Oxidative response to accumulation of trace metals in tissue of two bivalves, the Asian green mussel Perna viridis and the blood cockle Tegillarca granosa, living in Pattani Bay, Thailand

OBJECTIVE

Using bivalves to indicate aquatic pollutants was favorable for discerning the negative effects of high levels of metal accumulation in tissue. We investigated the correlation between trace metal accumulation and the tissue oxidative response of two bivalves.

METHODS

The Asian green mussel Perna viridis and the blood cockle Tegillarca granosa were sampled along with seawater and sediments from three locations around Pattani Bay, Thailand. Accumulation of nine trace metals (cadmium, cobalt, copper, chromium, nickel, manganese, iron, zinc, and lead) in seawater, sediments, and tissue and the oxidative tissue response were evaluated. Metal bioaccumulation factor, biota-sediment accumulation factor, and histopathology were also indicated.

RESULT

The present study found that P. viridis and T. granosa were macroconcentrators and bioaccumulative of cadmium, and their tissue accumulation of cadmium was strongly related to lipid peroxidation activation. Perna viridis exhibited a higher oxidative response than T. granosa, as indicated by malondialdehyde, catalase, and reduced glutathione levels.

CONCLUSION

The present study indicated that P. viridis and T. granosa were macroconcentrators and bioaccumulative of cadmium, and their tissue accumulation of cadmium was strongly related to lipid peroxidation activation. Research has shown discernible negative effects of a high level of metal accumulation in tissue, and deformed and damaged tissues were present in the gills, digestive glands, intestines, and feet of P. viridis and T. granosa.

Human Health Risk Assessment of Heavy Metal Concentration in Seafood Collected from Pattani Bay, Thailand

A significant impact of marine pollution is the contamination of seafood which has raised concerns due to its potential human health risks. This current study investigated seasonal bioaccumulation of 9 heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in 14 commercially important seafood species, including 4 fish, 5 molluscs, and 5 crustacean species. Samples were collected from Pattani Bay, Pattani province, Thailand, during the dry (July 2020) and wet (February 2021) seasons. The edible samples were analyzed for heavy metal concentrations using a flame atomic absorption spectrophotometer. The bioaccumulation trend of heavy metals decreased in the sequence of molluscs > crustaceans > fish. The possible human health risks associated with heavy metal-contaminated seafood consumption were assessed. The parameters investigated for non-carcinogenic and carcinogenic were target hazard quotient (THQ), total hazard index (HI), and target cancer risk (TR). The average ranges of THQs (7.79 × 10−8−8.97 × 10−3), HIs (4.30 × 10−5−1.55 × 10−2), and TRs (2.70 × 10−9−1.34 × 10−5) were observed in the studied seafood species. The results revealed no non-carcinogenic and carcinogenic health risks from consuming these 14 kinds of seafood.

First report on clinical aspects, blood profiles, bacterial isolation, antimicrobial susceptibility, and histopathology in canine pyometra in Thailand

Background and Aim:

Canine pyometra, either the closed (closed pyometra [CP]) or open (open pyometra [OP]) cervix type, is a frequent uterine disease in intact old age bitches. Therefore, early diagnosis and appropriate medical and surgical treatments are crucial to avoid the life-threatening condition in these bitches. This study aimed to investigate clinical alterations, blood parameters, causative bacteria, antimicrobial susceptibility, and uterine histopathology obtained during aseptic surgical treatment on bitches with pyometra.

Materials and Methods:

Sixty bitches of various breeds and ages with presumptive pyometra diagnoses were included in the study. The diagnoses were based on history, clinical examination, blood parameters, radiography, and ultrasonography. All pyometra bitches were ovariohysterectomized as an emergency surgical treatment. In addition, uterine content and tissues were submitted for bacterial isolation, antimicrobial susceptibility, and uterine histopathological analysis.

