Malignancy-associated vessel tortuosity: a computer-assisted, MR angiographic study of choroid plexus carcinoma in genetically engineered mice

BACKGROUND AND PURPOSE

The ability to assess tumor malignancy and monitor treatment response noninvasively would be of value to both clinicians and animal investigators. This report describes the MR imaging characteristics of a genetically engineered mouse model of choroid plexus carcinoma (CPC) during tumor growth and progression to malignancy. We assess the ability of vessel tortuosity measurements, as calculated from high-resolution MR angiographic (MRA) images, to detect emerging CPC cancers.

METHODS

MR images of 9 healthy mice and of 20 CPC mice with precancerous choroid dysplasia or with cancer over a wide range of sizes were analyzed. Two vessel tortuosity measures and a measure of vessel attenuation (vessel count) were calculated from MRA images. Malignancy assessment was based upon a statistical analysis of vessel tortuosity, by using an equation derived from an earlier study of human brain tumor patients.

RESULTS

Choroid dysplasia was correctly judged nonmalignant. On the basis of vessel count, neoangiogenesis could not be detected until cancers were full-blown and had reached a volume of approximately 80 mm3. Vessel tortuosity measurements, however, correctly identified emerging malignancy in lesions larger than 0.3 mm3.

CONCLUSION

To the best of our knowledge, this report provides the first description of in vivo, MR imaging characteristics of genetically engineered CPC mice during the progression from dysplasia to cancer. Vessel tortuosity measurements offer promise of correctly defining even tiny tumors as malignant.

Efficient semiparametric estimation of haplotype-disease associations in case-cohort and nested case-control studies

Estimating the effects of haplotypes on the age of onset of a disease is an important step toward the discovery of genes that influence complex human diseases. A haplotype is a specific sequence of nucleotides on the same chromosome of an individual and can only be measured indirectly through the genotype. We consider cohort studies which collect genotype data on a subset of cohort members through case-cohort or nested case-control sampling. We formulate the effects of haplotypes and possibly time-varying environmental variables on the age of onset through a broad class of semiparametric regression models. We construct appropriate nonparametric likelihoods, which involve both finite- and infinite-dimensional parameters. The corresponding nonparametric maximum likelihood estimators are shown to be consistent, asymptotically normal, and asymptotically efficient. Consistent variance-covariance estimators are provided, and efficient and reliable numerical algorithms are developed. Simulation studies demonstrate that the asymptotic approximations are accurate in practical settings and that case-cohort and nested case-control designs are highly cost-effective. An application to a major cardiovascular study is provided.

Maximum likelihood estimation of haplotype effects and haplotype-environment interactions in association studies

The associations between haplotypes and disease phenotypes offer valuable clues about the genetic determinants of complex diseases. It is highly challenging to make statistical inferences about these associations because of the unknown gametic phase in genotype data. We describe a general likelihood-based approach to inferring haplotype-disease associations in studies of unrelated individuals. We consider all possible phenotypes (including disease indicator, quantitative trait, and potentially censored age at onset of disease) and all commonly used study designs (including cross-sectional, case-control, cohort, nested case-control, and case-cohort). The effects of haplotypes on phenotype are characterized by appropriate regression models, which allow various genetic mechanisms and gene-environment interactions. We present the likelihood functions for all study designs and disease phenotypes under Hardy-Weinberg disequilibrium. The corresponding maximum likelihood estimators are approximately unbiased, normally distributed, and statistically efficient. We provide simple and efficient numerical algorithms to calculate the maximum likelihood estimators and their variances, and implement these algorithms in a freely available computer program. Extensive simulation studies demonstrate that the proposed methods perform well in realistic situations. An application to the Carolina Breast Cancer Study reveals significant haplotype effects and haplotype-smoking interactions in the development of breast cancer.

Effect of salbutamol on nasal symptoms and mast cell degranulation induced by adenosine 5' monophosphate nasal challenge

BACKGROUND

In addition to its well-known functional agonism at the level of beta(2) adrenergic receptors on airways smooth muscle cells, salbutamol appears to have additional protective effects, possibly through an inhibition of mast cell activation.

OBJECTIVE

The aim of this study is to provide the first evidence in vivo of inhibition of human mast cell activation by salbutamol.

