[Study on the effect of ligustrazine on adherent molecule expression of bone marrow cells in immune-mediated aplastic anemia mice]

OBJECTIVE

To explore the effect of ligustrazine on the expression of adherent molecule of bone marrow cells in immune-mediated aplastic anemia(AA) mice.

METHODS

Each immune-mediated AA mouse was intraperitoneally injected with 5 mg ligustrazine twice a day. On the 14th day, expressions of CD49d and CD49c in bone marrow mononuclear cells(MNC) were detected by flow cytometry, and VCAM-1 on stromal cells by immunohistochemistry SABC.

RESULTS

Expressions of CD49d, CD49e and VCAM-1 were significantly lower in AA group than in normal group(t = 11.96, 17.18 and 7.09 respectively, P < 0.001), and were much higher in ligustrazine treated group than in non-treated group(t = 9.05, 14.61 and 6.91 respctively, P < 0.001). Expressions of CD49d and VCAM-1 were in the normal range in ligustrazine group.

CONCLUSIONS

Ligustrazine can increase the expression of adherent molecule of bone marrow cells in immune-mediated AA mice, thus promote the growth of hematopoietic cells.

Neural precursor cells differentiating in the absence of Rb exhibit delayed terminal mitosis and deregulated E2F 1 and 3 activity

The severe neurological deficit in embryos carrying null mutations for the retinoblastoma (Rb) gene suggests that Rb plays a crucial role in neurogenesis. While developing neurons undergo apoptosis in vivo neural precursor cells cultured from Rb-deficient embryos appear to differentiate and survive. To determine whether Rb is an essential regulator of the intrinsic pathway modulating terminal mitosis we examined the terminal differentiation of primary cortical progenitor cells and bFGF-dependent neural stem cells derived from Rb-deficient mice. Although Rb -/- neural precursor cells are able to differentiate in vitro we show that these cells exhibit a significant delay in terminal mitosis relative to wild-type cells. Furthermore, Rb -/- cells surviving in vitro exhibit an upregulation of p107 that is found in complexes with E2F3. This suggests that p107 may partially compensate for the loss of Rb in neural precursor cells. Functional ablation of Rb family proteins by adenovirus-mediated delivery of an E1A N-terminal mutant results in apoptosis in Rb-deficient cells, consistent with the interpretation that other Rb family proteins may facilitate differentiation and survival. While p107 is upregulated and interacts with the putative Rb target E2F3 in neural precursor cells, our results indicate that it clearly cannot restore normal E2F regulation. Rb-deficient cells exhibit a significant enhancement of E2F 1 and 3 activity throughout differentiation concomitant with the aberrant expression of E2F-inducible genes. In these studies we show that Rb is essential for the regulation of E2F 1 and 3 activity as well as the onset of terminal mitosis in neural precursor cells.

[Evaluation of atrial natriuretic peptide in differentiating benign and malignant pleural effusion]

OBJECTIVE

To discuss the value of atrial natriuretic peptide (ANP) in differentiating benign and malignant pleural effusion.

METHODS

Direct radioimmunoassay was used to detect ANP of pleural effusion and serum in 30 tuberculous and 26 cancerous pleural effusion patients.

RESULTS

The ANP in tuberculous and cancerous pleural effusion were (75 +/- 9) ng/L, (157 +/- 45) ng/L respectively, and significant difference was found (P < 0.001). The ANP of tuberculous pleural effusion was apparently lower [(75 +/- 9) ng/L] than serum [(170 +/- 37) ng/L], and significant difference was also found (P < 0.001). The ratio of ANP of pleural effusion to that of serum were 0.47 +/- 0.17, 0.99 +/- 0.46 respectively in tuberculous and cancerous pleural effusion patients. The sensitivity of ANP was 81% and specificity 100% in diagnosing malignant pleural effusion.

CONCLUSIONS

Detecting ANP of pleural effusion is one of important methods for differentiating benign and malignant pleural effusion.

Prevention of neuronal cell death by neural adhesion molecules L1 and CHL1

The effects of L1-Fc and CHL1-Fc fusion proteins on neuronal survival were investigated. Cerebellar granule neurons of mouse and hippocampal neurons of rat embryo undergo apoptosis when cultured in serum-free medium. Treatment with chimeric proteins containing the extracellular domains of the neural adhesion molecules L1 or CHL1 fused to the Fc region of human immunoglobulin significantly enhanced the survival of neurons. Compared to the control, the percentage of surviving neurons increased about 60% and 45% with L1 and CHL1 fusion proteins, respectively. A fusion protein containing the extracellular domain of NCAM had no effect on survival. The L1 and CHL1 fusion proteins were effective both in soluble form or when offered as a substrate, with the maximal effect at about 1 microg/mL. To explore the intracellular events related to the neuronal survival effects of L1-Fc fusion protein, Bcl-2 and c-Jun expression were analyzed by Western blotting. The level of Bcl-2 in cerebellar granule neurons was increased by treatment with L1-Fc at both 1 and 5 days of culture. The level of c-Jun was not significantly affected at the early time point and was reduced by L1-Fc fusion protein after long-term culture. The results demonstrate that the neural adhesion molecule L1 and its relative CHL1 are potential neuronal survival factors for neurons of the central nervous system. Bcl-2 may serve as one of the intracellular mediators of the neuronal survival effects of L1.

[Effect of composite blood-activating decoction on expression of adherent molecule and cyclin in bone marrow hematopoietic cells in mice of immune-induced aplastic anemia]

OBJECTIVE

To study the effect of composite blood-activating decoction (CBAD) on expression of adherent molecule CD49 d and cyclin D2 in bone marrow hematopoietic cells in experimental immune-mediated aplastic anemia (AA) mice.

