Filamentous proteophosphoglycan secreted by Leishmania promastigotes forms gel-like three-dimensional networks that obstruct the digestive tract of infected sandfly vectors

Development of Leishmania parasites in the digestive tract of their sandfly vectors involves several morphological transformations from the intracellular mammalian amastigote via a succession of free and gut wall-attached promastigote stages to the infective metacyclic promastigotes. At the foregut midgut transition of Leishmania-infected sandflies a gel-like plug of unknown origin and composition is formed, which contains high numbers of parasites, that occludes the gut lumen and which may be responsible for the often observed inability of infected sandflies to draw blood. This "blocked fly" phenotype has been linked to efficient transmission of infectious metacyclic promastigotes from the vector to the mammalian host. We show by immunofluorescence and immunoelectron microscopy on two Leishmania/sandfly vector combinations (Leishmania mexicana/Lutzomyia longipalpis and L. major/Phlebotomus papatasi) that the gel-like mass is formed mainly by a parasite-derived mucin-like filamentous proteophosphoglycan (fPPG) whereas the Leishmania polymeric secreted acid phosphatase (SAP) is not a major component of this plug. fPPG forms a dense three-dimensional network of filaments which engulf the promastigote cell bodies in a gel-like mass. We propose that the continuous secretion of fPPG by promastigotes in the sandfly gut, that causes plug formation, is an important factor for the efficient transmission to the mammalian host.

Lipophilic 4-isoxazolyl-1,4-dihydropyridines: synthesis and structure-activity relationships

A series of 4-isoxazolyl-1,4-dihydropyridines bearing lipophilic side chains at the C-5 position of the isoxazole ring have been prepared. The calcium channel antagonistic activity of these compounds has been evaluated. A hypothetical model for binding of these compounds in the calcium channel is proposed, and the validity of this model is evaluated based on the SAR of this series of calcium binding, especially for the two most active derivatives, 1a, g. The solid-state structure for the most active compound, 1a, has also been determined, and its important features are reported.

An olfactory-specific glutathione-S-transferase in the sphinx moth Manduca sexta

Insect antennae have a primary function of detecting odors including sex pheromones and plant volatiles. The assumption that genes uniquely expressed in these antennae have an olfactory role has led to the identification of several genes that are integral components of odorant transduction. In the present study, differential display polymerase chain reaction (ddPCR) was used to isolate 25 antennal-specific mRNAs from the male sphinx moth Manduca sexta. Northern blot analyses revealed that one clone, designated G7-9, was antennal-specific and was highly enriched in male antennae relative to female antennae. In situ hybridization indicated that G7-9 expression was restricted to a spatial domain of the olfactory epithelium occupied exclusively by sex-pheromone-sensitive olfactory sensilla. Amino acid homology and phylogenetic analyses identified G7-9 as a glutathione-S-transferase (GST); we have named the full-length clone GST-msolf1. GSTs are known to function primarily in the detoxification of noxious compounds. Spectrophotometric and chromatographic analyses of total GST activity indicate that the endogenous GSTs of male and female antennae can modify trans-2-hexenal, a plant-derived green leaf aldehyde known to stimulate the olfactory system of M. sexta. The restricted localization of GST-msolf1 to sex-pheromone-sensitive sensilla, the fact that the sex pheromone of M. sexta consists of a complex mixture of aldehyde components, and the observation that antennal GSTs can modify an aldehyde odorant suggest that GST-msolf1 may have a role in signal termination. In the light of the more commonly observed role of GSTs in xenobiotic metabolism, we propose that GST-msolf1 may play a dual role of protecting the olfactory system from harmful xenobiotics and inactivating aldehyde odorants, especially components of the M. sexta sex pheromone.

Infection of lepidoptera with a pseudotyped retroviral vector

Studies requiring the introduction and expression of manipulated gene constructs have been technically difficult in non-drosophilid insects. Retroviruses can be engineered to be replication defective and to serve as vectors for gene constructs of interest. In this study, pseudotyped MoMLV(VSV-G) retroviral vectors are shown to successfully infect lepidopteran cells in vitro and in vivo. In Spodoptera frugiperda cells in vitro and in Manduca sexta in vivo, infection and conversion to proviral DNA were confirmed by PCR amplification and Southern blot hybridization of vector-specific sequences. Gene expression and integration of proviral DNA were also documented in vitro. This is the first report of retroviral infection in lepidoptera and suggests that pseudotyped retroviral vectors could be powerful tools in gene manipulation studies of non-drosophilid insects.

