Human anti-porcine gammadelta T-cell xenoreactivity is inhibited by human FasL expression on porcine endothelial cells

BACKGROUND

The role of gammadelta T cells during an immune response is still elusive and has been proposed to play a first line of defense along with other cells of the innate immune system, such as macrophages and natural killer cells, before alphabeta T-cell activation occurs. Innate cellular immune response plays a major role in xenograft rejection. We investigated the response of human gammadelta T cells to unmodified and human FasL (hFasL)-expressing xenogenic porcine endothelial cells.

METHODS

A 51Cr release assay was used to study the xenoreactivity of human gammadelta T-cell clones against porcine endothelial cells. Stable transfectants of porcine endothelial cells expressing hFasL were established and analyzed for their effectiveness in controlling this response.

RESULTS

Of the gammadelta T-cell clones tested, 38.9% were cytotoxic for porcine endothelial target cells. This cytotoxic response of human gammadelta T-cell clones was significantly inhibited by a monoclonal antibody against human CD3. Incubation of gammadelta T-cell clones with concanamycin A, an inhibitor of the perforin/granzyme B pathway, caused inhibition of lysis of porcine endothelial cells. Inhibition was not observed upon incubation with either anti-FasL or anti-tumor necrosis factor-alpha monoclonal antibodies. Expression of hFasL on porcine endothelial cells significantly reduced lysis by human gammadelta T cells.

CONCLUSION

These results imply that human gammadelta T cells may represent an important obstacle to xenotransplantation. Specific strategies targeted at this subset of T cells could be important in controlling innate cellular response to xenografts and facilitate graft survival.

Evidence that the proliferation stage of micropropagation procedure is determinant in the expression of banana streak virus integrated into the genome of the FHIA 21 hybrid (Musa AAAB)

Banana streak virus (BSV) is causing increasing concern in almost every producing area of banana and plantain (Musa spp.) worldwide. This situation appeared partially linked to some breeding lines and micropropagated hybrids. A complete BSV sequence integrated into the genome of a triploid plantain has been recently characterised and it has been hypothesised that it could give rise to infectious virus via recombination. In this study, we evaluated the effect of a routine micropropagation procedure on the expression of BSV in the FHIA 21 tetraploid hybrid. The widespread presence of integrated sequences and the absence of episomal BSV in thirty FHIA 21 "mother plants" selected for micropropagation were first confirmed by specific PCR and IC-PCR tests. The proliferation stage of the procedure, characterised by an intensive production of neoformed buds, appeared determinant in BSV expression whereas the rooting and acclimatisation stages had little or no effect. The duration in culture and the way of subdividing the clumps of proliferation influenced greatly the percentage of episomal BSV infections, reaching 58% of infected micropropagated lines after six in vitro subcultures. These data suggest that the expression of episomal BSV observed during the in vitro procedure is correlated with the presence of an integrated form.

Arsenite induces DNA-protein crosslinks and cytokeratin expression in the WRL-68 human hepatic cell line

The induction of DNA-protein crosslinks (DPC) has been proposed as an indicator of early biological effects due to the fact that known or suspected carcinogens induce an increased proportion of proteins tightly bound to DNA. Arsenic, a human carcinogen, is reduced and methylated mainly in liver cells generating a number of intermediate reactive forms which could lead to the formation of DNA-protein crosslinks. The induction of DPC by arsenite [As(III)] was investigated in the WRL-68 human hepatic cell line, testing the possibility that cytokeratins or cytokeratin-like proteins, due to their high content of SH groups, could participate in DPC. The formation and decay of DPC was dose-related. Arsenite was the only intracellular species present since no methylated As forms could be detected. Thus, DPC can be attributed to the presence of arsenite, an important species present in liver during As exposure, whose permanence in the tissue would depend on the methylation rate of the organism. Several cytokeratins were identified by immunoblotting among the proteins crosslinked with DNA, including cytokeratin 18 (CK18), a specific liver intermediate filament. An augmented presence of CK18 was detected in treated cultures by immunoblotting of total protein PAGE. In liver cells cytokeratin synthesis is tightly correlated with differentiation programs, thus arsenite could not only be damaging DNA but also modifying differentiation patterns in this tissue.

