Influence of intestinal resections on biliary composition and liver ultrastructure.

BACKGROUND & AIMS: Among the multiple factors that can influence bile acid (BA) metabolism and biliary poles, intestinal resections could do so directly (through absorption alterations) and/or indirectly (bacterial translocation, alterations of the hepato-intestinal hormonal axis). Our aim was to study the influence of partial intestinal resections on bile metabolism and biliary structure in an animal model. METHODS: Dunkin Hartley guinea pigs were used: Group A with only jejunum resection, Group B with only ileum resection, and Group CtrG, the control group. They were monitored for 21 days, with oral nutrition. At the end of this period, samples of the bile were taken from the hepatic duct and vena cava. After liver perfusion, samples of hepatic tissue were taken for optical and electron microscopy. RESULTS: There was a significant decrease in serum cholesterol in both GA & GB. The levels of biliary phospholipids (Ph) and cholic acid decreased only in Group B, but not ketolithocholic acid nor total conjugated BA. Slight liver macrosteatosis was observed in GB, but there were no changes in the biliary poles or canaliculi in the electron microscopy samples. CONCLUSIONS: Ileum resections affect the biliary Ph and BA composition, which could increase bile lithogenicity but do not seem to affect biliary duct anatomy.

[Optimization of sentinel lymph node biopsy in breast cancer by intraoperative axillary palpation]. / Optimización de la biopsia selectiva de ganglio centinela en el cáncer de mama mediante palpación axilar intraoperatoria.

INTRODUCTION: Sentinel node biopsy (SNB) by radioisotopes is a widely accepted and reliable surgical method for staging breast cancer in patients with unknown positive axillary lymph nodes involvement. The main limitation of this method is due to the appearance of false negatives that may be caused by tumor lymph node blockage of the sentinel lymph node and uptake in the neighboring lymph nodes. Infiltered sentinel nodes are generally increased in size and firm. Thus, they can be detected by intraoperative palpation, even when there is no uptake by the radiotracer. AIM: To reduce the false negative rates by applying intraoperative axillary palpation after SNB. METHOD: Over a two-year period, we complemented the SNB in 168 patients with careful intraoperative axillary palpation, detecting and removing all the palpable suspicious lymph nodes (SLN) that were analyzed as sentinel nodes RESULTS: In 32 out of 168 patients, 50 palpable SLN were found. In 3 out of 32 patients, 4 infiltrated SLNs were demonstrated with negative SNB and positive axillary lymphadenectomy. Thus, intraoperative palpation avoided false negative results. In one patient, one palpable SLN with tumor involvement was observed and SNB was also positive. In the remaining 28 patients, the histological analysis of 45 SLN was negative for tumor but SNB was positive in 3 patients. CONCLUSION: Intraoperative axillary palpation, once the SNB was done, reduced the false negative rate. Thus, we consider that it should be included as one more part of this procedure.

Early IFN-gamma production is related to the presence of interleukin (IL)-18 and the absence of IL-13 in experimental Trypanosoma cruzi infections.

Gamma-interferon (IFN-gamma) production, the hallmark of the Th1 immune response, has been shown to play a central role in the resistance to Trypanosoma cruzi infections, in particular when produced in the very early acute infection. BALB/c mice infected with T. cruzi, Tulahuén strain, reach high parasitemias during the acute phase, and their spleen cells release IFN-gamma in the second week of the infection, while those of the resistant C3H strain produce the cytokine earlier, at 2 days post-infection (pi). We studied in the spleen cells supernatants of infected BALB/c and C3H mice, the spontaneous production of cytokines involved in the induction, interleukin (IL)-18 and IL-12 p70, as well as in the downregulation, IL-13 and IL-10, of the Th1 immune response. We found that, at 2 days pi, only C3H mice produced IL-18, while IL-12 p70 was detected in both mouse strains. Moreover, at this time pi splenocytes from BALB/c mice spontaneously produced high amounts of IL-13. At 14 days pi, despite the increased levels of IL-13 and IL-10 detected in C3H mice, they still showed high concentrations of IL-18 and IL-12 p70. In contrast, spleen cells from BALB/c mice did not secrete IL-18, IL-12 p70 and IL-13 at this time pi, but produced higher amounts of IL-10 than C3H mice. Non of these cytokines was found increased in the cell supernatants of chronically infected mice. The addition of lipopolysaccharide (LPS) or Concanavalin A (Con A) to the cell cultures did not enhance the production of IL-18 and IL-12 at the time points tested. On the other hand, at 21 days pi, when parasitemia peaked, an inhibition of both the LPS induced IL-10 release and the IL-13 production upon Con A stimulation was observed in C3H, but not in BALB/c mice. We did not find an increase of IL-18, IL-10, or IL-12 p70 in the serum of the infected mice, despite the high seric IL-12 p40 concentrations reached during the infection. The data show that the different kinetics of the production of these cytokines in the spleen of both mouse strains could have a key role in the in vivo regulation of IFN-gamma production. In these experimental models, early IFN-gamma release and thus resistance to T. cruzi infection, could be related to the combined effect of both IL-18 and IL-12p70 in the absence of IL-13.

