[Progress on treatment of acetabular quadrilateral plate injury]

Acetabular quadrilateral plate injury has become a hot spot and focus in the field of orthopaedic trauma and pelvic floor function in recent years. Although there are five fracture types,they are all based on fracture morphology,without considering the pulling force of ligaments,joint capsular and muscles. A perfect classification needs to describe the displacement of bone mass in three-dimensional space to better guide reduction and fixation. The seven incision and exposure methods are still the traditional open-eye surgery,and how to protect the criss-crossing vascular neural network and pelvic organs is still the focus. Quadrilateral defect causes dislocation of artificial hip joint,and quantitative evaluation of quadrilateral defect volume and revision techniques are still a hot topic. In this paper,the viewpoints of three-dimensional network structure of acetabular pelvic vascular anatomy,anatomical surgical target channel and fixation anchor point of acetabular fracture reduction are proposed to design new techniques for accurate and minimally invasive surgical operations,in order to realize the requirements of rapid orthopedic rehabilitation.

Crystallization mechanism of the Pt50Au50 alloy with grain boundary segregation during the solidification process

The crystalline mechanism of the Pt50Au50 alloy with grain boundary (GB) segregation during the rapid solidification process is investigated using molecular dynamics simulations. The cluster evolution and phase transformation processes during the GB segregation are analyzed by means of the energy temperature (E-T) curve, the pair distribution function (g(r)) curves, common neighborhood analysis (CNA), cluster-type index method (CTIM) and three-dimensional visualizing analyses. It is found that the GB segregation phenomenon of the Pt50Au50 alloy comes from various solidification temperatures of Pt- and Au-centered clusters. Four critical temperatures T1 (1153 K), T2 (1073 K), T3 (853 K) and T4 (753 K) are discovered during the liquid-solid transition, corresponding to the supercooled liquid, Pt-centered atom nucleation, Pt-centered cluster growth, Au-centered atom nucleation and grain growth process, respectively, which is observably different to the solidification process of other alloys. The Pt atoms begin to gather together in the high-temperature liquid before the liquid-solid transition. It is also found that the CTIM proposed by us would provide an effective tool to investigate the GB segregation process.

Belowground seed and bud banks play complementary roles in the potential recruitment of dominant macrophyte communities in a Yangtze River-connected floodplain wetland

Both seed and bud banks play important roles in the recruitment and maintenance of macrophyte communities; however, few studies have investigated them simultaneously. We investigated the abundance, species composition, and seasonal patterns of seed and bud banks in two dominant macrophyte communities, Carex and Miscanthus, in the Dongting Lake wetlands. The seed densities of both communities were lower from November (after flooding) to March and increased dramatically before flooding (in May). The bud densities of the two dominant communities peaked in the coldest month of the year (January), decreased markedly in March, and were the lowest before flooding. The seed banks of the two macrophyte communities were mainly composed of annual species and a few perennial species, whereas the bud banks were composed of only dominant perennials. Furthermore, the perennial species present in bud banks did not occur in seed banks. Among the soil variables, the bud densities of both plant communities were negatively associated with soil bulk density, whereas the seed density of the Miscanthus community was positively associated with soil bulk density. Our results suggest that seed and bud banks are complementary in the potential recruitment of macrophyte communities; that is, bud banks regulate the demography of dominant perennials, and seed banks contribute to the recruitment and dispersal of annual species. Given the high abundance of annuals and near absence of the most dominant perennials in the seed bank, the bud banks of dominant perennial species should be more widely used in wetland restoration and management.

Exploring the relative contribution of flood regimes and climatic factors to Carex phenology in a Yangtze River-connected floodplain wetland

Hydrological regimes can combine with climatic factors to affect plant phenology; however, few studies have attempted to quantify their complex influences on plant phenology in floodplain wetlands. We obtained phenological information on Carex vegetation through MODIS normalized difference vegetation index (NDVI) data during 2001-2020, and monthly field investigation during 2011-2020. We then explored how these data were correlated with climatic factors and flood regimes in a Yangtze River-connected floodplain wetland (Dongting Lake, China). Our results showed that warmer temperature tended to advance the start of the pre-flooding growing season (SOS1), with a relative contribution of 76.1 %. Flood rising time strongly contributed to controlling the end of the pre-flooding growing season. Flood recession time and inundation duration were dominant factors determining the start of the post-flooding growing season (SOS2). Earlier flood recession time and shortened inundation duration tended to advance the SOS2. Shortened inundation duration, earlier flood recession time, and lower solar radiation tended to advance the end of the post-flooding growing season. The phenology of Carex distributed at high-elevation areas was more affected by hydrology than that of Carex distributed at low-elevation areas. Thus, climatic factors strongly affect the phenology of Carex during the pre-flooding growing season, whereas flood regimes play a dominant role in determining the phenology in the post-flooding growing season. The different responses of Carex phenology to climatic and flooding factors may provide insights for the conservation and management of floodplain wetlands in Yangtze River because Carex are primary food source and habitat for herbivorous waterfowls.

Prognostic impact of tumor deposits on overall survival in colorectal cancer: Based on Surveillance, Epidemiology, and End Results database

BACKGROUND

In colorectal cancer, tumor deposits (TDs) are considered to be a prognostic factor in the current staging system, and are only considered in the absence of lymph node metastases (LNMs). However, this definition and the subsequent prognostic value based on it is controversial, with various hypotheses. TDs may play an independent role when it comes to survival and addition of TDs to LNM count may predict the prognosis of patients more accurately.

AIM

To assess the prognostic impact of TDs and evaluate the effect of their addition to the LNM count.

METHODS

The patients are derived from the Surveillance, Epidemiology, and End Results database. A prognostic analysis regarding impact of TDs on overall survival (OS) was performed using Cox regression model, and other covariates associating with OS were adjusted. The effect of addition of TDs to LNM count on N restaging was also evaluated. The subgroup analysis was performed to explore the different profile of risk factors between patients with and without TDs.

RESULTS

Overall, 103755 patients were enrolled with 14131 (13.6%) TD-positive and 89624 (86.4%) TD-negative tumors. TD-positive patients had worse prognosis compared with TD-negative patients, with 3-year OS rates of 47.3% (95%CI, 46.5%-48.1%) and 77.5% (95%CI, 77.2%-77.8%, P < 0.0001), respectively. On multivariable analysis, TDs were associated poorer OS (hazard ratio, 1.35; 95%CI, 1.31-1.38; P < 0.0001). Among TD-positive patients, the number of TDs had a linear negative effect on disease-free survival and OS. After reclassifying patients by adding TDs to the LNM count, 885 of 19 965 (4.4%) N1 patients were restaged as pN2, with worse outcomes than patients restaged as pN1 (3-year OS rate: 78.5%, 95%CI, 77.9%-79.1% vs 63.2%, 95%CI, 60.1%-66.5%, respectively; P < 0.0001).

