Susceptibility of autologous target cells to lysis by lymphokine-activated effectors from interferon-α-treated chronic myelogenous leukaemia patients

Summary Chronic myelogenous leukemia (CML) patients in chronic phase display compromised lymphokine-activated killer (LAK) cell induction, which is partly restored after therapy with interferon . However, the relative resistance of the leukemic cells from these patients to autologous or allogeneic LAK lysis is not affected by this treatment. In an attempt to render CML cells more susceptible to lysis or cytostasis, they were precultured in serum-free medium with or without recombinant growth factors. In eight patients studied, interleukin-3 (IL-3) significantly enhanced the spontaneous short-term (6-day) proliferation of CML cells, with retention of ability to form colonies in methylcellulose. Culture in either medium alone or IL-3 led to a significant enrichment of CD14⁺ and CD33⁺ cells but to a reduction in CD34⁺ cells. In contrast, culture of the same cells in IL-2 (to generate autologous LAK activity) resulted in a loss of CD14⁺ and CD33⁺ as well as CD34⁺ cells but in a significant increase in CD3⁺ and CD56⁺ cells. Despite similarities in their phenotypes, IL-3 cultured cells but not those cultured in medium alone acquired susceptibility to lysis by the IL-2-cultured autologous LAK cells. These results may have significance for the design of novel combination immunotherapy in CML.This work was supported in part by the Deutsche Forschungsgemeinschaft (SFB 120)     

The achondroplasia gene is not linked to the locus for neurofibromatosis 1 on chromosome 17

Summary We have investigated genetic linkage of von Recklinghausen neurofibromatosis (NF1) and achondroplasia (ACH) using chromosome-17 markers that are known to be linked to NF1. Physical proximity of the two loci was suggested by the report of a patient with mental retardation and the de novo occurrence of both NF1 and ACH. Since the chance of de novo occurrence of these two disorders in one individual is 1 in 600 million, this suggested a chromosomal deletion as a single unifying molecular event and also that the ACH and NF1 loci might be physically close. To test this, we performed linkage analysis on a three-generation family with ACH. We used seven DNA probes that are tightly linked to the NF1 locus, including DNA sequences that are known to flank the NF1 locus on the centromeric and telomeric side. We detected two recombinants between the ACH trait and markers flanking the NF1 locus. In one recombinant, the flanking markers themselves were nonrecombinant. Multi-point linkage analysis excluded the ACH locus from a region surrounding the NF1 locus that spans more than 15cM (lod score < -2). Therefore, analysis of this ACH pedigree suggests that the ACH locus is not linked to the NF1 locus on chromosome 17.     

The role of carrier ATPases and neuromediators in neurological disorders

Physiological and biochemical processes which take place in the nervous system at stroke and neurotrauma are reviewed, and the experience of using low doses of steroid derivatives with piridamole in the treatment of central nervous system (CNS) disorders is summarized. ATPases (including Na,K-ATPase) are reported to play an important role in CNS functioning, the correlation between Na,K-ATPase activity and the extent of CNS injury is revealed. The use of NMR-spectroscopy method for investigation of brain and spinal cord condition in vivo is suggested.     

Endo-exonuclease of Aspergillus nidulans

Endo-exonuclease (EE) has been found in both active and inactive, but trypsin-activatable, forms in Aspergillus nidulans. Active EE was present mainly in nuclei, mitochondria, and vacuoles, while trypsin-activatable EE was mainly in the cytosol. The active form accounts for over 90% of the neutral deoxyribonuclease activity extracted from mycelia. A single strand (ss) DNA-binding EE associated with a 28 kilodalton (kDa) polypeptide was partially purified and characterized. It was found to closely resemble, in size and enzymological properties, the ss-DNA-binding EE previously purified from Neurospora crassa. Aspergillus nidulans EE was also found to be immunochemically related to the N. crassa EE and, like that enzyme, was probably derived from a polypeptide of 90 kDa or larger through proteolysis during extraction and purification. It had divalent metal ion-dependent (Mg2+, Mn2+, or Zn2+) activity on both DNA and RNA, which ultimately produced small 5'-P-terminated oligonucleotides. The nuclease activity was mixed endo- and exo-nucleolytic with ss-DNA as substrate, but largely exonucleolytic with double strand (ds) DNA. Superhelical phi X-174 DNA was nicked by EE to form relaxed circular and then linear ds-DNA, which was rapidly degraded to shorter fragments. Linearized pBR322 DNA was extensively nicked internally under conditions where there was relatively low exonuclease activity, but this nicking required that 5'-P-termini be present on the linear ds-DNA. The levels of active EE found in extracts of two recombination-deficient mutants of A. nidulans, uvsC and uvsE, dit not differ significantly from those in extracts of the wild type.     

Differential methylation of the hypervariable locus DXS255 on active and inactive X chromosomes correlates with the expression of a human X-linked gene

Consistent differences in methylation of particular cytosine residues in the DNA of active and inactive X chromosomes can be used for rapid, direct analysis of X-inactivation patterns in different female tissues. We have studied methylation of the highly polymorphic DXS255 locus in tissues from patients with deficiency of the E1 alpha subunit of the pyruvate dehydrogenase complex in whom the results can be correlated directly with total enzyme activity, levels of immunoreactive protein, and patterns of cell mosaicism. The results confirm that methylation of the DXS255 locus correlates with X-chromosome expression. In patients and normal controls, the pattern of X inactivation varied widely from tissue to tissue and often deviated markedly from a 50:50 proportion. These deviations are likely to reflect small numbers of tissue-specific stem cells at the time of random X inactivation and cannot be taken alone as evidence for selection or "nonrandom" inactivation.     

