Diagnostic performance of anti-citrullinated protein/peptide antibodies in juvenile idiopathic arthritis

The prevalence rates of anti-citrullinated protein/peptide antibodies (ACPAs) were investigated in a cohort of juvenile idiopathic arthritis (JIA) patients, and their diagnostic performances were compared. ACPAs, including anti-cyclic citrullinated peptide IgG (anti-CCP), anti-CCP IgG/IgA (anti-CCP3.1), citrullinated recombinant rat filaggrin antibodies (CPA), anti-mutated citrullinated vimentin (anti-MCV), and antibodies to citrullinated human IgG-derived peptides (RA/CP), were measured in the sera from 81 JIA patients. Serum samples from 55 children with other joint diseases or viral infections and 49 healthy donors were tested as controls. Of the 81 JIA patients, 7 (8.6%), 8 (9.9%), 17 (21.0%), 23 (28.4%), and 18 (22.2%) were found to be positive for anti-CCP, anti-CCP3.1, CPA, anti-MCV, and RA/CP, respectively, with specificities of 98.1, 95.1, 93.3, 84.6, and 86.5%. Analysis by subtype revealed that 7/7 (100%) of RF-positive polyarticular JIA patients tested positive at high serum levels for anti-MCV or RA/CP, and 5/7 (71.4%) were positive for anti-CCP, anti- CCP3.1, or CPA (P < 0.001, compared with controls). Eighteen of 81 JIA patients demonstrated joint erosions on radiographs and erosive arthritis occurred more often in ACPAs positive patients (P < 0.01). Our findings indicate that although ACPAs are not satisfactory screening biomarkers for JIA due to low sensitivity, ACPA measurement can aid in diagnosing RF-positive polyarticular JIA and identifying JIA patients with severe bone involvement. The diagnostic performance of each ACPA in JIA is different, and the careful selection of assays is necessary.

Effects of MK-801 concentration on cell proliferation in rats with focal cerebral ischemia-reperfusion

We explored the relationship between MK-801 concentration and neural stem cell proliferation in rats with focal cerebral ischemia-reperfusion (FCIR). A total of 60 male Sprague Dawley rats were randomized into control (six rats), sham-operation (six rats), operation (12 rats), and MK-801 groups. The MK-801 group comprised 36 rats that were subjected to different doses of MK-801 (0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 mg/kg). Suture occlusion was used to establish an ischemia reperfusion model of middle cerebral artery occlusion (MCAO); 30 min before establishing the FCIR model, the MK-801 group rats were intraperitoneally injected with different doses of MK-801, while the sham-operation and control groups were injected with normal saline. Seven days after model establishment, bromodeoxyuridine-positive cerebral cortex cells adjacent to the focus of infarction were labeled for immunohistochemistry. MK-801 at a concentration of 0.4 mg/kg prevented endogenous neural stem cell proliferation, and this inhibitory effect was strengthened with increasing MK-801 concentration, especially at concentrations greater than 0.8 mg/kg. MK-801 inhibits endogenous neural stem cell proliferation in rats with FCIR, and the inhibitory effect is strengthened with increasing MK-801 concentration.

Parallel enzyme-linked immunosorbent assay screening for human immunodeficiency virus among blood donors in five Chinese blood centres: a retrospective analysis

AIMS

To evaluate the strategy of parallel screening with different enzyme-linked immunosorbent assays (ELISA) among Chinese blood donors.

BACKGROUND

Parallel screening with ELISA has been the main strategy to detect human immunodeficiency virus (HIV) in blood donations in China for more than a decade. The performance of the strategy should be analysed.

METHODS

A total of 821,927 donations collected from five Chinese blood centres in 2008-2010 were tested using two third-generation ELISAs by different manufacturers licenced and confirmed by the Western blot (WB) in this study. The confirmatory positive predictive values (PPV), false positive rates (FPR), false negative rates (FNR) and potential risks for transfusion resulting from single or sequential ELISA screening were evaluated.

