The Bacillus secretion stress response is an indicator for alpha-amylase production levels.

AIMS: Overproduced alpha-amylases in Bacillus subtilis provoke a specific stress response involving the CssRS two-component system, which controls expression of the HtrA and HtrB proteases. Previously, the B. subtilis TepA protein was implicated in high-level alpha-amylase secretion. Our present studies were aimed at investigating a possible role of TepA in secretion stress management, and characterizing the intensity of the secretion stress response in relation to alpha-amylase production. METHODS AND RESULTS: The expression of a transcriptional htrB-lacZ gene fusion, and the levels of alpha-amylase production were monitored simultaneously using tepA mutant B. subtilis strains. TepA was shown to be dispensable for secretion stress management. Importantly, however, the levels of htrB-lacZ expression can be correlated with the levels of alpha-amylase production. CONCLUSION: Our observations show that the secretion stress response can serve as an indicator for alpha-amylase production levels. SIGNIFICANCE AND IMPACT OF STUDY: Conceivably, this stress response can be employed to monitor the biotechnological production of various secretory proteins by the Bacillus cell factory.

The potential active site of the lipoprotein-specific (type II) signal peptidase of Bacillus subtilis.

Type II signal peptidases (SPase II) remove signal peptides from lipid-modified preproteins of eubacteria. As the catalytic mechanism employed by type II SPases was not known, the present studies were aimed at the identification of their potential active site residues. Comparison of the deduced amino acid sequences of 19 known type II SPases revealed the presence of five conserved domains. The importance of the 15 best conserved residues in these domains was investigated using the type II SPase of Bacillus subtilis, which, unlike SPase II of Escherichia coli, is not essential for viability. The results showed that only six residues are important for SPase II activity. These are Asp-14, Asn-99, Asp-102, Asn-126, Ala-128, and Asp-129. Only Asp-14 was required for stability of SPase II, indicating that the other five residues are required for catalysis, the active site geometry, or the specific recognition of lipid-modified preproteins. As Asp-102 and Asp-129 are the only residues invoked in the known catalytic mechanisms of proteases, we hypothesize that these two residues are directly involved in SPase II-mediated catalysis. This implies that type II SPases belong to a novel family of aspartic proteases.

Risk factors for childhood acute non-lymphocytic leukemia: an association with maternal alcohol consumption during pregnancy?

A population-based case-control study of acute non-lymphocytic leukemia (ANLL) was performed with 80 ANLL cases diagnosed between 1973 and 1979, who were derived from the nationwide register of the Dutch Childhood Leukemia Study Group. Cases were compared to three age- and sex-matched population controls and, in order to control for recall bias, to 517 cases with acute lymphocytic leukemia from the same study base. Information on a large number of exposures to putative risk factors was collected by a self-administered questionnaire mailed to the parents. No significant association of ANLL was observed with smoking habits of the mother during pregnancy, ultrasound examinations, prenatal exposure to x-rays, viral infections, or hydrocarbon exposure. When comparing ANLL cases to population controls, maternal use of alcohol during pregnancy was associated with a more than two-fold increased risk of ANLL (odds ratio = 2.6; 95% confidence interval = 1.4-4.6). A similar increase in risk was found when comparing ANLL cases to acute lymphocytic leukemia cases. There was no significant elevation in risk for ANLL found for parental use of alcohol 1 year before pregnancy. This study suggests that intrauterine exposure to alcohol may increase the risk for childhood ANLL.

Terminal deoxynucleotidyl transferase (TdT)-positive cells in cerebrospinal fluid and development of overt CNS leukemia: a 5-year follow-up study in 113 children with a TdT-positive leukemia or non-Hodgkin's lymphoma.

