Identification of a cellular cofactor required for infection by feline leukemia virus.

Retroviral infection involves continued genetic variation, leading to phenotypic and immunological selection for more fit virus variants in the host. For retroviruses that cause immunodeficiency, pathogenesis is linked to the emergence of T cell-tropic, cytopathic viruses. Here we show that an immunodeficiency-inducing, T cell-tropic feline leukemia virus (FeLV) has evolved such that it cannot infect cells unless both a classic multiple membrane-spanning receptor molecule (Pit1) and a second coreceptor or entry factor are present. This second receptor component, which we call FeLIX, was identified as an endogenously expressed protein that is similar to a portion of the FeLV envelope protein. This cellular protein can function either as a transmembrane protein or as a soluble component to facilitate infection.

Highly Magnetizable Crosslinked Chloromethylated Polystyrene-Based Nanocomposite Beads for Selective Molecular Separation of 4-Aminobenzoic Acid.

In this work, we describe the preparation and characterization of highly magnetizable chloromethylated polystyrene-based nanocomposite beads. For synthesis optimization, acid-resistant core-shelled maghemite (γ-Fe2O3) nanoparticles are coated with sodium oleate and directly incorporated into the organic medium during a suspension polymerization process. A crosslinking agent, ethylene glycol dimethacrylate, is used for copolymerization with 4-vinylbenzyl chloride to increase the resistance of the microbeads against leaching. X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and optical microscopy are used for bead characterization. The beads form a magnetic composite consisting of ∼500 nm-sized crosslinked polymeric microspheres, embedding ∼8 nm γ-Fe2O3 nanoparticles. This nanocomposite shows large room temperature magnetization (∼24 emu/g) due to the high content of maghemite (∼45 wt %) and resistance against leaching even in acidic media. Moreover, the presence of superficial chloromethyl groups is probed by Fourier transform infrared and X-ray photoelectron spectroscopy. The nanocomposite beads displaying chloromethyl groups can be used to selectively remove aminated compounds that are adsorbed on the beads, as is shown here for the molecular separation of 4-aminobenzoic acid from a mixture with benzoic acid. The high magnetization of the composite beads makes them suitable for in situ molecular separations in environmental and biological applications.

Human neutrophils employ the myeloperoxidase-hydrogen peroxide-chloride system to convert hydroxy-amino acids into glycolaldehyde, 2-hydroxypropanal, and acrolein. A mechanism for the generation of highly reactive alpha-hydroxy and alpha,beta-unsaturated aldehydes by phagocytes at sites of inflammation.

Reactive aldehydes derived from reducing sugars and lipid peroxidation play a critical role in the formation of advanced glycation end (AGE) products and oxidative tissue damage. We have recently proposed another mechanism for aldehyde generation at sites of inflammation that involves myeloperoxidase, a heme enzyme secreted by activated phagocytes. We now demonstrate that human neutrophils employ the myeloperoxidase-H202-chloride system to produce alpha-hydroxy and alpha,beta-unsaturated aldehydes from hydroxy-amino acids in high yield. Identities of the aldehydes were established using mass spectrometry and high performance liquid chromatography. Activated neutrophils converted L-serine to glycolaldehyde, an alpha-hydroxyaldehyde which mediates protein cross-linking and formation of Nepsilon-(carboxymethyl)lysine, an AGE product. L-Threonine was similarly oxidized to 2-hydroxypropanal and its dehydration product, acrolein, an extremely reactive alpha,beta-unsaturated aldehyde which alkylates proteins and nucleic acids. Aldehyde generation required neutrophil activation and a free hydroxy-amino acid; it was inhibited by catalase and heme poisons, implicating H202 and myeloperoxidase in the cellular reaction. Aldehyde production by purified myeloperoxidase required H202 and chloride, and was mimicked by reagent hypochlorous acid (HOCl) in the absence of enzyme, suggesting that the reaction pathway involves a chlorinated intermediate. Collectively, these results indicate that the myeloperoxidase-H202-chloride system of phagocytes converts free hydroxy-amino acids into highly reactive alpha-hydroxy and alpha,beta-unsaturated aldehydes. The generation of glycolaldehyde, 2-hydroxypropanal, and acrolein by activated phagocytes may thus play a role in AGE product formation and tissue damage at sites of inflammation.

