Diagnosis of spinal dural arteriovenous fistula: a multimodal MRI assessment strategy

AIM

To identify more specific screening indicators at magnetic resonance imaging (MRI) for the diagnosis of spinal dural arteriovenous fistulas (SDAVFs) and to determine an efficient diagnostic strategy.

MATERIALS AND METHODS

This retrospective study analysed clinical and imaging data of patients diagnosed with SDAVF and alternative myelopathy who underwent conventional MRI examinations. Additionally, three-dimensional (3D) T2-weighted sampling perfection with application-optimised contrasts using different flip-angle evolutions (3D-T2-SPACE) and contrast-enhanced magnetic resonance angiography (CE-MRA) data from patients with SDAVF were compared with digital subtraction angiography (DSA) data.

RESULTS

The age of onset, perimedullary flow voids (PFV), distribution of lesions, syringomyelia, degree of spinal oedema, and cauda equina disorder (CED) were factors that showed statistically significance in the identification of SDAVF with alternative myelopathy. After controlling for age, gender, PFV, degree of spinal cord swelling, and syringomyelia, the multivariable ordinal logistic regression model showed that the CED sign (OR = 32.46; 95% confidence interval [CI]: 2.47-427.15; p=0.008) was an independent predictor for SDAVF. The diagnostic model constructed using the PFV and CED signs had better diagnostic performance, with an area under the curve of 0.957 (p<0.001), maximum Youden index of 0.844, sensitivity of 92.9%, and specificity of 91.5%. Both 3D-T2-SPACE (77.8%) and CE-MRA (83.3%) sequences had good localisation values for SDAVF. Combining the two imaging examinations had better diagnostic accuracy than that of DSA.

CONCLUSION

CED and PFV on conventional MRI were specific indicators for the diagnosis of SDAVF. To compensate for the lack of fistula localisation on conventional MRI, 3D-T2-SPACE and CE-MRA can be used. Together they complement each other and have good diagnostic potential.

Tumor Treatment Response Assessed During the Concurrent Chemoradiotherapy for Nasopharyngeal Patients

PURPOSE/OBJECTIVE(S)

To evaluate intratumoral treatment response distribution with using FDG-PET/CT during the chemoradiotherapy of nasopharyngeal patients (NPC).

MATERIALS/METHODS

A total of 5 of 30 patients with stage III-IVA NPC were enrolled in the institutional protocol for induction/concurrent chemoradiotherapy with radiation dose of 70 Gy in 33 fractions. For each patient, a pre-radiation treatment FDG-PET/MRI image (SUV0) and a mid-treatment image (SUVm) at the treatment dose of 31.8 Gy were obtained. Followed by deformable PET/MRI registration between SUV0 and SUVm, the tumor voxel SUV reduction ratio was obtained to construct a tumor dose response matrix (DRM). Tumor SUVavid was also constructed by limiting tumor voxel SUVm > a given value. Spatial correlations of the tumor SUV0, SUVm, SUVavid and DRM were determined.

RESULTS

The mean and coefficient variation (CV) of the SUV0, SUVm and DRM for all tumors were 5.05 (52%), 2.72 (49%) and 0.64 (63%) (Table contains the individual data), which were smaller than those on the SUVs of head-n-neck HPV+ patients reported previously due to the induction chemotherapy, but had much larger DRM mean and CV. The inter-tumoral CVs of SUV0 and DRM were 29% and 27%, which were much lower than those of the intra-tumoral CVs 43% and 57%. Meanwhile, the intra-tumoral variations on SUV0 was smaller than the one of head-neck HPV+ patients, but the DRM intra-variation was much larger. There was a weak correlation between SUV0 and SUVm with the correlation coefficient 0.13, a medium correlation of -0.55 between SUV0 and DRM, but a strong correlation, 0.72, between SUVm and DRM. However, the spatial correlation between tumor DRM and SUVavid was getting weaker as the SUVavid value increasing and equal 0.47 with SUVavid value > 3.

CONCLUSION

The spatial dose response DRM for NPC in the concurrent chemoradiotherapy was relatively high, while had relatively low baseline tumor metabolic activity SUV0. It was most likely due to the induction chemotherapy. In addition, the tumor dose response showed vary large intra-tumoral variation. The high correlations between DRM and SUVm imply that SUVavid could be used partially to guide adaptive modification of NPC treatment with carefully selected boundary value.