Results:

Except for abdominal CP distention, no specific clinical signs were linked to the pyometra type. The mean values of total white blood cell count (WBC) and plasma protein were predominantly raised in pyometra bitches regarding hematological parameters. Leukocytosis was found in both types; however, the WBC in CP was markedly higher than in OP. The mean value of blood urea nitrogen increased in the CP group. Klebsiella pneumoniae and Escherichia coli were the most frequent causative bacteria isolated in CP and OP, respectively. All isolated bacteria were 100% susceptible to imipenem, meropenem, and carbapenem. Marbofloxacin was the second most effective drug against isolated bacteria from both groups. Uncomplicated cystic endometrial hyperplasia (CEH) was not presented in the CP group. CEH and chronic endometritis (type IV), the most severe uterine histopathological changes, were discovered in the CP and OP.

Conclusion:

The CP and OP groups presented leukocytosis, increased plasma protein, and CEH and chronic endometritis. Depression, abdominal distention, and enlarged uterine size were the major characteristics of the CP group. Furthermore, abdominal distension is presented in other abnormalities in clinical practices, providing a differential diagnosis. Drugs in the carbapenem group were the most effective against isolated bacteria; however, they are not routinely used due to bacterial resistance concerns. Thus, marbofloxacin was recommended as an alternative medical treatment because it is convenient to manage by both oral and injection routes.

Evaluation of Aflatoxin Concentrations and Occurrence of Potentially Toxigenic Fungi in Imported Chia Seeds Consumed in Thailand

ABSTRACT

This study was conducted to investigate possible contamination by aflatoxins (AFs) and aflatoxigenic fungi in imported chia seeds consumed in Thailand. A survey was performed on 100 samples of imported chia seeds collected from supermarkets and health food stores in Bangkok from May 2017 to February 2018. Ten mold species belonging to Aspergillus and Penicillium were isolated, and Aspergillus flavus was the most prevalent aflatoxigenic fungi. Chia seed samples were cleaned with an immunoaffinity column and analyzed for AFs by high-performance liquid chromatography with fluorescence detection using precolumn derivatization. AFs were detected in 40% of total samples at concentrations of 0.4 to 10.99 ng/g. Among the positive samples, three were contaminated with total AFs at concentrations higher than the European Union regulatory limit (4 ng/g). The most commonly found AF found in chia seeds was AFB1.

HIGHLIGHTS

Pharmacokinetics of tolfenamic acid in Hawksbill turtles (Eretmochelys imbricata) after single intravenous and intramuscular administration

To the best of our knowledge, limited pharmacokinetic information to establish suitable therapeutic plans is available for Hawksbill turtles. Therefore, the present study aimed to assess the pharmacokinetic features of tolfenamic acid (TA) in Hawksbill turtles, Eretmochelys imbricata, after single intravenous (i.v.) and intramuscular (i.m.) administration at dosage 4 mg/kg body weight (b.w.). The study (parallel design) used 10 Hawksbill turtles randomly divided into equal groups. Blood samples were collected at assigned times up to 144 hr. The concentrations of TA in plasma were quantified by a validated liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). The concentration of TA in the experimental turtles with respect to time was pharmacokinetically analyzed using a noncompartment model. The C_max values of TA were 89.33 ± 6.99 µg/ml following i.m. administration. The elimination half-life values were 38.92 ± 6.31 hr and 41.09 ± 9.32 hr after i.v. and i.m. administration, respectively. The absolute i.m. bioavailability was 94.46%, and the average binding percentage of TA to plasma protein was 31.39%. TA demonstrated a long half-life and high bioavailability following i.m. administration. Therefore, the i.m. administration is recommended for use in clinical practice because it is both easier to perform and provides similar plasma concentrations to the i.v. administration. However, further studies are needed to determine the clinical efficacy of TA for treatment of inflammatory disease after single and multiple dosages.

Occurrence of Multiple Mycotoxins in Various Types of Rice and Barley Samples in Thailand

HIGHLIGHTS

Contamination with multiple mycotoxins was found in rice and barley. BEA, DAS, ZEA, and aflatoxins were the mycotoxins most frequently found in samples. The assessed mycotoxin exposure does not represent a health risk for consumers.

