The breakage-fusion-bridge (BFB) cycle as a mechanism for generating genetic heterogeneity in osteosarcoma

Osteosarcoma (OS) is characterized by chromosomal instability and high copy number gene amplification. The breakage-fusion-bridge (BFB) cycle is a well-established mechanism of genome instability in tumors and in vitro models used to study the origins of complex chromosomal rearrangements and cancer genome amplification. To determine whether the BFB cycle could be increasing the de novo rate of formation of cytogenetic aberrations in OS, the frequency of anaphase bridge configurations and dicentric chromosomes in four OS cell lines was quantified. An increased level of anaphase bridges and dicentrics was observed in all the OS cell lines. There was also a strong association between the frequencies of anaphase bridges, dicentrics, centrosomal anomalies, and multipolar mitotic figures in all the OS cell lines, indicating a possible link in the mechanisms that led to the structural and numerical instabilities observed in OS. In summary, this study has provided strong support for the role of the BFB cycle in generating the extensive structural chromosome aberrations, as well as cell-to-cell cytogenetic variation observed in OS, thus conferring the genetic diversity for OS tumor progression.

Impact of an asthma education programme on patients' knowledge, inhaler technique and compliance to treatment

INTRODUCTION

We conducted a study to assess the impact of an asthma education programme (AEP) on knowledge of asthma and medication, compliance to treatment and inhaler technique, emergency department visits and hospital re-admissions.

METHODS

Patients hospitalised for asthma exacerbation were administered a questionnaire to test their baseline knowledge and beliefs on asthma, its medications and their compliance to treatment. Their inhaler technique was assessed. They then underwent an AEP consisting of two individualised education sessions. Re-testing was performed after three months. Per protocol approach and McNemar's test was used to analyse the statistical significance of the change in the pre- and post-AEP test scores. Hospital administrative data were used to determine the number of ED visits and hospital admissions pre- and post-AEP.

RESULTS

Among the 67 patients who completed the two-phase AEP, there was significant improvement in some knowledge aspects (ability to identify rescue medication [p-value is 0.031], that different stimuli can trigger asthma symptoms [p-value is 0.016], that a peak flow meter is used for monitoring asthma [p-value is 0.004], that asthma symptoms are caused by airway swelling/narrowing [p-value is less than 0.001], that steroid inhaler are to be used daily as preventive therapy [p-value is less than 0.001], in self-reported inhaler compliance (number of puffs per administration [p-value is less than 0.001] and per day [p-value is less than 0.001]), and in inhaler technique [p-value is 0.001]. There was also significant reduction in emergency department attendances (p-value is less than 0.001) and hospital admissions (p-value is less than 0.001) among all 97 subjects over a one-year period.

CONCLUSION

This study demonstrated the effectiveness of an AEP in patients hospitalised for asthma exacerbation.

An integrated mBAND and submegabase resolution tiling set (SMRT) CGH array analysis of focal amplification, microdeletions, and ladder structures consistent with breakage-fusion-bridge cycle events in osteosarcoma

Osteosarcoma (OS) is characterized by chromosomal instability and high-copy-number gene amplification. The breakage-fusion-bridge (BFB) cycle is a well-established mechanism of genomic instability in tumors and in vitro models used to study the origins of complex chromosomal rearrangements and cancer genome amplification. However, until now, there have been no high-resolution cytogenetic or genomic array studies of BFB events in OS. In the present study, multicolor banding (mBAND) FISH and submegabase resolution tiling set (SMRT) array comparative genomic hybridization (CGH) were used to identify and map genomic signatures of BFB events in four OS cell lines and one patient tumor. The expected intermediates associated with BFB-dicentric chromosomes, inverted duplications, and intra- and interchromosomal amplifications-were identified. mBAND analysis provided detailed mapping of rearrangements in 1p, 6p, and 8q and showed that translocation junctions were often in close proximity to fragile sites. More detailed mBAND studies of OS cell line MG-63 revealed ladderlike FISH signals of equally spaced interchromosomal coamplifications of 6p21, 8q24, and 9p21-p22 in a homogeneously staining region (hsr). Focal amplifications that concordantly mapped to the hsr were localized to discrete genomic intervals by SMRT array CGH. The complex amplicon structure in this hsr suggests focal amplifications immediately adjacent to microdeletions. Moreover, the genomic regions in which there was deletion/amplification had a preponderance of fragile sites. In summary, this study has provided further support for the role of the BFB mechanism and fragile sites in facilitating gene amplification and chromosomal rearrangement in OS.

