[Pneumonitis secondary to the inhalation of isocyanates. An analysis of 2 cases]

We present two patients with diffuse interstitial lung disease attributed to two different forms of presentation of pneumonitis due to inhalation of isocyanates. The first case was acute and accidental and the second was due to longer workplace exposure. In both cases, clinical, radiological and lung function findings as well as results of bronchoalveolar lavage were similar to those of hypersensitivity pneumonitis triggered by organic agents.

Long-term rat survival after malignant brain tumor regression by retroviral gene therapy

Total regression of malignant brain tumors was observed in Wistar rats after retrovirus-mediated gene therapy. Tumors were induced by inoculation of C6 rat glioblastoma cells to a specific location in the rat brain and the tumors that developed were visualized by magnetic resonance imaging (MR). Retroviral vectors were constructed from a defective murine retrovirus to which the thymidine kinase (tk 1) gene from herpes simplex was added (HSV1tk). The vectors produced therapeutic viruses upon their introduction into retrovirus packaging cells. Delivery of the producer cells to the tumor mass and subsequent antiherpetic treatment eradicated the tumors completely, as observed using MRI. Some of the treated animals have been followed for over 8 months and show no signs of recurrence.

The role of protein kinase C in the regulation of extracellular signal-regulated kinase by the T cell antigen receptor

The aim of this study was to explore the role of protein kinase C (PKC) in the activation of mitogen-activated protein kinases (MAPK) in T lymphocytes. The MAPK extracellular signal-regulated kinase-2 (ERK2) is activated in response to phorbol esters which stimulate PKC, by transient expression of a constitutively active ras mutant by cell activation via the G protein-coupled type 1 muscarinic acetylcholine receptor (HM1R) or in response to triggering of the T cell antigen receptor (TCR). The relative contribution of PKC to TCR and HM1R regulation of ERK2 was explored by examining the effects of a PKC inhibitor (Ro 31-8425) on ERK2 activation. The data demonstrate that phorbol ester and HM1R regulation of ERK2 was prevented by the PKC inhibitor, but that the inhibitor had no effect on ERK2 activation induced by expression of a constitutively active ras mutant p21v-Ha-ras. Furthermore, the TCR stimulates both PKC and p21ras but TCR regulation of ERK2 was only weakly suppressed by the PKC inhibitor. These data indicate that PKC has a potential but not a predominant role in TCR regulation of ERK2.

The role of Raf-1 in the regulation of extracellular signal-regulated kinase 2 by the T cell antigen receptor

Triggering of the T cell antigen receptor (TCR) complex activates the serine/threonine kinase Raf-1 whose function is necessary for TCR induction of the interleukin 2 gene. Raf-1 has been identified as a candidate mitogen-activated protein (MAP) kinase kinase kinase (MKKK) and thus has the potential to couple the TCR to the activation of the MAP kinases such as ERK2. In the present study, the role of Raf-1 in ERK2 regulation of ERK2 in T cells has been explored. A constitutively active Raf-1 kinase, v-raf, or a dominant inhibitory Raf-1 mutant were expressed transiently from the pEF BOS vector in Jurkat cells and the effects of these Raf-1 mutants on a coexpressed ERK2 reporter was assessed. The action of the constitutively active Raf-1 was to stimulate the ERK2 kinase, whereas the dominant negative version of Raf-1 inhibited the ERK2 activation induced by triggering of the TCR. These data indicate a role for Raf-1 in the regulation of ERK2 in T cells.

Ubiquitin genes and ubiquitin protein location in polytene chromosomes of Drosophila

Ubiquitin genes are found in Drosophila either as a repeat block or as gene fusions with ribosomal proteins. Here is described the location of a new repeat block in the X chromosome that is present in the strain Canton S but absent in Vallecas. There are also two ubiquitin-ribosomal protein fusion genes located at regions 97A of chromosome 3R and 31E of 2L. Using an anti-ubiquitin antibody in Drosophila polytene chromosomes it is shown that ubiquitin is mainly associated with the compact and stabilized structure that forms the bands rather than with the more decondensed and destabilized protein-DNA structure that forms interbands and puffs.

Regulation of PtdIns-3-kinase and the guanine nucleotide binding proteins p21ras during signal transduction by the T cell antigen receptor and the interleukin-2 receptor

The T cell antigen receptor (TCR) and the interleukin-2 receptor (IL-2R) are important receptors in haematopoiesis since they control the activation and growth of T lymphocytes, respectively. The term T cell activation refers to the events that occur as T cells progress from the G0 to the G1 phase of the cell cycle and is characterised by the production of a wide range of cytokines and other immunomodulators crucial for the growth and development of other haematopoietic cells. Activation also induces the T cells to express on their cell surface high affinity receptors for various cytokines which enable the T cell to respond to the different cytokines generated during an immune response. One well characterised event that occurs when mature T cells are activated is the production of the cytokine IL-2 and the acquisition by the T cell of high affinity IL-2 receptors. Interaction between IL-2 and its cellular receptor than direct T cell growth. One notable difference between TCR and IL-2R signal transduction is that the TCR regulates intracellular calcium and stimulates protein kinase C whereas the IL-2 receptor does not. The present review focuses on TCR and IL-2R regulation of two common intracellular signalling pathways: the regulation of a PtdIns-3-kinase and the activation of the guanine nucleotide binding proteins p21ras. The aim is to illustrate differences in the mechanisms that couple the TCR and IL-2R to these two signalling pathways and attempt to explain the apparent discrepancy of TCR and IL-2R regulation of shared signal transduction pathways even though these receptors mediate quite distinct biological responses.

