Enhanced secretory ability for the human factor VIII light chain produced in baculovirus-infected insect cells

The light and truncated heavy chains of human factor VIII, expressed separately in baculovirus-infected insect cells, exhibited different secretory behaviour when compared with each other and with a biologically active fusion molecule of the truncated heavy and light chains. The light chain was very efficiently secreted into culture medium, as judged by high extracellular protein levels and the absence of evidence for light chain retention within cells. Alternatively, proteins containing the heavy chain sequence were poorly secreted and appeared to be sequestered within cells, suggesting that regions within the heavy chain are responsible for the low levels of secreted protein which have generally been observed for recombinant factor VIII.

Thiamine pyrophosphate (TPP) negatively regulates transcription of some thi genes of Salmonella typhimurium

In Salmonella typhimurium, thiamine is a required nutrient that is synthesized de novo. Labeling studies have demonstrated probable precursors for both the 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate moiety and the 4-methyl-5-(beta-hydroxyethyl) thiazole monophosphate moiety. The isolation of thiamine auxotrophs with mutations in at least five different genetic loci is reported. The majority (22 of 25) of the mutants required only the thiazole moiety of thiamine to satisfy their growth requirement. Most (14 of 25) of the mutants were affected in the thi cluster at min 90 on the S. typhimurium genetic map. Data provided herein indicate that this cluster encodes an operon whose transcription is regulated by thiamine and suggest that thiamine pyrophosphate, or a molecule derived form it, is the effector molecule. Mutants with altered regulation of this operon were isolated, and we propose that they are defective in thiamine phosphate kinase, the product of the thiL gene.

Meeting the needs of minority ethnic communities

Concentrating on exotica and cultural differences merely allows commissioners and providers to ignore general health needs and blame the communities themselves when they receive poor quality services. We now have to move forward if we are to achieve an improvement in their health care. We are not talking of an insignificant minority, but nearly one in 10 of all children. Clearly real differences in health needs do exist, for example haemoglobinopathy associated illness; these need to be addressed and adequate provision made. It is in meeting the general needs of minority ethnic children that we face the greatest challenge. These are no different to those of the white ethnic majority. However, meeting them may require different--sometimes radically different--response strategies on behalf of both purchasers and providers of health care to children, supported by appropriate training, audit, and research.

Serotonergic and noradrenergic dysregulation in alcoholism: m-chlorophenylpiperazine and yohimbine effects in recently detoxified alcoholics and healthy comparison subjects

OBJECTIVE

This study compared serotonergic (5-HT) and noradrenergic reactivity in recently detoxified alcoholic patients and healthy comparison subjects.

METHOD

Participants were 22 male inpatients who met DSM-III-R criteria for alcohol dependence and who were abstinent for 12-26 days and 13 male healthy comparison subjects. Subjects completed 3 days of testing over 2 weeks under double-blind conditions that involved the intravenous infusions of m-chlorophenylpiperazine (mCPP), yohimbine, or a saline placebo. Drug effects on mood, physiologic responses, and plasma levels of cortisol, prolactin, and 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured.

RESULTS

Both mCPP and yohimbine infusion increased nervousness, vital signs, and plasma cortisol, prolactin, and MHPG levels relative to placebo Cortisol responses to mCPP were blunted in the alcoholic patients relative to the comparison subjects. Cortisol and prolactin responses to yohimbine were greater in the alcoholic patients, whereas their pulse increases after yohimbine infusion were blunted. No group differences emerged in MHPG, nervousness, or blood pressure responses to either drug.

CONCLUSIONS

This study documents persistent alterations in neuroendocrine responsivity of both 5-HT and noradrenergic systems in alcoholic patients after detoxification. Blunted cortisol responses to mCPP in these recently detoxified patients may reflect reductions in 5-HT2 receptor function. The absence of altered MHPG responses to yohimbine in the alcoholic patients suggests that presynaptic noradrenergic responsivity is not persistently altered in these patients. In contrast, the enhanced cortisol responses and reduced pulse responses to yohimbine in alcoholic patients may reflect down-regulation of postsynaptic noradrenergic receptors.

