Vaccinia protein kinase 2: a second essential serine/threonine protein kinase encoded by vaccinia virus

The major protein kinase activity from vaccinia virus core particles was purified to near homogeneity. The protein kinase is a 50-kDa polypeptide that is shown here to phosphorylate primarily seryl residues in alpha-casein, a casein kinase I-specific peptide substrate, and itself through autophosphorylation. The sequence of four peptides derived from the protein kinase demonstrated that it is encoded by the vaccinia virus F10L gene. Expression of the F10L gene product in bacteria as a fusion with glutathione S-transferase confirmed that the vaccinia F10L gene encodes the protein kinase. We have termed this enzyme vaccinia protein kinase 2 (VPK2) to distinguish it from the protein kinase encoded by the vaccinia B1R gene. Targeted disruption of the VPK2 gene with a positive selectable marker demonstrated that all viruses with a disrupted gene also possessed a wild-type gene, suggesting that VPK2 is essential for viability. The discovery of a second essential protein kinase encoded by vaccinia virus, in addition to a protein phosphatase, underscores the importance of protein phosphorylation in poxvirus biogenesis.

Propofol causes a dose-dependent decrease in the thermoregulatory threshold for vasoconstriction but has little effect on sweating

BACKGROUND

Volatile anesthetics increase the core temperature required to trigger sweating and decrease the core temperature required to trigger vasoconstriction. However, little is known about the effects of intravenous anesthetics on thermoregulation. We therefore tested the hypothesis that propofol increases the sweating threshold and decreases the vasoconstriction threshold, thereby increasing the inter-threshold range (core temperatures not triggering autonomic thermoregulatory responses). The study was conducted using a new model in which thermal manipulations were restricted to insensate skin, and sensate skin temperature was controlled.

METHODS

Six healthy, male volunteers were studied on 3 randomly ordered days: no propofol, target propofol blood concentration 2 micrograms/ml, and target blood propofol concentration 4 micrograms/ml. Each day, epidural anesthesia (approximately T11 level) was induced, using 2% 2-chloroprocaine (one volunteer received bupivacaine). Thermal manipulations were confined to the legs, and we attempted to maintain upper-body (sensate) skin temperature constant. Propofol was infused by a computer-controlled infusion pump. Volunteers were heated until sweating was observed, then cooled until fingertip vasoconstriction was observed. The sweating threshold was defined as the tympanic membrane temperature triggering sustained evaporative heat loss > 40 g.m-2.h-1. Similarly, the vasoconstriction threshold was defined as the tympanic membrane temperature triggering a sustained reduction in fingertip blood flow to < 0.25 ml/min. Central venous blood was assayed for propofol blood concentration.

RESULTS

Increasing propofol concentration produced a linear decrease the vasoconstriction threshold (slope = -0.53 +/- 0.34 degrees C.microgram-1.ml-1; R2 = 0.98 +/- 0.04 [mean +/- SD]), but had little effect on the sweating threshold. The inter-threshold range was 0.51 +/- 0.46 degrees C during epidural anesthesia alone, and increased significantly, by 0.49 +/- 0.31 degrees C.microgram-1.ml-1 during propofol administration.

CONCLUSIONS

Like volatile anesthetics, propofol reduces the vasoconstriction threshold and increases the inter-threshold range. However, propofol differs in leaving the sweating threshold unchanged.

Chemical modification of Lys-6 in Taiwan cobra phospholipase A2 with 4-chloro-3,5-dinitrobenzoate

Phospholipase A2 (PLA2) from Naja naja atra snake venom was modified with 4-chloro-3,5-dinitrobenzoate, and one major carboxydinitrophenylated (CDNP) PLA2 was separated by high performance liquid chromato-graphy. CDNP-PLA2 contained only one CDNP group on Lys-6 and showed a 93% drop in enzymatic activity. However, carboxydinitrophenylation did not significantly affect the secondary structure of the enzyme molecule as revealed by the CD spectra, and Ca2+ binding and antigenicity of CDNP-PLA2 were unaffected. Conversion of nitro groups to amino groups resulted in a partial restoration of enzymatic activity of CDNP-PLA2 to 35% of that of native enzyme. These results suggested that the positively charged side chain of Lys-6 played a role in the enzymatic mechanism of PLA2. However, the partial restoration in PLA2 activity reflects that a distortion of the active conformation arising from incorporation of a bulky CDNP group should occur.

Integration and germ-line transmission of a pseudotyped retroviral vector in zebrafish

The zebrafish is rapidly becoming a popular model system for the study of vertebrate development because it is ideal for both embryological studies and genetic analysis. To determine if a retroviral vector pseudotyped with the envelope glycoprotein of the vesicular stomatitis virus could infect zebrafish embryos, and in particular, the cells destined to become the germ line, a pseudotyped virus was injected into blastula-stage zebrafish embryos. Fifty-one embryos were allowed to develop and eight transmitted proviral DNA to their progeny. Founders were mosaic, but as expected, transgenic F1's transmitted proviral DNA in a Mendelian fashion to the F2 progeny. Transgenic F1 fish inherited a single integrated provirus, and a single founder could transmit more than one viral integration to its progeny. These results demonstrate that this pantropic pseudotyped vector, originally developed for human gene therapy, will make the use of retroviral vectors in zebrafish possible.

Optically programmable two-channel sorting network based on a polarization- and area-encoded technique

We describe an optical cascadable polarization- and area-encoded sorting system that is capable of independently sorting two arrays of unipolar data, each in an arbitrary order specified by a corresponding instruction. The sorting instructions can be easily programmed by external optical signals. The system can be used for sorting a single array of bipolar data.

Femtosecond pump-probe analysis of energy and electron transfer in photosynthetic membranes of Rhodobacter capsulatus

Low-intensity, 295 K, femtosecond pump-probe transient absorption measurements are described that have been performed to investigate energy and electron transfer in photosynthetic membranes from a Rhodobacter capsulatus strain lacking functional light harvesting antenna complex II. Spectral and kinetic similarities between the absorption changes of isolated reaction centers and those of reaction centers in membranes upon 800-nm excitation suggest that the charge separation process in both cases is very similar. An ultrafast energy relaxation process observed near 872 nm when 800-nm excitation is used is interpreted as interexcitonic relaxation within the antenna, though other interpretations, such as vibrational relaxation, are possible. On the basis of global exponential fitting analysis of the time-dependent spectral changes using 800- and 880-nm excitation wavelengths to selectively excite the reaction center and the LHI antenna, respectively, it is found that excitation energy transfer and trapping in Rb. capsulatus is limited by the overall rate of energy transfer between the antenna and the reaction center. This conclusion is supported by the observation that excitation at 800 nm, but not 880 nm, results in absorbance changes indicative of charge separation with a lifetime (3.1 ps) very close to that reported for charge separation in isolated reaction centers (3.5 ps). Thus, most reaction centers that are directly excited undergo charge separation and not backward energy transfer to the LHI antenna complexes. Both a kinetic model analysis and a direct comparison between time-resolved spectra obtained using different excitation wavelengths resulted in an energy-detrapping efficiency of about 15 +/- 10%.

