Analysis of mutations in the GM-CSF receptor alpha coding sequence in patients with acute myeloid leukaemia and haematologically normal individuals by RT-PCR-SSCP.

Mutations of signal transducing molecules such as Ras have been shown to confer a growth advantage in leukaemic blasts and contribute to the pathogenesis of the disease. Alterations of signal transducing molecules other than Ras may play a role in leukaemogenesis. Knowledge of such mutations could also further our understanding of the normal signalling processes. We have therefore studied the coding sequence of the GM-CSF receptor alpha chain (GM-CSFR alpha) in patients with acute myeloid leukaemia (AML) and non-AML controls using single strand conformation polymorphism (SSCP) analysis. Abnormalities were detected in 4/32 AML patients (13%) and 2/15 non-AML controls (13%). Direct sequencing of PCR products revealed five different base substitutions. Three were conservative, two caused amino acid changes. The base substitution leading to amino acid change alanine to glycine at position 17 was found in both an AML patient and a control. It lies in the signal sequence and does not affect the mature protein. The other base change altering arginine to glutamine at position 164 is unlikely to influence the receptor structure as this structural position in the chain is not well conserved in members of the cytokine receptor family. Both amino acid changes were constitutive alterations as they could be demonstrated in the patients' children. The base changes described in the AML patients thus represent polymorphisms and do not contribute to the pathogenesis of AML.

The beta subunit common to the GM-CSF, IL-3 and IL-5 receptors is highly polymorphic but pathogenic point mutations in patients with acute myeloid leukaemia (AML) are rare.

The intracytoplasmic tail of the granulocyte-macrophage colony-stimulating factor receptor (GM-CSFR) beta c chain is essential for the activation of ligand-mediated signal transduction pathways in myeloid cells. Alterations in this region could deregulate normal signalling processes. We have therefore used RT-PCR-SSCP analysis of the receptor tail to look for point mutations in RNA from 35 patients with acute myeloid leukaemia (AML) and 10 haematologically normal controls. Patterns differing from those of the haemopoietic cell line TF-1 were detected in 25/35 (71%) AML patients and 8/10 (80%) normal controls. A total of six base substitutions were identified by sequencing. Three were conservative for the amino acid involved, three led to amino acid differences, valine652-->methionine, glycine647-->valine and proline603-->threonine. One alteration was found only in a normal control, the other five were all found in both AML patients and normal controls suggesting that they were DNA polymorphisms. Two substitutions were particularly common with allele frequencies of 0.23 (G1972-->A, unchanged proline648) and 0.13 (C1306-->T, unchanged serine426). These results indicate that the GM-CSFR beta c chain is highly polymorphic but point mutations of the intracytoplasmic tail do not appear to contribute frequently to the pathogenesis of AML.

Analysis of the coding sequence for the GM-CSF receptor alpha and beta chains in patients with juvenile chronic myeloid leukemia (JCML).

Peripheral blood granulocyte-macrophage progenitors (CFU-GMs) from patients with juvenile chronic myeloid leukemia (JCML) are able to proliferate spontaneously in the absence of exogenous growth factors and studies have shown that these progenitors display a hypersensitive growth response to GM-colony-stimulating factors (CSFs) in culture. We screened RNA from six patients with JCML for mutations in the GM-CSF receptor (GM-CSFR) coding sequence using RT-PCR-SSCP. Altered patterns were found in five patients for the GM-CSFR alpha chain, and in five patients for the beta chain. Two nucleotide substitutions accounted for all alpha chain abnormalities; one was conservative for Val333 and the other caused an Ala17-->Gly substitution. Both had previously been detected in normal controls. Sequencing of beta chain abnormalities revealed four base substitutions. Three were previously described polymorphisms, one causing a Pro603-->Thr substitution and two conservative point mutations involving Ser426 and Pro648. A further nucleotide mutation, which resulted in a Glu249-->Gln substitution, was also found but is not thought to be of pathological significance. Polymorphisms of the GM-CSFR alpha and beta chains are common, but pathogenic point mutations of the GM-CSFR are infrequent in patients with JCML and are unlikely to be involved in the hypersensitivity to GM-CSF demonstrated by progenitor cells.

Effects of NO2 on chronic bronchitics.

