Structure and organization of the CyIII actin gene subfamily of the sea urchin, Strongylocentrotus purpuratus

We describe here the organization of the CyIII subfamily of cytoskeletal actin genes in the sea urchin Strongylocentrotus purpuratus. The functional genes CyIIIa and CyIIIb are linked at a 6 X 10(3)-base distance. Gene CyIIIc appears to be a pseudogene that lacks 5' exons and displays unselected mutational changes. Gene CyIIIa codes for a protein that differs at only nine out of 376 residues from that coded by another cytoskeletal actin gene, CyI. However, five of these nine changes occur within an 11-amino acid region that could represent a functional specialization of the CyIIIa actin protein. The CyIIIa gene possesses three introns, located, respectively, 25 nucleotides upstream from the translation start site, between the codons for amino acids 121 and 122, and within the codon for amino acid 204. These intron positions have also been observed in other cytoskeletal sea urchin actin genes. Comparison of both intron and 3'-terminal sequences shows that the CyIIIa and CyIIIb genes are closely related, while no homology in these untranslated sequences is observed between the CyIII genes and the other cytoskeletal actin genes of the S. purpuratus genome. The CyIII genes probably arose by duplication events at least 40 X 10(6) years ago, prior to radiation of the genus Strongylocentrotus. Consideration of the biological role of the embryo and larval aboral ectoderm cells to which CyIIIa and CyIIIb transcripts are confined suggests that these actins might contribute to cytoskeletal elements that endow the larval body wall with its rigid structure.

Detergents as probes of reconstituted rat liver cytochrome P-450 function

A series of 16 ionic, zwitterionic, and nonionic detergents have been used to perturb the catalytic activities of major cytochrome P-450 (P-450) forms from untreated (UT-A), phenobarbital-treated (PB-B) and beta-naphthoflavone-treated (BNF-B) rats in reconstituted systems with NADPH--P-450 reductase Detergent effects on R warfarin hydroxylase activities were correlated with detergent effects on the quaternary structures of P-450 and reductase, and on their 1:1 complexes as determined by gel exclusion chromatography using sodium cholate as a prototype detergent. The detergent concentrations used did not in most cases affect rates of NADPH-dependent reduction of cytochrome c by the reductase. With P-450 BNF-B, ionic and zwitterionic detergents enhanced warfarin hydroxylase activities at low concentrations and produced marked inhibition at higher concentrations, while nonionic detergents only inhibited. With P-450 UT-A, some nonionic and zwitterionic detergents increased rates at low concentrations and inhibited at higher concentrations. P-450 PB-B was inhibited by detergents of all three classes at low and high concentrations. The concentrations of a detergent required to affect 50% inhibition differed for the three P-450s, suggesting, together with the differential susceptibilities to detergent-mediated rate enhancing effects, that the reductase interacts functionally differently with the three P-450s. Chromatographic studies demonstrated that concentrations of sodium cholate which optimally enhanced metabolic rates with P-450 BNF-B facilitated the uptake of the P-450 into the functional reductase/P-450 complex, and higher concentrations of cholate, which completely inhibited activity, produced profound disruptions of the complex. The data have provided insight into the functional interactions required for monooxygenase activity.

Comparison of CT and fiberoptic bronchoscopy in the evaluation of bronchial disease

CT was compared to fiberoptic bronchoscopy in a large series of patients to study the value of CT for visualizing bronchial disease. CT scans were available for review in 64 cases in which focal airway disease was identified with fiberoptic bronchoscopy and in 38 patients in whom the airways appeared normal at bronchoscopy. CT was positive in 59 of 64 cases in which lesions were detected endoscopically. If the results are analyzed according to the extent of involvement of individual bronchi, CT successfully identified 88 (90%) of 98 lesions. CT correctly excluded disease in 35 (92%) of 38 cases that were subsequently verified to be normal by fiberoptic bronchoscopy. In no case was the diagnosis of malignancy missed by CT. While extremely accurate in detecting focal lesions, CT was inaccurate in predicting whether a given abnormality was endobronchial, submucosal, or extrinsic (peribronchial). In three cases CT failed to detect submucosal extension into the left mainstream bronchus, which has important implications concerning the value of CT in staging bronchial malignancy. It is concluded that CT is helpful when bronchoscopy is contraindicated or refused. CT may also be used in selected cases when there is low clinical suspicion of endobronchial disease and as a complementary procedure to fiberoptic bronchoscopy for outlining the exact location of major mediastinal and hilar vessels, lymph nodes, and tumor in relation to adjacent airways.

