In vitro and ex vivo activities of antimicrobial agents used in combination with clarithromycin, with or without amikacin, against Mycobacterium avium

MICs of clarithromycin, amikacin, isoniazid, rifabutin, ciprofloxacin, sparfloxacin, ethambutol, and clofazimine were determined for six isolates of Mycobacterium avium complex (MAC) from AIDS patients both by the radiometric method and by an ex vivo model of infection in human macrophages. The median MICs in macrophages were similar or slightly lower than values found in broth, except for amikacin, which had slightly higher MICs inside the cells. Combinations of clarithromycin with other antimicrobial agents showed that clarithromycin-clofazimine and clarithromycin-rifabutin were synergistic on five of six strains while clarithromycin-amikacin and clarithromycin-isoniazid were antagonistic on one and two strains, respectively. The addition of amikacin made the combinations of clarithromycin-clofazimine and clarithromycin-ethambutol synergistic against all the MAC strains. In the macrophage model, the combination of clarithromycin-clofazimine (mean survival, 21%) and clarithromycin-rifabutin (mean survival, 29%) showed a strong reduction in viable counts compared with single drugs, while clarithromycin-amikacin was less active than single drugs alone. In general, the addition of amikacin did not improve the activity of the combinations, except for clarithromycin-isoniazid-amikacin (mean survival, 19%), which was significantly more active than either clarithromycin-isoniazid or clarithromycin-amikacin. The use of the macrophage model can suggest new combinations of antimicrobial agents with anti-MAC activity which, on the basis of their in vitro effectiveness, would probably be disregarded for assay in animal models.

Clastogenic effects of 1,3-butadiene and its metabolites 1,2-epoxybutene and 1,2,3,4-diepoxybutane in splenocytes and germ cells of rats and mice in vivo

Clastogenicity of 1,3-butadiene (BD), 1,2-epoxybutene (EB), and 1,2,3,4-diepoxybutane (DEB) was studied in splenocytes and germ cells of rats and mice by means of micronucleus assays (cytokinesis-block method for splenocytes, suspension method for germ cells). Inhalation exposure of mice to 200, 500, or 1,300 ppm BD (6 h/d; 5 days) induced significant chromosome damage in spermatocytes at the preleptotene stage. EB and DEB induced significant amounts of clastogenic damage in splenocytes and spermatocytes of rats and mice. The lowest tested effective doses for mice and rats were, respectively, 40 and 80 mg/kg for EB, and 15 and 30 mg/kg for DEB. In splenocytes, 80 mg EB/kg induced 3.6 times more MN in mice than in rats, whereas 30 mg DEB/kg induced the same amount of damage in both species. Damage in germ cells of mice was induced in early spermatocytes treated with 40 and 80 mg EB/kg, and in late spermatocytes exposed to 30 mg DEB/kg. In rats, 40 mg EB/kg induced damage in early spermatocytes, whereas 80 mg EB/kg induced chromosomal damage in early and late spermatocytes. In rats treated with DEB, clastogenic damage was induced in spermatocytes at preleptotene, zygotene, diplotene, and diakinesis stages. When the clastogenic potential of EB and DEB in splenocytes and germ cells of mice and rats was compared, DEB always showed a stronger effect than EB. Body weight, testis weight, ratio of testis weight to body weight, and ratio of Golgi to Golgi + cap phase spermatids were used as parameters for toxicity. Exposures to 500 and 1,300 ppm BD were somewhat toxic to mice. Doses of 80 mg EB/kg and 30 mg DEB/kg exhibited toxic effects in mice and rats.