Use of whole genome amplification and comparative genomic hybridisation to detect chromosomal copy number alterations in cell line material and tumour tissue

We have established that whole genome amplification (WGA), in conjunction with genomic DNA array comparative genomic hybridisation (gaCGH) allows for the identification of genome-wide copy number abnormalities (CNAs) in DNA extracted from both cell line and patient material. To determine the fidelity and reproducibility of WGA to detect copy number imbalances using gaCGH, well characterized cell line genomic DNA was analysed. The gaCGH data obtained from non-amplified DNA and amplified DNA for the neuroblastoma cell line NUB7 and a paediatric medulloblastoma patient was almost identical. In addition, laser capture microdissection (LCM) of prostate tumour cells and subsequent WGA allowed for the detection of a number of CNAs that may not have been identified if DNA had been extracted in bulk from heterogeneous tissue. The results presented here demonstrate the use of WGA for generating sufficient DNA for gaCGH analysis without the introduction of significant sequence representation bias. The combination of amplification and gaCGH using DNA extracted from archival patient material has the potential for permitting the studying of DNA from small cancerous or pre-cancerous foci, which may help to identify potential genomic markers for early diagnosis.

Combined spectral karyotyping, multicolor banding, and microarray comparative genomic hybridization analysis provides a detailed characterization of complex structural chromosomal rearrangements associated with gene amplification in the osteosarcoma cell line MG-63

The advancement of fluorescence in situ hybridization-based assays has permitted more refined delineation of chromosomal loci involved in complex chromosomal rearrangements (CCRs) and gene amplification. In this detailed molecular cytogenetic analysis, spectral karyotyping (SKY), multicolor banding (mBAND) analysis, and microarray comparative genomic hybridization (CGH) were used to refine the analysis of chromosomes with amplifications and small intrachromosomal rearrangements such as inverted duplications and interstitial deletions present in the osteosarcoma cell line MG-63. SKY analysis has limited resolving power to delineate cryptic chromosomal rearrangements, so mBAND assays were performed for a subset of chromosomes (i.e., 6, 8, 17, and 20). Of the 10 clonal CCRs analyzed in detail with mBAND, 5 were found to have rearrangements between 8q24 and either 6p23 approximately pter or 6p21, with multiple copies of this translocation inserted at various sites in the different chromosomes. In two CCRs, 6p21 and 8q24 generated an alternating pattern of mBAND probe hybridization, indicating the presence of a large coamplified repeat unit within homogeneously staining regions. Microarray CGH analysis demonstrated focal high-level amplification of 8q23 approximately q24, 6p22 approximately pter, and 6p21, in agreement with the pattern of chromosome subband gains identified with mBAND. Thus, sequential SKY, mBAND, and microarray CGH provided a comprehensive description of some of the intricate chromosomal aberrations present in the complex MG-63 karyotype and permitted reconstruction of the fine structure of the genomic rearrangements, thus providing some important mechanistic clues concerning the details of the amplification process in tumors.

Malnutrition screening in hospitalised patients and its implication on reimbursement

BACKGROUND

Several studies have cited the incidence of malnutrition in hospitals, which is correlated to negative clinical outcomes, to be up to 60%. Data in Singapore, however, are scarce. Its impact on casemix funding is not known.

AIMS

The aims of the present study were to determine the prevalence of malnutrition, the predisposing risk factors and the impact of documentation and coding of malnutrition on casemix funding in a local population in Singapore.

METHODS

Patients admitted to selected wards over a 1-month period were screened for malnutrition. Those at risk were further assessed using subjective global assessment. Logistic regression was used to ascertain the impact of identified factors on malnutrition. Financial impact analysis of coding of malnutrition as a comorbidity was carried out and tested with Wilcoxon signed rank tests.

RESULTS

Six hundred and fifty-eight patients were eligible for screening. The overall prevalence of malnutrition in the selected wards was 14.7% (95% confidence interval (CI): 12.0-17.4%). Old age, the occurrence of cancer and the admitting unit were statistically significant in explaining the occurrence of malnutrition. Coding of malnutrition was found to significantly increase the complexity of 24 of 105 episodes (22.9%) of patient care as measured by expected cost weights (P < 0.001) and expected lengths of stay (P < 0.001). As a result, the expected financing for these 24 patients increased by 59.7%.

