Assessment of temporal biochemical and gene transcription changes in rat liver cytochrome P450: utility of real-time quantitative RT-PCR

PURPOSE

A conventional approach to assess cytochrome P450 (CYP) induction in preclinical animal models involves daily dosing for a least a week followed by Western blot and/or enzyme activity analysis. To evaluate the potential benefit of a third more specific and sensitive assay, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), with the objective of reducing the duration of the conventional 1-week study, we simultaneously assessed gene expression by qRT-PCR along with Western blots and enzyme activity assays as a time course in an in vivo model.

METHODS

Rats were dosed daily for 8 days with model inducers of CYP1A, CYP2B, CYP3A, or CYP4A. Liver P450 levels were measured after 0.5, 1, 2, 4, and 8 days of dosing by qRT-PCR, Western blot, and enzyme activity.

RESULTS

CYP1A, CYP3A, and CYP4A genes were maximally induced very rapidly (0.5-1 day), whereas the CYP2B gene was maximally induced after a lag time of 4 days. In all cases, fold changes in induction detected by qRT-PCR were greater than fold changes in protein levels and enzyme activities.

CONCLUSIONS

Maximal persistent and larger fold changes observed by qRT-PCR either preceded or occurred simultaneously with maximal sustained fold changes in protein levels as measured by Western blots and enzyme activity assays. Our data show that qRT-PCR provides increased sensitivity and specificity over conventional assays and may be key information for reliable assessment of drug-related changes in CYP induction during the transition from discovery to toxicology studies.

Present-day crustal deformation in China constrained by global positioning system measurements

Global Positioning System (GPS) measurements in China indicate that crustal shortening accommodates most of India's penetration into Eurasia. Deformation within the Tibetan Plateau and its margins, the Himalaya, the Altyn Tagh, and the Qilian Shan, absorbs more than 90% of the relative motion between the Indian and Eurasian plates. Internal shortening of the Tibetan plateau itself accounts for more than one-third of the total convergence. However, the Tibetan plateau south of the Kunlun and Ganzi-Mani faults is moving eastward relative to both India and Eurasia. This movement is accommodated through rotation of material around the eastern Syntaxis. The North China and South China blocks, east of the Tibetan Plateau, move coherently east-southeastward at rates of 2 to 8 millimeters per year and 6 to 11 millimeters per year, respectively, with respect to the stable Eurasia.

Normal and malignant prostate epithelial cells differ in their response to hepatocyte growth factor/scatter factor

Hepatocyte growth factor/scatter factor (HGF/SF) promotes the proliferation, differentiation, motility, and invasion of epithelial cells by binding to its cell surface receptor, the Met tyrosine kinase. In the prostate, Met is expressed predominantly by prostate epithelial cells (PrEC), whereas HGF/SF is synthesized by prostate stromal cells (PrSC). Met is also expressed in localized and metastatic prostate cancers. Our results show that PrECs in in vitro culture maintain expression of Met at a level comparable to DU145 cancer cell expression. HGF/SF secreted by PrSC stimulates tyrosine phosphorylation of the Met receptor. In normal PrEC, HGF/SF causes growth inhibition, sustained phosphorylation of mitogen-activated protein kinase, and increased CK18 expression consistent with cell differentiation. In contrast, HGF/SF significantly stimulates the proliferation of DU145 prostate cancer cells. HGF/SF in the conditioned medium of PrSC specifically induces migration of both normal and malignant prostate epithelial cells through MatriGel-coated Transwell filters. HGF/SF depletion reduces cell migration by approximately 50%. The response of PrEC is specific for HGF/SF since the other growth factors tested do not significantly affect growth or migration of PrECs. These results support the in vivo importance of the prostate stroma and specifically of HGF/SF as a unique stromal derived factor in the development and progression of prostate cancer.

Molecular analysis of estrogen induction of preproenkephalin gene expression and its modulation by thyroid hormones