The acute influence of NO2 on mechanics of breathing and respiratory gas exchange was investigated in a total of 111 subjects, aged 25 to 74 years, with chronic nonspecific lung disease (CNSLD). They breathed NO2-air mixtures containing 0.5 to 8.0 ppm NO2 for up to 15 to 60 min. Additionally in nine subjects the protective action of atropine, meclastine, and orciprenaline was investigated. While the alveolar PO2 remained constant during inhalation of 5 and 4 ppm NO2, a significant decrease of the arterial PO2 and a corresponding increase of the arterial to alveolar PO2 gradients occurred. Inhalation of 2 ppm NO2 had not such an effect. Inhalation of NO2 at concentrations down to 1.5 ppm resulted in a significant increase of airway resistance. Lower concentrations had no significant effect. Prolongation of the exposure period from 15 to 60 min at a NO2 concentration of 5 ppm did not result in a more pronounced disturbance of the respiratory gas exchange for oxygen beyond the extent observed after exposure to 5 ppm NO2 for 15 min. Meclastine, in comparison with orciprenaline and atropine, showed a pronounced protective effect on the negative impact of NO2 on respiratory gas exchange and airway resistance. It is concluded that NO2 may act by release of histamine, causing a bronchiolar, alveolar, and interstitial edema, thus differing from irritant air pollutants like SO2, where reflex bronchoconstriction causes in some bronchitics dramatic increases of airway resistance at similar low concentrations.

Interferon-gamma inhibits the efficacy of interleukin 1 to generate a Th2-cell biased immune response induced by Leishmania major.

Splenic adherent cells from L. major-infected resistant and susceptible mice were restimulated in vitro and analyzed for the expression of IL-1 activity. Three weeks or later after infection, cells from parasite infected susceptible BALB/c mice produced substantially more IL-1 activity than those from non-infected controls or from L. major-infected resistant C57BL/6 animals. More than 95% of the IL-1 bioactivity was mediated by IL-1 alpha, as determined by blocking experiments with an anti-IL-1 alpha antiserum. The strain-specific differences in IL-1 production correlated with different accumulation of IL-1 producing adherent cells in the spleens of infected animals, but also with different IL-1 producing capacity on a per cell basis. When adherent cells were mixed with syngeneic IFN-gamma producing CD4+ T lymphocytes from L. major-infected C57BL mice or from animals that had been pretreated with anti-CD4 monoclonal antibody prior to infection, the level of detectable IL-1 decreased depending on the number of T cells added. This inhibition could be blocked completely with an anti-IFN-gamma antibody. No such effect was seen, when CD4+ cells were used that were derived from parasite-infected BALB/c mice and did not produce IFN-gamma. In contrast to L. major, L. donovani antigen not only failed to induce IL-1 production, but also dose-dependently suppressed the IL-1 activity elaborated by L. major antigen. We conclude from these data that IFN-gamma effectively inhibits the efficacy to IL-1 to generate to Th2-cell biased immune response induced by L. major. A T cell independent and as yet unknown mechanism to inhibit the IL-1 response is used by L. donovani.

Experimental studies on hydrocarbon neuropathies induced by methyl-ethyl-ketone (MEK).

An outbreak of neuropathies among Berlin solvent sniffers was closely related to the denaturation by methyl-ethyl-ketone (MEK) of the mixture used. The solvent was composed of n-hexane, toluene and ethyl-acetate. Nervous system responses to chronic repeated exposure to 10,000 ppm pure n-hexane, 10,000 ppm MEK/n-hexane (ratio 1:9) and 6000 ppm pure MEK were investigated in rats. Motor neuropathy of the dying back type with giant swelling of axons in the peripheral and central nervous system developed in animals exposed to MEK/n-hexane and n-hexane. Severe potentiation of n-hexane neurotoxicity and shortened onset of morphological and clinical signs were demonstrated in animals exposed to MEK/n-hexane. MEK alone did not produce neuropathy under these conditions. The findings suggest that commercial solvent mixtures containing MEK/n-hexane should be avoided.

Nervous system responses of rats to subchronic inhalation of N-hexane and N-hexane + methyl-ethyl-ketone mixtures.

