Passively Q-switched Nd:YAG/Cr(4+):YAG bonded crystal microchip laser operating at 1112 nm and its application for second-harmonic generation

A passively Q-switched Nd:YAG/Cr⁴⁺:YAG microchip laser operating at 1112 nm is demonstrated. Under a pump power of 5.5 W, a maximum average output power of 623 mW was obtained with T=6% output coupler, corresponding to an optical-to-optical conversion efficiency of 11.3% and a slope efficiency of 19.5%. The minimum pulse width was 2.8 ns, the pulse energy and peak power were 39.3 μJ and 14 kW, respectively. Additionally, based on the 1112 nm laser, a 230 mW 556 nm green-yellow laser was achieved within an LBO crystal.

[The development of the hospital plate washer]

The Developments of the Hospital Plate Washer and its control system are introduced in the paper, and the application of the ultrasound technotology in the plate washer is described too.

[Effect of aldosterone on the secretion of endothelin by ventricular fibroblasts]

Using cell culture, radioimmunoassay for endothelin and RT-PCR, the effect of aldosterone on the endothelin secretion of ventricular fibroblasts was studied. The results showed that aldosterone (1 x 10(-7) mol/L) promoted the expression of ppET-1 mRNA, which began to increase in 2 hours and attained the highest level in 4 hours, thereafter decreased; aldosterone increased the endothelin level in ventricular fibroblasts and fibroblast conditioned growth medium (FCGM) as well, which was blocked by spironolactone (1 x 10(-6) mol/L), an aldosterone receptor antagonist. The results suggest that aldosterone can increase endothelin secretion by ventricular fibroblasts, which can be inhibited by its receptor antagonist spironolactone.

[Role of mitogen-activated protein kinase in the inhibition of myocardial hypertrophy by nitric oxide in renovascular hypertensive rats]

The aim of this study was to examine the effects of L-arginine, a nitric oxide (NO) precursor, on protein expression of endothelial nitric oxide (eNOS), nitrite/nitrate content, protein expression of mitogen-activated protein kinase phosphatase-1 (MKP-1) and the activity of mitogen-activated protein kinase (MAPK) in cardiac tissues in renovascular hypertensive rats (RHR). The Goldblatt renovascular hypertensive model was established by two-kidney one clip method. The rats were divided into four groups, respectively treated with 50, 150 and 450 mg/kg L-arginine and 150 mg/kg L-arginine plus 10 mg/kg L-NAME (an eNOS inhibitor) (i.p.). Another group did not receive specific treatment from the 5th week after renal artery constriction. Control group was sham-operated. Mean arterial blood pressure (MABP) and the ratio of left ventricular weight to body weight (LVW/BW) were measured 8 weeks after treatment. eNOS protein expression, nitrite/nitrate content, MKP-1 protein expression and MAPK activity in cardiac tissues were detected using Western blot analysis, enzyme-reduction method and substrate in-gel kinase assay, respectively. It was found that L-arginine significantly inhibited the increase of MABP and LVW/BW, attenuated the activity of MAPK, increased protein expression of eNOS and MKP-1 and potentiated production of NO in cardiac tissue with the most effective dosage of 150 mg/kg, and these effects of L-arginine could be inhibited by L-NAME. These results suggest that MKP-1 may play an important role in the NO-induced inhibition of myocardial hypertrophy. The anti-hypertrophic effects of L-arginine may involve increase of eNOS protein expression and NO production, potentiation of MKP-1 protein expression, and inhibition of MAPK activity in the cardiac tissue of RHR.

[Role of conditioned growth medium for ventricular fibroblasts in promoting fibroblast collagen synthesis and proliferation]

Ventricular fibroblasts were cultured using conditioned growth medium for ventricular fibroblasts (FCGM). The rate of the total collagen synthesis of ventricular fibroblasts was measured by assaying the incorporation rate of [3H]-proline, whereas the proliferation of ventricular fibroblasts was assessed by determining the incorporation rate of [3H]-TdR and the expression of c-fos genes. FCGM significantly increased the [3H]-proline incorporation rate and [3H]-TdR incorporation rate of fibroblasts in a dose-dependent manner. Furthermore, FCGM promoted the c-fos gene expression of fibroblasts, which attained its maximum in 1 h. BQ123, an ETA receptor antagonist, partially blocked the above effects of FCGM, but AT1 receptor antagonist CV11974 and alpha-adrenergic receptor antagonist regitin did not. It is suggested that the ventricular fibroblast has an autorine function in promotion of collagen synthesis and proliferation of fibroblasts by secreting endothelin and other bioactive substances.

[The effect of aldosterone of promotion on proliferation of ventricular fibroblasts]

AIM

To study the effect of promoting aldosterone on proliferation of ventricular fibroblasts.

METHODS

Assay of [3H]-TdR incorporation rate and RT-PCR were used.

RESULTS

Aldosterone could promote [3H]-TdR incorporation of ventricular fibroblasts, the effective dose of aldosterone was among (1 x 10(-9)-1 x 10(-6))mol/L, and had dose-dependent manner, the c-fos gene was expressed after stimulated by aldosterone for 15 min, and studied the highest in 1 h, then reduced later. Spironolactone, aldosterone receptor antagonist could block the effect of aldosterone.

CONCLUSION

Aldosterone promotes the proliferation of ventricular fibroblasts, mediated by aldosterone receptor.

