State-level gonorrhea rates and expedited partner therapy laws: insights from time series analyses

OBJECTIVE

In this study, we examined state-level monthly gonorrhea morbidity and assessed the potential impact of existing expedited partner therapy (EPT) laws in relation to the time that the laws were enacted.

STUDY DESIGN

Longitudinal study.

METHODS

We obtained state-level monthly gonorrhea morbidity (number of cases/100,000 for males, females and total) from the national surveillance data. We used visual examination (of morbidity trends) and an autoregressive time series model in a panel format with intervention (interrupted time series) analysis to assess the impact of state EPT laws based on the months in which the laws were enacted.

RESULTS

For over 84% of the states with EPT laws, the monthly morbidity trends did not show any noticeable decreases on or after the laws were enacted. Although we found statistically significant decreases in gonorrhea morbidity within four of the states with EPT laws (Alaska, Illinois, Minnesota, and Vermont), there were no significant decreases when the decreases in the four states were compared contemporaneously with the decreases in states that do not have the laws.

CONCLUSION

We found no impact (decrease in gonorrhea morbidity) attributable exclusively to the EPT law(s). However, these results do not imply that the EPT laws themselves were not effective (or failed to reduce gonorrhea morbidity), because the effectiveness of the EPT law is dependent on necessary intermediate events/outcomes, including sexually transmitted infection service providers' awareness and practice, as well as acceptance by patients and their partners.

Self-Assembly and Anti-Amyloid Cytotoxicity Activity of Amyloid beta Peptide Derivatives

The self-assembly of two derivatives of KLVFF, a fragment Aβ(16-20) of the amyloid beta (Aβ) peptide, is investigated and recovery of viability of neuroblastoma cells exposed to Aβ (1-42) is observed at sub-stoichiometric peptide concentrations. Fluorescence assays show that NH2-KLVFF-CONH2 undergoes hydrophobic collapse and amyloid formation at the same critical aggregation concentration (cac). In contrast, NH2-K(Boc)LVFF-CONH2 undergoes hydrophobic collapse at a low concentration, followed by amyloid formation at a higher cac. These findings are supported by the β-sheet features observed by FTIR. Electrospray ionization mass spectrometry indicates that NH2-K(Boc)LVFF-CONH2 forms a significant population of oligomeric species above the cac. Cryo-TEM, used together with SAXS to determine fibril dimensions, shows that the length and degree of twisting of peptide fibrils seem to be influenced by the net peptide charge. Grazing incidence X-ray scattering from thin peptide films shows features of β-sheet ordering for both peptides, along with evidence for lamellar ordering of NH2-KLVFF-CONH2. This work provides a comprehensive picture of the aggregation properties of these two KLVFF derivatives and shows their utility, in unaggregated form, in restoring the viability of neuroblastoma cells against Aβ-induced toxicity.

Fully automated software solution for protein quantitation by global metabolic labeling with stable isotopes

Metabolic stable isotope labeling is increasingly employed for accurate protein (and metabolite) quantitation using mass spectrometry (MS). It provides sample-specific isotopologues that can be used to facilitate comparative analysis of two or more samples. Stable Isotope Labeling by Amino acids in Cell culture (SILAC) has been used for almost a decade in proteomic research and analytical software solutions have been established that provide an easy and integrated workflow for elucidating sample abundance ratios for most MS data formats. While SILAC is a discrete labeling method using specific amino acids, global metabolic stable isotope labeling using isotopes such as (15)N labels the entire element content of the sample, i.e. for (15)N the entire peptide backbone in addition to all nitrogen-containing side chains. Although global metabolic labeling can deliver advantages with regard to isotope incorporation and costs, the requirements for data analysis are more demanding because, for instance for polypeptides, the mass difference introduced by the label depends on the amino acid composition. Consequently, there has been less progress on the automation of the data processing and mining steps for this type of protein quantitation. Here, we present a new integrated software solution for the quantitative analysis of protein expression in differential samples and show the benefits of high-resolution MS data in quantitative proteomic analyses.

The NERC DataGrid services

This short paper outlines the key components of the NERC DataGrid: a discovery service, a vocabulary service and a software stack deployed both centrally to provide a data discovery portal, and at data providers to provide local portals and data and metadata services.

Factors governing the solubilization of phosphopeptides retained on ferric NTA IMAC beads and their analysis by MALDI TOFMS

We have revisited the direct analysis experiments reported by Tomer and co-workers in the MALDI-TOFMS analysis of phosphopeptide-loaded immobilized metal ion affinity chromatography (IMAC) beads (Zhou, W.; Merrick, B. A.; Khaledi, M. G.; Tomer, K. B. J. Am. Soc. Mass Spectrom. 2000, 11, 273-282). The results described herein provide no evidence to support a laser-induced direct desorption of phosphopeptides chelated on IMAC beads. However, we have established that solubilization of mono-phosphopeptides from their immobilized Fe3+-NTA chelates does occur effectively in solutions containing certain MALDI matrices. Particularly effective is 2,5-dihydroxybenzoic acid (2,5-DHB), which apparently forms a stronger chelation complex with Fe3+-NTA than mono-phosphopeptides. With regard to the disparity observed between the low pH value of MALDI matrices (saturated 2,5-DHB(aq) approximately pH 2) and the high pH values of conventional IMAC eluents (typically above pH 7), we have also investigated the influence of eluent pH on the recovery of phosphopeptides from IMAC media. Finally, we have confirmed the importance of employing ammonium dihydrogen phosphate as buffer to achieve effective liberation of mono- and all poly-phosphopeptide species from Fe3+-NTA IMAC resin.