The effects of long-term continuous and intermittent inhalation exposure to selected concentrations of n-hexane and mixtures of n-hexane and methyl-ethyl-ketone (MEK) on the nervous system of rats were investigated. Animals exposed continuously (24 h/d, 7 d/week) to 500 ppm n-hexane displayed complete hindlimb paralysis after 9 weeks. Histological examination showed hexacarbon-specific axonal lesions in peripheral nerves, particularly tibial branches to calf muscles, and in the gracile tract at cervical levels of the spinal cord. Similar clinical and pathological signs of neuropathy appeared one week earlier in animals treated with a mixture of 500 ppm n-hexane/MEK (4:1 or 3:2) and 5 weeks earlier with 700 n-hexane/MEK mixture (5:2) or 700 ppm of n-hexane alone. Rats exposed to the latter concentrations intermittently, 8 hours daily for 40 weeks, did not develop clinical or morphological signs of a hexacarbon neuropathy.

Simultaneous exposure of Chinese hamsters to ethanol and cigarette smoke: cytogenetic aspects.

Chinese hamsters (Cricetulus griseus) were treated with ethanol, with cigarette smoke and with both. During the experimental period of 12 weeks a control group of animals (c) received water ad libitum, another water drinking group received a cigarette smoke treatment during the last 4 weeks (S). Another group received 20% (v/v) ethanol during the whole experimental period as the only liquid supply (E), and one group with the same ethanol treatment was simultaneously treated with cigarette smoke during the last 4 weeks of the experiment (ES). The investigation of bone marrow cells after 12 weeks with regard to chromosomal aberrations and sister chromatid exchanges revealed no effects. A high mitotic activity was found in the smoke treated groups.

The serologic response of horses to equine arteritis virus as determined by competitive enzyme-linked immunosorbent assays (c-ELISAs) to structural and non-structural viral proteins.

In an effort to further characterize the humoral immune response of horses to equine arteritis virus (EAV), direct and competitive enzyme-linked immunosorbent assays (c-ELISAs) were developed using monoclonal and polyclonal anti-sera to structural (G(L), N and M) and non-structural (nsp1) viral proteins. A nsp1-specific monoclonal antibody was produced to facilitate development of a c-ELISA to this protein. Data obtained using the various c-ELISAs confirm that the M protein is a major target of the antibody response of horses to EAV. However, none of the c-ELISAs that were developed were as sensitive in detecting EAV-specific antibodies in horse sera as the existing serum neutralization test.

Effects of lipoic acid in hexacarbon-induced neuropathy.

The effects of lipoic acid on hexacarbon neurotoxicity in rats were investigated. Rats were exposed by inhalation to n-hexane for 24 hours/day, 7 days/week, up to a total period of 9 weeks. Eight animals were exposed to 700 ppm n-hexane only, and eight animals were exposed to 700 ppm n-hexane and additionally received 100 mumol/kg lipoic acid PO daily. Clinical status of the animals was evaluated by examination of general condition, motor performance tests and neurophysiological measurements of caudal nerve motor conduction velocity. Results showed that animals exposed to 700 ppm n-hexane developed severe motor neuropathy leading to paralysis by the 6th week. Motor distal latencies of these animals were severely prolonged. In contrast, in animals treated with lipoic acid the onset of motor neuropathy was delayed for approximately 3 weeks as could be demonstrated by motor performance tests and measurements of motor distal latencies.

Anther and pollen development in some species of Poaceae (Poales).

Anther and pollen development were studied in Olyra humilis Nees, Sucrea monophylla Soderstr, (Bambusoideae), Axonopus aureus P. Beauv., Paspalum polyphyllum Nees ex Trin. (Panicoideae), Eragrostis solida Nees, and Chloris elata Desv. (Chloridoideae). The objective of this study was to characterise, embryologically, these species of subfamilies which are considered basal, intermediate and derivate, respectively. The species are similar to each other and to other Poaceae. They present the following characters: tetrasporangiate anthers; monocotyledonous-type anther wall development, endothecium showing annular thickenings, secretory tapetum; successive microsporogenesis; isobilateral tetrads; spheroidal, tricellular, monoporate pollen grains with annulus and operculum. Nevertheless, the exine patterns of the species studied are distinct. Olyra humilis and Sucrea monophylla (Bambusoideae) show a granulose pattern, whereas in the other species, it is insular. In addition, Axonopus aureus and Paspalum polyphyllum (Panicoideae) have a compactly insular spinule pattern, while Chloris elata and Eragrostis solida (Chloridoideae) show a sparsely insular spinule pattern. The exine ornamentation may be considered an important feature at the infrafamiliar level.

Ultrastructural alteration of intrapulmonary nerves after exposure to organic solvents. A contribution to 'sniffers disease'.

