A comparison of enoxaparin with placebo for the prevention of venous thromboembolism in acutely ill medical patients. Prophylaxis in Medical Patients with Enoxaparin Study Group

BACKGROUND

The efficacy and safety of thromboprophylaxis in patients with acute medical illnesses who may be at risk for venous thromboembolism have not been determined in adequately designed trials.

METHODS

In a double-blind study, we randomly assigned 1102 hospitalized patients older than 40 years to receive 40 mg of enoxaparin, 20 mg of enoxaparin, or placebo subcutaneously once daily for 6 to 14 days. Most patients were not in an intensive care unit. The primary outcome was venous thromboembolism between days 1 and 14, defined as deep-vein thrombosis detected by bilateral venography (or duplex ultrasonography) between days 6 and 14 (or earlier if clinically indicated) or documented pulmonary embolism. The duration of follow-up was three months.

RESULTS

The primary outcome could be assessed in 866 patients. The incidence of venous thromboembolism was significantly lower in the group that received 40 mg of enoxaparin (5.5 percent [16 of 291 patients]) than in the group that received placebo (14.9 percent [43 of 288 patients]) (relative risk, 0.37; 97.6 percent confidence interval, 0.22 to 0.63; P< 0.001). The benefit observed with 40 mg of enoxaparin was maintained at three months. There was no significant difference in the incidence of venous thromboembolism between the group that received 20 mg of enoxaparin (43 of 287 patients [15.0 percent]) and the placebo group. The incidence of adverse effects did not differ significantly between the placebo group and either enoxaparin group. By day 110, 50 patients had died in the placebo group (13.9 percent), 51 had died in the 20-mg group (14.7 percent), and 41 had died in the 40-mg group (11.4 percent); the differences were not significant.

CONCLUSIONS

Prophylactic treatment with 40 mg of enoxaparin subcutaneously per day safely and effectively reduces the risk of venous thromboembolism in patients with acute medical illnesses.

An STS-based map of the human genome

A physical map has been constructed of the human genome containing 15,086 sequence-tagged sites (STSs), with an average spacing of 199 kilobases. The project involved assembly of a radiation hybrid map of the human genome containing 6193 loci and incorporated a genetic linkage map of the human genome containing 5264 loci. This information was combined with the results of STS-content screening of 10,850 loci against a yeast artificial chromosome library to produce an integrated map, anchored by the radiation hybrid and genetic maps. The map provides radiation hybrid coverage of 99 percent and physical coverage of 94 percent of the human genome. The map also represents an early step in an international project to generate a transcript map of the human genome, with more than 3235 expressed sequences localized. The STSs in the map provide a scaffold for initiating large-scale sequencing of the human genome.

Robust deep learning-based protein sequence design using ProteinMPNN

Although deep learning has revolutionized protein structure prediction, almost all experimentally characterized de novo protein designs have been generated using physically based approaches such as Rosetta. Here, we describe a deep learning-based protein sequence design method, ProteinMPNN, that has outstanding performance in both in silico and experimental tests. On native protein backbones, ProteinMPNN has a sequence recovery of 52.4% compared with 32.9% for Rosetta. The amino acid sequence at different positions can be coupled between single or multiple chains, enabling application to a wide range of current protein design challenges. We demonstrate the broad utility and high accuracy of ProteinMPNN using x-ray crystallography, cryo-electron microscopy, and functional studies by rescuing previously failed designs, which were made using Rosetta or AlphaFold, of protein monomers, cyclic homo-oligomers, tetrahedral nanoparticles, and target-binding proteins.

Hormone-dependent coactivator binding to a hydrophobic cleft on nuclear receptors

The ligand-binding domain of nuclear receptors contains a transcriptional activation function (AF-2) that mediates hormone-dependent binding of coactivator proteins. Scanning surface mutagenesis on the human thyroid hormone receptor was performed to define the site that binds the coactivators, glucocorticoid receptor-interacting protein 1 (GRIP1) and steroid receptor coactivator 1 (SRC-1). The residues involved encircle a small surface that contains a hydrophobic cleft. Ligand activation of transcription involves formation of this surface by folding the carboxyl-terminal alpha helix against a scaffold of three other helices. These features may represent general ones for nuclear receptors.

