Evaluation of a Diverse, Worldwide Collection of Wild, Cultivated, and Landrace Pepper (Capsicum annuum) for Resistance to Phytophthora Fruit Rot, Genetic Diversity, and Population Structure

Pepper is the third most important solanaceous crop in the United States and fourth most important worldwide. To identify sources of resistance for commercial breeding, 170 pepper genotypes from five continents and 45 countries were evaluated for Phytophthora fruit rot resistance using two isolates of Phytophthora capsici. Genetic diversity and population structure were assessed on a subset of 157 genotypes using 23 polymorphic simple sequence repeats. Partial resistance and isolate-specific interactions were identified in the population at both 3 and 5 days postinoculation (dpi). Plant introductions (PIs) 640833 and 566811 were the most resistant lines evaluated at 5 dpi to isolates 12889 and OP97, with mean lesion areas less than Criollo de Morelos. Genetic diversity was moderate (0.44) in the population. The program STRUCTURE inferred four genetic clusters with moderate to very great differentiation among clusters. Most lines evaluated were susceptible or moderately susceptible at 5 dpi, and no lines evaluated were completely resistant to Phytophthora fruit rot. Significant population structure was detected when pepper varieties were grouped by predefined categories of disease resistance, continent, and country of origin. Moderately resistant or resistant PIs to both isolates of P. capsici at 5 dpi were in genetic clusters one and two.

Sex-related heterogeneity in the life-history correlates of Mycobacterium bovis infection in European badgers (Meles meles)

Heterogeneity in the progression of disease amongst individual wild animals may impact on both pathogen and host dynamics at the population level, through differential effects on transmission, mortality and reproductive output. The role of the European badger (Meles meles) as a reservoir host for Mycobacterium bovis infection in the UK and Ireland has been the focus of intense research for many years. Here, we investigate life-history correlates of infection in a high-density undisturbed badger population naturally infected with M. bovis. We found no evidence of a significant impact of M. bovis infection on female reproductive activity or success, with evidence of reproduction continuing successfully for several years in the face of M. bovis excretion. We also found evidence to support the hypothesis that female badgers are more resilient to established M. bovis infection than male badgers, with longer survival times following the detection of bacterial excretion. We discuss the importance of infectious breeding females in the persistence of M. bovis in badger populations, and how our findings in male badgers are consistent with testosterone-induced immunosuppression. In addition, we found significant weight loss in badgers with evidence of disseminated infection, based on the culture of M. bovis from body systems other than the respiratory tract. For females, there was a gradual loss of weight as infection progressed, whereas males only experienced substantial weight loss when infection had progressed to the point of dissemination. We discuss how these differences may be explained in terms of resource allocation and physiological trade-offs.

Renal calculi in wild Eurasian otters (Lutra lutra) in England

Macroscopic renal calculi were seen in 50 of 492 (10.2 per cent) wild Eurasian otters found dead in England from 1988 to 2007. Forty-eight adults and two subadults were affected. Calculi were present in 15.7 per cent (31 of 197) of adult males and 12.7 per cent (17 of 134) of adult females. There was an increase in prevalence in the study population over time; no calculi were found in 73 otters examined between 1988 and 1996, but in most subsequent years they were observed with increased frequency. Calculi occurred in both kidneys but were more common in the right kidney. They varied greatly in shape and size; larger calculi were mostly seen in the calyces while the smallest ones were commonly found in the renal medulla. Calculi from 45 cases were examined by x-ray diffraction analysis; in 43 (96 per cent), they were composed solely of ammonium acid urate. Affected otters had heavier adrenal glands relative to their body size than unaffected otters (P<0.001). There was no significant association between body condition index and the presence of calculi (P>0.05). Many otters had fresh bite wounds consistent with intraspecific aggression. The proportion bitten increased over time and this coincided with the increased prevalence of renal calculi.

Titrated low-dose vaginal and/or oral misoprostol to induce labour for prelabour membrane rupture: a randomised trial

OBJECTIVE

To evaluate the clinical effectiveness and safety of titrated low-dose misoprostol for induction of labour (IOL) in the presence of prelabour rupture of membranes (PROM).

DESIGN

Randomised controlled trial.

SETTING

Maternity units in the UK (9) and Egypt (1).

POPULATION

Women >34 weeks of gestation with PROM, singleton viable fetus and no previous caesarean section.

METHODS

Subjects randomised to IOL with a titrated low-dose misoprostol regimen (oral except if unfavourable cervix, where initial dose vaginal) or a standard induction method, namely vaginal dinoprostone followed by intravenous oxytocin if the cervix was unfavourable or intravenous oxytocin alone if the cervix was favourable.

MAIN OUTCOME MEASURES

Primary outcome measures were caesarean section and failure to achieve vaginal delivery within 24 hours. Analysis was by intention to treat.

RESULTS

The trial did not achieve the planned sample size of 1890 due to failure in obtaining external funding. Seven hundred and fifty-eight women were randomised (375 misoprostol and 383 standard). There were less caesarean section (14 versus 18%, relative risk [RR] 0.79; 95% CI 0.57-1.09) and less women who failed to achieve vaginal delivery within 24 hours in the misoprostol group (24 versus 31%, RR 0.79; 95% CI 0.63-1.00), but the differences were not statistically significant. Subgroup analysis showed that with unfavourable cervix, misoprostol may be more effective than vaginal dinoprostone. There was no difference in hyperstimulation syndrome. There were more maternal adverse effects with misoprostol, but no significant differences in maternal and neonatal complications.

CONCLUSIONS

Titrated low-dose misoprostol may be a reasonable alternative for IOL in the presence of PROM, particularly in women with an unfavourable cervix. Safety and rare serious adverse events could not be evaluated in a trial of this size.