We investigated whether an indirect nuclear terminal deoxynucleotidyl transferase (TdT) immunofluorescence (IF) assay on single cells present in the cerebrospinal fluid (CSF) is more effective than conventional cytomorphology for early detection or exclusion of (minimal) meningeal leukemic infiltration in patients with a TdT+ malignancy. During a 5-year follow-up study, 1,661 consecutive CSF samples from 113 children with a TdT+ acute lymphoblastic leukemia (ALL) (n = 100), a TdT+ acute nonlymphoblastic leukemia (ANLL) (n = 8), or a TdT+ non-Hodgkin's lymphoma (NHL) (n = 5) were analyzed. In 1,511 (91.9%) of 1,643 evaluable CSF samples, the positive and negative findings of both cytomorphology and the TdT-IF assay were concordant. In 47 (2.9%) samples from 28 patients, the cytomorphology was suspect while the TdT-IF assay was negative; follow-up as long as 58 months revealed no CNS leukemia in any patient. In 85 (5.2%) samples, cytomorphology was negative (n = 70) or suspect (n = 15) but TdT+ cells were detected. RBC contamination seriously hampered evaluation in 31 of these 85 samples. From the remaining 54 TdT+ samples from 29 patients, 40 samples preceded overt CNS leukemia in 20 patients. Two consecutive findings of TdT+ cells in the CSF were always followed by overt CNS leukemia. At initial diagnosis, 11 children had TdT+ cells in their RBC-free CSF. In one of these children, morphology was suspect; a repeated lumbar puncture was positive on both assays. Thus, initial CNS leukemia was diagnosed. In the other ten children, morphology was negative. In six of them, CNS leukemia was diagnosed 2 to 20 months later. In 32 other children examined at initial diagnosis, neither TdT+ cells nor blasts were observed in the CSF. In none of these patients was a CNS leukemia diagnosed after a follow-up of 2.5 to 57 months (median 24 months). In 207 control CSF samples from 58 children with TdT- oncologic, hematologic, or infectious diseases, no TdT+ cells could be detected. The TdT-IF assay is easy to perform and is a more reliable diagnostic tool for detection of CNS leukemia at an early stage than is cytomorphology. At initial diagnosis, the finding of Tdt+ cells in a RBC-free CSF sample with a negative cytomorphology is highly predictive for development of overt CNS leukemia.

Effectiveness of rubidomycin in induction therapy with vincristine, prednisone, and L-asparaginase for standard risk childhood acute lymphocytic leukemia: results of a Dutch phase III study (ALL V). A report on behalf of the Dutch Childhood Leukemia Study Group (DCLSG).

The Dutch Childhood Leukemia Study Group (DCLSG) performed a phase III study-Study (ALL) V-to evaluate the effectiveness of rubidomycin in induction therapy with vincristine, prednisone, and L-asparaginase for children (0-15 years) with standard risk acute lymphoblastic leukemia (ALL) (white blood cell [WBC] counts less than 50.10(9)/L, absence of mediastinal mass, and/or cerebromeningeal leukemia). Furthermore, the influence of initial patient and disease characteristics on the outcome was analyzed. Between May 1979 and December 1982, 240 patients entered the study and were randomized into two groups: group A (n = 122) received induction treatment with vincristine (VCR), prednisone (Pred), and L-asparaginase (L-Asp); for group B (n = 118), induction therapy consisted of VCR, Pred, L-Asp, and rubidomycin (Rub). All patients subsequently underwent cranial irradiation (doses adjusted to age) in combination with intrathecal methotrexate; maintenance therapy of 6-mercaptopurine and methotrexate for 5 weeks followed by vincristine and prednisone for 2 weeks was given for 24 months. The complete remission (CR) rate was similar in both groups (94.5%). Event-free survival (EFS) 5 years after diagnosis was higher in group B (62.5 +/- 4.5%) than in group A (54.7 +/- 4.5%), although the difference is not significant (p = 0.20). A high initial WBC (greater than or equal to 10.10(9)/L), age (greater than or equal to 10 years), a low platelet count (less than 100.10(9)/L), and a positive acid phosphatase reaction of the leukemic cells were unfavorable prognostic factors (p less than 0.05). Sex, French-American-British (FAB) classification group, immunophenotype, and treatment in specialized centers did not have a significant impact on event-free survival.

