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Several experimental models have been developed to study respiratory tract carcinogenesis. The most widely applied in vivo model uses Syrian golden hamsters which receive intratracheal instillations of a suspension of benzo[a]pyrene... more
Several experimental models have been developed to study respiratory tract carcinogenesis. The most widely applied in vivo model uses Syrian golden hamsters which receive intratracheal instillations of a suspension of benzo[a]pyrene (B[a]P) particles attached to ferric-oxide (Fe2O3) particles in saline; it was first described by Saffiotti et al. [1]. This model has several benefits compared with other experimental models; however, the large number of variables affecting the tumour response is a clear disadvantage because the tumour response is difficult to control. In this review, we describe a systematic analysis of various variables that may influence the tumour response of the respiratory tract with the aim to further standardize the method and increase, through that, its suitability and predictability. The most important variables influencing the tumour response, as shown by statistical analysis of 29 representative studies, turned out to be the administered dose and the particle size. Both these variables influence the actual dose and the contact-time of the B[a]P particles with the target cells. The present study does not support the widespread opinion that ferric-oxide particles enhance the tumour response of the respiratory tract. In conclusion to the present analysis, some recommendations are made which probably increase the predictability of the model.
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Human head and neck tumours were successfully transplanted in athymic nude mice. In 14 xenograft lines the effect of 1 to 3 clinically active agents could be tested. Maximum tolerated doses were given daily for 3-7 days. Growth delay was... more
Human head and neck tumours were successfully transplanted in athymic nude mice. In 14 xenograft lines the effect of 1 to 3 clinically active agents could be tested. Maximum tolerated doses were given daily for 3-7 days. Growth delay was estimated in terms of the number of volume doubling times gained by the treatment. Cis-platinum and bleomycin appeared to be effective agents. In all 6 lines in which cis-platinum was examined, growth delay sometimes followed by complete regression was achieved. In 6/7 lines a response to bleomycin was observed. There was wide variation in sensitivity to cis-platinum and bleomycin among the different lines. Methotrexate, effective in 40-60% of patients with head and neck cancer, essentially showed no activity. Methotrexate produced a minimal growth delay in 1/11 lines treated. Two of the patients from whom xenografts were obtained responded to methotrexate treatment. The observed lack of activity of methotrexate against these tumour xenografts indic...
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The main goal of this study was to investigate whether and at what level damage of paternal DNA influences fertilization of oocytes and early embryonic development. We hypothesized that posttesticular sperm DNA damage will only marginally... more
The main goal of this study was to investigate whether and at what level damage of paternal DNA influences fertilization of oocytes and early embryonic development. We hypothesized that posttesticular sperm DNA damage will only marginally affect sperm physiology due to the lack of gene expression, but that it will affect embryo development at the stage that embryo genome (including the paternal damaged DNA) expression is initiated. To test this, we artificially induced sperm DNA damage by irradiation with x- or gamma rays (doses of 0-300 Gy). Remarkably, sperm cells survived the irradiation quite well and, when compared with nonirradiated cells, sperm motility and integrity of plasma membrane, acrosome, and mitochondria were not altered by this irradiation treatment. In contrast, a highly significant logarithmic relation between irradiation dose and induced DNA damage to sperm cells was found by both terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL)...