METHODS

After the model of AA was established, the animals were fed with 0.2 ml of 100% CBAD, twice a day for 12 days. Te CD49 d and cyclin D2 expression level of bone marrow hematopoietic cells in model mice were measured by flow cytometor analysis system at the 13th day of experiment.

RESULTS

CD49 d expression level in CBAD group was significantly higher than that in the AA group (P < 0.05), and was similar to that in the normal group (P > 0.05). The expression of cyclin D2 in CBAD group was significantly higher than that in the AA group (P < 0.01), but the cell count of G0 + G1 phase was significantly lower in the CBAD group, as compared with the AA group, P < 0.01.

CONCLUSION

CBAD can increase the expression of adherent molecule CD49 d and cyclin D2 in bone marrow hematopoietic cells, and promote the growth of hematopoietic cells.

Effect of ligustrazine on expression of adherent molecule CD49d and cyclin D2 in hematopoietic cells in acute radiation injured mice

After irradiation by 8.0 Gy gamma-ray, each mouse was stomach-fed by 4 mg ligustrazine injection twice a day. On the 7th day after irradiation, CD49d expression in ligustrazine-treated group was significantly higher than that in control group (P < 0.01), and showed no difference from that in normal group (P > 0.05). On the 14th day after irradiation. CD49d expression was increased in control group, but decreased significantly in ligustrazine-treated group (P < 0.01). The expression of Cyclin D2 in spleen mononuclear cells (MNC) in ligustrazine-treated group was significantly higher than that in control group, but the ratio of G0 + G1 phase cells was significantly lower in ligustrazine-treated group (P < 0.01). This finding indicated that ligustrazine could increase the expression of adherent molecule on bone marrow hematopoietic cells and Cyclin D2 in spleen MNC, thereby promoting the growth of hematopoietic cells.

[The observations of plasma of AC operation in the CT-6B Tokamak by Ha emissions]

The spatial distribution and temporal evolution of plasma of AC operation in the CT-6B Tokamak has been observed through Ha emissions by an optical multichannel diagnostic system for the first time. The results show the plasma density is not completely lost during current reversal, therefore, there were no need for second breakdown after the current reversal. The spatial and temporal evolution of plasma is dependent on the current wave forms.

Glutamate potentiates the toxicity of mutant Cu/Zn-superoxide dismutase in motor neurons by postsynaptic calcium-dependent mechanisms

Mutations in the Cu/Zn-superoxide dismutase (SOD-1) gene are responsible for a subset of familial cases of amyotrophic lateral sclerosis. Using a primary culture model, we have demonstrated that normally nontoxic glutamatergic input, particularly via calcium-permeable AMPA/kainate receptors, is a major factor in the vulnerability of motor neurons to the toxicity of SOD-1 mutants. Wild-type and mutant (G41R, G93A, or N139K) human SOD-1 were expressed in motor neurons of dissociated cultures of murine spinal cord by intranuclear microinjection of plasmid expression vector. Both a general antagonist of AMPA/kainate receptors (CNQX) and a specific antagonist of calcium-permeable AMPA receptors (joro spider toxin) reduced formation of SOD-1 proteinaceous aggregates and prevented death of motor neurons expressing SOD-1 mutants. Partial protection was obtained by treatment with nifedipine, implicating Ca2+ entry through voltage-gated calcium channels as well as glutamate receptors in potentiating the toxicity of mutant SOD-1 in motor neurons. Dramatic neuroprotection was obtained by coexpressing the calcium-binding protein calbindin-D28k but not by increasing intracellular glutathione levels or treatment with the free radical spin trap agent, N-tert-butyl-alpha-phenylnitrone. Thus, generalized oxidative stress could have contributed in only a minor way to death of motor neurons expressing the mutant SOD-1. These studies demonstrated that the toxicity of these mutants is calcium-dependent and provide direct evidence that calcium entry during neurotransmission, coupled with deficiency of cytosolic calcium-binding proteins, is a major factor in the preferential vulnerability of motor neurons to disease.

All-fiber optical add-drop multiplexer based on a selective fused coupler and a single fiber bragg grating

We demonstrate a novel fiber add-drop multiplexer based on a selective fused coupler consisting of a twin-core fiber and a standard telecommunication fiber and a single fiber Bragg grating. Loss as low as ~1.1 dB for the added and dropped channel is demonstrated with a potential to be as low as ~0.4 dB. Better than 30-dB isolation is also achieved between the dropped and added channels. The device is based on well-developed fused coupler and Bragg grating technology. Most importantly, the method is noninterferometric, which means it does not need critical alignment or trimming. The fused coupler and grating are completely decoupled and can be made separately.

Study on oxygen supply and protection of bone marrow in acute radiation injured mice

After irradiated by 8 Gy 60Co gamma-ray, mice were intraperitoneally injected immediately with 0.2 ml 100% compound blood-activating soup twice a day for 10 days. The in situ ulnar bone marrow partial pressure of oxygen (PbO2) was determined in vivo before, during and after irradiation respectively. The bone marrow sections in the same part were observed. Our results showed that the normal murine ulnar PbO2 was 12.72 +/- 1.05 kPa. During irradiation, the level of PbO2 decreased to 10.78 +/- 1.17 kPa (P < 0.001). And 3 days after irradiation, PbO2 decreased to 9.75 +/- 0.52 kPa, suggesting that the commonly used "blood-activating and stasis-eliminating" Chinese drugs could promote the rehabilitation and proliferation of bone marrow microvessels in the acute radiation injured mice, expand their areas, increase the oxygen supply of bone marrow microenvironment, thereby leading to PbO2 much higher increase than that of control group. It is also helpful in the proliferation and rehabilitation of hematopoietic cells.