Childhood leukaemia in The Netherlands, 1973-1986: temporary variation of the incidence of acute lymphocytic leukaemia in young children.

The incidence of childhood leukaemia in The Netherlands in the period 1973-1986 was studied by means of the DCLSG nationwide register, which lists all patients according to bone marrow slides classified in the DCLSG central laboratory. Acute lymphocytic leukaemia (ALL) accounted for 81% of cases, acute non-lymphocytic leukaemia (ANLL) for 13%, chronic myelocytic leukaemia (CML) for 2.5%, and acute unclassifiable leukaemia (AUL) for 3%. The peak incidence of ALL was at age 3, common-ALL and pre B-ALL comprising about 95% of the immunophenotypes at this age. Incidence rates for ALL remained stable between 1973 and 1978 at 2.85 cases per 10(5) children per year, exhibited a temporary increase between 1979 and 1984 to 3.60 and dropped back to the lower, previous level in 1985 and 1986. This rise was seen mainly among children in the 1-4 year age group, especially at age 3, and those with common-ALL and an initial WBC less than 5.0 x 10(9) l-1. Cumulative incidence rates per year of birth were fairly homogeneous up to age 6, except for the 1978 birth cohort which exhibited higher rates. Incidence rates for ANLL, CML and AUL remained stable over time. Changes in ascertainment, declining birth rates and a 50% decrease in childhood mortality, e.g. from infectious diseases, could not explain this temporary variation. Moreover, incidence rates in this survey appeared to be similar to those reported in various developed countries for the same period. As far as the aetiology of childhood common-ALL is concerned, therefore, the Dutch data appear to support the hypothesis of 'random mutation' as well as that of a limited role of environmental factors.

[Results of treatment of children with acute lymphatic leukemia (ALL) according to the ALL V protocol of the Netherlands Working Group on Leukemia in Children]. / Resultaten van behandeling van kinderen met acute lymfatische leukemie (ALL) volgens SNWLK protocol ALL V.

The Dutch Childhood Leukemia Study Group performed a phase III study (Study ALL V) to evaluate the effectiveness of addition of rubidomycin to induction treatment with vincristine, prednisone and L-asparaginase in children (0-15 years) with standard risk acute lymphoblastic leukemia: WBC less than 50.10(9)/l, absence of mediastinal mass and/or cerebromeningeal leukemia. Furthermore, the influence of some initial patient- en disease-characteristics on the outcome was analysed. Between May 1979 and December 1982 240 patients entered into the study and were randomized into 2 groups: group A (n = 122) received induction treatment with vincristine, prednisone and L-asparaginase; group B (n = 118) received induction treatment with vincristine, prednisone, L-asparaginase and rubidomycin. All patients received cranial irradiation (doses adjusted to age) and intrathecal methotrexate, followed by maintenance treatment with 6-mercaptopurine and methotrexate for 5 weeks, alternated with vincristine and prednisone for 2 weeks, up to 24 months. Complete remission rate was 94% in both groups. Event-free survival at 5 years after diagnosis was higher in group B (62% +/- 4.6%) than in group A (54.2% +/- 4.6%) but the difference was not significant. A higher initial WBC, age greater than or equal to 10 years and a positive acid phosphatase reaction of the leukemic cells were unfavorable prognostic factors (p less than 0.01). Sex, FAB-morphology, immunophenotype and place of treatment (center or general hospital) were not significant factors.

Acute lymphoblastic leukemia and non-Hodgkin's lymphoma of T lineage: colony-forming cells retain growth factor (interleukin 2) dependence.

