytes and in COMP purified from cartilage, these LMW bands could not be detected. In conclusion, the data suggest that certain forms of COMP detected in synovial fluid are secreted from synovial fibroblasts and could be distinguished by specific mAbs from COMP secreted by chondrocytes.

[From chondrocyte culture to joint cartilage replacement. Development of de novo cartilage in vitro]

Local repair of acute or chronic cartilage lesions has not been successful so far. An attempt has been made to use synthetic materials to improve the quality of the repair tissue, but no method has achieved reliable regrowth of normal hyaline cartilage with adequate biomechanical properties and bonding to surrounding tissue. After publication of the first short-term results of chondrocyte transplantation in patients with localized cartilage lesions of the knee joints by a Swedish group in 1994 [1], the situation seems to have changed. Even though the advantages of this method of chondrocyte transplantation is a matter of controversy, the interest in the so-called "Carticel" approach has grown steadily. Indeed, the technique was recently approved by the FDA, on condition of a randomized, "placebo"-controlled trial. In view of this rapid development, we feel that independent experimental studies are urgently needed. In this article we present our own results in synthesizing de novo cartilage from cultured and phenotypically stable chondrocytes in a truly three-dimensional cartilage-like polyanionic matrix. With the experience gained in animals, we expect to set the stage for future experimental therapy in young human patients with early cartilage lesions.

Small fragments of cartilage oligomeric matrix protein in synovial fluid and serum as markers for cartilage degradation

We determined the tissue distribution of cartilage oligomeric matrix protein (COMP) in man and evaluated COMP in synovial fluid (SF) and serum. COMP was purified from human articular cartilage. Polyclonal antibodies were used to detect COMP in tissue cryosections and protein extracts. COMP was determined quantitatively and qualitatively in SF and serum by competitive enzyme-linked immunosorbent assay and immunoblotting. Knee joint SF was taken from nine cadaveric and six living controls, 52 patients with osteoarthritis (OA), 85 patients with rheumatoid arthritis (RA) and 60 patients with other forms of inflammatory arthritis. The degradative potential of SF on native COMP was tested in vitro. The highest concentrations of COMP were measured in articular cartilage and meniscus, the lowest in rib and trachea. Compared with controls, the concentrations of COMP in SF and serum were elevated in 36 and 50% of the patients. A total of 84% of patients with RA and 60% of patients with other forms of inflammatory arthritis showed significant amounts of low-molecular-weight COMP fragments (50-70 kDa) in SF. In contrast, SF fragments were present in only 21% of the OA patients. Furthermore, 13% of SF taken from patients with RA or other forms of inflammatory arthritis were able to degrade COMP in vitro. Using inhibitors, the involvement of serine proteinases could be demonstrated in only 8% of the cases. Based on these results, the absolute levels of COMP in SF and serum, and its fragmentation pattern in SF, seem to be promising as markers of joint tissue metabolism.

The cellularity of developing adipose tissues in Pietrain and Meishan pigs

The development of external, internal, inter- and intramuscular adipose tissues was compared in Pietrain (lean) and Meishan (obese) pigs during their growth, at 0, 7, 30 and 90 days of age. Up to 1 month of age, the total lipid content of external and internal adipose tissues as well as mean adipocyte diameter increased similarly in both breeds of pigs. The percentage of plurilocular adipocytes decreased in both breeds; it remained higher in Meishan up to 30 days of age, which would indicate a delayed maturity of adipose tissue in this pig. Adipocyte hypertrophy characterizing the Meishan pig starts between 1 and 3 months of age. At 90 days, adipocyte diameters were about 50% higher in Meishan than in Pietrain. Muscle lipid content was higher in Pietrain than in Meishan until 1 month of age, whereafter it became lower than that of Meishan. Intramuscular adipocytes appeared later than those of other tissues in both breeds and were larger in Meishan than in Pietrain.

Inhibition of the electrostatic interaction between beta-amyloid peptide and membranes prevents beta-amyloid-induced toxicity

The accumulation of beta-amyloid peptides (Abeta) into senile plaques is one of the hallmarks of Alzheimer disease. Aggregated Abeta is toxic to cells in culture and this has been considered to be the cause of neurodegeneration that occurs in the Alzheimer disease brain. The discovery of compounds that prevent Abeta toxicity may lead to a better understanding of the processes involved and ultimately to possible therapeutic drugs. Low nanomolar concentrations of Abeta1-42 and the toxic fragment Abeta25-35 have been demonstrated to render cells more sensitive to subsequent insults as manifested by an increased sensitivity to formazan crystals following MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) reduction. Formation of the toxic beta-sheet conformation by Abeta peptides is increased by negatively charged membranes. Here we demonstrate that phloretin and exifone, dipolar compounds that decrease the effective negative charge of membranes, prevent association of Abeta1-40 and Abeta25-35 to negatively charged lipid vesicles and Abeta induced cell toxicity. These results suggest that Abeta toxicity is mediated through a nonspecific physicochemical interaction with cell membranes.

