Retinoids enhance IgA production by lipopolysaccharide-stimulated murine spleen cells

The effect of all-trans retinoic acid (RA) and vitamin A on IgA production by LPS-stimulated murine spleen cells was studied. Concentrations of immunoglobulins of six subclasses in the culture medium were determined. Only IgA level increased, RA dose dependently. In contrast, IgG1 level decreased and other subclasses (IgM, IgG2a, IgG2b, and IgG3) were not significantly affected by the treatment. IgA levels in LPS-stimulated spleen cells were usually between 10 and 100 ng/ml. When RA was added at the concentrations above 0.1 nM, the levels were increased dose dependently and peak response (8- to 20-fold) was observed from 0.1 to 1 microM. Enhancement of IgA secretion begins after 4 days culture and then increases linearly until Day 7. Vitamin A also showed IgA-enhancing activity, although its activity was about 1/170 of that of RA. TGF-beta activity in the culture medium was also determined, finding that RA rapidly stimulates secretion of biologically active TGF-beta, the elevation being evident after 1 day of culture. Specific neutralizing antibodies to TGF-beta 1 and TGF-beta 2 partially inhibited IgA enhancement caused by RA. These results suggest that retinoids at physiological concentrations may act as positive regulators for IgA production and the effect may be mediated, at least in part, via the induction of active TGF-beta.

Islet amyloid polypeptide/amylin contents in pancreata increase in genetically obese and diabetic mice

To search for a possible relationship between islet amyloid polypeptide (IAPP)/amylin and the pathophysiology of type 2 diabetes mellitus, we examined IAPP contents in the pancreata of genetically obese and diabetic mice (C57BL/6J ob/ob and KK mice), at 24 weeks of age, using a specific radioimmunoassay. IAPP and insulin contents were noticeably increased in the ob/ob mice with marked obesity and moderate hyperglycemia. These contents slightly, but significantly increased in the KK mice with mild obesity and hyperglycemia. Thus, IAPP production is possibly influenced by factors coded by mutant genes and a possible relationship between IAPP and hyperglycemia in the strains of mice deserves further attention.

Purification and identification of TGF-beta 2-related growth factor from bovine colostrum

Bovine colostrum contains transforming growth factor (TGF)-beta-like activity. High levels of this activity are found in early colostrum (within 12 h after parturition); however, it decreases rapidly after 30 h. In this study, the activity in early colostrum was purified by a sequence of decaseination, DEAE-Sephacel chromatography, Sephadex G-100 gel filtration, precipitation at neutral pH, further gel filtration and reversed-phase FPLC. A homodimeric 23 kDa protein was identified that retained the TGF-beta-like activity. Its activity was completely neutralized by a specific anti-TGF-beta 2 antibody. These results indicate that the TGF-beta-like growth factor found in bovine colostrum is chemically and antigenically related to TGF-beta 2. The physiological roles of the TGF-beta 2-related growth factor are discussed.

Islet amyloid polypeptide/amylin in pancreatic beta-cell line derived from transgenic mouse insulinoma

We examined the production and secretion of IAPP in a beta-cell line, MIN6, which is derived from an insulinoma obtained by targeted expression of the SV40 T-antigen gene in a transgenic mouse. RNA blot analysis revealed an abundance of IAPP and insulin II mRNA in the cells, findings comparable with those in the pancreas of a normal mouse. The presence of IAPP and insulin was confirmed immunohistochemically and by RIA. Analysis of the reverse-phase HPLC identified IAPP in cells with authentic mouse IAPP. Raising the glucose concentration from 5.6 to 25 mM failed to induce increments in IAPP and insulin II mRNAs. The cells secrete IAPP and insulin for short- and long-term incubations in response to concentration of glucose in the medium. These features resemble those of islet cells from normal animals. This beta-cell line will aid in analyzing the regulation of IAPP gene expression and the mechanisms of IAPP biosynthesis and secretion.

Hypersecretion of IAPP from the islets of VMH-lesioned rats and obese Zucker rats

To investigate the possible role of islet amyloid polypeptide (IAPP) in the development of type 2 diabetes mellitus, we examined the IAPP content and secretion in pancreatic islets isolated from ventromedial hypothalamic (VMH)-lesioned rats and genetically obese Zucker rats, using a specific radioimmunoassay for IAPP. Obesity and hyperinsulinemia were observed in rats 21 days after VMH lesioning. IAPP content was increased in the islets of VMH-lesioned rats compared with findings in the sham-operated controls (100.9 +/- 6.6 vs 72.8 +/- 3.85 fmol/islet; P less than 0.01). Isolated islets of VMH-lesioned rats secreted larger amounts of IAPP in the presence of 2.8 and 16.7 mM glucose (2.99 +/- 0.98 and 11.2 +/- 0.29 fmol islet-1 3 h-1) than was noted in sham-operated rats (ND and 6.65 +/- 0.78 fmol islet-1 3 h-1). In the obese Zucker rats, aged 14 weeks, IAPP concentrations in the islets were elevated compared with lean rats (133.3 +/- 10.6 vs 84.4 +/- 8.5 fmol/islet; P less than 0.01). The isolated islets secreted larger amounts of IAPP in response to 2.8 and 16.7 mM glucose (2.83 +/- 0.88 and 15.81 +/- 1.35 fmol islet-1 3 h-1) than did those from lean control rats (0.36 +/- 0.19 and 12.49 +/- 1.20 fmol islet-1 3 h-1). These results strongly suggest that overproduction and hypersecretion of IAPP occur in animals with obesity and hyperinsulinemia.

