Boron neutron capture therapy (BNCT) for liver metastasis in an experimental model: dose–response at five-week follow-up based on retrospective dose assessment in individual rats

Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. Employing an experimental model of liver metastases in rats, we recently demonstrated that BNCT mediated by boronophenylalanine (BPA-BNCT) at 13 Gy prescribed to tumor is therapeutically useful at 3-week follow-up. The aim of the present study was to evaluate dose–response at 5-week follow-up, based on retrospective dose assessment in individual rats. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA-BNCT (n = 19), Beam only (n = 8) and Sham (n = 7) (matched manipulation, no treatment). For each rat, neutron flux was measured in situ and boron content was measured in a pre-irradiation blood sample for retrospective individual dose assessment. For statistical analysis (ANOVA), individual data for the BPA-BNCT group were pooled according to absorbed tumor dose, BPA-BNCT I: 4.5–8.9 Gy and BPA-BNCT II: 9.2–16 Gy. At 5 weeks post-irradiation, the tumor surface area post-treatment/pre-treatment ratio was 12.2 ± 6.6 for Sham, 7.8 ± 4.1 for Beam only, 4.4 ± 5.6 for BPA-BNCT I and 0.45 ± 0.20 for BPA-BNCT II; tumor nodule weight was 750 ± 480 mg for Sham, 960 ± 620 mg for Beam only, 380 ± 720 mg for BPA-BNCT I and 7.3 ± 5.9 mg for BPA-BNCT II. The BPA-BNCT II group exhibited statistically significant tumor control with no contributory liver toxicity. Potential threshold doses for tumor response and significant tumor control were established at 6.1 and 9.2 Gy, respectively.

Boron neutron capture therapy (BNCT) for liver metastasis: therapeutic efficacy in an experimental model

Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. The present study evaluates tumor control and potential radiotoxicity of BNCT in an experimental model of liver metastasis. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA-BNCT, boronophenylalanine (BPA) + neutron irradiation; Beam only, neutron irradiation; Sham, matched manipulation. The total absorbed dose administered with BPA-BNCT was 13 ± 3 Gy in tumor and 9 ± 2 Gy in healthy liver. Three weeks post-treatment, the tumor surface area post-treatment/pre-treatment ratio was 0.46 ± 0.20 for BPA-BNCT, 2.7 ± 1.8 for Beam only and 4.5 ± 3.1 for Sham. The pre-treatment tumor nodule mass of 48 ± 19 mg fell significantly to 19 ± 16 mg for BPA-BNCT, but rose significantly to 140 ± 106 mg for Beam only and to 346 ± 302 mg for Sham. For both end points, the differences between the BPA-BNCT group and each of the other groups were statistically significant (ANOVA). No clinical, macroscopic or histological normal liver radiotoxicity was observed. It is concluded that BPA-BNCT induced a significant remission of experimental colorectal tumor nodules in liver with no contributory liver toxicity.

Boron neutron capture therapy (BNCT) for the treatment of liver metastases: biodistribution studies of boron compounds in an experimental model

We previously demonstrated the therapeutic efficacy of different boron neutron capture therapy (BNCT) protocols in an experimental model of oral cancer. BNCT is based on the selective accumulation of (10)B carriers in a tumor followed by neutron irradiation. Within the context of exploring the potential therapeutic efficacy of BNCT for the treatment of liver metastases, the aim of the present study was to perform boron biodistribution studies in an experimental model of liver metastases in rats. Different boron compounds and administration conditions were assayed to determine which administration protocols would potentially be therapeutically useful in in vivo BNCT studies at the RA-3 nuclear reactor. A total of 70 BDIX rats were inoculated in the liver with syngeneic colon cancer cells DHD/K12/TRb to induce the development of subcapsular tumor nodules. Fourteen days post-inoculation, the animals were used for biodistribution studies. We evaluated a total of 11 administration protocols for the boron compounds boronophenylalanine (BPA) and GB-10 (Na(2)(10)B(10)H(10)), alone or combined at different dose levels and employing different administration routes. Tumor, normal tissue, and blood samples were processed for boron measurement by atomic emission spectroscopy. Six protocols proved potentially useful for BNCT studies in terms of absolute boron concentration in tumor and preferential uptake of boron by tumor tissue. Boron concentration values in tumor and normal tissues in the liver metastases model show it would be feasible to reach therapeutic BNCT doses in tumor without exceeding radiotolerance in normal tissue at the thermal neutron facility at RA-3.

