Instrument for determining the complex shear modulus of soft-tissue-like materials from 10 to 300 Hz

Accurate determination of the complex shear modulus of soft tissues and soft-tissue-like materials in the 10-300 Hz frequency range is very important to researchers in MR elastography and acoustic radiation force impulse (ARFI) imaging. A variety of instruments for making such measurements has been reported, but none of them is easily reproduced, and none have been tested to conform to causality via the Kramers-Kronig (K-K) relations. A promising linear oscillation instrument described in a previous brief report operates between 20 and 160 Hz, but results were not tested for conformity to the K-K relations. We have produced a similar instrument with our own version of the electronic components and have also accounted for instrumental effects on the data reduction, which is not addressed in the previous report. The improved instrument has been shown to conform to an accurate approximation of the K-K relations over the 10-300 Hz range. The K-K approximation is based on the Weichert mechanical circuit model. We also found that the sample thickness must be small enough to obtain agreement with a calibrated commercial rheometer. A complete description of the improved instrument is given, facilitating replication in other labs.

Natriuretic Peptides, Antidiuretic Hormone and Hyponatraemia after Acute Craniocerebral Injury

We investigated the physiological mechanisms involved in central hyponatraemia in patients with acute craniocerebral injury (ACI). We measured blood concentrations of natriuretic peptides, antidiuretic hormone (ADH), and endogenous digitalis-like substance (EDLS), blood and urine sodium concentrations, and the plasma and urine osmolality in 68 patients with ACI and 24 healthy control subjects. A total of 27 ACI patients were hyponatraemic and the majority of these had grievous or severely grievous craniocerebral injuries. Blood concentrations of EDLS and ADH in hyponatraemic ACI patients were significantly higher compared with normonatraemic ACI patients and control subjects. Blood EDLS and sodium concentrations were negatively correlated with each other, whereas EDLS was positively correlated with urine sodium concentration and with urine osmotic pressure. Hyponatraemic ACI patients require different treatment based on the cause of their central hyponatraemia, so it is important to undertake a comprehensive analysis of each patient's physiological status.

A Frequent Partial AZFc Deletion does not Render an Increased Risk of Spermatogenic Impairment in East Asians

The gene families in the AZFc region of the Y chromosome have been shown to be functionally important in human spermatogenesis. The gr/gr deletion, a partial AZFc deletion that reduces the copy numbers of all the AZFc gene families, was identified as a significant risk factor for spermatogenic impairment in Dutch, Spanish and Italians. However, the presence of this deletion in healthy French and Germans questioned its importance in male infertility. In this study, we have shown that the gr/gr deletion does not render an increased risk in Han Chinese. In fact, the gr/gr deletion is frequent (about 8%) in our survey of 886 East Asians from 8 ethnic groups. Furthermore, the DAZ1/DAZ2 deletion has been detected as the primary subtype of the gr/gr deletion in East Asians, though this doublet has been considered as crucial for normal spermatogenesis in Europeans. The different spermatogenic effects of various types of the partial AZFc deletion suggest that the functional difference between AZFc gene copies is a likely cause of inconsistent associations of the gr/gr deletion with spermatogenic impairment across populations.

Outcome of floppy Nissen fundoplication with intraoperative manometry to treat sliding hiatal hernia

The aim of this study was to evaluate the effectiveness of floppy Nissen fundoplication with intraoperative esophageal manometry. Between February 1992 and July 2004, there were 102 patients with sliding hiatal hernia undergoing transabdominal Nissen fundoplication. They were divided into three groups: 27 patients were in the Nissen group (CNF), 44 in the floppy Nissen group (FNF, including 5 with laparoscopic Nissen fundoplication), and 31 in the intraoperative-esophageal-manometry group (INF, 13 with laparoscopic Nissen fundoplication). There were no operation-related deaths. Operation-related complications occurred in five patients within 1 month after operation: In CNF, two patients suffered from dysphagia and one from regurgitation; in FNF, one patient had slight dysphagia and two had regurgitation; in INF, there was no one who complained about dysphagia or regurgitation, but pneumothorax occurred in one case. After more than 2 years of follow-up, two patients, in CNF, suffered from severe dysphagia, one recurred and two with abnormal 24 h pH monitoring. In FNF, one patient had dysphagia, one recurred and three had abnormal 24 h pH monitoring; in INF, two patients had acid reflux on 24 h pH monitoring. The postoperative lower esophageal sphincter pressure was in the normal range in 30 of 31 patients (96.5%). The normal rate of postoperative tests in CNF, FNF and INF were 81.5%, 86.4% and 93.5%, respectively. Both the Nissen fundoplication and the floppy Nissen fundoplication are effective approaches to treat patients with sliding hiatal hernia. Intraoperative manometry is useful in standardizing the tightness of the wrap in floppy Nissen fundoplication and may contribute to reducing or avoiding the occurence of postoperative complications.