Estrogen receptors (ER) and thyroid hormone receptors (TR) are ligand-dependent nuclear transcription factors. Estrogen-induced preproenkephalin (PPE) gene expression in the hypothalamus is directly related to estrogen-induced lordosis behavior in the rat. In the present study, we showed that the PPE mRNA level in the ventromedial hypothalamus of female rats was significantly decreased by ovariectomy. This decrease was reversed by estrogen replacement in a dose- and time-dependent manner. Using transient transfection and electrophoretic mobility shift assays (EMSA), functional estrogen response elements (ERE) were identified between -437 and -145 base pairs (bp) of the rat PPE gene promoter region. Two ERE-like elements are present between -405 and -364 of the rat PPE gene promoter, which bind ERalpha as demonstrated by EMSA. Estrogen produced a dose-dependent increase in CAT activity in cotransfection assays with ERalpha expression vector and a 437PPE-CAT reporter construct containing 437 bp of the rat PPE gene promoter and the CAT reporter gene. This estrogen-induced PPE promoter activity was inhibited by liganded-TR in transient cotransfection assays. Analysis of DNA-protein interactions by EMSA revealed that both ERalpha and TR (alpha1 and beta1) could bind to the EREs in the rat PPE gene promoter. Furthermore, estrogen induction of PPE mRNA in the ventromedial hypothalamus of the ovariectomized female rat was significantly attenuated by concomitant administration of triiodothyronine. These results suggest that estrogen regulation of the hypothalamic PPE gene expression is mediated through an estrogen-receptor complex directly interacting with the functional EREs in its promoter region; and that this estrogen effect can be modified by thyroid hormones.

Conditional and targeted overexpression of vascular chymase causes hypertension in transgenic mice

We cloned a rat vascular chymase (RVCH) from smooth muscle cells (SMCs) that converts angiotensin I to II and is up-regulated in SMC from spontaneously hypertensive vs. normotensive rats. To determine whether increased activity of RVCH is sufficient to cause hypertension, transgenic mice were generated with targeted conditional expression of RVCH to SMC, with the use of the tetracycline-controlled transactivator (tTA). We confirmed conditional expression of RVCH by mRNA, protein, and chymase activity in the absence, but not in the presence, of dietary doxycycline. The systolic blood pressure (mmHg), measured by carotid artery cannulation at 10-12 weeks of age, was higher in tTA+/RVCH+ mice than in nonbinary transgenic littermates (136 +/- 4 vs. 109 +/- 3) (P < 0.05), as were the diastolic and mean pressures. Hypertension was completely reversed by doxycycline, suggesting a causal link with chymase expression. Medial thickening of mesenteric arteries from tTA+/RVCH+ mice vs. littermates (0.82 +/- 0.1 vs. 0.42 +/- 0.02) (P < 0.05) was associated with increased SMC proliferation, as judged by positive immunoreactivity, with the use of an antibody to the proliferating cell nuclear antigen. These structural changes were prevented by doxycycline. Perfusion myography of mesenteric arteries from tTA+/RVCH+ mice also revealed increased vasoconstriction in response to phenylephrine and impaired metacholine-induced vasodilatation when compared with littermate controls or with the doxycyline-treated group. Our studies suggest that up-regulation of this vascular chymase is sufficient to cause a hypertensive arteriopathy, and that RVCH may be a candidate gene and a therapeutic target in patients with high blood pressure.

[The protein expression of Bcl-x1 and Bcl-2 in eosinophils in nasal polyps and the influence of beclomethasone dipropionate on the expression]

OBJECTIVE

To investigate the protein expression of B-cell lymphoma/leukemia-2(Bcl-2) and B-cell lymphoma/leukemia-x long(Bcl-x1) in eosinophils in nasal polyps and the influence of beclomethasone dipropionate on the expression.

METHODS

Using May-Grünwald-Giemsa (MGG) method and immunohistochemical method, the protein expression of Bcl-x1 and Bcl-2 in eosinophils in nasal polyps from patients treated with beclomethasone dipropionate treatment and patients without any treatment was compared.

RESULTS

(1) Nasal polyp tissues from patients without treatment had more eosinophils than those from patients with treatment(P < 0.01). (2) No protein expression of Bcl-2 was observed in all 52 patients. (3) 20.0% patients with treatment had the expression of Bcl-x1, whereas 48.1% patients without treatment had the expression. The difference between these two groups was significant(P < 0.05).

CONCLUSION

These data suggest that Bcl-x1 may act as an anti-apoptotic molecule in eosinophils and corticosteroids induce eosinophil apoptosis through suppressing the expression of Bcl-x1.

[Comprehensive assessment on environmental quality in vulnerable ecotone of Tarim River Basin]

Tarim River Basin (TRB) is one of ecological environment vulnerable areas. Due to the matching of material and energy existed in some problems, the different fragility characteristics occurred obviously. According to related principles of ecological environment quality assessment, combined with ecological environment situation of Tarim River Basin, 20 indexes were selected, and the indicator system for synthetically ecological environment assessment was built. Moreover, ecological fragility index was set up, which can be used to indicate the degree of ecological environment quality in Tarim River Basin. The results were as follows: Aksu River Basin belongs to improved area. Yerkart River Basin and the upper reaches of TRB belongs to balance areas and Hetian River Basin and the middle reaches of TRB belongs to maladjustment areas. The lower reaches of TRB belongs to severe damage area. The assessment results are consonant with actual situation, which play an important function in ecological environment construction.