Acute-on-chronic liver failure: clinical course and liver transplantation

INTRODUCTION

Acute-on-chronic liver failure (ACLF) is a clinical syndrome characterized by intense systemic inflammatory response, multiple-organ failures, and high short-term mortality in patients with chronic liver disease. ACLF is dynamic and heterogeneous, and the prognosis is closely related to the clinical course. Currently, liver transplantation (LT) remains the only potential curative treatment that improves survival of ACLF patients.

AREAS COVERED

In this review, we summarize the dynamic clinical course of ACLF and the relationship between the clinical course and the post-LT prognosis, especially the factors affecting the mortality after LT in severe ACLF patients and explore the optimal choice of LT therapy for ACLF patients, both to benefit patients the most and to avoid futile therapy.

EXPERT OPINION

ACLF is a dynamic disease with varying clinical phenotypes, and the global burden is high. Early identification of the clinical course is important to assess the prognosis and guide the treatment. The contradiction between shortage of liver donors and the large number of recipients makes it necessary for us to strictly screen out the recipients and identify patients who really need LT to save liver sources.

A novel polypeptide encoded by the circular RNA ZKSCAN1 suppresses HCC via degradation of mTOR

BACKGROUND

hsa_circ_0001727 (circZKSCAN1) has been reported to be a tumor-associated circRNA by sponging microRNAs. Intriguingly, we found that circZKSCAN1 encoded a secretory peptide (circZKSaa) in the liver. The present study aims to elucidate the potential role and molecular mechanism of circZKSaa in the regulation of hepatocellular carcinoma (HCC) progression.

METHODS

The circRNA profiling datasets (RNA-seq data GSE143233 and GSE140202) were reanalyzed and circZKSCAN1 was selected for further study. Mass spectrometry, polysome fractionation assay, dual-luciferase reporter, and a series of experiments showed that circZKSCAN1 encodes circZKSaa. Cell proliferation, apoptosis, and tumorigenesis in nude mice were examined to investigate the functions of circZKSaa. Mechanistically, the relationship between the circZKSaa and mTOR in HCC was verified by immunoprecipitation analyses, mass spectrometry, and immunofluorescence staining analyses.

RESULTS

Receiver operating characteristic (ROC) analysis demonstrated that the secretory peptide circZKSaa encoded by circZKSCAN1 might be the potential biomarker for HCC tissues. Through a series of experiments, we found that circZKSaa inhibited HCC progression and sensitize HCC cells to sorafenib. Mechanistically, we found that the sponge function of circZKSCAN1 to microRNA is weak in HCC, while overexpression of circZKSaa promoted the interaction of FBXW7 with the mammalian target of rapamycin (mTOR) to promote the ubiquitination of mTOR, thereby inhibiting the PI3K/AKT/mTOR pathway. Furthermore, we found that the high expression of cicZKSCAN1 in sorafenib-treated HCC cells was regulated by QKI-5.

CONCLUSIONS

These results reveal that a novel circZKSCAN1-encoded peptide acts as a tumor suppressor on PI3K/AKT/mTOR pathway, and sensitizes HCC cells to sorafenib via ubiquitination of mTOR. These findings demonstrated that circZKSaa has the potential to serve as a therapeutic target and biomarker for HCC treatment.

mTORi-based immunosuppression reduces HCC recurrence at the expense of increased adverse side effects: A systematic review and meta-analysis

Sirolimus and everolimus are mammalian target of rapamycin inhibitors (mTORi) that can reduce relapse rates following liver transplantation (LT) for hepatocellular carcinoma (HCC). Herein, we performed a systematic review and meta-analysis to investigate the efficacy of mTORi and calcineurin inhibitors (CNI) in reducing HCC recurrence and survival adverse effects (AEs) in HCC patients after LT. Systematic literature searches were conducted using MEDLINE, EMBASE, and Cochrane Library databases up to October 2021. The primary outcomes of interest were tumor recurrence rates and overall survival. The secondary outcomes were the characterization and incidence of AEs. A total of 38 trials involving 10,607 participants was included in the analysis. The incidence of recurrence and overall mortality was significantly lower in the mTORi than in the CNI group (relative ratio [RR]: .78, 95% confidence interval [CI]: .68-.89 and RR: .76, 95% CI: .67-.86, respectively). The incidence of some AEs and complications such as acne, anemia, abnormal healing, dyslipidemia, depression, diarrhea, edema, headache/migraine, hypercholesterolemia, incisional hernia, infection, leukopenia, mouth ulceration, pyrexia, proteinuria, pruritis, rash, and thrombocytopenia were higher in the mTORi than in the CNI group. mTORi reduced the recurrence incidence and overall 5-year mortality rate but increased many other incidences of AEs compared with that by CNI. Therefore, clinicians should be aware of the risks and benefits of mTORi use when managing patients undergoing LT for HCC.

