Expression of interleukin-18 in a rat model of deep vein thrombosis

AIM

Interleukin-18 (IL-18) is an important proinflammatory cytokine. However, little is known about the roles of IL-18 in the process of venous thrombosis. This study aimed to investigate the roles of IL-18 during deep vein thrombosis (DVT).

METHODS

Fifty rats were randomly divided into 0 (control group), 12, 24, 36 and 48 h groups (10 rats in each group) by observation time. The inferior vena cava (IVC) was ligated to establish the DVT model. Serum samples were extracted to determine the levels of IL-18, tumor necrosis factor-alpha (TNF-α), thromboxane B2 (TXB2) and 6-keto-prostaglandin Fl alpha (6-keto-PG Flα) by enzyme-linked immunosorbent assay (ELISA). The weight and length of IVC was also measured.

RESULTS

The DVT model was successfully established by ligating IVC. The injury of vein endothelium was observed in the model groups. IL-18, TNF-α, TXB2, TXB2/6-keto-PG Flα levels and thrombus weight were significantly increased in the model groups as compared with the control group, and peaked at 24 h after IVC ligation. 6-keto-PG F1α slightly decreased in the model groups comparing with the control group. IL-18 was positively correlated with TNF-α, TXB2, TXB2/6-keto-PG Flα ratio and thrombus weight. However, IL-18 was negatively correlated with 6-keto-PG Flα. There was a positive correlation between TXB2/6-keto-PG Flα ratio and thrombus weight.

CONCLUSION

Serum IL-18 level increased in the process of DVT, which might impair venous endothelial cells and result in venous thrombosis. IL-18 might be a new potential therapeutic target of DVT prevention.

Proteasome inhibitors induce nucleolar aggregation of proteasome target proteins and polyadenylated RNA by altering ubiquitin availability

The ubiquitin-proteasome pathway is essential for most cellular processes, including protein quality control, cell cycle, transcription, signaling, protein transport, DNA repair and stress responses. Hampered proteasome activity leads to the accumulation of polyubiquitylated proteins, endoplastic reticulum (ER) stress and even cell death. The ability of chemical proteasome inhibitors (PIs) to induce apoptosis is utilized in cancer therapy. During PI treatment, misfolded proteins accrue to cytoplasmic aggresomes. The formation of aggresome-like structures in the nucleus has remained obscure. We identify here a nucleolus-associated RNA-protein aggregate (NoA) formed by the inhibition of proteasome activity in mammalian cells. The aggregate forms within the nucleolus and is dependent on nucleolar integrity, yet is a separate structure, lacking nucleolar marker proteins, ribosomal RNA (rRNA) and rRNA synthesis activity. The NoAs contain polyadenylated RNA, conjugated ubiquitin and numerous nucleoplasmic proteasome target proteins. Several of these are key factors in oncogenesis, including transcription factors p53 and retinoblastoma protein (Rb), several cell cycle-regulating cyclins and cyclin-dependent kinases (CDKs), and stress response kinases ataxia-telangiectasia mutated (ATM) and Chk1. The aggregate formation depends on ubiquitin availability, as shown by modulating the levels of ubiquitin and deubiquitinases. Furthermore, inhibition of chromosome region maintenance 1 protein homolog (CRM1) export pathway aggravates the formation of NoAs. Taken together, we identify here a novel nuclear stress body, which forms upon proteasome inactivity within the nucleolus and is detectable in mammalian cell lines and in human tissue. These findings show that the nucleolus controls protein and RNA surveillance and export by the ubiquitin pathway in a previously unidentified manner, and provide mechanistic insight into the cellular effects of PIs.

Effect of surface plasmon resonance on the optical activity of chiral metal nanogratings

We examine the mechanism responsible for the optical activity of a two-dimensional array of gold nanostructures with no mirror symmetry on a dielectric substrate. Measurements with different incident angles, polarizations and sample orientations allow us to reveal that observed polarization effect is enhanced by surface plasmon resonance. By performing numerical simulation with rigorous diffraction theory we also show that the grating chirality can be described in terms of the non-coplanarity of the electric field vectors at the front (air-metal) and back (substrate-metal) sides of the grating layer.