Toxicokinetic profile of fusarenon-X and its metabolite nivalenol in the goat (Capra hircus)

The main aim of this research was to evaluate the toxicokinetic characteristics of fusarenon-X (FX) and its metabolite, nivalenol (NIV), in goats. The amounts of FX and NIV in post-mitochondrial (S-9), microsomal and cytosolic fractions of diverse tissues of the goat were also investigated. FX was intravenously (iv) or orally (po) administered to goats at dosages of 0.25 and 1 mg/kg bw, respectively. The concentrations of FX and NIV in plasma, feces and urine were quantified by liquid chromatography tandem-mass spectrometry (LC-ESI-MS/MS). The concentrations of FX in plasma were quantified up to 8 h with both routes of administration. A large amount of NIV (metabolite) was quantifiable in plasma, urine and feces after both administrations. The C_max value of FX was 413.39 ± 206.84 ng/ml after po administration. The elimination half-life values were 1.64 ± 0.32 h and 4.69 ± 1.25 h after iv and po administration, respectively. In vitro experiments showed that the conversion FX-to-NIV mainly occurs in the liver microsomal fraction. This is the first study that evaluates the fate and metabolism of FX in ruminant species.

Monitoring and health risk of mycotoxins in imported wines and beers consumed in Thailand

The presence of mycotoxins has been reported in a wide range of agricultural commodities including wine and beer. Due to the widespread consumption of these beverages, risk assessment of contamination by toxins is required for consumer health. In the present study, multi-residue analysis for the determination of mycotoxins was undertaken to survey the incidence of mycotoxins in imported wines and beers being commercialised in Thailand, and to assess the consumer health risk. Samples of red wines (100) and beers (100) were collected randomly from supermarkets and retail shops in Bangkok, Thailand and were extracted using the dispersive liquid-liquid micro-extraction procedure. The quantitation and confirmation of 19 mycotoxins were performed using liquid chromatography tandem-mass spectrometry with an electro-spray ionisation interface in the multiple-reaction monitoring mode. The results demonstrated that the wine and beer samples were contaminated with mycotoxins at 35 and 13%, respectively. The most prominent mycotoxins found in wines were Alternaria toxins, ochratoxin A, and fumonisins, whereas zearalenone and deoxynivalenol were the most prevalent mycotoxins found in contaminated beers. However, ochratoxin A levels were far below the maximum limits established by the European Union. As indicated by the risk assessment, mycotoxin exposure via imported wines and beers were at safe levels in the Bangkok urban area.

Occurrence and Health Risk of Patulin and Pyrethroids in Fruit Juices Consumed in Bangkok, Thailand

The mycotoxin patulin (PAT) is well known as a natural contaminant of apple- and other fruit-based products. Pesticides are a group of chemicals abundantly used in agriculture to maximize productivity by protecting crops from pests and weeds. Because of their harmful health effects, PAT and pesticides are strictly monitored. The current study was undertaken to investigate the significance of PAT and pyrethroid insecticide contamination in a variety of fruit juices in Bangkok. To do this, a total of 200 fruit juice samples, consisting of 40 samples each of apple, apricot, peach, pineapple, and grape juice, were collected from supermarkets in Bangkok, Thailand. PAT contamination in a variety of fruit juices was detected using validated liquid chromatography-tandem mass spectrometry, and pyrethroid insecticides (cypermethrin, cyfluthrin, and flumethrin) were analyzed using a gas chromatography equipped with micro-electron capture detector. The survey found that PAT concentrations were lower than the maximum residue limit established by European Union. The results of the present study suggest that the risk of exposure to harmful levels of PAT, cypermethrin, cyfluthrin, and flumethrin in fruit juices is very low in urban areas of Thailand.

