Hematopoietic cell transplantation in older patients with hematologic malignancies: replacing high-dose cytotoxic therapy with graft-versus-tumor effects

Toxicities have limited the use of allogeneic hematopoietic cell transplantation (HCT) to younger, medically fit patients. In a canine HCT model, a combination of postgrafting mycophenolate mofetil (MMF) and cyclosporine (CSP) allowed stable allogeneic engraftment after minimally toxic conditioning with low-dose (200 cGy) total-body irradiation (TBI). These findings, together with the known antitumor effects of donor leukocyte infusions (DLIs), led to the design of this trial. Forty-five patients (median age 56 years) with hematologic malignancies, HLA-identical sibling donors, and relative contraindications to conventional HCT were treated. Immunosuppression involved TBI of 200 cGy before and CSP/MMF after HCT. DLIs were given after HCT for persistent malignancy, mixed chimerism, or both. Regimen toxicities and myelosuppression were mild, allowing 53% of eligible patients to have entirely outpatient transplantations. Nonfatal graft rejection occurred in 20% of patients. Grades II to III acute graft-versus-host disease (GVHD) occurred in 47% of patients with sustained engraftment. With median follow-up of 417 days, survival was 66.7%, nonrelapse mortality 6.7%, and relapse mortality 26.7%. Fifty-three percent of patients with sustained engraftment were in complete remission, including 8 with molecular remissions. This novel allografting approach, based on the use of postgrafting immunosuppression to control graft rejection and GVHD, has dramatically reduced the acute toxicities of allografting. HCT with the induction of potent graft-versus-tumor effects can be performed in previously ineligible patients, largely in an outpatient setting. Future protocol modifications should reduce rejection and GVHD, thereby facilitating studies of allogeneic immunotherapy for a variety of malignancies. (Blood. 2001;97:3390-3400)

Crystal structure of the cytochrome bc1 complex from bovine heart mitochondria

On the basis of x-ray diffraction data to a resolution of 2.9 angstroms, atomic models of most protein components of the bovine cytochrome bc1 complex were built, including core 1, core 2, cytochrome b, subunit 6, subunit 7, a carboxyl-terminal fragment of cytochrome c1, and an amino-terminal fragment of the iron-sulfur protein. The positions of the four iron centers within the bc1 complex and the binding sites of the two specific respiratory inhibitors antimycin A and myxothiazol were identified. The membrane-spanning region of each bc1 complex monomer consists of 13 transmembrane helices, eight of which belong to cytochrome b. Closely interacting monomers are arranged as symmetric dimers and form cavities through which the inhibitor binding pockets can be accessed. The proteins core 1 and core 2 are structurally similar to each other and consist of two domains of roughly equal size and identical folding topology.

FOG, a multitype zinc finger protein, acts as a cofactor for transcription factor GATA-1 in erythroid and megakaryocytic differentiation

The hematopoietic transcription factor GATA-1 is essential for development of the erythroid and megakaryocytic lineages. Using the conserved zinc finger DNA-binding domain of GATA-1 in the yeast two-hybrid system, we have identified a novel, multitype zinc finger protein, Friend of GATA-1 (FOG), which binds GATA-1 but not a functionally inactive mutant lacking the amino (N) finger. FOG is coexpressed with GATA-1 during embryonic development and in erythroid and megakaryocytic cells. Furthermore, FOG and GATA-1 synergistically activate transcription from a hematopoietic-specific regulatory region and cooperate during both erythroid and megakaryocytic cell differentiation. These findings indicate that FOG acts as a cofactor for GATA-1 and provide a paradigm for the regulation of cell type-specific gene expression by GATA transcription factors.