RESULTS

A total of 5318 (0·647%) of donations screened HIV reactive and were discarded. WB confirmatory results on 1668 available samples suggested that PPVs for dual ELISA, one round ELISA reactive and grey zone samples were 75·1, 0·7 and 0·5%, respectively. Eight out of 1124 one round ELISA reactive and 1 out of 195 grey zone samples were WB confirmed positive. All but one ELISA assay displayed comparable PPVs but variable FPRs and FNRs that differed by blood centre.

CONCLUSIONS

In the absence of nucleic acid testing (NAT), parallel ELISA screening prevented a substantial number of HIV infected donations from entering the Chinese blood supply. However, the loss of false positive donors should be re-evaluated especially given the frequently reported blood supply shortage in China.

Occult macrophage activation syndrome in systemic-onset juvenile idiopathic arthritic syndrome--a case report

Macrophage activation syndrome (MAS) is a severe and life-threatening complication of rheumatic disorders in children. We described a 9-year-old girl in whom MAS developed as a complication of systemic juvenile idiopathic arthritis (S-JIA) at onset with obvious hemophagocytosis presented in the marrow. She suffered from high fever and generalized rash subsequently joints swelling for two weeks before admission. Physical examination revealed mild cervical lymphadenopathy and hepatosplenomegaly. Laboratory findings were: abnormal liver enzymes, increased triglyceride and ferritin levels, anemia .Hyperplasia of hemophagocytic macrophages was remarkable in her bone marrow. Methylprednisolone and cyclosporin therapy resulted in clinical and laboratory improvement. It is unusual that hemophagocytosis presented in the marrow at onset of So-JIA without obvious abnormal coagulation profile, thrombocytopenia and leucopenia. It seemed that MAS may be occult at onset of SJIA. It may be integral to the pathogenesis of SJIA. The proper cyclosporine serum lever at the onset of MAS is as high as 200-300 ng/ml.

Primary immunodeficiency in south China: clinical features and a genetic subanalysis of 138 children

OBJECTIVES

We analyzed the clinical features of 138 patients with primary immunodeficiency (PID) and performed genetic testing on a subset of patients in order to complete gaps in research on PID in South China and thus improve pediatricians' ability to recognize and diagnose PID.

METHODS

We performed a retrospective analysis based on the medical records of PID patients hospitalized in our institution between May 1999 and June 2012. Gene sequencing was performed in 59 cases.

RESULTS

Children with PID usually present with fever and repeated infections that generally affect the respiratory and digestive tracts. Growth retardation is observed in some cases. Of the 138 patients, 113 were boys, median age at onset was 5 months (range, 0-119 months), and age at diagnosis was 10 months (2-159 months). A family history of repeated infection or death of family members in infancy because of recurrent infections was recorded in 20 cases (14.49%). Antibody defects were detected in 48 cases (34.78%), combined immunodeficiency disease in 45 cases (32.61%), and other well-defined immunodeficiency syndromes in 45 cases (32.61%). Of the 59 patients from the genetic subanalysis, 24 (15.94%) had a genetic mutation (x-linked agammaglobulinemia, 8 cases; severe combined immunodeficiency, 8 cases; hyperimmunoglobulin M syndrome, 3 cases; hyperimmunoglobulin E syndrome, 3 cases; chronic granulomatous disease, 2 cases). We detected 4 novel mutations. No relevant mutations were found in the remaining 35 cases.After treatment with intravenous immunoglobulin and anti-infectious agents, 16 patients died in hospital, and 5 cases died after discontinuing treatment (mortality, 15.22%).

CONCLUSIONS

In recent years, the number of patients with PID has risen gradually in South China. Genetic testing can confirm diagnosis. Since PID seriously affects children's quality of life, it is important to diagnose, treat, and intervene early.We hope our clinical and genetic analyses of children with PID can provide diagnostic guidance for clinicians.