Proteomics--post-genomic cartography to understand gene function

The completion of the genomic sequences of numerous organisms from human and mouse to Caenorhabditis elegans and many microorganisms, and the definition of their genes provides a database to interpret cellular protein-expression patterns and relate them to protein function. Proteomics technologies that are dependent on mass spectrometry and involve two-dimensional gel electrophoresis are providing the main window into the world of differential protein-expression analysis. In this article, the limitations and expectations of this research field are examined and the future of the analytical needs of proteomics is explored.

Cloning of a human type II phosphatidylinositol 4-kinase reveals a novel lipid kinase family

Phosphoinositide lipids regulate numerous cellular processes in all eukaryotes. The versatility of this phospholipid is provided by combinations of phosphorylation on the 3', 4', and 5' positions of the inositol head group. Two distinct structural families of phosphoinositide (PI) kinases have so far been identified and named after their prototypic members, the PI 3-kinase and phosphatidylinositol (PtdIns) phosphate kinase families, both of which have been found to contain structural homologues possessing PI 4-kinase activity. Nevertheless, the prevalent PtdIns 4-kinase activity in many mammalian cell types is conferred by the widespread type II PtdIns 4-kinase, which has so far resisted molecular characterization. We have partially purified the human type II isoform from plasma membrane rafts of human A431 epidermoid carcinoma cells and obtained peptide mass and sequence data. The results allowed the cDNA containing the full open reading frame to be cloned. The predicted amino acid sequence revealed that the type II enzyme is the prototypic member of a novel, third family of PI kinases. We have named the purified protein type IIalpha and a second human isoform, type IIbeta. The type IIalpha mRNA appears to be expressed ubiquitously in human tissues, and homologues appear to be expressed in all eukaryotes.

The nature of collision-induced dissociation processes of doubly protonated peptides: comparative study for the future use of matrix-assisted laser desorption/ionization on a hybrid quadrupole time-of-flight mass spectrometer in proteomics

Comparative MS/MS studies of singly and doubly charged electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) precursor peptide ions are described. The spectra from these experiments have been evaluated with particular emphasis on the data quality for subsequent data processing and protein/amino acid sequence identification. It is shown that, once peptide ions are formed by ESI or MALDI, their charge state, as well as the collision energy, is the main parameter determining the quality of collision-induced dissociation (CID) MS/MS fragmentation spectra of a given peptide. CID-MS/MS spectra of singly charged peptides obtained on a hybrid quadrupole orthogonal time-of-flight mass spectrometer resemble very closely spectra obtained by matrix-assisted laser desorption/ionization post-source decay time-of-flight mass spectrometry (MALDI-PSD-TOFMS). On the other hand, comparison of CID-MS/MS spectra of either singly or doubly charged ion species shows no dependence on whether ions have been formed by ESI or MALDI. This observation confirms that, at the time of precursor ion selection, further mass analysis is effectively decoupled from the desorption/ionization event. Since MALDI ions are predominantly formed as singly charged species and ESI ions as doubly charged, the associated difference in the spectral quality of MS/MS spectra as described here imposes direct consequences on data processing, database searching using ion fragmentation data, and de novo sequencing when ionization techniques are changed.

Role of intracellular chloride in the reversible activation of neutrophil beta 2 integrins: a lesson from TNF stimulation

The process of beta(2) integrin activation, which enhances the interaction of these heterodimers with ligands, plays a crucial role in the adherence-dependent neutrophilic polymorphonuclear leukocytes' (PMN) responses to TNF. Our previous observation, showing that a marked decrease of the high basal Cl(-) content (Cl(-)(i)) is an essential step in the TNF-induced activation of PMN, stimulated this study, which investigates the role of alterations of Cl(-)(i) in the activation of beta(2) integrins triggered by TNF. Here we show that TNF enhances the expression of activation-specific neoepitopes of beta(2) integrins, namely, epitope 24, a unique epitope present on all three leukocyte integrin alpha subunits, and epitope CBRM1/5, localized to the I domain on the alpha-chain of Mac-1 (CD11bCD18). Moreover, we demonstrate that the conformational changes underlying the expression of the neoepitopes are dependent on a drop in Cl(-)(i) because 1) inhibition of Cl(-)(i) decrease is invariably accompanied by inhibition of beta(2) integrin activation, 2) Cl(-)(i) decrease induced by means other than agonist stimulation, i.e., by placing PMN in Cl(-)-free buffers, activates beta(2) integrins, and 3) restoration of the original Cl(-)(i) levels is accompanied by deactivation of beta(2) integrins. We also show that Cl(-)(i) decrease is required for TNF-induced cytoplasmic alkalinization, but such a rise in pH(i) does not seem to be relevant for beta(2) integrin activation. The results of our study emphasize the role of Cl(-) as a new PMN "second messenger."