Tissue-specific overexpression of lipoprotein lipase causes tissue-specific insulin resistance

Insulin resistance in skeletal muscle and liver may play a primary role in the development of type 2 diabetes mellitus, and the mechanism by which insulin resistance occurs may be related to alterations in fat metabolism. Transgenic mice with muscle- and liver-specific overexpression of lipoprotein lipase were studied during a 2-h hyperinsulinemic-euglycemic clamp to determine the effect of tissue-specific increase in fat on insulin action and signaling. Muscle-lipoprotein lipase mice had a 3-fold increase in muscle triglyceride content and were insulin resistant because of decreases in insulin-stimulated glucose uptake in skeletal muscle and insulin activation of insulin receptor substrate-1-associated phosphatidylinositol 3-kinase activity. In contrast, liver-lipoprotein lipase mice had a 2-fold increase in liver triglyceride content and were insulin resistant because of impaired ability of insulin to suppress endogenous glucose production associated with defects in insulin activation of insulin receptor substrate-2-associated phosphatidylinositol 3-kinase activity. These defects in insulin action and signaling were associated with increases in intracellular fatty acid-derived metabolites (i.e., diacylglycerol, fatty acyl CoA, ceramides). Our findings suggest a direct and causative relationship between the accumulation of intracellular fatty acid-derived metabolites and insulin resistance mediated via alterations in the insulin signaling pathway, independent of circulating adipocyte-derived hormones.

A protein complex network of Drosophila melanogaster

Determining the composition of protein complexes is an essential step toward understanding the cell as an integrated system. Using coaffinity purification coupled to mass spectrometry analysis, we examined protein associations involving nearly 5,000 individual, FLAG-HA epitope-tagged Drosophila proteins. Stringent analysis of these data, based on a statistical framework designed to define individual protein-protein interactions, led to the generation of a Drosophila protein interaction map (DPiM) encompassing 556 protein complexes. The high quality of the DPiM and its usefulness as a paradigm for metazoan proteomes are apparent from the recovery of many known complexes, significant enrichment for shared functional attributes, and validation in human cells. The DPiM defines potential novel members for several important protein complexes and assigns functional links to 586 protein-coding genes lacking previous experimental annotation. The DPiM represents, to our knowledge, the largest metazoan protein complex map and provides a valuable resource for analysis of protein complex evolution.

Transport and pharmacological properties of nine different human Na, K-ATPase isozymes

Na,K-ATPase plays a crucial role in cellular ion homeostasis and is the pharmacological receptor for digitalis in man. Nine different human Na,K-ATPase isozymes, composed of 3 alpha and beta isoforms, were expressed in Xenopus oocytes and were analyzed for their transport and pharmacological properties. According to ouabain binding and K(+)-activated pump current measurements, all human isozymes are functional but differ in their turnover rates depending on the alpha isoform. On the other hand, variations in external K(+) activation are determined by a cooperative interaction mechanism between alpha and beta isoforms with alpha2-beta2 complexes having the lowest apparent K(+) affinity. alpha Isoforms influence the apparent internal Na(+) affinity in the order alpha1 > alpha2 > alpha3 and the voltage dependence in the order alpha2 > alpha1 > alpha3. All human Na,K-ATPase isozymes have a similar, high affinity for ouabain. However, alpha2-beta isozymes exhibit more rapid ouabain association as well as dissociation rate constants than alpha1-beta and alpha3-beta isozymes. Finally, isoform-specific differences exist in the K(+)/ouabain antagonism which may protect alpha1 but not alpha2 or alpha3 from digitalis inhibition at physiological K(+) levels. In conclusion, our study reveals several new functional characteristics of human Na,K-ATPase isozymes which help to better understand their role in ion homeostasis in different tissues and in digitalis action and toxicity.

Monolithic porous polymer for on-chip solid-phase extraction and preconcentration prepared by photoinitiated in situ polymerization within a microfluidic device

Monolithic porous polymers have been prepared by photoinitiated polymerization within the channels of a microfluidic device and used for on-chip solid-phase extraction and preconcentration. The preparation of the monolithic material with hydrophobic and ionizable surface chemistries is easily achieved by copolymerization of butyl methacrylate with ethylene dimethacrylate, or 2-hydroxyethyl methacrylate and [2-(methacryloyloxy)ethyl]trimethylammonium chloride with ethylene dimethacrylate, respectively. The porous properties, and consequently the flow resistance, of the monolithic device are controlled by the use of a mixture of hexane and methanol as a porogenic mixture. This mixture was designed to meet the specific requirements for pore formation within macroporous monoliths useful in the microfluidic formats. The low flow resistance enables high flow rates of up to 10 microL/min, which corresponds to a linear flow velocity of 50 mm/s and far exceeds the flow velocities typical of the common analytical microchips. The function of the monolithic concentration device was first demonstrated using very dilute solutions of Coumarin 519. The performance in a more realistic application was then demonstrated with the enrichment of a hydrophobic tetrapeptide and also of green fluorescent protein for which an increase in concentration by a factor as high as 10(3) was achieved.

