Non-infusional 5-fluorouracil, doxorubicin and cisplatin in the treatment of locally advanced or metastatic gastro-oesophageal adenocarcinoma

To reduce the Hickman line-associated morbidity of continuous infusion 5-fluorouracil combined with epirubicin and cisplatin (ECF) and to investigate the need for infusional regimens, we conducted a retrospective study in patients with advanced gastro-oesophageal adenocarcinoma. Thirty-six patients, with histologically proven irresectable gastro-oesophageal adenocarcinoma were given: 60 mg/m2 cisplatin on day 1, 35 mg/m2 doxorubicin on day 1 and 500 mg/m2 5-fluorouracil on days 1 and 8 (NIACF) every 3-weeks. A median of 3 cycles was administered. The principal toxicity was myelosuppression with grade III/IV neutropenia in 47% of cycles. Neutropenic fever occurred in 5% of the cycles: non-haematological toxicity was mild and there were no treatment-related deaths. Administered dose intensity was 96.1% for doxorubicin, 93.6% for cisplatin and 90.5% for 5-fluorouracil. There were 16 partial responses and 1 complete response (overall response rate 47%, 95% confidence interval CI 31-63%); 8 patients had stable disease. Median progression-free and overall survival rates were 5 months (95% CI 4-6) and 8 months (95% CI 6-10), respectively. NIACF is a well-tolerated regimen in advanced gastro-oesophageal adenocarcinoma that precludes the need for central venous access, with activity similar to that observed with ECF.

Modulation of blood fluke development in the liver by hepatic CD4+ lymphocytes

We have identified an alternate developmental pathway in the life cycle of the trematode pathogen Schistosoma mansoni. This pathway is used in immunodeficient hosts in which the parasite fails to receive appropriate signals from the host immune system. Helminth development is altered at an early stage during infection, resulting in the appearance of attenuated forms that prolong survival of host and parasite. Hepatic CD4+ T lymphocyte populations are an integral component of the immune signal recognized by the parasite.

Simple syntheses, structural diversity, and Tishchenko reaction catalysis of neutral homoleptic rare earth(II or III) 3,5-di-tert-butylpyrazolates--the structures of

The homoleptic rare-earth pyrazolate complexes [Sc(tBu2pz)3], [Ln2(tBu2pz)6] (Ln = La, Nd, Sm, Lu), [Eu4(tBu2pz)8] and the mixed oxidation state species [Yb2(tBu2pz)5] (tBu2pz = 3,5-di-tert-butylpyrazolate) have been prepared by a simple reaction between the corresponding rare-earth metal and 3,5-di-tert-butylpyrazole, in the presence of mercury, at elevated temperatures. In addition, [Yb2(tBu2pz)6] was prepared by redox transmetallation/ligand exchange between ytterbium, diphenylmercury(II) and tBu2pzH in toluene, whilst the same reactants in toluene under different conditions or in diethyl ether gave [Yb2(tBu2pz)5]. The complexes of the trivalent lanthanoids display dimeric structures [Ln2(tBu2pz)6] (Ln = La, Nd, Yb, Lu) with chelating eta2-terminal and eta2:eta2-bridging pyrazolate coordination. The considerably smaller Sc3+ ion forms monomeric [Sc(tBu2pz)3] of putative D3h molecular symmetry, with pyrazolate ligands solely eta2-bonded. [Eu4(tBu2pz)8] is a structurally remarkable tetranuclear EuII complex with two types of europium centres in a linear array. The outer two are bonded to one terminal and two bridging pyrazolates, and the inner two are coordinated by four bridging ligands. Unprecedented mu-eta5:eta2 pyrazolate ligation is observed, with each outer Eu2+ sandwiched between two eta5-bonded pyrazolate groups, which are also eta2-linked to an inner Eu2+. The two inner Eu2+ ions are linked together by two equally occupied components of each of two symmetry related, disordered pyrazolate groups with one component eta4:eta2 bridging and one eta3:eta2 bridging. [La2(tBu2pz)6] has also been shown to be a Tishchenko reaction catalyst with several organic substrates.