C5 blockade with conventional immunosuppression induces long-term graft survival in presensitized recipients

We explored whether a functionally blocking anti-C5 monoclonal antibody (mAb) combined with T- and B-cell immunosuppression can successfully prevent antibody-mediated (AMR) and cell-mediated rejection (CMR) in presensitized murine recipients of life-supporting kidney allografts. To mimic the urgent clinical features of AMR experienced by presensitized patients, we designed a murine model in which BALB/c recipients were presensitized with fully MHC-mismatched C3H donor skin grafts one week prior to C3H kidney transplantation. Presensitized recipients demonstrated high levels of circulating and intragraft antidonor antibodies and terminal complement activity, rejecting grafts within 8.5 +/- 1.3 days. Graft rejection was predominantly by AMR, characterized by interstitial hemorrhage, edema and glomerular/tubular necrosis, but also demonstrated moderate cellular infiltration, suggesting CMR involvement. Subtherapeutic treatment with cyclosporine (CsA) and LF15-0195 (LF) did not significantly delay rejection. Significantly, however, the addition of anti-C5 mAb to this CsA/LF regimen prevented terminal complement activity and inhibited both AMR and CMR, enabling indefinite (>100 days) kidney graft survival despite the persistence of antidonor antibodies. Long-term surviving kidney grafts expressed the protective proteins Bcl-x(S/L) and A-20 and demonstrated normal histology, suggestive of graft accommodation or tolerance. Thus, C5 blockade combined with routine immunosuppression offers a promising approach to prevent graft loss in presensitized patients.

Bone marrow mesenchymal stem cells induce angiogenesis and attenuate the remodeling of diabetic cardiomyopathy

Independent of the severity of coronary artery disease, diabetic patients have an increased risk of developing heart failure. Diabetic cardiomyopathy (DCM) is characterized by microvascular pathologies and interstitial fibrosis. Mesenchymal stem cells (MSCs) are pluripotent and are able to differentiate into cardiomyocytes and vascular endothelial cells. Studies have demonstrated MSCs transplantation can prevent apoptosis of ischemic heart via upregulation of Akt and eNOS and inhibit myocardial fibrosis of dilated cardiomyopathy by decreasing the expression of matrix metalloproteinase (MMP) in rat models. In order to find out whether transplantation of MSCs is a promising treatment in DCM, we used streptozotocin (STZ) -induced diabetic rats as the model. Exogenous MSCs were injected into the femoral vein 8 weeks after STZ injection. Using independent experimental approaches, we showed that MSCs presented in the myocardium 4 weeks after transplantation and some of them were positive for the cardiac markers Troponin T and myosin heavy chain. MSCs transplantation significantly increased myocardial arteriolar density and decreased the collagen volume in diabetic myocardium resulting in improved cardiac function. Furthermore, MSCs transplantation increased MMP-2 activity and decreased transcriptional level of MMP-9. These results show that MSCs transplantation improved cardiac function in the rat DCM model, possibly through angiogenesis and attenuation of cardiac remodeling.

Ultrasound simulation of real-time temperature estimation during radiofrequency ablation using finite element models

Radiofrequency ablation is the most common minimally invasive therapy used in the United States to treat hepatocellular carcinoma and liver metastases. The ability to perform real-time temperature imaging while a patient is undergoing ablation therapy may help reduce the high recurrence rates following ablation therapy. Ultrasound echo signals undergo time shifts with increasing temperature due to sound speed and thermal expansion, which are tracked using both 1D cross correlation and 2D block matching based speckle tracking methods. In this paper, we present a quantitative evaluation of the accuracy and precision of temperature estimation using the above algorithms on both simulated and experimental data. A finite element analysis simulation of radiofrequency ablation of hepatic tissue was developed. Finite element analysis provides a method to obtain the exact temperature distribution along with a mapping of the tissue displacement due to thermal expansion. These local displacement maps were combined with the displacement due to speed of sound changes and utilized to generate ultrasound radiofrequency frames at specified time increments over the entire ablation procedure. These echo signals provide an ideal test-bed to evaluate the performance of both speckle tracking methods, since the estimated temperature results can be compared directly to the exact finite element solution. Our results indicate that the 1D cross-correlation (CC) method underestimates the cumulative displacement by 0.20mm, while the underestimation with 2D block matching (BM) is about 0.14 mm after 360 s of ablation. The 1D method also overestimates the size of the ablated region by 5.4% when compared to 2.4% with the 2D method after 720 s of ablation. Hence 2D block matching provides better tracking of temperature variations when compared to the 1D cross-correlation method over the entire duration of the ablation procedure. In addition, results obtained using 1D cross-correlation diverge from the ideal finite element results after 7 min of ablation and for temperatures greater than 65 degrees C. In a similar manner, experimental results presented using a tissue-mimicking phantom also demonstrate that the maximum percent difference with 2D block matching was 5%, when compared to 31% with the 1D method over the 700 s heating duration on the phantom.