CONCLUSIONS

Malnutrition is prevalent in hospitalised medical and surgical patients. Certain clinical factors should heighten awareness and prompt detection for malnutrition. Coding for malnutrition impacts favourably on casemix funding for a subset of malnourished patients.

Defining a 0.5-mb region of genomic gain on chromosome 6p22 in bladder cancer by quantitative-multiplex polymerase chain reaction

Metaphase-based comparative genomic hybridization (CGH) has identified recurrent regions of gain on different chromosomes in bladder cancer, including 6p22. These regions may contain activated oncogenes important in disease progression. Using quantitative multiplex polymerase chain reaction (QM-PCR) to study DNA from 59 bladder tumors, we precisely mapped the focal region of genomic gain on 6p22. The marker STS-X64229 had copy number increases in 38 of 59 (64%) tumors and the flanking markers, RH122450 and A009N14, had copy number gains in 33 of 59 (56%) and 26 of 59 (45%) respectively. Contiguous gain was present for all three markers in 14 of 59 (24%) and for two (RH122450 and STS-X64229) in 25 of 59 (42%). The genomic distance between the markers flanking STS-X64229 is 0.5 megabases, defining the minimal region of gain on 6p22. Locus-specific interphase fluorescence in situ hybridization confirmed the increased copy numbers detected by QM-PCR. Current human genomic mapping data indicates that an oncogene, DEK, is centrally placed within this minimal region. Our findings demonstrate the power of QM-PCR to narrow the regions identified by CGH to facilitate identifying specific candidate oncogenes. This also represents the first study identifying DNA copy number increases for DEK in bladder cancer.

High-resolution mapping of amplifications and deletions in pediatric osteosarcoma by use of CGH analysis of cDNA microarrays

Conventional cytogenetic and comparative genomic hybridization (CGH) studies have shown that osteosarcomas (OSs) are characterized by complex structural and numerical chromosomal alterations and gene amplification. In this study, we used high-resolution CGH to investigate recurrent patterns of genomic imbalance by use of DNA derived from nine OS tumors hybridized to a 19,200-clone cDNA microarray. In six OSs, there was copy number gain or amplification of 6p, with a minimal region of gain centering on segment 6p12.1. In seven OSs, the pattern of amplification affecting chromosome arm 8q showed high-level gains of 8q12-21.3 and 8q22-q23, with amplification of the MYC oncogene at 8q24.2. Seven OSs showed copy number gain or amplification of 17p between the loci bounded by GAS7 and PMI (17p11.2-17p12), and three of these tumors also showed small losses at 17p13, including the region containing TP53. An in silico analysis of the distribution of segmental duplications (duplicons) in this region identified a large number of tracts consisting of paralogous sequences mapping to the 17p region, encompassing the region of deletions and amplifications in OS. Interestingly, within this same region there were clusters of duplicons and several genes that are expressed during bone morphogenesis and in OS. In summary, microarray CGH analysis of the chromosomal imbalances of OS confirm the overall pattern observed by use of metaphase CGH and provides a more precise refinement of the boundaries of genomic gains and losses that characterize this tumor.

A preliminary evaluation of a disease management programme for patients with diabetes mellitus and hypertension in a primary healthcare setting

INTRODUCTION

The Comprehensive Chronic Care Programme (CCCP) is an intensified programme designed to provide comprehensive care for the management of diabetes mellitus, hypertension and hyperlipidaemia at a primary healthcare setting. A formative study was done to evaluate the effectiveness of the CCCP compared to the normal polyclinic management of diabetes mellitus.

MATERIALS AND METHODS

Control of diabetes (HbA1c) and hypertension (blood pressure) in 63 diabetic patients of a pilot CCCP was compared with 100 diabetic patients not on the programme (non-CCCP) after a 6-month follow-up. Paired t-tests were conducted for differences in mean HbA1c values between baseline and after 6 months. The H-rank test was applied to check for significant differences in change categories of hypertension control between CCCP and non-CCCP cases.