Specificity of ethanollike effects elicited by serotonergic and noradrenergic mechanisms

BACKGROUND

This study evaluated the specificity of the ethanollike effects of the serotonergic receptor partial agonist m-chlorophenylpiperazine hydrochloride (MCPP) relative to the alpha 2-adrenergic receptor antagonist yohimbine hydrochloride and the placebo in recently detoxified alcoholics. It also examined the relationship between ethanollike discriminative properties and the induction of craving in these patients. Both MCPP and yohimbine are anxiogenic in humans; thus, this study evaluated the role of anxiogenic and ethanollike effects in the elicitation of craving.

METHODS

Twenty-two male inpatients who met DSM-III-R criteria for alcohol dependence and who had not consumed alcohol for 12 to 26 days prior to the study completed 3 days of testing that involved the intravenous infusion of MCPP (0.1 mg/kg), (0.1 mg/kg), yohimbine hydrochloride (0.4 mg/kg), or a saline solution over 2 weeks under double-blind conditions. Ethanollike subjective effects were assessed using the Sensation Scale and visual analog scales to measure the degree of similarity to the effects of ethanol, cocaine, and marijuana. Five components of craving for alcohol were assessed using visual analog scales. The effects of the drugs on mood were assessed using visual analog scales. Plasma levels of cortisol, prolactin, and 3-methoxy-4-hydroxyphenylethyleneglycol were also measured during the test days.

RESULTS

m-Chlorophenylpiperazine and yohimbine produced significant increases compared with placebo in Sensation Scale scores and the visual analog scale score for nervousness. However, the effects of MCPP were rated as more similar to those of ethanol, cocaine, and marijuana than were those of either yohimbine or placebo. Also, MCPP but not yohimbine or placebo significantly increased craving for alcohol. Yohimbine and MCPP increased plasma prolactin and cortisol levels relative to placebo, whereas only yohimbine increased plasma 3-methoxy-4-hydroxyphenylethleneglycol levels.

CONCLUSIONS

m-Chlorophenylpiperazine produced ethanollike effects and alcohol craving in recently detoxified alcoholics. Yohimbine increased Sensation Scale scores but was not recognized as ethanollike by patients. Although both drugs produced comparable levels of nervousness, yohimbine did not increase craving for alcohol. These data further implicate serotonergic systems in the discriminative properties of ethanol and may indicate a serotonergic contribution to craving. Noradrenergic systems contributed to the discriminative properties of ethanol but not to those features of ethanol response that were salient to craving in this population.

Expression of biologically active human factor VIII using a baculovirus vector

Factor VIII is a complex, plasma glycoprotein involved in the process of blood coagulation. Production of the recombinant molecule has largely been confined to mammalian cell systems which have, in general, proven to be inefficient producers of factor VIII. The use of a baculovirus expression system may provide increased levels of this glycoprotein, although it is not certain that insect cell-derived factor VIII will be biologically active. The N-linked glycosylation patterns in insect cells, until recently thought to be less complex than in mammalian cells, may influence activity and/or secretory ability. To this end we engineered a B domain-deleted factor VIII cDNA sequence for expression in Spodoptera frugiperda cells. The construct retained the native signal sequence to allow secretion of recombinant protein into the culture medium. Initial studies revealed the production of secreted factor VIII, and this protein was shown to possess coagulation activity. The presence of N-linked oligosaccharide residues was demonstrated, the glycosylated molecule being of a similar size to that expressed in mammalian cells.

An E mu-v-abl transgene elicits plasmacytomas in concert with an activated myc gene

To clarify how the v-abl oncogene of Abelson murine leukemia virus contributes to lymphoid tumorigenesis, we introduced the gene linked to an immunoglobulin heavy chain enhancer (E mu) into the mouse germline. Although lymphoid development was not detectably affected in young E mu-v-abl mice, three transgenic lines shared a high predisposition to develop clonal plasmacytomas that secreted IgA or IgG. The unexpected absence of pre-B lymphomas suggests that Abelson virus generates such tumors by infecting an early lymphoid progenitor cell that has not yet activated the heavy chain enhancer. Most plasmacytomas bore a rearranged c-myc gene, apparently as a result of spontaneous translocation to the Igh locus. Moreover, progeny of a cross with analogous E mu-myc mice rapidly developed oligoclonal plasmacytomas. Thus, the collusion of v-abl with c-myc is stage specific, efficiently transforming plasma cells but not pre-B cells or B cells.