Erythroid-cell-specific properties of transcription factor GATA-1 revealed by phenotypic rescue of a gene-targeted cell line

The zinc finger transcription factor GATA-1 is essential for erythropoiesis. In its absence, committed erythroid precursors arrest at the proerythroblast stage of development and undergo apoptosis. To study the function of GATA-1 in an erythroid cell environment, we generated an erythroid cell line from in vitro-differentiated GATA-1- murine embryonic stem (ES) cells. These cells, termed G1E for GATA-1- erythroid, proliferate as immature erythroblasts yet complete differentiation upon restoration of GATA-1 function. We used rescue of terminal erythroid maturation in G1E cells as a stringent cellular assay system in which to evaluate the functional relevance of domains of GATA-1 previously characterized in nonhematopoietic cells. At least two major differences were established between domains required in G1E cells and those required in nonhematopoietic cells. First, an obligatory transactivation domain defined in conventional nonhematopoietic cell transfection assays is dispensable for terminal erythroid maturation. Second, the amino (N) zinc finger, which is nonessential for binding to the vast majority of GATA DNA motifs, is strictly required for GATA-1-mediated erythroid differentiation. Our data lead us to propose a model in which a nuclear cofactor(s) interacting with the N-finger facilitates transcriptional action by GATA-1 in erythroid cells. More generally, our experimental approach highlights critical differences in the action of cell-specific transcription proteins in different cellular environments and the power of cell lines derived from genetically modified ES cells to elucidate gene function.

Elevated cholesterol metabolism and bile acid synthesis in mice lacking membrane tyrosine kinase receptor FGFR4

Heparan sulfate-regulated transmembrane tyrosine kinase receptor FGFR4 is the major FGFR isotype in mature hepatocytes. Fibroblast growth factor has been implicated in the definition of liver from foregut endoderm where FGFR4 is expressed and stimulation of hepatocyte DNA synthesis in vitro. Here we show that livers of mice lacking FGFR4 exhibited normal morphology and regenerated normally in response to partial hepatectomy. However, the FGFR4 (-/-) mice exhibited depleted gallbladders, an elevated bile acid pool and elevated excretion of bile acids. Cholesterol- and bile acid-controlled liver cholesterol 7alpha-hydroxylase, the limiting enzyme for bile acid synthesis, was elevated, unresponsive to dietary cholesterol, but repressed normally by dietary cholate. Expression pattern and cholate-dependent, cholesterol-induced hepatomegaly in the FGFR4 (-/-) mice suggested that activation of receptor interacting protein 140, a co-repressor of feed-forward activator liver X receptor alpha, may mediate the negative regulation of cholesterol- and bile acid-controlled liver cholesterol 7alpha-hydroxylase transcription by FGFR4 and cholate. The results demonstrate that transmembrane sensors interface with metabolite-controlled transcription networks and suggest that pericellular matrix-controlled liver FGFR4 in particular may ensure adequate cholesterol for cell structures and signal transduction.

Activation of NF-kappa B is required for hypertrophic growth of primary rat neonatal ventricular cardiomyocytes

The transcription factor NF-kappaB regulates expression of genes that are involved in inflammation, immune response, viral infection, cell survival, and division. However, the role of NF-kappaB in hypertrophic growth of terminally differentiated cardiomyocytes is unknown. Here we report that NF-kappaB activation is required for hypertrophic growth of cardiomyocytes. In cultured rat primary neonatal ventricular cardiomyocytes, the nuclear translocation of NF-kappaB and its transcriptional activity were stimulated by several hypertrophic agonists, including phenylephrine, endothelin-1, and angiotensin II. The activation of NF-kappaB was inhibited by expression of a "supersuppressor" IkappaBalpha mutant that is resistant to stimulation-induced degradation and a dominant negative IkappaB kinase (IKKbeta) mutant that can no longer be activated by phosphorylation. Furthermore, treatment with phenylephrine induced IkappaBalpha degradation in an IKK-dependent manner, suggesting that NF-kappaB is a downstream target of the hypertrophic agonists. Importantly, expression of the supersuppressor IkappaBalpha mutant or the dominant negative IKKbeta mutant blocked the hypertrophic agonist-induced expression of the embryonic gene atrial natriuretic factor and enlargement of cardiomyocytes. Conversely, overexpression of NF-kappaB itself induced atrial natriuretic factor expression and cardiomyocyte enlargement. These findings suggest that NF-kappaB plays a critical role in the hypertrophic growth of cardiomyocytes and may serve as a potential target for the intervention of heart disease.

