Pharmacological separation of charge movement components in frog skeletal muscle

1. Charge movements to small 10 mV steps superimposed upon a wide range of closely spaced depolarizing voltage-clamp pulses were studied in frog skeletal muscles under different pharmacological conditions in hypertonic solutions.2. In control fibres, capacitance was strongly voltage-dependent, especially between potentials of -60 and -20 mV, confirming earlier work. There was a sharp increase in capacitance at around -50 mV. The dependence of non-linear charge on potential was asymmetrical and saturated at around 25 nC/muF.3. The presence of tetracaine abolished the ;hump' in the non-linear transients, which became simple monotonic decays. The dependence of capacitance upon potential was reduced. The maximum available amount of non-linear charge fell to 10 nC/muF.4. The presence of lidocaine abolished both the ;hump' as well as the monotonic part of the non-linear transients. This resulted in capacitance falling with depolarization from -85 mV.5. Comparing the steady-state properties of the non-linear charge under the different pharmacological conditions made it possible to deduce empirically the following components:(i) A lidocaine-resistant component (q(alpha)), which was responsible for the fall in observed capacitance with depolarization from the control voltage.(ii) A component resistant to tetracaine yet abolished by lidocaine (q(beta)). This possesses quasi-exponential kinetics, and a maximum charge of about 20 nC/muF.(iii) A component abolished by both lidocaine and tetracaine (q(gamma)), which possesses a maximum charge of 15 nC/muF. This has complex kinetics, and its steep dependence upon voltage resembles the potential-dependence of the development of tension in skeletal muscle.

Factors associated with women's and children's body mass indices by income status

OBJECTIVE

To describe associations between eating behaviors, dietary intake, physical activity, attitudes toward diet and health, sociodemographic variables and body mass index (BMI) among women and children, and differences by household income.

DESIGN

Data from the 1994-1996 Continuing Survey of Food Intakes by Individuals (CSFII) and the Diet and Health Knowledge Survey (DHKS) were examined using multivariate regression to estimate the associations between BMI and behavioral and environmental variables among women and children.

SUBJECTS

CSFII 1994-1996 is representative of the US population. DHKS surveyed CSFII respondents 20 y of age and over. Our samples consisted of 2419 adult women and 1651 school-age children.

MEASUREMENTS

CSFII respondents reported 24 h recalls of all food intakes on 2 nonconsecutive days and their personal and household characteristics, including self-reported height and weight. DHKS collected data on knowledge and attitudes toward dietary guidance and health from CSFII adult respondents.

RESULTS

Significant correlations between women's BMI and age, race, dietary patterns, TV watching, and smoking was observed among women from both low- and high-income households. Beverage consumption, eating out, the importance of maintaining healthy weight, and exercise were correlated with BMI only among women from high-income households. Among children, age, race, income, and mother's BMI were significantly correlated with child BMI.

CONCLUSIONS

Among women, the associations between some behavioral and environmental factors and BMI differ by household income. Intervention programs need to target specific eating and physical activity behaviors to promote a healthy body weight.

Emerging insights into the role of calcium ions in osteoclast regulation

Osteoclasts are exposed to unusually high, millimolar, Ca2+ concentrations and can "sense" changes in their ambient Ca2+ concentration during resorption. This results in a sharp cystolic Ca2+ increase through both Ca2+ release and Ca2+ influx. The rise in cystolic Ca2+ is transduced finally into an inhibition of bone resorption. We have shown that a type 2 ryanodine receptor isoform, expressed uniquely in the osteoblast plasma membrane, functions as a Ca2+ influx channel, and possibly as a Ca2+ sensor. Ryanodine receptors are ordinarily microsomal membrane Ca2+ release channels. They have only recently been shown to be expressed a other sites, including nuclear membranes. At the latter site, ryanodine receptors gate nucleoplasmic Ca2+ influx. Nucleoplasmic Ca2+, in turn, regulates key nuclear processes, including gene expression and apoptosis. Here, we review potential mechanisms underlying the recognition, movement, and actions of Ca2+ in the osteoclast.

