Biomedical subjects

J L Vandeberg

Publications and source records attributed to J L Vandeberg.

At least 19 recordsLinked to original sources

PubMed1998

Two major loci control variation in beta-lipoprotein cholesterol and response to dietary fat and cholesterol in baboons.

We explored the genetic control of cholesterolemic responses to dietary cholesterol and fat in 575 pedigreed baboons. We measured cholesterol in beta-lipoproteins (low density lipoprotein cholesterol [LDLC]) in blood drawn from baboons while they were consuming a baseline (low in cholesterol and fat) diet, a high-saturated fat (lard) diet, and a high-cholesterol, high-saturated fat diet. In addition to baseline levels (LDLC(Base)), we analyzed two variables for diet response: LDLC(RF), which represents the LDLC response to increasing dietary fat (ie, high-fat diet minus baseline), and LDLC(RC), which represents the LDLC response to increasing dietary cholesterol level (ie, high-cholesterol, high-fat diet minus high-fat diet). Heritabilities (h2) of the 3 traits were 0.59 for LDLC(Base), 0.14 for LDLC(RF), and 0.59 for LDLC(RC). In addition, LDLC(Base) and LDLC(RC) had a significant genetic correlation (ie, rhoG=0.54), suggesting that 1 or more genes exert pleiotropic effects on the 2 traits. Segregation analyses detected a single major locus that accounted for nearly all genetic variation in LDLC(RC) and some genetic variation in LDLC(Base) and LDLC(RF) and confirmed the presence of a different major locus that influences LDLC(Base) alone. Preliminary linkage analyses indicated that neither locus was linked to the LDL receptor gene, a likely candidate locus for LDLC. Detection of these major loci with large effects on the LDLC response to dietary cholesterol in a nonhuman primate offers hope of detecting and ultimately identifying similar loci that determine LDLC variation in human populations.

Animals↗

PubMed1998

Low-dose ultraviolet exposure early in development can lead to widespread melanoma in the opossum model.

Suckling young of opossums (Monodelphis domestica) were exposed to ultraviolet radiation (UVR, predominantly UVB: 290-320 nm) in part to determine an optimal protocol for induction and progression of melanoma in this species. In all, 620 litters were introduced to one of seven protocols. The lowest dose (175 J/m2) administered three times a week for almost three weeks led to the highest incidence of melanotic lesions with melanoma potential (8.1%) among young (5-month-old) adults. Among 101 much older animals (> 17 months at necropsy), 43% showed metastatic melanoma to the lymph nodes and almost one-third of these had progressed to widespread dissemination. Three of the latter animals, from a total of 13 obtained so far, were selected for detailed histological examination of disseminated disease. At necropsy, all three showed widespread metastases beyond the lymph nodes to the spleen, lungs, and other distant sites. Histological changes typical of malignant melanoma included junctional activity, mitotic figures, and nerve and vessel invasion. This novel finding leads us to conclude that UVR can act as a complete carcinogen for progression to widely disseminated disease and that exposure of sucklings can lead, in old age, to widespread metastatic melanoma in this model. The results are thus not inconsistent with the view that, in humans, early exposure to sunlight might act as an initiating factor in a later progression to malignant melanoma.

Age Factors↗

PubMed1997

Genetic epidemiology of seropositivity for Trypanosoma cruzi infection in rural Goias, Brazil.

Chagas' disease is a zoonotic disease found throughout Latin America. Despite control programs in many of the affected countries, infection with Trypanosoma cruzi continues to be a major public health concern. In Brazil alone, approximately 53 million people live in endemic areas. Research with humans and with animal models indicates that there is variation in susceptibility to infection with T. cruzi. The reasons for this variation are not known although several studies have implicated genetic factors. An indirect immunofluorescence assay was used to assess seropositivity for T. cruzi infection in 716 adults from the municipality of Posse, Goias, Brazil. Detailed genealogic information was gathered at the time of sampling, which allowed assignment of 525 individuals to 146 pedigrees containing between two and 103 individuals; the remaining 191 unrelated individuals were retained as independents in the analysis. Using a maximum likelihood variance decomposition approach, we performed quantitative genetic analyses to determine if genetic factors could partially account for the observed pattern of seropositivity. The maximum likelihood estimate of the heritability of T. cruzi infection was 0.56 +/- 0.27 (mean +/- SE), indicating that genetic factors account for more than half of the observed variation in infection status. An additional 23% of the variation (c2 = 0.23 +/- 0.09) is attributable to the effects of shared environment, as assessed by common household. The results indicate that genetic factors play an important role in determining epidemiologic patterns of T. cruzi infection. Further characterization of these genetic factors may suggest new biologic areas to be targeted by prevention and intervention programs.