Fabrication of high-rejection low-loss single-passband filters in cladding depressed fiber by the chirped-grating concatenation method

High-rejection-low-loss single-passband filters have been successfully fabricated by the chirped-grating concatenation method in a cladding depressed fiber. The enhanced photosensitivity, the enlarged bandgap between the Bragg resonance and the cladding modes, and the effective suppression of the cladding-mode outcoupling of the cladding depressed fiber permitted what is to our knowledge the first achievement of an ~1-dB loss in the passband and 50-dB rejection for a 50-nm-wide stop band covering the entire amplified spontaneous emission spectral range of an Er-doped fiber amplifier.

Detection of Mycoplasma salivarium and Mycoplasma fermentans in synovial fluids of temporomandibular joints of patients with disorders in the joints

Thirty-six synovial fluid samples of temporomandibular joints were obtained from 33 patients with pain and anterior disk displacement (closed lock) in the joints. DNAs were prepared from the samples and amplified by a PCR-based assay specific for Mycoplasma salivarium or Mycoplasma fermentans. Of the 36 samples, five (14%), three (8%), and 19 (53%) were positive for M. salivarium, M. fermentans and both, respectively.

High-energy single-transverse-mode Q-switched fiber laser based on a multimode large-mode-area erbium-doped fiber

We demonstrate that appropriately designed doped multimode fibers provide robust single-mode output when used within a fiber laser cavity. Using a novel large-mode-area fiber, we demonstrate what we believe to be record single-mode (M(2) <1.2) pulse energies of >0.5 mJ from a Q -switched fiber laser and even higher pulse energies (as high as 0.85 mJ) with slightly compromised spatial-mode quality (M(2)<2.0) . This approach offers significant scope for extending the range of single-mode output powers and energies that are achievable from fiber-laser-amplifier systems.

Accurate tuning of mismatched twin-core fiber filters

We have demonstrated a reproducible and accurate way of tuning the coupling wavelength of a mismatched twin-core filter. This method allows high quality all-fiber filters to be implemented with low loss at any desired wavelength over a range of few hundred nanometers from the same fiber. An ~500-nm tuning range is demonstrated, limited only by the measurement setup and not by the technique itself. Highly accurate control of the filtering wavelength in combination with control of filtering strength by adjustment of the length of the twin-core fibers allows complex filter profiles to be implemented by cascading of several different filters. These filters are also very stable to a change in temperature (~0.26 nm/100 degrees C at 1.55 microm) and strain (less than 0.3 nm/mstrain at 1.55 microm), permitting easy packaging.

Coupling characteristics of cladding modes in tilted optical fiber bragg gratings

We have studied both theoretically and experimentally the effect of grating tilting on the coupling between the fundamental core mode and the cladding modes in an optical fiber Bragg grating. The coupling is shown to be very sensitive on the tilting angle. It is also shown that tilting angle has to be minimized in fibers with designs to suppress the coupling between the fundamental core mode and the cladding modes. We have also studied the single, strong loss peak accompanying the Bragg reflection peak in depressed-cladding fibers, thus showing a good agreement between behavior that is measured and that is predicted theoretically.

[Aberrant expression of immunoglobulin germline gene C mu in leukemias]

OBJECTIVE

To investigate the significance of immunoglobulin germline gene C mu expression in leukemias.

METHODS

Immunoglobulin germline gene C mu transcripts in 63 bone marrow samples from 59 leukemia patients were examined by RT-PCR.

RESULTS

Germline C mu transcripts could be identified in 17 of 26 AML, 9 of 12 ALL, 4 CML-BC and 2 CLL patients. HLA-DR was expressed in 80% C mu(+) patients and in 92.9% C mu(+) AML patients. In 10 normal bone marrow or peripheral blood samples C mu transcripts were undetectable.

CONCLUSION

Leukemogenesis in most acute leukemia may originate from the common progenitors of early B-lymphoid and myeloid cells.

A novel response to dioxin. Induction of ecto-ATPase gene expression

We used differential display to discover a new gene that the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) regulates in mouse hepatoma cells. Its predicted amino acid sequence suggests that the gene encodes an ecto-ATPase that contains multiple glycosylation sites, conserved cysteine residues, and apyrase conserved regions. cDNA expression experiments in mouse hepatoma cells confirm that the new gene encodes an ecto-ATPase. Wild-type mouse hepatoma cells contain both constitutive and TCDD-inducible ecto-ATPase activity. Induction of ecto-ATPase gene expression by TCDD is direct and occurs at the transcriptional level. Studies in mutant hepatoma cells indicate that induction requires both the aromatic hydrocarbon receptor (AhR) and the AhR nuclear translocator (Arnt). Furthermore, induction requires AhR's transactivation domain, but not that of Arnt. Our findings reveal new aspects of dioxin's biological effects and TCDD-dependent gene regulation.

A pencil-beam photon dose algorithm for stereotactic radiosurgery using a miniature multileaf collimator

A computer-controlled miniature multileaf collimator (MMLC) with 4 mm leaf width and a maximum field size of 6 cm X 6 cm has been designed as a tertiary beam-shaping device for linac-based stereotactic radiosurgery. The purpose of this study is to develop an accurate and efficient dose calculation model for use with the MMLC. A pencil-beam based algorithm using a sum of three Gaussian kernels was developed to model the off-axis ratio of MMLC fields. Because the kernel integration over a rectangular field can be solved in closed form, dose to any point from an arbitrary MMLC field can be calculated efficiently by summing dose contribution from a set of rectangular apertures and transmission blocks that model individual leaf openings or leaf transmissions. The model uses an effective rectangular field and equivalent square method for determination of depth dose and dose output. Results showed that the calculated percentage depth dose was within 1% and output factor was within 1.5% of measured data. The parameters of the pencil beam kernels were extracted by fitting measured off-axis profiles for a few field sizes at a few depths. The accuracy of the calculated off-axis ratio was tested by comparison with measured data for a number of MMLC fields. The algorithm was shown to be accurate to within 1.5% or 1 mm for off-axis ratios. The algorithm computes at a speed of 34,600 data points per second on a DEC Alpha server model 2000/433 (Digital Equipment Corp., Maynard, MA), which is about 15 times faster than a Clarkson-type summation method.