Phosphatidylinositol 4,5-bisphosphate and intracellular pH regulate the ROMK1 potassium channel via separate but interrelated mechanisms

ROMK channels are responsible for K(+) secretion in kidney. The activity of ROMK is regulated by intracellular pH (pH(i)) with acidification causing channel closure (effective pK(a) approximately 6.9). Recently, we and others reported that a direct interaction of the channels with phosphatidyl-4,5-bisphosphate (PIP(2)) is critical for opening of the inwardly rectifying K(+) channels. Here, we investigate the relationship between the mechanisms for regulation of ROMK by PIP(2) and by pH(i). We find that disruption of PIP(2)-ROMK1 interaction not only decreases single-channel open probability (P(o)) but gives rise to a ROMK1 subconductance state. This state has an increased sensitivity to intracellular protons (effective pK(a) shifted to pH approximately 7.8), such that the subconductance channels are relatively quiescent at physiological pH(i). Open probability for the subconductance channels can then be increased by intracellular alkalinization to supra-physiological pH. This increase in P(o) for the subconductance channels by alkalinization is not associated with an increase in PIP(2)-channel interaction. Thus, direct interaction with PIP(2) is critical for ROMK1 to open at full conductance. Disruption of this interaction increases pH(i) sensitivity for the channels via emergence of the subconductance state. The control of open probability of ROMK1 by pH(i) occurs via a mechanism distinct from the regulation by PIP(2).

Prognostic significance of heat shock protein-27 expression in hepatocellular carcinoma and its relation to histologic grading and survival

BACKGROUND

The expression of heat shock protein-27 (HSP-27) has been detected in some human tumors. In this study the authors investigated HSP-27 expression in patients with hepatocellular carcinoma (HCC) and examined its prognostic significance.

METHODS

Expression of HSP-27 was studied in 58 HCC and adjacent noncancerous liver tissues by immunohistochemical stain. The relation between its expression and eight known prognostic factors was evaluated.

RESULTS

Of the 58 HCC tissues studied, the presence of HSP-27 was demonstrated in 45 tissues (77.6%); low expression (</= 25%) was demonstrated in 17 tissues and high expression (> 25%) was demonstrated in 28 tissues. A significantly higher distribution of HSP-27 expression in HCC tissues compared with adjacent noncancerous liver tissues was obtained (P < 0.0001). Patients with high HSP-27 expression had a significantly higher histologic tumor grade than those with low HSP-27 expression (P = 0.001). The 5-year disease free survival rate of patients with high HSP-27 expression was 21.4% versus 59.3% for patients with low HSP-27 expression (P < 0.001). A similar relation was observed with overall survival (33.3% vs. 64. 8%; P = 0.009). HSP-27 expression was also identified to be a significant and powerful prognostic indicator for disease free survival (odds ratio = 2.25; P = 0.034) and for overall survival (odds ratio = 2.72; P = 0.015).

CONCLUSIONS

The current study data suggest that HSP-27 expression is a powerful prognostic indicator and is related to histologic grade and survival of patients with HCC.

Localization of the ROMK potassium channel to the apical membrane of distal nephron in rat kidney

BACKGROUND

The apical potassium (K+) channels mediate K+ recycling in thick ascending limb (TAL) and K+ secretion in cortical collecting duct (CCD). Recently, the cDNAs for a family of renal K+ channels, ROMK1, -2 and -3, were identified. Based on the biophysical properties and mRNA distribution, it is believed that these ROMK cDNAs encode the apical K+ channels of TAL and CCD. However, the information for cellular and subcellular localization of the ROMK proteins in these tubules is still not available.

METHODS

Paraffin or frozen kidney sections from adult Sprague-Dawley rats were stained by polyclonal antibodies against the N- and C-terminal domain of ROMK. Immunoreactive staining was visualized by color development from horseradish peroxidase reaction. Membrane homogenates from kidney were analyzed by Western blot analysis.