Apolipoprotein A5-1131T>C polymorphism, but not APOE genotypes, increases susceptibility for dyslipidemia in children and adolescents

Apolipoprotein A5 (APOA5) and apolipoprotein E (APOE) play important roles in the metabolism of cholesterol and triglycerides. The aim of this study was to determine the allelic and genotypic distributions of the APOA5-1131T>C (rs 662799) and the APOE HhaI polymorphisms and to identify the association of both individual and combined APOA5-APOE genetic variants and the risk for dyslipidemia in children and adolescents. We genotyped 53 dyslipidemic and 77 normolipidemic individuals. The total cholesterol, triglycerides and HDL cholesterol were determined enzymatically. For APOA5 polymorphism, the presence of the allele C confers an individual risk for dyslipidemia (OR = 2.38, 95% CI = 1.15-4.89; P = 0.018). No significant differences were observed for lipid parameters among the APOA5 groups, except for a higher value of HDLc (P = 0.024) in C-carriers. The allelic and genotypic frequencies of APOE polymorphism were similar between groups and did not increase the susceptibility for dyslipidemia. None of the combined APOA5-APOE polymorphisms increased risk for dyslipidemia. We demonstrated an association between APOA5-1131T>C polymorphism and dyslipidemia in children and adolescents. This finding may be useful to guide new studies with genetic markers down a path toward a better characterization of the genetic risk factors for dyslipidemia and atherosclerotic diseases.

Effect of Boron Neutron Capture Therapy (BNCT) on normal liver regeneration: Towards a novel therapy for liver metastases

PURPOSE

The effect of Boron Neutron Capture Therapy (BNCT) on normal liver regeneration was examined in the Wistar rat. The model used is clinically relevant to a novel technique proposed for the treatment of multifocal non-resectable liver metastases in man. The success of the technique also requires that BNCT should not significantly impair regeneration of normal hepatocytes.

MATERIALS AND METHODS

The effect of therapeutic doses of boronophenylalanine (BPA), GB-10 (Na(2)(10)B(10)H(10)) and (GB-10 + BPA) and of BNCT mediated by these boron delivery agents on normal liver regeneration and liver function in the Wistar rat was examined using partial hepatectomy as the regenerative stimulus. The end-points evaluated were body weight, liver weight/body weight ratio, DNA synthesis in terms of 5-bromo-2'-deoxyuridine incorporation, hemogram, kidney function in terms of blood urea nitrogen and creatinine levels, liver function in terms of serum albumin, total and direct bilirubin and liver enzymes (alanine transaminase and aspartate transaminase) and liver histology/architecture.

RESULTS

BNCT mediated by BPA, GB-10 or (GB-10 + BPA) did not cause alterations in the outcome of normal liver regeneration, regenerated liver function/proliferation or histology/architecture.

CONCLUSION

The BNCT protocols, at the physical doses selected, did not impair the capacity of normal liver hepatocytes to regenerate.

First Report of Dry Rot Caused by Fusarium oxysporum on Rose (Rosa spp.) in Brazil

Roses are a high-value niche crop in the higher altitudes of northeastern Brazil. From July of 2007 and throughout 2008, severe stem rot and wilting of rose seedlings were observed in commercial fields in the São Benedito District, Ceará State, Brazil. Although economic losses due to the disease are unknown, it poses a threat to the growing rose industry in that region. Symptoms included leaf yellowing and abscission followed by plant collapse. Symptoms appeared earlier when grafted seedlings were produced during periods of high relative humidity (80 to 98%) and warm temperatures (20 to 31°C). In the laboratory, symptomatic seedlings were rinsed with distilled water, surface sterilized with 0.5% NaOCl, and incubated on PDA at 26 ± 2°C. Fusarium oxysporum was consistently isolated from infected scions and rootstocks. Identification of F. oxysporum was based on colony and conidia morphology obtained from single-spore colonies. Five 4-week-old rose ('Carola') seedlings were inoculated with a culture of fungus by spraying the needle-wounded scion with a spore suspension (1 × 10⁵ CFU/ml). The spore suspension was obtained from a 1-week-old PDA culture incubated at 26 ± 2°C. Control seedlings were sprayed with sterile water. Inoculated seedlings were incubated for the first 48 h in a saturated humidity chamber. After 20 days at room temperature, the scion tissue of inoculated seedlings turned necrotic. Two symptomatic seedlings were placed in a saturated humidity chamber for 24 h to determine if fungal sporulation could be observed on the surface of the tissue. After 5 to 7 days, a white mycelium was observed over the necrotic tissue. Seedlings sprayed with sterile water remained symptomless. F. oxysporum was reisolated from symptomatic tissue. An isolate of F. oxyporum (No. 1484) was deposited in the Mycology Collection of Lavras (Minas Gerais State, Brazil). To our knowledge, this is the first report of F. oxysporum causing a disease on rose seedlings in Brazil.