Hybridisation based DNA screening on peptide nucleic acid (PNA) oligomer arrays

Arrays of up to some 1000 PNA oligomers of individual sequence were synthesised on polymer membranes using a robotic device originally designed for peptide synthesis. At approximately 96%, the stepwise synthesis efficiency was comparable to standard PNA synthesis procedures. Optionally, the individual, fully deprotected PNA oligomers could be removed from the support for further use, because an enzymatically cleavable but otherwise stable linker was used. Since PNA arrays could form powerful tools for hybridisation based DNA screening assays due to some favourable features of the PNA molecules, the hybridisation behaviour of DNA probes to PNA arrays was investigated for a precise understanding of PNA-DNA interactions on solid support. Hybridisation followed the Watson-Crick base pairing rules with higher duplex stabilities than on corresponding DNA oligonucleotide sensors. Both the affinity and specificity of DNA hybridisation to the PNA oligomers depended on the hybridisation conditions more than expected. Successful discrimination between hybridisation to full complementary PNA sequences and truncated or mismatched versions was possible at salt concentrations down to 10 mM Na+and below, although an increasing tendency to unspecific DNA binding and few strong mismatch hybridisation events were observed.

Ultrastructure and cytochemical detection of alkaline phosphatase in long-term cultures of osteoblast-like cells from rat calvaria

Two methods of collecting osteoblast-like cells from newborn rat calvaria were tested, either placing individual glass fragments or tipping dense glass beads onto the endocranial surface of periosteum-free bone. Inoculated at high density, cells collected by using these two methods form large mineralized plates after three weeks of culture. The main purpose of our investigation was to analyze the progressive formation of this mineralized structure and to localize alkaline phosphatase activity. At the beginning of the culture, flattened cells gathered into multilayers and synthesized collagen fibers. Cells in the upper layer became rapidly cuboidal in shape and continued to secrete collagen at their basal pole, whereas other cells became progressively embedded in the extracellular matrix. The upper cells featured ultrastructural characters of osteoblasts, whereas the embedded cells resembled osteocytes. After two weeks, the matrix began to mineralize: crystals appeared on collagen fibers, on matrix vesicles, and on cell debris. During the first days of the culture, the alkaline phosphatase activity was localized on the plasma membranes and on the collagen fibers. Thereafter, only the upper cells and collagen fibers that were juxtaposed to these cells showed alkaline phosphatase activity. In addition, the presence of mineralized matrix prevented the reaction product from being visualized on collagen fibers. The ultrastructural analysis reveals large mineralized plates with a structure resembling that of bone in vivo. This culture appears to be an appropriate model to study bone formation and regulation.

Interaction of cartilage matrix protein with aggrecan. Increased covalent cross-linking with tissue maturation

Cartilage matrix protein (CMP) is a trimeric protein present in many types of cartilage extracellular matrix. It has recently been purified under native conditions that allowed the proposal of a structural model (Hauser, N., and Paulsson, M. (1994) J. Biol. Chem. 269, 25747-25753). To examine the functional properties of CMP we studied its interaction with aggrecan within cartilage extracellular matrix. Aggrecan-enriched fractions were purified from bovine tracheal cartilage of different ages under nondenaturing and denaturing conditions, respectively, and characterized by a combination of biochemical methods and electron microscopy. The fractions contained a pool of CMP noncovalently associated with aggrecan as well as a pool of CMP that appears covalently cross-linked to the aggrecan core protein. Only about two thirds of the CMP subunits could be released even upon reduction under denaturing conditions. It appears that CMP is attached by a nonreducible covalent interaction of one of its subunits with the protein core. The amount of CMP strongly bound to aggrecan increases with age. Electron microscopy revealed interaction sites for CMP in the extended chondroitin-sulfate attachment domain E2. In old tissue five distinct binding sites for CMP were found while in young cartilage only three of these were occupied. The extent of decoration of E2 with CMP increases with age.

Increased degradation and altered tissue distribution of cartilage oligomeric matrix protein in human rheumatoid and osteoarthritic cartilage