The growing family of interferon regulatory factors

Interferons (IFN) exert their multiple biological effects through the induction of expression of over 30 genes encoding proteins with antiviral, antiproliferative and immunomodulatory functions. Among the many IFN-inducible proteins are the Interferon Regulatory Factors (IRFs), a family of transcription regulators, originally consisting of the well-characterized IRF-1 and IRF-2 proteins; the family has now expanded to over 10 members and is still growing. The present review provides a detailed description of recently characterized IRF family members. Studies analyzing IRF-expressing cell lines and IRF knockout mice reveal that each member of the IRF family exerts distinct roles in biological processes such as pathogen response, cytokine signalling, cell growth regulation and hematopoietic development. Understanding the molecular mechanisms by which the IRFs affect these important cellular events and IFN expression will contribute to a greater understanding of events leading to various viral, immune and malignant disease states and will suggest novel strategies for antiviral and immune modulatory therapy.

Functional human T-cell immunity and osteoprotegerin ligand control alveolar bone destruction in periodontal infection

Periodontitis, a prime cause of tooth loss in humans, is implicated in the increased risk of systemic diseases such as heart failure, stroke, and bacterial pneumonia. The mechanisms by which periodontitis and antibacterial immunity lead to alveolar bone and tooth loss are poorly understood. To study the human immune response to specific periodontal infections, we transplanted human peripheral blood lymphocytes (HuPBLs) from periodontitis patients into NOD/SCID mice. Oral challenge of HuPBL-NOD/SCID mice with Actinobacillus actinomycetemcomitans, a well-known Gram-negative anaerobic microorganism that causes human periodontitis, activates human CD4(+) T cells in the periodontium and triggers local alveolar bone destruction. Human CD4(+) T cells, but not CD8(+) T cells or B cells, are identified as essential mediators of alveolar bone destruction. Stimulation of CD4(+) T cells by A. actinomycetemcomitans induces production of osteoprotegerin ligand (OPG-L), a key modulator of osteoclastogenesis and osteoclast activation. In vivo inhibition of OPG-L function with the decoy receptor OPG diminishes alveolar bone destruction and reduces the number of periodontal osteoclasts after microbial challenge. These data imply that the molecular explanation for alveolar bone destruction observed in periodontal infections is mediated by microorganism-triggered induction of OPG-L expression on CD4(+) T cells and the consequent activation of osteoclasts. Inhibition of OPG-L may thus have therapeutic value to prevent alveolar bone and/or tooth loss in human periodontitis.

Montelukast for chronic asthma in 6- to 14-year-old children: a randomized, double-blind trial. Pediatric Montelukast Study Group

CONTEXT

Leukotrienes are important mediators of asthma by causing bronchoconstriction, mucous secretion, and increased vascular permeability. Studies using compounds that block leukotrienes have demonstrated improvement in asthma control in adults and adolescents, but children younger than 12 years, for whom asthma is the most common chronic disease, have not been studied.

OBJECTIVE

To determine the clinical effect of montelukast, a leukotriene receptor antagonist, in 6- to 14-year-old children with asthma.

DESIGN

Eight-week, multicenter, randomized, double-blind study.

SETTING

Forty-seven outpatient centers at private practices and academic medical centers in the United States and Canada.

PATIENTS

A total of 336 children with forced expiratory volume in 1 second (FEV1) between 50% to 85% of the predicted value, at least 15% reversibility after inhaled beta-agonist administration, a minimal predefined level of daytime asthma symptoms, and daily beta-agonist use. Concomitant inhaled corticosteroids at a constant daily dose were used by 39% of patients receiving montelukast and 33% receiving placebo.

INTERVENTION

After a 2-week placebo run-in period, patients received either montelukast (5-mg chewable tablet) or matching-image placebo once daily at bed-time for 8 weeks.

MAIN OUTCOME MEASURE

Morning FEV1 percent change from baseline.

RESULTS

Mean morning FEV1 increased from 1.85 L to 2.01 L in the montelukast group and from 1.85 L to 1.93 L in the placebo group. This represents an 8.23% (95% confidence interval [CI], 6.33% to 10.13%) increase from baseline in the montelukast group and a 3.58% (95% CI, 1.29% to 5.87%) increase from baseline in the placebo group (P<.001 for montelukast vs placebo).