Umbilical cord plasma concentrations of free morphine following single-dose diamorphine analgesia and their relationship to dose-delivery time interval, Apgar scores and neonatal respiration

OBJECTIVE

To find the effect of dose-delivery interval on cord-blood levels of diamorphine metabolites and its effect on Apgar sores and neonatal respiration.

STUDY DESIGN

Pilot study conducted in labour ward of a district general hospital. One hundred women who had normal delivery and received single dose of 7.5mg of intramuscular injection of diamorphine in labour were recruited in the study. A 2.0 ml sample of umbilical venous blood was collected from the placenta after delivery of the baby. The sample was analysed using RIA method to measure free morphine. Details about the labour and baby's condition at birth were recorded.

RESULTS

The concentration of free morphine in the umbilical venous blood was significantly associated with the dose-delivery interval (coefficient (95% CI)=1.08(0.99-1.18), p<0.001). Twenty neonates had low Apgar score (< or =7) at 1 min. The odds of such a low score were raised with higher log free morphine in the cord venous plasma, but not statistically significantly (OR (95% CI)=5.3 (0.84-34), p=0.08). Fourteen neonates required resuscitation. The odds of requiring resuscitation were significantly raised with higher log free morphine: OR (95% CI)=9.3 (1.0-86), p=0.05.

CONCLUSION

Concentration of free morphine in the umbilical venous blood after delivery was significantly associated with the dose-delivery interval and this had significant effect on the need for resuscitation.

Does sexual intercourse at term influence the onset of labour? A survey of attitudes of patients and their partners

It is not known if sexual intercourse at term influences the onset of labour, but there are several theoretical reasons why it may. Performing a definitive study to address this issue would pose practical and ethical difficulties. This study therefore sought to assess whether the scientific answer to this issue is of importance to pregnant women and their partners. Women and their partners attending antenatal clinics were asked to complete a questionnaire. Eighty-six per cent of women and 93% of men questioned wished to know if sexual intercourse did influence the onset of labour. If sexual intercourse did influence the onset of labour then a large proportion of those questioned indicated that it would have an effect on sexual activity at term. This study indicates that well-designed studies should be performed to assess whether sexual intercourse at term is implicated in the onset of labour.

Female marmoset monkeys (Callithrix jacchus) can be identified from the chemical composition of their scent marks

The present study analyzed 42 organic solvent extracts of scent mark pools from five dominant female common marmosets by gas chromatography (GC) and combined GC and mass spectrometry. We determined whether there were qualitative or quantitative differences between the chemical composition of scent marks from individual females. Gas chromatography and mass spectral analysis detected the same 162 chemicals in 86% (36/42) of scent mark pools from five dominant females. This near identical chemical composition of scent marks suggested there were few, if any, qualitative differences between the chemical composition of scent marks from individual females. Instead, quantitative differences in scent may provide the key factor distinguishing individual females. Using the relative concentration of highly volatile chemicals detected by GC in scent marks, linear discriminant analysis classified scent mark pools to their correct donor approximately 91% of the time. Such highly reliable statistical matching of scent to donor suggested that each individual female common marmoset has a unique ratio of highly volatile chemicals in their scent marks which may permit individual identification of females from odors in their scent alone.

Induction of labour: a comparison of two methods with particular concern to patient acceptability

Induction of labour is a common obstetric intervention. When the cervix is unfavourable ripening agents are used, commonly prostaglandin E2. There are several methods of administration of prostaglandin E2 and little comparative work has been performed as to their acceptability by patients. Patients undergoing induction of labour by prostaglandin E2 were randomised to receive either intravaginal gel or an intravaginal slow-release pessary. Patient satisfaction with the method received was then assessed. Sixty-nine patients were randomised, 34 to receive gel and 35 to receive a pessary. Median scores for satisfaction of the induction process were the same for both methods; however, satisfaction with the labour was increased with those who had been randomised to the pessary group (median pessary=5, gel=4). There may be a marginal improvement in patient satisfaction when a slow-release intravaginal prostaglandin E2 pessary is used for the induction of labour.

Early report: comparison of breath-hold MR excretory urography, Doppler ultrasound and isotope renography in evaluation of symptomatic hydronephrosis in pregnancy

AIM

To compare assessment by MR excretory urography (MREU), Doppler ultrasound and isotope renography of women with symptomatic hydronephrosis in pregnancy and to define its cause.

MATERIALS AND METHODS

Eleven women at 19-34 weeks of gestation were studied prospectively with gadolinium-enhanced breath-hold gradient echo MREU and transabdominal Doppler ultrasound compared with a 'gold standard' of isotope renography employing frusemide challenge. All studies were performed within 24 h, were reported independently in a blinded fashion and employed clearly defined criteria. Obstetric and infant outcomes were obtained.

RESULTS

There were no adverse reactions to gadolinium administration in pregnancy and no adverse obstetric or infant outcomes. Three of the 11 women were unable to tolerate the complete MREU protocol. Ultrasound indices could not be used to predict ureteric obstruction as shown by isotope renography. MREU agreed with renographic findings in five of the six cases with obstruction and in two without obstruction. MREU directly demonstrated hydronephrosis to result from extrinsic compression of the ureter between the gravid uterus and iliopsoas muscle.

CONCLUSION

MR excretory urography is a promising technique which affords equivalent functional and additional anatomical information to isotope renography. It is more accurate than Doppler ultrasound in the assessment of ureteric obstruction in pregnancy.Spencer, J. A. (2000). Clinical Radiology55, 446-453.

Malignant primary hypertension in pregnancy treated with lisinopril

OBJECTIVE

To report a case of a patient treated with an angiotensin-converting enzyme (ACE) inhibitor with a good neonatal outcome.

