Search PubMed⌕ Search

Biomedical subjects

K Thomas

Publications and source records attributed to K Thomas.

At least 217 records · Page 12Linked to original sources
PubMed1991

[Distribution of the concentrations of angiotensin II (A II), A II receptors, hPL, prolactin, and steroids in human fetal membranes].

By analyzing human trophoblastic tissues at the full term of pregnancy, this study shows the highest levels of angiotensin-II (729 +/- 111 and 602 +/- 105 pg/g of tissue), angiotensin-II receptors (295 +/- 30 and 250 +/- 32 fmol/mg proteins), human placental lactogen (973 +/- 154 and 680 +/- 28 micrograms/g) and progesterone (1,501 +/- 193 and 1,070 +/- 151 ng/g) in chorionic villi and in placental basal plate respectively. Tissue values of angiotensin-II, hPL and Progesterone were 4 times superior to those obtained in amniotic fluid and in umbilical and maternal blood. Estradiol values in chorionic villi were similar to those in placental basal plate, in chorionic plate and in chorion, but significantly higher (p less than 0,001) than in amnion, amniotic fluid and in umbilical and maternal blood. The concentrations of prolactin in chorion were 3 times superior than those found in amnion, in placental tissue, in amniotic fluid and in umbilical and maternal blood. A positive correlation was observed between Angiotensin-II and its receptors and also with hPL, P4/hPL ratio and E2/P4 ratio. Thus, angiotensin-II could play an important role in the physiology of pregnancy, due to its vasopressive action and due to its interactions with other peptides and chorio-placental steroids.

Angiotensin II↗
PubMed1991

Lithium toxicity--a risk factor for neuroleptic malignant syndrome.

We report a case of neuroleptic malignant syndrome (NMS). Lithium toxicity might have predisposed to the development of the syndrome in our patient. The patient had hyperthermia, extrapyramidal rigidity, disturbance in autonomic function and raised serum CPK level.

Chlorpromazine↗
PubMed1991

Influence of ketamine and propranolol on plasma renin activity (PRA) in female rabbits and guinea pigs.

1. Plasma renin activity was measured in non pregnant rabbits and guinea pigs under Ketamine-induced general anesthesia after pretreatment either with Propranolol or with a Placebo. Study was performed using a radio-immunoassay for angiotensin I. 2. Twenty minutes after the beginning of the observation period, renin activity in rabbits who had received Placebo alone (11.47 +/- 2.35 ng/ml/h) or associated with Ketamine (11.36 +/- 2.54 ng/ml/h) was similar. However, enzyme activity was significantly lower (P less than 0.001) when Propranolol was associated with Ketamine (3.97 +/- 0.58 ng/ml/h) or with Placebo (4.10 +/- 0.55 ng/ml/h). 3. In the same way, renin activity was significantly higher (P less than 0.001) in guinea pigs without Propranolol than in those who had received this drug. 4. These findings indicate that stress induced by general anesthesia with Ketamine or by simple manipulation of animals (Placebo) was accompanied by an excessive increase in plasma renin activity. Propranolol maintained the level of this enzyme activity within normal limits.

Animals↗
PubMed1991

[Study of the fetal and maternal renin-angiotensin system and chorio-placental steroids in the guinea pig].

1.) Total renin, active renin, prorenin, angiotensin II, estradiol and progesterone were measured in maternal, placental and fetal blood and in trophoblastic and uterine tissues of the guinea pig. Furthermore, membrane angiotensin II receptors were measured in trophoblastic tissues. 2.) Blood and tissue concentrations of total renin, active renin, angiotensin II and steroids are shown to increase with gestational age. At the full term of pregnancy (70th post-coital day), tissue concentrations of total renin in chorion (23,900 +/- 2,752 ng/g of tissue/h), maternal placenta (14,210 +/- 1,131), fetal placenta (12,475 +/- 927) and uterus (7,677 +/- 798) are 100 time higher than those observed in placental, fetal and maternal blood. Distribution of blood and tissue prorenin (inactive renin) is similar to that found for total renin. Active renin/Total renin ratio reaches 1% in uterine, placental and chorion tissues and 9.3 +/- 1.0% in maternal, placental and fetal blood. 3.) Angiotensin II levels in systemic maternal blood (690 +/- 99 pg/ml) and in uterine blood (467 +/- 84) are higher than those found in placental blood (266 +/- 39) and in different trophoblastic tissues (between 200 and 400 pg/g). Angiotensin II receptor concentrations are highest in chorion. 4.) Regarding the steroid hormones, it is noted that placental and maternal blood contain more progesterone than trophoblastic tissues. The highest concentrations of estradiol are found in chorion tissue and uterine blood. 5.) A positive correlation is observed between angiotensin II and estradiol in uterine blood (r = 0.69, P less than 0.01) and in chorion (r = 0.71, P less than 0.01). These findings indicate that angiotensin II and estradiol could, by their interactions, play an important role in the physiology of pregnancy.

