The ARH and Macrodomain Families of α-ADP-ribose-acceptor Hydrolases Catalyze α-NAD+ Hydrolysis

ADP-ribosyltransferases transfer ADP-ribose from β-NAD⁺ to acceptors; ADP-ribosylated acceptors are cleaved by ADP-ribosyl-acceptor hydrolases (ARHs) and proteins containing ADP-ribose-binding modules termed macrodomains. On the basis of the ADP-ribosyl-arginine hydrolase 1 (ARH1) stereospecific hydrolysis of α-ADP-ribosyl-arginine and the hypothesis that α-NAD⁺ is generated as a side product of β-NAD⁺/ NADH metabolism, we proposed that α-NAD⁺ was a substrate of ARHs and macrodomain proteins. Here, we report that ARH1, ARH3, and macrodomain proteins (i.e., MacroD1, MacroD2, C6orf130 (TARG1), Af1521, hydrolyzed α-NAD⁺ but not β-NAD⁺. ARH3 had the highest α-NADase specific activity. The ARH and macrodomain protein families, in stereospecific reactions, cleave ADP-ribose linkages to N- or O- containing functional groups; anomerization of α- to β-forms (e.g., α-ADP-ribosyl-arginine to β-ADP-ribose- (arginine) protein) may explain partial hydrolysis of ADP-ribosylated acceptors with an increase in content of ADP-ribosylated substrates. Af1521 and ARH3 crystal structures with bound ADP-ribose revealed similar ADP-ribose-binding pockets with the catalytic residues of the ARH and macrodomain protein families in the N-terminal helix and loop. Although the biological roles of the ARHs and macrodomain proteins differ, they share enzymatic and structural properties that may regulate metabolites such as α-NAD⁺.

Mono-ADP-Ribosylation Catalyzed by Arginine-Specific ADP-Ribosyltransferases

Methods are described for determination of arginine-specific mono-ADP-ribosyltransferase activity of purified proteins and intact cells by monitoring the transfer of ADP-ribose from NAD⁺ to a model substrate, e.g., arginine, agmatine, and peptide (human neutrophil peptide-1 [HNP1]), and for the nonenzymatic hydrolysis of ADP-ribose-arginine to ornithine, a noncoded amino acid. In addition, preparation of purified ADP-ribosylarginine is included as a control substrate for ADP-ribosylation reactions.

PARP1 inhibition alleviates injury in ARH3-deficient mice and human cells

Poly(ADP-ribosyl)ation refers to the covalent attachment of ADP-ribose to protein, generating branched, long chains of ADP-ribose moieties, known as poly(ADP-ribose) (PAR). Poly(ADP-ribose) polymerase 1 (PARP1) is the main polymerase and acceptor of PAR in response to DNA damage. Excessive intracellular PAR accumulation due to PARP1 activation leads cell death in a pathway known as parthanatos. PAR degradation is mainly controlled by poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribose-acceptor hydrolase 3 (ARH3). Our previous results demonstrated that ARH3 confers protection against hydrogen peroxide (H2O2) exposure, by lowering cytosolic and nuclear PAR levels and preventing apoptosis-inducing factor (AIF) nuclear translocation. We identified a family with an ARH3 gene mutation that resulted in a truncated, inactive protein. The 8-year-old proband exhibited a progressive neurodegeneration phenotype. In addition, parthanatos was observed in neurons of the patient's deceased sibling, and an older sibling exhibited a mild behavioral phenotype. Consistent with the previous findings, the patient's fibroblasts and ARH3-deficient mice were more sensitive, respectively, to H2O2 stress and cerebral ischemia/reperfusion-induced PAR accumulation and cell death. Further, PARP1 inhibition alleviated cell death and injury resulting from oxidative stress and ischemia/reperfusion. PARP1 inhibitors may attenuate the progression of neurodegeneration in affected patients with ARH3 deficiency.

Role of a TRIM72 ADP-ribosylation cycle in myocardial injury and membrane repair

Mono-ADP-ribosylation of an (arginine) protein catalyzed by ADP-ribosyltransferase 1 (ART1) - i.e., transfer of ADP-ribose from NAD to arginine - is reversed by ADP-ribosylarginine hydrolase 1 (ARH1) cleavage of the ADP-ribose-arginine bond. ARH1-deficient mice developed cardiomyopathy with myocardial fibrosis, decreased myocardial function under dobutamine stress, and increased susceptibility to ischemia/reperfusion injury. The membrane repair protein TRIM72 was identified as a substrate for ART1 and ARH1; ADP-ribosylated TRIM72 levels were greater in ARH1-deficient mice following ischemia/reperfusion injury. To understand better the role of TRIM72 and ADP-ribosylation, we used C2C12 myocytes. ARH1 knockdown in C2C12 myocytes increased ADP-ribosylation of TRIM72 and delayed wound healing in a scratch assay. Mutant TRIM72 (R207K, R260K) that is not ADP-ribosylated interfered with assembly of TRIM72 repair complexes at a site of laser-induced injury. The regulatory enzymes ART1 and ARH1 and their substrate TRIM72 were found in multiple complexes, which were coimmunoprecipitated from mouse heart lysates. In addition, the mono-ADP-ribosylation inhibitors vitamin K1 and novobiocin inhibited oligomerization of TRIM72, the mechanism by which TRIM72 is recruited to the site of injury. We propose that a mono-ADP-ribosylation cycle involving recruitment of TRIM72 and other regulatory factors to sites of membrane damage is critical for membrane repair and wound healing following myocardial injury.

The value of clinical teachers for EMR implementations and conversions

Effective physician training is an essential aspect of EMR implementation. However, it can be challenging to find instructors who can present the material in a clinically relevant manner. The authors describe a unique physician-training program, utilizing medical students as course instructors. This approach resulted in high learner satisfaction rates and provided significant cost-savings compared to alternative options.

Successful physician training program for large scale EMR implementation

End-user training is an essential element of electronic medical record (EMR) implementation and frequently suffers from minimal institutional investment. In addition, discussion of successful EMR training programs for physicians is limited in the literature. The authors describe a successful physician-training program at Stanford Children's Health as part of a large scale EMR implementation. Evaluations of classroom training, obtained at the conclusion of each class, revealed high physician satisfaction with the program. Free-text comments from learners focused on duration and timing of training, the learning environment, quality of the instructors, and specificity of training to their role or department. Based upon participant feedback and institutional experience, best practice recommendations, including physician engagement, curricular design, and assessment of proficiency and recognition, are suggested for future provider EMR training programs. The authors strongly recommend the creation of coursework to group providers by common workflow.

Nonenzymatic conversion of ADP-ribosylated arginines to ornithine alters the biological activities of human neutrophil peptide-1

Activated neutrophils, recruited to the airway of diseased lung, release human neutrophil peptides (HNP1-4) that are cytotoxic to airway cells as well as microbes. Airway epithelial cells express arginine-specific ADP ribosyltransferase (ART)-1, a GPI-anchored ART that transfers ADP-ribose from NAD to arginines 14 and 24 of HNP-1. We previously reported that ADP-ribosyl-arginine is converted nonenzymatically to ornithine and that ADP-ribosylated HNP-1 and ADP-ribosyl-HNP-(ornithine) were isolated from bronchoalveolar lavage fluid of a patient with idiopathic pulmonary fibrosis, indicating that these reactions occur in vivo. To determine effects of HNP-ornithine on the airway, three analogs of HNP-1, HNP-(R14orn), HNP-(R24orn), and HNP-(R14,24orn), were tested for their activity against Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus; their cytotoxic effects on A549, NCI-H441, small airway epithelial-like cells, and normal human lung fibroblasts; and their ability to stimulate IL-8 and TGF-β1 release from A549 cells, and to serve as ART1 substrates. HNP and the three analogs had similar effects on IL-8 and TGF-β1 release from A549 cells and were all cytotoxic for small airway epithelial cells, NCI-H441, and normal human lung fibroblasts. HNP-(R14,24orn), when compared with HNP-1 and HNP-1 with a single ornithine substitution for arginine 14 or 24, exhibited reduced cytotoxicity, but it enhanced proliferation of A549 cells and had antibacterial activity. Thus, arginines 14 and 24, which can be ADP ribosylated by ART1, are critical to the regulation of the cytotoxic and antibacterial effects of HNP-1. The HNP analog, HNP-(R14,24orn), lacks the epithelial cell cytotoxicity of HNP-1, but partially retains its antibacterial activity and thus may have clinical applications in airway disease.