CASE REPORT

A 39-year-old African-Caribbean patient who had chronic hypertension presented at 18 weeks' gestation with acute hypertension. She was being treated for chronic hypertension with lisinopril, but had self-discontinued treatment. Attempts to control her hypertension with labetolol, nifedipine, and methyldopa were ineffective. She was therefore offered termination of pregnancy so treatment with lisinopril could be restarted. The patient elected to continue with the pregnancy in spite of the fetal risks associated with the use of an ACE inhibitor. She was delivered of a girl at 26 weeks' gestation. The baby initially had renal failure and also developed acute necrotizing enterocolitis. The renal failure improved simultaneously with the latter complication, and it is postulated that there was enteric excretion of lisinopril. The baby was discharged home on day 102 with no further complications.

DISCUSSION

ACE inhibitors are acceptable medications to use in the first trimester of pregnancy; however, fetal malformations and neonatal complications have been associated with their use later in pregnancy, and they have a perinatal mortality rate of 97/1000. Lisinopril is excreted in urine and feces unchanged, and its half-life is prolonged in anuric neonates. Peritoneal dialysis eliminates lisinopril; however, this neonate improved after treatment for necrotizing enterocolitis and simultaneous improvement in bowel function.

CONCLUSIONS

ACE inhibitors should not be used in pregnancy beyond the end of the first trimester. In exceptional cases, they may be indicated for the control of severe hypertension when the patient is refractory to other medications. The patient should be fully counseled about the adverse effect profile and neonatal outcome. This case report documents a successful outcome for mother and baby in these circumstances.

Interactions of the nuclear matrix-associated steroid receptor binding factor with its DNA binding element in the c-myc gene promoter

Steroid receptor binding factor (RBF) was originally isolated from avian oviduct nuclear matrix. When bound to avian genomic DNA, RBF generates saturable high-affinity binding sites for the avian progesterone receptor (PR). Recent studies have shown that RBF binds to a 54 bp element in the 5'-flanking region of the progesterone-regulated avian c-myc gene, and nuclear matrix-like attachment sites flank the RBF element [Lauber et al. (1997) J. Biol. Chem. 272, 24657-24665]. In this paper, electrophoretic mobility shift assays (EMSAs) and S1 nuclease treatment are used to demonstrate that the RBF-maltose binding protei (MBP) fusion protein binds to single-stranded DNA of its element. Only the N-terminal domain of RBF binds the RBF DNA element as demonstrated by southwestern blot analyses, and by competition EMSAs between RBF-MBP and the N-terminal domain. Mass spectrometric analysis of the C-terminal domain of RBF demonstrates its potential to form noncovalent protein-protein interactions via a potential leucine-isoleucine zipperlike structure, suggesting a homo- and/or possible heterodimer structure in solution. These data support that the nuclear matrix binding site (acceptor site) for PR in the c-myc gene promoter is composed of RBF dimers bound to a specific single-stranded DNA element. The dimers of RBF are generated by C-terminal leucine zipper and the DNA binding occurs at the N-terminal parallel beta-sheet DNA binding motif. This complex is flanked by nuclear matrix attachment sites.

Selective increase in cellular A beta 42 is related to apoptosis but not necrosis

Amyloid beta protein ending at 42 (A beta 42) plays an important role in the pathology of Alzheimer's disease (AD). Here we show an increase in cellular A beta 42 in damaged neurons, with both ELISA and immunocytochemistry. The cellular A beta 42 increase was caused by 3-day treatments with H2O2, etoposide or melphalan, all of which induce genotoxic apoptosis, but not by treatment with sodium azide, which causes necrosis. Secreted A beta was similarly decreased with all these treatments. The cellular A beta 42 increase appeared even with minimal damage (ELISA) and A beta 42-positive cells were TUNEL negative (double staining), indicating that any early apoptosis mechanism may induce the cellular A beta 42 increase. Thus, neuronal apoptosis and cellular A beta 42 increase may be linked in a way that contributes importantly to AD pathology.

Analysis of transcription complexes and effects of ligands by microelectrospray ionization mass spectrometry

The human vitamin D receptor (VDR) and retinoid X receptor-alpha (RXRalpha) modulate gene activity by forming homodimeric or heterodimeric complexes with specific DNA sequences and interaction with other elements of the transcriptional apparatus in the presence of their known endogenous ligands 1alpha,25-dihydroxyvitamin D3 (1, 25-[OH]2D3) and 9-cis-retinoic acid (9-c-RA). We used rapid buffer exchange gel filtration in conjunction with microelectrospray ionization mass spectrometry (microESI-MS) to study the binding of these receptors to the osteopontin vitamin D response element (OP VDRE). In the absence of DNA, both VDR and RXRalpha existed primarily as monomers, but in the presence of OP VDRE, homodimeric RXRalpha and heterodimeric RXRalpha-VDR complexes were shown to bind OP VDRE. Addition of 9-c-RA increased RXRalpha homodimer-OP VDRE complexes, and addition of 1,25-(OH) 2D3 resulted in formation of 1, 25-(OH)2D 3-VDR-RXRalpha-OP VDRE complexes. Addition of low-affinity binding ligands had no detectable effect on the VDR-RXRalpha-OP VDRE transcription complex. These results demonstrate the utility of microESI-MS in analyzing multimeric, high-molecular-weight protein-protein and protein-DNA complexes, and the effects of ligands on these transcriptional complexes.

Naturally processed and presented epitopes of the islet cell autoantigen IA-2 eluted from HLA-DR4

During immune responses, antigen-presenting cells (APCs) process antigens and present peptide epitopes complexed with human leukocyte antigen (HLA) molecules. CD4 cells recognize these naturally processed and presented epitopes (NPPEs) bound to HLA class II molecules. Epitope identification is important for developing diagnostic and therapeutic tools for immune-mediated diseases and providing insight into their etiology, but current approaches overlook effects of natural processing on epitope selection. We have developed a technique to identify NPPEs using mass spectrometry (MS) after antigen is targeted onto APCs using a lectin-based antigen delivery system (ADS). We applied the technique to identify NPPEs of the intracellular domain of the type 1 diabetes mellitus-associated (type 1 DM-associated) autoantigen insulinoma-associated-2 (IA-2ic), presented by HLA-DR4 (0401). IA-2ic-derived NPPEs eluted from HLA-DR4 constitute 6 sets of peptides nested around distinct core regions. Synthetic peptides based on these regions bind HLA-DR4 and elicit primary T-cell proliferation frequently in HLA-DR4-positive type 1 DM patients, but rarely in non-HLA-DR4 patients, and in none of the HLA-DR4 nondiabetic controls we tested. This flexible, direct approach identifies an HLA allele-specific map of NPPEs for any antigen, presented by any HLA class II molecule. This method should enable a greater understanding of epitope selection and lead to the generation of sensitive and specific reagents for detecting autoreactive T cells.