Identification of differentially transcribed genes in human lymphoblastoid cells irradiated with 0.5 Gy of gamma-ray and the involvement of low dose radiation inducible CHD6 gene in cell proliferation and radiosensitivity

PURPOSE

To identify candidate genes specifically involved in response to low-dose irradiation in human lymphoblastoid cells; to better clarify the role of the human chromodomain helicase DNA binding protein 6 gene (CHD6), one of these genes, in cell proliferation and radiosensitivity.

MATERIALS AND METHODS

DNA microarray technology was used to analyse global transcriptional profile in human lymphoblastoid AHH-1 cells at 4 h after exposure to 0.5 Gy of gamma-ray. Gene expression changes were confirmed by semi-quantitative reverse transcription--polymerase chain reaction (RT-PCR) and Northern blot. RNA interfering technology was employed to knock-down the CHD6 gene in A549 cells. Colony-forming ability was used to analyse radiosensitivity.

RESULTS

The microarray assay revealed a set of 0.5 Gy-responsive genes, including 30 up-regulated genes and 45 down-regulated genes. The up-regulated genes include a number of genes involved in: signal transduction pathways, e.g., STAT3, CAMKK2, SIRT1, CREM, MAPK3K7IP2 and GPR56; transcription or DNA-binding, e.g., CHD6, CRSP3, SNURF, SH2 domain binding protein 1 and MIZF. Some of the down-regulated genes are involved in: cytoskeleton and cell movement (WASF2, LCP1, MSN, NIPSNAP1, KIF2C); DNA replication and repair (MCM2, MCM3, MCM7 and XRCC-4). Radiation-increased expression of CHD6 was also found in A549 cells and HeLa cells. The sustained CHD6 induction was restricted to relatively low doses (0.2 Gy or 0.5 Gy), no change occurring after 4 Gy irradiation. Silencing of CHD6 mediated by siRNA increased the growth rate of A549 cells by 40 approximately 60%. Most importantly, silencing CHD6 led to an increased radioresistance of A459 cells to radiation doses up to 2 Gy, but barely affected the sensitivity of cells at 4 and 8 Gy.

CONCLUSION

This study has identified a set of genes responsive to 0.5 Gy of gamma-rays. CDH6 gene can be specifically up-regulated by low dose irradiation, and its inducible expression could be involved in a low dose hypersensitive response.

Using Associated Polymer Gels to Control Conformance for High Temperature and High Salinity Reservoirs

Abstract

Most reservoirs in the Zhongyuan oilfield are characterized by high temperature, high salinity, and serious heterogeneity. Extensive waterflooding in the reservoir has magnified the effect of these heterogeniuties. To improve the poor conformance, a new kind of gel was developed using a water-soluble hydrophobically associating polymer (AP). Effect of the concentration of AP, crosslinker, and additives on gelation time and gel strength were studied. Thermo-stability of the gel was evaluated and results show that the gel can still retain 75 ˜ 85% of its original strength under conditions of 95 °C and salinity of 150,000 mg/l after six months. Core flooding results have illustrated that the plugging efficiency of the gel is more than 90% for selected applications. Twenty-six wells were treated using the new AP gel in the Zhongyuan oilfield in 2003. The response of treated wells and connected producers is reviewed. The average injected gel volume was 1,100 m3 each well. These treatments have resulted in approximately 6,000 m3 (5,300 tons) of incremental oil. Selection criteria for the optimum type of wells to be treated and injection procedures are summarized from the 26 applications.

Introduction

Gel treatment has been proved to be a cost effective method to control conformance for mature water/CO2 floods reservoirs (1–4).Traditionally, partially hydrolyzed polyacrymide (HPAM) is used to synthesize these crosslinked polymer gels. However, the traditional polymer molecular structure of these polymers tends to degrade under high salinity or hardness conditions in the injected brine, resulting in a sharp drop in viscosity of the polymer solution(5–6). Also, high molecular weight polymer tends to be irreversibly degraded by high shear rates, such as those encountered in pumps in the near wellbore region. Therefore, the application of traditional polymers of this type in high temperature and high salinity reservoirs is limited.