Adolescent↗

PubMed1997

Development in vitro of Marsupials: a comparative review of species and a timetable of cleavage and early blastocyst stages of development in Monodelphis domestica.

The development of marsupial oocytes and embryos in vitro is reviewed. Most stages of development have been cultured successfully, usually in a complex medium with added fetal calf serum. Simpler media without added serum have been developed for fertilization and cleavage in vitro. Culture systems have been established for oocyte maturation and fertilization in the grey short-tailed opossum and for cleavage from the zygote to the early expanding unilaminar blastocyst in a number of other marsupials. Survival in vitro of the unilaminar and early bilaminar blastocyst stages is limited in all species examined. In contrast, late bilaminar, trilaminar, embryonic and fetal stages develop at rates approximating those in vivo. More stages have been cultured successfully in Sminthopsis macroura than in any other species. It has been cultured from the late bilaminar blastocyst to within 18 h of birth. Stages of cleavage and unilaminar blastocyst formation of Monodelphis domestica timed by videotaping mating animals, proceeded at similar rates in vivo and in vitro. As in other marsupials, cleavage in this opossum is characterized by a polarized conceptus. This polarity is expressed in the distribution of organelles in the zygote and the localization of secretion of the extracellular matrix material into the cleavage cavity and of the initial cell-zona attachment. Because cell-cell adhesion follows cell-zona adhesion, a unilaminar blastocyst forms without the development of an intervening morula stage.

Animals↗

PubMed1996

Analysis of the cDNA and encoded protein of the human testis-specific PGK-2 gene.

Because of their unique function, germ cells require unique gene products. Thus, although the glycolytic enzyme phosphoglycerate kinase (PGK) is required in all metabolically active cell types, there are two functional PGK genes in the mammalian genome, one, PGK-1, that is X-linked and ubiquitously expressed in all somatic tissues, and a second, PGK-2, that is autosomal and expressed only in spermatogenic cells. Expression of the PGK-2 gene may function solely to compensate for repressed expression of the PGK-1 gene due to X-chromosome inactivation in spermatocytes. Alternative y, the PGK-2 gene could encode an isozyme with unique characteristics that are beneficial to spermatozoa. We have isolated a cDNA of the human PGK-2 gene and used this as probe to demonstrate that transcription of this gene in spermatocytes and spermatids coincides with a period of repressed transcription of the X-linked PGK-1 gene during spermatogenesis in the human testis. We have also analyzed the amino acid sequence and protein characteristics of the PGK-2 isozyme deduced from this cDNA and compared them with that of the human PGK-1 isozyme to show that known structural and functional motifs are conserved in both proteins. Finally, we have examined the distribution of the PGK-1 and PGK-2 isozymes during spermatogenesis in the mouse to show that while the PGK-2 protein does not appear to possess any unique intracellular localization signal, it is more stable in vivo than the PGK-1 protein.

Amino Acid Sequence↗

PubMed1995

Developmental progression of Gpd expression from the inactive X chromosome of the Virginia opossum.

Metatherian (marsupial) mammals possess a non-random form of X-chromosome inactivation in which the paternally-derived X is always the one inactivated. To examine the progression of X-linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded Gpd gene products in heterozygous female Virginia opossums (Didelphis virginiana) across a major portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post-partum development, expression of the paternal Gpd allele had not attained the adult, tissue-specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch-life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpd gene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) major changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue-specific manner.

Alleles↗

PubMed1994

Timetable of in vivo embryonic development in the grey short-tailed opossum (Monodelphis domestica).

The timing of development was examined in 496 embryos from female Monodelphis domestica collected at known time intervals after video recorded mating. Ovulation occurred approximately 20 hr (day 1) after mating, and fertilization was observed by 24 hr. Transport through the oviducts was rapid, and pronuclear stage embryos were recovered from the uterus as early as 24 hr after mating. Second cleavage had occurred by 55 hr after mating. Three-celled embryos were among those collected on day 3 after mating, indicating that asynchronous cleavage of blastomeres can occur from the two-cell stage. The four-cell stage persisted for approximately 24 hr, and embryos that had undergone third cleavage were first recovered 74 hr after mating. Embryos that had undergone fourth to fifth cleavage were found 96-100 hr (4 days) after mating and complete unilaminar blastocysts by 5.5 days after mating. Primary endoderm formed from an already distinct embryonic area of the unilaminar blastocyst early on day 7 after mating. Formation of the bilaminar blastocyst was completed rapidly, on day 7 after mating. The primitive streak appeared on day 10 after mating, and organogenesis rapidly ensued on a timetable similar to that reported for Didelphis virginiana (McCrady, 1938). Close contact with the maternal circulation was established on day 11 and by day 12 maternal and embryonic tissues could not be separated without damage. The length of the gestation period from fertilization to birth was approximately 13.5 days. These observations provide the basis for further embryological cellular and molecular studies of this species as a laboratory model for marsupial development.

