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C A Pinkert

Publications and source records attributed to C A Pinkert.

At least 55 records · Page 3Linked to original sources
PubMed1987

Transgenic mice selectively lacking MHC class II (I-E) antigen expression on B cells: an in vivo approach to investigate Ia gene function.

The E alpha MHC class II gene with 1.4 kb of 5'-flanking and 0.5 kb of 3'-flanking sequences was introduced into (H-2b X s)F2 mice, which do not express their endogenous E alpha gene. The transgene was expressed in thymic tissue and in adherent spleen cells and was induced in peritoneal exudate cells by gamma-interferon. In contrast to the normal E alpha gene, there was no expression in B lymphocytes. Since transgenic animals made with constructs containing 3.2 kb and 2 kb of 5'-flanking sequences show normal expression pattern of the E alpha gene, it appears that deletion of 5'-flanking sequences between -1.4 kb and -2 kb inactivated or eliminated regulatory sequences required for expression of E alpha specifically in B cells. The presence of pBR327 DNA linked to the -1.4 kb E alpha transgene suppresses expression in peripheral adherent cells, yielding mice expressing E alpha only in the thymus. These mice appear to be tolerant to I-E, as measured in mixed leukocyte response experiments.

Animals↗
PubMed1987

Pancreatic neoplasia induced by ras expression in acinar cells of transgenic mice.

Expression of an activated human c-H-ras oncogene under control of rat elastase I regulating elements leads to neoplasia of the fetal exocrine pancreas. In most transgenic mice bearing this gene construct, massive tumors involving all the pancreatic acinar cells develop within a few days of pancreatic differentiation. Expression of the normal c-H-ras proto-oncogene in acinar cells leads to more subtle anomalies, but no tumors develop. Thus modest amounts of the mutant ras proteins are sufficient, in an otherwise normal genetic background, to lead to neoplastic transformation of differentiating pancreatic acinar cells. In contrast, a comparable elastase-myc construct produces no pancreatic tumors in transgenic mice.

Animals↗
PubMed1987

Simian virus 40 (SV40)-transgenic mice that develop tumors are specifically tolerant to SV40 T antigen.

The ability to mount an immune response to simian virus 40 (SV40) T antigen was evaluated using mice from two distinct SV40 transgenic lines derived from injection of the same gene construct. Our studies demonstrate functional immune tolerance to SV40 T antigen in a SV40 transgenic line that consistently develops tumors of the choroid plexus by 7 mo of age. Antibodies to SV40 T antigen are undetectable in the serum of these animals; furthermore, mice from this line are unable to generate SV40-specific CTL after primary or secondary immunization with the virus, although they mount a normal CTL response to vaccinia virus when appropriately immunized. In contrast, we find that mice from a second transgenic line of low tumor incidence can mount a humoral response to SV40 T antigen, and upon immunization they generally respond with a vigorous cytotoxic T cell response to SV40 T antigen. These data suggest that specific immune tolerance to the product of an integrated viral oncogene may be induced, and is likely a reflection of the time in development at which the gene product first appears. Immune tolerance or responsiveness to the endogenous oncogene product may in turn play a role in the tumorigenic potential of such genes.

Animals↗
PubMed1987

Tumorigenesis in transgenic mice by a nuclear transport-defective SV40 large T-antigen gene.

The SV40(cT) mutant encodes a large tumor antigen (cT-ag) that is defective for transport from the cell cytoplasm into the nucleus. This mutant is able to transform established cell lines at near wild-type virus efficiencies, but has a markedly decreased ability to transform primary cells and to induce tumors in newborn hamsters (R. E. Lanford, C. Wong, and J. S. Butel, 1985, Mol. Cell. Biol. 5, 1043-1050). To explore the biology of transport-defective T-ag in vivo, transgenic mice carrying the cT-ag gene were produced. Five of eight founder animals died early in life of choroid plexus tumors (mean age +/- SE, 52 +/- 11.0 days); renal and thymic lesions were also observed. Mice of an SV40(cT) transgenic line regularly succumb to brain tumors (mean age, 81 +/- 1.2 days). SV40 T-ag is expressed in the tumor cells and is retained in the cytoplasm. The observation that SV40(cT) is equivalent to wild-type virus at tumor induction in transgenic mice emphasizes the probable importance of extranuclear forms of SV40 T-ag in brain tumor formation. This study also indicates that in vitro cell transformation assays may not always be accurate reflections of the oncogenic potential of a transforming gene in vivo, because of the different cell types involved.

Animals↗
PubMed1987

Progress on gene transfer in farm animals.