Associating polymer (AP) is a new type of water-soluble polymer in which a small number of special hydrophobic molecular groups are directly attached to the polymer chain(5–10). In aqueous solution, the hydrophobic groups of these polymers can associate to minimize their exposure to the external fluid, resulting in a star type of large spatial network structures, as shown in Figure 1. The association results in an increase of the hydrodynamic size of polymer that increases solution viscosity. This polymer solution can have a high viscosity at a relatively low molecular weight and low concentration. This associated structure is reversible. The fluids tend to be thixotropici in nature (viscosity is reduced by increased shear rates).

Most reservoirs in the Zhongyuan oilfield have high salinity and temperature and serious heterogeneity(11). The harsh reservoir conditions limit the application of traditional polymer HPAM. Therefore, AP associated polymer gel was synthesized and evaluated to control conformance in the Zhongyuan oilfield.

Experiment Results

Synthesis of the AP Gel

AP Concentration Effect

Synthesized Mazai formation water was used to prepare the polymer solution and the gel was formed at 95 °C. After three days' aging, the gel viscosity was measured at a shear rate of 12 rpm.

Analysis of factors influencing the blood levels and activities of tissue-type plasminogen activator (t-PA)

This study aimed to correlate plasmatic tissue-type plasminogen activator (t-PA) levels and activity with parameters of artery blood flow and vessel walls, nail fold microcirculation, hemorheology, serum glucose, and lipids. Thirty healthy volunteers (female/male 12/18) aged 40-60 (average 46) were included in the study. In citrate venous blood, the following parameters were determined: carotid mean velocity, carotid intimal-medial-thickness (IMT), capillary circulation parameters, hemorheology index, serum glucose, and lipids. Analysis of data showed that t-PA concentration was positively and significantly correlated with total cholesterol, triglycerides, and serum glucose (P<0.05, P<0.05, and P<0.01), but t-PA activity showed no correlation with them; among the hemorheology factors investigated, t-PA concentration showed the strongest positive correlation with both whole blood viscosity and reduced blood viscosity at high and low shear rate separately (P<0.01), t-PA activity showed no correlation with any hemorheology factors; t-PA concentration showed no correlation with any investigated nail fold capillary parameters, whereas t-PA activity was significantly and negatively associated with capillary loop number (P<0.05); t-PA concentration and activity was not associated with values of carotid maximum intimal-medial-thickness (mIMT) and mean velocity or systolic, diastolic blood pressure (P>0.05). But subjects with mIMT 1.0 mm showed higher t-PA levels compared with those with mIMT < 1.0 mm (P<0.05) and decreased carotid mean velocity (P<0.01). These findings suggest that multiple vascular disease risk factors would influence the t-PA level; t-PA concentration does not parallelize with t-PA activity.

Model-based normalization for iterative 3D PET image reconstruction

We describe a method for normalization in 3D PET for use with maximum a posteriori (MAP) or other iterative model-based image reconstruction methods. This approach is an extension of previous factored normalization methods in which we include separate factors for detector sensitivity, geometric response, block effects and deadtime. Since our MAP reconstruction approach already models some of the geometric factors in the forward projection, the normalization factors must be modified to account only for effects not already included in the model. We describe a maximum likelihood approach to joint estimation of the count-rate independent normalization factors, which we apply to data from a uniform cylindrical source. We then compute block-wise and block-profile deadtime correction factors using singles and coincidence data, respectively, from a multiframe cylindrical source. We have applied this method for reconstruction of data from the Concorde microPET P4 scanner. Quantitative evaluation of this method using well-counter measurements of activity in a multicompartment phantom compares favourably with normalization based directly on cylindrical source measurements.

Augmentation of anterior vertebral body screw fixation by an injectable, biodegradable calcium phosphate bone substitute

STUDY DESIGN

A biomechanical study to evaluate the effects of a biodegradable calcium phosphate (Ca-P) bone substitute on the fixation strength and bending rigidity of vertebral body screws.

