Regulation of chicken embryonic growth hormone secretion by corticosterone and triiodothyronine: evidence for a negative synergistic response.

We reported that growth hormone (GH)-secreting cells differentiated by d 16 of chick embryonic development and that these somatotrophs were responsive to GH-releasing hormone and thyrotropin-releasing hormone. The present experiments evaluated effects of corticosterone and triiodothyronine (T3) on embryonic GH secretion. Anterior pituitary cells from embryonic day (e) 16, e18, and e20 were subjected to reverse hemolytic plaque assays (RHPAs) for GH in the absence or presence of corticosterone or T3. Corticosterone increased GH secretion from embryonic somatotrophs, an effect particularly evident on e16 and e18. T3 decreased GH secretion on e16, while no effect of T3 was significant on e18 or e20. Next, pituitary cells were subjected to RHPAs with T3 and corticosterone alone or in combination. Combined treatment with these hormones suppressed GH secretion from e16, e18, and e20 somatotrophs to levels below those found under basal conditions. We conclude that corticosterone can stimulate GH secretion in vitro at all embryonic ages tested. Furthermore, T3 can suppress basal GH secretion on e16, and the combination of T3 and corticosterone can suppress GH secretion at all ages. These findings indicate that GH secretion during the end of chicken embryonic development may be regulated by the interactions of endogenous glucocorticoids and thyroid hormones that increase prior to hatching.

Appropriateness of self-care responses to symptoms among elders: identifying pathways of influence.

The purpose of the study was to investigate the separate and joint influences of sociodemographic, social situational (social support and interpersonal functioning), and symptom variables on the appropriateness of self-care responses to symptoms among elderly people. A cross-sectional face-to-face structured interview of a sample of noninstitutionalized, English-speaking persons 65 and older living in Minneapolis was used. The theoretical framework for the investigation was tested using graphical modeling techniques. A majority of the subjects responded appropriately to the symptoms they experienced. Gender was a key variable in understanding which of the sociodemographic, social support, interpersonal functioning, and symptom variables were related to the likelihood that individuals would engage in appropriate self-care. There appear to be fundamental differences in the influence of the social situational variables for men and women. If these results are confirmed in future studies, different intervention strategies may be needed for assisting elderly men and women in interpreting and responding to their symptoms.

Symptom consultation in lay networks in an elderly population.

Although lay referrals are known to be important as factors affecting the use of professional services, less is known about how individuals use lay consultation in evaluating symptoms. The amount and type of advice given by persons in the social network is especially important with respect to self care of symptoms that never reach the attention of professional caregivers. This article provides information on how often and from whom elderly citizens seek and receive consultation, such as family and friends, when they experience common symptoms. Findings suggest that female relatives are important sources of advice but that neither gender nor living arrangements are closely related to the tendency to seek lay advice for common symptoms. Subjects who consulted lay advisers about arthritic symptoms also were more likely to seek professional consultation.

Self-care of common illnesses in Denmark.

Survey data collected from a random sample of the Danish population in the first phase of a research investigation of self-care behavior are discussed. Self-administered postal questionnaires were used to obtain data on behavioral responses to common illness conditions. Information was obtained from 1,462 persons regarding care of 3,100 illness episodes. Log-linear analyses of multiway frequency tables were used to examine the effects of sociodemographic and attitudinal variables on the illness responses. Age, sex, perceived health status, and a reliant attitude toward physicians were the more important variables related to the illness behaviors. Interactions among these variables suggest directions for productive research into the factors shaping responses to illness. Income and social class, among respondents in relation to differences in activity levels maintained while ill suggest that some people may have limited options for caring for themselves during illness.

Simultaneous determination of phenytoin and phenobarbital in serum or plasma by substrate-labeled fluorescent immunoassay.