First Report of a Bacterial Leaf and Fruit Spot of Cashew Nut (Anacardium occidentale) Caused by Xanthomonas campestris pv. mangiferaeindicae in Brazil

In 2003 and 2004, leaves and young fruits of cashew nut plants showing an undescribed disease symptom were observed on plants of an early-dwarf clone in a commercial orchard in Ceará and Piauí states in northeastern Brazil. Initial symptoms consisted of angular, water-soaked, dark-to-black spots on the leaf and at the mid-rib vein surrounding the leaf veins. Eventually, lesions also extended from the mid-rib to the secondary veins, delineating the vein system of the leaf. In young, green fruits, symptoms were large, dark, oily spots surrounded by conspicuous water-soaked areas. A yellow-pigmented colony was consistently recovered from the lesions on nutrient yeast-extract dextrose agar medium (3 g of meat extract, 5 g of peptone, 10 g of dextrose, 5 g of yeast extract, and 18 g of agar per liter). Physiological tests revealed colonies that were gram negative, strictly aerobic, oxidase negative, catalase positive, lacking fluorescent pigmentation on King's B medium, urea hydrolase negative, and able to grow on yeast dextrose calcium carbonate medium yielding yellow colonies. These tests indicated that the bacterium belonged to the genus Xanthomonas. PCR amplification of bacterial DNA using RST2 (1) and Xcv3R (3) primers resulted in identical band patterns to mango isolates Xanthomonas campestris pv. mangiferaeindicae. Restriction fragment length polymorphism analysis of PCR-amplified products of six isolates of X. campestris pv. mangiferaeindicae was conducted with HaeIII and showed different profile patterns on agarose gel, indicating genetic variability among these isolates. Pathogenicity was demonstrated by gently piercing and misting cashew leaves with a bacterial suspension adjusted to 10⁶ CFU/ml. Inoculated plants were enclosed in plastic bags for 24 h and then incubated in a greenhouse (29 ± 1°C). Control plants were misted with sterile water and treated the same way. After 8 days, foliar symptoms similar to those observed in the field developed on all inoculated plants, and reisolated bacteria were characterized and found to be X. campestris pv. mangiferaeindicae. Control plants remained symptomless. To our knowledge, this is the first description of commercially grown cashew plants as host to X. campestris pv. mangiferaeindicae in Brazil. This disease may pose a serious problem to the cashew-growing industry in Brazil. This bacterial pathogen has been reported on mangoes (Mangifera indica) and cashew in India (2) under the former name of Pseudomonas mangiferae-indicae. References: (1) R. P. Leite, Jr. et al. Appl. Environ. Microbiol. 60:1068, 1994. (2) M. K. Patel et al. Curr. Sci. 17:189, 1948. (3) L. C. Trindade et al. Summa Phytopathol. 33:16, 2007.

A novel melon flexivirus transmitted by whitefly

In recent years, a viral disease on melon plants has become a serious problem in Brazil. Symptoms were principally yellowing and mottling on older leaves. Long filamentous virus particles, resembling those of carlaviruses, were seen in symptomatic leaves. In this study, the 3' terminal region of the virus genome isolated from an infected plant, including the last two ORFs, was cloned and sequenced. The sequence comprised a polyadenilated tail and two ORFs, one exhibiting similarity to potexvirus and carlavirus coat protein gene and the second to a carlavirus protein with potential nucleic acid-binding property. The sequence analysis, the genome organization and the particle morphology indicated that the virus could be classified as a novel whitefly-transmitted flexivirus. The name Melon yellowing-associated virus (MYaV) is tentatively suggested for this virus.