Relationship between thermodynamics and mechanism during photoinduced charge separation in reaction centers from Rhodobacter sphaeroides

Detailed fast transient absorption measurements have been performed at low temperature on reaction centers from Rhodobacter sphaeroides strain R-26 and on a double mutant, [LH(L131) + LH-(M160)], in which the P/P+ oxidation potential is roughly 140 mV (1100 cm-1) above that of wild-type reaction centers. In both samples, the decay of the excited singlet state of the initial electron donor is not well described by a single-exponential decay term. This is particularly true for reaction centers from the double mutant where at least three exponential kinetic components are required to describe the decay, with time constants ranging from a few picoseconds to hundreds of picoseconds. However, singular value decomposition analysis of the time-dependent absorption change spectra indicates the presence of only two spectrally distinct states in reaction centers from both R-26 and the double mutant. Thus, the complex decay of P* at low temperature does not appear to be due to formation of either the state P+BA- as a distinct intermediate in electron transfer or P+BB- as an equilibrated side product of electron transfer. Instead, the decay kinetics are modeled by assuming dynamic solvation of the charge-separated state, as was done for the long-lived fluorescence decay in the accompanying paper [Peloquin, J. M., Williams, J. C., Lin, X., Alden, R. G., Taguchi, A. K. W., Allen, J.P., & Woodbury, N. W. (1994) Biochemistry 33, 8089-8100]. The results of assuming a static distribution of electron-transfer rates at early times followed by dynamic solvation of the charge-separated states on longer time scales are also presented. Regardless of which model is used to describe the early time kinetics of excited-state decay, the time-dependent excited-state population on the 100-ps or longer time scale is best described in terms of thermal repopulation of P* from the charge-separated state, even at 20 K. This results in a time- and temperature-dependent driving force estimated for initial electron transfer of less than 200 cm-1 on all time scales from picoseconds to nanoseconds. Assuming a nonzero internal reorganization energy associated with charge separation, the small driving force does not appear to be consistent with the lack of temperature dependence of electron transfer and the fact that a mutant with a P/P+ oxidation potential 140 mV (1100 cm-1) higher than wild type is still able to undergo electron transfer, even at low temperature.(ABSTRACT TRUNCATED AT 400 WORDS)

Redox effects on the bacteriochlorophyll a-containing Fenna-Matthews-Olson protein from Chlorobium tepidum

The BChl a-containing Fenna-Matthews-Olson (FMO) protein from the green sulfur bacterium Chlorobium tepidum was purified and characterized. Fluorescence spectra indicate that efficient excited state quenching occurs at neutral or oxidizing redox potentials. The major fluorescence lifetime at room temperature is approximately 60 ps in samples that are in neutral or oxidizing conditions, and approximately 2 ns in samples where the strong reductant sodium dithionite has been added. A similar change is observed in pump-probe picosecond absorbance difference experiments, where the long life time component increases after dithionite addition. A 16 Gauss wide EPR signal with g factor = 2.005 is observed in samples without dithionite. This signal largely disappears upon addition of dithionite. Dithionite induces large reversible changes in the 77 K absorbance spectra of the purified FMO protein and in whole cells. These results indicate that the FMO protein contains redox active groups, which may be involved in the regulation of energy transfer. Room temperature circular dichroism and low temperature absorption spectra show that dithionite also induces conformational or structural changes of the FMO protein complex.

Impaired esophageal emptying in reflux disease

OBJECTIVES

The symptoms and mucosal damage that occur in gastroesophageal reflux disease (GERD) may be a consequence of either an increased frequency of reflux events or of a prolonged process of esophageal acid clearance. Acid clearance is dependent both upon effective esophageal emptying of luminal fluid and on normal salivary function to titrate residual acid to neutrality. This investigation examined the efficacy of esophageal emptying in a large group of GERD patients.

METHODS

Barium swallow examinations were done to categorize and quantify esophageal emptying dysfunction in 67 consecutive patients with reflux disease, compared with 85 patient asymptomatic controls. Quantitative fluoroscopic estimates of esophageal residua were compared with scintigraphic quantification in 14 controls and 20 GERD patients.

RESULTS

There was progressive impairment of esophageal emptying in the reflux patients without esophagitis compared with the controls, and it was even greater in patients with endoscopically evident esophagitis compared with reflux patients without esophagitis. Good correlation existed between the fluoroscopic and scintigraphic assessment of esophageal emptying.

CONCLUSIONS

These findings support the hypothesis that impaired esophageal emptying is an important determinant in the development of esophagitis among reflux patients. The dominant site of impaired emptying in the reflux patients was the phrenic ampulla as opposed to the tubular esophagus, suggesting a pathophysiological contribution of hiatus hernia.

Relationship of phospholipid distribution to shape change in Ca(2+)-crenated and recovered human erythrocytes

Echinocytosis induced by elevation of intracellular Ca2+ in human erythrocytes can be reversed by removal of the cation. Using back-extraction of radiolabeled dilauroyl phospholipid analogs which had been incorporated into the cell membrane, we examined the relationship between this reversible shape transformation and phospholipid distribution. Upon Ca2+ crenation of cells, surface exposure of phosphatidylserine and phosphatidylethanolamine was observed simultaneously with inward diffusion of phosphatidylcholine. Removal of Ca2+ allowed resequestration of exposed phosphatidylserine to the membrane inner monolayer, but randomized phosphatidylethanolamine and phosphatidylcholine were not redistributed to their original states. Both shape reversion and retranslocation of phosphatidylserine were reversibly inhibited vanadate. On the other hand, the cell shape recovery was found to be independent of membrane skeleton and phosphoinositide metabolism and was supported by ATP resynthesis only under conditions where the aminophospholipid translocator is active. Other Ca(2+)-mediated biochemical changes, such as generation of diacylglycerol and fatty acids, were found to have no effect on Ca2+ crenation or its reversal, or upon transbilayer distribution of any phospholipid. These findings suggest that Ca2+ induces phospholipid redistribution, possibly by direct interaction with the lipid bilayer and, further, that metabolic recovery from Ca2+ crenation reflects selective retransport of phosphatidylserine to the membrane inner monolayer.