[The recognition of the epidemic area of tsutsugamushi disease on Nan Peng Lie Island in China and the strategy of prevention]

OBJECTIVE

To investigate the region for the epidemic area of tsutsugamushi disease.

METHODS

Epidemiological studies, Orientia tsutsugamushi isolation, and preventive measures were used.

RESULTS

The region belonged to epidemic area of south subtropical zone. The main host was found Rattus norvegicu. The main biological vector was Leptotrombidium deliens. The seasonal trends of the quantity of Rattus norvegicu and Leptotrombidium deliens were consistent with the incidence change of the disease in the region. Orientia tsutsugamushi has been isolated from Rattus norvegicu and Leptotrombidium deliens. Data showed that Orientia tsutsugamushi isolated strains mainly belongs to Karp. Sero-epidemiological data showed that antibodies of Orientia tsutsugamushi are 100.0% positive in the residents of the region and 4.0% in army men. After taking comprehensive preventive measures, the incidence was descending.

CONCLUSION

Nan Peng Lie island was proved an epidemic area of tsutsugamushi disease.

[Construction and expression of HLA-DRalpha, DRB1*0401 transgenic mice model]

OBJECTIVE

To construct transgenic mice model on DR alpha and DRB1*0401 of human MHC-II molecules.

METHODS

By microinjection techniques on germ nucleus of zygotes, DRalpha and DRB1*0401 genes were injected into zygotes of C57BL/6 x DBA/1 hybrid mice and transplanted into the oviducts of pseudopregnancy female mice. The integration and expression of exogenous genes in offspring were detected by PCR, Southern blot and Northern blot, RT-PCR analysis.

RESULTS

There were 5 founders of all injected mice, which had steadily inherited to the fifth generation. It was found that 95 mice were positive by PCR and 68 mice were integrated exogenous gene by Southern blot analysis. DRalpha and DRB1*0401 genes were expressed on spleen and kidney of transgenic mice.

CONCLUSION

This experiment on the construction of DRalpha and DRB1*0401 transgenic mice model is a success.

[The value of nasal endoscopy in the resection of upper and posterior nasal septum deviation]

OBJECTIVE

In order to find a safe, reliable and satisfying technique to treat the upper and posterior nasal septum deviation.

METHOD

Performing the resection of the upper and posterior nasal septum deviation under nasal endoscopy, comparing this new method with the traditional one and discussing the safety and long-term curative effect of this new method.

RESULT

The observation of the outcome of 109 patients undergoing this operation after 1-50 months postoperation shows that this technique can resect the upper and posterior deviation safely and completely, improve the nasal respiratory and olfactory function and reduce the occurrence of nasal cavity adhesion and the recurrence of nasal polyp and sinusitis.

CONCLUSION

Performing the resection of the upper and posterior nasal septum deviation under nasal endoscopy is a good method for popularizing to clinician.

Immobilization and characterization of beta-galactosidase from the plant gram chicken bean (Cicer arietinum). Evolution of its enzymatic actions in the hydrolysis of lactose

beta-Galactosidase (beta-D-galactosidase galactohydrolase, EC 3.2.1. 23) isolated and purified from gram chicken bean was immobilized on cross-linked polyacrylamide gel. The activity yield was high and attained up to 72%. Compared with the free enzyme, the immobilized enzyme had a wider operational pH range and better thermal stability. Lyophilized pieces exhibited good stability when stored at room temperature for 60 days and a favorable operational stability when used eight times repeatedly without loss of enzymatic activity under the same conditions. Kinetic data (K(m), V(m), and E(a)) for the free and the immobilized enzymes were determined using O-nitrophenyl-beta-D-galactoside (ONPG) and lactose as substrates. The result of time courses of hydrolysis of lactose showed that beta-galactosidase from the plant gram chicken bean would have a promising application in the hydrolysis of lactose in milk.

[Microwave therapy of radiotherapeutical choanal atresia under nasal endoscope]

OBJECTIVE

In order to know efficacy of microwave to treat the secondary choanal atresia under nasal endoscope.

METHOD

Three patients suffering from membranous choanal atresia due to radiotherapy of nasopharyngeal carcinoma (NPC) were treated by microwave under nasal endoscope.

RESULT

Satisfing recoveries were accomplished in all patients and no relapse was found within the 7-13 months' follow-up.

