Effect of glucose on the respiratory burst of circulating neutrophils from asthmatics

The respiratory burst is dependent on a source of glucose. We wished to investigate the effect of glucose on the superoxide production of circulating neutrophils. Superoxide production of neutrophils was significantly enhanced by glucose concentration of from 1 to 50 mmole/liter in the medium. The neutrophils from asthmatics in both the acute and remission phases showed greater production of superoxide than those of controls. When the neutrophils were made to undergo the respiratory burst, initially in the absence of glucose, and thereafter in the presence of 5 and 20 mmole/liter glucose, the rate of superoxide formation with higher glucose medium was decreased in the control cells but significantly increased in the cells of the acute asthmatics in remission. It is concluded that glucose as an energy source is potentially critical in determining the rate of the respiratory burst and that the neutrophils from asthmatic subjects in some way have an enhanced uptake or metabolism of this substrate. Glycemic status may then have some role in determining the amount of superoxide production, and therefore airway inflammation, in asthma.

Effect of point mutations on the kinetics and the inhibition of human immunodeficiency virus type 1 protease: relationship to drug resistance

Mutations of human immunodeficiency virus type 1 (HIV-1) protease at four positions, Val82, Asp30, Gly48, and Lys45 were analyzed for the resulting effects on kinetics and inhibition. In these mutants, Val82 was substituted separately by Asn, Glu, Ala, Ser, Asp, and Gln; Asp30 was individually substituted by Phe or Trp; Gly48 by His, Asp, and Tyr, respectively; and Lys45 by Glu. By examination of the inhibition of a single inhibitor, the differences in Ki values between the native and mutant enzymes can range from very large to insignificant even for the mutants with substitutions at the same position. By examination of a single mutant enzyme, the same broad range of Ki changes was observed for a group of inhibitors: Thus, how much the inhibition changes from the wild-type enzyme to a mutant is dependent on both the mutation and the inhibitor. The examination of Ki changes of inhibitors with closely related structures binding to Val82 mutants also reveals that the change of inhibition involves subsites in which Val82 is not in direct contact, indicating a considerable flexibility of the conformation of HIV protease. For the catalytic activities of the mutants, the kcat and Km values of many Val82 mutants and a Lys45 mutant are comparable to the native enzyme. Surprisingly, Gly48 mutations produce enzymes with catalytic efficiency superior to that of the wild-type enzyme by as much as 10-fold. Modeling of the structure of the mutants suggests that the high catalytic efficiency of some substrates is related to an increase of rigidity of the flap region of the mutants. The examination of the relative changes of inhibition and catalysis of mutants suggests that some of the Val82 and Gly48 mutants are potential resistance mutants. However, the resistance is specific with respect to individual inhibitors.

[The diagnostic significance of anti-HCV IgM in chronic hepatitis C viral infection]

The significance of anti-HCV IgM testing in the diagnosis and evaluation of treatment of chronic hepatitis C was studied. The serum samples from 82 patients with chronic hepatitis C were tested for ALT, anti-HCV IgG and IgM and HCV RNA. All the 82 cases were positive for anti-HCV IgG and 51 (62.19%) positive for anti-HCV IgM. The emergence of anti-HCV IgM might be of four types: (1) persistent positive type, 24 (29.26%) cases; (2) intermittent positive type, 8 (9.75%) cases; (3) transient positive type, 19 (23.17%) cases; (4) persistent negative type, 31 (37.80%) cases. Usually there was progressive liver damage in type 1 and 2. If the patients were of transient positive type, they would usually recover. There was a significant correlation between the levels of serum anti-HCV IgM and ALT, while no correlation existed between the levels of serum ALT anti-HCV IgG. It is suggested that in patients with chronic hepatitis C, detection of anti-HCV IgM may be useful for estimating the extent of progressive liver damage and guiding the antiviral therapy.