Schistosome invasion of human skin and degradation of dermal elastin are mediated by a single serine protease

Aquatic larvae (cercariae) of the trematode parasite Schistosoma mansoni rapidly penetrate human skin by degrading host proteins including elastin. Two serine proteases, one chymotrypsin-like and the second trypsin-like, have been proposed to be involved. To evaluate the relative roles of these two proteases in larval invasion, both were purified, identified by sequence, and then biochemically characterized. The trypsin-like activity was resolved into two distinct serine proteases 76% similar in predicted amino acid sequence. Southern blot analysis, genomic polymerase chain reaction, and immunolocalization demonstrated that the trypsin-like proteases are in fact not from the schistosome, but are released with larvae from the snail host Biomphalaria glabrata. Invasion inhibition assays using selective inhibitors confirmed that the chymotrypsin-like protease is the enzyme involved in skin penetration. Its ability to degrade skin elastin was confirmed, and the three sites of cleavage within elastin help define a new family of elastases.

GATA factor transgenes under GATA-1 locus control rescue germline GATA-1 mutant deficiencies

GATA-1 germline mutation in mice results in embryonic lethality due to defective erythroid cell maturation, and thus other hematopoietic GATA factors do not compensate for the loss of GATA-1. To determine whether the obligate presence of GATA-1 in erythroid cells is due to its distinct biochemical properties or spatiotemporal patterning, we attempted to rescue GATA-1 mutant mice with hematopoietic GATA factor complementary DNAs (cDNAs) placed under the transcriptional control of the GATA-1 gene. We found that transgenic expression of a GATA-1 cDNA fully abrogated the GATA-1-deficient phenotype. Surprisingly, GATA-2 and GATA-3 factors expressed from the same regulatory cassette also rescued the embryonic lethal phenotype of the GATA-1 mutation. However, adult mice rescued with the latter transgenes developed anemia, while GATA-1 transgenic mice did not. These results demonstrate that the transcriptional control dictating proper GATA-1 accumulation is the most critical determinant of GATA-1 activity during erythropoiesis. The results also show that there are biochemical distinctions among the hematopoietic GATA proteins and that during adult hematopoiesis the hematopoietic GATA factors are not functionally equivalent.

Gata3 loss leads to embryonic lethality due to noradrenaline deficiency of the sympathetic nervous system

Mouse embryos deficient in Gata3 die by 11 days post coitum (d.p.c.) from pathology of undetermined origin. We recently showed that Gata3-directed lacZ expression of a 625-kb Gata3 YAC transgene in mice mimics endogenous Gata3 expression, except in thymus and the sympathoadrenal system. As this transgene failed to overcome embryonic lethality (unpublished data and ref. 3) in Gata3-/- mice, we hypothesized that a neuroendocrine deficiency in the sympathetic nervous system (SNS) might cause embryonic lethality in these mutants. We find here that null mutation of Gata3 leads to reduced accumulation of Th (encoding tyrosine hydroxylase, Th) and Dbh (dopamine beta-hydroxylase, Dbh) mRNA, whereas several other SNS genes are unaffected. We show that Th and Dbh deficiencies lead to reduced noradrenaline in the SNS, and that noradrenaline deficiency is a proximal cause of death in mutants by feeding catechol intermediates to pregnant dams, thereby partially averting Gata3 mutation-induced lethality. These older, pharmacologically rescued mutants revealed abnormalities that previously could not be detected in untreated mutants. These late embryonic defects include renal hypoplasia and developmental defects in structures derived from cephalic neural crest cells. Thus we have shown that Gata3 has a role in the differentiation of multiple cell lineages during embryogenesis.

Blockage of skin invasion by schistosome cercariae by serine protease inhibitors

Invasion of skin by schistosome cercariae is facilitated by a serine protease secreted from the acetabular cells of cercariae in response to skin lipid. Specific inhibitors of the protease, when applied to human skin in formulations designed to retain the inhibitor on and in the upper stratum corneum layers, block cercarial invasion of human skin. Both peptide-based, irreversible inhibitors and non-peptide, reversible inhibitors block cercarial invasion when applied in a propylene glycol:isopropyl alcohol (3:1) formulation in vitro. Arrest of cercarial invasion could be achieved even after immersion of treated skin in water for 2 hr. Peptide-based irreversible inhibitors in the presence of three different Topicare Delivery Compounds optimized arrest of cercarial invasion. The three Topicare Delivery Compounds applied alone prevented 80-100% of cercarial invasion. With inclusion of the inhibitor, there was 97-100% inhibition in vitro. The optimal formulation with inhibitor was then applied to the tails of BALB/c mice, and the mice were exposed to 120 cercariae by tail immersion. With the carrier lotion alone, there was a 50% reduction in worm burden and a 70% reduction in egg burden. When inhibitor was included, an 80% reduction in worm burden and a 92% reduction in egg burden was observed.