Interaction between zonal populations of articular chondrocytes suppresses chondrocyte mineralization and this process is mediated by PTHrP

OBJECTIVE

Articular cartilage is separated from subchondral bone by the tidemark and a calcified cartilage zone. Advancement of the calcified region and tidemark duplication are both hallmarks of osteoarthritis (OA). Currently the mechanisms controlling post-natal articular cartilage mineralization are poorly understood. The objective of this study is to test the hypothesis that cellular communication between different cartilage layers regulates articular chondrocyte mineralization.

DESIGN

Co-culture models were established to evaluate the interaction of chondrocytes derived from the surface, middle and deep zones of articular cartilage. The cultures were stimulated with triiodothyronine (T3) to promote chondrocyte hypertrophy. The effects of zonal chondrocyte interactions on chondrocyte mineralization were examined over time.

RESULTS

Co-culture of deep zone chondrocytes (DZCs) with surface zone chondrocytes (SZCs) suppressed the T3-induced increase in alkaline phosphatase (ALP) activity and related mineralization. Moreover, SZC-DZC co-culture was associated with a significantly higher parathyroid hormone-related peptide (PTHrP) expression when compared to controls. When PTHrP(1-40) was added to the DZC-only culture, it suppressed DZC ALP activity similar to the inhibition observed in co-culture with SZC. In addition, treatment with PTHrP reversed the effect of T3 stimulation on the expression of hypertrophic markers (Indian hedgehog, ALP, matrix metalloproteinases-13, Type X collagen) in the DZC cultures. Moreover, blocking the action of PTHrP significantly increased ALP activity in SZC+DZC co-culture.

CONCLUSION

Our findings demonstrate the role of zonal chondrocyte interactions in regulating cell mineralization and provide a plausible mechanism for the post-natal regulation of articular cartilage matrix organization. These findings also have significant implications in understanding the pathology of articular cartilage as well as devising strategies for functional cartilage repair.

Parameters controlling the gene-targeting frequency at the Sphingomonas species rrn site and expression of the methyl parathion hydrolase gene

AIMS

To investigate the key parameters controlling the exogenous methyl parathion hydrolase (MPH) gene mpd-targeting frequency at the ribosomal RNA operon (rrn) site of Sphingomonas species which has a wide range of biotechnological applications.

METHODS AND RESULTS

Targeting vectors with different homology lengths and recipient target DNA with different homology identities were used to investigate the parameters controlling the targeting frequency at the Sphingomonas species rrn site. Targeting frequency decreased with the reduction of homology length, and the minimal size for normal homologous recombination was >100 bp. Homologous recombination could succeed even if there were 3-4% mismatches; however, targeting frequency decreased with increasing sequence divergence. The Red recombination system could increase the targeting frequency to some extent. Targeting of the mpd gene to the rrn site did not affect cell viability and resulted in an increase of MPH-specific activity in recombinants.

CONCLUSIONS

Targeting frequency was affected by homology length, identity and the Red recombination system. The rrn site is a good target site for the expression of exogenous genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work is useful as a foundation for a better understanding of recombination events involving homologous sequences and for the improved manipulation of Sphingomonas genes in biotechnological applications.

The effects of a 3-year obesity intervention in schoolchildren in Beijing

BACKGROUND

Childhood obesity has become a health problem in urban areas in China. Intervention to reduce childhood obesity should be of high priority. School-based intervention programmes are needed to deal with the growing prevalence of childhood obesity in China.

METHODS

Five primary schools were selected randomly for this study in the Beijing urban area in China; two were allocated to the intervention group and three to the control group. A total of 2425 children (1029 children in intervention schools and 1396 children in control schools) took part in the study for 3 years. In the intervention group, children and their parents were involved in a programme of nutrition education and physical activity. Control school students followed their usual health and physical education curriculum with no extra intervention.

RESULTS

After the 3-year intervention, the prevalence of overweight and obesity were significantly lower in the intervention schools than in the control schools (overweight: 9.8% vs. 14.4%, P < 0.01; obesity: 7.9% vs. 13.3%, P < 0.01). The prevalence of overweight and obesity decreased by 26.3% and 32.5% in intervention schools respectively after intervention. The prevalence of overweight and obesity increased in control schools. There was also significant difference in body mass index between intervention and control schools (18.2 +/- 2.6 vs. 20.3 +/- 3.4, P < 0.01) after intervention. More non-obese children became obese in the control schools (7.0%) than in the intervention schools (2.4%) at end line (P < 0.01). Among the children who were obese at baseline, 49.2% remained obese at end line in intervention schools while 61.9% remained obese in control schools (P < 0.01).