CONCLUSION

This method has many advantages, such as: processing available under local anesthesia without incision, mild damage to normal tissues, clear operation visual field, less hemorrhage and postoperative pain, complete coagulation and gasification of atresic membrane, no need of postoperative dilation and stable therapeutical effect.

Expression of ICAM-1, B7.1 and TPO on human thyrocytes induced by IFN-alpha

OBJECTIVE

To detect expression of intercellular adhesion molecule-1 (ICAM-1), B7.1 and thyroid peroxidase (TPO) on thyrocyte and study the possible mechanism of interferon-alpha (IFN-alpha) in the pathogenesis of autoimmune thyroid disease (AITD).

METHODS

Thyrocytes were cultured from 6 normal persons. Antigen expression on thyrocytes induced by cytokines was examined using immunofluorescence staining with flow cytometer.

RESULTS

IFN-alpha significantly stimulated the expression of ICAM-1, B7.1 and TPO, as compared with those of control group. IFN-gamma markedly enhanced the expression of HLA-DR and ICAM-1, but not B7.1. Prolactin (PRL) resulted in increased expression of ICAM-1, B7.1, as well as overexpression of TPO, which is more significant than that stimulated by IFN-alpha.

CONCLUSIONS

Thyroid autoimmunity induced by IFN-alpha is associated with the expression of ICAM-1, B7.1 and TPO. IFN-gamma could not induce the expression of B7.1, therefore it is not an initiator in AITD. In addition, we should pay more attention to PRL which possibly plays an important role in the initiation and perpetuation of postpartum thyroiditis.

Characterization of experimental Cryptosporidium parvum infection in IFN-gamma knockout mice

Severe cryptosporidial infections were produced in gamma interferon (IFN-gamma) knockout mice. Mean oocyst shedding increased from 332 to 30,717 oocysts/100 microliters of faecal suspension between day 4 and 9 after administration of 1 x 10(5) oocysts/mouse. No significant differences in oocyst shedding were observed in mice after being inoculated with 1 x 10(5), 1 x 10(4) or 1 x 10(3) oocysts/mouse (P > 0.05). Infected mouse weights decreased an average 3-4 g before death or euthanization. Histological studies revealed heavy parasite colonization in small intestinal epithelium (approximately 250 organisms/high-power field at x 400). Mesenteric lymph nodes in infected mice were markedly enlarged compared to controls (P < 0.05). Both CD4+ and CD8+ T cell populations increased in spleens of infected mice while the B cell population increased in mesenteric lymph nodes from infected mice. No significant proliferation was observed when pooled lymphocytes from infected mice were exposed to C. parvum antigens in vitro. Addition of recombinant mouse IFN-gamma did not restore antigen responsiveness. While lymphoproliferative responses to specific antigen were not significant in the short period following infection, this mouse model provides unique features to study the characteristics of acute infection and the immune response against C. parvum.

Susceptibility differences to Cryptosporidium parvum infection in two strains of gamma interferon knockout mice

Differences in susceptibility to cryptosporidial infections were investigated between 2 strains of gamma interferon knockout (GKO) mice. Male C57BL/6J-Ifg and BALB/c-Ifg (GKO) mice, ages 8-10 wk, were inoculated with infectious oocysts at various doses. C57BL/6J-Ifg mice developed overwhelming infections and died 9-12 days after infection. Low inoculum doses (1 x 10(3)) did not increase the survival time significantly. The infection intensity in C57BL/6J-Ifg mice inoculated with 1 x 10(5) oocysts/mouse increased markedly on day 4 postinfection (PI) and continued to increase significantly over the next 6-7 days. Most of the C57BL/6J-Ifg mice exceeded 15% weight loss and died by day 10 PI. In contrast, BALB/c-Ifg mice developed moderate infections from which they recovered. The average parasite load in the BALB/c-Ifg mice was 100 times lower than in C57BL/6J-Ifg mice. Mice survived until termination of the experiment (39 days) even when 1 x 10(6) oocysts per mouse were used for inoculation. BALB/c-Ifg mice did not exhibit significant weight loss (or difference in stool consistency). These 2 mouse strains make excellent models for studying differences in recovering and nonrecovering immune mechanisms.