The myeloperoxidase system of human phagocytes generates Nepsilon-(carboxymethyl)lysine on proteins: a mechanism for producing advanced glycation end products at sites of inflammation.

Reactive aldehydes derived from reducing sugars and peroxidation of lipids covalently modify proteins and may contribute to oxidative tissue damage. We recently described another mechanism for generating reactive aldehydes from free alpha-amino acids. The pathway begins with myeloperoxidase, a heme enzyme secreted by activated neutrophils. Conversion of alpha-amino acids to aldehydes requires hypochlorous acid (HOCl), formed from H2O2 and chloride by myeloperoxidase. When L-serine is the substrate, HOCl generates high yields of glycolaldehyde. We now demonstrate that a model protein, ribonuclease A (RNase A), exposed to free L-serine and HOCl exhibits the biochemical hallmarks of advanced glycation end (AGE) products -- browning, increased fluorescence, and cross-linking. Furthermore, Nepsilon-(carboxymethyl)lysine (CML), a chemically well-characterized AGE product, was generated on RNase A when it was exposed to reagent HOCl-serine, the myeloperoxidase-H2O2-chloride system plus L-serine, or activated human neutrophils plus L-serine. CML production by neutrophils was inhibited by the H2O2 scavenger catalase and the heme poison azide, implicating myeloperoxidase in the cell-mediated reaction. CML was also generated on RNase A by a myeloperoxidase-dependent pathway when neutrophils were activated in a mixture of amino acids. Under these conditions, we observed both L-serine-dependent and L-serine-independent pathways of CML formation. The in vivo production of glycolaldehyde and other reactive aldehydes by myeloperoxidase may thus play an important pathogenic role by generating AGE products and damaging tissues at sites of inflammation.

Increased atherosclerosis in myeloperoxidase-deficient mice.

Myeloperoxidase (MPO), a heme enzyme secreted by activated phagocytes, generates an array of oxidants proposed to play critical roles in host defense and local tissue damage. Both MPO and its reaction products are present in human atherosclerotic plaque, and it has been proposed that MPO oxidatively modifies targets in the artery wall. We have now generated MPO-deficient mice, and show here that neutrophils from homozygous mutants lack peroxidase and chlorination activity in vitro and fail to generate chlorotyrosine or to kill Candida albicans in vivo. To examine the potential role of MPO in atherosclerosis, we subjected LDL receptor-deficient mice to lethal irradiation, repopulated their marrow with MPO-deficient or wild-type cells, and provided them a high-fat, high-cholesterol diet for 14 weeks. White cell counts and plasma lipoprotein profiles were similar between the two groups at sacrifice. Cross-sectional analysis of the aorta indicated that lesions in MPO-deficient mice were about 50% larger than controls. Similar results were obtained in a genetic cross with LDL receptor-deficient mice. In contrast to advanced human atherosclerotic lesions, the chlorotyrosine content of aortic lesions from wild-type as well as MPO-deficient mice was essentially undetectable. These data suggest an unexpected, protective role for MPO-generated reactive intermediates in murine atherosclerosis. They also identify an important distinction between murine and human atherosclerosis with regard to the potential involvement of MPO in protein oxidation.

Ductal lavage for detection of cellular atypia in women at high risk for breast cancer.