Evidence for a common mechanism of SIRT1 regulation by allosteric activators

A molecule that treats multiple age-related diseases would have a major impact on global health and economics. The SIRT1 deacetylase has drawn attention in this regard as a target for drug design. Yet controversy exists around the mechanism of sirtuin-activating compounds (STACs). We found that specific hydrophobic motifs found in SIRT1 substrates such as PGC-1α and FOXO3a facilitate SIRT1 activation by STACs. A single amino acid in SIRT1, Glu(230), located in a structured N-terminal domain, was critical for activation by all previously reported STAC scaffolds and a new class of chemically distinct activators. In primary cells reconstituted with activation-defective SIRT1, the metabolic effects of STACs were blocked. Thus, SIRT1 can be directly activated through an allosteric mechanism common to chemically diverse STACs.

TSC2Loss in Lymphangioleiomyomatosis Cells Correlated with Expression of CD44v6, a Molecular Determinant of Metastasis

Lymphangioleiomyomatosis (LAM), a rare multisystem disease found primarily in women of childbearing age, is characterized by the proliferation of abnormal smooth muscle-like cells, LAM cells, that form nodules in the pulmonary interstitium. Proliferation of LAM cells results, in part, from dysfunction in tuberous sclerosis complex (TSC) genes TSC1 (hamartin) and/or TSC2 (tuberin). Identification of LAM cells in donor lungs, their isolation from blood, and their presence in urine, chylous ascites, and pleural effusions are consistent with their ability to metastasize. Here, we investigated the presence on LAM cells of the hyaluronic acid receptor CD44 and its splice variants associated with metastasis. The heterogeneous populations of cells grown from lungs of 12 LAM patients contain cells expressing mRNA for the variant CD44v6. Histologically, CD44v6 was present in LAM lung nodules, but not in normal vascular smooth muscle cells. CD44v6-positive sorted cells showed loss of heterozygosity at the TSC2 locus; binding of CD44v6 antibody resulted in loss of cell viability. Levels of CD44 were higher in cultured Eker rat (Tsc2-/-) cells than in Tsc2+/+ cells, but unlike human LAM cells, the Tsc2-/- Eker rat cells did not contain CD44v6 splice variant mRNA. CD44 splicing and signaling is regulated by osteopontin. Plasma from LAM patients contained higher concentrations of osteopontin than plasma of healthy, age-, and sex-matched volunteers (P = 0.00003) and may be a biomarker for LAM. The cell surface receptor CD44 and its splice variant CD44v6 may contribute to the metastatic potential of LAM cells.

Kidney function estimating equations: where do we stand?

PURPOSE OF REVIEW

Estimation of the glomerular filtration rate (GFR) is central to the diagnosis, evaluation and management of chronic kidney disease. This review summarizes recent data on the performance of equations using serum creatinine to estimate the GFR, particularly the Modification of Diet in Renal Disease (MDRD) Study equation.

RECENT FINDINGS

During 2005 GFR estimation has received substantial attention with a focus on comparing the MDRD Study equation with the Cockcroft-Gault equation. Several large studies (n>500) have appeared. Most studies discuss creatinine calibration but few were able to standardize measurements. Studies that did calibrate the creatinine had improved performance. Overall, the MDRD Study equation performed well in populations with a low range of GFR and often outperformed the Cockcroft-Gault equation. Both equations have lower precision in high GFR populations, and the MDRD equation under-estimated the GFR in a number of studies. Efforts are underway to develop improved prediction equations by pooling data across many study populations.

SUMMARY

Equations for estimating the GFR from serum creatinine are useful for systematic staging of chronic kidney disease. The MDRD Study equation and systematic creatinine assay calibration improve the level of precision and accuracy in many settings. GFR estimates are less useful in the normal range of GFR, however, and are sensitive to the population under study.

Muscarinic receptor function, density and G-protein coupling in the overactive diabetic rat bladder

1 Bladder smooth muscle sensitivity to muscarinic agonists is increased in the overactive bladder. Treatment of rats with streptozotocin induces a diabetic state in which the bladder muscle is overactive and also supersensitive to muscarinic agonists. This study has examined bladder contraction, muscarinic receptor density and receptor/G-protein coupling in the streptozotocin-induced overactive bladder of the rat. 2 Diabetes was induced by a single intraperitoneal dose of streptozotocin. Seven days later contraction of isolated detrusor muscle strips was assessed in tissue bath experiments, while receptor density was assayed in saturation experiments with [3H]-QNB (quinuclidinyl benzilate, L-[benzilic-4,4'-3H]) and receptor/G-protein coupling was determined in agonist displacement experiments with this radioligand. 3 Isolated detrusor strips from diabetic animals displayed an enhanced degree of spontaneous activity (0.060 +/- 0.016 g mg(-1), compared with 0.015 +/- 0.004 g mg(-1), P < 0.05). Carbachol produced contractile responses in tissues from both control and diabetic rats, but the diabetic tissues were more sensitive to this agonist, the pEC50 being 6.52 +/- 0.17 compared with 5.93 +/- 0.06 in controls (P < 0.001). Maximum responses to carbachol were similar in both groups of animals. The increase in carbachol potency was accompanied by a 40% increase in receptor density from 158 +/- 5 to 221 +/- 22 fmol mg(-1) protein (P < 0.05), but this was not enough to fully account for the change in tissue sensitivity. 4 In the absence of GTP-gamma-S, carbachol displaced [3H]-QNB from two binding sites, the high-affinity site (pKi = 7.06 +/- 0.26) which represents the receptors coupled to G-proteins made up 43.1 +/- 5.9% of the total binding sites in control tissues and this value was similar (41.0 +/- 4.0%) in the diabetic tissues (pKi = 6.64 +/- 0.31). In the presence of GTP-gamma-S, carbachol displaced [3H]-QNB from a single binding site which had a low-affinity, similar to the low-affinity site observed in the absence of GTP-gamma-S. 5 These data demonstrate that detrusor supersensitivity is observed after only 1 week of untreated diabetes in the rat. The overactivity is associated with an enhanced sensitivity to carbachol, which is partly explained by an increase in receptor density, but there appears to be no change in receptor/G-protein coupling.

ART2, a T cell surface mono-ADP-ribosyltransferase, generates extracellular poly(ADP-ribose)

NAD functions in multiple aspects of cellular metabolism and signaling through enzymes that covalently transfer ADP-ribose from NAD to acceptor proteins, thereby altering their function. NAD is a substrate for two enzyme families, mono-ADP-ribosyltransferases (mARTs) and poly(ADP-ribose) polymerases (PARPs), that covalently transfer an ADP-ribose monomer or polymer, respectively, to acceptor proteins. ART2, a mART, is a phenotypic marker of immunoregulatory cells found on the surface of T lymphocytes, including intestinal intraepithelial lymphocytes (IELs). We have shown that the auto-ADP-ribosylation of the ART2.2 allelic protein is multimeric. Our backbone structural alignment of ART2 (two alleles of the rat art2 gene have been reported, for simplicity, the ART2.2 protein investigated in this study will be referred to as ART2) and PARP suggested that multimeric auto-ADP-ribosylation of ART2 may represent an ADP-ribose polymer, rather than multiple sites of mono-ADP-ribosylation. To investigate this, we used highly purified recombinant ART2 and demonstrated that ART2 catalyzes the formation of an ADP-ribose polymer by sequencing gel and by HPLC and MS/MS mass spectrometry identification of PR-AMP, a breakdown product specific to poly(ADP-ribose). Furthermore, we identified the site of ADP-ribose polymer attachment on ART2 as Arg-185, an arginine in a crucial loop of its catalytic core. We found that endogenous ART2 on IELs undergoes multimeric auto-ADP-ribosylation more efficiently than ART2 on peripheral T cells, suggesting that these distinct lymphocyte populations differ in their ART2 surface topology. Furthermore, ART2.2 IELs are more resistant to NAD-induced cell death than ART2.1 IELs that do not have multimeric auto-ADP-ribosylation activity. The data suggest that capability of polymerizing ADP-ribose may not be unique to PARPs and that poly(ADP-ribosylation), an established nuclear activity, may occur extracellularly and modulate cell function.