OBJECTIVES

To determine if an injectable, biodegradable Ca-P bone substitute provides significant augmentation of anterior vertebral screw fixation in the osteoporotic spine.

SUMMARY OF BACKGROUND DATA

Polymethylmethacrylate (PMMA) augmented screws have been used clinically; however, there is concern about thermal damage to the neural elements during polymerization of the PMMA as well as its negative effects on bone remodeling. Injectable, biodegradable Ca-P bone substitutes have shown enhanced fixation of pedicle screws.

METHODS

Sixteen fresh cadaveric thoracolumbar vertebrae were randomly divided into two groups: control (no augmentation) (n = 8) and Ca-P bone substitute augmentation (n = 8) groups. Bone-screw fixation rigidity in bending was determined initially and after 10(5) cycles, followed by pullout testing of the screw to failure to determine pullout strength and stiffness.

RESULTS

The bone-screw bending rigidity for the Ca-P bone substitute group was significantly greater than the control group, initially (58%) and after cyclic loading (125%). The pullout strength for Ca-P bone substitute group (1848 +/- 166 N) was significantly greater than the control group (665 +/- 92 N) (P < 0.01). Stiffness in pullout for the Ca-P bone substitute groups (399 +/- 69 N/mm) was significantly higher than the control group (210 +/- 51 N/mm) (P < 0.01).

CONCLUSION

This study demonstrated that augmentation of anterior vertebral body screw fixation with a biodegradable Ca-P bone substitute is a potential alternative to the use of PMMA cement.

[Studies on insulin-like growth factor I receptor in fetal rats with intrauterine growth retardation]

OBJECTIVE

This study was conducted to detect the localization of the insulin-like growth factor I receptor (IGF-I R) in the cells and tissues in the rats with intrauterine growth retardation (IUGR) and normal growth rats.

METHODS

21 pregnant rats were randomly divided into the experimental group (IUGR) (n = 12) and the control group (n = 9). Animal models for IUGR were established by clamping the uterine vasculature of pregnant rats for 20 minutes on day 14 of gestation. The control group rats were subjected to Sham-operation. On day 22 of gestation, fetal rats were delivered by cesarean section. Immunohistochemical assay was performed to detect the IGF-I R expression on liver and lung using specific polyclonal antibodies to rat IGF-I R.

RESULTS

In the experimental group, the IUGR rats' body weight, height, and the weight of their liver, lung and the placenta were significantly lower than those in the control group. In the IUGR rats' liver, the area ratio of IGF-I R was increased and the average gray level was decreased, compared with those in the control group. In the IUGR rats' lung, the area ratio of IGF-I R was increased, compared with that in the control group, but no difference of average gray level was observed between the two groups.

CONCLUSION

The increased expression of IGF-I R in rats with IUGR, may be due to the decrease of IGF-I and the compensative mechanism of the body.

The effect of stem modularity and mode of fixation on tibial component stability in revision total knee arthroplasty

The effect of stem length, diameter, and mode of fixation on the motion and stress transfer of a cemented tibial tray were evaluated for in 12 cadaver knees. There was a significant decrease in motion of the tibial tray with increasing press-fit stem length (75-150 mm) and increasing stem diameter (10-14 mm). Cemented tibial stems showed significantly less tray motion than uncemented stems. The short cemented stems produced tray stability equivalent to long press-fit stems. Although there was a trend for increased proximal tibial stress shielding with the use of cement and longer, wider stems, the trend was not statistically significant. Modular, press-fit stems can achieve tray stability similar to a smaller cemented stem and can avoid the potential problems with cement.

[The relationships of the serum concentrations of insulin-like growth factors in fetal rats with intrauterine growth retardation]

OBJECTIVE

To observe the alterations of serum insulin-like growth factor-I,-II (IGF-I, IGF-II) in rat fetus and to investigate the relationship of serum IGFs with intrauterine growth retardation (IUGR).