CONCLUSION

TDs are an independent prognostic factor for OS in colorectal cancer. The addition of TDs to LNM count improved the prognostic accuracy of tumor, node and metastasis staging.

Concurrent effects of flooding regimes and floodwater quality on sediment properties in a Yangtze River-connected floodplain wetland: Insights from field investigations during 2011-2020

Changes in flood regimes, floodwater quality, and macrophyte types may affect sediment characteristics post-flooding. However, few studies have attempted to unravel their complex influences in floodplain wetlands. From 2011 to 2020, the physical and chemical properties of surface layer sediment pre- and post-flooding was investigated through field surveys in the Dongting Lake wetland. Results indicated that the pre-flooding soil total phosphorus (TP) and total nitrogen (TN) exhibited an increasing trend during 2011-2020. Soil TP increased post-flooding relative to that pre-flooding. The changes in TN, sediment organic matter (SOM), sediment moisture content (SMC), and sediment bulk density (SBD) fluctuated over the years. The best-fitting multi-regression model demonstrated that the changes in sediment variables post-flooding showed a parabolic trajectory along the inundation duration (ID), except for SMC. Changes in soil properties post-flooding were negatively correlated with ID for sediment with a low IDs (<148 days). Meanwhile, changes in soil properties post flooding were positively correlated with ID for sediment with a high IDs (>193 days). Changes in SBD and SOM post-flooding were positively influenced by the TP content in the floodwater. These findings indicate that changes in the flooding regime, and water quality generated by anthropogenic disturbances such as the Three Gorges Dam significantly affect sediment properties, and subsequently influence the ecological functions of the Dongting Lake wetland.

[Research advances of music therapy and its application in the field of burn treatment]

Different from other trauma, the scar and pigmentation formed after healing of burn wound not only hinder beauty but also easily lead to a series of sequential psychological problems, such as depression and anxiety. Music therapy, as a supplementary treatment, is widely used in many fields including medical and health care and psychological regulation. However, affected by factors such as medical resources, the awareness and acceptance of music therapy among burn treatment workers in China are still low. Based on the clinical characteristics of burns, this paper matches the applicability of music therapy with it, summarizes the supplementary application of music therapy in the field of burn treatment, expounds this natural science with both science and aesthetics, and puts forward feasible suggestions for its future development.

Predictive value of serum alpha-fetoprotein for tumor regression after preoperative chemotherapy for rectal cancer

BACKGROUND

Preoperative therapy is widely used in locally advanced rectal cancer. It can improve local control of rectal cancer. However, there are few indicators that can predict the effect of preoperative chemotherapy accurately.

AIM

To investigate whether the increase in serum α-fetoprotein (AFP) can predict better efficacy of preoperative chemotherapy.

METHODS

This was a retrospective study. We analyzed 125 patients admitted between 2017 and 2019 with locally advanced rectal cancer. All patients received six cycles of preoperative chemotherapy (mFOLFOX6 every 2 wk). Serum AFP of 26 patients rose slightly after three or four cycles of chemotherapy, and fell to normal again within 2 mo. The other 99 patients had a normal level of serum AFP during chemotherapy. Patients were divided into two groups (AFP risen and AFP normal). According to postoperative pathology, we compared tumor regression and complete response rate between the two groups. The primary outcome measure was the tumor regression grade (TRG) after chemotherapy. The difference in pathological complete response between the two groups was also investigated.

RESULTS

There were no tumor progression and distant metastasis in both groups during preoperative chemotherapy. Patients in the AFP risen group achieved better TRG 0/1 than those in the AFP normal group (61.5% vs 39.4%). The increase in AFP was a significant predictor for better tumor regression [χ² = 4.144, odds ratio (OR) = 2.666, P = 0.04]. In the AFP risen group, the complete response rate was 30.8%, which was higher than in the AFP normal group (30.8% vs 12.1%, χ² = 4.542, OR = 3.251, P = 0.03).

CONCLUSION

Patients with a slight increase in serum AFP can achieve better tumor regression during preoperative chemotherapy, and are more likely to achieve pathological complete response.

Donut-like MOFs of copper/nicotinic acid and composite hydrogels with superior bioactivity for rh-bFGF delivering and skin wound healing

Background

Skin injury and the resultant defects are common clinical problems, and usually lead to chronic skin ulcers and even life-threatening diseases. Copper, an essential trace element of human body, has been reported to promote the regeneration of skin by stimulating proliferation of endothelial cell and enhance angiogenesis.

Results

Herein, we have prepared a new donut-like metal–organic frameworks (MOF) of copper-nicotinic acid (CuNA) by a simple solvothermal reaction. The rough surface of CuNA is beneficial for loading/release basic fibroblast growth factor (bFGF). The CuNAs with/without bFGF are easily processed into a light-responsive composite hydrogel with GelMA, which not only show excellent mechanical properties, but also display superior biocompatibility, antibacterial ability and bioactivity. Moreover, in the in vivo full-thickness defect model of skin wound, the resultant CuNA-bFGF@GelMA hydrogels significantly accelerate the wound healing, by simultaneously inhibiting the inflammatory response, promoting the new blood vessels formation and the deposition of collagen and elastic fibers.

Conclusions

Considering the superior biocompatibility, antibacterial ability and bioactivity, the CuNA and its composite light-responsive hydrogel system will be promising in the applications of skin and even other tissue regeneration.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01014-z.

Titanium Alloy Gamma Nail versus Biodegradable Magnesium Alloy Bionic Gamma Nail for Treating Intertrochanteric Fractures: A Finite Element Analysis

OBJECTIVE

To using finite element analysis to investigate the effects of the traditional titanium alloy Gamma nail and a biodegradable magnesium alloy bionic Gamma nail for treating intertrochanteric fractures.

METHODS

Computed tomography images of an adult male volunteer of appropriate age and in good physical condition were used to establish a three-dimensional model of the proximal femur. Then, a model of a type 31A1 intertrochanteric fracture of the proximal femur was established, and the traditional titanium alloy Gamma nails and biodegradable magnesium alloy bionic Gamma nails were used for fixation, respectively. The von Mises stress, the maximum principal stress, and the minimum principal stress were calculated to evaluate the effect of bone ingrowth on stress distribution of the proximal femur after fixation.

RESULTS

In the intact model, the maximum stress was 5.8 MPa, the minimum stress was -11.7 MPa, and the von Mises stress was 11.4 MPa. The maximum principal stress distribution of the cancellous bone in the intact model appears in a position consistent with the growth direction of the principal and secondary tensile zones. After traditional Gamma nail healing, the maximum stress was 32 MPa, the minimum stress was -23.5 MPa, and the von Mises stress was 31.3 MPa. The stress concentration was quite obvious compared with the intact model. It was assumed that the nail would biodegrade completely within 12 months postoperatively. The maximum stress was 18.7 MPa, the minimum stress was -12.6 MPa, and the von Mises stress was 14.0 MPa. For the minimum principal stress, the region of minimum stress value less than -10 MPa was significantly improved compared with the traditional titanium alloy Gamma nail models. Meanwhile, the stress distribution of the bionic Gamma nail model in the proximal femur was closer to that of the intact bone, which significantly reduced the stress concentration of the implant.

