Thymic stroma exposed to arylhydrocarbon receptor-binding xenobiotics fails to support proliferation of early thymocytes but induces differentiation

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and 3,3',4,4'-tetrachlorobiphenyl (TCB), two ubiquitous environmental pollutants, accelerate thymocyte maturation, and eventually lead to thymus atrophy. These processes are mediated by binding of TCDD or TCB to the cytosolic arylhydrocarbon receptor (AhR) abundant in the thymus, which acts as a ligand-activated transcription factor. At several stages of their maturation thymocytes need the interaction with thymus stroma. We tested whether thymocytes themselves or the thymus stroma are targets of AhR-binding compounds for interference with thymocyte maturation. We depleted fetal thymus lobes from proliferating cells, i.e., thymocytes, by treatment with deoxyguanosine and recultivated them with immature thymocytes (CD4-CD8-), exposing either the stroma or the thymocytes to TCDD or TCB before recultivation. Although CD4-CD8- immature thymocytes could differentiate in TCB-treated stroma, expansion of the cells was severely impaired. Selective exposure of thymocytes to AhR-binding compounds likewise did not impair the capacity of differentiation of CD4-CD8- thymocytes. These cells, however, could expand when transferred into new lobes that had not been exposed to TCDD or TCB. TCB treatment of fetal thymi leads to an accumulation of phenotypically mature CD4-CD8+ cells. We show here that these cells do not belong to the transient CD4-CD8+ thymocytes, as previously suggested, because in recultivation experiments they do not give rise to any thymocyte subset further down the maturation pathway.

Thymic stroma exposed to arylhydrocarbon receptor-binding xenobiotics fails to support proliferation of early thymocytes but induces differentiation

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and 3,3',4,4'-tetrachlorobiphenyl (TCB), two ubiquitous environmental pollutants, accelerate thymocyte maturation, and eventually lead to thymus atrophy. These processes are mediated by binding of TCDD or TCB to the cytosolic arylhydrocarbon receptor (AhR) abundant in the thymus, which acts as a ligand-activated transcription factor. At several stages of their maturation thymocytes need the interaction with thymus stroma. We tested whether thymocytes themselves or the thymus stroma are targets of AhR-binding compounds for interference with thymocyte maturation. We depleted fetal thymus lobes from proliferating cells, i.e., thymocytes, by treatment with deoxyguanosine and recultivated them with immature thymocytes (CD4-CD8-), exposing either the stroma or the thymocytes to TCDD or TCB before recultivation. Although CD4-CD8- immature thymocytes could differentiate in TCB-treated stroma, expansion of the cells was severely impaired. Selective exposure of thymocytes to AhR-binding compounds likewise did not impair the capacity of differentiation of CD4-CD8- thymocytes. These cells, however, could expand when transferred into new lobes that had not been exposed to TCDD or TCB. TCB treatment of fetal thymi leads to an accumulation of phenotypically mature CD4-CD8+ cells. We show here that these cells do not belong to the transient CD4-CD8+ thymocytes, as previously suggested, because in recultivation experiments they do not give rise to any thymocyte subset further down the maturation pathway.

The validity of the postcoital test for estimating the probability of conceiving

OBJECTIVE

We determined the prognostic value of the postcoital test in subfertile couples.

STUDY DESIGN

A retrospective study relates the result of the postcoital test to the occurrence of a spontaneous pregnancy. In a fertility center of a university hospital, data from the complete fertility workup of 956 couples who were examined because of infertility due to cervical hostility, male subfertility, or unexplained causes were collected. Statistical analysis was done with Cox regression.

RESULTS

The postcoital test result 9 to 12 hours after intercourse is strongly associated with future pregnancy during the first year after intake; the association is also present when the relation with other prognostic variables is taken into account.

CONCLUSIONS

The postcoital test result is a strong predictor of possible fertility within the following year.