METHODS

21 pregnant SD rats were randomly divided into control group (n = 9) and experimental group (IUGR group, n = 12). On day 14 of gestation, the bilateral uterine arteries and veins of experimental group were clamped for 20 minutes to build the rat IUGR models and sham surgeries were performed on control group. Fetal serum concentrations of IGFs, birth weight, the length and weight of fetal liver, lung, brain and placenta of all rats in the two groups were measured and compared.

RESULTS

The serum concentrations of IGF-I,-II of IUGR group were 117.92 +/- 26.58 ng/ml and 223.19 +/- 33.35 ng/ml, respectively, which were significantly lower than those of control group (234.43 +/- 70.65 ng/ml and 397.74 +/- 23.69 ng/ml, respectively, P < 0.01). Likewise, birth weight, the length and weight of liver, lung, brain and placenta in IUGR group were significantly lower than those in control group (P < 0.05).

CONCLUSION

The decrease of fetal serum concentrations of IGF-I,-II may be one of the internal factors contributing to fetal IUGR, and IGFs may play an important role in fetal growth.

Effect of articular step-off and meniscectomy on joint alignment and contact pressures for fractures of the lateral tibial plateau

OBJECTIVES

To determine the effects of intraarticular step-off and lateral meniscectomy on the alignment of the articular axis, contact area, and pressures for lateral tibial plateau fractures.

DESIGN

Biomechanical cadaver study.

INTERVENTION

Six fresh cadaveric knees were used. A simulated split fracture of the lateral tibial plateau was reproducibly created by osteotomies, and articular step-offs of zero, one, two, four, and six millimeters were achieved by using support shims. The knee was loaded with 500 newtons in 0 degrees and 350 newtons in 30 degrees of flexion. A digital camera determined changes in the alignment of the articular axis, and F-Scan sensors were inserted into the medial and lateral joint compartments to determine the pressures and pressure distributions.

MAIN OUTCOME MEASUREMENT

Each specimen was tested at step-offs of zero, one, two, four, and six millimeters, with the presence or absence of the lateral meniscus. The changes in alignment of the articular axis, the contact area, and the average and maximum contact pressures for each condyle were obtained.

RESULTS

Increased articular step-off heights progressively increased valgus angulation and average and maximum contact pressures and progressively decreased contact areas in lateral compartment. At a six-millimeter step-off with 0 degrees of flexion, the valgus angle increased an average of 7.6 degrees, and average contact pressures and maximum contact pressures increased an average of 208 percent and 97 percent, respectively, and contact area decreased an average of 33 percent (p < 0.05). Meniscectomy increased valgus angles by an average of 38 percent and contact pressures by an average of 45 percent and decreased contact areas by 26 percent in the lateral compartment at the same articular step-off heights (p < 0.05).

CONCLUSION

The results of this study show the importance of decreasing articular step-off heights in treating lateral tibial plateau split fractures, particularly if a meniscectomy is performed.

Effect of posterior cut angle on tibial component loading

Although clinical studies have shown that posterior cut angle affects tibial component stability, biomechanical studies are lacking. Fifteen Sawbones tibiae were divided into 5 groups and prepared with 0 degrees , 3 degrees, 6 degrees, 9 degrees, and -5 degrees tibial surface cuts, and a tibial component was implanted with cement. Using a standard and then a highly congruent polyethylene insert, the knee was loaded at 0 degrees and 30 degrees of flexion. There were statistically significant increases in anterior micromotion of the standard polyethylene component for each increase in posterior slope cut angle, which increased for the highly congruent polyethylene component. The anterior slope cut (-5 degrees) led to significant posterior micromotion of the tibial polyethylene component. Increased posterior slope cut angle significantly decreased tibial anterior compressive strains and significantly increased tibial posterior compressive strains. The highly congruent insert significantly increased this posterior strain. The results indicate that cutting the articular surface of the tibia at a 0 degrees or 3 degrees posterior slope provides the greatest tibial component stability.

