Is it possible to predict mortality and recurrence of VT afterablation? PAINESD risk score applicability vs new predictors

Funding Acknowledgements

Type of funding sources: None.

Introduction

Catheter ablation (CA) prevents ventricular tachycardia (VT) recurrences in patients (pts) with structural heart disease (SHD), and might have a favorable outcome, but is associated with severe short-term complications. Identification of pts at high risk of periprocedural acute haemodynamic decompensation has important implications at procedural planning.

The PAINESD risk score is a promising tool to predict VT ablation procedure-related mortality.

Aim

To evaluate the accuracy of the PAINESD risk score to predict short-term mortality after structural VT ablation and to compare it with other conventional clinical predictors.

Methods

Prospective, observational, single-centre study of consecutive pts with SHD (ischemic or nonischemic), referred for VT-CA. High-density substrate maps were collected, through endocardial, epicardial or combined endo-epicardial approaches according to clinical data and operator preference. The primary endpoint was 30-day mortality or hemodynamic decompensation. Univariate Cox regression analysis was used to identify relevant clinical predictors and to compare them with the PAINESD risk score. Multivariable Cox proportional hazards regression models were used to estimate predictors of 30-day mortality.

Results

A total of 102 pts with SHD referred for VT ablation were evaluated(mean age: 67±11 years, 94% male, 78.4% in NYHA class I-II; mean LVEF was 34±11%). The baseline PAINESD risk score was 12.39±5.8, 19.6% at low risk, 36.3% at intermediate risk and 27.5% at high risk of adverse events. Overall 30-day mortality was 4.9%. The PAINESD did not predict 30-days mortality or hemodynamic decompensation (p= 0.93). Indeed, a non- significant trend to higher short and long-term mortality was noticed in high-risk score pts – Figure 1. On univariate analysis age>65 years (p=0.019), LVEF <35% (p=0.049), body mass index<28kg/m2 (p=0.019), CKD (p=0.001) and previous VT ablation (p=0.022) were prognostic predictors. On multivariate analysis, only LVEF<35% (HR2.225; CI95% 1.004-4-774,p=0.038) and CKD (HR 3.35; CI95%: 1.31-8.51, p=0.011) were independent predictors of short-term prognosis.

Conclusions

In our population, LVEF<35% and CKD were the strongest predictors of short-term mortality. PAINESD risk score was not accurate in predicting adverse events. New score systems must be derived for prognostic stratification in this population, incorporating the reduction on the actual short-term event rates after VT ablation.

Burden of disease and associated complications of hepatitis a in children and adults in Mexico: A retrospective database study

BACKGROUND

Hepatitis A virus (HAV) infection is a leading cause of viral hepatitis in children, yet the HAV vaccine is not included in the national immunization program (NIP) in Mexico. This study addresses an identified evidence gap of the burden of hepatitis A disease, complications, and associated costs in Mexico by analyzing surveillance and healthcare data. Data review included disease morbidity (incidence and hospitalization), mortality, and healthcare resource utilization costs.

METHODS

In this observational, retrospective database study, we conducted a systematic screening, extraction, and analysis of outcome data from the national surveillance system in Mexico from January 2000 to December 2019.

RESULTS

During the analysis period (2000-2019), the average incidence rate/year of HAV cases was 14.7 (5.4-21.5) per 100,000 inhabitants. Children 1-9 years of age (YoA) had the highest average incidence rate/year with 47.8 (14.7-74.5). The average hospitalization rate/year due to HAV infection was 5.8% (2.9-9.6%). Although the highest burden of HAV continued to be in children (1-9 YoA), an increase in incidence and hospitalizations (with complications) in older age groups (≥ 10-64 YoA) was observed. The annual average fatality rate was estimated to be 0.44% (0.26-0.83%) of which 28.8% of deaths were concentrated in adults ≥ 65 YoA. The total direct costs of medical attention due to HAV and related complications were estimated at $382 million Mexican pesos.

CONCLUSION

The overall results suggest an uptrend in HAV infections in adolescents/adults compared to children in Mexico. Therefore, as the overall incidence risk of HAV infection decreases, the mean age of infection increases. This consequently increases the risk of severity and complications in older age groups, thus increasing the demand for healthcare resources. Our findings provide evidence for including the inactivated HAV vaccine in the Mexican NIP.