Interactions of apolipoprotein E genotype, total cholesterol level, age, and sex in prediction of Alzheimer's disease: a case-control study

OBJECTIVE

The joint effects of total cholesterol (TC) levels and the APOE genotype in Alzheimer's disease (AD) were evaluated because of previous reports that the APOE locus epsilon 4 allele was associated with both late-onset AD and elevated TC.

DESIGN

Logistic regression was used to determine the effects of the APOE genotype, TC, age, and sex on prediction of AD in a community-based study of 206 cases and 276 controls.

RESULTS

The relationship of the APOE genotype and AD was dependent on TC, age, and sex. However, current TC level does not fully explain the epsilon 4-Alzheimer's disease association. Affected men with higher TC and age under 80 years had the highest epsilon 4 allele frequencies. The epsilon 4 frequency declined significantly with age.

SIGNIFICANCE

A pathologic role of higher TC or cholesterol-based differential survival of epsilon 4-carrying individuals may be involved in the relationship of the epsilon 4 allele with AD. The observed association of the APOE genotype and AD is expected to depend on the age, sex, and TC distributions of a given sample.

Dentinogenesis imperfecta 1 with or without progressive hearing loss is associated with distinct mutations in DSPP

Dentinogenesis imperfecta 1 (DGI1, MIM 125490) is an autosomal dominant dental disease characterized by abnormal dentin production and mineralization. The DGI1 locus was recently refined to a 2-Mb interval on 4q21 (ref. 1). Here we study three Chinese families carrying DGI1. We find that the affected individuals of two families also presented with progressive sensorineural high-frequency hearing loss (gene DFNA39). We identified three disease-specific mutations within the dentin sialophosphoprotein gene (DSPP) in these three families. We detected a G-->A transition at the donor-splicing site of intron 3 in one family without DFNA39, a mutation predicted to result in the skipping of exon 3. In two other families affected with both DGI1 and DFNA39, however, we identified two independent nucleotide transversions in exons 2 and 3 of DSPP, respectively, that cause missense mutations of two adjacent amino-acid residues in the predicted transmembrane region of the protein. Moreover, transcripts of DSPP previously reported to be expressed specifically in teeth are also detected in the inner ear of mice. We have thus demonstrated for the first time that distinct mutations in DSPP are responsible for the clinical manifestations of DGI1 with or without DFNA39.

Direct aperture optimization: a turnkey solution for step-and-shoot IMRT

IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach "direct aperture optimization." This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT.

Spin-state changes in cytochrome P-450cam on binding of specific substrates

The electron paramagnetic resonance signals of the soluble P-450 cytochrome from Pseudomonas putida were observed at temperatures from 4.2 to 80 degrees K. As isolated, P-450 has a signal typical of a low spin ferric-heme compound with sulfur as one of the axial ligands (g = 2.45, 2.26, 1.91(5)). We also detected a minor signal typical of high spin ferric heme (g = 8, 4, 1.8) equivalent to less than 7% of the heme at temperatures below 20 degrees K. On titration with the substrate, (+)-camphor, the low spin signal decreased and the high spin signal increased, maximally representing about 60% of the heme. For reasons not thus far understood, 40% of the heme is not converted to high spin by either (+) or (-)-camphor. The high spin signal has a rhombic character which is stronger than any previously observed with a heme compound (E = 0.33 cm(-1); D = 3.8 cm(-1); E/D = 0.087). We conclude that P-450(cam) as isolated is equal to or more than 95% in a low spin form probably having sulfur as one of the axial ligands. The binding of substrate displaces this ligand sufficiently to allow for conversion from a low to a high spin form.