Identification of an activated c-Ki-ras oncogene in rat liver tumors induced by aflatoxin B1

Weanling male Fischer rats were administered 40 intraperitoneal injections of aflatoxin B1 (25 micrograms per animal per day) over a 2-month period. This chronic dosing regimen resulted in the sequential formation of hyperplastic foci, preneoplastic nodules, and hepatocellular carcinomas in all of the animals treated. The presence of transforming DNA sequences was detected by formation of anchorage-independent foci after transfection of tumor-derived DNA in NIH 3T3 mouse fibroblasts. Transfection of genomic DNA isolated from individual tumors from eight animals resulted in specific transforming activities ranging from 0.05 to 0.2 foci per micrograms of DNA. Primary transfectant DNAs were analyzed by Southern blot hybridization with DNA probes homologous to c-Ha-ras, c-Ki-ras, and N-ras oncogenes. A highly amplified c-Ki-ras oncogene of rat origin was detected in transformants derived from tumors in two of the eight animals tested. There was no evidence to suggest the presence of c-Ha-ras or N-ras sequences in any of the transformants. Analysis of primary liver tumor DNA showed no Ki-ras DNA amplification when compared to control liver DNA samples. Increased levels of c-Ki-ras p21 proteins were detected in 3T3 transformants containing activated rat c-Ki-ras genes. The presence of c-Ki-ras sequences of rat origin capable of inducing transformed foci can be taken as evidence that the c-Ki-ras gene has been activated in the primary liver tumors.

Simultaneous non-parametric confidence intervals for survival probabilities from censored data

In medical studies with censored data Kaplan and Meier's product limit estimator has frequent use as the estimate of the survival function. Simultaneous confidence intervals for the survival function at various time points constitute a useful addition to the analysis. This study compares several such methods. We consider in a simulation investigation two whole curve confidence bands and four methods based on the Bonferroni inequality. The results show that three Bonferroni-type methods are essentially equivalent, all being better than the other methods when the number of time points is small (3 or 5).

Further studies on the biosynthesis of chlorothricin

Feeding experiments with [U-13C3]- and (2R)-[1-2H2]glycerol showed that glycerol is incorporated intact into carbon atoms 22, 23 and 24 of the aglycone of chlorothricin. C-1 of glycerol gives rise to C-22 with retention of one atom of deuterium, which occupies the H-22R position. A mechanism for the assembly of the aglycone is proposed which invokes phosphoenolpyruvate as the direct precursor of the 3-carbon moiety and a Baeyer-Villiger oxidation as the mode of formation of the macrocyclic lactone functionality. A feeding experiment with [1,2-13C2]succinate suggests that the propionate units of the aglycone polyketide are formed entirely via the methylmalonyl-CoA mutase reaction. The formation of the two 2,6-dideoxy-D-rhamnose moieties of chlorothricin from glucose was shown to involve replacement of the 2-hydroxyl group of the sugar by hydrogen with inversion of configuration at C-2. This contrasts with the retention stereochemistry observed earlier for the analogous formation of the 2,6-dideoxyhexose moiety of the antibiotic granaticin.

Synthesis and biological activity of 5-phenylselenenyl-substituted pyrimidine nucleosides

Several 5-phenylselenenyl derivatives of pyrimidine nucleosides were synthesized by electrophilic addition of phenylselenenyl chloride to the nucleosides under basic conditions. With use of this route, 5-(phenylselenenyl)-6-azauracil was also prepared. These compounds may serve as inhibitors of thymidylate synthase, as potential antiviral and anticancer agents, and as versatile intermediates for the synthesis of 5- or 6-substituted nucleosides. 5-(Phenylselenenyl)arabinosyluracil (PSAU, 4) and the corresponding cytosine analogue (PSAC, 5) were poor inhibitors of a promyelocytic leukemia cell line that was arabinosylcytosine-resistant. PSAU and PSAC were significantly less active than ara-C against L1210 cells and were found to selectively interfere with the cellular uptake and/or phosphorylation of 2'-deoxycytidine and 2'-deoxyuridine in intact L1210 cells.