[Damage effects of methylmercury on cell membrane]

Damage to cell membrane system caused by methylmercury (Me-Hg) and its mechanism were studied with biochemical and cell biological methods experimentally. Results showed erythrocyte membrane and activities of T-ATPase, Mg(++)-ATPase and Na(+)-K(+)-ATPase of microsome membrane in brain, liver and kidney of the exposed animals decreased more significantly than of controls with a dose-effect pattern. Activities of Mg(++)-ATPase and Na(+)-K(+)-ATPase of erythrocyte membrane correlated positively with those of microsome membrane in brain and kidney. Sulfhydryl content of erythrocyte membrane and brain microsome membrane decreased significantly in the exposed animals (P < 0.01). Sulfhydryl content correlated inversely with the activities of above three kinds of ATPase in kidney, but so did in brain positively. Fluorescent polarization of membranes of erythrocytes and microsome in brain, liver and kidney increased, membrane fluidity decreased, LDH activities increased in plasma and decreased in cells and cell permeability increased in the exposed animals. Activities of respiratory enzymes of mitochondrion in exposed animals were lower than those in controls (P < 0.05). 3H-TdR incorporation was inhibited in spleen, liver and brain in exposed animals. Abilities of DNA synthesis and UDS repair were inhibited with high-dose of Me-Hg, and stimulated with low-dose. SCE frequency in bone marrow cells increased with dose of Me-Hg (P < 0.001). Proportion of splenocyte from G0/G1 to S phases increased and those from S to G2/M phases lowered, and it suggested DNA synthesis had been inhibited.

Assignment and calcium dependence of methionyl epsilon C and epsilon H resonances in cardiac troponin C

The 10 Met methyl groups in recombinant cardiac troponin (cTnC) were metabolically labeled with [13C-methyl]Met and detected as 10 individual cross-peaks using two-dimensional heteronuclear single- and multiple-quantum coherence (HSMQC) spectroscopy. The epsilon C and epsilon H chemical shifts for all 10 Met residues were sequence-specifically assigned using a combination of HSMQC and systematic conversion of the Met residues to Leu. The only negative functional consequence of these changes was seen when both Met 45 and 81 were mutated. Binding of Ca2+ to the high affinity C-terminal sites III and IV induced relatively large changes in the epsilon H and epsilon C chemical shifts of all Met residues in the C-terminal domain as well as small but significant changes in the chemical shifts of epsilon H Met 47 and Met 81 in the N-terminal half of cTnC. Binding of Ca2+ to the low affinity N-terminal site II induced large changes in the epsilon H and epsilon C chemical shifts of Met 45, Met 80, and Met 81. Binding of Ca2+ to site II had no effect on the chemical shifts of Met residues located in the C-terminal domain. The nature of the chemical shift changes of Met residues in the N- versus the C-terminal halves of cTnC were consistent with different Ca(2+)-induced conformational changes in these domains. Thus, the assigned methyl Met chemical shifts can serve as useful structural markers to study conformational transitional in free cTnC and potentially after association with small ligands, peptides, and other troponin subunits.

DQB1*0602 and DQA1*0102 (DQ1) are better markers than DR2 for narcolepsy in Caucasian and black Americans

In the present study, we tested 19 Caucasian and 28 Black American narcoleptics for the presence of the human leucocyte antigen (HLA) DQB1*0602 and DQA1*0102 (DQ1) genes using a specific polymerase chain reaction (PCR)-oligotyping technique. A similar technique was also used to identify DRB1*1501 and DRB1*1503 (DR2). Results indicate that all but one Caucasian patient (previously identified) were DRB1*1501 (DR2) and DQB1*0602/DQA1*102 (DQ1) positive. In Black Americans, however, DRB1*1501 (DR2) was a poor marker for narcolepsy. Only 75% of patients were DR2 positive, most of them being DRB1*1503, but not DRB1*1501 positive. DQB1*0602 was found in all but one Black narcoleptic patient. The clinical and polygraphic results for this patient were typical, thus confirming the existence of a rare, but genuine form of DQB1*0602 negative narcolepsy. These results demonstrate that DQB1*0602/DQA1*0102 is the best marker for narcolepsy across all ethnic groups.

Comparative study of reaction centers from purple photosynthetic bacteria: Isolation and optical spectroscopy