[A study on activity of beta-glucuronidase in serum and secretion from upper respiratory tract in patients with head and neck malignant tumors]

Beta-glucuronidase (beta-GD) activity in serum and upper respiratory tract (URT) secretion in patients with head and neck malignant tumors (HNMT) was studied. Subjects included 40 HNMT patients, 40 healthy volunteers and 40 patients with benign tumors of the head and neck region. The results showed that there was no statistically significant difference of serum beta-GD level among the three groups. The same was true for URT secretion between the normal control and benign tumor groups. beta-GD level in URT secretion was higher in HNMT group than in other groups (P < 0.001). Using healthy subjects' average beta-GD level plus two standard difference as positive standard, the sensitivity, reliability and specificity of the test were 85.0%, 92.5% and 100% respectively. beta-GD levels were higher in patients with advanced tumors and metastases. One year follow-ups of six patients showed that beta-GD level change in URT secretion was in accordance with clinical manifestations. These results suggest that assay of beta-GD level in URT secretion can be used as a valuable supplimental parameter in early diagnosis of HNMTs, their clinical staging, evaluation of therapeutic effectiveness and detection of recurrence and metastases. In addition, this method has the advantage of easy, prompt, result specificity, sensitivity and reliability.

In-vitro activities of paromomycin and lasalocid evaluated in combination against Cryptosporidium parvum

Using a chemiluminescence immunoassay, paromomycin and lasalocid were shown to inhibit Cryptosporidium parvum growth in Madin-Darby canine kidney cells in a concentration-dependent manner. The median effective concentrations (EC50s) for paromomycin and lasalocid were 1184 mg/L and 0.4 mg/L, respectively. Neither drug was cytotoxic to host cells at concentrations up to five times their EC50s. Drug combination studies were conducted and the resulting data were analysed by the median-effect principle and combination index method. Statistically significant synergy was observed when combinations of paromomycin and lasalocid were used at ratios of 5000:1 and 2500:1. A possible mechanism for synergy is discussed.

[Microwave operation of angiofibroma of nasopharynx under nasal endoscope]

Two patients with angiofibroma of nasopharynx were treated with microwave operation under nasal endoscope in our hospital. This operation could reduce the amount of blood less than operations by palatine apporach and nose apporach apprentently. So the blood transplantation was avoid. Meanwhile, it lessen somatopsychic pain and ecnomical burden. Because of the clean and clear operation field under nasal endoscope, the tumor could be removed completely and correctly. Then, the possibility of relapse was reduced.

[The association of HLA-DR4 gene subtypes with Vogt-Koyanagi-Harada syndrome]

OBJECTIVE

To investigate the association of HLA-DR4 subtypes with Vogt-Koyanagi-Harada (VKH) syndrome and to clarify immune genetic mechanism underlying the susceptibility/resistance to VKH syndrome.

METHODS

HLA-DR4 alleles of 54 patients with VKH and 106 healthy controls were amplified and subtyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

A selective amplification of the DR4 alleles of 263 bp was higher in patients with VKH than in the controls. The frequency of DR4-DRB1 alleles was 70% (38/54) in VKH group and was 19% (20/106) in the control group, relative rish (RR) = 10.21, P < 0.005. The genotyping of DR4 alleles showed that DRB1 * 0405 was more frequent in VKH group (35/38, 92%) than in the control group [6/20, 30%, RR = 27.2, P = 0.0,000,017, corrected pvalue (Pc) = 0.0,000,103].

CONCLUSIONS

It is suggested that DRB1 * 0405 be a susceptible subtype to VKH and the specific amino acid residue Ser (serine) at position 57 play an important role in the development of VKH syndrome. The molecular biological technique we used may be useful in studying the immunogenetic mechanism of VKH.

Interactions of a subassembly of the herpes simplex virus type 1 helicase-primase with DNA

The UL5, UL8, and UL52 genes of herpes simplex virus type 1 encode a multisubunit assembly that possesses primase, DNA helicase, and DNA-dependent nucleoside triphosphatase activities. A subassembly consisting of the UL5 and UL52 gene products retains these activities. The nucleoside triphosphatase activity of the UL5/UL52 subassembly is strongly stimulated by both homo- and heteropolymeric single-stranded DNA. Double-stranded DNA has little ability to stimulate the ATPase activity. The subassembly binds both double and single-stranded DNA. Nucleotides are not required for DNA-binding. The minimum length of single-stranded DNA that is bound and that stimulates enzymatic activity is about 12 nucleotides. The kinetic parameters of the ATPase activity of the subassembly are affected by the length of the oligonucleotide coeffector. The Km decreases as the coeffector length is increased up to a length of about 20 nucleotides and then remains independent of coeffector length. The first order rate constant for ATPase activity exhibits a quasihyperbolic dependence on the length of the DNA coeffector and is maximal for coeffectors of 20 nucleotides and longer.