Animals↗

PubMed1991

Ontogeny of the thymus gland of a marsupial (Monodelphis domestica).

The gray short-tailed opossum (Monodelphis domestica) has recently been established as a laboratory animal; consequently, its utility as an animal model is enhanced as more of its basic biologic characteristics become defined. To this end, we studied the ontogeny of the thymus gland in M. domestica ranging in age from the day of birth to over three years. In contrast to most Australian marsupials, M. domestica possesses only a thoracic thymus. The thymus is large in neonates and remains large until young adulthood (six months of age). It has a well-defined cortex, medulla and Hassall's corpuscles. At about six months of age, the thymuses of most animals begin to atrophy, the cortex and medulla being replaced by fat. By 28 months of age, about 50% of animals have thymuses that are completely atrophied. Thus, the ontogeny of the thymus of M. domestica appears to be similar to that of eutherian mammals.

Adipose Tissue↗

PubMed1991

In utero bone marrow transplantation of fetal baboons with mismatched adult baboon marrow.

In utero bone marrow transplantation to fetuses offers the potential advantage of ameliorating the effects of genetic disorders by transplanting allogeneic hematopoietic stem cells into recipients who are immunoincompetent and require no preparative regimen. Therefore, we undertook studies to examine the feasibility of in utero bone marrow transplantation of unrelated allogeneic adult bone marrow into fetal baboons. Thirty-one baboon fetuses were transplanted between the ages of 60 and 160 days gestation (normal gestation, 182 days) with unrelated allogeneic adult bone marrow containing a different isozyme of glucose-phosphate isomerase (GPI). Approximately one third of the 80-day fetuses demonstrated engraftment 1 month after transplantation. Three of three of the initial chimeras died in utero 45 to 80 days after transplantation and the remaining chimeras lost their graft. Furthermore, 80-day fetal baboons were able to recognize donor cells, maternal cells, and other adult baboon peripheral blood cells in a mixed lymphocyte culture (MLC) reaction but still could engraft with allogeneic bone marrow. In contrast all nonchimeric animals survived to term. These data suggest that fetal transplantation of primates is feasible using techniques employed in these studies and that transplantation of younger fetuses who are immunocompetent should be attempted.

Alleles↗

PubMed1990

Mammary glands in male marsupials: I. Primordia in neonatal opossums Didelphis virginiana and Monodelphis domestica.

Neonates of the American didelphid marsupials Didelphis virginiana and Monodelphis domestica were sexed by karyotype and histologically examined on the day of birth. Mammary anlagen were found in both sexes of both species, but the neonatal males had less than one-third of the full female complement of mammary glands. Male neonates of both species also had paired scrotal bulges anterior to the genital tubercle but these were never present in females, once again raising the question of whether the pouch and scrotum are homologous structures. Mammary anlagen are not found in male neonates of the Australian marsupial species so far studied, which suggests a dichotomy in the control of some aspects of sexual differentiation in the two marsupial lineages.

Animals↗

PubMed1990

Mixed lymphocyte culture reactivity of fetal baboons: application for in utero bone marrow transplantation.

Bone marrow transplantation offers a potential cure for patients suffering from genetic diseases such as inborn errors of metabolism. The optimal time to transplant many of these affected individuals would be early in gestation. To date, little information is available on the cellular immune reactivity of fetal primate lymphocytes. Therefore, we tested peripheral blood lymphocytes obtained in utero from baboon fetuses (Papio sp.) for their ability to respond in mixed lymphocyte culture (MLC) against their mothers, against a pool of unrelated animals, and in the case of fetuses given unrelated bone marrow transplants in utero, against their specific bone marrow donors. The majority of fetuses as young as 80 gestational days (182-day normal gestation period) were capable of responding strongly to maternal and unrelated lymphocytes in MLC. Of six fetuses that were transplanted, three did not engraft as indicated by undetectable levels of the donor-specific type B allele of glucose phosphate isomerase in fetal blood samples 1 month post-transplant. The three fetuses that did engraft all lost their grafts before birth. These data demonstrate that fetal lymphocytes obtained in utero can be tested for MLC reactivity and suggest that MLC testing can be used to select appropriate donor-recipient combinations for in utero bone marrow transplantation.

