Ben Pansky

Insulin and the gastrointestinal tract

Abstract To provide a less cumbersome and more socially accepted form of insulin treatment than subcutaneous injections, we have designed an azopolymer system to deliver insulin with an absorption enhancer to the upper colon. In pancreatectomized dogs repeated oral doses of insulin in azopolymer-coated capsules lower the diabetic hyperglycemia to near normal values. Direct visualization of capsules containing radionuclides and coated with two new batches of azopolymer demonstrated that the capsules either passed intact through the gut or were opened in the small intestine. Direct visualization and insulin delivery using the same azopolymer will be necessary to locate the site of insulin delivery, but there remains the possibility that the insulin was delivered within the small intestine. To understand the effect of large doses of insulin delivered to the upper GI tract, an insulin solution was substituted for the drinking water of normal and diabetic rats. This produced temporary decreases in blood glucose levels, showing that in rats some absorption of insulin takes place above the colon. However, these rats became hyperphagic and lost weight. On post mortem examination the gut was distended with undigested food. Insulin seemed to inhibit processing of the food by the gut, in confirmation of observations by Elliasson and coworkers in human volunteers. The inhibitory effect of insulin on the gut, coupled with the presence of insulin receptors on the mucosal side of the gut and the presence of other pancreatic peptides in the gut, suggested to us that the gut may be able to make insulin. Accordingly, we looked for and found immunocytochemical evidence for preformed insulin in crypt cells in the colon and stomach, as well as the mRNAs for both rat insulins in similar cells. Gut insulin may be involved in the response of the gastrointestinal tract to food. Caution must be exerted in the introduction of high concentrations of insulin into the gastrointestinal tract. The same may be true of other powerful natural agents for which an oral delivery system would be desirable.

Immunocytochemistry of mouse and human retina with antisera to insulin and S-100 protein

Immunocytochemistry using peroxidase antiperoxidase (PAP) techniques showed insulin-like immunoreactivity in the human retina, and in the mouse retina and optic nerve. The immunoreaction product was seen in the inner nuclear, ganglion cell, outer and inner plexiform layers of the retinas, and in glial cell bodies of the optic nerve. A similar staining pattern using antiserum to S-100 protein, a marker for glial elements, was also seen in these tissues. This demonstrates that insulin or insulin-like immunoreactivity appears to be limited to glial cells of the retina and optic nerve. Our study suggests that the presence of insulin or a similar peptide in retina and optic nerve may be important for their normal function and metabolism.

Insulin immunoreactivity in the fetal and neonatal rat retina

The ganglion cell layer of pre- and postnatal rat retina is positive for insulin immunoreactivity. At birth the inner nuclear layer also stains for insulin. By 5 days after birth the layers characteristic of the mature retina are demonstrable. At this time the outer nuclear layer and both limiting membranes show insulin reactivity. The lens is positive for insulin at all stages studied and the retinal pigment and choroid layers are positive after birth. These observations suggest that insulin may be important in differentiation and/or maturation of the retina.

Evidence for biosynthesis of preproinsulin in gut of rat

Glucagon and other pancreatic peptides are made in the gut, but there is little evidence for the formation of insulin. The demonstration of insulin receptors on the mucosa of gut epithelium suggests that there may be an autocrine or paracrine role for insulin made in the gut. Such insulin may control cell division, the secretion of other peptides from the same or neighboring cells, or motility and absorption. To search for the ability of the gut to make insulin, sections of freshly excised segments of rat gut were treated with an antiserum against porcine insulin. Intracellular immunore-activity appeared in glandular cells in the stomach and colon but not in the small intestine. Preproinsulin mRNA was detected in similar cells in the stomach and colon by in situ hybridization, using specific oligonucleotide probes. Rat preproinsulin 1 and 2 mRNAs were transcribed by reverse transcriptase to the corresponding cDNAs, which were then amplified by polymerase chain reaction, utilizing specific oligonucleotide primers. Restriction analysis confirmed the identity of rat preproinsulin 1 and 2 mRNA in the colon and rat preproinsulin 1 mRNA in the stomach. Neither was found in the small intestine. Base sequences of the cDNAs were identical to the coding regions of pancreatic rat preproinsulin 1 and 2 messages. These observations are strong evidence for the synthesis of preproinsulin in the gut of the rat.

Glucagon-like immunoreactivity in mouse and rat retina

Mouse and rat retinae were examined by the peroxidase-anti-peroxidase technique of immunocytochemistry using an antiserum against glucagon. The immunoreactivity was found in the cells of the ganglion cell layer and inner nuclear layer, including Müller cells. These observations may indicate that glucagon or a similar peptide is important in neuromodulation and/or metabolism of retinal cells.

