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Biomedical subjects

I C Enninga

Publications and source records attributed to I C Enninga.

9 recordsLinked to original sources
PubMed1998

Tissue implantation test in rabbits with gelatine sponges.

The purpose of this implantation study was to evaluate possible toxic effects and quality and quantity of resorption of two different resorbable gelatine sponges when implanted into the paravertebral muscle of the rabbit for a period of 7, 14 or 21 days and to evaluate bioequivalence of two types of test material. Test materials (Gelaspon) and a commercially available reference material were compared in three groups with 6 rabbits each. Tissue reaction to the implants and sponge degradation were scored on a graded scale and the sponges were compared for evaluation. No treatment-related mortality or body weight changes were observed. Clinical signs, indicative of local effects, were mainly seen for reference material. Tissue reaction after 7 days was comparable, after 14 and 21 days a significant increase in granulomatous reaction was seen for reference material. Sponge degradation was complete for test materials after 14 and 21 days without inflammatory tissue reaction, but small sponge rests of reference material were still present, accompanied by an increased inflammatory response. Results show test materials to fulfil the clinical requirements for implant material concerning fast resorption without inflammatory reactions and its superiority to reference material. Bioequivalence of used types of test material could be confirmed.

Animals↗
PubMed1995

Continuous intravenous infusion in the unrestrained rat--procedures and results.

1. A method of continuous infusion in the unrestrained rat is described, which provides a scientifically acceptable and easily maintained rodent model for use in toxicological investigations. 2. Sprague Dawley SPF rats had cannulas implanted into the vena cava via the femoral vein, and were continuously infused with physiological saline for a total of 28 or 90 days. 3. The results indicate that there was no change in body weight, food consumption, clinical observations or clinical biochemistry of infused rats when compared to non-infused rats. There were small changes in haematological parameters, however none were toxicologically significant. Urinary volume was increased and urinary specific gravity and osmolality were decreased. At macroscopic and microscopic examination there were findings of scar formation associated with the area of surgery and minimal irritation in the area of the vena cava which accommodated the cannula. 4. These results indicate that implantation of a cannula into the vena cava of a rat and subsequent continuous intravenous infusion of physiological saline produces no toxicological adverse effects over a period of 90 days. Consequently, this model can be recommended for the continuous intravenous administration of test substances to rats.

Animals↗
PubMed1994

Hematology and serum biochemistry of Japanese quail fed dietary tri-n-butyltin oxide during reproduction.

During a subchronic toxicity and reproduction study with tri-n-butyltin oxide (TBTO) concentrations of 0, 24, 60, and 150 mg/kg diet in Japanese quail, preliminary data on hematology and serum biochemistry were obtained. The absence of serious effects in blood parameters in both adult quail and developing chicks are discussed in view of the adverse effects of TBTO on reproduction.

Administration, Oral↗
PubMed1992

Subchronic toxicity and reproduction effects of tri-n-butyltin oxide in Japanese quail.

A subchronic toxicity/reproduction study was performed in Japanese quails that were fed a diet containing 0, 24, 60, and 150 mg tri-n-butyltin oxide (TBTO) per kg basal diet for 6 weeks. Eggs produced during the 6 weeks of treatment were incubated and hatched, and chicks hatched from eggs collected in weeks 5 and 6 of exposure were reared for 2 weeks. In parent quail, neither diminished food consumption nor any overt toxic or histopathologic signs were observed following exposure to TBTO. A statistically significant decrease in hatch-ability and increase in percent of chicks found dead in the shell were observed following TBTO exposure at concentrations of 60 and 150 mg/kg food. However, no significant, adverse effects were recorded on total egg production, eggshell thickness and cracked eggs. Blood chemistry parameters of birds measured at the last day of TBTO treatment revealed a statistically significant decrease in serum aspartate aminotransferase (ASAT) enzyme activity among both sexes in all treatment groups. In addition, a statistically significant dose-related decrease in serum calcium level was observed in females only, while serum follicle stimulating hormone (FSH) levels were statistically significantly reduced in male birds in all treatment groups (approximately 50% of the controls). Moreover, a significant decrease in hepatic microsomal 7-ethoxyresorufin (EROD) activity was recorded in females fed 24 and 60 mg TBTO/kg diet and males fed 60 and 150 mg TBTO/kg diet, whereas pentoxyresorufin-o-deetylase (PROD) activity was only significantly decreased in males fed 150 mg TBTO/kg diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The wavelength dependence of u.v.-induced pyrimidine dimer formation, cell killing and mutation induction in human diploid skin fibroblasts.

