A gas phase fractionation acquisition scheme integrating ion mobility for rapid diaPASEF library generation

Data independent acquisition (DIA/SWATH) MS is a primary strategy in quantitative proteomics. diaPASEF is a recent adaptation using trapped ion mobility spectrometry (TIMS) to improve selectivity/sensitivity. Complex DIA spectra are typically analyzed with reference to spectral libraries. The best-established method for generating libraries uses offline fractionation to increase depth of coverage. More recently strategies for spectral library generation based on gas phase fractionation (GPF), where a representative sample is injected serially using narrow DIA windows that cover different mass ranges of the complete precursor space, have been introduced that performed comparably to deep offline fractionation-based libraries. We investigated whether an analogous GPF-based approach that accounts for the ion mobility (IM) dimension is useful for the analysis of diaPASEF data. We developed a rapid library generation approach using an IM-GPF acquisition scheme in the m/z versus 1/K0 space requiring seven injections of a representative sample and compared this with libraries generated by direct deconvolution-based analysis of diaPASEF data or by deep offline fractionation. We found that library generation by IM-GPF outperformed direct library generation from diaPASEF and had performance approaching that of the deep library. This establishes the IM-GPF scheme as a pragmatic approach to rapid library generation for analysis of diaPASEF data.

Benzamil sensitive ion channels contribute to volume regulation in canine chondrocytes

BACKGROUND AND PURPOSE

Chondrocytes exist within cartilage and serve to maintain the extracellular matrix. It has been postulated that osteoarthritic (OA) chondrocytes lose the ability to regulate their volume, affecting extracellular matrix production. In previous studies, we identified expression of epithelial sodium channels (ENaC) in human chondrocytes, but their function remained unknown. Although ENaC typically has Na(+) transport roles, it is also involved in the cell volume regulation of rat hepatocytes. ENaC is a member of the degenerin (Deg) family, and ENaC/Deg-like channels have a low conductance and high sensitivity to benzamil. In this study, we investigated whether canine chondrocytes express functional ENaC/Deg-like ion channels and, if so, what their function may be.

EXPERIMENTAL APPROACH

Canine chondrocytes were harvested from dogs killed for unassociated welfare reasons. We used immunohistochemistry and patch-clamp electrophysiology to investigate ENaC expression and video microscopy to analyse the effects of pharmacological inhibition of ENaC/Deg on cell volume regulation.

KEY RESULTS

Immunofluorescence showed that canine chondrocytes expressed ENaC protein. Single-channel recordings demonstrated expression of a benzamil-sensitive Na(+) conductance (9 pS), and whole-cell experiments show this to be approximately 1.5 nS per cell with high selectivity for Na(+) . Benzamil hyperpolarized chondrocytes by approximately 8 mV with a pD2 8.4. Chondrocyte regulatory volume decrease (RVI) was inhibited by benzamil (pD2 7.5) but persisted when extracellular Na(+) ions were replaced by Li(+) .

CONCLUSION AND IMPLICATIONS

Our data suggest that benzamil inhibits RVI by reducing the influx of Na(+) ions through ENaC/Deg-like ion channels and present ENaC/Deg as a possible target for pharmacological modulation of chondrocyte volume.

Evaluation of a new cataract surgery referral pathway

AIMS

To compare the quality of referrals and listing rates of direct optometric referrals vs traditional GP referrals for cataract surgery.

METHODS

A retrospective cohort of 124 patients referred for cataract surgery was identified (62 via optometric pathway and 62 via GP pathway). The quality of the referral was assessed by establishing if it contained adequate information relating to the College of Optometrists' referral framework document. Age, sex, drug history, listing rate, operative rate, and visual acuity (best corrected) at referral and at the postoperative visit were recorded and compared between the two referral pathways using the Fisher's exact test.

RESULTS

Optometric referrals, relative to GP referrals, were more likely to include information relating to objective visual loss (100 vs 87%, P=0.0061) and to counsel the patient (97 vs 18%, P=0.0001). GP referrals, relative to optometric referrals, were more likely to comment on personal circumstances (32 vs 3%, P=0.0001), past medical history (95 vs 68%, P=0.0001), and drug history (94 vs 69%, P=0.0009). Operative rates were higher for the optometric direct referrals relative to GP referrals (87 vs 69%, P=0.0284). There was no difference in the visual acuity before or after surgery between the pathways.