CONCLUSION

Montelukast improves morning FEV1 in 6- to 14-year-old children with chronic asthma.

The folding mechanism of a beta-sheet: the WW domain

The folding thermodynamics and kinetics of the Pin WW domain, a three-stranded antiparallel beta-sheet, have been characterized extensively. Folding and activation free energies were determined as a function of temperature for 16 mutants, which sample all strands and turns of the molecule. The mutational phi value (Phi(m)) diagram is a smooth function of sequence, indicating a prevalence of local interactions in the transition state (TS). At 37 degrees C, the diagram has a single pronounced maximum at turn 1: the rate-limiting step during folding is the formation of loop 1. In contrast, key residues for thermodynamic stability are located in the strand hydrophobic clusters, indicating that factors contributing to protein stability and folding kinetics are not correlated. The location of the TS along the entropic reaction coordinate Phi(T), obtained by temperature-tuning the kinetics, reveals that sufficiently destabilizing mutants in loop 2 or in the Leu7-Trp11-Tyr24-Pro37 hydrophobic cluster can cause a switch to a late TS. Phi(m) analysis is usually applied "perturbatively" (methyl truncation), but with Phi(T) to quantitatively assess TS shifts along a reaction coordinate, more severe mutations can be used to probe regions of the free energy surface beyond the TS.

Transferrin and iron in normal, Alzheimer's disease, and Parkinson's disease brain regions

Oxidant-mediated damage is suspected to be involved in the pathogenesis of several neurodegenerative disorders. Iron promotes conversion of hydrogen peroxide to hydroxyl radical and, thus, may contribute to oxidant stress. We measured iron and its transport protein transferrin in caudate, putamen, globus pallidus, substantia nigra, and frontal cortex of subjects with Alzheimer's disease (n = 14) and Parkinson's disease (n = 14), and in younger adult (n = 8) and elderly (n = 8) normal controls. Although there were no differences between control groups with regard to concentrations of iron and transferrin, iron was significantly increased (p < 0.05) in Alzheimer's disease globus pallidus and frontal cortex and Parkinson's disease globus pallidus, and transferrin was significantly increased in Alzheimer's disease frontal cortex, compared with elderly controls. The transferrin/iron ratio, a measure of iron mobilization capacity, was decreased in globus pallidus and caudate in both disorders. Regional transferrin and iron concentrations were generally more highly correlated (Pearson's correlation coefficient) in elderly controls than in Alzheimer's and Parkinson's disease. The altered relationship between iron and transferrin provides further evidence that a disturbance in iron metabolism may be involved in both disorders.

Complex roles of Stat1 in regulating gene expression

Stat1 is a fascinating and complex protein with multiple, yet contrasting transcriptional functions. Upon activation, it drives the expression of many genes but also suppresses the transcription of others. These opposing characteristics also apply to its role in facilitating crosstalk between signal transduction pathways, as it participates in both synergistic activation and inhibition of gene expression. Stat1 is a functional transcription factor even in the absence of inducer-mediated activation, participating in the constitutive expression of some genes. This review summarizes the well studied involvement of Stat1 in IFN-dependent and growth factor-dependent signaling and then describes the roles of Stat1 in positive, negative and constitutive regulation of gene expression as well as its participation in crosstalk between signal transduction pathways. Oncogene (2000).

Regulation of c-myc expression by IFN-gamma through Stat1-dependent and -independent pathways