Reaction centers from two species of purple bacteria, Rhodospirillum rubrum and Rhodospirillum centenum, have been characterized and compared to reaction centers from Rhodobacter sphaeroides and Rhodobacter capsulatus. The reaction centers purified from these four species can be divided into two classes according to the spectral characteristics of the primary donor. Reaction centers from one class have a donor optical band at a longer wavelength, 865 nm compared to 850 nm, and an optical absorption band associated with the oxidized donor at 1250 nm that has a larger oscillator strength than reaction centers from the second class. Under normal buffering conditions, reaction centers isolated from Rb. sphaeroides and Rs. rubrum exhibit characteristics of the first class while those from Rb. capsulatus and Rs. centenum exhibit characteristics of the second class. However, the reaction centers can be converted between the two groups by the addition of charged detergents. Thus, the observed spectral differences are not due to intrinsic differences between reaction centers but represent changes in the electronic structure of the donor due to interactions with the detergents as has been confirmed by recent ENDOR measurements (Rautter J, Lendzian F, Lubitz W, Wang S and Allen JP (1994) Biochemistry 33: 12077-12084). The oxidation midpoint potential for the donor has values of 445 mV, 475 mV, 480 mV and 495 mV for Rs. rubrum, Rs. centenum, Rb. capsulatus, and Rb. sphaeroides, respectively. Despite this range of values for the midpoint potential, the decay rates of the stimulated emission are all fast with values of 4.1 ps, 4.5 ps. 5.5 ps and 6.1 ps for quinone-reduced RCs from Rs. rubrum, Rb. capsulatus, Rs. centenum, and Rb. sphaeroides, respectively. The general spectral features of the initial charge separated state are essentially the same for the four species, except for differences in the wavelengths of the absorption changes due to the different donor band positions. The pH dependence of the charge recombination rates from the primary and secondary quinones differ for reaction centers from the four species indicating different interactions between the quinones and ionizable residues. A different mechanism for charge recombination from the secondary quinone, that probably is direct recombination, is proposed for RCs from Rs. centenum.

Relationship between rate and free energy difference for electron transfer from cytochrome c2 to the reaction center in Rhodobacter sphaeroides

The rate of electron transfer from cytochrome c2 to the bacteriochlorophyll dimer of the reaction center from the photosynthetic bacterium Rhodobacter sphaeroides has been investigated using time-resolved optical spectroscopy. Measurements were performed on a series of mutant reaction centers in which the midpoint potentials of the bacteriochlorophyll dimer vary over a range of 350 mV. Dramatic changes in the characteristic time of electron transfer were observed, with the measured values ranging from 7730 to 80 ns compared to 960 ns for wild type. The binding constants (0.15 to 0.25 microM-1) and the second-order rate constants for the slow component (5.5 x 10(8) to 9.4 x 10(8) M-1 s-1) for the mutants are similar to the corresponding values for wild type (0.35 microM-1 and 11 x 10(8) M-1 s-1), indicating that the binding of the cytochrome to the reaction center is not changed in the mutants. In the mutants with the fastest rates, an additional minor component was resolved that is probably due to formation of a reaction center-cytochrome complex in an unfavorable configuration with a binding constant an order of magnitude weaker than the major component. The altered midpoint potentials in the mutants result in values for the free energy difference for this electron transfer reaction ranging from -65 to -420 meV compared to -160 meV for wild type. The relationship between the rate and free energy difference was well fit by a Marcus equation using a reorganization energy of 500 meV.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of a novel cDNA encoding a putative membrane receptor with high homology to the cloned mu, delta, and kappa opioid receptors

A rat brain cDNA library was screened for clones homologous to the recently cloned mouse delta-opioid receptor (DOR-1). Among the clones isolated was Hyp 8-1, a clone with a unique nucleotide sequence capable of encoding a putative protein which is 57-58% identical to the amino acid sequences of the cloned delta, mu and kappa opioid receptors, indicating a close relationship of Hyp 8-1 with the opioid receptor family. Several cDNAs representing possible splice variants of Hyp 8-1 were also isolated. Binding studies of COS-7 cells transfected with clone Hyp 8-1 failed to demonstrate specific binding with several 3H-opioid ligands. In situ hybridization studies indicate that the mRNA for Hyp 8-1 is distributed discretely throughout the rat brain, in an overall pattern which is different from that of several other G-protein-coupled seven transmembrane receptors. Thus, it is likely that the Hyp 8-1 cDNA encodes a novel peptide receptor.