Immunogenicity profiling and distinct immune response in liver transplant recipients vaccinated with SARS-CoV-2 inactivated vaccines

SARS-CoV-2 vaccination has been recommended for liver transplant (LT) recipients. However, our understanding of inactivated vaccine stimulation of the immune system in regulating humoral and cellular immunity among LT recipients is inadequate. Forty-six LT recipients who received two-dose inactivated vaccines according to the national vaccination schedule were enrolled. The clinical characteristics, antibody responses, single-cell peripheral immune profiling, and plasma cytokine/chemokine/growth factor levels were recorded. Sixteen (34.78%) LT recipients with positive neutralizing antibody (nAb) were present in the Type 1 group. Fourteen and 16 LT recipients with undetected nAb were present in the Type 2 and Type 3 groups, respectively. Time from transplant and lymphocyte count were different among the three groups. The levels of anti-RBD and anti-S1S2 decreased with decreasing neutralizing inhibition rates. Compared to the Type 2 and Type 3 groups, the Type 1 group had an enhanced innate immune response. The proportions of B, DNT, and CD3+CD19+ cells were increased in the Type 1 group, whereas monocytes and CD4+ T cells were decreased. High CD19, high CD8+CD45RA+ cells, and low effector memory CD4+/naïve CD4+ cells of the T-cell populations were present in the Type 1 group. The Type 1 group had higher concentrations of plasma CXCL10, MIP-1 beta, and TNF-alpha. No severe adverse events were reported in all LT recipients. We identified the immune responses induced by inactivated vaccines among LT recipients and provided insights into the identification of immunotypes associated with the responders.

[Clinical evaluation of vocal fold paralysis in 207 children]

Objective: To investigate the etiology and clinical characteristics of vocal fold paralysis in children. To provide useful information for diagnosis, management and prognosis in the clinical work. Methods: Two hundred and seven children with vocal fold paralysis in Children's Hospital of Fudan University were retrospectively studied, and followed-up. Results: All the patients had hoarseness.151 cases had vocal paralysis in the left side and the main etiology was pulmonary arterial hypertension.43 cases had bilateral vocal paralysis and all of them had respiratory problems.The main etiology were congenital tracheoesophageal malformations.13 cases had vocal paralysis in the right side.In terms of etiology, 8 cases were related to intracranial lesions, 2 cases were idiopathic. Conclusions: The main etiologies of left vocal fold paralysis were cardiovascular diseases, and bilateral vocal paralysis were congenital tracheoesophageal malformations.The main etiologies of right vocal fold paralysis were neoplastic and central lesion.The prognosis of bilateral vocal fold paralysis and right vocal fold paralysis was poor.

[Clinical research about needle-tract assisted standard percutaneous nephrolithotomy for the treatment of complicated upper urinary tract calculi]