In this study, we determined the wavelength dependence of u.v.-induced pyrimidine dimer formation, cell killing and mutation induction in human diploid skin fibroblasts. Pyrimidine dimers were quantified using the T4 endonuclease V assay, cell killing was measured as loss of colony forming ability and mutation induction was detected at the HPRT locus. U.v. irradiation was performed with monochromatic light of four different wavelengths (254, 297, 302 and 365 nm) and with polychromatic light of a Philips TL-01 lamp (predominantly 312 nm). The relative wavelength dependence for cell killing and mutation induction did not correlate with that for dimer formation. Toxicity and mutagenicity per equivalent initial dimer load increase with increasing wavelength. The relative wavelength dependence for cell killing and mutation induction is essentially the same, except at 365 nm.

Cell Survival↗
PubMed1984

Use of low temperature for growth arrest and synchronization of human diploid fibroblasts.

The growth kinetics of human diploid fibroblasts at two different temperatures were followed. Proliferation of exponentially growing cells is reduced and eventually stops upon incubation at low temperature (i.e. 30 degrees C). The cells which are in S phase at the time of switching to low temperature complete their DNA synthesis and become arrested in the G1 phase of the cell cycle. The arrested cells can be stimulated to proliferate by restoration of the optimal growth temperature (37 degrees C). The kinetics of entry into S phase were investigated by measuring [3H]thymidine incorporation into TCA-precipitable material, by autoradiography and by flow cytofluorimetry. The synchronized cells initiate DNA synthesis at approximately 8 h and DNA synthesis peaks at 20.4 +/- 0.7 h after stimulation. In addition, the rates of UV-induced excision repair at 30 degrees C and 37 degrees C were compared. The results indicate that at 30 degrees C the excision-repair process is operative but at a slightly reduced rate in comparison with repair at 37 degrees C. This method will be useful for the study of S-phase-dependent processes, as well as for repair studies in the absence of cell division.

Cell Cycle↗
PubMedDate not supplied

Recovery of growth-arrested human fibroblasts from UV-induced lethal damage is inhibited by low cell density or sodium butyrate.

The influence of growth arrest on recovery from UV-induced lethal damage in human fibroblasts was investigated. Cells were arrested in G1 either by confluent holding (high cell density at 37 degrees C) or by temperature holding (low cell density at 30 degrees C) or by a combination of both methods. These experiments showed that survival recovery only occurred in cells arrested at high cell density, both at 37 degrees C and at 30 degrees C, and not in cells arrested at low cell density at 30 degrees C. Furthermore, it was demonstrated that the rate of transcription in unirradiated cells arrested at high density, both at 37 degrees C and at 30 degrees C, was much lower compared to that in cells arrested at low density. These observations can be explained by assuming that impaired transcription is responsible for UV-induced cytotoxicity and that recovery of RNA synthesis due to repair of damage in transcriptionally active genes may account for survival recovery. Sodium butyrate did not influence the absence of recovery during low temperature holding at low density but inhibited survival recovery during confluent holding. Sodium butyrate might prevent survival recovery at high cell density by inducing a chromatin structure resembling that of untreated cells arrested at low density.

Butyrates↗
PubMedDate not supplied

Differential response of human fibroblasts to the cytotoxic and mutagenic effects of UV radiation in different phases of the cell cycle.

The effects of DNA repair on UV-induced mutagenesis and cell killing in human diploid skin fibroblasts in different phases of the cell cycle were studied. The cells were synchronized in G1 by culturing at 30 degrees C. Using this synchronization method, it could be demonstrated that cells irradiated at 30 degrees C and allowed to carry out excision repair for various lengths of time, show a much lower mutation frequency than cells irradiated in the exponentially growing state. Irradiation in early G1 gives rise to less mutations than irradiation in S. However, the surviving fraction is not decreased when cells are irradiated in S in comparison with irradiation in G1. Moreover, there is no recovery from UV-induced lethal effects when irradiated cells are kept stationary at 30 degrees C for various periods of time. This is in contrast with the results obtained with density-inhibited fibroblasts held at 37 degrees C, which show a recovery from the UV-induced lethal effects.

Cell Cycle↗