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Biomedical subjects

V Godfrey

Publications and source records attributed to V Godfrey.

13 recordsLinked to original sources
PubMed2006

Evaluation of dosing regimen of respirable rifampicin biodegradable microspheres in the treatment of tuberculosis in the guinea pig.

OBJECTIVES: The efficacy of rifampicin-loaded polymeric microspheres (RPLGA) delivered to guinea pigs infected with Mycobacterium tuberculosis (H37Rv) was compared with a daily dose of nebulized rifampicin suspension. METHODS: Aerosol-infected animals were subjected to multiple dose or single dose treatment with RPLGA, PLGA microspheres or micronized rifampicin suspension aerosols. For comparison with treatment with suspensions of microspheres, additional groups received daily doses of rifampicin-only suspensions for 20 (20-RIF) and 10 (10-RIF) days. RESULTS: Drug and polymer treated multiple dose groups exhibited significantly lower wet lung weights than untreated animals. Spleen wet weights and viable bacterial counts (VBCs) were much lower for drug microsphere treated animals than for all other groups. In multiple dose studies with rifampicin-only suspensions, wet lung weights for 10-RIF and 20-RIF treated animals were much smaller than controls. Likewise, wet spleen weights of 10-RIF and 20-RIF treated animals were much smaller than controls, consistent with reduced inflammation. Spleen VBC of 20-RIF treated animals was much smaller than controls. No statistical differences were observed in the lung VBC among single dose groups. However, a trend similar to that of the wet weights was observed. CONCLUSIONS: Aerosolized RPLGA reduced most measures of tuberculosis (TB) infection. These studies are further evidence for the potential of inhaled aerosol therapy for the treatment of TB. However, additional studies are required to elucidate underlying mechanisms of action and optimize this route of drug delivery.

Administration, Inhalation↗
PubMed2001

Impact of ionizing radiation and genetic background on mammary tumorigenesis in p53-deficient mice.

Loss of p53 function is known to compromise cell cycle regulation, inductionof apoptosis, and DNA damage repair and can facilitate neoplastic transformation of cells. Mutations in the p53 gene are identified frequently in breast carcinomas. Li-Fraumeni patients inheriting a mutant p53 allele have an increased risk for developing tumors including breast cancer. Although mouse lines carrying mutations in the p53 gene have been generated, they die primarily of lymphoma and thus to date provide a limited model for the study of this disease and the role of p53 in nonfamilial breast cancer. An increasing body of literature suggests that the incidence of various tumors is determined largely by the genetic background on which mutations are studied. In addition, population studies and studies in animals suggest that environmental factors, together with genetic factors, determine overall risk for development of specific types of tumors. We therefore examined the impact of genetic background together with exposure to ionizing radiation on the development of tumors, particularly mammary tumors, in p53-deficient animals. We report here that modifier alleles present in the BALB/c strain increase the incidence of hemangiosarcomas [15 of 53 (28.3%); P = 0.0007] in p53(-/-) mice above rates reported previously in p53(-/-) mice on a mixed background as compared to the incidence observed in DBA/p53(-/-) mice. However, no increase in the frequency of mammary tumors is seen in these mice or in p53(-/-) DBA/2 animals, nor was an increase in mammary tumors observed in the DBA/2 p53(+/-) mice, even after exposure to 5 Gy of whole-body ionizing radiation. In contrast, a significant increase in the incidence of mammary tumors was observed in similarly treated BALB/c p53(+/-) mice (37.3% versus 6.8%; P = 0.0007). This was accompanied by a comparable decrease in the incidence of lymphomas. These results show that environmental agents together with genetic factors can increase the frequency and decrease the latency of mammary tumors, leading to an incidence similar to that observed in Li-Fraumeni syndrome. Furthermore, it suggests that the risk of development of a particular type of tumor by individuals deficient in p53 after exposure to damaging agents can be influenced by modifier alleles.

Alleles↗
PubMed1999

Growth retardation, DNA repair defects, and lack of spermatogenesis in BRCA1-deficient mice.

