Loss of murine Paneth cell function alters the immature intestinal microbiome and mimics changes seen in neonatal necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) remains the leading cause of gastrointestinal morbidity and mortality in premature infants. Human and animal studies suggest a role for Paneth cells in NEC pathogenesis. Paneth cells play critical roles in host-microbial interactions and epithelial homeostasis. The ramifications of eliminating Paneth cell function on the immature host-microbial axis remains incomplete. Paneth cell function was depleted in the immature murine intestine using chemical and genetic models, which resulted in intestinal injury consistent with NEC. Paneth cell depletion was confirmed using histology, electron microscopy, flow cytometry, and real time RT-PCR. Cecal samples were analyzed at various time points to determine the effects of Paneth cell depletion with and without Klebsiella gavage on the microbiome. Deficient Paneth cell function induced significant compositional changes in the cecal microbiome with a significant increase in Enterobacteriacae species. Further, the bloom of Enterobacteriaceae species that occurs is phenotypically similar to what is seen in human NEC. This further strengthens our understanding of the importance of Paneth cells to intestinal homeostasis in the immature intestine.

The survival identification of pancreatic islets of Langerhans. In vitro and in vivo effects of two dithizone preparations on staining of rat and human islets of Langerhans-preliminary study (Part I).

Dithizone (DTZ) which selectively stains islets of Langerhans in vitro has a diagnostic potential in the in vivo identification of viable transplanted pancreatic islets. In the present study, we compared the use of DTZ, and a synthetic iodo-derivative of DTZ (I-DTZ) as a potential radioactive marker for identification of viable transplanted pancreatic islet cells. Fresh islets isolated from Lewis rat donors were transplanted beneath the kidney capsule into each diabetic syngeneic (Lewis) recipient rat. DTZ(I-DTZ) solution was injected intravenously (i.v.) at a dose 10 mg/kg body weight (b.w.) for macro and microscopic identification of surviving transplanted islets. The recipients were nephrectomized to confirm that the normoglycemic state was maintained by the islet grafts. In addition, we administered i.v. at the same time concentrations of DTZ (I-DTZ) to test for toxicity. The results show that following i.v. or intraductal (i.d.) injection of low concentrations does not damage pancreatic islet function as determined by insulin secretion or glucose levels. Angiogenesis and microvascularization were observed for 10-12 days after transplantation, and the histologic and biochemical studies showed no pathological changes in injected rats in organ examined. The human pancreatic islets harvested from multiorgan donors stain red ex vivo in the same way as DTZ or I-DTZ administered i.v. in rats. The results indicate that DTZ has a diagnostic potential in monitoring the survival of transplanted pancreatic islets and possibly in the early diagnosis by radioisotopic detection of pancreatic endocrine diseases.

Staining and in vitro toxicity of dithizone with canine, porcine, and bovine islets.

Dithizone (DTZ) is a recognized diabetogenic agent in vivo, and a supravital stain commonly used for identification of islets to be used for transplantation. In the present studies, we compared DTZ staining of freshly isolated and cultured canine, bovine, and porcine islets, and the effect of DTZ on the function and viability of islets. Incubation with DTZ resulted in staining of canine and porcine islets, but no discernible staining with bovine islets. Insulin content of porcine, canine, and bovine islet was 2.0 +/- 0.2, 2.2 +/- 0.3, and 1.9 +/- 0.2 mU/EIN, indicating a lack of correspondence of DTZ staining and insulin content. Seven days of culture with canine islets resulted in > or = 50% reduction of DTZ stained cells. Exposure to DTZ at 50 micrograms/mL resulted in a maximal number of stained cells in preparations of purified islets (80-85%; counted after dispersion), a lower percentage of cells stained faintly at 20 micrograms/mL (50-55%), with no discernible staining at 10 micrograms/mL. Prolonged exposure of islets (4-48 h) to 20 micrograms/mL DTZ led to reduced insulin secretion and islet cell death. Incubation of canine or porcine islets with 100 micrograms/mL of DTZ for 0.5 h resulted in a dramatic loss of viability and diminished insulin secretory function, which was not reversed with continued culture. The concentration dependence of toxic effects paralleled the concentration dependence of cellular staining. The minimally effective staining concentration (20 micrograms/mL) also resulted in a loss of viability. An additional assessment of DTZ toxicity was made using the RIN-38 beta-cell line, which shows no discernible staining with DTZ.(ABSTRACT TRUNCATED AT 250 WORDS)

Deleterious effect of dithizone-DMSO staining on insulin secretion in rat and human pancreatic islets.

Dithizone (DTZ) is a selective stain for pancreatic islets which facilitates their identification, being of special interest in human islet isolation assessment. Nevertheless, there are few studies concerning its potential toxic effects on islet function. In our study, we have evaluated the effects of DTZ (dissolved in dimethyl sulfoxide [DMSO] 1% w/v) at three different concentrations (2, 10, and 100 micrograms/ml) on insulin response to glucose in human and rat islets. Likewise, we studied the effect of incubation time, in the presence of DTZ at the above-mentioned concentrations, on insulin release. Only when DTZ was employed at low concentrations and for a short period of incubation (10 min) was there no impairment of pancreatic islet function. Moreover, even at this low concentration, DTZ became deleterious for islet function when the incubation period with the dye was prolonged for 30 min. Culture (24 h) of previously stained islets produced a partial recovery of insulin response. In conclusion, our findings indicate (a) DTZ should not be employed to collect islets for functional studies because of its deleterious effect on beta-cell function, (b) DTZ's deleterious effects on beta-cell function should be considered if this dye is used to purify islets by fluorescence-activated cell sorting for transplantation.

[Features of lipid peroxidation in the vitreous body and retina during intravitreal hemorrhaging in dithiosone-induced diabetes]. / Osobennosti perekisnogo okisleniia lipidov steklovidnogo tela i setchatki pri intravitreal'nom krovoizliianii na fone ditizonovogo diabeta.

It has been stated that in experimental dithiazone-induced diabetes lipid peroxidation is intensified in vitreous body and retina of the rabbits' eyes. The increase of LP in vitreous body and retina during intravitreal hemorrhage due to experimental diabetes was controlled by antioxidants.

[Mechanism of phasic fluctuations of glycemia after administration of diabetogenic substances]. / K mekhanizmu faznykh kolevanii glikemii pri vvedenii diabetogennykh veshchestv.

Dithizone induces similar glycemic changes in rabbits, golden hamsters and mice (triphasic fluctuations resulting in diabetes). In rabbits who received 8-(p-toluenesulfonylamino)-quinoline, 8-(benzenesulfonylamino)-quinoline or alloxan, the glycemic reaction is similar to that observed after a dithizone injection. A degree of glycemic reaction to chromophiric chelants injected to animals, depends on their accumulation in the lysosome-segregation apparatus, of insulin producing cells (acidotropic action).

[Damaging action of dithizone on insulin-releasing cells]. / Povrezhdaiushchee deistvie ditizona na insulinvyrabatyvaiushchie kletki.

Alterative action of dithizone was investigated in the experiments on various species of animals (fish, frogs, pigeons, mice, guinea pigs, golden hamsters, rats, rabbits, cats and dogs). The data received support the previously advanced suggestion that unsaturated (electrophilic) zinc complex formation is the basic mechanism of the alterative chelant's action.