RESULTS

The polyclonal antibodies against cytoplasmic epitope of ROMK recognized a approximately 42 kD protein in the membrane homogenates from kidney, but not from liver. Staining by immunocytochemistry revealed that ROMK channels were localized to the apical membranes of the distal nephron in cortex and outer medulla, including thick ascending limb and collecting tubule. ROMK staining was absent in glomerulus, proximal tubule and inner medulla. Double staining of the tissue section with both ROMK-specific and H+-ATPase-specific antibodies revealed labeling of ROMK in the principal cells of the collecting tubules.

CONCLUSIONS

These results further strengthen the idea that ROMK channels play important roles in the recycling of K+ in TAL and the secretion of K+ in CCD.

Regeneration of the sciatic nerve in rats. The effect of muscle basement membrane

An orientated substratum has been implicated in the development and regeneration of axons and synapses. We prepared a basement membrane matrix from autogenous striated muscle, used it to repair the sciatic nerve in rats, then investigated the results by histology and electrophysiology. When treated grafts were coaxially aligned with the nerve fascicles functional recovery appeared within 30 days, with good growth of axons into the distal nerve. Grafts with myotubes at right angles to the nerve fascicles supported nerve regeneration but at a slower rate. Grafts of coaxially aligned but untreated muscle allowed axon penetration only through naturally degenerated muscle fibres, with minimal axon penetration of the distal nerve. It is concluded that in the rat a treated graft with correctly orientated empty myotubes can facilitate and guide the regeneration of peripheral nerve after injury and so lead to recolonisation of the distal stump with functional recovery.

Gradient preemphasis calibration in diffusion-weighted echo-planar imaging

This article describes a method which enables fast and objective pulse-sequence-specific preemphasis calibration, using standard pulse sequences and system hardware. The method is based on a k-space measurement technique, and has been applied to single-shot, diffusion-weighted, spin-echo, echo-planar imaging (DW-SE-EPI), which is particularly sensitive to eddy-current-induced image distortions. The efficiency of the technique was demonstrated not only by the reduction of eddy-current fields to a negligible level using full preemphasis compensation, but also by the fact that adjustment of the slow time-base alone sufficed for the practical elimination of image distortions in the DW-SE-EPI images and the subsequent diffusion tensor maps (in a phantom and a human brain). By seeking to eliminate directly the effect of eddy-current-induced phase shifts during the EPI data collection, the method is free of the complications and restrictions associated with other eddy-current correction techniques for DW-SE-EPI (such as acquisition of additional calibration scans, intense postprocessing, extensive pulse-sequence modifications), making their use redundant.

In vivo evidence that cGMP is the second messenger for atrial natriuretic factor

cGMP generation has been associated with many of the vascular and endocrine actions of atrial natriuretic factor (ANF) in vitro. To examine the role of cGMP as a second messenger for the renal hemodynamic action of ANF in vivo, we measured glomerular filtration rate (GFR) and cGMP concentration in systemic artery, renal vein, and urine as well as in Bowman's space and end-proximal tubule (by free-flow micropuncture) after administration of ANF. ANF increased GFR by 45% and simultaneously induced a greater than 5-fold increase of cGMP concentration in glomerular ultrafiltrate (Bowman's space) when compared to controls. There was no significant increase in either systemic artery or renal vein cGMP concentration. Thus, the source of increased Bowman's space cGMP is not from the blood via filtration but rather from either glomerular mesangial or epithelial cells, which are not in direct contact with the circulation. Although a small amount of tubular handling of cGMP occurred along the length of the nephron, the augmented cGMP production from the glomerulus accounted for most of the 10- to 12-fold higher urinary cGMP excretion observed after ANF administration. Intrarenal arterial infusion of dibutyryl cGMP, but not dibutyryl cAMP, increased GFR in a dose-dependent fashion (from 10 to 1000 microM) by a mechanism similar to that of ANF--an increase in glomerular hydraulic pressure. Thus, ANF markedly stimulated glomerular production of cGMP, which coincided with a marked increase in GFR. Since dibutyryl cGMP itself was capable of increasing GFR, cGMP is the likely second messenger for ANF in vivo.

