Biomedical subjects
Publications and source records attributed to K A Ford.
Carotid artery aneurysms are rare. Nurses need an awareness of these lesions in order to conduct appropriate neurological and cardiovascular assessments, provide appropriate preoperative and postoperative interventions and educate patients and their families. Understanding carotid artery aneurysms enables the nurse to provide quality nursing care to this patient population.
A replication of an American study of body shape preference was conducted in a group of 218 Arab students attending the American University in Cairo, Egypt. Arab female students felt their ideal shape to be significantly thinner than their current shape, while male students did not. Hence the appraisal of body shape shows gender differences in Egypt consistent with the American study. The Arab women reported a current shape similar to American women but had a smaller discrepancy between ratings of their ideal and current body shape. There was no difference for either Arab women or men between the shape thought most attractive to the opposite sex and that which the other gender actually reported as most attractive. The study shows a clear preference for thinness in the Arabic culture, inferences are made to its role in predisposing to eating disorders.
Laser-assisted angioplasty is an exciting, new treatment option being used for patients with peripheral arterial disease. Nurses need to be aware of this procedure so that they can provide quality care for this patient population.
An automated enzyme immunoassay for human lutropin for use with the Abbott IMx analyzer is described. The assay provides results in approximately 40 min with a sensitivity of 0.25 int. units of LH per liter for up to 23 serum or plasma samples. Cross-reactivity with follitropin (2000 int. units/L) and thyrotropin (2 int. units/L) was negligible; it was 0.016% with human choriogonadotropin (1 X 10(6) int. units/L). There was no interference by high concentrations of bilirubin (0.5 g/L), hemoglobin (7.50 g/L), or triglycerides (13.5 g/L). Intra-, inter-, and total assay CVs were less than or equal to 3.75%, less than or equal to 7.1%, and less than or equal to 7.94%, respectively. Values obtained with the IMx correlated well (r = 0.98, n = 194) with values obtained with Diagnostic Products' LH Double Antibody RIA, and Serono's LH MAIAclone assay. This assay should be useful for small to medium-size laboratories involved in the clinical diagnosis of reproductive pathology.
The purpose of these studies was to determine how exposure to FSH affects subsequent responsiveness of adenylyl cyclase and progesterone production to FSH in immature porcine granulosa cells in vitro. Acute cAMP and progesterone responses to FSH and the postreceptor activators of cyclase, forskolin and cholera toxin, were determined after a 24-h preincubation with FSH. Pretreatment with FSH (1-1000 ng/ml) resulted in an increase in subsequent basal progesterone production which was dependent on preincubation FSH concentration. The cAMP response to FSH, on the other hand, was reduced after preincubation with FSH in a manner dependent on preincubation FSH concentration. Removal of FSH with acidified medium and subsequent incubation in FSH-free medium resulted in recovery of the cAMP response to FSH, indicating that attenuation of the response is reversible. Attenuation of the cAMP response to FSH does not appear to be due to 1) a loss of activity of the catalytic moiety of cyclase, since the response to forskolin and cholera toxin was not decreased by FSH; 2) a decrease in coupling of the stimulatory guanine nucleotide regulatory protein with the catalytic moiety of cyclase, since the response to cholera toxin was not reduced by FSH; 3) inhibitory signals, since preincubation with pertussis toxin did not affect the subsequent response to FSH; or 4) cAMP itself, since neither cholera toxin nor the cAMP analog 8-(4-chlorophenyl-thio)cAMP affected the response to FSH. It appears, instead, that FSH regulates FSH responsiveness by regulating the interaction of the FSH receptor with stimulatory guanine nucleotide regulatory protein.
