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Biomedical subjects

M M Miller

Publications and source records attributed to M M Miller.

At least 55 records · Page 3Linked to original sources
PubMed1997

Progesterone regulated expression of flavin-containing monooxygenase 5 by the B-isoform of progesterone receptors: implications for tamoxifen carcinogenicity.

Progesterone is a key developmental, proliferative, and differentiative hormone in the breast and endometrium, and it can accelerate carcinogenesis in the mammary gland epithelium. In the breast and uterus, progesterone acts through two coexpressed isoforms of progesterone receptors, the B- and A-receptors. To study the function of each isoform in isolation, we previously constructed two breast cancer cell lines that stably and independently express either B-receptors (YB cells) or A-receptors (YA cells). In the present study, YA or YB cells were left untreated, or were treated with the synthetic progestin R5020, and the messages present in each cell line under the two conditions were analyzed by differential display. Two message species are described that are regulated only by B-receptors. One of these is regulated in a ligand-independent manner. A third set of messages, encoding flavin-containing monooxygenase 5 (FMO5), was induced by R5020 only in YB cells. A-receptors appear to be inhibitory. FMOs are involved in the metabolic activation of drugs and xenobiotic compounds, including the antiestrogen tamoxifen, to carcinogenic intermediates. It is possible, therefore, that by upregulating the levels of FMO5, progesterone enhances the carcinogenicity of tamoxifen in target tissues that overexpress progesterone B-receptors.

Breast Neoplasms↗
PubMed1996

Assignment of Rfp-Y to the chicken major histocompatibility complex/NOR microchromosome and evidence for high-frequency recombination associated with the nucleolar organizer region.

Rfp-Y is a second region in the genome of the chicken containing major histocompatibility complex (MHC) class I and II genes. Haplotypes of Rfp-Y assort independently from haplotypes of the B system, a region known to function as a MHC and to be located on chromosome 16 (a microchromosome) with the single nucleolar organizer region (NOR) in the chicken genome. Linkage mapping with reference populations failed to reveal the location of Rfp-Y, leaving Rfp-Y unlinked in a map containing >400 markers. A possible location of Rfp-Y became apparent in studies of chickens trisomic for chromosome 16 when it was noted that the intensity of restriction fragments associated with Rfp-Y increased with increasing copy number of chromosome 16. Further evidence that Rfp-Y might be located on chromosome 16 was obtained when individuals trisomic for chromosome 16 were found to transmit three Rfp-Y haplotypes. Finally, mapping of cosmid cluster III of the molecular map of chicken MHC genes (containing a MHC class II gene and two rRNA genes) to Rfp-Y validated the assignment of Rfp-Y to the MHC/NOR microchromosome. A genetic map can now be drawn for a portion of chicken chromosome 16 with Rfp-Y, encompassing two MHC class I and three MHC class II genes, separated from the B system by a region containing the NOR and exhibiting highly frequent recombination.

Animals↗
PubMed1996

Use of excluded volume to increase the heterogeneity of pore size in agarose gels.

When testing theoretical models that quantitatively describe the sieving of macromolecules during gel electrophoresis, investigators have been limited by absence of control of the heterogeneity of the size of pores in the gel. In a recent study performed by electron microscopy of thin sections (G. A. Griess et al., J. Struct. Biol. 1993, III, 39-47), pore size heterogeneity has been increased for agarose gels by a combination of both derivatization and molecular weight reduction of the polysaccharide chains of agarose. In the present study, pore size heterogeneity is increased by a mechanism that appears to have an origin different from the origin of this previously observed increase in heterogeneity: Pore size heterogeneity is increased by addition of a polyethylene glycol (PEG) of high molecular weight (18,500) to molten agarose before gelation. In contrast, the use of a lower molecular weight PEG (either 4,000 or 7,500) causes the formation of micron-sized precipitates within a gelled network of agarose fibers. Thus far, the PEG-induced heterogeneity of pore size occurs primarily in 100-1,000 microns scale zones separated from each other by interzone regions of decreased agarose fiber density. More uniform gels are needed for the study of sieving.