Specific alteration of the oxidation potential of the electron donor in reaction centers from Rhodobacter sphaeroides

The effects of multiple changes in hydrogen bond interactions between the electron donor, a bacteriochlorophyll dimer, and histidine residues in the reaction center from Rhodobacter sphaeroides have been investigated. Site-directed mutations were designed to add or remove hydrogen bonds between the 2-acetyl groups of the dimer and histidine residues at the symmetry-related sites His-L168 and Phe-M197, and between the 9-keto groups and Leu-L131 and Leu-M160. The addition of a hydrogen bond was correlated with an increase in the dimer midpoint potential. Measurements on double and triple mutants showed that changes in the midpoint potential due to alterations at the individual sites were additive. Midpoint potentials ranging from 410 to 765 mV, compared with 505 mV for wild type, were achieved by various combinations of mutations. The optical absorption spectra of the reaction centers showed relatively minor changes in the position of the donor absorption band, indicating that the addition of hydrogen bonds to histidines primarily destabilized the oxidized state of the donor and had little effect on the excited state relative to the ground state. Despite the change in energy of the charge-separated states by up to 260 meV, the mutant reaction centers were still capable of electron transfer to the primary quinone. The increase in midpoint potential was correlated with an increase in the rate of charge recombination from the primary quinone, and a fit of these data using the Marcus equation indicated that the reorganization energy for this reaction is approximately 400 meV higher than the change in free energy in wild type. The mutants were still capable of photosynthetic growth, although at reduced rates relative to the wild type. These results suggest a role for protein-cofactor interactions--in particular, histidine-donor interactions--in establishing the redox potentials needed for electron transfer in biological systems.

[Construction of human glioma cDNA library]

Total RNA from a human glioma was extracted by acid guanidinium-thiocyanate-chloroform one step method, and poly(A+)RNA was separated by affinity chromatography on oligo (dT) cellulose. The cDNA was synthesized by using poly (A+) RNA as template, the length of cDNA being 0.2-5 kb. The glioma cDNA inserts could be cloned into lambda gt11 vector, the resulting recombinant DNA was packaged in vitro. The cDNA library of 1.12 x 10(5) pfu/ml was obtained, and the cloning efficiency was 4.8 x 10(3)/ng cDNA. This library might contribute an important basis to study of the structure and function of human glioma genes.

Transformation of human osteoblasts to anchorage-independent growth by insoluble nickel particles

Nickel compounds are well established by epidemiologic studies as human carcinogens. Although the carcinogenicity of nickel compounds has been studied in experimental animals and in a variety of cultured mammalian cells, there are only sporadic reports of nickel-induced transformation of human cells. In attempts to study the mechanisms of nickel-induced carcinogenesis in human cells, an immortalized human osteoblastic cell line (HOS) that could not grow in soft agar or form tumors in athymic nude mouse was repeatedly treated with a water-soluble nickel compound (NiCl2) or a less water-soluble nickel compound crystalline (NiS). After three rounds of NiS treatment, there was an increase in anchorage-independent (AI) colony formation. This was not found in untreated or NiCl2-treated cells. Ten AI colonies obtained from NiS-treated cells were isolated. All of these clones showed changes in cell morphology, including the appearance of uniform polygon shape, growth in multilayers, and heavy staining with Giemsa. Most of these clones were retested for their ability to grow in soft agar and showed growth efficiencies of 5 to 50%. It has been shown by other investigators that aggregate growth is well correlated with tumorigenic potential in viral or chemical transformants of HOS cells. Four of seven tested NiS-transformed clones were able to form large aggregates compared to their untransformed counterparts, and continued to proliferate in aggregate form when they were plated on 0.9% agar. Current investigations focus on the molecular and genetic changes induced by nickel compounds in these human cells.

Engineering aspartic proteases to probe structure and function relationships

Recently, protein engineering has been used to interconvert homodimeric and homologous single-chain aspartic proteases, with some success. The independent folding of the domains of these proteases has also permitted the engineering of domain-rearranged protease zymogens and the use of individual domains as probes for structural denaturation. In addition, site-directed mutagenesis has provided insights into the catalytic mechanism and specificity of this family of proteases.

Time-dependent thermodynamics during early electron transfer in reaction centers from Rhodobacter sphaeroides

The temperature dependence of fluorescence on the picosecond to nanosecond time scale from the reaction centers of Rhodobacter sphaeroides strain R-26 and two mutants with elevated P/P+ midpoint potentials has been measured with picosecond time resolution. In all three samples, the kinetics of the fluorescence decay is complex and can only be well described with four or more exponential decay terms spanning the picosecond to nanosecond time range. Multiexponential fits are needed at all temperatures between 295 and 20 K. The complex decay kinetics are explained in terms of a dynamic solvation model in which the charge-separated state is stabilized after formation by protein conformational changes. Many of these motions have not had time to occur on the time scale of initial electron transfer and/or are frozen out at low temperature. This results in a time- and temperature-dependent enthalpy change between the excited singlet state and the charge-separated state that is the dominant term in the free energy difference between these states. Long-lived fluorescence is still observed even at 20 K, particularly for the high-potential mutants. This implies that the driving force for electron transfer on the nanosecond time scale at low temperature is less than 200 cm-1 (25 meV) in R-26 reaction centers and even smaller on the picosecond time scale or in the high-potential mutants.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Diuretic therapy for hypertension and the risk of primary cardiac arrest