The expression of placental glutathione-s-transferase (gst-pi) in human normal salivary-glands and tumors

Immunohistochemical localization of placental glutathione S-transferase (GST-pi) in normal and inflammatory salivary glands (74 cases) and tumors (71 cases) was studied. In the normal and inflamed salivary glands of all locations (including major and minor salivary glands), the ductal epithelial cells showed moderate to strong GST-pi staining, myoepithelial cells showed weak staining and the acinar cells were negative. The staining pattern of the tumor cells was similar to that of their normal counterparts. The tumor cells were generally positive with GST-pi staining except those tumor cells demonstrating acini differentiation (serous cells in acinic cell carcinoma, mucous cells in mucinous cystadenoma and mucoepidermoid carcinomas). Most of the salivary gland tumors, benign or malignant, showed a weak GST-pi staining. Only mucoepidermoid carcinomas demonstrated significantly increased GST-pi reactivity compared to other tumors (p<0.0001), which may be a reflection of both malignancy and squamous differentiation of the tumor. The marked increase in GST-pi activity in mucoepidermoid carcinomas may be useful in serological screening of recurrent and metastatic mucoepidermoid carcinomas.

Increased frequencies of micronuclei in early spermatids of rats following exposure of young primary spermatocytes to acrylamide

The 'suspension method' for detection of micronuclei in early spermatids (Golgi phase 1 + 2) of rats was used to study induction of chromosomal damage in spermatocytes exposed to single (50 and 100 mg/kg) or fractionated (4 x 50 mg/kg; 24-h intervals) doses of acrylamide. Animals were killed at different time intervals after treatment to measure induction of damage in different stages of spermatocyte development. A statistically significant enhancement of micronucleus frequencies was found after exposure of pre-leptotene spermatocytes to a single dose of 100 mg/kg (days 18 and 20 after treatment) or a fractionated dose of 4 x 50 mg/kg (day 19). In the latter case there was also a significant effect in zygotene spermatocytes that were sampled 15 days after treatment. Comparative studies indicated that the original 'suspension method' can be simplified by omitting enzyme treatments for the release of germ cells from the seminiferous tubules. In the present acrylamide study the old and new procedures gave similar results.

[Effects of fibronectin on cell attachment and migration of human tongue squamous cancer line Tca8113]

By using the cell culture technique in vitro, quantitative studies were carried out to test the effects of fibronectin (FN) on cell biological behaviour of human tongue squamous cancer line Tca8113 in terms of cell attachment to rat-tail collagen substrata supplemented with different concentration of FN or/and anti-FN serum as well as cell migrating distance from the agarose drop cultured with different media containing FN or/and anti-FN serum. The results displayed that FN could increase the density of cells attached to collagen substrata; the cell attachment was dose-dependent on FN. In addition, cell migration from the agarose drop might be induced and cell motility might be promoted by FN. Anti-FN serum could abolish or weaken the above-mentioned FN effects.

A single promoter sequence recognized by a newly identified alternate sigma factor directs expression of pathogenicity and host range determinants in Pseudomonas syringae

A conserved sequence motif associated with transcription of avr genes was identified in the promoter regions of six Pseudomonas syringae pv. syringae Pss61 hrp operons. A 34-bp fragment carrying this motif was cloned from the HrpZ promoter region and was shown to confer HrpL-dependent promoter activity. Expression of pathogenicity and host range determinants in P. syringae strains is thus directed by the apparent alternate sigma factor HrpL.

[Changes in cell spreading area and cell surface morphology of Tca8113 line affected by fibronectin]

Morphometric changes in cell spreading area and morphological alternation in cell surface of human tongue squamous cancer line Tca8113 on rat-tail collagen substrata supplemented with different concentration of FN and/or anti-FN serum were quantified and observed with cell culture technique as well as light and scanning electron microscopes. It was found that FN could increase the cell spreading area and also area of lamellar cytoplasm of Tca8113 cells on collagen substrata, and that cells grown on FN-collagen substrata tended to flatten out, stretch out more filopodia, and sink more deeply into the substrata with the FN concentration. The results indicated that FN might relate closely to certain stages in the process of tumor invasion.

