The molecular weight measurement of intact Escherichia coli proteins separated by isoelectric focusing-immobilized pH gradient (IEF-IPG) gels and analyzed by mass spectrometry is presented. Two methods are discussed: (i) electrospray ionization (ESI) mass spectrometry (MS) of extracted proteins, and (ii) matrix-assisted laser desorption/ionization (MALDI)-MS analysis directly from IEF-IPG gels. Both ESI and MALDI methods yield sub-picomole sensitivity and good mass measurement accuracy. The use of an array detector for ESI-MS was essential to discriminate against contaminating background ions and to selectively detect high mass protein ions. MALDI-MS offers high-throughput analysis of one- and potentially two-dimensional (2-D) gels. The "virtual 2-D" gel method with first-dimensional IEF separation and the second dimension as molecular mass determination by MS, is a particularly promising method for protein analysis due to its ultra high sensitivity and correspondence to classical 2-D gels. Further sensitivity enhancements for the MALDI-MS method are provided by post acceleration detection optimized for high mass time-of-flight analysis.

Bacterial Proteins↗

PubMedDate not supplied

Sensitivity and mass accuracy for proteins analyzed directly from polyacrylamide gels: implications for proteome mapping.

Matrix-assisted laser desorption ionization (MALDI) mass spectra have been obtained directly from thin-layer isoelectric focusing (IEF) gels with as little as 700 femtomoles of alpha- and beta-chain bovine hemoglobin and bovine carbonic anhydrase, and 2 picomoles of bovine trypsinogen, soybean trypsin inhibitor, and bovine serum albumin all loaded onto a single lane. By soaking the gel in a matrix solution, matrix was deposited over the entire gel surface, allowing MALDI scanning down complete lanes of the one-dimensional gel. As long as matrix crystals were deposited finely on the surface of the gel, time-lag focusing techniques were capable of ameliorating some of the mass accuracy limitations inherent in desorbing from uneven insulator surfaces with external calibration. Eleven measurements on the 5 kDa alpha-subunit proteins of lentil lectin measured over the course of 1 h and referenced to a single calibration yielded a standard deviation of 0.025%. Colloidal gold staining was found to be compatible with desorption directly from IEF and sodium dodecyl sulfate (SDS)-polyacrylamide gels. This direct approach simplifies the interface between gel electrophoresis and mass spectrometry dramatically, making the process more amenable to automation.

Acrylic Resins↗

PubMedDate not supplied

The relative importance of head size, gender and age on the auditory brainstem response.

Correlations between the ABR (auditory brainstem response) and subject characteristics of gender, age, and head diameter were established in simple and multiple regression analyses of normal hearing individuals. The simple regression tests demonstrated that head diameter and gender were significantly correlated with the latencies and amplitudes of waves I, III, and V and the I-V and III-V interpeak intervals. In nearly all cases, head diameter correlated more highly with the ABR waves than did gender. Males had longer latencies than females with comparable head diameter, suggesting that factors other than head size are differentiating them. Age was significantly correlated only with the latency of wave III. All significant subject variables also were compared simultaneously in a multiple regression analysis to determine their order of significance and relative contributions to the ABR wave latencies. This permitted the establishment of regression equations for each wave latency to predict the ABR with measurable subject characteristics.

Adolescent↗

PubMedDate not supplied

Effect of mic gene structure on repressor activity in the OmpA system.

It has been previously established that micRNA (mRNA-interfering complementary RNA) complementary to an individual mRNA specifically represses the expression of the target mRNA. We have constructed several plasmids which produce micRNAs which are complementary to different regions of the ompA mRNA. The repressor activity of these different micRNAs has been compared to determine the role of mic gene structure in effective micRNA function. The results indicate that micRNAs complementary to regions of the ompA mRNA likely to encounter ribosomes have the highest repressor activities. A clear effect of mic gene dosage was also observed. This was demonstrated using both identical and different mic(ompA) genes.

Bacterial Outer Membrane Proteins↗

PubMedDate not supplied

Gastroesophageal reflux disease.

This article examines the diagnostic and treatment options available to people who have gastroesophageal reflux disease. The role of nurses in advising and educating patients about lifestyle modifications, which reduce the severity of symptoms and increase the quality of life, is emphasised.

Gastroesophageal Reflux↗

PubMedDate not supplied

Peripheral and central parenteral nutrition: a cost-comparison analysis.

The concept that total parenteral nutrition (TPN) has to be administered centrally is increasingly recognised to be mistaken: for most patients, peripheral parenteral nutrition provides satisfactory nutritional support. Use of the peripheral route avoids the risks of central venous cannulation--but is it more cost-effective? In a randomized clinical study we examined the costs of TPN in 51 patients who underwent a mean of 8 days of intravenous feeding and conclude that the use of peripheral parenteral nutrition may lead to cost savings.

Catheterization↗

PubMedDate not supplied

Assignment of an anonymous DNA sequence IB/D22 (DXS371) to XP11.1-11.4.

In densely mapped and characterized chromosomes such as the X chromosome there are still regions which have a paucity of markers. One of these areas lies in the Xp11 region. Using human-rodent somatic cell hybrids we have assigned a newly isolated clone IB/D22 to the Xp11.1-p11.4 region.

Cell Line, Transformed↗

PubMedDate not supplied