Response of peripheral blood lymphocytes from the (nzb/nzw)f1 mouse to phytohemagglutinin.

Abstract In view of the earlier occurrence and greater prevalence of autoimmune disease in the female New Zealand black/white ( NZB NZW )F 1 hybrid mouse, we have compared the response of peripheral blood lymphocytes (PBL) from male and female F 1 mice to phytohemagglutinin-M (PHA). Between the ages of 6 and 20 weeks, the response of lymphocytes from F 1 hybrid females was significantly greater than that of males. A peak in the response of the female occurred at 12 – 14 weeks of age. The response to PHA in both sexes began decreasing at 22 weeks of age, with the rate of decrease being greater in the female. Additional experiments showed that the plasma from ( NZB NZW )F 1 females enhanced the responsiveness of PBL from ( NZB NZW )F 1 males. In contrast, male plasma suppressed responsiveness of PBL from females. The age at which female mice begin to hyperrespond to PHA correlates with the time at which others have reported loss of suppressor T-cell function in these mice. Our data suggest a difference between the immunological responsiveness of peripheral blood lymphocytes of male and female ( NZB NZW )F 1 mice.

Insulin-like immunoreactivity in human retinoblastoma Y79 cell line.

Cells from the Y79 human retinoblastoma cell line were examined by immunofluorescence immunocytochemistry using an antiserum against insulin. All the cells showed intense staining, indicating the presence of insulin-like immunoreactivity in these cells. Our observations suggest that insulin may play an important role in the metabolism of retinoblastoma cells and that it may be possible to use this cell line as an in vitro model for studies on the action of insulin in the metabolism of human retinal cells.

Human retinoblastoma Y79 cells contain both insulin-specific mRNA and insulin-binding sites

We previously reported the presence of insulin-like immunoreactivity in cells from the human retinoblastoma Y79 cell line. In the present study, in situ DNA hybridization techniques were applied, using a human insulin cDNA probe to investigate whether the insulin-like activity is due to local synthesis of insulin. Our results suggest that Y79 cells contain mRNA for the synthesis of insulin or a homologous peptide. In addition, 125I-insulin binding autoradiographic studies show that these cells also contain specific insulin-binding sites. It is suggested that insulin may play an autocrine and/or paracrine role in the maintenance and metabolism of the Y79 retinoblastoma cells.

Synthesis of Insulin or a Similar Peptide in the Pituitary Gland and in Retinal Muller Cells

Insulin or insulin-like peptides have been reported to be present in, and may be synthesized by, organisms that do not have pancreatic beta cells (LeRoith, et al., 1980, 1981, 1983; Falkner, et al., 1975; Meneses and Oritz, 1975; Duve and Thorpe, 1979; Yuri, et al., 1980)., Similar reports have appeared claiming localization and possible synthesis of insulin in the extrapancreatic tissues of vertebrates (Hendricks, et al.,1983). Proposed extrapancreatic sites of insulin synthesis in mammalian species have including the brain (Havrankova, et al., 1978; Raizada, et al., 1979; Bernstein, et al., 1980; Rosenzweig, et al.,1980; Stevenson, 1982; Raizada, et al., 1983; Lee, et al., 1984; Clarke, et al., 1986), rodent and human pituitary (Hatfield, et al., 1981; Budd, et al., 1986; Budd, et al., 1987), rodent and human retina (Das et al., 1984, 1985), human retinoblastoma cells (Pansky, et al., 1986),, yolk sac (Muglia and Locker, 1984), human placenta (Liu, et al., 1985) and mouse seminal vesicle (Stahler et al., 1986, 1987).

Anatomy of the pancreas

SummaryEarly diagnosis of pancreatic disease is difficult because of the position of the pancreas deep in the abdomen, where it is covered by hollow viscera, making it inaccessible for simple examination. In addition, the functional reserve of the gland is great, and over 50% of its acinar tissue must be destroyed before there is marked evidence of an effect on digestion. The stimulus to pancreatic secretion is very complicated and difficult to control because it is both humoral and neurogenic. Since the ampulla of Vater is used for both bile and pancreatic secretion and opens into the duodenum, there is a reservoir for reflux into the biliary system and the pancreas, as well as a potential route for transfer of infection. The relationship of the pancreas to the surrounding viscera, its rich blood and lymphatic supply, and its lack of complete fascial protective covering allow for the rapid and severe dissemination of malignant processes long before obvious symptoms are apparent.