Nitrogen utilization and transformation in red soil fertilized with urea and ryegrass

The influence of fertilization with urea and ryegrass on nitrogen utilization and transformation in red soil has been studied by using ^15N tracer method.When urea and ryegrass were applied alone or in combination,the percentage of N uptaken by ryegrass from labelled urea was 3 and 1.7 times that from labelled ryegrass for the application rate of 200mgN.kg^-1 and 100mgN.kg^-1,respectively;combining application of ryegrass and ureareduced uptake of urea N and increased uptake of ryegrass N by ryegrass plant,but the percentage of N residued in soil increased for urea and decreased for ryegrass.when urea and ryegrass were applied alone,the percentage of N residued in soil from labelled ryegrass was more than 69% while that from labelled urea was less than 25%,and much more ryegrass N was incorporated into humus than urea N.     

Lysophosphatidylcholine is involved in the antigenicity of oxidized LDL

Lysophosphatidylcholine (LPC) is formed by hydrolysis of PC in low density lipoprotein (LDL) and cell membranes by phospholipase A2 or by oxidation. Oxidized (ox) LDL activates endothelial cells, an effect mimicked by LPC. oxLDL also has the capacity to activate T and B cells, and antibody titers to oxLDL are related to the degree of atherosclerosis. The antigen in oxLDL responsible for its immune-stimulatory capacity is not well characterized, and we hypothesized that LPC was involved. We demonstrate herein the presence of antibodies against LPC, both of the IgG and IgM isotype, in 210 healthy individuals. This antibody reactivity was not specifically related to oxidation of the fatty acid moiety in LPC, since LPC containing only palmitic acid showed antibody titers equivalent to those of LPC containing unsaturated fatty acids. Antibody titers to PC were low compared with LPC, and hydrolysis of PC at the sn-2 position is thus essential for immune reactivity. There was a close correlation between anti-oxLDL and anti-LPC antibodies. Furthermore, LPC competitively inhibited anti-oxLDL reactivity, which indicates that LPC may explain a significant part of the immune-stimulatory properties of oxLDL. LPC, being a lipid, is not likely to be an antigen itself. Instead, LPC could form immunogenic complexes with peptides, which may induce and potentiate immune reactions in the vessel wall. This study adds to the evidence that LPC is an important component of oxLDL and emphasizes the potential role of phospholipase A2 in atherosclerosis.     

Autonomic nervous activity at episodes of myocardial ischemia in patients with coronary artery disease by heart rate power spectral analysis

Heart rate power spectral analysis in 44 patients with coronary artery disease was obtained from 24-hour dynamic electrocardiogram. 195 episodes of transient myocardial ischemia that was defined as horizontal or down sloping depression of the ST segment of > or = 0.1 mV and lasted for > or = 2 minutes were studied. The area of low frequency components (LF, 0.02-0.10 Hz) representing predominontly sympathetic tone with some contribution from the parasympathetic tone and that of high frequency components (HF, 0.15-0.40 Hz) representing mainly parasympathetic tone and the value of LF/HF on 4 minute heart rate power spectral graph at the deepest depression of ST segment were compared with that before the episode of myocardial ischemia. The area of HF of fast rate myocardial ischemia occurring in night reduces significantly (P < 0.001), the value of LF/HF increases markedly (P < 0.05) and the area of LF increases slightly. The results suggest that there is a change of autonomic nervous activity during the episode of fast rate myocardial ischemia in night, parasympathetic nervous tone decreases markedly, there may be secondary increase of sympathetic nervous activity.     

高温超导红外探测器的电极工艺探讨

介绍了高温超导红外探测器电极材料的选择和制备。选用先蒸、后蒸金，再合金化的电极工艺。芯片装配成器件后，器件性能稳定，膜层牢固，接触电阻小。     

半导体激光泵浦掺钕铍酸镧固体激光器

报道了用国产二极管激光端面泵浦自行研制的掺铵铍酸镧（Ｎｄ：ＢＥＬ）晶体得到１．０７μｍ线偏振激光输出的研究结果。分别用非球面透镜成像、加棱镜对扩束、加光纤传输三种方式将泵浦光耦合到增益介质中，由此得到不同的斜效率，并对此作了分析。     