Spontaneous release of interleukin 2 by lung T lymphocytes in active pulmonary sarcoidosis is primarily from the Leu3+DR+ T cell subset

The inflammation within the lower respiratory tract of individuals with pulmonary sarcoidosis is dominated by large numbers of helper T lymphocytes that proliferate and spontaneously release interleukin 2 (IL-2). To identify the lymphocyte subpopulation that releases IL-2 in this disorder, lung lymphocytes recovered by bronchoalveolar lavage were characterized using the monoclonal antibodies Leu4 (T lymphocyte), Leu3 (helper/inducer), Leu2 (suppressor/cytotoxic), and anti-HLA-DR, and separated by panning and flow cytometry. The majority of the IL-2 spontaneously released by T cells in the sarcoid lung was contributed by the Leu3+ cell population (Leu3+65 +/- 23 IL-2 units released/10(6) cells per 24 h; Leu2+ 9 +/- 8, P less than 0.04). Further characterization of the lung Leu3+ T cells in sarcoid demonstrated that 30 +/- 3% were expressing HLA-DR molecules on their surface compared with 6 +/- 1% in normals (P less than 0.01). Importantly, the subpopulation of Leu3+ lung T lymphocytes expressing a high intensity of HLA-DR molecules on their surface was responsible for the majority of the release of IL-2 in the sarcoid lung (Leu3+ high-intensity DR 42 +/- 17 U/10(6) cells per 24 h, Leu3+ low-intensity DR 8 +/- 1 U/10(6) cells per 24 h; P less than 0.01). Thus, the spontaneous release of IL-2 in the lung of sarcoid patients appears to be localized to a subset of Leu3+ high-intensity DR ("activated" lung helper/inducer) T lymphocytes. Because the sarcoid lung is characterized by markedly increased numbers of these cells, it is likely that this compartmentalized T cell population plays a major role in sustaining the exaggerated localized immune processes of this disorder.

Synthesis and biological activity of several amino nucleoside-platinum(II) complexes

Several platinum(II) complexes of 3',5'-diamino-3',5'-dideoxythymidine (compound 1), 5'-amino-5'-deoxythymidine (compound 2), and 3'-amino-3'-deoxythymidine (compound 3) and the respective 2'-deoxyuridine amino nucleoside complexes, 4-6, have been synthesized. Whereas compounds 1, 2, and 4-6 had no inhibitory effect on the replication of murine L1210 cells in cell culture, compound 3 [(3'-AdThd)2PtCl2] inhibited these cells with an ED50 of 0.8 microM. Incubation of L1210 cells with 10-20 microM compound 3 for 2 h produced less than 18% inhibition of RNA, DNA, or protein synthesis, which is of questionable significance. However a 16-h incubation resulted in an increased uptake of labeled thymidine into DNA (77%), labeled uridine into RNA (17%), and labeled amino acids into protein (100%). These unexpected results indicate that inhibition of macromolecules may not be involved in the inhibition of the replication of L1210 cells. The increased incorporation of labeled metabolites into macromolecules may be related to the increase in cell volume after a 2-h incubation of L1210 cells with compound 3 plus a marked increase after 2 h in the proportion of cells in their S phase. Compound 3 appears to delay the progression of cells through their cell cycle. A marked inhibitory effect on the transport of methionine or aminoisobutyric acid into L1210 cells was found with compound 3, which was slightly greater than that produced with cisplatin. Compound 3 had a dose-dependent effect on the survival of mice bearing the L1210 ascites neoplasm, with a T/C X 100 of 175 at a dose of 320 mg/kg. Investigation of the kinetics of decomposition in aqueous systems demonstrated that the primary UV-absorbing decomposition product is 3'-amino-3'-deoxythymidine and that only a limited amount of the compound is formed (less than 8%). Although 3'-amino-3'-deoxythymidine could account for a part of the inhibition of the replication of L1210 cells in culture, it cannot account for the inhibition of amino acid transport by compound 3, the platinum complex of 3'-amino-3'-deoxythymidine. Compound 3 has been shown to limit part of the amino acid uptake into L1210 cells in a similar manner to cisplatin.

