Parathyroid hormone-related protein is a possible autocrine growth inhibitor for lymphocytes

Adult T-cell leukemia (ATL)-related cells have the ability to produce a newly-isolated calcium-regulating protein, parathyroid hormone-related protein (PTHrP). The present study revealed that lectin-stimulated normal lymphocytes produce immunoreactive (IR)-PTHrP. When the T-cell-enriched fraction was purified from normal lymphocytes and then treated with lectin, a similar amount of IR-PTHrP was detected, suggesting that IR-PTHrP is an actual product of T-lymphocytes. A biologically active fragment of PTHrP, PTHrP(1-34), suppressed DNA synthesis in lectin-stimulated lymphocytes at concentrations greater than 50 pg/mL; the same concentration range of IR-PTHrP detected in the cultured media of lectin-stimulated lymphocytes. Therefore, it is reasonable to postulate that PTHrP is a cytokine inhibiting the cellular growth of normal lymphocytes.     

Regulation by induction of branched-chain 2-oxo acid dehydrogenase complex in clofibrate-fed rat liver.

The activity of branched-chain 2-oxo acid dehydrogenase complex increased 3.0-fold in liver of rats fed on 0.1%(w/w) clofibrate. Immunotitration experiments with antibodies against the constituent enzymes of the complex revealed that this increase resulted mainly from the increased amounts of only two(a decarboxylase and a lipoate acyltransferase) of three components of the complex and that the other component(dihydrolipoamide dehydrogenase) remained unchanged in its content, irrespective of clofibrate administration. The increases of both enzyme components were associated with increases in their mRNA levels which were estimated by in vitro translation with poly(A)+ RNA.     

Analysis of the oligosaccharides in ovalbumin by high-performance capillary electrophoresis

The oligosaccharides in ovalbumin as a glycoprotein model were released with anhydrous hydrazine, and reductively pyridylaminated after re-N-acetylation. The derivatives were analyzed by capillary zone electrophoresis (CZE) with on-column fluorometric detection. Direct CZE could separate the derivatives on the basis of the degree of polymerization, giving five peaks of hepta-, octa-, nona-, deca-, and undecasaccharides. Coelectrophoresis with the standard mixture of isomaltooligosaccharide derivatives was effective for peak assignment. CZE as borate complexes allowed separation on the basis of structural difference, especially in the peripheral monosaccharide residues. Peaks were tentatively assigned to the derivatives of reported oligosaccharides by comparing their relative mobilities with those of the chromatographic fractions obtained by using the ODS and Dowex 50W x 2 columns. These two modes gave excellent separation and were complementary to each other. Although the actual amount analyzed in the capillary tube was quite small (ca. 5 ng as carbohydrates), a larger amount (ca. 25 micrograms as carbohydrates) was required to make sample concentration sufficiently high to be detected by a modification of a commercial fluoromonitor for HPLC.     

Preventive effect of angiotensin I on weight reduction in the adrenal glands of DOCA/salt hypertensive rats

We examined the effect of angiotensin I (AI), without the effect of angiotensin II (AII) converted from AI, on the weight of the adrenal glands, adrenal corticosterone (B) and adrenal aldosterone under conditions where the renin-angiotensin system was suppressed, since a reduction in the size of the adrenal glands is often observed in DOCA/salt hypertensive rats. Sixty male Wistar rats fed on a 1% NaCl solution were divided into 6 groups as follows: a) Salt group: received sesame oil and vehicle, b) Salt + C group: received sesame oil and MK422 (0.14 mg/day), an angiotensin converting enzyme inhibitor (CEI), c) DOCA group: received DOCA (30 mg/week) and vehicle, d) DOCA + A group: received DOCA and AI (0.5 mg/kg/day), e) DOCA + A + C group: received DOCA and AI with MK422, and f) DOCA + C group: received DOCA and MK422. After 4 weeks, the rats were sacrificed to sample their blood and remove their adrenal glands. There was no significant difference in adrenal B among the groups apart from the DOCA + C group. Adrenal aldosterone was lower in the groups of DOCA/salt hypertensive rats than in the Salt group and Salt + C group. Furthermore, the DOCA + A + C group and DOCA + C group had lower adrenal aldosterone levels than the DOCA group and DOCA + A group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Formation of amino acids from reactor-irradiated ammonium acetate

Ammonium acetate in various conditions was irradiated in a reactor to examine the contributions of both the reactor radiations and recoiled¹⁴C nucleis to form the biologically interesting molecules. Present investigations demonstrated that several amino acids, glycine, alanine, -alanine and GABA, and may-be aspartic acid, serine and valine by prolonged irradiation, were formed in the aqueous solutions of ammonium acetate.¹⁴C-radioactivities were also found distributed in these amino acids. However, no special relationship between¹⁴C-radioactivity and these amino acids formed was observed.     