First Report of Black Branch Dieback of Cashew Caused by Lasiodiplodia theobromae in Brazil

Cashew nut (Anacardium occidentale) is one of the most important cash crops of northeastern Brazil. A new disease, named here as black branch dieback, caused by Lasiodiplodia theobromae, was observed causing serious damage on as many as 30% of the trees in some orchards in both coastal and inland semiarid cashew-growing areas of Ceará and Piauí states of Brazil, respectively. The disease symptoms are first observed as darkened, elongated lesions on stems near the branch apexes of herbaceous tissues. Gum exudation is common from lesions, which expand rapidly to affect the entire branch, leading to branch death. Diseased plants were collected, and L. theobromae was consistently isolated from canker tissues. Fresh mycelial disks of the fungus were used for artificial inoculation of healthy plants. Shoots of young cashew plants were inoculated on the apex by inserting a 3-mm plug taken from actively growing colonies on potato dextrose agar into an incision made with a sterile scalpel. Agar plugs with no mycelium were placed into incised plant shoots to serve as controls. Plants were incubated in a greenhouse at 28°C. Symptoms developed within 15 days after inoculation. Artificially inoculated plants showed symptoms similar to those that were naturally infected. L. theobromae was consistently reisolated from inoculated plants. The disease seems to occur throughout the year, but it spreads faster during the rainy season. A contagious disease pattern within the orchard was observed with a decreasing gradient from the orchard perimeter to the interior of the field, suggesting an external source of primary inoculum. All improved dwarf cashew clones were susceptible, but the newly released clone END-189 was the most susceptible. Black branch dieback may reduce tree growth, nut yield, and eventually cause plant death. Plant susceptibility is not related to its age however; only herbaceous tissues are vulnerable to natural infection. A similar disease on floral shoots of cashew caused by L. theobromae was reported by Olunloyo and Esuruoso in Nigeria (1). To our knowledge, this is the first report of L. theobromae causing branch dieback in cashew orchards in Brazil. Reference: (1) O. A. Olunloyo and O. F. Esuruoso. Plant Dis. 59:176, 1975.

Histological and histoquantitative study of the rat parotid gland after Trypanosoma cruzi infection

The present study deals with the morphology of the rat parotid gland and its changes after Trypanosoma cruzi infection. The glands of control and infected animals were analyzed by histologic and histoquantitative methods. After 18 days of infection with T. cruzi, a significant reduction of the density of the volume of the acini and duct system, as well as a significant increase in the amount of connective tissue was noted. In addition, these animals displayed an increase in the number of cells undergoing mitosis. In the 45 day infected rats, there was return to the normal pattern. It is suggested that in the infected animals the decrease in body weight could be responsible for retarded sexual maturity, leading to the lower level of testosterone. It can be assumed that decreased levels of epidermal growth factor (EGF) and neural growth factor (NGF) caused by the lack of testosterone in infected animals also contribute to the atrophy of the parotid gland and to the proliferation of the connective tissue.

Hepatic regeneration in the isolated perfused rat liver followed by liver transplantation

Controlling the S phase of the hepatocyte cell cycle would be of considerable help for stable retroviral foreign gene transfer. The aim of this article is to study hepatocyte regeneration during S phase in isolated, perfused rat liver followed by liver transplantation. Normal livers (G I: n = 7) were perfused with blood from normal rats for 6.1+/-0.3 hours. Regenerating livers (G II; n = 7) obtained 18 hours after partial hepatectomy were perfused for 6.0+/-0.3 hours with blood from rats partially hepatectomized 18 hours before. Regenerating livers (G III; n = 7) obtained 22 hours after partial hepatectomy were perfused for 2.4+/-0.1 hours with blood from normal rats. In the normothermal perfusion system, a bolus of 25 mg of 5-bromo-2'-deoxyuridine (BrdU) was added to the perfusate. Liver biopsies were taken at the end of each experiment. In group II, a biopsy was also taken 1 hour after BrdU introduction. At the end of each experiment, livers were orthotopically transplanted. The percentage of BrdU positive hepatocyte nuclei was 0.2% in G I; 14.8% and 38.4% after 1 hour and 6.1 hours, respectively, in G II; and 46.5% after 2.4 hours in G III. In G I, five rats died at day 1, 5, 6, 7, and 48 and two rats were still alive after 17 months. In G II, all the rats died before day five. In G III, two rats died at day one, one at day six, and four were still alive after 12 months. This study shows that, after 6 hours of normothermal perfusion, organ viability allows successful liver transplantation and that rat hepatocyte regeneration during cell cycle S phase in isolated normothermal conditions progresses in a similar way-quantity and timing-to liver regeneration found in vivo after partial hepatectomy.

