Cellular mechanisms underlying carbachol-induced oscillations of calcium-dependent membrane current in smooth muscle cells from mouse anococcygeus

1. At a holding potential of -40 mV, carbachol (50 microM) produced a complex pattern of inward currents in single smooth muscle cells freshly isolated from the mouse anococcygeus. Membrane currents were monitored by the whole-cell configuration of the patch-clamp technique. Previous work has identified the first, transient component as a calcium-activated chloride current (ICl(Ca)) and the second sustained component as a store depletion-operated non-selective cation current (I(DOC)). The object of the present study was to examine the cellular mechanisms underlying the third component, a series of inward current oscillations (I(oscil)) superimposed on I(DOC). 2. Carbachol-induced I(oscil) (amplitude 97 +/- 11 pA; frequency 0.26 +/- 0.02 Hz) was inhibited by the chloride channel blocker anthracene-9-carboxylic acid (A-9-C; 1 mM), and by inclusion of 1 mM EGTA in the patch-pipette filling solution. 3. In calcium-free extracellular medium (plus 1 mM EGTA), carbachol produced an initial burst of oscillatory current which lasted 94 s before decaying to zero; I(oscil) could be restored by re-admission of calcium. The frequency, but not the amplitude, of I(oscil) increased with increasing concentrations of extracellular calcium (0.5-10 mM). 4. Inclusion of the inositol triphosphate (IP3) receptor antagonist heparin (5 mg ml(-1) in the patch-pipette filling solution, or pretreatment of cells with the sarcoplasmic reticulum (SR) calcium ATPase inhibitor cyclopiazonic acid (CPA; 10 microM), prevented the activation of I(oscil) by carbachol. Caffeine (10 mM) activated both ICl(Ca) and I(DOC) and prevented the induction of I(oscil) by carbachol. Caffeine and CPA also abolished I(oscil) in the presence of carbachol, as did both a low (3 microM) and a high (30 microM) concentration of ryanodine. 5. Carbachol-induced I(oscil) was abolished by the general calcium entry blocker SKF 96365 (10 MM) and by Cd2+ (100 microM), but was unaffected by La3+ (400 microM). As found previously, I(DOC) was also blocked by SKF 96365 and Cd2+, but not La3+; the inhibition of I(DOC) preceded the abolition of I(oscil) by 27 s with SKF 96365 and by 30 s with Cd2+. Nifedipine (1 microM) produced a partial inhibition of the carbachol-induced I(oscil) frequency at holding potentials of -20 mV and -60 mV and, in addition, reduced I(DOC) at -60 mV by 18%. 6. It is concluded that carbachol-induced inward current oscillations in mouse anococcygeus cells are due to a calcium-activated chloride current, and reflect oscillatory changes in cytoplasmic calcium ion concentration. These calcium oscillations are derived primarily from the SR stores, but entry of calcium into the cell is necessary for store replenishment and maintenance of the oscillations. Capacitative calcium entry (via I(DOC) appears to be important not only for sustained contraction of this tissue, but also as a route for re-filling of the SR and, therefore, represents an important target for the development of novel and selective drugs.     

From genome to proteome: protein map of Haemophilus influenzae

High-resolution two-dimensional (2-D) polyacrylamide gel electrophoresis allows the separation of complex biological mixtures (i.e., several hundred proteins from a bacterial cell lysate) in a single experiment. In this report proteins from Haemophilus influenzae were separated by 2-D gels and analyzed by peptide mass fingerprinting and/or amino acid analysis. By comparing the peptide mass profiles and the amino acid composition with the Haemophilus influenzae database, 119 protein spots were identified. The combination of amino acid analysis and peptide mass fingerprinting is a powerful tool for a rapid and economical identification of a large number of proteins resolved by 2-D gels. Studies on gene regulation and changes of protein expression upon drug treatment require quick and serial analysis techniques to efficiently identify potential new drug targets.     

Detection of hepatitis G virus from serum and liver of a patient with long-term liver dysfunction after autologous bone marrow transplantation

Long-term effects after blood or bone marrow transplantation (BMT) are emerging as an important issue, as more patients are included in BMT programmes and as this procedure becomes more successful. Long-term liver dysfunction, mainly due to chronic graft-versus-host disease or hepatitis C virus infection, is a well-known complication. Nevertheless, the diagnosis of liver disease in this patient group is sometimes difficult and, despite adequate studies, it may remain undetected. A novel hepatitis-associated virus, hepatitis G virus (HGV), has recently been identified. The virus belongs to the Flaviviridae family and is known to be parenterally transmitted, although there is no clear evidence to implicate this agent in causing acute or chronic hepatitis. We report a patient who developed mild, but persistent, abnormalities in transaminases for 2 years after an autologous BMT. HGV RNA was detected in both serum and liver. HGV RNA persisted in serum for at least 8 months. No other known hepatitis virus was found. This report provides the first direct evidence of a patient with long-term liver abnormalities after a BMT in whom the only known hepatitis virus isolated was the HGV.     

