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PubMed2005

Interleukin-4 gene transfer into rat pancreas by recombinant adenovirus.

OBJECTIVE: Adenovirus-mediated gene transfer technology may provide a novel approach in the treatment of pancreatic diseases. In the rat model of chronic pancreatitis induced by dibutyltin dichloride (DBTC), Th1 lymphocytes are known to be involved in the mediation of inflammation. We therefore investigated whether local expression of the Th2 cytokine interleukin (IL)-4 might modulate the inflammatory response. To address this question, we have established a protocol of efficient gene transfer into rat pancreas. MATERIAL AND METHODS: Recombinant adenovirus constructs carrying the Escherichia coli beta-galactosidase gene (Adbeta-gal) or the rat IL-4 gene (AdrIL-4) were injected into the left gastric artery of healthy LEW.1W rats. Expression of beta-Gal and IL-4 in pancreatic cells was analyzed by X-Gal staining and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. After optimization of the transduction protocol, effects of the IL-4 gene transfer on pancreatic inflammation and fibrosis were studied in DBTC-treated rats. RESULTS: Seven days after Adbeta-gal injection, beta-gal-positive cells were detectable in the rat pancreas. RT-PCR analysis using RNA from pancreata of AdrIL-4-treated rats indicated that IL-4 was expressed for at least 14 days after adenovirus application. Expression of the IL-4 transgene was accompanied by a transient increase of the IL-10 mRNA level in the pancreas. In DBTC-treated rats, adenovirus-mediated transfer of the IL-4 gene modified the pattern of infiltrating inflammatory cells in the pancreas. Importantly, a decrease of CD4+ helper cells was observed. CONCLUSIONS: Our data suggest that the injection of recombinant adenoviruses into the left gastric artery is a promising approach to achieving expression of therapeutic transgenes in the pancreas.

Adenoviridae↗
PubMed2000

In vitro studies of cellular and molecular developmental toxicity of adjuvants, herbicides, and fungicides commonly used in Red River Valley, Minnesota.

Recent epidemiologic studies showed increased frequency of birth defects in pesticide applicators and general population of the Red River Valley, Minnesota. These studies further indicated that this crop growing area used more chlorophenoxy herbicides and fungicides than elsewhere in Minnesota. Based on frequency of use and known biology, certain herbicides, pesticide additives, fungicides, and mycotoxins are suspect agents. To define whether these agents affect developmental endpoints in vitro, 16 selected agrochemicals were examined using the MCF-7 breast cancer cell line. In the flow cytometric assay, cell proliferation in this estrogen-responsive cell line indicates xenobiotic-mediated estrogenic effects. Cell viability, morphology, ploidy, and apoptosis were incorporated in this assay. Data showed that the adjuvants X-77 and Activate Plus induced significant cell proliferation at 0.1 and 1 microg/ml. The commercial-grade herbicides 2,4-D LV4 and 2,4-D amine induced cell proliferation at 1 and 10 microg/ml. The reagent-grade 2,4-D products failed to induce proliferation over the same concentration range, suggesting that other ingredients in the commercial products, presumably adjuvants, could be a factor in these results. The fungicides triphenyltin and mancozeb induced apoptosis at concentrations of 4.1 microg/ml (10(-5) M) and 50 microg/ml, respectively. Triphenyltin also induced aneuploidy (C2/M arrest) at 0.41 microg/ml (10(-6) M). Data provide a mechanistic step to understanding human reproductive and developmental effects in populations exposed to these agrochemicals, and initiative to focusing limited resources for future in vivo animal developmental toxicity studies.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Migration from packaging materials into foodstuffs--a need for more fundamental information.