METHODS

Nine atopic subjects received placebo and salbutamol (5 mg/mL) 15 min before an adenosine 5' monophosphate (AMP) nasal provocation in a double-blind crossover study design. The nasal lavage was collected from these subjects prior to or 3, 5, 15 or 30 min after the AMP nasal challenge, and concentrations of histamine and tryptase in the nasal lavage were measured.

RESULTS

AMP nasal provocation produced considerable sneezing and induced a transient increase in histamine and tryptase release with peak values achieved at 3 min after the challenge in all the subjects studied. Compared with placebo, salbutamol significantly attenuated the release of histamine and tryptase induced by AMP challenge (P=0.048 and 0.020, respectively). Moreover, the AMP-induced sneezing was also inhibited by pre-treatment with salbutamol (P=0.004).

CONCLUSIONS

Intranasal salbutamol attenuates nasal symptoms and inhibits histamine and tryptase release caused by AMP nasal provocation thus supporting the hypothesis that salbutamol may play an additional protective role in the airways by inhibiting mast cell activation.

Estimating haplotype-disease associations with pooled genotype data

The genetic dissection of complex human diseases requires large-scale association studies which explore the population associations between genetic variants and disease phenotypes. DNA pooling can substantially reduce the cost of genotyping assays in these studies, and thus enables one to examine a large number of genetic variants on a large number of subjects. The availability of pooled genotype data instead of individual data poses considerable challenges in the statistical inference, especially in the haplotype-based analysis because of increased phase uncertainty. Here we present a general likelihood-based approach to making inferences about haplotype-disease associations based on possibly pooled DNA data. We consider cohort and case-control studies of unrelated subjects, and allow arbitrary and unequal pool sizes. The phenotype can be discrete or continuous, univariate or multivariate. The effects of haplotypes on disease phenotypes are formulated through flexible regression models, which allow a variety of genetic hypotheses and gene-environment interactions. We construct appropriate likelihood functions for various designs and phenotypes, accommodating Hardy-Weinberg disequilibrium. The corresponding maximum likelihood estimators are approximately unbiased, normally distributed, and statistically efficient. We develop simple and efficient numerical algorithms for calculating the maximum likelihood estimators and their variances, and implement these algorithms in a freely available computer program. We assess the performance of the proposed methods through simulation studies, and provide an application to the Finland-United States Investigation of NIDDM Genetics Study. The results show that DNA pooling is highly efficient in studying haplotype-disease associations. As a by-product, this work provides valid and efficient methods for estimating haplotype-disease associations with unpooled DNA samples.

A major lung cancer susceptibility locus maps to chromosome 6q23-25

Lung cancer is a major cause of death in the United States and other countries. The risk of lung cancer is greatly increased by cigarette smoking and by certain occupational exposures, but familial factors also clearly play a major role. To identify susceptibility genes for familial lung cancer, we conducted a genomewide linkage analysis of 52 extended pedigrees ascertained through probands with lung cancer who had several first-degree relatives with the same disease. Multipoint linkage analysis, under a simple autosomal dominant model, of all 52 families with three or more individuals affected by lung, throat, or laryngeal cancer, yielded a maximum heterogeneity LOD score (HLOD) of 2.79 at 155 cM on chromosome 6q (marker D6S2436). A subset of 38 pedigrees with four or more affected individuals yielded a multipoint HLOD of 3.47 at 155 cM. Analysis of a further subset of 23 multigenerational pedigrees with five or more affected individuals yielded a multipoint HLOD score of 4.26 at the same position. The 14 families with only three affected relatives yielded negative LOD scores in this region. A predivided samples test for heterogeneity comparing the LOD scores from the 23 multigenerational families with those from the remaining families was significant (P=.007). The 1-HLOD multipoint support interval from the multigenerational families extends from C6S1848 at 146 cM to 164 cM near D6S1035, overlapping a genomic region that is deleted in sporadic lung cancers as well as numerous other cancer types. Parametric linkage and variance-components analysis that incorporated effects of age and personal smoking also supported linkage in this region, but with somewhat diminished support. These results localize a major susceptibility locus influencing lung cancer risk to 6q23-25.