Analysis of Johne's disease ELISA status and associated performance parameters in Irish dairy cows

BACKGROUND

Infection with Mycobacterium avium subspecies paratuberculosis (MAP) has been associated with reductions in milk production in dairy cows and sub optimal fertility. The aim of this study was to highlight the production losses associated with testing MAP ELISA positive in Irish dairy cows. Secondary objectives included investigation of risk factors associated with testing MAP ELISA positive. A survey of management practices on study farms was also conducted, with examination of associations between management practices and herd MAP status. Blood samples were collected from 4188 breeding animals on 22 farms. Samples were ELISA tested using the ID Screen Paratuberculosis Indirect Screening Test. Production parameters examined included milk yield, milk fat, milk protein, somatic cell count, and calving interval. The association between MAP ELISA status and production data was investigated using multi-level mixed models. Logistic regression was used to identify risk factors for testing JD blood ELISA positive at individual cow level and to identify associations between farm management practices and herd MAP status.

RESULTS

Data were available for 3528 cows. The apparent prevalence recorded was 7.4%. Mixed model analysis revealed no statistically significant association between testing MAP ELISA positive and dairy cow production parameters. Risk factors associated with testing positive included larger sized herds being over twice more likely to test positive than smaller herds (OR 2.4 P = <0.001). Friesians were less likely to test positive relative to other breeds. A number of study farmers were engaged in management practices that have previously been identified as high risk for MAP transmission e.g., 73.1% pooled colostrum and 84.6% of study farmers used the calving area to house sick animals throughout the year. No significant associations however, were identified between farm management practices and herd MAP status.

CONCLUSION

No production losses were identified; however an apparent prevalence of 7.4% was recorded. With the abolition of EU milk quotas herd size in Ireland is expanding, as herds included in this study were larger than the national average, results may be indicative of future JD levels if no JD control programmes are implemented to minimise transmission.

Invited review: The economic impact and control of paratuberculosis in cattle

Paratuberculosis (also called Johne's disease) is a chronic disease caused by Mycobacterium avium ssp. paratuberculosis (MAP) that affects ruminants and other animals. The epidemiology of paratuberculosis is complex and the clinical manifestations and economic impact of the disease in cattle can be variable depending on factors such as herd management, age, infection dose, and disease prevalence, among others. Additionally, considerable challenges are faced in the control of paratuberculosis in cattle, such as the lack of accurate and reliable diagnostic tests. Nevertheless, efforts are directed toward the control of this disease because it can cause substantial economic losses to the cattle industry mainly due to increased premature culling, replacement costs, decreased milk yield, reduced feed conversion efficiency, fertility problems, reduced slaughter values, and increased susceptibility to other diseases or conditions. The variability and uncertainty surrounding the estimations of paratuberculosis prevalence and impact influence the design, implementation, and efficiency of control programs in diverse areas of the world. This review covers important aspects of the economic impact and control of paratuberculosis, including challenges related to disease detection, estimations of the prevalence and economic effects of the disease, and the implementation of control programs. The control of paratuberculosis can improve animal health and welfare, increase productivity, reduce potential market problems, and increase overall business profitability. The benefits that can derive from the control of paratuberculosis need to be communicated to all industry stakeholders to promote the implementation of control programs. Moreover, if the suspected link between Johne's disease in ruminants and Crohn's disease in humans was established, significant economic losses could be expected, particularly for the dairy industry, making the control of this disease a priority across dairy industries internationally.

Adhesion molecule profiles of B-cell non-Hodgkin's lymphomas in the leukemic phase

We evaluated the expression of 10 adhesion molecules on peripheral blood tumor cells of 17 patients with chronic lymphocytic leukemia, 17 with mantle-cell lymphoma, and 13 with nodal or splenic marginal B-cell lymphoma, all in the leukemic phase and before the beginning of any therapy. The diagnosis of B-cell non-Hodgkin's lymphomas was based on cytological, histological, immunophenotypic, and molecular biology methods. The mean fluorescence intensity of the adhesion molecules in tumor cells was measured by flow cytometry of CD19-positive cells and differed amongst the types of lymphomas. Comparison of chronic lymphocytic leukemia and mantle-cell lymphoma showed that the former presented a higher expression of CD11c and CD49c, and a lower expression of CD11b and CD49d adhesion molecules. Comparison of chronic lymphocytic leukemia and marginal B-cell lymphoma showed that the former presented a higher expression of CD49c and a lower expression of CD11a, CD11b, CD18, CD49d, CD29, and CD54. Finally, comparison of mantle-cell lymphoma and marginal B-cell lymphoma showed that marginal B-cell lymphoma had a higher expression of CD11a, CD11c, CD18, CD29, and CD54. Thus, the CD49c/CD49d pair consistently demonstrated a distinct pattern of expression in chronic lymphocytic leukemia compared with mantle-cell lymphoma and marginal B-cell lymphoma, which could be helpful for the differential diagnosis. Moreover, the distinct profiles of adhesion molecules in these diseases may be responsible for their different capacities to invade the blood stream.

