Increased pressor responsiveness of femoral arteries to exogenous norepinephrine in renal hypertensive dogs mediated through alpha 2 adrenoceptors

Changes of perfusion pressure induced by femoral arterial perfusion of norepinephrine (NE) were studied in renal hypertensive dogs made with the method of wrapping both kidneys. The NE threshold dose which induced perfusion pressure increase was lower in hypertensive dogs than that in normotensive dogs. The NE pressor response in low concentration (1, 2, 10 ng.kg-1) was increased in hypertensive dogs, after alpha 2 adrenoceptors antagonized by idazoxan this increased response had been eliminated. These suggested that increased vasoconstriction by exogenous NE in hypertensive dogs was mediated through the increased reactivity of postsynaptic alpha 2 adrenoceptors to NE.

[Distribution of 14C labeled at dioxopiperazine or methyl morpholine group of probimane by whole body autoradiography]

Probimane (AT-2153) is a new anticancer compound. It was first developed in this Institute. It is effective against mouse tumors S37, S180, Lewis lung carcinoma, L1210 and human pulmonary adenocarcinoma heterotransplanted into nude mice. In the present work, 14C was labeled at central dioxopiperazine or methyl morpholine group of probimane 120 mg.kg-1 was injected iv in mice bearing Lewis lung carcinoma by whole body autoradiography. The results showed that probimane was broken into at least two parts: a central part and a methyl morpholine group. The central part of compound hardly penetrated through the blood-brain barrier, but accumulated in the urinary bladder. The methyl morpholine group showed a high affinity to tumor tissue and accumulated in spleen, bone and liver.

A human mitochondrial transcriptional activator can functionally replace a yeast mitochondrial HMG-box protein both in vivo and in vitro

Human mitochondrial transcription factor A is a 25-kDa protein that binds immediately upstream of the two major mitochondrial promoters, thereby leading to correct and efficient initiation of transcription. Although the nature of yeast mitochondrial promoters is significantly different from that of human promoters, a potential functional homolog of the human transcriptional activator protein has been previously identified in yeast mitochondria. The importance of the yeast protein in yeast mitochondrial DNA function has been shown by inactivation of its nuclear gene (ABF2) in Saccharomyces cerevisiae cells resulting in loss of mitochondrial DNA. We report here that the nuclear gene for human mitochondrial transcription factor A can be stably expressed in yeast cells devoid of the yeast homolog protein. The human protein is imported efficiently into yeast mitochondria, is processed correctly, and rescues the loss-of-mitochondrial DNA phenotype in a yeast abf2 strain, thus functionally substituting for the yeast protein. Both human and yeast proteins affect yeast mitochondrial transcription initiation in vitro, suggesting that the two proteins may have a common role in this fundamental process.

[A study on classification of Xanthomonas by isoelectric focusing]

Studying Xanthomonas strains of 4 species and 29 pathovars by isoelectric focusing, it was shown that the protein patterns were very different among the species and pathovars. Through cluster analysis of IEF date, it was found that the protein pattern differences among certain pathovars were no fewer than that among the species. It revealed that some pathovars could become to be species. There were few differences of 6 protein bands among X. campestris pv. cerealis, X. campestris pv. undulosa and X. campestris pv. hordei which cause bacterial black cheff, so the classification of the three pathovars need to be re-considered. It also showed that isoelectric focusing could be used to classify Xanthomonas below species.

Cytotoxic effect of interferon on primary malignant tumour cells. Studies in various malignancies

It is a well established fact that interferon (IFN) can inhibit cell growth, but only recently has it been found that IFN can exert a direct cytotoxic effect on primary tumour cells. This was shown in malignant cells from patients with multiple myeloma. In this study the influence of IFN on the viability of primary malignant cells from patients with different malignancies was studied. As previously described a direct cytotoxic effect of IFN on multiple myeloma cells was observed. No major effects on cell viability could be found in malignant cells from patients with lymphoma, chronic lymphocytic leukaemia, hairy cell leukaemia, chronic myelogenous leukaemia and carcinoma. This indicates that the direct cytotoxic effect of IFN in multiple myeloma may be relatively specific for this malignancy. It could be due to a specific differentiation stage in the myeloma cells, specific genetic alterations and/or abrogation of an autocrine/paracrine loop.