CONCLUSION

The biodegradable magnesium alloy bionic Gamma nail implant can improve the stress distribution of fractured bone close to that of intact bone while reducing the risk of postoperative complications associated with traditional internal fixation techniques, and it has promising clinical value in the future.

Community Trait Responses of Three Dominant Macrophytes to Variations in Flooding During 2011-2019 in a Yangtze River-Connected Floodplain Wetland (Dongting Lake, China)

In lacustrine wetlands connected to rivers, the changes in flood regimes caused by hydrological projects lead to changes in the community traits of dominant macrophytes and, consequently, influence the structure and function of wetland vegetation. However, community trait responses of macrophytes to the timing and duration of flood disturbance have been rarely quantified. In 2011-2019, we investigated plant species diversity, density, and biomass in three dominant macrophyte communities (Carex brevicuspis C.B. Clarke, Miscanthus sacchariflorus (Maxim.) Hackel, and Polygonum hydropiper L.) through monthly field surveys in Dongting Lake wetlands. Partial least squares regressions were used to analyze how the variations in hydrological regimes affected plant community traits. Apparent inter-annual fluctuations in plant community traits were detected during 2011-2019. The species richness and Shannon index of diversity of Miscanthus and Polygonum communities increased, whereas the Shannon index of diversity of Carex community decreased. Variation in flooding had a greater effect on Polygonum and Carex community traits than on Miscanthus community traits. Flooding disturbed all plant communities, especially when the duration and timing varied. Shorter inundation periods caused the biomass of Miscanthus community to decline, and that of Carex and Polygonum communities to increase. Earlier flood recession caused the species richness and Shannon index of diversity of Polygonum and Miscanthus community to increase, and those of Carex community to decrease. These findings imply that shorter inundation durations and earlier flood recession generated by the operation of the Three Gorges Dam have changed the macrophyte growth pattern.

Apoptosis inhibition is involved in improvement of sevoflurane-induced cognitive impairment following normobaric hyperoxia preconditioning in aged rats

Sevoflurane, a commonly used anesthetic agent has been confirmed to induce cognitive impairment in aged rats. Normobaric hyperoxia preconditioning has been demonstrated to induce neuroprotection in rats. The present study aimed to determine whether normobaric hyperoxia preconditioning could ameliorate cognitive deficit induced by sevoflurane and the possible mechanism by which it may exert its effect. A total of 66, 20-month-old male Sprague-Dawley rats were randomly divided into 3 groups (n=22 each): Rats in the control (C) and sevoflurane anesthesia (S) groups received no normobaric hyperoxia preconditioning before sevoflurane exposure, rats in the normobaric hyperoxia pretreatment (HO) group received normobaric hyperoxia preconditioning before sevoflurane exposure (95% oxygen for 4 continuous h daily for 6 consecutive days). The anesthesia rats (S and HO groups), were exposed to 2.5% sevoflurane for 5 h, while the sham anesthesia rats (C group) were exposed to no sevoflurane. The neurobehavioral assessment was performed using a Morris water maze test, the expressions of the apoptosis proteins were determined using western blot analysis, and the apoptosis rate and cytosolic calcium concentration were measured by flow cytometry. Normobaric hyperoxia preconditioning improved prolonged escape latency and raised the number of platform crossings induced by sevoflurane in the Morris water maze test, increased the level of bcl-2 protein, and decreased the level of bax and active caspase-3 protein, the apoptosis rate and cytosolic calcium concentration in the hippocampus 24 h after sevoflurane exposure. The findings of the present study may imply that normobaric hyperoxia preconditioning attenuates sevoflurane-induced spatial learning and memory impairment, and this effect may be partly related to apoptosis inhibition in the hippocampus. In conclusion, normobaric hyperoxia preconditioning may be a promising strategy against sevoflurane-induced cognitive impairment by inhibiting the hippocampal neuron apoptosis.

Triplanar Chevron Osteotomy: A Newly Proposed Method to Treat Hallux Valgus Deformities

Objective

To present a novel method called triplanar chevron osteotomy to treat hallux valgus (HV).

Methods

This is a retrospective study. In this study, the CT data of HV patients with painful callosities were evaluated retrospectively between 1 June 2018 and 1 June 2020. CT data from 49 consecutive patients (59 feet) with HV were evaluated. The average age at the time of surgery was 49.6 years (range, 30–63 years). The apex of the chevron osteotomy procedure was located at the center of the first metatarsal and was defined as the line formed by the central point perpendicular to the fourth metatarsal bone. The cut planes of the plantarward oblique chevron osteotomy (POCO) were defined as follows: chevron osteotomy along with 20° of plantarward obliquity. The triplanar osteotomy incision was made using the POCO method, with the direction inclined by 10° distally. The intermetatarsal angle (IMA), the HV angle (HVA), the projection of the second metatarsal (PSM), the metatarsal protrusion index (MPI), and the metatarsal protrusion distance (MPD) were all calculated before and after the operations. The length of the first metatarsal was measured and calculated with an equation.

Results

The results showed that the HVA was significantly decreased after surgery (32.7° ± 4.6° vs 14.9° ± 2.1°, t = 25.583, P < 0.001) in the triplanar, traditional, and POCO groups. The IMA was also significantly decreased (14.7° ± 2.0°) compared with the results before surgery (8.0° ± 1.1°, t = 22.739, P < 0.001) in these groups. Compared with traditional osteotomy and POCO, there were no differences in correcting deformities on axial planes for the HVA (14.5° ± 1.7° vs 14.9° ± 2.1°, t = 1.835, P = 0.072) and IMA (8.1° ± 1.1° vs 8.0° ± 1.1°, t = −0.97, P = 0.336). There was a statistically significant decrease following surgery in terms of the PSM, MPI, and MPD after triplanar osteotomy. The length of the first metatarsal increased (10.9 ± 1.3 mm), as measured through three‐dimensional images in the triplanar osteotomy group. The length was calculated as follows: H = L2 * Tan θ ≈ L/COS β * Tan θ.

Conclusion

The new triplanar osteotomy technique is safe and effective for treating HV, and in simulation experiments reveals potential benefits of correction and preventing transfer metatarsalgia.

Intertrochanteric Femur Fracture Treatment in Asia: What We Know and What the World Can Learn

Hip fractures are of great interest worldwide as the geriatric population continues to increase rapidly. Currently, surgeons prefer to use cephalomedullary nail for internal fixation of pertrochanteric/intertrochanteric fractures. This article summarizes 10 concepts in hip fracture treatment over the past 20 years, including fracture line mapping, proximal lateral wall and anterior cortex, posteromedial lesser trochanter-calcar fragment, anteromedial cortex support reduction, changes of fracture reduction after sliding and secondary stability, nail entry point and wedge-open deformity, tip-apex distance and calcar-referenced tip-apex distance, femoral anterior bowing and nail modification, long nails for wide medullary canal and large posterior coronal fragment, and postoperative stability score.