p21ras couples the T cell antigen receptor to extracellular signal-regulated kinase 2 in T lymphocytes

It has previously been shown in T cells that stimulation of protein kinase C (PKC) or the T cell antigen receptor (TCR) induces the rapid accumulation of the active guanosine triphosphate-bound form of p21ras. These stimuli also induce the activation of extracellular signal-regulated kinase 2 (ERK2), a serine/threonine kinase that is rapidly activated via a kinase cascade in response to a variety of growth factors in many cell types. In this study, we show that p21ras is a component of the TCR signaling pathway that controls ERK2 activation. In the human Jurkat T cell line, transient expression of constitutively active p21ras induces ERK2 activation, measured as an increase in the ability of an ERK2-tag reporter protein to phosphorylate myelin basic protein. Thus, constitutively active p21ras bypasses the requirement for PKC activation or TCR triggering to induce ERK2 activation. In addition, activation of PKC or the TCR produces signals that cooperate with activated p21ras to stimulate ERK2. Conversely, expression of a dominant negative mutant of ras, Ha-ras N17, blocks ERK2 activation after TCR stimulation, indicating that endogenous p21ras function is necessary for the TCR-stimulated ERK2 activation. Taken together, these results demonstrate that the activation of p21ras is both necessary and sufficient to induce ERK2 activation in T cells.

Timing of p53 mutations during astrocytoma tumorigenesis

Using a combination of polymerase chain reaction and single-strand conformation polymorphism techniques (PCR-SSCP) we have analyzed 78 brain tumor samples (70 primary and 8 metastatic) for the presence of mutations in the conserved regions of the Tp53 (tumor p53) gene. We have found that only two groups, gliomas (exclusively in astrocytomas) and metastases, displayed Tp53 mutations. Three of eight (37.5%) metastases showed a mutant Tp53 allele accompanied by loss of the normal one. In contrast, the frequency of Tp53 mutations in the primary brain tumors examined was lower (5.7%). Although we have examined different types of primary brain tumors, Tp53 mutations were exclusively observed in both, low and high-grade astrocytomas (four of 24). The Tp53 mutations detected in astrocytic tumors appear to be correlated with the malignancy grade. The low-grade astrocytomas were heterozygous for the mutation, whereas the high-grade astrocytomas had affected the two Tp53 alleles, suggesting a two-steps model for inactivation of the p53 gene in astrocytomas. Thus, single p53 mutation seems to occur in initial stages of astrocytoma tumorigenesis; the later lost of the remaining wild-type allele appears associated with the progression towards a more malignant stage.

De novo methylation causes a tissue-specific polymorphic EcoRI pattern at the human epidermal growth factor receptor gene

A novel restriction polymorphism, probably due to tissue-specific methylation, has been identified at the human epidermal-growth-factor-receptor (EGF-R) gene. DNA isolated from smooth muscle showed altered EcoRI restriction bands when hybridized with different fragments of the EGF-R cDNA. These bands were absent in brain or leucocyte DNA samples from the same individuals. Three restriction sites, partly resistant to cleavage by EcoRI, were characterized in muscle DNA which were not clustered but instead were scattered along the gene. The flanking sequences of one of these resistant EcoRI sites were determined. This specific EcoRI site was followed by a 3'-guanosine generating a methylatable EcoRI sequence. This suggests that the failure to digest to completion these EcoRI sites was due to modification by methylation. In addition, we noted that EcoRI sites were affected at both alleles, indicating that de novo methylation changes, and not methylation events related to genomic imprinting, would cause the muscle-specific EcoRI pattern. Also abnormal restriction fragments with XbaI were observed in muscle DNA. A large number of unrelated muscle DNA samples have been analysed, and all of them displayed an identical EcoRI polymorphic pattern, suggesting that DNA modification by de novo methylation events could be functionally relevant.

Protein tyrosine kinases couple the interleukin-2 receptor to p21ras

The T cell growth factor interleukin-2 (IL-2) induces p21ras activation in T lymphocytes. We have previously shown that a protein kinase C (PKC)-mediated pathway for p21ras regulation exists in T cells and that the IL-2 receptor (IL-2R) can couple to p21ras independently of the presence of the PKC pathway for p21ras regulation. Our data show that in conditions where cellular protein tyrosine kinases (PTK) were efficiently down-regulated by pretreatment with the specific PTK inhibitor herbimycin, the IL-2-induced activation of p21ras was blocked. Herbimycin did not inhibit the PKC-mediated pathway for p21ras regulation. Thus, the data indicate that PTK are involved in the coupling of the IL-2R to p21ras.