The influence of donated gametes on the incidence of hypertensive disorders of pregnancy

Pregnancies achieved from oocyte, sperm or embryo donation are unique, since they have resulted from donor gametes that are immunologically foreign to the mother. Thus, studying the obstetric outcome of such pregnancies may shed some light on the pathophysiology of preeclampsia, particularly in women conceiving with donated embryos, since the entire fetal genome is allogenic in these pregnancies. In this retrospective cohort study, a total of 144 women were studied. Of these, 72 were infertility patients who had conceived as a result of sperm, ovum or embryo donation and the other 72 women were age- and parity-matched control patients who became pregnant with their own gametes, either spontaneously, or following intrauterine insemination with their partner's spermatozoa. Study patients were divided into three groups depending on the origin of the donated gametes. Group 1 consisted of pregnancies achieved by intrauterine insemination with washed donor spermatozoa (n = 33). Group 2 included women who conceived using donated oocytes (n = 27) and group 3 consisted of women who conceived as a result of embryo donation (n = 12). The incidence of pregnancy-induced hypertension in the donated gametes study group was 12.5% (9/72) compared with 2.8% (2/72) in the control group. In addition, pre-eclampsia was diagnosed in 18.1% (13/72) of the donated gametes study group compared to 1.4% (1/72) in the age- and parity-matched controls. The increased incidence of gestational hypertension in pregnancies resulting from donated gametes gives evidence for a maternal genetic component, with an equally strong fetal influence, in the complicated aetiology of gestational hypertension, and pre-eclampsia in particular.

On-line sample clean-up and chromatography coupled with electrospray ionization mass spectrometry to characterize the primary sequence and disulfide bond content of recombinant calcium binding proteins

We have used on-line sample clean-up, concentration, and chromatography with electrospray ionization mass spectrometry (ESI-MS), to characterize and determine the presence of disulfide bonds in recombinant full-length rat brain calbindin D28K and two deletion mutants of the protein, one lacking EF-hand 2 (calbindin delta 2) and the other lacking EF-hands 2 and 6 (calbindin delta 2,6). The molecular weights of the expressed proteins dissolved in biological buffers were determined with high accuracy using a low-flow, pressurized chamber infusion system, that allows on-line protein clean-up by removing buffers/salts incompatible with ESI-MS. The molecular weight determinations showed that the amino-terminal methionine residues had been cleaved during the expression and isolation of the recombinant proteins. Approximately 85-90% of the protein sequences were confirmed by on-line HPLC-ESI-MS analysis of peptides generated by a lysyl endoproteinase C digestion. Comparisons of ESI-MS spectra of native and reduced calbindin D28K and delta 2 show that the full length- and delta 2 mutant-protein contain one disulfide bond. Molecular mass determinations of calbindin delta 2,6 showed that this protein contains a highly active cysteine residue that covalently binds a mercaptoethanol group, or forms a homodimer via a disulfide bond. The results show surprising differences amongst the deletion mutants of calbindin D28K with respect to the formation of disulfide bonds. These differences are not readily detected by other techniques and show that ESI-MS is a powerful, rapid method by which to detect disulfide linkages for intact proteins.

On-line HPLC-tandem mass spectrometry structural characterization of case-associated contaminants of L-tryptophan implicated with the onset of eosinophilia myalgia syndrome

The eosinophilia-myalgia syndrome (EMS) outbreak that occurred in the USA in 1989 was caused by the intake of L-tryptophan (Trp) produced from one manufacturer, Showa Denko K.K. of Japan. Six compounds present in the Trp were reported to be case-associated contaminants. However, three of these compounds, Peaks C, FF and AAA have remained unidentified. Here, we successfully employ on-line HPLC-electrospray ionization multistage mass spectrometry to structurally characterize Peak C and Peak FF. Peak C was determined by accurate mass-LC-MS to have a protonated molecular ion MH+ = 221.0919 with an empirical formula of C11H13N2O3. By comparing the LC-MS-MS spectra with authentic 5-OHTrp and other structurally similar compounds, as well as considering the chemical reactivity of the indole ring, the structure of Peak C was consistent with 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2,3-b]-indole-2-carboxy lic acid. Peak FF was also subjected to accurate mass-LC-MS and shown to have MH+ = 338.1524, corresponding to an empirical formula of C19H20N3O3. Comparison of the LC-MS-MS and LC-sCID-MS-MS of spectra derived from Peak FF with a previously characterized contaminant of Trp, namely P31, was consistent with Peak FF being 2-(2-hydroxy indoline)-Trp. Unlike the majority of the contaminants identified in EMS implicated tryptophan, both Peaks C and FF possess an indoline ring. This is significant since a case-associated contaminant found in 5-hydroxy-Trp also contains an indoline ring, and the chemical reactivity of this ring system may possibly play a role in the etiology of EMS.

