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Biomedical subjects

H J Sander

Publications and source records attributed to H J Sander.

13 recordsLinked to original sources
PubMed1995

Inhibin and oestradiol-17 beta in antral follicles of various size classes of cyclic rats.

On the various days of the 5-day oestrous cycle of the rat, ovarian antral follicles were dissected out and grouped in five size classes. Four follicles of the same size class were homogenized jointly in medium, after which inhibin-like bioactivity, inhibin immunoreactivity and oestradiol-17 beta content were measured. In general, there was a significant correlation between immunologically and biologically active inhibin levels in the different size classes; overall correlation was 0.85 (n = 87, P < 0.00001). In the smallest antral follicles (classes 1 and 2) inhibin bioactivity was detected only during the first three days of the cycle. With increasing follicle size, inhibin bioactivity and immunoreactivity increased, with maximal activity present in the largest, i.e. preovulatory, follicles (class 5) during the last three days of the cycle (the day of oestrus denotes day 1 of the cycle). These results indicate that only follicles which reach the antral stage at oestrus, and are known to be recruited by the periovulatory FSH peak, acquire the potency to produce biologically active inhibin. This is the cohort of follicles from which selection of ovulatory follicles will normally take place. In contrast to inhibin, follicular oestradiol-17 beta concentrations were negligible until the last days of the cycle when oestradiol-17 beta was present in follicles larger than class 2; levels increased with increasing follicle size and a maximal level was found in preovulatory follicles at pro-oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Pre-clinical and clinical treatment of breast cancer with antiprogestins.

Antiprogestins form a new potential treatment modality for breast cancer and their mode of action has been assessed in vitro on several breast cancer cell lines, in vivo in rats with dimethylbenzanthracene (DMBA)-induced mammary tumours and in vivo in patients with metastatic breast cancer. In vitro in serum-free medium, the progestin Org 2058 and antiprogestins RU486 and Org 31710 caused a dose-dependently stimulated MCF7 cell growth. Both antiprogestins dose-dependently inhibited the oestrogen-stimulated proliferation of progesterone receptor (PgR)-rich T-47D cells in DCC medium. Inhibition by Org 31710 plateaued at 10(-8) M (74% inhibition), compared with RU486 at up to 10(-6) M (53% inhibition). No inhibition was observed at doses of 10(-12)-10(-6) M of both antiprogestins in the absence of oestradiol. The proliferation of the ZR-75.1 and MDA-MB-231 cell lines was not or only marginally affected by either antiprogestin. Rats with DMBA-induced mammary tumours given prophylactic treatment with RU486 displayed a doubled latency period. Antiprogestins were slightly more effective than tamoxifen or progestins in rats with existing tumours. Org 31710 sometimes showed a somewhat more pronounced inhibitory effect than the antiprogestins Org 31806 and RU486. Combined antiprogestational and anti-oestrogenic treatment showed striking additive growth inhibitory effects resulting in clear tumour remissions, in the presence of very strong suppression of oestrogen and PgRs. The growth inhibitory effect of luteinizing hormone-releasing hormone agonists was potentiated by antiprogestins.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Initial ovulation rate and follicle population after injection of inhibin-neutralizing antiserum in the late-prepubertal rat.

In late-prepubertal female rats passive immunoneutralization of endogenous inhibin was achieved by injection of inhibin antiserum. Effects on follicle population, timing of sexual maturation, ovulation rate at first and second oestrus and serum FSH levels were studied. Rats were injected with antiserum, (non-immune) control serum from castrated sheep (castrated serum) or their IgG fractions, or with saline on day 33 or 3 or 2 days (days -3/-2) before the expected day of first ovulation, day 38.5 +/- 0.2 (n = 70). Blood was collected from different subgroups at 8, 24 and 48 h, and at first and second oestrus after injection. At necropsy, ovaries were histologically prepared for differential counting of follicles (48 h and first oestrus) and counting of corpora lutea (CL; first and second oestrus) as an index of ovulation rate. Results from rats injected with either serum or its IgG fraction were not different, as was the case when rats were injected with either castrated serum or saline. Thus, results from groups treated with antiserum and antiserum IgG were combined and labelled 'antiserum', and the castrated serum, castrated serum IgG and saline-treated groups were combined and labelled 'control'. The activity of inhibin-neutralizing antibodies in the circulation of antiserum-treated rats was reduced by 43% between 8 h and second oestrus after injection, as determined by the binding of purified bioactive radioiodinated 31 kDa bovine inhibin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Ovulation rate, follicle population and FSH levels in cyclic rats after administration of an inhibin-neutralizing antiserum.