Role of protein kinase C in T-cell antigen receptor regulation of p21ras: evidence that two p21ras regulatory pathways coexist in T cells

T-lymphocyte activation via the antigen receptor complex (TCR) results in accumulation of p21ras in the active GTP-bound state. Stimulation of protein kinase C (PKC) can also activate p21ras, and it has been proposed that the TCR effect on p21ras occurs as a consequence of TCR regulation of PKC. To test the role of PKC in TCR regulation of p21ras, a permeabilized cell system was used to examine TCR regulation of p21ras under conditions in which TCR activation of PKC was blocked, first by using a PKC pseudosubstrate peptide inhibitor and second by using ionic conditions that prevent phosphatidyl inositol hydrolysis and hence diacylglycerol production and PKC stimulation. The data show that TCR-induced p21ras activation is not mediated exclusively by PKC. Thus, in the absence of PKC stimulation, the TCR was still able to induce accumulation of p21ras-GTP complexes, and this stimulation correlated with an inactivation of p21ras GTPase-activating proteins. The protein tyrosine kinase inhibitor herbimycin could prevent the non-PKC-mediated, TCR-induced stimulation of p21ras. These data indicate that two mechanisms for p21ras regulation coexist in T cells: one PKC mediated and one not. The TCR can apparently couple to p21ras via a non-PKC-controlled route that may involve tyrosine kinases.

Population pharmacokinetics of gentamicin in premature infants

The population kinetics of gentamicin were studied in 97 newborn patients with a gestational age ranging between 28 and 43 weeks and a postnatal age ranging between 2 and 30 days undergoing routine therapeutic monitoring of their serum gentamicin levels. The individual kinetic analysis of serum drug levels was performed using a single-compartment model. The clearance and apparent distribution volume were calculated in each patient. The population model employed assumes the existence of residual variability in the serum concentrations and interindividual variability in the pharmacokinetic parameters. The effects of demographic variables on the clearance, distribution volume, and optimum daily dose of gentamicin were established using multiple linear regression. Gestational age is the best predictive variable of the clearance and the optimum dose/day in the whole population studied. In the premature infant patients, the predictive capacity increases with postconceptional age. Weight is a good predictive variable of all of the parameters, especially of the apparent distribution volume in the overall population of newborns. Analysis of the population kinetic behavior and optimum dose/day in each subgroup recommends that the interval of drug administration should be increased, keeping the same dose/day ratio, due to the tendency of the drug to accumulate its long half-life, especially in premature babies.

Analysis of different protein kinase C-dependent events in T cells from allogeneic bone marrow transplantation recipients

In order to understand the mechanisms underlying the T lymphocyte dysfunction associated to allogeneic bone marrow transplantation (BMT), we assessed two different protein kinase C (PKC) dependent events in T cells from BMT recipients: the PKC-dependent membrane expression and function of the CD69 early activation antigen; and the rapid phorbol ester-induced phosphorylation of PKC protein substrates in lysates from T cells permeabilized with digitonin, in the presence of (gamma-32P)ATP. Most BMT recipient T cells detectably expressed the CD69 surface antigen after 24 h of stimulation with either phorbol 12-myristate 13-acetate (PMA) or anti-CD3 MoAb and PMA, thus indicating that PKC activity is sufficient to induce de novo gene expression. Nevertheless, it is noteworthy that the fluorescent staining intensity with anti-CD69 MoAbs was significantly lower in BMT recipient T cells than in normal T lymphocytes, although no clear-cut correlation was found between the expression of CD69 and the proliferative capacity. However, the pattern of PMA-induced phosphoproteins analysed as early as 1 min after PKC activation in T cells from BMT recipients displaying a low response to mitogenic stimuli, was undistinguishable from that detected in T cells from healthy subjects. In all cases a major 110-kD phosphoprotein was observed, which was inducible with PMA, phorbol 12,13-dibutyrate (PDBu), 1-oleoyl-2-acetylglycerol (OAG) and a phorbol-ester-related activator of PKC (mezerein); moreover, its phosphorylation was blocked by pretreating cells with the PKC inhibitor H-7. Altogether our results suggest that the depressed mitogenic responses, which were also observed in the present study when T cells were stimulated via CD69, cannot be simply attributed to a defective PKC activity.