Research Interests: Andrology, Gamma Rays, DNA damage, Apoptosis, Gene expression, and 22 moreX Rays, Pregnancy, Female, Animals, In Vitro Fertilization, Male, Embryo Transfer, Behavioral Animal Models, Clinical Sciences, Cattle, Fertilization, Embryonic Development, Acrosome, Spermatozoa, Sperm Motility, Oocytes, Embryos, Cell Survival, Plasma Membrane, Acridine Orange, Embryo Development, and Terminal Deoxynucleotidyl Transferase
The interaction between enrofloxacin and porcine phagocytes was studied with clinically relevant concentrations of enrofloxacin. Enrofloxacin accumulated in phagocytes, with cellular concentration/extracellular concentration ratios of 9... more
The interaction between enrofloxacin and porcine phagocytes was studied with clinically relevant concentrations of enrofloxacin. Enrofloxacin accumulated in phagocytes, with cellular concentration/extracellular concentration ratios of 9 for polymorphonuclear leukocytes (PMNs) and 5 for alveolar macrophages (AMs). Cells with accumulated enrofloxacin brought into enrofloxacin-free medium released approximately 80% (AMs) to 90% (PMNs) of their enrofloxacin within the first 10 min, after which no further release was seen. Enrofloxacin affected neither the viability of PMNs and AMs nor the chemotaxis of PMNs at concentrations ranging from 0 to 10 microg/ml. Enrofloxacin (0.5 microg/ml) did not alter the capability of PMNs and AMs to phagocytize fluorescent microparticles or Actinobacillus pleuropneumoniae, Pasteurella multocida, and Staphylococcus aureus. Significant differences in intracellular killing were seen with enrofloxacin at 5x the MIC compared with that for controls not treated...
Research Interests: Microbiology, Medical Microbiology, Animals, Staphylococcus aureus, Quinolones, and 12 moreNeutrophils, Phagocytosis, Swine, Antimicrobial agents, Microbial Sensitivity Tests, Pasteurella Multocida, Actinobacillus pleuropneumoniae, Antineoplastic Agents, Phagocytes, Fluoroquinolones, Alveolar Macrophage, and Host Defense
Spontaneous nasal tumors in ageing rats are very rare. Chronic irritation and disruption of nasal, paranasal, buccal, and dental tissues have been associated with the occurrence of tumors of the nasal and paranasal structures in rats. To... more
Spontaneous nasal tumors in ageing rats are very rare. Chronic irritation and disruption of nasal, paranasal, buccal, and dental tissues have been associated with the occurrence of tumors of the nasal and paranasal structures in rats. To find out whether there is a relationship between malocclusion (MO) and nasal squamous cell carcinoma (SCC) in Cpb:WU (Wistar random) rats, a total of 899 untreated control rats (548 males and 351 females) from eight long-term toxicity/carcinogenicity studies was screened for nasal tumors and MO. All relevant data and the histopathology of the nasal and paranasal structures of a sample of these rats (189 males and 197 females from three of the studies) and all rats bearing a nasal tumor were subjected to a detailed analysis. Of the 899 rats, 84 males (15%) and 78 females (22%) suffered from MO. Microscopic examination revealed an unexpectedly high incidence of lesions in the nasolachrymal duct (NLD): 64 out of 189 males (34%) and 68 out of 197 female...
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The effect of a high dietary level of beta-carotene on the formation of preneoplastic and neoplastic respiratory tract lesions was studied in hamsters intratracheally treated with benzo[a]pyrene (B[a]P) attached to ferric oxide (Fe2O3)... more
The effect of a high dietary level of beta-carotene on the formation of preneoplastic and neoplastic respiratory tract lesions was studied in hamsters intratracheally treated with benzo[a]pyrene (B[a]P) attached to ferric oxide (Fe2O3) and suspended in saline. In addition to conventional histopathological examinations, the expression of cytokeratins and the glutathione S-transferase isoenzyme Pi (GST-Pi) was determined in tracheal epithelium using immunocytochemical techniques. B[a]P treatment increased the expression of cytokeratins in tracheal mucous and ciliated epithelial cells as detected by antibody RCK102 (cytokeratins 5 and 8), which normally recognizes basal cells only. The expression of cytokeratins in mucous and ciliated cells as detected by antibody RGE53 (cytokeratin 18) was decreased by B[a]P treatment. Furthermore, the expression of the cytokeratin detected by antibody RKSE60 (cytokeratin 10), characteristic of metaplastic squamous cells, and the expression of the GST...