TNF-Induced shedding of TNF receptors in human polymorphonuclear leukocytes: role of the 55-kDa TNF receptor and involvement of a membrane-bound and non-matrix metalloproteinase

A down-modulation of both the 55-kDa (TNF-R55) and the 75-kDa (TNF-R75) TNF receptors is observed in neutrophils exposed to a variety of stimuli. Proteolytic cleavage of the extracellular region of both receptors (shedding) and, with TNF, internalization of TNF-R55 and shedding of TNF-R75 are the proposed mechanisms. We have characterized the TNF-induced shedding of TNF receptors in neutrophils and determined the nature of the involved proteinase. Neutrophils exposed to TNF release both TNF receptors. A release of TNF receptors comparable to that observed with TNF was induced with TNF-R55-specific reagents (mAbs and a mutant of TNF) but not with the corresponding TNF-R75-specific reagents. A hydroxamic acid compound (KB8301) almost completely inhibited shedding of TNF-R55 and to a lesser degree shedding of TNF-R75. KB8301 also inhibited FMLP-induced shedding to a similar extent. Shedding was also inhibited by 1,10-phenanthroline, but this effect was considered nonspecific as the compound, at variance with KB8301, almost completely inhibited TNF and FMLP-induced PMN activation. Diisopropylfluorophosphate partially inhibited shedding of TNF-R75, suggesting the contribution of a serine proteinase to the release of this receptor. Shedding activity was not affected by matrix metalloproteinases inhibitors nor was it released in the supernatants of FMLP-stimulated neutrophils. These results suggest that TNF induces release of its receptors, that such a release is mediated via TNF-R55, and that a membrane-bound and non-matrix metalloproteinase is involved in the process. The possibility that ADAM-17, which we show to be expressed in neutrophils, might be the involved proteinase is discussed.

Employing target modifications for the investigation of liquid infrared matrix-assisted laser desorption/ionization mass spectrometry

We present a new target modification for commercial ion sources to facilitate the use of liquid matrices such as glycerol and lactic acid in infrared matrix-assisted laser desorption/ionization (IR-MALDI). Benefits of this modification include increased sensitivity compared with the unmodified commercial target, mass resolution comparable to the best achievable with conventional IR-MALDI or UV-MALDI, and decreased sample volatility leading to an analysis time extended up to fivefold compared with using conventional target designs (up to 1 hour using volumes of only 250 nL).

Triggering of chloride ion efflux from human neutrophils as a novel function of leukocyte beta 2 integrins: relationship with spreading and activation of the respiratory burst

PMN residing on immobilized fibronectin have been shown to respond to TNF with an intense and long lasting Cl- efflux that leads to a marked decrease of the unusually high basal Cl- content of these phagocytes. The finding that this Cl- efflux depends, at least in part, on beta2 integrin engagement stimulated the present investigation, which addresses the question as to whether beta2 integrins per se, in the absence of PMN agonists, are able to generate signals triggering Cl- efflux. We induced beta2 integrin cross-linking by plating PMN onto surface-bound mAbs directed against either the common beta-chain (CD18) or the individual alpha-chains (CD11a, CD11b, CD11c) of LFA-1, CR3, and gp150/95. Anti-CD18 mAbs triggered a marked release of Cl- ions, which was accompanied by spreading and activation of the respiratory burst. Cross-linking of gp150/95 and LFA-1 generated the most powerful signals for the activation of Cl- efflux. The results of three independent experimental approaches, i.e., kinetic studies, use of Cl- transport inhibitors, and modulation of Cl- efflux with different amounts of anti-beta2 integrin mAbs, indicated that Cl- efflux regulates both spreading and respiratory burst triggered by beta2 integrin cross-linking. Cl- efflux appears to be independent on either alterations of [Ca2+]i or changes in the plasma membrane potential and shows sensitivity to a raise in pHi. This study uncovers a new signaling ability of beta2 integrins and contributes to highlight the role of Cl- efflux in the outside-in signal transduction pathway regulating adherence-dependent PMN responses.

Role of the 75-kDa TNF receptor in TNF-induced activation of neutrophil respiratory burst

The exclusive role of the 55-kDa TNF receptor (TNF-R55) as the signaling receptor in TNF-induced activation of respiratory burst by human polymorphonuclear leukocytes residing on biologic surfaces has been inferred from results obtained with receptor-specific monoclonal and polyclonal Abs. In this work, we confirm this assumption by a more direct approach, i.e., by using receptor-specific TNF mutants (p55TNF and p75TNF) and, as a novel contribution, we show that cooperation of the 75-kDa TNF receptor (TNF-R75) is required for a full blown response to the cytokine. This conclusion stems from three sets of data: 1) none of the TNF-R55-specific agonists used, i.e., mAbs or p55TNF, induced a respiratory burst comparable with that induced by TNF; 2) selective down-modulation of TNF-R75 resulted in a diminished response to TNF but not to TNF-R55-specific agonists or to the chemotactic peptide FMLP; and 3) mAbs that either block or stabilize binding of TNF to TNF-R75 inhibited the response to the cytokine, suggesting that cooperation requires not only TNF binding to the receptor but also an appropriate dissociability from it. The inhibitory effect of the Abs increased as the cytokine concentrations decreased, indicating that cooperation by TNF-R75 becomes more relevant at low TNF doses. Such a cooperation does not seem to rely on the activation of a TNF-R75-linked signaling pathway independent of TNF-R55, since the response to p55TNF and p75TNF given in combination was not higher than the response to p55TNF alone. The possible mechanisms of cooperation are discussed.