During recent years considerable legislative attention has been focused on food packaging materials, especially plastics, and in a number of countries extensive legislation has been formulated. Such legislation often takes the form of a positive list of permitted substances accompanied either by compositional limits or migration limits in foods or stimulant liquids. In the UK this approach has not been followed owing to the general lack of fundamental information on which to base such a system. Instead, the UK has opted for a basic legislative framework supported by informal controls which rely to a large extent on close co-operation between Industry and Government. It is recognized, however, that in future years there is likely to be a move towards more extensive legislation on packaging materials in the UK, particularly as a result of the EEC's harmonization programme. It is imperative that any future legislation is placed on a sound scientific footing and affords adequate protection for the consumer. The Government of the UK is, therefore, currently sponsoring a number of studies aimed at providing this necessary basic information.

Chemical Phenomena↗
PubMedDate not supplied

Speciation of organotins in poly(vinyl chloride) products.

Extraction studies on butyl- and octyltins were conducted with three poly(vinyl chloride) (PVC) product types: clear food container, rigid pipe and flexible membrane. Three solvents, tetrahydrofuran, xylene and methylene chloride were evaluated for extraction efficiency. Methylene chloride extracted more than 97% of the total extractable organotin in two extractions and resulted in the highest recoveries of analytes from all three PVC products. Method detection limits ranged from 0.3 to 0.9 microgram alkyltin/g PVC. The mean precision of the method is 6.8% relative standard deviation. Food industry PVC product samples contained between < 0.8 and 8751 micrograms/g octyltins and < 0.3 and 4.7 micrograms/g butyltins. Butyltins (< 0.9-5985 micrograms/g) were detected in potable water pipe samples. Pipe used in industrial applications contained both butyl- (13-1501 micrograms/g) and octyltins (701-3033 micrograms/g).

Food Contamination↗
PubMed2000

Alkyltins in farmed fish and shellfish.

A study to update dibutyltin (DBT) and tributyltin (TBT) residues in farmed fish and shellfish (Mytilus edulis) was carried out 4 years after the adopting of the restricting regulation of the antifouling uses of organotins in Italy. DBT and TBT were simultaneously extracted from farmed fish and shellfish (M. edulis) and from free living specimens, used as control, purchased from retail stores or fishermen in the province of Naples (Italy), and detected using a capillary gas chromatograph equipped with a flame photometric detector (GC-FPD). Dosable amounts of DBT were found in the 10% of the farmed fish analyzed, ranging from 1 to 26 micrograms kg-1 wet wt (mean 10 micrograms kg-1) and in the 23% of the free living fish at an average level of 2 micrograms kg-1 wet wt (range 1-4 micrograms kg-1 wet wt). TBT was detected in 85% of the farmed fish, in concentrations varying from 2 to 260 micrograms kg-1 wet wt (mean 28 micrograms kg-1 wet wt) and in 46% of the free living specimens (mean 39 micrograms kg-1 wet wt; range 1-93 micrograms kg-1). All the mussel samples analyzed were polluted by both DBT and TBT. In the farmed mussels the average amounts of DBT and TBT were, respectively, 4 and 2 micrograms kg-1 wet wt; in the free living they were 4 and 5 micrograms kg-1 wet wt, respectively. The results indicate that the DBT and TBT contamination is as highly diffuse in farmed as in free living fish and mussels on sale in retail markets in Naples province even if the levels of the contamination are meanly quite low.

Animals↗
PubMed2005

Reaction of the 2'-silyl and 2'-stannyl derivatives of 6-(bromomethyl)dimethylsilyl-1',2'-unsaturated uridine under radical conditions.

The mode of cyclization (5-exo versus 6-endo) of 2-sila-5-hexen-1-yl radicals generated from 2'-tributylstannyl- and 2'-trimethylsilyl-6-(bromomethyl)dimethylsilyl-1',2'-unsaturated uridines (8 and 9) was investigated. Although the actual structure of the reaction products differ from each other reflecting the ease of elimination of the 2'-substituent, it was found that both substrates prefer the 5-exo-cyclization pathway.