The glutathione S-transferase M1 (GSTM1) null genotype and benzidine-associated bladder cancer, urine mutagenicity, and exfoliated urothelial cell DNA adducts

Multiple studies in the general population have suggested that subjects with the glutathione S-transferase M1 (GSTM1)-null genotype, who lack functional GSTM1, are at higher risk for bladder cancer. To evaluate the impact of the GSTM1-null genotype on bladder cancer caused by occupational exposure to benzidine and to determine its influence on benzidine metabolism, we carried out three complementary investigations: a case-control study of bladder cancer among workers previously exposed to benzidine in China, a cross-sectional study of urothelial cell DNA adducts and urinary mutagenicity in workers currently exposed to benzidine in India, and a laboratory study of the ability of human GSTM1 to conjugate benzidine and its known metabolites in vitro. There was no overall increase in bladder cancer risk for the GSTM1-null genotype among 38 bladder cancer cases and 43 controls (odds ratio, 1.0; 95% confidence interval, 0.4-2.7), although there was some indication that highly exposed workers with the GSTM1-null genotype were at greater risk of bladder cancer compared to similarly exposed workers without this allele. However, the GSTM1 genotype had no impact on urothelial cell DNA adduct and urinary mutagenicity levels in workers currently exposed to benzidine. Furthermore, human GSTM1 did not conjugate benzidine or its metabolites. These results led us to conclude that the GSTM1-null genotype does not have an impact on bladder cancer caused by benzidine, providing a contrast to its association with elevated bladder cancer risk in the general population.

A chemiluminescence immunoassay for evaluation of Cryptosporidium parvum growth in vitro

A chemiluminescence immunoassay (CLIA) was developed to detect Cryptosporidium parvum growth in Madin-Darby canine kidney (MDCK) cell cultures. Optimal results were obtained when MDCK cells were plated at a density of 1 x 10(4) cells/well (96-well plate) and maintained as a monolayer for 4 days prior to infection with 2 x 10(4) parasites/well. Two compounds (paromomycin and maduramicin) were evaluated and shown to have selective activity against C. parvum in a dose-dependent manner. There was excellent correlation between CLIA and immunofluorescence assay when assessing anti-C. parvum agents in MDCK cells. CLIA offers advantages over conventional enzyme-linked immunosorbent assay and immunofluorescence assay methods in that it is more sensitive and efficient. The combination of CLIA and MDCK culture provides an efficient tool for evaluating potential anti-cryptosporidial compounds prior to testing in animal models.

In vitro anticryptosporidial activity of dinitroaniline herbicides

Despite the evaluation of over 100 antimicrobial drugs, the diarrheal disease cryptosporidiosis has remained refractory to treatment. We report the evaluation of five dinitroaniline herbicides including trifluralin, profluralin, nitralin, pendimethalin, and fluchloralin for anticryptosporidial activity in an in vitro cultivation model of Cryptosporidium parvum. All five compounds exhibited significant anticryptosporidial activities with no corresponding evidence of toxicity. The most active compound was pendimethalin with an IC50 of 0.19 microM while nitralin was the least active with an IC50 of 4.5 microM. These compounds should be evaluated further in an animal model of cryptosporidiosis.

An animal study on transmission of hepatitis B virus through mosquitoes

Three gena of mosquitoes were fed with human blood infected with hepatitis B virus (HBV) artificially. When blood in the stomach was completely digested, mosquitoes were used to bite monkeys Tupaia Belangeri. A month after biting, venous blood samples were taken from the monkeys to detect serum HBsAg, HBeAg, Anti-HBs and Anti-HBc. Among 29 test monkeys, 9 were HBV infective serum markers positive. In 4 of 16 test monkey liver biopsies, acute inflammatory changes were found with Hematoxylin-Eosine staining. In the hepatic cells, HBsAg and HBcAg were detected by immunohistochemical double-labeling assays, and HBV-DNA was also positive by in situ hybridization in monkey liver sections. These results provided an evidence for the possibility of transmission of HBV through mosquitoes and suggest its epidemiological significance in mosquito infested areas.

Effect of Corticosteroids on Rabbit Corneal Keratocytes After Photorefractive Keratectomy

BACKGROUND

To determine the corticosteroid effect on the activity and repopulation of keratocytes after photorefractive keratectomy (PRK).

METHODS

A 193-nm excimer laser (VISX Twenty/Twenty) created a central ablation depth of 22 microns (diameter:5 nm) on 22 corneas of 16 albino rabbits. Two ablated eyes were examined 6 hours following PRK. Twelve eyes received no postoperative corticosteroids and eight were treated with topical fluoromethalone for 3 months. Corneas were examined 1, 3, 6, and 12 months after PRK by immunofluorescence and transmission electron microscopy.