[Relationship between risk-taking behavior and knowledge for HIV infection among young men in Longchuan, Yunnan of China]

OBJECTIVE

To study the relationship between characteristics of risk-taking behavior and knowledge level of HIV infection/AIDS and risk perception of HIV infection among young men in an AIDS epidemic area.

METHODS

A cross-sectional survey was carried out among young men aged 18-29 years in 82 villages in Longchuan, Yunnan, China in 1994. Their demographic and behavioral information and knowledge level of AIDS were collected by interviewer administered anonymous questionnaire.

RESULTS

A total of 1,548 subjects were interviewed and 433 were drug abusers, including 192 intravenous users with 73% of them sharing syringes with others. Drug abusers were four times more likely to have pre-/extra-marital sex than non-users. More than half of the interviewees scored zero in HIV/AIDS knowledge.

CONCLUSION

Factors predisposing spread of HIV infection were common in the local young men. It is recommended that intervention be implemented as soon as possible to prevent HIV infection and AIDS.

[Treatment of arteriovenous malformation by linear accelerator radiosurgery]

OBJECTIVE

To summarize the effectiveness of radiosurgery for cerebral arteriovenous malformations (AVMs).

METHOD

We treated with linear accelerator radiosurgery 17 patients harboring AVMs in the brain. 15 AVMs were located supratentorially and others infratentorially. All the patients were treated with single fraction. The doses at AVM margin were 15 to 30 Gy.

RESULT

AVMs disappeared in 13 of the 17 patients, reduced in 3 and unchanged in only 1 at 2 year follow up. Vasogenic edema observed in 2 patients, their neurologic deficits were all improved with steroid.

CONCLUSION

Linear accelerator radiosurgery is effective in dealing with cerebral AVMs. It provides with a new means of treatment for AVMs which can't be effectively treated with microsurgery and embolization.

Transformation-sensitive changes in expression, localization, and phosphorylation of adducins in renal proximal tubule epithelial cells

Adducins are cytoskeletal proteins that facilitate interactions between spectrin and actin to form the subcortical membrane skeleton. We recently determined that alpha- and gamma-adducins are among a group of PKC substrates that we have designated "STICKS" (substrates that interact with C-kinase). To study the role of adducins and their regulation by protein kinase C (PKC) in carcinogenesis, we compared the content, localization, and phosphorylation of alpha- and gamma-adducins in primary renal proximal tubule epithelial (RPTE) cells and oncogene-altered derivative lines. RPTE cells expressing adenovirus E1A are immortalized but not transformed, whereas RPTE cells expressing SV40 large T antigen are transformed. Phosphorylation of adducins was monitored with a phosphorylation state-specific antibody directed toward the PKC phosphorylation site on adducins. Basal levels of phospho-alpha-adducin were relatively low in growing and confluent primary RPTE cells; however, basal levels of phosphoadducins relative to total adducins were increased in E1A-RPTE and SV40-RPTE cells. Phorbol esters stimulated alpha-adducin phosphorylation to a greater extent in primary cells than in oncogene-altered cells, possibly because of the already high basal levels of phosphorylation in those cells. Phosphorylated adducins were preferentially recovered in the soluble fraction, indicating that PKC phosphorylation either directly or indirectly influences the subcellular location and functions of adducins in regulating membrane skeleton structure. Thus, these studies provide evidence for increased endogenous PKC activity in oncogene-altered cells and suggest that the increased activity directly influences cytoskeletal organization by phosphorylating regulatory proteins, such as the adducins.

[Effect of ligustrazine on CD34 antigen expression of bone marrow cells in immune-mediated aplastic anemia mice]

OBJECTIVE

To explore the effect of ligustrazine on CD34 antigen expression of bone marrow cells in immune-mediated aplastic anemia (AA) mice.

METHODS

The model of immune aplastic anemia mice was induced by means of 6.0 Gy60Co gamma-ray irradiation and lymphocyte infusion through tail vein. The mice were divided into 3 groups: the normal group, the AA control group and the ligustrazine group. Mice of the ligustrazine group were fed by 4 mg of ligustrazine injection twice a day by gastrogavage. On the 10th day, CD34 antigen expression intensity of bone marrow cell membrane was measured by flow cytometer analysis system.

RESULTS

CD34 antigen expression intensity of ligustrazine group was 77.6 +/- 6.5, with no statistic difference from that in the normal group (80.0 +/- 2.6), while that of the control group was much higher (68.6 +/- 4.5, P < 0.05).

CONCLUSIONS

Ligustrazine could promote proliferation of stem and progenitor cell of AA mice through influencing on bone marrow micro-environment so as to increase the CD34 antigen expression of bone marrow cells.

Ultrastructural observation on spermatocytogenesis in Taeniid cestodes

AIM

To study the spermatocytogenesis of taeniid cestodes at the ultrastructural leaves.

METHODS

Transmission electron microscopy.

RESULTS

The ultrastructural observation on spermatocytogenesis in Taenia solium, T. saginata and T. pisiformis were made by TEM. Two types of spermatogonia; type A and B, as well as the supporting cells surrounding the peripheral of spermatogonia are recognized. The type A spermatogonia are stem cells and the type B are mother cells which produce 16 primary spermatocytes by mitosis for 4 times with the cells unseparated. The primary spermatocytes are characterized by the ribosome masses in the cytoplasm. 32 secondary spermatocytes arranged in roselike were produced by reductive division of primary spermatocytes. The secondary spermatocytes become the spermatid quickly by short time development.