Dose-Response Relationship, Drug↗
PubMed1996

Characterization of Mhc genes in a multigenerational family of ring-necked pheasants.

Little is known about the major histocompatibility (Mhc) genes of birds in different taxonomic groups or about how Mhc genes may be organized in avian species divergent by evolution or habitat. Yet it seems likely that much might be learned from birds about the evolution, organization, and function of this intricate complex of polymorphic genes. In this study a close relative of the chicken, the ring-necked pheasant (Phasianus colchicus), was examined for the presence and organization of Mhc B-G genes. The patterns of restriction fragments revealed by chicken B-G probes in Southern hybridizations and the patterns of pheasant erythrocyte polypeptides revealed in immunoblots by antisera raised against chicken B-G polypeptides provide genetic, molecular, and biochemical data confirming earlier serological evidence for the presence of B-G genes in the pheasant, and hence, the presence of a family of B-G genes in at least a second species of birds. The high polymorphism exhibited by the pheasant B-G gene family allowed genetic differences among individuals within the small experimental population in this study to be detected easily by restriction fragment patterns. Further evidence was found for the organization of the pheasant Mhc class I and class II genes into genetically independent clusters. Whether these gene clusters are fully comparable to the B and Rfp-Y systems in the chicken or whether yet another organization of Mhc genes has been encountered in the pheasant remains to be determined.

Amino Acid Sequence↗
PubMed1996

Improved human zygote development in a modified Ham's F10 medium in vitro.

PURPOSE: Our purpose was to determine the effect of modified Ham's F10 media with and without glucose, hypoxanthine, phosphate, and transition metals (MM) on human embryo development. METHODS: Patients with at least one zygote were randomized by alternate assignment to one of the treatment groups. The treatment groups were as follows: normal Hams F10, MM, and MM with 0.5 mM glucose (LGMM). Patients were undergoing in vitro fertilization and embryo transfer or frozen-thawed embryo transfer. Zygotes (fresh and frozen-thawed) were incubated in one of three media for 24 hr before transfer. The groups were compared with respect to embryo quality, number of embryos transferred, age of the patients, clinical pregnancy rate, and implantation rate. RESULTS: The clinical pregnancy rate and the implantation rate were significantly higher in the group of patients whose zygotes were cultured in MM. LGMM did not appear to improve the pregnancy outcome compared to normal Ham's F10. However, the quality of the embryos cultured in MM or LGMM appears to be superior to the normal Ham's F10 with respect to the number of excellent and good-quality embryos and embryos without fragments. CONCLUSION: A modified Ham's F10 medium (MM) without added glucose appears to be superior to normal Ham's F10 for culture of human zygotes for embryo transfer.

Culture Media↗
PubMed1996

Association between the Rfp-Y haplotype and the incidence of Marek's disease in chickens.

Certain haplotypes at the major histocompatibility (B) complex (Mhc) of the chicken provide an easily demonstrated influence on tumor formation following infections with Marek's disease virus (MDV). Recognition that there is a second histocompatibility complex of genes in the chicken, Rfp-Y, comprised of Mhc class I and class II genes, some of which are at least transcribed, evokes the question of whether this gene complex might also influence the outcome of MDV infections. To test this hypothesis, pedigree-hatched chicks in families from the original Rfp-Y-defining stock in which three Rfp-Y and two B system haplotypes are segregating were challenged with the RB1B strain of MDV. Birds with the Y3/Y3 genotype were found to have 2.3 times the risk of developing a tumor compared with birds with other Rfp-Y genotypes combined (P <0.02). Additionally, birds carrying the BR9/B11 genotype had 2.3 times the risk of tumor formation, relative to birds with the B11/B11 genotype (P <0.02). We found no evidence for an interaction between genotypes within the B and Rfp-Y systems. These data provide evidence that Rfp-Y haplotypes, as well as B haplotypes, can significantly influence the outcome of infection with MDV.

Animals↗
PubMed1996

Yeast infection of sperm, oocytes and embryos after intravaginal culture for embryo transfer.

