Immunolocalization of β-1-4-galactan and its relationship with lignin distribution in developing compression wood of Cryptomeria japonica

Compression wood (CW) contains higher quantities of β-1-4-galactan than does normal wood (NW). However, the physiological roles and ultrastructural distribution of β-1-4-galactan during CW formation are still not well understood. The present work investigated deposition of β-1-4-galactan in differentiating tracheids of Cryptomeria japonica during CW formation using an immunological probe (LM5) combined with immunomicroscopy. Our immunolabeling studies clearly showed that differences in the distribution of β-1-4-galactan between NW (and opposite wood, OW) and CW are initiated during the formation of the S₁ layer. At this stage, CW was strongly labeled in the S₁ layer, whereas no label was observed in the S₁ layer of NW and OW. Immunogold labeling showed that β-1-4-galactan in the S₁ layer of CW tracheids significantly decreased during the formation of the S₂ layer. Most β-1-4-galactan labeling was present in the outer S₂ region in mature CW tracheids, and was absent in the inner S₂ layer that contained helical cavities in the cell wall. In addition, delignified CW tracheids showed significantly more labeling of β-1-4-galactan in the secondary cell wall, suggesting that lignin is likely to mask β-1-4-galactan epitopes. The study clearly showed that β-1-4-galactan in CW was mainly deposited in the outer portion of the secondary cell wall, indicating that its distribution may be spatially consistent with lignin distribution in CW tracheids of Cryptomeria japonica.     

Monodeiodination of thyroxine to 3, 5, 3'-triiodothyronine and to 3, 3', 5'-triiodothyronine in isolated dog renal cortical tubuli

Monodeiodination of T4 to T3 and rT3 in the intact cells of dog renal tubuli and glomeruli was investigated. The tubuli and glomeruli were obtained by a sieve method. T4 (2 micrograms/ml) was incubated in Tris-HCl buffer, pH 7.5, with renal cells (180 micrograms protein/ml) and 5 mM DTT for 1 h at 37 degrees C and the T3 and rT3 generated during incubation were measured by specific radioimmunoassays. In order of decreasing activity, dog renal cortical tubuli, cortical homogenate, glomeruli and medullary tubuli were capable of converting T4 to T3. Net rT3 production from T4 in cortical tubuli was also greater than that in cortical homogenate. The conversion of T4 to T3 and also to rT3 in cortical tubuli was enzymatic in nature, since the reactions showed dependence on time and protein concentration; instability to heating; temperature and pH optimum. The production of T3 and rT3 from T4 was maximum at pH 6.5 and at pH 9.5, respectively, indicating that two different enzymic systems, a 5- and a 5'-monodeiodinase, might be involved in the deiodination of the tyrosyl and the phenolic ring of T4 in dog kidney.     

Ischemic flow threshold for striatal dopamine release in rats

To determine the level of cerebral blood flow reduction which causes striatal dopamine release, extracellular dopamine and cerebral blood flow was simultaneously determined using in vivo brain dialysis and a hydrogen clearance method, respectively, in the striatum of spontaneously hypertensive rats, before and during experimental cerebral ischemia. The ischemic flow threshold for neurotransmitter dopamine release was found to be 20% of the resting value or 8–10 ml/100g/min of cerebral blood flow, being similar to those for energy and membrane failures.     

Three main components in plasma proteases and their relation to the renin-angiotensin system

The relation of plasma renin activity (PRA) and plasma levels of angiotensin I (AI) and II (AII) to those of various proteases, including eight endopeptidases and four aminopeptidases, was investigated in 51 normal control subjects. The multivariate study using factor analysis showed that the plasma proteases can be classified into three main components: the aminopeptidase, the plasmin, and the kinin-kallikrein. PRA and AI were related almost exclusively to the aminopeptidase component, while the AII level was related not only to the same component but also to the kallikrein-kinin component. This kind of multivariate study may help in the elucidation of the role of proteases and bioactive peptides, such as angiotensin derivatives, in essential hypertension through a comparison of multivariate relationships in controls and patients.     

Requirement of c-kit for development of intestinal pacemaker system.

A discovery that the protooncogene encoding the receptor tyrosine kinase, c-kit, is allelic with the Dominant white spotting (W) locus establishes that c-kit plays a functional role in the development of three cell lineages, melanocyte, germ cell, and hematopoietic cell which are defective in W mutant mice. Recent analyses of c-kit expression in various tissues of mouse, however, have demonstrated that c-kit is expressed in more diverse tissues which are phenotypically normal in W mutant mice. Thus, whether or not c-kit expressed outside the three known cell lineages plays a functional role is one of the important questions needing answering in order to fully elucidate the role of c-kit in the development of the mouse. Here, we report that some of the cells in smooth muscle layers of developing intestine express c-kit. Blockade of its function for a few days postnatally by an antagonistic anti-c-kit monoclonal antibody (mAb) results in a severe anomaly of gut movement, which in BALB/c mice produces a lethal paralytic ileus. Physiological analysis indicates that the mechanisms required for the autonomic pacing of contraction in an isolated gut segment are defective in the anti-c-kit mAb-treated mice, W/Wv mice and even W/+ mice. These findings suggest that c-kit plays a crucial role in the development of a component of the pacemaker system that is required for the generation of autonomic gut motility.     

Modulation of postinhibitory increase in plasma prolactin by domperidone in patients with prolactin secreting adenoma

To evaluate the PRL secretory mechanism in patients with PRL-secreting adenoma (PRL-oma), plasma PRL responses to dopamine (DA) were studied in these cases and in normal subjects. Plasma PRL values showed clear decreases during the infusion of DA (5 micrograms/kg/min for 90 min) in both 6 normal and 7 PRL-oma subjects (%decrease: 43.8 +/- 3.9% vs. 53.9 +/- 5.6%; NS) and postinhibitory increases after the termination. However, the postinhibitory increase occurred more promptly and markedly in PRL-oma patients than in normal subjects, i.e. the postinhibitory increase exceeded the basal level 45 min after the termination of DA infusion in PRL-oma patients, whereas the increase in normal subjects did not exceed the basal level even 90 min after the infusion. When domperidone was injected at the termination of DA infusion, the postinhibitory increases were significantly enhanced in either PRL-oma or normal subjects. The maximal increments in plasma PRL in the combination test of DA plus domperidone were significantly larger in PRL-oma patients, but were almost the same in normal controls, compared to the single domperidone test. In contrast, TRH did not modify the postinhibitory rises in 9 PRL-oma patients. These results indicate that the secretory properties and the sensitivities of lactotrophs to decreasing action of DA might be different between PRL-oma patients and normal controls. Further, the postinhibitory rebound phenomenon in PRL-oma patients is possibly determined by an overshoot of PRL storage concomitantly with a decreasing DA action.(ABSTRACT TRUNCATED AT 250 WORDS)