Objective: To investigate the safety and efficacy of needle-tract assisted standard percutaneous nephrolithotomy (PCNL) for the treatment of complicated upper urinary tract calculi. Methods: The clinical data of 1 562 patients with complicated upper urinary calculi who received standard PCNL from December 2013 to December 2017 at Department of Urology, the First Affiliated Hospital of Xiamen University were retrospectively analyzed. There were large residual stones in 256 patients through B-ultrasound exploration after standard PCNL, could't be detected with nephoscope in standard PCNL tracts. 16 F mini PCNL tract were established in 120 cases for treatment of residual stones, while needle-tract were established in order to guide nephroscope to find residual stones in 126 cases. Needle-tract were transferred to 16 F mini PCNL tract for treatment of residual stones in 10 patients if these residual stones could't be detected through needle-tract. Operation time, change of hemoglobin level after operation, incidence of postoperative complications, time of hospitalization and rate of stone clearance were measured in two groups. The statistical methods used included t test, Wilcoxon rank sum test, and χ² test. Results: There were 1 to 3 mini tracts (M(Q_R): 1(1)) established in the mini tracts group and 1 to 7 needle-tracts (M(Q_R): 3(2)) established in the needle-tract group (Z=-10.57, P=0.000). Compared with mini tract group, the operation time ((62.0±18.0) minutes vs. (84.0±15.5) minutes, t=10.242, P=0.000), hospitalization time ((4.40±0.86) days vs. (5.20±0.81) days, t=7.570, P=0.049), hemoglobin dropped ((1.31±0.47) g/L vs. (2.74±0.63) g/L, t=20.12, P=0.000), and incidence of postoperative complications (7.9% (10/126) vs. 19.2% (23/120), χ²=6.674, P=0.01) of needle-tract group were lower, while postoperative stone clearance rate was higher (89.7% vs. 76.7%, χ²=7.497, P=0.006). No perioperative severe complications such as pleural injury, pneumatothorax, perforation of renal, trauma of abdominal organ occurred in two groups. Conclusion: Needle-tract assisted standard PCNL for the treatment of complicated upper urinary calculi can significantly improve stone clearance rate, reduce operation time, decrease risk of kidney and surrounding organs damage.

Pathogenicity characteristics of Enterococcus faecium from diseased black bears

The death of several black bears at the black bear breeding base in Yunnan Pingbian Daweishan is a matter of concern. Multiple black bears exhibited decreased appetite or unusual waste, and some were soporific or suffered from vomiting and anhelation. In order to ascertain the cause of death, 16S rDNA gene sequencing and phylogenetic analysis was performed on bacteria isolated from tissue samples obtained from dead bears. The biochemical characteristics of the isolated bacteria were subsequently analyzed using different biochemical test systems. The bacteria can decompose glucose, but it cannot produce gas. The fermentation study of sucrose, lactose, trehalose, glycerol and mannitol yielded positive results; while it was unable to decompose urea or ODC (ornithine decarboxylase). Basic Local Alignment Search Tool (BLAST) analysis of a ~1500-bp DNA product amplified from the 16S rDNA of the bacterial isolate revealed that Enterococcus faecium from black bears is highly similar to other E. faecium isolates in the National Center for Biotechnology Information (NCBI) database, and the highest sequence similarity (99%) was with the reference strain. In addition, mice infected with the E. faecium isolate succumbed to severe damage to the lungs, liver, spleen, myocardium, and kidney tissues. In summary, the isolated E. faecium from dead black bears induced pathological changes in mice.

Long non-coding RNA FOXD2-AS1 functions as a tumor promoter in colorectal cancer by regulating EMT and Notch signaling pathway

OBJECTIVE

A growing number of long noncoding RNAs (lncRNAs) are emerging as new modulators in cancer origination and progression. However, the functions and molecular mechanisms of lncRNAs to colorectal cancer (CRC) are still largely unknown. The aim of this study was to investigate the function and role of lncRNA FOXD2-AS1 (FOXD2-AS1) in human CRC.

PATIENTS AND METHODS

The expression of FOXD2-AS1 was investigated using Real-time reverse transcription-polymerase chain reaction (qRT-PCR) in 45 CRC specimens and matched adjacent normal tissues and CRC cell lines. MTT assays were conducted to explore the impact of FOXD2-AS1 knockdown on the proliferation of human CRC cells. The effects of FOXD2-AS1 on CRC cell migration and invasion were evaluated by cell invasion assays and migration assays. Western blot analysis was used to determine the expression levels of EMT-related and Notch-related proteins.

RESULTS

The results showed that FOXD2-AS1 expression was significantly increased in CRC tissues as well as in CRC cell lines. Moreover, down-regulation of FOXD2-AS1 suppressed cell, proliferation, invasion and migration in vitro. Importantly, we further confirmed that EMT and the Notch signaling pathway were inactivated in CRC cells after FOXD2-AS1 knockdown.

CONCLUSIONS

FOXD2-AS1 promoted the progression of CRC by regulating EMT and Notch signaling pathway. Thus, targeting FOXD2-AS1 may be an effective strategy for CRC treatment.

Risk factors for and management of ischemic-type biliary lesions following orthotopic liver transplantation: A single center experience

INTRODUCTION

Biliary complications can cause morbidity, graft loss, and mortality after liver transplantation. The most troublesome biliary complications are ischemic-type biliary lesions (ITBL), which occur since transplants can now be performed after the donor has undergone circulatory death. The exact origin of this type of biliary complication remains unknown.