Animals↗
PubMed1991

[Immunoradiometric determination of total and active renin in human fetal appendages].

The total renin and active renin in human fetal appendices were determined by an immunoradiographic assay. In addition, some samples of maternal plasma were analyzed in order to provide a reference value. The prorenin level was determined by subtracting the level of active renin from that of the total renin. At the end of this study, it was found that the mean total renin concentration was 515 +/- 54 pg/ml in the peripheral blood of the woman who had given birth, 30,385 +/- 2,951 pg/g in the tissue of the chorion and 3,986 +/- 822 pg/g in the amnion. The level within the placenta reached 1,113 +/- 155 pg/g of tissue in the chorionic plate, 256 +/- 53 pg/g in the villosities and 294 +/- 46 pg/g in the basal plate. In these various tissues, prorenin accounted for over 80% of the total renin, except in the chorionic villosities, where it accounted for only 72.44%. In general, this study showed that the highest, concentrations of immunoreactive renin are found in the chorionic membrane. This membrane probably plays a decisive role in regulating the renin-angiotensin system within the fetal appendices.

Extraembryonic Membranes↗
PubMed1991

[Angiotensin II receptors in the human placenta are type AT1].

Membrane angiotensin II receptors were measured in human placenta by means of 125I [Sar1 Ile8] All (angiotensin II antagonist) and characterized by using 2 other antagonists of angiotensin II: Dup 753 and CGP 42112A. These are specific and selective ligands which enable identification of AT1 and AT2 receptor subtypes respectively. The [Sar1 Ile8] All affinity is similar (Kd approximately 1 nmol.l-1) in the 3 different placental structures examined. However, the Bmax of villous tissues is approximately 9 times higher than that observed in chorionic plate but remains near that found in basal plate. In the central area of the placenta, mean values of 125I [Sar1 Ile8] All binding observed at a single concentration of 0.15 nmol.l-1 are 242 +/- 31 fmol/mg proteins in basal plate, 300 +/- 35 in villous tissues and 36 +/- 8 in chorionic plate. The umbilical vein and arteries respectively have 8.8 +/- 4.8 and 4.0 +/- 1.7 fmol/mg protein. The subtype analysis shows that only AT1 receptor is present in placental tissues. The Bmax values as well as those obtained by the relative measurement performed at a fixed 125I [Sar1 Ile8] All concentration of 0.15 nmol.l-1 indicate that the highest concentrations of angiotensin II receptors are found in placental villous tissues.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1991

The effect of owning private long-term care insurance policies on out-of-pocket costs.

This article examines the effect of owning long-term care insurance policies on the amount of out-of-pocket costs incurred by the elderly during their nursing home stays, and the importance of different policy features and restrictions. Data were drawn from the 1985 National Nursing Home Survey, and from copies of long-term care insurance policies collected from 11 leading companies during the spring and summer of 1988. The study results show a great deal of uncertainty concerning amounts the policies are likely to pay toward nursing home stays. This implies that the policies collected did not adequately fulfill one of the primary purposes of insurance: a reduction in risk and uncertainty. To examine whether rapid policy changes in recent years have made a difference, we assessed each of seven policy features and found that the two most important restrictions in long-term care insurance policies are prior hospitalization and level-of-care requirements. Recently, the National Association of Insurance Commissioners (NAIC) recommended that states prohibit the sale of policies containing these restrictions. Our findings confirm the wisdom of this recommendation. We did find, however, that two other policy restrictions--policy maximums and lack of inflation adjustment--are problematic. We recommend that the NAIC expand its model regulations to require that policy maximums be a minimum of four years, and that some form of inflation protection be incorporated into policy benefit structures.

Aged↗
PubMed1991

Metabolic and cardiac effects of Clistanthus collinus poisoning.