BACKGROUND: Breast cancer originates in breast epithelium and is associated with progressive molecular and morphologic changes. Women with atypical breast ductal epithelial cells have an increased relative risk of breast cancer. In this study, ductal lavage, a new procedure for collecting ductal cells with a microcatheter, was compared with nipple aspiration with regard to safety, tolerability, and the ability to detect abnormal breast epithelial cells. METHODS: Women at high risk for breast cancer who had nonsuspicious mammograms and clinical breast examinations underwent nipple aspiration followed by lavage of fluid-yielding ducts. All statistical tests were two-sided. RESULTS: The 507 women enrolled included 291 (57%) with a history of breast cancer and 199 (39%) with a 5-year Gail risk for breast cancer of 1.7% or more. Nipple aspirate fluid (NAF) samples were evaluated cytologically for 417 women, and ductal lavage samples were evaluated for 383 women. Adequate samples for diagnosis were collected from 111 (27%) and 299 (78%) women, respectively. A median of 13,500 epithelial cells per duct (range, 43-492,000 cells) was collected by ductal lavage compared with a median of 120 epithelial cells per breast (range, 10-74,300) collected by nipple aspiration. For ductal lavage, 92 (24%) subjects had abnormal cells that were mildly (17%) or markedly (6%) atypical or malignant (<1%). For NAF, corresponding percentages were 6%, 3%, and fewer than 1%. Ductal lavage detected abnormal intraductal breast cells 3.2 times more often than nipple aspiration (79 versus 25 breasts; McNemar's test, P<.001). No serious procedure-related adverse events were reported. CONCLUSIONS: Large numbers of ductal cells can be collected by ductal lavage to detect atypical cellular changes within the breast. Ductal lavage is a safe and well-tolerated procedure and is a more sensitive method of detecting cellular atypia than nipple aspiration.

Proton NMR lipid profile of Leishmania donovani promastigotes.

The proton nuclear magnetic resonance (NMR) lipid profile of Leishmania donovani was obtained in the one-dimensional and two-dimensional modes. Partial assignments of lipid classes and individual lipids were obtained purely from the proton NMR spectrum of the mixture. A more complete assignment and quantitative analysis was achieved by prior separation of the lipids by high pressure liquid chromatography (HPLC) followed by proton NMR analysis of the fractions. This work showed that proton NMR spectroscopy could facilitate lipid analysis and classification of various parasitic protozoa and serve as a basis for rapid studies of comparative lipid metabolism in parasites.

Ki-1 anaplastic large cell lymphoma with a prominent leukemic phase.

Patients with Ki-1 (CD30)-positive anaplastic large cell lymphoma (ALCL) occasionally have rare circulating lymphoma cells. We report a case of ALCL with a prominent leukemic phase. A 36-year-old man presented with widespread ALCL involving lymph nodes, spleen, pleural fluid, cerebrospinal fluid, and bone marrow. His white blood cell count was 106,000/mm3 with 20% lymphoma cells. The circulating neoplastic cells were large, and had irregular nuclei with multiple small nucleoli, ample cytoplasm, and multiple clear cytoplasmic vacuoles. This case illustrates that ALCL may have a marked leukemic phase composed of large anaplastic cells.

Leukemic phase of mantle cell lymphoma, blastoid variant.

Six patients with mantle cell lymphoma, blastoid variant, involving the blood are described. The circulating blast-like cells suggested the possibility of acute leukemias, chronic lymphoproliferative disorders or peripheralized lymphomas. The WBC counts ranged from 3,700 to 249,000/microL (3.7-249.0 x 10(9)/L) and the absolute lymphocyte counts from 1,000 to more than 200,000/microL (1.0 to > 200.0 x 10(9)/L). The peripheral blood smears showed a spectrum of cells, from small mature lymphocytes with irregular nuclei to medium-sized lymphocytes with blast-like chromatin. However, the morphologic features in a lymph node biopsy specimen and the immunophenotype confirmed a diagnosis of mantle cell lymphoma, blastoid variant. By flow cytometry the lymphoma cells expressed B-cell-associated antigens (CD19, CD20 and CD22), coexpressed CD5, lacked CD23, and expressed moderate intensity monoclonal surface immunoglobulin and CD20. Cytogenetic analysis showed the characteristic t(11;14) in 2 of 4 analyzed specimens. Mantle cell lymphoma, blastoid variant, is part of the differential diagnosis for blast-like cells.

Overweight and obesity in native-American adolescents: comparing nonreservation youths with African-American and Caucasian peers.

