Immunological characterization of L-triiodothyronine and L-thyroxine labelled with rhodamine B isothiocyanate.

In the present work the label of L-T3 and L-T4 with RBITC have been developed by means of a relatively easy procedure. A purification by TLC, previously optimized, offers the possibility of obtaining a good recovery of conjugates T3 and T4-RBITC. The immunoreactivity of conjugates was calculated by a formulas especially designed for this purpose.

Marital relationships and Type A-B behavior assessed using the structured interview, Jenkins Activity Survey, and Framingham Type A Scale.

Associations between spouses' Type A/Type B Behavior and marital distress, communication, and desired relationship changes were investigated in a sample of 42 healthy Caucasian couples aged 39 to 60 years. Consistency of relationships between marital distress and behavior type (BT) across different BT measurement techniques was also evaluated. BT was measured using the Structured Interview (SI), the Jenkins Activity Survey (JAS), and the Framingham Type A Scale (FTAS).

Carboxylterminal deletion mutants of ribulosebisphosphate carboxylase from Rhodospirillum rubrum.

The carboxylterminal octapeptide of ribulosebisphosphate carboxylase from Rhodospirillum rubrum, which lacks small subunits, shows homology to a highly conserved region near the amino terminus of the small subunits of hexadecameric ribulosebisphosphate carboxylases, which are composed of large and small subunits. Truncations of the R. rubrum enzyme, which partially or completely deleted the region of homology, demonstrated that the region is not an important determinant of the catalytic efficiency of the enzyme.

The Subunit Structure of Potato Tuber ADPglucose Pyrophosphorylase.

ADPglucose pyrophosphorylase has been extensively purified from potato (Solanum tuberosum L.) tuber tissue to study its structure. By employing a modified published procedure (JR Sowokinos, J Preiss [1982] Plant Physiol 69: 1459-1466) together with Mono Q chromatography, a near homogeneous enzyme preparation was obtained with substantial improvement in enzyme yield and specific activity.

Molecular Characterization of the Brittle-2 Gene Effect on Maize Endosperm ADPglucose Pyrophosphorylase Subunits.

Activity of the enzyme ADPglucose pyrophosphorylase is known to be reduced in maize (Zea mays L.) endosperm mutants at two independent loci, Shrunken-2 (Sh(2)) and Brittle-2 (Bt(2)). Spinach leaf ADPglucose pyrophosphorylase has previously been shown to comprise two subunits of 51 and 54 kilodaltons.

Serum activity of the key gluconeogenic enzymes in carbon-tetrachloride-induced experimental hepatotoxicity.

Serum activity has been measured in three of the key enzymes in the gluconeogenic pathway in rats subjected to experimental hepatotoxicity after intraperitoneal administration of carbon tetrachloride. The levels of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-biphosphatase (FBPase) showed a similar behavior to the transaminase (AST and ALT), increasing markedly with respect to the controls at 12 h after administration of the poison, reaching their maximum peak of activity at between 24 and 36 h, and returning to normal values at 96 h. The activity of glucose-6-phosphatase was not significantly modified throughout the treatment.

Immunocytochemical Localization of ADPglucose Pyrophosphorylase in Developing Potato Tuber Cells.

The subcellular localization of ADPglucose pyrophosphorylase, a key regulatory enzyme in starch biosynthesis, was determined in developing potato tuber cells by immunocytochemical localization techniques at the light microscopy level. Specific labeling of ADPglucose pyrophosphorylase by either immunofluorescence or immunogold followed by silver enhancement was detected only in the amyloplasts and indicates that this enzyme is located exclusively in the amyloplasts in developing potato tuber cells. Labeling occurred on the starch grains and, in some instances, specific labeling patterns were evident which may be related to sites active in starch deposition.

The encoded primary sequence of a rice seed ADP-glucose pyrophosphorylase subunit and its homology to the bacterial enzyme.