(R)-methanandamide: a chiral novel anandamide possessing higher potency and metabolic stability

Four chiral congeners of arachidonylethanolamide (anandamide) have been synthesized and evaluated for (a) their ability to bind to the cannabinoid receptor in rat forebrain membranes and (b) their pharmacological potency as measured by the compounds' ability to inhibit electrically-evoked contractions of the mouse vas deferens. The lead analog was also tested for its potency in vivo. Of the analogs tested, (R)-(+)-arachidonyl-1'-hydroxy-2'-propylamide [(R)-methanandamide] exhibited the highest affinity for the cannabinoid receptor with a Ki of 20 +/- 1.6 nM, 4-fold lower than that of anandamide (Ki = 78 +/- 2 nM). Moreover, determination of the cannabinoid binding affinity in the presence and absence of the protease inhibitor phenylmethanesulfonyl fluoride (PMSF) revealed that (R)-methanandamide possesses a remarkable stability to aminopeptidase hydrolysis. Pharmacological studies on mouse isolated vasa deferentia demonstrated that all four analogs produce concentration-related inhibition of the twitch response and the order of potency is the same as the rank order of the affinities of these agonists for cannabinoid binding sites. Furthermore, experiments with mice have demonstrated that (R)-methanandamide also possesses cannabimimetric properties in vivo, as established by the four tests of hypothermia, hypokinesia, ring immobility, and antinociception.

Potential parental exposure to pesticides and limb reduction defects

OBJECTIVES

The goal of the study was to examine the effects of the potential pesticide exposure of parents on the risk of limb reduction defects in their offspring.

METHODS

A case-referent study was conducted utilizing New York State Congenital Malformation Register data. Persons with limb reduction defects and referents were compared in terms of parental occupations and residence counties. Parental occupations and industries reported on birth certificates were qualitatively rated by industrial hygienists to estimate potential pesticide (list four groups) exposures. Residential exposures were estimated from agricultural census data according to county of residence.

RESULTS

Neither parental exposure to pesticides [odds ratio (OR) 0.9, 95% confidence interval (95% CI) 0.6-1.4] nor farming occupation (OR 1.1, 95% CI 0.5-2.7) had an effect on the risk of total limb reduction defects. Those persons with limb reduction defects who had additional defects showed weak but consistent elevated risks in relation to parental occupational pesticide exposure. However, isolated cases of limb reduction defects were negatively related to these exposures. Residence in a farming or high pesticide use county was not associated with any type of limb reduction defect.

CONCLUSIONS

Cases of limb reduction defect with additional malformations appear to be associated with parental occupational pesticide exposure. Improving exposure classifications and subdividing the limb reduction defects by types in the analyses are suggested for future research.

Structure-activity relationships among monoterpene inhibitors of protein isoprenylation and cell proliferation

The monoterpene d-limonene inhibits the post-translational isoprenylation of p21ras and other small G proteins, a mechanism that may contribute to its efficacy in the chemoprevention and therapy of chemically induced rodent cancers. In the present study, the relative abilities of 26 limonene-like monoterpenes to inhibit protein isoprenylation and cell proliferation were determined. Many monoterpenes were found to be more potent than limonene as inhibitors of small G protein isoprenylation and cell proliferation. The relative potency of limonene-derived monoterpenes was found to be: monohydroxyl = ester = aldehyde > thiol > acid = diol = epoxide > triol = unsubstituted. All monoterpenes that inhibited protein isoprenylation did so in a selective manner, such that 21-26 kDa proteins were preferentially affected. Perillyl alcohol, one of the most potent terpenes, reduced 21-26 kDa protein isoprenylation to 50% of the control level at a concentration of 1 mM, but had no effect on the isoprenylation of 67, 47 or 17 kDa proteins. In particular, p21ras farnesylation was inhibited 40% by 1 mM perillyl alcohol. At the same concentration, perillyl alcohol completely inhibited the proliferation of human HT-29 colon carcinoma cells. The structure-activity relationships observed among the monoterpene isoprenylation inhibitors support a role for small G proteins in cell proliferation, and suggest that many limonene-derived monoterpenes warrant further investigation as antitumor agents.

Finding noncommunicating sets for Markov chain Monte Carlo estimations on pedigrees

Markov chain Monte Carlo (MCMC) has recently gained use as a method of estimating required probability and likelihood functions in pedigree analysis, when exact computation is impractical. However, when a multiallelic locus is involved, irreducibility of the constructed Markov chain, an essential requirement of the MCMC method, may fail. Solutions proposed by several researchers, which do not identify all the noncommunicating sets of genotypic configurations, are inefficient with highly polymorphic loci. This is a particularly serious problem in linkage analysis, because highly polymorphic markers are much more informative and thus are preferred. In the present paper, we describe an algorithm that finds all the noncommunicating classes of genotypic configurations on any pedigree. This leads to a more efficient method of defining an irreducible Markov chain. Examples, including a pedigree from a genetic study of familial Alzheimer disease, are used to illustrate how the algorithm works and how penetrances are modified for specific individuals to ensure irreducibility.

Stability of cataplexy over several months--information for the design of therapeutic trials

Twenty-seven narcoleptic patients severely affected with cataplexy completed four symptom diaries over a 4-month period in order to clarify some of the controversies surrounding assessment of anticataplectic medications. The home diary method was found to be a viable model for the assessment of anticataplectic activity. Assessment of reliability in 1-, 2-, 3-, 4-, 5- and 10-day intervals indicated that reliability increases with the number of days included. A 10-day design was found to be optimal. Reliability decreased, however, with each successive diary over the 4-month period. Power analysis indicates that two groups of 30-40 subjects in a parallel design, or one group of 30-40 subjects in a crossover design, would be sufficient to demonstrate a significant therapeutic anticataplectic effect in most cases. A "first diary effect" was observed, suggesting that a training period prior to the actual trial might improve reliability. Whether the patient was treated or untreated with stimulant medications did not affect severity or fluctuation of cataplexy, suggesting that both groups of patients could be included in therapeutic trials. No time-of-day fluctuation was observed in the daily distribution of cataplexy attacks. Sudden increases in cataplexy were often, although not always, caused by unusual emotional events or sleepiness. The finding of a long-lasting "precataplectic" feeling or "aura" pointed to the need to carefully clarify the symptom prior to beginning a therapeutic trial.