[Morphological changes of the central sulcus in children with complete growth hormone deficiency: a 3.0 T MRI study]

Objective: To analyze morphological changes in central sulcus of the cerebral cortex in children with complete growth hormone deficiency (CGHD). Methods: Patients attending the Shandong Provincial Hospital who were diagnosed with CGHD or idiopathic short stature were recruited from January 2015 to January 2019. Thirty children with CGHD (18 males and 12 females, 5 to 14 years old) and 30 children with idiopathic short stature (22 males and 8 females, 5 to 14 years old) were included. Measurements of the central sulcus, including the average width, maximum depth, average depth, top length, bottom length and depth position-based profiles (DPP), were obtained using Brain VISA software. The significant differences between groups were statistically analyzed. Results: The average width of bilateral central sulci in children with CGHD (left: (2.26±0.41) mm; right: (2.19±0.34) mm) were significantly higher than those in children with idiopathic short stature (left: (2.10±0.27) mm; right: (2.02±0.18) mm) (P<0.05) ; The maximum depth of the left central sulcus ((19.67±1.29) mm) and the average depth of the right central sulcus ((14.18±1.41) mm) were significantly lower than those in children with idiopathic short stature (left maximum depth: (20.69±1.43) mm; right average depth: (14.92±1.21) mm) (P<0.05) . Children with CGHD had significantly lower DPP at the middle part of the left central sulcus (sites: 46-54) and the inferior part of the right central sulcus(sites: 91-98). Conclusion: There are significant morphological changes of the central sulcus in children with CGHD, which may represent the structural basis of their relatively slower development in motor, cognitive and linguistic functional performance.

Differential Strategies to Tolerate Flooding in Polygonum hydropiper Plants Originating From Low- and High-Elevation Habitats

In species that occur over a wide range of flooding conditions, plant populations may have evolved divergent strategies as a consequence of long-term adaptation to local flooding conditions. In the present study, we investigated the effects of a flooding gradient on the growth and carbohydrate reserves of Polygonum hydropiper plants originating from low- and high-elevation habitats in the Dongting Lake wetlands. The results indicated that shoot length did not differ, whereas the total biomass and carbohydrate reserves were reduced under flooded compared to well-drained conditions for plants originating from both habitat types. However, shoot length, shoot mass, rhizome mass, and total biomass were lower in plants from low-elevation habitats than in those from high-elevation habitats in the flooded condition. Soluble sugar and starch contents in belowground biomass were higher in plants from low-elevation habitats than in those from high-elevation habitats independently of the water level. Therefore, P. hydropiper plants from low-elevation habitats exhibit a lower growth rate and more conservative energy strategy to cope with flooding in comparison with plants from high-elevation habitats. Differential strategies to cope with flooding among P. hydropiper populations are most likely a response to the flooding pressures of the habitat of origin and may potentially drive ecotype differentiation within species along flooding gradients.

[Three-dimensional computed tomography analysis and clinical application of sacroiliac screw placement]

Objective: To evaluate the possibility of transverse sacroiliac screw placement in different segments of the sacrum. Methods: Data of 80 pelvic CT scans (slice thickness ≤1.0 mm) archived in CT department of the Third Hospital of Hebei Medical University from September 2016 to October 2017 were retrospectively collected. Mimics software was used to rebuild the pelvis three-dimensional model. According to whether the sacral 1(S(1)) segment could place the transverse sacroiliac screws or not, all the sacrums were divided into normal group (n=55) and dysmorphic group (n=25). Simulation the S(1), sacral 2(S(2)) transverse sacroiliac screw placement in 3-Matic software. Analysis whether there was any difference in maximum diameter and length of S(2) transverse sacroiliac screw between the normal group and the dysmorphic group. The pelvic CT data of the dysmorphic group were measured, and the optimal tilt angle and length of the oblique S(1) screw were obtained. The feasibility of transverse sacroiliac screw insertion in sacral 3(S(3)) segment was evaluated.t-test, rank sum test, and χ(2) test was used to analyze data, respectively. Results: In the dysmorphic group, the largest diameter of the S(1) transverse screw was (4.9±1.6)mm, and the normal group was (13.6±3.6)mm (t=-15.07, P=0.00). In the dysmorphic group, the largest diameter of S(2) transverse screw was (13.8±3.0)mm, and was (12.4±2.2)mm in the normal group(t=2.11, P=0.04). There was no significant difference in the length of S(2) transverse sacroiliac screw between the two groups (t=0.47, P=0.64). In the dysmorphic group, the anterior vertebral height of S(1) was (23.1±4.0)mm, which was significantly higher than that of the normal group ((14.1±4.2)mm)(t=9.01, P=0.00). The angle of S(1)S(2) in the dysmorphic group was 10.9°(3.8°, 17.6°), which was significantly larger than that of the normal group (2.0°(1.0°, 2.0°) (Z=-4.03, P=0.00). In the dysmorphic group, the incline angle of the oblique S(1) sacroiliac screw was (35.6±6.2)°, the anteversion angle was (37.2±4.4)°, and the mean screw length was (90.2±4.7)mm. In the dysmorphic group, the placement rate of S(3) transverse sacroiliac screw was 48.0%, and that of the normal sacral group was 9.1%. Conclusions: There is often dysmorphic in the sacrum in patients with large S(1) anterior vertebral height and S(1)S(2) angle. Sacral dysmorphic patients with posterior pelvic ring injury may be treated with S(1) pedicle oblique sacroiliac screws. S(3) transverse sacroiliac screws should be carefully placed, especially for the absence of sacral dysmorphic in patients.

Cooling rate dependence of solidification for liquid aluminium: a large-scale molecular dynamics simulation study

The effect of the cooling rate on the solidification process of liquid aluminium is studied using a large-scale molecular dynamics method. It is found that there are various types of short-range order (SRO) structures in the liquid, among which the icosahedral (ICO)-like structures are dominant. These SRO structures are in dynamic fluctuation and transform each other. The effect of the cooling rate on the microstructure is very weak at high temperatures and in supercooled liquids, and it appears only below the liquid-solid transition temperature. Fast cooling rates favour the formation of amorphous structures with ICO-like features, while slow cooling rates favour the formation of FCC crystalline structures. Furthermore, FCC and HCP structures can coexist in crystalline structures. It is also found that nanocrystalline aluminium can be achieved at appropriate cooling rates, and its formation mechanism is thoroughly investigated by tracing the evolution of nanoclusters. The arrangement of FCC and HCP atoms in the nanograins displays various twinned structures as observed using visualization analysis, which is different from the layering or phase separation structures observed in the solidification of Lennard-Jones fluids and some metal liquids.