3,3',4,4'-Tetrachlorobiphenyl inhibits proliferation of immature thymocytes in fetal thymus organ culture

The environmental pollutant 3,3',4,4'-tetrachlorobiphenyl (TCB) leads to thymic atrophy and immunosuppression, the former possibly causing the latter. TCB binds to the cytosolic aryl-hydrocarbon receptor (AhR) and transforms it into a DNA-binding state. The development of fetal thymocytes is severely affected by TCB and other AhR-binding xenobiotics, leading to a skewed pattern of thymocyte maturation stages. Murine thymocyte proliferation after exposure to TCB was studied in fetal thymus organ culture (FTOC). C57BL/6 fetus thymic lobes from day 15 of gestation were explanted and grown for 2, 4, 6, and 8 days in organ culture in the presence or absence of 3.3 microM TCB. Subsets of thymocytes were defined by CD4 and CD8 surface markers, and their cell cycle was analysed by DNA staining with 7-amino-actinomycin D (7-AAD). Exposure of fetal thymi in vitro to 3.3 microM TCB significantly reduced the total number of thymocytes, and fewer thymocytes were in S/G2M phase. The inhibition of cell proliferation induced by TCB treatment affected mainly the CD4-CD8- (double-negative, DN) and CD4-CD8+ (single-positive, SP) subsets, and these inhibition appeared mainly in more immature thymocytes, i.e. DNCD3- and CD8+CD3- subpopulations, whereas no effect of TCB on CD4+CD8+ (double-positive, DP) cell proliferative activity was observed. Analysis of the relation of cell proliferation and development of subsets in differentiating fetal thymocytes suggests that TCB enhanced thymocyte differentiation into mature CD8+ cells.

Differential in vitro methylation and synthesis of the 480-kilodalton corrinoid protein in Methanosarcina barkeri grown on different substrates

The 480-kDa corrinoid protein was significantly methylated in extracts of acetate- but not methanol-grown cells incubated with 14CH3OH, in part because of its decreased synthesis in cells grown on substrates other than acetate. In addition, a 200-kDa corrinoid protein was methylated in extracts of methanol- but not acetate-grown cells.

High voltage cryomicroscopy of human blood platelets

We have analyzed the ultrastructure of human blood platelets using ultrarapid freezing techniques followed by either freeze-substitution fixation or direct imaging of frozen hydrated specimens in a high voltage electron microscope. Freeze substitution preserved a regularity in the arrangement of microtubules when compared with chemically fixed specimens, as identified by a preferred center-to-center distance of 30 nm. Platelets imaged in the frozen hydrated state during different stages of adhesion and spreading were rich in cytoplasmic detail and revealed novel features not previously reported. Different granule populations were distinguished in the unstained samples, and the morphology of the cells was dramatically different from that of dried cells. Membrane channels formed as the cells spread, increasing in size and number as the number of granules in the cell decreased, suggesting a fusion of granule membranes with one another or an additional membrane system to release their contents. The data support the idea that direct cryoimaging is an optimum method for characterizing rapid structural changes of labile organelles in whole cells.

The significance of antisperm antibodies for sperm-cervical mucus interaction

An overview is presented of the effects of antisperm antibodies on the sperm-cervical mucus interaction. Antisperm IgA on spermatozoa or in cervical mucus can severely inhibit sperm penetration of cervical mucus and migration through it. Disturbance of the sperm-cervical mucus interaction is the only firmly established effect of these antisperm antibodies and leads to reduced fertility, as shown by a poor or negative result of the post-coital test. The presence of antisperm IgA in the male or female partner can be investigated more specifically with the sperm-cervical mucus contact test and can be confirmed by the sperm agglutination test on bromelinliquefied cervical mucus, by the mixed antiglobulin reaction test or by the immunobead test for IgA.