[Role of the central alpha-receptors in the modulation of carotid sinus reflex of rats]

To investigate the effects of the central alpha-receptors on the carotid sinus reflex, phenoxybenzamine (PBZ, 2 micrograms/20 microliters) or yohimbine (Y, 2 micrograms/20 microliters) was injected into the lateral cerebral ventricle (LCV) and intracarotid sinus pressure (ISP)-mean arterial pressure (MAP) relationship curve was constructed and fitted by a Logistic function. The results were as follows: (1) After injection of PBZ into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range while the ISP-slope curve shifted downward. (2) After injection of Y into LCV, the ISP-MAP relationship curve shifted upward at a higher ISP level with decreased peak slope and MAP range and increased threshold. The ISP-slope curve shifted downward significantly at 10.64, 15.96 kPa. The peak slope and MAP range of Y group decreased significantly as compared with that of the PBZ group. These results indicated that after blockage of central alpha-receptors the sensitivity of the sinus reflex decreased significantly, and the blockage action of alpha 2-receptor is greater than that of alpha 1-receptor.

Baculovirus phosphoprotein pp31 is associated with virogenic stroma

The PstI K fragment of Autographa californica nuclear polyhedrosis virus (AcMNPV) encodes a protein with a molecular weight of 31,000. To define the role of this protein (pp31) in virus infection further, it was overexpressed in bacteria and used to produce polyclonal antiserum. Radioimmunoprecipitation analysis indicated that pp31 was synthesized during both the early and late phases of virus infection, consistent with previous analyses indicating that the gene was regulated by tandem early and late promoters. Metabolic labeling of cells with carrier-free phosphate indicated that pp31 was phosphorylated. Biochemical fractionation experiments showed that pp31 was localized in the nucleus and that it was more stably associated with the nucleus at later times of infection. Immunoblot analysis of subnuclear fractions indicated that pp31 was associated predominantly with the chromatin and nuclear matrix fractions. Immunofluorescence experiments confirmed that the pp31 protein was localized in the nucleus. Nuclear staining was relatively uniform early but was more centrally nuclear later in infection. Immunoelectron microscopy indicated that the pp31 protein was a component of virogenic stroma. Southwestern (DNA-protein) blot analysis demonstrated that pp31 is a DNA-binding protein. These findings suggest a possible role for pp31 in the virus life cycle.

[Effects of zinc deficiency and vitamin D deficiency on bone calcification and development of rats]

Zinc deficiency rat model was made by feeding zinc deficiency diet. The level of bone calcium of the zinc deficiency rats was significantly lower than that of the control rats. Their bone cortex was thinner and bone density decreased. The counts of their cartilage cells and hypertrophic cells of epiphyseal plate were less frequent, and the diameter of their hypertrophic cells was smaller than that of the controls. It suggested that zinc deficiency caused defective bone calcification which was similar to that in vitamin D deficiency. Zinc deficiency seemed to hinder the linear growth of long bone and might be the cause of dwarf.

Arginine vasotocin gene expression during osmotic challenge in the chicken

The avian hypothalamic nonapeptide arginine vasotocin (AVT) is released from axon terminals in the neural lobe upon the application of osmotic stimuli. We have investigated whether, and to what extent, hormone secretion from the neurohypophysis is related to gene expression in the hypothalamus. Results from hybridization experiments with an AVT-specific cDNA probe indicate that in adult chickens stimulated by water deprivation or by hypertonic saline (2% w/v) drinking water, an upregulation of the AVT mRNA pool takes place, since consistently higher AVT mRNA levels compared to controls were monitored in osmotically challenged birds. This stimulatory effect was even visible at the transcriptional level after 19 h of water deprivation when osmolality was still near the basal value. In hens osmotically challenged by hypertonic saline drinking water for 5 days, a dissociation between osmolality and AVT plasma concentration was visible: extremely high plasma osmolality was accompanied by only moderately increased plasma AVT concentration. This might be caused either by exhaustion of stored hormone, or by downregulation of the system after chronic challenge. The latter suggestion is supported by the fact that the AVT mRNA concentration after 5 days of hypertonic saline challenge was well below the AVT mRNA levels of the groups with the more short-term stimuli of water deprivation for 19 or 48 h. In 30-day-old chicks the hypothalamic AVT mRNA concentration hardly reached 70% of the adult value, although AVT plasma concentrations were similar to those in the mature bird. We conclude that osmotic challenge of the hypothalamo-neurohypophysial system not only causes secretion of AVT from stores in the neural lobe but is accompanied by upregulation of AVT gene expression. Upregulation already occurs after marginal increase in plasma osmolality, as seen after 19 h of water deprivation in hens. In 30-day-old chicks gene expression is only slightly upregulated after short-term water deprivation while increase in plasma AVT is even greater compared to hens.

