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Dive into the research topics where George L. Flickinger is active.

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Featured researches published by George L. Flickinger.


Steroids | 1968

Metabolism of free and sulfoconjugated DHEA in brain tissue in vivo and in vitro.

Paul Knapstein; Amnon David; Chung-Hsiu Wu; David F. Archer; George L. Flickinger; Joseph C. Touchstone

Abstract Two rhesus monkey brains were perfused in vivo either with 14C-DHEA (dehydroepiandrosterone) and 3H-DHEA sulfate or with 3H-DHEA. Plasma from the jugular vein and the brain were analyzed for free and conjugated metabolites. Many more free than sulfoconjugated steroids were withdrawn from the blood. These were not stored to a large extent. Up to 16% of DHEA were metabolized to ring D hydroxylated Δ5-compounds. When fresh human fetal brain was incubated with 3H-DHEA, 5.9% of the free steroids were sulfurylated. 30% were converted mainly to ring D hydroxylated Δ5-metabolites.


Fertility and Sterility | 1986

Differences in ovarian stimulation in human menopausal gonadotropin treated woman may be related to follicle-stimulating hormone accumulation *

Zion Ben-Rafael; Jerome F. Strauss; Luigi Mastroianni; George L. Flickinger

Two groups of normal ovulatory women who displayed either a marked (high responders; HR) or a more subtle (low responders; LR) ovarian response to a fixed dose of human menopausal gonadotropins (hMG) were evaluated for differences in blood levels of hormones. Serum follicle-stimulating hormone (FSH) levels doubled during the first 3 days of treatment (to approximately 20 mIU/ml) in all patients; thereafter, the levels plateaued in LR but continued to rise steadily (to 35 mIU/ml) in HR. In the latter group, rise in estradiol (E2) and FSH was accompanied by an increase of luteinizing hormone (LH; two to five times) progesterone (P; four to eight times) testosterone (T; three to four times) and prolactin (PRL; 2 times) toward the end of the follicular phase. Positive correlation was found between FSH and E2 in HR and LR. Positive correlation was found, however, between LH, T, and P and between E2, P, and PRL only in HR. The extent of FSH accumulation in the circulation may be a principal factor in determining an individuals response to hMG therapy. Temporal changes of blood hormones indicated that the continuous rise in FSH levels in HR was associated with early luteinization of the follicles. Increased secretion of P in the follicular phase of these women (HR) probably synergized with the elevated E2 levels to elicit LH release. Similar changes in blood hormones were not found in LR.


Fertility and Sterility | 1989

Cortisol levels in human follicular fluid

Majid Fateh; Zion Ben-Rafael; C.A. Benadiva; Luigi Mastroianni; George L. Flickinger

This study shows that cortisol levels in follicular fluids in stimulated cycles were correlated with oocyte maturity and in vitro fertilizability. The levels were significantly higher than the concentrations found in spontaneous cycles. Our findings suggest that the presence of cortisol in follicular fluid may play a role in follicular development and oocyte maturation.


Fertility and Sterility | 1987

Dose of human menopausal gonadotropin influences the outcome of an in vitro fertilization program

Zion Ben-Rafael; C.A. Benadiva; Militza Ausmanas; Brenda Barber; Luis Blasco; George L. Flickinger; Luigi Mastroianni

This study compares outcomes of in vitro fertilization (IVF) in two groups of 57 patients when either 2 (group 1) or 3 (group 2) ampules of human menopausal gonadotropin (hMG) were administered daily. Treatment began on day 3 of the cycle and was discontinued when at least 2 follicles attained diameters greater than or equal to 1.5 cm. Human chorionic gonadotropin (hCG) was given either 24 or 48 hours after the last dose of hMG. Although serum estradiol levels were lower in group 1, the average number of oocytes retrieved (3.2 versus 2.9), fertilized (1.9 versus 2.0), and cleaved (1.7 versus 1.8) per completed cycle did not differ between groups 1 and 2. Likewise, the number of oocytes that fertilized abnormally was similar in both groups (0.5 versus 0.3/cycle). However, the number of atretic oocytes (0.03 versus 0.5/cycle) and the percent of oocytes recovered from the cul-de-sac (0 versus 7.2%) were significantly (P less than 0.05) lower in group 1. In group 1, administration of hCG 48 hours after the last dose of hMG was associated with a higher number of cleaving embryos (2.1 versus 1.5/cycle) and a higher pregnancy rate (34.8 versus 14.7%; P less than 0.05) when compared with injection at 24 hours. In group 2, the interval between hMG and hCG did not influence these results. Together, the associations between fewer oocytes that were atretic or recovered from the cul-de-sac, and a trend toward a higher pregnancy rate, suggest that follicular recruitment with 2 ampules of hMG is more appropriate than 3 ampules in an IVF program.


American Journal of Obstetrics and Gynecology | 1973

Plasma estrogens in postmenopausal women.

M.D. Rader; George L. Flickinger; G.O. deVilla; John J. Mikuta; George Mikhail

Abstract The concentration of plasma estrone and estradiol was measured in different groups of postmenopausal women; including physiologic menopause, castration menopause, and those who in addition to menopause had diabetes, hypertension, or cardiac disease. The mean values for estrone were 41 pg. per milliliter and for estradiol 13 pg. per milliliter. There was no statistical difference in the levels of plasma estrogen in all groups of postmenopausal women studied. In 3 individuals, studies of estrogens in ovarian vein blood suggested a nonovarian origin of estrogen.