Interleukin (IL)-2 activation of p21ras in murine myeloid cells transfected with human IL-2 receptor beta chain

The T cell growth factor interleukin-2 (IL-2) induces p21ras activation in T lymphocytes. To determine whether the IL-2 receptor (IL-2R) can regulate p21ras when expressed in a non-T cell environment we have examined the ability of IL-2 to activate p21ras in 32D murine myeloid progenitor cells transduced with human IL-2R beta chains. These cells are denoted beta 53 cells. 32D cells normally proliferate in response to IL-3 but the expression of the IL-2R beta chain confers IL-2 responsiveness to the cells. Our data show that IL-3 is able to activate p21ras in the parental 32D cells and both IL-2 and IL-3 can stimulate p21ras in the IL-2R-expressing beta 53 clone of 32D. In T lymphocytes, activation of protein kinase C (PKC) with phorbol esters is sufficient to stimulate p21ras. However, in 32D and beta 53 cells activation of PKC with phorbol esters does not result in p21ras activation even though these cells express functional PKC. It appears, therefore, that a PKC-mediated pathway for p21ras regulation exists in T lymphocytes but not in 32D cells. The IL-2R can couple to p21ras independently of the concomitant presence of the PKC pathway for p21ras regulation. These data imply that multiple intracellular mechanisms may exist to regulate p21ras and that cells of different lineages may differ with regard to p21ras regulation.

A novel functional cell surface dimer (Kp43) expressed by natural killer cells and gamma/delta TCR+ T lymphocytes. II. Modulation of natural killer cytotoxicity by anti-Kp43 monoclonal antibody

In the present study we provide the first evidence supporting the fact that the Kp43 NK-associated cell-surface dimer may be involved in regulating MHC-unrestricted cytotoxicity. Our results indicated that incubation of IL-2-activated NK cells in a 51Cr-release assay with either the Kp43-specific mAb or its F(ab')2 fragments induced a significant cytolytic activity directed against normal autologous and allogeneic T cell blasts, which are relatively resistant to NK cell-mediated lysis. The cytotoxic effect was not observed in fresh CD3- CD16+ CD56+ Kp43+ lymphocytes and was only substantiated in IL-2-preactivated NK cells. Although stimulation with the Kp43-specific mAb did not significantly change the intracellular Ca2+ concentration, both Ca2+ and Mg2+ were required for the induction of cytotoxicity. The anti-Kp43-mediated activation of cytolysis was inhibited by anti-CD18 and CD11a mAb, whereas it was not significantly altered by either CD11b, CD11c, CD2, or LFA-3-specific mAb, rendering unlikely the participation of the latter. In contrast to these results the Kp43-specific mAb did not enhance the high levels of spontaneous cytotoxicity mediated by IL-2-activated NK cells against a panel of different tumor cell lines. An inhibitory effect mediated by anti-Kp43 mAb on the IL-2-dependent proliferation of NK cells was previously reported and appears, at least partially, secondary to the induction of an autolytic mechanism that is synergistically enhanced by anti-CD16 mAb. Altogether our results point out that interaction of the Kp43 dimer with its specific mAb is capable of inducing cytolytic activity and suggest that the molecule may play an important functional role in lymphokine-activated NK cells.

A novel functional cell surface dimer (Kp43) expressed by natural killer cells and gamma/delta TCR+ T lymphocytes. II. Modulation of natural killer cytotoxicity by anti-Kp43 monoclonal antibody

In the present study we provide the first evidence supporting the fact that the Kp43 NK-associated cell-surface dimer may be involved in regulating MHC-unrestricted cytotoxicity. Our results indicated that incubation of IL-2-activated NK cells in a 51Cr-release assay with either the Kp43-specific mAb or its F(ab')2 fragments induced a significant cytolytic activity directed against normal autologous and allogeneic T cell blasts, which are relatively resistant to NK cell-mediated lysis. The cytotoxic effect was not observed in fresh CD3- CD16+ CD56+ Kp43+ lymphocytes and was only substantiated in IL-2-preactivated NK cells. Although stimulation with the Kp43-specific mAb did not significantly change the intracellular Ca2+ concentration, both Ca2+ and Mg2+ were required for the induction of cytotoxicity. The anti-Kp43-mediated activation of cytolysis was inhibited by anti-CD18 and CD11a mAb, whereas it was not significantly altered by either CD11b, CD11c, CD2, or LFA-3-specific mAb, rendering unlikely the participation of the latter. In contrast to these results the Kp43-specific mAb did not enhance the high levels of spontaneous cytotoxicity mediated by IL-2-activated NK cells against a panel of different tumor cell lines. An inhibitory effect mediated by anti-Kp43 mAb on the IL-2-dependent proliferation of NK cells was previously reported and appears, at least partially, secondary to the induction of an autolytic mechanism that is synergistically enhanced by anti-CD16 mAb. Altogether our results point out that interaction of the Kp43 dimer with its specific mAb is capable of inducing cytolytic activity and suggest that the molecule may play an important functional role in lymphokine-activated NK cells.

Autonomous roles for the cytoplasmic domains of the CD2 and CD4 T cell surface antigens

CD2 and CD4 are single chain transmembrane T cell surface molecules that are involved in signal transduction. Chimaeric constructs from rat CD2 and CD4 antigens were expressed in the Jurkat human T cell line to examine the role of extracellular, transmembrane and cytoplasmic domains in mediating functions controlled by CD2 and CD4. The results show that the large rise in concentration of cytoplasmic free Ca2+ mediated via CD2 crosslinking is controlled by the cytoplasmic domain and does not require the CD2 transmembrane and extracellular domains. Similarly the CD4 cytoplasmic domain alone was shown to encode the specificity for binding to the p56lck tyrosine kinase and to control down-modulation of CD4 after treatment with phorbol ester. Evidence was obtained that down-modulation of CD4 occurs when p56lck dissociates from the cytoplasmic domain due to phosphorylation of Ser 405.