Reduction in preretinal neovascularization by ribozymes that cleave the A2B adenosine receptor mRNA

Adenosine modulates a variety of cellular functions by interacting with specific cell surface G protein-coupled receptors (A1, A2A, A2B, and A3) and is a potential mediator of angiogenesis through the A2B receptor. The lack of a potent, selective A2B receptor inhibitor has hampered its characterization. Our goal was to design a hammerhead ribozyme that would specifically cleave the A2B receptor mRNA and examine its effect on retinal angiogenesis. Ribozymes specific for the mouse and human A2B receptor mRNAs were designed and cloned in expression plasmids. Human embryonic kidney (HEK) 293 cells were transfected with these plasmids and A2B receptor mRNA levels were determined by quantitative real-time RT-PCR. Human retinal endothelial cells (HRECs) were also transfected and cell migration was examined. The effects of these ribozymes on the levels of preretinal neovascularization were determined using a neonatal mouse model of oxygen-induced retinopathy (OIR). We produced a ribozyme with a Vmax of 515+/-125 pmol/min and a Kcat of 36.1+/-8.3 min(-1) (P< or =1x10(-5)). Transfection of HEK293 cells with the plasmid expressing the ribozyme reduced A2B receptor mRNA levels by 45+/-4.8% (P=5.1x10(-5)). Transfection of HRECs reduced NECA-stimulated migration of cells by 47.3+/-1.2% (P=7x10(-4)). Intraocular injection of the constructs into the mouse model reduced preretinal neovascularization by 53.5+/-8.2% (P=4.5x10(-5)). Our results suggest that the A2B receptor ribozyme will provide a tool for the selective inhibition of this receptor and provide further support for the role of A2B receptor in retinal angiogenesis.

Inhibition of human mast cell activation with the novel selective adenosine A(2B) receptor antagonist 3-isobutyl-8-pyrrolidinoxanthine (IPDX)(2)

The antiasthmatic drug enprofylline was the first known selective, though not potent, A(2B) antagonist. On the basis of structure-activity relationships (SARs) of xanthine derivatives, we designed a novel selective adenosine A(2B) receptor antagonist, 3-isobutyl-8-pyrrolidinoxanthine (IPDX), with potency greater than that of enprofylline. IPDX displaced [3H]ZM241385 ([3H]4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a]-[1,3,5]triazin-5-ylamino]ethyl)phenol) from human A(2B) adenosine receptors with a K(i) value of 470 +/- 2 nM and inhibited A(2B)-dependent cyclic AMP (cAMP) accumulation in human erythroleukemia (HEL) cells with a K(B) value of 625 +/- 71 nM. We found that IPDX was more selective than enprofylline toward human A(2B) receptors. It was 38-, 55-, and 82-fold more selective for human A(2B) than for human A(1) (K(i) value of 24 +/- 8 microM), human A(2A) (K(B) value of 36 +/- 8 microM), and human A(3) (K(i) value of 53 +/- 10 microM) adenosine receptors, respectively. IPDX inhibited NECA (5'-N-ethylcarboxamidoadenosine)-induced interleukin-8 secretion in human mast cells (HMC-1) with a potency close to that determined for A(2B)-mediated cAMP accumulation in HEL cells, thus confirming the role of A(2B) adenosine receptors in mediating human mast cell activation. Since adenosine triggers bronchoconstriction in asthmatic patients through human mast cell activation, IPDX may become a basis for the development of new antiasthmatic drugs with improved properties compared with those of enprofylline. Our data demonstrate that IPDX can be used as a tool to differentiate between A(2B) and other adenosine receptor-mediated responses.

Predominance of NK1.1+TCR alpha beta+ or DX5+TCR alpha beta+ T cells in mice conditioned with fractionated lymphoid irradiation protects against graft-versus-host disease: "natural suppressor" cells

We developed a nonmyeloablative host conditioning regimen in a mouse model of MHC-mismatched bone marrow transplantation that not only reduces radiation toxicity, but also protects against graft-vs-host disease. The regimen of fractionated irradiation directed to the lymphoid tissues and depletive anti-T cell Abs results in a marked change in the residual host T cells, such that NK1.1+ or DX5+asialo-GM1+ T cells become the predominant T cell subset in the lymphoid tissues of C57BL/6 and BALB/c mice, respectively. The latter "natural suppressor" T cells protect hosts from graft-vs-host disease after the infusion of allogeneic bone marrow and peripheral blood cells that ordinarily kill hosts conditioned with sublethal or lethal total body irradiation. Protected hosts become stable mixed chimeras, but fail to show the early expansion and infiltration of donor T cells in the gut, liver, and blood associated with host tissue injury. Cytokine secretion and adoptive transfer studies using wild-type and IL-4(-/-) mice showed that protection afforded by NK1.1+ and DX5+asialo-GM1+ T cells derived from either donors or hosts conditioned with lymphoid irradiation is dependent on their secretion of high levels of IL-4.