Implication of soluble and membrane HLA class I and serum IL-10 in liver graft acceptance

Membrane HLA class-I expression (mHLA-I), soluble HLA class-I antigens (sHLA-I) and interleukin (IL)-10 are different factors implicated in the special acceptance of liver allograft. In this study, pre- and post-operative levels of mHLA-I in peripheral blood lymphocytes (PBL) and serum sHLA-I were analyzed in 86 liver transplants, immunosuppressed with Cyclosporine-A, methylprednisolone and azathioprine, and classified into acute-rejection (AR, n = 28) and non-acute-rejection (NAR, n = 58) groups. Serum IL-10 was studied in 47 recipients (AR-group, n = 16 and NAR-group, n = 31). Pre-transplant values of mHLA-I and sHLA-I showed a bimodal distribution (high/low) in NAR-recipients, but in AR-patients were mainly included in the low expression/secretion zone (mHLA-I, p < 0.02 and sHLA-I, p < 0.05). Consequently, average pre-transplant mHLA-I (868 +/- 109 versus 998 +/- 123, p < 0.05) and sHLA-I (1.3 +/- 0.4 versus 2.02 +/- 0.7 microg/ml, p < 0.01) was lower in the AR- than in the NAR-group. After transplant both parameters decreased in the NAR-group, but increased in AR-recipients previous to and on rejection diagnosis day. Additionally, serum IL-10 levels were significantly higher (p < 0.01) in the NAR than in the AR-group during the first 24 h post-transplant. In conclusion, low pre-transplant mHLA-I and sHLA-I levels pre-dispose liver recipients to acute rejection, whereas early post-transplant increases of serum IL-10 appear to be related to a good liver allograft acceptance.

[Myotonic dystrophy: DNA instability in monozygotic twins]

INTRODUCTION

Myotonic dystrophy is an autosomal dominant hereditary disorder with variable expression, associated with expansion of the CTG triplet on the gene which codifies myotonia situated on chromosome 19q. We present an unusual case of myotonic dystrophy in a pair of monozygotic twin sisters, determination of CTG expansion in lymphocytes of members of their family and in their father's spermatozoids.

CLINICAL CASE

The patients presented the phenomenon of anticipation of paternal transmission with an expansion of triplet CTG of lymphocyte DNA in a range of 300-1,400 identical repetitions in both. DNA of the paternal lymphocytes and spermatozoids showed a similar expansion of 75 repetitions.

CONCLUSIONS

CTG expansion is not due to previous expansion of DNA in the paternal gametes but to instability of DNA in the cellular mitoses following formation of the zygote.

Protective effect of N-acetyl-L-cysteine on the renal failure induced by inferior vena cava occlusion

BACKGROUND

Renal ischemia is produced during orthotopic liver transplantation when the inferior vena cava is clamped above the renal veins (inferior vena cava occlusion [IVCO]), and it often leads to postoperative renal failure. Although free radicals and nitric oxide (NO) have been implicated in the pathogenesis of ischemic renal failure, the effect of free radical scavengers in this model is unknown.

METHODS

The effects of N-acetyl-L-cysteine (NAC), a free radical scavenger, on the acute renal failure that follows IVCO were evaluated in pentobarbital-anesthetized dogs. The effect of NO synthesis inhibition with NG-nitro-L-arginine methyl ester (NAME) was also studied. Renal vascular endothelial function was tested by infusing acetylcholine (Ach) into the renal artery before the ischemia and during reperfusion.

RESULTS

Renal failure developed during IVCO and persisted during reperfusion in all groups. However, in NAC-pretreated dogs, the glomerular filtration rate recovered progressively, reaching 31% of basal preischemic values 150 min after reperfusion. During reperfusion, fractional excretion of sodium increased above preischemic values only in the control group, which indicates a beneficial effect of NAC and NAME on the tubular dysfunction observed during reperfusion. The renal response to Ach was abolished in control dogs and in animals given NAME during reperfusion, which indicates endothelial dysfunction. However, in NAC-pretreated dogs, the renal response to Ach was preserved during reperfusion.

CONCLUSIONS

These results demonstrate that NAC ameliorates the renal failure and renal endothelial dysfunction induced by IVCO. This protective effect was abolished by NAME, which suggests that NO is involved in the beneficial effects of NAC. These data also suggest that the use of NAC could be beneficial in ameliorating the acute renal failure observed after orthotopic liver transplantation.