The origin of estrogens, progesterone, androgens and sex hormone binding globulin in peritoneal fluid in the immediate postovulatory period in normal ovulating women

In 20 women with proven fertility, one menstrual cycle was monitored by ovarian ultrasonography, laparoscopy and estimation of 17 beta-estradiol (E2), estrone (E1), progesterone, testosterone, androstenedione (Adion), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and sex hormone binding globulin (SHBG) in serum and peritoneal fluid. Three groups were studied, in which the peritoneal fluid was collected within 1, 3 and 5 days after ovulation. E1, E2 and progesterone levels in peritoneal fluid were highest shortly after ovulation and decreased with time. Testosterone and Adion in peritoneal fluid showed no changes, but peritoneal fluid levels were always higher than serum levels. No differences were found between the peritoneal fluid and serum levels of DHEA and DHEAS. SHBG in serum was always higher than in peritoneal fluid. The results are compared with reported steroid levels in follicular fluid from the literature and factors complicating the interpretation of steroid levels in peritoneal fluid are discussed.

Further details on sequelae at the cervical and tubal level of Chlamydia trachomatis infection in infertile women

OBJECTIVE

Relationships were studied between correlates of sexually transmitted diseases and chlamydial antibodies versus cervical mucus abnormalities and tubal abnormalities. An estimate was also attempted of the baseline prevalence of endogenous tubal abnormalities.

DESIGN

Prospective, descriptive.

SETTING

The outpatient department of the Fertility Unit of the Department of Obstetrics and Gynaecology of the Groningen University Hospital.

PATIENTS

Females (n = 184) of infertile couples consecutively visiting the department for evaluation and treatment.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Sexually transmitted disease correlates, cervical chlamydial infection, cervical and serum chlamydial antibodies, cervical mucus qualities according to World Health Organization criteria, tubal abnormalities.

RESULTS

Of the 175 cervical mucus samples studied, subnormal quality was because of imperfect timing of collection of 22 of the 23 subnormal samples. Tubal abnormalities correlated with more than five lifetime sexual partners (P less than 0.035), as well as with serum immunoglobulin G antibodies (P less than 0.05), which could be because of interaction between both risk factors.

CONCLUSIONS

No correlation was found between subnormal cervical mucus and chlamydial infection. Approximately two thirds of the tubal abnormalities seem unrelated to exogenous factors, although further study seems warranted.

Hypo-osmotic sperm swelling test does not assess fertilizing capacity of human spermatozoa

The hypo-osmotic sperm swelling (HOSS) test was performed on semen samples of five normospermic men from couples with prolonged infertility. Previously, the men had negative results of the zona-free hamster oocyte (ZFHO) test on two different ejaculates and the wives subsequently had become pregnant by donor insemination. A high swelling percentage (at least 60%) was found in all five men. It would appear that the HOSS test does not assess fertilizing capacity.

Studies on the decondensation of human, mouse, and bull sperm nuclei by heparin and other polyanions

We report heparin-induced decondensation of human, mouse, and bull sperm nuclei. Decondensation did not occur if the spermatozoa were intact but only if the membranes were severely damaged by freezing and thawing or by treatment with a detergent. If a disulphide bond reducing agent (thiol) was absent, decondensation of human sperm nuclei was usually a relatively slow process, with large interindividual variation. Mouse and bull sperm nuclei did not decondense in the absence of a thiol. With a thiol relatively low concentrations of heparin induced a rapid decondensation of the sperm nuclei of all three species. The decondensation activity was not specific for heparin; other polyanions were also active, with heparin being the most effective compound. It is supposed that heparin and other polyanions induce sperm nuclear decondensation because they deplete protamines from the chromatin. Thus the negatively charged phosphate groups of the DNA are no longer opposed by positively charged protamines. Consequently the mutual repulsion of unopposed phosphate groups causes the DNA molecules to stretch, which results in an increase of the sperm nuclear volume. Since heparin and other polyanions induce decondensation under physiological pH and temperature, polyanions might also be active in the oocyte.

The pin-hole cervical os; a small fertility problem

24 women with a so-called pin-hole cervical os during the pre-ovulatory phase of the menstrual cycle were detected in a group of 850 infertile couples. This cervical condition is rarely seen and is often combined with extreme oligomucorrhea and poor cervical mucus qualities. Sperm quality was so poor in four couples that they were excluded. Nine women were likely to have been exposed to diethylstilbestrol (DES) in utero. The pregnancy rate in this group was poor, only two pregnancies by coitus and none by intra-uterine AIH. In the other eleven women there was a strong correlation between a good result of the post-coital test (PCT) and the chance to achieve pregnancy. Four of the eight women with a good result of the PCT became pregnant by coitus. The three women with a poor result of the PCT became pregnant by intra-uterine AIH. It is possible that the fertility prognosis of a woman with a pin-hole cervical os during the pre-ovulatory phase of the menstrual cycle is unfavourably influenced by DES exposure in utero. A pin-hole cervical os in the pre-ovulatory phase of the menstrual cycle, without DES exposure, has probably no influence on fertility.