Comparison of protein mixtures in aqueous humor by membrane preconcentration - capillary electrophoresis - mass spectrometry

The significance of proteomic research is coupled with the recent exponential growth of these investigations. Currently, the most popular techniques used for these studies include the coupling of 1- and 2-dimensional electrophoresis with mass spectrometric analysis of the extracted and digested proteins. However, detection limits of gel staining methods have led to a search for complimentary techniques that afford the detection of lower concentrations of biologically relevant proteins. In the present studies, we have evaluated the applicability of on-line capillary electrophoresis - mass spectrometry (CE-MS) for this application. Specifically, we used membrane preconcentration-CE-MS (mPC-CE-MS) to analyze 13 samples of human aqueous humor (AH) from patients with various ocular pathologies (cataract, cataract plus glaucoma, and cataract plus pseudoexfoliation syndrome). This approach enabled rapid analysis of a relatively large volume (1 microL of each specimen, and a protein map for each was created. Measured average molecular weights (Mr) were used to tentatively identify proteins after search of the SWISS-PROT database using TagIdent from ExPaSy. Among those proteins tentatively identified are beta-2 microglobulin (Mr 11731.2), apolipoprotein A1 (Mr 28078.6) and serum albumin (Mr 66400). Proteins with Mr of 4349 (unidentified), 11731.2 (beta-2 microglobulin), 13400-14100 (immunoglobulin fragments), 28078.2 (apolipoprotein A1) and approximately 68000 (serum albumin) were observed in the majority of specimens. Generally no significant differences were noted in the protein composition of aqueous humor samples from different pathologies. However, the absence of an Mr 13345 protein and its oxidized form (Mr 13361) in samples from patients with pseudoexfoliation syndrome was noted. Occasionally the alpha-and beta-chains of hemoglobin, a contaminant in aqueous humor introduced during sampling, were also detected. We conclude from these studies that mPC-CE-MS is an attractive complimentary technique for proteome research, as this approach enables direct mapping and characterization of low concentrations of proteins that are present in complex physiologically derived fluids.

Enhanced sensitivity for sequence determination of major histocompatibility complex class I peptides by membrane preconcentration-capillary electrophoresis-microspray-tandem mass spectrometry

Sequence analysis of antigenic major histocompatibility complex (MHC) class I peptides requires minimizing sample loss and enhancing mass spectrometric sensitivity. In order to facilitate such analyses, we have coupled on-line membrane preconcentration-capillary electrophoresis (mPC-CE) with microspray mass spectrometry (mPC-CE-microMS) and tandem mass spectrometry (mPC-CE-microMS/MS). Specifically, cell lysate from approximately 10(9) EG-7 mouse tumor cells was immunoprecipitated and the released MHC class I peptides were subjected to reverse-phase HPLC. An HPLC fraction containing antigenic peptide(s) shown to induce T-cell stimulation was subjected to mPC-CE-microMS. Approximately 10 microL (from 100 microL) of the fraction was pressure-injected and concentrated on a styrenedivinylbenzene (SDB) impregnated membrane. The peptides were eluted from the membrane with approximately 100 nL of 80% methanol, sandwiched between a leading stacking buffer (LSB, also serving as CE separation medium) of approximately 110 nL of 0.1% acetic acid in 10% methanol, and a trailing stacking buffer (TSB) of approximately 110 nL of 0.1% NH4OH. On application of the CE voltage the peptides are subjected to moving boundary transient isotachophoresis and focused. The peptides were separated in a Polybrene-coated capillary with application of -20 kV in reverse polarity mode and subsequently sprayed via an emitter coupled to the CE capillary by a liquid junction containing a platinum wire. An ion at m/z 482.3 was detected and subjected to mPC-CE-microMS/MS and determined to be SIINFEKL, a peptide (OVA) known to be antigenic in the mouse model system. Sensitivity enhancement over conventional mPC-CE-MS and MS/MS was approximately 100-fold.

Rapid HPLC screening method for contaminants found in implicated L-tryptophan associated with eosinophilia myalgia syndrome and adulterated rapeseed oil associated with toxic oil syndrome

In 1981 a massive food-borne epidemic, termed the toxic oil syndrome (TOS), occurred in Spain. Eight years later a closely related disease, the eosinophilia myalgia syndrome (EMS), was reported in the USA with many additional cases being reported worldwide. Although EMS was linked to the ingestion of contaminated L-tryptophan and TOS to aniline denatured rapeseed oil, the etiological agent(s) responsible for both diseases remains unknown. However, contaminants in both the oil and the dietary supplement are believed to have triggered these diseases, and there has been much speculation that a common contaminant may have caused both epidemics. In this report, methods for the facile preparation and HPLC analysis of EMS-implicated L-tryptophan and adulterated rapeseed oil samples associated with TOS are described which allow a direct comparison between the contaminants of both foodstuffs. A combination of solvent and solid phase extraction methods are demonstrated along with the application of C18 reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with on-line UV and MS detection. These methods have allowed us to determine for the first time, based upon this work, that there are no detectable common contaminants that possess a UV response, between EMS implicated L-tryptophan and TOS implicated rapeseed oil samples.

Protein analysis by membrane preconcentration-capillary electrophoresis: systematic evaluation of parameters affecting preconcentration and separation

Fast and efficient analysis of proteins in physiological fluids is of great interest to researchers and clinicians alike. Capillary electrophoresis (CE) has proven to be a potentially valuable tool for the separation of proteins in specimens. However, a generally acknowledged drawback of this technique is the limited sample volumes which can be loaded onto the CE capillary which results in a poor concentration limit of detection. In addition, matrix components in samples may also interfere with separation and detection of analytes. Membrane preconcentration-CE (mPC-CE) has proved to be effective in overcoming these problems. In this report, we describe the systematic evaluation of parameters affecting on-line preconcentration/clean-up and separation of protein mixtures by mPC-CE. Method development was carried out with a standard mixture of proteins (lysozyme, myoglobin, carbonic anhydrase, and human serum albumin). First, using MALDI-TOF-MS, membrane materials with cation-exchange (R-SO3H) or hydrophobic (C2, C8, C18, SDB) characteristics were evaluated for their potential to retain proteins in mPC cartridges. Hydrophobic membranes were found most suitable for this application. Next, all mPC-CE analysis of protein samples were performed in polybrene coated capillaries and parameters affecting sample loading, washing and elution, such as the composition and volume of the elution solvent were investigated. Furthermore, to achieve optimal mPC-CE performance for the separation of protein mixtures parameters affecting postelution focusing and electrophoresis, including the composition of the background electrolyte and a trailing stacking buffer were varied. Optimal conditions for mPC-CE analysis of proteins using a C2 impregnated membrane preconcentration (mPC) cartridge were achieved with a background electrolyte of 5% acetic acid and 2 mM ammonium acetate, 60 nl of 80% acetonitrile in H2O as an elution solvent, and 60 nl of 0.5% ammonium hydroxide as a trailing stacking buffer. The developed method was used successfully to separate proteins in aqueous humor, which contains numerous proteins in a complex matrix of salts.

