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R N Andersen

Publications and source records attributed to R N Andersen.

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

Fimbria-associated proteins of Bacteroides loescheii PK1295 mediate intergeneric coaggregations.

Bacteroides loescheii PK1295 serves as a coaggregation bridge between Streptococcus sanguis 34 and Actinomyces israelii PK14, two gram-positive oral bacteria that are otherwise unable to coaggregate. Whereas coaggregation with S. sanguis 34 is inhibited by lactose, no simple sugar was found that inhibited coaggregation with A. israelii PK14. Coaggregation-defective (Cog-) mutants of B. loescheii PK1295 were isolated for the purpose of identifying the surface components responsible for the interaction with each coaggregation partner. Selection for spontaneously occurring Cog- mutants gave rise to two phenotypic classes of mutants. Type I lost the ability to coaggregate with S. sanguis 34, whereas type II failed to coaggregate with either S. sanguis 34 or A. israelii PK14. Purified fimbriae from the parent agglutinated cells of both partners, and agglutination with S. sanguis 34 was inhibited by lactose. Denaturing polyacrylamide gel electrophoresis and immunoblot analysis demonstrated the presence of both a 75- and a 43-kilodalton (kDa) protein associated with parental fimbriae, but only a 43-kDa protein was seen with fimbriae prepared from the type I mutant. Neither polypeptide was found in similar preparations from the type II mutants. Our data suggest that coaggregation of B. loescheii PK1295 with both gram-positive partners is mediated by fimbria-associated proteins present on the surface of the gram-negative organism and that the 75- and 43-kDa polypeptides are responsible for the recognition of S. sanguis 34 and A. israelii PK14 cells, respectively.

Actinomyces↗
PubMed1986

Nonsteroidal substances that affect serum free testosterone.

Several steroid hormones affect free testosterone (FT) levels in blood by competing with testosterone for binding sites on testosterone-binding globulin (TeBG). However, the effect of endogenous nonsteroidal substances in serum has not been reported. Some of these potential modifiers of FT were studied using equilibrium dialysis. Nonesterified fatty acids at 0.9 mM elevated FT approx 10% at pH 7.4. Investigation of the curvilinear relationship of percent FT (pFT) vs pH showed that pH-dependent changes of testosterone binding to albumin were responsible for a small linear increase in pFT with decreasing pH. The greater portion of the curvilinear increase of pFT with decreasing pH was due to fatty acids competing with testosterone for TeBG binding sites. Ketone bodies significantly affected FT (7.5% elevation) only at levels found in diabetic ketoacidosis. Sodium ions improved binding 11% when 7 mM was compared to 157 mM sodium, but physiological changes in sodium would result in only +/- 1% changes in FT. Very low levels (0.03 mM) of calcium may be essential for normal testosterone binding to TeBG since 1.0 mM EGTA raised FT by 75%. This study shows that dialysis at 37 degrees C should not be performed overnight, that thimerosol should not be used as a preservative, and that the dialysis buffer should contain physiological concentrations of sodium and calcium.

Calcium↗
PubMed1986

Multigeneric aggregations among oral bacteria: a network of independent cell-to-cell interactions.

A radioactivity-based assay was developed to define the participation of radioactively labeled cell types within the milieu of unlabeled partners in multigeneric aggregates. The cell types in these multigeneric aggregations consisted of various combinations of 21 strains representing five genera of human oral bacteria. The coaggregation properties of each cell type, when paired individually with various strains, were delineated and were unchanged when the microbes took part in the more complex multigeneric aggregations. Competition between homologous labeled and unlabeled cells for binding to a partner cell type was achieved only when the homologous cells were mixed together before the addition of their partner cells. Attempts to displace a labeled cell type from an aggregate by subsequent addition of a large excess of the same unlabeled cell type were unsuccessful, which suggested that the forces that bound different cell types together were very strong and the cell-to-cell interactions were stable. However, a cell type that exhibited only lactose-reversible coaggregations with partners was easily and selectively released by the addition of lactose to multigeneric aggregates otherwise consisting solely of lactose-nonreversible cell-to-cell interactions. This not only indicates the independent nature of individual coaggregations but also suggests the involvement of lectinlike adhesins in these sugar-inhibitable coaggregations. Although the molecular mechanisms responsible for multigeneric aggregations are unknown, the principle of a common partner cell type serving as a bridge between two otherwise noncoaggregating cell types was firmly established by the observation of sequential addition of one cell type to another. Thus, competition, bridging, coaggregate stability, independent nature of interactions, and partner specificity are the key principles of adherence that form the framework for continued studies of multigeneric aggregates. While the human oral cavity is a prime example of a complex microbial community, collectively the community appears to consist of simple and testable individual interactions.

