Hernia de Amyand: presentación de un caso y revisión de la literatura / Amyand hernia: report of one case

La presencia de apendicitis aguda en una hernia inguinal es un hecho infrecuente, con un 0,13% de los casos. Esta rara condición se conoce como Hernia de Amyand. La forma de presentación habitual es la de una hernia inguinal complicada. Es por este motivo que el diagnóstico preoperatorio de apendicitis aguda requiere de una alta sospecha clínica, realizándose mayoritariamente durante la cirugía. El estudio de imágenes, en particular la Tomografía Axial Computada, ha sido utilizado para plantear este diagnóstico. El tratamiento recomendado es la apendicectomía y la reparación primaria de la hernia en el mismo tiempo operatorio. No se debe utilizar prótesis por el riesgo de infección y fístula del muñón apendicular. Debido a lo excepcional de esta patología, presentamos el caso de un hombre de 75 años que se manifestó como una hernia inguinal complicada y cuyo diagnóstico de apendicitis se realizó en pabellón luego de abrir el saco.

The presence of an acute appendicitis in an incarcerated inguinal hernia, termed Amyand's hernia, is an uncommon and rare condition estimated to be found in approximately 0.13% of adult inguinal hernia repairs. The usual clinical presentation is as a complicated inguinal hernia; this is why the preoperative diagnosis of acute appendicitis requires a high clinical suspicion, even though the diagnosis of Amyand's hernia is done mainly during surgery. Computed tomography is a good diagnostic method. The treatment is surgical, and consists of an appendectomy with primary repair of the hernia. Synthetic mesh should not be used in the repair of contaminated abdominal wall defects, because the prosthetic material can increase the inflammatory response and result in wound infection and a possible appendiceal stump fistula. We report a 75 years old man who presented with a complicated inguinal hernia, in whom the diagnosis of acute appendicitis was made during surgery after opening the hernia sac.

Nondisjunction rates of mouse chromosomes involved in heterozygous Rb rearrangements measured by chromosome painting of spermatocytes. II. The effects of trivalent combinations and genetic background.

Chromosome specific nondisjunction rates were quantified by dual-colour FISH in spermatocytes II of Robertsonian heterozygous mice with different trivalent combinations or, alternatively, with different genetic backgrounds. We found that such factors do not influence the proneness to nondisjunction of specific chromosomes.

Nondisjunction rates of mouse specific chromosomes involved in heterozygous Rb rearrangements measured by chromosome painting of spermatocytes II. I. The effects of the number of trivalents.

Dual-colour FISH painting with alternative fluorescent chromosome-specific probes allowed us to distinguish chromosomes 1, 4, 6 and 14. The purpose was to check whether nondisjunction rates of specific chromosomes involved in heterozygous Robertsonian fusions are independent of the number of trivalents, or an epistatic effect among Rb chromosomes takes place affecting nondisjunction rates. Probes were used on DAPI-stained metaphases of spermatocytes II of laboratory strains of mice with reconstructed karyotypes heterozygous for one, two, three or four Robertsonian metacentrics in an all-acrocentric background. The existence of such epistatic interactions was not verified.

Comet assay and micronucleus test in circulating erythrocytes of Cyprinus carpio specimens exposed in situ to lake waters treated with disinfectants for potabilization.

The detection of a possible genotoxic effect of surface water treated with disinfectants for potabilization is the aim of the present work. The Comet assay and the micronucleus test were applied in circulating erythrocytes of Cyprinus carpio. Young specimens (20-30 g) were exposed in experimental basins, built within the potabilization plant of Castiglione del Lago (Perugia, Italy). In this plant the water of the Trasimeno Lake is treated and disinfected for potabilization before it is distributed to the people in the net of drinkable water. A continuous flow of water at a constant rate was supplied to basins; the water was continuously treated at a constant concentration with one of the three tested disinfectants (sodium hypochlorite, peracetic acid and chloride dioxide), one control basin being supplied with untreated water. Three sampling campaigns were performed: October 2000, February 2001 and June 2001. Repeated blood samplings through intracardiac punctures allowed to follow the same fish populations after different exposure times: before introduction of the disinfectant, and 10 or 20 days afterwards. An additional blood sampling was performed 3 h after addition of the disinfectant in other, simultaneously exposed, fish populations. Genotoxic damage was shown in fish exposed to water disinfected with sodium hypochlorite and chloride dioxide. The Comet assay showed an immediate response, i.e. DNA damage that was induced directly in circulating erythrocytes, whereas micronuclei reached their highest frequencies at later sampling times, when a genotoxic damage in stem cells of the cephalic kidney is expressed in circulating erythrocytes. The quality of the untreated surface water seems to be the most important parameter for the long-term DNA damage in circulating erythrocytes.