Detection and quantitation of cellularly derived amyloid beta peptides by immunoprecipitation-HPLC-MS

A quantitative method for detection of amyloid beta peptides using immunoprecipitation-HPLC-mass spectrometry (IP-LC-MS) is described. Comparison of IP-LC-MS with sandwich ELISA revealed comparable results in the analysis of A beta 1-40 and A beta 1-42 derived from fetal guinea pig cell media and cell lysates. The use of IP-LC-MS not only allows a quantitative method for A beta 1-40 and A beta 1-42 peptides present in Alzheimer's disease (AD), but allows detection of other A beta peptide species that may also play a role in the onset of AD in humans.

Low temperature aqueous electrospray ionization mass spectrometry of noncovalent complexes

In the present study we describe conditions that permit the characterization of noncovalent protein-substrate complexes in aqueous solution by microspray electrospray ionization-mass spectrometry (ESI-MS), using a heated transfer capillary at low temperature (45 degrees C). Specifically, we examined the binding of calmodulin to two polypeptides; the calmodulin-binding domain of calmodulin-dependent protein kinase II (CamK-II) and melittin. Calmodulin, a well known calcium-binding protein, binds to a number of small amphipathic peptides in a calcium-dependent manner. Our results directly show that both peptides form equimolar complexes with calmodulin only in the presence of calcium. The stoichiometry necessary for the formation of each complex was 1:1:4 for calmodulin:peptide (melittin or CamK-II):Ca2+, respectively. Furthermore, it is demonstrated that the detection of the complex in ESI-MS is source temperature dependent.

A randomised controlled trial of antibiotic prophylaxis for vesico-vaginal fistula repair

OBJECTIVE

To test the hypothesis that intravenous antibiotics given intra-operatively reduce the failure rate of vesico-vaginal fistula repair.

DESIGN

A single blind, randomised controlled trial.

SETTING

A district hospital in Benin, West Africa.

POPULATION

Seventy-nine women undergoing repair of an obstetric vesico-vaginal fistula by a single surgeon at Hopital Evangelique; two women had repeat operations.

METHODS

Participants in the treatment group (n = 41) received ampicillin 500 mg intra-operatively. Controls (n = 40) received no prophylactic antibiotics.

MAIN OUTCOME MEASURES

Failure of fistula closure and objective incontinence (a positive pad test) at hospital discharge. Secondary outcomes included febrile morbidity, other antibiotic use and urinary infection.

RESULTS

Antibiotic prophylaxis did not reduce the odds of failed repair (OR 2.1 95% CI 0.75-6.1) or of objective incontinence (OR 1.9; 95% CI 0.72-5.1). The women in the antibiotic prophylaxis group received less post-operative antibiotics and had less urinary infections at day 10.

CONCLUSIONS

Prophylactic antibiotics should not be used in vesico-vaginal fistulae repair in the developing world outside randomised controlled trials.

Structural characterization of contaminants found in commercial preparations of melatonin: similarities to case-related compounds from L-tryptophan associated with eosinophilia-myalgia syndrome

On-line HPLC/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) in conjunction with NMR has been successfully employed to identify and structurally characterize seven contaminants found in three different commercial preparations of melatonin. Six of these contaminants were identified as analogues of impurities found in contaminated L-tryptophan (an over-the-counter dietary supplement) associated with the eosinophilia-myalgia syndrome (EMS) epidemic that occurred in the United States during 1989. In particular, our studies identified two compounds with MH+ = 249 to be hydroxymelatonin isomers. Four other compounds with MH+ = 477 were identified as melatonin-formaldehyde condensation products. These compounds are structural analogues of L-tryptophan contaminants, namely, 'peak C' and 'peak E' that were previously implicated as etiological agents causing EMS. It has been reported that melatonin consumption has resulted in eosinophilia in some humans taking high doses of this supplement. Although there has not been a major outbreak of EMS-like symptoms from consumption of melatonin, this study clearly suggests that tighter control and regulation of nutritional supplements sold and used as drugs is necessary.

Metal mediated sterol receptor-DNA complex association and dissociation determined by electrospray ionization mass spectrometry

The vitamin D receptor (VDR) binds to specific DNA sequences termed vitamin D response elements (VDREs) thereby enhancing or repressing transcription. We have used electrospray ionization mass spectrometry to examine the interaction between the DNA-binding domain of the vitamin D receptor (VDR DBD) with a double-stranded DNA (dsDNA) sequence containing the VDRE from the mouse osteopontin gene. The VDR DBD was shown to bind to the appropriate DNA sequence only when bound to 2 moles of zinc (Zn2+) or cadmium (Cd2+) per mole of protein. Additional binding of Zn2+ or Cd2+ by the protein caused the protein to dissociate from the dsDNA. These results show that the VDR DBD/DNA metal-dependent association occurs when the receptor is occupied by 2 moles of Zn2+ per mole of protein and that further binding of Zn2+ to the protein causes dissociation of the complex.