This assay system for simultaneously determining phenytoin and phenobarbital in serum and plasma is based on the substrate-labeled fluorescent immunoassay technique. A beta-galactosylcoumarin derivative of phenobarbital and a 4-methylcoumarin phosphodiester derivative of phenytoin are used as substrate labels for Escherichia coli beta-galactosidase and Crotalus atrox phosphodiesterase I, respectively. The smallest measurable concentrations are about 1.6 mg/L for phenytoin, 2.7 mg/L for phenobarbital. Within-run coefficients of variation are about 5% for phenytoin and 2% for phenobarbital, about 6% for both between-runs. Results for phenytoin and phenobarbital in serum and plasma correlate well with those determined by the Ames TDA (r = 0.944 and 0.986, respectively) and Syva's EMIT (r = 0.977 and 0.969, respectively) assays.

Enzyme therapy XVII: metabolic and immunologic evaluation of alpha- galactosidase A replacement in Fabry disease.

A pilot trial of enzyme replacement using splenic and plasma forms of alpha-galactosidase A was undertaken in 2 brothers with Fabry disease, an X-linked glycosphingolipid storage disease. Partially purified preparations of alpha-galactosidase A from human spleen and plasma Cohn fraction IV-1 were prepared aseptically for in vivo administration. The disappearance of enzymatic activity from plasma, levels of circulating substrate, and potential immune response were evaluated following IV administration of 6 unentrapped doses (2,000 U/kg) of each enzyme form to the respective recipient during a 117-day period. Repeated injections were well tolerated. The circulating half-life of the splenic form was about 10 min whereas that for the plasma form was approximately 70 min. No immune response was detected by skin and immunodiffusion tests or by alterations in the maximal activity or clearance kinetics for either enzyme following successive administrations. After each dose of the splenic form, the concentration of the accumulated circulating substrate globotriaosylceramide, decreased maximally (approximately 50% of initial values) in 15 min and returned to preinfusion levels by 2-3 hr. In marked contrast, injection of the plasma form decreased the circulating substrate levels 50-70% by 2-6 hr; the concentrations of globotriaosylceramide gradually returned to preinfusion values by 36-72 hr. Two consecutive doses of the plasma form, administered on days 1 and 3, reduced the circulating substrate concentration to normal levels. Prior to the 6th enzyme administration, circulating substrate was stable-isotope labeled by the infusion of dideutero-glucose, and the effects of each enzyme form on circulating substrate degradation and reaccumulation were determined. The results of this study indicated that labeled (newly synthesized) substrate reaccumulated following injection of the splenic enzyme whereas both unlabeled (previously stored?) and labeled substrate reaccumulated in the circulation after administration of the plasma form. These studies demonstrated the differential disappearance kinetics of the splenic and plasma forms of alpha-galactosidase A, their differential effects on circulating substrate degradation and reaccumulation, as well as the lack of an immune response to repeated administrations of these homologous, unentrapped enzymes.

Enzyme therapy in Fabry disease: differential in vivo plasma clearance and metabolic effectiveness of plasma and splenic alpha-galactosidase A isozymes.

A pilot trial of enzyme replacement with splenic and plasma alpha-galactosidase A (alpha-D-galactosidase; alpha-D-galactoside galactohydrolase, EC 3.2.1.22) isozymes was undertaken in two brothers with Fabry disease, an X-linked glycosphingolipid storage disease. Six unentrapped doses (2000 units/kg) of each isozyme were administered intravenously to the respective recipients during a 117-day period. The circulating half-life of the splenic isozyme was about 10 min, whereas that for the plasma isozyme was approximately 70 min. No immune response was detected by skin and immunodiffusion tests or by alterations in the maximal activity or clearance kinetics for either isozyme after successive administrations. After each dose of the splenic isozyme, the concentration of the accumulated circulating substrate, trihexosylceramide (globotriaosylceramide), decreased maximally (approximately 50% of initial values) in 15 min and returned to preinfusion levels by 2-3 hr. In marked contrast, injection of the plasma isozyme decreased the circulating substrate levels 50-70% by 2-6 hr; the concentrations gradually returned to preinfusion values by 36-72 hr.