BACKGROUND

The results of trials of the primary prevention of coronary heart disease have suggested that treating hypertension with high doses of thiazide diuretic drugs might increase the risk of sudden death from cardiac causes. In contrast, treatment with low doses of thiazide reduces the risk of coronary heart disease.

METHODS

To examine the association between thiazide treatment for hypertension and the occurrence of primary cardiac arrest, we conducted a population-based case-control study among enrollees of a health maintenance organization. The case patients were 114 persons with hypertension who had a primary cardiac arrest from 1977 through 1990. The control patients were a stratified random sample of 535 persons with hypertension. The patients' treatment was assessed with the use of a computerized pharmacy data base. Records of their ambulatory care were reviewed to determine other clinical characteristics.

RESULTS

The risk of primary cardiac arrest among patients receiving combined thiazide and potassium-sparing diuretic therapy was lower than that among patients treated with a thiazide without potassium-sparing therapy (odds ratio, 0.3; 95 percent confidence interval, 0.1 to 0.7). As compared with low-dose thiazide therapy (25 mg daily), moderate-dose therapy (50 mg daily) was associated with a moderate increase in risk (odds ratio, 1.7; 95 percent confidence interval, 0.7 to 4.5), and high-dose therapy (100 mg daily) was associated with a larger increase in risk (odds ratio, 3.6; 95 percent confidence interval, 1.2 to 10.8) (P value for trend, 0.02). The addition of a potassium-sparing drug to low-dose thiazide therapy was associated with a reduced risk of cardiac arrest (odds ratio, 0.4; 95 percent confidence interval, 0.1 to 1.5).

CONCLUSIONS

Both the dose of thiazide drugs and the addition of potassium-sparing drugs influence the risk of primary cardiac arrest. These results may explain the differences in the effect of antihypertensive therapy on mortality from coronary heart disease in previous clinical trials.

The presence but not the sequence of the N-terminal peptide in cardiac TnC is important for function

The most diverged region of the primary amino acid sequence between cardiac (cTnC) and fast skeletal troponin C is the N-terminal ten amino acids. We report here that major changes in the primary sequence of this region in cTnC had a minimal effect on the ability of the mutant proteins to recover maximal activity in TnC-extracted cardiac and fast skeletal muscle myofibrils. However, deletion of the N-terminal nine amino acids resulted in a 60% decrease in maximal Ca(2+)-dependent ATPase activity with only a small change in the pCa50 of activation. Deletion of the N-terminal peptide did not appear to appreciably affect the Ca(2+)-binding properties of cTnC, but it did alter the interaction with hydrophobic fluorescent probes. Thus, the presence but not the sequence, of the N-terminal extension is important for the maximal activity of cTnC. The N-terminal helix may function in a relatively non-specific manner to prevent unfavorable interactions between domains in cTnC or between cTnC and other troponin subunits.

Nickel-induced transformation of human cells causes loss of the phosphorylation of the retinoblastoma protein

The retinoblastoma (Rb) protein (pRb) has been studied in various crystalline NiS-transformed cell clones derived from the human osteoblast cell line, HOS TE-85. The parental HOS cells were not able to proliferate in soft agar medium, but they acquired this property following treatment with crystalline NiS. The pRb was found only in the hypophosphorylated form in 8 of 9 nickel-transformed clones examined, whereas in the parental cells the pRb appeared in both phosphorylated and unphosphorylated forms. Neither Rb gene expression nor its phosphorylation was affected by acute nickel treatments of HOS cells. The nickel-transformed HOS clones expressed the major regulators of Rb phosphorylation, cyclin E and cdk-2, at levels similar to those of the parental cells. In coimmunoprecipitation assays with cell lysates from the transformed clones that exhibited the hypophosphorylated form of pRb, the Rb protein failed to form a complex with simian virus 40 large T-antigen, indicating a lack of functional activity. When a plasmid containing the normal Rb gene was transfected into these nickel-transformed cells, it restored the Rb phosphorylation pattern observed in parental cells and the cells acquired a normal phenotype (i.e., they were no longer able to grow in soft agar). This suggested that a mutation was induced in nickel-transformed cells that affected the ability of the Rb protein to be phosphorylated and function normally, and this mutation allowed the human nickel-transformed cells to acquire anchorage-independent growth.