OBJECTIVE: To report a case of an embryo culture infected with Candida albicans after intravaginal culture. DESIGN: Case report. SETTING: Private infertility practice and university medical center. PATIENT: A couple with tubal and male factor infertility. INTERVENTIONS: Superovulation, oocyte recovery, Percoll sperm preparation, and intravaginal culture of sperm and oocytes in a tissue culture tube. MAIN OUTCOME MEASURES: Yeast infection of sperm, oocyte, and embryo culture. RESULTS: Candida albicans infection occurred in the sperm, oocyte, and embryo culture when cultured in a sealed tube in the vagina. Candida albicans also was found in the prepared sperm suspension culture in a separate tube kept in a 37 degrees C incubator. CONCLUSIONS: Infection of the embryo culture with C. albicans probably occurred when contaminated sperm was added at the time of insemination. Sperm preparation by the Percoll gradient centrifugation failed to eliminate C. albicans in the semen.

Adult↗
PubMed1996

RAPD analysis reveals low genetic variability in the endangered light-footed clapper rail.

Numbers of light-footed clapper rails Rallus longirostris levipes, an endangered bird inhabiting southern California salt marshes, have substantially declined from historic levels. RAPD (randomly amplified polymorphic DNA) analysis was employed to assess the genetic variability within and among four of the largest remaining light-footed clapper rail populations. A single, larger population of the endangered Yuma clapper rail Rallus longirostris yumanensis was used for comparison. A total of 325 RAPD primers were tested on DNA from a subset of five clapper rails composed of a single representative for each of the four light-footed clapper rail populations and a representative for the single Yuma clapper rail population. Of the 1338 amplified bands (loci) surveyed in these five representative birds, approximately 1% were polymorphic, indicating the level of differentiation across all loci is quite low. Nine primers yielding these 16 polymorphic bands were used to analyse 48 individuals from five populations. Five of these bands were polymorphic in both subspecies, six were polymorphic only within the light-footed clapper rails, and five were polymorphic only within the Yuma clapper rail samples. Considering the few bands that were polymorphic among the light-footed clapper rail populations, a surprisingly high level of population differentiation (GST = 0.28) was found. This is in accord with the results of AMOVA analyses which show that a fairly high percentage of the limited variability among the rails is due to either differences between subspecies or differences between the light-footed rail populations. Because inbreeding depression is suspected and overall genetic distances between populations are low, movement of light-footed clapper rails from larger populations into smaller ones might be considered as a management strategy. Employing RAPDs as one of a series of assays is useful in revealing the population structure of genetically depauperate species.

Analysis of Variance↗
PubMed1996

Medical approaches to gambling issues--I: The medical condition.

Gambling is a common human behavior. People who gamble encounter physicians. At times, gambling can produce adverse consequences for the player. Persistence of gambling despite adverse consequences can be called problem gambling. Roughly 1% of adults and 3% of adolescents exhibit signs of a medical disorder defined as pathological gambling. In many areas, including Wisconsin, gambling is increasing in legality, availability, and prevalence, and with it, pathological gambling is increasing in prevalence. This paper provides a descriptive review of gambling behaviors and the condition of pathological gambling, in the hope of increasing the awareness of practicing physicians, medical educators and researchers, and public policy makers, about what is known about these behaviors and the features of gambling illness that may present in a clinical setting. A companion paper focuses on the opportunities for constructive clinical activity by physicians regarding gambling problems.

Adult↗
PubMed1996

Medical approaches to gambling issues--II: The medical response.

Gambling behaviors cover a spectrum from an enjoyable benign form of social entertainment to a disabling and potentially lethal medical condition. A companion paper, Medical Approaches to Gambling Issues--I: The Medical Condition, provides a literature review of gambling in its pathological and nonpathological forms. Physicians encounter patients who gamble, patients who have a treatable disorder of pathological gambling and family members of problem and pathological gamblers. This paper is intended to aid practicing physicians in their care of their patients who gamble and experience problems related to gambling, as well as in the care of those among their patient caseload who are symptomatically affected by someone else's gambling.