CONCLUSION

The dividing mode of spermatogonia in Taeniid cestodes is mitosis with cells unseparated.

[Effect of HE-NE laser acupuncture on the spleen in rats]

The splenic sinuses, lymphocytes and antigen presenting cells in the spleen of rat stimulated by He-Ne laser acupuncture were observed by using TEM to investigate the ultrastructural changes of them. The width of endothelial interstice was increased, hence a lot of blood cells oozed out of the splenic sinuses. There were numerous activated T cells which contained abundant mitochondria and ribosome in the periarterial lymphatic sheaths. The B cells were gradually differentiated into large lymphocytes, immature and mature plasmatic cells with a lot of endoplasmic reticula. They were prominently increased in the splenic nodules. The macrophages had short processes with numerous folds and microvilli and tended to neighboring lymphocytes. The nucleus pores were increased. There were a lot of vacuoles, phagosome and mitochondria were closed to macrophages and lymphocytes. In conclusion the activities of the cellular immunity and humoral immunity were enhanced by laser.

Down-regulation of major histocompatibility complex Q1b gene expression by 2,3,7,8-tetrachlorodibenzo-p-dioxin

We analyzed mouse hepatoma cells using differential display to discover new genes that respond to the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We identified a class I major histocompatibility complex (MHC) gene, which we designated as MHC Q1b, whose expression decreases in the presence of TCDD. TCDD-induced down-regulation of MHC Q1b requires both the aromatic hydrocarbon receptor and the aromatic hydrocarbon receptor nuclear translocator, transcription factors that up-regulate other genes in response to TCDD. Down-regulation of MHC Q1b by TCDD appears to involve both transcriptional and post-transcriptional regulatory events; the post-transcriptional destabilization of MHC Q1b mRNA is probably a secondary response to TCDD. Our findings reveal new mechanistic aspects of gene regulation by TCDD. In addition, our observations suggest a mechanism that might account for some of TCDD's immunotoxic effects.

Thermal decay of fiber Bragg gratings of positive and negative index changes formed at 193 nm in a boron-codoped germanosilicate fiber

A complex grating decay process is observed at elevated temperatures as predicted by a recently proposed three-energy-level model. We have also measured thermal stability of fiber gratings of both positive and negative index changes in a boron-codoped germanosilicate fiber in order to characterize the energy levels of the system and to predict grating lifetimes. The negative index gratings are found to be able to operate at 300 degrees C for more than 25 years without significant degradation.

[Effects of low pH and nicotine on carotid body chemoreceptor activity in the rabbit]

The unit discharges of carotid chemosensory afferent fibers were recorded in the in vitro carotid body (CB)--sinus nerve preparations (n = 55) from 29 rabbits. The results were as follows: (1) The discharge of all the units increased from 0.86 +/- 0.21 to 1.75 +/- 0.40 imp/s (P < 0.001) upon lowering the pH of modified Locke solution. (2) Addition of nicotine at doses of 1, 3, 6, 10 and 15 micrograms/ml to the solution led to a dose-dependent increase in the discharge from 0.60 +/- 0.21 to 0.96 +/- 0.21, 1.19 +/- 0.30. 1.24 +/- 0.29, 1.48 +/- 0.41 and 1.82 +/- 0.39 imp/s, respectively (r = 0.94, P < 0.001, n = 10). Nicotinic stimulation was antagonized by D-tubocurarine but the basal discharge was not significantly affected. (3) Superfusion of the CB with acid solution increased the discharge from 0.95 +/- 0.34 to 1.84 +/- 0.55 imp/s (P < 0.01, n = 19); After injections of nicotine 1-5 micrograms/ml to acid perfusate the unit discharge showed an increase from 0.96 +/- 0.25 to 1.53 +/- 0.24 imp/s. The degree of increase was less as compared with that due to mere acidification (P < 0.05). (4) D-tubocurarine did not alter the action of acid solution on chemosensory discharge (P > 0.05, n = 17). The present results suggest that ACh might act only as a modulator on carotid chemosensory activity without involving N-cholinergic receptor directly as did by low pH perfusion of CB.

Acousto-optic superlattice modulator using a fiber Bragg grating

A modulator is reported in which an extensional acoustic wave is launched along a fiber Bragg grating. The acousto-optic superlattice effect causes an enhancement in reflectivity within a narrow spectral region on both sides of the Bragg wavelength. For a fixed acoustic propagation direction, the Doppler shift can be either positive or negative, depending on whether the wavelength of the incident light lies above or below the Bragg condition. The device can function as a Bragg cell and a tunable filter.

Efficient single-frequency fiber lasers with novel photosensitive Er/Yb optical fibers

Boron- and germanium-doped highly photosensitive cladding is used in a novel design to achieve photosensitive Er/Yb-doped fibers, permitting short, strong gratings (length approximately 1 cm, reflectivity >99%) to be written without hydrogenation. The high absorption at 980 nm in Er/Yb fibers permits efficient pump absorption over a short device length, which is ideal for achieving highly efficient single-frequency fiber lasers. Both single-frequency Bragg-grating reflector and distributed-feedback lasers with slope efficiencies of 25% with respect to launched pump power have been realized in such fibers.

[Research on the reproducibility and selection of experimental conditions of capillary electrochromatography]

In this work, we prepared the packed columns for capillary electrochromatography (CEC) with 75microm and 100microm i.d., both of coupled mode and uncoupled mode. A mixture of thiourea and other three aromatic compounds was employed to evaluate the efficiency of the CEC columns. RSD values of retention times smaller than 2.12% was obtained on the home-made CEC system. The influence of pH value and the concentration of the organic solvent in the buffer on the retention behavior was investigated, giving a guide to the selection of experimental conditions. High speed analysis can be achieved by using high pH value buffers. Higher concentration of acetonitrile will improve the elution ability, while lower ocncentration of acetonitrile would improve the resolution. Seven kinds of neutral molecules were separated efficiently within 25 minutes. The results from the two modes of CEC columns were compared.