A monoclonal antibody to a multiphosphorylated, conformational epitope at the carboxy-terminus of p53

Mutations of the gene encoding the tumor suppressor protein p53 are the most common molecular alterations of cancer cells found in about half of all human tumors. Mutations which cluster in well-defined hot spots change the structure of the protein thus affecting its ability to bind to DNA. Post-translational modifications, primarily phosphorylation, might also influence how p53 binds to DNA or folds to its active tetrameric form. However, the lack of appropriate biochemical markers to characterize the status of phosphorylation in different cell types and in cells at different stages of tumor progression has prohibited such investigations. To generate a sensitive and phosphorylation-specific monoclonal antibody (mAb), we chemically synthesized the C-terminal 23 amino acid stretch of human p53 in a double-phosphorylated form. The peptide 371-393, carrying phosphate groups on Ser378 and Ser392, was co-synthesized with a turn-inducing spacer and peptide 31D, an immunodominant T-helper cell epitope in mice of the H-2k haplotype. After immunization and fusion of splenocytes with myeloma cells, a number of mAbs were obtained, from which mAb p53-18 emerged as a highly sensitive reagent. By enzyme-linked immunosorbent assay, p53-18, a mAb of the IgM isotype, recognized phosphorylated p53, expressed in insect cells infected with a recombinant baculovirus but not p53 expressed in Escherichia coli. Moreover, murine p53 from insect cells could be immune purified with mAb p53-18. Mass spectrometry following tryptic digestion of the purified protein and liquid chromatography of the fragments verified the presence of phosphate groups at both Ser375 and Ser389. From the corresponding human protein fragments, mAb p53-18 bound to the immunizing peptide phosphorylated on Ser378 and on Ser392, but failed to cross-react with the unphosphorylated peptide, or peptides phosphorylated individually on either Ser378 or Ser392. The binding to the unphosphorylated peptide could be restored, however, if the peptide conformation was stabilized to that of an alpha-helix. The immunogenic nature of the multiphosphorylated C-terminus of p53 is indicated by the finding that human sera, mostly from cancer patients, preferentially recognized the double-phosphorylated peptide over the monophosphorylated or unphosphorylated analogs. Antibody p53-18 appears to be a highly useful biochemical marker to detect low levels of p53 protein in different tissues, and to be a key tool to characterize the phosphorylation status of the C-terminus of p53 protein originated from various sources.

Snmp-1, a novel membrane protein of olfactory neurons of the silk moth Antheraea polyphemus with homology to the CD36 family of membrane proteins

While olfactory neurons of silk moths are well known for their exquisite sensitivity to sex pheromone odorants, molecular mechanisms underlying this sensitivity are poorly understood. In searching for proteins that might support olfactory mechanisms, we characterized the protein profile of olfactory neuron receptor membranes of the wild silk moth Antheraea polyphemus. We have purified and cloned a prominent 67-kDa protein which we have named Snmp-1 (sensory neuron membrane protein-1). Northern blot analysis suggests that Snmp-1 is uniquely expressed in antennal tissue; in situ hybridization and immunocytochemical analyses show that Snmp-1 is expressed in olfactory neurons and that the protein is localized to the cilia, dendrites, and somata but not the axons. Snmp-1 mRNA expression increases significantly 1-2 days before the end of adult development, coincident with the functional maturation of the olfactory system. Sequence analysis suggests Snmp-1 is homologous with the CD36 protein family, a phylogenetically diverse family of receptor-like membrane proteins. CD36 family proteins are characterized as having two transmembrane domains and interacting with proteinaceous ligands; Snmp-1 is the first member of this family identified in nervous tissue. These findings argue that Snmp-1 has an important role in olfaction; possible roles of Snmp-1 in odorant detection are discussed.

Peptide biotinylation with amine-reactive esters: differential side chain reactivity

N-hydroxysuccinimide (NHS) esters of biotin are reported to react specifically with amino groups of peptides and proteins. However, we have found that these reagents can readily acylate other functional groups in specific peptide sequences under relatively mild conditions. We have extended our inquiry of sequence-dependent acylation by evaluating the reactivity of a variety of commonly employed biotinylation reagents typically used for amino group modification. These included the p-nitrophenyl ester of biotin, NHS-esters of biotin containing aminohexanoic acid spacer arms, and a sulfonated NHS-biotin ester that contained a disulfide bond within its spacer. The decapeptide [D-Lys6]gonadotropin releasing hormone was employed as a model peptide. Reaction products were characterized by high-performance liquid chromatography, amino acid compositional analysis, reaction with hydroxylamine, and mass spectrometry. In addition to the O-acylation of Ser4 and Tyr5 in this peptide, we have also identified a novel biotinylation of the Arg8 side chain.

Melanin granule model for laser-induced thermal damage in the retina

An analytical model for thermal damage of retinal tissue due to absorption of laser energy by finite-sized melanin granules is developed. Since melanin is the primary absorber of visible and near-IR light in the skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are modeled as absorbing spheres surrounded by an infinite medium of water. Analytical solutions to the heat equation result in computations that are quick and accurate. Moreover, the model does not rely on symmetric beam profiles, and so arbitrary images can be studied. The important contribution of this model is to provide a more accurate biological description of sub-millisecond pulse exposures than previous retinal models, while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vaporization as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.