[Immunohistochemical observation of anti-human hepatocellular carcinoma monoclonal antibody HL2 in cancers]

Molecular weight of human hepatocellular carcinoma (HCC)-associated antigen-HL2 antigen was detected to be about 50,000 dalton by SDS-PAGE and Western blot. One hundred and twenty-seven paraffin sections of cancers and pathological liver tissue were tests by ABC immunohistochemical staining. MAb HL2 reacted with 62.7% HCC and also with 8 of the 10 stomach carcinomas but only with a few other digestive system carcinomas (pancreas carcinoma, rectum carcinoma and duodenum carcinoma) and hepatitis. MAb HL2 was negative in hepatocirrhosis and other tumors (vesica carcinoma, skin carcinoma, breast carcinoma, neurogliocytoma and carcinoma of the lung). The results suggest that MAb HL2 has values in diagnosis of HCC and differential diagnosis between HCC and other tumours. HL2 antigen might be a new tumor-associated antigen (TAA). Further study of HL2 antigen will significantly show the actions of TAA in the occurrence and development of tumor.

[Subclavian steal syndrome: a report of 25 cases]

From 1982 to 1992, 25 patients with subclavian steal syndrome (SSS) were admitted with 20 undergoing surgery. Etiology included atherosclerosis 56% (14/25), Takayasu's disease 36% (9/25), 14 of them were smokers. Stenosis or occlusion of the left subclavian artery were found in 14, the right in 7, and bilateral in 4. 14 cases had vertigo symptoms, 24 cases had claudication of the arm, 9 of them complained transient ischemic attack (TIA). Carotid to subclavian bypass were performed for 15 cases. Two patients underwent axilloaxillary bypass with evidence of both clinical and laboratory improvement. Aorta-Carotid graft bypass was done in 2 cases with good result in one. PTA was done for a girl with innominate severe stenosis but symptom recurred three months later. Symptoms of the upper extremity ischemia were relieved in 75% of the patients, and of the cerebrovascular ischemia in 50%. Our conclusion is that surgical therapy remains the treatment of choice in symptomatic patients.

Increase in placental glutathione S-transferase in human oral epithelial dysplastic lesions and squamous cell carcinomas

This study investigated the immunohistochemical expression of human placental glutathione S-transferase (GST-pi) in the epithelium of oral premalignant and malignant lesions. Epithelial lining of normal oral mucosa, hyperplastic lesions and oral epithelium exhibiting mild dysplasia showed weak to moderate GST-pi staining. Moderate epithelial dysplasia revealed an increased antibody content while severe dysplasia, carcinoma-in-situ (CIS) and squamous cell carcinoma (SCC) demonstrated markedly increased antibody binding. The GST-pi staining was evident mainly in the cytoplasm. Severe dysplasia, CIS and SCC were also characterized by areas of cells with intensive nuclear GST-pi staining. These findings support the hypothesis that GST-pi plays a role in human oral carcinogenesis and may be used as a tumor marker for human oral premalignant and malignant lesions.

Induction of IL-1 beta, IL-6, TNF-alpha, GM-CSF and G-CSF in human macrophages by smooth transparent and smooth opaque colonial variants of Mycobacterium avium

Both smooth transparent (SmT) and smooth domed-opaque (SmD) colonial variants were obtained from a strain of Mycobacterium avium isolated from a patient with AIDS. The two variants showed similar biochemical characteristics but SmT bacteria proliferated better than SmD bacteria inside human macrophages and were much less capable than the SmD variant of inducing the release of IL-1 beta, IL-6, TNF-alpha, GM-CSF and G-CSF, after incubation for either 3 or 6 days. As cytokines are important extracellular signals for immune cells, the lack of induction observed in SmT-infected macrophages may be one of the pathogenic mechanisms of M. avium.