CONCLUSIONS

Our study showed that an intervention programme could be feasible in schools in Beijing, China. The prevalence of overweight and obesity was reduced in schoolchildren in Beijing through an intervention focused on nutrition education and physical activity. Overweight and obesity children as well as normal weight children and their parents should be involved in such an intervention programme.

Surgical outcome after removal of idiopathic macular epiretinal membrane in young patients

PURPOSE

To report the clinical features of the eye of young patients with an idiopathic macular epiretinal membrane (ERM), and the visual outcomes after the surgical removal of the ERM.

METHODS

A retrospective review of the medical records of eight young patients (age, 23-39 years; mean, 32.5 years) with an idiopathic macular ERM was performed. The patients underwent vitrectomy and removal of the ERM with peeling of the internal limiting membrane (ILM). The pre- and postoperative visual acuity and intra- and postoperative complications were investigated.

RESULTS

Ophthalmoscopically, the ERMs in seven eyes were white, opaque, and dense, while one was grayish-white and less dense. A posterior vitreous detachment was not present and the ERM adhered strongly to the underlying retina in all eight eyes. The mean best-corrected visual acuity (BCVA) preoperatively was 20/140 (Snellen; range: 20/250-20/63), and the BCVA improved significantly to 20/30 (range: 20/40-20/20) postoperatively with an average follow-up of 14.6 months (range: 6-42 months; Wilcoxon sign-rank test, P<0.001). An improvement of >7 lines was observed in seven of eight eyes. A recurrence of an ERM without involving the macula was detected in one eye (12.5%).

CONCLUSIONS

The clinical features of the ERMs in young patients are different from those in elderly patients, eg, thicker, more adherent to the retina, and still attached to the vitreous. Vitrectomy and removal of ERM with ILM peeling are effective and safe surgical procedures. Removal of the ILM may minimize the recurrence of an ERM.

Diagnostic accuracy of tumour markers for malignant pleural effusion: a meta-analysis

BACKGROUND

The role of tumour markers such as carbohydrate antigen (CA) 125, CA 15-3, CA 19-9 and CYFRA 21-1 (a fragment of cytokeratin 19) in differentiating malignant pleural effusions (MPE) from benign effusions is not yet clear.

METHODS

After a systematic review of English language studies, sensitivity, specificity and other measures of accuracy of pleural concentrations of CA 125, CA 15-3, CA 19-9 and CYFRA 21-1 or their combinations in the diagnosis of MPE were pooled using random effects models. Summary receiver operating characteristic curves were used to summarise overall test performance.

RESULTS

Twenty-nine studies met the inclusion criteria for the analysis. The summary estimates of the sensitivity and specificity of these tumour markers were as follows: CA 125, 0.48/0.85; CA 15-3, 0.51/0.96; CA 19-9, 0.25/0.96; CYFRA 21-1, 0.55/0.91 for diagnosing MPE. The estimated summary receiver operating characteristic curves showed that the performance of pleural CA 125 and CA 19-9 measurement in the diagnosis of MPE was limited, whereas that of CA 15-3 and CYFRA 21-1 was better. When two or more of the above four tumour markers were combined, or combined with carcinoembryonic antigen, the sensitivity and specificity were all increased to different extents.

CONCLUSIONS

The current evidence does not recommend using one tumour marker alone for the diagnosis of MPE, but the combination of two or more tumour markers seems to be more sensitive. The results of tumour marker assays should be interpreted in parallel with clinical findings and the results of conventional tests.

Distribution and characteristics of hepatitis B virus genotype C subgenotypes in China

Genetic diversity within the same hepatitis B virus (HBV) genotype indicates the presence of several subgenotypes. We have found that genotype C is the most common in China, and this study aimed to determine the geographical distribution and characteristics of HBV-C subgenotypes in the country. A cohort of 534 patients with chronic HBV genotype C infection, collected across China, was analysed by nucleotide sequencing or polymerase chain reaction-restriction fragment length polymorphism. HBV-C1/Cs (n = 112, 21%) and HBV-C2/Ce (n = 397, 74%) were the most common HBV-C subgenotypes and showed different geographical distribution in China. No significant differences were found between patients infected with HBV-C1 and HBV-C2 when comparing liver function tests, hepatitis B e antigen positive rate and clinical manifestations. We identified two other types of HBV-C provisionally designated as HBV-CD1 and HBV-CD2, which have particular virological features and clustered in one geographic area. These two types of C/D hybrids have emerged through recombination with genotype D and encode serotype ayw2 hepatitis B surface antigen. In conclusion, there are at least four subtypes of HBV genotype C: subgenotypes C1, C2 and two types of C/D recombinants CD1 and CD2 in China, which have a distinct geographic distribution. Whether HBV-C subgenotypes differ in their impact on liver disease progression requires prospective studies.