[Merkel cell carcinoma. Report of 4 cases]

We report four cases of Merkel cell carcinoma, a rare cutaneous neuroendocrine neoplasm with a high malignant potential. The first patient is a 90 years old male presenting with a tumor in the left superior eyelid. Surgical excision was the only treatment and seven months later, a local and regional tumoral relapse caused the death of this patient. The second patient is a 83 years old female with a tumor in her left ear. She was treated surgically and with radiotherapy, being free of disease after five years of follow up. The third patient is a 45 years old male with a tumor in the left forearm. Treatment was surgical excision of the primary tumor and axillary lymph nodes. He received post operative radiotherapy and is free of disease after three years of follow up. The last case is a 76 years old male, who was subjected only to an excisional biopsy of a lesion located in the left knee. He had a tumor relapse with inguinal and crural lymph node involvement that caused his death 12 months later.

Disruption of microtubule assembly and spindle formation as a mechanism for the induction of aneuploid cells by sodium arsenite and vanadium pentoxide

Arsenic and vanadium are important environmental and industrial pollutants. Due to their widespread occurrence and potential genotoxicity, we studied the aneuploidy-inducing effects of these elements in cultured human lymphocytes using a variety of techniques including fluorescence in situ hybridization (FISH) with DNA probes for chromosomes 1 and 7, immunostaining of the lymphocyte spindle apparatus, and an in vitro assay measuring the polymerization and depolymerization of tubulin. Dose-related increases in hyperdiploidy were seen in lymphocyte cultures treated with sodium arsenite (NaAsO2) or vanadium pentoxide (V2O5) over concentrations ranging from 0.001 to 0.1 microM. NaAsO2-treated cells from different donors exhibited similar hyperdiploid frequencies, whereas substantial inter-individual variability was seen in the V2O5-treated cells. Examination of the spindle apparatus using an anti-beta-tubulin antibody indicated that these compounds might disrupt spindle formation by interacting with microtubules. Additional in vitro assays using purified tubulin indicated that both compounds inhibited microtubule assembly and induced tubulin depolymerization. These results indicate that in vitro exposure to both NaAsO2 and V2O5 can induce aneuploidy in human lymphocytes, and that this effect may occur through a disruption of microtubule function.

[Quality of life of cirrhotic patients before and after liver transplantation]

In this study we assessed the quality of life of a group of cirrhotic patients who underwent liver transplant using a psychological test to evaluate family relations, work activity, emotional state and social relations. The quantification of hospital dependence and degree of fitness for work, before and after the transplant were also analyzed. 32 patients were included in the study with the diagnosis of hepatic cirrhosis and minimum post-transplant follow-up of 6 months. The average age of the study population was 44.8 +/- 10.5 years; there were 23 males and 9 females, with an average follow-up of 15 months. The psychological test used was the Quality of Life Scale (QLS), which consists of 21 items, each scoring from 1 to 6 points. The questionnaire was completed before the transplant by all the patients, and after the transplant by 32 patients at 6 months, 20 at 12 months and 12 at 24 months. Hospital dependence was evaluated by number of admissions and number of days per admission. Lastly, we compare the rate of unfitness for work before the transplant and at one and two years after the transplant. The QLS test showed a post-transplant improvement in the 4 aspects assessed, specially in the personal aspects (emotions and family) (p < 0.001). Hospital dependence following pre-transplant situation (p < 0.01). Finally, the post-transplant percentage of unfitness for work decreased with time, reaching significant differences 2 years after the liver transplant (p < 0.05).

Hepatic artery complications after liver transplantation

We present the arterial complications arising from 100 orthotopic liver transplants (OLT) carried out in 87 consecutive patients. Mean patient age was 42.5 +/- 12.8 years (7-63). There was a predominance of male patients (67%). The most common indications were hepatic cirrhosis (53%) and severe acute hepatitis insufficiency (14%). The donor liver presented 29 arterial malformations, mainly a left hepatic artery arising from the left gastric artery, either as a single or associated anomaly. Only six arterial complications appeared in 4 of the 87 patients. Of these six, four corresponded to arterial thrombosis, and the remaining two to arterial stenosis and a ruptured mycotic aortic aneurysm. Two of the 4 patients had a double arterial complication (one had arterial thrombosis in 2 of the 3 grafts, and the other presented arterial thrombosis and aortic rupture). No arterial complications were related to arterial anomalies in the donor liver. Three of the 4 patients died from the complication. The 1-year actuarial survival rate in our series is 77.5%. In conclusion, arterial complications are infrequent in our series (6%) but do carry a high mortality rate (75%).