Previous studies have consistently shown that, compared to national standards, Native Americans across all age groups are disproportionately overweight or obese. Although most available data on rates of obesity in this group come from studies conducted on reservations, the proportion of Native Americans residing on reservation lands is rapidly declining. This study examines the prevalence of overweight and obesity in a population of Midwestern adolescents in public school settings and contrasts Caucasian and African-American adolescents with Native-American youths of the same age. Data were derived from a secondary analysis of an anonymous health-risk survey. Height, weight, and ethnicity were ascertained through self-report. The results call into question whether rates of overweight or obesity in Native-American adolescents are disproportionate relative to those for Caucasian and African-American adolescents. Cumulative comparisons of all overweight and obese adolescents in the sample (n = 5,655) show significant differences among ethnic groups, but age-specific comparisons do not yield a consistent pattern, especially for Native-American girls. To compare the entire sample to national weight standards, we plotted mean body mass index (BMI) for each ethnic group by age against NHANES II reference data. Age-specific BMI means for Native-American and Caucasian girls fell largely below the NHANES II reference data. We present several explanations for these results. Given the study limitations, further objective study of the weight status of Native-American children and adolescents in direct comparison with other ethnic groups is recommended.

Frequency of ultraviolet radiation-induced mutation at the hprt locus in repair-proficient murine fibroblasts transfected with the denV gene of bacteriophage T4.

The frequency of spontaneous and ultraviolet radiation (UVR)-induced mutation at the hprt locus was determined in control and denV-transfected, repair-proficient murine fibroblasts. Control cells removed an average of 25% of pyrimidine dimers induced by exposure to 150 J/m2 UVR from an FS40 sunlamp within 24 h; under the same conditions of induction and repair, denV-transfected cells removed an average of 71% of pyrimidine dimers. Control cells were somewhat more resistant than denV-transfected cells to killing by UVR. The average frequency of spontaneous mutation at the hprt locus for control and denV-transfected cells was 3 and 15 6-thioguanine (6-TG)-resistant colonies per 10(6) surviving cells, respectively; there was no statistically significant difference between control and denV-transfected cells. However, after exposure to 75 or 150 J/m2 UVR, denV-transfected cells had a significantly lower frequency of mutation to 6-TG resistance. After exposure to a fluence of 75 J/m2, the average frequency of UVR-induced mutation at the hprt locus was 166 mutant colonies per 10(6) surviving cells for control cells and 92 mutant colonies for denV-transfected cells; after 150 J/m2, control cells had 205 6-TG-resistant colonies per 10(6) cells, while denV-transfected cells had 61 mutant colonies. These results demonstrate that UVR-induced pyrimidine dimers are mutagenic photoproducts in mammalian cells.

Physician utilization of computers in medical practice: policy implications based on a structural model.

The development of policies regarding computer-based medical technology is hampered by a lack of knowledge about the process by which such applications are adopted and utilized by physicians. This study was designed to test a model of the process by which physicians change their practice behavior by utilizing a computer-based hospital information system (HIS). A structural model was developed, estimated, and tested using data from 270 members of the medical staff of a 1160 bed, private teaching hospital. The overall model consists of a measurement model which assumes that the observed variables are generated by a smaller number of unobserved variables or factors; and a structural equation model that relates exogenous and endogenous variables. The model indicates that consultation with other physicians on a hospital service leads to greater exposure to potential computer applications resulting in less concern about the potential impact of computers on medical practice. Physicians who are more knowledgeable about computers are far more likely to tailor the system to their individual practice by developing their own personal order sets for use on the HIS. All of these factors result in increased use of the HIS by physicians. A number of policy implications related to the introduction of new computer-based technology into medical practice settings are discussed.

Positive smoking history as a preliminary screening device for substance use in pregnant adolescents.