Localization of distant urogenital system-, central nervous system-, and endocardium-specific transcriptional regulatory elements in the GATA-3 locus

We found previously that neither a 6-kbp promoter fragment nor even a 120-kbp yeast artificial chromosome (YAC) containing the whole GATA-3 gene was sufficient to recapitulate its full transcription pattern during embryonic development in transgenic mice. In an attempt to further identify tissue-specific regulatory elements modulating the dynamic embryonic pattern of the GATA-3 gene, we have examined the expression of two much larger (540- and 625-kbp) GATA-3 YACs in transgenic animals. A lacZ reporter gene was first inserted into both large GATA-3 YACs. The transgenic YAC patterns were then compared to those of embryos bearing the identical lacZ insertion in the chromosomal GATA-3 locus (creating GATA-3/lacZ "knock-ins"). We found that most of the YAC expression sites and tissues are directly reflective of the endogenous pattern, and detailed examination of the integrated YAC transgenes allowed the general localization of a number of very distant transcriptional regulatory elements (putative central nervous system-, endocardium-, and urogenital system-specific enhancers). Remarkably, even the 625-kbp GATA-3 YAC, containing approximately 450 kbp and 150 kbp of 5' and 3' flanking sequences, respectively, does not contain the full transcriptional regulatory potential of the endogenous locus and is clearly missing regulatory elements that confer tissue-specific expression to GATA-3 in a subset of neural crest-derived cell lineages.

Bacteroides fragilis enterotoxin cleaves the zonula adherens protein, E-cadherin

Strains of Bacteroides fragilis associated with diarrheal disease (enterotoxigenic B. fragilis) produce a 20-kDa zinc-dependent metalloprotease toxin (B. fragilis enterotoxin; BFT) that reversibly stimulates chloride secretion and alters tight junctional function in polarized intestinal epithelial cells. BFT alters cellular morphology and physiology most potently and rapidly when placed on the basolateral membrane of epithelial cells, suggesting that the cellular substrate for BFT may be present on this membrane. Herein, we demonstrate that BFT specifically cleaves within 1 min the extracellular domain of the zonula adherens protein, E-cadherin. Cleavage of E-cadherin by BFT is ATP-independent and essential to the morphologic and physiologic activity of BFT. However, the morphologic changes occurring in response to BFT are dependent on target-cell ATP. E-cadherin is shown here to be a cellular substrate for a bacterial toxin and represents the identification of a mechanism of action, cell-surface proteolytic activity, for a bacterial toxin.

Rescue of the embryonic lethal hematopoietic defect reveals a critical role for GATA-2 in urogenital development

Mutations resulting in embryonic or early postnatal lethality could mask the activities of any gene in unrelated and temporally distinct developmental pathways. Targeted inactivation of the transcription factor GATA-2 gene leads to mid-gestational death as a consequence of hematopoietic failure. We show here that a 250 kbp GATA-2 yeast artificial chromosome (YAC) is expressed strongly in both the primitive and definitive hematopoietic compartments, while two smaller YACs are not. This largest YAC also rescues hematopoiesis in vitro and in vivo, thereby localizing the hematopoietic regulatory cis element(s) to between 100 and 150 kbp 5' to the GATA-2 structural gene. Introducing the YAC transgene into the GATA-2(-/-) genetic background allows the embryos to complete gestation; however, newborn rescued pups quickly succumb to lethal hydroureternephrosis, and display a complex array of genitourinary abnormalities. These findings reveal that GATA-2 plays equally vital roles in urogenital and hematopoietic development.

Individual LCR hypersensitive sites cooperate to generate an open chromatin domain spanning the human beta-globin locus

BACKGROUND

The human beta-globin locus control region (LCR) is composed of five DNase I hypersensitive (HS) sites located 5' to the multiple genes it regulates. The LCR has been shown to comprise, among other essential properties, an activity that is required for generating a chromatin structure which renders the entire beta-globin gene locus accessible to exogenous nucleases. This nuclease-sensitive state is generally believed to be reflective of the chromatin environment that is permissive for transcriptional activation of the globin genes.