Rice seed ADP-glucose pyrophosphorylase cDNA clones were isolated by screening a lambda expression library prepared from rice endosperm poly(A+) RNA with a heterologous antibody raised against the spinach leaf enzyme and subsequently by nucleic acid hybridization. One cDNA plasmid, possessing about 1650 nucleotides, was shown by both DNA and RNA sequence analysis to contain the complete ADP-glucose pyrophosphorylase coding sequence of 483 amino acids. The primary sequence displayed a putative leader peptide presumably required for transport of this nuclear encoded protein into the amyloplasts, a differentiated starch containing plastid.

Psychophysiologic stress responsivity in type A and B female college students and community women.

Extreme Type A and Type B women (Jenkins Activity Survey) randomly assigned to low or high stress conditions of a forced choice reaction time task were monitored for heart rate (interbeat intervals), pulse transit time, skin conductance levels, and skin conductance responses during baseline, task, and recovery periods. Participants included 41 female undergraduates (student sample) and 58 women aged 25-65 years (community sample). Multivariate repeated measures analysis of variance indicated that among the students, Type As exposed to high stress had significantly higher skin conductance levels at baseline than did the Type As in low stress.

Effect of low-iodine diet and propylthiouracil on glycolytic enzymes in brain areas of adult rats.

Glycolytic activity of five brain areas in the rat was studied under two hypothyroid states: (1) induced by low-iodine diet from weaning, and (2) induced by propylthiouracil. The areas studied were the anterior cortex, amygdala, hypothalamus, septum and hippocampus. A low-iodine diet induced a decrease of pyruvate kinase activity in three region and of phosphofructokinase in the hippocampus, while hexokinase increased in both the amygdala and septum.

Influence of thyroidectomy on serum and pituitary FSH in control and orchidectomized rats.

The influence of hypothyroidism on both pituitary and serum FSH has been studied in male rats thyroidectomized in early stages of development. To know whether FSH alterations are produced by changes of the gonadal feed-back system or by a direct effect of thyroid hormones upon pituitary synthesis, estradiol, testosterone and testicular weight were measured. The result showed a decrease of biological and immunological activity of pituitary FSH in thyroidectomized rats.

Postnatal development of the renin-angiotensin system in thyroidectomized rats.

Postnatal changes in plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin substrate (PRS) and plasma angiotensin II concentration (AII) were studied in young thyroidectomized rats from the 4th to the 10th week of life. Although there were no differences in the PRA pattern between thyroidectomized and euthyroid animals, an increase in PRC from the 6th week of life, together with a reduction of the glomerular filtration rate (GFR) and an increase in the fractional excretion of sodium (FENa) from the 8th week of life, was observed in young hypothyroid animals. Moreover, in thyroidectomized animals, PRS and AII declined until the 10th week of age, while in euthyroid animals an increase of PRS and AII was observed between the 8th and 10th weeks of life.

Mental stress and the induction of silent myocardial ischemia in patients with coronary artery disease.

To assess the causal relation between acute mental stress and myocardial ischemia, we evaluated cardiac function in selected patients during a series of mental tasks (arithmetic, the Stroop color--word task, simulated public speaking, and reading) and compared the responses with those induced by exercise. Thirty-nine patients with coronary artery disease and 12 controls were studied by radionuclide ventriculography. Of the patients with coronary artery disease, 23 (59 percent) had wall-motion abnormalities during periods of mental stress and 14 (36 percent) had a fall in ejection fraction of more than 5 percentage points.

Affinity labeling of the allosteric activator site(s) of spinach leaf ADP-glucose pyrophosphorylase.

Pyridoxal-P has been shown to be an activator of the spinach leaf ADP-glucose pyrophosphorylase. It has a higher apparent affinity than the physiological activator 3-phosphoglycerate but only activates the enzyme activity 6-fold whereas 3-phosphoglycerate gives a 25-fold activation. Reductive phosphopyridoxylation of the spinach leaf enzyme results in enzyme having less dependence on the presence of activator for activity.

Psychophysiological reactivity to mental arithmetic stress in black and white normotensive men.

Racial differences in physiological responses to a behavioral stressor were examined. Thirty-four Black and 42 White male normotensives 34 to 55 years old (mean age = 43.01 years) performed a mental arithmetic task while blood pressure, heart rate, and skin conductance were recorded.

[L-thyroxine and triiodo-L-thyronine in the cerebrospinal fluid and hypothalamo-hypophyseal axis of hyper- or hypothyroid rats].