[The correlation of serum levels of insulin-like growth factors and intrauterine growth: report of a study in rats]

This animal experiment was designed to investigate the relationship of the serum insulin-like growth factors (IGFs) with fetal intrauterine growth. The serum concentrations of IGF-I, -II in 21 fetal rats were measuerd and their relationships with fetal birth weight, length and tissue weights of brain, lung, liver were analysed respecively. The results showed that both of the serum concentrations of IGF-I, -II were positively correlated (P < 0.01) with fetal birth weight, length and tissue weights of brain, lung, liver respectively. These data suggest that both IGF-I and IGF-II may play an important role in fetal intrauterin growth and their decreased concentrations in serum may be factors contributing to fetal intrauterine growth retardation.

A biomechanical comparison of Schuhli nuts or cement augmented screws for plating of humeral fractures

Schuhli locking nuts can be used in poor quality cortical bone to enhance fixation stability as an alternative to cement augmented screws. This study compared the fixation strength and stability of plate constructs using Schuhli locking nuts with standard screws and cement augmented screws for fixation of simulated humeral shaft fractures in a test model with osteoporosis. The constructs were tested in axial compression, 4-point bending, and torsion to determine fixation stability. The humeri were cycled in torsion (4.5 Nm) for 1000 cycles to simulate upper extremity use during the early postoperative period and retested for stability. The Schuhli locking nuts and cement augmented screws had significantly greater fixation stability than the standard screws before (range, 6-14 times greater) and after cycling in torsional loading (range, 3-3.6 times greater). Although cement augmented screws and Schuhli augmentation showed increased fixation stability compared with the standard screws in axial and 4-point bending before cycling (range, 1.3-1.4 times greater), this was not significant. Compared with Schuhli fixation, cement augmented screws showed no significant difference in fixation stability in all loading modes before and after cycling. Schuhli locking nuts offer the stability of cement augmentation while avoiding its potential adverse effects on fracture healing with extravasation and thermal necrosis.

New technique for treatment of unstable distal femur fractures by locked double-plating: case report and biomechanical evaluation

BACKGROUND

A comminuted, intra-articular distal femur fracture was surgically treated by the authors with a locked, double-plating technique because fixation stability could not be initially achieved by using a standard double-plating technique. The purpose of this study was to determine biomechanically whether a locked double-plate construct would enhance fixation stability compared with a nonlocked double-plate construct.

METHODS

Six matched pairs of mildly osteopenic femurs were selected and all had a reproducible intra-articular fracture pattern created. Each pair underwent fixation with either a double-plating construct or a locked, double-plating construct that was randomly assigned. The instrumented femurs were then mechanically tested in several loading modes to determine fixation stability. After initial testing, specimens were cyclically loaded and retested for stability.

RESULTS

The locked, double-plating construct provided significantly greater fixation stability than the standard double-plating construct in precycling and postcycling biomechanical testing.

CONCLUSION

The technique described is particularly applicable for severely comminuted fractures of the distal femur and fractures in osteopenic bone with poor screw purchase. It offers a simple alternative for enhancing fixation stability, which avoids the potential complications of methylmethacrylate-enhanced screw fixation.

Gelfoam as a barrier to prevent polymethylmethacrylate-induced thermal injury of the spinal cord: in vitro and in vivo studies in pigs

Gelatin sponge (Gelfoam; Upjohn, Kalamazoo, MI, U.S.A.) is commonly used as an interpositional barrier to shield the spinal cord from thermal injury during vertebral reconstruction with polymethylmethacrylate bone cement. The aim of this study was to record epidural and intradural temperatures during polymethylmethacrylate reconstruction of vertebral corpectomy defects. Three surgical techniques (subtotal corpectomy, total corpectomy with insertion of a Gelfoam barrier, and total corpectomy with no barrier) were compared in vivo and in vitro in a porcine model. As expected, total corpectomy defects cemented without a Gelfoam barrier produced the highest epidural temperatures in vivo (52.8 degrees C) and in vitro (58 +/- 2 degrees C). The Gelfoam barrier provided some protection against heat transfer, but peak temperatures and absolute temperature increases were significantly higher than in defects with an intact posterior cortex (p < 0.05). These results indicate that an intact posterior cortex provides the best protection against heat transfer, whereas the use of a Gelfoam barrier appears to provide only partial protection against thermal injury.