Behavior Therapy↗
PubMed1995

Lectin-biotin assay for slime present in in situ biofilm produced by Staphylococcus epidermidis using transmission electron microscopy (TEM).

A lectin-biotin assay was developed for use in the specific detection of slime produced by Staphylococcus epidermidis RP62A and M187sp11 grown in a chemically defined medium. Mature biofilm was formed on polyvinylchloride (PVC) disks using a combined chemostat-modified Robbins device (MRD) model system. Specimens fixed in situ were: 1) stained with ruthenium red; 2) reacted overnight with biotin-labeled lectins (WGA, succinyl-WGA, Con A, or APA) followed by treatment with gold-labeled extravidin; or 3) reacted with antibodies against S. epidermidis RP62A capsular polysaccharide/adhesin (PS/A) using an immunogold procedure. WGA and succinyl-WGA (S-WGA), which specifically bind N-acetylglucosamine, were shown by TEM to react only with slime, both cell-associated and exocellular. In contrast, Con A, APA and anti-PS/A reacted with the bacterial cell surface but did not react with slime. These results indicate the usefulness of WGA lectin as a specific marker for detection of the presence and distribution of slime matrix material in S. epidermidis biofilm.

Biocompatible Materials↗
PubMed1995

Selective expression of major histocompatibility complex (MHC) antigens and modulation of T-cell differentiation in chickens with increased MHC-chromosome dosages.

Increased dosage of genes belonging to the immunoglobulin superfamily may be responsible for some of the less noticeable but targeted phenotypic disturbances seen in trisomy conditions of humans and animals. We used an avian aneuploidy model to study the specific effects of extra major histocompatibility complex (MHC)-microchromosome dosage on the progression of thymocyte differentiation through a broad period of embryonic and neonatal development. The particular goal in the present investigation was to determine whether a reduction in the number of thymocytes, previously observed in the developing thymus of MHC aneuploids, is accompanied by particular alterations in thymocyte differentiation. We hypothesized that the subpopulation structure and/or developmental pattern for thymocyte differentiation are characteristically perturbed (delayed or modified) by increased MHC-chromosome dosage in cells. The regulation of MHC surface antigen expression in aneuploid thymocytes was also studied to detect dosage-dependent expression for one and possibly more sub-regions (class I, II, IV) of the avian MHC. Surface densities of MHC class I antigens on thymocytes were increased significantly at all ages studied, for example by 15% and 45% in trisomics and tetrasomics, respectively at 22 days post-hatching. The surface density of CT1 antigen, a thymocyte-specific marker, was also increased in a dosage-dependent manner, but only in juveniles. Increases in the proportion of alpha beta 1, TCR+ and CD3+ thymocytes were observed in juveniles, with no alterations in other TCR-expressing thymocytes. No major alterations in CD4 and CD8 thymocyte populations were observed. These results demonstrate a targeted effect of extra MHC-chromosome dosage towards enhanced class I and CT1, and not class II or IV, expression. The increased MHC-microchromosome dosage appears to influence primarily immature thymocytes expressing alpha beta 1 TCR and CD3.

Aneuploidy↗
PubMed1995

Effects of age and long-term ovariectomy on the estrogen-receptor containing subpopulations of beta-endorphin-immunoreactive neurons in the arcuate nucleus of female C57BL/6J mice.