Animals↗

PubMed1989

Immune response of a marsupial (Monodelphis domestica) to sheep red blood cells.

A study of the humoral immune response of a marsupial, Monodelphis domestica, was performed using sheep red blood cells as the immunogen and a hemolytic titration as the assay. The primary response to a single intramuscular injection was similar to that observed in other mammalian species, except that the titers remained high for as long as 37 weeks after the initial injection. The secondary response was weaker than the primary response and diminished as early as 15 weeks after the initial injection (and only 11 weeks after the single booster injection). The hyperimmune response was similar to the secondary response, except that the titers remained consistent for up to 10 weeks and then fell to very low levels at 35 weeks. The data support the view that the primary humoral response of this marsupial is similar to that of eutherian mammals. However, the secondary and hyperimmune responses appear to be very weak, if present at all.

Animals↗

PubMed1988

DNA methylation in the developing marsupial embryo.

Marsupial development differs from early development of placental mammals in that the blastocyst is unilaminar, so that both embryonic and extraembryonic cells are derived from a single layer of cells (protoderm) which faces the blastocyst cavity. Also, all cells in female marsupial conceptuses so far examined show preferential paternal X-inactivation. To test for a possible correlation between cell position, paternal X-inactivation and DNA hypomethylation, marsupial DNA preparations from three regions, embryo, vascular yolk sac and avascular yolk sac, were digested with methyl-specific restriction endonucleases, separated on agarose gels and end-labelled with 32P-dCTP. The size distribution of the fragments obtained indicated three levels of methylation: high methylation of embryonic DNA, intermediate levels of methylation of vascular yolk sac DNA and hypomethylation of avascular yolk sac DNA. The degree of methylation of repeat sequences, observed as discrete bands in end-labelled HpaII digests, was correlated with the overall methylation of tissue DNA. Thus, the difference in methylation in embryonic and extraembryonic DNA was similar to that described for the mouse conceptus, and the outside cell position of marsupial fetal precursor cells did not correlate with hypomethylation. HpaII tiny fragments, which indicate the presence of CpG-rich islands of DNA, were evident in the marsupial digests. In the mouse DNA, these islands are associated with gene transcription and provide one route to cloning of unique gene sequences.

Animals↗

PubMed1988

In utero bone marrow transplantation of fetal baboons with mismatched adult marrow: initial observations.

Recent advances in prenatal diagnoses of sickle cell anemia and thalassemia permit early identification of affected fetuses. However, the only intervention possible to date is abortion of the affected fetuses. Transplantation of normal marrow into fetuses in utero could correct these life-threatening disorders, but to accomplish this techniques must be developed for fetal transplantation in man. Therefore, we have transplanted fetal baboons with mismatched adult baboon bone marrow from donors that differed at the glucose phosphate isomerase locus. Twenty-two fetuses between 60 and 160 days of gestation (term gestation is 182 days) were transplanted intraperitoneally with 10(9) marrow mononuclear cells/kg body weight using an ultrasonic technique. No immunosuppressive or preparative regimen was given prior to or after transplantation, and all fetuses tolerated the procedure well. One month after transplantation fetal blood samples were obtained to assess chimerism. Three chimeras were detected among 10 fetuses transplanted at 80 days' gestation, and no chimeras were detected in fetuses greater than 80 days' gestation at the time of transplantation. All chimeras died in utero during the third trimester of pregnancy: one of an intrauterine infection at 160 days' gestation, one at 135 days' gestation and one at 145 days' gestation. In contrast, the other 19 non-chimeric fetuses survived. These data suggest: (1) in utero fetal bone marrow transplantation is technically feasible in primates; (2) that allogeneic adult bone marrow can engraft and persist for at least 1 month in fetal baboons transplanted at 80 days of gestation; and (3) that delineation of the causes for loss of fetal chimeras should prove valuable in assessing the therapeutic potential for in utero bone marrow transplantation in man.

Aging↗

PubMed1987

Pregnancy-associated esterase in sera of baboons.