Dynamic changes in optic fiber terminal arbors lead to retinotopic map formation: an in vivo confocal microscopic study

Dynamic remodeling of retinal ganglion cell terminal arbors has been proposed to contribute to formation of the topographically ordered retinotectal projection. To test this directly, the growth of individual terminal arbors was observed in live X. laevis tadpoles using a confocal microscope to visualize their complex three-dimensional structure. During initial development, nasal and temporal retinal arbors covered overlapping tectal areas. Despite subsequent remodeling, the dimensions and positions of the temporal arbors remained relatively stable. In contrast, the nasal arbors grew caudally, as they extended caudal branches and retracted rostral branches. These results suggest that differences in the remodeling of the nasal and temporal arbors lead to the emergence of retino-topography along the rostrocaudal axis of the tectum. All the terminal arbors were dynamic, including those with stable dimensions, suggesting that continual remodeling of arbors may be a universal feature of neuronal projections.     

Identification of rat cell lines that preferentially express insulin-like growth factor binding proteins rlGFBP-1, 2, or 3.

The bioavailability and action of the insulin-like growth factors (IGFs) are determined by specific IGF-binding proteins (IGFBP) to which they are complexed. Complementary DNA clones have been isolated that encode three related IGFBPs: human IGFBP-1 (hIGFBP-1), human IGFBP-3 (hIGFBP-3), and rat IGFBP-2 (rIGFBP-2). IGFBP-1 and IGFBP-3 are regulated differently in human plasma, suggesting that they have different functions. In order to study the molecular basis of the regulation of the different IGFBPs, we have identified a panel of rat cell lines that express a single predominant binding protein and developed an assay strategy to distinguish the different binding proteins. Proteins in conditioned medium were examined by ligand blotting, and by immunoprecipitation and immunoblotting using antibodies to rIGFBP-2 and hIGFBP-1; RNAs were hybridized to cDNA probes for rIGFBP-2 and hIGFBP-1. 1) C6 glial cells and B104 neuroblastoma cells express an approximately 40 kilodalton (kDa) glycosylated binding protein that most likely represents rIGFBP-3, the binding subunit of the 150 kDa IGF: binding protein complex in adult rat serum. The C6 and B104 binding proteins do not react with antibodies to rIGFBP-2, and RNAs from C6 and B104 cells do not hybridize to cDNA probes for rIGFBP-2 or hIGFBP-1. 2) BRL-3A, Clone 9, and TRL 12-15 cell lines derived from normal rat liver express rIGFBP-2, a 30 kDa nonglycosylated IGF-binding protein that is recognized by antibodies to rIGFBP-2 but not by antibodies to hIGFBP-1. RNAs from these cells hybridize to a rIGFBP-2 cDNA probe, but not to a hIGFBP-1 probe. 3) H35 rat hepatoma cells express a 30 kDa nonglycosylated IGFBP that is presumptively identified as rIGFBP-1. It does not react with antibodies to rIGFBP-2, but is recognized by polyclonal and monoclonal antibodies to hIGFBP-1. RNA from H35 cells hybridizes to a hIGFBP-1 cDNA probe, but not to a rIGFBP-2 probe. Expression of rIGFBP-1 by the H35 cell line has enabled us to establish and validate specific assays for this protein that allow us to study its regulation in intact rats. Identification of a panel of rat cell lines expressing specific IGFBPs should be useful in elucidating the molecular mechanisms of IGFBP regulation.     

Uptake and degradation of hyaluronan in lymphatic tissue.

Afferent lymph vessels entering popliteal lymph nodes of sheep were infused with [3H]acetyl-labelled hyaluronan of high Mr (4.3 x 10(6)-5.5 x 10(6)) and low Mr (1.5 x 10(5)). Analysis of efferent lymph and of residues in the nodes showed that hyaluronan presented by this route is taken up and degraded by lymphatic tissue. Labelled residues isolated in node extracts by gel chromatography and h.p.l.c. included N-acetylglucosamine, acetate, water and a fraction provisionally identified as N-acetylglucosamine 6-phosphate. Between 48 and 75% of the infused material was unrecovered, and had been presumably eliminated through the bloodstream as diffusible residues. Rates of degradation reached as high as 43 micrograms/h in a node of 2 g wt. infused with 56 micrograms/h. Some HA passed into efferent lymph and some was detected in the nodes, but fractions of Mr greater than 1 x 10(6) were not found in either. It is concluded that the amounts and Mr values of hyaluronan released from the tissues into peripheral lymph can be significantly underestimated by analysis of efferent lymph, i.e. lymph that has passed through lymph nodes. A substantial role in the normal metabolic turnover of at least one major constituent of intercellular matrix and connective tissue may now be added to the established functions of the lymphatic system.     

Diagnosis of alpha 1-antitrypsin deficiency by enzymatic amplification of human genomic DNA and direct sequencing of polymerase chain reaction products.

We have compared sequencing of cloned "polymerase chain reaction" (PCR) products and the direct sequencing of PCR products in the examination of individuals from six families affected with alpha 1-antitrypsin (AAT) deficiency. In families where paternity was in question we confirmed consanguinity by DNA fingerprinting using a panel of locus-specific minisatellite probes. We demonstrate that direct sequencing of PCR amplification products is the method of choice for the absolutely specific diagnosis of AAT deficiency and can distinguish normals, heterozygotes and homozygotes in a single, rapid and facile assay. Furthermore, we demonstrate the reproducibility of the PCR and a rapid DNA isolation procedure. We have also shown that two loci can be simultaneously amplified and that the PCR product from each locus can be independently examined by direct DNA sequencing.