Pancreatic islet cells are especially vulnerable to damage by various oxygen derived free radicals. Free radicals generated by cells of the immune system play a key role in the cellular pathogenesis of type I diabetes (Rabinovitch 1992). Furthermore, a variety of diabetogenic drugs, most notably alloxan (Sakurai and Miura 1989) and streptozotocin (Nukatsuka, Sakurai, Yoshimura, Nishida and Kawada 1988), exert their effects via free radical generation. To combat freeradical damage, islets contain various scavenging enzyme systems, among the most prominent of which is superoxide dismutase (SOD) (Asayama, Kooy and Burr 1986; Crouch, Gandy, Kimsey, Galbraith, Galbraith and Buse 1981; Grankvist, Marklund and Taljedal 1981). This enzyme, which scavenges superoxide radicals, can protect against both alloxanand streptozotocin-induced diabetes in vivo (Papaccio, Pisanti and Frascatore 1986; Thaete, Crouch, Buse and Spicer 1985) and islet B-cell destruction in vitro (Fischer and Hamburger 1980).

We have examined a wide range of cultured human tumor cell lines and found that a specific subset of tumors expresses the cholecystokinin (CCK) gene. All neuroepitheliomas (eight) and Ewing sarcoma (eight) cell lines that were tested express CCK RNA. In addition, two of six rhabdomyosarcoma cell lines also express the CCK gene, suggesting that rhabdomyosarcomas are probably heterogenous and that a subset may be similar to Ewing sarcoma and neuroepithelioma. Very few of the positive tumors express completely processed immunoreactive CCK. However, we have used a radioimmunoassay that detects the CCK precursor to demonstrate synthesis of CCK precursor-like peptides by all of the Ewing sarcoma and neuroepithelioma lines that were tested and by the rhabdomyosarcoma cell line that expresses CCK mRNA. These data demonstrate a consistent association of CCK gene expression with a specific group of human neoplasms. The data also add credence to the theory that Ewing sarcoma and neuroepithelioma are derived from the same transformed cell type. Finally, our results suggest that CCK gene expression may serve as a marker to distinguish these tumors, which are considered to be small-round-cell tumors of childhood, from other pediatric tumors.

Tetracycline antibiotics (TETs) have a recently discovered novel action: inhibition of extracellular metalloproteinase activity, especially that of collagenase and gelatinase. This property, now confirmed in 8 different laboratories using >40 tissue sources, includes natural and semi-synthetic TETs as well as a chemically modified TET (CMT) devoid of antimicrobial activity. We have used 14C-Tyr biosynthetically labelled intracellular proteins in L-6 myoblast culture as a test system to assess intracellular proteolysis. Starvation accelerates proteolysis, which can be suppressed by agents such as insulin or serum. Minocycline, doxycycline, and CMT all retarded the rate of intracellular protein degradation in a dose dependent manner. These agents also demonstrated marked synergism with insulin. A CMT derivative (pyrazole) stripped of one of its metal chelation sites and lacking anti-collagenase activity, also lost its antiproteolytic effect. CMT at physiologic concentrations (≤ 5 μg/ml) had no effect on protein synthesis, but at 15 μg/ml (pharmacologic), a suppressive effect was noted. These findings demonstrate that TETs can inhibit protein degradation as well as synthesis in a mammalian muscle-derived cell line.

Quantitative histomorphometric studies of the dynamics of growth and development of pancreatic islets in normal and pathological states pose substantial methodological and conceptual problems. We address these problems with the geometry of random fractals, and apply our methods to the analysis of islet regeneration in the alloxan-treated guinea-pig. In both experimental islet-regenerated and control animals, islet centres are found to cluster in similar fractal subsets of dimension strictly less than 3, in agreement with the postulated origin of islets along a system of ductules, and suggesting that regeneration follows the same mathematical dynamics as original islet formation.

We have used a sensitive radioimmunoassay to quantify and characterize PBMC-associated immunoreactive ACTH (ACTH-IR). Mean ACTH content of freshly isolated human PBMCs was 3.8 +/- 0.72 pg (SEM) per 10(6) cells. During 3 days of incubation ACTH-IR in conditioned media of control PBMCs increased significantly, p less than 0.02. Gel filtration chromatography revealed a minor peak of ACTH-IR coeluting with ACTH (1-39) and a major peak coeluting with ACTH (11-24). Treatment with 15 nM CRH did not alter the amount of ACTH-IR secreted or its gel pattern. Synthetic ACTH (11-24), was radioiodinated and was used for binding experiments that demonstrated specific high- and low-affinity binding sites for ACTH (11-24) on a human T cell line. These results add support for a role of ACTH and related peptides in immune regulatory systems and suggest that cell-specific post-translational processing of POMC may generate an expanding number of biologically active moieties.

Antisera to guinea pig insulin are not commonly available, largely because of the short supply and limited immunogenicity of the intact hormone. To overcome these problems we have employed a novel reagent, synthetic guinea pig insulin B-chain C-terminal decapeptide, as a hapten for raising antibodies that react with intact guinea pig insulin. The decapeptide, coupled to bovine serum albumin, was successfully used as an immunogen in rabbits. The resulting antiserum was employed for immunocytochemical staining of guinea pig insulin in pancreatic sections. The specificity of the staining was verified by both pre-absorption and preimmune serum controls. The utility of this new antiserum for investigations of guinea pig insulin physiology is discussed.