Identification of a putative alternate sigma factor and characterization of a multicomponent regulatory cascade controlling the expression of Pseudomonas syringae pv. syringae Pss61 hrp and hrmA genes

The Pseudomonas syringae hrp and hrmA genes controlling pathogenicity and elicitation of the hypersensitive response and the avr genes controlling host range have been shown previously to be regulated by carbon, nitrogen, pH, osmolarity, and hypothetical plant factors. In P. syringae pv. syringae Pss61, inactivation of hrp complementation groups II and XIII reduced expression of a plasmid-borne hrmA'-lacZ fusion. The hrp regions II and XIII were cloned on separate plasmids and shown to enhance the activity of the hrmA promoter in Escherichia coli MC4100 transformants at least 100-fold. The nucleotide sequence of region XIII revealed two open reading frames (hrpR and hrpS) whose deduced products share homology with P. syringae pv. phaseolicola NPS3121 HrpS and are both related to the NtrC family of two-component signal transduction systems. HrpR and HrpS differ from most members of the protein family by lacking an amino-terminal domain which modulates the regulatory activity. A single open reading frame, hrpL, whose product shares homology with AlgU, a putative alternate sigma factor of P. aeruginosa, as well as with the related alternate sigma factors was identified within region II. Key domains are partially conserved. Inactivation of hrpS in Pss61 repressed expression of a plasmid-borne hrpL'-lacZ fusion carried by pYXPL1R, and transformation of MC4100(pYXPL1R) with a plasmid carrying hrpRS increased hrpL promoter activity at least 200-fold. Neither hrpS nor hrpR, when cloned on separate plasmids, activated the hrpL promoter activity individually. The expression of hrpL when directed by a lac promoter was sufficient to express a set of plasmid-borne hrmA'-, hrpJ'-, and hrpZ'-lacZ fusions independently of other hrp genes. The results indicate that hrpRS and hrpL are part of a regulatory cascade in which HrpR and HrpS activate expression of hrpL and HrpL, a putative sigma factor, induces expression of HrpL-responsive genes.

Comparison of placental glutathione-s-transferase with gamma-glutamyl-transpeptidase as tumor-markers during hamster pouch carcinogenesis

This study investigated the expression of placental glutathione S-transferase (GST-P) in late squamous cell carcinomas and its expression after withdrawal of short term carcinogen treatment using the hamster buccal pouch mucosa (HBPM) model, and compared the activity of GST-P with that of gamma-glutamyl transpeptidase (GGT). 25 of 32 (78%) tumors induced by an 18-week treatment with 0.5% dimethylbenz(a)anthracene (DMBA) stained positive with GST-P while only 2 (6%) tumors were positive for GGT. Numerous GST-P positive foci were present in the pouch epithelium with 3 weeks of DMBA treatment. At week 6, after 3-week discontinuation of the carcinogen treatment, the average number of GST-P foci was not significantly less than that of week 3. Numerous GST-P foci were still evident at week 9 after 6-week discontinuation of the carcinogen treatment, although the number was significantly less than those of weeks 3 and 6. In contrast, GGT foci were hardly identifiable after discontinuation of the carcinogen treatment and the number of GGT foci at both weeks 6 and 9 was significantly less than that of week 3. The results suggest that GST-P may be a more persistent and stable tumor marker than GGT in the HBPM model.

Gene targeting of X chromosome-linked chronic granulomatous disease locus in a human myeloid leukemia cell line and rescue by expression of recombinant gp91phox

The X chromosome-linked chronic granulomatous disease (X-CGD) locus, which encodes the gp91phox subunit of the phagocyte respiratory-burst oxidase cytochrome b, was disrupted by homologous recombination in the PLB-985 human myeloid cell line to develop an in vitro model of X-CGD. Superoxide formation was absent in targeted cells after differentiation to granulocytes but was rescued by stable transfection and expression of wild-type gp91phox cDNA. The targeted cell line should be useful in experiments aimed at defining functional regions within gp91phox by expression of mutant gp91phox cDNAs, complementing studies of naturally occurring mutations in X-CGD. In addition, the mutant line provides a model system in which to establish an experimental basis for the treatment of X-CGD patients with gene replacement therapy. Rescued clones containing even modest amounts of recombinant gp91phox had respiratory-burst activity comparable to the wild-type PLB-985 line, suggesting that functional correction of X-CGD neutrophils may not require high-level expression of gp91phox.