Diagnosis and treatment of iatrogenic ureteral injury

Diagnosis and treatment of 17 patients who sustained 20 iatrogenic ureteral injuries were analyzed. Primary operations in which ureteral injury occurred are almost gynecologic procedures and general surgery. Injuries were managed by ureteroureterostomy in four, ureteral stent in one, removal suture ligation and ureteral double J-catheter in one, ureteroneocystostomy in ten, psoas-hitch technique and ureteroneocystostomy in one, nephrectomy in two. All patients with appropriate repair were followed-up periods of three to five years. Renal function of these patients had optimal results. When ureteral injury occurs, B-US, IVU, cystoscopy, retrograde ureterography or infusion of dye may be useful. An appropriate repair should be chosen according to length and position of ureteral injuries. Reoperation was optimal in two to three weeks. Immediate recognition of accidental ureteral injury provides optimal results. Patients with unrecognized injuries had suboptimal results.     

A comparative study on coronary angiography and exercise ECG testing

42 patients with chronic urinary retention caused by BPH were treated by means of Mesh-like tubular stent placing from August 1993 to August 1994. The mesh-like tubular stent was made of nickel titanium alloy in sizes of 2.0 x 1.5 cm, 2.5 x 1.5 cm, 3.0 x 1.5 cm respectively. Under direct vision the stent was placed with the deployment tool. The desirable position of the stent is 0.3-0.5 cm proximal to the internal urethral orifice, 0.5 cm distal to the verumontanum. In 38 patients followed up for 1-6 months, 34 were succesful with an effective rate of 80%. IPSS, PUFR, RUV after 1, 3, 6 months of placement were 8.5 +/- 4.4, 6.8 +/- 3.5, 7.1 +/- 5.2; 12.5 +/- 6.0 ml/s, 14.0 +/- 5.2 ml/s, 14.4 +/- 8.1 ml/s; 43 +/- 11.5 ml, 47.4 +/- 13.3 ml, 44.5 +/- 15.7 ml respectively. Four stents were taken away transurethrally in the unsuccessful cases. The results indicat that there are no serious complications except for shorttime hematuria, fever, and bladder irritation. The success depends chiefly upon exactly meassuring the length of prostatic urethra, selecting the rational size of the stent, and correctly placing the stent.     

N-Methyl-D-aspartate attenuates opioid receptor-mediated G protein activation and this process involves protein kinase C

The effects of N-methyl-D-aspartate (NMDA) on opioid receptor-mediated G protein activation were explored in neuroblastoma X glioma hybrid (NG108-15) cells. Treatment of the cells with NMDA resulted in a remarkable attenuation of [35S]guanosine-5'-O-(3-thio)triphosphate binding stimulated by [D-Pen2,D-Pen5]-enkephalin (DPDPE), a delta-opioid receptor agonist. The effects of NMDA were dose and time dependent with an IC50 value of 5 nM and could be blocked by NMDA receptor antagonists. After NMDA treatment, the DPDPE dose-response curve shifted to the right (EC50 value increased approximately 7-fold, from 6 to 40 nM), and the maximal response induced by DPDPE was reduced by approximately 60%. The effects of NMDA were reversible, and the DPDPE response could recover within 60 min. The functional responses of delta-, mu-, and kappa-opioid receptors in primarily cultured neurons also were attenuated significantly by NMDA treatment. The inhibitory effects of NMDA on opioid receptor-mediated G protein activation could be blocked by coadministration of the protein kinase C (PKC) inhibitors or by elimination of the extracellular Ca2+. Correspondingly, NMDA treatment of NG108 cells significantly elevated cellular PKC activity and stimulated Gialpha2 phosphorylation. Transient transfection into NG108-15 cells of the wild-type Gialpha2 and a mutated Gialpha2 (Ser144Ala) resulted in a 2-fold increase in DPDPE-stimulated G protein activation. The DPDPE responses were greatly inhibited by NMDA treatment in the wild-type Gialpha2-transfected cells but much less affected in the mutant Gialpha2-transfected cells. In summary, NMDA attenuates opioid receptor/G protein coupling, and this process requires activation of PKC.