Consequences of Repeated Defoliation on Belowground Bud Banks of Carex brevicuspis (Cyperaceae) in the Dongting Lake Wetlands, China

Despite the predominant role of bud banks in the regeneration of clonal macrophyte populations, few studies have examined the way in which clonal macrophytes adjust the demographic features of bud banks to regulate population dynamics in response to defoliation in wetlands. We investigated the density and composition of bud banks under repeated defoliation in the wetland sedge Carex brevicuspis C. B. Clarke in the Dongting Lake wetlands, China. The density and biomass of rhizome buds and shoots did not decrease significantly in response to repeated defoliation over two consecutive years. The composition of bud banks, which consisted of long and short rhizome buds, also did not change significantly in response to repeated defoliation. Nevertheless, the ramet height and the shoot, root, and rhizome mass of C. brevicuspis declined significantly under repeated defoliation. Our findings suggest that bud banks are a conservative reproductive strategy that enables C. brevicuspis to tolerate a certain amount of defoliation. The maintenance of large bud banks after repeated defoliation may enable C. brevicuspis populations to regenerate and persist in disturbed habitats. However, bud bank density of C. brevicuspis might decline in the long term because the amount of carbon stored in rhizome buds and plants is reduced by frequent defoliation.

Medial Compartment Decompression by Fibular Osteotomy to Treat Medial Compartment Knee Osteoarthritis: A Pilot Study

Compared with high tibial osteotomy and total knee arthroplasty, the authors found a simpler surgical procedure, partial fibular osteotomy, could effectively relieve knee pain and also correct the varus deformity for patients with medial compartment knee osteoarthritis (OA). From January 1996 to April 2012, a total of 156 patients with medial compartment OA were treated by proximal fibular osteotomy in the authors' hospital. A 2-cm-long section of fibula was resected 6 to 10 cm below the fibular head. A total of 110 patients with follow-up of more than 2 years were included in the study, including 34 males and 76 females with an average age of 59.2 years. Anteroposterior and lateral weight-bearing radiographs, the femorotibial angle (FTA) and lateral joint space, and the American Knee Society Score (KSS) and the visual analog scale (VAS) score of the knee joint were evaluated preoperatively and at final follow-up, respectively. At final follow-up, mean FTA and lateral joint space were 179.4°±1.8° and 6.9±0.7 mm, respectively, which were significantly smaller than those measured preoperatively (182.7°±2.0° and 12.2±1.1 mm, respectively; both P<.001). Mean KSS at final follow-up was 92.3±31.7, significantly higher than the mean preoperative score of 45.0±21.3 (P<.001). Mean VAS score and interquartile range were 2.0 and 2.0, significantly lower than the preoperative data (7 and 1.0, respectively; P<.001). The authors found that proximal fibular osteotomy can significantly improve both the radiographic appearance and function of the affected knee joint and also achieve long-term pain relief. This procedure may be an alternative treatment option for medial compartment OA.

[Characteristics of Carex brevicuspis and its impact factors in Dingzidi, East Dongting Lake]

In recent 20 years, the area of lake grass has been drastically reduced and degraded. In order to search for reasonable recovery ways of the lake grass, the vegetational characteristics (plant height, coverage, density, biomass and biodiversity index) and soil physico-chemical characteristics (soil organic carbon, SOC; total nitrogen, TN; total phosphorus, TP; soil bulk density and moisture) were investigated in the Carex brevicuspis community from 63 sampling plots in 7 sampling belts along an elevation gradient in Dingzidi, East Dongting Lake. All biological characteristics showed an inverted "U" distribution pattern along with increasing elevation, except for diversity index, which showed a tendency of increasing at first and then decreasing. Plant growth was inhibited near water body (low elevation region) and levee (high elevation region). In contrast, the intermediate elevation region had a favorable condition for plant growth. For soil physical properties, soil water moisture decreased but soil bulk density increased along with increasing elevation. However, SOC and TN contents were higher in the intermediate elevation region and lower in both low and high elevation regions. TP content was fluctuant along with increasing elevation. The principal component analysis (PCA) showed that the key factors influencing biomass of C. brevicuspis were soil C and N contents, soil moisture and bulk density. These results indicated that increasing soil fertility and maintaining proper soil moisture might be efficient to recover the vegetation of C. brevicuspis.

Axial and tangential views of the acromioclavicular joint: the introduction of new projections

BACKGROUND

Routine anteroposterior radiographs of the acromioclavicular (AC) joint with or without weight bearing have limitations in demonstrating the AC joint. Transarticular fixation with Kirschner wire is a treatment choice for AC dislocations. However, percutaneous fixation of the AC joint is technically demanding. The C-arm fluoroscopy can be used as routine intraoperative guidance to facilitate this procedure. The current study aims to introduce new projections, the axial and tangential views of AC joint, to help evaluate the severity of the injury and facilitate the percutaneous procedure.

METHODS

Three shoulder specimens were used to find the projection directions of the axial and tangential views of the AC joint by using the digital radiography (DR) unit. The axial and tangential views were taken of 20 adult volunteers by referencing the projection directions determined in the shoulder specimens. The angles showed on the DR system and the angles between the coronal plane of the body and the vertical plane of the flat panel detector (FPD) during taking these radiographs were recorded. The C-arm fluoroscopy unit was used to take the axial and tangential views referencing the angles measured on the DR system. Routine anteroposterior radiographs of the AC joint were taken on the volunteers. The minimal distances from the distal clavicle to the acromion were measured on both tangential and anteroposterior radiographs. The data was statistically analyzed.

RESULTS

The clear axial and tangential radiographs of AC joints of the volunteers were obtained using both DR and C-arm fluoroscopy units. The angles demonstrated on the DR window are (20.8 ± 2.4)° for male and (18.3 ± 2.3)° for female. During taking the axial views, the angles between the coronal plane of the body and vertical plane of FPD are (23.3 ± 3.2)° for male and (20.1 ± 2.4)° for female. During taking tangential views, the corresponding angles are (117.5 ± 3.7)° for male and (113.1 ± 3.3)° for female. On the tangential radiographs, the minimal distance from the distal clavicle to the acromion is (6.1 ± 1.2) mm, wider than the same measurement on the anteroposterior radiographs (P < 0.05). Statistical analyses showed no significant differences in the above-mentioned angles and the minimal distances between the left and right AC joints (P > 0.05). There were no significant differences in the above-mentioned angles between DR and C-arm fluoroscopy units (P > 0.05).

CONCLUSIONS

The axial and tangential radiographs of the AC joint can demonstrate the joint clearly and they can be easily obtained with both DR system and C-arm fluoroscopy unit in similar projection directions.