DNA minor groove-binding ligands: a different class of mammalian DNA topoisomerase I inhibitors

A number of DNA minor groove-binding ligands (MGBLs) are known to exhibit antitumor and antimicrobial activities. We show that DNA topoisomerase (Topo) I may be a pharmacological target of MGBLs. In the presence of calf thymus Topo I, MGBLs induced limited but highly specific single-strand DNA breaks. The 3' ends of the broken DNA strands are covalently linked to Topo I polypeptides. Protein-linked DNA breaks are readily reversed by a brief heating to 65 degrees C or the addition of 0.5 M NaCl. These results suggest that MGBLs, like camptothecin, abort Topo I reactions by trapping reversible cleavable complexes. The sites of cleavage induced by MGBLs are distinctly different from those induced by camptothecin. Two of the major cleavage sites have been sequenced and shown to be highly A + T-rich, suggesting the possible involvement of a Topo I-drug-DNA ternary complex at the sites of cleavage. Different MGBLs also exhibit varying efficiency in inducing Topo I-cleavable complexes, and the order of efficiency is as follows: Hoechst 33342 and 33258 >> distamycin A > berenil > netropsin. The lack of correlation between DNA binding and cleavage efficiency suggest that, in addition to binding to the minor grooves of DNA, MGBLs must also interact with Topo I in trapping Topo I-cleavable complexes.

Generation of superoxide anion by succinate-cytochrome c reductase from bovine heart mitochondria

Production of superoxide anion (O-2), measured as the chemiluminescence of the 2-methyl-6-(p-methoxyphenyl)-3, 7-dihydroimidazo[1,2-a]pyrazin-3-one hydrochloride (MCLA)-O-2 adduct, was observed during electron transfer from succinate to cytochrome c by reconstituted succinate-cytochrome c reductase-phospholipid vesicles replenished with succinate dehydrogenase. Addition of carbonyl cyanide p-trifluoromethoxyphenylhydrazone or detergent to the reconstituted reductase-phospholipid vesicles abolished O-2 production, suggesting that O-2 generation is caused by the membrane potential generated during electron transfer through the cytochrome bc1 complex. Production of O-2 was also observed during electron transfer from succinate to cytochrome c by antimycin-treated reductase, in which approximately 99.7% of the reductase activity was inhibited. The rate of O-2 production was closely related to the rate of antimycin-insensitive cytochrome c reduction. Factors affecting antimycin-insensitive reduction of cytochrome c also affected O-2 production and vice versa. When the oxygen concentration in the system was decreased, the rate of O-2 production and cytochrome c reduction by antimycin-treated reductase decreased. When the concentrations of MCLA and cytochrome c were increased, the rate of O-2 production and cytochrome c reduction by antimycin-treated reductase increased. The rate of antimycin-insensitive cytochrome c reduction was sensitive to Qo site inhibitors such as 5-undecyl-6-hydroxy-4,7-dioxobenzothiazole. These results indicate that generation of O-2 during the oxidation of ubiquinol by the cytochrome bc1 complex results from a leakage of the second electron of ubiquinol from its Q cycle electron transfer pathway to interact with oxygen. The electron-leaking site is located at the reduced cytochrome b566 or ubisemiquinone of the Qo site because addition of MCLA to antimycin-treated cytochrome bc1 complex, in the presence of catalytic amounts of succinate-cytochrome c reductase, delayed cytochrome b reduction by succinate. In the presence of oxidized cytochrome c, purified succinate dehydrogenase also catalyzed oxidation of succinate to generate O-2. When succinate dehydrogenase was reconstituted with the bc1 particles to form succinate-cytochrome c reductase, the production of O-2 diminished. These results suggest that reduced FAD of succinate dehydrogenase is the electron donor for oxygen to produce O-2 in the absence of their immediate electron acceptor and in the presence of cytochrome c.