The use of an injectable, biodegradable calcium phosphate bone substitute for the prophylactic augmentation of osteoporotic vertebrae and the management of vertebral compression fractures

STUDY DESIGN

A biomechanical study comparing two materials for augmentation of osteoporotic vertebral bodies and vertebral bodies after compression fracture.

OBJECTIVES

To compare an injected, biodegradable calcium phosphate bone substitute with injected polymethylmethacrylate bone cement for strengthening osteoporotic vertebral bodies and improving the integrity of vertebral compression fractures.

SUMMARY OF BACKGROUND DATA

Injection of polymethylmethacrylate bone cement into fractured vertebral bodies has been used clinically. However, there is concern about thermal damage to the neural elements during polymerization of the polymethylmethacrylate bone cement as well as its negative effects on bone remodeling. Biodegradable calcium phosphate bone substitutes have been studied for enhancement of fixation in fractured vertebrae.

METHODS

Forty fresh osteoporotic thoracolumbar vertebrae were used for two separate parts of this study: 1) injection into osteoporotic vertebrae: intact control (n = 8), calcium phosphate (n = 8), and polymethylmethacrylate bone cement (n = 8) groups. Each specimen then was loaded in anterior compression until failure; 2) injection into postfractured vertebrae: calcium phosphate (n = 8) and polymethylmethacrylate bone cement (n = 8) groups. Before and after injection, the specimens were radiographed in the lateral projection to determine changes in vertebral body height and then loaded to failure in anterior bending.

RESULTS

For intact osteoporotic vertebrae, the average fracture strength was 527 +/- 43 N (stiffness, 84 +/- 11 N/mm), 1063 +/- 127 N (stiffness, 157 +/- 21 N/mm) for the group injected with calcium phosphate, and 1036 +/- 100 N (stiffness, 156 +/- 8 N/mm) for the group injected with polymethylmethacrylate bone cement. The fracture strength and stiffness in the calcium phosphate bone substitute group and those in the polymethylmethacrylate bone cement group were similar and significantly stronger than those in intact control group (P < 0.05). For the compression fracture study, anterior vertebral height was increased 58.5 +/- 4.6% in the group injected with calcium phosphate and 58.0 +/- 6.5% in the group injected with polymethylmethacrylate bone cement as compared with preinjection fracture heights. No significant difference between the two groups was found in anterior vertebral height, fracture strength, or stiffness.

CONCLUSION

This study demonstrated that the injection of a biodegradable calcium phosphate bone substitute to strengthen osteoporotic vertebral bodies or improve vertebral compression fractures might provide an alternative to the use of polymethylmethacrylate bone cement.

[Effect of anti-opioid peptide sera on the enhancement of electroacupuncture analgesia induced by neurotensin in PAG of rats]

With the use of potassium iontophoresis induced tail-flick for measuring the pain threshold, the effects of injecting neurotensin (NT), naloxone (NX), anti-metenkephalin serum (AMEKS), anti-beta-endorphin serum (AEPS) and anti-dynorphin A1-13 serum (ADYNS) into periaqueductal gray (PAG) on electroacupuncture (EA) analgesia in rats were investigated. NT administration enhanced EA analgesia remarkably. Pre-injection of NX, AMEKS and AEPS into PAG could significantly attenuate the enhancement of EA analgesia induced by NT, but not by administration of ADYNS. The results indicate that NT in PAG is responsible for the enhancement of EA analgesia. The effect of NT may be partly mediated by met-enkephalin and beta-endorphin.

[Studies on immunoprotection of monoclonal antibodies against Cryptosporidium parvum]

AIM

To explore the immune protection of the monoclonal antibody (McAb) against Cryptosporidium parvum.

METHODS

On the basis of Madin-Darby canine kidney (MDCK) cell culture, the immunoprotection of McAb against C. parvum was screened by means of neutralization test in vitro, and verified by rat model and transmission electron microscopy of infected MDCK cells.

RESULTS

The number of C. parvum sporozoites recovered on the surface of rat intestinal epithelial cells and the mean output of oocyst were significantly reduced by McAb Z3D2 (P < 0.001, P < 0.05). The decreased Cryptos poridium at each development phase within infected MDCK cells and less damage of cell ultrastructure caused by Cryptosporidium were found in Z3D2 treated group.