[Effect of the central noradrenergic system on carotid sinus reflex in rats]

In order to study the effect of central noradrenergic system on the regulation of mean arterial pressure (MAP) by intracarotid sinus pressure (ISP), ISP-MAP relationship curves were constructed using isolated carotid sinus under the condition of injection of 6-OHDA (200 micrograms) into lateral ventricle or cauterization of locus coeruleus (LC) and compared with that obtained under the condition of control. All ISP-MAP curves can be fitted by a logistic functional plot whose characteristics can be defined by two parameters, i.e. coordinates of the inversion point of the slope of the curve and the MAP range related to the rate of change of slope factor with which carotid sinus pressure exerts its control. The results were as follows: After injection of 6-OHDA, the rate of change of the slope of the ISP-MAP curve is considerably slower than that of the normal control, thus showing a much compressed range of MAP by ISP, while the abscissa (i.e. position of ISP) of the slope inversion point of the curve shows practically no change. In comparison with the control, cauterization of LC causes a similar but less striking change of ISP-MAP curve than that of 6-OHDA injection experiment. All such differences were illustrated in Fig. 3. The above results indicated that the central noradrenergic system facilitates carotid sinus reflex and LC plays a dominant role.

Assignment of a yeast protein necessary for mitochondrial transcription initiation

Yeast mitochondrial DNA contains multiple promoters that are responsible for expression of its genes. The basic yeast mitochondrial promoter consists of a nonanucleotide consensus sequence [5'-ATATAAGTA(+1)-3'] that must be recognized by transcription proteins, including mitochondrial RNA polymerase and any relevant trans-acting factors. Since mitochondrial RNA polymerase alone appeared unable to recognize a mitochondrial promoter, we examined the effects of providing accessory proteins to enable promoter function. After expression in Escherichia coli or purification from yeast mitochondria, two proteins were tested; they were ABF2 (a structural homologue of the human mitochondrial transcriptional activator mtTF1) and MTF1 (the gene product of a yeast locus known to exhibit a mitochondrial transcription phenotype). The results show that MTF1 specifies correct transcriptional initiation while ABF2 does not. We conclude that MTF1 is an essential key protein in yeast mitochondrial promoter function. Considering the increasing complexity of the mitochondrial transcription apparatus, we propose a nomenclature system for its components.

[Methanogens from feces of patients with intestine disorder]

Fecal specimens from 10 colorectal cancer, 1 duodenum diverticulosis and 2 healthy adults were examined. Nine fecal enrichments contained Methanobrevibacter. The percentage of methanogen positive individuals was 69% Methanobrevibacter were isolated from fecal enrichments of 4 colorectal cancer and 1 duodenum diverticulosis. The percentage of breath methane positive individuals and methane production had significantly increased in colorectal cancer patients. It will be hopeful that methane production in breath samples at the end of exhalation will became a rapid, simple and non-penetrative method for monitoring precancerous colonic or rectal carcinogenesis and monitoring the relapse of individuals with carcinosectomy.