Effect of mitochondrial inhibitors on adenosinetriphosphate levels in Plasmodium falciparum

1. The effects of mitochondrial inhibitors on the ATP levels of intraerythrocytic Plasmodium falciparum have been studied. 2. Changes in parasite ATP or ADP levels with time in response to various mitochondrial inhibitors appear quite complex; ATP levels may be initially depressed and then elevated above normal, but the nature of the response depends upon the stage in the intraerythrocytic cycle and in some cases upon the concentration of the inhibitor used. 3. After ca 2 hr incubation of cultures with inhibitors ATP levels appear to be stabilized and are similar to those of untreated parasites. However, ADP levels of trophozoites show significant increases after a 2 hr incubation with inhibitors, particularly with oligomycin and to a lesser extent with antimycin A; increases in ADP levels however were not observed in ring-stages of the parasite. 4. Inhibition of red cell and parasite glycolysis leads to rapid decreases in parasite ATP levels which are not significantly affected by oligomycin. Incubation of in vitro cultures with oligomycin can result in a decreased, rather than increased rate of lactate production with a concomitant appearance of pyruvate in the growth medium. 5. This investigation would indicate that if there is a mitochondrial contribution to the parasite ATP pool it is relatively small, and that a short-fall in this contribution is quickly compensated for by ATP from other source(s), although this is not necessarily met by increased glycolysis.

Lymphomagenesis in Emu-myc transgenic mice does not require transgene rearrangement or mutation of myc exon 1

In most human Burkitt's lymphomas, translocation of the myc oncogene to an immunoglobulin locus is associated with loss of myc exon 1 or with mutations near its 3' border, a region where myc transcription is attenuated and translation of a larger myc polypeptide initiates. Emu-myc transgenic mice, which bear the three myc exons coupled to an immunoglobulin enhancer, provide a model for the development of such lymphomas, because their lymphomagenesis appears to require events other than expression of the transgene. To determine whether myc rearrangement or exon 1 mutation is a necessary tumorigenic event, we examined the transgene structure and myc exon 1 sequences in Emu-myc B lymphoid tumours. Southern blots revealed no transgene rearrangements in 20 of the lymphomas, and only two tumours showed amplification (2 to 5-fold). To search for exon 1 alterations, the exon 1 mRNA region was amplified from five tumours by polymerase chain reaction and sequenced, but no mutations were found. Hence, neither excision nor mutation of exon 1 is necessary to render myc tumorigenic. The sequence analysis across the exon 1-exon 2 boundary unexpectedly revealed an ambiguity in myc splicing that predicts a variant form of the larger myc polypeptide lacking a single amino acid residue.

A bcr-v-abl oncogene induces lymphomas in transgenic mice

In chronic myeloid leukemia and some cases of acute lymphoblastic leukemia, a 9;22 chromosome translocation has fused most of the c-abl oncogene to a gene designated bcr. To explore in vivo the biological effects of the chimeric gene, we introduced a facsimile of the translocation product, a bcr-v-abl gene, into the mouse germ line under the control of the immunoglobulin heavy-chain enhancer or a retroviral long terminal repeat. Some transgenic mice bearing either construct developed clonal lymphoid tumors. T lymphomas predominated, but some pre-B lymphomas developed. The transgenes were expressed in the tumors but not detectably in the lymphoid tissues of nontumorous transgenic animals, implying that transcription is activated by a low-frequency somatic event. These results demonstrate that bcr-v-abl is tumorigenic in vivo and provide a new animal model for lymphomagenesis.