PIV pictures of stream field predict haemolysis index of centrifugal pump with streamlined impeller

Previously it has been found by pump haemolysis testing that the flow rate has a remarkable effect on index of haemolysis (IH), while pressure head does not affect IH. Recent investigation with particle image velocimetry (PIV) technology has demonstrated that IH is directly related to the flow pattern of stream field in impeller vane channels. PIV is a visible approach showing the real flow status in the pump. The different positions of a tracer particle in two PIV pictures taken at 20 micros intervals decide the velocity value and direction. The velocity vectors of many particles draw the flow pattern of the stream field. The same pictures are taken at 2, 4 and 6 l min(-1) flow rates while the pressure head is kept unchanged at 100 mmHg; then the pictures are taken at 4 l min(-1) flow with different pressure heads of 80, 100 and 120 mmHg. Results reveal that the flow rate of 4 l min(-1) (IH = 0.030) has the best stream field, and neither turbulence nor separation can be seen. In other flow rates (IH: 0.048 - 0.082), there is obviously second flow. Meanwhile, no significant difference can be seen among the PIV pictures of different pressure heads pumped, which agrees with the results of haemolysis testing showing that pressure has no effect on pump haemolysis. It may be concluded that the haemolysis property of a centrifugal pump can be assessed approximately by PIV pictures, which are much easier to take than haemolysis tests.

World-smallest LVAD with 27 g weight, 21 mm OD and 5 l min-1 flow with 50 mmHg pressure increase

To investigate the feasibility of a long-term left ventricular assist device (LVAD) placed in the aortic valve annulus, an implantable aortic valve pump (21 mm outer diameter, weighing 27 g) was developed. The device consists of a central rotor and a stator. The rotor assembly incorporates driven magnets and an impeller. The stator assembly has a motor coil with an iron core and outflow guide vanes. The device is to be implanted identically to an aortic valve replacement, occupying no additional anatomic space. The pump delivers the blood directly from left ventricle to the aortic root, like a natural ventricle, therefore causing less physiologic disturbance to the natural circulation. Neither connecting conduits nor 'bypass' circuits are necessary. The pump is designed to cycle between a peak flow and zero net flow to approximate systole and diastole. Bench testing indicates that the pump can produce a blood flow of 5 l min(-1) with 50 mmHg pressure increase at 17,500 rpm. At zero net flow rate, the pump can maintain a diastole aortic pressure against 80 mmHg at the same rotating speed.

An improved design of axially driven permanent maglev centrifugal pump with streamlined impeller

BACKGROUND

In 1839, Earnshaw proved theoretically that it is impossible to achieve a stable equilibrium with a pure permanent maglev. Furthermore, in 1939, Braunbeck deduced that it is only possible to stabilize a super conductive or an electric maglev. In 2000, however, the present authors discovered that stable levitation is achievable by a combination of permanent magnetic and nonmagnetic forces, and its stability can be maintained even with mere passive magnetic forces by use of the gyro-effect.

DESIGN CONCEPTS

An improved design of permanent maglev impeller pump has been developed. Passive magnetic (PM) bearings support the rotor radially; on its right side, an impeller is fixed and on its left side a motor magnets-assemble is mounted. Unlike a previous prototype design, in which the rotor magnets were driven by a motor via magnetic coupling, a motor coil is installed opposite to the motor magnets disc, producing a rotating magnetic field. At standstill or if the rotating speed is lower than 4000 rpm, the rotor has one axial point contact with the motor coil. The contact point is located at the centre of the rotor. As the rotating speed increases gradually to higher than 4000 rpm, the rotor will be drawn off from the contact point by the hydrodynamic force of the fluid. Then the rotor becomes fully suspended.

KEY POINTS OF STABILIZATION

For radial and peripheral stabilization, a gyro-effect is important, which is realized by designing the motor magnets disc to have large diameter, short length and high rotating speed; for axial stability, an axial rehabilitating force is necessary, which is produced by PM bearings.

RESULTS

The rotor demonstrated a full levitation by rotation over 4000 rpm. As a left ventricular assist device, the rotation of the pump has a speed range from 5000 to 8000 rpm. The relation between pressure head and flow rate indicates that there is neither mechanical friction nor hydrodynamic turbulence inside the pump; the former is due to the frictionless maglev and the latter is a result of the streamlined design of the impeller.