ADP-ribosyltransferase-specific modification of human neutrophil peptide-1

Epithelial cells lining human airways and cells recruited to airways participate in the innate immune response in part by releasing human neutrophil peptides (HNP). Arginine-specific ADP-ribosyltransferases (ART) on the surface of these cells can catalyze the transfer of ADP-ribose from NAD to proteins. We reported that ART1, a mammalian ADP-ribosyltransferase, present in epithelial cells lining the human airway, modified HNP-1, altering its function. ADP-ribosylated HNP-1 was identified in bronchoalveolar lavage fluid (BALF) from patients with asthma, idiopathic pulmonary fibrosis, or a history of smoking (and having two common polymorphic forms of ART1 that differ in activity), but not in normal volunteers or patients with lymphangioleiomyomatosis. Modified HNP-1 was not found in the sputum of cystic fibrosis patients or in leukocyte granules of normal volunteers. The finding of ADP-ribosyl-HNP-1 in BALF but not in leukocyte granules suggests that the modification occurred in the airway. Most of the HNP-1 in the BALF from individuals with a history of smoking was, in fact, mono- or di-ADP-ribosylated. ART1 synthesized in Escherichia coli, glycosylphosphatidylinositol-anchored ART1 released with phosphatidylinositol-specific phospholipase C from transfected NMU cells, or ART1 expressed endogenously on C2C12 myotubes modified arginine 14 on HNP-1 with a secondary site on arginine 24. ADP-ribosylation of HNP-1 by ART1 was substantially greater than that by ART3, ART4, ART5, Pseudomonas aeruginosa exoenzyme S, or cholera toxin A subunit. Mouse ART2, which is an NAD:arginine ADP-ribosyltransferase, was able to modify HNP-1, but to a lesser extent than ART1. Although HNP-1 was not modified to a significant degree by ART5, it inhibited ART5 as well as ART1 activities. Human beta-defensin-1 (HBD1) was a poor transferase substrate. Reduction of the cysteine-rich defensins enhanced their ability to serve as ADP-ribose acceptors. We conclude that ADP-ribosylation of HNP-1 appears to be primarily an activity of ART1 and occurs in inflammatory conditions and disease.

Regulatory role of arginine 204 in the catalytic activity of rat alloantigens ART2a and ART2b

ART2a (RT6.1) and ART2b (RT6.2) are NAD glycohydrolases (NADases) that are linked to T lymphocytes by glycosylphosphatidylinositol anchors. Although both mature proteins possess three conserved regions (I, II, III) that form the NAD-binding site and differ by only ten amino acids, only ART2b is auto-ADP-ribosylated and only ART2a is glycosylated. To investigate the structural basis for these differences, wild-type and mutant ART2a and ART2b were expressed in rat mammary adenocarcinoma (NMU) cells and released with phosphatidylinositol-specific phospholipase C. All mutants were immunoreactive NADases. Arginine 204 (Arg204), NH2-terminal to essential glutamate 209 in Region III, is found in ART2b, but not ART2a. Replacement of Arg204 in ART2b with lysine, tyrosine, or glutamate abolished auto-ADP-ribosylation. Unlike wild-type ART2a, ART2a(Y204R) was auto-ADP-ribosylated. The tryptophan mutant ART2b(R204W) was auto-ADP-ribosylated and exhibited enhanced NADase activity. Incubation with NAD and auto-ADP-ribosylation decreased the NADase activities of wild-type ART2b and ART2b (R204W), whereas activity of ART2b(R204K), which is not auto-modified, was unchanged by NAD. Facilitation of auto-ADP-ribosylation by tryptophan 204 suggests that the hydrophobic amino acid mimics an ADP-ribosylated arginine. Thus, Arg204 in ART2b serves as a regulatory switch whose presence is required for additional auto-ADP-ribosylation and regulation of catalytic activity.

ADP ribosylation of human neutrophil peptide-1 regulates its biological properties

In human airways, epithelial cells lining the lumen and intraluminal cells (e.g., polymorphonuclear cells) participate in the innate immune response. These cells secrete or express on their surfaces arginine-specific ADP ribosyltransferases. Defensins, antimicrobial proteins secreted by immune cells, are arginine-rich, leading us to hypothesize that ADP ribosylation could modify their biological activities. We found that an arginine-specific ADP ribosyltransferase-1 present on airway epithelial cells modifies Arg-14 of alpha defensin-1. ADP-ribosylated defensin-1 had decreased antimicrobial and cytotoxic activities but still stimulated T cell chemotaxis and IL-8 release from A549 cells. Further, ADP-ribosylated defensin-1 inhibited cytotoxic and antimicrobial activities of unmodified defensin-1. We identified ADP-ribosylated defensin-1 in bronchoalveolar lavage fluid from smokers but not from nonsmokers, confirming its existence in vivo. Thus, airway mono-ADP-ribosyltransferases could have an important regulatory role in the innate immune response through modification of alpha defensin-1 and perhaps other basic molecules, with alteration of their biological properties.

Giles F. Filley Lecture. Genetics and gene expression in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a disease of unknown etiology that is characterized by the proliferation of abnormal smooth muscle cells (LAM cells) in the lung, which leads to cystic parenchymal destruction and progressive respiratory failure. Recent evidence suggests that the proliferative and invasive nature of LAM cells may be due, in part, to somatic mutations in the TSC2 gene, which has been implicated in the pathogenesis of tuberous sclerosis complex. Here, we describe the clinical and molecular characteristics of LAM, as well as the efforts now under way to understand the genetic and biochemical factors that lead to progressive pulmonary destruction and, ultimately, to lung transplantation or death.

Nicotinamide adenine dinucleotide (NAD) and its metabolites inhibit T lymphocyte proliferation: role of cell surface NAD glycohydrolase and pyrophosphatase activities

The presence of NAD-metabolizing enzymes (e.g., ADP-ribosyltransferase (ART)2) on the surface of immune cells suggests a potential immunomodulatory activity for ecto-NAD or its metabolites at sites of inflammation and cell lysis where extracellular levels of NAD may be high. In vitro, NAD inhibits mitogen-stimulated rat T cell proliferation. To investigate the mechanism of inhibition, the effects of NAD and its metabolites on T cell proliferation were studied using ART2a+ and ART2b+ rat T cells. NAD and ADP-ribose, but not nicotinamide, inhibited proliferation of mitogen-activated T cells independent of ART2 allele-specific expression. Inhibition by P2 purinergic receptor agonists was comparable to that induced by NAD and ADP-ribose; these compounds were more potent than P1 agonists. Analysis of the NAD-metabolizing activity of intact rat T cells demonstrated that ADP-ribose was the predominant metabolite, consistent with the presence of cell surface NAD glycohydrolase (NADase) activities. Treatment of T cells with phosphatidylinositol-specific phospholipase C removed much of the NADase activity, consistent with at least one NADase having a GPI anchor; ART2- T cell subsets contained NADase activity that was not releasable by phosphatidylinositol-specific phospholipase C treatment. Formation of AMP from NAD and ADP-ribose also occurred, a result of cell surface pyrophosphatase activity. Because AMP and its metabolite, adenosine, were less inhibitory to rat T cell proliferation than was NAD or ADP-ribose, pyrophosphatases may serve a regulatory role in modifying the inhibitory effect of ecto-NAD on T cell activation. These data suggest that T cells express multiple NAD and adenine nucleotide-metabolizing activities that together modulate immune function.

