Synergistic inhibitory effect of berberine and icotinib on non-small cell lung cancer cells via inducing autophagic cell death and apoptosis

Resistance to epidermal growth factor receptor-tyrosin kinase inhibitors (TKIs, e.g. icotinib) remains a major clinical challenge. Non-small cell lung cancer patients with wild-type EGFR and/or K-RAS mutation are primary resistance to EGFR-TKIs. Berberine has been found to have potent anticancer activities via distinct molecular mechanism. In this study, we sought to investigate the therapeutic utility of BBR in combination with icotinib to overcome icotinib resistance in NSCLC cells, and explore the molecular mechanism of synergism of icotinib and BBR to EGFR-resistant NSCLC cells. We used the two EGFR-resistant NSCLC cell lines H460 and H1299 for testing the inhibitory effect of icotinib and/or BBR on them. Moreover, xenograft mouse model was applied for assessing the anti-tumor activities of BBR and icotinib in combination. Results showed that BBR and icotinib have a synergistic inhibitory effect on H460 and H1299 cells through induction of autophagic cell death and apoptosis. Accordingly, the anti-cancer effect of BBR plus icotinib was further confirmed in the NSCLC xenograft mouse models. Combination of BBR and icotinib significantly inhibited the protein expression and the activity of EGFR by inducing autophagic EGFR degradation. BBR plus icotinib resulted in intracellular ROS accumulation, which could mediated autophagy and apoptosis and involved in the suppression of cell migration and invasion. In conclusions, combination application of BBR and icotinib could be an effective strategy to overcome icotinib resistance in the treatment of NSCLC.

Synergistic killing effect of paclitaxel and honokiol in non-small cell lung cancer cells through paraptosis induction

PURPOSE

Paclitaxel is an anticancer drug for the treatment of non-small cell lung cancer (NSCLC). However, drug-resistance remains a major problem. Honokiol is a natural component which has been found to exhibit anti-tumor activity. Paclitaxel and honokiol have been reported to be able to induce paraptosis. The aim of this study was to investigate whether honokiol can reverse paclitaxel resistance by inducing paraptosis in NSCLC cells.

METHODS

NSCLC cell lines H1650 (paclitaxel-sensitive), H1299 and H1650/PTX (intrinsic and acquired paclitaxel-resistant, respectively) were used to assess the cytotoxic effects of paclitaxel and honokiol. Light and transmission electron microscopy were performed to detect cytoplasmic vacuolation. In vitro cell viability and clonogenic survival assays, as well as in vivo xenograft assays were conducted to test synergistic killing effects of paclitaxel and honokiol on NSCLC cells. Western blotting, flow cytometry and immunofluorescence were performed to evaluate paraptosis-regulating mechanisms.

RESULTS

We found that combination treatment with paclitaxel and honokiol synergistically killed H1650, H1299 and H1650/PTX cells by inducing paraptosis, which is characterized by cytoplasmic vacuolation. Moreover, paclitaxel/honokiol treatment resulted in a significant growth delay in H1299 xenograft tumors that showed extensive cytoplasmic vacuolation. Mechanistically, proteasomal inhibition-mediated endoplasmic reticulum (ER) stress and unfolded protein responses leading to ER dilation, and the disruption of intracellular Ca2+ homeostasis and mitochondrial Ca2+ overload resulting in mitochondrial disfunction, were found to be involved in paclitaxel/honokiol-induced paraptosis. Cellular protein light chain 3 (LC3) may play an important role in paclitaxel/honokiol induced cytoplasmic vacuolation and NSCLC cell death.

CONCLUSIONS

Combination of honokiol and paclitaxel may represent a novel strategy for the treatment of paclitaxel-resistant NSCLC.

Spatiotemporal characteristics of neural activity in tibial nerves with carbon nanotube yarn electrodes

BACKGROUND

Reliable interfacing with peripheral nervous system is essential to extract neural signals. Current implantable peripheral nerve electrodes cannot provide long-term reliable interfaces due to their mechanical mismatch with host nerves. Carbon nanotube (CNT) yarns possess excellent mechanical flexibility and electrical conductivity. It is of great necessity to investigate the selectivity of implantable CNT yarn electrodes.

NEW METHOD

Neural interfaces were fabricated with CNT yarn electrodes insulated with Parylene-C. Acute recordings were carried out on tibial nerves of rats, and compound nerve action potentials (CNAPs) were electrically evoked by biphasic current stimulation of four toes. Spatiotemporal characteristics of neural activity and spatial selectivity of the electrodes, denoted by selectivity index (SI), were analyzed in detail.

RESULTS

Conduction velocities of sensory afferent fibers recorded by CNT yarn electrodes varied between 4.25 m/s and 37.56 m/s. The SI maxima for specific toes were between 0.55 and 0.99 across seven electrodes. SIs for different CNT yarn electrodes are significantly different among varied toes.

COMPARISON WITH EXISTING METHODS

Most single CNT yarn electrode with a ∼ 500 μm exposed length can be sensitive to one or two specific toes in rodent animals. While, it is only possible to discriminate two non-adjacent toes by multisite TIME electrodes.

CONCLUSION

Single CNT yarn electrode exposed ∼ 500 μm showed SI values for different toes comparable to a multisite TIME electrode, and had high spatial selectivity for one or two specific toes. The electrodes with cross section exposed could intend to be more sensitive to one specific toe.

[Advance in the research of graphene and its derivatives in wound dressings]

Graphene, as a new two-dimensional nanomaterial, is isolated and prepared for various industries application, which has become a hot research topic at present. It is also used in biomedicine for drug carriers, biological detection, cancer treatment, and tissue engineering. Graphene and its derivatives have great potential in the application of wound dressings attributed to the unique and good properties, including self-antibacterial property and antibacterial property in combination with different substances, excellent mechanical property, biocompatibility, etc. This article reviews the research of graphene and its derivatives in wound dressings.

[Study of iron overload assessment by T2* magnetic resonance imaging in patients with myelodysplastic syndromes]

Objectives: To analyze the cardiac T2* value, liver iron concentration (LIC) , and related laboratory parameters in myelodysplastic syndrome (MDS) with iron overload and evaluate the changes of organ functions after iron chelation therapy. To explore the value of magnetic resonance imaging (MRI) T2* in making early diagnosis and assessing organs iron overload. Methods: Retrospective investigation was used to observe the cardiac T2* value, LIC, iron metabolism parameters and related laboratory parameters of 85 MDS patients from Nov 2014 to Jan 2018. Among them, 7 MDS patients with Low/Int-1 have received iron chelation therapy for 6 months during two MRI examinations. The above parameters were collected before and after iron chelation therapy for comparison. Results: Correlations were found between heart T2* value and age (rs=-0.290, P=0.007) and left ventricular ejection fraction (LVEF) (rs=0.265, P=0.009) . There was a significant negative correlation between heart T2* value and blood transfusion units (rs=-0.701, P<0.001) . There was a significant positive correlation between LIC and serum ferritin (SF) (rs=0.577, P<0.001) . There was also a correlation between LIC and ALT (rs=0.268, P=0.014) and blood transfusion units (rs=0.244, P=0.034) . There was no correlation between heart T2* and pro-BNP, SF (all P>0.05) , and no correlation between LIC and age (P>0.05) . The increase of heart T2* between the normal and abnormal groups was statistically significant (P=0.005) , but the iron overload ratio of the heart T2*<20 ms was not significant between the two groups. There was statistical significance in the proportion of severe liver iron overload (LIC>15 mg/g DW) (P=0.045) . After iron chelation therapy, the values of SF, transferrin saturation, ALT, AST, pro-BNP and LIC of 7 patients were decreased compared with values before iron chelation therapy, and the peripheral blood cell level was increased. However, the changes of LVEF and T2* values after iron chelation were not obvious. Conclusion: MRI T2* may be a predictor of iron overload in patients with MDS in early stage, and may be more valuable compare with LVEF, SF and other laboratory indicators. The safety and repeatability of MRI cardiac T2* examination are recognized, and it can be used as an ideal detection for patients with iron overload.

