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Biomedical subjects

R Landesman

Publications and source records attributed to R Landesman.

At least 37 records · Page 2Linked to original sources
PubMed1977

Screening for twin pregnancy.

A group of 590 women who, 4 to 5 weeks after their last menstrual period, were confirmed to be pregnant, as measured by the human chorionic gonadotropin (hCG) by radioreceptor assay. Nine of these women had serum hCG levels approximately twofold higher than the others and were suspected of having twin pregnancy. When these women were tested at 12 weeks of gestation, pelvic sonography confirmed twin pregnancies in all the nine cases. Serum hCG levels thus provide a simple, rapid, and easy method to detect twin pregnancy.

Chorionic Gonadotropin↗
PubMed1977

Human chorionic gonadotropin and its subunits in hydatidiform mole and choriocarcinoma.

Serum human chorionic gonadotropin (hCG) was measured by a radioreceptorassay (RRA) and radioimmunoassay (RIA) and serum hCG-beta and hCG-alpha by RIA in 10 patients with intact mole, 3 patients with choriocarcinoma, and 4 patients with hydatidiform mole during treatment. hCG levels by RRA were higher in 5 of 10 molar pregnancies and ranged from 20,900 to 100,000 ng/ml and from 30,000 to 100,000 ng/ml by RIA. hCG levels by RRA and RIA paralleled one another closely during treatment of hydatidiform mole. hCG-alpha was higher than hCG by RRA and RIA and hCG-beta in molar pregnancies, in the uterine venous blood draining a uterine choriocarcinoma, and during chemotherapy of choriocarcinoma. In 2 of 3 choriocarcinoma patients who eventually developed cerebral metastases, hCG-alpha increased while hCG and hCG-beta were declining or negative. hCG-beta was usually lower than hCG or hCG-alpha in all the cases studied. These results demonstrate the production of free alpha and beta subunits in trophoblastic disease. Further, due to the biospecificity, simplicity, and rapidity, the RRA of hCG is a sueful diagnostic aid during treatment of trophoblastic neoplasia until the levels fall to within the sensitivity range of the assay. Finally, the RIA of hCG, hCG-beta, and hCG-alpha, which requires several days, should be performed until they become negative or fall within normal range.

Choriocarcinoma↗
PubMed1977

Radioreceptorassay of luteinizing hormone-human chorionic gonadotropin in urine: detection of the luteinizing hormone surge and pregnancy.

A radioreceptorassay of luteinizing hormone (LH)-human chorionic gonadotropin (hCG), using plasma membranes of bovine corpora lutea, has been extended to the detection of the midcycle LH peak and subsequent pregnancy in morning and 24-hour urine samples on days 10 to 12 following ovulatiobjects as determined by radioreceptorassay and radioimmunoassay were 45 ng and 20 ng/ml of urine, respectively; in 24-hour urine samples, mean levels of 39 ng and 17 ng of LH/ml, respectively, were found. A sustained rise in hCG was detected by the radioreceptorassay from 10 to 12 days after conception, and by day 15 the hCG levels were in the range of the midcycle LH range; this finding was confirmed by the radioimmunoassay of hCG.

Adult↗
PubMed1977

Magnesium deficiency in embryos of Xenopus laevis.

Embryos of Xenopus laevis reared in media with various low (less than or equal to 10(-5) M) magnesium ion concentrations will exhibit differing degrees of a potentially lethal magnesium starvation syndrome depending on the ion concentration and rearing temperature. The higher the rearing temperature or the lower the magnesium ion content of the medium the more severely the syndrome will be expressed. (Normal development can be expected at temperatures 13-30 degrees C and magnesium ion concentrations greater than 10(-5)M to 10(-2) M.). The magnesium deficiency syndrome in Xenopus embryos is described in detail and compared with the normal and anucleolate conditions. The deficiency condition becomes manifest after hatching as retarded growth and differentiation with progressive paralysis and edema. At the same time alterations are observed in the pattern of soluble proteins. The use of magnesium ions as a probe for investigating developing systems is discussed.

Age Factors↗
PubMed1976

Results of the first 1000 radioreceptorassays for the determination of human chorionic gonadotropin: a new, rapid, reliable, and sensitive pregnancy test.

One thousand radioreceptorassays for human chorionic gonadotropin (hCG) for the diagnosis of pregnancy were analyzed under eight categories. The high sensitivity (50 pg/ml) and specificity, coupled with performance time of the assay (1 hour), provided a new modality for the early diagnosis and management of normal and abnormal pregnancy in the first trimester. The radioreceptorassay becomes positive 1 week after conception. In the normal pregnancy this assay has been 100% correct at the time of the first missed menses. All ectopic pregnancies demonstrated positive tests, and no false negatives occurred. On the other hand, a negative assay excluded ectopic pregnancy.

Abortion, Incomplete↗
PubMed1976

Detection of human chorionic gonadotropin in blood of regularly bleeding women using copper intrauterine contraceptive devices.

Highly sensitive and specific radioreceptorassay and radioimmunoassay of human chorionic gonadtropin (hCG) have been used in the detection of hCG in random serum samples during the luteal phase of the menstrual cycles of 200 women and in daily serum samples obtained a few days prior to expected ovulation through the luteal phase in 3 women with regular bleeding patterns and using a copper intrauterine device (IUD). Twelve to nineteen per cent of IUD users showed hCG in serum during the luteal phase, indicating that the presence of the IUD, while permitting fertilization, probably causes interference through degeneration of the blastocyst and consequent lack of implantation.

Chorionic Gonadotropin↗
PubMed1975

The use of a radioreceptorassay of human chorionic gonadotropin for the diagnosis and management of ectopic pregnancy.

The radioreceptorassay of human chorionic gonadotropin (hCG), with a sensitivity of 50 pg or 3 mIU/ml of plasma, has provided almost 100% reliability in detecting pregnancy after the first missed cycle. This test may be performed within 1 hour and is ideally suited to the clinical detection of ectopic pregnancy, especially in patients who require immediate surgical intervention. Thirteen patients with suspected ectopic pregnancy were evaluated by the radioreceptorassay, one of whom was followed with four separate determinations. The results of the assay were subsequently compared with those of hemagglutination pregnancy tests, clinical symptoms, and pathologic findings. All of the patients were diagnosed accurately by the radioreceptorassay, even when hemagglutination tests yielded a false indication of pregnancy. By this assay, the hCG levels during ectopic pregnancies are generally lower than those found during a normal intrauterine pregnancy; in addition, pregnancy may be detected much earlier (prior to the rupture) than is possible by hemagglutination tests. Furthermore, the diagnosis of ectopic pregnancy may be excluded for patients admitted to the hospital with acute abdominal emergencies.

Acromegaly↗
PubMed1975

Application of a radioreceptorassay of human chorionic gonadotropin in the diagnosis of early abortion.

A radioreceptorassay for human chorionic gonadotropin (hCG) was used to detect pregnancy as early as 6 to 8 days following conception and to predict spontaneous abortion as early as 8 to 10 days after conception in subjects whose hCG levels were lower than those occurring during normal pregnancy of the same duration. The evidence for the specific measurement of hCG was further provided by the correlation of plasma hCG levels measured by radioimmunoassay using antisera specific for hCG-beta and radioreceptorassay of hCG. By virtue of its sensitivity and specificity, the radioreceptorassay of hCG allowed early and accurate prediction of spontaneous abortion in 15 patients.

Abortion, Threatened↗