Pharmacokinetics of glycosylated recombinant human granulocyte colony-stimulating factor (lenograstim) in healthy male volunteers

AIMS

The aim of this open, randomised, crossover, parallel-group study was to compare the pharmacokinetics and neutrophil responses of lenograstim when administered subcutaneously (s.c.) and intravenously (i.v.).

METHODS

A total of 27 healthy male volunteers was recruited. Lenograstim doses (0.5, 2, 5, or 10 microg kg(-1)) were administered s.c. or i.v. once-daily for 5 days, and then, after a 10-day washout period, vice versa for a further 5 days. Lenograstim concentrations and absolute neutrophil counts (ANCs) were measured predosing and postdosing on days 1 and 5.

RESULTS

Maximum serum concentrations of lenograstim were higher following i.v. dosing (mean 5.2-185.5 vs 0.7-30.0 ng ml(-1) after s.c. dosing on day 1) and attained sooner (median 0.5-0.8 vs 4.7-8.7 h on day 1). However, apparent elimination half-lives of lenograstim were longer following s.c. dosing (mean 2.3-3.3 vs 0.8-1.2 h after i.v. dosing on days 1 and 5). ANCs increased in a dose-dependent manner with both routes of lenograstim, but more prolonged rises and higher ANC peaks were attained following s.c. doses. ANCs peaked on day 6 following 5 microg kg(-1) s.c. doses (mean peak=26.3x10(9) cells l(-1)), but on day 2 after 5 microg kg(-1) i.v. doses (mean peak = 12.4 x 10(9) cells l(-1)). Irrespective of route, the most common adverse events were headaches and back/spine pain; at doses of up to 5 microg kg(-1) these were mild and generally well tolerated.

CONCLUSIONS

While supporting the use of both s.c. and i.v. administered lenograstim to treat neutropenia, these results demonstrate that neutrophil responses are more sustained and prolonged with the s.c. route.

The RT6 (Art2) family of ADP-ribosyltransferases in rat and mouse

Recent evidence suggests that a new member of the mono-ADP-ribosyltransferase/NAD glycohydrolase family, RT6, may be important in immune regulation. RT6 is expressed in two allelic forms and is present on post-thymic T cells in the rat. RT6-expressing T cells in the rat may have a regulatory role, a conclusion based on their ability to prevent autoimmune diabetes in the BB rat model of insulin-dependent diabetes mellitus. This observation led to investigation of RT6 at a molecular and biochemical level resulting in the determination that RT6 protein exists as both glycosylated and non-glycosylated glycosylphosphatidylinositol (GPI)-linked cell surface molecules. RT6, like many GPI-linked proteins, can mediate cell signal transduction events associated with T cell activation, and is also present in a soluble form in the circulation. The discovery that RT6 is an NAD glycohydrolase and auto-ADP-ribosyltransferase led to the ongoing investigations into the role that enzymatic activity may have in the immunoregulatory function of rat RT6+ T cells. A homologue of rat RT6, termed Rt6, has been identified in the mouse. Rt6 is predominately an ADP-ribosyltransferase enzyme as determined using simple guanidino compounds (e.g. arginine) as ribose acceptors. Abnormalities in mouse Rt6 mRNA are associated with the expression of autoimmunity. In the present manuscript, we review recent data on RT6/Rt6, and discuss the potential mechanisms by which RT6-expressing cells, and perhaps RT6 protein itself, may mediate immune regulation.

Characterization of NAD:arginine ADP-ribosyltransferases

NAD:arginine mono-ADP-ribosyltransferases catalyze the transfer of ADP-ribose from NAD to the guanidino group of arginine on a target protein. Deduced amino acid sequences of one family (ART1) of mammalian ADP-ribosyltransferases, cloned from muscle and lymphocytes, show hydrophobic amino and carboxyl termini consistent with glycosylphosphatidylinositol (GPI)-anchored proteins. The proteins, overexpressed in mammalian cells transfected with the transferase cDNAs, are released from the cell surface with phosphatidylinositol-specific phospholipase C (PI-PLC), and display immunological and biochemical characteristics consistent with a cell surface, GPI-anchored protein. In contrast, the deduced amino acid sequence of a second family (ART5) of transferases, cloned from murine lymphoma cells and expressed in high abundance in testis, displays a hydrophobic amino terminus, consistent with a signal sequence, but lacks a hydrophobic signal sequence at its carboxyl terminus, suggesting that the protein is destined for export. Consistent with the surface localization of the GPI-linked transferases, multiple surface substrates have been identified in myotubes and activated lymphocytes, and, notably, include integrin alpha subunits. Similar to the bacterial toxin ADP-ribosyltransferases, the mammalian transferases contain the characteristic domains involved in NAD binding and ADP-ribose transfer, including a highly acidic region near the carboxy terminus, which, when disrupted by in vitro mutagenesis, results in a loss of enzymatic activity. The carboxyl half of the protein, synthesized as a fusion protein in E. coli, possessed NADase, but not ADP-ribosyltransferase activity. These findings are consistent with the existence at the carboxyl terminus of ART1 of a catalytically active domain, capable of hydrolyzing NAD, but not of transferring ADP-ribose to a guanidino acceptor.

Effects of site-directed mutagenesis of Escherichia coli heat-labile enterotoxin on ADP-ribosyltransferase activity and interaction with ADP-ribosylation factors

Escherichia coli heat-labile enterotoxin (LT), an oligomeric protein with one A subunit (LTA) and five B subunits, exerts its effects via the ADP-ribosylation of Gsalpha, a guanine nucleotide-binding (G) protein that activates adenylyl cyclase. LTA also ADP-ribosylates simple guanidino compounds (e.g., arginine) and catalyzes its own auto-ADP-ribosylation. All LTA-catalyzed reactions are enhanced by ADP-ribosylation factors (ARFs), 20-kDa guanine nucleotide-binding proteins. Replacement of arginine-7 (R7K), valine-53 (V53D), serine-63 (S63K), valine 97 (V97K), or tyrosine-104 (Y104K) in LTA resulted in fully assembled but nontoxic proteins. S63K, V53D, and R7K are catalytic-site mutations, whereas V97K and Y104K are amino acid replacements adjacent to and outside of the catalytic site, respectively. The effects of mutagenesis were quantified by measuring ADP-ribosyltransferase activity (i.e., auto-ADP-ribosylation and ADP-ribosylagmatine synthesis) and interaction with ARF (i.e., inhibition of ARF-stimulated cholera toxin ADP-ribosyltransferase activity and effects of ARF on mutant auto-ADP-ribosylation). All mutants were inactive in the ADP-ribosyltransferase assay; however, auto-ADP-ribosylation in the presence of recombinant human ARF6 was detected, albeit much less than that of native LT (Y104K > V53D > V97K > R7K, S63K). Based on the lack of inhibition by free ADP-ribose, the observed auto-ADP-ribosylation activity was enzymatic and not due to the nonenzymatic addition of free ADP-ribose. V53D, S63K, and R7K were more effective than Y104K or V97K in blocking ARF stimulation of cholera toxin ADP-ribosyltransferase. Based on these data, it appears that ARF-binding and catalytic sites are not identical and that a region outside the NAD cleft may participate in the LTA-ARF interaction.