[miR-202 contributes to sensitizing MM cells to drug significantly via activing JNK/SAPK signaling pathway]

目的

研究microRNA-202（miR-202）对多发性骨髓瘤（MM）细胞生长的影响，并初步探讨miR-202在MM细胞药物敏感性中的作用机制。

方法

荧光定量PCR检测miR-202及其靶基因B淋巴细胞刺激因子（BAFF）在MM细胞中的表达水平。将miR-202模拟物、miR-202抑制物、BAFF干扰质粒（siBAFF）及其阴性对照转染U266细胞，Western blot检测Bcl-2家族和MAPK信号通路蛋白的表达。WST-1法、流式细胞术（Annexin V-FLUOS）分别检测转染后U266细胞的增殖和凋亡情况。

结果

U266细胞、MM患者CD138⁺细胞中miR-202 mRNA表达（分别为0.052±0.009、0.304±0.354）均低于健康对照组（3.550±1.126）（P<0.001，P=0.009），BAFF表达水平（5.700±0.734、9.576±2.887）均高于健康对照组（1.819±0.853）（P<0.001，P=0.006）。miR-202模拟物转染组细胞增殖抑制率高于对照组[（56.04±0.02）％对（18.89±0.32）%，P=0.002]。Western blot结果显示，转染miR-202模拟物后，U266细胞Bcl-2表达下调约24%，而Bax蛋白的表达上调约1.24倍，miR-202模拟物组细胞凋亡率高于对照组[（49.60 ± 4.89）％对（26.20 ± 1.28）%，P=0.029]。硼替佐米和miR-202模拟物联合组细胞凋亡率为（51.23 ± 5.41）%，高于硼替佐米单独处理组（31.70 ± 4.40）％和硼替佐米与模拟物对照联合处理组[（51.23±5.41）％对（31.70±4.40）%，P=0.047；（51.23±5.41）％对（27.94±4.04）%，P=0.028）]，而miR-202模拟物联合沙利度胺和地塞米松与miR-202模拟物对照组相比差异无统计学意义[（11.66±1.91）％对（10.63±1.74）%，P=0.700；（16.35±1.32）％对（17.43±1.95）%，P=0.400]。miR-202模拟物联合硼替佐米对U266细胞的增殖抑制率高于硼替佐米单独处理组[（36.93±5.98）%对（18.18±4.10）%，P=0.029]。miR-202模拟物及硼替佐米处理U266细胞后，p-JNK蛋白表达水平下调。

结论

miR-202模拟物和硼替佐米可协同抑制MM细胞增殖、诱导其凋亡，可能通过miR-202负向调控靶基因BAFF的表达、抑制JNK/SAPK信号通路的活化来实现的。

Dietary supplementation with arginine and glutamic acid enhances key lipogenic gene expression in growing pigs

Our previous study showed dietary supplementation with Arg and Glu increased intramuscular fat deposition and decreased back fat thickness in pigs, suggesting that the genes involved in lipid metabolism might be regulated differently in muscle and s.c. adipose (SA) tissues. Sixty Duroc × Large White × Landrace pigs with an average initial BW of 77.1 ± 1.3 kg were randomly assigned to 1 of 5 treatment groups (castrated male to female ratio = 1:1). Pigs in the control group were fed a basic diet, and those in experimental groups were fed the basic diet supplemented with 2.05% alanine (isonitrogenous group), 1.00% arginine (Arg group), 1.00% glutamic acid + 1.44% alanine (Glu group), or 1.00% arginine + 1.00% glutamic acid (Arg+Glu group). Fatty acid percentages and mRNA expression levels of the genes involved in lipid metabolism in muscle and SA tissues were examined. The percentages of C14:0 and C16:0 in the SA tissue of Glu group pigs and C14:0 in the longissimus dorsi (LD) muscle of Glu and Arg+Glu groups decreased ( < 0.05) compared to the basic diet group. The Arg+Glu group showed the highest ( < 0.05) hormone-sensitive lipase expression level in SA tissue and higher ( < 0.05) mRNA levels of in the LD muscle than the basic diet and isonitrogenous groups. Additionally, the mRNA level of fatty acid synthase in the Arg+Glu group was more upregulated ( < 0.05) than that of the Arg group. An increase in the mRNA level of in the biceps femoris muscle was also observed in the Arg+Glu group ( < 0.05) compared with the basic diet and isonitrogenous groups. Collectively, these findings suggest that dietary supplementation with Arg and Glu upregulates the expression of genes involved in adipogenesis in muscle tissues and lipolysis in SA tissues.

Knockdown of REV3 synergizes with ATR inhibition to promote apoptosis induced by cisplatin in lung cancer cells

It has been demonstrated that REV3, the catalytic subunit of the translesion synthesis (TLS) polymerase ζ, play an important role in DNA damage response (DDR) induced by cisplatin, and Ataxia-telangietasia mutated and Rad-3-related (ATR) knase is a central player in activating cell cycle checkpoint, stabilizing replication forks, regulating DDR, and promoting repair of DNA damage caused by cisplatin. Cancer cells deficient in either one of REV3 and ATR are more sensitive to cisplatin. However, whether co-inhibition of REV3 and ATR can further increase sensitivity of non-small cell lung cancer (NSCLC) cells to cisplatin is not clear. In this study, we show that REV3 knockdown combined with ATR inhibition further enhance cytotoxicity of cisplatin in NSCLC cells, including cisplatin-sensitive and -resistant cell lines, compared to individual knockdown of REV3 or ATR, which are accompanied by markedly caspase-dependent apoptosis response, pronounced DNA damage accumulation and severe impediment of interstrand crosslink (ICL), and double strand break (DSB) repair. Our results suggest that REV3 knockdown synergize strongly with ATR inhibition to significantly increase sensitivity of cisplatin in NSCLC cells by inhibiting ICL and DSB repair. Thus simultaneously targeting REV3 and ATR may represent one approach to overcome cisplatin resistance and improve chemotherapeutic efficacy in NSCLC treatment.

Suppression of the FA pathway combined with CHK1 inhibitor hypersensitize lung cancer cells to gemcitabine

The combination of platinum and gemcitabine is one of the standard regimens in the treatment of advanced lung squamous carcinoma (LSC). Resistance to gemcitabine is main barrier to the successful treatment of LSC. In this study, we showed that suppression of the Fanconi anemia (FA) pathway increased the sensitivity of two LSC cell lines SK-MES-1 and KLN205 to gemcitabine. Moreover, we found that the CHK1 pathway and the FA pathway are functionally compensatory in the repair of DNA damage in the LSC cell lines. Inactivation of one of the two pathways led to DNA damage, triggering compensatory activation of other pathway. Furthermore, we demonstrated that FANCD2 depletion combined with CHK1 inhibitor MK-8776 significantly potentiated the cytotoxicity of gemcitabine to the two LSC cell lines, compared to individual FANCD2 depletion or MK-8776 treatment. The enhanced effect of gemcitabine-chemosensitization was accompanied by loss of DNA repair function and accumulation of DNA single strand breaks and double strand breaks, in parallel with obvious increase of caspase-3 dependent apoptosis. Our results indicate that the enhancement effect of FANCD2 depletion combined with CHK1 inhibitor in sensitizing the LCS cells to gemcitabine supports the FA pathway and CHK1 as two therapeutic targets for improvement of anti-tumor regimens in treatment of LSC.