BRCA1 is a nuclear phosphoprotein expressed in a broad spectrum of tissues during cell division. The inheritance of a mutant BRCA1 allele dramatically increases a woman's lifetime risk for developing both breast and ovarian cancers. A number of mouse lines carrying mutations in the Brca1 gene have been generated, and mice homozygous for these mutations generally die before day 10 of embryonic development. We report here the survival of a small number of mice homozygous for mutations in both the p53 and Brca1 genes. The survival of these mice is likely due to additional unknown mutations or epigenetic effects. Analysis of the Brca1(-/-) p53(-/-) animals indicates that BRCA1 is not required for the development of most organ systems. However, these mice are growth retarded, males are infertile due to meiotic failure, and the mammary gland of the female mouse is underdeveloped. Growth deficiency due to loss of BRCA1 was more thoroughly examined in an analysis of primary fibroblast lines obtained from these animals. Like p53(-/-) fibroblasts, Brca1(-/-) p53(-/-) cells proliferate more rapidly than wild-type cells; however, a high level of cellular death in these cultures results in reduced overall growth rates in comparison to p53(-/-) fibroblasts. Brca1(-/-) p53(-/-) fibroblasts are also defective in transcription-coupled repair and display increased sensitivity to DNA-damaging agents. We show, however, that after continued culture, and perhaps accelerated by the loss of BRCA1 repair functions, populations of Brca1(-/-) p53(-/-) fibroblasts with increased growth rates can be isolated. The increased survival of BRCA1-deficient fibroblasts in the absence of p53, and with the subsequent accumulation of additional growth-promoting changes, may mimic the events that occur during malignant transformation of BRCA1-deficient epithelia.

Animals↗
PubMed1999

Mammary tumor formation in p53- and BRCA1-deficient mice.

The inheritance of a mutant copy of the BRCA1 gene greatly increases a woman's lifetime risk for ovarian and breast cancer. While a homologous gene has been identified in mouse, mice carrying mutations in this gene do not display a detectable increase in tumor formation. To determine whether mutations in p53 might increase the incidence of tumors associated with the loss of BRCA1 function in mice, we have generated mice carrying mutations at both of these loci. We report here that the presence of a mutant Brca1 allele does not alter survival of either p53-/- or p53+/- mice. Although the tumor spectrum was not dramatically altered, an increased incidence of mammary tumors was observed in the Brca1+/-p53-/- mice. Four mammary tumors were seen in the Brca1+/-p53-/- group whereas only one such tumor was seen among the p53-/- control group. In addition, although the presence of a mutant Brca1 allele did not alter the survival rate or the incidence of most tumor types in the p53+/- mice, 5 of the 23 tumors isolated from the Brca1+/-p53+/- mice treated with ionizing radiation were of mammary epithelial origin, and 3 of these had lost expression of the wild-type Brca1 gene. In contrast, no such tumors were observed in the irradiated p53+/- controls. Although the number of mammary tumors observed in these animals is small, these results are suggestive of a role for BRCA1 in mammary tumor formation after exposure to specific DNA damaging agents.

Animals↗
PubMed1998

Expression of the Epstein-Barr virus latent membrane protein 1 induces B cell lymphoma in transgenic mice.

The latent membrane protein 1 (LMP1) of the Epstein-Barr virus has transforming properties in rodent fibroblasts and is expressed in most of the cancers associated with Epstein-Barr virus (EBV) infection including posttransplant lymphomas, Hodgkin's disease, nasopharyngeal carcinoma, and AIDS-related lymphomas. In this study, three lineages of LMP1 transgenic mice were established with LMP1 expressed under the control of the Ig heavy chain promoter and enhancer. Lymphoma developed in all three lineages, and the incidence of lymphoma increased significantly with age with lymphomas developing in 42% of transgenic mice over 18 months. The expression of LMP1 was detected at high levels in the lymphoma tissues but only at trace levels in normal lymphoid tissues. Gene rearrangement of the Ig heavy chain indicated monoclonality or oligoclonality in all lymphomas, some of the lymphoid hyperplastic spleens, and some histologically normal spleens. These data reveal that LMP1, without the expression of other EBV genes, is oncogenic in vivo and indicate that LMP1 is a major contributing factor to the development of EBV-associated lymphomas.