Time-resolved fluorescence and absorption spectroscopy of photosystem I

Picosecond fluorescence and femtosecond transient absorption spectroscopy have been used to investigate the primary energy transfer and trapping processes in a photosystem II deletion mutant from the cyanobacterium Synechocystis sp. PCC 6803, which contains active photosystem I reaction centers with approximately 100 chlorophylls per P700. In all experiments, low levels of excitation were used which avoid annihilation processes. Following 590-nm excitation, at room temperature, spectral equilibration is observed in both fluorescence and absorption measurements and is characterized by a time constant of 4-6 ps. The shape of the spectra associated with the equilibration process indicates that long wavelength pigments (pigments with absorption maxima at longer wavelength than that of the primary electron donor, P700) are present and functional at physiological temperatures in this preparation. The overall decay of excitations in the antenna is characterized by a time constant of 24-28 ps, in both fluorescence and absorption measurements. The 24-28-ps process results in the appearance of absorption changes associated with only P700+ formation. Absorption changes associated with the reduction of the primary electron acceptor were not resolved under the experimental conditions used here.

Observation of the reduction and reoxidation of the primary electron acceptor in photosystem I

Femtosecond transient absorption spectroscopy has been used to investigate the primary charge separation in a photosystem II deletion mutant from the cyanobacterium Synechocystis sp. PCC 6803. These cells contain only the photosystem I reaction center and have a pigment content of approximately 100 chlorophylls per P700. Utilizing relatively high excitation intensities, the difference spectrum for the reduction of primary electron acceptor [(A0(-)-A0) difference spectrum] was obtained from experiments performed under both reducing and oxidizing conditions. Both approaches yield very similar results with the (A0(-)-A0) difference spectrum displaying a maximum bleaching at 687 nm. The shape of the difference spectrum suggests that the primary electron acceptor in photosystem I may be a chlorophyll a molecule. The observed rate of primary radical pair formation depends on the overall rate of decay of excitations in the antenna; the radical pair state forms as the antenna decays. The decay of the primary radical pair state is characterized by a 21-ps time constant. Under conditions that avoid annihilation effects, the mean lifetime for excitations in the antenna is 28 ps [Hastings, G., Kleinherenbrink, F.A.M., Lin, S., & Blankenship, R.E. (1994) Biochemistry (preceding paper in this issue)]. This indicates that the reduced acceptor decays faster than it forms. Therefore, only a low concentration of the reduced acceptor will accumulate under most conditions.

Bovine pancreatic deoxyribonuclease F: isoelectric focusing, peptide mapping and primary structure

DNAase F is a minor isoform of bovine pancreatic DNAase which can be separated from the other isoforms (DNAases A, B, C and D) present in a commercial preparation by a preparative isoelectric-focusing cell (Rotofor; Bio-Rad). The ampholytes and other contaminating proteins present in DNAase F preparations can be removed by chromatography on an affinity column (Cibacron Blue 3GA-agarose) and a hydrophobic-interaction column (phenyl-Sepharose CL-4B). The complete separation of DNAase F from the other isoforms is demonstrated on a thin-layer isoelectric-focusing gel, DNAase F being the most basic (pI 5.68). A procedure is described for tryptic peptide mapping by h.p.l.c. requiring only picomolar amounts of DNAase F protein. The DNAase F map shows two peptide peaks not present in the DNAase A map, and the DNAase F map does not have a peak at the position where a C-terminal peptide of DNAase A is normally eluted. The amino acid compositions and sequences for the two new peptides suggest that Gly240 in DNAase A is changed to Arg240 in DNAase F.

Time-resolved spectroscopy of energy and electron transfer processes in the photosynthetic bacterium Heliobacillus mobilis

The kinetics of excitation energy transfer and electron transfer processes within the membrane of Heliobacillus mobilis were investigated using femtosecond transient absorption difference spectroscopy at room temperature. The kinetics in the 725- to 865-nm region, upon excitation at 590 and 670 nm, were fit using global analysis. The fits returned three kinetic components with lifetimes of 1-2 ps and 27-30 ps, and a component that does not decay within several nanoseconds. The 1- to 2-ps component is attributed to excitation equilibration to form a thermally relaxed excited state. The 27- to 30-ps phase corresponds to the decay of the relaxed excited state to form a charge-separated state. The intrinsic energy and electron transfer rates were estimated using the experimental results and theoretical models for excitation migration and trapping dynamics. Taking into account the number of antenna pigments and their spectral distribution, an upper limit of 1.2 ps for the intrinsic time constant for charge separation in the reaction center is calculated. This upper limit corresponds with the trapping-limited case for excitation migration and trapping. Reduction of the primary electron acceptor A0 was observed in the 640 to 700 nm region using excitation at 780 nm. An instantaneous absorbance increase followed by a decay of about 30 ps was observed over a broad wavelength region due to the excited state absorption and decay of BChl g molecules in the antenna. In addition, a narrow bleaching band centered at 670 nm grows in with an apparent time constant of about 1.0 ps, superimposed on the 30-ps absorbance increase due to excited state absorption. Measurements on a longer time scale showed that besides the 670 nm pigment a BChl g molecule absorbing near 785 nm may be involved in the primary charge separation, and that this pigment may be in equilibrium with the 670 nm pigment. The bleaching bands at 670 nm and 785nm recovered with a time constant of about 600 ps, due to forward electron transport to a secondary electron acceptor. Energy and electron transfer properties of H. mobilis membranes are compared with Photosystem 1, to which the heliobacteria bear an evolutionary relationship.