[Study of abnormal iron metabolism parameters and iron overload in patients with myelodysplastic syndromes]

Objective: To investigate the abnormalities of iron metabolism parameters, the prevalence and risk factors of iron overload and clinical characteristics of patients with myelodysplastic syndromes(MDS). Methods: Retrospective investigation was used to observe abnormal iron metabolism parameters and clinical characteristics of newly diagnosed 94 MDS patients in our center from June 2015 to March 2016. Results: Of 94 patients, 71(75.53%)had a hemoglobin level of less than 100 g/L at diagnosis. Iron overload was observed in 52(55.32%)of 94 MDS patients, in which a higher prevalence of iron overload was observed in low risk groups(IPSS low/Int-1 risk groups)than higher risk groups(Int-2/high risk groups). Higher levels of serum iron(SI)[36.5(8.5-64.7)mmol/L vs 25.2(3.7-45.3)mmol/L, P<0.01], transferrin saturation(TSAT)[43.5(12.2-77.2)% vs 53.4(14.8-97.5)%, P <0.01]and serum ferritin(SF)were observed in iron overload group. No differences of labile cellular iron(LCI)and reactive oxygen species(ROS)were observed between two groups(P=0.88, P=0.06). As the results of clinical complication of iron overload, alanine aminotransferase(ALT)[25(3-158)U/L vs 16(5-80)U/L, P=0.03]and type B natriuretic peptide precursor(proBNP)[190(6-4281)ng/L vs 84(12-2 275)ng/L, P= 0.05]levels were increased in iron overload group. There was no significant difference in iron metabolism parameters between patients with refractory anemia(RARS)and non RARS patients(P>0.05). Both frequency and volume of RBC transfusion had a significant effect on all iron metabolism parameters(SI, TSAT and SF)(P <0.01)except LCI and ROS. Excluded the patients with history of blood transfusion and SF levels over 1 000 μg/L, higher levels of LCI were mainly observed in dysplastic erythropoiesis and increased bone marrow erythroblasts ratio groups(P<0.01, P<0.05). Conclusion: The main cause of iron overload in MDS is chronic transfusion therapy. Both frequency and intensity of transfusion regimen have a main effect on iron metabolism parameters. LCI levels are mainly increased in newly diagnosed patients with the abnormalities of iron metabolism and have a stronger association with dysplastic erythropoiesis and increased bone marrow erythroblasts ratio. As the toxic fraction of iron and its negative impact on MDS, iron overload monitoring and chelation treatment decision can also be supported by LCI.

Fabrication of Ag-Decorated CaTiO₃ Nanoparticles and Their Enhanced Photocatalytic Activity for Dye Degradation

CaTiO₃nanoparticles of 30-40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8-16 nm were deposited onto CaTiO₃particles by a photochemical reduction method to yield CaTiO₃@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO₃ particles exhibit an enhanced photocatalytic activity compared to bare CaTiO₃ particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO₃particles to 72% for CaTiO₃@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH⁻/H₂O to generate hydroxyl (·OH) radicals. ·OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO₃@Ag composites. In addition, it is found that the addition of ethanol, which acts as an ·OH scavenger, leads to a quenching of ·OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that ·OH radicals are the dominant active species responsible for the dye degradation.

HIV testing rate in the top end of the Northern Territory of Australia: room for improvement

The Northern Territory of Australia has an exceptionally high prevalence of sexually transmitted infections (STIs), particularly in remote areas. In contrast there are few notified cases of HIV at present. This study describes HIV testing rates in both primary care and sexual health clinics in the Top End region. In 2010, medical records were reviewed for a random sample of patients from a sexual health clinic and three remote primary care clinics. Among sexual health clinic patients 51.4% overall, and 59.7% of those with an STI, were tested for HIV. In people diagnosed with an STI in remote primary care clinics 19.1% were tested for HIV. HIV testing rates in the Top End of the Northern Territory do not meet the standard of national and international guidelines, with implications both for the early initiation of therapy and the accuracy of surveillance in a region with very high rates of STIs.

Total knee arthroplasty after failed dome osteotomy

A retrospective, clinical and radiographic analysis was done between a study group of 15 patients with 17 total knee arthroplasties done following failed, proximal-tibial dome osteotomies and a control group of 14 patients with 17 primary arthroplasties. The groups were matched according to age of patients, type of prosthesis, primary disease and length of follow-up. The average length of follow-up was 59.4 months (range, 25-146 mo) in the study group and 62.3 months (range, 43-140 mo) in the control group. On the basis of the knee rating scale of the American Knee Society, 94% of the patients had either an excellent or a good result in the study group. There were no significant differences in knee scores, function scores, or range of motion of the knee between the two groups during the follow-up period. Although two overcorrected valgus knees and one severe varus knee necessitated an autogeneic bone graft for tibial defects at the time of implantation of the secondary prosthesis, dome osteotomy does not appear to compromise a subsequent arthroplasty.

Ultrasonographic study of the coexistence of muscular torticollis and dysplasia of the hip

The consistent relationship between congenital muscular torticollis and dysplasia of the hip is now widely accepted. However, the coexistence rate of these two disorders has been reported with variations from 0 to 20%. To obtain a more accurate coexistence rate, ultrasound scanner was used as the diagnostic tool for both of these disorders.Sixty-three children (30 boys and 33 girls) younger than 6 months who had undergone ultrasound scanning of both bilateral sternocleidomastoid muscle and bilateral hips were included in this study. Forty-seven children were confirmed to have muscular torticollis, and the remaining 16 cases were diagnosed as postural torticollis. Only these 47 cases were included for analysis of the coexistence rate. Eight children were found with dysplasia of the hips associated with muscular torticollis, which included Graf's type IIa for four hips, type IIb for two hips, type IIIa for one hip, and type IIIb for one hip. From the results of the present ultrasonographic study, the coexistence rate of congenital muscular torticollis and dysplasia of the hip was concluded to be 17%. If only those dysplastic hips (type IIb, IIIa, IIIb) that required treatment were included, the coexistence rate would be lowered to 8.5%.

MicroStructured Omnifit acetabular components: concerns with locking system complications and excessive polyethylene wear

BACKGROUND

We began to use cementless MicroStructured Omnifit acetabular components in November 1988. Liner dislodging and excessive polyethylene wear later occurred in some of our patients. This finding prompted us to review our experience with the use of such modular acetabular components.

METHODS

A total of 887 hips in 672 patients, which had been fitted with cementless MicroStructured Omnifit acetabular components, were evaluated for locking system complications using radiographic examinations. Of the cases, 240 hips which had received a 26-mm femoral head (group 1) and 110 hips which had received a 32-mm femoral head (group 2) were compared using a digitiser to determine the influence of femoral head size on polyethylene wear.

RESULTS

There were two types of radiographic signs of locking system complications in 7 hips, at a mean time of 2.9 years after implantation. The incidence of liner locking system complications using this modular acetabular component was 0.8%. The mean liner wear rate per year was 0.15 mm in group 1 and 0.20 mm in group 2 (p <0.005). The initial polyethylene thickness ranged from 5.9 to 13.6 mm in group 1, compared with 3.9 to 10.6 mm in group 2 (p < 0.005).

CONCLUSION

A patient who has received a total hip arthroplasty that includes a MicroStructured Omnifit acetabular component should be monitored frequently for radiographic signs of locking system complications. In this study, the mean liner wear rate was significantly higher in group 2. Inadequate polyethylene thickness in this group was implicated as the major cause of excessive polyethylene wear.

Adult monteggia fracture with ipsilateral distal radius fracture: case report

Although the adult Monteggia fracture is a well-known injury, the combination of a Monteggia fracture and an ipsilateral distal radius fracture is extremely rare. It is important for the treating physician to recognize that this injury involves not only the bone elements but also their articulations. The distortion of the integrity of both the elbow and the wrist results in the potential for functional compromise, if inadequately treated. The case report presented here describes a 21-year-old woman with this complex injury resulting from a fall. The injury included a Monteggia type II fracture and an ipsilateral distal radius intra-articular fracture in the left forearm. An excellent result was obtained by surgical intervention in both the radial and ulnar bones. The factors we believe contributed to the excellent result were early diagnosis, anatomic reduction, stable fixation, and early physical exercise. The mechanism of injury giving rise to this rare combination of fractures is discussed, as well as a review of the literature.