Asynchronous expression of myeloid antigens in leukemic cells in a PML/RARalpha transgenic mouse model

Acute promyelocytic leukemia (APL) is characterized by the expansion of blasts that resemble morphologically promyelocytes and harbor a chromosomal translocation involving the retinoic acid receptor alpha (RARalpha) and the promyelocytic leukemia (PML) genes on chromosomes 17 and 15, respectively. The expression of the PML/RARalpha fusion gene is essential for APL genesis. In fact, transgenic mice (TM) expressing PML/RARalpha develop a form of leukemia that mimics the hematological findings of human APL. Leukemia is diagnosed after a long latency (approximately 12 months) during which no hematological abnormality is detected in peripheral blood (pre-leukemic phase). In humans, immunophenotypic analysis of APL blasts revealed distinct features; however, the precise immunophenotype of leukemic cells in the TM model has not been established. Our aim was to characterize the expression of myeloid antigens by leukemic cells from hCG-PML/RARalpha TM. In this study, TM (N = 12) developed leukemia at the mean age of 13.1 months. Morphological analysis of bone marrow revealed an increase of the percentage of immature myeloid cells in leukemic TM compared to pre-leukemic TM and wild-type controls (48.63 +/- 16.68, 10.83 +/- 8.11, 7.4 +/- 5.46%, respectively; P < 0.05). Flow cytometry analysis of bone marrow and spleen from leukemic TM identified the asynchronous co-expression of CD34, CD117, and CD11b. This abnormal phenotype was rarely detected prior to the diagnosis of leukemia and was present at similar frequencies in hematologically normal TM and wild-type controls of different ages. The present results demonstrate that, similarly to human APL, leukemic cells from hCG-PML/RARalpha TM present a specific immunophenotype.

Age-related changes of the multidrug resistance P-glycoprotein function in normal human peripheral blood T lymphocytes

The multidrug resistance P-glycoprotein is a transmembrane efflux pump expressed by lymphocytes and is involved in their cytolytic activity. In the present study, we investigated the age-related changes of P-glycoprotein function in normal peripheral blood lymphocytes. Blood samples from 90 normal volunteers (age range, 0 to 86 years) were analyzed. P-glycoprotein function was assessed by the flow cytometric rhodamine 123 assay. P-glycoprotein function was highest in cord blood and progressively declined with age in peripheral blood T CD4+ and CD8+ cells. In contrast, P-glycoprotein function did not vary with age in CD19+ B or CD16+CD56+ natural killer cells. These data suggest that the decline in P-glycoprotein function in T CD4+ and CD8+ lymphocytes as a function of age may contribute to the decrease in T cell cytolytic activity with aging.

Aggressive variant of morphologically typical T large granular lymphocyte leukemia/lymphoma lacking NK cell markers

A 46-year-old woman with a previous diagnosis of sarcoidosis presented with morphologically typical large granular lymphocyte (LGL) leukemia/lymphoma with an aggressive clinical course. Epstein-Barr virus DNA was detected in peripheral blood mononuclear cells by PCR. The phenotype was typical of the T cell lineage (CD2+ CD3+ CD5+ CD7+ CD8+ TCRalphabeta+) but with the absence of the CD16, CD56, CD57 NK cell markers. In addition, the LGLs expressed CD122 (p75) in the absence of CD25 which is characteristic of LGLs. These leukemic LGLs did not exhibit NK activity. The clonal nature of this proliferation was demonstrated by the rearrangement of the TCRgamma gene. This phenotypically unusual but morphologically typical LGL leukemia/lymphoma may represent the clonal expansion of a minor normal subset of T-LGLs which do not express any NK cell markers, probably corresponding to in vivo activated T cells.