Liver function improvement following increased portal blood flow in cirrhotic rats

BACKGROUND/AIMS

Liver microcirculation in cirrhosis is characterized by development of intrahepatic shunts and capillarization of sinusoids secondary to cell necrosis and deposition of new collagen, resulting in both decreased drug elimination and increased vascular resistance with portal hypertension. The aim of this study was to examine the effects of increased portal blood flow on hepatic microcirculation and drug elimination in 13 perfused livers from cirrhotic rats.

METHODS

Intrahepatic resistance was assessed under basal conditions (21.2 +/- 0.3 mL/min) and 1 hour after doubling the flow (41.6 +/- 1.0 mL/min). A multiple indicator dilution technique was used at both flow rates to measure sinusoidal volume, albumin and sucrose extravascular volumes, and cellular water volume. Hepatic elimination of labeled taurocholate and propranolol was also measured, and the recovery of 15-microns microspheres was used to evaluate large intrahepatic shunts.

RESULTS

After doubling the flow, intrahepatic resistance decreased by 31%. Sinusoidal and extravascular volume increased significantly without a change in microsphere recovery. However, there was a marked increase in taurocholate and propranolol elimination by cirrhotic livers. Moreover, during high flow, significant correlations were found between changes in albumin extravascular volume and taurocholate and propranolol elimination.

CONCLUSIONS

Increased portal blood flow in cirrhotic rats induces a decrease in intrahepatic resistance without changes in intrahepatic shunting and improves drug elimination by the liver without deleterious effects on hepatocyte viability.

Portal pumping: a new perspective for treatment of variceal hemorrhage and liver failure in end-stage cirrhosis?

In end-stage cirrhosis complicated by variceal hemorrhage, attempts to reduce portal pressure by treatments such as portosystemic shunts also decrease sinusoidal perfusion and risk impairing liver function. It has been suggested that encouraging portal flow to pass through the cirrhotic liver by mechanical action could cause a decrease in distal (splanchnic) portal pressure on one hand, and improve liver function on the other. The aim of this work was to evaluate the hemodynamic and functional effects of a 30-min pump-driven increase in portal blood flow through the liver of patients with end-stage cirrhosis before the anhepatic phase of liver transplantation. Basel portal flow (800 +/- 270 ml.min-1) was increased two fold (n = 10) or four fold (n = 9). When the flow was doubled, splanchnic portal pressure decreased 17.9 +/- 11.3% (from 31.8 +/- 5.3 to 26.0 +/- 5.8 mmHg, n = 10; p < 0.001); when flow was increased four fold, splanchnic portal pressure decreased 39.2 +/- 15.4% (from 32.8 +/- 5.0 to 19.9 +/- 6.0 mmHg, n = 9; p < 0.001). The comparison of indocyanine green clearance between basal and doubled portal flow demonstrated an increase of 32.1 +/- 26.9% (n = 5; p = 0.053). Histological analysis demonstrated sinusoidal dilatation in three out of ten livers. These results, as well as previous studies using isolated perfused cirrhotic rat or human livers, suggest that portal pumping should be explored as a treatment for certain sclerotherapy-resistant cirrhotic patients, with variceal hemorrhage and liver failure.

Augmentation of portal blood flow improves function of human cirrhotic liver

In cirrhotic livers, the intrahepatic resistance is increased and drug elimination and portal transhepatic flow are decreased. The aim of our work was to study the effect of a twofold increase in portal blood flow during 2 hr on the hemodynamic parameters, drug elimination and hepatic viability in eight isolated perfused human cirrhotic livers. Using an oxygenated recirculating system with independent arterial and portal flows, we perfused livers with Kreb's buffer bicarbonate solution, bovine serum albumin (20 gm.L-1) and human red blood cells (hematocrit 20%). The flow was maintained at a basal level of 0.713 +/- 0.19 L/min for 1 hr and then increased and maintained for 2 hr at twice the basal flow. Portal pressure-portal flow curve slopes were linear (27.04 +/- 21.06 mm Hg.L-1 x min; range = 6.43 to 60.8) and correlated with intrahepatic resistance during the basal-flow period (r = 0.87, p < 0.01). Parameters registered during the basal- and high-flow periods were compared by use of Student's t test: portal pressure increased from 23.5 +/- 7 to 37.3 +/- 16.7 mm Hg (p < 0.05); arterial pressure increased from 80.3 +/- 19 to 103.5 +/- 26 mm Hg (p < 0.005); hepatic artery flow resistance increased 31.9% (from 690.1 +/- 218 to 899.4 +/- 269 mm Hg.L-1 x min; p < 0.005); indocyanine green clearance increased by 28.2% (from 86.0 +/- 58.3 to 109.2 +/- 74.8 ml.min-1 x kg liver-1; p < 0.04). No significant differences were observed in enzyme release, biliary flow (n = 5) and oxygen consumption. Histological examinations demonstrated sinusoidal dilatations in six of eight cases.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ retrovirus-mediated gene transfer into dog liver