[Adherence formation following different forms of treatment of peritoneal lesions]

The authors analyse the adhesion forming capacity of various forms of treating a peritoneal lesion. There were four groups each of 10 rats, all receiving the same peritoneal lesion. The control group did not receive any treatment for this injury; in the remaining three, the peritoneal lesion was treated with electrocoagulation, mechanical suture or manual suture. The animals were killed after 30 days, and adhesions quantified using an original method of the authors, which evaluates number, thickness, tenacity, vascularisation and site. Electrocoagulation significantly generated the smallest number of adhesions. The application of suture stimulated the formation of adhesions to a larger extent, manual suture more so than the mechanical method.

Pathogenic and free-living amoebae isolated from swimming pools and physiotherapy tubs in Mexico

A protozoological survey was done to isolate free-living amoebae from swimming pools and physiotherapy tubs in Mexico City. Amoebae were isolated by culture in nonnutritive agar medium combined with Escherichia coli. Identification of the isolates was done by morphology using specialized taxonomic keys and by isoelectric focusing of total proteins and isoenzymes in agarose. Pathogenicity of the isolates was determined in 3-week-old mice by intracerebral and intranasal inoculations. Statistical tools were used to determine the existence of significant differences on the incidence and diversity of the isolates in relation to the two types of water bodies analyzed. Water and environmental temperatures, pH, and chloride concentrations were determined at each sampling site. Twenty-nine amoebic strains from eight genera were isolated. Most frequently found were specimens of the genera (Acanthamoeba (with four pathogenic strains), Vahlkampfia, Hartmannella, and Naegleria. Amoebae were isolated more frequently in spring and summer, and could not be recovered from pools with chloride levels of 5.31 mg/ml or more. This survey demonstrates that chloride concentrations commonly used in recreative pools and therapy tubs are not sufficient to eliminate viable cysts of most free-living amoebae. Significantly higher numbers of isolates were retrieved from the pools than from the tubs.

Vagal system involvement in changes in small bowel motility during restraint stress: an experimental study in the dog

Changes in small intestinal motility were studied during restraint stress in fasting animals and after food; the involvement of the vagal system in the pathophysiology of these changes was assessed. Small intestinal motility was recorded in 40 dogs using electromyography with monopolar electrodes and manometry with submucosal microballoons. Twenty animals underwent bilateral truncal vagotomy. Stress increased intestinal motility (percentage of slow waves followed by action potentials in 1 min), both in fasting conditions (P < 0.001) and post-prandially (P < 0.001). It also completely abolished the migrating motor complex-interdigestive myoelectric complex periodicity characteristic of the normal fasting pattern. In dogs subjected to vagotomy, restraint stress increased motility during fasting (P < 0.001) but decreased it after feeding (P < 0.01). Restraint stress thus increases small intestinal motility, both during fasting and after food. The vagal system is partially involved in this hypermotility response.

[Biliary complications in the follow-up of 54 orthotopic liver transplant patients]

We analyze the biliary tract complications after 54 orthotopic liver transplantation in 49 patients during a 2-year period. Biliary tract reconstruction was achieved by a choledochocholedochostomy over a t-tube in 47 cases and by a Roux-en-Y choledochojejunostomy in 7 cases (2 sclerosing cholangitis, 4 retransplants and 1 secondary biliary cirrhosis). The t-tube was removed between the 12-16 postoperative week in all cases except in two patients (2 and 3 postoperative week).

RESULTS

There was not intraoperative mortality. During the first postoperative month 8 patients died (16.3%) none of them because a biliary complications. The one year actuarial survival of patients was 74.6%. During the (first three postoperative months) we observed 5 patients with a bile leak (biloma). In 3 cases the ultrasonographic drainage was effective and in two cases a surgical drainage was necessary. After the 3rd postoperative month, four patients developed a biliary peritonitis after t-tube removal and a reoperation was required in all cases. Finally, 1 patient suffered a hilar biloma cavity due to hepatic artery thrombosis. We stress the low incidence of reoperations due to early biliary complications (2 cases) and the high incidence of biliary peritonitis after t-tube removal.