Ontogeny of odorant receptor gene expression in zebrafish, Danio rerio

We cloned three putative odorant receptor (OR) genes from the zebrafish to use as in situ hybridization probes to follow the temporal patterns of neurons expressing OR genes through a developmental progression from embryo (12 h postfertilization) to adult. The identification of these genes is supported by sequence homology to previously reported ORs and by the morphology and location of labeled cells in in situ hybridization experiments. Cells expressing OR mRNA were first observed in the olfactory placodes between 31 and 38 h after fertilization (fish reared at 26 degrees C). Initially, only single cells were observed to hybridize the probe; the number of labeled cells increased throughout the remainder of embryogenesis and through postembryonic growth and morphogenesis of the olfactory organ. At all ages, the positively hybridizing cells were scattered throughout the olfactory epithelium but not in the nonsensory epithelium of the olfactory organ.

Identifying suitable grass species for saline areas

The salt tolerance of 20 lines of perennial grasses, including both native Australian and introduced species, was evaluated in 3 separate experiments over 0-180 mol Na Cl/m3 in the greenhouse, with the aim of identifying material that may be grown productively in saline areas in Australia, particularly the Murray- Darling Basin. Lolium perenne cv. Victorian, a species that is recognised as having a moderate level of salt tolerance, was included in all experiments as a reference species. In relative terms (as defined by the rate of the decline in dry matter production under saline conditions), only 5 species or cultivars (Psathyrostachys juncea cvv. Mankota, Tetracan and Vinall, Pascopyrum smithii cv. Walsh and Thinopyrum elongatum cv. Tyrell) were more salt tolerant than L. perenne cv. Victorian. However, several species including the native species Enteropogon acicularis and Themeda triandra, and the introduced species Eragrostis curvula cv. Consol and Thinopyrum elongatum, produced more dry matter than L. perenne over NaCl concentrations ranging from 0 to 180 mol/m3. The salt tolerance of Danthonia richardsonii was very similar to that of L. perenne. It was concluded that Psathyrostachys juncea, Pascopyrum smithii, Enteropogon acicularis and D. richardsonii, may offer potential as salt-tolerant germplasm, however, further field studies are recommended in order to fully assess the response of this material to saline soil conditions.

Laser induced bubble formation in the retina

BACKGROUND AND OBJECTIVE

The immediate thermodynamic effects of absorption of a laser pulse in the retina are theoretically studied to understand underlying physical damage mechanisms at threshold fluences. Damage is most likely to occur at threshold levels in the retinal pigment epithelium due to the strong absorption by the melanosomes.

METHODS

The retinal pigment epithelium is modeled as an aqueous environment with absorption occurring at small spherical sites with absorption coefficients representative of melanosomes. For laser pulse durations of less than 10(-6) seconds, heat conduction is negligible during energy deposition and the resulting large energy density in the melanosomes will cause vaporization of the medium immediately surrounding a melanosome.

RESULTS

We developed expressions for calculating the size of bubbles produced as a function of pulse characteristics and melanosome properties. We show that for pulse durations between 10(-6) and 10(-9) seconds, bubble formation will occur for laser fluences that are smaller than those required to cause Arrhenius-type thermal damage.

CONCLUSION

Bubble formation is likely to be the mechanism of threshold damage to the retina for laser pulses durations in the time regime between 10(-6) and 10(-9) seconds.

Interdialytic weight gain and nutritional parameters in chronic hemodialysis patients

The extent of interdialytic weight gain (IDWG) in chronic hemodialysis patients is usually attributed to the level of compliance with fluid restriction. However, in view of the substantial water content of food (and caloric content of beverages), IDWG also may be a function of calorie and protein intake and may reflect the nutritional state of patients. To investigate this theory, the relationship between 2-day IDWG and body weight, normalized protein catabolic rate (nPCR), serum albumin, and delivered Kt/V urea was assessed in a prospective, randomized study of 860 chronic hemodialysis patients in 56 dialysis units. Compared with patients having < 2 kg IDWG (n = 378), patients with > 3 kg IDWG (n = 138) weighed more (dry weight, 76.8 v 61.7 kg), had higher nPCR (1.15 v 0.96 g/kg/d), and had higher serum albumin levels (3.96 vs 3.79 g/dL) (all P < 0.001) but did not have different levels of Kt/V (1.04 v 1.06). When IDWG was assessed as a function of dry weight, patients with IDWG > 4.5% of dry weight (n = 151) had higher nPCR (1.17 v 0.94 g/kg/d) but weighed less (60.1 v 70.0 kg) and had a higher Kt/V (1.14 v 1.01) than patients with IDWG < 3% of dry weight (n = 355) (all P < 0.001). Artifactual association between IDWG and nPCR attributable to an accentuated two-pool effect from differing ultrafiltration requirements was unlikely as assessed by the relationship between modeled Kt/V and prescribed Kt/V determined using an anthropometric urea volume.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dialyzer reuse on dialysis delivery