Analysis of phospho- and glycopolypeptides with infrared matrix-assisted laser desorption and ionization

The analytical characteristics of infrared (IR) matrix-assisted laser desorption and ionization (MALDI) were investigated for the analysis of phosphopeptides, a phosphopolypeptide, and glycopeptides. Two commercially available instruments, a high-resolution delayed extraction (DE) reflectron time-of-flight (RETOF) mass spectrometer and a high-power pulsed Er:YAG laser, were interfaced to produce a high-resolution MALDI-DE-RETOF instrument that is easy to use and can be switched between UV- and IR-MALDI mode within seconds. In the interface design, particular attention was paid to maintaining the same professional operating environment for the new IR-MALDI mode as exists for the commercial UV-MALDI mode. This instrument configuration facilitates comparative observation and investigation of the relative analytical merits of IR- and UV-MALDI. The results of studies of the tryptic alpha-casein phosphopeptides, RP1 (a Thr45-monophosphorylated congener of the recombinant protein hirudin variant 1), and fetuin Asn81 tryptic glycopeptides are presented. The elimination of labile substituents such as phosphoric acid and sialic acid is suppressed in IR-MALDI-RETOF mass spectrometry, with concomitant higher analyte ion yields. These results reflect the advantages that accrue from deposition of significantly less internal energy in the case of IR-MALDI.

The effect of different condylar positions on masticatory muscle electromyographic activity in humans

OBJECTIVES

The purpose of this study was to determine a condylar position that permitted the greatest total temporalis and masseter muscle activity in maximum static clench.

STUDY DESIGN

Twenty normal adults, 9 women and 11 men, were evaluated to determine masseter and temporalis activity in maximum static clench with mandibular condyles in different therapeutic positions. Bimanually manipulated, leaf gauge, centric occlusion, and neuromuscular condylar positions were studied.

RESULTS

When mandibular condyles were placed anteroinferiorly in a neuromuscular position, total masticatory muscle recruitment was the greatest. In a bimanually manipulated or a leaf gauge position, mandibular condyles were positioned superoposteriorly, producing the least amount of muscle recruitment.

CONCLUSIONS

The result of any therapeutic position should be an improvement in muscle function. With respect to balance and activation, a neuromuscular condylar position proved to be the position capable of recruiting the greatest motor unit activity when compared with a bimanually manipulated position, a leaf gauge position, and a neuromuscular position.

Infrared matrix-assisted laser desorption and ionization by using a tunable mid-infrared free-electron laser

Initial results of infrared matrix-assisted laser desorption/ionization (IR-MALDI) mass spectrometry of proteins by using the Vanderbilt free-electron laser as the source of selective vibrational excitation are reported. The ability of this laser to initiate desorption and ionization by excitation of specific vibrational modes is demonstrated. For the first time it is shown that IR-MALDI mass spectrometry at wavelengths other than those available from conventional fixed-frequency IR lasers, that is, 2.79 (Er:YSGG), 2.94 (Er:YAG), and 9.3-10.6 µm (CO2), is feasible and exhibits similar performance. IR-MALDI mass spectra were taken in the wavelength ranges 2.8-4 and 5.5-6.5 µm, covering the absorption bands of the O-H and C=O stretch vibrations typical of many organic compounds such as succinic acid, fumaric acid, or nicotinic acid, which were used as matrices in these studies. A comparison between these results and Er:YAG/YSGG MALDI data are given. The potential of IR-MALDI at wavelengths near the C=O stretch vibration and the possibilities for studies of the IR-MALDI mechanisms by using this kind of tunable source are discussed.

Chloride ion efflux regulates adherence, spreading, and respiratory burst of neutrophils stimulated by tumor necrosis factor-alpha (TNF) on biologic surfaces

Chloride ion efflux is an early event occurring after exposure of neutrophilic polymorphonuclear leukocytes (PMN) in suspension to several agonists, including cytokines such as tumor necrosis factor-alpha (TNF) and granulocyte/macrophage-colony stimulating factor (Shimizu, Y., R.H. Daniels, M.A. Elmore, M.J. Finnen, M.E. Hill, and J.M. Lackie. 1993. Biochem. Pharmacol. 9:1743-1751). We have studied TNF-induced Cl- movements in PMN residing on fibronectin (FN) (FN-PMN) and their relationships to adherence, spreading, and activation of the respiratory burst. Occupancy of the TNF-R55 and engagement of beta 2 integrins cosignaled for an early, marked, and prolonged Cl- efflux that was accompanied by a fall in intracellular chloride levels (Cl-i). A possible causal relationship between Cl- efflux, adherence, and respiratory burst was first suggested by kinetic studies, showing that TNF-induced Cl- efflux preceded both the adhesive and metabolic response, and was then confirmed by inhibition of all three responses by pretreating PMN with inhibitors of Cl- efflux, such as ethacrynic acid. Moreover, Cl- efflux induced by means other than TNF treatment, i.e., by using Cl(-)-free media, was followed by increased adherence, spreading, and metabolic activation, thus mimicking TNF effects. These studies provide the first evidence that a drastic decrease of Cl-i in FN-PMN may represent an essential step in the cascade of events leading to activation of proadhesive molecules, reorganization of the cytoskeleton network, and assembly of the O2(-)-forming NADPH oxidase.