Clonable progenitors committed to the T lymphocyte lineage in the mouse bone marrow; use of an extrathymic pathway

We searched for clonable committed T cell progenitors in the adult mouse bone marrow and isolated rare (approximately 0.05%) cells with the Thy-1hiCD2-CD16+CD44hiCD25-Lin- phenotype. In vivo experiments showed that these cells were progenitors committed only to reconstituting the T cell lineage of irradiated Ly5 congenic hosts. Reconstitution of the thymus was minimal compared with that of the bone marrow, spleen, and lymph nodes. At limiting dilutions, donor T cell reconstitution of the spleen frequently occurred without detectable donor cells in the thymus. Progenitors were capable of rapidly reconstituting athymic hosts. In conclusion, the clonable bone marrow progenitors were capable of T cell reconstitution predominantly by means of an extrathymic pathway.

Allogeneic bone marrow cells that facilitate complete chimerism and eliminate tumor cells express both CD8 and T-cell antigen receptor–αβ

Nonmyeloablative host conditioning regimens have been used in clinical allogeneic bone marrow and hematopoietic progenitor transplantation to effectively treat lymphohematopoietic tumors and reduce early toxicity. However, severe graft-versus-host disease (GVHD) remains a major problem. The goal of the current study was to determine whether specific subsets of cells in allogeneic bone marrow transplants can effectively treat the BCL1 B-cell lymphoma in nonmyeloablated BALB/c mouse hosts given a single dose of sublethal (450 cGy) total body irradiation, without inducing severe GVHD. The experimental results show that high doses of whole bone marrow cells from major histocompatiblity complex (MHC)-mismatched donors eliminate both normal and malignant host-type lymphohematopoietic cells without causing injury to nonlymphohematopoietic host tissues. The CD8+T-cell antigen receptor–αβ+(TCRαβ+) T cells within the marrow transplants mediated the killing of the tumor cells via both perforin- and FasL-dependent pathways. Cells present in marrow transplants from either CD8−/− or TCRα−/− donors failed to eliminate malignant and normal host lymphohematopoietic cells. Addition of small numbers of blood mononuclear cells to the marrow inoculum caused lethal GVHD. Thus, the resident allogeneic bone marrow CD8+ TCRαβ+ T cells had the unique capacity to eliminate the host lymphohematopoietic cells without nonlymphohematopoietic tissue injury.

[Studies on the isolation, culture and DNA identification of mycelia of Tricholoma matsutake]

The tissue isolation for Tricholom matsutake(S Ito et Imai) Sing were made with 8 media in 810 test tubes from different positions of 9 basidiocarps of different source and from mycorrhizae, and soil with the fungi in the studies. The results showed that 94 test tubes of slow-growing mycelia were isolated from lamellae and their success percentages of isolation with media PDAS, PDAW, BM, PDA were 74.4%, 355%, 15.6% and 8.9% respectively. The fast-growing mycelia were easily got from the mycorrhizae and soil related to matsutake. The isolates with different culture characteristics were appraised through DNA fingerprinting comparison with matsutake basidiocarps collected from Jilin province, China and reference isolates presented by matsutake research workers of China and Japan, in which RAPD (Random Amplified Polymorphic DNA)-PCR patterns were sharply prepared using 17 arbitrary decamer nucleotide primers screened. The statistical data indicated that all slow-growing mycelia isolated from lamellae had the same DNA fingerprinting patterns as their origin basidiocarps tissues such as pileus (containing lamellae) and stipe, whose similarity coeffecients all were 1.000, and were therefore identified as true Tricholoma matsutake. However, the fast-growing mycelia or yeast colony were identified as not matsutake. The results suggested that matsutake and its own mycelia have DNA homogeneity, and there exists no any other microbe in the basidiocarps. The results also demonstrated that all matsutake from east China and reference isolates of matsutake from southwest China and Japan were one same species Tricholoma matsutake, whose DNA similarity coeffecients varied from 0.934 to 0.994.