The regulatory role of interleukin 2 (IL 2) in the proliferation of T acute lymphoblastic leukemia (T-ALL) and T non-Hodgkin's lymphoma (T-NHL) cells from six individual patients was analyzed in a colony culture system to which pure recombinant IL 2, and the lectin phytohemagglutinin (PHA) or the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA), had been added. The proliferative response was correlated with the inducibility of receptors for IL 2 on the surface membrane of T-ALL and T-NHL cells by incubation with TPA or PHA for 18 hours. Leukemic T cell colonies, identified by immunophenotyping or cytogenetic analysis, appeared in vitro following TPA and IL 2 stimulation in all six cases. Accordingly, receptors for IL 2, initially absent from the cell surface, were found on high proportions of the T-ALL and T-NHL cells after in vitro exposure to TPA. In contrast, colony formation stimulated by PHA and the induction of IL 2 receptors by PHA were limited to the one case of T-NHL with the mature thymocyte immunophenotype. The cells from the other patients, expressing common or prothymocyte phenotypes, did not respond to PHA. No colonies were formed in any of these cases when PHA or TPA was withheld from the IL 2-containing cultures. Although colony growth depended absolutely on exogenous IL 2 in three cases (ALL), in the three other cases (one ALL, two NHL) some colonies grew also when no IL 2 had been added to the cultures. Upon further analysis of the cells of one of the latter patients, it was found that the cells produced IL 2 and proliferated in response to this endogenous IL 2. The results from this study indicate that the requirements of endogenous v exogenous IL 2 for cell proliferation in T-ALL and T-NHL and IL 2 receptor activation by PHA and TPA vary from patient to patient. In addition, they support the notion that T-ALL and T-NHL cells have not lost dependence on IL 2 and IL 2 receptor activation for in vitro growth.

Childhood leukemia and infectious diseases in the first year of life: a register-based case-control study.

In the Netherlands, a nationwide register of children with leukemia formed the basis for a case-control study (1973-1980). Population controls were matched with the cases for the year of birth, sex, and place of residence at the time of diagnosis. The information was collected by mailed questionnaires addressed to the parents. The analyses concerned infectious diseases in the first year of life of children with acute lymphocytic leukemia and their controls. Common colds, periods of fever, and primary childhood infections showed relative risks (RR) of 0.8, 0.9, and 0.8, respectively, after adjustment for birth order, family size, social class, and residential space. Furthermore, fewer cases reported infectious diseases which required hospitalization in their first year of life (RR = 0.6, 95% confidence interval (CI) = 0.4-1.0). The general infection risk profile of children with acute lymphocytic leukemia is compatible with these findings: there were more first-born children among the patients (RR = 1.8; 95% CI = 1.1-2.7), more children from one-child families (RR = 1.4; 95% CI = 0.8-2.3), more children of parents with higher education (RR = 1.2; 95% CI = 0.9-1.5), and more rooms in patient's houses (RR = 1.4; 95% CI = 0.6-2.6).

[Detection of low numbers of malignant cells in patients with leukemia or non-Hodgkin lymphoma: use of immunological markers]. / Opsporen van lage aantallen maligne cellen bij patiënten met een leukemie of non-Hodgkin lymfoom: gebruik van immunologische markers.

Several different techniques have been used for the detection of low numbers of malignant cells in patients with leukemia or non-Hodgkin lymphoma, e.g. cytomorphology, cytogenetics, recombinant DNA techniques and immunological marker analysis. The detection limit of most techniques, however, is not lower than 1% (i.e. 1 malignant cell in 100 normal cells). Most immunological markers represent differentiation antigens, which are also expressed by normal cells. Nevertheless, it is possible to use these differentiation antigens for the detection of low numbers of malignant cells, since the occurrence of positive cells outside their normal homing areas can be indicative of malignancy. A useful marker for the detection of low numbers of acute lymphoblastic leukemia (ALL) cells in the cerebrospinal fluid is terminal deoxynucleotidyl transferase (TdT). Although TdT positive cells normally occur in low frequencies in bone marrow and blood, the combined detection of TdT and a T cell marker at the single cell level, allows detection of very low numbers of T-ALL cells. The detection limit of this technique is at least 0.01%. Such a low detection limit allows the adjustment of remission and staging criteria as well as the individualization of therapy.