Actinomyces↗
PubMed1985

A theoretically sound and practicable equilibrium dialysis method for measuring percentage of free testosterone.

Free testosterone measured in serum equilibrated in vitro is considered a good index of biologically available testosterone even though a large part of free testosterone in vivo is derived locally from rapid dissociation of testosterone bound to albumin. The most accurate method for measuring free testosterone, however, is unsettled. The classical method--equilibrium dialysis--has been questioned because of the dilution of serum that it entails and the previous inability to achieve identical results with diluted and undiluted serum. Essentially identical measurements of free testosterone were achieved in diluted and undiluted charcoal-stripped serum by using the dialysis method and calculation reported here. The measured free testosterone in undiluted whole serum from women was only 4-6% lower than the estimated physiological values. These results were obtained using a validated calculation, controlling pH, using physiological bicarbonate buffer at 37 degrees C, maintaining a constant free ligand concentration for dilutions, measuring the water gain by the dialysis bag, and using highly purified labeled testosterone. The mean free testosterone for normal women was 0.17 ng/dl (0.11-0.23) and for hirsute women was 0.49 ng/dl (0.27-0.71). The testosterone not bound to testosterone-estradiol binding globulin, calculated from free testosterone and albumin concentrations, was close to the production rate/min of testosterone. The method should be adaptable to other ligands.

Dialysis↗
PubMed1985

Coaggregation of oral Bacteroides species with other bacteria: central role in coaggregation bridges and competitions.

Seventy-three freshly isolated oral strains representing 10 Bacteroides spp. were tested for their ability to coaggregate with other oral gram-negative and gram-positive bacteria. None coaggregated with any of the gram-negative strains tested, which included Capnocytophaga gingivalis, C. ochracea, C. sputigena, and Actinobacillus actinomycetemcomitans. Strains of Bacteroides buccae, B. melaninogenicus, B. oralis, and B. gingivalis failed to coaggregate with any of the gram-positive strains tested. However, six Bacteroides spp. coaggregated with one or more species of gram-positive bacteria. Most isolates of B. buccalis, B. denticola, B. intermedius, B. loescheii, B. oris, and B. veroralis coaggregated with strains of Actinomyces israelii, A. viscosus, A. naeslundii, A. odontolyticus, Rothia dentocariosa, or Streptococcus sanguis. The strongest coaggregations involved B. denticola, B. loescheii, or B. oris; 22 of 25 strains coaggregated with A. israelii. Only B. loescheii interacted with certain strains of S. sanguis; these coaggregations were lactose inhibitable and were like coaggregations between A. viscosus and the same strains of S. sanguis. In fact, B. loescheii and A. viscosus were competitors for binding to S. sanguis. Many bacteroides also acted as coaggregation bridges by mediating coaggregations between two noncoaggregating cell types (e.g., S. sanguis and A. israelii). Evidence for binding-site competition and coaggregation bridging involving noncoaggregating cell types from three different genera provides support for the hypothesis that these intergeneric cell-to-cell interactions have an active role in bacterial colonization of the oral cavity.

Actinomyces↗
PubMed1984

The effects of continuous androgen secretion on the hypothalamic-pituitary axis in woman: evidence from a luteinized thecoma of the ovary.