Immunophenotype of normal and leukemic bone marrow B-precursors in a Brazilian population. A comparative analysis by quantitative fluorescence cytometry

The distinction between normal and leukemic bone marrow (BM) B-precursors is essential for the diagnosis and treatment monitoring of acute lymphoblastic leukemia (ALL). In order to evaluate the potential use of quantitative fluorescence cytometry (QFC) for this distinction, we studied 21 normal individuals and 40 patients with CD10+ ALL. We characterized the age-related changes of the CD10, CD19, TdT, CD34 and CD79a densities in normal and leukemic BM. Compared to normal adults, the B-precursors from normal children expressed significantly lower values of CD34-specific antibody binding capacity (SABC) (median value of 86.6 vs 160.2 arbitrary units (a.u.) in children and adults, respectively). No significant age-related difference was observed in the expression of the other markers in the normal BM, or in any of the markers in the leukemic BM. Based on the literature, we set the cut-off value for the normal CD10 expression at 45 x 10(3) a.u. for both age groups. For the remaining markers we established the cut-off values based on the minimum-maximum values in the normal BM in each age group. The expression of CD10 was higher than the cut-off in 30 ALL cases and in 18 of them there was a concomitant aberrant expression of other markers. In 9 of the 10 CD10+ ALL with normal CD10 SABC values, the expression of at least one other marker was aberrant. In conclusion, the distinction between normal and leukemic cells by QFC was possible in 38/40 CD10+ ALL cases.

Increased dexamethasone-induced apoptosis of thymocytes from mice exposed to long-term extremely low frequency magnetic fields

To address the effect of extremely low frequency electromagnetic fields on programmed cell death we assessed both the spontaneous and dexamethasone (Dex)-induced apoptosis of thymocytes and spleen cells from mice submitted to a long-term continuous exposure of a 0.4-1.0 microT 60 Hz magnetic field or an 8-20 microT direct current (DC) magnetic field. Dex-induced apoptosis but not spontaneous apoptosis was substantially increased in thymocytes from 0.4 to 1.0 microT 60 Hz field-exposed animals. Spontaneous apoptosis and Dex-induced apoptosis of spleen cells were not affected by the 0.4-1.0 microT 60 Hz field exposure. In addition, spontaneous apoptosis and Dex-induced apoptosis of thymocytes and spleen cells from mice exposed to an 8-20 microT DC field were similar to the controls. These findings represent the first demonstration that thymocytes from mice exposed to a long-term 0.4-1.0 microT 60 Hz field may show abnormal response to Dex apoptotic stimuli.

The effect of unmodified or prestorage white cell-reduced allogeneic red cell transfusions on the immune responsiveness in orthopedic surgery patients

BACKGROUND

The immunomodulatory effects of allogeneic blood transfusions have been attributed to the white cells (WBCs) present in the cellular blood components transfused to patients.

STUDY DESIGN AND METHODS

The effect of the transfusion of allogeneic red cells (RBCs) or allogeneic prestorage WBC-reduced RBCs (WBC-reduced RBCs) on host immune responsiveness was evaluated by measuring the lymphocyte subsets and the in-vitro cytokine production in response to phytohemagglutinin stimulation of WBCs of orthopedic surgery patients. Forty-seven patients undergoing hip replacement surgery were randomly assigned to receive allogeneic RBCs (n = 17) or WBC-reduced RBCs (n = 14; 99.95% WBC removal). Sixteen patients were not transfused. Patient blood samples taken before surgery and on Days 1 and 4 after surgery were tested for complete blood count, lymphocyte subset analysis, and measurement of cytokine levels.

RESULTS

After surgery, the lymphocyte count was significantly decreased in patients transfused with > or = 3 units of allogeneic RBCs (2.0 +/- 0.5 vs. 1.3 +/- 0.3 x 10(9)/L; p = 0.017), but not in patients transfused with > or = 3 units of WBC-reduced RBCs (2.0 +/- 0.9 vs. 1.7 +/- 0.8 x 10(9)/L). Compared with preoperative levels, on Day 4 after surgery, patients transfused with > or = 3 units of allogeneic RBCs also had a decrease in the number of natural killer cells (0.07 +/- 0.05 vs. 0.04 +/- 0.03 x 10(9)/L; p = 0.018). Postoperatively, interleukin-2 was decreased in one patient who received WBC-reduced RBCs compared with that in four patients transfused with allogeneic RBCs (p = 0.32), and eight untransfused patients (p = 0.01). On Day 4, about 70 percent of patients transfused with allogeneic RBCs showed a 20-percent decrease in the interferon gamma level.