Activation of sea urchin actin genes during embryogenesis. Measurement of transcript accumulation from five different genes in Strongylocentrotus purpuratus

The number of molecules of mRNA transcribed from each of five different actin genes are reported for developing embryos of the sea urchin Strongylocentrotus purpuratus. Transcripts of the cytoskeletal actin genes CyI, CyIIa, CyIIb and CyIIIa, and of the muscle actin gene M, were measured in unfertilized egg and embryo RNAs of cleavage, blastula, gastrula and pluteus stages. The measurements were obtained by probe excess titrations of these RNAs, using a set of single-stranded RNA probes each identifying the mRNA transcripts of a specific actin gene. These mRNAs can be identified by their distinct 3' non-translated trailer sequences. We confirm prior observations that the prevalence of actin mRNA in the unfertilized egg is low. Cytoskeletal actin genes CyI and CyIIIa each contribute 1 X 10(3) to 2 X 10(3) maternal mRNA molecules, and CyIIb contributes less than 2 X 10(2) mRNA molecules, while no detectable maternal mRNAs derive from cytoskeletal actin gene CyIIa or the muscle actin gene M. During certain periods of development, transcripts derived from the individual cytoskeletal actin genes accumulate rapidly, with kinetics specific to each mRNA. Transcripts of the muscle actin gene are absent until after gastrulation, when the initial muscle progenitor cells are formed. At late stages of development, each of the five genes studied is represented by 10(4) to 10(5) mRNA molecules per embryo. The present measurements permit calculation of the levels of each actin mRNA species in the particular cell types in which each gene functions in the fully differentiated embryo.

Cell lineage-specific programs of expression of multiple actin genes during sea urchin embryogenesis

We have determined spatial patterns of expression of individual actin genes in embryos of the sea urchin Strongylocentrotus purpuratus. Radioactively labeled probes specific for each of five cytoplasmic-type (Cy) and the single muscle-type (M) mRNAs were hybridized in situ to sections of fixed embryos. M actin mRNA appears only late in development and is confined to a few cells associated with the coelomic rudiments. The five Cy mRNAs fall into three sets, whose times and sites of expression during development are highly distinctive. Different cell lineages express messages of one or more of these sets, but never all three. Although all Cy actin mRNAs exhibit monophasic accumulation in the RNA of whole embryos during the course of development, such accumulation in many cases results from the summation of both increases and decreases in abundance within individual sets of cells. Within the genomic linkage group CyI-CyIIa-CyIIb, expression of CyI and CyIIb appears to be co-ordinate, and quite distinct from that of CyIIa. CyI and CyIIb are expressed in all lineages at some point in embryogenesis, but confined mainly to oral ectoderm and portions of the gut of the pluteus larva. CyIIa mRNAs are restricted to mesenchyme lineages throughout late gastrula stage, and subsequently accumulate in parts of the gut. The CyIIIa and CyIIIb genes, which form a separate linkage group, are expressed only in aboral ectoderm and its precursors. Furthermore, CyIII messages are the only detectable actin mRNAs in this cell lineage after late blastula stage.

Production of herpes simplex virus type 1 thymidine kinase in the presence of thymidine analogues

Treatment of herpes simplex virus type 1 (HSV-1) infected Vero, BHK, BHKtk- and LMtk- cells with 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd) caused increased synthesis of ICP36 and an increase in HSV-1 thymidine kinase (tk) activity at late times of infection. The overproduced ICP36 was identified as the HSV-1 encoded tk protein by immunoprecipitation. Whereas the thymidine analogue 5'-amino-5'-deoxythymidine (AdThd) caused an increase in HSV-1 tk synthesis and activity in wild type Vero and BHK cells, 5-iodo-2'-deoxyuridine (IdUrd) caused a similar increase only in tk- cells (LMtk-, BHKtk-). In vivo and in vitro stabilization studies using a [35S]methionine pulse-chase experiment or heat inactivation studies with purified HSV-1 tk revealed that stabilization of tk by the analogues could not account for the extent of the observed increase. Since overproduction of tk is observed only at late times of infection, it is suggested that the presence of these thymidine analogues in either the viral DNA or the cellular nucleotide pools is responsible for the observed differential effects.