[Characteristics of soil seed banks in different water level areas after returning farmland into lake in Qingshanyuan of Dongting Lake]

To study the composition and distribution of soil seed bank in the areas after returning farmland into lake is of significance in evaluating the ecological restoration effect of damaged wetlands. In this paper, the composition and diversity of seed bank in soil profile (0-2, 2-5, and 5-10 cm) and their relationships with above-ground vegetation in different water level areas in Qingshanyuan, a typical region after returning farmland into lake in Dongting Lake, were investigated. A V-type variation pattern was observed in the seed density and species richness of soil seed bank and in the similarity coefficient of soil seed bank and above-ground vegetation along a gradient of low-medium-high water level. As for the seed density, it was the highest (36943 +/- 5207 seeds x m(-2)) in frequently flooded area, followed by in heavily flooded area (30572 +/- 5329 seeds x m(-2)), and in incidentally flooded area (18618 +/- 6977 seeds x m(-2)); for the similarity coefficient, it was also in the order of frequently flooded area (0.76) > heavily flooded area (0.53) > incidentally flooded area (0.41). The seed density, species diversity, and species richness of soil seed bank decreased along soil profile, but the decrements differed in different water level areas. The regular variation patterns of the seed density and species richness of soil seed bank and of the similarity coefficient of soil seed bank and above-ground vegetation along the water level gradient were closely related to the water-level fluctuation and the life-form composition of the vegetations in study area.

[Preliminary survey on aquatic vegetations in Baiyangdian Lake]

A field survey was conducted on the species composition, community type, distribution pattern, and biomass of aquatic vegetations in the Baiyangdian Lake of Hebei Province. A total of 39 species were observed, including 16 emergent species, 14 submerged species, 6 floating-leaved species, and 3 floating species, belonging to 21 families and 32 genera. Compared with those about 15 years ago, 9 species were disappeared, community types were decreased from 16 to 13, and some predominant communities with large distribution area, such as Hydrilla verticillata and Najas major, were not found in the present survey. Meanwhile, the distribution pattern of aquatic vegetations was greatly changed. The biomass of aquatic vegetations decreased dramatically, compared to the survey in 1980. Human cultivation, random discharge of pollutants, and tremendous change of water level could be the main reasons for the degradation of aquatic vegetations and the great change of their distribution pattern in the Lake.

Atrial tachyarrhythmias induced by acetylcholine in tilapia (Oreochromis sp.) isolated atria

1. Effects of the parasympathetic neuromediator acetylcholine (ACh) on atrial tissues vary greatly depending on the species, the type of atrial cells and experimental conditions. The aim of the present study was to investigate, with microelectrode techniques, the arrhythmogenic effects of ACh in tilapia (Oreochromis sp.) isolated atria at room (22-25 degrees C) and high temperature (37 degrees C). 2. Acetylcholine (1-10 micromol/L) shortened action potential duration (APD), depressed action potential plateau and decreased twitch force in tilapia atria, as it did in human atrial fibres. In addition, ACh induced premature responses and re-entrant tachyarrhythmias (TA; frequency range from 7 to 25 Hz) in five of 19 and 14 of 22 tilapia atria tested at room and high temperature, respectively. The higher incidence of ACh-induced TA at 37 degrees C compared with room temperature was statistically significant. 3. The ACh-induced TA consisted of high-frequency and uniform action potentials accompanied by tension oscillation and elevation of diastolic force (flutter). Acetylcholine-induced TA could be readily abolished by atropine (1 micromol/L) and prevented by treatment with agents with local anaesthetic properties, such as 0.1 micromol/L tetrodotoxin or 3 micromol/L quinidine. The antagonistic action of quinidine occurred without significant prolongation of APD. 4. The present findings suggest that pharmacological concentrations of the cholinergic muscarinic agonist ACh readily induce TA (mainly atrial flutter) in tilapia atria, presumably via sodium channel-dependent re-entrant excitation. The poikilothermic tilapia appears to be an appropriate animal model for the study of atrial TA.

Identification of 2,3-butanedione monoxime hydrogenation products by gas chromatography-mass spectrometry in an ion trap mass spectrometer

The reduced products of 2,3-butanedinone monoxime by reaction with hydrogen in the presence of homogeneous catalysts were identified by gas chromatography coupled to an ion trap mass spectrometer operating either in the electron impact or chemical ionization mode. The major hydrogenation products were found to be several heterocyclic nitrogen-containing compounds: tetramethylpyrazine, 2,4-dimethyl-3-ethylpyrrole, 3,4,5-trimethylpyrazole, 2,5-dimethyl-1-propylpyrrole, 3-acetyl-2,4-dimethylpyrrole, 3,5-dimethyl-4-allypyrazole and tetramethylpyrazine N-monoxide.

The effect of panic attack on mitral valve prolapse

It has been reported that panic attacks might cause mitral valve prolapse (MVP) via haemodynamic or indirect effects. Such prolapse can be classified as being physiological (benign course) or pathological (poor course). It is therefore important to consider whether panic attacks, as a risk factor for MVP, are associated with its physiological or pathological type. Our study sample consisted of two groups of patients with panic disorder (PD), one having onset within 1 year (n=24) and the other with a history of more than 10 years (n=21). Demographic data, symptom presentations, auscultatory and echocardiographic findings of both groups were compared, but no significant difference was found except with regard to anticipatory anxiety. It is concluded that panic attack exerts no significant effect on mitral valve prolapse.

Determination of dextromethorphan metabolic phenotype by salivary analysis with a reference to genotype in Chinese patients receiving renal hemodialysis

BACKGROUND

The polymorphic metabolism of debrisoquin and sparteine by cytochrome P450IID6 (CYP2D6) is genetically determined. Determination of the CYP2D6 metabolic phenotype with conventional urine analytic methods is not feasible in anuric patients with renal failure. The possibility of using salivary analysis, with dextromethorphan as a probe drug, to determine the CYP2D6 metabolic phenotype in patients with renal failure was evaluated.

METHODS AND RESULTS

One hundred four Chinese patients with renal failure were recruited. All 104 patients were receiving hemodialysis. Saliva was collected before and at 3 hours after each patient took a capsule of dextromethorphan hydrobromide (30 mg). Four patients were excluded because of insufficient samples of saliva. The distribution of logarithms of the metabolic ratios (log[MR]) in the 100 patients appeared to be normal. Administration of quinidine sulfate (200 mg twice daily) to nine of the patients significantly and markedly increased the dextromethorphan metabolic ratios. The metabolic ratios of nine patients pretreated with quinidine were higher than any of the 100 patients with renal failure who did not receive quinidine pretreatment. A metabolic ratio of 33 separated these two groups. Genomic deoxyribonucleic acid was extracted from whole blood in a subset of patients. Polymerase chain reaction (PCR)-based methods were used to detect the CYP2D6 and B mutant genes. Mutant B alleles (which are common in white poor metabolizers) of CYP2D6 genes were not detected in any of the 47 subjects tested. A PCR-based test of cytosine (C188) to thymine (T188) polymorphism at 188 base pairs in exon 1 of CYP2D6 genes was performed in 61 patients. Subjects who were homozygous for C188 had significantly (p = 0.0067) lower log[MR] values than those who were homozygous for T188.