It is well documented that the reprocessing of dialyzers may reduce their solute clearance capabilities. However, the effect of dialyzer reuse has never been assessed in an uncontrolled clinical practice setting. We addressed this issue in a prospective 436-patient, 34-center study. All patients underwent formal urea kinetic modeling monthly, usually for 3 sequential months. Dialyzers were reprocessed and reused in the usual manner for each unit. As a result, urea kinetic modeling was performed in individual patients using dialyzers with differing numbers of prior uses. For each patient, Kt/V urea for the treatment using the dialyzer with the most reuses (mean, 13.8) was compared with that with the treatment using the dialyzer with the fewest reuses (mean, 3.8). The mean Kt/V delivered for high reuse treatments was significantly lower than that for low reuse treatments (1.05 v 1.10, P = 0.002). Prescribed Kt/V in high and low reuse treatments was identical. Individual centers appeared to differ substantially (P = 0.06) in the effect of reuse on delivered Kt/V. Of the 23 centers using formalin-based reprocessing, an average difference of > or = 0.12 (mean, 0.17) in Kt/V between high and low reuse treatments was seen in 10 centers. Dialyzer reprocessing significantly impairs dialysis delivery, an effect that may be related to the methods and procedures in individual dialysis centers.

Deficiencies in delivered hemodialysis therapy due to missed and shortened treatments

The frequency of missed and shortened hemodialysis treatments was assessed in a randomly selected sample of 860 ESRD patients from 54 dialysis units. Data were collected for three sequential 4-week periods covering 28,108 treatments. During each of these 4-week periods, 5.1% to 7.6% of patients missed at least one treatment, 26.8% to 32.3% of patients had at least one shortened treatment, and 6.6% to 7.9% of patients missed 10% or more of their prescribed therapy. Over the entire 12-week period, 50% of patients had either missed or shortened treatments (or both). Missed and shortened treatments are prevalent enough to account for clinically important deficiencies in delivered dialysis for a significant number of patients.

Identification and characterization of O-biotinylated hydroxy amino acid residues in peptides

Recent findings have indicated that certain hydroxyl groups of peptides have enhanced intrinsic chemical reactivity and can be O-acylated by N-hydroxysuccinimide esters of biotin. Analytical procedures are described for the identification of O-acylated derivatives of seryl, threonyl, and tyrosyl residues after reaction with the N-hydroxysuccinimide ester of biotin containing the extended spacer arm 6-aminohexanoic acid. The identification and chemical characterization of O-biotinylated residues included amino acid analysis, peptide sequence determination, and mass spectrometric analysis. The application of these analytical procedures provided unequivocal identification of O-biotinylated residues for a number of peptides investigated. In a separate study, we also show that O-biotinylated amino-terminal seryl residues occurring after proteolysis of peptides or proteins can rapidly undergo an O-->N acyl shift resulting in blockage of sequence analysis by the Edman degradation procedure.

Ultrashort laser pulse effects in ocular and related media

Relatively little experimental and theoretical data exist on the retinal hazards of ultrashort laser pulses operating in the visible and near infrared spectral regions. Because of potential nonlinear effects that can occur from high-peak irradiance, ultrashort laser pulses propagate from the cornea to the retina, we have developed four projects within our Ultrashort Pulse Effects program. First, we discuss preliminary ED50 threshold values for nanosecond (ns), picosecond (ps), and femtosecond (fs) single pulses for in-vivo ocular exposures in Dutch Belted Rabbits using pulses in the visible spectral region. Then we examine two experiments that study nonlinear absorption using water tubes and measure the nonlinear refractive index of ocular tissue using the Z-Scan technique. Finally, we determine laser-induced breakdown thresholds in ultrahigh purity water. These studies give reasonable estimates of the damage thresholds and insight into the biophysics of how ultrashort pulses interact with ocular media.

The science of unitary human beings: current perspectives

This article explicates current perspectives on Rogers' science of unitary human beings. Possibilities for nursing in the 21st century are elaborated upon. Attention is called to the increasingly rapid social changes which will have an impact on nursing science.

Nonlinear refraction in vitreous humor

We extend the application of the z-scan technique to determine the nonlinear refractive index (n(2)) for human and rabbit vitreous humor, water, and physiological saline. In these measurements there were nonlinear contributions to the measured signal from the aqueous samples and the quartz cell that held the sample. Measurements were made with 60-ps pulses at 532 nm. To our knowledge, this is the first measurement of the nonlinear refractive properties of biological material.