In vitro toothbrush-dentifrice abrasion of resin-modified glass ionomers

OBJECTIVES: The three purposes of this study are to: (1) describe the relationship between the prevalence of coronal caries and root caries; (2) describe the relationship between the three-year incidence of coronal caries and root caries; and (3) if the two conditions are associated, develop a multiple regression model that identifies characteristics distinguishing people who had increments of both root caries and coronal caries from people who had increments of either coronal caries or root caries, or who had no new caries. METHODS: Dental examinations and interviews were conducted in the homes of a randomly selected, stratified sample of people over the age of 65 years in five North Carolina counties. The relationships between coronal and root D and DF were analyzed through contingency table analyses, and ordinal logistic regression was used to identify characteristics that differentiated people who had both coronal and root D over the three years from people who had either coronal or root D and people who had no new disease. RESULTS: Evidence of root and coronal caries in whites was much more likely to be in the form of fillings, while for blacks, it was more likely to be in the form of untreated decay. Prevalence rates of coronal and root D and DF were significantly associated for both blacks and whites. Incidence rates based on DF indicated that root and coronal caries were not associated in whites, but were associated in blacks. People more likely to experience both types of caries had more gingival recession at baseline, greater average attachment loss over the three years, and lactobacilli at baseline. In addition, the presence of Porphymonas gingivalis at three years was important for whites. CONCLUSIONS: It appears that coronal and root caries do tend to appear together in the same individuals, but fillings attenuate that relationship. The impact of dental treatment on the epidemiology of dental caries appears to be considerable and calls into question whether the F component of the caries index is related to disease as defined by epidemiologic criteria.     

Measurement techniques for monolithic microwave integrated circuits

Introduces the basic technologies that are associated with measurements of monolithic microwave integrated circuits. The use of test fixtures and wafer probe stations at ambient room temperature is reviewed and their role at thermal and cryogenic temperatures is discussed. With the increasing need for performing non-invasive measurements, advances in experimental field probing techniques are explored     

Uniplanar techniques for monolithic microwave integrated circuits

`Uniplanar' techniques have recently been introduced for the design of monolithic microwave integrated circuits (MMICs). The aim of these techniques is to achieve a higher level of integration of circuitry and to overcome the need for through-substrate via holes and the related back-face processing steps. This is achieved by using coplanar waveguide (CPW), slotline, and miniature `thin-film microstrip' transmission-line media as opposed to conventional microstrip. The design and performance of a number of uniplanar MMIC couplers, amplifiers, and other test circuits fabricated using the GEC-Marconi (Caswell) foundry are described     

Dental evidence for the peopling of the New World: some methodological considerations

Turner (1985b) and Greenberg et al. (1986) proposed that New World populations originated in northern Asia and entered the Americas in three migratory waves: Macro-Indian, Aleut-Eskimo, and Na-Dene. Biological support for this model comes from Turner's unweighted pair group (UPGMA) cluster analysis of discrete dental traits in world populations. Unfortunately, UPGMA analysis often creates suspect clusters and may not be valid as a method for displaying evolutionary relationships because it assumes that rates of evolution are equal among all populations. To test whether Turner's results are an artifact of his analytical method, I analyzed his published data (Turner 1985b) using two alternative techniques that do not assume homogeneous rates of change: a Wagner distance algorithm employing the Fitch-Margoliash criterion for goodness of fit and a maximum parsimony analysis using segment-coded dental trait frequencies. Both alternative methods produce trees that are similar to the UPGMA analysis results, supporting Turner's original results and basic conclusions. Comparisons of tree topology demonstrate that there is strong congruence between trees produced by all three methods, although the placement of certain populations, such as Na-Dene, depends on the method of analysis employed.     

Effect of furosemide and intravenous normal saline fluid load upon the renal resistive index in nonobstructed kidneys in children

Recent literature has shown that relative to baseline the renal resistive index remains unchanged in nonobstructed kidneys and increases in obstructed kidneys after administration of furosemide. To our knowledge the effect upon the renal resistive index of furosemide administered in conjunction with intravenous normal saline fluid load has not been reported. We evaluated the renal resistive index in 13 nonobstructed kidneys in 8 children 6 to 18 years old before and after furosemide and intravenous normal saline fluid load. The mean resistive index decreased from baseline (mean decrease was 0.06 +/- 0.06 standard deviation), with the observation of a resistive index decrease significant to p < 0.005). It appears likely that the combination of an intravenous normal saline fluid load and furosemide caused the resistive index decrease, since a decrease was not observed with furosemide alone; however, these results cannot exclude the possibility that the resistive index decrease was due to the intravenous normal saline fluid load alone. Nonetheless, these data are important since they may provide the foundation for the development of a pharmacologically challenged Doppler sonographic examination using furosemide and intravenous normal saline fluid load to evaluate better potentially obstructed kidneys.