Level-headed about empowerment

Empowerment: born as quality circles, declined, and reincarnated beneath a broader heading. Parents empower children, yet organizational efforts lack the same basic skills. Is self-direction for everyone? Seven levels of empowerment are examined plus tips for conducting a feasibility study to determine your opportunities for success.

Comparison of IR- and UV-matrix-assisted laser desorption/ionization mass spectrometry of oligodeoxynucleotides

UV-matrix assisted laser desorption/ionization mass spectrometry (UV-MALDI-MS) with 3-hydroxypicolinic acid as matrix and IR-MALDI-MS with succinic acid as matrix have proved their feasibility for highly accurate and sensitive mass determination of nucleic acids (DNA and RNA). In this work, a detailed comparison of these two MALDI-methods and between positive- and negative ion mass spectra for the analysis of oligodeoxynucleotides is undertaken. Mass spectra of DNA sequences with up to 40 nucleotides are shown. Both linear and reflectron time-of-flight mass analyzers were used within this study and are compared for their potential in the MALDI analysis of oligodeoxynucleotides. The role of molecule-ion fragmentation is also discussed.

Evidence that tumor necrosis factor alpha (TNF)-induced activation of neutrophil respiratory burst on biologic surfaces is mediated by the p55 TNF receptor

Polymorphonuclear leukocytes (PMN) residing on biologic surfaces respond with a vigorous respiratory burst when exposed to tumor necrosis factor alpha (TNF). PMN possess both the p55 and the p75 TNF receptors, but their role in the elicitation of the respiratory burst is not known. We addressed this problem by studying the effect of monoclonal antibodies (MoAbs) directed against the p55 TNF receptor (MoAb H398 and MoAb htr-9) and the p75 TNF receptor (MoAb utr-1) on TNF-induced production of O2- by PMN residing on fibronectin-coated surfaces. Neither the anti-p55 nor the anti-p75 MoAbs affected TNF-induced O2- production despite their known ability to competitively inhibit TNF binding to the corresponding receptor. Experiments with the antibodies alone showed that the anti-p55 MoAbs directly triggered PMN O2- production, whereas no response was elicited by the anti-p75 MoAb. PMN unresponsiveness to the anti-p75 MoAb could not be ascribed to low expression of p75 receptor, because binding of the anti-p75 MoAb utr-1 to PMN was, indeed, even higher than binding of the anti-p55 MoAb htr-9. The agonistic activity of the anti-p55 MoAbs was comparable with that of TNF and was not or only minimally modified by the simultaneous presence of TNF. Triggering of the respiratory burst by TNF was completely prevented by Fab fragments of the anti-p55 MoAb H398. Moreover, the monovalent Fab fragments, which lacked any stimulatory effect on PMN O2- production, acquired strong agonistic activity on cross-linking with anti Fab antibodies, suggesting that the ability of the anti-p55 antibodies to stimulate PMN O2- production depends on their ability to cross-link the TNF receptors. The agonistic effect of the anti-p55 MoAbs was only observed with cells residing on fibronectin-coated surfaces and not with cells in suspension, and in terms of kinetics, dependence on beta 2 integrin-mediated adherence, microfilament integrity, and sensitivity to elevations of intracellular levels of cAMP, it was virtually indistinguishable from the agonistic effect of TNF. Taken together, these results suggest that the p55 receptor is responsible for TNF-induced triggering of the respiratory burst of PMN residing on biologic surfaces.

Cerebral metabolism and electrocortical activity in the chronically hyperglycemic lamb

Pages R1262–R1269: T. S. Rosenkrantz, I. Knox, E. L. Zalneraitis, J. R. Raye, P. J. Porte, R. Cramer, R. Smoloski, and A. F. Philipps. “Cerebral metabolism and electrocortical activity in the chronically hyperglycemic lamb.” Page R1265: Several errors relating to significance of changes in arterial oxygen concentration, cerebral oxygen delivery, and cerebral oxygen uptake were introduced into Table 1 by the publisher. All of the information in the abstract and text are correct as originally printed. A corrected version of the table is reprinted below. Note that there were no changes in the fetal arterial oxygen content during any of the study periods, cerebral oxygen delivery rose during G2 ( P = 0.06), and there was a significant increase in cerebral oxygen uptake during G2 ( P < 0.05). It is hoped that this clarifies conflicting information in the text and the table concerning the metabolic changes that occur in the brain of the chronically hyperglycemic fetal lamb.

(See PDF)

Cerebral metabolism and electrocortical activity in the chronically hyperglycemic lamb

Pages R1262–R1269: T. S. Rosenkrantz, I. Knox, E. L. Zalneraitis, J. R. Raye, P. J. Porte, R. Cramer, R. Smoloski, and A. F. Philipps. “Cerebral metabolism and electrocortical activity in the chronically hyperglycemic lamb.” Page R1265: Several errors relating to significance of changes in arterial oxygen concentration, cerebral oxygen delivery, and cerebral oxygen uptake were introduced into Table 1 by the publisher. All of the information in the abstract and text are correct as originally printed. A corrected version of the table is reprinted below. Note that there were no changes in the fetal arterial oxygen content during any of the study periods, cerebral oxygen delivery rose during G2 (P = 0.06), and there was a significant increase in cerebral oxygen uptake during G2 (P < 0.05). It is hoped that this clarifies conflicting information in the text and the table concerning the metabolic changes that occur in the brain of the chronically hyperglycemic fetal lamb.