Anterior knee pain after intramedullary tibial nailing

BACKGROUND

Currently, intramedullary nailing is a well-accepted method for treating tibial shaft fractures, but some patients complain of anterior knee pain after surgery. Multiple factors may influence this troublesome complication.

METHODS

This was a retrospective analysis of the medical records of 200 patients who were treated with intramedullary nailing after tibial shaft fractures. Sixty-four patients complained of knee pain after surgery. We evaluated the knee pain in relation to the surgical approach, radiographic readings, and the type of nail used.

RESULTS

Among the 64 patients, 45 (70%) received central approaches and 19 (30%) received paramedial approaches (p = 0.0002); 46 patients (72%) showed nail protrusions on radiographs and only 18 patients (28%) were without nail impingement (p = 0.0001). Forty-three patients (67%) received Kuntscher nail fixation and just 21 patients (33%) had interlocking nail fixation (p = 0.0015).

CONCLUSION

The use of the central patellar tendon splitted approach, nail protrusion observed on radiographs, and the insertion of a non-locking intramedullary nail were all significant risk factors for anterior knee pain after surgery. All these risk factors should be avoided in tibial nailing to decrease the problem of postoperative knee pain.

The influence of the gap size on the interfacial union between the bone and the tendon

An in-vivo model of New Zealand white rabbit was used to study the influence of gap size on the interfacial union between bone and tendon through histological observation and mechanical testing. In the model, the anterior cruciate ligament (ACL) was cut and reconstructed by autografted semitendinosus tendon (with average diameter of 1.48 mm +/- 0.12 mm). Mechanical testing of the interfacial healing tissue was done on the 15th post-operative day. At that time the mean maximal tensile strength was 2.511 +/- 0.293 kg to a bone tunnel size of 1.5 mm. The maximal tensile strength lowered to 1.853 +/- 0.563 kg to a bone tunnel size of 1.8 mm. The maximal tensile strength lowered to 1.302 +/- 0.657 kg to a bone tunnel size of 2.0 mm. Using a paired-t test, the gap size was found to have great influence on the tensile strength of the interfacial healing tissue (p < 0.05). The histological study showed that the interfacial gap was connected by the new growing collagen fibers. The healing tissue appeared much denser and much more maturated and organized in the smaller interfacial gap in comparison with specimens with a larger gap so that it can tolerate higher tensile strength. From this study, we concluded that the gap size really plays an important role in the process of maturation and organization of interfacial healing tissue. Furthermore, we recommend that in order to achieve greater anchoring strength of the grafted tendons, the bone tunnel should be made with approximately the same diameter of grafted tendon.

Reduction of H2O2-evoked, intracellular calcium increases in the rat N18-RE-105 neuronal cell line by pretreatment with an electrophilic antioxidant inducer

Pretreatment of the neuronal cell line N18-RE-105 with the antioxidant enzyme inducer dimethyl fumarate (DMF) reduced cell death elicited by H2O2 (50 mM for 1 h) as measured 24 h after H2O2 washout. Oxidants like H2O2 may contribute to cell death by increasing intracellular ionized calcium ([Ca2+]i), suggesting that DMF may in part confer protection by altering H2O2-induced [Ca2+]i signals. To examine this possibility, we measured [Ca2+]i of fura-2-loaded cultures of DMF- and vehicle-pretreated cells during H2O2 superfusion. H2O2 exposure induced a delayed [Ca2+]i increase that was significantly lower in DMF-pretreated cells than controls. Elevation of extracellular cystine also reduced the H2O2 induced [Ca2+]i elevation. Thus, antioxidant upregulation may contribute to protection during oxidative stress by stabilizing [Ca2+]i. However, since oxidative stress may induce cytotoxicity by multiple pathways, [Ca2+]i stabilization may not be the only mechanism responsible for the protective effect of DMF.

[The role of endogenous CO in the regulation of endothelin-induced VSMC proliferation and MAPK activity]

Heme oxygenase (HO) is a rate-limiting enzyme of heme degradation, which converts the cellular heme to bilirubin and carbon monoxide (CO). Recently it is suggested that endogenous CO plays an important role in regulating vascular tone under both physiological and pathological conditions, but it is not clear whether endogenous HO/CO system regulates vascular smooth muscle cell (VSMC) proliferation. In the present study, VMSC 3H-TdR incorporation, mitogen-activated protein kinase (MAPK) activity, HO activity and CO release were determined to study the role of endogenous HO/CO system in regulating the VSMC proliferation induced by endothelin-1 (ET-1) in a cultured system. The results showed that ET-1 increased VSMC 3H-TdR incorporation, MAPK activity, HO activity, and CO release were up-regulated. Pretreatment of HO inhibitor, zinc protoporphyrin-9 (ZnPP-9), increased the ET-1-induced VSMC 3H-TdR incorporation and MAPK activity by 31.8% and 36.6% (P < 0.01, respectively), whereas pretreatment of heme-L-lysinate (HLL), a HO substrate, inhibited these activities. This study demonstrated that up-regulation of VSMC endogenous HO represents a cellular protective response to stress or injury. Inhibition of HO may enhance VSMC proliferation induced by ET-1 in vitro, suggesting that endogenous HO/CO system may be directly involved in the regulation of VSMC proliferation through MAPK signaling pathway.

Knee dislocation: treatment of high-velocity knee dislocation

BACKGROUND

We report the outcomes of patients treated with a new arthroscopic treatment modality for knee dislocation after high-velocity trauma.

METHODS

Twenty-three patients (12 men, 11 women; 25 knees) with traumatic knee dislocation were treated with this technique. Under arthroscopy with gravity inflow irrigation, the ruptured posterior cruciate ligament was reconstructed with a patellar bone-tendon-bone graft, and the anterior cruciate ligament was debrided subacutely. The collateral ligament, meniscus, and capsules were repaired through additional incisions.

RESULTS

The average interval between injury and surgery was 11.1+/-5 days (range, 5 to 25 days). After a mean follow-up period of 27.2+/-7.86 months, the mean extension was 1+/-2 degrees and the average flexion was 129.6+/-4.91 degrees. The mean Lysholm score was 84. There were no major complications.

CONCLUSION

Arthroscopic posterior cruciate ligament reconstruction seems to be an effective treatment for traumatic knee dislocation.

Role of endogenous carbon monoxide in the pathogenesis of hypotension during septic shock

A sepsis model induced by cecal ligation and puncture was used to study the role of endogenous carbon monoxide in hypotension pathogenesis of rats during septic shock. After administration of zinc deuteroporphyrin 2,4-bisglycol (ZnDPBG),an inhibitor of heme oxygenase (HO),blood pressure (BP),HO activity and carbon monoxide (CO) release from vascular muscle tissue were measured. The results showed that BP of sepsis rats, including systolic and diastolic arterial BP, decreased significantly while HO activity and CO content were significantly increased. In contrast, after administration of ZnDPBG, BP of sepsis rats was significantly increased while the HO activity and CO production were significantly decreased. These findings suggest that HO activity and CO release within vascular musculature are increased during septic shock; inhibition of HO may elevate BP of rats during septic shock through a decrease of endogenous CO production. It is concluded that endogenous CO derived from vascular muscle cells plays an important role in regulating vascular tone, and the up-regulation of HO activity followed by subsequent CO production contributes to hypotension pathogenesis during septic shock.