Ovulation rate, follicle growth, serum FSH and oestradiol concentrations were studied after a single intraperitoneal injection of inhibin antiserum in 5-day-cyclic rats. Control rats received (non-immune) serum from castrated sheep or saline. Rats were injected at 10.00 h on dioestrus-1 (D1), i.e. the day following the day of oestrus, or at 17.00 h on dioestrus-2 (D2). The ovaries were excised at necropsy 48 h after injection, or at first or second oestrus after injection. After routine histology fresh corpora lutea were counted and/or differential follicle counts were made. Results from rats injected with either (non-immune) serum from castrated sheep or with saline were not different and were therefore combined to form the control group. The activity of inhibin-neutralizing antibodies in the circulation of antiserum-treated rats was reduced by approximately 39% between 8 h and second oestrus after injection, as determined by the binding of purified bioactive radioiodinated 31 kDa bovine inhibin. Rats were injected on D1 and killed at first oestrus. The number of fresh corpora lutea was significantly higher in antiserum-treated rats than in controls (13.9 +/- 0.4 vs 11.8 +/- 0.4; P less than 0.05). Other rats injected on D1 were killed either 48 h or at the second oestrus after injection. Blood was collected 8, 16, 24 and 48 h and at first and second oestrus after injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Inhibin increases in the ovaries of female rats approaching first ovulation: relationships with follicle growth and serum FSH concentrations.

In order to relate various prepubertal events in a group of 95 late prepubertal female rats, the following data were obtained during the last 10 days before the day of first ovulation: amounts of ovarian inhibin-like activity (ILA) in some animals (n = 47); size and numbers of healthy (antral) follicles with a volume greater than or equal to 100 X 10(5) microns3 (or diameter greater than or equal to 260 microns) present per ovary in their litter-mates (n = 48); serum FSH concentrations in both groups. Rats were unilaterally ovariectomized to obtain an ovary for either estimation of ILA content or for histological procedures and counting of follicles. At the time of unilateral ovariectomy they were bled to obtain serum for estimation of FSH concentrations. Rats were kept until the day after the day of first ovulation to determine the time-interval between the day of unilateral ovariectomy and first ovulation. They were studied between 10 and 1 days (days -10 to -1, maturational age) before first ovulation. In addition, adult cyclic rats were bilaterally ovariectomized on different days of the oestrous cycle for estimation of ovarian ILA content. The amount of ovarian ILA was estimated in steroid-free ovarian cytosols using an in-vitro bioassay system with dispersed anterior pituitary cells and subsequent measurement of FSH and LH in the spent medium. The amount of ovarian ILA was about 83 units/ovary from days -10 to -5, and subsequently increased (P less than 0.005) to reach a maximum on day -1, the day of pro-oestrus (213 units/ovary).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Inhibin-like activity in ovarian homogenates of prepubertal female rats and its physiological significance.

The presence and physiological significance of ovarian inhibin-like activity (ILA) in immature rats was studied by measuring ILA in ovarian homogenates and by studying the short-term changes in serum concentrations of FSH and LH after unilateral or bilateral ovariectomy. Inhibin-like activity in ovarian homogenates was estimated using an in-vitro bioassay system with dispersed rat anterior pituitary cells and subsequent measurement of FSH and LH levels in the spent pituitary cell medium. Inhibin-like activity, expressed in units/ovary, was undetectable in 13-day-old ovaries, was present in 18-day-old ovaries (5.8 units/ovary) and rose significantly to a value of 29.1 units/ovary on day 23. Another significant rise was seen between 28 and 33 days of age, with ILA reaching a value of 66.4 units/ovary, a value still well below that found in adult dioestrous ovaries (155.6 units/ovary). In the bioassay no systematic dose-dependent influence on LH secretion was found. Serum concentrations of FSH after unilateral or bilateral ovariectomy at 18 days of age showed no change at 5h and a significant (P less than 0.05) increase compared with sham-operated controls at 24 h after operation. At 23, 28 and 33 days of age significant increases in FSH concentration were seen at 5 and 8 h after both unilateral and bilateral ovariectomy. At 24 h after unilateral ovariectomy, FSH had returned to the control values in these rats, whereas after bilateral ovariectomy a further increase in FSH was seen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Compensatory ovulatory mechanisms operative after first ovulation in rats unilaterally ovariectomized prepubertally.