Potential human health risk from consumption of metallic elements-contaminated benthic mollusks from Don Hoi Lot sandbar, Thailand

Environmental pollutants have raised more concerns for human health risk, especially via consumption of contaminated food. Terrestrial as well as aquatic animals are capable of bioaccumulation a variety of toxic substances including metallic elements. With increasing anthropogenic activities along the coastal areas, living organisms have more chances to be exposed to released contaminants. In this study, seven metallic elements (Cd, Cu, Fe, Mn, Ni, Pb and Zn) were determined in sediments and water from Don Hoi Lot sandbar, Samutsongkharm province, Thailand. Potential human health risks via the consumption of two benthic bivalves Solen corneus (Larmarck, 1818) and Meretrix meretrix (Linnaeus, 1758) were also estimated using the target hazard quotients (THQs). The variations of metallic element concentrations were apparent between wet and dry season. Fe was the predominate metallic element in the sediment and the remaining were Mn>Pb>Zn>Ni>Cu>Cd. Whereas metallic element concentrations in water were Pb>Ni>Fe>Zn>Cu>Mn>Cd. PCA analysis confirmed that the contaminations of these metallic elements were from Mae Klong river surface water. Most Pb THQ values in both S. corneus and M. meretrix were >1 indicating that human health risk is of concern. However, the sum of THQs of an individual metallic element should also be considered since multiple metallic elements exposure is so common.

Inhibitory Effects of Thai Essential Oils on Potentially Aflatoxigenic Aspergillus parasiticus and Aspergillus flavus

　The antiaflatoxigenic and antifungal activities of essential oils (EOs) of finger root (Boesenbergia rotunda (L.) Mansf.), pine (Pinus pinaster), rosewood (Aniba rosaedora), Siam benzoin (Styrax tonkinensis), Thai moringa (Moringa oleifera), and ylang ylang (Cananga odorata) were tested for Aspergillus parasiticus and Aspergillus flavus in potato dextrose broth. Aflatoxin B₁ (AFB₁) was extracted from culture using a QuEChERS-based extraction procedure and analyzed with high performance liquid chromatography (HPLC) coupled to a fluorescence detector. EO of pine showed the greatest inhibition of growth and AFB₁ production of A. parasiticus, followed by EOs of rosewood, finger root, Siam benzoin, and ylang ylang. EO of finger root gave the best inhibitory effects on A. flavus, followed by EOs of rosewood, pine, ylang ylang, and Siam benzoin. EO of Thai moringa did not show any significant inhibition of aflatoxigenic fungi. The antiaflatoxigenic activities of EOs correlated with their antifungal activities in the dosedependent manner. Comparison of the application of the five selected EOs in peanut pods by direct and vapor exposure indicated that the AFB₁ production inhibitory effects of the five EOs by direct exposure were faster and more effective than by vapor exposure. EO of finger root showed the best inhibition of AFB₁ production of A. flavus in peanut pods by direct exposure, followed by EOs of pine, rosewood, ylang ylang, and Siam benzoin.

Using Nassarius stolatus as a potential heavy metal biomonitor

Nassarius stolatus was evaluated as the potential heavy metal (Cd, Fe, Mn, Ni and Pb) accumulator in Don Hoi Lot sandbar, Samut Songkhram province, Thailand. This selected species belongs to the Gastropoda, which is widely distributed in the coastal areas from the upper Gulf through the southern part of Thailand. From our findings, the heavy metal accumulations in N. stolatus tissues were Fe > Pb > Mn > Ni > Cd. The retrieved bioaccumulation factor (BAF) indicated that N. Stolatus has high potential to be a biomonitor for the contaminations of Fe and Mn in water and Cd, Ni and Pb in sediment.