Expression in BALB/c and C57BL/6 mice of Rt6-1 and Rt6-2 ADP-ribosyltransferases that differ in enzymatic activity: C57BL/6 Rt6-1 is a natural transferase knockout

Several proteins with NAD+:arginine ADP-ribosyltransferase (ART) activity are expressed in T cells and affect their function. Rat T cells that express the ART designated RT6 are determinants of the expression of autoimmune diabetes. In the mouse, a 35-kDa ecto-ART modulates the proliferation and functional activity of CTL. Here we report on mouse ARTs designated Rt6-1 and Rt6-2 in BALB/c and C57BL/6 mice. mRNAs for Rt6-1 and Rt6-2 were found in spleen, thymus, and intestinal tissue of both strains, but Rt6-1 mRNA in C57BL/6 mice was detected only at low levels. Rt6-1 and Rt6-2 cDNAs from both strains were cloned and sequenced. Predicted amino acid sequences of Rt6-2 were identical in both strains, but there was an in-frame stop codon in the sequence of Rt6-1 in C57BL/6 mice not present in BALB/c mice. Recombinant C57BL/6 Rt6-2 and BALB/c Rt6-1 proteins expressed in COS1 cells exhibited ART activity and were documented to be glycosylphosphatidylinositol-linked membrane proteins. COS-1 cells transfected with a C57BL/6 Rt6-1 cDNA construct expressed a truncated protein consistent in size with that predicted by the presence of the stop codon. This approximately 21-kDa protein appeared not to be glycosylphosphatidylinositol linked to the cell surface and lacked ART activity. C57BL/6 Rt6-1 therefore appears to be a naturally occurring ART knockout. The expression of Rt6-1 and Rt6-2 mRNAs in lymphoid tissues suggests that these ARTs may regulate immune system functions. Expression of Rt6-2 or another redundant ART may compensate for the lack of enzymatically active Rt6-1 in C57BL/6 mice.

Expression in BALB/c and C57BL/6 mice of Rt6-1 and Rt6-2 ADP-ribosyltransferases that differ in enzymatic activity: C57BL/6 Rt6-1 is a natural transferase knockout

Several proteins with NAD+:arginine ADP-ribosyltransferase (ART) activity are expressed in T cells and affect their function. Rat T cells that express the ART designated RT6 are determinants of the expression of autoimmune diabetes. In the mouse, a 35-kDa ecto-ART modulates the proliferation and functional activity of CTL. Here we report on mouse ARTs designated Rt6-1 and Rt6-2 in BALB/c and C57BL/6 mice. mRNAs for Rt6-1 and Rt6-2 were found in spleen, thymus, and intestinal tissue of both strains, but Rt6-1 mRNA in C57BL/6 mice was detected only at low levels. Rt6-1 and Rt6-2 cDNAs from both strains were cloned and sequenced. Predicted amino acid sequences of Rt6-2 were identical in both strains, but there was an in-frame stop codon in the sequence of Rt6-1 in C57BL/6 mice not present in BALB/c mice. Recombinant C57BL/6 Rt6-2 and BALB/c Rt6-1 proteins expressed in COS1 cells exhibited ART activity and were documented to be glycosylphosphatidylinositol-linked membrane proteins. COS-1 cells transfected with a C57BL/6 Rt6-1 cDNA construct expressed a truncated protein consistent in size with that predicted by the presence of the stop codon. This approximately 21-kDa protein appeared not to be glycosylphosphatidylinositol linked to the cell surface and lacked ART activity. C57BL/6 Rt6-1 therefore appears to be a naturally occurring ART knockout. The expression of Rt6-1 and Rt6-2 mRNAs in lymphoid tissues suggests that these ARTs may regulate immune system functions. Expression of Rt6-2 or another redundant ART may compensate for the lack of enzymatically active Rt6-1 in C57BL/6 mice.

Characterization of mouse Rt6.1 NAD:arginine ADP-ribosyltransferase

Rat RT6 proteins, and perhaps mouse Rt6, identify a set of immunoregulatory T lymphocytes. Rat RT6.1 (RT6.1) and rat RT6.2 (RT6. 2) are NAD glycohydrolases, which catalyze auto-ADP-ribosylation, but not ADP-ribosylation of exogenous proteins. Mouse Rt6.1 (mRt6.1) also catalyzes auto-ADP-ribosylation. The activity of mouse cytotoxic T lymphocytes is reportedly inhibited by ADP-ribosylation of surface proteins, raising the possibility that mRt6 may participate in this process. The reactions catalyzed by mRt6, would, however, need to be more diverse than those of the rat homologues and include the ADP-ribosylation of acceptors other than itself. To test this hypothesis, mRt6.1 and rat RT6.2 were synthesized in Sf9 insect cells and rat mammary adenocarcinoma (NMU) cells. mRt6.1, but not rat RT6.2, catalyzed the ADP-ribosylation of guanidino-containing compounds (e.g. agmatine). Unlike RT6.2, mRt6.1 was a weak NAD glycohydrolase. In the presence of agmatine, however, the ratio of [adenine-14C]ADP-ribosylagmatine formation from [adenine-14C]NAD to [carbonyl-14C]nicotinamide formation from [carbonyl-14C]NAD was approximately 1.0, demonstrating that mRt6.1 is primarily a transferase. ADP-ribosylarginine hydrolase, which preferentially hydrolyzes the alpha-anomer of ADP-ribosylarginine, released [U-14C]arginine from ADP-ribosyl[U-14C]arginine synthesized by mRT6.1, consistent with the conclusion that mRt6.1 catalyzes a stereospecific Sn2-like reaction. Thus, mRt6.1 is an NAD:arginine ADP-ribosyltransferase capable of catalyzing a multiple turnover, stereospecific Sn2-like reaction.

Expression in human endothelial cells of ADP-ribosylation factors, 20-kDa guanine nucleotide-binding proteins involved in the initiation of vesicular transport

ADP-ribosylation factors (ARFs) are approximately 20-kDa, guanine nucleotide-binding proteins, initially discovered as stimulators of cholera toxin ADP-ribosyltransferase activity and subsequently shown to participate in vesicular trafficking. Five of the six mammalian ARFs have been identified in human tissues by molecular cloning. They fall into three classes (class I: ARFs 1-3; class II: ARFs 4, 5; class III: ARF 6) based on deduced amino acid sequence, size, phylogenetic analysis, and gene structure. Similar to the rab family of approximately 20 kDa guanine nucleotide-binding proteins, the ARFs appear to function in specific trafficking pathways. The presence of a specific ARF might serve as a marker for that pathway. To verify expression of ARF mRNA and protein in human umbilical vein endothelial cells, immunoreactivity using antibodies specific for each ARF class, quantitative polymerase chain reaction (PCR) using ARF-specific, internal cRNA standards containing unique restriction enzyme cleavage sites introduced by point mutations, and Northern analysis with probes specific for ARFs 1, and 3-6, were utilized. PCR and Northern analysis were in agreement in showing that amounts of mRNA for ARF 1 and ARF 4 were similar and higher than those of ARF 3 and ARF 5 which were greater than ARF 6. Primarily, Class 1 ARF proteins were detected by immunoreactivity, with the majority in the supernatant fraction. The relative expression of ARFs in endothelial cells thus differs from that in neuronal tissues where it had been found that ARF3 is the predominant species.

Rat RT6.2 and mouse Rt6 locus 1 are NAD+: arginine ADP ribosyltransferases with auto-ADP ribosylation activity

RT6 is a glycosylphosphatidylinositol-linked protein found on the surface of mature rat T lymphocytes. Cells that express RT6 have an immunoregulatory function and modulate the expression of autoimmune diabetes mellitus in the BioBreeding rat. A homologue of the rat RT6 gene, designated Rt6, has been identified in the mouse, but expression of mouse Rt6 protein has not been documented. Rat RT6 is known to be a nicotinamide adenine dinucleotide (NAD+) glycohydrolase. We now report that rat RT6.2 and recombinant mouse Rt6 locus 1 proteins possess auto-ADP ribosylation activity. In addition, mouse Rt6 but not rat RT6, catalyzes the ADP ribosylation of exogenous acceptors such as histones. The ADP-ribosyl-protein bonds in auto-ADP-ribosylated rat RT6.2, auto-ADP-ribosylated mouse Rt6, and ADP-ribosylhistone synthesized by Rt6 were stable to HgCl2 and HCl, but labile to NH2OH, consistent with ADP ribosylarginine linkages. To determine if these enzymatic activities could affect the function of rat T cells, the effect of substrate availability on lymphocyte proliferation was examined. An inverse correlation was observed between NAD+ concentration in the medium and the ability of rat T cells to respond to anti-CD3, ConA, and PMA plus ionomycin. The data suggest that lymphocyte surface ADP ribosyltransferases could be involved in signaling and immunoregulatory processes.