CONCLUSION

Taken together, these data support the hypothesis that transfusion of > or = 3 units of allogeneic RBCs is associated with early postoperative lymphopenia in otherwise healthy individuals undergoing surgery. These findings were not observed in those individuals transfused with RBCs that had undergone prestorage WBC reduction.

Age-related changes of immunophenotypically immature lymphocytes in normal human peripheral blood

The presence of phenotypically immature lymphocytes in umbilical cord blood has been a controversial topic. Moreover, their changes with age have not been systematically evaluated. In the present study, relative and absolute numbers of CD34+, CD10+CD19+, and CD4+CD8+ cell subsets were determined in umbilical cord blood from 12 full-term normal newborns, 43 children aged 1 month to 6 years, and 10 young adults. The samples were processed by whole-blood lysis and monoclonal antibody staining, and cells were analyzed by flow cytometry. Immature cells were present in cord blood and progressively declined in both absolute and percentage numbers with age, each according to a particular curve, reaching youth values roughly at age 2-4 years. These results demonstrate that phenotypically immature cells normally circulate at low levels in peripheral blood, mostly at birth and during infancy, but also during youth.

CD10 and CD19 fluorescence intensity of B-cell precursors in normal and leukemic bone marrow. Clinical characterization of CD10(+strong) and CD10(+weak) common acute lymphoblastic leukemia

In order to assess the age-related changes in CD10 and CD19 fluorescence intensity (FI) the present study analyzed by flow cytometry 56 sternal biopsies from 'normal' infants, children and adults undergoing cardiac surgery. The CD10(+weak) subset was predominant in all age groups, representing approximately 50% of the bone marrow (BM) lymphoid cells in children younger than 4 years. Both CD10+ subsets significantly decreased with age but their ratio did not differ significantly. Moreover, the intensity of CD10 and CD19 fluorescence in the strong and weak subsets did not vary with age. The CD19 intensity was significantly higher in CD10(+weak) than in CD10(+strong) cells. In addition, we classified as CD10(+weak) or CD10(+strong) the leukemic cells from BM aspirates of 117 patients with common acute lymphoblastic leukemia (cALL) (78 children and 39 adults). A higher frequency of cases expressing the CD19+ CD10(+strong) phenotype was observed both in children and adults. Children of the CD10(+weak) group tended to be older than those of the CD10(+strong) group (median = 7 vs. 4 years, P = 0.07), and presented a significantly higher frequency of splenomegaly (93.7 vs. 55%, P = 0.04), which was massive in about 60% of these cases. Among adults, a significantly higher frequency of cases expressing the CD10(+weak) phenotype was observed in females. No other clinical or biological difference was detected between the two groups either for children or adults. Concerning the treatment outcome, we did not observe significant differences in complete remission rate (CRR) or in disease free survival (DFS) among the 32 children and 28 adults analyzed. Finally, we compared the CD10 and CD19 intensity in normal and leukemic BM. Overexpression of either or both antigens in leukemic cells was observed in 42.4% of the cALL cases. In these cases, using cut off values of 110 afu for the CD10 FI and of 100 afu for the CD19 FI, the detection of leukemic cells was possible at levels of 0.2% based on CD10 analysis, of 0.6% based on CD19, and 0.02% when both antigens were overexpressed. In conclusion, we demonstrated that the heterogeneity of CD10 and CD19 fluorescence intensity is of no clinical relevance in cALL, although its study may be helpful for the diagnosis and the detection of minimal residual disease.