Hyperandrogenic states in women are often accompanied by disruption of gonadotropin secretion. However, the role of androgens per se in the pathogenesis of this abnormality is poorly understood. We report a woman with a virilizing ovarian tumor in whom the effects of continuous androgen secretion on the hypothalamic-pituitary axis were investigated in detail. A 29-yr-old woman with previously normal reproductive function, including prior fertility, was evaluated for amenorrhea and hirsutism. She had elevated peripheral serum levels of testosterone (T; 337-500 ng/dl) and androstenedione (A; 258-353 ng/dl). Her serum LH level was above the normal follicular phase range and was hyperresponsive to LHRH, whereas the FSH level was below normal early follicular phase levels and increased minimally in response to LHRH. A luteinized thecoma of the left ovary, shown by catherization of the ovarian venous blood to be secreting both T and A, was removed. Postoperatively, serum T and A levels returned to normal, and the patient had a normal ovulatory menstrual cycle in the 30 days after the operation, documented by daily determinations of plasma estradiol, progesterone, and gonadotropin levels. A repeat LHRH test in the follicular phase of the second postoperative menstrual cycle was completely normal. This case indicates that the characteristic abnormalities of gonadotropin secretion observed in hyperandrogenic states such as polycystic ovarian disease can result from chronic androgen secretion by an ovarian tumor and that normal folliculogenesis and gonadotropin secretion can be promptly restored by the elimination of the androgen excess.

Adrenocorticotropic Hormone↗
PubMed1983

Androgen parameters and their correlation with body weight in one hundred thirty-eight women thought to have hyperandrogenism.

The first objective of this study was to determine which plasma androgen assay or combination of assays would be the most useful in documenting hyperandrogenism in women with hirsutism, acne, oligomenorrhea, or unexplained infertility. Plasma levels of androstenedione (A), total testosterone (T), and dehydroepiandrosterone sulfate (DHEAS) were measured and free T (FTc) was calculated from the measured total T and T-estradiol-binding globulin binding capacity (TeBG-BC) in 138 consecutive women referred to our clinic for hirsutism, acne, oligomenorrhea, and/or unexplained infertility. FTc was elevated in 82% and was most frequently elevated parameter. DHEAS was elevated in 59% of the women, and 93% were noted to have hyperandrogenemia on the basis of a combination of FTc and DHEAS levels. The second objective of this study was to determine whether there was significant correlation between the androgen parameters and any of the clinical features. Body weight was significantly negatively correlated with DHEAS and TeBG-BC in those women with a normal DHEAS level but not in those with an elevated level. A strong positive correlation (simple and partial) was noted between body weight and plasma T levels in the whole group of patients, as well as in those with a normal or an elevated DHEAS level. It is suggested that the relationship between T and body weight is multifaceted. Conceivably, T could influence body mass by effects on food intake or through alterations in intermediary metabolism.

Acne Vulgaris↗
PubMed1983

Ligand-induced change in sedimentation behavior of human progestin receptors.

We determined the effect of ligand binding on the sedimentation behavior of cytosolic progestin receptors in human uterine leiomyomata, normal endometria and myometria. When cytosols were prelabeled with the tritiated progestin R5020, 4.4S and 7-8S receptors were demonstrated in all three uterine tissues; with postlabeling of fractionated gradients, 4.4S and 9-10S receptors were present. Sodium molybdate (20 mM) blocked the ligand-induced conversion of 9-10S to 7-8S receptors. The relative amount of 7-8S receptor increased with increasing amounts of ligand and time of incubation with ligand (up to 5 hrs); the amount of 9-10S receptor decreased with time. These data indicate that ligand binding to human uterine progestin receptors induces a change from a 9-10S to 7-8S form of receptor. Since molybdate blocks transformation of receptors and the ligand effect on receptor sedimentation, ligand binding to 9-10S receptor and the consequent conversion to 7-8S receptor may be a step preceding transformation of progestin receptors.

Centrifugation, Density Gradient↗
PubMed1983

Human ovarian 17 beta-hydroxysteroid oxidoreductase activity: a comparison of normal and polycystic ovarian tissues.