Proline inhibits aggregation during protein refolding

The in vitro refolding of hen egg-white lysozyme is studied in the presence of various osmolytes. Proline is found to prevent aggregation during protein refolding. However, other osmolytes used in this study fail to exhibit a similar property. Experimental evidence suggests that proline inhibits protein aggregation by binding to folding intermediate(s) and trapping the folding intermediate(s) into enzymatically inactive, "aggregation-insensitive" state(s). However, elimination of proline from the refolded protein mixture results in significant recovery of the bacteriolytic activity. At higher concentrations (>1.5 M), proline is shown to form loose, higher-order molecular aggregate(s). The supramolecular assembly of proline is found to possess an amphipathic character. Formation of higher-order aggregates is believed to be crucial for proline to function as a protein folding aid. In addition to its role in osmoregulation under water stress conditions, the results of this study hint at the possibility of proline behaving as a protein folding chaperone.

Efficient Baylis--Hillman reaction using stoichiometric base catalyst and an aqueous medium

A practical and efficient set of conditions were developed using stoichiometric base catalyst, 1,4-diazabicyclo[2,2,2]octane (DABCO), and an aqueous medium to overcome problems commonly associated with the Baylis--Hillman reaction, such as low reaction yields and long reaction time. These simple modifications to the classical conditions, using more base catalyst and an aqueous medium, proved to be successful in converting a variety of aliphatic and aromatic aldehydes to their corresponding Baylis--Hillman products. The inclusion of environmentally friendly water in the reaction solvent was critical for achieving the high yield of Baylis--Hillman adducts. Our deuterium-exchange experiments suggest that the Michael addition adduct formed between DABCO and methyl acrylate is the active intermediate for the Baylis--Hillman reaction in aqueous conditions, and its hydrolysis, a nonproductive side reaction facilitated by the quaternary ammonium ion, leading to the formation of a stable betaine product, consumes both the catalyst and methyl acrylate, making it necessary to add more base catalyst and methyl acrylate.

Inhibitor binding changes domain mobility in the iron-sulfur protein of the mitochondrial bc1 complex from bovine heart

We have analyzed crystal structures of cytochrome bc1 complexes with electron transfer inhibitors bound to the ubiquinone binding pockets Qi and/or Qo in the cytochrome b subunit. The presence or absence of the Qi inhibitor antimycin A did not affect the binding of the Qo inhibitors. Different subtypes of Qo inhibitors had dramatically different effects on the mobility of the extramembrane domain of the iron-sulfur protein (ISP): Binding of 5-undecyl-6-hydroxy-4, 7-dioxobenzothiazol and stigmatellin (subtype Qo-II and Qo-III, respectively) led to a fixation of the ISP domain on the surface of cytochrome b, whereas binding of myxothiazol and methoxyacrylate-stilbene (subtype Qo-I) favored release of this domain. The native structure has an empty Qo pocket and is intermediate between these extremes. On the basis of these observations we propose a model of quinone oxidation in the bc1 complex, which incorporates fixed and loose states of the ISP as features important for electron transfer and, possibly, also proton transport.

Substituted 2,5'-Bi-1H-benzimidazoles: topoisomerase I inhibition and cytotoxicity

Several 2'-aryl-5-substituted-2,5'bi-1H-benzimidazole derivatives were synthesized and evaluated as topoisomerase I poisons and for their cytotoxicity toward the human lymphoblast cell line RPMI 8402. This study focused on 18 2,5'-bi-1H-benzimidazole derivatives which contained either a 5-cyano, a 5-(aminocarbonyl), or a 5-(4-methylpiperazinyl) group. Among these bibenzimidazoles, the pharmacological activity of 2'-phenyl derivatives and the influence of the different positional isomers of either a 2'-tolyl group or a 2'-naphthyl moiety on cytotoxicity and topoisomerase I inhibitory activity were determined.

Roles of acyl-coenzyme A:cholesterol acyltransferase-1 and -2

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme that produces cholesteryl esters in various tissues. In mammals, two ACAT genes (ACAT1 and ACAT2) have been identified. Together, these two enzymes are involved in storing cholesteryl esters as lipid droplets, in macrophage foam-cell formation, in absorbing dietary cholesterol, and in supplying cholesteryl esters as part of the core lipid for lipoprotein synthesis and assembly. The key difference in tissue distribution of ACAT1 and ACAT2 between humans, mice and monkeys is that, in adult human liver (including hepatocytes and bile duct cells), the major enzyme is ACAT1, rather than ACAT2. There is compelling evidence implicating a role for ACAT1 in macrophage foam-cell formation, and for ACAT2 in intestinal cholesterol absorption. However, further studies at the biochemical and cell biological levels are needed in order to clarify the functional roles of ACAT1 and ACAT2 in the VLDL or chylomicron synthesis/assembly process.