The expression of the salt-responsive gene salT from rice is regulated by hormonal and developmental cues

The expression pattern of the salT gene was analyzed in different cell types and organs of rice (Oryza sativa L.) in response to saline and hormonal treatments to obtain detailed information on the physiological cues controlling gene expression. Gel blot analysis of RNA and in-situ hybridization performed on seedlings grown for 10 ds in the presence of 1% NaCl revealed that salT was expressed mainly in the younger tissues of the plant. In contrast, 6-week-old plants exhibited maximal salT mRNA accumulation in sheaths of older leaves. In addition, salT was normally expressed in rapidly dividing suspension-cultured cells, but not in quiescent ones. Altogether, these results may indicate that salT expression in each region of the plant is dependent on the metabolic activity of the cells as well as on whether or not they are stressed. The effects of two growth regulators, abscisic acid (ABA) and gibberellic acid, were investigated in combination with the effects of NaCl. Gibberellic acid had a synergistic effect on the induction of the salT gene when combined with 0.5% NaCl, but did not induce salT on its own. At 10 microM, ABA induced salT both in the absence of NaCl and in its presence. Whereas 1 microM ABA acted additively with NaCl to induce gene expression, 5 microM ABA with NaCl was only as effective as NaCl alone. This may indicate that the two stimuli act independently and possibly through antagonistic signal transduction pathways.

Decreased activity of the multidrug resistance P-glycoprotein in acquired aplastic anaemia: possible pathophysiologic implications

To address a possible impairment of multidrug resistance mechanisms in acquired aplastic anaemia (AA), the functions of P-glycoprotein (P-gp) and multidrug resistance-associated protein (MRP) were respectively assessed by rhodamine 123 (Rh123) and daunorubicin (DNR) efflux in peripheral blood lymphocytes from AA patients. The proportion of Rh123-effluxing T cells was significantly decreased in AA, relative to controls. Interestingly, these changes were also present in patients with AA in remission. Conversely, Rh123 efflux in B and natural killer (NK) cells and DNR efflux in peripheral blood lymphocytes were unchanged. These data indicated that P-gp activity was decreased in AA not only during the development of the disease, but also after remission, introducing a new concept on the pathophysiology of AA by suggesting that it may contribute to drug-induced injury to haemopoietic cells in some cases of AA, by increasing the proportion of susceptible cells.

Fas-mediated apoptosis with normal expression of bcl-2 and p53 in lymphocytes from aplastic anaemia

In order to investigate the involvement of apoptosis in the pathogenesis of aplastic anaemia (AA) we measured the expression of the Fas receptor (membrane protein that triggers apoptosis), Fas ligand (FasL), bcl-2 (cytoplasmatic protein that blocks apoptosis) and p53 (nuclear protein that induces apoptosis) in CD3 and CD19 lymphocytes from the peripheral blood or bone marrow of controls, patients with AA, aplastic anaemia in complete remission (AA-CR) and multiply transfused patients without aplastic anaemia. The Fas receptor was overexpressed in both T and B lymphocytes from the peripheral blood and bone marrow from patients with AA. These abnormalities were not detected in AA-CR or multiply transfused patients. CD3/FasL cells were not increased and no FasL expression was detected in B lymphocytes. Bcl-2 was highly expressed in lymphocytes from controls, AA, AA-CR and multiply transfused patients (> 99% of positive cells) whereas p53 was not detected in any group. To further characterize the functional activity of the Fas receptor we performed a Fas-induced apoptosis assay in peripheral blood lymphocytes using an anti-Fas monoclonal antibody. The crosslinking of the Fas receptor transduced an increased apoptotic signal in lymphocytes from AA patients, but not in lymphocytes from controls, AA-CR patients or multiply transfused patients. Taken together, these data suggest that a Fas-based mediated apoptosis without the apparent participation of bcl-2 or p53 is a possible mechanism of lymphocyte depletion in patients with AA. In addition, these findings suggest that Fas expression is a continuous event occurring from progenitor bone marrow cells to mature cells.

Age-related changes of lymphocyte subsets in normal bone marrow biopsies

There is a paucity of information in the literature concerning the age-related changes of the lymphocyte subsets in bone marrow (BM), and the available reports disagree about the characteristics of the population studied and the methods for obtaining, handling, and analyzing the samples. The purpose of the present study was to determine the distribution of lymphoid subsets in the BM from infants, children, and adults by analyzing fragments of sternum obtained during cardiovascular surgery. The samples were studied by flow cytometry employing the whole blood lysis method and excluding from the analysis the contamination of the lymphoid window by erythroid precursors. We observed that in the first 4 years of life the B subset represented more than 65% of all cells in the lymphoid window, most of them (80%) exhibiting the immature phenotype CD19+CD100+. Conversely, the T subset was composed of mature CD4+ or CD8+ cells, with the CD4/CD8 ratio being less than 1 in all age groups. With age there was a progressive decrease in the percentage of B cells and an increase of T cells, reaching similar proportions in the BM from adults (33.6% and 34.8%, respectively). Furthermore, the percentage of CD10+ cells in the B subset decreased independently, whereas the CD20 expression increased. The percentage of NK cells did not change with age.