We have reported a decrease in the number of arcuate nucleus (ARC)-immunoreactive beta-endorphin neurons in old (24 months) female C57BL/6J mice versus young (5 months) mice. Here, we have tested by immunocytochemistry whether age-related changes in beta-endorphin neuron numbers are selective for beta-endorphin neurons which do or do not contain estrogen receptors (E2R). We also compared beta-endorphin neuron number in mice with short- (S) and long-duration (L) ovariectomy (OVX), since the latter may protect against neuroendocrine aging. Mice were studied at 5 (young), 12 (middle-aged), or 23-24 months (old). When the mean number of neurons per tissue section (15 sections per animal) was examined, there were no significant differences between young and middle-aged S-OVX females for either beta-endorphin, E2R, or beta-endorphin/E2R neuron number. However, there were significant decreases in beta-endorphin-containing neurons in the oldest age group versus young females (young S-OVX: 74.4 +/- 11 (+/- SD) immunopositive neurons per tissue section, n = 10 mice; young L-OVX: 61.6 +/- 6.9, n = 6; old S-OVX: 45.7 +/- 9.9, n = 7; and old L-OVX: 37.5 +/- 7.3, n = 7). There were also decreases in beta-endorphin neurons which contained E2R in the oldest animals (young S-OVX: 16.6 +/- 6.4; young L-OVX: 13.7 +/- 1.3; old S-OVX: 9.2 +/- 1.8; L-OVX: 6.0 +/- 1.5) (p < 0.05 ANOVA). Both age (p < or = 0.001, two-way ANOVA) and ovarian status (p < or = 0.05) independently affected neuron number for both the beta-endorphin and beta-endorphin/E2R populations versus young mice. We tested whether the observed age and/or ovarian-related decreases were proportionally greater in the subpopulation of beta-endorphin neurons which contained E2R compared to the total beta-endorphin neuron population. In the oldest age group, there was no significant difference in the decrease with age in the population of beta-endorphin neurons which contained E2R and the total beta-endorphin population (p = 0.208). When we examined the E2R neuron population as compared to the beta-endorphin neuron populations, age-related decreases in the beta-endorphin neuronal population tended to be greater than the decreases seen in the E2R neuron population (p = 0.054 repeated measures ANOVA). The tyrosine hydroxylase (TH) neuron population was studied to test whether there were changes in another ARC neuron population.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1995

Age-related alterations in the expression of prohormone convertase messenger ribonucleic acid (mRNA) levels in hypothalamic proopiomelanocortin mRNA neurons in the female C57BL/6J mouse.

POMC processing is mediated by the prohormone convertases (PC1 and PC2). The cleavage of beta-endorphin-(1-31) is mediated by PC2. PC2 can also further cleave beta-endorphin-(1-31) to beta-endorphin-(1-27). We previously reported a significant increase in the proportion of beta-endorphin-(1-27) and -(1-27) forms in the arcuate nucleus (ARC) of the hypothalamus in middle-aged females with irregular estrous cycles (5-7 days) compared to young female C57BL/6J mice with regular cycles (4-5 days). Changes in processing enzymes may be a mechanism underlying this change. We compared ARC messenger RNA (mRNA) levels of PC1, PC2, and furin by Northern blot and in situ hybridization analyses in young, middle-aged, and old mice. Antisense complementary RNA probes to mouse PC1, PC2, and furin were radiolabeled and used in single label studies, alone or in combination with a mouse POMC digoxigenin-labeled complementary RNA probe for double label studies. For Northern blot analysis, young (4- to 5-month-old) normally cycling (4-5 days) mice at diestrus were compared to middle-aged (12- to 13-month-old) irregularly cycling (5-7 days) mice at diestrus. By Northern blot analysis, a significant increase (P < 0.05) in ARC PC2 mRNA levels was detected in middle-aged compared to young mice, but ARC PC1 and furin mRNA levels were unaltered. Single label in situ hybridization analysis confirmed these findings in the general neuron population. We also observed a significant reduction in ARC furin mRNA levels in old mice compared to either young or middle-aged mice. Double labeling in situ hybridization histochemistry demonstrated that PC2 mRNA levels were significantly increased (at least 2-fold) in POMC mRNA-containing neurons of middle-aged compared to young mice. Selective changes in PC2 mRNA levels in ARC POMC neurons are correlated with changes in beta-endorphin-(1-31) processing to beta-endorphin-(1-27)/(1-26) in middle-aged animals. Our data suggest that the natural age-related shift in beta-endorphin peptide processing is mediated by PC2.