RESULTS

Here we show, in mice bearing intact YAC transgenes that encompass the whole human beta-globin locus, that the deletion of individual core LCR HS sites negatively affects the ability of the LCR to confer this open chromatin conformation throughout the locus, and when analysed in concert with the effect that these same mutations have on transcription, the data show that the chromatin opening activity is a necessary, but not sufficient, prerequisite for globin gene expression. The results also show that after deletion of individual hypersensitive sites, the mutated LCR is no longer able to provide an accessible chromatin environment that is independent from the site of YAC transgene integration.

CONCLUSIONS

These experiments provide further evidence for the hypothesis that the HS sites must act cooperatively to fulfil the multiple functions that are attributable to the LCR.

Mammalian granulocyte-macrophage colony-stimulating factor receptor expressed in primary avian hematopoietic progenitors: lineage-specific regulation of proliferation and differentiation

The cytokine Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) regulates proliferation, differentiation, and apoptosis during myelopoiesis and erythropoiesis. Structure-function relationships of GM-CSF interactions with its receptor (GM-R), the biochemistry of GM-R signal transduction, and GM-CSF action in vivo are relatively well understood. Much less is known, however, about GM-R function in primary hematopoietic cells. In this paper we show that expression of the human GM-R in a heterologous cell system (primary avian erythroid and myeloid cells) confirms respective results in murine or human cell lines, but also provides new insights how the GM-R regulates progenitor proliferation and differentiation. As expected, the hGM-CSF stimulated myeloid progenitor proliferation and differentiation and enhanced erythroid progenitor proliferation during terminal differentiation. In the latter cells, however, the hGM-R only partially substituted for the activities of the erythropoietin receptor (EpoR). It failed to replace the EpoR in its cooperation with c-Kit to induce long-term proliferation of erythroid progenitors. Furthermore, the hGM-R alpha chain specifically interfered with EpoR signaling, an activity neither seen for the betac subunit of the receptor complex alone, nor for the alpha chain of the closely related Interleukin-3 receptor. These results point to a novel role of the GM-R alpha chain in defining cell type-specific functions of the GM-R.

Regulation and function of transcription factor GATA-1 during red blood cell differentiation

The tissue-specific transcription factor GATA-1 is a key regulator of red blood cell differentiation. One seemingly contradictory aspect of GATA-1 function is that, while it is abundant in erythroid progenitor cells prior to the onset of overt differentiation, it does not significantly activate known GATA-1 target genes in those cells. To investigate the mechanisms underlying GATA-1 function during the transition from early to late erythropoiesis, we have examined its expression and activity in normal avian erythroid progenitor cells before and after induction of differentiation. In these primary progenitor cells, GATA-1 protein was predominantly located in the cytoplasm, while induction of differentiation caused its rapid relocalization to the nucleus, suggesting that nuclear translocation constitutes an important regulatory step in GATA-1 activation. As an alternative way of addressing the same question, we also ectopically expressed a GATA-1/estrogen receptor fusion protein (GATA-1/ER) in red blood cell progenitors, where nuclear translocation of, and transcriptional activation by, this hybrid factor are conditionally controlled by estrogen. We found that hormone-activated GATA-1/ER protein accelerated red blood cell differentiation, and concomitantly suppressed cell proliferation. These phenotypic effects were accompanied by a simultaneous suppression of c-myb and GATA-2 transcription, two genes thought to be involved in the proliferative capacity of hematopoietic progenitor cells. Thus, GATA-1 appears to promote differentiation in committed erythroid progenitor cells both by inducing differentiation-specific genes and by simultaneously suppressing genes involved in cell proliferation.

Cysteine protease inhibitors block schistosome hemoglobin degradation in vitro and decrease worm burden and egg production in vivo

Schistosome parasites utilize hemoglobin as a major protein source for their metabolism. Degradation of hemoglobin has been hypothesized to be mediated by both cysteine and aspartyl proteases secreted into the lumen of the parasite intestine. We now show that two distinct types of irreversible cysteine protease-specific inhibitors both arrest schistosome hemoglobin degradation in vitro. Arrest of hemoglobin degradation is followed by death of developing schistosomula 1 week later. Schistosome infected mice treated by a dose of 2 mg inhibitor per day for 1 week early in infection, and 2 weeks at the time of egg production, showed a significant reduction in worm burden, hepatomegaly, and the number of eggs produced per female worm. Histopathology showed a minimal immune response to those eggs which were produced, consistent with a delay in egg production relative to untreated infections. By tagging the inhibitor with biotin, specific cysteine protease targets were identified in extracts of schistosome worms.