Ovarian steroid contents and serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin were measured during the days after first ovulation in rats unilaterally ovariectomized in late prepuberty. In addition, follicle counts were made at second estrus and second metestrus. During the cycle following first ovulation, ovarian estradiol contents in unilaterally ovariectomized (ULO) rats were significantly increased as compared to intact rats on the day of metestrus, on diestrus 1 and on second estrus. Ovarian progesterone was significantly increased on the days of metestrus, on diestrus 1, second proestrus and second estrus, but no differences were seen in ovarian androgen contents. After ULO there was an indication of an augmented FSH surge at the first and the second ovulation. Follicle counts revealed that the total number of healthy as well as of atretic antral follicles on the day of second estrus was significantly increased after ULO, due to increased numbers of the smallest antral follicles. At second metestrus the number of larger antral follicles (350-500 micron 3) and the total number of healthy antral follicles was higher after ULO. It is concluded that the compensatory process after ULO involved increased recruitment of small antral follicles. Activities in the remaining ovary were not simply doubled but a new hormonal balance was established.

Animals↗
PubMed1984

Inhibin-like activity in media from cultured rat granulosa cells collected throughout the oestrous cycle.

Granulosa cells of antral ovarian follicles from adult 5-day cyclic rats were cultured on each day of the cycle. The rat granulosa cell conditioned medium (rGCCM) was harvested and renewed on each day of a 4-day culture period. Inhibin-like activity and progesterone were estimated in rGCCM using an in-vitro bioassay system with dispersed rat anterior pituitary cells and radioimmunoassay respectively. Removal of steroids from rGCCM with dextran-coated charcoal was effective and did not significantly change the inhibin-like activity of the treated samples. On day 1 of culture the inhibin-like activity of rGCCM for each day of the oestrous cycle was 20-90% higher than on days 2, 3 and 4 of culture when low and constant levels were observed. Media collected after culture on days 1 and 2 from pro-oestrous cells contained larger amounts of inhibin-like activity than media collected on the other days of the cycle. On day 1 of culture, rGCCM from pro-oestrous cells contained higher concentrations of progesterone than that from cells collected on the other days of the cycle. On days 2, 3 and 4 progesterone levels in rGCCM were undetectable (less than 320 pmol/l) except in media from pro-oestrous cultures on day 2. Addition of FSH (62 micrograms/l) to granulosa cell cultures in medium with or without 10% fetal calf serum (FCS) did not alter the inhibin-like activity of rGCCM from pro-oestrous cells. The presence of FCS maintained the production of inhibin-like activity since rGCCM from cells cultured without FCS was devoid of FSH-suppressing activity after 3 days of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Immunocytochemical localization of fibrinogen, platelet factor 4, and beta thromboglobulin in thin frozen sections of human blood platelets.

Affinity-purified monospecific antibodies against human fibrinogen and the platelet-specific proteins platelet factor 4 and beta thromboglobulin were used to localize these antigens in thin and ultra-thin frozen sections of mildly fixed, washed human blood platelets. By immunofluorescent double-labeling experiments the distribution of fibrinogen was compared to that of platelet factor 4 and beta thromboglobulin. All three antigens occurred in virtually all platelets and showed and identical, dotlike distribution. For immunoelectron microscopy we used protein A-colloidal gold on ultra-thin frozen sections to visualize the specific reaction indirectly. The staining for platelet factor 4, beta thromboglobulin, and fibrinogen localized exclusively over alpha-granules of washed platelets. Within the granules, platelet factor 4 was localized preferentially in the electron dense, alpha-granule nucleoid, whereas fibrinogen was more predominant in the electron-lucent granule periphery. Beta thromboglobulin localization did not show a preferential intragranular distribution.