MR diffusion tensor imaging of white matter tract disruption in stroke at 3 T

Recent advances in MR diffusion weighted imaging (DWI) enable the identification of anisotropic white matter tracts with diffusion tensor imaging (DTI). We aimed to use a novel DTI technique to safely study patients with recent stroke in a high field (3 T) MR machine with its intrinsically higher spatial resolution and signal-to-noise ratio. Of ten patients studied, six had disruption of white matter tracts as determined by DTI. A further patient had distortion of white matter tracts around an infarct rather than actual disruption of the tracts themselves. The lack of tract destruction may imply a beneficial prognosis, information that is not available with conventional DWI.

Regulation of cytosolic free calcium in isolated rat osteoclasts by calcitonin

It is now established that calcium is a second messenger mediating the action of calcitonin on the osteoclast. We have demonstrated that an increase in the concentration of intracellular free calcium ([Ca2+]i) is associated with (and possibly mediates) the functional effects of calcitonin, including an acute reduction of cell spread area (the R effect) and, in the longer term, a reduction in enzyme release. The present study addresses questions relating to mechanisms of calcitonin action on osteoclast [Ca2+]i. We have used asusuberic(1-7) eel and human calcitonin as agonists, and an indo-1-based dual-emission microspectrofluorimetric method for the measurement of [Ca2+]i in single osteoclasts. Whilst asusuberic(1-7) eel calcitonin caused a biphasic increase in [Ca2+]i, human calcitonin produced only a monophasic [Ca2+]i response of a much lower magnitude. Each biphasic response consisted of a rapid initial transient increase, occurring within seconds of exposure, followed by a sustained increase in [Ca2+]i. The magnitude of the latter response was more variable, but was consistently below the peak value of [Ca2+]i. The sustained phase of the calcitonin effect was abolished in extracellular Ca(2+)-free medium. This phase is therefore dependent on extracellular [Ca2+] ([Ca2+]e) whilst the rapid transient increase appeared to be dependent on Ca2+i redistribution. The effects of calcitonin on [Ca2+]i were concentration-dependent, with neither latency nor oscillations. Repetitive 30-s exposures to calcitonin failed to produce subsequent responses. There was a marked concentration-dependent correlation between changes in osteoclast [Ca2+]i and the magnitude of the R effect. Thus the likely components of the biphasic [Ca2-]i response are a rapid redistribution followed by the transmembrane flux of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Cortical spreading depression in the gyrencephalic feline brain studied by magnetic resonance imaging

1.Time-lapse diffusion-weighted magnetic resonance imaging (DWI) was used to detect and characterize complex waves of cortical spreading depression (CSD) evoked with KCL placed upon the suprasylvian gyrus of anaesthetized cats. 2. The time-lapse representations successfully demonstrated primary CSD waves that propagated with elliptical wavefronts selectively over the ipsilateral cerebral hemispheres with a velocity of 3.8 +/- 0.70 mm min(-1) (mean +/- S.E.M. of 5 experiments). 3. In contrast, the succeeding secondary waves often remained within the originating gyrus, were slower (velocity 2.0 +/- 0.18 mm min(-1), more fragmented and varied in number. 4. Computed traces of the apparent diffusion coefficients (ADCs) showed negative deflections followed by monotonic decays (amplitudes: primary wave, -19.9 +/- 2.8%; subsequent waves, -13.6 +/- 1.9% duration at half-maximal decay, 150-200 s) when determined from regions of interest (ROIs) through which both primary and succeeding CSD waves propagated. 5. The passage of both the primary and the succeeding waves often correlated with transient DC potential deflections recorded from the suprasylvian gyrus. 6. The detailed waveforms of the ADC and the T2*-weighted (blood oxygenation level-dependent: BOLD) traces showed a clear reciprocal correlation. These imaging features that reflect disturbances in cellular water balance agree closely with BOLD measurements that followed the propagation velocities of the first and subsequent CSD events. They also provide a close physiological correlate for clinical observations of cortical blood flow disturbances associated with human migraine.