Rat RT6.2 and mouse Rt6 locus 1 are NAD+: arginine ADP ribosyltransferases with auto-ADP ribosylation activity

RT6 is a glycosylphosphatidylinositol-linked protein found on the surface of mature rat T lymphocytes. Cells that express RT6 have an immunoregulatory function and modulate the expression of autoimmune diabetes mellitus in the BioBreeding rat. A homologue of the rat RT6 gene, designated Rt6, has been identified in the mouse, but expression of mouse Rt6 protein has not been documented. Rat RT6 is known to be a nicotinamide adenine dinucleotide (NAD+) glycohydrolase. We now report that rat RT6.2 and recombinant mouse Rt6 locus 1 proteins possess auto-ADP ribosylation activity. In addition, mouse Rt6 but not rat RT6, catalyzes the ADP ribosylation of exogenous acceptors such as histones. The ADP-ribosyl-protein bonds in auto-ADP-ribosylated rat RT6.2, auto-ADP-ribosylated mouse Rt6, and ADP-ribosylhistone synthesized by Rt6 were stable to HgCl2 and HCl, but labile to NH2OH, consistent with ADP ribosylarginine linkages. To determine if these enzymatic activities could affect the function of rat T cells, the effect of substrate availability on lymphocyte proliferation was examined. An inverse correlation was observed between NAD+ concentration in the medium and the ability of rat T cells to respond to anti-CD3, ConA, and PMA plus ionomycin. The data suggest that lymphocyte surface ADP ribosyltransferases could be involved in signaling and immunoregulatory processes.

Tracheal colonization factor: a Bordetella pertussis secreted virulence determinant

We report here the identification of a virulence-associated factor, Tcf, (tracheal colonization factor), produced by strains of Bordetella pertussis but not Bordetella parapertussis or Bordetella bronchiseptica. This protein is encoded by the tcfA gene. When a strain of B. pertussis 18323 lacking this protein is used to infect mice with an aerosol challenge, the number of bacteria isolated from the tracheas is decreased 10-fold when compared with the parent 18323. The derived amino acid sequence of tcfA predicts a 68 kDa RGD-containing, proline-rich protein, which after cleavage of a typical prokaryotic signal sequence would be 64 kDa. Amino acid sequence analysis demonstrates that the C-terminal 30 kDa of this protein shows 50% identity to the 30 kDa C-terminus of another Bordetella protein, the pertactin precursor. The N-terminal 34 kDa region contains the three amino-acid motif RGD and is 16.5% proline. Coupled in vitro transcription and translation analysis indicates that the tcfA gene product migrates as two bands of approximately 90 kDa. A fusion protein of the N-terminal, 34 kDa portion of Tcf to maltose-binding protein migrates, on SDS-PAGE, 30 kDa higher than expected from the combined molecular weights. Polyclonal antisera raised against the unique N-terminal portion of Tcf recognizes 90 kDa and 60 kDa bands in immunoblots of whole-cell lysates of strains of B. pertussis; it does not recognize any protein in whole-cell lysates of B. bronchiseptica or B. parapertussis. Supernatants of cultures of B. pertussis 18323 contain the 60 kDa form of the protein. Southern blot analysis of chromosomal DNA from strains of B. bronchiseptica and B. parapertussis, using a probe derived from tcfA, shows strong hybridization only to B. pertussis DNA. Thus, Tcf appears to be a unique virulence factor of B. pertussis.

Involvement of N-myristoylation in monoclonal antibody recognition sites on chimeric G protein alpha subunits

Monoclonal antibody, LAS-2, directed against the alpha subunit of transducin (Gt alpha), inhibited Gt beta gamma-dependent, pertussis toxin-catalyzed ADP ribosylation of Gt alpha and was specific for Gt alpha. Immunoblotting studies on proteolytic fragments of Gt alpha were consistent with an amino-terminal epitope. To define the antibody recognition site, recombinant Gt alpha was synthesized in Escherichia coli cotransfected with or without yeast N-myristoyl-transferase. Amino-terminal fatty acylation of Gt alpha, verified by use of radiolabeled fatty acid, was required for immunoreactivity. LAS-2 did not react with a chimeric protein consisting of residues 1-9 of Gt alpha and the remainder Go alpha, regardless of its myristoylation. Immunoreactivity was observed when amino acids 1-17 of Gt alpha were present in a Go alpha chimera and the protein was amino-terminally myristoylated; there was no reactivity without myristoylation. It appears that the LAS-2 epitope requires both Gt alpha-specific sequence in amino acids 10-17 and a fatty acyl group in proximity to these residues. These results are consistent with the hypothesis that the myristoyl group is essential for protein structure; conceivably it "folds back" on and stabilizes the amino-terminal structure of Gt alpha as opposed to protruding from an amino-terminal alpha-helix and serving as an amino-terminal membrane anchor.

Characterization of class II and class III ADP-ribosylation factor genes and proteins in Drosophila melanogaster

ADP-ribosylation factors (ARFs) are ubiquitous approximately 20-kDa guanine nucleotide-binding proteins that enhance the ADP-ribosyltransferase activity of cholera toxin and are involved in intracellular vesicular transport. Based on size, phylogenetic analysis, amino acid identity, and gene structure, mammalian ARFs fall into three classes (class I, ARF1, -2, and -3; class II, ARF4 and -5; class III, ARF6). A class I ARF had been identified in Drosophila melanogaster. To search for ARFs of other classes in Drosophila, polymerase chain reaction-based techniques were used, resulting in cloning of Drosophila ARF (dARF) II and dARF III with deduced amino acid sequences similar to those of class II and class III mammalian ARFs, respectively. The three Drosophila ARF genes map to different chromosomes and the coding regions have different splicing sites. dARF II mRNA, like ARF I mRNA, is fairly uniformly distributed throughout adult flies, whereas dARF III mRNA is significantly more abundant in heads than in legs or bodies. Recombinant dARF II and dARF III have biochemical and immunological properties similar to those of human ARF5 (hARF5) and hARF6, respectively. These observations are consistent with the conclusion that the three classes of ARFs are present in non-mammalian as well as mammalian species.

Characterization of a glucose-repressible ADP-ribosylation factor 3 (ARF3) from Saccharomyces cerevisiae

ADP-ribosylation factors (ARFs) are highly conserved approximately 20-kDa guanine nucleotide-binding proteins that enhance the ADP-ribosyltransferase activity of cholera toxin, and are believed to participate in vesicular transport in both exocytic and endocytic pathways. Based on size, phylogenetic analysis, amino acid sequence, and gene structure, mammalian ARFs fall into three classes (class I, ARFs 1, 2, 3; class II, ARFs 4, 5; class III, ARF6). Two ARF genes (yARF1, yARF2) are known in Saccharomyces cerevisiae and believed to participate in vesicular trafficking in the Golgi system; the double deletion mutant is not viable. A third yeast ARF (yARF3) cDNA has been cloned by polymerase chain reaction-based procedures. It contains an open reading frame of 549 bases encoding a protein of 183 amino acids, with a deduced amino acid sequence more identical (60%) to that of the class III mammalian ARF than to those of the other two classes (52-56%). The yARF3 protein, however, reacted poorly with antibodies against any of the three classes of mammalian ARFs. In the presence of GTP, recombinant yARF3 protein stimulated cholera toxin-catalyzed auto-ADP-ribosylation. yARF3 gene transcription, similar to that of yARF2, was repressed by glucose. As yARF3 was not essential for cell viability and was not required for endoplasmic reticulum to Golgi protein transport, it may provide an opportunity to define an ARF function in another kind of vesicular trafficking.