Matching Ca efflux and influx to maintain steady-state levels in cultured cardiac cells. Flux control in the subsarcolemmal cleft

The study examines the feed-back mechanism by which Ca efflux via Na/Ca exchange adjusts to match Ca influx via Ca channels-the condition which must obtain if cellular steady-state Ca level is to be maintained. It is proposed that variation in Ca channel influx produces changes in sarcoplasmic reticulum content which, in turn, through interaction within the subsarcolemmal cleft space, sets the level of Na/Ca exchange-mediated efflux. We measured Ca channel influx with whole-cell voltage-clamp, Ca efflux specifically via Na/Ca exchange by high resolution, non-perfusion-limited 45Ca wash-out technique and sarcoplasmic reticulum (SR) Ca content by combination of the latter with measurement of sarcolemmal Ca-binding by use of instantaneous "gas-dissected" sarcolemmal membrane isolation. Ca channel influx was varied by Bay K 8644 or nifedipine. Ca influx via Ca channels was increased by 37.8% with Bay K and decreased by 68% with nifedipine. The SR contribution to Na/Ca exchange-mediated efflux was increased by 36.7% with Bay K and reduced by 66.8% by nifedipine-virtually identical changes. Application of the cleft space model to determine beat-to-beat efflux via Na/Ca exchange predicted values which closely matched beat-to-beat channel influx.

[Relationship between reaction of membrane potential and size of glomus cells in rat carotid body during hypoxia]

The membrane potentials (Em) of 85 cultured isolated glomus cells were measured by intracellular recording. The shapes of glomus cells were recorded by microscopic photograph and the cell diameter was measured by micrometer enlarger. The glomus cells with different diameters exhibited two distinct responses to hypoxia. The glomus cells with diameter shorter than 10 microns were depolarized in response to hypoxia, while the cells with diameter over 10 microns were hyperpolarized during hypoxia. Thus, it is sugested that glomus cells may be divided into two functionally different subtypes. Although the smaller glomus cells depolarized more seriously under extreme hypoxia, the degree of hypoxia could not change the original response pattern of glomus cells to hypoxia.

Inflammatory damage to skin by prolonged contact with 1,2-dichlorobenzene and chloropentafluorobenzene

Skin samples from Fischer-344 rats and Hartley guinea pigs exposed dermally to 1,2-dichlorobenzene (DCB) and chloropentafluorobenzene (CPFB) for up to 4 h were examined for chemical-induced damage. Samples were stained with hematoxylin and eosin and scored for polymorphonuclear cell (PMN) margination, dermal inflammation, and epidermal necrosis by light microscopy. Ultrastructural evaluation of samples fixed with 2% glutaraldehyde and postfixed with 1% osmium tetroxide was used to visualize margination of PMNs. Guinea pigs exhibited postexposure inflammatory changes following an exposure of about an hour-and-a-half shorter duration than rats. DCB-induced inflammation and PMN margination occurred following an exposure about a half hour shorter in both species compared to CPFB. In contrast, epidermal necrosis was more severe with CPFB than with DCB. These changes may account for decreases in chemical penetration rates which have been observed in previous studies with DCB and CPFB in rats and guinea pigs.

Aggregation of mutant Cu/Zn superoxide dismutase proteins in a culture model of ALS

Mutations in the Cu/Zn-superoxide dismutase (SOD-1) gene underlie some familial cases of amyotrophic lateral sclerosis (FALS), a neurodegenerative disorder characterized by loss of cortical, brainstem, and spinal motor neurons. To investigate the mechanisms responsible for the toxicity of mutant enzyme, SOD-1 cDNAs bearing mutations found in FALS patients (mSOD) were expressed in cultured spinal motor neurons, dorsal root ganglion (DRG) and hippocampal neurons. Many features of motor neuron disease seen in humans with FALS and in transgenic mouse models were reproduced, including preferential susceptibility of motor neurons to toxicity of mSOD. Abnormal cytoplasmic aggregation of mSOD protein was observed in mSOD-expressing motor neurons, but never in neurons expressing SODwt enzyme, and was followed by evidence of apoptotic cell death. Such aggregates were not observed in nonvulnerable neuronal populations expressing mSOD (DRG or hippocampal neurons). Aggregation of SOD-1 may contribute significantly to the death of motor neurons expressing mutations associated with FALS-1 and the mechanisms leading to aggregation may pertain to the specific vulnerability of motor neurons in this disease.

Characteristics of risk-taking behaviors, HIV and AIDS knowledge, and risk perception among young males in southwest China

A cross-sectional survey was undertaken to describe risk-taking behaviors and to assess the knowledge and risk perception of HIV and AIDS among young males aged 18 to 29 years in 82 villages in Longchuan, Yunnan, China, in 1994. Information on demographic, behavioral, and drug-using factors, and knowledge of HIV transmission and prevention, and risk perception was collected using an interviewer-administered anonymous questionnaire. A total of 1,548 individuals were interviewed and 433 drug users, including 52 nonsharing injectors and 140 sharing injectors, were identified. Over half the individuals scored 0 on HIV knowledge, but knowledge was greater among nonsharing drug injectors. Most drug injectors had initiated drug injection after 1990. The reported incidence continues to increase in all three major ethnic groups. Sharing of equipment was common (73%) among injectors. Drug users were four times more likely to have had premarital or extramarital sex, but condoms were used by only 2.5%. Thus, factors promoting spreading of HIV are common in this area. We recommend that a community-based intervention program, targeting both young men and women, be implemented and evaluated in Longchuan as soon as possible.