Role of the endothelial cell in osteoclast control: new perspectives

The osteoclast is of central importance in the process of bone remodeling. Its function is regulated by hormones and locally produced factors. Endothelial cells occur in close proximity to the osteoclast. Some endothelial cell-derived products, including endothelins, nitric oxide, and reactive oxygen species, have been recently implicated as modulators of osteoclast function. Endothelins inhibit bone resorption and osteoclast margin ruffling (quiescence or Q effect) at concentrations similar to those effective for their primary vasoconstrictive action. Contrary to expectations, however, it has been shown that endothelin action on the osteoclast is not mediated through an elevation of cytosolic Ca2+. Nitric oxide (NO) produces marked cell retraction (retraction or R effect), but its detailed mode of action is unknown. However, it is clear that the effects of this autocoid are not due to enhanced cyclic guanosine monophosphate (cGMP) production, a transduction system commonly used by NO. Finally, the reactive oxygen species H2O2 has been shown recently to enhance osteoclastic activity. Thus, the reported effects of the endothelial cell-derived products on the osteoclast are generally consistent with a regulatory role for endothelial cells in osteoclast control and suggest the existence of unique activation pathways, well worth exploring further. Unravelling the responsible mechanisms may also help understand the pathophysiology of a range of bone and joint diseases. For example, in rheumatoid arthritis, there is increased H2O2 production from activated neutrophils, and bone resorption is a major pathophysiological feature.

Extracellular Ca2+ sensing by the osteoclast

An increasing number of cell types appear to detect changes in the extracellular Ca2+ concentration and and accordingly modify their function. We review recent evidence for the existence and function of such a mechanism in the osteoclast. Elevated external [Ca2+] in the mM range reduces bone resorption and results in motile changes in the cells. These changes may partly result from elevations of cytosolic [Ca2+] triggered through activation of a surface Ca2+ receptor. Closer analyses of the increases in cytosolic [Ca2+] associated with receptor activation are hindered by the action of this ion both as extracellular agonist and intracellular second messenger. Variations in the peak cytosolic [Ca2+] response to external Ca2+ with changes in cell membrane potential by K+ and valinomycin establish a contribution from extracellular Ca2+. Use of CIO4-, Ni2+ and Cd2+ as surrogate activators in low extracellular [Ca2+] indicate a contribution from Ca2+ release from intracellular stores as well. Such agonists also modify Ca2+ redistribution in other systems, such as skeletal muscle. Thus, we may gain insights into osteoclast extracellular Ca2+ detection and transduction from known features of more well-characterised cell systems.

IL-10 inhibits HIV-1 replication and is induced by tat

Interleukin 10 (IL-10) is produced by TH2 lymphocytes and regulates both lymphoid and myeloid cells. In the present study we demonstrate that IL-10 is expressed and produced spontaneously in the peripheral blood mononuclear cells (PBMCs) of all HIV-1 infected individuals tested, 3 of 19 cases of HIV-negative lymphoma and none of five healthy controls. IL-10 mRNA was detectable in both monocytes/macrophages and T lymphocytes isolated from PBMCs of HIV infected patients. We have also shown that infection of promonocytic (U937) and T (H9) cell lines with HIV stimulates IL-10 secretion. Furthermore, a T cell line (H9) stably transfected with a HIV tat expression-vector secreted higher levels of IL-10. We have also demonstrated that rhIL-10 inhibited HIV-1 replication in infected monocytes and PBMCs in a dose dependent manner. IL-10 may thus participate in long latency between HIV-1 infection and development of AIDS.

Trace Metals' abnormalities in hemodialysis patients: relationship with medications