Synergistic regulation of human beta-globin gene switching by locus control region elements HS3 and HS4

Proper tissue- and developmental stage-specific transcriptional control over the five genes of the human beta-globin locus is elicited in part by the locus control region (LCR), but the molecular mechanisms that dictate this determined pattern of gene expression during human development are still controversial. By use of homologous recombination in yeast to generate mutations in the LCR within a yeast artificial chromosome (YAC) bearing the entire human beta-globin gene locus, followed by injection of each of the mutated YACs into murine ova, we addressed the function of LCR hypersensitive site (HS) elements 3 and 4 in human beta-globin gene switching. The experiments revealed a number of unexpected properties that are directly attributable to LCR function. First, deletion of either HS3 or HS4 core elements from an otherwise intact YAC results in catastrophic disruption of globin gene expression at all erythroid developmental stages, despite the presence of all other HS elements in the YAC transgenes. If HS3 is used to replace HS4, gene expression is normal at all developmental stages. Conversely, insertion of the HS4 element in place of HS3 results in significant expression changes at every developmental stage, indicating that individual LCR HS elements play distinct roles in stage-specific beta-type globin gene activation. Although the HS4 duplication leads to alteration in the levels of epsilon- and gamma-globin mRNAs during embryonic erythropoiesis, total beta-type globin mRNA synthesis is balanced, thereby leading to the conclusion that all of the human beta-locus genes are competitively regulated. In summary, the human beta-globin HS elements appear to form a single, synergistic functional entity called the LCR, and HS3 and HS4 appear to be individually indispensable to the integrity of this macromolecular complex.

Structure and regulation of the chicken erythroid delta-aminolevulinate synthase gene

Erythroid cells regulate heme biosynthesis in a manner that is distinct from all other cell types. While heme negatively regulates the synthesis of the housekeeping delta-aminolevulinate synthase (ALAS-N) in all non-erythroid cells, the expression of an erythroid-specific isozyme (ALAS-E) is developmentally regulated in red blood cells. As a first step towards understanding the molecular basis for the transcriptional regulation of ALAS-E during erythropoiesis, we cloned and characterized the chicken ALAS-E locus. This gene spans 18 kbp and is composed of eleven exons. The intron/exon structure of erythroid ALAS was found to be conserved among several vertebrate species. Direct RNA sequencing identified a 5' untranslated region that is derived from two continuous exons and is predicted to form a very stable stem-loop structure that bears resemblance to the ferritin iron-responsive element. Tissue-specific expression of the ALAS-E gene was analyzed by transient transfection assays in hematopoietic cells of both erythroid and non-erythroid origins. These experiments identified distal (-784 to -505 bp) and proximal (-155 to +21 bp) promoter elements which are required for high level, erythroid-specific transcription.

Effect of loading and syringing on void formation in automixed addition silicone elastomers

The effect of loading and syringing on void formation in five automixed addition silicones was evaluated by determining the voids created in the first and second halves of material loaded and dispensed from a metal syringe. Impressions were made of a model with six stainless-steel cylinders. The voids were counted at a predetermined site on 3 separate days using a binocular microscope at x 7 magnification. Automixed addition silicones did not confirm the 'last out-fewer bubbles' phenomenon and specific loading and syringing technique did not appear to have a consistent effect on void formation in automixed elastomers.

Expression of the chicken GATA factor family during early erythroid development and differentiation

The DNA motif WGATAR has been identified within transcriptional regulatory domains of globin and other erythroid-specific genes and the activator proteins that bind to this regulatory element, the GATA factors, belong to a multi-gene family that is expressed in chicken erythroid cells. Here we show that, as in chickens, multiple members of the GATA factor family are expressed in human and murine erythroid cells. During the early stages of chicken embryogenesis (well before blood island formation), each of the GATA family members is transcribed with a unique temporal and spatial pattern. In the primitive erythroid lineage, transcription of the embryonic epsilon-globin gene parallels GATA-1 expression while the switch to beta-globin transcription in definitive erythroid cells is directly preceded by a pronounced increase in GATA-3 accumulation. The timing and pattern of expression of these different mRNAs during avian erythroid development and differentiation suggests that temporally regulated changes in GATA factor expression are required for vertebrate hematopoiesis.