CONCLUSIONS

Determination of dextromethorphan metabolic ratios in saliva is feasible in patients with renal failure requiring hemodialysis. All subjects in this study appeared to be "extensive metabolizer" phenotype for CYP2D6, and no poor metabolizer was identified. From the results with quinidine pretreatment, a metabolic ratio of 33 is suggested to be a tentative antimode for identification of poor metabolizers in patients with renal failure.

Upright postures and isoproterenol infusion for provocation of neurocardiogenic syncope: a comparison of standing and head-up tilting

Head-up tilt testing has proved to be useful in provocation of neurocardiogenic syncope. The purpose of this study was to examine whether simply assuming an upright posture by standing can be an alternative to the head-up tilt testing for diagnosis of neurocardiogenic syncope. Eighty-four patients with recurrent unexplained syncope and 22 normal volunteers were recruited into the study. Forty-seven patients with syncope and all normal volunteers received the standing test. Thirty-seven of the patients with syncope received head-up tilt testing (90 degrees). All subjects lay down for 5 minutes and then assumed an upright posture until syncope or presyncope occurred or until a maximum of 10 minutes was reached in each stage of the test. The tests included four stages: baseline and infusion of 1, 2, or 3 micrograms/min isoproterenol in each of the successive stages. Five subjects could not tolerate the procedure, and further testing was terminated. Overall, the standing test was positive in 83% of the patients with syncope, and its specificity was 74%. The head-up tilt testing was positive in 75% of the patients with syncope. The duration of assuming an upright posture before occurrence of syncope or presyncope was significantly longer in the syncope-tilting group in the third stage (p < 0.01) and the fourth stage (p < 0.05) compared with the syncope-standing group. However, the curves of the time course for cumulative positive rates were not significantly different (p = 0.0739) in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of antihypertensive effects between two formulations of atenolol: tenolol and tenormin

BACKGROUND

Atenolol is a cardioselective beta-blocker. Tenolol is a new formulation of atenolol, with bioequivalence to the original atenolol (Tenormin). This study was designed to compare the antihypertensive effects between the two formulations of atenolol, Tenolol and Tenormin.

METHODS

Twenty-three patients, with mild to moderate hypertension untreated with any antihypertensive drugs, were recruited. They were randomized to receive two weeks of placebo, four weeks of Tenolol or Tenormin (100 mg once daily) and two weeks of placebo. Then the treatments were crossed over for four more weeks.

RESULTS

At two weeks five patients were excluded because their blood pressures (BP) were below 160/90 mmHg. The baseline BPs for the patients receiving Tenormin (162 +/- 18/97 +/- 8 mmHg) and Tenolol (164 +/- 17/97 +/- 9 mmHg) were not distinct. After two weeks of treatment with Tenormin or Tenolol, systolic BPs decreased by 12 +/- 11 mmHg and 13 +/- 14 mmHg, respectively (p < 0.01 for both formulations). Similarly the diastolic BPs decreased significantly (p < 0.01) by 7 +/- 9 mmHg and 7 +/- 10 mmHg, respectively. The hypotensive effects persisted at four weeks of treatment for both formulations. Reductions in systolic and diastolic BPs by treatment with Tenormin and Tenolol were not significantly different by two-way ANOVA analysis. There were no side effects in any patient throughout the study.

CONCLUSIONS

The results indicate that the generic formulation of atenolol (Tenolol) has comparable antihypertensive effects as the original formulation (Tenormin).

Acute treatment of recent-onset atrial fibrillation and flutter with a tailored dosing regimen of intravenous amiodarone. A randomized, digoxin-controlled study

A 24 h intravenous dosing regimen of amiodarone was designed to reach a peak plasma concentration at 1 h and to maintain the concentration above a certain level during the infusion period. A randomized, open-label, digoxin-controlled study was undertaken to observe the efficacy and safety of the dosing regimen of amiodarone in treating recent-onset, persistent, atrial fibrillation and flutter with ventricular rates above 130 beats.min-1. Fifty patients with a mean age of 70 +/- 7 (SD) years were enrolled and randomly assigned to receive either amiodarone intravenously (n = 26) or digoxin (n = 24). Amiodarone HCl was infused over 24 h according to the following regimen: 5 mg.min-1, 3 mg.min-1, 1 mg.min-1 and 0.5 mg.min-1 for 1, 3, 6 and 14 h, respectively, for a 70-kg subject. Digoxin (0.013 mg.kg-1) was infused in three divided doses, each dose 2 h apart and infused over 30 min. The mean heart rates in the amiodarone group decreased significantly from 157 +/- 20 beats.min-1 to 122 +/- 25 beats.min-1 after 1 h (P < 0.05 vs baseline), and then decreased further to stabilize at 96 +/- 25 beats.min-1 after 6 h (P < 0.05). The digoxin group had fewer dramatic alterations in heart rates, compared to the amiodarone group, in the first 8 h (P < 0.05, respectively). Maximum reduction was reached only after 8 h. The amiodarone infusion was prematurely aborted in two patients due to severe bradycardia and death after conversion in one patient and aggravation of heart failure in the other.(ABSTRACT TRUNCATED AT 250 WORDS)

[Protrusion of thoracic intervertebral disk: report of 11 cases]

The authors reported 11 cases of thoracic intervertebral disk protrusion examined with plane film, myelography, CT and CT-myelography in 11 cases and MR imaging in 3. All of the 11, cases were confirmed by operation. There were 13 protrusions in the 11 cases with the locations of T10-11 in 4, T11-12 in 5 cases and T12-L1 in 4. 9 protrusions fell into central type, 1 into paracentral type and 1 into lateral type. The clinical symptoms were prominent with all 11 cases, however, most primary clinical diagnoses were erroneously given as lumber intervertebral disk protrusions and even the disorders of heart, lung, alimentary tract and urinary system. It was concluded that the main causes of the misdiagnosis included: (1) not easily to think of this entity for the clinic physicians due to its low incidence, (2) the untypical clinical manifestations. The authors considered that the exam method with the highest accuracy is CT-myelography.

Pacing may not prevent neurocardiogenic syncope: the importance of correct diagnosis

A 28-year-old female with frequent attacks of syncope showed high degree atrioventricular (AV) block in Holter's electrocardiographic monitoring. A permanent pacemaker (VVIR) was implanted. However, the syncope recurred despite the normally-functioning pacemaker. The syncope associated with hypotension and bradycardia was reproduced by upright posture for 8 min. This neurocardiogenic syncope was prevented by propranolol (30 mg/day). Neurocardiogenic syncope should be ruled out before pacemaker implantation in patients with syncope, particularly in young adults with no apparent symptom/electrocardiography correlation.