(See PDF)

Cerebral metabolism and electrocortical activity in the chronically hyperglycemic fetal lamb

Previous studies in the fetal lamb have demonstrated that hyperglycemia stimulates the fetal metabolic rate. The present study examined the effects of chronic fetal hyperglycemia on fetal cerebral metabolic rate and electrocortical activity. Nine chronically instrumented fetal lambs had measurements of cerebral blood flow and cerebral uptake/excretion of oxygen, glucose, lactate, and beta-hydroxybutyrate taken before and during a 48-h fetal glucose infusion. Electrocortical activity was also recorded. The fetal arterial glucose concentration was 19.8 +/- 2.0 mg/dl before glucose infusion and 48 +/- 4.5 to 54.6 +/- 6.6 mg/dl during the infusion period. Cerebral blood flow and cerebral glucose and oxygen uptake increased by 219, 209, and 171%, respectively, by the end of the infusion period. There was a linear relationship between the fetal arterial glucose concentration and cerebral blood flow and cerebral glucose and oxygen uptakes. The electroencephalogram showed significant slowing with increases in the cerebral metabolic rate. These findings suggest that fetal hyperglycemia is associated with significant metabolic stimulation of the brain.

Ion stability of nucleic acids in infrared matrix-assisted laser desorption/ionization mass spectrometry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with infrared laser light of a wavelength of 2.94 microns has been used for the analysis of nucleic acids. Spectra of oligodeoxynucleotides up to 26 nucleotides, oligothymidylic acids up to 100 nucleotides as well as different synthetic RNA oligomers and RNA transcripts up to 104 nucleotides are presented. A main problem in the analysis of oligodeoxynucleotides was found to be related to the loss of bases. The stability of oligothymidylic acids as opposed to oligodeoxynucleotides containing all four bases indicates that the loss of bases is correlated with A, C and G protonation which decreases the stability of the N-glycosidic bond. Experiments indicate that the breakage of the N-glycosidic bond probably occurs during the desorption process due to proton transfer from the phosphodiester groups to the ionizable bases. RNA displayed a significantly higher stability in MALDI-MS due to the presence of a 2'-OH group. Consequently, signals of RNA transcripts with a length of up to 142 nucleotides could be detected by MALDI-MS. Technical details of the method, including the distribution of positive counterions on the phosphodiester backbone, the upper mass limit and mass accuracy are discussed along with a number of potential analytical applications.

Potentiation of human polymorphonuclear leukocytes respiratory burst and phagocytosis by a standardized liver and spleen fraction of peptides

The effect of Factor AF2 (AF2), a xenogeneic fraction of peptides with a molecular weight of < 10,000 Dalton obtained from livers and spleens of newborn lambs, on the oxygen consumption and the phagocytic activity of human polymorphonuclear leukocytes (PMN) was studied. AF2 increased the oxygen uptake of PMN exposed both to serum-treated zymosan (STZ), a phagocytosable stimulus, and phorbol-myristate-acetate (PMA), a soluble stimulus. The potentiating effect of the drug was dose-dependent and more pronounced when suboptimal amounts of either stimulus were used. The phagocytic activity of PMN, as measured by the rate of mineral oil particles ingestion, was also increased by AF2 in a dose-dependent manner. These results suggest that the drug may influence PMN behaviour in at least two ways: 1. by increasing the rate of phagocytosis, and 2. by potentiating the respiratory burst induced by soluble and particulate stimuli. The results are discussed in relation to the beneficial effects of AF2 in cancer patients under chemotherapy or radiation treatment.

The effect of four jaw relations on electromyographic activity in human masticatory muscles

Significant differences were found in the electromyographic (EMG) activation between the masseter and temporalis muscles for the leaf gauge (LG), manually manipulated (CR) and neuromuscular (NM) bite positions during maximal static clench. The LG position consistently demonstrated the lowest EMG activity, while the NM position displayed the highest degree of muscle activity. Similarly, the ratio of the masseter/temporalis EMG activity during maximal clench was lower for the LG and CR positions and highest for the NM position. These data indicate that the NM position produced the greatest total muscle recruitment, with more masseter involvement during maximal clench, and enabled the subjects to generate greater clenching forces in the NM position as compared to the LG and CR positions.