Disposition of a long-acting oxytetracycline formulation in Thai swamp buffaloes (Bubalus bubalis)

The present study aimed to characterize the pharmacokinetic profile of oxytetracycline long-acting formulation (OTC-LA) in Thai swamp buffaloes, Bubalus bubalis, following single intramuscular administration at two dosages of 20 and 30 mg/kg body weight (b.w.). Blood samples were collected at assigned times up to 504 h. The plasma concentrations of OTC were measured by high-performance liquid chromatography (HPLC). The concentrations of OTC in the plasma were determined up to 264 h and 432 h after i.m. administration at doses of 20 and 30 mg/kg b.w., respectively. The C_max values of OTC were 12.11 ± 1.87 μg/mL and 12.27 ± 1.92 μg/mL at doses of 20 and 30 mg/kg, respectively. The AUC_last values increased in a dose-dependent fashion. The half-life values were 52.00 ± 14.26 h and 66.80 ± 10.91 h at doses of 20 and 30 mg/kg b.w, respectively. Based on the pharmacokinetic data and PK-PD index (T > MIC), i.m. administration of OTC at a dose of 30 mg/kg b.w once per week might be appropriate for the treatment of susceptible bacterial infection in Thai swamp buffaloes.

Survey of Deoxynivalenol and Aflatoxin B1 in Instant Noodles and Bread Consumed in Thailand by Using Liquid Chromatography-Tandem Mass Spectrometry

One hundred wheat product samples (50 instant noodle samples and 50 bread samples) were collected from supermarkets in Bangkok, Thailand. Deoxynivalenol (DON) and aflatoxin B1 (AFB1) contamination in these products was analyzed using a validated liquid chromatography-tandem mass spectrometry method. The limit of quantification values of DON and AFB1 in the instant noodles and bread were 2 and 1 ng g(-1), respectively. The survey found that DON was quantifiable in 40% of collected samples, in 2% of noodles (0.089 μg g(-1)), and in 78% of breads (0.004 to 0.331 μg g(-1)). AFB1 was below the limit of quantification of the method in all of the tested samples. The results suggest that the risk of DON exposure via noodles and breads is very low in urban areas of Thailand. No risk can be attributable to AFB1 exposure in the same food matrices, but further studies with a larger sample size are needed to confirm these data.

Health risk associated with the consumption of duck egg containing endosulfan residues

Eight duck farms and a local market in Suphanburi province, Thailand adjacent to paddy fields were selected for this study. The concentrations of endosulfan isomers (α- and β-endosulfan) and endosulfan sulfate in environmental matrices (water, soil, feed) and duck eggs were determined. Human health risk via the contaminated egg consumption was also evaluated. Analysis of environmental matrices found both endosulfan isomers (α- and β-endosulfan) and endosulfan sulfate in most samples. Endosulfan sulfate was predominantly found in all matrices followed by β- and α-endosulfan, respectively. The total endosulfan concentrations were in the following order: feed > soil > water. However, the levels of endosulfan detected were lower than the regulatory maximum residue limit of endosulfan, except in water (>0.200 ng mL(-1)). Endosulfan sulfate in duck egg samples was also predominantly detected in both yolk and albumin. The average total endosulfan residues (∑endosulfan) in yolk (6.73 ng g(-1)) were higher than in albumin (4.78 ng g(-1)). According to principle component analysis, we found that paddy soil surrounding the duck farms is the suspected source of endosulfan contamination in husbandry water which subsequently contaminates duck eggs. The estimated daily intakes (EDIs) of these endosulfan-contaminated eggs were well below the acceptable daily intake (ADI) for endosulfan (6 μg kg(-1) day(-1)). However, the consumption of this contaminated duck eggs should be of concerns in regard to chronic exposure. Therefore, the better environmental managements to reduce endosulfan residues can play a crucial role for decreasing human health risk.

Dispositions and tissue residue of zearalenone and its metabolites α-zearalenol and β-zearalenol in broilers

Zearalenone (ZEA) is a secondary fungal metabolite produced mainly by a Fusarium graminearum. To clarify the toxicokinetics, and residues of ZEA and its major metabolites α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) in chickens, ZEA was then administered intravenously (iv) or orally (po) to broiler chickens at a dosage of 1.2 mg/kg body weight. The concentrations of ZEA, α-ZOL and β-ZOL in the plasma and various tissues were quantified using LC–MS/MS. The plasma concentrations of ZEA were measurable up to 2 h after iv and po administration, and the concentrations of α-ZOL and β-ZOL were detected up to 4 h after both types of administration. A two-compartment model was developed to describe the toxicokinetic of ZEA in broilers. The values of t_1/2β and V_d were 1.36 ± 0.29 h and 6.40 ± 0.89 l/kg, respectively. The absolute oral bioavailability was 29.66 ± 5.6%. ZEA, α-ZOL and β-ZOL were measurable in the vital organs after po administration. These results suggest that ZEA is absorbed from the gastrointestinal tract and it has ability to penetrate into the various tissues of broiler chickens.