Organotin Compounds↗
PubMed1983

Dimethyltin dichloride: investigations into its gastrointestinal absorption and transplacental transfer.

Dimethyltin dichloride (DMDC) is commonly used as a stabilizer in PVC pipe used for transport of potable water. Learning deficiencies have been observed postnatally in pups from DMDC-treated dams. Studies were conducted with female Sprague-Dawley rats to determine whether DMDC was absorbed by the dam and transferred across the placenta to fetal blood and brain tissue. This was accomplished in three phases: (1) a comparison of absorption of organic and inorganic tin from drinking water, (2) a comparison of prenatal and postnatal levels of tin in the pups in cross-fostering studies, and (3) a [14C]dimethyltin dichloride tracer study to determine whether organic tin passed to the pup intact. Major findings include: (1) DMDC is absorbed in the gastrointestinal tract of the dam much more rapidly than Sn2+; (2) the more rapid absorption of DMDC results in higher concentration of tin in fetal blood and brain; and (3) in fetuses that receive tin as DMDC, both tin and the methyl carbon are absorbed by the dam and transferred to the blood and brain of the fetuses.

Animals↗
PubMed1985

Testicular changes in rats after administration of organotin complex.

Intratesticular administration of di-n-butyltin (o-hydroxyacetophenone S-methyldithiocarbazate) has been shown to induce marked degenerative changes in the testes of adult rats. The possible mechanism of its action is discussed. In particular, an atrophy of seminiferous tubules with complete arrest of spermatogenesis has been noted.

Animals↗
PubMed1988

Immunologic effects of perinatal exposure of rats to dioctyltin dichloride.

Studies were conducted to determine the period of immune system development that was most sensitive to perturbation by the known immunotoxicant di-n-octyltin dichloride (DOTC). Fischer 344 rats were exposed prenatally, both pre- and postnatally, or postnatally to DOTC by oral gavage of pregnant and/or lactating females. At various ages, ranging from 3 to 16 wk of age, offspring were examined for a number of immune functions. These included body and lymphoid organ weights; lymphoproliferative responses to B- and T-cell mitogens; natural killer cell activity; and primary antibody response to sheep erythrocytes. Prenatal (10-20 of gestation), pre- and postnatal (d 11-20 of gestation and 2-11 d of age), or postnatal (2-13 d of age) oral dosing of dams with 20-50 mg/kg DOTC resulted in no consistent alteration in immune function in offspring. However, direct oral dosing of rat pups to 5-15 mg/kg DOTC, beginning at 3 d of age and then 3 times per week up to 24 d of age for a total of 10 doses, resulted in significant suppression of the lymphoproliferative response of splenocytes to a T-cell mitogen in 10-wk-old rats (i.e., 7 wk after the last exposure to DOTC). Lymphoproliferative responses returned to control levels by 12 wk of age. In comparison young adult (8 wk old) rats dosed with 10 or 20 mg/kg DOTC under an identical dosing schedule (i.e., 3 times per week for a total of 10 doses) showed no suppression in the mitogen response of splenocytes 4 wk after the last exposure to DOTC. These results suggest that direct dosing of pups during early postnatal life may be the most effective means of inducing immunosuppression with DOTC during immune system development. The results also provide evidence for the greater sensitivity of the developing immune system compared with the fully developed immune system for a known immunotoxicant.

Administration, Oral↗
PubMed2002

Immobilization of Spirulina subsalsa for removal of triphenyltin from water.

Spirulina subsalsa is immobilized with alginate, which increases the growth rate, chlorophyll content, phycocyanin content and nitrate reductase activity. Immobilized Spirulina subsalsa with alginate increases absorption of triphenyltin chloride (TPT). The phycocyanin of immobilized Spirulina subsalsa is more sensitive to TPT then free alga. The immobilization enhances the toxic effect of TPT on nitrate reductase activity of Spirulina subsalsa. Experimental results demonstrate that the immobilization of Spirulina subsalsa is feasible. Removal of TPT by immobilized Spirulina subsalsa reaches 68%. Biosorption mechanism of TPT by Spirulina subsalsa should be further studied.