Dogs were used as a large animal model to assess the feasibility and safety of a surgical method for gene transfer into hepatocytes in vivo. This method, which we previously described in rats, consists of a partial hepatectomy aimed at inducing liver regeneration, followed by the selective in situ perfusion of the remnant liver parenchyma with a retrovirus preparation. Isolation of the liver was obtained by clamping the afferent and efferent blood vessels, a procedure that prevented retroviral vector dissemination and genetic modification of nonhepatic organs. A helper-free retrovirus vector encoding beta-galactosidase targeted to the nucleus was perfused in the liver of 5 golden retriever dogs. Volumes up to 1,650 ml of fresh or concentrated vector stocks were perfused and the procedure was well tolerated. Gene transfer, observed in 3 of 5 treated dogs when documented on liver biopsy fragments obtained at day 4, involved 0.15-0.6% hepatocytes and persisted at equivalent levels at the time of sacrifice, 6 weeks later. No propagation of the vector to other tissues was detected. These observations suggest that the selective perfusion of the regenerating liver might be considered an alternative to liver transplantation for the treatment of certain severe genetic liver disorders, or for the delivery of a therapeutic protein into the serum.

Augmented portal flow in the isolated perfused cirrhotic rat liver: a haemodynamic and morphological study

1. Isolated perfused cirrhotic rat livers were used to study the effects of an increase in portal perfusion pressure and portal flow on the microcirculation and viability of the hepatocytes. Cirrhosis was induced by CCl4, and Krebs-Ringer bicarbonate buffer solution was used as the perfusate. Portal perfusion pressures were increased incrementally between 25 and 45 cm H2O. The viability of the livers was assessed and histological studies were performed under light and electron microscopy. 2. An increase in portal perfusion pressure induced an increase in hepatic flow in all the experiments (P < 0.05). Hepatic flow was 2.52 ml min-1g-1 of liver (SD 0.67; n = 5) at basal pressure compared with 4.19 ml min-1g-1 of liver (SD 0.93; n = 5) and 5.91 ml min-1g-1 of liver (SD 0.63; n = 5) when pressures were raised to 25 and 45 cmH2O, respectively. Portal perfusion pressure and hepatic flow were correlated (r = 0.908; P < 0.001; n = 30). 3. Production of the enzyme alanine aminotransferase (EC 2.6.1.2) increased significantly from 5.69i.u. ml-1min g-1 of liver (SD 3.62; n = 5) to 23.53i.u. ml-1min g-1 of liver (SD 16.7; n = 5) when the perfusion pressure was raised from baseline to 30 cmH2O. In all the cases the porto-caval gradient of enzyme production was within the normal range. No correlation existed between the release of enzyme and portal perfusion pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Two modes of idiotypic stimulation of T lymphocytes from patients with Chagas' disease: correlations with clinical forms of infection

Patients with chronic Trypanosoma cruzi infections have peripheral auto-anti-idiotype (Id) T cells that proliferate on exposure to immunoaffinity-purified antibodies against T. cruzi epimastigote antigens (EPI). The responses of some patients' (group 1) peripheral blood mononuclear cells (PBMC) to anti-EPI antibodies from sera of patients with the cardiac form of Chagas' disease (Id-C) were inhibited by chloroquine, but responses of other patients' (group 2) PBMC to Id-C were not inhibited. PBMC responses of both group-1 and -2 patients to anti-EPI antibodies from asymptomatic (indeterminate) patients (Id-I) were inhibited by chloroquine, as were their responses to the antigens in EPI. Most patients (69%) in group 1 had indeterminate Chagas' disease, and 100% of the patients in group 2 had severe, cardiac or digestive Chagas' disease. Both the direct (chloroquine-insensitive) and indirect (processed) modes of stimulation by anti-EPI antibodies required adherent cells. In group 2 (direct stimulation), this requirement was met by exogenous IL-1, and neither anti-HLA-DR,DP(DQ) monoclonal antibody (mAb) nor sodium azide inhibited T-cell proliferation. Indirect Id stimulation of group-1 cells by Id-I or Id-C, and group-2 cells by Id-I or EPI, was inhibited by anti-HLA-DR,DP(DQ) mAb or sodium azide, and exogenous IL-1 alone did not support this processed, MHC-mediated T-cell stimulation, but live adherent cells did. The mode of activation of auto-anti-Id T cells from patients with Chagas' disease depends on the clinical form of infection of both the cell donor and the donor of the stimulating anti-EPI antibodies.