DNA helical instability facilitates initiation at the SV40 replication origin

Previous analysis of mutations in bacterial and yeast replication origins has identified a genetic component, termed a DNA unwinding element (DUE), whose intrinsic helical instability is essential for origin function. For the SV40 replication origin, we show here that the early palindrome (EP) and A + T-rich (AT) domains both exhibit helical instability, despite their dissimilar A + T compositions. To test the possible contribution of helical instability to SV40 origin function, the relationship between helical stability of mutant origin sequences and their known origin activity in vitro and in vivo was examined. Origin activity correlates inversely with the helical stability of mutations within the EP domain but not the AT domain or the T-antigen binding domain. The quantitative correlation holds for four different measures of origin activity determined in vitro and in vivo. An even better-correlated collection of mutations was found in a specific portion of the EP domain. This specific EP subdomain coincides with the sequence known to be strand-separated after T-antigen binds the origin in vitro and with the origin of bidirectional replication in vivo. Our analysis of origin mutations indicates that the helical instability of the specific EP subdomain is required to facilitate T-antigen-induced melting and the initiation of DNA replication. The sensitivity of the required EP subdomain to mutations that stabilize the DNA helix defines the DUE of the SV40 replication origin.

lacZ expression in germline transgenic zebrafish can be detected in living embryos

Use of transgenic technology in zebrafish has been limited by the inability to efficiently express transgenes in early embryos of F1 and subsequent generations and to rapidly detect transgenic fish. We generated transgenic fish by injecting fertilized eggs with the Escherichia coli lacZ gene under the control of the Xenopus elongation factor 1 alpha transcriptional regulatory element. Four of five lines of transgenic fish we obtained express the lacZ gene in early embryos. The pattern of expression was distinct for each line, with two lines showing extensive expression beginning at approximately the midblastula transition, one showing patchy expression and one showing expression almost exclusively in motor neurons. Expression patterns were stable through the F2 generation in the three lines studied to date. The availability of these lines facilitated the development of a reliable and rapid method for live-staining lacZ-expressing embryos using the substrate fluorescein-di-beta-D-galactopyranoside (FDG). Positive embryos of the two most highly lacZ-expressing lines could be identified after 2-3 min of staining in FDG and then picked out and raised. These observations should prove useful for a variety of studies in zebrafish.

Government size, demographic changes, and economic growth

"This paper examines the effect of government size on the growth rate of per capita output by incorporating demographic variables. Evidence from more than 86 countries suggests that the demographic variables not only affect economic growth, but also determine the size of government. Both the young and the old age dependency ratios were positively related to the size of government, while population density and population size were negatively related to the size of government. Moreover, when the demographic variables are included in the growth equations, the effect of government size on the growth rate of per capita output became insignificant rather than, as prior studies showed, significantly negative."

Shape, volume, and content of the deglutitive pharyngeal chamber imaged by ultrafast computerized tomography

BACKGROUND

Conventional radiographic techniques image only the silhouettes of the deglutitive pharyngeal chamber. This study aimed to accurately image the horizontal plane shape and content of the pharynx during swallowing.

METHODS

Dynamic computerized tomography images of the pharynx were obtained at the rate of 17 per second during swallowing. Multiple adjacent levels were imaged in eight subjects and a single level was scanned in four subjects during swallows of varied volume. Images were analyzed for area, volume, and the bolus fraction of the deglutitive pharyngeal chamber.

RESULTS

The deglutitive chamber enlarged to approximately 24 mL (during tongue loading) compared with a preswallow pharyngeal volume averaging 15 mL. Throughout the 10 mL swallows, the bolus occupied less than 30% of the lumen regardless of axial level. The bolus fraction of the deglutitive chamber increased with swallow volume, as did the dimensions of the upper esophageal sphincter and the bolus velocity through the upper esophageal sphincter.

CONCLUSIONS

The deglutitive pharyngeal chamber was typically approximately 15 mL > the bolus volume, implying that an obligatory 15 mL of air was swallowed under these test conditions. Most swallowed air originated as air trapped within the pharynx and larynx as the oropharynx was sealed from above and below.

Improved model of optical fuzzy associative memory

A new learning algorithm of fuzzy associative memory is proposed. Optical implementation of a fuzzy associative memory network is presented, and experimental results are given.

Modulation of tensin and vimentin expression in chick embryo developing cartilage and cultured differentiating chondrocytes

It has been proposed that tensin, in association with several other proteins, mediates the micro-filament-integrin link. Here we describe the isolation of clones spanning about 5 kb from the 3' end of tensin mRNA from cultured chick embryo chondrocyte and embryonic heart cDNA libraries. Tensin expression was investigated in cultured chick embryo cells. It was observed that tensin expression is dependent upon substrate adhesion and it is turned off after 7 days of suspension culture. This process is reversible. Tensin expression is also regulated during cartilage cell differentiation in vivo; at Hamburger and Hamilton stage 39-40, non-hypertrophic tibial chondrocytes express both RNA and protein while hypertrophic chondrocytes do not. In the culture system the expression of vimentin, a major component of intermediate filaments, showed an opposite behaviour since the suspension culture enhances the accumulation of both vimentin and its mRNAs. Therefore in chick embryo cultured chondrocytes and in vivo, during cartilage development, cell shape changes and/or integrin-extracellular matrix protein interactions may be involved in the regulation of these two genes coding for cytoskeletal proteins.

Pharmacological evaluation of iodo and nitro analogs of delta 8-THC and delta 9-THC

One aspect of cannabinoid structure-activity relationships (SARs) that has not been thoroughly investigated is the aromatic (A) ring. Although halogenation of the side chain enhances potency, our recent observation that iodination of the A ring also enhanced activity was surprising. The purpose of this investigation was to establish the steric and electrostatic requirements at these sites of the cannabinoid molecule via molecular modeling, while determining pharmacological activity. Molecular modeling was performed using the Tripos molecular mechanics force field and the semiempirical quantum mechanical package AM1. The Ki values for novel cannabinoids were determined in a [3H]CP-55,940 binding assay and ED50 values generated from four different evaluations in a mouse model. The present studies underscore the increase in potency produced by a dimethylheptyl (DMH) side chain. Trifluoro substitutions on the pentyl side chain, or bromination of the DMH side chain, had little effect on the pharmacological activity. Any substitution at the C4 position of the aryl ring resulted in a loss of activity, which appears to be due to steric hindrances. Nitro, but not iodo, substitution at the C2 position essentially produces an inactive analog, and the drastic alteration of the electrostatic potential appears to be responsible. The altered pharmacological profile of the 2-iodo analog seems to be related to an alteration in the highest occupied molecular orbital because there is no alteration in the electron density map compared to delta 8-tetrahydrocannibinol.