The Lewis x epitope is a major non-reducing structure in the sulphated N-glycans attached to Asn-65 of bovine pro-opiomelanocortin

The N-terminal glycopeptide of pro-opiomelanocortin (POMC), designated as the 16K fragment, is highly conserved throughout vertebrates from amphibians to mammals and is likely therefore to have an important functional role. In this paper, we report the first structural characterization of N-glycans attached to asparagine-65 of a 16K glycopeptide. The 16K fragment was isolated from bovine pituitaries and the N-glycans were analysed using fast atom bombardment mass spectrometry together with sugar and linkage analysis. Sulphated-N-acetylgalactosamine-capped antennae, typical of the pituitary glycohormones, were present in the major acidic components. The POMC oligosaccharides are distinct from those of the pituitary glycohormones because the sulphate is exclusively located on the 3-arm of biantennary structures and, in addition, a significant proportion of the molecules carry the Lewis x epitope. It is probable that these differences reflect the absence of a tripeptide motif in POMC which fully conforms to the criteria previously defined for the recognition sequence for the N-acetylgalactosamine transferase that is specific for the pituitary glycohormones [Smith and Baenziger (1992) Proc. Natl. Acad. Sci. USA, 89, 329-333]. It remains to be seen whether the Lewis x epitope is involved in selectin-mediated events, but previous studies suggest that the sulphated moieties are unlikely to play a major role in clearance. The Lewis x epitope is also present in the neutral N-linked oligosaccharides, together with a variety of other antennae including a rarely found fucosylated GalNAc-GlcNAc structure.

Variation in yield potential and salt tolerance of selected cultivars and natural populations of Trifolium repens L

The effects of NaCl (0-60 mol m-3) on growth rates, dry matter production, leaf expansion, photosynthesis and tissue ion concentrations were evaluated in 10, widely sourced cultivars and five natural populations of Trifolium repens. Shoot dry matter in all cultivars was significantly reduced at NaCl concentrations greater than 20 mol m-3. The rate of yield decline was greater in those cultivars which had the highest yield under non-saline conditions. In all cultivars, shoot concentrations of Na and Cl increased significantly with increasing external NaCl concentrations, but the response of individual cultivars differed. Differences in the capacity to control the uptake and distribution of Na and Cl into the shoot were related to differences in salt tolerance. Four cultivars (Haifa, Irrigation, Ladino and Tamar), representing extremes in relative salt tolerance, were studied in detail. There were no significant differences in root growth or in the concentrations of Na and Cl in the roots between these cultivars when grown at 0 to 60 mol m-3 NaCl. Rates of leaf expansion and petiole elongation were significantly reduced by NaCl in Ladino and Tamar, which had lower salt tolerance, but were not reduced greatly in Haifa and Irrigation, the two cultivars with higher tolerance. Individual leaf photosynthesis rates were not sensitive to NaCl and did not differ between cultivars. There were no significant differences in shoot yields or in shoot ion concentrations between five populations of T. repens, collected from the Mediterranean Region, and the control cultivar Haifa, although two populations (9028 and 9494) produced more dry matter at 60 mol m-3 NaCl. The plant-to-plant variation for all measured characters was large within both populations and cultivars. This study showed that genotypes which have greater salt tolerance or greater yield potential under non-saline conditions can be selected in order to maximize the yield of T. repens under moderately saline conditions.

The linkage between stimulus frequency and covert peak areas as it relates to monaural localization

Head-related transfer functions for differently centered narrow noise bands were obtained on 6 subjects. Derived from these measurements were covert peak areas (CPAs), defined as the spatial constellation of loudspeakers that generates maximal sound pressure at the entrance of the ear canal for specific bands of frequency. On the basis of previous data, we proposed that different frequency bands served as important spectral cues for monaural localization of sounds from different loci and that location judgments were directed toward the CPAs associated with the different bands. In the first study, the stimuli were bandpass filtered so that they contained only those frequencies whose associated CPAs occupied either the monaural listener's "upper" or "lower" spatial regions. Loudspeakers, separated by 15 degrees, were stationed in the left hemifield, ranging from 0 degree to 180 degrees azimuth and -45 degrees to 60 degrees elevation. Subjects reported the loudspeaker from which the sound appeared to originate. Judgments of the sound's elevation were in general accord with the CPAs associated with the different frequency segments. In the second study, monaural localization tests were administered in which different 2.0-kHz-wide frequency bands linked with specific CPAs were notch filtered from a 3.5-kHz highpass noise band. For the control condition, the highpass noise was unfiltered. The data demonstrated that filtering a frequency segment linked with specific CPAs resulted in significantly fewer location responses directed toward that particular spatial region. These results demonstrate in greater detail the relation between the directional filtering properties of the pinna and monaural localization of sound.

Observations on an outbreak of anthrax in pigs in north Wales

Nineteen pigs in a 500 sow herd died from anthrax over a period of 95 days. This paper describes some of the problems encountered and how they were dealt with, including the risks to public health, the disposal of slurry and the cleansing and disinfection of the premises after the herd was slaughtered.