[Gastric bezoar]. / Bezoar gástrico.

Bezoar consist of the accumulation of different substances in the digestive tract. We present the clinical case of a girl with gastric trichobezoar discovered in a postoperatory follow-up to an appendicectomy. Ultra-sound images and oesophagus-gastric transit are fundamental points in the diagnosis. Endoscopy was useful in confirming the diagnosis and in ruling out associated ulcus, frequent in these patients. Surgical treatment is the choice in big bezoar but laser, prokinetics and enzymatic dissolutions have also been used. Theses patients should undergo psychological control.

IL-12 and IFN-gamma production, and NK cell activity, in acute and chronic experimental Trypanosoma cruzi infections.

Resistance to acute Trypanosoma cruzi infection is mainly associated with a Th1 immune response, characterized by gamma-interferon (IFN-gamma) production and activation of macrophages. The outcome of the Th1 response in the spleen and serum of BALB/c and C3H mice infected with T. cruzi, Tulahuén strain was studied. The levels of interleukin-12 p40 (IL-12 p40) and IFN-gamma, as well as natural killer (NK) cell cytotoxicity were determined at different time-points during the acute phase, and the production of cytokines was also studied in the chronic infection. At 2 days post-infection (pi), spleen cells from C3H mice increased their NK cell activity and the ex vivo spontaneous release of both IL-12 p40 and IFN-gamma. On the other hand, BALB/c mice reached low levels of NK cell cytotoxicity and no IFN-gamma production was detected at this time pi, but the cytokine was released at high amounts in the second week of the infection. Seric IL-12 p40 concentrations showed a 3-fold increase in both mouse strains on the second day pi and remained high throughout the acute phase. However, seric IFN-gamma levels increased during the late acute infection and were higher in BALB/c than in C3H mice. In chronically infected mice IL-12 p40 was as high as in the acute phase in the serum of both strains, but only BALB/c mice still produced IFN-gamma. To the authors' knowledge this is the first report showing the protein levels of IL-12 p40 determined in vivo in acute and chronic T. cruzi infections. The results reveal differences between both mouse strains in the mechanisms controlling the onset and fate of the Th1 response triggered by the parasite and a long lasting pro-inflammatory stimuli.

[TH1 response in the experimental infection with Trypanosoma cruzi]. / Respuesta TH1 en la infección experimental con Trypanosoma cruzi.

Specific antibodies and the activation of phagocytic cells by IFN-gamma are the key elements of the immune response involved in protection of the T. cruzi infected host. The central role of the IFN-gamma in vivo seems to be the activation of the inducible nitric oxide synthetase of macrophages (iNOS) and the production of nitric oxide (NO degree) for the intracellular destruction of the parasite. Interleukin 12 (IL-12), the cytokine that stimulates NK cells for IFN-gamma production, seems to trigger the TH1 response in the acute phase. Other cell types, such as lymphocytes Thy-1+CD4-CD8-, CD4+ and CD8+, are also involved in IFN-gamma production. The down regulation of the TH1 response could in part depend on the decrease in the macrophage activation, as a result of the controlled parasite burden, and on the production of IL-10 and transforming growth factor beta (TGF-beta). The protective TH1 immune response seems to be also related to both the tissue damage and the alterations of the immune response observed during the infection. We studied the kinetics of both NK cell activity, and the production of IL-12 and/IFN-gamma by spleen cells, as well as the seric levels of these cytokines, in BALB/c and C3H mice infected with T. cruzi, Tulahuén strain. In the spleen, we found that the production of IL-12 and the NK cell activity increased in the very early acute infection, and that in C3H the effect was higher than in BALB/c mice. IFN-gamma increased in C3H at the same time, but in the BALB/c strain it increased later in the acute phase. The infection induced a very early increase in the seric levels of IL-12, that remained high throughout the acute phase, in both mouse strains. However, the levels of IFN-gamma in the serum increased a few days before the peak of parasitemia, reaching higher values, and earlier, in BALB/c than in C3H mice. Surprisingly, in the chronic infection IL-12 production remained high in both mouse strains, but IFN-gamma production was only observed in BALB/c mice. The immune response was predominantly TH1 in both mouse strains, in spite of the higher susceptibility of BALB/c compared to C3H. The early control of the parasite burden could be evaluated as the expression of the TH1 response in spleen cells, while the seric levels of IL-12 and IFN-gamma would be related to the induction of tissue damage. Our data indicate that the protective TH1 immune response has a different expression according to the host-parasite relationship, and that the factors controlling the response are of primary importance to determine the quali- and quantitative expression of IL-12/NK/IFN-gamma as well as their involvement in resistance and tissue damage.