Zeta Potential as a Tool to Characterize Plasma Oxidation of Carbon Fibers

Two different types of carbon fibers (ultrahigh modulus and high strength carbon fibers) were surface-treated in an oxygen plasma under equivalent conditions. Changes in the fiber surface chemistry were followed by electrokinetic measurements (zeta potential). The oxygen plasma treatment resulted in a displacement of the isoelectric point of carbon fibers toward lower pHs, evidence of an increase in the surface acidity. The possible simultaneous formation of basic functional groups was also inferred and supported by results obtained by inverse gas chromatography and wettability measurements. Differences were more evident with ultrahigh modulus carbon fibers than with high strength carbon fibers. It is concluded that the measurement of the electrokinetic properties constitutes a useful technique to follow the evolution of the surface chemical characteristics of different types of carbon fibers. Copyright 1997Academic Press

Lymphocyte subsets in experimental hemochromatosis

The distribution of lymphocyte subsets in blood, thymus, spleen, mesenteric lymph nodes, Peyer's patches and bone marrow was evaluated in an experimental model of secondary hemochromatosis in rats. The values of CD2, CD4, CD8, B and NK cells in these different lymphoid compartments did not differ between the control group and the experimental group. These results suggest that the abnormalities of lymphocyte subsets previously reported in patients with secondary hemochromatosis may be due to factors other than iron overload.

Phenotypic and functional evaluation of natural killer cells in thymectomized children

The purpose of this study was to determine the effect of thymectomy on the number and activity of NK cells in the peripheral blood of children submitted to thymus removal. Twenty-three children, aged 4 to 48 months at thymectomy, whose thymus was fully removed to permit access to the heart for corrective surgery, were studied. Only children thymectomized during the first year of life had a decreased number of CD2+/CD3+, CD4+/CD16- , and CD8+/CD16- T subsets and an increase in the CD16-/CD56bright+ NK subset. In addition, the CD57-/CD16+ and CD57-/D56+ subsets which are shared by T and NK cells were increased. These findings associated with a tendency to increased NK activity suggest that the human thymus is partially involved in the control of the release of circulating T cells and may negatively modulate some NK subsets, as well as NK activity, during the first year of life but not later.

Characterization of acute lymphoblastic leukemia subtypes in Brazilian patients

The distribution of the acute lymphoblastic leukemia (ALL) subsets in 225 consecutive Brazilian patients was determined by an immunophenotypic study with an extensive panel of monoclonal antibodies. All subsets were detected and their relative frequencies were similar to those described in developed countries, except for the B-mature subset which had a higher frequency, especially in adults. Associated myeloid markers were expressed by 11% of the ALL and CD10 by 15.9% of T-ALL cases. Besides, the incidence rates determined for the region of Ribeirão Preto showed that the overall incidence of ALL was 12.5 cases/10(6) people years (PY) (5 cases/10(6) PY in non-Whites versus 14 cases/10(6) PY in Whites); the incidence of childhood ALL was 25.5 cases/10(6) PY (8.1 versus 29.8 cases/10(6) PY in non-Whites and Whites, respectively) and the incidence of ALL in adults was 6.2 cases/10(6) PY (5.5 versus 6.1 cases/10(6) Py in non-Whites and Whites, respectively). The significantly lower incidence rate of ALL in non-White children was associated with a selective deficit of the common subtype and a lack of the typical age peak of incidence in this group. The ALL features demonstrated here in Brazilian non-White children resemble those described in the American non-Whites before the seventies and those in British and American Whites at the beginning of the century.