Relation between the increase of circulating CD3+ CD57+ lymphocytes and T cell dysfunction in recipients of bone marrow transplantation

Some patients undergoing bone marrow transplantation (BMT) persistently present increased proportions of circulating CD57+ T cells. We analysed the cell surface phenotype in peripheral blood mononuclear cells (PBMC) from 69 allogeneic and 11 autologous BMT recipients. In parallel samples from 49 patients, the proliferative response to T cell mitogens was assessed, either in the presence or absence of exogenous interleukin-2 (IL-2). PBMC samples from long-term allogeneic BMT patients with increased proportions of CD57+ cells displayed significantly (P less than 0.001) lower proliferative responses, compared with samples from patients with normal proportions of CD57+ cells and from healthy subjects. Elimination of the CD57+ population by C'-dependent lysis did not normalize the proliferative response. After positive selection by cell sorting, CD57+ cells responded poorly, but in the presence of IL-2 the proliferation appeared to be similar to that displayed by the CD57- subset and still suboptimal compared with normal controls. These data suggest that the hyporesponsiveness to mitogenic stimuli in the presence of exogenous IL-2 of PBMC from allogeneic BMT recipients cannot be simply attributed either to the putative suppressor activity of CD57+ cells, or to a poor proliferative capacity of this subset. Supporting this notion we report that PBMC from long-term autologous BMT recipients containing high proportions of CD57+ T cells respond normally to T cell mitogens.

Chromosome aberrations and urinary thioethers in smokers

Chromosome aberrations, classified as chromosome- and chromatid-type aberrations, were evaluated in 94 individuals. The concentration of thioethers in the urine was also determined. The sample consisted of 41 non-smokers (control group) and 53 smokers, 25 smoked 10-20 cigarettes/day (subgroup IIA) and 28 smoked more than 20 cigarettes/day (subgroup IIB). Our aim was to perform internal dosimetry on smokers using a cytogenetic test, and a test for urinary excretion of thioethers, in order to determine the relation between these 2 methods of dosimetry. Our results show a higher frequency of chromosome aberrations (p less than 0.0001) and a higher excretion of urinary thioethers (p less than 0.0001) in smokers as compared to non-smokers. However, linear regression between these parameters was not statistically significant. In view of the variation between different individuals with regard to the amount of urinary thioethers, it seems more accurate to perform the biomonitoring of smoking by analyzing chromosome aberrations.

Transcription at the ecdysone-inducible locus 2B5 in Drosophila

The Broad-Complex (BR-C) of D. melanogaster, mapping at the 2B5 early ecdysone puff, mediates ecdysone-induced processes. We present here the transcriptional analysis of the locus in both wild type and representative mutants. Two well defined regions are transcribed, only one of which has a pattern consistent with the proposed 2B5 located BR-C function. The 2B5 region is actively transcribed in early third instar larvae before ecdysone levels increase. Ecdysone switches this early pattern to a complex late type which requires the presence of functional BR-C product. Therefore, BR-C self-regulates its own ecdysone-induced transcription. The effect of 2B5 mutations on transcription at several intermolt, early and late puffs is also described. Null mutations at the 2B5 locus prevents ecdysone inducible transcription. This evidence supports the fact that 2B5 codes for an ecdysone-dependent transcriptional regulator.

[Diagnostic usefulness of neurospecific enolase determination in pleural fluid]

To investigate the diagnostic usefulness of the measurement of neurospecific enolase (NSE) in pleural fluid 116 consecutive patients with pleural effusion were prospectively evaluated. In 95 of them, carcinoembryonic antigen (CEA) was also measured for comparative purposes. The habit of smoking did not apparently influence the NSE levels. In the 43 malignant effusions the mean value of NSE (25.0 +/- 27.4) was significantly higher (p less than 0.001) than in benign effusions (8.7 +/- 7.1). The values above 12 ng/ml had a sensitivity of 51% for malignancy, with a specificity of only 74%. The specific sensitivity of NSE was lower than that of CEA; neither individually nor as a whole these markers modified the diagnostic yield of cytology (67%). The mean value of NSE in tuberculous pleural effusions (14.4 +/- 8.3), different from that found in malignancies (p less than 0.05), was significantly higher (p less than 0.001) than that found in other benign diseases (6.2 +/- 4.7). The results of this study demonstrate the nonspecific character of an increased level of NSE, and the low diagnostic yield of this enzyme as a pleural tumour marker.