RESULTS

In the CCCP group, there was a two-point decrease in HbA1c after 6 months and 65.1% of the patients showed improvement. The proportion of patients achieving optimal diabetic control increased from 9.5% to 36.5%. Conversely, there was deterioration in the non-CCCP group with decrease in the proportion of patients achieving optimal diabetic control from 31% to 21%. Of the hypertensive patients in the CCCP group, 54.5% showed an improvement in blood pressure (BP) control while 44% of the non-CCCP group showed improvement at 6 months.

CONCLUSIONS

CCCP, a comprehensive chronic disease management programme, is effective for good diabetic control of patients with diabetes mellitus.

Fractured Whiteside Ortholoc II knee components

A comprehensive failure analysis was performed on 6 femoral components and 1 tibial component that fractured in service. All were Whiteside Ortholoc II total knee arthroplasty components, manufactured from cast cobalt-chromium-molybdenum alloy and porous coated. Fracture surface analysis revealed fatigue-induced failure in all cases. Most fractures occurred at regions of high stress concentration, such as sharp corners, sintered beads, and thin sections. Metallurgical examination showed significant variation in grain size, interdendritic carbides, and hardness between samples. In some cases, continuous carbide networks and voids were prominent at the bead-substrate interface. Patient weight and surgical placement were identified as contributory factors in component failure. Limitations of cast cobalt-chromium-molybdenum alloy in weight-bearing applications must be emphasized, particularly when important determinants, such as design, metallurgy, and specific clinical factors, are less than optimal.

Pyridoxine and pyridoxamine inhibits superoxide radicals and prevents lipid peroxidation, protein glycosylation, and (Na+ + K+)-ATPase activity reduction in high glucose-treated human erythrocytes

Vitamin B(6) (pyridoxine) supplementation has been found beneficial in preventing diabetic neuropathy and retinopathy, and the glycosylation of proteins. Oxygen radicals and oxidative damage have been implicated in the cellular dysfunction and complications of diabetes. This study was undertaken to test the hypothesis that pyridoxine (P) and pyridoxamine (PM) inhibit superoxide radical production, reduce lipid peroxidation and glycosylation, and increase the (Na+ + K+)-ATPase activity in high glucose-exposed red blood cells (RBC). Superoxide radical production was assessed by the reduction of cytochrome C by glucose in the presence and absence of P or PM in a cell-free buffered solution. To examine cellular effects, washed normal human RBC were treated with control and high glucose concentrations with and without P or PM. Both P and PM significantly lowered lipid peroxidation and glycated hemoglobin (HbA(1)) formation in high glucose-exposed RBC. P and PM significantly prevented the reduction in (Na+ + K+)-ATPase activity in high glucose-treated RBC. Thus, P or PM can inhibit oxygen radical production, which in turn prevents the lipid peroxidation, protein glycosylation, and (Na+ + K+)-ATPase activity reduction induced by the hyperglycemia. This study describes a new biochemical mechanism by which P or PM supplementation may delay or inhibit the development of complications in diabetes.

Overcoming challenges in newborn hearing screening

Retrospective hearing screening data were analyzed on 66,292 newborns to assess factors which contribute to overall program success, especially those related to tracking and follow-up of positive initial hearing screens. Newborn hearing screens were performed in 46 sites within five regions utilizing automated auditory brainstem response (AABR) technology. Pediatrix Medical Group managed all 46 sites and tracked all positive screens under the direction of the national program director. One hundred and fourteen newborns were confirmed with hearing loss, with 60% exhibiting no known risk factors. The five regions collectively yielded a final refer rate of 1.01% over a 1-year period, whereas two of the five regions boasted capture rates of 98%. Fifty percent of the confirmed hearing losses was bilateral in nature. Several key factors were noted to have a positive impact on the overall success of the program as related to follow-up. This paper demonstrates that tracking and follow-up can be successful if program management and implementation are considered when establishing a newborn hearing screening program. The protocol presented can be viewed as a model for existing programs by those who are interested in overcoming challenges related to follow-up and can ensure program success.