Transgenic pigs and sheep have been produced by the microinjection of single-cell zygotes and two-cell ova with linear molecules of mouse metallothionein I (MT) promoter/regulator fused to either the human growth hormone (hGH) or bovine growth hormone (bGH) structural genes. The foreign genes integrated into the chromosomes of 3 of 111 lambs or fetuses and 31 of 341 pigs or fetuses examined. Immunoreactive hGH or bGH was present in the plasma of two transgenic lambs and 19 transgenic pigs. The hGH concentration in plasma varied greatly among pigs and was unrelated to the number of gene copies that had integrated. Rate of growth was not enhanced in any of the transgenic pigs in comparison to their littermate controls. However, bGH and hGH exerted definite biological effects in transgenic pigs as evidenced by significantly depressed backfat measurements, elevated levels of insulin-like growth factor (IGF-I), stimulation of mammary development (by hGH) and reduction in porcine growth hormone (pGH) to nondetectable levels in plasma. Five of six founder transgenic pigs transmitted the MT-hGH gene construct to one or more progeny. Three progeny of a boar that expressed hGH also expressed the foreign gene.

Animal Husbandry↗
PubMed1987

Glomerulosclerosis and renal cysts in mice transgenic for the early region of SV40.

Considerable evidence indicates that genetic determinants play a major role in the pathogenesis of a variety of human and experimentally-induced renal diseases. There are, however, no firm data to indicate which genes or types of genes can induce or promote renal disease. The recently acquired ability to make specific alterations in the genetic background of an animal affords a unique opportunity to assess the effect(s) of a given gene on the structure and function of an organ of interest. Such modifications have been carried out in the creation of transgenic mice. We examined mice transgenic for the transforming gene encoding large T-antigen which is present in the early region of simian virus 40 (SV40). Renal lesions were present in most animals. While there was some heterogeneity in the type and severity of the renal lesions observed, a majority of the older mice displayed glomerulosclerosis and/or proliferative tubular lesions which in some were associated with multiple, large tubular cysts. The appearance of these lesions in mice transgenic for a transforming gene suggests that renal expression of a gene which controls cell proliferation may be associated with the development of glomerulosclerosis and renal cysts. These findings indicate a possible role for other transforming genes, or oncogenes, in the pathogenesis of glomerulosclerosis and cystic renal disease in humans and other animal models.

Animals↗
PubMed1987

Structural and pathological effects of synthesis of hepatitis B virus large envelope polypeptide in transgenic mice.

Overproduction of the hepatitis B virus (HBV) large envelope polypeptide by transgenic mice containing the entire HBV envelope coding region leads to the formation of extremely long (up to 800 nm), occasionally branching, filamentous 22-nm-diameter hepatitis B surface antigen particles that accumulate within the endoplasmic reticulum of the hepatocyte and are not efficiently secreted. As the endoplasmic reticulum expands to accommodate the increasing cellular filament stores, the hepatocytes become enlarged, hydropic, and eosinophilic and also display the characteristic features of "ground-glass" cells. As filament storage progresses, the ground-glass cells undergo coagulative necrosis and the mice develop an age-dependent lesion, whose severity is related to the intracellular concentration of envelope polypeptide, that is characterized by focal hepatocellular degeneration and necrosis, lobular macrophagic inflammation, and increased serum transaminase activity. Advanced lesions demonstrate hepatocellular hyperplasia evident as lobular architectural disarray and microscopic hepatocellular nodules, many of which no longer contain detectable HBV envelope antigens. These changes may become extreme, producing a massively enlarged liver due to multifocal nodular regenerative hyperplasia. Overproduction of the large HBV envelope polypeptide exerts major structural constraints on HBV particle formation, leading to reduced secretion and progressive intracellular accumulation of hepatitis B surface antigen, which can reach sufficiently high concentrations to be directly cytotoxic to hepatocytes in this transgenic mouse system.

Animals↗
PubMed1987

An albumin enhancer located 10 kb upstream functions along with its promoter to direct efficient, liver-specific expression in transgenic mice.

Transgenic mice were used to locate the cis-acting DNA elements that are important for efficient, tissue-specific expression of the mouse albumin gene in the adult. Chimeric genes with up to 12 kb of mouse albumin 5'-flanking region fused to a human growth hormone (hGH) reporter gene were tested. Remarkably, a region located 8.5-10.4 kb upstream of the albumin promoter was essential for high-level expression in adult liver and the region in between -8.5 and -0.3 kb was dispensable. The far-upstream region behaved like an enhancer in that its position and orientation relative to the albumin promoter were not critical; however, it did not function well with a heterologous promoter. Two of four DNase hypersensitive sites found in the 5'-flanking region of the albumin gene map to the far-upstream and promoter regions; the others may reflect regions involved in developmental or environmental control of this gene.