Antigens↗
PubMed1983

Changes in serum concentration of luteinizing hormone in the female rat approaching puberty.

Concentrations of LH in the serum were estimated in rats bled either once or twice during a 15-day period preceding first ovulation. In rats bled once (between 09.00 and 17.00 h) serum concentrations showed little change between 15 and 9 days before first ovulation and averaged 16 micrograms/l (days -15 to -9). A shift in LH level, to a mean of 31 micrograms/l, was seen on day -8, whereafter LH concentrations increased gradually. Basal LH values of less than 10 micrograms/l were only found until day -4. The finding that LH values increased with age was confirmed by data from rats bled twice with an interval of greater than or equal to 3 days between bleedings. Furthermore, both in rats bled twice at 11.00 h and in rats bled twice at 15.00 h LH concentrations were significantly higher in the second sample. Both morning (11.00 h) and afternoon (15.00 h) LH concentrations in rats bled once also indicated a rise in LH concentrations with age but it became apparent that only morning values showed a shift in LH concentration (from approximately 15 to approximately 42 micrograms/l) from day -9 to day -8. In contrast, mean afternoon values showed a gradual increase from day -15 on. From day -8 on the number of rats with LH values greater than or equal to 50 micrograms/l increased, and from day -5 on they were more frequent at 15.00 than at 11.00 h. Thus a clear increase in LH secretion, most likely of a pulsatile nature, was found in the female rat approaching puberty. The correlation in time and possible functional relationship with late-prepubertal follicular growth is discussed.

Animals↗
PubMed1982

Estimation of inhibin-like activity in spent medium from rat ovarian granulosa cells during long-term culture.

Granulosa cells were isolated from antral follicles of intact, adult female rats by treatment with EGTA and hypertonic sucrose, and were kept in culture for 1, 15 or 37 days. The amount of inhibin-like activity in spent rat granulosa-cell media (rGCCM) was assessed by using a bioassay for inhibin (measurement of the unstimulated release of FSH and LH by pituitary cells in culture). After 1 day in culture, inhibin-like activity was detected in rGCCM of 0.016-0.8 X 10(5) cultured granulosa cells per dish. In the bioassay, maximal suppression of FHS occurred when 0.8 X 10(5) granulosa cells were plated. With this or a larger number of cells in long-term cultures, pooled rGCCM, collected up to 37 days after plating, suppressed levels of FSH (and not of LH) in the inhibin bioassay in parallel with the suppression found after addition of charcoal-treated bovine follicular fluid (bFF), which served as a standard. The amount of inhibin-like activity of rGCCM (relative to the amount present in bFF, which was given a potency of 1) ranged between 0.05 and 0.90 X 10(-3). Release of inhibin-like activity could not be estimated on day 4, and was low from days 29 to 37 in culture. Except after 1 day of culture, no substantial amounts of progesterone were detected in the media. It is concluded that granulosa cells collected from adult, intact female rats have and retain the capacity to secrete inhibin-like activity in vitro, under basal conditions in long-term cultures.

Animals↗
PubMed1981

Binding of factor VIII-von Willebrand factor to human arterial subendothelium precedes increased platelet adhesion and enhances platelet spreading.

Time-dependent studies of platelet adhesion and binding of F VIII-VWF to human arterial subendothelium were carried out in vitro, using 51Cr-labeled platelets and 125I-labeled F VIII-VWF. Rapid binding of F VIII-VWF was found, resulting in a constant surface concentration after 1 to 2 min of perfusion. The number of platelets adhering in the first minute is similar in the absence of F VIII-VWF, but the platelet coverage is about twofold higher perfusions of 2 to 5 min in the presence of F VIII-VWF. Thus binding of F VIII-VWF precedes the increase in platelet adhesion, in line with our previous studies on the role of subendothelium-bound F VIII-VWF. By morphological evaluation it was found that the number of contact platelets (nonspread platelets) is lower in the presence of F VIII-VWF. The ratio of contact platelets to spread decreases in time, however, at a higher rate when F VIII-VWF is present. This indicates that F VIII-VWF enhances platelet spreading arterial subendothelium and consequently that the spreading is impaired in VWD. The enhancement may be caused directly by F VIII-VWF or indirectly as the result of a better attachment of contact platelets.

Arteries↗