N-myc transgene promotes B lymphoid proliferation, elicits lymphomas and reveals cross-regulation with c-myc

To assess the impact of constitutive N-myc expression on lymphocytes, we generated lines of transgenic mice bearing the murine N-myc oncogene coupled to the immunoglobulin heavy chain enhancer (E mu). As in mice carrying an analogous c-myc construct, E mu-N-myc mice exhibit a limited overgrowth of cycling pre-B cells and eventually succumb to clonal B lymphoid tumours. The endogenous N-myc and c-myc alleles are silent in both E mu-N-myc and E mu-myc lymphomas, suggesting that these genes are subject to auto- and cross-regulation. The regulatory interaction and the similar biological effects of N-myc and c-myc imply that the two genes perform interchangeable functions in the promotion of cell proliferation.

Expression of multiple homeobox genes within diverse mammalian haemopoietic lineages

Several mouse and human genes encoding the DNA-binding homeobox domain are implicated here in haematopoiesis, a differentiation process maintained throughout life. Four homeobox cDNA clones were isolated from bone marrow and spleen of adult mice and two from the human leukaemia cell line K562. They derive from the Hox 1.1, Hox 2.3, Hox 6.1 genes and two previously undescribed genes, one of a type (paired) not found before in vertebrates. A survey of 36 cell lines of the lymphoid, myeloid and erythroid lineages revealed that certain homeobox transcripts were almost ubiquitous, while others were restricted to certain lineages or even particular cell lines. The expression pattern altered in a myeloid and an erythroid line induced to terminal differentiation, and in novel lines that had switched from a lymphoid to a myeloid phenotype. Altogether, the haemopoietic compartment may contain up to 20 homeobox transcripts. In one myeloid leukaemia, DNA rearrangement has perturbed expression. These findings suggest that homeobox genes may influence developmental decisions within the haemopoietic system.

Arachidonic acid-induced inflammation: inhibition by dual inhibitor of arachidonic acid metabolism, SK&F 86002

The antiinflammatory activity of the structurally novel dual inhibitor of arachidonic acid metabolism, SK&F 86002 was evaluated using arachidonic acid-induced edema and inflammatory cell infiltration. Histological examination demonstrated extensive subcutaneous edema and neutrophil (PMN) accumulation in perivascular and interstitial locations one hour after application of arachidonic acid to the ear. SK&F 86002 and, to a lesser extent, phenidone demonstrated potent inhibition of this inflammatory response following oral and topical administration. Nordihydroguaiaretic acid (NDGA) displayed only topical activity. The selective cyclooxygenase inhibitors ibuprofen and naproxen were either inactive or stimulated ear swelling. Histological evaluation of the lesion in drug-treated animals revealed that SK&F 86002 impaired edema formation and caused a significant reduction in numbers of infiltrating neutrophils. Using arachidonic acid-induced peritoneal exudation, a reduction in the cellular infiltrate was observed after oral treatment with SK&F 86002 or phenidone, but not with naproxen. Taken together, these data illustrate the potent antiinflammatory effects of SK&F 86002 and support the suggestion that 5-lipoxygenase products play a significant role in both the edematous and cellular phases of arachidonic acid-induced inflammation.

Effect of supplementary vitamins and iron on malaria indices in rural Gambian children

The effect of a combined supplement of iron, thiamine, riboflavin and vitamin C on malarial incidence in 5 to 14-year-old children was tested in a malnourished rural community in a region of The Gambia noted for high prevalence of malaria during the rainy season. 190 children, divided into 2 matched groups, received either the supplement or a matching placebo for 3 months. No significant difference in malarial incidence was observed between the 2 groups, despite a major improvement in biochemical indices of nutrient status in the supplemented group, especially for riboflavin and vitamin C. Severity of episodes was also similar between groups, but in subjects who developed parasitaemias there was a trend towards higher parasite counts in those receiving the active supplement. Nutritional interventions in malarious areas may have adverse effects on malaria, and the increase in parasitaemia was compatible with the hypothesis that a small but significant reduction in defences had occurred. However, the absence of increases in the incidence of proven malaria cases and their severity must also be taken into account, in order to make a balanced assessment of the possible increase in risk. Further investigations are needed to measure the risk in benefit rates, and to consider the effects of individual nutrients in isolation.