Decrease in erythrocyte glycophorin sialic acid content is associated with increased erythrocyte aggregation in human diabetes

1. Sialic acid moieties of erythrocyte membrane glycoproteins are the principal determinants of the negative charge on the cell surface. The resultant electrostatic repulsion between the cells reduces erythrocyte aggregation and hence the low shear rate viscosity and yield stress of blood. 2. Using g.c.-m.s., a decrease in sialic acid content has been observed in the major erythrocyte membrane glycoprotein, glycophorin A, obtained from nine diabetic patients compared with that from seven normal control subjects [median (range): 3.30 (0.01-11.90) versus 18.60 (3.20-32.60) micrograms/100 micrograms of protein, P less than 0.02]. 3. Erythrocyte aggregation, measured by viscometry as the ratio of suspension viscosity to supernatant viscosity (LS/S) in fibrinogen solution, was increased in ten diabetic patients compared with ten normal control subjects (mean +/- SEM, 37.6 +/- 1.3 versus 33.8 +/- 0.6, P less than 0.02). 4. In the patients in whom both viscometry and carbohydrate analysis were performed, the decrease in erythrocyte glycophorin sialylation and the increase in erythrocyte aggregation in fibrinogen solution were related statistically (LS/S correlated negatively with glycophorin sialic acid content, r = 0.73, P less than 0.05). 5. Decreased glycophorin sialylation provides an explanation at the molecular level for increased erythrocyte aggregation and it may be important in the pathogenesis of vascular disease in diabetes.

Nursing science and the space age

This article presents the basic elements of Rogers' science of unitary human beings. It defines science, explicates nursing as a science and an art, addresses the meaning of the principles of hemodynamics, and discusses the building blocks of these principles. Several theories arising from the science of unitary human beings are elaborated, and noninvasive therapeutic modalities are discussed as part of nursing practice.

Characterisation of the N-linked oligosaccharides of the light chain of human glycoprotein IIb by f.a.b.-m.s

The glycosylation of the light chain (GPIIbL) of glycoprotein IIb, one of the glycoproteins constituting the receptor for fibrinogen, fibronectin, and the von Willebrand factor on platelet cell surfaces, was investigated using fast-atom-bombardment mass spectrometry (f.a.b.-m.s.). Complex-type N-glycans were observed, attached to Asn-60. The most abundant oligosaccharide is a disialylated biantennary structure substituted with fucose on the chitobiose core. Mono-sialylated biantennary, and di- and tri-sialylated triantennary structures were found as minor constituents of the N-glycan population. The amino acid sequence of GPIIbL was fully mapped by f.a.b.-m.s., thereby providing the first direct evidence for the absence of O-glycosylation.

Foraging profiles of sympatric lowland gorillas and chimpanzees in the Lopé Reserve, Gabon

Comparison of the diets of sympatric gorillas and chimpanzees allows an analysis of niche separation between these two closely related species. Qualitatively, their diets are similar, being dominated by an equally diverse array of fruit species complemented with vegetative plant parts, seeds and insects. Gorillas eat more vegetative plant parts than do chimpanzees, but niche separation is most obvious in periods of fruit scarcity when the two species show different strategies that reduce competition for food. Their abilities to overcome mechanical and physical plant defences appear to differ, as gorillas are able to subsist entirely on abundant vegetative foods. Chimpanzees show social adjustment, foraging alone or in small groups, to reduce intra-specific competition for scarce fruit resources. Thus it seems that subtle physiological differences have far-reaching repercussions, defining potential evolutionary pathways for social organization and allowing sufficient niche separation between species.

Single-dose and three-day regimens of ofloxacin versus trimethoprim-sulfamethoxazole for acute cystitis in women

We compared the safety and efficacy of a single 400-mg dose of ofloxacin, ofloxacin (200 mg) once daily for 3 days, and trimethoprim-sulfamethoxazole (160:800 mg) twice daily for 7 days for the treatment of acute uncomplicated cystitis (urinary tract infection [UTI]) in women. At 5 weeks posttreatment, 35 (81%) of 43 patients treated with single-dose ofloxacin, 40 (89%) of 45 treated with 3 days of ofloxacin, and 41 (98%) of 42 treated with trimethoprim-sulfamethoxazole were cured (P = 0.03, single-dose ofloxacin group versus trimethoprim-sulfamethoxazole group). Retreatment for symptomatic recurrent UTI was given to 7 (16%) of 43 patients initially treated with single-dose ofloxacin, 3 (7%) of 45 patients treated with 3 days of ofloxacin, and 0 of 42 patients treated with trimethoprim-sulfamethoxazole (P = 0.01, single-dose ofloxacin group versus trimethoprim-sulfamethoxazole group). There was a trend in each of the three treatment groups toward an association between persistent or recurrent episodes of significant bacteriuria and a history of UTI in the past year and with diaphragm use. Ofloxacin was more effective than trimethoprim-sulfamethoxazole in eradicating Escherichia coli from rectal cultures during or soon after therapy, but there were no differences at later follow-up visits. Adverse effects were equally common among the three treatment groups. We conclude that single-dose ofloxacin was less effective than 7 days of trimethoprim-sulfamethoxazole for treatment of uncomplicated cystitis in women, while the 3-day ofloxacin regimen and the trimethoprim-sulfamethoxazole regimen were not significantly different in efficacy.