Rat adrenal gland in experimental American trypanosomiasis: immunocytochemical study of tissue parasitism

The rat adrenal gland is poorly parasitized during the experimental infection with Y strain of Trypanosoma cruzi. In both cortical and medullary regions, the parasitism peaked at day 10 and was characterized by the predominance of single amastigotes over nests containing 2 or more parasites. After day 10 of infection, the tissue parasitism dropped rapidly to become practically null at day 32 of infection. In cortical tissue, the amastigotes occurred mainly inside the endocrine cells. In the medulla, they found mainly in glial cells and non-identified stromal cells. In both cortex and medulla, inflammatory processes were found till day 20 of infection. Our data do not support the hypothesis that a corticoid rich environment would favor T. cruzi parasitism in adrenal medulla.

Anti-Trypanosoma cruzi and anti-laminin antibodies in chagasic patients after specific treatment

The antibody response to Trypanosoma cruzi epimastigote and trypomastigote stages, as well as to laminin, was studied in several groups of chagasic patients. In six patients who were cured of the parasite, the serum antibody titers as revealed by indirect immunofluorescence and hemagglutination tests against epimastigotes (conventional serology) and a complement-mediated lysis test with living trypomastigotes did not differ from those of normal individuals. In seven presumably cured patients, although the complement-mediated lysis test turned negative, conventional serology remained positive. Sera from this group of so-called "dissociated" patients presented significant lower mean antibody titers against epimastigote but not trypomastigote stages than did sera from 14 untreated patients (P less than 0.01). Most of the antibodies against trypomastigotes, including the residual levels found in cured patients, were absorbed by mouse laminin. In fact, significantly higher titers of anti-laminin antibodies were observed in sera from untreated chagasic patients (1.131 +/- 0.458) and cured patients (1.103 +/- 0.572) than in sera from eight normal individuals (0.459 +/- 0.402) (P less than 0.01). The anti-laminin titers were higher in sera of patients of blood group A or O than in those of patients of group B or AB. In Western blotting (immunoblotting) analysis against trypomastigotes, sera from chronic untreated patients recognized many polypeptide bands ranging from 26 to 160 kilodaltons, whereas no protein bands were observed with sera from cured patients. Only faint bands of parasite proteins were observed with sera of dissociated patients. In conjunction, the above data suggest that the anti-trypomastigote antibodies which persist after parasitological cure of patients with Chagas' disease are due mainly to cross-reactive epitopes from mouse laminin.

[Post-mortem artificial xenodiagnosis in chronic chagasic patients]

A fim de obter metodologias que permitam estabelecer, com segurança, o diagnóstico "post-mortem " da infecção chagásica, adaptou-se o xenodiagnóstico artificial a necropsiados com diferentes tempos de óbito. O testefoi positivo em três (30%) de dez chagásicos autopsiados. O tempo decorrido entre o êxito letal e o início do repasto pelos triatomineos destes chagásicos foi de duas horas, duas horas e quinze minutos e sete horas, respectivamente. Discutem-se os fatores que podem explicara sobrevivência do Trypanosoma cruzi no hospedeiro morto bem como as aplicações práticas do achado.

Hematological changes in mice experimentally infected with Trypanosoma cruzi

Mice inoculated with trypanosoma cruzi display an intense thrombocytopenia which is more severe in animals infected with the Y than CL strain. In animals inoculated with a T. cruzi strain which induces chronic infection (Colombiana), the number of platelets decreases as parasitemia ascends, and then reverts to normal values as soon as the acute infection merges into the chronic phase. The mechanisms involved in the thrombocytopenia are still obscure and are likely to be related to more general phenomena affecting the host rather than to direct damage of platelets or precursor cells by parasitism. Anemia and leukopenia are also present in T. cruzi infected mice.