The effects of the solvents n-hexane, butanone (methyl-ethyl-ketone, MEK) and a mixture of both in the intrapulmonary nerve system of rats were studied by light and electron microscopy. The alteration in the fine structures of the tissue consisted in a disseminated swelling of axons due to a striking multiplication of neurofilaments. Nonspecific axonal alterations could be demonstrated as well. The latter consisted in clusters of phospholipid material within the axoplasm of nerve fibers and the cytoplasm of Schwann cells plus an accumulation of glycogen granules in the axoplasm. Additionally, single degenerative changes of Schwann cells were observed. An enzyme-associated metabolic damage with a concomitant impairment of axonal flow is discussed as a possible underlying pathomechanism.

Experimental data on the neurotoxicity of methyl-ethyl-ketone (MEK).

A severe potentiating effects of methyl-ethyl-ketone (MEK) on the peripheral and central neurotoxicity of n-hexane could be demonstrated in a chronic inhalation study in rats.

Ultrastructural alteration of the alveolar epithelium after exposure to organic solvents.

Adult rats were exposed to the solvents n-hexane and methylethylketone (MEK) in different concentrations. Lung tissue was examined systematically after various periods by electron microscopy. The direct toxic effect to pneumocytes could be demonstrated as definite regressive alterations, such as fatty degeneration and changes of lamellar bodies of type II pneumocytes as well as increased detachment of cells. Besides these findings, after chronic inhalation of solvents conspicuous aggregation of lamellar discharge material of type II pneumocytes can be seen, and probably, as a result of an irritated fat metabolism, large lysosome-like bodies with densely packed lipid material appear in type I pneumocytes. The most distinguished changes could be demonstrated after exposure to a mixture of n-hexane and MEK, while they were less obvious after n-hexane alone. The observation suggests a profound enzymatic irritation of metabolism.

Potentiation of hexacarbon-neurotoxicity by methyl-ethyl-ketone (MEK) and other substances: clinical and experimental aspects.

Hexacarbon-containing solvents can induce specific functional and morphological disorders in the peripheral and central nervous system. The neurological manifestations consist in polyneuropathy syndromes and neuromyelopathies. Such clinical pictures have been observed both after exposure at industrial work and after abuse of hexacarbon-containing solvents as narcotics. An outbreak of neuropathies among solvent-sniffers after denaturation of the hexacarbon-containing solvent with methyl-ethyl-ketone led to the assumption that the neurotoxic properties of n-hexane can be considerably potentiated with methyl-ethyl-ketone. Experimental studies on laboratory rats have shown that solvent mixtures with n-hexane and methyl-ethyl-ketone bring about an earlier onset of clinical-neurological deficits and hexacarbon-specific morphological changes than exposure to n-hexane alone. First results of a combined exposure to lead and n-hexane solvents also indicate an intensified effect of the combined neurotoxins.

Relationship between the airway response to inhaled sulfur dioxide, isocapnic hyperventilation, and histamine in asthmatic subjects.

To determine whether bronchoconstriction induced by sulfur dioxide can be predicted by the airway response to inhaled histamine, we exposed on two days 46 patients with asthma to air or 0.5 ppm SO2. The exposure protocol consisted of 10 min of tidal breathing followed by 10 min of isocapnic hyperventilation at a rate of 30 l/min. Airway response was measured before (baseline) and after hyperventilation in terms of specific airway resistance, SRaw. Exposure to air increased baseline mean (SD) SRaw from 6.27 (2.12) to mean (SD) maximum post-hyperventilation SRaw of 9.10 (4.38) cmH2O*s (P less than 0.0001). Exposure to SO2 increased mean (SD) baseline SRaw from 6.93 (3.29) to mean (SD) maximum post-hyperventilation SRaw of 18.21 (18.69) cmH2O*s (P less than 0.0001). Mean (SD) effect of SO2 defined as difference between maximum post-hyperventilation SRaw after SO2 versus air was 9.11 (16.14) cm H2O*s. When evaluated individually, 26 and 34 of the 46 patients showed an airway response to hyperventilation of air and SO2, respectively. Airway response to histamine was determined as the histamine concentration necessary to increase specific airway resistance by 100%, PC100SRaw. The airway response after SO2 and PC100SRaw showed a weak but significant correlation (R = -0.48), whereas the responses to hyperventilation and SO2 did not correlate. We suggest that the mechanisms by which histamine and SO2 exert their bronchomotor effects are different and that in asthmatic patients the risk of pollutant-induced asthmatic symptoms can be poorly predicted by histamine responsiveness.