Effects of a multivitamin and iron supplement on running performance in Gambian children

Forty boys and girls between 11 and 14.5 years with evidence of subclinical vitamin deficiencies were allocated to two groups to receive, twice weekly, either a placebo or a multivitamin and iron supplement. Prior to supplementation and on two subsequent occasions about 5 weeks apart, the children performed an exercise regimen on a treadmill during which expired air was collected and heart rate monitored. The supplement resulted in marked improvements in riboflavin and vitamin C status and checked the decline in iron stores seen in the unsupplemented children. During the study the running performance of unsupplemented children deteriorated, and markedly so in a subgroup with initially poor nutrient status. The vitamin and iron supplement prevented this deterioration so as to produce a significant reduction in the energy cost of treadmill running in the more malnourished subgroup, relative to the changes seen in children receiving no supplement.

Variant (6;15) translocations in murine plasmacytomas involve a chromosome 15 locus at least 72 kb from the c-myc oncogene

The variant (6;15) translocations in murine plasmacytomas join the myc oncogene-bearing band of chromosome 15 and the immunoglobulin kappa band of chromosome 6. We recently cloned a region from chromosome 15 linked to C kappa and have now used probes from that region to define the major locus of plasmacytoma variant translocations, which we denote pvt-1. In five of nine plasmacytomas we analysed, the 6;15 translocation resulted from reciprocal recombination between the C kappa locus and a 4.5-kb region of pvt-1. Moreover, nearby we located the region shown by others to have undergone a complex (15;12;6) translocation in plasmacytoma PC7183. All the chromosome 6 breakpoints fell between 1 and 3 kb 5' to C kappa but only two were near J kappa genes. Thus the J kappa -C kappa region appears to be a recombination 'hot spot' in lymphocytes, but the breaks are unlikely to be mediated via V/J recombination enzymes. Comparison of a cloned 108-kb region across pvt-1 and another of 52 kb across c-myc established that the pvt-1 breakpoints lie at least 72 kb from the c-myc promoters. Since c-myc is expressed at a substantial level, the 6;15 translocation apparently activates c-myc. Activation may occur directly, at a remarkable distance along the chromosome, or indirectly, via a putative pvt-1 gene product.

Variant (6 ; 15) translocation in a murine plasmacytoma occurs near an immunoglobulin kappa gene but far from the myc oncogene

Chromosome translocations in B-lymphoid tumours are providing intriguing insights and puzzles regarding the role of immunoglobulin genes in the activation of the myc oncogene (reviewed in refs 1, 2). The 15 ; 12 translocations found in most murine plasmacytomas and the analogous 8 ; 14 translocation in human Burkitt's lymphomas involve scissions of murine chromosome 15 (human chromosome 8) near the 5' end of the c-myc gene and subsequent fusion near an immunoglobulin heavy-chain gene. The less well characterized 'variant' translocations found in about 15% of such tumours also involve the myc-bearing chromosome band, but exchange occurs with a chromosome bearing an immunoglobulin light-chain locus--in mice, the kappa-chain locus bearing chromosome 6 (refs 3-5) and, in man, chromosome 2 (or 22), at the same band at which the kappa (or lambda) locus lies (reviewed in ref. 1). The Burkitt variant translocations involve scissions 3' of c-myc; one 8 ; 22 translocation placed the C lambda locus just 3' of c-myc, but usually the chromosome 8 breakpoint is a greater, but unknown, distance away from c-myc, more than 20 kilobases (kb) in one 8 ; 2 translocation involving the C kappa gene. Little is known about the murine 6 ; 15 translocations, although a C kappa gene cloned from one plasmacytoma (PC7183) is linked, via chromosome 12 sequences, to an unidentified region of chromosome 15 (ref. 11). We describe here the chromosome fusion region from plasmacytoma ABPC4, which displays the typical reciprocal 6;15 translocations. We find that the chromosome 6 breakpoint is near C kappa but, unlike those in the heavy-chain locus, not at a position where immunoglobulin genes normally recombine. Moreover, the chromosome 15 sequences involved in the ABPC4 translocation are not derived from the vicinity of c-myc.