A prospective study of 11 cases of Clistanthus collinus leaf poisoning was undertaken to evaluate the mechanism of hypokalaemia that occurs in these cases. Continuous cardiac monitoring was done. Ventricular ectopics, ventricular tachycardia and fibrillation were the important arrhythmias. No atrioventricular blocks or other significant bradyarrhythmias were noted. The renal potassium loss was found to be very high (120 +/- 87.95 mEq/L) even in the presence of hypokalaemia and in spite of continuing drop in serum potassium concentration. Metabolic study established that renal potassium leak is the mechanism by which hypokalaemia was mediated.

Adolescent↗
PubMed1991

[Radioimmunoassay of progesterone in peripheral and placental blood of pregnant rabbits and guinea pigs].

Radioimmunoassay of progesterone in systemic and placental blood of pregnant rabbits and guinea pigs. 1. The level of progesterone in pregnant rabbits and guinea pigs serum was measured directly (without extraction) using a RadioImmunoAssay (RIA). 2. Hormonal concentrations in systemic blood were shown to increase with gestational age, being at their highest half-way through pregnancy (16.03 +/- 2.63 ng/ml for rabbits; 319.01 +/- 42.10 ng/ml for guinea pigs) and decreasing at the end of the pregnancy. 3. Progesterone was not detectable in rabbit placental blood, whereas a high level of this hormone was found in guinea pig placental blood, which increased with gestational age. From the 28th to the 56th post-coital day, the level increased from 143.22 +/- 13.15 to 283.30 +/- 36.84 ng/ml. 4. The method used enables to measure correctly progesterone concentrations in rabbit and guinea pig serum without extraction.

Animals↗
PubMed1991

Capillary blood cell velocity is reduced in fever without hypotension.

Capillary blood cell velocity was measured in a group of normotensive febrile patients as a basis for further study into the microvascular physiology of febrile hypotensive patients with sepsis. Television videomicroscopy was used to record the capillary blood cell movement in the finger nailfold. Analysis of all moving gaps in the red cell column seen during a minimum of 2 minutes was done by the frame-by-frame technique and mean blood cell velocity derived. Core (external auditory meatus) and skin (finger) temperature were also measured. Subjects (n = 6) were sex and skin temperature matched to controls. Although the mean skin temperature of subjects [28.73 degrees C, SD = 0.28] was not significantly different to controls [30.63 degrees C, SD = 3.11; p less than 0.05] the mean velocity was significantly reduced in the febrile subject group [0.28 mm/sec, SD = 0.17] as compared with controls [0.56 mm/sec, SD = 0.22; p less than 0.05]. It is likely therefore that these skin vessels vasoconstrict as part of the integrated response to reduce heat loss.

Adolescent↗
PubMed1991

[The value of radioimmunoassay of urinary hCG in an in vitro fertilization program].

Radio-immuno-assay estimations of urinary hCG were carried out with pharmacia Kit beta hCG Riact on 36 women who had received embryo transfers. The analysis was carried in order to try and find how and at what moment in time it is possible to diagnose very early a developing pregnancy after embryo transfer. In this work we have found that the mean level of urinary hCG was significantly higher (P less than 0.001) in women who became pregnant (group B) than in those who did not become pregnant (group A). The difference in mean hormone levels in these two groups became more marked in the following days. The time doubling of the hCG level varied between 1.21 and 3.24 days in group B. By the eighth day the level of urinary hCG was less in group B than in group A, probably due to rapid renal breakdown of hCG. In summary these results show that the level of urinary hCG estimated from the 11th day onwards after an embryo transfer repeated two or three days later makes it possible to detect early pregnancies.

Adult↗
PubMed1990

Inhibition of ovulation by low-dose monophasic contraceptive containing gestodene.

Ovulation inhibition by the monophasic oral contraceptive containing 75 ug of gestodene and 30 ug of ethinyl estradiol was evaluated in 25 healthy volunteers for five cycles: a pretreatment cycle, three treatment cycles, and a posttreatment cycle. Serum luteinizing and follicle- stimulating hormones, estradiol, and progesterone levels were measured on days 8 through 17; progesterone was measured once, around day 21. Pelvic ultrasound examinations were performed on cycle days 8 to 17, luteinizing and follicle-stimulating hormone levels reached values on the lower limit of detection. Luteal activity was not detected in treated cycles. Follicular activity, which was reflected by estradiol levels, was mot strongly depressed during the first treated cycle. Pelvic ultrasound examinations confirmed excellent inhibition of follicular maturation. Restoration of ovarian function in the posttreatment cycle was excellent and showed a midcycle hormonal profile identical to the pretrial cycle.