MATERIAL AND METHODS

A total of 528 patients were retrospectively analyzed following liver transplantation after excluding 30 patients with primary sclerosing cholangitis and those lost to follow-up from January 2007 to January 2014. The incidence of and risk factors for ITBL were evaluated.

RESULTS

Cold ischemia time (CIT) (P = 0.042) and warm ischemia time (WIT) (P = 0.006) were found to be independent risk factors for the development of ITBL. Use of the cytochrome P450 (CYP) 3A5 genotype assay to guide individualization of immunosuppressive medications resulted in significantly fewer ITBL (P = 0.027. Autoimmune hepatitis might be a risk factor for ITBL, as determined using univariate analysis (P = 0.047).

CONCLUSIONS

Efforts should be taken to minimize risk factors associated with ITBL, such as CIT and WIT. The CYP3A5 genotype assay should be used to guide selection of immunosuppressive therapy in an effort to reduce the occurrence of ITBL.

[Detection of total and covalently closed circular HBV DNA in liver transplant recipients due to HBV-associated liver diseases]

OBJECTIVE

To investigate the levels of hepatitis B virus (HBV) total DNA and covalently closed circular (ccc) DNA in liver transplant recipients due to HBV-associated liver diseases and detemaine their clinical significance.

METHODS

Sixty patients undergoing liver transplantation (LT) due to HBV-associated liver diseases were enrolled for the study. Levels of HBV total and ccc DNA in plasma, liver and PBMCs were measured by RT-PCR.

RESULTS

The ratio of male:female participants was 48:12. The mean age was 52.98+/-9.40 years old, and the median duration post-LT was 72 (25-128) months. 59 of the patients had no detectable HBV DNA in plasma.Four patients had detectable levels of total HBV DNA in PBMCs, but no detectable ccc DNA. Five patients had detectable levels of total HBV DNA in liver, and two of those also had detectable levels of ccc DNA. One patients who had detectable HBV DNA in PBMCs suffered HBV recurrence.

CONCLUSION

The liver transplant recipients with detectable levels of HBV total and ccc DNA in PBMCs and liver should be considered high risk for HBV recurrence following LT.

Short-term effects of splenectomy on serum fibrosis indexes in liver cirrhosis patients

OBJECTIVE

To determine the changing patterns of 4 liver fibrosis markers pre and post splenectomy (combined with pericardial devascularization [PCDV]) and to examine the short-term effects of splenectomy on liver fibrosis.

METHODS

Four liver fibrosis markers of 39 liver cirrhosis patients were examined pre, immediately post, 2 days post, and 1 week post (15 cases) splenectomy (combined with PCDV).

RESULTS

The laminin (LN) level decreased immediately post surgery compared with the preoperative LN level (P < 0.05). The type IV collagen level decreased immediately post surgery compared with that pre surgery (P < 0.05), it significantly increased (P < 0.05) 2 days post surgery and significantly decreased 1 week post surgery (P < 0.05). Hyaluronic acid and the procollagen III N-terminal peptide levels increased significantly 2 days post surgery compared with that pre and immediately post surgery, they significantly decreased 1 week post surgery compared to 2 days post surgery (P < 0.05).

CONCLUSIONS

In the short-term, the 4 liver fibrosis markers and the FibroScans post splenectomy showed characteristic changes, splenectomy may transiently initiate the degradation process of liver fibrosis.

Three-dimensional printed trileaflet valve conduits using biological hydrogels and human valve interstitial cells

Tissue engineering has great potential to provide a functional de novo living valve replacement, capable of integration with host tissue and growth. Among various valve conduit fabrication techniques, three-dimensional (3-D) bioprinting enables deposition of cells and hydrogels into 3-D constructs with anatomical geometry and heterogeneous mechanical properties. Successful translation of this approach, however, is constrained by the dearth of printable and biocompatible hydrogel materials. Furthermore, it is not known how human valve cells respond to these printed environments. In this study, 3-D printable formulations of hybrid hydrogels are developed, based on methacrylated hyaluronic acid (Me-HA) and methacrylated gelatin (Me-Gel), and used to bioprint heart valve conduits containing encapsulated human aortic valvular interstitial cells (HAVIC). Increasing Me-Gel concentration resulted in lower stiffness and higher viscosity, facilitated cell spreading, and better maintained HAVIC fibroblastic phenotype. Bioprinting accuracy was dependent upon the relative concentrations of Me-Gel and Me-HA, but when optimized enabled the fabrication of a trileaflet valve shape accurate to the original design. HAVIC encapsulated within bioprinted heart valves maintained high viability, and remodeled the initial matrix by depositing collagen and glyosaminoglycans. These findings represent the first rational design of bioprinted trileaflet valve hydrogels that regulate encapsulated human VIC behavior. The use of anatomically accurate living valve scaffolds through bioprinting may accelerate understanding of physiological valve cell interactions and progress towards de novo living valve replacements.