Role of endogenous carbon monoxide in hypertension pathogenesis of rats

The present study investigated the contribution of endogenous heme oxygenase (HO)/carbon monoxide (CO) system to hypertension pathogenesis of rats. Zinc deuteroporphyrin 2,4-bisglycol (ZnDPBG), an inhibitor of heme oxygenase (HO), was used to inhibit HO activity in vivo. It was found that the blood pressure of rats with HO inhibition was significantly elevated, and plasma levels of adrenaline, noradrenaline, endothelin, nitrate and nitrite were significantly increased. HO activity and HbCO formation within vascular smooth muscle tissues were significantly inhibited after administration of ZnDPBG. Furthermore, administration of exogenous CO into HO inhibiting rats led to MABP decrease, but injection of HO substrate, heme-L-lysinate, had no effect on HO inhibition-induced hypertension. In spontaneously hypertensive rats, injection of exogenous CO resulted in a significant decrease of MABP, and heme-L-lysinate had a similar effect with exogenous CO. These data show that HO/CO system has an anti-hypertension biological action, suggesting that endogenous CO plays an important role in hypertension pathogenesis.

Mechanisms of isoflurane-increased submaximum Ca2+-activated force in rabbit skinned femoral arterial strips

BACKGROUND

Isoflurane enhances contraction in isolated intact arterial rings by a protein kinase C (PKC) activator and also causes contracture in skinned arterial strips. This study investigated the mechanisms of this isoflurane activation of the contractile proteins of skinned strips.

METHODS

The skinned strips, mounted on photodiode force transducers, were prepared from rabbit femoral arteries treated with saponin. The strips were activated by 1 microM Ca2+ (buffered with 7 mM EGTA) with or without inhibitors for PKC and calmodulin-dependent protein kinase II (CaM kinase II). When force reached steady state, isoflurane was administered and changes in force were observed. Another group of the strips was frozen to assay myosin light chain phosphorylation (MLC-p) using two-dimensional electrophoresis and immunoblotting. Analysis of variance was used to compare the results from test and control groups. Probability values <0.05 were significant.

RESULTS

Isoflurane (1-5%) dose dependently increased (24-81%) the Ca2+-activated force. At 1% and 5% isoflurane, MLC-p did not change either as the force increased or reached a new steady state level. However, with 3% isoflurane, MLC-p transiently decreased (29.1% and 17.1% of total MLC for 0% and 3% isoflurane, respectively). The 3% isoflurane-increased force was blocked by 10 microM bisindolymaleidmide, an inhibitor of PKC, but not by 10 microM Gö-6976, an inhibitor of Ca2+-dependent PKC, and was enhanced 50% by 0.1 mM KN-62, an inhibitor of CaM kinase II.

CONCLUSIONS

Isoflurane increased submaximum Ca2+-activated force in skinned femoral arterial strips by activating Ca2+-independent PKC, possibly epsilon isoezyme. The isoflurane-decreased MLC-p may be caused by activation of CaM kinase II.

Inhibitory effect of trapidil on proliferation of cultured rat aortic smooth muscle cells induced by endothelin-1

AIM

To study the effect of trapidil (Tra) on endothelin-1-induced proliferation of cultured rat aortic vascular smooth muscle cells (VSMC).

METHODS

The [3H]TdR incorporation into DNA assay, the number of VSMC, and cell cycle distribution were measured.

RESULTS

Pretreated with endothelin-1 100 nmol.L-1, cell number, [3H]TdR uptake, and cell mitogenic activity increased 134% +/- 23%, 210% +/- 70%, and 86% +/- 18%, respectively. This proliferation was inhibited by Tra 5, 50, 500 mumol.L-1. The inhibitory rates were 12%-48%, 35%-54% and 15%-47%, respectively. Tra did not influence the proliferation of VSMC without endothelin-1 pretreatment.

CONCLUSION

Tra antagonized the proliferation of VSMC induced by endothelin-1.

Effects of halothane on the sarcoplasmic reticulum Ca2+ stores and contractile proteins in rabbit pulmonary arteries

BACKGROUND

The authors' purpose of this study was to elucidate the mechanisms of direct effects of halothane on the contractile proteins and Ca2+ release from the sarcoplasmic reticulum Ca2+ stores using isolated skinned strips (sarcolemma permealized with saponin) from rabbit pulmonary arteries.

METHODS

The sarcoplasmic reticular Ca2+ stores were examined by immersing the skinned strips sequentially in solutions to load Ca2+ into and release Ca2+ from the sarcoplasmic reticulum using caffeine, inositol 1,4,5-trisphosphate, or halothane. The contractile proteins were assessed by activating the strips with Ca2+ followed by administration of halothane (with or without protein kinase C inhibitors). Tension, fura-2 fluorescence activated by Ca2+ release, and phosphorylation of myosin light chains were measured.

RESULTS

Halothane (0.07-3.00%) increased Ca2+, tension, and phosphorylation of myosin light chains in a dose-dependent manner. Halothane decreased accumulation of Ca2+ in the sarcoplasmic reticulum and enhanced the caffeine-induced tension transients. In strips pretreated with caffeine or inositol 1,4,5-trisphosphate, halothane-induced tension transients were reduced but Ca2+ was not. In strips activated by 1 microM Ca2+, halothane (0.5-3.0%) decreased 20-45% of the activated force at 15 min. Halothane (3%) transiently increased the force (20%) associated with increases in Ca2+ and phosphorylation of myosin light chains. The increased force was abolished and the subsequent relaxation was enhanced by the protein kinase C inhibitor bisindolylmaleimide but not by indolocarbazole Gö-6976.

CONCLUSIONS

In skinned pulmonary arterial strips, halothane, at clinical concentrations, inhibits uptake of Ca2+ by and induces release of Ca2+ from intracellular stores possibly shared by caffeine and inositol 1,4,5-trisphosphate, which are regulated by phosphorylation of myosin light chains. The time-dependent inhibition of the contractile proteins by halothane may be mediated by Ca2+-independent protein kinase C.

[Effect of Arg-Gly-Asp-Ser (RGDS) peptide on ADP-induced signal transduction of activated rat platelet]

The purpose of this work was to investigate the effect of Arg-Gly-Asp-Ser (RGDS) peptide on platelet aggregation, protein phosphorylation, protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activity during platelet activation. Experiments were performed on ADP activated rat platelets in vivo. Results showed that 50 mumol/L ADP, in addition to inducing platelet aggregation, obviously enhanced not only PKC and MAPK activities but also 95 and 66 kD protein phosphorylation. When platelets and ADP were incubated together with 50, 100, 200 mumol/L RGDS peptide it was found that the latter markedly inhibited ADP activated platelet aggregation and activation of PKC and MAPK, both in a concentration-dependently manner. RGDS peptide also inhibited 95 and 66 kD protein phosphorylation concentration-dependently and went positively with its activation of PKC and MAPK. The above result suggested that the antithrombotic effect of RGDS peptide was probably mediated through its effect on intracellular signal transduction in the ADP activation of platelets.

Allogeneic cortical strut for benign lesions of the humerus in adolescents

Allogeneic cortical strut associated with or without cancellous bone grafting for benign adolescent humeral shaft lesions is an alternative management option offering a good chance of stabilization and healing. This study monitored 16 patients who had been treated with this surgical method from 1988 to 1993. There were nine boys and seven girls between the ages of 11 and 16 years (average, 14). Eleven patients had unicameral bone cysts; two had aneurysmal bone cysts; and three had fibrous dysplasia. All 16 patients received fresh-frozen (-70 degrees C) cortical strut inlay grafts in the humeral shaft defect after subtotal excision of the large lesions. No intramedullary rod or plate was used. The follow-up period ranged from 26 to 58 months (average, 41). There were no local recurrences or fractures of the shaft or allograft implants. The radiographs of all humeri revealed the cortical grafts to be well incorporated with new bone formation in the cavity. The overall functional results were good and excellent. This reconstruction with biologically safe and active material provided increased strength and prevented refracture.