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ABSTRACT Exposure to mycotoxins has been linked to adverse effects on female reproduction by interfering with the synthesis, metabolism or degradation of steroid hormones, interaction with steroid receptors or impairing oocyte maturation... more
ABSTRACT Exposure to mycotoxins has been linked to adverse effects on female reproduction by interfering with the synthesis, metabolism or degradation of steroid hormones, interaction with steroid receptors or impairing oocyte maturation and competence. To assess such effects, many studies initially focussed on possible endocrine actions of mycotoxins using specific cell lines known to express key enzymes involved in the synthesis of steroid hormones. Using these models, zearalenone, deoxynivalenol, ochratoxin A, T-2 and HT-2 toxins, and aflatoxin B1 were claimed to be endocrine active substances. As yet, zearalenone is the only mycotoxin for which a direct interaction with oestrogen receptors could be demonstrated, classifying this mycotoxin as an endocrine disruptor. Mycotoxin exposure of complex cell systems like ovarian follicles at the earliest (primordial) to most advanced (pre-ovulatory) stages can serve not only as the first indication of the potential of a mycotoxin to affect female reproduction, but also provides insight in specific mechanisms involved in such an effect and identifies vulnerable phases in follicle development. Zearalenone is the most widely studied mycotoxin regarding female reproduction, but effects on oocyte maturation have also been demonstrated for deoxynivalenol. Exposure to zearalenone impairs the formation of primordial, while its metabolite ?-zearalenol is more harmful to fertilised oocytes than zearalenone itself. This short overview aims to provide an introduction into the different models, such as cell lines and oocytes, commonly used to assess the potential adverse effects of mycotoxins on female reproduction.
Steady-state plasma levels were determined for oxytetracycline (OTC), doxycycline (DC), and minocycline (MC) after medication with different in-feed concentrations. Each concentration of the three tetracyclines was examined in six pigs.... more
Steady-state plasma levels were determined for oxytetracycline (OTC), doxycycline (DC), and minocycline (MC) after medication with different in-feed concentrations. Each concentration of the three tetracyclines was examined in six pigs. The animals were housed in individual pens and fed twice daily with an interval of 12 h. All pigs consumed their feed within 1 h after it was provided. Concentrations of 400, 800, 1,600, and 2,400 mg of OTC per kilogram of feed induced steady-state plasma levels ranging from .13 to .22, .19 to .50, .39 to 1.43, and 1.41 to 2.14 micrograms/ml, respectively. On a feed intake basis, pigs received 13, 26, 54 to 81, and 108 mg of OTC per kilogram of BW per day, respectively. Steady-state plasma levels after medication with 200, 400, and 800 mg of DC or MC per kilogram of feed ranged from .37 to .89, .71 to 1.14, and 1.62 to 3.18 micrograms/ml for DC and from .21 to .60, .43 to 1.05, and 1.19 to 2.62 micrograms/ml for MC. Pigs consumed 7, 13, and 26 mg of ...
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Women presenting fertility problems are often helped by Assisted Reproductive Techniques (ART), such as in vitro fertilization (IVF) programs. However, in many cases the etiology of the in/subfertility remains unknown even after... more
Women presenting fertility problems are often helped by Assisted Reproductive Techniques (ART), such as in vitro fertilization (IVF) programs. However, in many cases the etiology of the in/subfertility remains unknown even after treatment. Although several aspects should be considered when assisting a woman with problems to conceive, a survey on the patients' exposure to contaminants would help to understand the cause of the fertility problem, as well as to follow the patient properly during IVF. Daily exposure to toxic compounds, mainly environmental and dietary ones, may result in reproductive impairment. For instance, because affects oocyte developmental competence. Many of these compounds, natural or synthetic, are endocrine disruptors or endocrine active substances that may impair reproduction. To understand the risks and the mechanism of action of such chemicals in human cells, the use of proper in vitro models is essential. The present review proposes the bovine and porci...