RESULTS

Corticosteroids reduced haze (p=0.02), but all corneas (treated or untreated) cleared 6 months after PRK. Keratocytes were absent from the anterior 100 microns of the stroma 6 hours after PRK. However, the number and activity of keratocytes were significantly greater in this area in untreated corneas at 1 month and then gradually decreased. By 6 and 12 months, the number of keratocytes approached controls. Treated corneas had fewer keratocytes than either controls or untreated eyes (p<0.01) and by 3 months, a subepithelial acellular zone of 30 to 50 microns thickness appeared and persisted until at last 12 months after PRK.

CONCLUSIONS

Corticosteroids have a transient effect in reducing haze and seem to inhibit keratocyte movement, leading to an acellular subepithelial region beneath the ablated area.

Evaluation of maduramicin and alborixin in a SCID mouse model of chronic cryptosporidiosis

Two polyether ionophores, maduramicin and alborixin, were evaluated for anticryptosporidial activity in a severe combined immune deficient (SCID) mouse model of cryptosporidiosis. Groups of SCID mice were inoculated with 10(6) oocysts of bovine origin by oral gavage. Maduramicin or alborixin was administered beginning 4 weeks postinfection at 3 mg/kg of body weight per day. Maduramicin treatment resulted in a 96% reduction in fecal parasite load over the 3-week treatment period (P < 0.003). This reduction correlated with decreases in tissue parasite loads observed in histological sections of the small intestine (P < 0.000002) and the colon (P < 0.000006). A significant decrease in oocyst shedding was also observed after a 3-week treatment with alborixin (71% reduction, P < 0.01). Maduramicin was also evaluated in a relapsing model of cryptosporidiosis in which the infection was observed to recur after treatments were discontinued. Some toxicity, as demonstrated by weight loss, was observed with both maduramicin and alborixin. Both drugs exhibited significant anticryptosporidial activities with concomitant moderate toxicity. These polyether ionophores should be valuable as positive controls in compound evaluation studies and as lead compounds for chemical optimization (modification).

[An analysis of the uneven prevalence of tuberculosis in various areas and regions in China]

This article analyzed the uneven prevalence of tuberculosis in various areas and regions and its trend in China nowadays based on the data of the nationwide epidemiological sampling survey of tuberculosis in 1979 and 1990. The highest prevalence was 25-30 times higher than the lowest among provinces, municipalities and regions. The prevalence in remote areas and regions was significantly higher than that in coastal areas and municipalities. The ratios of the prevalence of pulmonary tuberculosis between cities and countryside were 1:2.4-2.8. Most of the investigation points which had a higher prevalence was located in remote and inland areas. Some minority areas which had higher prevalence resided in the northwest and southwest remote areas. The uneven tuberculosis prevalence in various areas and regions indicated that tuberculosis is still an important public health problem in China at present.

Protection of carbon tetrachloride hepatotoxicity by cinchona alkaloids

Elevated serum enzymes were observed due to all four cinchona alkaloids in male Sprague-Dawley rats after four day treatment. Only a slight effect on bile flow and excretion of phenolphthalein glucuronide in bile was noted. Animals treated with cinchona alkaloid for four days and then receiving CCl4 showed a partial protection against CCl4 induced hepatotoxicity. The levels of serum enzymes were lowered as compared to animals treated with CCl4 alone. Bile flow and excretion of phenolphthalein glucuronide in bile showed a trend of restoration towards control levels. All four cinchona alkaloids probably inhibit microsomal enzymes, thereby, inhibiting the bioactivation of CCl4 and hence reducing the toxicity.

Infection dynamics and clinical features of cryptosporidiosis in SCID mice

Cryptosporidial infections in severe combined immune deficient (SCID) mice produce a chronic disease state which in the later stages leads to extraintestinal involvement and hepatic dysfunction. To further characterize the infection dynamics in this model and monitor the changes in the hepatic system, a dose titration of the oocyst inoculum was performed and alkaline phosphatase levels in the sera were assayed. Ten SCID mice per dose were inoculated with 10(3), 10(4), 10(5), 10(6), or 10(7) oocysts. Oocyst shedding in the feces was quantified by microscopic enumeration. Mice inoculated with 10(6) oocysts and those inoculated with 10(7) oocysts demonstrated similar oocyst shedding patterns, but the 10(7)-oocyst group exhibited signs of distress (e.g., weight loss and icterus) earlier. The intensity of the infection increased markedly approximately 14 days postinoculation (p.i.) and continued to increase steadily over the next 6 weeks. Inoculation with lower oocyst doses produced a delay in patency (e.g., it occurred 7 days later with the 10(5)-oocyst inoculum and 14 days later with the 10(4)-oocyst inoculum). Mean serum alkaline phosphatase levels in the 10(7)-oocyst group were more than twice control values at 5 weeks p.i. and continued to increase over the next 8 weeks. Oocyst doses and alkaline phosphatase levels were positively correlated with hepatobiliary colonization (r = 0.71) and liver necrosis (r = 0.65) at 13 weeks p.i. A strong positive correlation between hepatobiliary colonization and liver necrosis at 13 weeks p.i. (r = 0.87) was observed.