Efficient enzymatic synthesis of 13C,15N-labeled DNA for NMR studies

The power of heteronuclear NMR spectroscopy to study macromolecules and their complexes has been amply demonstrated over the last decade. The obstacle to routinely applying these techniques to the study of DNA has been the synthesis of 13C,15N-labeled DNA. Here we present a simple and efficient method to generate isotope-labeled DNA for NMR studies that is as easy as that for isotope labeling of RNA. The method was used to synthesize a uniformly 13C,15N-labeled 32-nucleotide DNA that binds to human basic fibroblast growth factor with high affinity and specificity. Isotope-edited experiments were applied to the 13C,15N-labeled DNA bound to unlabeled protein, and the 13C,15N-labeled DNA was also examined in complex with 15N-labeled protein. The NMR experiments show that the DNA adopts a well-defined stable structure when bound to the protein, and illustrate the potential of 13C,15N-labeled DNA for structural studies of DNA-protein complexes.

[Effects of hypoxia/reoxygenation on mitogen-activated protein kinase activity in cultured neonatal rabbit cardiac myocytes]

Cardiomyocytes subjected to brief episode of hypoxia possess a resistance to serious damaging effect exerted by a subsequent long-time hypoxia on these cells, which is called hypoxic preconditioning (PC). The pathway of intracellular signal transduction during hypoxia PC has not yet been validated. On a model of hypoxia/reoxygenation (H/R) of cultured neonatal rabbit cardiomyocytes, the present study is taken to investigate the changes of mitogen-activated protein kinase (MAPK) and ribosomal S6 kinase (S6K) activity. It was found that intracellular total MAPK and nuclear MAPK, after a 15-min period of reoxygenation preceded by a single 60-min period of hypoxia, were increased by 95% and 230%, respectively. Intracellular S6K activity increased by 142% at 30 min of H/R vs the control group (P < 0.01). Phosphatase 1 (PPase 1) inhibitor (ocadaic acid, OA 1 mumol/L) augmented the increase of MAPK and S6K activity induced by H/R. However, tyrosine kinase (Tyr K) inhibitor (genistein), protein kinase C (PKC) inhibitor (H7) and preincubation of cardiomyocytes with PKC activator PMA all reduced MAPK activation by H/R. Protein kinase A (PKA) inhibitor (H89), Ca2+/Calmodulin-dependent protein kinase (PKM) inhibitor (W7) or PPase 2a inhibitor (OA 10 nmol/L) had no significant effect on MAPK and S6K activity. The above results suggested that activation of MAPK and S6K activity during hypoxia/reoxygenation there might require participation of PKC, Tyr K and PPase 1, while PKA, PKM and PPase 2a were not involved.

Effects of recombinant human endothelial-derived interleukin-8 on hemorrhagic shock in rats

AIM

To study the effects of recombinant human endothelial-derived interleukin-8 (IL-8) on hemorrhagic shock.

METHODS

A profound hemorrhagic shock in rats was produced by exsanguination from femoral artery with mean arterial blood pressure (MABP) maintained at 5.32 kPa for 90 min. After transfusion, IL-8 250 micrograms.kg-1 was i.v. injected. Plasma endothelin-1 (ET-1) and 6 ketoprostaglandin F1 alpha (6-KPGF1 alpha) contents were determined with radioimmunoassay.

RESULTS

After i.v. IL-8, the MABP in IL-8 group was elevated obviously (P < 0.01), the rat survival 2 h after infusion was increased (P < 0.05). During profound shock the plasma ET-1 levels were higher (21 +/- 4 vs 8.2 +/- 1.8 ng.L-1, P < 0.01) and the plasma 6-KPGF1 alpha contents lower than those in normal rats (107 +/- 12 vs 157 +/- 11 ng.L-1, P < 0.01). IL-8 remarkably reduced the plasma ET-1 levels (10 +/- 4 ng.L-1, P < 0.01) and enhanced plasma 6-KPGF1 alpha contents (368 +/- 16 ng.L-1, P < 0.01).

CONCLUSION

IL-8 has beneficial antishock effects.

[Effect of anoxic preconditioning on protein kinase C activity in neonatal rat cardiomyocytes]

In a model of anoxia/reoxygenation (A/R) of cultured rat cardiomyocytes, protection of cellular damage, activation of protein kinase C (PKC) and PKC-mediated protein phosphorylation by anoxic preconditioning (APC) can be demonstrated as shown by the increase of cell viability, attenuation of formation of lipid peroxides (MDA) and lowering of the leakage of lactate dehydrogenase (LDH) and protein from cells. The results also show that transient anoxia mimicked the outcomes of activation of PKC as shown by increased incorporation of 32P, especially in the 66 kD and 31 kD protein fractions. Preincubation of cardiomyocytes with H7 (an inhibitor of PKC) completely abolished these protective effects of transient anoxia. Protein phosphatase inhibitor OA mimicked the protective effects of A/R, while protein phosphatase activator BDM induced a complete abolishment. In short, we conclude that the protective effect of APC is medicated by activation of PKC.

[Effects of basic fibroblast growth factor on anoxia/reoxygenation injury of rat neonatal cardiomyocytes]

The effects of basic fibroblast growth factor (bFGF) on anoxia/reoxygenation (A/R) injury and protein kinase C (PKC) activity were studied on a model of A/R injury of neonatal rat cardiomyocytes to investigate the possibility of its using as a substrate for pharmacological preconditioning. The data indicated that bFGF improved the viability of cardiomyocytes, lowered the deplection of ATP and leakage of intracellular lactate dehydrogenase (LDH) in a concentration-dependent manner. PKC inhibitor, H7, completely abolished the protective effects. It was also found that bFGF directely activated PKC in cardiomyocytes in a time course similar to that in hypoxic preconditioning. The data suggested that the protective effect of bFGF on cardiomyocyte A/R injury might be mediated by PKC.

[Changes of calcium transport in rat liver nuclei during sepsis]

Calcium transport changes in rat liver nuclei were observed on the model of early sepsis (9 h after operation of cecal ligation and puncture). Calcium content in hepatocytes and nuclei were significantly increased by 20% and 36% respectively (P < 0.05) during sepsis. The activity of Ca(2+)-ATPase in hepatocytic nuclei was increased by 94% (P < 0.01) and 45Ca2+ transport accelerated by 32% (P < 0.01). There was a positive correlation between nuclear 45Ca2+ transport and nuclear Ca(2+)-ATPase activity (r = 0.914, P < 0.01). Calmodulin stimulated the activity of nuclear Ca(2+)-ATPase and 45Ca2+ transport; while calmodulin inhibitor trifluoperazine exerted an opposite effect. The above results suggest that liver nuclear calcium transport is strengthened during early sepsis as a result of changes of Ca(2+)-ATPase activity.

[L-arginine transport in cultured vascular smooth muscle cells of spontaneously hypertensive rats and effect of liposome on the transport]

The characteristics of L-arginine (L-Arg) transport in cultured aortic smooth muscle cells (SMC) of spontaneously hypertensive rat (SHR) and control WKY rats were studied and the effect of liposome as L-Arg carrier on the transport was investigated. The results showed that the L-Arg transport of SMC in SHR was obviously lower than that in WKY rats. Maximum transport velocity (Vmax) of high and low affinity in SHR were respectively 48% (P < 0.01) and 49% (P < 0.01) of WKY rat, while the michaelis constant (K(m)) showed no significant difference (P > 0.05). Increase of L-Arg transport induced by tumor necrosis factor-alpha (TNF alpha) in SMC of SHR was obviously lower than that in WKY rats (P < 0.01). The uptake of L-Arg increased 10 to 20 times in SMC when incubated with liposome encapsulated L-Arg (Liposome-L-Arg) than with free L-Arg. The transport velocity in SMC incubated with liposome-L-Arg showed no significant difference in SHR and WKY rats (P > 0.05). The transport of liposome-L-Arg in SMC was not affected by TNF alpha in both the types of rats. The above results indicate that there exists a functional disturbance in L-Arg transport in the SMC of SHR, but the L-Arg transport in SMC can be obviously enhanced when liposome is used as L-Arg carrier. Thus, it appears that liposome-L-Arg may have clinical perspective in the treatment of hypertension.