Trypanosoma cruzi: T cell subpopulations in the Peyer's patches of BALB/c infected mice.

The changes in the T cell subsets of the Peyer's patches and the thymus were analyzed in BALB/c mice infected with Trypanosoma cruzi, Tulahuén strain. During the acute stage of the infection both lymphoid organs drastically reduced their cellularity. This was mainly due to the decrease in the immature CD4+CD8+ T cell population in the thymus and in both T and B cells in the Peyer's patches. In the acute infection, few Peyer's patches were found and the histological studies revealed a depletion of the thymic-dependent areas, paralleling the decreased number of cells expressing CD4 and alpha beta T cell receptor. After 14 weeks, in the late stage of the infection, the cellularity and the levels of the T cell subsets studied returned to values similar to those of noninfected mice.

Release of reactive oxygen species by phagocytic cells in response to live parasites in mice infected with Trypanosoma cruzi.

The release of reactive oxygen intermediates (ROI), mediators of inflammatory reactions, was evaluated in murine Trypanosoma cruzi infection. In acutely infected BALB/c mice, spleen cells were stimulated, either with epimastigote or trypomastigote forms of the parasite, and the effect was enhanced by serum from infected mice. Only opsonized parasites triggered the release of ROI by normal mouse cells and this response was several times lower than in infected mice. This seems to indicate that cells from acutely infected mice reacted to T. cruzi and that neither parasites nor serum factors blocked the release of ROI. During the acute stage of the infection, both the parasitemia and the release of ROI by spleen cells were higher in BALB/c than in C3H mice (ROI generated in response to a phagocytic stimulation was 12 and 3 times the normal levels, respectively). In addition, in BALB/c mice infected with different numbers of parasites, the production of ROI was related to parasitemia. On the other hand, during the chronic stage of the infection, the inflammatory reaction in myocardium was greater in C3H than in BALB/c mice, and the increase in ROI production was 30% and 100% above the normal levels in BALB/c and C3H mice, respectively. This suggests that the increased ROI production paralleled the parasite burden in the acute phase, and could be related to inflammatory processes after the control of the parasitemia.

[Superantigens: a particular interaction between microorganisms and the immune system]. / Superantígenos: una particular interacción entre microorganismos y el sistema inmune.

The discovery of the superantigens (SAgs) offered new insights on the interaction between microorganisms and the host immune system. Associated to Major Histocompatibility Complex (MHC) class II molecules, SAgs bind to the variable domain of the beta chain (V beta) of the TCR alpha beta engaged in the family specificity of lymphocytes. Therefore, these molecules are able to activate a high number of T lymphocytes as well as surface MHC class II bearing cells, leading to an overriding release of cytokines and inflammatory mediators, which have been related to their toxic effects. Endogenous SAgs are encoded by murine tumor proviruses (Mtv) which are integrated in the genome of mice. Bacteria and viruses produce exogenous SAgs and those related to food poisoning have been widely studied. The presence of parasite SAgs is still unclear and further studies are required to establish their existence and effects on the corresponding infections.

T cell receptor V beta repertoire in the thymus and spleen of mice infected with Trypanosoma cruzi.

The T cell receptor (TCR) V beta repertoire was studied in BALB/c, CBA/HJ, and CBA/J mice experimentally infected with Trypanosoma cruzi. The percentage of expression of 14 V beta chains of the variable domain of the TCR in the thymus and spleen was evaluated. In the thymus of acutely infected with BALB/c and CBA/HJ mice there was an increase in the expression of positively selected V beta families. These changes in the V beta chains usage in the thymus paralleled the enrichment of CD4+ and CD8+ single-positive T cells. During the acute infection, several changes were observed in the peripheral expression of V beta families, such as of V beta 6 in BALB/c (a 36% increase in CD8+ T cells of the corresponding levels of V beta), of V beta 8 in CBA/HJ (a 37% decrease in CD8+ cells), and of V beta chains 8 and 14 in CBA/J mice (V beta 14+CD4+ cells increased 19%, and V beta 8 expression decreased 19 and 33% in CD4+ and CD8+ cells, respectively). In chronically infected BALB/c and CBA/HJ mice, no change in the V beta families was observed, neither in the thymus nor in the spleen. In acutely infected mice, the alterations of the peripheral expression of positively selected V beta families could be due to the stimulation by T. cruzi antigens and/or cytokines; the homeostatic mechanism/s that maintains the selection of the TCR V beta repertoire did not seem to be severely affected during the infections.