Salivary analysis for determination of dextromethorphan metabolic phenotype

Debrisoquin oxidative phenotype is a determinant of pharmacologic response for many drugs. Poor and extensive metabolizers can be identified by the dextromethorphan metabolic ratio (dextromethorphan/dextrorphan). We developed and tested a method to determine debrisoquin phenotype on the basis of the metabolic ratio in saliva. Each of 62 normal volunteers was given a 50 mg capsule of dextromethorphan hydrobromide and collected urine (0 to 8 hours) and saliva (at 3 hours). Dextromethorphan and dextrorphan in saliva and urine were assayed by HPLC. The distributions of paired urinary and 3-hour salivary metabolic ratios of samples from 61 subjects were compared. The urinary and salivary metabolic ratios were distributed trimodally and bimodally, respectively. The Spearman rank correlation coefficient for logarithm of urinary metabolic ratio vs that of salivary metabolic ratio was 0.704. All the poor metabolizers identified by urinary metabolic ratio were also identified by the metabolic ratio in saliva at 3 hours (100% concordance). This study demonstrates that salivary analysis for determination of dextromethorphan metabolic phenotype is feasible.

Intrathecal injection of Iohexol for routine myelography and CT myelography in 1,000 cases

This article is to present the experience in 1,000 cases given intrathecal Iohexol injection during 1985-1988, including conventional myelography in 343 cases, conventional and CT myelography in 572, only CT myelography in 60 and CT cisternography in 25. No convulsions were observed. The frequency of headache was 11.6% and the total uncomfortable subjective reaction was 19.6% after intrathecal injection, but no serious complications were found. Because of very low frequency of side effects after this injection, most of the examinations can be made in the outpatient departments. In our clinical experience, Iohexol appears to be a myelographic contrast medium with diagnostic capabilities and less morbidity compared to Metrizamide. Thus Iohexol seems to be well suited for intrathecal injection and will replace metrizamide in this respect.

Role of acetylcholine in induction of repetitive activity in human atrial fibers

The actions of acetylcholine and its interactions with epinephrine were studied in human atrial tissues by recording transmembrane potentials and contractile force. Acetylcholine (0.55-5.5 microM) reduced force, shortened the duration and shifted to more negative values the plateau of action potentials, abolished phase 4 depolarization, and suppressed the activity of spontaneous fibers. During the recovery, often there was a rebound increase in some parameters of the action potential and in force. Epinephrine (0.3-2.8 microM) induced oscillatory potentials and aftercontractions and acetylcholine abolished them. However, during the washout of acetylcholine in the presence of epinephrine, the oscillatory potentials and aftercontractions were larger than before acetylcholine, and repetitive activity was often induced. The inhibitory and excitatory effects of acetylcholine were mimicked by methacholine (5.1 microM) and abolished by atropine (1.5 microM). The postacetylcholine rebound was also potentiated by theophylline (0.6-2 mM) but was not blocked by propranolol (1-3.4 microM), prazosin (1 microM), and diltiazem (0.1 microM). It is concluded that in human atrial fibers acetylcholine has inhibitory as well as excitatory effects that are exaggerated in the presence of epinephrine and are mediated by the activation of the muscarinic receptor. The interaction between acetylcholine and epinephrine involves an antagonism at an intracellular level.

Effects of calcium-channel blockers on picrotoxin-induced centrogenic arrhythmias in cats

Intravenous picrotoxin injection has been established as a model of producing arrhythmias, mainly through enhanced central sympathetic outflow. The effects of calcium-channel blockers, and a beta-blocker on these arrhythmias were tested in chloralose-anesthetized cats. Picrotoxin (10 mg/kg, i.v.) produced mostly ventricular, sometimes supraventricular tachycardias and ectopic beats, as well as a marked elevation of arterial blood pressure. Nifedipine at the doses of 2 micrograms/kg (i.v. or i.c.) and 5 micrograms/kg (i.v.) transiently suppressed the arrhythmias in some of the cats tested. With the dose of 10 micrograms/kg (i.v.), it promptly and consistently abolished the arrhythmias without recurrence and significantly reduced the blood pressure (-62 +/- 8/-59 +/- 8 mmHg, delta systolic pressure/delta diastolic pressure, p less than 0.001, n = 9). A similar degree of blood pressure reduction (-69 +/- 8/-67 +/- 7 mmHg, n = 6) after sodium nitroprusside (4-5 mg/kg, i.v.) injection abolished the arrhythmias in 4 of 6 cats; however, there was marked ECG evidence of myocardial ischemia in 3 cats. Verapamil (50 micrograms/kg, i.v.) transiently abolished the arrhythmias and significantly decreased the blood pressure (7/7 cats), whereas a larger dose (150 micrograms/kg) had a persistent effect (2/4 cats). Propranolol at a dose of 240 micrograms/kg also consistently abolished the arrhythmias without recurrence in all 4 cats. We conclude that nifedipine, verapamil and propranolol are effective in the treatment of picrotoxin-induced arrhythmias. This result indicates that calcium-channel blockers or beta-blockers may be clinically effective in the treatment or prevention of arrhythmias caused by intracranial lesions with enhanced sympathetic outflow.

Somatostatin effects in isolated human atrial fibres

Effects of hypothalamic hormone somatostatin on the action potential and contractile force of 54 human atrial preparations obtained at cardiac surgery were studied with standard microelectrode techniques. In the atrial fibres responding to electrical stimuli with fast response action potentials in 4 mM [K]0 Tyrode solution (maximum rate of phase 0 depolarization greater than 50 V/s), somatostatin (10(-7) to 10(-6) M) reduced slightly the duration of action potential and decreased twitch force dose-dependently. In spontaneously active atrial fibres, somatostatin (10(-7) to 10(-6) M) abolished the action potentials in the preparations with low maximal diastolic potential (MDP, -48 +/- 2.8 mV), but induced only mild suppressive effect in the preparations with high MDP (-70 +/- 2.4 mV). When the fibres were depolarized in 27 mM [K]0 Tyrode solution, somatostatin decreased the maximum rate of depolarization and amplitude of the slow response action potentials induced by electrical stimuli. The delayed afterdepolarizations or triggered action potentials induced by high-frequency electrical drive in the presence of epinephrine were also suppressed by somatostatin. The above findings suggest that somatostatin may suppress the abnormal automaticity and the triggered activity in human atrial fibres through a reduction of cellular calcium.

Electrophysiological effects of low pH in human atrial fibres

In the studies of the electrophysiological properties of human atrial fibres obtained at cardiac surgery, it has often been reported that the diastolic potential, the maximum upstroke velocity of the phase 0 depolarization (Vmax) and the amplitude of action potential are relatively low. The same findings were also obtained in our previous study when the tissue preparations were perfused with a Tyrode solution which, as usually described in literatures on cardiac cell studies had a NaHCO3 concentration of 12 mM and was aerated with a gas mixture of 95% O2-5% CO2 at 37 degrees C. Recently we found that the relatively poor electrical activities of the human atrial fibres were related to the low pH value (around 7.06) of the perfusate used. Raising the pH value of the perfusate either by increasing the NaHCO3 concentration or by reducing the CO2 in the bubbling gas mixture significantly improved the electrical activities of the fibres. There is evidence that the suppressive effect of low pH on the electrical activities is due to the hindering action of H+ on the transportation of other cations across the plasma membrane.