Animals↗
PubMed1986

Expression of hepatitis B virus large envelope polypeptide inhibits hepatitis B surface antigen secretion in transgenic mice.

The outer membrane of the hepatitis B virus consists of host lipid and the hepatitis B virus major (p25, gp28), middle (gp33, gp36), and large (p39, gp42) envelope polypeptides. These polypeptides are encoded by a large open reading frame that contains three in-phase translation start codons and a shared termination signal. The influence of the large envelope polypeptide on the secretion of hepatitis B surface antigen (HBsAg) subviral particles in transgenic mice was examined. The major polypeptide is the dominant structural component of the HBsAg particles, which are readily secreted into the blood. A relative increase in production of the large envelope polypeptide compared with that of the major envelope polypeptide led to profound reduction of the HBsAg concentration in serum as a result of accumulation of both envelope polypeptides in a relatively insoluble compartment within the cell. We conclude that inhibition of HBsAg secretion is related to a hitherto unknown property of the pre-S-containing domain of the large envelope polypeptide.

Animals↗
PubMed1985

A transgenic mouse model of the chronic hepatitis B surface antigen carrier state.

In an attempt to establish a model of the healthy carrier state in hepatitis B virus (HBV) infections, transgenic mice expressing HBV genes were produced. Fertilized one-cell eggs were microinjected with subgenomic fragments of HBV DNA containing the coding regions for the HBV surface antigen (HBsAg) and pre-S and X antigens. Either the normal (HBV) or metallothionein promoters were used to obtain expression of the HBV genes. There was no evidence of viral replication or tissue pathology. The integrated HBV DNA sequences were inherited in a normal Mendelian fashion. Three of 16 transgenic mice expressed HBV-encoded gene products to which they were immunologically tolerant. Expression was not tissue specific and may be influenced by the genomic integration site and cellular factors. Both HBsAg and pre-S antigen were detectable within the cytoplasm of hepatocytes and renal tubular epithelial cells. High serum concentrations of HBsAg were detectable and the secreted product appeared authentic as judged by mean density, morphology, mean particle diameter, polypeptide composition, and antigenicity. The absence of tissue pathology in these immunologically tolerant animals supports the hypothesis that cellular injury under these conditions is not a direct consequence of expression of the pre-S or HBs regions of the HBV genome.

Animals↗
PubMed1985

Tissue-specific, inducible and functional expression of the E alpha d MHC class II gene in transgenic mice.

We have introduced the class II E alpha d gene into (C57BL/6 X SJL) F2 mice which do not express their endogenous E alpha gene. The mRNA expression of the E alpha d gene shows the same tissue distribution as the endogenous class II genes except in the case of one mouse, which carried 19 copies of the E alpha d gene. In this mouse expression of E alpha d mRNA was seen in all tissues tested. Expression of the transgene was induced by gamma-interferon in isolated macrophages from the transgenic mice. In addition, fluorescence activated cell sorter (FACS) analysis, mixed lymphocyte response and antigen-presentation experiments showed that the product of the transferred gene is expressed on the cell surface and functions as a major histocompatibility complex restriction element. Transmission of the gene occurred only with female transgenic mice, all males were infertile or did not transmit the gene, suggesting an effect of the transferred DNA sequence on male reproductive function.

Animals↗
PubMed1985

Regression of induced corpora lutea by human chorionic gonadotropin in prepuberal gilts.

The effect of daily injections of human chorionic gonadotropin (HCG) on luteal maintenance in hysterectomized prepuberal gilts induced to ovulate and in hysterectomized mature gilts was studied. Twenty-four pre-puberal gilts, 120 to 130 d of age, were induced to ovulate with 1,000 IU pregnant mare serum gonadotropin followed 72 h later with 500 IU HCG. Nine of the 24 prepuberal gilts (bred controls) were artificially inseminated on d 0 (d 0 = d after HCG). Mature gilts that had displayed one or more estrous cycles of 17 to 22 d were used (d 0 = onset of estrus). All gilts, except the bred controls, were totally hysterectomized on d 6 to 9 and their corpora lutea (CL) marked with charcoal. From d 10 through 29, eight prepuberal and 10 mature hysterectomized gilts received daily injections of 500 IU HCG in saline while seven prepuberal and eight mature hysterectomized gilts received daily injections of saline vehicle. Jugular blood samples were quantitated by radioimmunoassay for estrogen and 13,14-dihydro-15-keto prostaglandin F2 alpha (PGFM), a metabolite of prostaglandin F2 alpha. One bred control gilt was pregnant on d 30, indicating that the prepuberal gilts used in the experiment were prepuberal. All mature gilts and six of seven prepuberal gilts that received saline had maintained CL to d 30. Eight of 10 mature gilts that received HCG had maintained CL to d 30, while only two of eight (P less than .05) prepuberal gilts that received HCG maintained CL to d 30. All gilts receiving HCG had numerous follicles and accessory luteal structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Luteinizing hormone receptors and progesterone content in porcine corpora lutea after prostaglandin F2 alpha.

