Characterization of two mouse myeloma X sheep lymphocyte cell lines secreting sheep antibody.

Two mouse X sheep interspecific cell hybrids were obtained by fusing mouse myeloma cell line Sp2/O. Ag14 with sheep lymphocytes obtained from a lymph node antigenically stimulated with azo-benzene arsonate-ovalbumin (ABA-ova). The interspecific cell lines were characterized using immunochemical, karyotypic and molecular DNA techniques. Both cell lines secreted sheep IgG1 antibody specific for the ABA haptenic determinant. Karyotypic analysis revealed that cell lines 4.11 and 11.9 had modal chromosome numbers of 91 and 106, respectively. Although C-banded spreads confirmed that fusion between sheep and mouse cells had occurred, it was not possible to differentiate sheep from mouse chromosomes. However, DNA hybridization techniques showed that each line contained sheep repetitive sequence DNA. It was calculated that cell line 11.9 contained 17640 copies while cell line 4.11 contained 734 copies of the previously characterized sheep satellite DNA.

The subtle danger of symmetry restrictions in time series regressions, with application to fertility models.

PIP: It is widely known that linear restrictions involve bias. What is not known is that some linear restrictions are especially dangerous for hypothesis testing. For some, the expected value of the restricted coefficient does not lie between (among) the true unconstrained coefficients, which implies that the estimate is not a simple average of these coefficients. In this paper, the danger is examined regarding the additive linear restriction almost universally imposed in statistical research--the restriction of symmetry. Symmetry implies that the response of the dependent variable to a unit decrease in an expanatory variable is identical, but of opposite sign, to the response to a unit increase. The 1st section of the paper demonstrates theoretically that a coefficient restricted by symmetry (unlike coefficients embodying other additive restrictions) is not a simple average of the unconstrained coefficients because the relevant interacted variables are inversly correlated by definition. The next section shows that, under the restriction of symmetry, fertility in Finland from 1885-1925 appears to respond in a prolonged manner to infant mortality (significant and positive with a lag of 4-6 years), suggesting a response to expected deaths. However, unscontrained estimates indicate that this finding is spurious. When the restriction is relaxed, the dominant response is rapid (significant and positive with a lag of 1-2 years) and stronger for declines in mortality, supporting an aymmetric response to actual deaths. For 2 reasons, the danger of the symmetry restriction may be especially pervasive. 1st, unlike most other linear constraints, symmetry is passively imposed merely by ignoring the possibility of asymmetry. 2nd, modles in a wide range of fields--including macroeconomics (e.g., demand for money, consumption, and investment models, and the Phillips curve), international economics (e.g., intervention models of central banks), and labor economics (e.g., sticky wage models)--predict asymmetry. The conclusion of the study is that, to avoid spurious hypothesis testing, empirical research should systematically test for asymmetry, especially when predicted by theory.^ieng

Cytogenetic and DNA analyses of equine abortion.

Although no major structural or numerical abnormalities were found in the karyotypes of 12 aborted equine fetuses, two unrelated abortuses each carried a large polymorphism for the amount of heterochromatin in chromosome 1. In both karyotypes this chromosome was shown to be larger than its homolog. To determine the nature of the extra DNA in these chromosomes, equine DNA was isolated and characterized by buoyant density analysis. Equine mainband DNA had a buoyant density in neutral CsCl of 1.699 g/cm3, while the highly repetitive (dG+dC)-rich fraction had a buoyant density of 1.715 g/cm3. A radioactive RNA probe complementary to the purified satellite fraction was used for in situ hybridization to chromosomal spreads containing the enlarged chromosome 1. The results indicated that an increase in highly repetitive (dG+dC)-rich DNA was responsible for the increase in the size of the abnormal No. 1 chromosomes. While two of the 12 aborted fetuses exhibited marked heterochromatic dimorphisms, none of the karyotypes obtained from individuals with no family history of abortion exhibited such obvious polymorphisms.

An econometric test of structural change in the demographic transition.

"The structural change model of the demographic transition developed by Easterlin and others is explored empirically by applying the Brown, Durbin and Evans test of structural change to annual data from the transitions of Sweden, Norway, England and Wales, and Finland. The evidence strongly supports the structural change model over traditional models (based on gradual changes in explanatory variables), indicating a supply response of fertility to declining illness and death during the early stages of transition, and a demand response to the death of children during the latter stages, when families are likely to have achieved desired size."

Microbiological profile of the cervix in 1,000 sexually active women.