Interferons (IFNs) inhibit cell growth in a Stat1-dependent fashion that involves regulation of c-myc expression. IFN-gamma suppresses c-myc in wild-type mouse embryo fibroblasts, but not in Stat1-null cells, where IFNs induce c-myc mRNA rapidly and transiently, thus revealing a novel signaling pathway. Both tyrosine and serine phosphorylation of Stat1 are required for suppression. Induced expression of c-myc is likely to contribute to the proliferation of Stat1-null cells in response to IFNs. IFNs also suppress platelet-derived growth factor (PDGF)-induced c-myc expression in wild-type but not in Stat1-null cells. A gamma-activated sequence element in the promoter is necessary but not sufficient to suppress c-myc expression in wild-type cells. In PKR-null cells, the phosphorylation of Stat1 on Ser727 and transactivation are both defective, and c-myc mRNA is induced, not suppressed, in response to IFN-gamma. A role for Raf-1 in the Stat1-independent pathway is revealed by studies with geldanamycin, an HSP90-specific inhibitor, and by expression of a mutant of p50(cdc37) that is unable to recruit HSP90 to the Raf-1 complex. Both agents abrogated the IFN-gamma-dependent induction of c-myc expression in Stat1-null cells.

A faster-acting and more potent form of tissue plasminogen activator

Current treatment with tissue plasminogen activator (tPA) requires an intravenous infusion (1.5-3 h) because the clearance of tPA from the circulation is rapid (t 1/2 approximately 6 min). We have developed a tPA variant, T103N,N117Q, KHRR(296-299)AAAA (TNK-tPA) that has substantially slower in vivo clearance (1.9 vs. 16.1 ml per min per kg for tPA in rabbits) and near-normal fibrin binding and plasma clot lysis activity (87% and 82% compared with wild-type tPA). TNK-tPA exhibits 80-fold higher resistance to plasminogen activator inhibitor 1 than tPA and 14-fold enhanced relative fibrin specificity. In vitro, TNK-tPA is 10-fold more effective at conserving fibrinogen in plasma compared to tPA. Arterial venous shunt models of fibrinolysis in rabbits indicate that TNK-tPA (by bolus) induces 50% lysis in one-third the time required by tPA (by infusion). TNK-tPA is 8- and 13-fold more potent in rabbits than tPA toward whole blood clots and platelet-enriched clots, respectively. TNK-tPA conserves fibrinogen and, because of its slower clearance and normal clot lysis activity, is effective as a thrombolytic agent when given as a bolus at a relatively low dose.

Mycobacterium species identification and rifampin resistance testing with high-density DNA probe arrays

Species identification within the genus Mycobacterium and subsequent antibiotic susceptibility testing still rely on time-consuming, culture-based methods. Despite the recent development of DNA probes, which greatly reduce assay time, there is a need for a single platform assay capable of answering the multitude of diagnostic questions associated with this genus. We describe the use of a DNA probe array based on two sequence databases: one for the species identification of mycobacteria (82 unique 16S rRNA sequences corresponding to 54 phenotypical species) and the other for detecting Mycobacterium tuberculosis rifampin resistance (rpoB alleles). Species identification or rifampin resistance was determined by hybridizing fluorescently labeled, amplified genetic material generated from bacterial colonies to the array. Seventy mycobacterial isolates from 27 different species and 15 rifampin-resistant M. tuberculosis strains were tested. A total of 26 of 27 species were correctly identified as well as all of the rpoB mutants. This parallel testing format opens new perspectives in terms of patient management for bacterial diseases by allowing a number of genetic tests to be simultaneously run.

Roles of phosphatidylinositol 3-kinase in interferon-gamma-dependent phosphorylation of STAT1 on serine 727 and activation of gene expression

STAT1 must be phosphorylated on serine 727 to be fully active in transcription. We show that phosphatidylinositol 3-kinase (PI3K) and its effector kinase Akt play an important role in the serine phosphorylation of STAT1 and in the activation of gene expression in response to interferon-gamma (IFN gamma). IFN gamma activates PI3K as well as Akt in a variety of cell lines. Specific inhibition of PI3K abrogates IFN gamma-induced, but not interleukin-1- or tumor necrosis factor-alpha-induced, phosphorylation of STAT1 on serine and reduces STAT1-dependent transcription and gene expression by approximately 7-fold. Constitutively active forms of PI3K or Akt activate and their dominant-negative derivatives inhibit STAT1-driven transactivation in response to IFN gamma. In addition to PI3K and Akt, JAK1, JAK2, and the tyrosine 440 STAT1 docking residue of IFNGR1 are required for STAT1 to be phosphorylated on serine. Taken together, these results suggest that the following events lead to the activation of STAT1 upon IFN gamma stimulation: 1) PI3K and Akt are activated by the occupied receptor and Tyr-440 is phosphorylated by the activated JAKs; 2) STAT1 docks to Tyr-440; and 3) Tyr-701 is phosphorylated by the JAKs and Ser-727 is phosphorylated by a kinase downstream of Akt.