[The modified process for preparing natural organic polymer flocculant chitosan]

The modified process for preparing chitosan from crab or lobster shells was developed. In the decalcification stage, 10% HCl was used as soaking solution with addition of a small quantity of A as a promoter, and the mass ratio of reactants was 10% HCl:A:crab or lobster shells = 3.5:0.5:1, continuously stirring the crab or lobster shells at 30 degrees C for 3 h in place of simply soaking the crab or lobster shells at room temperature for 16-24 h in the previous process. In the deacetylation stage, 40% NaOH solution was used with addition of a small quantity of B as a promoter, and the mass ratio of reactants was 40% NaOH:B:chitin = 4:0.2:1, keeping reaction at 105 degrees C for 2 h in place of at 115 degrees C for 6 h in the previous process. By this new process, the cost of the raw materials used for preparing chitosan was cut down 49%, the preparation time was shortened by one half, and the main properties of this chitosan such as viscosity, deacetylation and molecular weight all approached or exceeded those of the Sigma' commercial chitosan (Chitosan C-3646).

[Ecological study on relationship between desertification process and vegetation dynamics in west of northeast China: vegetation classification]

Based on the data obtained from 72 plant community plots and 276 plant species in Hulunbeier Sandy Land and Kerqin Sandy Land in the northeast desertification region of China, TWINSPAN analysis was carried out. Meanwhile the practical classification result was obtained by Detrended correspondence Analysis (DCA). Under the vegetation classification principles of China, the vegetation classification system of the desertification regions in northeast China was preliminarily established, which includes 6 vegetation types, 11 subtypes, 40 formations, and 55 associations.

Cutting edge: a role for CD1 in the pathogenesis of lupus in NZB/NZW mice

Since anti-CD1 TCR transgenic T cells can activate syngeneic B cells via CD1 to secrete IgM and IgG and induce lupus in BALB/c mice, we studied the role of CD1 in the pathogenesis of lupus in NZB/NZW mice. Approximately 20% of B cells from the spleens of NZB/NZW mice expressed high levels of CD1 (CD1high B cells). The latter subset spontaneously produced large amounts of IgM anti-dsDNA Abs in vitro that was up to 25-fold higher than that of residual CD1int/low B cells. T cells in the NZB/NZW spleen proliferated vigorously to the CD1-transfected A20 B cell line, but not to the parent line. Treatment of NZB/NZW mice with anti-CD1 mAbs ameliorated the development of lupus. These results suggest that the CD1high B cells and their progeny are a major source of autoantibody production, and activation of B cells via CD1 may play an important role in the pathogenesis of lupus.

PG27, an extract of Tripterygium wilfordii hook f, induces antigen-specific tolerance in bone marrow transplantation in mice

PG27, an active fraction purified from an extract of a Chinese herb, Tripterygium wilfordii hook f, was used to prevent graft-versus-host disease (GVHD) in a murine model. Lethally irradiated BALB/c (H-2(d)) recipients of B10.D2 (H-2(d)) donor grafts were given daily intraperitoneal injections of PG27 (40 mg/kg per day) for the first 35 days after transplantation. Control mice were given daily injections of solvent vehicle (Ethanol and Cremophor EL). All the control recipients (15/15) died of GVHD within 90 days, but all the recipients given prophylactic treatment with PG27 (15/15) survived beyond 100 days without any signs of GVHD. Furthermore, the GVHD-free recipients were used as donors, and their bone marrow and spleen cells were transplanted into lethally irradiated normal BALB/c (same party) or lethally irradiated normal C3H (H-2(k), third party) mice. Although 10 of 10 same-party recipients survived more than 100 days without any signs of GVHD, 10 of 10 third-party C3H recipients died of GVHD within 40 days. Further studies of PG27 in the murine BCL1 leukemia/lymphoma model demonstrated that animals treated with PG27 partially retained the graft-versus-leukemia (GVL) effect of the graft without GVHD. These results suggest that treatment with PG27 induces host-specific tolerance and retains the GVL effect of allogeneic marrow grafts. (Blood. 2000;95:705-710)