A multicenter collaborative study was performed to investigate the prevalence of abnormal blood contents of 6 trace metals, copper (Cu), zinc (Zn), aluminum (Al), lead (Pb), cadmium (Cd), and mercury (Hg), in hemodialysis (HD) patients and to analyze their relationship with the medications, such as CaCO3, Ca acetate, Al containing phosphate-binding agents, 1,25-dihydroxy vitD3, 1-hydroxy vitD3, and erythropoietin (EPO), as well as hematocrit level, by chi-square statistics. From 6 medical centers in Taiwan, we included 456 patients in maintenance HD for more than 4 months for this study, and they had continued the previously mentioned medications for at least 3 months. Blood samples were collected before initiating HD, and atomic absorption spectrophotometry was used to measure plasma levels of Cu, Zn, and Al as well as whole blood levels of Pb, Cd, and Hg. Three hundred seventy-five (78%) of the HD patients had low plasma Zn levels, that is, <800 microg/L, and the mean (+/-SD) concentration was 705.8 (+/-128.23) microg/L in all subjects. One hundred forty-one (31%) of the HD patients had high plasma Al, that is, >50 microg/L, and the mean (+/-SD) was 44.30 (+/-28.28) microg/L in all subjects. Three hundred thirty-three (73%) of the dialysis patients had high Cd levels, that is, >2.5 microg/L, and the mean (+/-SD) was 3.32 (+/-1.49) microg/L in all subjects. The majority of HD patients had normal blood levels of Cu, PB, and Hg. Only 21 (4. 6%), 5 (1.1%), and 3 (0.06%) patients had elevated blood levels of Cu, Pb, and Hg, respectively. Their mean (+/-SD) blood concentration of Cu, Pb, and Hg were 1,049.78 (+/-233.25) microg/L, 7.45 (+/-3.95) microg/dL, and 3.17 (+/-25.56) microg/L, respectively. Three patients had elevated plasma Hg concentrations, that is, 546, 12.6, and 24.0 microg/L, respectively. In the 152 normal healthy age and sex matched control group, the blood levels of Al, Cd, and Pb were all significantly lower than the HD patients. However, the levels of Cu and Zn were higher in the control group. The Hg level was not significantly different in both groups. There was no statistical difference between patients with normal and abnormal blood levels of trace metals in various medications except Al containing phosphate binder. The Al containing phosphate binder users had significantly higher plasma Al levels (54.71 +/- 26.70 versus 41.15 +/- 28.03 microg/L, p < 0.001) and hematocrit levels (29.61 +/- 4.61 versus 27. 81 +/- 3.91, p < 0.0005). There was no statistical correlation between erythropoietin (EPO) dose and hematocrit level in these patients. In conclusion, the blood level of trace metals of these HD patients except Al was not related to their medications. However, caution must be exercised in interpreting this result as dose and duration of medication; efficiency of HD and water treatment may play an important role. Otherwise, environmental factors, diet, and the aging process may contribute to the trace metal burden in uremia. Thus, Zn and Cu are abundant in seafood, and Cd is abundant in contaminated plants such as rice.

Effects of premature stimulation on HERG K(+) channels

1. The unusual kinetics of human ether-à-go-go-related gene (HERG) K(+) channels are consistent with a role in the suppression of arrhythmias initiated by premature beats. Action potential clamp protocols were used to investigate the effect of premature stimulation on HERG K(+) channels, transfected in Chinese hamster ovary cells, at 37 degrees C. 2. HERG K(+) channel currents peaked during the terminal repolarization phase of normally paced action potential waveforms. However, the magnitude of the current and the time point at which conductance was maximal depended on the type of action potential waveform used (epicardial, endocardial, Purkinje fibre or atrial). 3. HERG K(+) channel currents recorded during premature action potentials consisted of an early transient outward current followed by a sustained outward current. The magnitude of the transient current component showed a biphasic dependence on the coupling interval between the normally paced and premature action potentials and was maximal at a coupling interval equivalent to 90 % repolarization (APD(90)) for ventricular action potentials. The largest transient current response occurred at shorter coupling intervals for Purkinje fibre (APD(90) - 20 ms) and atrial (APD(90) - 30 ms) action potentials. 4. The magnitude of the sustained current response following premature stimulation was similar to that recorded during the first action potential for ventricular action potential waveforms. However, for Purkinje and atrial action potentials the sustained current response was significantly larger during the premature action potential than during the normally paced action potential. 5. A Markov model that included three closed states, one open and one inactivated state with transitions permitted between the pre-open closed state and the inactivated state, successfully reproduced our results for the effects of premature stimuli, both during square pulse and action potential clamp waveforms. 6. These properties of HERG K(+) channels may help to suppress arrhythmias initiated by early afterdepolarizations and premature beats in the ventricles, Purkinje fibres or atria.