Triggering the interferon response: the role of IRF-3 transcription factor

The interferon (IFN) regulatory factors (IRF) consist of a growing family of related transcription proteins first identified as regulators of the IFN-alpha/beta gene promoters, as well as the IFN-stimulated response element (ISRE) of some IFN-stimulated genes. IRF-3 was originally identified as a member of the IRF family based on homology with other IRF family members and on binding to the ISRE of the IFN-stimulated gene 15 (ISG15) promoter. Several recent studies have focused attention on the unique molecular properties of IRF-3 and its role in the regulation of IFN gene expression. IRF-3 is expressed constitutively in a variety of tissues, and the relative levels of IRF-3 mRNA do not change in virus-infected or IFN-treated cells. Following virus infection, IRF-3 is posttranslationally modified by protein phosphorylation at multiple serine and threonine residues, located in the carboxy-terminus of IRF-3. Phosphorylation causes the cytoplasmic to nuclear translocation of IRF-3, stimulation of DNA binding, and increased transcriptional activation, mediated through the association of IRF-3 with the CBP/p300 coactivator. The purpose of this review is to summarize recent investigations demonstrating the important role of IRF-3 in cytokine gene transcription. These studies provide the framework for a model in which virus-dependent phosphorylation of IRF-3 alters protein conformation to permit nuclear translocation, association with transcriptional partners, and primary activation of IFN and IFN-responsive genes.

Characterization of a functional NF-kappa B site in the human interleukin 1 beta promoter: evidence for a positive autoregulatory loop

The -300 region of the interleukin 1 beta (IL-1 beta) promoter contains a functional NF-kappa B binding site composed of the decamer sequence 5'-GGGAAAATCC-3'. Probes representing the -300 region or the NF-kappa B site alone interacted with NF-kappa B proteins present in phorbol myristate acetate-, lipopolysaccharide-, or Sendai virus-induced myeloid cell extracts as well as recombinant NFKB1 (p50) and RelA (p65); furthermore, NF-kappa B protein-DNA complex formation was dissociated in vitro by the addition of recombinant I kappa B alpha. Mutation of the NF-kappa B site in the context of the IL-1 beta promoter reduced the responsiveness of the IL-1 beta promoter to various inducers, including phorbol ester, Sendai virus, poly(rI-rC), and IL-1 beta. A 4.4-kb IL-1 beta promoter fragment linked to a chloramphenicol acetyltransferase reporter gene was also preferentially inducible by coexpression of individual NF-kappa B subunits compared with a mutated IL-1 beta promoter fragment. When multiple copies of the IL-1 beta NF-kappa B site were linked to an enhancerless simian virus 40 promoter, this element was able to mediate phorbol ester- or lipopolysaccharide-inducible gene expression. In cotransfection experiments, RelA (p65) and c-Rel (p85) were identified as the main subunits responsible for the activation of the IL-1 beta NF-kappa B site; also, combinations of NFKB1 (p50) and RelA (p65) or c-Rel and RelA were strong transcriptional activators of reporter gene activity. The presence of a functional NF-kappa B binding site in the IL-1 beta promoter suggests that IL-1 positively autoregulates its own synthesis, since IL-1 is a strong inducer of NF-kappa B binding activity. Thus, the IL-1 beta gene may be considered as an important additional member of the family of cytokine genes regulated in part by the NF-kappa B/rel family of transcription factors.