Substrate specificity of human fibroblast stromelysin. Hydrolysis of substance P and its analogues

To probe the substrate specificity of the human metalloproteinase stromelysin (SLN), we determined values of kc/Km for the SLN-catalyzed hydrolysis of substance P (Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-MetNH2; SP; kc/Km = 1790 +/- 140 M-1 s-1), 15 analogues of SP, and 17 other peptides. We found a remarkably narrow substrate specificity for SLN: while SP and its analogues could serve as substrates for SLN (hydrolysis occurred exclusively at the Gln6-Phe7 bond), peptides that were not direct analogues could not (kc/Km less than 3 M-1 s-1). From the study of the SLN-catalyzed hydrolysis of SP and its analogues, the following findings emerged: (1) Decreasing the length of SP results in decreases in kc/Km. (2) Conservative amino acid replacements near the scissle bond of SP decrease kc/Km. (3) The SP analogue in which Gly9 is replaced with sarcosine (N-methylglycine) is not hydrolyzed by SLN (kc/Km less than 3 M-1 s-1). (4) Several SP analogues that are not hydrolyzed by SLN are inhibitors of the enzyme. The complexes formed from interaction of SLN with these peptides have dissociation constants that are similar to the Km value for the complex of SLN and SP. Combined, these results suggest that SLN uses the energy that is available from favorable interactions with its substrate to stabilize catalytic transition states but not the Michaelis complex or other stable-state complexes.

Deficient protein kinase C-dependent Na+/H+ exchanger activity in T cells from bone marrow transplantation recipients

The early Na+/H+ exchanger-mediated alkalinization of intracellular pH (pHi) was analyzed in peripheral blood T cells from 23 bone marrow transplantation (BMT) recipients (17 allogeneic and 6 autologous) and a group of 13 healthy controls, in response to stimulation of protein kinase C (PKC) with a phorbol ester. In parallel we evaluated the proliferative response of peripheral blood T cells to an anti-CD3 mAb in the presence of either IL-2 or PMA. The pHi increase (delta pHi) observed in control samples ranged from 0.14 to 0.23 pH units (X +/- SD = 0.17 +/- 0.03). In 10 allogeneic and four autologous BMT recipients the delta pHi was under the lower limit of the control range (range: 0.01 to 0.09, X +/- SD = 0.05 +/- 0.02), whereas the remaining nine cases responded similarly to control samples (range: 0.14 to 0.24, X +/- SD = 0.17 +/- 0.04). The response of the Na+/H+ antiporter to a PKC-independent osmotic stimulation appeared to be normal, thus indicating that the intrinsic Na+/H+ exchanger activity was unaltered. The anti-CD3 induced proliferative response of the group of samples displaying a suboptimal delta pHi, was significantly lower (p less than 0.01) than that detected in control samples. T cell proliferation in samples from BMT recipients displaying a normal delta pHi was undistinguishable from the control group (p greater than 0.05). Our results provide the first evidence for a defective early metabolic event, closely related to PKC activity, in T cells from BMT recipients displaying a low proliferative response to T cell mitogens.

Deficient protein kinase C-dependent Na+/H+ exchanger activity in T cells from bone marrow transplantation recipients

The early Na+/H+ exchanger-mediated alkalinization of intracellular pH (pHi) was analyzed in peripheral blood T cells from 23 bone marrow transplantation (BMT) recipients (17 allogeneic and 6 autologous) and a group of 13 healthy controls, in response to stimulation of protein kinase C (PKC) with a phorbol ester. In parallel we evaluated the proliferative response of peripheral blood T cells to an anti-CD3 mAb in the presence of either IL-2 or PMA. The pHi increase (delta pHi) observed in control samples ranged from 0.14 to 0.23 pH units (X +/- SD = 0.17 +/- 0.03). In 10 allogeneic and four autologous BMT recipients the delta pHi was under the lower limit of the control range (range: 0.01 to 0.09, X +/- SD = 0.05 +/- 0.02), whereas the remaining nine cases responded similarly to control samples (range: 0.14 to 0.24, X +/- SD = 0.17 +/- 0.04). The response of the Na+/H+ antiporter to a PKC-independent osmotic stimulation appeared to be normal, thus indicating that the intrinsic Na+/H+ exchanger activity was unaltered. The anti-CD3 induced proliferative response of the group of samples displaying a suboptimal delta pHi, was significantly lower (p less than 0.01) than that detected in control samples. T cell proliferation in samples from BMT recipients displaying a normal delta pHi was undistinguishable from the control group (p greater than 0.05). Our results provide the first evidence for a defective early metabolic event, closely related to PKC activity, in T cells from BMT recipients displaying a low proliferative response to T cell mitogens.

Mutation mapping of the 2B5 ecdysone locus in Drosophila melanogaster reveals a long-distance controlling element

Mutations at the Broad-Complex, a key gene triggering metamorphosis in Drosophila melanogaster, were mapped at the DNA level. The Broad-Complex includes two mutually complementing allelic classes, br and l(1)2Bc, both of which can associate to insertions at the same intron. Alterations spreading over 50 kilobases upstream from the transcription unit also disrupt br but not l(1)2Bc function.