Cosegregation of Robertsonian metacentric chromosomes in the first meiotic division of multiple heterozygous male mice as revealed by FISH analysis of spermatocyte II metaphases.

Contrasting results (random segregation or cosegregation of isomorphic chromosomes) have been reported up to now on the segregation pattern of Robertsonian metacentric chromosomes of Mus musculus domesticus in multiple heterozygotes, using different approaches (karyotypical analysis of the progeny or of second meiotic metaphases). In the present contribution data are presented based on FISH (Fluorescence In Situ Hybridisation) analysis with telomeric probes, which allowed us to distinguish metacentric chromosomes from pairs of acrocentric chromosomes with their centromeric regions close to each other. Probes were hybridized to DAPI stained metaphases of spermatocytes II of mice heterozygous for two, three or four Robertsonian metacentrics in an all-acrocentric background, the karyotype of which has been reconstructed starting from laboratory strains. Isomorphic chromosomes tend to cosegregate (metacentrics with metacentrics, acrocentrics with acrocentrics); the values found for cosegregation have a clear even if moderate effect on the reproductive isolation caused by underdominant chromosomal rearrangements.

Genotoxicity of surface water treated with different disinfectants using in situ plant tests.

Disinfection of surface drinking water, in particular water chlorination, results in many by-products with potential genotoxic and/or carcinogenic activity. In the present study, we evaluated the genotoxicity of surface water after treatment with different disinfectants by means of in situ plant genotoxicity assays (micronucleus and chromosomal aberration tests) which can detect both clastogenic and aneugenic effects. The study was carried out at a pilot plant using lake water after sedimentation and filtration. This water supplied four stainless steel basins: three basins were disinfected with sodium hypochlorite, chlorine dioxide, and peracetic acid and the fourth basin containing untreated lake water was used as a control. Plants were exposed in situ in the basins. The study was carried out using water collected in different seasons over a period of about 1 year in order to assess the treatments in different physical and chemical lake water conditions. The micronucleus test in root cells of Vicia faba (Vicia faba/MCN test) revealed genotoxicity in many samples of disinfected water. The micronucleus test in Tradescantia pollen cells and the chromosome aberration test in root cells of Allium cepa showed genotoxic effects only in some disinfected samples, but also revealed genotoxicity in raw water. The results of the study indicated that the Vicia faba/MCN test was the most sensitive plant assay for disinfected water and that peracetic acid disinfection produced similar or lower genotoxicity than sodium hypochlorite or chlorine dioxide treatment.

[Genotoxicity of surface water treated with different disinfectants using in situ plant tests]. / Valutazione della genotossicità di acque superficiali trattate con diversi disinfettanti mediante test su vegetali.

Disinfection of surface drinking water, in particular water chlorination, produces many by-products with genotoxic and/or carcinogenic activity. The aim of this research was to evaluate the genotoxicity of surface water after treatment with different disinfectants by means of in situ plant genotoxicity assays. The study was carried out in a pilot plant using lake water after sedimentation and filtration, which supplied four stainless steel basins: three basins were disinfected with sodium hypochlorite, chlorine dioxide and peracetic acid, respectively, and the fourth basin contained untreated lake water and was used as a control. The study was carried out using water collected in different seasons over a period of about one year in order to assess the treatments under different physical and chemical lake water conditions. Plant genotoxicity tests were performed by exposing plant bioindicators directly to raw and disinfected water. The Tradescantia micronucleus test in pollen cells of the flowers of an hybrid of Tradescantia and the Allium cepa test, a chromosome aberration test in root cells of Allium cepa, showed genotoxic effects only in some disinfected samples and revealed genotoxicity also in raw water in one experiment. The Vicia faba test, a micronucleus test in root cells of Vicia faba, revealed genotoxicity in many samples of disinfected water. The results of the study indicated that the Vicia faba/MCN test was the most sensitive plant assay for disinfected water, and that peracetic acid disinfection produced lower genotoxicity than sodium hypochlorite or chlorine dioxide treatment.

Micronuclei induced in erythrocytes of Cyprinus carpio (teleostei, pisces) by X-rays and colchicine.