Correlation between N-acetyltransferase activity and NAT2 genotype in Chinese males

Eighty-four healthy Chinese male control subjects derived from an occupation-based case-control study of bladder cancer were evaluated for hepatic N-acetyltransferase activity by dapsone and for NAT2 genotype using allele-specific amplification of peripheral leukocyte DNA by the polymerase chain reaction. Fifty-nine percent of the overall variation in acetylation activity was explained by genotype (p < 0.0001). The remaining variation in acetylation was not associated with dapsone N-hydroxylation activity, age, current smoking status, or weight in the study population, or within any genotype subgroup. Although acetylation activity in the homozygous mutant group did not overlap with the other genotype categories, there was moderate overlap in acetylation between the heterozygous mutant and wildtype groups, and substantial variation in acetylation within them. Considering all subjects with the identical NAT2 genotype as phenotypically similar and all subjects with differing NAT2 genotypes as phenotypically distinct may result in misclassification of metabolic risk factors in epidemiological investigations. As such, it would seem prudent, where possible, to collect both acetylation phenotype and NAT2 genotype data, since the advantages and limitations of these two sources of information complement, and serve to assess the accuracy of each other.

N-acetylation phenotype and genotype and risk of bladder cancer in benzidine-exposed workers

Several studies in subjects occupationally exposed to arylamine carcinogens have shown increased risks for bladder cancer associated with the slow acetylator phenotype. To follow up these reports, a case-control study of N-acetylation and bladder cancer risk was carried out among subjects occupationally exposed to benzidine, in benzidine dye production and use facilities in China. Thirty-eight bladder cancer cases and 43 controls from these factories were included for study of acetylation phenotype, by dapsone administration, and for polymorphisms in the NAT2 gene, by a polymerase chain reaction (PCR)-based test. In contrast to previous studies, no increase in bladder cancer risk was found for the slow N-acetylation phenotype (OR = 0.3; 95% CI = 0.1-1.3) or for slow N-acetylation-associated double mutations in NAT2 (OR = 0.5; 95% CI = 0.1-1.8). Examination of specific mutations and adjustment for age, weight, city and tobacco use did not alter the results. When examined by level of benzidine exposure in the cases, the bladder cancer risks associated with low (OR = 0.3, 95% CI = 0.0-2.2), medium (OR = 0.7, 95% CI = 0.1-4.5) and high (OR = 0.6, 95% CI = 0.1-3.5) exposure showed no interaction between genotype and benzidine exposure, within the range of exposures experienced by subjects in this study. This study, which is the first to incorporate phenotypic and genotypic analyses, provides evidence that the NAT2-related slow N-acetylation polymorphism is not associated with an increased risk of bladder cancer in workers exposed to benzidine, and may have a protective effect.

Mortality and incidence of bladder cancer in benzidine-exposed workers in China

We examined bladder cancer mortality and incidence to 1981 in 1,972 workers employed in benzidine-exposed jobs in Tianjin, Shanghai, and Jilin, China, between 1972 and 1977, and in 1,974 unexposed workers employed during the same time period. In comparison to general population rates, in the benzidine-exposed group the ratio of observed to expected deaths (SMR) was 17.5 (95% C.I.: 7.5-34.5) and the ratio of observed to expected incident cases (SIR) was 25.0 (95% C.I.: 16.9-35.7). No excess was noted in the unexposed group. The 25-fold increase in bladder cancer incidence in the exposed group was related to level of exposure, with the SIR rising from 4.8 for low exposure to 36.2 for medium exposure, and 158.4 for high exposure. Risks were elevated both for producers of benzidine (SIR = 45.7; 95% C.I.: 20.9-86.8) and for users (SIR = 20.9; 95% C.I.: 12.9-32.0) of benzidine dyes. Benzidine-exposed workers who smoked tobacco had a 31-fold risk (95% C.I.: 20.4-46.4), while non-smoking workers had an 11-fold risk (95% C.I.: 3.6-25.8), suggestive of a multiplicative relationship between these two carcinogens.