Lipoic acid decreases lipid peroxidation and protein glycosylation and increases (Na(+) + K(+))- and Ca(++)-ATPase activities in high glucose-treated human erythrocytes

Lipoic acid supplementation has been found to be beneficial in preventing neurovascular abnormalities in diabetic neuropathy. Insufficient (Na(+) + K(+))-ATPase activity has been suggested as a contributing factor in the development of diabetic neuropathy. This study was undertaken to test the hypothesis that lipoic acid reduces lipid peroxidation and glycosylation and can increase the (Na(+) + K(+))- and Ca(++)-ATPase activities in high glucose-exposed red blood cells (RBC). Washed normal human RBC were treated with normal (6 mM) and high glucose concentrations (45 mM) with 0-0.2 mM lipoic acid (mixture of S and R sterioisomers) in a shaking water bath at 37 degrees C for 24 h. There was a significant stimulation of glucose consumption by RBC in the presence of lipoic acid both in normal and high glucose-treated RBC. Lipoic acid significantly lowered the level of glycated hemoglobin (GHb) and lipid peroxidation in RBC exposed to high glucose concentrations. High glucose treatment significantly lowered the activities of (Na(+) + K(+))- and Ca(++)-ATPases of RBC membranes. Lipoic acid addition significantly blocked the reduction in activities of (Na(+) + K(+))- and Ca(++)-ATPases in high glucose- treated RBC. There were no differences in lipid peroxidation, GHb and (Na(+) + K(+))- and Ca(++)-ATPase activity levels in normal glucose-treated RBC with and without lipoic acid. Thus, lipoic acid can lower lipid peroxidation and protein glycosylation, and increase (Na(+) + K(+))- and Ca(++)-ATPase activities in high-glucose exposed RBC, which provides a potential mechanism by which lipoic acid may delay or inhibit the development of neuropathy in diabetes.

Tunable stimulated-Brillouin-scattering resonator started by feedback provided by Bragg scattering from the dynamic grating within an active medium

We report a tunable stimulated-Brillouin-scattering resonator that does not require a starting mirror or a wavelength selector. The resonator is based on the Bragg scattering from the dynamic grating within the active medium itself. The laser dye (Rhodamine 6G dissolved in ethanol) was utilized as the active medium and was pumped by a frequency-doubled Nd:YAG laser. The quality factor (M(2)) of the output beam was 2.2. A single short pulse (<1 ns) with a pumping efficiency of ~4% was observed.

An application of polarized domains in ferroelectric thin films using scanning probe microscope

The feasibility of utilizing PZT films as future data storage media was investigated using a modified AFM. Applying voltages between a conductive AFM tip and the PZT films causes the switching of ferroelectric domains. The domains are observed using an EFM imaging technique. The experimental results and calculations revealed that the electrostatic force generated between the polarized area and the tip is a main contributor for the imaging of the polarized domains. The written features on ferroelectric films were less than 100 nm in diameter, implying the possibility of realizing data storage devices with ultra-high area density. The disappearance of the polarized images without any applied voltage was observed, which is a drawback in this application of PZT thin films.

Transbuccal permeation of a nucleoside analog, dideoxycytidine: effects of menthol as a permeation enhancer

The use of a safe and effective permeation enhancer is paramount to the success of a buccal drug delivery system intended for systemic drug absorption. The enhancing effects of menthol (dissolved in an aqueous buffer in the absence of co-enhancers) on buccal permeation of a model hydrophilic nucleoside analog, dideoxycytidine (ddC), were investigated. In vitro transbuccal permeation of ddC was examined using freshly obtained porcine buccal mucosa. The experiments were carried out in side-bi-side flow through diffusion cells. Permeation enhancement studies were performed with varying concentrations of l-menthol dissolved in Krebs buffer solutions containing ddC. Partition coefficient experiments were carried out to probe into the mechanism of permeation enhancing properties of l-menthol and DSC studies were conducted to determine if there is a eutectic formation between ddC and l-menthol at various concentrations. Permeation of ddC increased significantly (P<0.05) in the presence of l-menthol independent of the concentration of the terpene. The apparent 1-octanol/buffer partition coefficient (log K(p)) of ddC was significantly (P<0.05) increased in presence of l-menthol and was also independent of the enhancer concentration. However, the tissue/buffer partition coefficient (log K'(p)) data showed a concentration dependent increase of log K'(p) in presence of l-menthol. Since log K'(p) is a measure of drug binding to the tissue in addition to drug partitioning, binding of ddC to the buccal tissue may provide an explanation for the concentration dependent increase in these values.