CONCLUSIONS

Optometric direct cataract referrals provide better information on objectively measured vision and better delivery of preoperative counselling. Traditional GP referrals contain better medical history, drug information, and details of personal circumstances. Rates of surgery were slightly higher with optometric referrals.

Influence of sphingomyelin and TNF-α release on lethality and local inflammatory reaction induced by Loxosceles gaucho spider venom in mice

It is well known that Loxosceles venom induces local dermonecrosis in rabbits, guinea pigs and humans but not in mice, although, depending on the dose, Loxosceles venom can be lethal to mice. In this work we demonstrate that mice injected intradermally in the dorsal area of the back can survive a lethal dose of Loxosceles gaucho venom and also develop an inflammatory reaction (with infiltration of leukocytes shown by histological analysis) at the local injection site when the venom is co-administered with sphingomyelin. It was observed that more venom was retained for a longer period of time at the local injection site when venom was co-administered with sphingomyelin. The presence of exogenous sphingomyelin did not influence significantly the release of TNF-alpha induced by L. gaucho venom. These results suggest that the action of venom on sphingomyelin, producing ceramide phosphate, causes the development of an inflammatory reaction, which in turn traps the venom in the local area for a long period of time and does not allow it to disperse systemically in a dose sufficient to cause death. Our findings also indicate that the size and availability of the local sphingomyelin pool may be important in determining the outcome of Loxosceles envenoming in different mammalian species.

Effect of Loxosceles gaucho venom on cell morphology and behaviour in vitro in the presence and absence of sphingomyelin

This study was performed to investigate whether the toxic effects of Loxosceles gaucho venom on cells might be exerted via stimulators of TNF-alpha release generated by sphingomyelinase D--a major component of the venom. It was demonstrated that L. gaucho venom alone is unable to induce TNF-alpha release by J774A.1 cells, while in the presence of exogenous sphingomyelin it induces a high level of TNF-alpha release which is significantly increased by incubation with non-inactivated serum. Ceramide phosphate also induces TNF-alpha release in J774A.1 cells, but (unlike sphingomyelin/sphingomyelinase) the level of release is not influenced by the presence or otherwise of non-inactivated serum. L. gaucho venom does not induce proliferation of J774A.1 cells and even at high concentrations it does not affect their viability. J774A.1 cells, which prior to venom treatment were elongated and clumped, round up after venom treatment, but, revert to their original morphology after incubation with fresh medium. TNF-alpha resistant MRC-5 cells and TNF-alpha sensitive MCF-7 cells are susceptible to the toxic effect of both L. gaucho venom and ceramide phosphate. The results obtained in this study demonstrate that exogenous sphingomyelin can modulate, in vitro, the release of TNF-alpha induced by L. gaucho venom in mouse macrophages. In addition, the results also indicate that ceramide phosphate and L. gaucho venom are toxic to several different cell types, via a variety of mechanisms, some, but not all, of which may involve TNF-alpha as an intermediary.

The influence of surface modification on the cytotoxicity of PAMAM dendrimers

The influence of surface modification on the cytotoxicity of PAMAM dendrimers was examined using Caco-2 cells. Dendrimers were modified by conjugating either lauroyl chains or polyethylene glycol (PEG) 2000 onto the surface of cationic PAMAM dendrimers (G2, G3, G4). The cytotoxicity of unmodified dendrimers towards Caco-2 cells was appreciably higher for cationic (whole generation) compared with anionic (half generation) dendrimers and for both types increased with increasing size (generation) and concentration. A marked decrease in the cytotoxicity of cationic PAMAM dendrimers was noted when the surface was modified, with the addition of six lauroyl or four PEG chains being particularly effective in decreasing cytotoxicity. This decrease in cytotoxicity is thought to be due to a reduction/shielding of the positive charge on the dendrimer surface by the attached chains. The cytotoxicity of dendrimer-based delivery systems is likely to be very different from the parent dendrimer.