A computer-assisted image processing method for determining relative cardiac function in the chick embryo

The general objective of this study was to develop a noninvasive method for efficiently and reproducibly determining relative cardiac function parameters in the chick embryo. The specific objectives of the study were 1) to develop several methods for computer-assisted image processing and quantitation of relative intraventricular blood volumes in the 3-day-old embryonic chick heart and 2) to compare methods for precision and with a previously established manual processing method. Images of the embryonic chick heart in ovo were recorded on videocassette tape, digitized, and enhanced by computer-aided histogram equalization. The area occupied by blood within the common ventricle was extracted by region-growing and spurious region removal algorithms and defined by the determination of edge-pixel coordinates. Edge-pixel coordinates of the longitudinal and transverse axes of the common ventricular blood region were located by three different methods, the lengths of the axes calculated, and volumes computed from the equation for determining volume of a prolate spheroid. Twenty-five images of the embryonic heart were randomly selected and processed. Volumes were calculated with each of the three methods on six different occasions. A coefficient of variation was calculated for each method. The intraobserver mean coefficient of variation for each method was 7.4%. When a 2-way ANOVA was conducted, mean coefficients of variation did not differ significantly for the three methods. However, computer processing (in addition to significantly reducing the time required to generate data) reduced the coefficient of variation observed in manual processing by 56.5%.

Efficacy of bimolane in the Malassezia ovalis model of psoriasis

Bimolane, an analog of razoxane has been used in China with comparable efficacy but less toxicity than razoxane in the treatment of psoriasis. In an attempt to characterize further its mode of action it was administered both systemically and topically in the Malassezia ovalis animal model of psoriasis. Intravenous methotrexate and topical 0.1% betamethasone valerate were also used as positive control treatments. The animal model of psoriasis was effectively treated by bimolane, both systemically and topically, and also by parenteral methotrexate and topical betamethasone valerate. The time course of bimolane's effect with this model was different from methotrexate's suggesting the possibility of a different mode of action. Because bimolane, like razoxane, is an ethylene diamino tetraacetate acid (EDTA) derivative, it is possible that its effects on this reaction relate to its chelating properties and that inhibition of complement activation is important to its mode of action.

Iron oxidation chemistry in ferritin. Increasing Fe/O2 stoichiometry during core formation

The origin of previously observed variations in stoichiometry of iron oxidation during the oxidative deposition of iron in ferritin has been poorly understood. Knowledge of the stoichiometry of Fe(II) oxidation by O2 is essential to establishing the mechanism of iron core formation. In the present work, the amount of Fe(II) oxidized was measured by Mössbauer spectrometry and the O2 consumed by mass spectrometry. The number of protons produced in the reaction was measured by "pH stat" titration and hydrogen peroxide production by the effect of the enzyme catalase on the measured stoichiometry. For protein samples containing low levels of iron (24 Fe(II)/protein) the stoichiometry was found to be 1.95 +/- 0.18 Fe(II)/O2 with H2O2 being a product, viz. Equation 1. 2Fe2+ + O2 + 4H2O----2FeOOH + H2O2 + 4H+ (1) EPR spin trapping experiments showed no evidence of superoxide radical formation. The stoichiometry markedly increased with additional iron (240-960 Fe/protein), to a value of 4 Fe(II)/O2 as in Equation 2. 4Fe2+ + O2 + 6H2O----4FeOOH + 8H+ (2) As the iron core is progressively laid down, the mechanism of iron oxidation changes from a protein dominated process with H2O2 being the primary product of O2 reduction to a mineral surface dominated process where H2O is the primary product. These results emphasize the importance of the apoferritin shell in facilitating iron oxidation in the early stage of iron deposition prior to significant development of the polynuclear iron core.

Inhibition of cellular thymidylate synthesis by cytotoxic propenal derivatives of pyrimidine bases and deoxynucleosides

A series of cytotoxic propenal (3-oxoprop-1-enyl) derivatives of pyrimidine bases and deoxynucleosides was evaluated for their ability to block thymidylate synthesis in intact and permeabilized murine leukemia L1210 cells. Several were potent inhibitors of this process, likely contributing to their cytotoxicity. The IC50 values of thymidine-3-propenal, the prototype of this series, in intact and permeabilized L1210, L-M and L-M(TK-) cells were 21, 7.5, and 75 microM and 1.5, 1.7, and 3.5 microM, respectively. The related base analogue, thymine-1-propenal, is a product of bleomycin-induced DNA strand-scission; the results of the present study bear on the mode of action of this antibiotic.