Antisera to guinea pig insulin are not commonly available, largely because of the short supply and limited immunogenicity of the intact hormone. To overcome these problems we have employed a novel reagent, synthetic guinea pig insulin B-chain C-terminal decapeptide, as a hapten for raising antibodies that react with intact guinea pig insulin. The decapeptide, coupled to bovine serum albumin, was successfully used as an immunogen in rabbits. The resulting anti-serum was employed for immunocytochemical staining of guinea pig insulin in pancreatic sections. The specificity of the staining was verified by both pre-absorption and pre-immune serum controls. The utility of this new antiserum for investigations of guinea pig insulin physiology is discussed.

Annals of the New York Academy of SciencesVolume 594, Issue 1 p. 413-415 Mononuclear Leukocytes Produce and Specifically Bind a Novel ACTH-related Peptide GARY M. PEPPER, Corresponding Author GARY M. PEPPER The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451G.M.P., NYHHC, Lincoln Hospital Medical Center, 234 East 149th Street, Room 8-29, Bronx, NY 10451.Search for more papers by this authorJONATHAN MAIMON, JONATHAN MAIMON The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451Search for more papers by this authorBRUCE SCHNEIDER, BRUCE SCHNEIDER The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451Search for more papers by this author GARY M. PEPPER, Corresponding Author GARY M. PEPPER The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451G.M.P., NYHHC, Lincoln Hospital Medical Center, 234 East 149th Street, Room 8-29, Bronx, NY 10451.Search for more papers by this authorJONATHAN MAIMON, JONATHAN MAIMON The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451Search for more papers by this authorBRUCE SCHNEIDER, BRUCE SCHNEIDER The Division of Endocrinology Long Island Jewish Medical Center New Hyde Park, New York 10451Search for more papers by this author First published: June 1990 https://doi.org/10.1111/j.1749-6632.1990.tb40513.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume594, Issue1Neuropeptides and Immunopeptides: Messengers in a Neuroinunune AxisJune 1990Pages 413-415 RelatedInformation

Cultured L6 myoblasts afford considerable advantages for identifying and studying the insulin-like actions of test substances in a muscle-derived line. We have used this system to examine the interaction of the oral hypoglycemic sulfonylurea glyburide with bovine insulin on protein degradation and synthesis as well as on thymidine incorporation (as a measure of DNA synthesis) in these cells. Bovine insulin, at doses of 0.1 μg/mL to 10 μg/mL, produced a dose-dependent inhibition of protein degradation (measured by release of trichloracetic acid (TCA)-soluble 14C-tyrosine from myoblasts into the culture medium) and increase in total protein content in the cultured myoblasts. At concentrations of 10 μg/mL, insulin achieved its maximal suppression of protein degradation (by nearly 50%) and increased cellular protein content (by 15%) over levels observed in the absence of added insulin. Glyburide, at concentrations at or above 1 μg/mL, significantly suppressed protein degradation (up to 14%) and slightly augmented protein content of the cells. The effects of glyburide on protein degradation were additive with those of submaximally but not maximally effective concentrations of insulin, suggesting a common mechanism of action of the compounds. Both insulin and glyburide, at maximally effective doses, significantly depressed protein degradation as early as 2 to 6 hours after exposure. In addition, in a 24-hour labeling experiment, insulin stimulated tyrosine incorporation into TCA-insoluble protein and thymidine incorporation into DNA in the cells, whereas glyburide did not enhance these processes and, under certain conditions, inhibited them. These results demonstrate that glyburide, either alone or in concert with insulin, is capable of significantly inhibiting protein turnover in skeletal muscle-derived cells. The physiological implications of these observations are discussed.

We have developed a radioimmunoassay for the nonapeptide predicted by cDNA sequence analysis to reside at the extreme C-terminus of the mouse cholecystokinin (CCK) precursor. Sensitivity of the assay is 1 pg synthetic CCK precursor-related peptide (CCK-PRP)/ml. The antibody has no cross-reactivity with cholecystokinin, gastrin, or a variety of other known neuropeptides. We have employed this assay to demonstrate the presence, in rodent brain, gut, and peripheral plasma, of peptides with immunological properties that are identical to, and gel filtration characteristics that are very similar to, those of the synthetic CCK-PRP. We have also detected a similar peptide in the culture media of a human CCK-producing tumor. The molar ratios of immunoreactive CCK-PRP/CCK vary widely among tissues of origin and during ontogeny, suggesting regional and developmental differences in the turnover rates or in posttranslational modification of the two peptides. Our studies suggest that peptides very similar to intact CCK-PRP are posttranslationally liberated from the cholecystokinin precursor in a variety of tissues and may have neurotransmitter and/or hormonal functions distinct from those of CCK. Relatively high quantities of material immunologically indistinguishable from CCK-PRP were also found in several coelenterate species, indicating that this epitope arose as early in evolution as did CCK.