CONCLUSION

McAb Z3D2 possesses highly effective protection against C. parvum.

[The role of periaqueductal gray neurotensin in electroacupuncture analgesia]

The effect of periaqueductal gray (PAG) injection of neurotensin (NT), anti-NT serum (ANTS), and naloxone (Nx) on both the pain threshold and electroacupuncture (EA) analgesia in rat was investigated in this study. The potassium iontophoresis-induced tail-flick was used to measure the pain threshold. NT administration induced an increase in pain threshold and enhanced EA analgesia. Injection of ANTS reduced the pain threshold significantly and diminished the effect of EA analgesia. Furthermore, pre-injection of Nx into PAG could weaken analgesia effect of NT and NT-EA analgesia. These results indicate that NT in PAG is involved in pain modulation and plays a role in EA analgesia. The effect of NT may be partly conducted by endogenous opiate peptides.

[Total hip replacement in patients with steroid-induced femoral head necrosis]

In order to evaluate the long-term effect of total hip replacement (THR) in patients with steroid-induced femoral head necrosis, 40 cases of 50 hips received THR patients were followed up for an average of 8.5 years after operation. Evaluation was carried act according to Harris score system. In these cases, average score was seventy-five points. Revision rate among them was 2% after four years and 18% after five to eight and a half years, with as overall rate of 20%. It was found that the main reason for revision was looseness of the prosthesis. In this follow-up, it showed that besides foreigen body reaction, abnormal osseous remodelling was the main factor in long-term failure of this arthroplasty. It was also proved that it was a good selection to perform cemented total hip replacement in younger patients, which could improve living quality.

Electron spin resonance determination and superoxide dismutase activity in polymorphonuclear leukocytes in congestive heart failure

Electron spin resonance spin trapping technique was used to measure the generation of active oxygen free radicals during the respiratory burst of phorbol myristate acetate-stimulated leukocytes, and the superoxide dismutase activity in healthy subjects and in patients with congestive heart failure. The authors also measured the concentration of peroxidation products (primarily malondialdehyde) by the thiobarbituric acid method. Experimental results showed that the electron spin resonance spectra obtained during the respiratory burst of polymorphonuclear leukocytes stimulated with phorbol myristate acetate primarily were those of the spin adduct of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) with the superoxide anion and to a lesser extent those of DMPO with hydroxyl radical. Compared with healthy subjects, the release of oxygen free radicals in the respiratory burst of polymorphonuclear leukocytes stimulated with phorbol myristate acetate and the concentration of thiobarbituric acid reactive product in plasma were significantly increased in patients with congestive heart failure while the activity of superoxide dismutase was markedly lower. The increased production of oxygen free radicals by polymorphonuclear leukocytes and the decreased capability of antioxidative defences might play an important role in the generation and development of cardiac failure.

Ventromedial hypothalamic somatostatin may affect gastric somatostatin concentration in rats

Changes in the somatostatin-like immunoreactivity (SLI) concentrations in gastric antral mucosa were detected by RIA following microinjections of synthetic somatostatin (SS) or cysteamine (CSH) into the ventromedial nucleus of the hypothalamus (VMH). SLI concentrations in the antral mucosa were increased by 60.8% (p less than 0.001) and 42.3% (p less than 0.05), respectively, one and four hours after microinjection of somatostatin (0.5 microgram/0.5 microliter) into the VMH, and decreased by 32.6% (p less than 0.05) four hours after microinjection of cysteamine (15 microgram/0.5 microliter) into the VMH. Moreover, microinjection of somatostatin (0.5 microgram/0.5 microliter) into the VMH could only elicit an increase of 16.0% (p less than 0.05) in the SLI concentration in the antral mucosa one hour after bilateral subdiaphragmatic vagotomies, but still produced an increase of 120.0% (p less than 0.05) following celiac ganglionectomies. In conclusion, somatostatin (exogenous and endogenous) in the VMH seems to affect the gastric somatostatin levels via the vagal nerves.