158-microJ pulses from a single-transverse-mode, large-mode-area erbium-doped fiber amplifier

We report the amplification of 10-100-pJ semiconductor diode pulses to an energy of 158 microJ and peak powers >100 kW in a multistage fiber amplifier chain based on a single-mode, large-mode-area erbium-doped amplifier design. To our knowledge these results represent the highest single-mode pulse energy extracted from any doped-fiber system.

Verification of radiosurgery target point alignment with an electronic portal imaging device (EPID)

A procedure has been developed using an electronic portal imaging device (EPID) to verify that the center of a patient's lesion is aligned with the center of a treatment cone prior to treatment in a linac-based stereotactic radiosurgery procedure. The coordinates of the lesion center are set on the Brown-Roberts-Wells phantom base using a target simulator. A 3 mm tungsten ball, mounted on the target simulator, is used as the reference point for the planned isocenter. The target simulator is then attached to an adapter mounted on the linac couch, and an EPID image of the simulated target is acquired. The center of the circular-shaped radiation field is calculated from the centroid of the segmented EPID image, and the center of the tungsten ball is identified by an automated computer search algorithm. A summation filter is used to find the position of the lowest radiation intensity coincident with the center of the ball. The alignment error is defined as the difference between the center of the radiation field and the center of the ball. The accuracy of this method was tested and found to be within 0.2 mm. The advantage of the EPID-based procedure is that it can give quantitative offset values quickly for immediate readjustment. We have found that the method is also a convenient tool for testing room laser alignment and the accuracy of the treatment cones.

[Pharmacognostical identification of niuxi from Guizhou Province]

In this paper, 7 kinds of Niuxi from Guizhou Province have been studied on their pharmacognostical characters, histological characters and effective constituents and the difference of species have been found based on the experimental results.

Negative-index gratings formed by a 193-nm excimer laser

We have demonstrated fast formation [~1500 pulses at ~1 (J/cm(2))/pulse] of fiber gratings with highly negative index modulations (~-3 x 10(-4)). We have found that the maximum negative index modulations that are achieved do not depend on the pulse intensities, although the inverse of the time taken to reach the negative index-modulation maximum varies linearly with the pulse intensities. This prompts us to use a three-energylevel system to model the photosensitivity in boron-doped germanosilicate fiber. All the necessary parameters of the model can be determined from a single growth measurement of the average index change, and the model's prediction fits well the measured index-modulation growth.

[Effects of different natural stimulants on the activity of the rabbits' carotid chemoreceptor]

The effects of different natural stimulants on the afferent unit discharge of rabbit carotid chemoreceptors were studied in the in vitro carotid body- sinus nerve preparation. A total of 32 chemoreceptive units were recorded. The results were as follows: (1) Of the 32 units, 10 (31%) showed chemosensory responses only to PO2 decrease; 9 (28%) to all stimulants (PO2 decrease, PCO2 increase and pH decrease); 9 (28%) to PO2 decrease and PCO2 increase; 3 (9%) to PO2 decrease and pH decrease; only one to pH decrease. (2) The potency of the three natural stimulants in eliciting the changes in intensity of discharge showed a decreasing order as follows: PO2 decrease > PCO2 increase > pH decrease. The above results suggest that the carotid body may contain only one or a combination of 2 or 3 kinds of chemoreceptors respectively sensitive to decrease PO2 to increase PCO2 or decrease pH.

Fiber Bragg gratings with various chirp profiles made in etched tapers

We have studied, both theoretically and experimentally, fiber Bragg gratings with a number of different chirp profiles. These chirp profiles can easily be achieved by a recently demonstrated technique involving a taper of desired profile etched into the cladding of a fiber. The performances of gratings with linear, quadratic, periodically modulated, and step-chirp profiles are analyzed numerically. The versatility of the technique was demonstrated when linearly and quadratically chirped gratings were made as examples of continuous chirp, and gratings with step chirps were made as examples of discontinuously chirped structures.

Risk factors for initiation of drug use among young males in southwest China

To identify risk factors for drug use among young males in southwest China a cross-sectional survey and a non-concurrent cohort study were conducted. Demographic, behavioral and drug-use information was collected from young males aged 18-29 years. The non-concurrent cohort included the period 1 January 1991 to 1 August 1994. A total of 1548 subjects were interviewed. The cumulative incidence increased between 1991 and 1993. Multivariate analysis identified the following significant risk factors for drug use: being divorced/widowed/separated, having been encouraged by friends/others to try drugs, smoking cigarettes, belonging to the Jingpo ethnic group, and having a family member who used drugs in 1991. More than 6 years of education was a protective factor for drug use. Drug use in the community was associated with having been encouraged by friends or others to try drugs (71%), to smoking cigarettes (50%), and to belonging to the Jingpo group (24%). The results are consistent with community based prevention approaches which should be studied carefully because of the unique cultural and epidemiological situation in China.

Role of intracardiac angiotensin II in cardiac dysfunction of rat during septic shock

OBJECTIVE

To observe changes in the content of myocardial angiotensin II and its role in cardiac dysfunction of rat during septic shock.

METHODS

Septic shock model was produced by cecal ligation and puncture (CLP) operation on rats. Experimental rats were given captopril 15 mg.kg-1/d per os for 3 days before CLP operation. Mean blood pressure and left ventricular pressure were recorded. Myocardial angiotensin converting enzyme (ACE) activities were determined by a fluorometric assay and myocardial angiotensin II content was measured by radioimmunoassay. 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

Myocardial angiotensin II content increased by 51.5% (P < 0.01) at the 18th hour post CLP, meanwhile there was a decrease in left ventricular +/- dp/dtmax value and the impairment in Ca2+ uptake and (3H) ryanodine binding to cardiac SR. Preliminary administration of captopril reduced myocardial ACE activity and angiotensin II content, but increased left ventricular +/- dp/dtmax value. In comparison to shock group, the initial rate and the capacity of SR Ca2+ uptake were increased by 120% (P < 0.01) and 33.9% (P < 0.05), the Bmax value of (3H) ryanodine binding to SR was also elevated, while the Kd value remained unchanged.