One step microelectroelution concentration method for efficient coupling of sodium dodecylsulfate gel electrophoresis and matrix-assisted laser desorption time-of-flight mass spectrometry for protein analysis

The coupling of the widely used separation technique of conventional sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) with the mass accuracy measurement capability of mass spectrometry (MS) provides a very powerful analytical technique. However, at present, there is no simple, definitive method for coupling the two methods. Typically, separated proteins are extracted from the gel, either as the native protein or as a peptide mixture after in-gel proteolytic digestion, and then analyzed by mass spectrometry. However, the various extraction techniques described previously have been labor intensive and require a large number of steps. The mass spectrometry analysis of very low concentrations of in vivo derived proteins requires minimum sample handling and on-line concentration. Therefore, we have developed an efficient microelectroelution technique that is applied in a single step manner and contains an on-line concentration device. Initial results from this system have shown a high efficiency of analyte elution from the gel and a simple, robust technique for the coupling of SDS-containing gels with MALDI-TOF-MS analysis and a capability of analyzing proteins at the subpicomole level.

Zinc-induced conformational changes in the DNA-binding domain of the vitamin D receptor determined by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was used to measure conformational changes within the DNA-binding domain of the vitamin D receptor (VDR DBD) upon binding zinc (Zn2+). As increasing concentrations of Zn2+ were added to the VDR DBD, a gradual shift in the mass envelope to lower charge states was observed in the multiply charged spectrum. The shift in the charge states was correlated to changes observed in the far-ultraviolet circular dichroic (far-UV CD) spectrum of the protein as it was titrated with Zn2+. Both the multiply charged ESI and far-UV CD spectra of the Zn(2+)-titrated protein show that the binding of the first Zn2+ ion to the protein results in very little conformational change in the protein. The binding of a second Zn2+ ion resulted in a significant alteration in the structure of the protein as indicated by changes in both the multiply charged ESI and far-UV CD spectra. Much smaller changes were seen within the multiply charged ESI or far-UV CD spectra upon increasing the Zn2+ concentration beyond 2 mol/mol of protein. The results presented indicate that ESI-MS in combination with CD is a powerful method to measure gross conformational changes induced by the binding of metals to metalloproteins.

Inhibition of human mitochondrial aldehyde dehydrogenase by the disulfiram metabolite S-methyl-N,N-diethylthiocarbamoyl sulfoxide: structural characterization of the enzyme adduct by HPLC-tandem mass spectrometry

S-Methyl-N,N-diethylthiocarbamoyl sulfoxide (MeDTC-SO) is a known metabolite of the aversion therapy drug disulfiram (DSF). MeDTC-SO is also a potent inhibitor of human mitochondrial aldehyde dehydrogenase (hmALDH) with an IC50 of 1.5 microM. Inhibition of the enzyme by MeDTC-SO resulted in the addition of approximately 100 Da to the molecular mass of the intact protein, as determined by on-line HPLC-electrospray ionization MS (LC-MS). Dialysis of the inhibited protein did not reverse the inhibition, and the molecular mass of 54,533 Da (+/- 0.01%) remained unchanged, indicating that a covalent modification of the protein had occurred. Proteolytic digestion of hmALDH under basic conditions using trypsin at pH 7.8 revealed that the adduct was base labile. However, treating the adducted protein with endopeptidase-Glu-C at pH 3.7 produced a peptide adduct at MH+ = 4924, tentatively attributable to a carbamoylated peptide. This peptide contains three adjacent cysteines, one of which has been implicated as a key amino acid in the highly conserved active site region of ALDH. A pepsin digestion of hmALDH carried out at pH 3.7 and subsequent LC-MS analysis revealed an ion at MH2(2+) = 501.5, corresponding to the carbamoylated peptide FNQGQC1C2C3. This peptide contains the same adjacent active site cysteines. This latter peptide was subjected to LC-MS/MS, which enabled us to determine that the site of carbamoylation was at Cys2. The MS/MS product ion data also confirmed the presence of a carbamoyl group as the adduct species.

New approaches in clinical chemistry: on-line analyte concentration and microreaction capillary electrophoresis for the determination of drugs, metabolic intermediates, and biopolymers in biological fluids

The use of capillary electrophoresis (CE) for clinically relevant assays is attractive since it often presents many advantages over contemporary methods. The small-diameter tubing that holds the separation medium has led to the development of multicapillary instruments, and simultaneous sample analysis. Furthermore, CE is compatible with a wide range of detectors, including UV-Vis, fluorescence, laser-induced fluorescence, electrochemistry, mass spectrometry, radiometric, and more recently nuclear magnetic resonance, and laser-induced circular dichroism systems. Selection of an appropriate detector can yield highly specific analyte detection with good mass sensitivity. Another attractive feature of CE is the low consumption of sample and reagents. However, it is paradoxical that this advantage also leads to severe limitation, namely poor concentration sensitivity. Often high analyte concentrations are required in order to have injection of sufficient material for detection. In this regard, a series of devices that are broadly termed 'analyte concentrators' have been developed for analyte preconcentration on-line with the CE capillary. These devices have been used primarily for non-specific analyte preconcentration using packing material of the C18 type. Alternatively, the use of very specific antibody-containing cartridges and enzyme-immobilized microreactors have been demonstrated. In the current report, we review the likely impact of the technology of capillary electrophoresis and the role of the CE analyte concentrator-microreactor on the analysis of biomolecules, present on complex matrices, in a clinical laboratory. Specific examples of the direct analysis of physiologically-derived fluids and microdialysates are presented, and a personal view of the future of CE in the clinical environment is given.