Absorption↗
PubMed1979

Organotin-mediated exchange diffusion of anions in human red cells.

Organotin cations (R3Sn+) form electrically neutral ion pairs with monovalent anions. It is demonstrated that the tin derivatives induce exchange diffusion of chloride in red cells and resealed ghosts, without any detectable increase of membrane permeability to net movements of chloride ions. The obligatory anion exchange is believed to be due to the permeation of electroneural ion pairs, whereas the organic cation (R3Sn+) has an extremely low membrane permeability. Exchange fluxes of chloride increased with the lipophilicity of the substituting group (R3). At the same molar concentration of organotin, the relative potencies of the tin derivatives as anion carriers (with trimethyltin as a reference) were: methyl 1, ethyl 30, propyl = phenyl 1,00, and butyl 10,000. Tributyltin-mediated anion exchange was studied in detail. The organotin-induced anion transport increased through the sequence: F- less than Cl- less than Br- less than I- = SCN- less than OH-. Partitioning of tributyltin into red cell membranes was greater in iodide than in chloride media (partition coefficients 6.6 and 1.7 x 10(-3) cm, respectively). Bicarbonate, fluoride, nitrate, phosphate, and sulphate did not exchange with chloride in the presence of tributyltin. Chloride exchange fluxes increased linearly with tributylin concentrations up to 10(-5) M, and with chloride concentrations up to at least 0.9 M. The apparent turnover number for tributyltin-mediated chloride exchange increased from 15 to 1,350 s-1 between 0 and 38 degrees C. These figures are minimum turnover numbers, because it is not known what fraction of the organotin in the membrane exists as chloride ion pairs.

Adsorption↗
PubMed2003

Triphenyl tin benzimidazolethiol, a novel antitumor agent, induces mitochondrial-mediated apoptosis in human cervical cancer cells via suppression of HPV-18 encoded E6.

Here we report the effect of TPT-benzimidazolethiol, a novel anti-tumor agent developed by our group, on the apoptotic pathway of human cervical carcinoma cells. Treatment of HeLa cells with TPT-benzimidazolethiol arrests the cell cycle at G0/G1 phase and transcriptionally downregulates HPV-encoded E6, restoring p53 expression from E6 suppression. Increased p53 accumulation up-regulates p21/waf and ultimately induces apoptosis. The effect of TPT-benzimidazolethiol is far more potent in inducing apoptosis than cisplatin. Treatment with TPT-benzimidazolethiol in HeLa cells is accompanied by the up-regulation of Bak at the transcriptional level, resulting in the release of cytochrome c and Smac/DIABLO from mitochondria to cytosol and, subsequently, the activation of procaspase-9, -3 and PARP, suggesting that TPT-benzimidazolethiol induced-apoptosis signaling is by an intrinsic mitochondrial pathway. Taken together, we propose that TPT-benzimidazolethiol could has the potential to be developed into a new therapeutic agent for treating HPV-associated cervical neoplasia.

Antineoplastic Agents↗
PubMed1997

Induction of calcium release from isolated sarcoplasmic reticulum by triphenyltin.