High toxic efficiency of ricin immunotoxins specific for the T-cell antigen receptor of a human leukemia T-cell line

Immunotoxins (ITs) were prepared by covalently coupling ricin to monoclonal antibodies (MAbs) directed against: (a) 2 different epitopes of the T-cell receptor (TcR) expressed by the Jurkat leukemia T-cell line (JTi2 and JTi4 MAb), (b) 2 epitopes of the CD3 complex (SpV-T3b and 11D8 MAb), (c) the CD2 and the CD8 cell-surface molecules. Conjugates were assayed for their cytotoxic activity by pre-incubating the Jurkat cell line with different concentrations (10-250 ng/ml) of each IT for 2 hr at 37 degrees C in the presence of 0.1 M lactose. After washing, cells were cultured for 24 hr and their protein synthesis and proliferative capacities were assessed. Dose-response experiments indicated that JTi2, JTi4 and anti-CD3 (11D8) ITs inhibited by greater than 90% the cell line proliferation at 50 ng/ml, a 5-fold lower concentration than that required to achieve a similar effect when anti-CD2 and anti-CD3 (SpVT3b) were used. After 4 hr of culture subsequent to treatment with JTi2 or JTi4 ITs (250 ng/ml), protein synthesis was inhibited (greater than 80%). By limiting dilution analysis (LDA) we estimated that the frequency of proliferating Jurkat cells (1/1.5) was reduced to 1/20, 1/460 and 1/300 after treatment with anti-CD3 (SpVT3b), JTi4 and JTi2 ITs, respectively. Phenotypic analysis of 13 clones derived from JTi2 IT-treated Jurkat cells showed that 50% were CD7+ CD3- JTi- variants. When bone-marrow mononuclear cells, previously mixed with low concentrations of Jurkat cells, were treated with anti-JTi ITs, the toxic efficiency estimated by LDA was maintained whereas the growth of CFU-GM remained unaltered.

Selective T cell subset depletion with anti-CD4 and anti-CD8 intact ricin immunotoxins

In the present study we have comparatively analysed the specific activity of a panel of immunotoxins (ITs) prepared by coupling Ricin to several monoclonal antibodies (MoAbs) directed against the CD3, CD4 and CD8 T cell membrane molecules. Peripheral blood and bone marrow mononuclear cells (PBMC and BMMC) were incubated with the different ITs for 2 h, in the presence of 0.1 M lactose, washed and subsequently stimulated with either phytohemagglutinin (PHA) or an anti-CD3 MoAb. Our results indicate that the proliferative response of PBMC to both stimuli was specifically inhibited (greater than 95%) by either anti-CD3 IT or a combination of anti-CD4 and CD8 ITs, at concentrations comparable to those previously used for ex vivo T cell depletion (300 ng/ml). When used individually at the same dose, anti-CD8 and anti-CD4 ITs inhibited the PHA-induced PBMC proliferative response 40 and 70% respectively. When either anti-CD4 or anti-CD8 IT-treated cells were activated with PHA and cultured for 14 days in the presence of IL-2, less than 2% of the blasts expressed the corresponding antigens as assessed by flow cytometry analysis. Similar results were observed when BMMC were treated with the different ITs. In contrast, the growth of CFU-GM was minimally affected (0-25% inhibition). Our data indicate that ITs directed against T cell subsets are highly active and specific reagents that may be potentially useful for pre-transplant bone marrow purging.

Defective interleukin 2 receptor expression is associated with the T cell disfunction subsequent to bone marrow transplantation

In the present work we have used monoclonal antibodies (mAb) as probes to attempt a dissection of the mechanisms underlying the immunodeficiency subsequent to bone marrow transplantation (BMT). To this end we have studied 19 allogeneic BMT recipients, analyzing the proliferative response of peripheral blood mononuclear cells (PBMC) after activation with either phytohemagglutinin (PHA), anti-CD3 or anti-CD2 mAb. All patients presented normal proportions of CD2+ and CD3+ lymphocytes, as assessed by flow cytometry. Our results indicated that in most cases both CD2 and CD3-mediated activation pathways were inefficient to trigger normal T cell proliferation. The addition of exogenous interleukin 2 (IL2) did not restore in most cases the proliferative response, pointing out that additional defects contribute to the hyporesponsiveness. This was more evident in the group of patients studied during the first 6 months. To further dissect the T cell defect we analyzed the effect of a phorbol ester (phorbol myristate acetate, PMA), which activates protein kinase C, on the anti-CD3-induced response. Our data showed that PMA synergized with anti-CD3 similarly to exogenous IL2, and restored the proliferative response only in certain cases. The expression of IL2 receptors (CD25) as assessed by cytofluorimetry, after either PHA or anti-CD3 and PMA stimulation, was shown to be depressed, and the addition of IL2 did not restore it. Finally, we observed that the early increase of intracytoplasmic Ca2+ after anti-CD3 stimulation was comparable to that detected in normal PBMC. Altogether these results indicate that a diminished CD25 expression is associated with the T cell defect, and cannot apparently be attributed to an inability of the CD3 molecule to transduce early activation signals thus suggesting that either protein kinase C itself or an as yet undefined metabolic step preceding IL2 receptor expression is abnormal in variable proportions of T cells after BMT, and constitutes another manifestation of this complex immunodeficiency.