[Role of central vasopressin in the maintenance of cardiovascular activities during acute hypoxia]

To investigate whether central vasopressin play a role in the maintenance of cardiovascular activities of rats exposed to acute hypoxia, blood pressure, heart rate, pressures of left and right ventricles and their dp/dt were monitored in rats anesthetized with urethane. The rats were divided into three groups, each of which received intracerebroventricular injection (icv.) of V1- and V2-vasopressinergic antagonists (4 micrograms, each) and equivolumetric vehicle (8 microliters, served as control group). Ten min after icv. three groups of rats were exposed to acute hypoxia (9% O2 in N2) for 15 min before reoxygenation. During hypoxia, MBP, HR, LVSP and LV + dp/dtmax of V1-antagonist treated group decreased more significantly than those of the control group (P < 0.01). After reoxygenation there were no significant differences between both groups. V1-antagonist and the vehicle had no detectable effect on the cardiovascular parameters during normoxia. Although icv. V2-antagonist caused a transient augmentations of HR, MBP, LVSP and LV + dp/dtmax except for RVSP and RV + dp/dtmax, there were no significant differences in cardiovascular activities between V2-antagonist treated group and control group during hypoxia and reoxygenation. These results indicate that central endogenous vasopressin play an important role in the maintenance of cardiovascular activities during hypoxia via its V1-receptor without involving V2-receptor. The central vasopressin does not have a tonic effect on cardiovascular activities under normal conditions.

Characterization of the Pseudomonas syringae pv. syringae 61 hrpJ and hrpI genes: homology of HrpI to a superfamily of proteins associated with protein translocation

The Pseudomonas syringae pv. syringae 61 hrpJ and hrpI genes were sequenced and found to encode predicted proteins of 37,710 Da and 76,490 Da, respectively. The products of these genes were confirmed by T7 polymerase-dependent expression and sodium dodecyl sulfate-polyacrylamide gel analysis. HrpI belongs to a superfamily of proteins represented by Yersinia pestis LcrD.

Air pollution-type fluorosis in the region of Pingxiang, Jiangxi, Peoples' Republic of China

This paper reports on the epidemiology, environmental factors, geological features, and total amount of fluoride intake by residents of the Pingxiang region in the Peoples' Republic of China where there is a high incidence of endemic fluorosis. The results demonstrate that the type of endemic fluorosis is related to air pollution, the major source of which comes from coal that is burned by the residents in their homes. Air pollution also originates from the small kilns that are used to make bricks and tile. The fluorine content in the coal and mud used to mix the coal is considerably high; the content in the mud used as adobe for tiles exceeds 10,000 mg/kg. During the process of burning coal or baking bricks or tiles, a large amount of nonsoluble fluorine is converted into water-soluble fluoride, which can have major human health effects.

Comparison between the properties of 3-nitrosalicyl-N-alkylamide and antimycin A acting on QH2:cytochrome c reductase

3-Nitrosalicyl N-alkylamide was found to be an inhibitor different from antimycin A not only in its inhibitory nature but also in many other aspects. This difference indicated that the 11 kDa component, which was identified as the antimycin A (AA) binding factor in the QH2: cytochrome c reductase of Rhodopseudomonas sphaeroides by Wilson et al. ((1985) J. Biol. Chem. 260, 10288-10292) using the radioactive photoaffinity analogue 3-azidosalicyl N-octadecylamide, was not the genuine binding site of AA. Based on the observations that the 3-azidosalicyl N-alkylamide specifically inhibits the reactions of ubiquinone catalyzed by Q-related enzymes of the respiratory chain, the labeled 11 kDa factor might be one of the ubiquinone binding proteins in QH2:cytochrome c reductase.