GACPAT HIV 1 + 2: a simple, inexpensive assay to screen for, and discriminate between, anti-HIV 1 and anti-HIV 2

A simple and cheap assay suitable for screening for anti-HIV 1 and anti-HIV 2 and discriminating between them was evaluated. In it specimens are incubated in U-bottomed microplate wells coated with anti-human IgG for 30 min at room temperature. After washing, 100 microliters of a 1 in 50 dilution of HIV 1-coated gelatin particles (Serodia-HIV 1/2, Fujirebio) are added. Settling patterns are read on the second day: A positive reaction is indicated by adherence of the particles and a negative by a button. The HIV 1 particles are then washed away and HIV 2 particles added. Anti-HIV 2 reaction patterns are read on the third day. To assess the performance of the modified "GACPAT HIV 1 + 2" assay a panel of 1,621 serum/plasma specimens was used. It comprised validated anti-HIV 1 positive (n = 220), anti-HIV 2 positive (n = 214), dual anti-HIV 1/anti-HIV 2 positive (n = 11), and anti-HIV negative (n = 1,176) serum/plasma specimens. All 434 specimens that contained anti-HIV 1 or anti-HIV 2 reacted positively with the homologous particles. The 11 dually positive specimens reacted positively with both HIV 1 and HIV 2 particles. Five (2.3%) anti-HIV 1 and five (2.3%) anti-HIV 2 positive specimens gave positive reactions with both particle types, but none of the five cross-reactive anti-HIV 2 specimens were dually reactive when the order of particle addition was reversed.(ABSTRACT TRUNCATED AT 250 WORDS)

Heat-inducible rice hsp82 and hsp70 are not always co-regulated

We have characterized several heat-shock-induced genes in rice (Oryza sativa L.) and compared their expression under a variety of conditions. Three of these genes, which are analogs of the hsp82/90 family, lie within a cloned 18-kilobase (kb) region of the genome. The middle member of this cluster, designated hsp82B, has been fully sequenced. The gene uses a promoter containing six putative heat-shock elements as well as several unusual sequence motifs including a stretch of 11 thymidines alternating with 11 adenosines. The mRNA for this gene reaches its highest relative level of expression within 120 min after plants are shifted to 42 degrees C; no other conditions induce this gene. By contrast, we found that during heat stress the expression of hsp70 correlates well with increases in internal ion concentrations, and can also be induced by excess salt or ethanol at normal growth temperatures. These results appear to indicate that whereas hsp70 is induced by all stresses that lead to protein denaturation-including heat stress-HSP82 mRNA accumulates only upon heat stress.

Expression of CD45RA (naive) and CD45RO (memory) antigens in T-acute lymphoblastic leukaemia

We have determined the distribution of CD45RO (memory) and CD45RA (naive) antigens in the bone marrow blasts from 25 patients with T-acute lymphoblastic leukaemia (T-ALL). Four groups of patients were identified on the basis of reactivity with specific antibodies by flow cytometric analysis: (a) CD45RA-/CD45RO+ (16 patients): four CD4-/CD8+, seven CD4+/CD8+ and five CD4-/CD8-; (b) CD45RA+/CD45RO- (three patients): three CD4-/CD8-; (c) five CD45RA-/CD45RO-: one CD4+/CD8-; one CD4-/CD8+; three CD4+/CD8+; (d) CD45RA+/CD45RO+ (one case): CD4+/CD8-. There was no correlation between the expression of the naive and the memory phenotypes and the presence of CD4, CD8 or any other antigen except the CD10 antigen which was expressed by all CD45RA-/CD45RO- patients. The predominance of the CD45RA-/CD45RO+ phenotype (65%) and the low incidence of the hybrid phenotype CD45RA+/CD45RO+ (5%) in T-ALL, differs from the results reported by others for chronic or prolymphocytic T-cell leukaemias, in which the simultaneous expression of these maturational antigens was detected in approximately half of the cases.

Characterization of myeloid or lymphoid acute leukemia by a chemiluminescence assay. Comparison with immunocytochemistry using an antimyeloperoxidase antibody

A simple and sensitive chemiluminescence assay for the demonstration of the activity of intracellular myeloperoxidase (MPO) is described, which is useful for the distinction between myeloid and lymphoid commitment in blasts from acute leukemia patients. When the cut-off point was settled at 13 mV of chemiluminescence all cases of acute myeloid leukemia (AML) were distinguished from those of acute lymphoid leukemia. In addition, this technique was able to demonstrate MPO activity in AML poorly differentiated (FAB-M0) which usually does not stain for MPO in classical cytochemistry preparations and could be negative also by immunocytochemistry with anti-MPO monoclonal antibody. Therefore the method here described presented a higher sensitivity than the immunocytochemistry procedure with anti-MPO.