Heterogeneity of NK1.1+ T cells in the bone marrow: divergence from the thymus

NK1.1+ T cells in the mouse thymus and bone marrow were compared because some marrow NK1.1+ T cells have been reported to be extrathymically derived. Almost all NK1.1+ T cells in the thymus were depleted in the CD1-/-, beta2m-/-, and Jalpha281-/- mice as compared with wild-type mice. CD8+NK1.1+ T cells were not clearly detected, even in the wild-type mice. In bone marrow from the wild-type mice, CD8+NK1.1+ T cells were easily detected, about twice as numerous as CD4+NK1.1+ T cells, and were similar in number to CD4-CD8-NK1.1+ T cells. All three marrow NK1.1+ T cell subsets were reduced about 4-fold in CD1-/- mice. No reduction was observed in CD8+NK1.1+ T cells in the bone marrow of Jalpha281-/- mice, but marrow CD8+NK1.1+ T cells were markedly depleted in beta2m-/- mice. All NK1.1+ T cell subsets in the marrow of wild-type mice produced high levels of IFN-gamma, IL-4, and IL-10. Although the numbers of marrow CD4-CD8-NK1.1+ T cells in beta2m-/- and Jalpha281-/- mice were similar to those in wild-type mice, these cells had a Th1-like pattern (high IFN-gamma, and low IL-4 and IL-10). In conclusion, the large majority of NK1.1+ T cells in the bone marrow are CD1 dependent. Marrow NK1.1+ T cells include CD8+, Valpha14-Jalpha281-, and beta2m-independent subsets that are not clearly detected in the thymus.

[The effects of Xuezhikang on neointimal proliferation and C-myc gene expression after angioplasty in rabbits]

OBJECTIVE

To investigate the effects of Xuezhikang (XZhK) on the neointimal proliferation and C-myc gene expression after angioplasty in rabbits.

METHODS

Angioplasty for atherosclerotic stenosis of celiac arteries was performed in 30 male white rabbits after being fed with cholesterol-supplemented diet for 8 weeks, which were then randomized to control group, high-cholesterol group and XZhK group. After 4 weeks, the local vessels were collected for morphological observation. C-myc mRNA level was measured with RT-PCR and C-myc protein with immunohistochemical analysis.

RESULTS

Morphological observation showed that the neointimal area in the XZhK group were less than the control group (P < 0.05), and that in control group were less than that in the high-cholesterol group (P < 0.05). The levels of C-myc mRNA measured with RT-PCR and the percentage of C-myc protein positive cell by immunohistochemical analysis were lower in the XZhK group than in the control and high-cholesterol group (P < 0.05), The levels in the latter two groups showed no difference (P > 0.05).

CONCLUSION

XZhK can inhibit the neointimal proliferation and the expression of C-myc gene after angioplasty in rabbits.

cDNA cloning and sequence analysis of hepatitis G virus genome isolated from a Chinese blood donor

OBJECTIVE

To obtain full-length sequence of a Chinese hepatitis G virus (HGV) strain (HGVch) and investigate the genetic characteristic of HGVch and its identity to other isolates.

METHODS

Reverse transcription (RT) and nested-PCR were used to screen HGV RNA positive serum and amplify cDNA fragments. A positive serum without known hepatitis virus markers was selected for isolating HGV RNA template. The HGV genome was divided into 12 overlapping fragments and directly cloned into pGEM-T vector. Sequences were determined by dideoxy terminus-end method of DNA sequencing and then analyzed by computer.

RESULTS

The twelve fragments of HGVch cover 9213 nucleotides in length, containing a large open reading frame (ORF) encoding 2873 animo acids polyprotein that began with a methonine residue and ended at termination codon. HGVch is about 86.5%-89.5% identical to other known HGV isolates at the nucleotide level and about 93.9%-96.2% at the deduced animo acid level.

CONCLUSION

HGV is a non-A-E hepatitis causal agent, proved to be related with posttransfusion hepatitis in all over the world. Chinese HGV isolate has very close relationship to other isolates from Africa, Europe, Japan, without significant difference across the entire genome. It is suggested that the sequences of HGV isolates are very conservative and the evolution is very slow.