Recent advances in pharmacologic study of natural anticancer agents in China

In this paper a number of anticancer agents of natural origin will be presented. Hydroxycamptothecin (HCPT) was found to produce a strong inhibitory action on a variety of animal tumors. It is also effective for treatment of patients with gastric carcinoma, liver carcinoma, tumor of head and neck or leukemia. Pharmacologic studies showed that it could depress S phase of tumor cells significantly and cause formation of cellular chromatid breaks. By means of alkaline elution and nick translation methods it has been proved that HCPT induced DNA single strand breaks remarkably. Homoharringtonine (HHRT) was shown to be effective against acute leukemia. Recent experiments in tumor-bearing mice indicated that (HHRT) could diminish tumor metastasis. Using molecular hybridization technique it was demonstrated that (HHRT) decreased the content of c-myc RNA in the cytoplasm but not in the nuclei. Lycobetaine (LBT) possessed strong inhibitory effects on a number of ascites tumors. In clinical trials it was effective against ovarian and gastric carcinomas. It is able to intercalate into DNA. Oxalysine (OXL) is a new antibiotic and shown to be effective against tumor metastatis. When used in combination with 5-FU, its anticancer action could be enhanced. Other natural compounds such as indirubin, beta-elemene, irisquinone, oridonine, norcantharidin and PSP have been also found to possess antitumor action.

Effects of lycobetaine on chromatin structure and activity of murine hepatoma cells

The effects of lycobetaine (LBT) on DNA single strand break and chromatin conformation were examined by in-situ nick translation method. It was found that LBT did not cause DNA single strand break. After 2-h incubation of murine hepatoma cells with 1-50 micrograms/ml LBT in vitro, the chromatin transcription activity was inhibited gradually. This effect was time- and dose-dependent. Actinomycin D produced a similar effect; 10-hydroxycamptothecin not only caused DNA single strand break, but also altered chromatin conformation; homoharringtonine had no marked influence on either. By molecular hybridization technique, it was found that the effect of LBT on individual genes was somewhat different. After 2-h incubation of the cells with LBT, the sensitivities of c-myc, N-ras, and beta 2-microglobulin genes to DNase I were decreased from 75 +/- 6, 66 +/- 4, 70 +/- 8% to 28 +/- 8, 25 +/- 5, 28 +/- 7%, respectively, while that of c-myb and beta-globin genes (8 + 6%, 6 + 5%) did not change obviously.

[Demonstration of the presence of Methanobrevibacter in a colon cancer Chinese patient]

A fecal specimen from a Chinese patient (85-year-old man) suffering from colonic cancer was examined for the presence of methane-producing bacteria. As a result, a Methanobrevibacter organism was isolated. Our isolate did not grow in the presence of bile salts, a result different from Methanobrevibacter from healthy Americans' feces by Miller et al.

[Modulation of norepinephrine release in sympathetic nerve endings in renal hypertensive dogs]

Experimental renal hypertensive and normal dogs with femoral arteries constantly perfused were studied. Cocaine was used to block the presynaptic norepinephrine (NE) reuptake and tyramine to initiate the release of NE in sympathetic nerve endings. NE spillover and infusion pressure were measured under basic conditions and during intraarterial infusion of cocaine, tyramine and in combination with alpha 1 and alpha 2 adrenoceptor antagonists. The extent of NE spillover increase induced by infusion of tyramine, the increased infusion pressure by cocaine and tyramine, and the reduced infusion pressure by prazosin were all greater in hypertensive dogs than those in normal dogs, but adrenoceptor antagonist idazoxan further increased tyramine-induced NE spillover in normal dogs only. It was suggested that reduced-regulation of presynaptic alpha 2 adrenoceptors to NE release and increased responsiveness of postsynaptic alpha 1 adrenoceptors to NE were present in hypertensive dogs.