Effects of a continuous infusion of tris(hydroxymethyl)aminomethane on acidosis, oxygen affinity, and serum osmolality

The effects of a continuous infusion of tris(hydroxymethyl)aminomethane (THAM) on pH, base excess, p50, serum osmolality, and plasma drug concentration during respiratory acidosis were studied in newborn piglets. Measurements were made during three experimental periods: (1) control period with normal blood gases; (2) hypercapnia period, and (3) hypercapnia plus THAM period (THAM infusion: 1.65 mmol/kg/h). pH decreased and paCO2 increased between control period (7.40 +/- 0.05 and 45 +/- 3 mm Hg) and hypercapnia period (7.24 +/- 0.06 and 59 +/- 2 mm Hg; p < 0.001; mean +/- SD). pH returned to baseline (7.37 +/- 0.04) during the hypercapnia plus THAM period, while paCO2 remained elevated (63 +/- 4 mm Hg). p50 increased from 30.7 +/- 5.9 to 38.3 +/- 4.7 (p < 0.05) during hypercapnia and decreased with hypercapnia plus THAM. THAM concentration and base excess increased with time and were linearly related. Serum osmolality was unchanged during the THAM infusion. We conclude that continuous infusion of THAM is effective in normalizing pH during respiratory acidosis in the piglet.

Matrix-assisted laser desorption/ionization mass spectrometry of nucleic acids with wavelengths in the ultraviolet and infrared

A number of different matrices have been tested and compared for ultraviolet and infrared (UV and IR) matrix-assisted laser desorption/ionization (MALDI) of oligodeoxyribonucleotides and mixtures thereof, as well as ribonucleic acids (tRNA from yeast and rRNA from E. coli). A new technique for removing alkali cations from nucleic acid samples during sample preparation on the sample support is demonstrated. The amount of oligonucleotide sample consumed during a typical measurement in IR-MALDI-MS was determined.

A new, one-step assay on whole cell suspensions for peroxidase secretion by human neutrophils and eosinophils

The degranulation of neutrophils and eosinophils is frequently monitored by assaying myeloperoxidase (MPO) and eosinophil peroxidase (EPO) activity in the cell-free supernatant of degranulating cells, after removal of the cells by centrifugation. This procedure leads to underestimation of the extent of degranulation, since both peroxidases tend to stick to cell surfaces, to test tube walls, and to particulate stimuli used to elicit degranulation, because of their highly cationic nature. In this paper we describe a method for assaying MPO and EPO secretion in whole cell suspensions that avoids separation of the cells from the incubation medium. The least toxic and thus safest among the sensitive peroxidase substrates, 3,3',5,5'-tetramethylbenzidine (TMB), was employed for peroxidase assay. The method we describe here is applied to the detection of peroxidase release by neutrophil and eosinophil cell suspensions incubated in either polypropylene test tubes or flat-bottomed microtiter plate wells. Because of the omission of the centrifugation step, the TMB method offers two major advantages over the currently used techniques: (1) higher estimates of degranulation, which permits the use of a smaller number of cells (in the microassay version, 150,000 neutrophils and 50,000 eosinophils) and smaller amounts of the secretagogues, and (2) rapidity, since the degranulation assay can be performed immediately on completion of the cell incubation with the secretagogue.

A simple and rapid method for isolation of eosinophilic granulocytes from human blood

A simple and rapid method for the purification of morphologically and functionally intact eosinophils from human blood of both normal and eosinophilic subjects is described. The method is based on a single centrifugation of total blood leukocytes suspended in Percoll with specific gravity 1.0853 g/ml, after erythrocyte removal by dextran sedimentation. The peculiarity of this isolation technique is the maintenance of strictly physiological values of pH and osmolality throughout the entire procedure. Moreover, the cells are not subjected to measures aimed at changing the physical properties of either neutrophils or eosinophils. Because of such characteristics, this isolation method could be usefully exploited for comparative studies of normal and eosinophilic normodense eosinophils and of neutrophils and eosinophils from the same noneosinophilic subject.

Eosinophil activation on biologic surfaces. Production of O2- in response to physiologic soluble stimuli is differentially modulated by extracellular matrix components and endothelial cells

Production of O2- in response to FMLP, TNF, IFN-gamma, platelet activating factor, LPS, substance P, and PMA by human eosinophils in suspension and in contact with polystyrene ELISA plastic (PL) or biologic surfaces was studied. Monolayers of human endothelial cells (HEC) or PL coated with FCS, fibronectin, laminin, collagen types I and IV, fibrinogen, or fibrin were used as biologic surfaces. Only PMA and FMLP stimulated O2- generation by eosinophils in suspension. Eosinophils residing on HEC monolayers, either untreated or treated with LPS, were unresponsive to all stimuli except PMA. PMA induced O2- generation by eosinophils on all surfaces; FMLP on all surfaces but HEC monolayers; TNF and platelet-activating factor only on PL, fibrinogen, and fibrin; LPS and substance P only on PL. PMA was equally effective on eosinophils on surfaces and in suspension, whereas the effect of FMLP was greater on eosinophils on surfaces than on eosinophils in suspension. IFN-gamma was ineffective on any of the surfaces tested. These results indicate that biologic surfaces may profoundly affect the ability of eosinophils to respond with a respiratory burst to physiologically relevant soluble stimuli, the effect varying according to the nature of both the stimulus and the surface. Since the respiratory burst generates products of oxygen reduction that are toxic to several tissue components, it follows that biologic surfaces may modulate eosinophil-induced tissue injury.