STUDY OBJECTIVE: To assess the utility of a history of smoking as a clinical indicator of substance use in pregnant adolescents. DESIGN: A secondary analysis of a subsample of all 15- to 19-year-old live-birth mothers (N = 1640) taken from the 1988 National Maternal and Infant Health Survey (NMIHS). Self-reported data were weighted and analyzed covering ethnicity, substance use, socioeconomic status, and prenatal care. Contingency table analysis and stepwise logistic regression were applied to compare the prevalence of other forms of substance use among smokers versus nonsmokers, and to evaluate whether a history of smoking made a unique contribution to identifying adolescents at increased risk for use of other substances. The specific substances studied were alcohol and cocaine which are known to be important contributors to perinatal morbidity and mortality. RESULTS: In this multiethnic, nationally representative subsample of pregnant adolescents, 35% reported a positive history of tobacco use 12 months before delivery. Another 32% had consumed alcohol, 9% had used marijuana, and about 1.5% had reported some use of cocaine or crack. The findings show greater use of tobacco by whites, non-Hispanics, the ever married, and women receiving prenatal care in the private sector. Fifty-three percent of all admitted users of alcohol or cocaine smoked cigarettes 12 months before delivery. Logistic regression shows that smokers were four times more likely to use alcohol or cocaine than nonsmokers when controlling for other sociodemographic and economic variables. CONCLUSION: Substance use is common in pregnant adolescents from all ethnic and economic backgrounds. Self-report of smoking may be useful in screening for adolescents at risk for using cocaine or alcohol during pregnancy.

Why doctors don't use computers: some empirical findings.

The attitudes of 148 medical students, 141 residents, and 644 practising physicians towards computer applications in medicine were studied. The results indicate that physicians recognize the potential of computers to improve patient care, but are concerned about the possibility of increased governmental and hospital control, threats to privacy, and legal and ethical problems. In general, all three groups are uncertain as to the potential effects of computers on their traditional professional role and on the organization of practice. Practising physicians, however, express more concern about these potential effects of computers than do medical students and residents. While attitudes appear to be somewhat independent of prior computer experience, they significantly affect the extent to which physicians use a computer-based hospital information system. This may be a major reason for the slow introduction of clinical computer systems.

HIV and adolescents.

Human immunodeficiency virus has entered the adolescent population, and pediatricians will be caring for youngsters who are HIV positive or at risk of being infected. We should remember that it is risky sexual behavior and injection drug use that places a teen at risk for HIV infection, not their sexual orientation, ethnicity, or gender. Parents and their teenagers desire and expect their pediatricians to provide care and guidance for the diseases and problems that adolescents face. A screening psychosocial assessment of teenagers can identify those who need more in-depth counseling. Although the subjects of sex and drug use initially may be uncomfortable for a physician, practice using the HEADSS assessment will rapidly lead to comfort in discussing these important subjects. An understanding of HIV testing and pre- and post-test counseling will prepare the physician for the inevitable patient who wishes testing or who is HIV positive. Much of the treatment of HIV-positive adolescents involves patience and support while the adolescent grapples with the serious implications of being HIV positive. The initial history and physical exam establishes baselines regarding previous infections and illnesses that may bear on HIV infection, as well as determining which symptoms and signs of HIV infection are present. The initial laboratory tests further define the patient's current clinical state and will determine what therapies are immediately needed. Human immunodeficiency virus continues to evolve toward a manageable chronic illness that responds most favorably to early intervention.

Abnormal vaginal bleeding in adolescents.

The evaluation and management of abnormal vaginal bleeding should be tailored to the individual case. Pediatricians caring for adolescents need to be skilled in the evaluation and management of this common adolescent problem. Physicians who do not feel comfortable with their skills in the performance of a pelvic exam should obtain consultation from an adolescent specialist or a gynecologist who has experience with adolescents.

[Metoprolol prevents myocardial ischemia during endoscopic retrograde cholangiopancreatography]. / Metoprolol forebygger myokardieiskaemi under endoskopisk retrograd kolangiopankreatikografi.