Glucan synthesis in Pneumocystis carinii

Rat-derived Pneumocystis carinii lysed with sodium deoxycholate catalysed the incorporation of uridine diphosphoglucose into an insoluble polymer. This enzyme activity was present in both the pellet and the supernatant when the P. carinii preparations were centrifuged. The polymer whose production was catalysed by the supernatant was examined by mass spectrometry and found to be an alpha 1----4 glucan, which is either unbranched or has relatively few branches. Polymer formation was completely inhibited by the addition of alpha amyloglucohydrolase to the supernatant. Polymer formation in the pellet of deoxycholate P. carinii preparations, unlike that in the supernatant, was partially resistant to alpha amyloglucohydrolase. The soluble glucan synthase activity in the supernatant was stable for more than 30 h at room temperature and was approximately 50 times more active on a cell-to-cell basis than the supernatant from deoxycholate preparations of the yeast Saccharomyces cerevisae.

A novel sialylated N-acetylgalactosamine-containing oligosaccharide is the major complex-type structure present in Bowes melanoma tissue plasminogen activator

We have employed fast atom bombardment mass spectrometry (FAB-MS) to screen the N-linked oligosaccharides of Bowes melanoma tissue plasminogen activator (mt-PA), and recombinant t-PAs produced by Chinese hamster ovary cells (rt-PA) and by a gene-enriched melanoma cell line (rmt-PA). These studies have confirmed the published structures for rt-PA, but are not in agreement with some of the structures reported for mt-PA. In the latter glycoprotein we have identified a novel structure as the major oligosaccharide attached to Asn-184 and Asn-448. This is a biantennary oligosaccharide consisting of a fucosylated trimannosyl core to which are attached two GalNAc(1----4)GlcNAc antennae, one of which carries a sialic acid linked at the 6-position of the GalNAc. Minor constituents are sialylated on both or neither antennae. The sialylated GalNAc moiety is unique in N-linked glycoproteins. The majority of complex structures in rmt-PA contain N-acetyllactosamine moieties at both the Asn-184 and Asn-448 sites with the novel oligosaccharide occurring as a minor component at the Asn-184 site. This study demonstrates the power of mass spectrometric strategies based on high-field two-sector FAB-MS for structure elucidations of natural and recombinant glycoproteins.

Fast-atom-bombardment mass spectrometry of sulphated oligosaccharides from ovine lutropin

The positive- and negative-ion f.a.b.-mass spectra and the fragmentation of sulphated oligosaccharides derived from ovine lutropin are described. Negative-ion f.a.b.-m.s. of methylated derivatives offers a sensitive and rapid method for screening glycans for sulphation, for defining the location of sulphated residues, and for sequencing sulphated branches. Positive-ion f.a.b.-m.s. gives complementary data on non-sulphated branches in both complex and hybrid-type sulphated structures.

The effect of NaCl on the establishment and growth of balansa clover (Trifolium michelianum Savi var. balansae Boiss.)

The effect of NaCl on the germination, seedling emergence and growth of established plants of balansa clover, Trifolium michelianum Savi var. balansae Bois. cv. Paradana was studied and compared with plants of subterranean clover T: subterraneum L. cv. Clare. Balansa and subterranean clover had similar salt tolerances at germination and seedling emergence. However balansa clover suffered from poor seedling vigour even under non-saline conditions, and this resulted in a low number of emerged seedlings over all NaCl concentrations compared with subterranean clover. Established plants of balansa clover, despite a lower initial seedling yield, were significantly more salt tolerant (P < 0.001) and had a greater survival rate over a four month period at concentrations greater than 75 mol m-3 NaCl. Shoot concentrations of chloride and sodium increased with increasing salinity in both species, however concentrations were lower in balansa clover especially at higher NaCl concentrations (75 and 100 mol m-3 NaCl). It is concluded that whilst established stands of balansa clover may be able to withstand high concentrations of NaCl, the major limitation to its establishment and production in saline irrigation areas is its poor seedling emergence and vigour.

Ciprofloxacin compared with doxycycline for nongonococcal urethritis. Ineffectiveness against Chlamydia trachomatis due to relapsing infection

We compared 7-day regimens of ciprofloxacin in dosages of 750 and 1000 mg twice daily with doxycycline 100 mg twice daily for the treatment of nongonococcal urethritis in 178 men enrolled in a prospective, randomized, double-blind trial. The overall clinical response was comparable in the three treatment groups at both 2 and 4 weeks after therapy. However, among patients who initially had cultures positive for chlamydia, Chlamydia trachomatis was reisolated within 4 weeks after treatment in none of 10 doxycycline-treated patients, in 11 (52%) of 21 patients treated with 750 mg of ciprofloxacin twice daily, and in six (38%) of 16 patients treated with 1000 mg of ciprofloxacin twice daily. Each of the recurrent strains was identical in serotype to the original infecting strain. We conclude that ciprofloxacin in dosages as high as 2 g daily is inadequate for treatment of chlamydial urethritis in men, often resulting in relapsing infections.