[Terminal deoxynucleotidyltransferase (TdT)-positive cells in cerebrospinal fluid of children with leukemia or non-Hodgkin lymphoma: implications for the diagnosis of central nervous system leukemia]. / Terminal deoxynucleotidyl transferase (TdT) positieve cellen in de liquor cerebrospinalis van kinderen met een leukemie of non-Hodgkin lymfoom: implicaties voor de diagnose centraal zenuwstelsel leukemie.

Identification of terminal deoxynucleotidyl transferase (TdT) positive cells in sites other than bone marrow, thymus, lymph nodes and peripheral blood is indicative of a TdT positive lymphoproliferative disease. We therefore employed both a TdT-immunofluorescence (IF) assay and conventional cytomorphology to examine the cells in 421 cerebrospinal fluid samples from 60 children with a TdT positive acute lymphoblastic leukemia or non-Hodgkin lymphoma, at diagnosis as well as during follow-up. The results of the TdT assay were compared with those obtained by cytomorphological analysis of the same sample. The authors conclude that the TdT-IF assay is a valuable additional tool in diagnosing TdT positive central nervous system leukemia. It offers more reliable and conclusive diagnoses than cell count and cytomorphology alone, which might avoid both under- and overtreatment of the patient.

Are maternal fertility problems related to childhood leukaemia?

An explorative case-control study was conducted in The Netherlands. The cases were obtained from a complete nationwide register of childhood leukaemia (1973-1980). Controls were matched with the cases for year of birth, sex and place of residence. Information about exposures of the mother to potential risk factors in the year before pregnancy and during pregnancy was collected via mailed questionnaires. The analyses concerned data on 519 patients with acute lymphocytic leukaemia and 507 controls. An association between maternal subfertility and childhood leukaemia might be suggested by several findings. A history of two or more miscarriages (OR 1.6; 95% Cl 1.0-2.7) and fertility problems (OR 6.0; 95% Cl 0.9-38.2) were more frequently reported among mothers of cases. The use of oral contraceptives (OC) was significantly higher (OR 1.3; 95% Cl 1.0-1.8) and the duration between discontinuation of OC and the relevant pregnancy was significantly longer. The OR for threatened abortion during the relevant pregnancy was 1.6 (95% Cl 1.0-2.6) and the related use of 'drugs to maintain pregnancy' was 1.9; 95% Cl 1.0-3.5. Among known risk factors, an increased OR for diagnostic irradiation was confirmed (OR 2.2; 95% Cl 1.2-3.8). No association between childhood leukaemia and prenatal viral infections, smoking and alcohol was found.

Human bone marrow cells positive for terminal deoxynucleotidyl transferase (TdT), HLA-DR, and a T cell marker may represent prothymocytes.

Recent evidence suggests that prothymocytes, which occur in a low frequency in murine bone marrow (BM), are already committed to thymocyte differentiation and discrete from precursor B cells as well as pluripotent hematopoietic stem cells. Furthermore, it was suggested that, in rodents, prothymocytes are positive for the nuclear enzyme terminal deoxynucleotidyl transferase (TdT) and a T cell surface antigen. The human prothymocyte has not been identified as yet. We analyzed human BM cells by double immunofluorescence staining for TdT and the T cell surface markers Tp41 (recognized by the monoclonal antibodies WT1 and 3A1), T11, T1, and T6. In the BM samples tested, neither T1+/TdT+ nor T6+/TdT+ cells were detected, but Tp41+/TdT+ and T11+/TdT+ cells were present in low frequencies. In childhood BM, the frequency was about two to five in 10,000, whereas in adult BM and regenerating BM, these cells were not always detectable, but if detected, their frequency was five- to 10-fold lower. In a triple staining, using fluorescein, rhodamine, and colloidal gold particles as labels, it appeared that all Tp41+/TdT+ cells were also positive for HLA-DR. These Tp41+/HLA-DR+/TdT+ cells were also detectable in low frequencies in the thymus, and occasionally Tp41+/TdT+ and T11+/TdT+ cells were detected in the peripheral blood (PB), suggesting a migration from the BM to the thymus via the PB. The malignant counterpart of the Tp41+/HLA-DR+/TdT+ cell was detected in a patient with acute lymphoblastic leukemia with the Tp41+/T11+/HLA-DR+/TdT+/T1-/T6- phenotype and germ-line immunoglobulin heavy chain genes. We postulate that the Tp41+/T11+/HLA-DR+/TdT+/T1-/T6- cell represents a human prothymocyte.