Islet amyloid polypeptide-derived amyloid deposition increases along with the duration of type 2 diabetes mellitus

To investigate the involvement of islet amyloid polypeptide (IAPP) and amyloid deposits in the pathophysiology of this disease, we studied the relationship between IAPP-derived amyloid deposition and the clinical features in type 2 diabetes mellitus. We examined pancreata obtained from 37 type 2 diabetic subjects and 12 non-diabetic ones by immunohistochemical techniques using two specific antibodies to IAPP. IAPP-derived deposits occurred in 1 of the 12 (8.3%) non-diabetic subjects and 28 of the 37 (75.7%) diabetics. When diabetic patients were divided into categories according to the presence of the deposits, the duration of the disease was significantly longer in patients with amyloid than that in the patients without it. The odds ratio of type 2 diabetes mellitus of at least 14-years-duration to the deposition was significantly high, and a body weight of at least 120% maximal ideal body weight was relatively high. In conclusion, IAPP-derived amyloid deposition increases along with the duration of type 2 diabetes mellitus and obesity may further enhance these deposits, hence hypersecretion of IAPP may be involved in the progression of this disease.

Safety and efficacy of the cell-associated vaccine prepared by an attenuated infectious laryngotracheitis virus

The safety and efficacy of the cell-associated (C-A) vaccine prepared by chicken embryo fibroblast (CEF) cells infected with the tissue-culture-modified strain of infectious laryngotracheitis (ILT) virus were studied in chickens. Over seventy percent of chickens inoculated with the C-A vaccine by the subcutaneous (S.C.) or intramuscular (I.M.) route at 1 day of age was protected against challenge with a virulent strain of ILT virus without any clinical signs. Chickens vaccinated with the C-A vaccine at 1 day of age acquired immunity within 6 days after vaccination, and the protection rate maintained more than 60% until 10 weeks post-vaccination. The C-A vaccine was invariably effective for chickens at various age. There was no evidence that the development of immunity was hindered by further vaccination with Newcastle disease and infectious bronchitis combined live vaccine. In addition, the C-A vaccine was safe when chickens were inoculated with 10 doses. In the field trials of the C-A vaccine, no adverse reaction was observed, and over 65% of vaccinated chickens was protected against the challenge of the virulent ILT virus at 8 weeks after vaccination.

Hypersecretion of islet amyloid polypeptide from pancreatic islets of ventromedial hypothalamic-lesioned rats and obese Zucker rats

To investigate the possible role of islet amyloid polypeptide (IAPP) in the development of type 2 diabetes mellitus, we examined the IAPP content and secretion in pancreatic islets isolated from ventromedial hypothalamic (VMH)-lesioned rats and genetically obese Zucker rats, using a specific RIA for IAPP. Obesity and hyperinsulinemia were observed in rats 21 days after VMH lesioning. IAPP content was increased in the islets of VMH-lesioned rats compared with findings in the sham-operated controls (100.9 +/- 6.6 vs. 72.8 +/- 3.85 fmol/islet; P less than 0.01). Isolated islets of VMH-lesioned rats secreted larger amounts of IAPP in the presence of 2.8 mM and 16.7 mM glucose (2.99 +/- 0.98 and 11.2 +/- 1.29 fmol.islet(-1).3 h-1) than was noted in sham-operated rats (ND and 6.65 +/- 0.78 fmol.islet(-1).3 h-1). In the obese Zucker rats, aged 14 weeks, IAPP concentrations in the islets were elevated compared with lean rats (133.3 +/- 10.6 vs. 84.4 +/- 8.5 fmol/islet; P less than 0.01). The isolated islets secreted larger amounts of IAPP in response to 2.8 mM and 16.7 mM glucose (2.83 +/- 0.88 and 15.81 +/- 1.35 fmol.islet(-1).3 h-1) than did those from lean control rats (0.36 +/- 0.19 and 12.49 +/- 1.20 fmol.islet(-1).3 h-1). These results strongly suggest that overproduction and hypersecretion of IAPP occur in animals with obesity and hyperinsulinemia.