Animals↗
PubMed1998

Immunological and pathological consequences of mutations in both Fas and Fas ligand.

The lpr mutation in mice results in premature termination of transcription of the gene encoding the apoptosis-signaling receptor Fas. As a result, lpr mice develop severe lymphoproliferation and lupus-like autoantibodies. Growing evidence suggests that the lpr mutation is "leaky" and that low levels of Fas are expressed in lpr mice. To determine if Fas expressed in lpr mice is contributing to apoptosis we generated a novel strain of mice (B6/lprgld) which is homozygous for both the lpr mutation and the gld mutation which encodes nonfunctional Fas ligand (FasL) protein. If low levels of Fas in B6/lpr mice contribute to apoptosis and lessen the severity of disease, the B6/lprgld mice, which also lack functional FasL, would be expected to develop a more severe form of disease than B6/lpr mice. Our results revealed no significant increase in either lymphoproliferation or autoimmunity in B6/lprgld mice compared to B6/lpr or B6/gld mice. Additionally, no increase in surface expression of Fas was detected by flow cytometry on B6/lprgld lymphocytes compared to B6/lpr lymphocytes. However, histological examination of B6/lprgld liver revealed a marked increase in lymphocytic infiltration, compared to livers of B6/lpr and B6/gld mice. Our results suggest that, while low levels of Fas in lpr mice may not be contributing to amelioration of lymphoproliferation or autoimmunity, they may be partially protecting the liver from abnormalities which arise in the absence of Fas-mediated apoptosis.

Animals↗
PubMed1997

Mutations in the murine fitness 1 gene result in defective hematopoiesis.

Identification and characterization of mutations that disrupt normal hematopoiesis are essential for understanding the genetic pathways that control the development and regulation of the mammalian hematopoietic system. Previously, the fitness 1 gene was identified by five, independent mutations in N-ethyl-N-nitrosourea (ENU) saturation mutagenesis experiments within the albino (c) region of mouse chromosome 7 (MMU7). We report here that fit1 mutants are anemic, display numerous peripheral blood defects, and are deficient in early hematopoietic progenitor cell populations. The number of both erythroid and myeloid progenitors, as well as B cells, are reduced. These results implicate fit1 involvement in normal hematopoiesis and suggest that further characterization of the fit1 gene, and the five presumed point mutations of the gene, will lead to an improved understanding of normal hematopoiesis in the mouse.

Animals↗
PubMed1996

Disease in the scurfy (sf) mouse is associated with overexpression of cytokine genes.

The murine X-linked lymphoproliferative disease scurfy is similar to the Wiskott-Aldrich syndrome in humans. Disease in scurfy (sf) mice is mediated by CD4+ T cells. Based on similarities in scurfy mice and transgenic mice that overexpress specific cytokine genes, we evaluated the expression of cytokines in the lesions of sf mice by Northern blotting, quantitative reverse-transcription polymerase chain reaction (RT-PCR) and by hybridization in situ. Overall, the phenotypic characteristics of scurfy disease correlated well with increased interleukin (IL)-4 (lymphadenopathy), IL-6 (B cell proliferation, hypergammaglobulinemia), IL-7 (dermal inflammatory cell infiltration), and high levels of tumor necrosis factor-alpha (wasting).

Animals↗
PubMed1992

The beta 4 subunit of the integrin family is displayed on a restricted subset of endothelium in mice.

More than 15 subunits of the integrin family of cell surface adhesion molecules have been identified. The alpha 6 beta 4 integrin has recently been identified as a component of hemidesmosomes of stratified squamous epithelium. The monoclonal antibody (mAb) 346-11A binds to the beta 4 subunit in mice. Sequence analysis of a cDNA clone coding for this epitope localizes reaction of the mAb to a portion about half way through the extracellular domain at the beginning of the cysteine-rich region. Sites of beta 4 expression in mice were detected by autoradiographic analysis of tissues collected from mice 24 or 48 h after intravenous injection of 125I-labeled mAb 346-11A. This non-quantitative technique emphasizes detection of antigen exposed in the vascular space. These data show that in addition to the epithelia of several organs, the endothelia of intermediate vessels throughout the body are sites of beta 4 expression. In particular, endothelium of larger vessels but not capillaries in lung, vessels in thymus, spleen and Peyer's patches, and portal vessels but not the central veins of the liver, are positive. The expression of the beta 4 integrin in blood vessels may indicate a specialized function for beta 4 at these sites that is distinct from its role in hemidesmosome-mediated attachment.