The effect of prostaglandin F2 alpha (PGF2 alpha) on luteinizing hormone (LH) receptors, weight and progesterone content of corpora lutea (CL), and serum progesterone concentrations was studied in gilts. Fifteen gilts were hysterectomized between Days 9 to 11 of the estrous cycle. Twelve gilts were injected i.m. with 10 mg of PGF2 alpha and 3 with saline on Day 20. Ovaries were surgically removed from each of 3 gilts at 4, 8, 12 and 24 h following PGF2 alpha treatment and from the 3 control gilts 12 h following saline injection. Jugular blood samples for progesterone analysis were collected from all gilts at 0, 2 and 4 h following treatment and at 8, 12 and 24 h for gilts from which ovaries were removed at 8, 12 and 24 h, respectively. Mean serum progesterone and CL progesterone concentrations decreased within 4 h after PGF2 alpha treatment (P less than 0.05) and remained low through 24 h after treatment. The number of unoccupied LH receptors decreased by 4 h (P less than 0.05) and this trend continued through 24 h. There were no differences in luteal weight or affinity of unoccupied LH receptors of luteal tissue at 4, 8 12 and 24 h after PGF2 alpha when compared to luteal tissue from controls. These data indicate that during PGF2 alpha-induced luteolysis in the pig, luteal progesterone, serum progesterone concentrations and the number of LH receptors decrease simultaneously.

Animals↗
PubMed1984

Serum luteinizing hormone and estrogen profiles before puberty in the gilt.

The hypothesis that an increase in serum luteinizing hormone (LH) concentration occurs before the onset of puberty in the gilt was tested. Blood samples were collected from 14 gilts, 166 d of age and 72.6 +/- 1.8 kg body weight, every 15 min for 8 h 1 d after jugular cannulation. Gilts were checked daily for estrus with a boar. The sampling procedure was repeated 21 and 33 d later, by which time three gilts had attained puberty (first estrus with continued regular estrous cycles), and then every 7 d thereafter until an additional five gilts attained puberty. Serum LH and estrogen (E) concentrations were quantitated by radioimmunoassay. Bleeding periods were grouped into seven common physiological ages before puberty; age 1 greater than or equal to 57 d (n = 4), age 2 = 43 to 50 d (n = 5), age 3 = 31 to 38 d (n = 4), age 4 = 22 to 26 d (n = 5), age 5 = 17 to 19 d (n = 4), age 6 = 10 to 12 d (n = 5) and age 7 = 3 to 5 d (n = 5). Mean serum LH concentration (ng/ml, mean +/- SE) at age 7 (1.0 +/- .1) was greater (P less than .01) than at ages 2, 3, 4 and 5 (6 +/- .1) but not ages 1 and 6 (.8 +/- .1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Serum concentrations of pituitary and adrenal hormones in female pigs exposed to two photoperiods.

Serum concentrations of pituitary and adrenal hormones were determined in lactating sows and ovariectomized (OVX) gilts exposed to 8 h (8L:16D) or 16 h of light (16L:8D). In addition serum prolactin (PRL) concentrations were determined after a thyrotropin releasing hormone (TRH) challenge. At 103 +/- 2 d of gestation or 3 wk after ovariectomy of nulliparous gilts on d 7 to 9 of the estrous cycle (d - 10), blood samples were collected from jugular vein cannulae at 30-min intervals for 8 h beginning at 0800 h. Immediately after the last sample, 13 sows and five OVX gilts were assigned to 8L:16D and 14 sows and five OVX gilts were assigned to 16L:8D/d and placed in two identical chambers in the farrowing house. Blood sampling was repeated on d 7, 14 and 21 of lactation in the sows and on d 7, 14, 21 and 28 in the OVX gilts. In Exp. 1, serum cortisol (C) concentrations were similar for sows exposed to 8L:16D (n = 7) and 16L:8D (n = 6) treatments, whereas in Exp. 2, serum C concentrations for sows exposed to 8L:16D (n = 6) were lower than those exposed to 16L:8D (n = 6) on d 7, 14 and 21. Photoperiod failed to influence serum concentrations of PRL, luteinizing hormone (LH) and growth hormone in the lactating sows or PRL in the OVX gilts. Photoperiod also failed to affect mean basal serum concentrations, peak height and peak frequency for PRL and LH in the lactating sows or for PRL in the OVX gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