Personal and family factors associated with quality of life in adolescents with diabetes

OBJECTIVE

Quality of life is an important criterion for assessing outcomes of treatment in chronic illness related to psychosocial well-being. The purpose of this study was to evaluate the factors that influence quality of life in adolescents with IDDM.

RESEARCH DESIGN AND METHODS

Self-reports were obtained from 52 adolescents (age 13-20 years, mean 16.1 +/- 1.9 [mean +/- SD], diabetes duration 8.2 +/- 3.4 years, 49% female) using the following scales: Diabetes Quality of Life for Youths, Children's Depression Inventory, Issues in Coping with Diabetes, Diabetes Family Behavior Scale, Family Adaptability and Cohesion, Self-Efficacy for Diabetes, and the Adolescent Coping Orientation. Metabolic control was measured by HbA1c.

RESULTS

Teenagers whose diabetes had the greater impact (R2 = 0.48) and were less satisfied (R2 = 0.45) felt that management was more difficult (r = 0.56) and that diabetes was more upsetting (r = 0.63). They also used fewer rebellion strategies for coping (r = -0.44), had lower diabetes self-efficacy (r = -0.36), and had more depressive symptoms (r = 0.61). Higher impact was also associated with higher family warmth and caring (r = -0.54) and lower family adaptability (r = -0.42). Teenagers who were more worried (R2 = 0.37) about their diabetes felt that management was more difficult (r = 0.40) and that diabetes was more upsetting (r = 0.58), and they used less rebellion (r = -0.49) and more ventilation (r = 0.42) to cope, had lower diabetes (r = -0.40) and medical (r = -0.30) self-efficacy, were more depressed (r = 0.55), and their families were less warm and caring (r = -0.33). HbA1c levels were not associated with quality of life or any other psychosocial factors except in teenagers who perceived their families as providing more guidance and control. These teenagers had lower HbA1c values than those whose families were less involved.

CONCLUSIONS

Even teenagers who are successfully achieving HbA1c goals of therapy may perceive diabetes as having a negative impact on their lives, be depressed, and find diabetes difficult to manage. Diabetes treatment teams need to pay equal attention to the psychosocial needs to the quiet, nonrebellious teen with well-controlled diabetes from a supportive family as they do to the rebellious adolescent with poorly controlled diabetes.

Microvessel count and cerebrospinal fluid basic fibroblast growth factor in children with brain tumours

Tumour growth is angiogenesis-dependent; brain tumours have more intense neovascularisation than other tumours and produce basic fibroblast growth factor, a potent angiogenic mediator. Because little is known about the release of basic fibroblast growth factor from brain tumours into extracellular fluids, we tested cerebrospinal fluid (CSF) from 26 children and young adults with brain tumours and 18 controls for basic fibroblast growth factor and for proliferative activity on cultured capillary endothelial cells. We also measured the density of microvessels in tumours by immunohistochemical staining. Basic fibroblast growth factor was detected in the CSF of 62% (16 of 26) patients with brain tumours but in none of the controls. Specimens with basic fibroblast growth factor stimulated DNA synthesis of capillary endothelial cells in vitro. Endothelial proliferative activity was blocked by neutralising antibodies to basic fibroblast growth factor. Basic fibroblast growth factor correlated with mitogenic activity in CSF in vitro (p < or = 0.0001), and with density of microvessels in histological sections (p < or = 0.005). A microvessel count of > or = 68 per 200 x field was associated with tumour recurrence (p = 0.005) and with mortality (p = 0.02). Basic fibroblast growth factor in brain tumours may mediate angiogenesis as measured by microvessel density in histological sections, so has potential as both a marker for neoplasia and a target for tumour treatments. Furthermore, evaluation of cerebrospinal fluid basic fibroblast growth factor, along with microvessel quantitation in biopsied tumours, may provide improved prognostic information for the management of patients with brain tumours.