Ectopic expression of a conditional GATA-2/estrogen receptor chimera arrests erythroid differentiation in a hormone-dependent manner

The GATA factors are a family of transcriptional regulatory proteins in eukaryotes that share extensive homology in their DNA-binding domains. One enigmatic aspect of GATA factor expression is that several GATA proteins, which ostensibly share the same DNA-binding site specificity, are coexpressed in erythroid cells. To elucidate the roles of individual GATA factors in erythropoiesis, conditional alleles of GATA-1, GATA-2, and GATA-3 were prepared by fusing each of the factors to the hormone-binding domain of the human estrogen receptor (ER). These GATA/ER chimeric factors were shown to be hormone-inducible trans-activating proteins in transient transfection assays. When stably introduced into primary erythroblasts or conditionally transformed erythroid progenitors cells, exogenous GATA-2/ER promoted proliferation and inhibited terminal differentiation in an estrogen-dependent manner. These phenotypic effects are specifically attributable to the action of ectopically expressed GATA-2/ER because erythroblasts expressing exogenous GATA-2 are constitutively arrested in differentiation and because erythroid progenitors expressing either Gal/ER or GATA-3/ER do not display a hormone-responsive block in differentiation. Thus, the GATA-2 transcription factor appears to play a role in regulating the self-renewal capacity of early erythroid progenitor cells.

Effect of operator variability on void formation in impressions made with an automixed addition silicone

This study examined voids produced in impressions of an automixed addition-reaction silicone. Two operators took the impressions using material dispensed from either intra-oral tips or an impression syringe. The material was also hand-mixed for comparison. There were no differences in the number of voids in the automixed material dispensed using the intra-oral tip or impression syringe. Automixing produced substantially fewer voids than hand-mixing. There was a significant difference in the number of voids in the impressions made by the two operators.

Effect of interchanging automatic mixing tips on void formation for an automixed addition silicone impression

This study examined the effect of interchanging mixing tips on void formation for impressions of an automixed addition silicone material. The impressions were made of a series of stainless-steel cylinders by two dentists. The voids were counted at a predetermined site with a binocular microscope. The results showed that there were no significant variations in the number of voids in impressions of the automixed addition silicone using the three different mixing tips. However, one dentist made impressions that had substantially less voids for all three mixing tips.

Porosities in five automixed addition silicone elastomers

Five automixed and one hand-mixed addition silicones were evaluated by counting the number of voids produced in impressions made. It was concluded that although automixing produced fewer voids than hand-mixing, certain automixed materials were better than others.

Microleakage of intermediate restorative materials

This study compares the microleakage of a glass ionomer cement, Ketac Fil, used without cavity conditioning, with the established intermediate restorative materials, Cavit-W, and a reinforced zinc oxide-eugenol cement, Kalzinol. Microleakage was assessed using an electrochemical technique. At the end of 30 days, the materials tested, listed in decreasing order of microleakage, were Cavit-W, Ketac Fil inserted without cavity conditioning, Kalzinol, and the control group of Ketac Fil inserted into conditioned cavities. There was no significant difference in the microleakage observed in Ketac Fil restorations inserted without cavity conditioning and Kalzinol (p = 0.450), while the differences between the other groups were highly significant (p less than 0.001).

MRI study of brain changes with short-term abstinence from alcohol

Magnetic resonance brain scans were obtained from 10 chronic alcoholics within 2 weeks of alcohol withdrawal, and 19 to 28 days later. Age-matched control subjects were scanned at comparable intervals. At the initial scan, the alcoholics had larger lateral ventricles than the controls; at the second scan, their ventricles were significantly smaller than at the first scan. Among the controls, there was no mean change in the size of the lateral ventricles between the first and second scan. This study demonstrates reversibility in ventricular enlargement with short-term abstinence from alcohol. The role of rehydration in this process and the possibility of further changes with continued abstinence remain to be tested.