[Effects of calcium blockers on the performance of left and right ventricles during acute hypoxia]

In anesthetized and thoracotomized 20 adult dogs under artificial respiration, the effects of calcium blockers (nifedipine, diltiazem and verapamil) on the mechanics of the left and right cardiac pumps under acute hypoxia were observed. The left and right ventricular pressure (LVP and RVP) and their dp/dt (+/- dp/dtmax), aortic flow (Fa), pulmonary pressure (Ppa) and heart rate (HR) were recorded. After treatment with calcium blockers, LVP and L +/- dp/dtmax decreased, and Fa increased, while RVP, R +/- dp/dtmax and Ppa all tended to increase. These results showed that the effects of calcium blockers on the performance of the left and right ventricles were different, suggesting that the dependence of left and right myocardium on calcium was different in degree. The mechanics of the left and right ventricles responded differently to calcium blockers under acute hypoxia. After treatment with calcium blockers, pressor responses on LVP by acute hypoxia disappeared. There was a great increase in Fa. Decrease in pressor response of RVP and Ppa was also observed in acute hypoxic dogs receiving verapamil and diltiazem. Comparing the effects of nifedipine, diltiazem and verapamil on the mechanics of the left and right cardiac pumps under acute hypoxia, it appears that diltiazem exerts beneficial effect on the performance of cardiac pump under acute hypoxia.

Suppression of cytoplasmic senescence in Neurospora

We have shown that senescence in Kalilo strains of Neurospora, caused by a linear mitochondrial plasmid called kalDNA, is suppressible by existing variants of the nuclear genome. The suppressors are manifested by 4:4 segregation of senescence and immortality in asci from crosses between senescent female strains and males chosen from non-senescent candidate stocks. In one case of suppression, the asci also show segregation at the plasmid level. There is a reduction of kalDNA to barely detectable levels in the four ascospores showing immortality, so this suppressor evidently influences the maintenance of the plasmid itself. In the other case of suppression, the phenotypic segregation is not correlated with segregation at the plasmid level, and all eight ascospores in the asci show both free and inserted forms of kalDNA. This suggests that the suppression genotype provides a way of tolerating the presence of the plasmid rather than diminishing it. However, the allele f, which provides an analogous kind of suppression for the cytoplasmic mutation poky, does not suppress Kalilo or Maranhar senescence. Suppression is hence shown to be a possible option for host strains to combat the plasmid in nature, but no examples of suppressors were found in a limited survey of natural isolates. In addition, we have shown that long-lived, presumably non-senescent, strains do not arise by suppressor mutation, but lose senescence plasmid DNA by another mechanism.

Organization and environmental regulation of the Pseudomonas syringae pv. syringae 61 hrp cluster

The ability of Pseudomonas syringae pv. syringae 61 to elicit the hypersensitive response in nonhost plant species has been linked to a cluster of hrp/hrm genes whose expression appears to be environmentally regulated. To understand the genetic organization of this hrp/hrm gene cluster and its expression during the interaction with nonhost plant species better, we constructed a set of chromosomal hrp-uidA fusions in P. syringae pv. syringae 61 by Tn5-gusA1 mutagenesis of the cloned hrp/hrm gene cluster and transferred them into the genome by marker exchange mutagenesis. Complementation analysis employing plasmid-borne Tn5-gusA1 insertions and previously characterized chromosomal TnphoA mutations defined at least eight apparent transcriptional units within the hrp/hrm cluster, several of which were multicistronic. The expression of hrp-uidA fusions in seven of these apparent hrp transcriptional units increased following inoculation into tobacco leaves. Enhanced expression from a representative fusion was detected 1 h after inoculation of tobacco leaves. The induction observed in planta was similar to the levels detected following culture of the bacteria in minimal-salts medium: irrespective of the carbon source. Complex amino acid sources, such as peptone, repressed the expression of P. syringae pv. syringae 61 hrp genes at levels exceeding 0.028%. The results indicate that enhanced expression of hrp genes occurs early in the interaction with nonhost plant species in an apparent response to altered nutritional conditions.