Fertility and Sterility | 1988

Ovarian response of individuals to different doses of human menopausal gonadotropin

C.A. Benadiva; Zion Ben-Rafael; Jerome F. Strauss; Luigi Mastroianni; George L. Flickinger

Hormonal profiles were compared in 14 ovulatory women who were treated with two different doses of gonadotropins in successive in vitro fertilization cycles. All patients suffered from mechanical causes of infertility. Serum estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone (P) were measured daily during the follicular phase. Women were arbitrarily classified as high responders (E2 greater than 1000 pg/ml on the day of human chorionic gonadotropin administration, n = 8) or as low responders (E2 less than 1000 pg/ml, n = 6), according to the peak E2 levels during the cycle when they received 3 ampules of human menopausal gonadotropin (hMG). When patients were treated with 3 ampules of hMG, serum FSH, LH, and P concentrations increased significantly during the follicular phase in high responders but remained unchanged in low responders. When these patients were treated with 2 ampules of hMG, the temporal profiles of the hormones were similar, but the magnitude of increases in serum levels of gonadotropins and sex steroids was significantly reduced in high responders. The authors conclude that temporal individuality of endocrine profiles cannot be altered by varying the dose of gonadotropin. Increases in hormone levels accompanying a high response to hMG can, however, be dampened by lowering the dose. In contrast, hormone concentrations are not influenced by changing the dose of hMG in low responders.


Fertility and Sterility | 1986

Follicular maturation parameters associated with the failure of oocyte retrieval, fertilization, and cleavage in vitro

Zion Ben-Rafael; Gregory S. Kopf; Luis Blasco; George L. Flickinger; Richard W. Tureck; Jerome F. Strauss; Luigi Mastroianni

Follicular maturation parameters predictive of decreased success in human in vitro fertilization were evaluated in 104 gonadotropin-stimulated cycles. Falling estradiol (E2) levels correlated with decreased fertilization (1.9 oocyte/cycle) and cleavage (1.4 oocyte/cycle), when compared with cycles with increasing E2 (2.4 and 2.1 oocyte/cycle, respectively). Likewise, polyspermic fertilization was higher in the former group. Falling E2 levels after human chorionic gonadotropin (hCG) administration correlated with similar trends. Delaying hCG (24 to 96 hours) relative to the last dose of gonadotropin did not affect the total number of oocytes fertilized per cycle. However, polyspermic fertilization and cancellation rates were higher. Leading follicles growing beyond 2.3 cm (determined by ultrasound examination) were associated with decreased recovery, fertilization, and cleavage, and increased polyspermic fertilization. We conclude that ultrasonography and E2 monitoring can predict decreased fertilization and cleavage and should also be monitored after hCG administration.


General and Comparative Endocrinology | 1961

Effect of grouping on adrenals and gonads of chickens

George L. Flickinger

Abstract 1. 1. Adrenals and thyroids of birds kept in groups of six were significantly heavier than the adrenals and thyroids of heterosexual pairs kept at the same density. 2. 2. After sexual maturity the adrenal weights of cocks correlated reciprocally with social rank. 3. 3. Adrenal stimulation, as measured by lipid depletion, correlated well with the amount of social interaction within each group. 4. 4. Subordinate grouped cocks were found to have a slower testes weight gain, delayed onset of spermatogenesis, and degenerative changes in the testes in comparison to paired and grouped dominant males.


Annals of the New York Academy of Sciences | 1977

ESTROGEN AND PROGESTERONE RECEPTORS IN THE FEMALE GENITAL TRACT OF HUMANS AND MONKEYS

George L. Flickinger; Carlene Elsner; Doreen V. Illingworth; Eberhard K. Muechler; George Mikhail

Studies in laboratory animals have shown that responses of target organs to avarian hormones are influenced by the levels and intracellular location of specific steroid-binding proteins. I , * The cellular content of estrogen and progesterone receptors seems to be primarily regulated by the magnitude and duration of exposure of the tissues to circulating hormones. We have assessed endocrine regulation of human female genital tissues by measuring estrogen and progesterone receptors in different areas of the genital tract during the menstrual cycle, during administration of progestins and estrogens, and in some pathologic states. Other studies were performed on the genital tract of rhesus monkeys. In this primate model, the circulating levels of progesterone and estradiol were controlled by administration of hormones to castrated animals.


American Journal of Obstetrics and Gynecology | 1988

Collagen matrix influences the morphologic features and steroid secretion of human granulosa cells

Zion Ben-Rafael; C.A. Benadiva; Luigi Mastroianni; Carmen J. García; Justina M. Minda; Renato V. Iozzo; George L. Flickinger

Steroid secretion and structure of granulosa cells on floating collagen gels were compared with those of cells grown on plastic. Granulosa cells from follicles of gonadotropin-treated women were plated either onto dishes coated with type I collagen or onto plastic dishes. Medium containing serum was removed after 24 hours, defined medium was added, and the gel was floated. Medium was changed daily for 3 days, after which the granulosa cells were prepared for light and electron microscopy. Cells grown on collagen secreted significantly more estradiol and progesterone than those grown on plastic during the 3 days of culture. The round multilayered granulosa cells on collagen had abundant mitochondria and lipid droplets and they formed numerous intercellular junctions. On plastic surfaces, flat granulosa cells grew as a monolayer with few junctions and less abundant mitochondria or lipid droplets. We conclude that growth on floating collagen promotes structural changes of human granulosa cells that enhances cell interaction and secretion of steroid hormones.

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Luigi Mastroianni

University of Pennsylvania

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George Mikhail

University of Pennsylvania

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Luis Blasco

University of Pennsylvania

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C.A. Benadiva

University of Connecticut

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Jerome F. Strauss

Virginia Commonwealth University

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Chung-Hsiu Wu

University of Pennsylvania

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Frank Meloni

University of Pennsylvania

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Richard W. Tureck

University of Pennsylvania

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