Cloning and characterization of a novel serine/threonine protein kinase expressed in early Xenopus embryos

We have cloned from a Xenopus ovary cDNA library a novel protein kinase gene whose expression peaks in the oocyte and unfertilized egg, begins to decrease gradually after fertilization, and disappears during the gastrulation stage of embryogenesis. The cloned gene, termed XEEK1 (for Xenopus egg and embryo kinase), encodes a protein with a predicted molecular mass of 49 kDa. Bacterially expressed XEEK1 migrates at 57 kDa upon polyacrylamide gel electrophoresis analysis, and a XEEK1-specific antibody recognizes a protein of 57 kDa in Xenopus oocyte and egg extracts. The XEEK1 kinase domain shares 35% identity (approximately 65% similarity) with the yeast SNF1 kinase and related kinases. However, expression of XEEK1 does not complement a snf1 deletion mutation in yeast, which suggests that it is probably not a Xenopus homolog of SNF1. Recombinant XEEK1 protein autophosphorylates on threonine residues in vitro in a reaction that prefers Mn2+ to Mg2+ ions. Site-directed mutagenesis of the conserved lysine residue (Lys-81) within the kinase domain to isoleucine totally abolishes kinase activity, and threonine 192 has been identified as the autophosphorylation site. This site is distinct from the conserved threonine (Thr-215 in XEEK1) present in the protein kinase activation loop that is the site of autophosphorylation for many protein kinases. XEEK1 is a substrate for the cyclic AMP-dependent protein kinase both in vitro and in vivo, suggesting a possible mode of regulation of XEEK1. An immunoprecipitate of oocyte/egg extracts with anti-XEEK1 serum contains a protein of approximately 155 kDa that may be a substrate and/or a regulatory component of the kinase.

Mechanisms of action of isoflurane on contraction of rabbit conduit artery

Isoflurane may cause differential effects on different vascular beds of the same animal species. The mechanisms of this action have not been elucidated. Accordingly, we compared in rabbit aorta and femoral artery the effects of isoflurane (1-3.3%) in isolated rings (endothelium denuded) activated by norepinephrine, and isoflurane effects on Ca2+ fluxes from the sarcoplasmic reticulum in skinned strips. When < 30 nM norepinephrine was used to cause ring contraction, isoflurane increased the force of contraction in aortic rings, but decreased force in femoral arterial rings. At 30 nM norepinephrine stimulation, 3.3% isoflurane decreased the force and, in the presence of verapamil, isoflurane actually increased the force in both arterial types. In skinned strips of both arterial types, isoflurane present during Ca2+ uptake decreased the caffeine-induced tension transients, whereas isoflurane present during Ca2+ release enhanced the transients. Isoflurane potentiated the depression of the tension transients by ryanodine. Isoflurane directly caused contracture even in the absence of caffeine. Thus, isoflurane has similar cellular mechanisms of action in the aortic and femoral arterial smooth muscle: inhibiting Ca2+ influx through the sarcolemma, decreasing Ca2+ uptake by the sarcoplasmic reticulum, and enhancing caffeine-induced Ca2+ release from the sarcoplasmic reticulum.

Effects of Arg-Gly-Asp-Ser on Ca2+ transport of myocardial sarcoplasmic reticulum in rat septic shock

AIM

To study the effects of Arg-Gly-Asp-Ser (RGDS), a synthetic short peptide of fibrinogen degradation, on the Ca2+ transport function of cardiac sarcoplasmic reticulum in rat septic shock.

METHODS

RGDS 5 mumol.kg-1 was injected i.v. at 4 h and 14 h after cecal ligation and puncture (CLP) operation on rats. Highly purified membrane of sarcoplasmic reticulum (SR) was prepared from rat hearts. Assays were made of ATP-dependent Ca2+ uptake by cardiac SR and [3H] ryanodine binding to SR.

RESULTS

The initial rate and the capacity of SR Ca2+ uptake were increased by 104% (P < 0.01) and 12% (P < 0.05), respectively, paralleled by an increase in Ca(2+)-ATPase activity and a decrease in calcium accumulation of myo- cardium of septic rats, whereas the Bmax and Kd values of Ca2+ activated [3H]ryanodine binding to SR were unaffected after RGDS administration.

CONCLUSIONS

The results indicated that RGDS have cardioprotective effects of maintaining Ca2+ homeostasis of cardiac myocytes by enhancing SR Ca2+ uptake in rat septic shock.

Total knee arthroplasty in tuberculous arthritis

Sixteen cases of tuberculosis of the knee treated by total knee arthroplasty with followup of 3.4 to 11 years were reviewed. Eight cases were treated with antituberculous chemotherapy for 2 to 20 months before and 1 year after the arthroplasty. Another 8 cases were not diagnosed primarily and therefore received only postoperative antituberculous chemotherapy. Five cases had a recurrence of tuberculosis. Four of these 5 cases did not receive preoperative antituberculous treatment. The infection in 1 case was controlled satisfactorily with chemotherapy alone, and for the other 3 cases, chemotherapy was supported by surgical debridements. The last case of recurrent infection occurred in a patient who had received long- standing corticosteroid therapy. He required an excisional arthroplasty to control the infection. The mean functional knee score was 30.5 points before surgery and 82.6 points at the time of the last followup. These results suggest that arthroplasty may be formed for knees badly damaged with tuberculous infection, and good results may be expected for those patients who have received effective antituberculous chemotherapy both before and after surgery. There is a substantial risk of reactivation of tuberculous infection for those patients not treated before surgery or for patients dependent on corticosteroids.

Arthroscopic debridement for osteoarthritis of the knee: a seven years follow-up study

We reviewed 32 knees with osteoarthritis of the knee treated by either arthroscopic debridement in association with drilling the subchondral bone or arthroscopic debridement alone and followed for 2.5 to 11 years. Eighteen knees had arthroscopic debridement and drilling the subchondral bone, and 14 knees had arthroscopic debridement alone. In the group treated with arthroscopic debridement and drilling the subchondral bone, 55.6% had good to excellent results, 22.2% had fair results, and 22.2% had poor results. In the group that had arthroscopic debridement alone, 57.2% had good to excellent results, 35.7% had fair results, and 7.1% had poor results. There was better relief of pain in the group with arthroscopic debridement alone.

Cloning and characterization of the Xenopus cyclin-dependent kinase inhibitor p27XIC1

We have isolated a gene encoding Xic-1, a 27-kDa cyclin-dependent kinase (Cdk) inhibitor from Xenopus ovary that shares significant homology with both mammalian CIP1 and Kip1/Kip2. The N- and C-terminal halves of Xic-1 are sufficient for interacting with Cdks and proliferating cell nuclear antigen, respectively. Recombinant Xic-1 inhibits Xenopus cyclin E/Cdk2, cyclin A/Cdk2 and cyclin B/Cdc2 activities, although with quite different IC50 values. Truncation of the N terminus of Xic-1 increases the IC50 value for cyclin A/Cdk2 50-fold with no effect on the inhibition of cyclin E/Cdk2 or cyclin B/Cdc2.Xic-1 inhibits both single-stranded and nuclear DNA synthesis in egg extracts, an effect reversed by proliferating cell nuclear antigen or cyclin E/Cdk2, respectively. These results suggest a function for Xic-1 in the control of DNA synthesis by cyclin E/Cdk2.