Chronic juvenile toxic epidemic syndrome

The clinical manifestations in 21 children with chronic toxic epidemic syndrome (TES) and musculoskeletal manifestations were analysed and compared with those of the adult population. The sex ratio (2.5:1, F/M) was different from the one found in adults (6:1, F/M). The neuromuscular syndrome, the scleroderma-like picture, the pulmonary hypertension, and the Raynaud's phenomenon characteristic of TES were similar to those in adults but milder in children. The less severe vascular endothelial lesions found on microscopic examination might explain the better prognosis in this age group.

Toxic epidemic syndrome: musculoskeletal manifestations

The musculoskeletal manifestations of a new systemic disease that developed after toxic oil consumption are described. Clinically, it was characterized by the presence of arthralgias, sometimes arthritis, extensive muscle atrophy, severe neuropathy and a scleroderma-like skin involvement. Radiologically, different types of osteopenia could be seen in the absence of joint space narrowing or erosions. Neither hypertrophy, nor hyperplasia of synoviocytes were seen on microscopic examination. A non-necrotizing vasculitis and increase in fibrous tissue were observed at different levels.

Sequences isolated from a Drosophila early-ecdysone puff are expressed in rat liver

We have studied the presence of a cloned fragment of DNA from Drosophila melanogaster in other organisms by means of nucleic acid hybridization analysis. The isolated region is localized in polytene chromosomes at the 63F subdivision. This region includes a puff that responds within minutes to ecdysone stimulation. We have found that 63F DNA from D. melanogaster hybridizes 'in situ' to both DNA and RNA from D. simulans, D. teissieri, and D. hydei. In all these species the isolated DNA remains associated with one early-ecdysone stimulated puff. The isolated Drosophila recombinant DNA is also complementary to polyadenylated RNA from foetal and adult rat liver but fails to hybridize to the nonpolyadenylated RNA classes from both sources and to polyadenylated RNA from rat mammary glands.

In situ immunofluorescent visualization of chromosomal transcripts in polytene chromosomes

The induction and distribution of chromosomal transcripts in the polytene chromosomes of D. melanogaster and D. hydei has been investigated by indirect immunofluorescence using an antiserum directed against DNA/RNA hybrids. The fluorescence was intense and occurred in most of the chromosomal subdivisions when the chromosomes were exposed to denaturing conditions and then allowed to reanneal. The extent of hybrid formation depended both on the extent of DNA denaturation and on the maintenance of RNA integrity. Fluorescence was absent from chromosomes treated with pancreatic RNase before denaturation. The velocity of the chromosomal DNA/RNA hybridization reaction and the effects of the initiation inhibitor of RNA synthesis, DRB, suggest that in order to hybridize the RNA has to be located in its transcriptional compartment. Even though overall patterns of fluorescence seem to be similar during a developmental stage, variations were observed, particularly some correlated with puff induction after ecdysone stimulation.

Isolation of a structural gene mapping to subregions 63F of Drosophila melanogaster and 90B of D. hydei polytene chromosomes

We have isolated by molecular cloning techniques a structural gene that maps to subregion 63F of Drosophila melanogaster chromosome 3L. This locus being one of the early chromosomal targets for ecdysone stimulation, may be induced to puff by the hormone. The gene is on a plasmid vector and it has been designated as pDm 63F. This recombinant molecule also maps to the early ecdysone inducible subregion 90B of Drosophila hydei chromosome 4. The cytological inspection of large number of chromosomal sets after in situ hybridization of the cloned DNA, locates the cloned sequence between bands 63F 2-4 according to Bridges map. Similarly, in Drosophila hydei the cloned DNA maps between subdivisions 90B 2-4 according to Berendes' map. In situ hybridization of the pDm 63F cloned DNA, directed to the nascent RNA rather than to the DNA, shows two to three times more silver grains over the corresponding regions when puffed than in the resting stage. There are however quantitative differences attending to the transcriptional activity of homologous loci in both species. By RNA excess hybridization we have found that the cellular concentration of the 63F cloned mRNA is bout 2 times higher in hormone stimulated total larval tissues than in non-stimulated ones.

[9p trisomy syndrome. Two new cases (author's transl)]

Two cases of trisomy 9p, are reported affecting different break points involving chromosome 9; one of them showed skeletal abnormalities of importance. An analysis of the two cases reported is done and some of the last hypothesis in order to determine genetical and clinical correlations of the syndrome are considered.

Isolation and mapping of a cloned ribosomal protein gene of Drosophila melanogaster

Molecular cloning techniques are particularly well suited to the study of gene organization in Drasophila melanogaster because recombinant DNA can easily be localized in the genome by in situ hybridization to salivary gland polytene chromosomes. We report here the isolation and preliminary characterization of a recombinant phage, designated C25, containing a bona fide D. melanogaster ribosomal protein gene. In situ hybridization demonstrates that this sequence maps to region 99D on chromosome 3.