The distribution and cellular localization of the serotonin 1C receptor mRNA in the rodent brain examined by in situ hybridization histochemistry. Comparison with receptor binding distribution

The regional distribution and cellular localization of mRNA coding for the serotonin 1C receptor were investigated in tissue sections of mouse and rat brain by in situ hybridization histochemistry. Several 32P-labelled riboprobes derived from mouse genomic clones were used. The serotonin 1C receptor binding sites were visualized autoradiographically and quantified using [3H]mesulergine as ligand, in the presence of spiperone to block serotonin 1C receptors. Strong hybridization signal was observed in the choroid plexus of all brain ventricles. High levels of hybridization were also seen in the anterior olfactory nucleus, pyriform cortex, amygdala, some thalamic nuclei, especially the lateral habenula, the CA3 area of the hippocampal formation, the cingulate cortex, some components of the basal ganglia and associated areas, particularly the nucleus subthalamicus and the substantia nigra. The midbrain and brainstem showed moderate levels of hybridization. The distribution of the serotonin 1C receptor mRNA corresponded well to that of the serotonin 1C receptors. The highest levels of serotonin 1C receptor binding were observed in the choroid plexus. In addition, significant levels of the serotonin 1C receptor binding were seen in the anterior olfactory nucleus, pyriform cortex, nucleus accumbens, ventral aspects of the striatum, paratenial and paracentral thalamic nuclei, amygdaloid body and substantia nigra pars reticulata. The cingulate and retrosplenial cortices as well as the caudal aspects of the hippocampus (CA3) were also labelled. Binding in brainstem and medulla was low and homogeneously distributed. No significant binding was seen in the habenular and subthalamic nuclei. Similar findings were obtained in rat brain. These results demonstrate that, in addition to their enrichment in the choroid plexus, the serotonin 1C receptor mRNA and binding sites are heterogeneously distributed in the rodent brain and thus could be involved in the regulation of many different brain functions. The combination of in situ hybridization histochemistry with receptor autoradiography opens the possibility of examining the regulation of the serotonin 1C receptor synthesis after pharmacological or physiological alterations.

Loss of cell surface syndecan-1 causes epithelia to transform into anchorage-independent mesenchyme-like cells

Simple epithelial cells are polygonal in shape, polarized in an apical-basal orientation, and organized into closely adherent sheets, characteristics that result from a variety of cellular specializations and adhesive proteins. These characteristics are lost when the epithelia transform during embryogenesis into mesenchymal cells or after neoplasia into invasive carcinoma cells. Of the syndecan family of transmembrane heparan sulfate proteoglycans, simple epithelia produce predominantly syndecan-1, which is found at basolateral surfaces and within adhesive junctions. To elucidate the function of this syndecan-1, normal murine mammary gland epithelia were made deficient in syndecan-1 by transfection with an expression vector containing the syndecan-1 cDNA in the antisense configuration. Several independently derived clones of stable transfectants contained the antisense cDNA in their genome and expressed the antisense transcript. These grew either as epithelial islands of closely adherent polygonal cells, identical to both the parental cells and the vector-only control transfectants, or as individual elongated fusiform cells that invaded and migrated within collagen gels, like mesenchymal cells, but were anchorage-independent for growth. The clones that retained epithelial characteristics were moderately deficient in cell surface syndecan-1 (greater than 48% of control levels) but did not differ from control cells in expression of beta 1-integrins and E-cadherin, or in F-actin organization. However, the clones of fusiform cells were severely deficient in cell surface syndecan-1 (less than 12% of control levels) and showed rearranged beta 1-integrins, markedly reduced E-cadherin expression, and disorganized F-actin filaments, but retained mammary epithelial markers. Therefore, depleting epithelia of cell surface syndecan-1 alters cell morphology and organization, the arrangement and expression of adhesion molecules, and anchorage-dependent growth controls. Thus, cell surface syndecan-1 is required to maintain the normal phenotype of simple epithelia.

Lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot

BACKGROUND

The purpose of this study was to determine the degree to which pressure on the plantar aspect of the forefoot is reduced following percutaneous lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot.

METHODS

Ten diabetic patients who had a history of neuropathic plantar ulceration of the forefoot were enrolled in a laboratory gait trial. A repeated-measures design and a computer analysis of force-plate data were used to examine dynamic pressures on the forefoot, with the patient walking barefoot, immediately before percutaneous lengthening of the Achilles tendon and at eight weeks afterward. Although the wound in each patient had healed at least one month before the operation, we considered the patients to be at high risk for ulceration because they had had an ulcer previously.