[Analgesic and antipyretic effects of cyproheptadine]

Cyproheptadine-HCl raised the pain thresholds during hot plat test and writhing test in mice and tail flick test in rats, strengthened the hypnotic action by subthreshold dosage of sodium pentobarbital and chloral hydrate. The ED50 were 4.4 (3.2-5.7) and 12.4 (8.4-18.2) mg/kg 30 min after ip cyproheptadine in mice and rats, respectively. The ED50 was 0.14 (0.12-0.18) mg/kg 90 min after icv cyproheptadine in mice. Cyproheptadine po 20, 40 mg/kg and ip 10, 20 mg/kg showed significant antipyretic effects on yeast-induced pyrexia in rats.

[A new therapy of hemophilia with ranitidine]

20 cases of hemophilia, including ten of hemophilia A , nine of hemophilia B and one of von Willebrand's disease (VWD), were treated with ranitidine. The results revealed that the levels of both factor VIII and IX were increased and the clinical symptoms of bleeding were ameliorated. The level of factor VIII in hemophilia A ranged from 5.27 +/- 3.94% before treatment and rose to 14.68 +/- 4.70% during the treatment period (P less than 0.001). The level of the factor IX in the patients with hemophilia B increased from 4.42 +/- 3.01% before treatment to 20.33 + 9.31% under treatment (P less than 0.001). Tn the patient with VWD the level of the factor VIII rose but the level of von Willebrand factor did not change. The drug has no side effect. The results of our study suggests that ranitidine therapy is effective and safe in hemophilia.

Biological response modifier enhances the activity of natural killer cell against human cytomegalovirus-infected cells

Peripheral blood lymphocytes (PBL) from two human cytomegalovirus (CMV)-seronegative donors and eight CMV-seropositive donors were cultured for 3 days with or without the biological response modifier OK-432 and examined for lysis of K562 cells and CMV-infected MRC-5 cells. OK-432-stimulated PBL exhibited significantly greater natural killer (NK) activity than did unstimulated PBL. There was no difference in activity of NK cells in PBL prepared from CMV-seronegative and -seropositive donors. Antibody-complement depletion studies suggested that OK-432-stimulated NK activity was associated with Leu-7-positive cells. The ability of OK-432 to sustain the NK activity in PBL was decreased when the CD4-positive population of lymphocytes was eliminated by antibody-complement depletion prior to OK-432 stimulation. The ability of OK-432 to sustain the NK activity of PBL was also significantly decreased in the presence of monoclonal antibody against recombinant human interleukin-2. The results suggest that the activity of human NK cells against K562 and CMV-infected MRC-5 target cells can be sustained in vitro by OK-432-stimulated T-helper cells and that the effect of the T-helper cells is mediated, at least in part, by interleukin-2.

Characteristics of the interaction of lycobetaine with DNA

The characteristics of the interaction of lycobetaine (LBT) with DNA were examined by fluorescence spectrometer, disc electrophoresis and restriction enzyme analysis. The apparent binding constant of LBT with calf thymus DNA has been determined as 1.67 x 10(6) L/mol by ethidium bromide displacement method. Based on electrophoresis titration, the mode of DNA binding was found to be through intercalation. Fluorescence quenching assay showed that the intrinsic association constant and the binding site size of LBT to calf thymus DNA were 0.26 x 10(6) L/mol and 2.6 base pairs, respectively. Selective inhibition of LBT on action of some restriction enzymes showed that LBT intercalate preferentially into GC base pairs. Neither DNA strand break nor interstrand cross-link was produced by LBT. LBT did not bind to DNA covalently and did not cause DNA alkylation.

[Influence of zinc deprivation on thymus, spleen development and adenosine deaminase activity in young rats]

This study on the thymus and spleen development and ADA activity was done in young rats with zinc deprivation and supplementation. The serum zinc level, body weight, absolute and relative weight, and ADA activity of the thymus and spleen were compared between the experimental rats and the control group. Above indications were all decreased; especially both the thymus weight and the thymus ADA activity were markedly decreased in the zinc deficient group. The averages of thymic absolute weight, relative weight and ADA activity were dropped by 61.32%, 54.54% and 47.59%, respectively. After zinc supplementation for one month, all the body weight, weight of the thymus and spleen, and ADA activity of the spleen were recovered to the control group's level, while ADA activity of the thymus was 33.03% higher than that of the control group. Our data suggested that zinc was not only an important trace element in maintaining the growth of the body, the development of the thymus and spleen, but it may be an important agent to activate the ADA or to prompt synthesis of ADA.