Expression and functional characterization of a Plasmodium falciparum Ca2+-ATPase (PfATP4) belonging to a subclass unique to apicomplexan organisms

We have obtained a full-length P type ATPase sequence (PfATP4) encoded by Plasmodium falciparum and expressed PfATP4 in Xenopus laevis oocytes to study its function. Comparison of the hitherto incomplete open reading frame with other Ca(2+)-ATPase sequences reveals that PfATP4 differs significantly from previously defined categories. The Ca(2+)-dependent ATPase activity of PfATP4 is stimulated by a much broader range of [Ca(2+)](free) (3.2-320 micrometer) than are an avian SERCA1 pump or rabbit SERCA 1a (maximal activity < 10 micrometer). The activity of PfATP4 is resistant to inhibition by ouabain (200 micrometer) or thapsigargin (0.8 micrometer) but is inhibited by vanadate (1 mM) or cyclopiazonic acid (1 microM). We used a quantitative polymerase chain reaction to assay expression of mRNA encoding PfATP4 relative to that for beta-tubulin in synchronized asexual stages and found variable expression throughout the life cycle with a maximal 5-fold increase in meronts compared with ring stages. This analysis suggests that PfATP4 defines a novel subclass of Ca(2+)-ATPases unique to apicomplexan organisms and therefore offers potential as a drug target.

Comparison of auscultatory and oscillometric automated blood pressure monitors in the setting of preeclampsia

OBJECTIVE

The aim of this study was to compare the accuracy of 2 automated blood pressure monitors against mercury sphygmomanometry and intra-arterial blood pressure determination in women with preeclampsia.

STUDY DESIGN

The auscultatory and oscillometric monitors were compared with mercury sphygmomanometry according to the British Hypertension Society protocol and criteria of the Association for the Advancement of Medical Instrumentation in a group of 30 women with proteinuric preeclampsia. In addition both monitors were compared with intra-arterial blood pressure measurements in a group of 6 women with severe preeclampsia. The mean (+/- SD) of the differences was calculated and a paired t test was used to compare values obtained with each monitor with intra-arterial measurements.

RESULTS

Compared with mercury sphygmomanometry the auscultatory QuietTrak monitor markedly underestimated systolic and diastolic blood pressure by 13 +/- 15 mm Hg. The oscillometric SpaceLabs 90207 monitor also underestimated systolic pressure by 10 +/- 10 mm Hg and diastolic pressure by 8 +/- 7 mm Hg. According to the British Hypertension Society grading criteria both monitors achieved the lowest grade (D) for recording systolic and diastolic pressure. The 2 monitors also did not meet the accuracy criteria stipulated by the Association for the Advancement of Medical Instrumentation. Compared with intra-arterial readings the SpaceLabs monitor significantly underestimated systolic and mean arterial pressures (by 19 and 7 mm Hg, respectively, P <. 01). The QuietTrak monitor significantly underestimated systolic, diastolic, and mean arterial pressures (by 25 mm Hg, P <.05, 18 mm Hg, P <.01, and 20 mm Hg, P <.01, respectively).

CONCLUSION

Neither monitor can be recommended for clinical use in women with proteinuric preeclampsia.

Do hospital palliative care teams improve symptom control? Use of a modified STAS as an evaluation tool

The support team assessment schedule (STAS) has previously been validated as an evaluation tool for community palliative care teams and inpatient units. This study reports on use of an expanded STAS (E-STAS) to determine symptom prevalence and outcome for inpatients and outpatients referred to a multiprofessional hospital palliative care team. E-STAS forms were completed on patients at referral and twice weekly thereafter. Between August 1996 and May 1997, 352 patients had one or more E-STAS forms completed; 122 of this group had three or more assessments. One-hundred-and-eighty-two patients were male and 170 were female, the median age was 68.5 years (range 26-101 years) and all but 27 (8%) had malignant disease. Of the symptoms assessed on referral, the most common were psychological distress 93%, anorexia 73%, pain 59%, mouth discomfort 59%, depression 40%, constipation 36%, breathlessness 32%, nausea 24% and vomiting 13%. In the 122 patients where three or more assessment were completed, statistically significant improvements from first to last assessment were seen in all symptoms except depression. This study suggests that E-STAS may be a useful tool to evaluate interventions by a hospital palliative care team in patients with advanced disease.

