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Biomedical subjects

K Thomas

Publications and source records attributed to K Thomas.

At least 307 records · Page 17Linked to original sources
PubMed1982

Purification of total cellular DNA from a single plant.

A procedure is outlined for purifying DNA from a single plant. A crude organelle pellet consisting of nuclei, chromatin, chloroplasts, and mitochondria is prepared, suspended, and immediately lysed with detergents. The DNA is separated from RNA, protein, and polysaccharides by banding it in CsCl density equilibrium gradients. Ethidium bromide is included in all buffers to act as an inhibitor of DNAase activity. The DNA prepared in this manner can be digested with restriction endonucleases, separated by gel electrophoresis, and used to identify specific genes by hybridization of cloned DNA sequences.

Chloroplasts↗
PubMed1982

Ovarian morphology during and after lynestrenol treatment around menopause.

In this histological study, the inhibition of continuous oral administration of lynestrenol 5 mg/day on the ovarian follicle and corpus luteum development was found to be extremely pronounced. Known estrogen - producing structures such as antral, mature follicles and corpora lutea were completely absent during treatment. Structures devoid of cystic function however, as persistent and cystic follicles and follicular cysts, seemed not to be influenced in their histological appearance and frequency. As the recovery of the cyclic ovarian function after cessation of the medication compares favorably with the spontaneous cycle, a continuous lynestrenol treatment of 5 mg/day can be regarded as a safe endocrinological regimen.

Adult↗
PubMed1982

Incidence of pathological factors not revealed by hysterosalpingography but disclosed by laparoscopy in 500 infertile women.

Hysterosalpingography and laparoscopy were performed in 500 infertile women. Results obtained by both techniques were compared. Taking into consideration only the tubal patency, the present study shows an agreement in 90% of cases. In total of 980 fallopian tubes examined, fimbrial conglutination was suspected in 79 tubes (8%) and diagnosed by laparoscopy in 154 tubes (15.7%). Peritubal adhesions with tubal patency are a frequent pathology (23.8%) and hysterosalpingography alone permits the diagnosis in only 68.8% of the cases confirmed by laparoscopy. Other additional findings by laparoscopy are frequent: endometriosis was found in 124 women. Isolated periovarian adhesions were disclosed in 48 women. The high incidence of unsuspected pathology is an additional support in favor of laparoscopy in each case of infertility.

Adult↗
PubMed1982

Incidence of the luteinized unruptured follicle syndrome in fertile women and in women with endometriosis.

One-hundred normal fertile women with normal luteal phase and 118 women with endometriosis underwent luteal phase laparoscopy before day 22. The luteal phase was ascertained by the presence of secretory endometrium and serum progesterone levels higher than 3 ng/ml. The ovaries were carefully inspected for the presence or absence of an ovulation ostium. The percentage of ostii that was observed in fertile women (91%) was similar to that observed in women with mild endometriosis (85%). However, in women with moderate and severe endometriosis, significantly less ostii were noted, respectively 72 and 51%. It is therefore argued that the absence of an ovulation ostium (so-called luteinized unruptured follicle syndrome, LUF) is more frequent in women with moderate and severe endometriosis and may contribute to infertility in this group of women.

Adult↗
PubMed1982

Comparison of complexes containing lysyl-tRNA synthetase from normal and virus-transformed cells.

We compared the lysyl-tRNA synthetases from normal (Balb/3T3) and murine sarcoma virus-transformed (KA31) mouse fibroblasts. In agreement with several other reports of mammalian systems, the lysyl-tRNA synthetases from these cells occurred in very large postmicrosomal complexes as determined by gel filtration on agarose columns. Arginyl-, isoleucyl-, methionyl-, phenylalanyl-, and tyrosyl-tRNA synthetases also occurred as part of a large complex or complexes. Activity of glycyl- or leucyl-tRNA synthetase was not detected in a complex. The specific activities of arginyl- and methionyl-tRNA synthetases were three- and five-fold higher, respectively, in a complex from KA31 as compared with a complex from Balb/3T3. In contrast, the specific activity of lysyl-tRNA synthetase from the Balb/3T3 complex was 50% higher than that of the KA31 complex. tRNALys obtained from the complexes of Balb/3T3 and KA31 was fractionated into isoacceptors on columns of RPC-5. The relative amounts of lysine isoacceptors in total preparations of tRNA from normal whole cells and in tRNA obtained from the normal enzyme complex were the same. However, two isoacceptors were present in greater amounts and two were present in lesser amounts in the KA31 enzyme complex as compared with lysine isoacceptors in a total preparation of tRNA from KA31 cells.

Amino Acyl-tRNA Synthetases↗
PubMed1982

Correlation between hormonal levels and ultrasound in patients with threatened abortion.