Novel totally implantable trans-ventricular and cross-valvular cannular pump with rolling bearings and purge system for recovery therapy

In the early 1990s, Yamazaki et al. developed a partly intra-ventricular pump, which was inserted into the left ventricle via the apex and then into the aorta through the aortic valve. The pump delivered blood flow directly from the left ventricle to the aorta, like a natural heart, and needed no inflow and outflow connecting tubes; it could be weaned off after the left ventricle had been recovered. The shortcomings were that the driving DC motor remained outside of the ventricle, causing an anatomic space problem, and the sealing and bearing were not appropriate for a durable device. Recently, a totally implantable trans-ventricular pump has been developed in the authors' laboratory. The device has a motor and a pump entirely contained within one cannula. The motor has a motor coil with iron core and a rotor with four-pole magnet; the pump has an impeller and an outflow guide vane. The motor part is 60 mm in length and 13 mm in diameter; the pump part is 55 mm in length and 11 mm in diameter. The total length of the device is therefore 115 mm. The total weight of the device is 53 g. The motor uses rolling bearing with eight needles on each side of the rotor magnets. A special purge system is devised for the infusion of saline mixed with heparin through bearing to the pump inlet (30 - 50 cc per hour). Thus neither mechanical wear nor thrombus formation along the bearing will occur. In haemodynamic testing, the pump can produce a flow of 4 l min-1 with 60 mmHg pressure increase, at a pump rotating speed of 12,500 rpm. At zero flow rate, corresponding to the diastolic period of the heart, the pump can maintain aortic blood pressure over 80 mmHg at the same rotating speed. This novel pump can be quickly inserted in an emergency and easily removed after recovery of natural heart. It will be useful for patients with acute left ventricular failure.

Computational fluid dynamics verified the advantages of streamlined impeller design in improving flow patterns and anti-haemolysis properties of centrifugal pump

Computational fluid dynamics (CFD) technology was applied to predict the flow patterns in the authors' streamlined blood pump and an American bio-pump with straight vanes and shroud, respectively. Meanwhile, haemolysis comparative tests of the two pumps were performed to verify the theoretical analysis. The results revealed that the flow patterns in the streamlined impeller are coincident with its logarithmic vanes and parabolic shroud, and there is neither separate flow nor impact in the authors' pump. In the bio-pump, the main flow has the form of logarithmic spiral in vertical section and parabola in cross section, thus there are both stagnation and swirl between the main flow and the straight vanes and shroud. Haemolysis comparative tests demonstrated that the authors' pump has an index of haemolysis of 0.030, less than that of the bio-pump (0.065).

New concepts and new design of permanent maglev rotary artificial heart blood pumps

According to tradition, permanent maglev cannot achieve stable equilibrium. The authors have developed, to the contrary, two stable permanent maglev impeller blood pumps. The first pump is an axially driven uni-ventricular assist pump, in which the rotor with impeller is radially supported by two passive magnetic bearings, but has one point contact with the stator axially at standstill. As the pump raises its rotating speed, the increasing hydrodynamic force of fluid acting on the impeller will make the rotor taking off from contacting point and disaffiliate from the stator. Then the rotor becomes fully suspended. The second pump is a radially driven bi-ventricular assist pump, i.e., an impeller total artificial heart. Its rotor with two impellers on both ends is supported by two passive magnetic bearings, which counteract the attractive force between rotor magnets and stator coil iron core. The rotor is affiliated to the stator radially at standstill and becomes levitated during rotation. Therefore, the rotor keeps concentric with stator during rotation but eccentric at standstill, as is confirmed by rotor position detection with Honeywell sensors. It concludes that the permanent maglev needs action of a non-magnetic force to achieve stability but a rotating magnetic levitator with high speed and large inertia can maintain its stability merely with passive magnetic bearings.