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Deoxynivalenol (DON, vomitoxin) is a secondary metabolite and mycotoxin produced by Fusarium species that occurs with a high prevalence in cereals and grains intended for human and animal consumption. Pigs are considered to be the most... more
Deoxynivalenol (DON, vomitoxin) is a secondary metabolite and mycotoxin produced by Fusarium species that occurs with a high prevalence in cereals and grains intended for human and animal consumption. Pigs are considered to be the most sensitive animal species and exposure to DON results in reduced feed intake, reduced performance and cause alterations in the expression of markers of inflammation and cell cycle regulation. The objective of this study was to determine how DON possibly affects the oocyte developmental potential in vitro at concentrations which correspond to those observed in practice. To evaluate DON toxicity during specific stages of oocyte meiosis, cumulus-oocyte complexes were exposed to 0.02, 0.2, or 2 microM DON. Exposure to the highest DON concentration inhibited cumulus expansion and induced cumulus cell death. After exposure for 42 h, DON at all concentrations reduced Metaphase II formation and led to malformations of the meiotic spindle. Despite spindle malformations, exposure to different concentrations of DON did not lead to increased percentages of blastomeres with abnormal ploidy in embryos. Spindle malformation occurred by DON exposure during formation of meiotic spindles at Metaphase I and II, but embryo development was also reduced when oocytes were exposed to DON during Prophase I. Together, these results indicate that exposure to DON via contaminated food or feed can affect oocyte developmental competence by interfering directly with microtubule dynamics during meiosis, and by disturbing oocyte cytoplasmic maturation through other as yet undetermined mechanisms.
Research Interests: Theriogenology, Biological Sciences, Meiosis, Text, Mycotoxins, and 17 moreFemale, Animals, Male, Cell Death, Secondary Metabolites, Oocyte Maturation, Fertilization, Embryonic Development, Swine, Cell Cycle regulation, Fertilization in Vitro, Deoxynivalenol, Oocytes, Embryos, Cell Survival, Feed Intake, and Embryo Development
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Research Interests: Embryology, Pregnancy, Toxicity, Reproductive toxicology, Mycotoxins, and 13 moreFemale, Animals, Pigs, Transgenerational effects on development, Preantral follicles, Public health systems and services research, Swine, Ovary, Oocytes, Transgenerational Effects, Zearalenone, Maternal-fetal exchange, and Gene expression profiling
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A computerized image analysis system (IAS) has been used to develop a new method for reading the agar diffusion test automatically. In four experiments a total of 88 porcine plasma and 95 urine samples were screened for oxytetracycline by... more
A computerized image analysis system (IAS) has been used to develop a new method for reading the agar diffusion test automatically. In four experiments a total of 88 porcine plasma and 95 urine samples were screened for oxytetracycline by the agar diffusion test. The inhibition zones were measured by hand and by the IAS directly from the bioassay plate and by the IAS from the photo-negative taken from the plate. Both methods were positively correlated with the hand method for plasma (0.9716, 0.9669) and urine (0.9878, 0.9731) in the range tested for 0.1 to 2.0 micrograms/ml. Moreover, the coefficient of variation and the day-to-day-variation amounted to 1.72% and 1.47% respectively, for the method by hand and 1.10, 1.54% and 0.27, 0.38% respectively, for the IAS methods. It is concluded that the IAS method is an objective and accurate alternative for reading the agar diffusion test.