96 women with threatened abortion were monitored by repeated ultrasonic examinations. Simultaneously plasma HCG, progesterone, estradiol and estriol levels were measured. 12 patients with blighted ovum had hormonal levels in the low normal range before the 8th week and abnormal values after the 10th week. 31 patients had abnormal ultrasonic morphology and absence of fetal heart movements. In half of these patients, estradiol was low even before vaginal bleeding. When vaginal bleeding occurred, all subjects who aborted later, except 1, had at least one abnormal hormonal value. In 4 cases, fetal life signs were detected only after the 10th week; hormonal levels remained normal, confirming the presence of a viable fetus. 31 patients had normal ultrasounds despite vaginal bleeding and arrived to term. Hormonal profiles were also normal. 18 patients had normal ultrasounds and aborted in the second trimester of pregnancy. Some of them had low normal hormonal levels. Others had a secondary decrease in hormonal levels (most often estrogen levels) which, in some cases, preceded the abnormality of the ultrasounds. It is concluded that ultrasounds and hormonal measurements are complementary. Ultrasounds alone gave a correct prognosis in 78% of the cases after a single examination. Caution is advised when fetal life signs are absent and termination of pregnancy is contemplated. Hormonal measurements may then confirm or refute the unfavorable prognosis. Also, hormonal measurements may provide some insight as to the subsequent evolution of a threatened pregnancy, even in the presence of normal ultrasounds. The therapeutic prospect of this knowledge is, however, still to be defined.

Abortion, Spontaneous↗
PubMed1982

Ritodrine concentrations in maternal and fetal serum and amniotic fluid.

Ritodrine hydrochloride concentrations were measured by radioimmunoassay in maternal and fetal sera and amniotic fluid from eight, pregnant, volunteers. Each patient agreed to have 420 micrograms . kg-1 of ritodrine infused intra-venously over two hours prior to elective cesarian section. During infusion a blood sample was taken every 30 minutes from a maternal peripheral vein. Once anesthesia was established the infusion was discontinued. During surgery, samples were drawn from maternal peripheral vein, uterine vein, umbilical artery and vein, and amniotic fluid. All the children delivered were healthy and had a normal course during the neonatal period. Ritodrine concentrations in maternal and fetal compartments at the time of cesarian section were 54.2 +/- 11.8 ng/ml (mean +/- S.D.) in maternal peripheral vein, 37.5 +/- 10.3 ng/ml in uterine vein, 15.8 +/- 4.8 ng/ml in umbilical artery, 16.6 +/- 8.9 ng/ml in umbilical vein, and 15.2 +/- 8.7 ng/ml in amniotic fluid. There was a statistically significant difference (p less than 0.02, paired-t test) between the mean ritodrine concentrations in sera from the maternal peripheral vein and uterine vein. This difference probably reflects transplacental passage. The mean ratio of fetal vein and peripheral maternal vein serum ritodrine concentrations was 0.30 +/- 0.13 (mean +/- SD). The similarity between mean ritodrine concentrations in amniotic fluid, and sera from umbilical arterial and venous blood was striking. These results suggest that the fetus does not conjugate the drug.

Amniotic Fluid↗
PubMed1982

Effect of natural protease inhibitors and a chemoattractant on tumor cell invasion in vitro.

The effect of natural protease inhibitors and a chemoattractant on tumor cell invasion were studied with the use of a new in vitro quantitative assay of tumor cell penetration of native connective tissue. Human amnion membrane denuded of its epithelium is composed of a continuous basement membrane (BM) attached to a dense avascular collagenous stroma. M5076 reticulum sarcoma cells, known to be highly invasive in vivo, were placed on the BM side of the amnion connective tissue. Tumor cells penetrating the full thickness of the connective tissue barrier were collected on the stromal side with a Millipore filter. N-Formylmethionyl-leucyl-phenylalanine (FMLP) at an optimal concentration of 10(-7) M stimulated the penetration of up to 600% more tumor cells into the connective tissue after 20 hours in comparison to the number of tumor cells spontaneously penetrating in serum-free media. Natural protease inhibitors blocked both FMLP-stimulated and spontaneous invasion. A bovine cartilage extract containing inhibitors of both serine proteinases and metalloproteinases caused a 500% decrease in invasion. Furthermore, a 500% inhibition of invasion was produced by a purified collagenase (metalloproteinase) inhibitor. In contrast, soybean trypsin inhibitor and bovine serum albumin did not significantly alter the invasion rate. The protease inhibitors were nontoxic and did not reduce tumor cell proliferation, attachment to the amnion, and the rate of tumor cell migration through Nuclepore filters. These data support the hypothesis that collagenolytic metalloproteinases play a necessary role in tumor cell invasion of native connective tissue.

Amnion↗
PubMed1982

[Intravenous administration of ritodrine to pregnant insulin-dependent diabetics. Metabolic impact].