We investigated the degradation and tissue distribution of cartilage oligomeric matrix protein in normal, osteoarthritic, and rheumatoid arthritic articular cartilage of the human knee. Cartilage was subjected to sequential extractions with buffers containing neutral salt, with EDTA, and finally with guanidine/HCl and then was analyzed by Western blotting with a polyclonal antiserum to human cartilage oligomeric matrix protein. Western blots of the nine neutral salt extracts from normal cartilage revealed mostly intact pentameric molecules of cartilage oligomeric matrix protein, in contrast to the 13 osteoarthritic and five rheumatoid arthritic cartilage samples that demonstrated marked degradation of cartilage oligomeric matrix protein as noted by a predominance of reduction-sensitive bands at approximately 150 kDa and nonreduction-sensitive bands in the 67-94 kDa range. The EDTA and guanidine/HCl extracts from all groups were similar and showed mostly intact molecules of cartilage oligomeric matrix protein, with smaller amounts of degraded cartilage oligomeric matrix protein identical to those resolved by the Western blots of the neutral salt extracts. Western blots of matched pairs of synovial fluid and cartilage extracts demonstrated cartilage oligomeric matrix protein fragments of the same molecular mass. Competitive enzyme-linked immunosorbent assay revealed significantly less cartilage oligomeric matrix protein in rheumatoid articular cartilage than in either normal or osteoarthritic cartilage. In contrast to normal cartilage, where cartilage oligomeric matrix protein was predominantly localized to the interterritorial matrix throughout all zones of the matrix, with increased staining in the deeper cartilaginous zones, the most intense staining in osteoarthritic cartilage was in the superficial zones of fibrillated cartilage, with little to no immunostaining in the midzones and relatively poor staining in the deeper cartilaginous zones. This distribution was the inverse of that for proteoglycans, as demonstrated by toluidine blue staining, where proteoglycans were depleted primarily from the superficial fibrillated cartilage. In mild to moderately affected rheumatoid cartilage, the tissue distribution of cartilage oligomeric matrix protein was similar to the distribution of proteoglycans, with relatively uniform staining of the interterritorial and territorial matrics. In more severely affected rheumatoid cartilage, the superficial zones demonstrated punctate immunostaining for cartilage oligomeric matrix protein in the interterritorial and territorial matrics, and staining was restricted to the territorial matrix in the deep cartilaginous zones. It is evident from this study that (a) noncollagenous proteins such as cartilage oligomeric matrix protein are greatly affected in arthritis, (b) degradation fragments released from the matrix into the synovial fluid reflect the processes occurring within the matrix, and (c) different zones of the articular cartilage are susceptible to degradation of cartilage oligomeric matrix protein in the different disease processes.

N-Glycosylation affects endoplasmic reticulum degradation of a mutated derivative of carboxypeptidase yscY in yeast

The endoplasmic reticulum (ER) of eukaryotic cells contains a quality control system, that is required for the proteolytic removal of aberrantly folded proteins that accumulate in this organelle. We used genetic and biochemical methods to analyse the involvement of N-glycosylation in the degradation of a mutant derivative of carboxypeptidase yscY in the ER of the yeast Saccharomyces cerevisiae. Our results demonstrate that N-glycosylation of this protein is required for its degradation since an unglycosylated species is retained stably in the ER. Cells that were devoid of the ER-processing alpha 1,2-mannosidase showed reduced degradation of the glycosylated substrate protein. Disruption of CNE1, a gene encoding a putative yeast homologue for calnexin, did not exhibit any effects on the degradation of this substrate protein in vivo. Also, the alpha 1,2-mannosidase-dependent reduction in the degradation rate did not show any correlation with the function of the CNE1 gene product. Our results suggest that the ER of yeast contains a glycosylation-dependent quality control system, as has been shown for higher eukaryotic cells.

Beta-amyloid-induced cell toxicity: enhancement of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-dependent cell death

In an attempt to understand the cause of neurodegeneration in Alzheimer's disease, the toxic effects of beta-amyloid (Abeta) peptides have been widely studied. At high micromolar concentrations Abeta peptides have been demonstrated to be acutely toxic to various cell types. At submicromolar concentrations, Abeta peptides have been suggested to inhibit cellular metabolic activity, due to their inhibition of the ability of cells to metabolize the oxidoreductase substrate 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Here we show, first, that MTT reduction surprisingly leads to a breakdown in PC12 cell membrane integrity and cell death, presumably through the formation of a crystalline formazan product, and, second, that pretreatment of PC12 cells with nanomolar concentrations of Abeta peptide, rather than inhibiting their metabolic activity, increases the susceptibility of these cells to the secondary toxic effect of formazan crystal formation. These results suggest that low nanomolar concentrations of Abeta render membranes more susceptible to damage by a secondary insult, in this case, MTT reduction. It is plausible that such an effect, when combined with additional risk factors, could contribute to the neurodegeneration that occurs in Alzheimer's disease.

Cloning, sequencing and expression analysis of mouse cartilage matrix protein cDNA

A cDNA encoding the mouse cartilage matrix protein (CMP) was cloned following the reverse-transcription polymerase chain reaction and rapid amplification of cDNA ends procedures using mRNA isolated from trachea. The open reading frame encodes a product of 500 amino acids. Large parts of the protein have been completely conserved when compared to chicken and human sequences, including all 12 cysteine residues of the mature CMP. In situ hybridization reveals an even distribution of the CMP mRNA in the developing skeleton, which is followed by a zonal distribution paralleling hypertrophy and calcification. From early cartilage differentiation and onwards, CMP transcript is absent in the forming articular surfaces and intervertebral discs. Extraskeletal expression of CMP mRNA was detected in the adult eye.