Inhibition of succinate-ubiquinone reductase by nitrosalicyl-N-alkylamides

The abilities of eight nitrosalicyl-N-alkylamides to inhibit succinate-ubiquinone reductase were compared. These compounds possess both a nitro group at 3- or 5-position of the benzyl ring, and a methyl, decyl, dodecyl or tetradecyl group subsituted for the amide hydrogen of salicylamide. The result shows the following: (a) 3-Nitrosalicyl-N-alkylamides are stronger inhibitors than 5-nitrosalicyl-N-alkylamides when they have the same alkyl group. (b) The inhibitory abilities of both 3-and 5-nitrosalicyl-N-alkylamides increase with increasing alkyl group length. (c) Kinetic data show that the inhibition by 3-nitrosalicyl-N-tetradecylamide is noncompetitive with respect to the electron acceptor Q2.

[Establishment of standard strains of serotypes (groups) of Streptococcus pneumoniae in China]

Streptococcus pneumoniae is an important human pathogen which is responsible for life-threatening infections such as pneumonia, bacteremia and meningitis as well as for less severe but highly prevalent diseases such as otitis media and sinusitis. The number of serogroups (types) of Streptococcus pneumoniae found in the world is total 46 groups or 83 types according to typing system of Statens Serum Institute, Copenhagen, Denmark. The standard strains established in our lab of 42 groups or 67 types distributed in 17 different regions in China. The significance of this study is that two of the new serotypes (10C, 16A) are first reported in the literature in which the microbes were the agents causing pneumococcal infections. Our standard strains also include some serotypes on rare occasions such as 19C and 22A and 33C which have been found only in Asia. Our findings not only increase the total number of known types of pneumococci from 83 to 85, but also indicate that China has made progress in the field of pneumococcal research. It is the first time to report establishing a series of standard strains of pneumococci involving many serotypes (groups) in China. The work is necessary as a preliminary for pneumococcal disease prevention and treatment. The standard strains listed here with providing the resource of strain and scientific basis for developing vaccine and biological products.

[Inhibition of growth and metastases of lung carcinoma in C57BL/6 mice by Corynebacterium parvum and its antitumor mechanism]

Cocrynebacterium parvum (CP) was injected around the tumor and tumor cells were inoculated subcutaneously with activated peritoneal macrophages. The effects on the growth and metastases of Lewis lung carcinoma in C57BL/6 mice were observed. Experimental results indicated that CP had significant inhibitory effect on the tumor growth and lung metastases. The cytotoxic effects of activated peritoneal macrophages in mice on target tumor cells (L5178Y) in vitro were studied with the technique of 3H-TdR assay. The proliferation of tumor cells was markedly inhibited by the activated peritoneal macrophages of CP. Experiments showed that the antitumor mechanism of CP was the mediation via activated cytotoxic macrophages. These results indicated that CP is an effective immunostimulant. These findings will provide a scientific basis for the clinical treatment of the primary and metastatic lung carcinoma.

Angiogenin depresses aortic smooth muscle cell cAMP by a pertussis toxin sensitive mechanism

Angiogenin transiently depresses the cAMP level of rat aortic smooth muscle cells. The dose response is similar to angiogenin activation of the inositol-specific phospholipase C in this cell line [Moore, F. & Riordan, J.F. (1989) Biochemistry. Submitted]. The time course showed a maximal depression (28%) in cAMP at 2 min, followed by a return to that of unstimulated cells by 3.5 min. Angiogenin also inhibited isoproterenol stimulated cAMP formation, but the percentage depression in cAMP (9%) was less than that in cells treated with angiogenin alone (28%). In contrast angiogenin enhanced forskolin stimulation of adenylate cyclase, an effect previously linked with agonist activation of protein kinase C. The effect of angiogenin on cellular cAMP was abolished by pre-incubation with pertussis toxin. Angiogenin had no effect on cellular cGMP. These results are consistent with activation of adenylate cyclase Gi following exposure of the cells to angiogenin and provide further evidence for interaction between cellular signalling pathways.