One thousand consecutive women who attended the Richmond Family Planning Association Clinic and who were to undergo a vaginal examination were asked to participate in a large prospective microbiological study. Participants were questioned about their sexual activity during the previous 12 months and any apparent signs of sexually transmitted disease. On examination the cervix was inspected for evidence of inflammation, ectopy or discharge and cervical swabs were taken microbiological assessment. Chlamydia trachomatis was isolated in 5.1% of women tested while Ureaplasma urealyticum and Mycoplasma hominis were found in 48.8% and 16.4% of women respectively. Significant associations were found between the number of sexual partners during the previous 12 months and the incidence of all 3 organisms. The carriage rate of the genital mycoplasmas was significantly affected by the type of contraception. In addition the association between the presence of the genital mycoplasmas and pelvic and cervical abnormalities was determined.

A prospective single-blind trial of minocycline and doxycycline in the treatment of genital Chlamydia trachomatis infection in women.

A total of 2124 women who attended the Richmond Family Planning Association Clinic in Melbourne consecutively were screened for the presence or absence of Chlamydia trachomatis. One hundred and three women were found to have Chl. trachomatis infection of the cervix and were invited to participate in a clinical trial of minocycline and doxycycline for the treatment of chlamydial infection. A 10-day course of either drug resulted in a negative result of a chlamydial culture for all patients at the follow-up assessment, which occurred between 11 days to 12 weeks after the therapy. Minocycline and doxycycline showed equal effectiveness in the eradication of mycoplasmas in over 80% of the treated patients. Minocycline appeared to have a slight advantage with respect to the resolution of the gynaecological symptoms that were associated with the chlamydial infection. The number of adverse events that were recorded during the trial was similar for both treatment regimens. Gynaecological symptoms were associated with chlamydial infection in approximately 50% of the women in the study. The lack of association between chlamydial infection and gynaecological symptoms has led to the instigation of routine testing for the presence of Chlamydia spp. in young women who have more than one sexual partner.

The prevalence of Chlamydia trachomatis in a young, sexually-active population.

A prospective study was carried out to determine the prevalence of Chlamydia trachomatis among 1000 sexually-active women at the Family Planning Association Clinic in Melbourne. This organism was isolated from the cervices of 5.1% of screened women. The women were surveyed about their sexual and gynaecological history, and symptoms of discharge or pain. It was found that women who gave positive results for the presence of Chlamydia were younger, and had commenced intercourse at an earlier age. Risk factors of multiple sexual partners, cervical ectopy and symptoms of urethritis were identified. We recommend that women who have more than one sexual partner should ask their partners to use condoms or, failing this, undergo annual screening for Chlamydia by immunofluorescent staining.

PIP: A prospective study was conducted over the December 11, 1985-May 29, 1986, period to determine the prevalence of "Chlamydia trachomatis" among 1000 sexually-active women at Melbourne's (Australia) Family Planning Association Clinic. An epidemiological and clinical history was recorded on a code sheet for study participants. Patients' ages, weights, coitarches, numbers of sexual partners during the last 12 months, and lengths of association with their present partners were recorded along with current contraceptive usage and the results of the last Papanicolaou smear-test. Patients also were asked about the presence of any symptoms of sexually-transmitted disease (STD). The appearance of the cervix was ascertained on speculum examination. Cervical specimens were taken from all women for microbiological assessment. 995 patients completed the patient record form. In 994 of these women, satisfactory swabs were taken for microbiological examination. The patients ranged in age from 15-50 years with a mean age of 25.4. The age at 1st intercourse (coitarche) ranged from 12-30 years and the number of sexual partners during the last 12 months from none to more than 10 partners. 573 (57.6%) women were using oral contraceptives (OCs), 141 (14.2%) no contraception, 101 (10.2%) an IUD, 118 (11.9%) a barrier method, and the remainder a progestagen-only pill, an injectable contraceptive agent, sterilization, or natural contraceptive methods. The previous cervical cytology was available for 775 (77.9%) women; 625 (80.6%) of these showed no abnormal cells. Of the 150 smear-tests that showed some abnormality, only 10 tests demonstrated dysplastic lesions. The rest were indicative of infection or a benign abnormality. Of the 994 cervical swabs, 51 (5.1%) swabs grew Chlamydia trachomatis. 42 swabs gave positive results of both immunofluorescence staining and culture; 9 swabs gave positive results of culture alone. An association between other factors and the presence or absence of Chlamydia was determined. When the ages of patients were compared, patients whose swabs gave positive results for Chlamydia were significantly younger than those whose swabs gave negative results. The women whose swabs gave positive results for Chlamydia began intercourse at a significantly younger age. The prevalence of Chlamydia trachomatis in a young sexually-active population was 5.1%; the group with multiple partner was identified as being at high risk (9.3% positive results). In trying to identify women with an increased risk of carrying Chlamydia, 5 factors appeared relevant: younger age at coitarche; a younger age; more than 1 sexual partner during the previous 12 months; symptoms of urethritis; and the presence of cervical ectopy.