Adult↗
PubMed1990

Prediction of individual response to controlled ovarian hyperstimulation by means of a clomiphene citrate challenge test.

A clomiphene citrate (CC) challenge test was carried out in 114 patients to evaluate the capacity of this test to predict the patient's individual response to controlled ovarian hyperstimulation (COH) performed with a gonadotropin-releasing hormone agonist and human menopausal gonadotrophins (hMG) for in vitro fertilization. The sum of follicle-stimulating hormone measured before and after CC intake, is the parameter that correlated best with subsequent response to COH. The upper limit of the reference value for this parameter, established by considering the CC challenge test performed on 26 patients who became pregnant, was 26.03 mIU/mL. Twenty patients who presented a CC challenge test result above the reference value were compared with patients with a normal test result. For these 20 patients, COH required more hMG and was cancelled in 25% of the cases (instead of 1% in the control group). The number of follicles aspirated, oocytes retrieved, and embryos obtained were on average six times lower than in patients with a CC challenge test result within the reference value, and no pregnancy was obtained. We concluded that CC challenge test provides a reliable individual prognosis for the ovarian response to COH.

Clomiphene↗
PubMed1990

Changes of relaxin concentrations determined by immunodensitometry in ovaries of NMRI mice during pregnancy.

Relaxin has been localized in corpora lutea (CL) of pregnant NMRI mice using the avidin-biotin complex immunocytochemical procedure and an antiserum against highly purified porcine relaxin. The immunostaining was measured by immunodensitometry. Relaxin immunostaining was first observed in luteal cells of type I gestational CL on day 11.5 (D11.5). For each investigated day, all CL were identically stained, and immunostaining was evenly dispersed all over the CL. Seventy-five percent of cells were stained at D11.5, and nearly all cells were stained between D13.5 and D18.5. The staining intensity increased throughout the last half of pregnancy, reaching a maximum at D18. A few hours before parturition, at D18.5, relaxin immunostaining decreased dramatically and reached the background level shortly after delivery. From our results we may conclude that, in murine CL, the number of relaxin-secreting cells and the intracellular storage of the peptide increase during pregnancy. The disappearance of relaxin with the cells occurs rapidly +/- 12 h before parturition.

Animals↗
PubMed1990

Developmental regulation of expression of the lactate dehydrogenase (LDH) multigene family during mouse spermatogenesis.

Expression of the Lactate Dehydrogenase (LDH) genes during various stages of spermatogenesis was studied by using a combination of Northern blot analyses and in situ hybridization techniques. These studies have indicated that developmentally programmed expression of all three functional LDH genes occurs during differentiation of germ cells. The LDH/C (ldh-3) gene was expressed exclusively during meiosis and spermiogenesis, beginning in leptotene/zygotene spermatocytes and continuing through to the elongated spermatids. LDH/C (ldh-3) gene expression was accompanied by transient expression of the LDH/A (ldh-1) gene in pachytene spermatocytes and round spermatids. The LDH/B (ldh-2) gene was expressed mainly in Sertoli and spermatogonial cells. By using somatic cell hybrids, the LDH/C (ldh-3) gene has been mapped to mouse chromosome 7, establishing that it is syntenic with the LDH/A (ldh-1) gene locus. Experimental observations made in this study provide new insight into the order and sequence of events involved in the regulation of gene expression of the LDH gene family during spermatogenesis.

Animals↗
PubMed1990

[An evaluation method for the determination and monitoring of urinary HCG].

A kit of anti-beta hCG monoclonal antibodies (Pharmacia beta hCG Riact) has been tested in the assay and monitoring of urinary hCG. After several tests, the technique was found to be reproducible and specific for assay of hCG and showed good sensitivity in urine assays. Optimal sensitivity was seen in the urine pH range 5.5 and 10.00. Below 5.5 and above 10.00, its detection capacity dropped off sharply. Dilution of urine with the kit buffer gave hormonal values comparable to those of undiluted urine, but improved them substantially when the urine pH was below 5.5. It is therefore wise to dilute urine to avoid the potential risk of assay interference by urine acidity. In frozen urine, hCG concentrations tend to decrease but are not altered significantly. This recently developed method allows easy and reliable monitoring of urinary hCG for detection of unknown pregnancy in spontaneous cycles, surveillance of the state of embryos transferred during in vitro fertilization cycles, and evaluation of the efficacy of treatment of tumors secreting (beta hCG).

Adult↗