Common and pre-B acute lymphoblastic leukemia cells express interleukin 2 receptors, and interleukin 2 stimulates in vitro colony formation.

The role of interleukin 2 (IL 2) as a possible regulator of in vitro proliferation and differentiation of non-T acute lymphoblastic leukemia (ALL) cells was investigated. For this purpose, leukemic cells from the blood or bone marrow of eight untreated patients with common or pre-B ALL were analyzed using the anti-Tac monoclonal antibody (reactive with the IL 2 receptor) in indirect immunofluorescence. The receptors for IL 2, which were initially absent from the cell surface, were induced on high percentages of the ALL cells after the in vitro exposure to the lectin phytohemagglutinin or the phorbol ester 12-O-tetradecanoylphorbol-13-acetate in six patients, suggesting that the cells had become sensitive to IL 2. In colony cultures to which feeder leukocytes and IL 2 had been added, colony growth was obtained in five of eight cases. Whereas the cells from one patient formed colonies in the absence of exogenous stimuli, the cells from others were dependent on the addition of feeder leukocytes plus IL 2. In the latter cases, feeder leukocytes alone, releasing some IL 2, stimulated growth suboptimally at different cell concentrations. Their stimulative effect was significantly enhanced when leukocyte-derived IL 2 or pure recombinant IL 2 was supplemented. Alone, IL 2 (up to 500 U/mL) did not support colony formation. Apparently, IL 2 and feeder leukocytes are both required for the induction of colonies in these cases of ALL. From cell sorting of fluorescent anti-common ALL antigen (CALLA) stained cells it appeared that colonies descended from cells with high as well as low or negative CALLA expression. Immunophenotyping demonstrated the presence of the original leukemia markers on colony cells, but was not indicative of maturation of ALL toward more differentiated B cells. We suggest that IL 2 can stimulate the in vitro proliferation of certain neoplastic B lymphocyte progenitors.

Childhood leukemia and parental occupation. A register-based case-control study.

To explore possible etiologic factors of childhood leukemia, a case-control study was performed in the Netherlands. Cases were selected from a complete nationwide register of cases of childhood leukemia which were diagnosed between 1973 and 1980. Controls were matched with cases for year of birth, sex, and place of residence at the time of diagnosis. Information about possible exposures was collected by a postal questionnaire addressed to the parents. This report concerns the results of the analysis of parental occupations and occupational exposures for 519 children with acute lymphocytic leukemia and 507 controls. During pregnancy, more mothers of patients were working in "hydrocarbon-related" occupations; relative risk (RR) = 2.5 (95% confidence interval (CI) = 0.7-9.4). Likewise, greater occupational exposure to chemicals (paint, petroleum products, and unspecified chemicals) during pregnancy was found for mothers of patients (RR = 2.4, 95% CI = 1.2-4.6). The kind of work being performed by the mothers one year before diagnosis did not differ between cases and controls. For the fathers, no relationship was found between a hydro-carbon-related occupation or occupational exposure to chemicals and leukemia in the offspring. Adjustment for birth order, social class, and degree of urbanization did not materially change the relative risks.