[A study of acute toxicity of mitoxantrone]

Acute toxicity of mitoxantrone (DHAQ) synthetized by Department of Organic Chemistry, School of Pharmacy, WCUMS was studied in mice and dogs. The toxic effects were compared with those of adriamycin (ADR). The LD50 were 6.6 +/- 1.3 and 7.1 +/- 1.6 mg/kg DHAQ, 7.9 +/- 2.1 and 10.7 +/- 2.2 mg/kg ADR (P = 0.95) respectively on observation with a single dose i.v. and i.p., for 21 days in Kunming mice. The toxicity appeared to be delayed with DHAQ and ADR. The earliest death occurred on 4th day after treatment in mice. In the third week still a few died. There were obvious decreases in WBC counts in the peripheral blood of mice receiving either 1-2.5 mg/kg DHAQ or 2.5-5 mg/kg ADR with a single dose i.p.. The WBC count could return to normality after 3 weeks with the withdrawal of the drugs. On electron microscopic examination of myocardial samples from mice 4 days after a single dose of 20 mg/kg DHAQ i.p., mitochondria swelling and vacuoles formation in some cells were shown. Besides the above-mentioned changes, some myocytes exhibited disorientation and loss of myofilaments in the mice which received equivalent dose of ADR. In dogs anaesthetized a temporary falling of blood pressure and slowing of heart rate were observed following 5-10 mg/kg DHAQ i.p.. When a dose of 50-100 mg/kg was given, the blood pressure dropped continuously until death.

Correlation of dietary aflatoxin B1 levels with excretion of aflatoxin M1 in human urine

Corn and peanut oil (total, 253 samples) were collected from 32 households in Fushui county of the Guangxi autonomous region of the People's Republic of China, where high liver cancer incidence has been reported, every day over a period of 1 week and analyzed for aflatoxin B1 (AFB). A total of 252 urine samples were collected simultaneously from the residents in the households which were shown to have consumed AFB and were analyzed for aflatoxin M1 (AFM) by a competitive direct enzyme-linked immunosorbent assay. A good correlation between total dietary AFB intake and total AFM excretion in human urine was observed during a 3-day study. A regression equation of 0.143 plus 0.0135 multiplied by the amount of AFB consumed was observed. Between 1.23 and 2.18% of dietary AFB was found to be present as AFM in human urine. A good correlation was also observed between the AFB concentration in corn and the AFM concentration in human urine. The results suggest that analysis of AFM in urine by enzyme-linked immunosorbent assay could be used as an index for human exposure of AFB in an extensive epidemiological study.

Studies on optic nerve of Lipotes vexillifer-structure, fiber count and diameter spectrum

Four optic nerves obtained from two Lipotes Vexillifer have been studied with the aid of electron microscope. The fiber diameter spectra of all the four optic nerves are unimodal. The diameters of fibers range from 0.35 to 7.45 microns with the highest frequency at 1.5 microns. T test indicates there is no significant difference in fiber density and fiber diameter between the central and peripheral regions of the optic nerve. The ratio of axon diameter to the total fiber diameter is 0.6 +/- 0.02 (p less than 0.05). The examination of four optic nerves indicates a mean count of 78,900 fibers; none of unmyelinated fibers have been seen. The shapes of the cross sections of fibers are very irregular. The myelin sheaths of some nerve fibers are very thick while those of some others are thinner.

Recent advances in anther culture of Hevea brasiliensis (Muell.-Arg.)

The yield of pollen embryoids from cultured Hevea anthers was increased 4 fold by optimizing the proportion of ammonium nitrate to potassium nitrate in the dedifferentiation medium. For optimal differentiation of pollen embryoids, kinetin, 2,4-D and α-naphtalene acetic acid are required. Anther culture for 50 days on the dedifferentiation medium is a prerequisite for the selective development of calli and embryoids from microspores.The determination of chromosome numbers in embryoids, plantlets and regenerated trees reveals that they originate from (poly)haploid pollen grains (n=2x=18). Aneuploid, triploid (3x=27) and tetraploid (4x=36) cells were encountered in increasing frequencies as the embryoids and plants developed. A few haploid cells with 9 chromosomes were consistently observed. Buds from shoots with mixoploid chromosome numbers can be grafted and the change in the chromosome constitution of the developing new shoots followed.