Animals↗
PubMed1992

Two-dimensional polyacrylamide gel electrophoretic characterization of proteins from organs of C3H mice expressing the scurfy (sf) genetic mutation during early and late stages of disease progression.

Scurfy (sf), is an X-linked recessive lethal mutation that occurs spontaneously in the C3H mouse. The disease is characterized by lymphoid and hematopoietic dysfunction. Affected males are of small stature and exhibit scaliness and crusting of the eyelids, ears, tail, and feet, marked splenomegaly, moderate hepatomegaly, enlarged lymph nodes, and atrophy of the thymus. The average lifespan of the affected hemizygous males (sf/y) is 24 +/- 0.7 days. Total cellular proteins were extracted from pooled samples of thymus and spleen obtained from combined litters of mice. Tissue-specific protein profiles characteristic of either sf mutant or normal mice were analyzed by two dimensional polyacrylamide gel electrophoresis (2DPAGE) at different stages of the phenotypic expression of the sf mutation, to identify changes in protein patterns that might be associated with the progression of the disease. The resultant gels were silver stained, digitized, and analyzed, by image analysis utilizing a pipelined image processor connected to a host computer. At 14 +/- 1 days of age, protein patterns from sf mutant and normal mice control organs showed considerable homogeneity, although there were proteins identified unique to the sf mutant and to the normal controls. At 20 +/- 1 days of age, the pattern differences between the sf mutant and normal control increased markedly. Differences were expressed as the percent of proteins that were unique to either the sf mutant or the normal control from the total number of each type. The percent of proteins that increased or decreased in the three organs utilized in this study ranged between 21%-39% at 14 days and were between 25%-54% at 20 days. Differences in protein expression between the normal and sf mutant as the disorder progressed for each of the three tissues examined. In addition, thymus protein profiles from 9 day old littermates that were phenotypically normal but genotypically unknown were evaluated to determine if marker proteins could be identified for the sf mutation. Limited protein changes were noted at relative molecular weights of 66, 60, 54, 39, 37, 33, 25, 23, 27, and 11 kDa. These data suggest that the sf mutation follows a trackable pattern of protein expression and repression different than the normal control C3H mouse. Several potential marker proteins associated with the sf mutation were identified in 9 day thymus prior to the phenotypic expression of the disease. These putative biomarkers may be useful for characterizing the sf mutation and the mutant may act a possible model the Wiskott-Aldrich syndrome (WAS).

Abnormalities, Multiple↗
PubMedDate not supplied

Gene expression and cytokine and enzyme activation in the liver after a burn injury.

The liver plays a critical role in the inflammatory response to injury; however, the mechanisms by which the liver is affected and how it influences the rest of the immune system are not well understood. Partial hepatectomy is a direct injury to the liver, whereas a burn is an indirect injury to liver, but both injuries appear to produce damage to the liver. In this study, we used a mouse model of 25% total body surface area and 40% total body surface area full-thickness burns to investigate the mechanism of liver damage and response to burn injury by measuring levels of c-Jun messenger (m)RNA, NFkappaB nuclear protein, interleukin-6, transaminases, and liver tissue histology over time. c-Jun and NFkappaB are 2 transcription factors that are induced by partial hepatectomy and related to hepatocyte injury and growth. In both groups of mice with burns, expression of c-Jun mRNA and NFkappaB nuclear protein was activated within 30 minutes after the burn injury, followed by increased levels of interleukin-6 and, finally, elevated enzyme levels. Liver injuries were similar in both groups despite the magnitude of the burns. We believe that these gene products are initiated in the hepatocyte injury after a burn and that they precede other inflammatory responses such as cytokine release, plasma transaminase levels, and histologic changes.

Alanine Transaminase↗