NMDA receptor activation in differentiating cerebellar cell cultures regulates the expression of a new POU gene, Cns-1

POU/homeobox genes encode transcription regulatory proteins that are important in defining cellular phenotypes. Expression of these genes may be critical for to the regulation of CNS cellular differentiation. We have identified a cDNA corresponding to a new member of the POU/homeobox gene family. Expression of RNA encoded by this new gene occurs predominantly in the CNS. Thus, this new gene was designated Cns-1. Cns-1 transcripts are expressed in differentiating cells cultured from the early postnatal cerebellum. Treatment of these cultured cells with NMDA results in an increase in the level of Cns-1 RNA. This increase is blocked by simultaneous treatment with the specific NMDA receptor antagonist amino-5-phosphonovaleric acid. Continued activation of the NMDA receptor allows maintenance of this new steady state level of Cns-1 mRNA for at least 5 d in these cultured cells. A transcription runoff assay suggests that this increase in the level of RNA is due, at least in part, to an increase in transcription from the Cns-1 gene. The NMDA-induced increase in Cns-1 mRNA was reduced by pretreatment with calcium chelators EGTA or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) tetrakis(acetoxymethyl). These studies suggest that specific activation of the NMDA receptor in cultures of differentiating cerebellar cells increases Cns-1 gene expression and that calcium entry through the NMDA channel may be required for this response. This change in Cns-1 expression may modify phenotypic characteristics of these cultured cells.

Differences in the metabolism of 18:2n-6 and 18:3n-6 by the liver and kidney may explain the anti-hypertensive effect of 18:3n-6

The present study examined the in vitro and in vivo metabolism of 18:2n-6 and 18:3n-6 by kidney and liver in the male adult spontaneously hypertensive (SHR) and normotensive (WKY) rats. In liver and kidney slices incubated for 1 h with either [1-14C]18:2n-6 or [1-14C]18:3n-6 (60 microM), substantial amounts of radioactivity were incorporated into triacylglycerol and phospholipid fractions. Approximately 15% of the radiolabeled 18:2n-6 was converted into 18:3n-6 in liver slices but no conversion was found in kidney slices. When incubated with radiolabeled 18:3n-6, over 40% of the radioactivity was metabolized mainly to 20:4n-6 in liver slices, but evenly to 20:3n-6 and 20:4n-6 in kidney slices. There were no differences between the results from SHR and those from WKY. In WKY rats given an oral bolus of radiolabeled 18:3n-6, most of the radioactivity was recovered in the liver and significantly less in the kidney. In both tissues, the radioactivity was associated initially only with 18:3n-6 and later with its elongation product, 20:3n-6. These findings indicated that the kidney, although unable to metabolize 18:2n-6, could metabolize 18:3n-6 taken up from the circulation. The effectiveness of 18:3n-6, compared to 18:2n-6, as an anti-hypertensive agent may result from the provision of a post-delta 6-desaturation metabolite which can be directly converted to blood pressure-regulating eicosanoids in the kidney.

[Hepatic ultrasonographic imaging and serum amino acid levels in cured schistosomiasis cases]

Ultrasonography (B mode) of liver and serum amino-acid levels were studied in 15 cases of schistosomiasis japonica who had been cured for more than 5-15 years. Typical B-ultrasonic images of hepatic fibrosis due to schistosomiasis were found in all patients which could be classified into three types, namely, the spotty type (I), the tortoise-shell type (II) and the net-patchy type (III) according to the patterns of echogenic bands. Moderate to marked echogenic thickening of portal vein wall, and dilation of portal and splenic veins were revealed in patients with type II and III images. Free amino acids in sera were determined by using HPLC-AAAS. The result revealed that the concentration of 8 nonessential and 3 essential amino acids (threonine, valine, tryptophan) were significantly decreased in the 15 patients. The ratio of aromatic to aliphatic amino acid was markedly elevated in 3 patients of type III. The serum amino acid imbalance was attributed to the severe hepatic damage and impaired liver function.