[Role of the vagal system in changes in small intestinal motility induced by psychological stress. Experimental study on dogs]

The objectives of the present study were: 1) to describe the modifications in motility of the small intestine in response to situations of psychic stress during fasting and postprandial periods. 2) To analyse the possible involvement of the vagal system in these modifications. For this we used a total of 40 dogs. The motility of the small intestine was recorded using electromyography techniques (monopolar electrodes) and manometric techniques (submucous microballons). The stress stimulus consisted in the complete body immobilization of the animal in plaster. We show that stress induced a significant increase in the intestinal motility index (percentage of show waves followed by the action potential) in the three locations of the intestine studied (duodenum, angle of Treitz and proximal part of the jejunum) during the fasting (p less than 0.001) and postprandial periods (p less than 0.001). Finally, we demonstrate that vagotomy prevents the effect of hypermotility causes by the psychic stress. We can conclude that psychic stress does indeed modify the normal motility of the small intestine, both in the fasting and postprandial periods, and the vagus is implicated in this hypermotility response.

[Orthotopic liver transplantation in the Budd-Chiari syndrome. A case report]

A patient with Budd-Chiari's syndrome of idiopathic etiology, received an emergency liver transplant because of terminal liver insufficiency, including encephalopathy, functional renal failure and progressive deterioration of coagulation. The diagnosis was confirmed by biopsy. The transplanted liver was from a patient with the same blood group and the preserving solution was Euro Collins. No veno-venous by-pass was necessary during operation. Anticoagulation was started from the immediate post-operative stage, as well as triple immunosuppressive therapy with azathioprine, cyclosporine and corticoids. The patient is asymptomatic twenty months after transplantation.

[Intra-arterial infusion with urokinase for embolism of the superior mesenteric artery]

We report the case of a 65 year old male patient in whom an early diagnosis of embolism of the superior mesenteric artery was made and successfully treated by an intraarterial infusion of urokinase.

Pathogenic and free-living protozoa cultured from the nasopharyngeal and oral regions of dental patients

Protozoa of nose, mouth, and pharynx of 30 randomly chosen female caries patients at an odontological clinic of the National Autonomous University of Mexico, were surveyed by culture from swabs. Culture tubes of swabs from each patient were observed every other day during 5 weeks. Pathogenic protozoa found included Entamoeba histolytica Schaudinn, 1903; Naegleria fowleri Carter, 1970; Acanthamoeba castelanii Douglas, 1930; Acanthamoeba culbertsoni Singh & Das, 1970; and Balantidium coli (Malmsten, 1857) Stein, 1862. This isolation of pathogens suggests that healthy patients may be healthy carriers of cysts of protozoa, mainly amoebae, responsible for several diseases, including primary amoebic meningoencephalitis. Small pathogenic free-living amoebae have not been isolated before from females in Mexico. Many species of free-living protozoa were also cultured from swabs from the patients.

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while those specimens of the genera Amoeba, Entamoeba, Thecamoeba, and Vanella were recovered only in their trophic stage during this study. Amoebae were concentrated through filtration procedures and subsequently cultured in different culture media. Nonpathogenic amoebae also isolated by culture included: Amoeba proteus (Pallas) Leidy, Amoeba striata Penard, Paratetramitus jugosus Page, Acanthamoeba astronyxis Ray and Hayes, Vahlkampfia avara Page, Vahlkampfia inornata Page, Thecamoeba verrucosa Ehrenberg, and Vanella mira Schaeffer. Trophozoites of Entamoeba gingivalis Gros, were also recovered, both directly and by culture. Most commonly found were amoebae of the species Naegleria gruberi Schardinger (59.02%), N. fowleri (16.77%), and A. castellanii (7.64%). Least-frequently found amoebae belonged to the species Thecamoeba verrucosa (0.12%). All isolated strains of N. fowleri and A. castellanii were thermophilic at 45 and 40 degrees C, respectively, and also pathogenic when inoculated into white mice. More populated by amoebae were those swimming pools of the indoor type with an inner side garden. It was also shown that the free residual chloride values of 0.50 to 1.5 mg/liter, ordinarily used in pool waters, are not adequate for elimination of amoebae.