Recombinant Mycobacterium tuberculosis KatG(S315T) is a competent catalase-peroxidase with reduced activity toward isoniazid

The presence of KatG(S315T), a mutation frequently detected in clinical isolates of Mycobacterium tuberculosis, has been associated with loss of catalase-peroxidase activity and resistance to isoniazid therapy. Wild-type KatG and KatG(S315T) were expressed in a heterologous host (Escherichia coli) and purified to homogeneity, and enzymatic activity was measured. The catalase activity for KatG(S315T) was reduced 6-fold, and its peroxidase activity was decreased <2-fold, compared with the activities for wild-type KatG. Pyridine hemochrome analysis demonstrated 1.1 +/- 0.1 hemes/subunit for wild-type KatG and 0.9 +/- 0.1 hemes/subunit for KatG(S315T), indicating that the difference in enzymatic activity is not the result of incomplete heme cofactor incorporation in KatG(S315T). High-performance liquid chromatography analysis showed that wild-type KatG was more efficient than KatG(S315T) at converting isoniazid to isonicotinic acid. These results demonstrate that KatG(S315T), as expressed in E. coli, is a competent catalase-peroxidase that exhibits a reduced ability to metabolize isoniazid.

Zinc binding properties of the DNA binding domain of the 1,25-dihydroxyvitamin D3 receptor

To assess the zinc binding stoichiometry and the structural changes induced upon the binding of zinc to the human vitamin D receptor (VDR), we expressed the DNA binding domain (DBD) of the human VDR in bacteria as a soluble glutathione-S-transferase fusion protein at 20 degrees C, and examined the apo-protein and metal-liganded protein by mass spectrometry, and circular dichroism and nuclear magnetic resonance spectroscopy. Following final preparation with a zinc-free buffer, the VDR DBD bound 2 mol of zinc/mol of protein as measured by inductively coupled plasma-mass spectrometry and electrospray ionization-mass spectrometry. When protein preparation was carried out in a zinc containing buffer and zinc content of the protein was assesed by the same methods, VDR DBD bound 4 mol of zinc/mol of protein. Analysis of the protein using circular dichroism spectroscopy demonstrated that the EDTA-treated protein increased in alpha-helical content from 16 to 27% on the addition of zinc. Equilibrium ultracentrifugal analyses of the VDR DBD indicated that the protein was present in solution as a monomer. Gel mobility shift analyses of the VDR DBD with several vitamin D response elements (VDREs) in the absence of accessory proteins such as retinoic acid receptor, showed that VDR DBD was able to form a protein/VDRE DNA structural complex. In the presence of zinc, proton NMR NOESY spectra showed that the protein possessed elements of secondary structure. The addition of VDRE DNA, but not random DNA, caused changes in the proton NMR spectra of VDRE DNA indicating specific interaction between protein and DNA groups. We conclude that the DBD of the VDR binds zinc and DNA and undergoes conformational changes on binding to the metal and DNA.

On-line HPLC-tandem mass spectrometry analysis of contaminants of L-tryptophan associated with the onset of the eosinophilia-myalgia syndrome

The structural characterization of a number of contaminants of L-tryptophan (Trp) associated with eosinophilia myalgia syndrome has been performed for the first time by the powerful structural elucidation technique of tandem mass spectrometry coupled with on-line HPLC (LC-ESI-MS/MS). The identity of the contaminants: peaks UV-5, 3-(phenylamino)alanine, (PAA); E 1,1'-ethylidenebis(tryptophan); 200, 2-(3-indolylmethyl)-L-tryptophan; (all identified as case related) and peaks 1, 3-carboxy-1,2,3,4-tetrahydro-beta-carboline; 2, 3-carboxy-1-methyl-1,2,3,4-tetrahydro-beta-carboline; 100, 2-(2,3 dihydroxy-1-[3-indolyl]propyl)-L-tryptophan; and 300 and 400, diastereomers of 3-carboxy-1-[3-indolyl-methyl]-1,2,3,4-tetrahydro-beta-carboline, have been confirmed by this technique. By comparison of tandem MS (MS/MS) data from these compounds with the MS/MS data of several other impurities, we have structurally characterized peaks CC, KK and OO, as well as two previously unreported components labeled as peak P18 and peak P31. Peak P18 was unresolved from the large Trp peak and has been characterized as indole-3-ethylamine. Peak P31 was previously unresolved from peak 200, a case related compound and therefore its structure is of extreme importance. This compound has been tentatively identified as 2-(3-indolyl)-L-tryptophan.

Capillary isoelectric focusing of physiologically derived proteins with on-line desalting of isotonic salt concentrations

Capillary isoelectric focusing within capillaries (cIEF) is a powerful and practical method for high-resolution separation of components within complex biological mixtures. However, a major problem has always existed; separation performance is usually degraded by the presence of salts within the sample. Normally this requires the removal of these components by some off-line sample cleanup method, prior to analyte separation by cIEF. In this study, we have shown it is possible to efficiently remove high salt levels from samples by on-line voltage ramping of the applied CE voltage. To allow this technique to be used effectively, a customized version of an existing method to internally coat a fused-silica capillary has been developed and examined for interexperimental reproducibility. We describe the systematic examination of the desalting process and its optimization through the use of model protein systems. Furthermore, we demonstrate the automated application of this on-line desalting cIEF scheme to studies of whole human blood and human cerebrospinal fluid which have undergone no manipulation or work up prior to cIEF analysis.

Identification of a naturally occurring ligand for thymic positive selection

In the thymus, positive and negative selection shape the T cell repertoire. It has previously been shown that positive selection, like negative selection, is the result of the interaction of the TCR with self-peptides bound to MHC. However, little is known about the number or nature of the self-peptide ligands that mediate positive selection in vivo. We devised a novel assay with enhanced sensitivity for low affinity TCR ligands to identify self-peptides that may be biologically relevant. At least eight K(b)-bound self-peptides were detected by this assay using thymocytes bearing the OT-I TCR (specific for OVAp/K(b)). The sequence of one of these peptides was determined using the recently developed technique of membrane preconcentration-capillary electrophoresis-tandem mass spectrometry. This peptide, CP alpha1, has limited sequence similarity to OVAp, yet was found to induce positive selection of OT-I thymocytes in fetal thymic organ culture.