The aim of our study was to evaluate the effect of metoprolol on the occurrence of myocardial ischaemia during endoscopic cholangiopancreatography. Thirty-eight (2 x 19) patients scheduled for endoscopic cholangiopancreatography received either metoprolol 100 mg or placebo two hours before endoscopy. During endoscopy, arterial oxygen saturation was measured by continuous pulse oximetry, and the electrocardiogram was monitored continuously with a Holter tape recorder. Myocardial ischaemia was defined as an ST segment deviation > 1 mV from baseline. Heart rate during endoscopy was significantly lower in the metoprolol group compared with the placebo group (p = 0.0002). Twenty-one patients (16 placebo versus five metoprolol, p = 0.0008) developed tachycardia (heart rate > 100/min) during the procedure. A total of eleven patients (ten placebo versus one metoprolol, p = 0.003) developed myocardial ischaemia during the procedure, and myocardial ischaemia was always related to increases in heart rate. In conclusion, metoprolol prevented myocardial ischaemia during endoscopic cholangiopancreatography, probably through a heart rate lowering effect. Thus, tachycardia seems to be a key pathogenic factor in the development of myocardial ischaemia during endoscopy.

Telephone advice: new solutions for old problems.

This article describes the increasing use of the telephone as a means for seeking medical care. The literature is reviewed concerning the problems and pitfalls of telephone advice. The legal/ethical implications of health care providers giving telephone advice are discussed. Recommendations for the assessment of need, planning, implementation, and organization of a consistent telephone advice program are stressed. The development of a quality assurance program to maintain the quality of the advice program is presented. Suggestions for training of personnel and the importance of documentation of calls are included.

Fabrication of glycine-functionalized maghemite nanoparticles for magnetic removal of copper from wastewater.

Maghemite nanoparticles (MNPs) were functionalized with glycine, by a cost-effective and environmentally friendly procedure, as an alternative route to typical amine-functionalized polymeric coatings, for highly efficient removal of copper ions from water. MNPs were synthesized by co-precipitation method and adsorption of glycine was investigated as a function of ligand concentration and pH. The efficiency of these functionalized nanoparticles for removal of Cu(2+) from water has been explored and showed that adsorption is highly dependent of pH and that it occurs either by forming chelate complexes and/or by electrostatic interaction. The adsorption process, which reaches equilibrium in few minutes and fits a pseudo second-order model, follows the Langmuir adsorption model with a very high maximum adsorption capacity for Cu(2+) of 625mg/g. Furthermore, these nanoadsorbents can be used as highly efficient separable and reusable materials for removal of toxic metal ions.

Magnetic ionic liquids produced by the dispersion of magnetic nanoparticles in 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf2).

̀This paper reports on the advancement of magnetic ionic liquids (MILs) as stable dispersions of surface-modified γ-Fe(2)O(3), Fe(3)O(4), and CoFe(2)O(4) magnetic nanoparticles (MNPs) in a hydrophobic ionic liquid, 1-n-butyl 3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMI.NTf(2)). The MNPs were obtained via coprecipitation and were characterized using powder X-ray diffraction, transmission electron microscopy, Raman spectroscopy and Fourier transform near-infrared (FT-NIR) spectroscopy, and magnetic measurements. The surface-modified MNPs (SM-MNPs) were obtained via the silanization of the MNPs with the aid of 1-butyl-3-[3-(trimethoxysilyl)propyl]imidazolium chloride (BMSPI.Cl). The SM-MNPs were characterized by Raman spectroscopy and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy and by magnetic measurements. The FTIR-ATR spectra of the SM-MNPs exhibited characteristic absorptions of the imidazolium and those of the Fe-O-Si-C moieties, confirming the presence of BMSPI.Cl on the MNP surface. Thermogravimetric analysis (TGA) showed that the SM-MNPs were modified by at least one BMSPI.Cl monolayer. The MILs were characterized using Raman spectroscopy, differential scanning calorimetry (DSC), and magnetic measurements. The Raman and DSC results indicated an interaction between the SM-MNPs and the IL. This interaction promotes the formation of a supramolecular structure close to the MNP surface that mimics the IL structure and is responsible for the stability of the MIL. Magnetic measurements of the MILs indicated no hysteresis. Superparamagnetic behavior and a saturation magnetization of ~22 emu/g could be inferred from the magnetic measurements of a sample containing 50% w/w γ-Fe(2)O(3) SM-MNP/BMI.NTf(2).