The association of K-ras gene mutation and vascular endothelial growth factor gene expression in pancreatic carcinoma

BACKGROUND

Previously, the authors reported the role of the vascular endothelial growth factor (VEGF) as an angiogenic factor in 40 patients with pancreatic carcinoma. In this study, they investigated the mechanism underlying the regulation of VEGF gene expression and evaluated VEGF expression and K-ras gene status in 48 patients with pancreatic carcinoma.

METHODS

The authors used quantitative reverse transcriptase-polymerase chain reaction analysis and direct sequencing techniques for a retrospective study of VEGF gene expression and K-ras gene status in tumor tissue samples from 48 patients with pancreatic carcinoma. Immunohistochemistry also was used to investigate VEGF protein expression.

RESULTS

Thirty-one tumors (64.6%) were evaluated with high VEGF expression, and 17 tumors (35.4%) were evaluated with low VEGF expression. Of the 48 primary pancreatic tumors studied, 33 tumors (68.8%) contained mutations of the K-ras gene. There was a significant correlation between VEGF expression and K-ras status. Twenty-five of 33 tumors (75.8%) with mutant K-ras genes showed high VEGF expression, whereas only 6 of 15 tumors with the wild type K-ras (40.0%) showed high VEGF expression (P = 0.038). The mean (+/- standard error) VEGF conservation rate for the 33 tumors with mutant K-ras was 1.839 +/- 1.241, and that for the 15 tumors with wild type K-ras was 1.057 +/- 0.983 (P = 0.037). Furthermore, the median survival for patients with mutant K-ras was shorter than for those with wild type K-ras (10.6 months vs. 27.6 months, respectively; P = 0.026), whereas the median survival for patients with high VEGF expression was shorter compared with that for patients with low VEGF expression (9.5 months vs. 26.4 months, respectively; P = 0.002). Cox regression model analysis indicated that only the VEGF status was a significant factor for prognosis (P = 0.024). Other variables, i.e., K-ras status, histopathologic tumor grade, tumor status, lymph node status, metastatic status, gender, and age at surgery, were not significant.

CONCLUSIONS

The results of this study suggest that K-ras oncogene mutation may be associated with VEGF expression and that patients with pancreatic carcinoma who have high VEGF expression are associated with a poor prognosis.

Immunohistochemically detected expression of motility-related protein-1 (MRP-1/CD9) in lung adenocarcinoma and its relation to prognosis

Motility-related protein-1 (MRP-1)/CD9 is a trans-membrane glycoprotein closely associated with suppression of cell motility and reduced metastatic potential of some tumor cells. We currently report that, according to the RT-PCR method for MRP-1/CD9 gene expression, patients with low expression of MRP-1/CD9 in non-small-cell lung cancer, especially the adenocarcinoma type, showed short overall survival. Then, to determine accurately the prognostic value of MRP-1/CD9 product levels in lung-adenocarcinoma cells, we immunohistochemically investigated its expression in 132 lung-adenocarcinoma patients undergoing potentially curative surgery. Of these patients, 44 (33%) showed reduced expression of MRP-1/CD9 in cancer cells, and an inverse association was observed between its expression and factors associated with tumor progression, such as nodal involvement (p = 0.029) or stage (p = 0.028). Patients with reduced expression of MRP-1/CD9 showed a significantly worse prognosis in overall survival (p = 0.005) and disease-free survival (DFS; p < 0.0001) than those with stronger expression; and even among patients with stage-I disease, similar results were obtained (overall survival, p = 0.038; DFS, p = 0.012). In a multivariate analysis, immunohistochemical MRP-1/CD9-expression level was an independent prognostic factor for DFS (p = 0.021), but not for overall survival (p = 0.572). Thus, immunohistochemical MRP-1/CD9-expression level solely in lung-adenocarcinoma cells within the tumor tissue appears to be a prognostic factor for DFS, and may be useful for detecting a high-risk sub-group of recurrence during the post-operative clinical course of the disease.