Construction and characterization of recombinant Vibrio cholerae strains producing inactive cholera toxin analogs

The catalytic A subunit of cholera toxin (CT-A) is capable of ADP-ribosylating the guanine nucleotide-binding protein, which regulates cell adenylyl cyclase, leading to the life-threatening diarrhea of cholera. Amino acids involved in the enzymatic activity of CT-A have previously been identified. By means of site-directed mutagenesis, an analog of the CT-A subunit gene was created with codon substitutions for both Arg-7 and Glu-112, each of which has been shown to produce subunits lacking ADP-ribosyltransferase activity. The mutated gene fragment was exchanged for the wild-type copy in the previously cloned ctxAB operon from El Tor biotype, Ogawa serotype Vibrio cholerae strain 3083, which produces CT-2. Further, the zonula occludens toxin gene, zot, was inactivated by an insertional mutation to create the new plasmid construct pCT-2*. Additionally, a DNA fragment encoding the B subunit of CT-1 (CT produced by classical biotype, Inaba serotype V. cholerae strain 569B) was exchanged for the homologous part in pCT-2*, resulting in the creation of pCT-1*. These plasmid constructs were introduced into the CT-negative V. cholerae mutant strain JBK70 (E1 Tor biotype, Inaba serotype); CT-A-B+ derivatives CVD101 and CVD103 of classical biotype Ogawa and Inaba serotype strains 395 and 569B, respectively; El Tor biotype Inaba and Ogawa serotype strains C6706 and C7258, respectively, recently isolated in Peru; and O139 (synonym Bengal) strain SG25-1 from the current epidemic in India. Recombinant toxins (CT-1* and CT-2*), partially purified from culture supernatants of transformed JBK70, were shown to be inactive on mouse Y1 adrenal tumor cells and in an in vitro ADP-ribosyltransferase assay. CT-1* and CT-2* reacted with polyclonal and monoclonal antibodies against both A and B subunits of CT. The toxin analogs reacted with antibodies against CT-A and CT-B on cellulose acetate strips and in a GM1 enzyme-linked immunosorbent assay; they reacted appropriately with B-subunit epitype-specific monoclonal antibodies in checkerboard immunoblots, and they formed precipitin bands with GM1-ganglioside in Ouchterlony tests. However, the reactions of the modified proteins with anti-A-subunit monoclonal antibodies were weaker than the reactions with wild-type holotoxins. V, cholerae strains carrying ctxA*, with either ctxB-1 or ctxB-2, and inactivated zot genes were created by homologous recombination. The recombinant strains and the purified toxin analogs were inactive in the infant rabbit animal model.(ABSTRACT TRUNCATED AT 400 WORDS)

Blinded comparison of biopsy needles and automated devices in vitro: 2. Biopsy of medical renal disease

OBJECTIVE

The purpose of this study was to compare several of the commonly used manual biopsy needles with several of the new automated biopsy devices (biopsy guns) for biopsy of medical renal disease.

MATERIALS AND METHODS

Ten different biopsy needles or automated devices were each used to do two biopsies of 10 cadaveric kidneys. The specimens were reviewed in a blinded fashion by a pathologist using a previously published histopathologic scale.

RESULTS

Of the four conventional biopsy needles tested (16-gauge Jamshidi, 18-gauge Sure-Cut, 14-gauge Tru-Cut, and 14-gauge Vim Silverman), the Jamshidi needle obtained the greatest average number of glomeruli (5.64). Results similar to those obtained with the conventional needles were obtained with the 16- and 18-gauge Biopty and Ultra-Cut biopsy guns. The 18-gauge Autovac gun with either a 2- or 4-cm depth of biopsy suffered from a significant number of biopsies from which no tissue was obtained. The 14-gauge Biopty gun was clearly superior, leading in all graded categories including the average number of glomeruli (8.11) per biopsy.

CONCLUSION

The automated biopsy device, or biopsy gun, can provide more diagnostic specimens than can manual or conventional needles in biopsy for medical renal disease.

Blinded comparison of biopsy needles and automated devices in vitro: 1. Biopsy of diffuse hepatic disease

OBJECTIVE

The purpose of this study was to compare several of the commonly used needles with several of the new automated biopsy devices (biopsy guns) for biopsy of diffuse hepatic disease.

MATERIALS AND METHODS

Nine different biopsy needles or automated devices were each used to do three biopsies of 10 cadaveric livers. The specimens were reviewed in a blinded fashion by a pathologist who did not know which needle or device was used, and they were compared on the basis of a previously published histopathologic grading scale.

RESULTS

The three conventional biopsy needles (16-gauge Jamshidi, 18-gauge Sure-Cut, and 14-gauge Tru-Cut) obtained a large amount of tissue with an average of 4.1 intact portal triads per biopsy. The 18-gauge Biopty gun obtained equivalent results. The 18-gauge Autovac gun with a 2-cm biopsy depth did not obtain any tissue in 18.5% of attempts. The 14- and 16-gauge Biopty guns and the 18-gauge Autovac gun with a 4-cm biopsy depth performed best with respect to fragment size and number of intact portal triads.

CONCLUSION

Automated biopsy devices can provide more diagnostic specimens than can manual or conventional needles in biopsy for diffuse hepatic disease.

Molecular characterization of a conserved, guanine nucleotide-dependent ADP-ribosylation factor in Drosophila melanogaster

ADP-Ribosylation factors (ARFs) are ubiquitous approximately 20-kDa guanine nucleotide-binding proteins that stimulate cholera toxin-catalyzed ADP-ribosylation in vitro. Because the functional role(s) of ARF in mammalian systems is (are) elusive, we looked for ARF in Drosophila melanogaster, and report the partial purification and molecular cloning of an ARF from Drosophila. We cloned the Drosophila ARF 1 gene without library screening by a combination of 5 polymerase chain reactions (PCRs), yielding a 546-base open reading frame encoding 182 amino acids, which are > 93% identical to those of mammalian class I ARFs. This ARF gene maps to 79F3-6 in the proximal region of the left arm of Drosophila chromosome 3. The Drosophila ARF1 gene structure, including placement of introns, is highly conserved relative to mammalian class 1 ARF genes. A single ARF mRNA species of 1.8 kb was abundant in all Drosophila body segments. Recombinant Drosophila ARF 1 synthesized in Escherichia coli had biochemical and immunochemical activities similar to those of mammalian ARF. The similarities of sequence and biochemical properties between Drosophila and mammalian ARFs contrast with their differences from Drosophila arl (ARF-like protein), which does not stimulate cholera toxin-catalyzed ADP-ribosylation, and is only approximately 52-56% identical in amino acid sequence to mammalian ARFs.

Automated biopsy devices: a blinded evaluation

To evaluate 20 different automated biopsy devices with respect to the quality of tissue obtained for histopathologic analysis, a total of 1,470 18-gauge biopsy specimens were obtained from 10 fresh autopsy cases, including 30 liver, 20 kidney, 10 pancreas, and 10 psoas muscle biopsy specimens per device and per biopsy depth. There was no statistical difference in the performance of the long-throw Biopty, ASAP 18, 1.9-cm UltraCut, long-throw Monopty, and 2.5-cm ABS biopsy guns. All obtained a large amount of tissue with minimal fragmentation or crush artifact. Most of the short-throw biopsy guns (depth of biopsy < or = 1.1 cm) did not perform as well. Although the other guns performed adequately, less than optimal results were obtained with the Temno, Bio-Gun, Roth, Klear Kut, ABC, and Urocut biopsy guns. Most 18-gauge automated biopsy devices with a biopsy excursion of at least 2.0 cm provide a high-quality, diagnostically adequate specimen for histopathologic analysis.

Fluvoxamine does not interact with alcohol or potentiate alcohol-related impairment of cognitive function

OBJECTIVE

To assess whether fluvoxamine alters the pharmacokinetics of alcohol or potentiates alcohol-related impairment of cognitive function.

METHODS

The study design required partially "blinded" balanced crossover studies, each involving 12 healthy male volunteers who each received a 40 gm dose of intravenous or oral alcohol after single and multiple doses of 50 mg fluvoxamine. Main outcome measures for pharmacokinetics were venous blood alcohol and plasma fluvoxamine. Main outcome measures for pharmacodynamics were word recall, simple and choice reaction time, number vigilance, memory scanning, and word recognition.