Eosinophil activation on biologic surfaces. Production of O2- in response to physiologic soluble stimuli is differentially modulated by extracellular matrix components and endothelial cells

Production of O2- in response to FMLP, TNF, IFN-gamma, platelet activating factor, LPS, substance P, and PMA by human eosinophils in suspension and in contact with polystyrene ELISA plastic (PL) or biologic surfaces was studied. Monolayers of human endothelial cells (HEC) or PL coated with FCS, fibronectin, laminin, collagen types I and IV, fibrinogen, or fibrin were used as biologic surfaces. Only PMA and FMLP stimulated O2- generation by eosinophils in suspension. Eosinophils residing on HEC monolayers, either untreated or treated with LPS, were unresponsive to all stimuli except PMA. PMA induced O2- generation by eosinophils on all surfaces; FMLP on all surfaces but HEC monolayers; TNF and platelet-activating factor only on PL, fibrinogen, and fibrin; LPS and substance P only on PL. PMA was equally effective on eosinophils on surfaces and in suspension, whereas the effect of FMLP was greater on eosinophils on surfaces than on eosinophils in suspension. IFN-gamma was ineffective on any of the surfaces tested. These results indicate that biologic surfaces may profoundly affect the ability of eosinophils to respond with a respiratory burst to physiologically relevant soluble stimuli, the effect varying according to the nature of both the stimulus and the surface. Since the respiratory burst generates products of oxygen reduction that are toxic to several tissue components, it follows that biologic surfaces may modulate eosinophil-induced tissue injury.

Mechanisms of eosinophil adherence to cultured vascular endothelial cells. Eosinophils bind to the cytokine-induced ligand vascular cell adhesion molecule-1 via the very late activation antigen-4 integrin receptor

We have examined the mechanisms involved in the adherence of normal peripheral blood eosinophils to cultured human umbilical vein endothelial cells (HEC) under three conditions: (a) adherence in the absence of treatment of HEC or eosinophils with activating agents (basal adherence); (b) adherence induced by stimulation of eosinophils with phorbol ester (eosinophil-dependent adherence); and (c) adherence induced by pretreatment of HEC with LPS, tumor necrosis factor (TNF), or IL-1 (endothelial-dependent adherence). A mechanism was identified that was equally active in basal, eosinophil-dependent, and endothelial-dependent adherence. This mechanism was optimally active in the presence of both Ca++ and Mg++, and reduced in the presence of Ca++ only or Mg++ only. Furthermore, like the other mechanisms of eosinophil adherence, it was active at 37 degrees C but not at 4 degrees C. A second mechanism of adherence was involved in eosinophil- and in endothelial-dependent adherence. This mechanism was dependent on the CD11/CD18 adhesion complex of eosinophils (i.e., inhibited by anti-CD18 MAb) and it was active in the presence of Ca++ and Mg++ or Mg++ only, but not Ca++ only. The third mechanism of adherence was specific for endothelial-dependent adherence. It involved the endothelial ligand vascular cell adhesion molecule-1 (VCAM-1) and the eosinophil receptor very late activation antigen-4 (VLA-4, CD49d/CD29, i.e., inhibited by anti-VCAM-1 MAb or anti-VLA-4 MAb). This mechanism was active in the presence of Ca++ and Mg++ but not of Ca++ only or Mg++ only, and was not up- or downregulated when eosinophils were stimulated with phorbol ester. In contrast, the endothelial leukocyte adhesion molecule-1 (ELAM-1), that binds neutrophils and monocytes, was not involved in eosinophil adherence to LPS-, TNF-, or IL-1-stimulated HEC (i.e., not inhibited by anti-ELAM-1 MAb). We conclude that eosinophils, like monocytes and lymphocytes, bind to the cytokine-induced endothelial ligand VCAM-1 via the integrin receptor VLA-4.

Oxidation of homovanillic acid as a selective assay for eosinophil peroxidase in eosinophil peroxidase-myeloperoxidase mixtures and its use in the detection of human eosinophil peroxidase deficiency

Biochemical assays for peroxidase activity do not usually distinguish between different peroxidases. The guaiacol assay, for example, which is one of the most commonly used assays for peroxidase activity, is sensitive to both eosinophil peroxidase (EPO) and the peroxidase of neutrophils, i.e., myeloperoxidase (MPO), thus preventing distinction of the two peroxidases in mixed neutrophil-eosinophil populations. In this paper we describe a simple and sensitive method for selective assays of EPO in EPO-MPO mixtures or mixed populations of neutrophils and eosinophils. The method is based on the peroxidase-mediated oxidation of homovanillic acid (HVA) under appropriate assay conditions in which EPO is still very active in catalyzing the reaction whilst MPO-mediated HVA oxidation is almost undetectable. Optimal assay conditions were as follows: pH 10.5, 10 microM hydrogen peroxide, 0.8 mM HVA and an incubation time of 120 min at 37 degrees C. Under these conditions the assay permits EPO activities as low as 0.025 guaiacol U/ml to be measured even in the presence of 0.175 guaiacol U/ml of MPO. In mixed neutrophil-eosinophil cell suspensions the test permits the detection of as few as 5 X 10(3) eosinophils even in the presence of about 700 X 10(3) neutrophils (eosinophils: neutrophils ratio 1:140) with no appreciable interference by the latter cells. The method described here has been applied to studies of human EPO deficiency and proved to be successful in the identification of individuals with partial EPO deficiency, which is not feasible with non quantitative methods (for example, cytochemistry) or unselective biochemical assay of peroxidase activity.