Study on stable equilibrium of levitated impeller in rotary pump with passive magnetic bearings

It is widely acknowledged that the permanent maglev cannot achieve stable equilibrium; the authors have developed, however, a stable permanent maglev centrifugal blood pump. Permanent maglev needs no position detection and feedback control of the rotor, nevertheless the eccentric distance (ED) and vibration amplitude (VA) of the levitator have been measured to demonstrate the levitation and to investigate the factors affecting levitation. Permanent maglev centrifugal impeller pump has a rotor and a stator. The rotor is driven by stator coil and levitated by two passive magnetic bearings. The rotor position is measured by four Hall sensors, which are distributed evenly and peripherally on the end of the stator against the magnetic ring of the bearing on the rotor. The voltage differences of the sensors due to different distances between the sensors and the magnetic ring are converted into ED. The results verify that the rotor can be disaffiliated from the stator if the rotating speed and the flow rate of the pump are large enough, that is, the maximal ED will reduce to about half of the gap between the rotor and the stator. In addition, the gap between rotor and stator and the viscosity of the fluid to be pumped also affect levitation. The former has an optimal value of approximately 2% of the radius of the rotor. For the latter, levitation stability is better with higher viscosity, meaning smaller ED and VA. The pressure to be pumped has no effect on levitation.

World-first implantable aortic valvo-pump (IAVP) with sufficient haemodynamic capacity

For better anatomic and physiologic fitting, a novel implantable aortic valvo-pump (IAVP) has been developed. A valvo-pump is a micro axial flow impeller pump, which has the same dimensions and function, as well as the same location, of a valve. Therefore, IAVP needs no inlet and outlet tubes, no additional anatomic occupation, and has less physiologic disturbance to natural circulation compared with the traditional bypass left ventricular assist device (LVAD). The device has a stator and a rotor. The stator consists of a motor coil with an iron core and an outflow guide vane; the rotor includes driven magnets and impeller. There is neither bearing nor strut in both the pump and the motor. In order to reduce the attractive force between the rotor and the stator, so as to enhance the durability of the performance, the rotor magnets were minimized without reducing the driving torque and efficiency of the motor. The impeller vane was designed according to a three-dimensional and analytical method, for preventing stasis and turbulence. The largest outer diameter is 24.7 mm and the length at this point is 12.4 mm. The total weight is 40 g (including the rotor of 11 g). The consumed power is 7 W (14 V x 0.5 A) at 15 000 rpm. This rotating speed stays unchanged during haemodynamic testing together with a pulsatile centrifugal pump, which imitates a failing ventricle. The maximal flow cross IAVP reaches over 10 l min(-1) and the pressure head at 0 l min(-1) can be as large as 80 mmHg. At flow rate of 4 - 8 l min(-1), IAVP enlarges the flow c. 1 l min(-1) and meanwhile increases the pressure about 10 mmHg. The pressure pulsatility generated by the pulsatile centrifugal pump remains 40 mmHg after passing IAVP. By first animal experimental trial the device was sewed in aortic position of an 80 kg pig without harm to adjacent tissue and organs. IAVP promises to be a viable alternative to natural donor heart for heart transplantation in the future.

A novel permanent maglev rotary LVAD with passive magnetic bearings

It has been widely acknowledged that permanent maglev cannot achieve stability; however, the authors have discovered that stable permanent maglev is possible under the effect of a combination of passive magnetic and nonmagnetic forces. In addition, a rotary left ventricular assist device (LVAD) with passive magnetic bearings has been developed. It is a radially driven impeller pump, having a rotor and a stator. The rotor consists of driven magnets and impeller; the motor coil and pump housing form the stator. Two passive magnetic bearings counteract the attractive force between motor coil iron core and rotor magnets; the rotor thereafter can be disaffiliated from the stator and become levitated under the action of passive magnetic and haemodynamic forces. Because of the pressure difference between the outlet and the inlet of the pump, there is a small flow passing through the gap of rotor and stator, and then entering the lower pressure area along the central hole of the rotor. This small flow comes to a full washout of all blood contacting surfaces in the motor. Moreover, a decreased Bernoulli force in the larger gap with faster flow produces a centring force that leads to stable levitation of the rotor. Resultantly, neither mechanical wear nor thrombosis will occur in the pump. The rotor position detection reveals that the precondition of levitation is a high rotating speed (over 3250 rpm) and a high flow rate (over 1 l min(-1)). Haemodynamic tests with porcine blood indicate that the device as a LVAD requires a rotating speed between 3500 and 4000 rpm for producing a blood flow of 4 - 6 l min(-1) against 100 mmHg mean pressure head. The egg-sized device has a weight of 200 g and an O.D. of 40 mm at its largest point.