In the present work the induction of micronuclei in erythrocytes of Cyprinus carpio treated with X-rays and colchicine is studied for the evaluation of mutagenic effects of both clastogenic and mitoclastic (spindle poisoning) agents in this system. Three different experiments were performed treating groups of laboratory-reproduced animals with (1) single doses of X-rays (0.1, 0.5 and 2Gy); (2) a single i.p. injection of colchicine at the concentrations: 1.6x10(-2), 8x10(-2), 0.4 and 2mg/kg b.w. so as to mimic an acute exposure to the agent and (3) six repeated i.p. injections of the first three concentrations of colchicine, over a period of 18 days, so as to mimic a chronic exposure. Repeated blood samplings were performed by cardiac puncture over a period of about 2 months after the treatment and micronucleus frequencies were determined at multiple times on the same individuals after mutagen exposure. A dose-dependent increase in the micronucleus frequency was observed in irradiated fish and a peak value detected at 21 days. Slight increases of micronucleus frequencies were also observed in both colchicine experiments only for the highest concentrations at the earliest sampling time. Higher concentrations of colchicine clearly showed a lethal effect. According to the present data the micronucleus frequency induced by the highest colchicine dose is comparable to that observed after 0.1Gy of X-ray irradiation.

Direct and indirect non-disjunction in the origin of trisomy in cultured human lymphocytes.

The aim of the present work was to investigate the processes involved in the origin of trisomic karyotypes, i.e. co-migration of sister chromatids (mitotic non-disjunction, MND) and recovery of micronuclei (MN) originating from lagging chromosomes/chromatids at anaphase (mitotic indirect non-disjunction, MIND), and to evaluate their relative contribution to aneuploidy in human lymphocytes mitotically activated in vitro. Therefore, phytohaemagglutinin-stimulated human lymphocytes from one donor were treated with 10 and 25 nM colchicine and analysed through two cell cycles by means of both molecular (FISH with centromeric DNA probes specific for chromosomes 7 and 11) and classical cytogenetic techniques. The following events were analysed: (i) chromosome/chromatid loss (a MN-generating event) in M(1) bipolar ana-telophases; (ii) MN recovery in M(2+) prophases; (iii) non-disjunction and loss of chromosomes 7 and 11 by FISH analysis in cytochalasin B-induced binucleate cells; (iv) spontaneous frequency of trisomic cells by chromosome counting and FISH analysis in M(1) c-metaphases; (v) induced frequency of trisomic cells by chromosome counting and FISH analysis in M(2) c-metaphases. Our results indicate that MND plays a major role compared with MIND in the origin of trisomic karyotypes, being approximately 4- to 5-fold higher in colchicine-treated cells. Moreover, remarkable reductions in the observed frequencies of trisomic cells were recorded in comparison with the expected ones, with an observed/expected frequency ratio of trisomic M(2) c-metaphases ranging between 1/3 and 1/6.

Effect of cytochalasin B on the induction of chromosome missegregation by colchicine at low concentrations in human lymphocytes.

The aim of the present work was to investigate the possible interference of cytochalasin B (cyt B) with low concentration treatment with colchicine in the induction of chromosome/chromatid loss and micronuclei in human lymphocytes mitotically activated in vitro. Thus, cells from a single female donor were treated with colchicine (10 or 25 nM, from 24 h after PHA addition to fixation at 66 h) either in the presence or absence of cyt B. Single lagging chromosomes/chromatids were scored in bipolar ana-telophases and greater damage (disrupted and c-anaphases) was scored in cells at anaphase. Micronuclei were scored in the first 4000 nuclei observed in both cyt B-treated (in mononucleate and binucleate cells) and untreated cultures. With the same criterion, FISH analysis was performed on 2000 nuclei where chromosome 7 and 11 centromeric DNA probes were used in pairs. Our results showed that: (i) the frequency of laggards and of micronuclei increased with colchicine concentration but in the presence of cyt B there was a lower frequency of both (with a mean reduction of approximately 49%); (ii) FISH analysis showed a colchicine concentration-dependent increase in nuclei with three spots for chromosome 7; (iii) a colchicine concentration-dependent increase in tetraploid cells was observed. This increase was particularly remarkable (5-fold) in cells grown in the presence of cyt B compared with cyt B-untreated cells. The observed 'cyt B effects' can be explained if it is assumed that in cytokinesis-blocked cells there is a shorter distance between the poles. As a consequence: (i) laggards would be engulfed in the nearest daughter nucleus with a consequent lower induction of micronuclei; (ii) segregating sister chromatids in heavily impaired anaphases would not travel a sufficient distance to give rise to two daughter nuclei, leading to an increased frequency of polyploid nuclei.