Phase I trial with pharmacokinetic analyses of high-dose carboplatin, etoposide, and cyclophosphamide with autologous bone marrow transplantation in patients with refractory germ cell tumors

Thirty patients with cisplatin-refractory germ cell tumor were treated with high-dose carboplatin, etoposide, and cyclophosphamide and autologous bone marrow transplantation. The total dose of carboplatin was 1500 mg/m2, etoposide 1200 mg/m2, and cyclophosphamide was increased by increments from 60 to 150 mg/kg. Twenty-five cycles of treatment, given to 17 patients, did not include granulocyte-colony stimulating factor (G-CSF). Nineteen cycles of high-dose chemotherapy, given to 13 patients at the 2 highest dose levels of cyclophosphamide, included G-CSF. The dose of cyclophosphamide was escalated to 150 mg/kg/cycle without prohibitive toxicity. The use of G-CSF resulted in a shorter duration of neutropenia (P = 0.07); the median number of days until the recovery of an absolute granulocyte count > 0.5 was 25 without G-CSF and 14 with G-CSF. The most frequent nonhematological toxicity was hepatic, and there were 2 (7%) treatment-related deaths. Thirteen (43%) patients achieved a complete response, and 8 are alive and free of disease (27%); 7 are in continuous complete response (23%), and 1 after resection of a solitary site of disease following a relapse after high-dose chemotherapy. Five patients had pharmacology studies performed to determine the area under the curve (AUC) of free and total platinum, carboplatin, etoposide, cyclophosphamide, and phosphoramide mustard. There was a decrease in the AUC of cyclophosphamide and an increase in the AUC of phosphoramide mustard, the "active" metabolite, with successive days of treatment. The interpatient variability of the AUC of cyclophosphamide/phosphoramide mustard that was demonstrated was most likely a result of each individual's metabolic capacity. The measured AUC of carboplatin and/or free platinum closely approximated the predicted AUC of carboplatin calculated by renal function in 3 of the 5 patients. In summary, cyclophosphamide administered at a dose of 50 mg/kg x 3 days was achieved with acceptable toxicity, and no further dose escalation is planned. High-dose carboplatin, etoposide, and cyclophosphamide achieved a 23% continuous complete response proportion (27% alive, free of disease) when used as third-line therapy in germ cell tumor patients refractory to cisplatin + ifosfamide-based chemotherapy. Ongoing studies are addressing the role of high-dose carboplatin-containing chemotherapy in previously untreated patients with poor prognostic features or as a part of first-line salvage.

In vitro and in vivo testing of the dopamine D1 ligand [123I]SCH 23982 with respect to its potential application in SPET investigations

[123I]SCH 23982, a dopamine D1 ligand, was labelled in a large scale process and then tested in vitro for binding to rat brain sections and membranes. Because of the promising values of KD = 1.5 x 10(-10) M and Bmax = 0.7 x 10(-11) mol/g, in vivo evaluation was performed on rats and normal volunteers to test its possible usefulness for SPET imaging. In competition experiments, a higher binding in the presence of sulpiride was found while ketanserin displaced [123I]SCH 23982 only at a 10,000-fold excess. Differences between rats and men were seen with respect to their metabolism. SPET investigations failed because the washout of [123I]SCH 23982 was too rapid.

GaAs optoelectronic neuron arrays

A simple optoelectronic circuit integrated monolithically in GaAs to implement sigmoidal neuron responses is presented. The circuit integrates a light-emitting diode with one or two transistors and one or two photodetectors. The design considerations for building arrays with densities of up to 10(4) cm(-2) are discussed.

Phase II trial of postoperative adjuvant intraperitoneal cisplatin and fluorouracil and systemic fluorouracil chemotherapy in patients with resected gastric cancer

PURPOSE

This study was performed to assess the short- and long-term toxicities and the impact on relapse pattern and survival of postoperative intraperitoneal (IP) cisplatin and fluorouracil (FU) plus systemic intravenous (IV) FU as adjuvant therapy for gastric cancer patients who are at high risk for recurrence after potentially curative resection (T2N1-2M0 or T3-4N(any)M0).

PATIENTS AND METHODS

Starting 14 to 28 days after potentially curative resection of primary gastric cancers, 35 patients were given IP cisplatin 25 mg/m2 and FU 750 mg daily for 4 days; FU 750 mg/m2 was concurrently given as a continuous 24-hour i.v. infusion. Five cycles of therapy delivered at 1-month intervals were used.

RESULTS

After a median follow-up of 24 months, 51% of patients remain alive and free of disease. Sixteen patients have recurred; 13 of 16 had an intraabdominal component, whereas three had extraabdominal failure only. Two major treatment-related toxicities were noted: neutropenia and a late toxicity of peritoneal fibrosis (sclerosing encapsulating peritonitis [SEP]). There was one postoperative death. Eleven patients underwent second laparotomy: five patients had SEP, two patients had bowel obstruction from adhesions unrelated to SEP, and four patients had recurrent cancer. Potential causes of SEP included an alkaline pH of infused FU and cisplatin that possibly led to activation of cisplatin before infusion.

CONCLUSION

IP cisplatin and FU and concurrent systemic FU is a tolerable adjuvant therapy in the postoperative setting for patients with resected gastric cancer. The recommended dosage schedule with this technique is cisplatin 25 mg/m2 and FU 750 mg total dose IP with FU 500 mg/m2 as a continuous 24-hour infusion daily for days 1 to 4. SEP as a late toxicity, which was observed in 15% of patients, is treatable by surgical lysis of adhesions.

Evaluation of congenital limb reduction defects in upstate New York

Limb reduction defects (LRD), reported to the Congenital Malformations Registry in upstate New York between 1983-1987, were investigated in terms of LRD classification, parental demographics, and LRD characteristics. After excluding LRD with chromosome abnormalities, we followed guidelines developed by the European Congenital Anomaly Surveillance Consortium (EUROCAT) to classify 271 LRD into six groups based on similar patterns of embryological failure. The descriptive analysis indicated a prevalence of 0.45 per 1,000 births (stable over 5 years) for LRD diagnosed during the first 2 years of life. Among 271 LRD cases, 95 were classified as terminal transverse (35.1%), 71 as split limbs (26.2%), 36 as preaxial (13.3%), 32 as postaxial (11.8%), 26 as intercalary (9.6%), and 11 as multiple types (4.1%). In cases with multiple limb involvement (28.4%), two thirds had the same type of LRD in each limb. The multiple types and preaxial groups showed the most distinctive characteristics: they had the highest frequency of suspected syndromes, other birth defects, and syndactyly compared to the other LRD. There were no significant differences in the distribution of demographic variables among different LRD types. Consideration of the incidence and characteristics of LRD by classifying them into these distinct subgroups may be useful for evaluating possible mechanisms of malformation.