Ovarian tissue and ovarian venous blood were obtained from women undergoing wedge resection, and ovarian tissue was obtained from normally menstruating women who had an oophorectomy for medical reasons. A morphological evaluation was made of the wedged tissue. 17 beta-Hydroxysteroid oxidoreductase levels were determined as the 17-ketoreductase (17-KR) and 17 beta-dehydrogenase activities in both normal and wedged tissue. Plasma androstenedione (A) and testosterone (T) levels were measured in the ovarian venous blood. Low, but measurable, 17 beta-hydroxysteroid oxidoreductase activity was found in the mitochondria, microsomes, and cytosol. With whole, cell-free homogenates, mean 17-KR activity was not significantly different in normal tissues and polycystic tissues; mean 17-KR activity of corpora lutea was significantly greater than that of the other tissues. Mean 17 beta-dehydrogenase activity was not significantly different from 17-KR activity in the tissues studied. Ovarian venous A levels were higher than the reported mean ovarian venous A levels of normal women with only one exception; approximately half of the ovarian venous T levels were higher than reported mean ovarian venous T levels of normal women. The morphology of the wedge sections did not correlate well with the biochemical data.

17-Hydroxysteroid Dehydrogenases↗
PubMed1982

The effect of leupeptin on progestin receptors of human uterine tissues.

In preparation for studies of progestin receptor dynamics in human uterine tissues, we have investigated the effect of tissue handling and the protease inhibitor leupeptin on the molecular forms of progestin receptors in human endometrium, myometrium, and leiomyoma. Tritiated R5020 [17,21-dimethyl-19-nor-4,9-pregnadiene-3.20-dione) (promegestone)] was the labeled ligand, and sucrose density gradient ultracentrifugation was used to determine the sedimentation coefficients of the receptors. Scatchard plots of saturation analyses were used to determine the number of binding sites and dissociation constants. We found that rapid chilling of tissue at surgery was necessary to maintain specific progestin binding in myometrium, that leupeptin permitted demonstration of 8S receptors in myometrium and leiomyoma, and that 8S receptors were present in endometrium, with or without leupeptin. With careful handling of tissue and minimal homogenization, leupeptin may not be necessary to preserve 8S receptors in myometrium and leiomyoma cytosols; however, the use of leupeptin gives greater assurance that 8S receptors will be preserved. The number of binding sites varied from 0.6-2.0 pmol/mg cytosol protein, and the Kd values observed were between 1.7-6.9 X 10(-10) M.

Centrifugation, Density Gradient↗
PubMed1980

Response to repetitive luteinizing hormone-releasing hormone stimulation in hypothalamic and pituitary disease.

The gonadotropin response to 100 microgram of luteinizing hormone-releasing hormone (LH-RH) administered three times intravenously at 2-hour intervals was measured to ascertain whether this would distinguish between patients with hypothalamic and those with pituitary disease. Responses in two patients with Kallmann's syndrome were compared to those in patients with other forms of hypothalamic or pituitary disease, including weight-loss amenorrhea, panhypopituitarism, and hyperprolactinemia. The conclusion was that a triple-bolus LH-RH test is not adequate to distinguish patients who are potentially treatable with LH-RH from those in whom no stimulation can be anticipated.

Adolescent↗
PubMed1980

beta-Endorphin and beta-lipotropin plasma levels in hirsute women: correlation with body weight.

Based on the findings of elevated circulating beta-endorphin (beta-END) levels in genetically obese (fa/fa) fats and the reversal of the overeating of genetically obese (ob/ob) mice by naloxone, circulating beta-END and beta-lipotropin (beta-LPH) levels were measured in 8 hirsute, hyperandrogenic, oligo-amenorrheic women of varying weights. Circulating beta-END and beta-LPH levels were significantly elevated (p less than .001) above the levels in nonobese control subjects and were positively correlated with body weight (p less than .025). Based on these data and indirect evidence in the literature, we propose a role may exist for beta-END and/or beta-LPH in human obesity and in adrenal androgen secretion.

Adolescent↗
PubMed1977

Characterization of human ovarian oestradiol-17 beta oxidoreductase activity.