The binding of ATP to the catalytic and the regulatory site of Ca2+,Mg2+-dependent ATPase of the sarcoplasmic reticulum

Two kinds of ATP binding sites were found on the ATPase molecule in deoxycholic acid-treated sarcoplasmic reticulum. One was the catalytic site (1 mol/mol active site) and its affinity was high. Upon addition of Ca²⁺, all the ATP bound to the catalytic site disappeared at 75 mM KCl, while a significant amount of ATP remained bound to the site at 0–2 mM KCl. The latter binding was found to be due to the formation of a slowly exchanging enzyme-ATP complex, which is in equilibrium with phosphoenzyme + ADP. The other binding site was the regulatory one (1 mol/mol active site) and its affinity was low, changing only insignificantly upon addition of Ca²⁺. The ATP binding to the regulatory site shifted the equilibrium between the slowly exchanging complex and EP toward EP.     

An anchorage-dependent locus in the cell cycle for the growth of 3T3 cells

Mouse fibroblasts, 3T3 cells, require a solid surface for continuous growth, but when 3T3 cells, during their exponential phase in Petri dishes, were transferred to a suspension culture, the number of cells roughly doubled by 30 h. During the suspension culture the number of pairing cells (c₂) increased, but that of the single cells decreased. When cells synchronized at mitosis or at the G1-S boundary were transferred to the suspension culture, the number of pairing cells peaked at 30 min and at 10 h, respectively. DNA synthesis began immediately after the cells, which were cultured for 16 h in the suspension, had settled onto the surface of the Petri dishes. When cells in a confluent culture were arrested at an early G1 period and were suspended, the number of pairing cells did not increase. These results indicate that the most important locus for anchorage growth seems to be at a late G1 period of the cell cycle.     

The measurement of intracellular sodium activities in the bullfrog by means of double-barreled sodium liquid ion-exchanger microelectrodes.

A double-barreled Na+-selective microelectrode was constructed with monensin as a liquid ion exchanger. The HCl-treated monensin was dissolved in a solvent (Corning 477317) at 10% (weight/weight). Internal reference solution of its ionic barrel was mixture of 0.49 M NaCl and 0.01 M KCl, the pH being adjusted to 3 with 0.1 M citrate-HCl buffer, whereas that of the PD barrel was 0.5 M KCl. Average slope and selectivity ratio (Na+/K+) tested on 10 different microelectrodes were -57.5 +/- 1.87 mV/P(Na) (SEM) and 6.7 +/- 0.44, respectively. The electrical resistance was an order of 10(10) ohm and the response time was less than 10 sec. Using this microelectrode, a free flow micropuncture experiment was carried out in the bullfrog kidney and the intracellular Na+ activity as well as the membrane PD was determined on the proximal tubular cell. Average value (+/- SEM, n = 15) for the intracellular Na+ and K+ was 20.7 +/- 1.56 mEq/L and 61.2 +/- 1.16 mEq/L, respectively, and -68.7 +/- 0.88 mV for the peritubular membrane PD. There was a significant negative correlation between Na+ and K+ activities within the cell, i.e., the lower the ionic activity of cellular Na+ was, the higher the cellular K+, and vice versa, the sum of these two being kept nearly constant. The above finding may be somehow related to the isosmosis in the reabsorptive process across the proximal tubular epithelium.     

Studies of oligosaccharide linkages by simultaneous determination of component aldehydes in dialdehyde fragments as (2,4-dinitrophenyl)hydrazones

The component aldehydes in dialdehyde fragments formed by periodate oxidation of oligosaccharides were converted quantitatively into the corresponding (2,4-dinitrophenyl)hydrazones by the simple procedure of treatment with excess (2,4-dinitrophenyl)hydrazine hydrochloride in 1,2-dimethoxyethane. Then, by chromatographic separation of the hydrazones on a small column of silica gel and subsequent spectrophotometric analysis, it was possible to determine the position of glycosidic substitution in μmolar amounts of various types of glucobioses, oligosaccharides of senega, and some synthetic (1→6)-β-D-gluco-oligosaccharides.     

Metabolism of PG in man: Effect of furosemide on the excretion of the main metabolite of PG F2α

The excretion rates of main urinary metabolite of PG F₂α were measured radioimmunologically in 4 healthy persons and in 13 essential hypertensives. The resting values were 9.3±0.73 in the former and 10.4±2.17 ng/min in the latter. There was no significant differences between them. The excretion of the metabolite decresed prominently after the administration of furosemide. The percent decrease was 57% in healthy persons and 70% in essential hypertension. The percent result supports that furosemide inhibit the catabolism of PG F₂α.