Rapid 3D printing of anatomically accurate and mechanically heterogeneous aortic valve hydrogel scaffolds

The aortic valve exhibits complex three-dimensional (3D) anatomy and heterogeneity essential for the long-term efficient biomechanical function. These are, however, challenging to mimic in de novo engineered living tissue valve strategies. We present a novel simultaneous 3D printing/photocrosslinking technique for rapidly engineering complex, heterogeneous aortic valve scaffolds. Native anatomic and axisymmetric aortic valve geometries (root wall and tri-leaflets) with 12-22 mm inner diameters (ID) were 3D printed with poly-ethylene glycol-diacrylate (PEG-DA) hydrogels (700 or 8000 MW) supplemented with alginate. 3D printing geometric accuracy was quantified and compared using Micro-CT. Porcine aortic valve interstitial cells (PAVIC) seeded scaffolds were cultured for up to 21 days. Results showed that blended PEG-DA scaffolds could achieve over tenfold range in elastic modulus (5.3±0.9 to 74.6±1.5 kPa). 3D printing times for valve conduits with mechanically contrasting hydrogels were optimized to 14 to 45 min, increasing linearly with conduit diameter. Larger printed valves had greater shape fidelity (93.3±2.6, 85.1±2.0 and 73.3±5.2% for 22, 17 and 12 mm ID porcine valves; 89.1±4.0, 84.1±5.6 and 66.6±5.2% for simplified valves). PAVIC seeded scaffolds maintained near 100% viability over 21 days. These results demonstrate that 3D hydrogel printing with controlled photocrosslinking can rapidly fabricate anatomical heterogeneous valve conduits that support cell engraftment.

Cholinergic agonists attenuate renal ischemia-reperfusion injury in rats

Inflammation plays a significant role in the pathophysiology of renal ischemia-reperfusion injury. Local inflammation is modulated by the brain via the vagus nerve and nicotinic acetylcholine receptors such that electrical or pharmacologic stimulation of this cholinergic anti-inflammatory pathway results in suppression of proinflammatory cytokine production. We examined the effects of cholinergic stimulation using agonists, nicotine or GTS-21, given before or after bilateral renal ischemia-reperfusion injury in rats. Pretreatment of rats with either agonist significantly attenuated renal dysfunction and tubular necrosis induced by renal ischemia. Similarly, tumor necrosis factor-alpha protein expression and leukocyte infiltration of the kidney were markedly reduced following treatment with cholinergic agonists. We found functional nicotinic acetylcholine receptors were present on rat proximal tubule epithelial cells. Cholinergic stimulation significantly decreased tubular necrosis in vagotomized rats after injury, implying an intact vagus nerve is not required for this renoprotective effect.

[The development of a hemorrhologity observating and measuring instrument]

A new instrument for observing blood cell state and the process of variation on hemorrheology has been developed. There are three ways of shear rate: setting by hand, automatically setting and simulating pulsative state. It can provide different variable flow fields. The shear rate can be set in the range from 0.1 to 1000 s-1. It needs only a little blood. It can be easyly and rapidely operated. it has clear images. The hemorrheology state of blood cells can be directly perceived through thd instrument by eyes. The display and measurement and record of blood cell's hemorrheology state can be finished in real time dynamically and simultaneously.

[The development of a multifunction shear flow field generating device]

A new shear flow field generating device has been developed. It can be widely used in the basic research of hemorheology, clinical test and measurement. It has rich functions and can make dynamic measurement of hemorheology parameters. There are three work ways of shear rate: setting by hand, automatically setting and simulating pulsative state. It can provide different variable flow fields. The shear rate can be set in the range from 0.1 to 1000 s-1.