RESULTS

The pharmacokinetics of intravenous alcohol were not affected by concomitant administration of fluvoxamine. Compared with placebo-alcohol, alcohol slightly increased the rate of fluvoxamine absorption, but the area under the plasma concentration-time curve from 0 to 12 hours at steady state was unchanged. As expected, alcohol significantly impaired cognitive function in volunteers. However, fluvoxamine did not potentiate the effects of alcohol and in some instances appeared to reverse the effects or reduce their duration. Fluvoxamine was well tolerated: only mild adverse effects were reported, and none of those required intervention.

CONCLUSION

Fluvoxamine does not interact significantly with alcohol or potentiate alcohol-related impairment of cognitive function.

Pertussis toxin-catalyzed ADP-ribosylation of G(o) alpha with mutations at the carboxyl terminus

The guanine nucleotide-binding protein G(o alpha) has been implicated in the regulation of Ca2+ channels in neural tissues. Covalent modification of G(o alpha) by pertussis toxin-catalyzed ADP-ribosylation of a cysteine (position 351) four amino acids from the carboxyl terminus decouples G(o alpha) from receptor. To define the structural requirements for ADP-ribosylation, preparations of recombinant G(o alpha) with mutations within the five amino acids at the carboxyl terminus were evaluated for their ability to serve as pertussis toxin substrates. As expected, the mutant in which cysteine 351 was replaced by glycine (C351G) was not a toxin substrate. Other inactive mutants were G352D and L353 delta/Y354 delta. Mutations that had no significant effect on toxin-catalyzed ADP-ribosylation included G350D, G350R, Y354 delta, and L353V/Y354 delta. Less active mutants were L353G/Y354 delta, L353A/Y354 delta, and L353G. ADP-ribosylation of the active mutants, like that of wild-type G(o alpha), was enhanced by the beta gamma subunits of bovine transducin. It appears that three of the four terminal amino acids critically influence pertussis toxin-catalyzed ADP-ribosylation of G(o alpha).

An AIDS educational program for third-year medical students

Medical student training now involves an increasing number of patients with HIV infection and AIDS. Thus far educational efforts to change attitudes and behaviors toward AIDS patients have not been successful. Education that only involves the presentation of information appears to be insufficient to alter fearful and prejudicial attitudes toward such patients. Using four different teaching modules (open discussion, role play, and two videotapes) we demonstrated a positive change in students' anticipation of how they would respond to a question or a statement from a non-AIDS patient or a patient with AIDS. There were significant changes in the students' response to AIDS patients on the Understanding, Probing, Focusing, and Judgmental scales of the Medical Helping Relationship Inventory. This initial work suggests that educators can have a positive effect on students' attitudes. Techniques that traverse the emotional barriers students erect to protect themselves from the painful feelings stimulated by working with AIDS appear to be useful.

Techniques for reversing the failure of empathy towards AIDS patients

Educating the general population and health care workers about the acquired immunodeficiency syndrome (AIDS) is of paramount importance. There is a need to address the many fears and anxieties concerning this dreaded illness. Experience has shown that simple information-giving alone does little to allay the panic in the general population and in hospital personnel. The paper offers a psychodynamic explanation of the origins of the irrational fear and anxieties around AIDS patients and why information alone does not help the anxieties hospital workers experience. We have suggested a training program using group process and videotape techniques which can address the underlying fears and concerns about AIDS patients. These sessions can help hospital staff to deliver more empathic care to this patient group.

Correlation of the clinical pharmacodynamics of loprazolam with serum concentration

Six healthy fasted volunteers each received oral doses of a placebo, 1 mg and 2 mg loprazolam with one week between treatments using a double-blind balanced crossover design. Serum samples were obtained at selected times after dosing for measurement of loprazolam using a combined high-performance liquid and gas chromatographic assay. Drug effect was also measured at the corresponding times using self-assessment scales and psychomotor tests. The serum levels of loprazolam followed a somewhat irregular shape with secondary and tertiary peaks possibly associated with food intake. The maximum serum levels of loprazolam following 1 mg and 2 mg doses of the drug (6.0 +/- 2.6 and 11.3 +/- 2.9 ng/ml, respectively) occurred at approximately one hour after dosing. Both the maximum serum levels and the area under the curve of loprazolam measured to six hours increased in direct proportion to dose. Statistically significant drug effects were seen after 2 mg loprazolam, although the subjects also appeared sedated after 1 mg doses. There appeared to be a good correlation between the logarithm of the serum concentration of loprazolam and effect which suggested that the hypnotic activity of the drug was not mediated via a long-lived metabolite. A threshold serum concentration associated with evident sedation was observed at approximately 3 ng/ml.

Intravenous and oral administration of molsidomine, a pharmacodynamic and pharmacokinetic study

In 12 healthy male volunteers, molsidomine 1, 2 and 4 mg i.v. increased resting heart rate and decreased systolic blood pressure, the latter still being affected after 8 hours. After single oral doses of 1 and 2 mg, systolic pressure tended to be reduced for 90 minutes and exercise heart rate tended to be increased. After oral treatment with 2 mg molsidomine three times daily for 1 week, the pharmacokinetic parameters and the effects on heart rate and blood pressure after the final dose were not different from those after the first dose. The terminal half-life was independent of dose and route of administration. Clearance and distribution volume were not dose-dependent. The bioavailability of a 2 mg oral dose of molsidomine was 44%. Inter-individual variation in heart rate, blood pressure and pharmacokinetics was observed.

The psychological impact of immediate breast reconstruction for women with early breast cancer

Twenty-five patients were evaluated, 13 who had immediate breast reconstruction and 12 who had delayed breast reconstruction for early breast cancer. Data were elicited about the psychological impact of the cancer, the mastectomy, and the reconstruction. Our results support the conclusion that immediate breast reconstruction is accompanied by a lower incidence of psychological morbidity postoperatively, and we recommend that immediate breast reconstruction be offered as an alternative to women with early breast cancer.

Comparative bioavailability of two furosemide formulations in humans

Twelve healthy male volunteers participated in a balanced crossover comparison of a brand-name and generic furosemide formulations. Each treatment was given as a single 40-mg tablet following an overnight fast. Furosemide concentrations in plasma and urine were determined up to 24 h after treatment; urine output and urinary sodium excretion were also measured. In comparison with the brand-name tablets, generic furosemide was significantly less bioavailable. Using a 95% confidence interval approach, generic furosemide gave up to 66% lower maximum furosemide plasma levels, up to 52% less area under the plasma level curve to infinite time, and up to 37% less urinary recovery of furosemide. Comparison of the effect of the two treatments was a less sensitive measurement of bioequivalence. Confidence intervals for differences in urinary output and sodium excretion over the period of maximum effect (0-4 h) were, however, asymmetrical, and pharmacodynamic differences between treatments were significant at the 10% level.

Single and repeated dose kinetics of the hypnotic agent loprazolam in healthy volunteers

The pharmacokinetics of loprazolam have been studied in eight healthy male volunteers after single and repeated 2 mg oral doses taken at night, for eight nights. The absorption and disposition of unchanged drug (HPLC-GC assay) and receptor active benzodiazepine-type materials (radioreceptor assay) were examined after the first and eighth dose. Maximum levels of approximately 10 ng ml-1 (range 3.6 to 15.5 ng ml-1) were reached within about 2.5 h after dosing. The post-peak levels declined in a single exponential fashion with an overall mean +/- SD half-life of 7.06 +/- 1.98 h and total areas under the curve ranging from 35.9 to 189.0 ng ml-1 h. There were no statistical differences between the values for the first and eighth doses. There was no evidence to suggest that significant accumulation of parent drug or receptor active benzodiazepine-type materials had occurred, and it is concluded that the kinetics of loprazolam would allow repeated daily doses of 2 mg.