Fate of fusarenon-X in broilers and ducks

In order to investigate the comparative fates and dispositions of fusarenon-X (FX) in broilers and ducks, FX was administered i.v. or orally (p.o.) to broilers and ducks. The FX and its metabolite (nivalenol, NIV) were determined in plasma and excreta using gas chromatography-mass spectrometry. The plasma concentrations of FX were determined up to 180 and 120 min in broilers and ducks, respectively, after i.v. and p.o. administration. The NIV was eliminated more slowly than its parent compound. The FX disposition fit an open 2-compartment pharmacokinetic model in broilers and ducks. The elimination half-life (t(1/2beta)) of FX was longer in ducks than in broilers. The elimination rate constant (kel) was higher in broilers than in ducks, whereas the oral bioavailability of FX was higher in ducks than in broilers. The gas chromatography-mass spectrometry profile in plasma showed that a large proportion of FX was recovered as NIV after administration of FX in both broilers and ducks. In vitro incubation of liver microsomal and cytosolic fractions with FX demonstrated that the liver and kidney are capable of the FX-to-NIV conversion. Thus, this study demonstrated that FX is absorbed more efficiently in ducks than in broilers, whereas it is eliminated more slowly in ducks than in broiler chickens. Consequently, the toxicity would have more serious consequences in ducks rather than broilers.

Distribution and residue depletion of oxytetracycline in giant freshwater prawn (Macrobrachium rosenbergii)

Distribution and residue depletion patterns of oxytetracycline were examined in giant freshwater prawns, Macrobrachium rosenbergii, after medicated-feed treatment at the feeding level of 4 g/kg of feed for 5 consecutive days. The concentration of oxytetracycline in prawn muscle tissues was measured using high-performance liquid chromatography equipped with a fluorescence detector. The limit of detection was 0.1 microg/g. In the medicated-feed-treated group, oxytetracycline was detectable 8 days posttreatment at the feeding level of 4 g/kg of feed for 5 consecutive days. The depletion half-life and mean residence time of oxytetracycline were 30.96 and 100.3 h, respectively. The dose of 4 g/kg of feed for 5 consecutive days can be recommended for therapeutic dosage regimen in giant freshwater prawn aquaculture. The minimal withdrawal period of M. rosenbergii muscle tissue should be 8 days postcessation of medicated feed.

Time- and tissue-dependent polychlorinated biphenyl residues in hairless mice after exposure to polychlorinated biphenyl-contaminated soil

Four groups of 16 age-matched female Crl:SKH1-hrBR hairless mice were exposed to either control soil or polychlorinated biphenyl (PCB)-contaminated soil (retrieved from an electrical waste landfill in Southern Illinois) for 11 weeks. The mice were exposed in a study to determine interactions between environmental PCBs and ultraviolet radiation (UVR), but the UVR group did not differ and provided a replicate for the residue study. Ear biopsies were performed immediately after the termination of soil exposure. The mice were maintained in regular bedding for 37 weeks thereafter. The ear-skin, trunk-skin, fat-pad, and liver samples were collected and weighed at the end of the study (week 48) and analyzed for PCB residues. A total of 141 PCB congeners were target analytes. There were significant differences in body weights and food consumption from week 2 to 28. The liver weights of mice treated with PCB only were significantly greater than those of UVR-treated mice. The fat-pad weight did not differ among treated groups. PCB residues in the ear biopsies specimens of mice exposed to contaminated soil were 342.3 and 317.2 ppm in the PCB- and PCB + UVR-treated groups, respectively, and contained both persistent and episodic congeners. After 37 weeks of isolation from soil, the ear PCB residues decreased to 21.5 ppm (PCB group) and 14.5 ppm (PCB + UVR group), and only persistent congeners contributed to the total PCB residues. The accumulation of PCB residues was highest in the fat pad (fat pad > ear skin > trunk skin > liver) in both PCB +/- UVR groups at the end of the study. However, the percentage of individual congeners contributing to total PCBs in these different tissues did not differ.