[The research and design of a constant flow pump for clinical ultrasonic emulsification]

A constant flow pump for clinical ultrasonic emulsification is developed, According to request, its output rotational speed can be continuously changed from 0 to 40 revolutions per minute. It can stably infuses emulsion to operating area.

Pressure peaking in pulsatile flow through arterial tree structures

An analytical iterative scheme is presented for computing the local characteristics of pressure and flow waves as they progress along a tree structure and become modified by wave reflections. Results are obtained to illustrate the phenomenon of pressure peaking under two different sets of circumstances. In the first case, the propagation of a single harmonic wave along a simple tree is considered, where wave reflections modify the amplitude of the pressure wave as it travels. In the second case, the propagation of a composite wave along a tree with multiple branches is considered, where wave reflections modify the shape of the wave as it travels and cause it to peak. The results demonstrate unambiguously that the root cause of this phenomenon is wave reflections caused by stepwise decreases in admittance, as has been previously suggested, rather than due to nonlinear interactions, as has also been previously suggested. It is shown clearly that even when wave reflections combine linearly, they lead to considerable peaking in the pressure waveform.

Mechanics of wave reflections in a coronary bypass loop model: the possibility of partial flow cut-off

Local hemodynamics in a bypass loop model with dimensions typical of those in the human coronary circulation are studied, particularly with regards to the effects of wave reflections. While in a single vessel of such dimensions and a single source of wave reflections the effects would be insignificant, in a bypass loop the combination of a narrowed vessel with a converging junction and several reflection sites may produce wave reflections with significant effects on the pressure and flow distributions within the vessels forming the loop. Calculations to test this possibility were performed, based on D'Alembert's solutions of the wave equation and with a proposed matching scheme to deal with the converging junction. The results indicate that there are very large wave reflection effects at a frequency of 10 Hz, smaller but significant effects at 5 Hz, and some insignificant effects at 1 Hz. The results also indicate that partial flow cut-off may occur within the loop under some singular circumstances, whereby certain harmonic components of the incident wave are totally reflected. In the clinical setting these effects would detract from the efficiency of the bypass as a conduit, to a degree dependent on the degree of occlusion of the bypassed vessel. The choice of a larger diameter for the bypass appears to diminish this dependence and is thus on the whole favorable despite the contribution it makes to impedance mismatch at the junction.

Reflection coefficients in pulsatile flow through converging junctions and the pressure distribution in a simple loop

Analytical expressions for the reflection coefficients in pulsatile flow through converging junctions are derived by two independent methods and are used to study the effects of wave reflections on the pressure distribution in a simple vascular loop. A simulated physiological situation is used as an example in which the loop is formed by the combination of a bypass and a bypassed vessel, the relative diameter of the latter being varied in order to simulate a narrowing. The results demonstrate how, in the case of a converging junction, the effects of wave reflections on the pressure distribution in one vessel depend on conditions within the vessel itself as well as in the other. The new reflection coefficients take into account this interdependence of flow in the two vessels forming a converging junction, and are shown to be consistent with reflection coefficients commonly used in diverging junctions.

[Multi-locus DNA fingerprints using oligonucleotide probe (CAC)5/(GTG)5 in the Chinese population]

In order to test the practical applicability of oligonucleotide fingerprinting in China we have investigated unrelated individuals, family members and a pair of twins from the Beijing area using the probe (CAC)5/(GTG)5. Except for the monozygotic twins highly variable banding patterns were demonstrated as expected for the randomly selected individuals but also for the relatives. On the basis of an initial survey of 50 unrelated individuals the calculated probability for obtaining by chance two identical multilocus patterns is very small (less than 1.93 x 10(-13). Therefore it seems reasonable to conclude that like in caucasians, (CAC)5/(GTG)5 fingerprints are completely individual-specific also in this population. Therefore they have already been used successfully for identification purposes and paternity tests in many actual cases.

Secondary prevention of myocardial reinfarction with low dose aspirin

A clinical trial of secondary prevention of reinfarction with low dose aspirin is reported. 50 mg aspirin per day was administered in 216 case. 211 cases did not take aspirin or any other antiplatelet agents as a control group. The follow-up periods in the two groups were 19.4 +/- 12.6 mon and 20.7 +/- 13.0 mon, respectively. There were 175 males in the aspirin group and 137 males in the control group. The incidence of reinfarction was reduced by 65% and platelet aggregation was inhibited obviously in the aspirin group as compared to the control group in men, whereas no significant trends were observed in women.