CONCLUSIONS

The elevated intracardiac angiotensin II, resulting from the activation of myocardial ACE during sepsis, probably serves as one of the important mediators participating in the pathogenesis of heart failure: the effects of angiotensin II may be associated with the disturbance of Ca2+ transport function of cardiac SR.

Reversible and irreversible immobilization of enzymes on Graphite Fibrils

Graphite Fibrils are hollow tubes (0.01 x 1-10 microns) consisting of concentric layers of graphite. Fibrils can be chemically modified to introduce surface functionalities such as carboxyl groups. Carboxylated fibrils were further functionalized to amino alkyl derivatives which were covalently linked to an enzyme, horseradish peroxidase (HRP). HRP fibrils showed substantial catalytic activity. Additionally, carboxyl fibrils were derivatized with specific inhibitors of the enzymes beta-galactosidase (beta-Gal) and alkaline phosphatase (AP). Enzyme inhibitor-modified fibrils were used to specifically purify both beta-Gal (using beta-Gal inhibitor fibrils) and AP (using AP inhibitor fibrils) from mixtures of these two enzymes. These studies demonstrate the feasibility of using Graphite Fibrils as supports in biocatalysis and biospecific affinity chromatography.

Risk factors for intravenous drug use and sharing equipment among young male drug users in Longchuan County, south-west China

OBJECTIVES

To identify the risk factors for intravenous drug use and sharing of equipment in Longchuan County in south-west China.

METHODS

Demographic information and sexual and drug-use-related behavior between 1 January 1991 and 1 August 1994 were collected retrospectively from a cohort of young male drug users aged 18-29 years in 82 villages.

RESULTS

A total of 433 drug users were identified. The cumulative incidence of intravenous drug use was 40.0% during the 3.7-year study period. The annual incidence increased from 10% in 1991 to over 30% in 1994. Risk factors for intravenous drug use among drug users, according to the multivariate model, included having had premarital/extramarital sex [odds ratio (OR), 1.5; 95% confidence interval (CI), 1.01-2.3], having a family member who used drugs in 1991 (OR, 1.8; 95% CI, 1.1-2.9), and currently not married (OR, 1.6; 95% CI, 0.98-2.7). Being Buddhist protected against intravenous drug use (OR, 0.4; 95% CI, 0.2-0.9). The population attributable fraction was 30% for not being currently married, 17% for having had premarital/extramarital sex and 14% for having a family member who used drugs. The risk factor for sharing of equipment was being of Jingpo ethnicity (OR, 5.8; 95% CI, 2.5-13.8). The average incidence of sharing equipment was 19.6% per year. The population attributable fraction for sharing equipment was 58.5% for being Jingpo.

CONCLUSIONS

The incidence of intravenous drug use and sharing equipment is increasing. Therefore, it is urgent that vigorous, effective intervention programs be initiated in southern Yunnan. Unmarried, sexually promiscuous Jingpo drug users with a family history of drug use should be especially targeted. Given the problems of transport and communication in this remote area of China, intervention programs which use existing social, governmental and community networks should be implemented.

Cytochromes P450 5: induction of cytochrome P4501A1: a model for analyzing mammalian gene transcription

The induction of microsomal cytochrome P4501A1 by polycyclic aromatic hydrocarbons represents an interesting response by which mammalian cells adapt to xenobiotic exposure. Enzyme induction reflects increased transcription of the corresponding CYP1A1 gene. Analyses of the induction mechanism using genetic, biochemical, and molecular biological approaches have revealed a novel transcriptional regulatory pathway that involves ligand-dependent heterodimerization between two basic helix-loop-helix proteins (the Ah receptor and Arnt), interaction of the heterodimer with a xenobiotic-responsive enhancer, transmission of the induction signal from the enhancer to the CYP1A1 promoter, and alterations in chromatin structure. Current techniques permit examination of the induction mechanism in intact cells and analyses of the CYP1A1 gene in its native chromosomal configuration. Such experiments generate new insights into the control of mammalian transcription that are of relatively broad interest.

Systemic uptake and clearance of chloroform by hairless rats following dermal exposure. I. Brief exposure to aqueous solutions

The systemic uptake of chloroform from dilute aqueous solutions into live hairless rats under conditions simulating dermal environmental exposure was studied. Whole blood was sampled during a 30-min immersion of an animal within water containing a known concentration of chloroform and then for 5.5 h following its removal from the bath. The amount of chloroform systemically absorbed was determined by comparing the AUCs of the blood concentration vs. time plots from dermal exposure to that obtained after i.v. infusion (for a period of 30 min) of an aqueous solution containing a known amount of chloroform (positive control). Although dermal data implied two-compartment disposition characteristics, i.v. infusion data fit best to a three-compartment disposition. Linear pharmacokinetics was observed both by i.v. administration and percutaneous absorption at the dose levels studied. Chloroform was detected in the rat blood as early as 4 min following exposure. Our findings suggest that about 10.2 mg of chloroform was systemically absorbed after dermal exposure of a rat to an aqueous solution of 0.44 mg/ml. This amount is substantially higher than the predictions of mathematical risk-models put forth by some investigators. However, when expressed as the "effective" permeability coefficient (Kpeff), close agreement was noticed between our value and those estimated by others using physiologically based pharmacokinetic (PBPK) models. Also, in terms of Kpeff, reasonable agreement existed between our and another investigator's past estimates of uptake based on depletion of bath level of chloroform and the actual uptake measured in our current experiments. The estimated onset of systemic entry seen here is entirely consistent with our estimate of how long it takes to establish the diffusion gradient across the stratum corneum based on tape stripping.