Creating a Climate for the Implementation of a Nursing Conceptual Framework

Over the last decade, increasing numbers of service and educational institutions have initiated plans to implement a nursing conceptual framework to guide practice, education, administration, and research. Regardless of the conceptual framework being implemented, for effective change to occur, considerable attention must be paid to the nature of the learning process experienced by individual nurses. In this article, adult learning theory is discussed as it relates to the process of learning a nursing conceptual framework.

Variation in turf-type morphological characters within Lolium perenne L. cv. Victorian

Aspects of plant morphology and flowering were measured in a spaced-plant collection of perennial ryegrass (Lolium perenne L.) cv. Victorian in order to assess the possibility of improving this cultivar for turf. The Victorian perennial ryegrass collection was also compared with a smaller collection of fine-leafed turf ryegrasses. Within cv. Victorian, positive phenotypic correlations were found betwecn the character�s leaf length and width, leaf length and sheath length, leafwidth and sheath length, leafwidth and leaf tensile strength, and leafiness (leaf number per unit ground area) and angle of growth. The correlated responses to selection were significant (P<0.001) for all characters, with the exception of heading date. Heritability values, calculated by using three methods, were also very high (>0.70). These heritabilities, combined with the fact that the variation found within Victorian ryegrass often encompassed the entire range in the turf ryegrass cultivars, indicate that an improved turf-type could be developed within cv. Victorian. However, some compromise must be made in selection strategies due to unfavourable correlations between the character's turf wear, assessed by using leaf tensile strength and appearance, and between vegetative growth and seed production.

Novel fast atom bombardment mass spectrometric procedures for glycoprotein analysis

We describe procedures, based upon fast atom bombardment mass spectrometry, for characterising the carbohydrate chains in glycoproteins and for determining sites of glycosylation. Strategies for rapidly screening glycoproteins to ascertain the types of sugar chains present and the degree of heterogeneity are presented. Protocols are given for sequencing O- and N-linked glycans. These strategies exploit simple purification steps and afford data at high sensitivity.

Nursing science and art: a prospective

The 21st century will arrive with a plethora of manifestations of change. Rapid acceleration will be evident in every aspect of life. Diver sification and synthesis will grow as new world views multiply to encom pass the extraterrestrial. Nursing's abstract system signifies a new real ity as nurses participate in the process of change to benefit people. The future demands flexibility, imagination, and a sense of humor.

Structures of novel sialylated O-linked oligosaccharides isolated from human erythrocyte glycophorins

The O-linked oligosaccharides attached to human erythrocyte glycophorins were extensively characterized. In addition to the previously described disialylated tetrasaccharide, NeuNAc alpha 2----3Gal beta 1----3 (Neu-NAc alpha 2----6)GalNAcOH and monosialylated trisaccharide, NeuNAc alpha 2----3Gal beta 1----3GalNAcOH, novel trisialylated oligosaccharides were isolated. Methylation analysis, fast atom bombardment-mass spectrometry, and enzymatic degradation were used to elucidate the following novel structures: formula; see text: These results suggest that O-linked oligosaccharides with a disialosyl group, NeuNAc alpha 2----8NeuNAc alpha 2----, may be present in various tissues.

Isolation of mutants sensitive to 2-aminopurine and alkylating agents and evidence for the role of DNA methylation in Penicillium chrysogenum

Using high performance liquid chromatography, the presence of N6-methyladenine has been found at a level of 0.1 mol percent in DNA extracted from Penicillium chrysogenum. No 5-methylcytosine was detected. A mutant strain HP547, which is sensitive to the lethal effects of N-methyl-N'-nitro-N-nitrosoguanidine, methylmethane sulphonate and the base analogue 2-aminopurine shows an increased spontaneous mutation rate and no detectable DNA methylation. Comparison of restriction enzyme digests of wild type and undermethylated strains indicated that methylation was occurring at a different sequence to that of the Dam methylase system of E. coli.

High-performance liquid chromatographic identification of beta-lactam antibiotics produced by dermatophytes

Thirteen of 48 dermatophyte isolates were found by bioassay to produce beta-lactam antibiotics and seven produced other antibiotics. Estimation and detection of specific beta-lactams in culture broths by derivatization and HPLC was only possible following concentration and extraction procedures. Analysis of the concentrated broths demonstrated the production of penicillin X and penicillin G by two Trichophyton mentagrophytes strains and by one Microsporum canis strain; one further T. mentagrophytes strain produced only penicillin X. Additions of the beta-lactam side-chain precursors, phenylacetic acid and phenoxyacetic acid, to fermentation media failed to increase the antibiotic titres.