Glucagon, glicentin, proglucagon, PYY, PP and proPP-icosapeptide immunoreactivities of rectal carcinoid tumors and related non-tumor cells

Glucagon/PP-related peptides were detected immunohistochemically in 18 out of 22 cases of rectal tumors investigated. The reactive tumors showed prevalence of trabecular or mixed trabecular-acinar structure and moderate staining with Grimelius' silver and lead-hematoxylin. Three of the remaining 4 cases were characterized by reactivity for 5-hydroxytryptamine only, prevalence of a solid nest structural component and intense staining with Grimelius' silver technique and lead-hematoxylin. Fifteen of the 18 glucagon/PP-reactive cases were investigated immunohistochemically with a series of 6 sera directed against different sequences of glucagon, glicentin and proglucagon, and of 7 sera directed against PP, PYY and proPP-icosapeptide. A large spectrum of glucagon-related immunoreactivities, including C-terminus and mid-portion glucagon-immunoreactivity, N- and C-terminus glicentin-immunoreactivity, GLP1- and GLP2-immunoreactivity, were detected in human rectal L cells and most rectal carcinoids. With the exception of a few scattered cells in the rectal mucosa and in 3 tumors, C-terminus glucagon-immunoreactivity was obtained only after trypsin or subtilisin treatment of tissue sections. Both PYY and PP/proPP-like peptide(s) were detected in rectal L cells and carcinoids, with prevalence of PYY in normal cells and PP/proPP-like peptides in tumor cells. It is concluded that the same or closely related hormone/prohormone sequences are synthesized and stored in rectal endocrine cells and carcinoid tumors although differences of quantitative expression, post-translational cleavage or reactivity to antibodies may occur. The usefulness of protease treatments of tissue sections to unmask immunoreactivities of uncleaved propeptides or fixative-denatured peptides is outlined.     

Galanin and vasoactive intestinal polypeptide are colocalised with classical pituitary hormones and show plasticity of expression

The identity of galanin- and vasoactive intestinal polypeptide-(VIP) immunoreactive (IR) cells in the rat anterior pituitary was investigated using immunocytochemistry and, since levels of both peptides are stimulated by oestrogen, the effect of oestrogen treatment and gonadectomy on the expression of both peptides was examined. In normal male rats, few galanin-IR and very few VIP-IR cells were found. Colocalisation studies performed on 2-microns serial paraffin sections revealed that in these animals galanin IR was present in somatotrophs and thyrotrophs. In normal females in dioestrus many lactotrophs, in addition to somatotrophs and thyrotrophs, expressed galanin, but very few VIP-IR cells were seen. In cryostat sections of normal rat pituitaries, slightly more VIP-IR cells were present. Oestrogen treatment in females produced an increase in frequency of galanin-IR cells, the vast majority of which were lactotrophs, and more VIP-IR cells, identified as lactotrophs, also appeared. VIP was present in a subset of galanin-IR lactotrophs after oestrogen treatment. After ovariectomy female pituitaries resembled those of normal males, with few galanin positive cells none of which were lactotrophs, and hardly any VIP-IR cells. Thus these two peptides are present in specific endocrine cell types of rat anterior pituitary and display plasticity of expression in different cell types under the influence of oestrogen. Their roles in control of pituitary hormone secretion are supported by these findings, and it is possible that both peptides act in a paracrine fashion within the pituitary.     

Phytochrome elicits the cryptic red-light signal which results in amplification of anthocyanin biosynthesis in sorghum

Anthocyanin synthesis in Sorghum bicolor Moench induced by a low-fluence response of phytochrome (phy) is multiplicatively amplified by a cryptic red-light signal (CRS) produced by red light (R). The photoreceptor for CRS and its features in CRS production were studied. (i) An action spectrum determined with a 200-s light pulse of wavelengths from 347 to 693 nm had peaks at 657 and 378 nm. (ii) The CRS-producing effect of R, even as short a pulse as 20 s, was neither suppressed by an immediately subsequent far-red light (FR) pulse nor increased by placing a dark interval of 180 s between R and FR; simultaneous FR, however, suppressed the R action in accordance with the resulting ratios of the FR-absorbing form (Pfr) to total phy. (iii) The effect of R increased with increasing fluence rate to plateau at the same fluence rate regardless of the pulse length, but the level of this plateau depended on the pulse length. (iv) The effect of R increased with increasing pulse length when compared at the same fluence, whether saturating or unsaturating; thus, no reciprocity law holds. These results indicate that the photoreceptor for CRS production is a phy, Pfr being active, which presumably shows very fast dark reversion to the R-absorbing form without absorbing FR. The possible CRS-production mechanism of the phy and its significance in the so-called R high-irradiance response of phy are discussed. Received: 26 June 1998 / Accepted: 27 July 1998     

Simplified Isoelectric Focusing Columns of Small Scales

ABSTRACT

Citrus plants are rich in flavonoids and beneficial for lipid metabolism. However, the mechanism has not been fully elucidated. Both citrus peel flavonoid extracts (CPFE) and a mixture of their primary flavonoid compounds, namely, nobiletin, tangeretin and hesperidin, citrus flavonoid purity mixture (CFPM), were found to have lipid-lowering effects on oleic acid-induced lipid accumulation in HepG2 cells. The carnitine palmitoyltransferase 1α (CPT1α) gene was markedly increased, while the fatty acid synthase (FAS) gene was significantly decreased by both CPFE and CFPM in oleic acid-treated HepG2 cells. Flavonoid compounds from citrus peel suppressed miR-122 and miR-33 expression, which were induced by oleic acid. Changes in miR-122 and miR-33 expression, which subsequently affect the expression of their target mRNAs FAS and CPT1α, are most likely the principal mechanisms leading to decreased lipid accumulation in HepG2 cells. Citrus flavonoids likely regulate lipid metabolism by modulating the expression levels of miR-122 and miR-33.     