Seven diabetic patients who had been dependent on insulin before pregnancy (classes B, C, D of White) threatened to go into premature labour between the 31st and 36th week of the pregnancy. They were treated by intravenous administration of Ritodrine, the dosage varying between 100 and 400 micrograms per minute. The changes in the mother consisted in a rise in the blood glucose level which rose from 140 +/- 34 mg % to 212 +/- 56 mg % (p less than 0.01). This occurred in spite of a mean rise of 49% of insulin (p less than 0.0025) and a moderate ketonuria in two patients and a severe acido-ketosis in two further patients. In five patients there were no effects on the fetus as far as repeated observations of the fetal heart rate could detect. On the other hand, in the two mothers who developed acido-ketosis during the transfusion the fetal heart rythm showed signs of acute fetal distress, which however was temporary. Oscillations were reduced and there were late decelerations. These disappeared when the maternal metabolic state was brought back to equilibrium. 13.1 +/- 7.3 days were gained for the fetus by using tocolytic treatment, and this is considered a success. Discussion of these cases is accompanied by a complete review of the literature of the administration of beta-mimetic drugs in diabetic women. The authors point out that special precautions have to be taken and special conditions have to be fulfilled when this type of treatment is used. These consist of changes in the amounts of insulin that are given and particularly careful observation of the fetal heart rhythm before and during treatment.

Adult↗
PubMed1982

Peritoneal fluid volume and 17 beta-estradiol and progesterone concentrations in ovulatory, anovulatory, and postmenopausal women.

Data on the volume of peritoneal fluid and the concentrations of estradiol (17 beta-estradiol) and progesterone during the normal menstrual cycle of 158 women are reported and compared with data obtained from women with anovulatory cycles (N = 16), women using hormonal contraceptives (N = 40), and postmenopausal women (N = 6). During the menstrual cycle, the volume of peritoneal fluid increased significantly after ovulation and remained high for at least 10 days, whereas only small quantities were found in women taking oral contraceptives and in women after menopause. During the follicular phase, estradiol and progesterone concentrations in peritoneal fluid were in the same range as the levels in serum. After ovulation (days 14 to 16), the ratios of the hormonal levels in peritoneal fluid and serum, respectively, were 10 for estradiol and 63 for progesterone. The concentrations of estradiol and progesterone in peritoneal fluid were much higher than in serum for at least 1 week after ovulation. The comparison between the different groups suggests that variations in peritoneal fluid during the menstrual cycle are directly related to cyclic ovarian activity. This particular hormonal environment of the ovocyte in vivo has to be considered in future studies on female infertility that focus on maturation and fertilization in vitro.

Anovulation↗
PubMed1981

Localization of relaxin in human gestational corpus luteum.

Corpora lutea from 12 pregnant women were prepared for immunohistochemical localization of relaxin using a highly specific antiserum. A positive response is given by luteal cells that are diffusely distributed throughout the corpus luteum. These cells do not form a distinctive group in any particular area. A negative response is seen in the adjacent ovarian tissue, and also in nongestational corpora lutea in early luteal phase.

Animals↗
PubMed1981

A restriction map of the ribosomal RNA genes and the short single-copy DNA sequence of the pearl millet chloroplast genome.

The chloroplast rDNA genes of pearl millet (Pennisetum americanum) have been cloned and physically mapped. The chloroplast genome of the pearl millet contains two identical rRNA genes located on DNA sequences that are inverted with respect to one another and separated by 12 kb of single-copy DNA. The rRNA genes were positioned on a restriction endonuclease map by using as hybridization probes specific cloned rDNA sequences from the chloroplast DNA of the alga Euglena gracilis. The 16S and 23S rRNA genes were shown to be approx. 2 kb from one another, and the 5S RNA gene is immediately adjacent to the 23S tRNA gene.

Bacteriophage lambda↗
PubMed1981

Tyrosine crystals in salivary gland tumours.

Tyrosine crystals were seen in 24 of 113 salivary gland pleomorphic adenomas from Malawi and one of six carcinomas arising in a pleomorphic adenoma; they were present in tumours from all common anatomical sites. They were not found in 71 other salivary tumours of varying histological type. Similar crystals were found in one out of 56 pleomorphic adenomas from patients operated on at St Thomas's Hospital. No excess tyrosine was demonstrated in a tumour containing many crystals. Their great frequency in black patients is confirmed but an adequate explanation for this phenomenon has not been found.

Adenoma, Pleomorphic↗
PubMed1981

Demonstration of plasma human chorionic gonadotropin beta-subunit during pregnancy using LH-hCG receptors from immature porcine testis.

In an attempt to provide better assessment of human chorionic gonadotropin beta-subunit (hCG-beta) secretion in pregnant women, a method was developed for complete removal of hCG by porcine-purified receptors before measurement of the free hCG-beta subunit by radioimmunoassay. Blood samples of 111 pregnant women were collected and the following results were obtained: (1) Extensive removal (over 96%) of hCG allows quantitative determination of the free hCG-beta subunit by a specific radioimmunoassay. Our data demonstrate the presence of circulating hCG-beta subunit during pregnancy, a fact that was still under controversy until now. (2) In contrast with the hCG profile drug during pregnancy the free hCG-beta subunit exhibits a plasma concentration peak (400 +/- 132 ng/ml; mean +/- 1 SD) at the 12th-13th week, indicating that the changes in plasma levels of intact hCG and free hCG-beta subunit are unrelated.

Animals↗