Aging↗
PubMed1995

Hypothalamic processing of beta-endorphin in female C57BL/6J mice is altered at middle age.

beta-Endorphin (beta-endo) (1-31) is the active opioid peptide product of pro-opiomelanocortin processing. Further post-translational modifications of beta-endo(1-31) yield beta-endo(1-27), (1-26) and their acetylated forms which are considered to be opiate receptor antagonists. Mechanistically, alteration in opiatergic properties is likely to result in the loss of a number of physiological functions including reproductive capacity. The purpose of this study was to determine whether there are changes in the way beta-endo neurones process the peptide with age in female C57BL/6J mice. Pooled extracts of arcuate nucleus (ARC) and preoptic area (POA) of 3- to 4-month-old normally cycling (4-5 days at dioestrus), 12- to 13-month-old irregularly cycling (5-7 days at dioestrus), 23- to 24-month-old acyclic (in persistent dioestrus) animals were subjected to reversed-phase HPLC (n = 4 experiments). Column fractions were assayed for beta-endo-like-immunoreactivity by sequence-specific RIAs. The opiate receptor active as well as opiate receptor antagonist forms of beta-endo were present in both ARC and POA at all three age groups although their ratios varied. beta-Endo(1-31), the active opiate, was the predominant form in young animals. At middle age there was a threefold (P < 0.05, ANOVA) increase in the antagonist forms of beta-endo and this was associated with a significant (P < 0.05, ANOVA) increase in the ratio of antagonist to active forms. This was accompanied by a trend toward an increase in acetylated forms of beta-endo in middle-aged mice. HPLC profiles from hypothalami of old animals more closely resembled those of young females. The increase in the antagonist forms of beta-endo at middle age may contribute to a decline of opiatergic influences in the female C57BL/6J mouse and suggest a mechanism whereby alterations in opiate influence over gonadotrophin control may occur.

Aging↗
PubMed1995

Luteinizing hormone response to N-methyl-D, L-aspartic acid in the presence of physiological estradiol concentrations: influence of age and the ovary.

We have previously reported that the pituitary of intra-atrially cannulated old female C57BL/6J mice is as capable of responding to a GnRH challenge as is that of young females (10). We have observed elevated luteinizing hormone (LH) levels in ovariectomized (OVX) intra-atrially cannulated mice. Sustained physiologic levels of estradiol (E2) for 6 days suppressed circulating LH to intact levels. However, in that model, a bolus of E2 following E2 priming was unable to elicit an LH surge (Joshi et al., unpublished findings). The present studies were designed to examine: first, whether GnRH neurons are competent to release GnRH in the presence of tonic physiologic levels of E2 and, second, whether either age or the ovary can influence GnRH neuronal responsiveness. The N-methyl-D, L-aspartic acid (NMA)-evoked GnRH response was assessed indirectly by measuring LH in two groups of OVX C57BL/6J mice: short-term OVX (S-OVX) (1 week) mice were either prepubertal (5 weeks), postpubertal (10 weeks), young (5 months), middle aged (12 months), or old (24 months). Long-term OVX (L-OVX) mice were either young (5 months), or old (24 months) and OVX at puberty; middle-aged L-OVX mice were OVX at 8 months and examined at 12 months of age. Animals were administered physiologic levels of E2 by subcutaneous silastic capsule for 1 week before testing. LH secretion was inhibited by E2 in S-OVX mice of all ages. In no case did NMA overcome this inhibition in E2 primed S-OVX females. E2 also inhibited LH secretion in L-OVX mice of all ages, but NMA was able to overcome the E2 inhibition of LH secretion in L-OVX mice (young: 0.5 +/- 0.1, 0.84 +/- 0.19 ng/ml, first and second challenge, respectively; middle-aged: 0.46 +/- 0.1, 1.08 +/- 0.16 ng/ml; and old: 1.44 +/- 0.19, 0.99 +/- 0.27 ng/ml). This last effect was independent of animal maturity at the time of OVX or animal age at the time of experiment. These findings suggest that although the ovaries in the 24-month-old S-OVX mice had not produced enough E2 to alter the vaginal cytology for 2 +/- 0.5 months before the experiment, the ovarian modulation of the inhibitory effect of E2 on NMA-induced LH secretion was still present. The nature of the ovarian factor(s) modulating this effect is unknown.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