[Impaired calcium uptake by cardiac sarcoplasmic reticulum and its underlying mechanism during rat septic shock]

The underlying mechanism of Ca2+ uptake function of cardiac sarcoplasmic reticulum (SR) was investigated in the rat septic shock model produced by cecal ligation and puncture (CLP). The results are as follows. During the early phase of sepsis, the initial rate of ATP-dependent Ca2+ uptake by SR was decreased, while both the capacity of Ca2+ uptake and the activity of Ca(2+)-ATPase were unaffected. In the late sepsis, the impairment in SR function was even greater as the initial rate and the capacity of Ca2+ uptake by SR were significantly decreased, and this was paralleled by a reduction in Ca(2+)-ATPase activity. Although Ca2+ affinity (Km value) to calcium pump and the A0.5 values for Mg2+ and ATP activation on the Ca2+ uptake rate were unchanged, during sepsis the phosphorylation of SR vesicles by adding of catalytic subunit of the cAMP-dependent protein kinase (PKA), calmodulin, or the fragment of PKC into Ca2+ uptake buffer, failed to stimulate Ca2+ uptake activities of SR isolated from early or late septic rats. These data suggest that depression of cardiac SR function is aggravated as sepsis develops, the impairment of SR Ca2+ uptake is possibly based on a mechanism of defective phosphorylation of SR rather than the ionic and energic regulatory actions of Ca2+, Mg2+, ATP on cardiac SR.

In Vitro antimicrobial susceptibilities of Streptococcus pneumoniae isolated from two teaching hospitals in Taiwan, 1989-1995

The susceptibility of 46 pneumococcal isolates collected during October 1989 to May 1995 from National Taiwan University Hospital and Taipei Municipal Yang Ming Hospital was studied. Among these isolates, the resistant rate of penicillin G was 21.7%; the penicillin G-resistant strains were more frequently resistant than the penicillin-sensitive strains to other beta-lactam antimicrobial drugs. The minimum bactericidal concentrations (MBCs) of penicillin G for all isolates were equal to, or one dilution higher than, minimum inhibitory concentrations (MICs). Three strains were false positive for penicillin resistance among isolates of Streptococcus pneumoniae screened with oxacillin. On the other hand, resistance to penicillin G was often independent of resistance to erythromycin. Vancomycin was the most active agent tested.

Modulation of the ryanodine receptor sarcoplasmic reticular Ca2+ channel in skinned fibers of fast- and slow-twitch skeletal muscles from rabbits

This study was performed to compare skinned fibers from rabbit adductor magnus (AM) and soleus (SL) muscles with regard to the influence of caffeine, Ca2+ and Mg2+ on the depressive effects of ryanodine (RYA) on the caffeine-induced tension transients. Single skinned fibers were immersed in solutions to load Ca2+ into, and release Ca2+ from the SR (a load-release cycle). Three cycles were sequentially performed in each skinned fiber: (1) a control (no RYA), (2) a conditioning period in which activation was carried out in the presence of ryanodine plus various concentrations of the modulators, i.e. caffeine, Ca2+ or Mg2+, and (3) a test (no RYA) which monitored the release activity retained after the conditioning cycle. The depressive effect of RYA was found to be a function of [ryanodine], [caffeine], or [Ca2+], and an inverse function of [Mg2+], where [] denotes concentration. The half-maximal effects of RYA in AM (5 microM RYA) and SL (10 microM RYA), respectively, occurred at a pCa50 of 5.32 versus 5.43 without caffeine, or pCa50 of 7.24 versus 6.88 and pMg50 of 3.29 versus 3.61 with 25 mM caffeine, at a [caffeine] of 4.96 versus 7.29 mM, and at a [ryanodine] of 31.0 versus 101.6 microM. Thus, the RYA depression in skinned muscle fibers is modulated by caffeine, Ca2+, and Mg2+ in both muscle types, and AM is at least two- to fourfold more sensitive than SL.

Effects of halothane on calcium(2+)-activated tension of the contractile proteins and calcium(2+) uptake and release by the sarcoplasmic reticulum in skinned human myocardial fibers

Based on studies using skinned myocardial fibers from animals, it has been postulated that one of the major mechanisms by which halothane depresses myocardial contractility is by decreasing the Ca2+ content of the sarcoplasmic reticulum (SR). In this study we examined, in skinned human myocardial fibers, the effects of halothane on Ca(2+)-activated tension development of the contractile proteins and Ca2+ uptake and release by the SR. Left ventricular muscle samples obtained from patients undergoing aortocoronary bypass operations were mechanically skinned and immersed in test solutions equilibrated with N2 and halothane preceded and followed by immersion in control solution (no halothane). To study Ca(2+)-activated tension development of the contractile proteins, free Ca2+ concentrations in the bathing solutions were buffered by EGTA. To study Ca2+ uptake and release by the SR, Ca2+ was loaded into the SR and released with caffeine and the resulting tension transients were measured. Halothane (1%-3%) depressed maximum Ca(2+)-activated tensions (pCa = -log[Ca2+](M) = 3.8) by 5% for each 1% increase in concentration. Tensions generated by submaximum Ca2+ concentrations expressed as a percentage of maximum tension were not significantly decreased by halothane except at 3%. Halothane decreased Ca2+ uptake (IC50 = 1.7%), and increased (by approximately 50%) Ca2+ release by the SR. We conclude that decreased activation of the contractile proteins and Ca2+ uptake by the SR can both contribute to the myocardial depression produced by halothane. Of these, decreased Ca2+ uptake by the SR is probably a major mechanism for halothane depression of myocardium.

Phosphofructokinase binding to myofibrils in fish muscle: influences of ionic strength and metabolite levels on enzyme complex formation

The interaction of 6-phosphofructo-1-kinase (PFK) with myofibrils was assessed using the purified proteins from rainbow trout white skeletal muscle. More than 70% of PFK activity was bound at pH values between 6 and 7 but higher pHs dissociated the complex. Increasing salt concentrations also reduced PFK binding, with greater sensitivity to salt at pH 7.0 vs pH 6.6. Substrates and allosteric effectors also reduced enzyme binding to myofibrils; 50% of enzyme was released at 0.23, 0.24, 1.3, and 2.0 mM for fructose 6-phosphate, Mg.ATP, ATP and AMP, respectively. However, the addition of a protein crowding agent, poly(ethylene)glycol, greatly enhanced PFK binding to myofibrils, particularly at high pH (8.0) or high [KCl]. The studies suggest that reversible binding of PFK to myofibrils may be an important factor in the control of anaerobic glycolysis in vivo, especially under the cellular conditions of burst swimming exercise.

Cloning and expression of a Xenopus gene that prevents mitotic catastrophe in fission yeast

In fission yeast the Wee1 kinase and the functionally redundant Mik1 kinase provide a regulatory mechanism to ensure that mitosis is initiated only after the completion of DNA synthesis. Yeast in which both Wee1 and Mik1 kinases are defective exhibit a mitotic catastrophe phenotype, presumably due to premature entry into mitosis. Because of the functional conservation of cell cycle control elements, the expression of a vertebrate wee1 or mik1 homolog would be expected to rescue such lethal mutations in yeast. A Xenopus total ovary cDNA library was constructed in a fission yeast expression vector and used to transform a yeast temperature-dependent mitotic catastrophe mutant defective in both wee1 and mik1. Here we report the identification of a Xenopus cDNA clone that can rescue several different yeast mitotic catastrophe mutants defective in Wee1 kinase function. The expression of this clone in a wee1/mik1-deficient mutant causes an elongated cell phenotype under non-permissive growth conditions. The 2.0 kb cDNA clone contains an open reading frame of 1263 nucleotides, encoding a predicted 47 kDa protein. Bacterially expressed recombinant protein was used to raise a polyclonal antibody, which specifically recognizes a 47 kDa protein from Xenopus oocyte nuclei, suggesting the gene encodes a nuclear protein in Xenopus. The ability of this cDNA to complement mitotic catastrophe mutations is independent of Wee1 kinase activity.