The significance of the zona-free hamster oocyte test for the evaluation of male fertility

Results of the zona-free hamster oocyte test were compared with pregnancy rates after coitus and after artificial insemination with donor semen (AID) in 322 primary infertile couples. Artificial donor insemination was offered if in the test the percentage of hamster oocytes with at least one decondensed sperm head (oocyte-sperm interaction rate) was less than 20. If the rate was less than 5, the pregnancy rate after coitus was significantly lower than in the group with a rate of greater than or equal to 5 to less than 20. In the former group, the pregnancy rate by AID was significantly higher than the pregnancy rate by coitus. We conclude that the zona-free hamster oocyte test is useful to predict the chance to achieve pregnancy in couples with unexplained infertility and to determine whether AID can increase this chance.

Epidemiological aspects of chlamydial infections and tubal abnormalities in infertile couples

Demographic and behavioural data on parameters of previous sexual behaviour were collected of both partners of 184 couples visiting the Department of Obstetrics and Gynaecology because of infertility. They were also screened for urogenital infection with Chlamydia trachomatis. Of 131 (71.2%) women, a diagnosis was established by hysterosalpingography and/or laparoscopy about the condition of their fallopian tubes. An unmarried status correlated significantly with a history of sexually transmitted disease, and with past promiscuity of male and female partner. Abnormalities of the fallopian tubes were significantly related to an unmarried status, a history of pelvic inflammatory disease, and past promiscuity. Male promiscuity was not shown to correlate with tubal abnormalities in the female partner. In only three couples, the partners reported to have had a sexual relationship with a partner other than the current one over the past year. The percentage of Chlamydia trachomatis-positive women of 1.8 and men of 3.0 in our study agrees with this low recent promiscuity. Chlamydia trachomatis was shown to be able to maintain itself for at least 4 years within a couple. The results are commented on.

Inspection of the ovaries and steroids in serum and peritoneal fluid at various time intervals after ovulation in fertile women: implications for the luteinized unruptured follicle syndrome

In 20 fertile women one menstrual cycle was monitored by ovarian ultrasonography, laparoscopy, and estimation of 17 beta-estradiol (E2) and progesterone levels in serum and peritoneal fluid (PF). Three groups were studied, performing the laparoscopy within 1, 3, and 5 days after ovulation. The results indicate that the opening in the corpus luteum remains at least during the first 1.5 postovulatory days. The process of the closure starts thereafter and has been accomplished 4 to 5 days after ovulation. Progesterone and E2 levels in PF follow a similar pattern, showing high levels in the first, decreasing levels in the second, and low levels in the last laparoscopy groups. Therefore the significance of inspection of the ovaries and hormone level estimation in PF depend on the timing of the laparoscopy in relation to the moment of ovulation, especially in the first 5 postovulatory days.

Is serology of any use when searching for correlations between Chlamydia trachomatis infection and male infertility?

Evidence on Chlamydia trachomatis causing male infertility is conflicting. We therefore collected data on epidemiological and clinical correlates of chlamydial infection and male fertility in 184 males visiting our Fertility Unit. Antibodies against Chlamydia trachomatis in serum and semen were also determined. Significant correlations were demonstrated between current chlamydial urethral infection and semen immunoglobulin (Ig) A, serum IgA and serum IgG. These parameters, however, were neither related to a history of sexually transmitted disease nor to lifetime number of sexual partners. Why, in the male, serology does not correlate with chlamydial infection in a more remote past is explained. Our data support, on epidemiological as well as serological grounds, the conclusion that chlamydial infection probably does not contribute significantly to male infertility.