Oestradiol-17 beta oxidoreductase activity, which catalyzes the interconversion of oestrone and oestradiol, was investigated in preparations of human ovaries. The enzyme activities were localized primarily in the 105,000 X g supernatant fraction; dialyzed supernatant preparations were used in subsequent studies. The pH optima were 6.9 for reduction and 8.1 for 17 beta-dehydrogenation. The apparent Michaelis constants for oestrone and oestradiol were 1 X 10(-7) M and 5 X 10(-7) M, respectively. The enzyme activity was present with either NADP(H) or NAD(H), though (NADP(H) were the preferred cofactors. Non-aromatic steroids androstenedione, dehydroepiandrosterone, testosterone and 5-androstene-3beta,17beta-diol were poor substrates for the enzyme preparation. Methylation of the phenolic hydroxyl of oestrone and oestradiol resulted in slightly enhanced activities. The sulfhydryl reagent, N-ethylmaleimide, inhibited the reduction of oestrone. A dialyzed supernatant preparation retained approximately 79% of the original enzyme activity when stored at -20 degrees C for 6 weeks.

Estradiol↗
PubMed1976

Response of the binding capacity of plasma testosterone-estradiol-binding globulin to norethindrone, 2 mg., and mestranol, 0.1 mg., in polycystic ovarian disease.

The binding capacity of plasma testosterone-estradiol-binding globulin (TeBG) and testosterone (T) levels were measured in four women with proved polycystic ovaries and three women with a clinical diagnosis of polycystic ovarian disease before, during, and after administration of norethindrone, 2 mg., and mestranol, 0.1 mg. (N + M)...

Carrier Proteins↗
PubMed1976

The effectiveness of two oral contraceptives in suppressing plasma androstenedione, testosterone, LH, and FSH, and in stimulating plasma testosterone-binding capacity in hirsute women.

The effectiveness of two oral contraceptives in suppressing plasma androstenedione (A), testosterone (T), LH, and FSH and in stimulating testosterone-estradiol-binding globulin (TeBG) was evaluated in 39 hirsute women. Twenty-seven hirsute women received norethindrone 2 mg.-mestranol 0.1 mg. (Group I) and 12 received norgestrel 0.5 mg.-ethinyl estradiol 0.05 mg. (Group II). Hormone assays were performed before treatment and at the end of 3 weeks of therapy. Ninety percent of the women in both groups had an elevated plasma A and/or T. During treatment, plasma A,T, LH, and FSH were significantly reduced in both groups (p less than 0.01). In Group I, 78% of the women had a normal plasma A and T during treatment. In Group II, 83% of the women had a normal A and T during treatment. There was a greater increase in TeBG in Group I (p less than 0.01). It is concluded that these two oral contraceptives effectively suppressed the hyperandrogenism of most of the hirsute women.

Adolescent↗
PubMed1976

Deficient 17 beta-hydroxysteroid oxidoreductase activity in testes from a male pseudohermaphrodite.

17beta-Hydroxysteroid oxidoreductase (17 beta-HOR) activity in testicular tissue from a male pseudohermaphrodite (MP) who had elevated plasma LH and androstenedione (A) levels, and normal dehydroepiandrosterone (DHA) levels was compared by in vitro studies to that of testicular tissue from a normal man. The 17 beta-HOR activity from the MP was localized predominantly in the microsomal fraction, as it is in normal testicular tissue. With DHA, A, and estrone as substrates, the 17 beta-HOR activity of the MP was decreased in the presence of NADPH, but not NADH, in comparison with the normal. NADPH was the preferred co-factor for 17 beta-HOR from the normal testes, while 17 beta-HOR activity from the MP testes was less with NADPH than with NADH as cofactor. These results indicate that the inefficient testosterone production in the MP testes may be accounted for by a deficiency of NADPH-dependent 17 beta-HOR activity. Further studies suggested that 3 beta-hydroxysteroid oxidoreductase-isomerase (3 beta-HOR) was increased in the MP testes and was much greater than 17 beta-HOR activity with DHA as substrate. These findings largely explain the elevated plasma A levels with normal DHA levels, and suggest that DHA leads to A leads to testosterone was the major route of testosterone biosynthesis in the MP testes.

Androstenedione↗