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Research Interests: Andrology, Gamma Rays, DNA damage, Apoptosis, Gene expression, and 22 moreX Rays, Pregnancy, Female, Animals, In Vitro Fertilization, Male, Embryo Transfer, Behavioral Animal Models, Clinical Sciences, Cattle, Fertilization, Embryonic Development, Acrosome, Spermatozoa, Sperm Motility, Oocytes, Embryos, Cell Survival, Plasma Membrane, Acridine Orange, Embryo Development, and Terminal Deoxynucleotidyl Transferase
Several experimental models have been developed to study respiratory tract carcinogenesis. The most widely applied in vivo model uses Syrian golden hamsters which receive intratracheal instillations of a suspension of benzo[a]pyrene... more
Several experimental models have been developed to study respiratory tract carcinogenesis. The most widely applied in vivo model uses Syrian golden hamsters which receive intratracheal instillations of a suspension of benzo[a]pyrene (B[a]P) particles attached to ferric-oxide (Fe2O3) particles in saline; it was first described by Saffiotti et al. [1]. This model has several benefits compared with other experimental models; however, the large number of variables affecting the tumour response is a clear disadvantage because the tumour response is difficult to control. In this review, we describe a systematic analysis of various variables that may influence the tumour response of the respiratory tract with the aim to further standardize the method and increase, through that, its suitability and predictability. The most important variables influencing the tumour response, as shown by statistical analysis of 29 representative studies, turned out to be the administered dose and the particle size. Both these variables influence the actual dose and the contact-time of the B[a]P particles with the target cells. The present study does not support the widespread opinion that ferric-oxide particles enhance the tumour response of the respiratory tract. In conclusion to the present analysis, some recommendations are made which probably increase the predictability of the model.
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This study examined the effect of different methods of cryopreservation on the cytoskeletal integrity of camel embryos. A total of 32 embryos were recovered on Days 6 and 7 after ovulation and measured before being frozen using either a... more
This study examined the effect of different methods of cryopreservation on the cytoskeletal integrity of camel embryos. A total of 32 embryos were recovered on Days 6 and 7 after ovulation and measured before being frozen using either a conventional slow-cooling technique (n=12: six Day 6 and six Day 7 embryos) or vitrification (n=12: four Day 6 and eight Day 7). The remaining 8 'control' embryos (four Day 6 and four Day 7) were not cryopreserved but instead incubated in holding medium for 30 min. After thawing, warming or incubation, the embryos were stained with 4,6-diamino-2-phenylindole dihydrochloride (DAPI) to identify dead cells. Subsequently, the embryos were fixed in 4% paraformaldehyde, permeabilized and labelled with Alexa Fluor 488-Phalloidin to enable assessment of cytoskeleton integrity. Vitrified-warmed embryos contained a significantly higher percentage of dead cells than either conventionally frozen embryos or controls (P<0.05). Although the proportion of dead cells in conventionally frozen embryos tended to be higher than in controls, the difference was not significant (P> or =0.07). Whereas embryo size did not affect the number of dead cells in conventionally frozen embryos, vitrified-warmed embryos >300 microm in diameter had a significantly higher percentage of dead cells than embryos < or =300 microm (P=0.01). Cytoskeleton integrity was also affected by both freezing method and embryo diameter. All 8 control embryos had a Grade I cytoskeleton, compared with only 2/24 (8.3%) frozen or vitrified embryos. Of the 8 slow-frozen or vitrified embryos with a Grade III cytoskeleton post-thaw, 7 had been vitrified and 6 were larger (Day 7) embryos. These results indicate that while both slow-freezing and vitrification of camel embryos lead to cytoskeleton disruption and cell death, embryo quality is better preserved by slow-freezing.
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Human head and neck tumour tissues derived from 16 different patients were transplanted in athymic nude mice. Treatment of tumour-bearing animals with methotrexate had little or no effect on the doubling time of the xenografts. Included... more
Human head and neck tumour tissues derived from 16 different patients were transplanted in athymic nude mice. Treatment of tumour-bearing animals with methotrexate had little or no effect on the doubling time of the xenografts. Included were three tumour lines derived from patients in whom methotrexate did demonstrate antitumour activity. These results are also in contrast to clinical experience with methotrexate, showing remissions in 50% of patients with head and neck cancer. It is unlikely that this lack of effect of methotrexate is attributed to a difference in drug pharmacokinetics between man and nude mouse, since a xenografted rat tumour was found to be sensitive. With regard to possible resistance mechanisms underlying methotrexate inactivity, we found no evidence of increased dihydrofolate reductase activity in the methotrexate-insensitive human xenografts. It is possible that in this model a selection occurs favouring the outgrowth of a resistant subpopulation of tumour cells.