Nephrotoxicity and hepatotoxicity of 1,1-dichloro-2,2-difluoroethylene in the rat. Indications for differential mechanisms of bioactivation

1,1-Dichloro-2,2-difluoroethylene (DCDFE) produced marked nephrotoxicity in rats upon an i.p. dose of 150 mumole/kg. At doses higher than 375 mumole/kg, DCDFE also produced hepatotoxicity. Aminooxyacetic acid, an inhibitor of cysteine conjugate beta-lyase, appeared to be slightly nephrotoxic in Wistar rats. Nevertheless it exerted an inhibitory effect on the nephrotoxicity of DCDFE. The N-acetylcysteine conjugate of DCDFE was identified as a major urinary metabolite of DCDFE. When administered as such, this conjugate appeared to be a potent nephrotoxin, without any effect on the liver, indicating that glutathione conjugation of DCDFE is most likely a bioactivation step for nephrotoxicity. The appearance of traces of chlorodifluoroacetic acid in urine of rats treated with higher doses of DCDFE indicates the existence of an oxidative pathway of metabolism of DCDFE, probably involving epoxidation by hepatic mixed-function oxidases. It is speculated that the latter route might account for the hepatotoxicity at higher doses of DCDFE. The nephro- and hepatotoxicity of DCDFE, therefore, most likely are the result of two different mechanisms of bioactivation.

[Transplantation model of human lung oat cell carcinoma in nude mice]

A human lung oat cell carcinoma from a surgical specimen was successfully transplanted into nude mice and has been maintained for over four years through 14 passages. This transplanted tumor had a long latent period of more than one month, slowly growing in the initial inoculation and the following passages. The interval between two passages was about four months. 5 months after the inoculation, the transplanted tumor in nude mice grew to 2 cm in diameter. It was demonstrated that the transplanted tumor possessed the human isoenzyme pattern and human chromosome karyotype. The original human tumor and its transplanted counterparts in the nude mice were strikingly similar by histopathology. Besides, specific neuro-secretory granules in cytoplasm of the transplanted tumor were observed under transmission electron microscope.

[Ultrastructural study on the model of human lung adenocarcinoma heterotransplanted to nude mice]

A human lung adenocarcinoma from surgical biopsy specimen was successfully heterotransplanted into nude mice and has been maintained for 40 generations. The experiments were made on 6-8 week old male or female nude mice with Swiss genetic background cultivated in specific pathogen-free condition. The electron microscopic observation on transplanted tumor of passages 2, 6, 12, 18 and 23 revealed that the ultrastructural features of this tumor were strictly maintained and no obvious change of differentiation was found. But there was a potential prone to regional squamous epithelial metaplasia in the transplanted tumor. The nude mice model of human lung adenocarcinoma so established can be used as a good experimental system of the homologous and reproducible human cancer for the study of basic medical sciences and chemotherapy of human lung carcinoma.

[Changes in protein in bile excretion from rat liver inoculated with BERH-2 hepatoma]

Rocket immunoelectrophoresis was used to assay the change in alpha fetoprotein (AFP) and albumin (Alb) in bile of rats 10 to 14 days after intrahepatic or intraperitoneal inoculation of BERH-2 hepatoma. The bile was collected from the common bile duct cannula. Total protein was determined by the Lowry method. The results showed that the excretion of total protein and Alb was reduced to 54% and 24% of the control in the intrahepatic group, and 65% and 56% of the control in the intraperitoneal group. Bile-AFP can be detected in rats in both groups and its concentration increased gradually during the tumor progression. In the hepatic group, the bile-AFP content per gram of tumor tissue was 29% of that in the intraperitoneal group. It suggests that decreased excretion of AFP, Alb and total protein in bile of rat bearing tumor in the liver be related to local obstruction of excretion by the tumor mass leading to constriction of biliary canaliculi.