Relationship between chromatin bridges in anaphase and chromosomal aberrations induced by TMP + UVA (365 nm) in CHO cells.

In a recent paper, the hypothesis of 'conservative pairing' between complementary DNA strands belonging to both sister chromatids has been proposed as a phenomenon that could account for, at least in part, sister chromatid pairing in late G2/mitosis. The hypothesis was verified through a cytogenetic approach, studying the so-called 'sister chromatid chromatin bridges' (SCCBs), induced in the previous G2/mitosis by a crosslinking (TMP + UVA 365 nm) treatment in CHO cells (Rizzoni, M., E. Cundari, P. Perticone and B. Gustavino (1993) Chromatin bridges between sister chromatids induced in late G2 mitosis in CHO cells by trimethylpsoralen + UVA. Experimental Cell Res., 209, 149-155; [1]). The purpose of the present paper is the study of the relationship between chromatin bridges without fragments in ana-telophase, which were demonstrated to be SCCBs, and chromosomal aberrations, in order to investigate their mechanism of induction. The evolution along the time of the two classes of mitotic anomalies was studied and a comparison was carried out to verify whether the bridges rise as a direct and immediate effect of the treatment or represent the misrepair-mediated effect of it. The present data show that single bridges without fragments come from a direct effect of photoinduced crosslinks in late G2/mitosis. Moreover TMP + 365 nm UVA treatment shows an S-dependent clastogenic effect. The proposed hypothesis of 'conservative pairing' between DNA strands of sister chromatids is further supported.

Mitotic indirect non-disjunction in phytohemagglutinin stimulated human lymphocytes.

In a previous publication we demonstrated that in cells of Vicia faba micronuclei derived from whole lagging chromosomes or chromatids may perform DNA synthesis and mitotic condensation in synchrony with main nuclei and be regained by main nuclei at the next mitosis, giving rise to trisomic cells together with diploids. This process was called 'mitotic indirect non-disjunction' (MIND). In the present work the occurrence of MIND was studied in human lymphocytes cultivated in vitro. Human lymphocytes were treated with low colcemid concentrations until fixation; BrUdR was supplied together with colcemid to distinguish the number of mitoses performed by the cells (M1, M2 and M3 cells). The frequencies of M1 ana-telophases with single lagging chromosomes/chromatids and of M2+ prophases with single micronuclei in synchronous motitic condensation with main nuclei were evaluated. On this basis the expected frequencies of both monosomic and trisomic M2 cells were calculated, according to the hypothesis of MIND. Their observed frequencies were very close to those expected. These results support the hypothesis of the occurrence of MIND in human lymphocytes.

Chromatin bridges between sister chromatids induced in late G2 mitosis in CHO cells by trimethylpsoralen + UVA.

A hypothesis is proposed that sister chromatid pairing is due, at least in part, to the pairing between DNA strands belonging to each of the two sister chromatids (conservative pairing). To test this hypothesis interstrand DNA cross-links were induced in late G2-mitosis in CHO cells in order to bind covalently paired DNA strands eventually coming from both sister chromatids and detect the consequent chromatin bridges between sister chromatids (SCCBs). Therefore cells were treated with trimethylpsoralen (TMP) + UVA (365 or 405 nm). Chromatin bridges in ana-telophase were induced by an UVA irradiation at 365 nm, which gives rise to both monoadducts and cross-links, but not by a 405-nm irradiation, which gives rise only to monoadducts. An analysis of colchicine-induced c-anaphases demonstrated that such chromatin bridges were really SCCBs and that terminal regions of chromosomes were particularly involved. The evolution of SCCBs was studied to rule out that they were masked isochromatid exchanges. So TMP + UVA-treated cells were induced to polyploidize with colchicine and labeled with 5-bromodeoxyuridine. Cells treated with TMP + UVA in G2-mitosis appeared as M1 tetraploid c-metaphases; in such cell populations there was not an increase in isodicentric chromosomes, which are derived from isochromatid exchanges. The present data, as a whole, support the hypothesis that a "conservative pairing" between DNA strands of sister chromatids can be present in mitosis.

Vinblastine-induced numerical chromosome changes and selection processes in mouse bone marrow cells.