RESULTS

The mean peak pressure (and standard deviation) on the plantar aspect of the forefoot decreased significantly from 86+/-9.4 newtons per square centimeter preoperatively to 63+/-13.2 newtons per square centimeter at eight weeks postoperatively (p<0.001). Commensurately, the mean dorsiflexion of the ankle joint increased significantly from 0+/-3.1 degrees preoperatively to 9+/-2.3 degrees at eight weeks post-operatively (p<0.001).

CONCLUSIONS

The results of this study suggest that peak pressures on the plantar aspect of the forefoot are significantly reduced following percutaneous lengthening of the Achilles tendon in diabetic patients who are at high risk for ulceration of the foot. We are unaware of any other reports in the medical literature that describe such findings. These data may lend support to studies that have indicated that this procedure should be used as an adjunctive therapeutic or prophylactic measure to reduce the risk of neuropathic ulceration.

Heparan sulfate proteoglycans from mouse mammary epithelial cells: localization on the cell surface with a monoclonal antibody

Mouse mammary epithelial cells, of the normal murine mammary gland (NMuMG) cell line, bear a heparan sulfate-rich proteoglycan (HSPG) on their surfaces. A hybridoma (281-2) secreting a monoclonal antibody that recognizes this HSPG was produced by fusion of SP-2/0 myeloma cells with spleen cells from rats immunized with NMuMG cells. The 281-2 monoclonal antibody is directed against the core protein of the cell surface HSPG, as demonstrated by (a) recognition of the isolated proteoglycan but not its glycosaminoglycan chains, (b) co-localization of 281-2-specific antigen and radioactive cell surface HSPG on gradient polyacrylamide gel electrophoresis and on isopycnic centrifugation, and (c) abolition of immunofluorescent staining of the NMuMG cell surface by the intact, but not the protease-digested ectodomain of the cell surface HSPG. The antibody is specific for cell surface HSPG and does not recognize the HSPG that accumulates extracellularly beneath the basal cell surface. Therefore, the 281-2 antibody may be used to isolate the cell surface HSPG and to explore its distribution in tissues.

Enhanced ribosomal association of p27(Kip1) mRNA is a mechanism contributing to accumulation during growth arrest

p27(Kip1) regulates the decision to enter into S-phase or withdraw from the cell cycle by establishing an inhibitory threshold above which G1 cyclin-dependent kinases accumulate before activation. We have used the HL-60 cell line to study regulation of p27 as cells withdraw from the cell cycle following treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). We found that the amount of p27 is maximal in G0 cells, lower in G1 cells, and undetectable in S-phase cells. In contrast to the protein, the amount of p27 mRNA was the same in these populations, suggesting that accumulation of p27 during the cell cycle and as cells withdraw from the cell cycle is controlled by post-transcriptional mechanisms. In S-phase cells, the degradation of p27 appears to predominate as a regulatory mechanism. In G0 cells, there was an increase in the synthesis rate of p27. Our data demonstrate that, in G0 cells, accumulation of p27 is due to an increase in the amount of p27 mRNA in polyribosomes.

Late onset of invasive aspergillus infection in bone marrow transplant patients at a university hospital

Despite new antifungal treatment strategies, invasive aspergillosis (IA) remains a principal cause of infectious mortality after bone marrow transplantation (BMT). We reviewed the medical records of 93 allogeneic and 149 autologous transplant recipients during a 20 month period, with attention to cases of proven or probable IA. No autologous transplant recipient developed IA, whereas IA was seen in 15.1% of allogeneic recipients (including two of five patients with a prior history of IA despite prophylaxis), for an overall incidence of 5.8%. The median time to occurrence was 92 days post transplant, with no de novo cases developing prior to engraftment. Survival 100 days from diagnosis was 29%. Risk factors for the development of IA included > or = 21 days of corticosteroid therapy of >or= 1mg/kg/day and post-transplant cytomegalovirus (CMV) infection. These two risk factors were statistically linked. Our data illustrate a shift toward a later occurrence of post-transplant IA, suggesting a need for close, prolonged surveillance in the outpatient environment. The contributory role of protracted corticosteroid use is also highlighted. These data have important implications in an era of alternate donor transplants and more intense immunosuppression. Established strategies implementing newer, less toxic antifungal agents as prophylaxis in high-risk patients are needed.