The pathomorphologic changes that accompany the resolution of cervical radiculopathy. A prospective study with repeat magnetic resonance imaging

STUDY DESIGN

A prospective study with independent clinical and radiologic review.

OBJECTIVE

To assess whether regression of cervical intervertebral disc herniations accompanied and correlated with clinical improvement in patients recovering from cervical radiculopathy without undergoing surgical intervention.

SUMMARY OF BACKGROUND DATA

The study subjects were 13 consecutive patients, nine men (69%) and four women (31%), presenting with cervical radiculopathy. All patients but one had objective neurologic signs. All patients had large posterolateral cervical intervertebral disc herniations demonstrated by magnetic resonance imaging.

METHODS

Pain was controlled by serial periradicular and epidural corticosteroid injections. Patients were finally examined and discharged from care because of sustained pain control at an average of 6 months (range, 2-12 months). They were interviewed subsequently over the telephone by an independent clinician and rescanned at an average of 12 months (range, 4-31 months). The scans were reviewed by an independent radiologist masked to the sequence of the scans.

RESULTS

Regression of cervical disc herniations was demonstrated in 12 of the 13 patients. All patients had made a satisfactory clinical recovery, but the one with the herniation that had not regressed suffered from persistent minor symptoms.

CONCLUSIONS

Most cervical disc herniations regress with time and without the need for surgical resection. Thus, surgical intervention can be avoided with adequate pain control, allowing the herniation time to regress.

Advances in hormone replacement therapy

Thousands of women in the UK undergo hormone replacement therapy each year. Many of them experience side-effects and choose to discontinue treatment. In this article, the authors review some of the products currently available and the new approaches to therapy that are under investigation.

Changes in the CA 19-9 antigen and Lewis blood group with pulmonary disease severity in cystic fibrosis

The altered carbohydrate structure of sputum from patients with cystic fibrosis (CF) has been thought to be due to the inflammatory airway response. Carcinoembryonic antigen (CEA) and CA 19-9 detect sialosylated carbohydrates in mucus. The epitope of CA 19-9 is part of the Lewis A (Le(a)) blood group antigen. Serum concentrations of CEA and CA 19-9 were determined by radioimmunoassay in 41 CF patients, aged 6-34 years; 16 were asymptomatic Outpatients, and 25 had been admitted for pulmonary exacerbations. There was no difference in CEA between groups. The CA 19-9 serum concentration was elevated in 90% of patients who had at least one of the two Lewis antigens. The CA 19-9 concentration of Inpatients with exacerbations was 2.7 times that of stable Outpatients (263 +/- 44 versus 99 +/- 13 U/mL; P less than 0.02). CA 19-9 correlated significantly with age (r = 0.35, P less than 0.05), Brasfield score (r = 0.39, P less than 0.015), pulmonary function tests, cough severity (r = 0.50, P less than 0.001) and NIH clinical score (r = 0.57, P less than 0.001). CA 19-9 concentration of Inpatients decreased by 44% from admission to discharge (302 +/- 45 to 169 +/- 39, P less than 0.02). Fourteen of 25 (56%) of the Inpatients were Le(a) positive versus only 3/15 (20%) of Outpatients who had milder lung disease (P less than 0.002). Of the Inpatients, 25% with more advanced lung disease were Le(a+b+), a rare blood group in the normal population, and one not observed in the Outpatients with milder disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of phosphate transport in sheep intestine and parotid gland: response to variation in dietary phosphate supply

The transport of phosphate in intestinal brush-border membrane and parotid basolateral membrane vesicles isolated from sheep maintained on high and low phosphate diets have been studied. The mechanism of the transport of phosphate in the intestine is via a proton symporter whilst in the parotid gland it is effected by a Na+ coupled transporter. In sheep fed a low-P diet there is no change in the capacity of the parotid basolateral membrane to transport phosphate into the parotid end piece cells. This is in marked contrast to the response of the enterocyte brush-border membrane, where there is a significant enhancement of the capacity of the membrane to transport phosphate. We conclude that in sheep the gut appears to play a major role in response to phosphate deprivation, by increasing the capacity to transport phosphate. This enhancement is not achieved by increases in the levels of circulating 1,25-dihydroxycholecalciferol.