PCB profiles in mouse skin biopsies and fat from an environmental mixture

Fat, ear skin and trunk skin were collected from mice exposed to PCB-contaminated soil for PCB specific congener analysis. The soil had been retrieved from a Superfund site prior to remediation. Mice were exposed to either contaminated soil or control soil for 4 weeks. Skin samples were collected immediately after the 4-week exposure and again after 4-week recovery. Out of 141 PCB congeners measured, only 91 peaks representing 103 congeners were above quantification limits. Relative liver weights in PCB-exposed mice doubled indicating significant enzyme induction. Consistent with this observation, total PCB residues declined about 80% during the 4-week recovery. The PCB residue profiles in the ear skin (208mg/kg total) and trunk skin (129mg/kg) after 4-week exposure were identical and similar to those in body fat (370mg/kg) and in the contaminated soil. The results confirmed that both skin tissues are important reservoirs and can serve as useful biopsy media.

Exposure to soil contaminated with an environmental PCB/PCDD/PCDF mixture modulates ultraviolet radiation-induced non-melanoma skin carcinogenesis in the Crl:SKH1-hrBR hairless mouse

Chlorinated aromatic contaminants are active in carcinogenic processes within the skin and may have the potential to modulate ultraviolet radiation (UV)-induced skin carcinogenesis. Exposure to a complex environmental PCB/PCDD/PCDF mixture (polychlorinated biphenyls/polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans) during the irradiation phase of photocarcinogenesis was associated with significant (P < or = 0.001) reductions in papilloma incidence and squamous cell carcinoma multiplicity at irradiated skin sites. This protective effect was associated with significantly (P < 0.0001) reduced chronic epidermal thickening in UV and contaminant-exposed mice compared with mice exposed to UV only. Contaminant exposure was also associated with increased UV absorbance of skin methanol extracts implying a sunscreen-like effect.

Inflammatory response to intramuscular implantation of polyacrylonitrile ultrafiltration probes in sheep

Polyacrylonitrile is used in the manufacture of dialysis membranes. These membranes are fundamental to the functioning of implantable probes for microdialysis and ultrafiltration sampling of tissue fluids. Although in vivo experimentation using polyacrylonitrile has been reported to cause little inflammatory response when implanted subcutaneously, such information is not available for intramuscular implantation in sheep. The procaine and benzathine salts of penicillin are formulated for intramuscular injection. These salts of penicillin or the formulation excipients may cause inflammatory reactions. Use of polyacrylonitrile probes to draw samples from sites at which these formulations have been injected may be compromised by inflammation or direct interaction between formulation excipients and the dialysis membrane. The aim of this project was to describe tissue responses to intramuscular implantation of polyacrylonitrile in the presence and absence of either procaine or procaine plus benzathine salts of penicillin G. Each of 20 normal sheep was implanted with two ultrafiltration probes, one at the site of an injection of procaine or benzathine plus procaine penicillin G. Similar injections were also made at remote intramuscular sites. After 8, 9, and 11 days of the experiment, sheep were killed and the injection and implantation site muscle were excised and prepared for histopathological examination. The implantation of the probe alone caused greater inflammatory response than the injection of procaine or procaine plus benzathine penicillin G at remote intramuscular sites. The histopathological lesions were greatest where the implantation site was coupled with the injection of either formulation of penicillin G. Polyacrylonitrile may not be a suitable dialysis membrane material for intramuscular implantation in sheep.