Amyloid protein in somatostatinoma differs from human islet amyloid polypeptide

Amyloid deposits in somatostatinomas are rare observations. To examine the characteristics of this amyloid, we compared amyloid deposits in a somatostatinoma to those found in pancreatic tissue in patients with Type II diabetes mellitus and in insulinomas, using immunohistochemical techniques and specific antibodies to islet amyloid polypeptide or other pancreatic hormones, as well as electron-microscopy. Antibodies to islet amyloid polypeptide regions 8-17 or 25-37 were confirmed to be specific. Amyloid deposits in patients with Type II diabetes mellitus and in insulinomas, but not those in the somatostatinoma strongly reacted with these antibodies, or to an antibody to amyloid P component. Amyloid deposits in the somatostatinoma were not reactive with antibodies to somatostatin or to other pancreatic hormones. Electron-microscopic examinations revealed that amyloid fibrils in the somatostatinoma were thinner and more randomly distributed than were those in islets from patients with Type II diabetes mellitus. As amyloid in somatostatinomas is unlike that consisting of islet amyloid polypeptide or other mature pancreatic hormones, it may be a novel type of local amyloid in pancreatic islets.

Isolation of two new proteins from bovine colostrum which stimulate epidermal growth factor-dependent colony formation of NRK-49F cells

Defatted bovine colostrum and decaseinated whey contain biological activity similar to that of TGF-beta in that they stimulate the anchorage-independent growth of NRK-49F cells in the presence of EGF. Two new proteins with such activity, termed BC-1 and BC-2, were isolated from decaseinated colostrum by a sequence of DEAE-Sephacel chromatography, Sephadex G-100 gel filtration in 1 M acetic acid, Sephadex G-50 re-gelfiltration in 8 M urea-1 M acetic acid and reverse-phase FPLCs. The two proteins showed distinctly different molecular weight from that of TGF-beta 1. BC-1 was a small Mr peptide of 8.5 kD. BC-2 had molecular mass of 46 kD, which yielded peptides of 46,40, and 6 kD on reduction. In contrast to TGF-beta, both proteins did not lose their biological activity on reduction. Both BC-1 and BC-2 suppress DNA synthesis in concanavalin A-stimulated thymocytes. These results suggest that BC-1 and BC-2 belong to a new class of mitogen/inhibitors, though their biological activities resemble those of TGF-beta.

Secretion of islet amyloid polypeptide in response to glucose

The content of islet amyloid polypeptide (IAPP) in isolated rat pancreatic islets was determined by a radioimmunoassay. Reverse-phase high-performance liquid chromatography analysis revealed that a main peak of IAPP immunoreactivity in the extracts from the islets corresponded to a synthetic rat IAPP. Secretion of IAPP from the cells is regulated by the extracellular glucose concentration. Thus, IAPP may be a novel regulator for glucose homeostasis and changes in the secretion perhaps relate to insular amyloid deposits and impaired glucose tolerance in type 2 diabetes mellitus.

Bovine colostric transforming growth factor-beta-like peptide that induces growth inhibition and changes in morphology of human osteogenic sarcoma cells (MG-63)

TGF-beta like peptide, termed TGF(BC-1), was partially purified from defatted and decaseinated bovine colostrum by a sequence of DEAE-Sephacel chromatography and Sephadex G-50 gel filtration in 1M acetic acid. TGF(BC-1) was distinct from well-known 25K TGF-beta in chemical properties: TGF(BC-1) was sensitive to acid ethanol extraction (Roberts et al., 1980). Its apparent molecular weight ranged from 21k to 11k by gel filtration and it was composed of low MW peptides (15k, 13k, 10k and 7.3k but not 25k) as examined by SDS-PAGE under non-reducing conditions. However, TGF(BC-1) shares some biological properties with the prototype TGF-b. TGF(BC-1) remarkably suppressed growth of osteogenic sarcoma cells (MG-63), and this was intriguingly accompanied by a striking change in morphology.

Mouse monoclonal antibodies with restricted specificity for human renal cell carcinoma and ability to modulate the tumor cell growth in vitro

Three mouse monoclonal antibodies (MAbs), KRC-1, -2 and -3(IgG1) were produced against cultured cells of human renal cell carcinoma (RCC) cell lines. All of them had restricted specificity for subset of RCC, but did not react with other tumor cell lines, tumor and normal tissues including kidney. The effect of these MAbs on the tumor cell growth in vitro was examined both in soft agar and in plate culture systems. All of them showed modulator effect on the tumor cell growth: KRC-1 showed stimulation effect and others, KRC-2 and -3, suppression one in the both systems. The specificity was observed in the modulator effects. KRC-1 detected a 135 kd glycoprotein in immunoblotting. KRC-2 detected a high molecular weight antigen (ca. 1200 kd) in gel filtration. All the antigens showed affinity for Con A lectin. Molecular properties of the antigens appeared to be different from those of previously reported RCC-associated antigens. The three MAbs seem to be useful to study mechanism of growth regulation in transformed cells.