[Effect of protein kinase C on inhibition of nitric oxide synthesis in cultured neonatal rat cardiomyocytes by angiotensin II]

The purpose of the present study was to investigate the effect of angiotensin II (Ang II) on nitric oxide (NO) concentration and its signal transduction pathway in cultured neonatal rat cardioymocytes. NO content was measured in cultured neonatal rat cardiomyoctes using a nitrite/nitrate colormetric method kit. NO content was represented by measured nitrite (NO(2)) and nitrate (NO(3)) level (NO(2)/NO(3)). The results are as follows. NO production was decreased by Ang II in a dose dependent manner but increased by L Arg. The Saralasin, an antagonist of Ang II receptor, inhibited the effect of Ang II on NO production. The effect of Ang II on NO production was inhibited by NOS blocker N(G)-nitro-L-arginine methyl ester L-NAME but not by L-Arg. Pretreatment of Phorbol 12-myristate 13-acetate PMA , a PKC activator, decreased NO concentration significantly. This effect was strengthened by L-NAME. Staurosporine, a PKC inhibitor, abolished the inhibiting effect of Ang II on production of NO. The above results suggest that Ang II could decrease NO content in cultured neonatal rat cardiomyocytes significantly. Activity of NOS may be inhibited by Ang II. Ang II receptor was involved in the inhibitory effect of Ang II on NO production. Activation of protein kinase C (PKC) decreased significantly NO production in cultured neonatal rat cardiomyoctes, which appears to be associated with PKC in the signal transduction pathway.

[Cardiocyte hypertrophy induced by cultured neonatal rat ventricular fibroblast conditioned growth medium]

The present work demonstrated that cultured neonatal rat ventricular fibroblast conditioned growth medium (FCGM) could significantly increase cell surface area and protein content and promote (3)H -Leucine incorporation on neonatal rat cardiomyocyte. The above effect was strongest on the third day, and was dose-dependent. BQ(123), an ET-A receptor antagonist, significantly blocked the effect, while CV11974, an Ang II I-type receptor antagonist, and regitin, an alpha-adrenergic receptor antagonist, did not. These results suggest that there are some substances promoting hypertrophy of cardiomyocytes in FCGM, which may be ET-1. The FCGM-induced increases in cardiomyocyte protein synthesis and cell surface area were inhibited partially by pertusis toxin (PTX) and PKC inhibitor staurosporine (ST), suggesting that the hypertrophic effect is related with PTX sensitive G protein and PKC.

[Pressor effect of substance P applied to the pressor area of ventral surface of medulla oblongata and the underlying mechanism in rabbits]

Experiments were performed on urethane anesthetized and artificially ventilated rabbits. The results were as follows. Application of substance P (SP) to the pressor area of ventral surface of medulla oblongata (VSMp) elicited a dose-dependent increase in blood pressure (BP), but no significant change in heart rate. The pressor response of SP was blocked by pretreatment with SP receptor antagonist (DSP) in VSMp. Application of DSP alone to VSMp elicited a significant decrease in BP. The pressor response of SP was attenuated when VSMp was pretreated with phentolamine or prazosine, whereas pretreatment with yohimbin or propranolol was without effect. Application of SP to VSMp elicited an increase in renal sympathetic nerve discharge (RSND) in association with pressor response; both these responses were blocked by pretreatment with DSP in VSMp. Application of DSP alone to VSMp elicited a significant decrease in RSND and BP. The above results indicate that SP has a pressor effect in VSMp due to activation of SP receptor mediated by alpha 1-receptor. The pressor effect of SP may be mainly due to an increase of peripheral vascular resistance induced by the augmented sympathetic nerve activity. In summary, it appears that endogenous SP in VSMp plays an important role in maintaining sympathetic tone and BP level.

Abuse of antibiotics in China and its potential interference in determining the etiology of pediatric bacterial diseases

There is scant information about the etiology and epidemiology of bacterial diseases of infants and children in China because of very little success with bacterial culture. This study describes the severity of abuse of antibiotics among Chinese pediatricians and this abuse's potential interference in determining the etiology of bacterial diseases. According to a survey in Beijing Children's Hospital more than 98% of the patients in the Outpatient Department who were diagnosed with common cold were given antibiotics by physicians. More than one-third of the patients had been taking antibiotics before coming to the hospital. Using a sensitive Staphylococcus aureus assay we found that 70% of blood samples and 43% of cerebrospinal fluid samples from the patients with bacterial meningitis and pneumonia contained antibacterial activity. Bacteria were recovered significantly less often from the samples with antibacterial activity than from those who did not from which antibiotic was not recovered, both in blood (5.3% vs. 12.5%) and in cerebrospinal fluid (2.5% vs. 14.8%). This study indicates that antibiotic abuse is a severe problem in China and that judicious use of antibiotics is urgently needed.

Effectiveness of amodiaquine, sulfadoxine-pyrimethamine, and combinations of these drugs for treating chloroquine-resistant falciparum malaria in Hainan Island, China

The study was carried out in 1985-86 in Hainan Island where Plasmodium falciparum is resistant to chloroquine. Fifty cases of falciparum malaria were treated with 1800 mg amodiaquine for 3 days: the cure rate was 65.3%, and the mean time to clear fever and asexual parasitaemia was 30.7 and 60.3 hours, respectively; 34.7% of cases showed RI or RII recrudescence, and one patient's temperature did not come down to normal within 7 days.Twenty-one cases were treated with sulfadoxine-pyrimethamine (1500 mg and 75 mg, respectively): 19 were cured, I showed RI and another had an S or RI response; the mean time for fever control was 56.1 hours.Fifty cases were treated with amodiaquine plus sulfadoxine and 49 received amodiaquine plus sulfadoxine-pyrimethamine: the cure rate was 97.9% and 100%, respectively; the mean time for fever clearance was 25.0 and 25.7 hours and for parasite clearance 57.1 and 52.8 hours, respectively. These drug combinations gave much better results for cure and for symptom control than amodiaquine or sulfadoxine-pyrimethamine alone, and may be considered for treatment of chloroquine-resistant falciparum malaria.