The effect of selection processes operating on chemically induced aneuploid and polyploid cells was studied in mouse bone marrow cells at their third generation after a single i.p. treatment with vinblastine (VBL). Bromodeoxyuridine (BrdUrd)-labeled metaphases were analyzed for chromosome number and the frequencies of aneuploid and polyploid cells recorded at 2 different times, both within the third cell cycle after VBL treatment. Cell-cycle progression was analyzed for both control and treated mice at the 2 fixation times. Our data suggest that polyploid cells and possibly also cells with numerous additional chromosomes could have a cell cycle longer than that of diploid cells and cells hyperploid for 1-2 additional chromosomes. Both hyperploid and polyploid cells seem to have a reduced probability of undergoing further mitoses, as shown by the reduction of their frequencies at the third cell cycle, when compared to the frequencies observed in the second cell cycle after the same VBL treatment.

Indirect mitotic nondisjunction in Vicia faba and Chinese hamster cells.

The hypothesis of indirect mitotic nondisjunction was tested in plant and mammalian cells. This hypothesis states that micronuclei derived from lagging chromosomes or chromatids are able to perform DNA synthesis and undergo mitotic condensation synchronously with main nuclei. Hence, as chromosomes, they can be moved to spindle poles together with the chromosomes of the main nuclei during mitosis. In that way chromosomes "lost" as micronuclei can be reincorporated in the main nuclei. In order to test this, both Vicia faba meristematic cells and cells of a Chinese hamster line (Cl-1) were treated with low doses of colchicine. Mitotic anomalies, micronuclei and cells with a polyploid or aneuploid karyotype were scored at different fixation times. A detailed analysis was performed on single chromosome misdistributions, as well as on micronuclei and cells with aneuploid karyotypes derived from single chromosome misdistributions. Indirect mitotic nondisjunction was shown to play a primary role in the origin of aneuploid karyotypes in Vicia faba, but not in Cl-1 cells.

A comparison between short-term evolution of micronuclei induced by X-rays and colchicine in root tips of Vicia faba.

The short-term evolution of micronuclei derived from acentric fragments and whole chromosomes was studied in root tips of Vicia faba. Micronuclei were induced by X-rays (30 cGy and 120 cGy) and colchicine (10(-5) M and 3 X 10(-4) M). Frequencies of chromosome breakage or loss of micronuclei in interphase and mitotic cells were studied. The DNA content of micronuclei in interphase cells was also measured. Micronuclei derived from whole chromosome showed a higher probability to survive and to undergo mitotic condensation in synchrony with main nuclei than micronuclei derived from an acentric fragment. PCC (Premature Chromosome Condensation) was not observed for both types of micronuclei in Vicia faba, in contrast to the ones reported in mammalian cells in culture.

Sister chromatid exchanges induced by DNA demethylating agents persist through several cell cycles in mammalian cells.

Eukaryotic DNA methylation has been extensively studied in recent years. The ability of many carcinogens to interfere with DNA methylation has not yet been directly related to their tumorigenic activity. Recent data obtained using L-ethionine and 5-azacytidine--both demethylating agents--showed a small but significant increase in the sister chromatid exchange (SCE) rate induced in mammalian cells (human lymphocytes and CHO cells). In this paper we show that the SCE increase induced by both these agents in Chinese hamster ovary (CHO) cells persists for as long as 10 cell cycles. On the other hand mitomycin-C and u.v. light-induced SCEs show a rapid decrease to the control value, as reported for all known SCE inducers. We suggest that DNA demethylation and SCEs are connected through a perturbation of the cell machinery at the level of the replication fork, producing an increase of the error-prone ligation. Since the methylation level is maintained (inherited), the SCE increase produced by these recombinational events will not be corrected through several cell cycles.

Micronucleus induction by low doses of X-rays in Vicia faba root tips.

Studies on the micronucleus test in Vicia faba root tips (VM test) were carried out in order to estimate the effects at low doses of X-rays (1, 2, 4, 8 and 12 R). The control value of micronucleus frequency is about 0.44/1000 cells. The dose where the micronucleus frequency is twice that of the control was estimated at 1.384 R. There was a linear kinetic dose response for the low-dose range studied here.

Restriction endonuclease Bam H I induces chromosomal aberrations in Chinese hamster ovary (CHO) cells.

Treatment of Chinese hamster ovary (CHO) cells with the restriction endonuclease Bam H I (recognition site: G/GATCC) leads to high frequencies of chromosomal aberrations. Experiments with bromodeoxyuridine-labelled chromosomes show that the aberrations occur nearly exclusively in first post-treatment metaphases. The results are interpreted to mean that only some of the cells take up the enzyme and that these cells are the ones showing the aberrations. Cells which do not take up the enzyme show up as differentially stained metaphases and have no aberrations. Why some cells take up the restriction enzyme and others not is not known, possibly this is dependent on the physiological condition of the cells.