Copy Number Analysis Identifies Novel Interactions Between Genomic Loci in Ovarian Cancer

Ovarian cancer is a heterogeneous disease displaying complex genomic alterations, and consequently, it has been difficult to determine the most relevant copy number alterations with the scale of studies to date. We obtained genome-wide copy number alteration (CNA) data from four different SNP array platforms, with a final data set of 398 ovarian tumours, mostly of the serous histological subtype. Frequent CNA aberrations targeted many thousands of genes. However, high-level amplicons and homozygous deletions enabled filtering of this list to the most relevant. The large data set enabled refinement of minimal regions and identification of rare amplicons such as at 1p34 and 20q11. We performed a novel co-occurrence analysis to assess cooperation and exclusivity of CNAs and analysed their relationship to patient outcome. Positive associations were identified between gains on 19 and 20q, gain of 20q and loss of X, and between several regions of loss, particularly 17q. We found weak correlations of CNA at genomic loci such as 19q12 with clinical outcome. We also assessed genomic instability measures and found a correlation of the number of higher amplitude gains with poorer overall survival. By assembling the largest collection of ovarian copy number data to date, we have been able to identify the most frequent aberrations and their interactions.     

Studies of the guinea-pig epididymis

Summary The innervation of the ductuli efferentes and seven zones of the guinea-pig epididymis was investigated using immunohistochemical, histochemical and electron-micro-scopical techniques. Nerve fibers were localized by use of antibodies against substance P (SP-IR), vasoactive intestinal polypeptide (VIP-IR) and dopamine-beta-hydroxylase (DBH-IR). In the ductuli efferentes and all zones of the epididymal duct, SP-IR is consistently observed in the interstitial tissue and perivascular areas. Histochemistry reveals a significant amount of acetylcholinesterase-containing fibers in the interstitial, perivascular and periductal smooth muscles of the ductuli efferentes and zones V, VI and VII. In contrast to the homogeneous distribution of SP-IR within all zones of the epididymis, VIP-IR is seen only in zones VI and VII. Within these zones, VIP-IR is detected in large amounts in the subepithelial and muscular layers as is a sparse number of SP-IR varicosities. DBH-IR is also seen throughout all zones in the interstitial and perivascular regions with a tendency to increase in zones VI and VII. Transmission electron microscopy (TEM) reveals evidence of a cholinergic (agranular vesicles, AGV), adrenergic (small granular vesicles, SGV) and peptidergic (large granular vesicles, LGV) innervation throughout the interstitial connective tissue of the ductuli efferentes and all epididymal zones. Furthermore AGV are localized in the subepithelial layer, and also co-stored with LGV in the muscular layer of zones VI and VII. No nerve profiles were encountered within the epithelium.Correlation of immunohistochemical findings to TEM counterparts as well as their possible functional role are discussed.Supported by the Deutsche Forschungsgemeinschaft     

Leumorphin is a novel endogenous opioid peptide in man

Porcine leumorphin, a putative opioid peptide corresponding to amino acid residues 228-256 of preproenkephalin B has been demonstrated to exist in the porcine neurointermediate pituitary. A recent study on the sequence analysis of genomic DNA of human preproenkephalin B has shown that human leumorphin differs in 3 amino acid residues from porcine leumorphin. In order to clarify whether leumorphin is an endogenous opioid peptide in man, we have studied its existence in the human brain using a radioimmunoassay and its opioid activity by a bioassay with the guinea-pig ileum myenteric plexus-longitudinal muscle preparation. High performance gel permeation chromatography and reverse-phase high performance liquid chromatography coupled with the radioimmunoassay for leumorphin have revealed that human leumorphin exists in water extracts of the human striatum. In the guinea-pig ileum assay, synthetic human leumorphin exhibited potent opioid activity, with the concentration of 3nM to give 50 per cent inhibition. These results indicate that leumorphin is a novel endogenous opioid peptide in man.     

Coexistence of catecholamine and methionine enkephalin-Arg6-Gly7-Leu8 in neurons of the rat ventrolateral medulla oblongata. Application of combined peptide immunocytochemistry and histofluorescence method in the same vibratome section

An overlapping distribution of catecholamine-containing cells and proenkephaline-A derived peptide-containing neurons have been identified in the rat medulla oblongata. However, it is not evident whether the coexistence of these bioactive substances occurs in the same neurons or not. Therefore, we examined the coexistence of catecholamine and methionine-enkephalin-Arg6-Gly7-Leu8 (MEAGL), a proenkephaline-A derived peptide, using a combination of histofluorescence and peroxidase-anti-peroxidase (PAP) immunohistochemical (modified formaldehyde-glutalaldehyde (Faglu)) methods on the same tissue sections. We found one third of A1/C1 catecholamine fluorescent cells show MEAGL-like immunoreactivity.