The purpose of these studies was to determine whether changes in FSH receptors correlated with FSH-induced attenuation of FSH-responsive adenylyl cyclase in immature porcine granulosa cells. Cells were incubated with FSH (1-1000 ng/ml) for up to 24 h, treated with acidified medium (pH 3.5) to remove FSH bound to cells, and incubated with [125I]iodo-porcine FSH to quantify FSH-binding sites. FSH increased binding of FSH in a time-, temperature-, and FSH concentration-dependent manner. FSH (200 ng/ml) increased binding approximately 4-fold within 16 h. Analysis of equilibrium saturation binding data indicated that the increase in binding sites reflected a 2.3-fold increase in receptor number and a 5.4-fold increase in apparent affinity. The increase in binding did not appear to be due to 1) a decrease in receptor turnover, since the basal rate of turnover appeared to be very slow; 2) an increase in receptor synthesis, since agents that inhibit protein synthesis and glycosylation did not block the increase in binding; or 3) an increase in intracellular receptors, since agents that inhibit cytoskeletal components had no effect. Agents that increase intracellular cAMP did not affect FSH binding. The increase in binding appeared to result from unmasking of cryptic FSH-binding sites, since FSH increased binding in cell-free membrane preparations to the same extent as in cells. Unmasking of cryptic sites was hormone specific, and the sites bound FSH specifically. Unmasking of sites was reversible in a time- and temperature-dependent manner after removal of bound FSH. The similarity between the FSH dose-response relationships for unmasking of FSH-binding sites and attenuation of FSH-responsive cAMP production suggests that the two processes are functionally linked.
Magnesium (Mg2+) increases binding of follicle-stimulating hormone (FSH) to membrane-bound receptors and increases adenylyl cyclase activity. We examined the effects of divalent and monovalent cations on FSH binding to receptors in granulosa cells from immature porcine follicles. Divalent and monovalent cations increased binding of [125I]iodo-porcine FSH (125I-pFSH). The divalent cations Mg2+, calcium (Ca2+) and manganese, (Mn2+) increased specific binding a maximum of 4- to 5-fold at added concentrations of 10 mM. Mg2+ caused a half-maximal enhancement of binding at 0.6 mM, whereas Ca2+ and Mn2+ had half-maximal effects at 0.7 mM and 0.8 mM, respectively. The monovalent cation potassium (K+) increased binding a maximum of 1.5-fold at an added concentration of 50 mM, whereas the monovalent cation (Na+) did not increase binding at any concentration tested. The difference between K+ and Na+ suggested that either enhancement of binding was not a simple ionic effect or Na+ has a negative effect that suppresses its positive effect. Ethylenediamine tetraacetic acid, a chelator of Mg2+, prevented binding of 125I-pFSH only in the presence of Mg2+, whereas pregnant mare's serum gonadotropin, a competitor with FSH for the receptor, prevented binding in both the absence and the presence of Mg2+. Guanyl-5-ylimidodiphosphate (Gpp[NH]p) inhibited binding of 125I-pFSH in the absence or presence of Mg2+, but only at Gpp(NH)p concentrations greater than 1 mM. We used Mg2+ to determine if divalent cations enhanced FSH binding by increasing receptor affinity or by increasing the apparent number of binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)
The divalent cations magnesium, calcium and manganese, and the monovalent cation, potassium, but not sodium, enhance binding of [125I]iodo-porcine follicle-stimulating hormone to follicle-stimulating hormone (FSH) receptors in membranes of porcine granulosa cells via an increase in the apparent number of binding sites. The objective of the present studies was to determine if increased binding of FSH to its receptor causes increased adenylyl cyclase activity in response to FSH, or conversely, if enhancement of the cyclase or one of its components causes increased binding, or if the two processes are modulated independently. MgCl2 and CaCl2, which both enhance binding in intact cells and in cell-free membrane preparations, had opposite effects on cyclase-MgCl2 stimulatory, CaCl2 inhibitory. In isotonic NaCl, MgCl2 did not enhance binding, but it did increase FSH-stimulated production of cyclic adenosine 3',5'-monophosphate (cAMP). NaCl did not enhance FSH binding and it did not enhance cyclase in cell-free membranes, but it did increase FSH- and forskolin-stimulated cAMP production in intact cells. In intact cells, maximally effective concentrations of MgCl2 and KCl were additive in enhancing cAMP production whereas the effects of NaCl and KCl together were synergistic. The results indicate that although cationic effects on FSH binding are not causally related to effects on cyclase, the cationic microenvironment of the granulosa cell membrane is critical to both FSH receptor and adenylyl cyclase functions.
Preexposure to lithium chloride attenuated the subsequent acquisition of amphetamine-induced taste aversions. This attenuation was independent of the similarity of the preexposure and conditioning environments, an effect inconsistent with an associative interpretation of the effects of LiCl preexposure. These results were discussed in terms of the mechanism underlying the effects of drug preexposure on taste aversion learning.