Dielectric components of charge movements in skeletal muscle

1. Voltage clamp experiments measured transients from 10 mV steps applied about different membrane potentials, VT. Their analysis employed the Fourier transform relationship between dielectric spectra of permittivity as a function of frequency, and the step transient admittance, as well as established methods. 2. The membrane capacitance measured between -85 mV and about -50 mV rose monotonically and was associated with simple decaying transients in both 'on' and 'off' steps. At more depolarized potentials the capacitance increased sharply and was associated with a charging current of complex form, before falling again beyond the transition potential. 3. Step-transient responses for dielectric analysis were sampled in the above voltage range. Dielectric spectra of the non-linear transients were obtained by subtracting Fourier transforms of transients at VC = -85 mV from test transforms at VT. 4. The imaginary transform coefficients represent a spectrum of dielectric loss against frequency. These showed two non-linear components. The q beta component formed a broad peak, when charge movements were simple monotonic decays. A sharp low-frequency q gamma peak became superimposed at particular voltages when charge-movement kinetics became complex. 5. In contrast, 'off' transients were simple monotonic relaxations. Their transforms showed only one dielectric loss peak, whose frequency was relatively voltage-independent when q gamma occurred in 'on' transforms. 6. Both altering holding potential from VH = -85 to -50 mV and adding 1 mM-tetracaine to the bathing solution reduced the dependence of capacitance on voltage. The non-linear polarization currents became simple monotonic relaxations at both the beginning and end of the voltage step. 7. It is concluded that charge movements are composed of at least two components: q beta, and the tetracaine and voltage-inactivated q gamma. Any causal relationship between q beta and q gamma and the membrane processes they might underlie would be expected to be complex.

Cortical spreading depression and migraine: new insights from imaging?

The possibility that spreading depression (SD) of cortical activity, a phenomenon observed in all vertebrates, causes the aura of migraine remains an open question in spite of nearly half a century of investigation. SD is also thought to be associated with the progressive neuronal injury observed during cerebral ischaemia. Thus, the ability to detect and investigate SD in humans might prove clinically significant. Animal studies of cortical spreading depression (CSD) have benefited greatly from the advent of relatively non-invasive imaging techniques. The use of these new imaging techniques for clinical studies will accelerate progress in this area of neurobiology.

Selective antagonism of calcitonin-induced osteoclastic quiescence (Q effect) by human calcitonin gene-related peptide-(Val8Phe37)

Exposure of isolated rat osteoclasts to calcitonin (CT) leads to an abrupt cessation of cell motility (Q effect) followed by cell retraction (R effect). We have previously shown that these effects are mediated by two G proteins that appear to activate separate post-receptor pathways. The present study demonstrates that the Q but not the R effect of CT (0.006 microM) is abolished in the presence of human calcitonin gene-related peptide (CGRP)-(Val8Phe37) (0.5 microM), a fragment analogue of human CGRP. This selective antagonism suggests that the Q effect could result from an action of CT upon a site that is distinct from that producing the R effect. The former site ('amylin site') also appears to interact with related peptides, amylin and CGRP, whilst the latter site ('CT site') specifically interacts with CT.

Mapping of brain activation in response to pharmacological agents using fMRI in the rat

Functional MRI (fMRI) was used to investigate the effects of psychotropic compound activity in the rat brain in vivo. The effects of dizocilpine (MK-801) an N-methyl-D-aspartate receptor antagonist and m-chlorophenylpiperazine (mCPP), a 5-HT(2b/2c)-receptor agonist on rat brain activity were investigated over a time interval of about 1 h and the results were compared to published glucose utilisation and cerebral blood flow data. Signal magnitude increases were observed predominantly in limbic regions following MK-801 administration (0.5 mg/kg i.v) whereas signal decreases were restricted to neocortical areas; a characteristic, time dependent pattern of regional changes evolved from the thalamic nuclei to cortical regions. In contrast, mCPP (25 mg/kg i.p) produced gradual signal intensity increases in limbic and motor regions with signal decreases restricted to the visual, parietal and motor cortices. The results from both compounds show remarkable similarity with autoradiographic measurements of cerebral blood flow and glucose uptake. These experiments suggest that the spatio-temporal capabilities of fMRI may be applied to the in vivo investigation of psychoactive compound activity with potential for clinical applications.