Deglutitive tongue action: volume accommodation and bolus propulsion

BACKGROUND

Swallow function is best analyzed in components because discrete component failure may be compensated for with devised maneuvers, postures, or biofeedback techniques. The present investigation examined normal deglutitive tongue function.

METHODS

Biplane videofluoroscopy synchronized with intraluminal manometry was performed in eight volunteers. Tongue surface motion was characterized as centripetal or centrifugal along seven equiangular rays emanating from the tongue center during 1-, 5-, 10-, and 20-mL swallows.

RESULTS

The tongue perimeter remained in contact with the alveolar ridge while the central groove exhibited centripetal and subsequent centrifugal motion that, in conjunction with the pharyngeal walls, created an oropharyngeal propulsive chamber and then expelled that chamber's contents into the hypopharynx. Intrabolus propulsive pressure was generated when the initially expansive propulsive chamber volume contracted to the test bolus volume. Because pharyngeal chamber action cycle timing was relatively constant among bolus volumes, vigorous expulsion occurred with large volumes but relatively delayed, sluggish expulsion occurred with smaller volumes.

CONCLUSIONS

Deglutitive tongue functions include bolus containment, volume accommodation, and the major contributor to bolus propulsion.

[Mitochondrial DNA polymorphism of cattle (Bos taurus) and mithun (Bos frontalis) in Yunnan Province]

An analysis of cleavage patterns of mtDNA by restriction endonuclease was performed for fifteen Yunnan native cattle, two Kunming black and white cow, and one mithun (Bos frontalis). Two types of mtDNA molecule were detected in Yunnan native cattle: five individuals showed the type of yellow cattle (Bos taurus), the other ten showed that of zebu cattle (Bos indicus), suggesting their European and zebu origins. The mtDNA in Kunming black and white cow also consists of two restriction types. The mithun mtDNA showed the type of zebu cattle, indicating the close relationship between the origins of mithun and zebu cattle.

Achieving irreducibility of the Markov chain Monte Carlo method applied to pedigree data

Markov chain Monte Carlo (MCMC) methods have been explored by various researchers as an alternative to exact probability computation in statistical genetics. The objective is to simulate a Markov chain with the desired equilibrium distribution. If the transition kernel is aperiodic and irreducible, then convergence to the equilibrium distribution is guaranteed; realizations of the Markov chain can thus be used to estimate desired probabilities. Aperiodicity is easily satisfied, but, although it has been shown that irreducibility is satisfied for a diallelic locus, reducibility is a potential problem for a multiallelic locus. This is a particularly serious problem in linkage analysis, because multiallelic markers are much more informative than diallelic markers and thus highly preferred. In this paper, the authors propose a new algorithm to achieve irreducibility of the Markov chain of interest by introducing an irreducible auxiliary chain. The irreducibility of the auxiliary chain is obtained by assigning positive probabilities to a small subset of the genotypic configurations inconsistent with the data, to bridge the gap between the irreducible sets.

Monte Carlo analysis on a large pedigree

Monte Carlo methods for linkage and segregation analysis are applied to the HGAR1 pedigree. To address these data, the methods are extended in several ways. The results are compared with those provided by PAP.

A new class of B/W halftoning algorithms

A new class of dithering algorithms for black and white (B/W) images is presented. The basic idea behind the technique is to divide the image into small blocks and minimize the distortion between the original continuous-tone image and its low-pass-filtered halftone. This corresponds to a quadratic programming problem with linear constraints, which is solved via standard optimization techniques. Examples of B/W halftone images obtained by this technique are compared to halftones obtained via existing dithering algorithms.

Noncontiguous injuries of the spine

A total of 372 consecutive spinal injury patients were evaluated at the Regional Spinal Cord Injury Center of Delaware Valley. Of these, 39 patients (10.5%) were found to have noncontiguous spinal column injuries. Fewer than half of the patients in our series could be classified into previous classification systems (Calenoff, Gupta) of noncontiguous spinal fractures. Fifteen fractures in 12 patients were missed on presentation on admission and 25% of these patients had a progressive neurologic deficit as a result of improper initial immobilization. The location of missed fractures were found to be primarily at the extremes or junctures of the spine (i.e., cervicothoracic, thoracolumbar). Complete spinal roentgenographic evaluation is recommended in the workup of suspected spinal column injury patients, and additional imaging modalities (i.e., tomograms, computed tomography scans, and magnetic resonance imaging) may be necessary in those areas of the spine difficult to visualize.

Processing of surfactant protein B proprotein by a cathepsin D-like protease

Surfactant protein B (SP-B) is a hydrophobic peptide of relative molecular weight (M(r)) = 8,000 that is associated with pulmonary surfactant phospholipids. SP-B is synthesized by the alveolar type II epithelial cell as a proprotein of M(r) = 42,000 which requires at least two proteolytic cleavages to generate the 79 residue mature SP-B peptide. We have previously reported that cleavage of the NH2-terminal propeptide, to generate a processing intermediate of M(r) = 25,000, occurs in close temporal approximation to secretion. In the present study we demonstrate that SP-B proprotein, isolated from stably transfected Chinese hamster ovary cells, is processed to M(r) = 25,000 by a crude type II cell membrane fraction but not by intact type II cells or type II cell conditioned media. In vitro processing of the proprotein by the type II cell membrane preparation resulted in release of a single peptide of M(r) = 16,000-17,000, which was detected by antiserum directed against antigenic epitopes in propeptide of the precursor. SP-B processing activity was extracted by Na2CO3 lysis of the type II cell membrane preparation, had a pH optimum of 5.0-6.0, and was inhibited by 10(-7) M pepstatin A, suggesting that the NH2-terminal peptide of the precursor is cleaved by an aspartyl protease. Consistent with this hypothesis, processing of SP-B by a crude type II cell membrane preparation was blocked by antiserum directed against the aspartyl protease cathepsin D; further, purified cathepsin D efficiently processed the SP-B precursor to M(r) = 25,000. Collectively these results suggest that cleavage of the NH2-terminal propeptide of the SP-B precursor is mediated by cathepsin D or a cathepsin D-like protease localized within the secretory pathway of the type II epithelial cell.