A direct peripheral myopathy has been found in organotin intoxication and suggested to be a significant factor in the development of muscle weakness following exposure. In this study, by using the isolated sarcoplasmic reticulum membrane vesicles, we have shown that triphenyltin dose-dependently induced Ca2+ release from the actively and passively loaded sarcoplasmic reticulum vesicles. Triphenyltin induced Ca2+ release in ruthenium red-sensitive and insensitive ways with EC50 values of 75 and 270 microM, respectively. The Ca2+-ATPase activity and Ca2+ uptake of sarcoplasmic reticulum were also inhibited by triphenyltin. Triphenyltin exerted dual effects on the apparent [3H]ryanodine binding. Triphenyltin (0.5-10 microM) dose-dependently potentiated the [3H]ryanodine binding; however, the [3H]ryanodine binding decreased as the concentration of triphenyltin increased. The dissociation of bound [3H]ryanodine was facilitated by triphenyltin. The present study suggested that the internal Ca2+ store of skeletal muscle could be depleted by triphenyltin through the inhibition of the Ca2+ uptake and the induction of Ca2+ release by acting on the Ca2+-ATPase and Ca2+ release channel, also known as the ryanodine receptor, of sarcoplasmic reticulum, respectively. These results could partly explain the development of muscle weakness in organotin intoxication; however, their relevance to the development of peripheral myopathy requires further examination.

Animals↗
PubMed1985

DCCD-sensitive, Na+-dependent H+-influx process coupled to membrane potential formation in membrane vesicles of Halobacterium halobium.

The effects of N,N'-dicyclohexylcarbodiimide (DCCD) on light-induced H+-transport and transmembrane electric potential (delta phi) formation were studied in the membrane vesicles of Halobacterium halobium R1M1. In accordance with our previous finding of the existence of two DCCD-binding components in vesicle membrane using 14C-DCCD (Konishi & Murakami FEBS Lett. 169, 283-286 (1984)), DCCD inhibited the H+-influx process biphasically; that is, the H+-influx process which is electrically silent was initially inhibited at concentrations below 30 nmol of DCCD/mg vesicle protein, while another H+-influx process which is coupled to delta phi formation was secondarily inhibited above this concentration of DCCD. The latter H+-influx process was highly dependent on the Na+ concentration. The extents of Na+-dependent recovery of delta phi formation and H+-influx were quantitatively correlated. From these results, it was concluded that the second DCCD-sensitive H+-influx process which is coupled to delta phi formation is due to the hypothetical Na+/H+-antiporter postulated by Lanyi and MacDonald (Biochemistry 15, 4608-4614 (1976)). It was also found that Li+ can be substituted for Na+ in this system, as is the case with Na+/H+-antiporters found in other organisms.

Carrier Proteins↗
PubMed2003

Nociception in persistent pancreatitis in rats: effects of morphine and neuropeptide alterations.

BACKGROUND: Most animal models of pancreatitis are short-lived or very invasive. A noninvasive animal model of pancreatitis developed in highly inbred rats by Merkord with symptoms persisting for 3 weeks was adopted in the current study to test its validity as a model of visceral pain in commercially available rats. METHODS: The persistent pancreatitis model was established by tail vein injection of dibutyltin dichloride. Animals were given 10% alcohol in their drinking water to enhance the pancreatitis attack. Blood serum pancreatic enzymes and nociceptive state were monitored for 3 weeks after dibutyltin dichloride or vehicle. Behavioral testing included reflexive withdrawal to mechanical and thermal stimulation of the abdominal area. The effect of morphine on nociceptive behaviors was tested. Histologic analysis of the pancreas and immunohistochemical analysis of substance P and calcitonin gene-related peptide in the spinal cord are included in the study. RESULTS: Compared with naïve and vehicle-only injected control groups, rats receiving dibutyltin dichloride demonstrated an increase in withdrawal events after von Frey stimulation and decreased withdrawal latency after thermal stimulation, signaling a sensitized nociceptive state through 7 days. These pain-related measures were abrogated by morphine. Blood serum concentrations of amylase and lipase as well as tissue inflammatory changes and substance P were also significantly elevated during this same time period. CONCLUSIONS: These results indicate that animals with the dibutyltin dichloride-induced experimental pancreatitis expressed serum, histologic, and behavioral characteristics similar in duration to those present during acute attacks experienced by patients with chronic pancreatitis. These findings and responsivity to morphine suggest the utility of this model developed in a commercially available strain of rats for study of persistent visceral pain.

Amylases↗