Baboon serum samples were resolved by starch gel electrophoresis and polyacrylamide gradient gel electrophoresis and stained with naphthol substrates for esterase activity. An esterase that hydrolyzed alpha-naphthyl butyrate in preference to alpha-naphthyl acetate was found in very high activities in some individuals but not others. It migrated just cathodal of the albumin band in starch gels. In polyacrylamide gradient gels, it co-migrated with albumin and had an apparent molecular weight of approximately 65,000 daltons. Electrophoretic analysis by gel electrophoresis of random serum samples from male and female baboons indicated that this esterase was present only in the sera of pregnant baboons. Further investigation of serial samples collected from carefully monitored baboons confirmed that the amount of activity of this esterase was correlated with stage of pregnancy. Therefore, it was named pregnancy esterase (PE). PE was detectable by gel electrophoresis and chromogenic staining techniques as early as day 30 of pregnancy; its activity gradually increased with progressive pregnancy and reached maximum activity near full term (182 days). Soon after parturition, the activity of PE decreased rapidly and was not detected in maternal sera by day 14 postpartum. No evidence of PE was detected in sera of pregnant humans.

Animals↗

PubMed1986

Ocular NAD-dependent alcohol dehydrogenase and aldehyde dehydrogenase in the baboon.

Isoelectric focusing (IEF) techniques and spectrophotometric analyses were used to examine the distribution and properties of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isozymes in ocular tissue of olive and yellow baboons. Cornea extracts exhibited very high specific activities of the 'stomach-specific' ADH and ALDH isozymes (designated ADH-3 and ALDH-III respectively), and were devoid of the major liver and kidney isozymes. Lens extracts exhibited lower activities of ADH-3 and ALDH-III, and also showed significant activity of ALDH-II (the major liver cytosolic isozyme) and a group of 'lens-specific' ALDHs of low isoelectric point. Extracts of baboon retina also exhibited ADH-3 and ALDH-III activities, together with activities of the major liver cytosolic (ALDH-II) and mitochondrial (ALDH-I) isozymes of ALDH; and ADH-5 (or chi-ADH) activity. Evidence was obtained for individual variation of ALDH-III activity in the lens. An electrophoretic variant for ADH-3 indicated genetic identity of the major stomach and ocular ADH isozyme. The catalytic properties of the high specific activity corneal ADH and ALDH isozymes indicated a role in the detoxification of lipid peroxidation by-products.

Alcohol Dehydrogenase↗

PubMed1986

Genetic analysis of liver neuraminidase isozymes in Rattus norvegicus: independent control of NEU-1 and NEU-2 phenotypes.

Two recently identified isozymes of neuraminidase in rat liver were examined for transmission patterns and linkage relationships, and for variation among inbred strains. The isozymes, designated neuraminidase-1 (NEU-1) and neuraminidase-2 (NEU-2), exhibited no electrophoretic mobility variants among the 22 inbred strains examined, but did possess striking interstrain variation in activity phenotypes on electrophoretic gels. The results of a backcross analysis involving the KGH and ACP strains revealed that NEU-1 and NEU-2 phenotypes are independently controlled, each by a single autosomal locus with additively acting alleles. The two loci are unlinked to one another, but the gene controlling NEU-1 is tightly linked to RT1, the rat major histocompatibility complex. This gene is almost certainly identical to Neu-1, a gene identified previously through its effect on "total" activity levels of liver neuraminidase as determined by fluorometric assay of tissue homogenates. NEU-2 and the gene controlling its phenotype were not detected by the fluorometric technique. We designate the genes controlling the NEU-1 and NEU-2 phenotypes as Neu-1 and Neu-2, respectively. Data from this and other studies place Neu-1 between Glo-1 and dw-3. The location of Neu-2 is unknown.

Animals↗

PubMed1986

Passively acquired immunity in the newborn of a marsupial (Monodelphis domestica).

A colony of fully pedigreed Monodelphis domestica has been used to investigate the maternal-fetal relationship in this unique marsupial species. To determine how immunity is transferred from mothers to young in M. domestica, we hyperimmunized females with sheep red blood cells (SRBC) before and during gestation. Offspring from these females were collected at various times after birth, and saline extracts of the neonates were assayed for hemolysins against SRBC. Antibodies were present in extracts of newborn that had been allowed to suckle their mothers; none were detected in extracts of infants that were not allowed to suckle. Antibodies were present in the milk of immunized mothers, but were not detected in the milk of nonimmunized mothers. The titer of antibodies in the extracts of newborns generally increased proportionately to the time that the newborn had been allowed to suckle. We conclude that the transfer of passive immunity from mothers of M. domestica to their offspring occurs primarily via the milk.

Animals↗