Pharyngeal clearance during swallowing: a combined manometric and videofluoroscopic study

The deglutitive pharyngeal contraction was analyzed using simultaneous videofluoroscopic and manometric studies of eight volunteers. Anterior, posterior, and longitudinal movements of the pharyngeal surfaces, relative to the cervical vertebrae, were measured during swallows of 5 and 10 mL of liquid barium. Profound pharyngeal shortening during bolus transit through the pharynx eliminated access to the larynx and elevated the upper esophageal sphincter to within 1.5 cm of the retrolingual pharynx. Bolus head movement through the pharynx preceded the propagated pharyngeal contraction and registered manometrically as a slight intrabolus pressure before the major pressure complex. Contraction in the horizontal plane began after bolus head transit and culminated with stripping of the bolus tail through the pharynx. Prolonged upper sphincter opening with the larger-volume swallows resulted from a delayed onset rather than altered propagation of the horizontal pharyngeal contraction. It is concluded that the propagated pharyngeal contraction facilitates pharyngeal clearance but has a minimal role in the process of bolus propulsion during swallowing. The propagated contraction works in concert with profound pharyngeal shortening to minimize hypopharyngeal residue after a swallow.

Large scale preparation strategy for labelling of [123I]-SCH 23982, a dopamine D1 receptor binding agent

The labelling of the D1 antagonist SCH 23982 with 123I was studied in detail by following the nucleophilic and electrophilic approaches and the reaction conditions were optimized. The product was purified by reversed phase HPLC with a phosphoric acid/EtOH mixture which simply has to be neutralized and diluted before injection. Its binding was tested in vitro with rat striatal membranes proving the high affinity to D1 and very low affinity to D2 receptors.

Production of germ-line chimeras in zebrafish by cell transplants from genetically pigmented to albino embryos

To determine whether embryonic cells transplanted from one zebrafish embryo to another can contribute to the germ line of the recipient, and to determine whether pigmentation can be used as a dominant visible marker to monitor cell transplants, we introduced cells from genetically pigmented (donor) embryos to albino recipients at midblastula stage. By 48 hr many of the resulting chimeras expressed dark pigment in their eyes and bodies, characteristics of donor but not albino embryos. By 4-6 weeks of age pigmentation was observed on the body of 23 of 70 chimeras. In contrast to fully pigmented wild-type fish, pigmentation in chimeras appeared within transverse bands running from dorsal to ventral. Pigmentation patterns differed from one fish to another and in almost every case were different on each side of a single fish. At 2-3 months of age chimeras were mated to albino fish to determine whether pigmented donor cells had contributed to the germ line. Of 28 chimeric fish that have yielded at least 50 offspring each, 5 have given rise to pigmented progeny at frequencies of 1-40%. The donor cells for some chimeras were derived from embryos that, in addition to being pigmented, were transgenic for a lacZ plasmid. Pigmented offspring of some germ-line chimeras inherited the transgene, confirming that they descended from transplanted donor cells. Our ability to make germ-line chimeras suggests that it is possible to introduce genetically engineered cells into zebrafish embryos and to identify the offspring of these cells by pigmentation at 2 days of age.

The vaccinia virus B1R gene product is a serine/threonine protein kinase

The nucleotide sequence of the vaccinia virus open reading frame B1 predicts a polypeptide with significant sequence similarity to the catalytic domain of known protein kinases. To determine whether the B1R polypeptide is a protein kinase, we have expressed it in bacteria as a fusion with glutathione S-transferase. Affinity-purified preparations of the fusion protein were found to undergo autophosphorylation and also phosphorylated the exogenous substrates casein and histone H1. Mutation of lysine 41 to glutamine within the conserved kinase catalytic domain II abrogated protein kinase activity on all three protein substrates, supporting the notion that the protein kinase activity is inherent to the B1R polypeptide. Casein and histone H1 were phosphorylated on serine and threonine residues. The B1R fusion protein was phosphorylated on a threonine residue(s) by an apparently intramolecular mechanism. The autophosphorylation reaction resulted in phosphorylation of the glutathione S-transferase portion of the fusion and not the protein kinase domain. The protein kinase activity of B1R was specific for ATP as the phosphate donor; GTP was not utilized to a detectable extent. Immunoblotting experiments with anti-B1R antiserum showed that the protein kinase is located in the virion particle. Chromatography of virion extracts resulted in separation of the B1R protein kinase from the bulk of the total protein kinase activity, indicating that multiple protein kinases are present in the virion particle and that B1R is distinct from the previously described vaccinia virus-associated protein kinase.

A risk-based prospective payment system that integrates patient, hospital and national costs

We suggest that a desirable form for prospective payment for inpatient care is hospital average cost plus a linear combination of individual patient and national average cost. When the coefficients are chosen to minimize mean squared error loss between payment and costs, the payment has efficiency and access incentives. The coefficient multiplying patient costs is a hospital specific measure of financial risk of the patient. Access is promoted since providers receive higher reimbursements for risky, high cost patients. Historical cost data can be used to obtain estimates of payment parameters. The method is applied to Medicare data on psychiatric inpatients.

[Endothelin and acute renal failure: study on their relation and possible mechanisms]

In order to investigate the role of endothelin in the pathogenesis of ARF, we determined the plasma endothelin (pET) level in different clinical ARF patients and experimental ARF rat models. It was found that pET level was significantly higher in hepatic renal syndrome (n = 9, pET 210.1 +/- 32.0 pg/ml), epidemic hemorrhagic fever (n = 18, 113.3 +/- 14.86 pg/ml), septic shock ARF (n = 8, 121.5 +/- 13.5 pg/ml), gentamicin ARF (n = 7, 55.9 +/- 6.23 pg/ml) patients, and in HgCl2 ARF (n = 8, 31.75 +/- 3.07 pg/ml), glycerine ARF (n = 8, 44.75 +/- 9.8 pg/ml) rats, compared with that of normal persons (n = 9, 33.6 +/- 3.08 pg/ml) or of normal rats (n = 10, 11.4 +/- 0.98 pg/ml). Both in the patients and animal groups, there were a linear relationship between the levels of pET and Scr (r = 0.603 4 and 0.844, P less than 0.01, respectively). Intrarenal infusion ET in dosage of 0.16 micrograms.kg-1/h produced a severe reduction of RPF and GFR in the infused kidney, without significant similar changes on the contralateral kidney. Pretreated with captopril ameliorated the renal hemodynamic changes induced by iv ET (0.67 micrograms.kg-1/h), whereas indomethacin potentiated this effect. It is concluded that both circulating or local generated ET during the ARF play an important role in the pathogenesis of ARF. RAS and PG might involve in its mechanisms.