L-thyroxine and triiodo-L-thyronine concentrations in cerebrospinal fluid (CSF), hypothalamus and pituitary gland are measured in male albino-Wistar rats under several experimental thyroid disfunction : including hyperthyroidism induced by L-T3 and L-T4 treatments and surgical hypothyroidism. Radioimmunoassay is carried out by Nejad's method modified in this work. The pattern of thyroid hormone concentrations in CSF is similar to that in serum, but the values obtained are lower.

Effect of thyroid hormones on angiotensinogen production in the rat in vivo and in vitro.

The influence of thyroid hormones on angiotensinogen production was studied in vitro and in vivo. In the in-vitro system, angiotensinogen production rate (APR) of monolayer cultures of rat hepatocytes in response to tri-iodothyronine (T3) and thyroxine (T4) was assayed. In the in-vivo system, plasma angiotensinogen concentration (PAC) and liver angiotensinogen content (LAC) were measured in hyper- and hypothyroid rats.

Subunit Structure of Spinach Leaf ADPglucose Pyrophosphorylase.

To initiate structural studies of the ADPglucose pyrophosphorylase from spinach an improved purification procedure was devised. The modified purification scheme allowed the isolation of 20 to 30 milligrams pure enzyme from 10 kilogram of spinach leaves. Electrophoresis of the purified enzyme confirmed an earlier study which showed that the enzyme was putatively composed of two subunits (Copeland L, J Preiss 1981 Plant Physiol 68: 996-1001).

Effect of various components of the renin-angiotensin-aldosterone system on angiotensinogen production in a monolayer culture of adult rat hepatocytes.

A monolayer culture of adult rat hepatocytes was used to study the effect of various components of the renin-angiotensin-aldosterone system (angiotensin II, aldosterone and angiotensinogen), and intracellular sodium depletion (by ouabaine addition) on the angiotensinogen production rate. Normal hepatocytes synthesized linearly angiotensinogen for 6 h at a mean rate of 110 pg angiotensin I generated/mg intracellular protein each h. The addition of hydrocortisone (0.

[Homologous radioimmunoanalysis of serum L-thyroxine and triiodo-L-thyronine in rats with hypo- and hyperthyroidism].

Total L-thyroxine and triiodo-L-thyronine serum concentrations have been measured in 70-day-old male rats under normal conditions (controls) and in rats subjected to several experimental alterations of the thyroid function: hyperthyroidism, hypothyroidism and substitutive treatments. Since some problems appear when standard curves are performed with hormone serum, as consequence of differences in the affinity and inhibitory effects between heterologous proteins at the antigen-antibody reaction, RIA in this work has been carried out with standard curves performed with rat serum maintaining similar protein concentrations in standard and problems. This modification avoids errors by the use of extraction methods and shows a high degree of similarity between standard and problems.

Influence of thyroid hormone deficiency on the citrate synthase activity in rat brain regions during early postnatal development.

The developmental pattern of citrate synthase activity has been studied in the liver and several brain areas of hypothyroid rats during the 4 first weeks of life. While citrate synthase activity in the liver showed a rise during the 2 first weeks of life, different patterns of enzyme activity were found in the brain regions of euthyroid animals. Citrate synthase activity increased in the cerebellum, decreased in the cerebral cortex and did not change significantly in the brain stem during the period studied.

Regulation of starch synthesis: enzymological and genetic studies.

Significant advances have been made with respect to elucidating the structure, the allosteric site, interactions of effectors, covalent modifications, and the amino acid sequence of the ADPG synthetase. It is hoped that in the near future, sufficient information will be obtained to enable facile manipulation of the plant tissue ADPG synthetase gene and its product.

Activities of glycolytic enzymes in some brain areas of thyroidectomized rats and their response to replacement therapy.

Glycolytic metabolism has been assessed by studying a set of key enzymes, in anterior cortex, amygdala, hypothalamus septum and hippocampus, in thyroidectomized rats. The reversibility of the changes induced by the thyroidectomy has been assessed by replacement therapy. In thyroidectomized rats the hexokinase activity was significantly decreased in anterior cortex and hypothalamus.