Fluorescence probing of the function-specific cysteines of rat microsomal NADPH-cytochrome P-450 reductase

Titration of NADPH-cytochrome P-450 reductase with a fluorigenic maleimide suggests that approximately four cysteines are initially accessible and in close proximity to four tryptophans. Perturbation of the cysteines and/or tryptophans results in concomitant decreases in enzymic activity. These cysteines were correlated with functional components by binding studies and subsequent tryptic peptide mapping on the acid mobile phase-reverse phase HPLC. Adenine nucleotides and cytochrome c block labelling of the more hydrophilic peptides, while detergents facilitate labelling of the more hydrophobic peptides. The more hydrophobic peptides contain the microsomal binding site of cytochrome P-450. Removal of the prosthetic flavins exposes more cysteines in the more hydrophilic and hydrophobic regions of the peptide map, associating the former with FAD and the latter with FMN binding sites.

Identification of a warfarin-sensitive protein component in a 200S rat liver microsomal fraction catalyzing vitamin K and vitamin K 2,3-epoxide reduction

A partially purified, 200S submicrosomal fraction exhibiting thiol-dependent vitamin K1 (vitamin K) and epoxide reductase activities has been isolated by partial solubilization of rat hepatic microsomes with sodium cholate and separation by centrifugation at 105 000 g into a discontinuous sucrose gradient. At pH 7.4, the rates of vitamin K and vitamin K 2,3-epoxide reduction per milligram of 200S fraction protein were equivalent and were 2.5-3.0 times faster than in microsomes. Reduction of vitamin K 2,3-epoxide occurred in a tightly coupled, two-step reaction initially to vitamin K and subsequently to vitamin K hydroquinone (vitamin KH2). Incorporation of glycerol or sucrose and of sodium cholate into reaction mixtures equivalently affected the rates of both vitamin K and vitamin K 2,3-epoxide reduction, but in the case of epoxide metabolism, the ratios of vitamin KH2/vitamin K were much lower, suggesting that the second reaction has been partially uncoupled from the first. A 14 000-17 000-dalton warfarin-sensitive protein (WSP) that participates in vitamin K and vitamin K 2,3-epoxide reduction in the 200S fraction was identified by incorporation of N-[3H]ethylmaleimide ([3H]NEM) into the catalytically active reduced form of one or more attached disulfides. Reduction of WSP with dithiothreitol was required for reaction with [3H]NEM, and the substrates vitamin K and vitamin K 2,3-epoxide and the inhibitor warfarin all effectively blocked the reaction. 2-Mercaptoethanol could not substitute for dithiothreitol.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical and biological consequences of incorporation of antiviral agents into virus DNA

The molecular basis for the antiviral activity is discussed for a variety of nucleoside compounds approved for clinical use in the U.S.A. (5-iodo-2'-deoxyuridine, 5-trifluoromethyl-2'-deoxyuridine, 9-beta-D-arabinofuranosyladenine, 9-(2-hydroxyethoxymethyl)guanine), or in clinical trial (E-5-(2-bromovinyl)-2'-deoxyuridine, 1-(2-deoxy-2-fluoro-beta-D-arabinosyl)-5-iodocytosine, 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), or of specific interest to our laboratory (5-iodo-5'-amino-2',5'-dideoxyuridine, 5'-amino-5'-deoxythymidine). The consequence of incorporation of idoxuridine, the 5'-amino analog of thymidine or the 5'-amino analog of idoxuridine into the DNA of herpes simplex virus type 1 on transcription and translation is emphasized.

Regulation of cytoplasmic mRNA prevalence in sea urchin embryos. Rates of appearance and turnover for specific sequences

Complementary DNA clones representing cytoplasmic poly(A) RNAs of sea urchin embryos were hybridized with metabolically labeled cytoplasmic RNA preparations and the rates of appearance and of decay for each transcript species were determined at the blastula-gastrula stage of development. The prevalence of the transcripts chosen for this study ranged, on average, from about one molecule per cell to a few hundred molecules per cell. The embryos were labeled continuously for 18 hours with [3H]guanosine, beginning at 24 hours post-fertilization. The amount of cytoplasmic [3H]poly(A) RNA that hybridized to each cloned sequence was determined and the specific activity of the [3H]GTP pool was measured in the same embryos. Rate constants for the entry of each transcript species into the cytoplasm, and for its decay were extracted from these data. The embryo transcript species identified by the cloned probes displayed a range of stabilities. Half-lives of only a few hours were measured both for a very rare sequence and for a moderately prevalent sequence. Other newly synthesized transcripts, including sequences that first appear during embryonic development, as well as sequences also represented in maternal RNA, are far more stable. We conclude that cytoplasmic RNA turnover rate is a major variable in the determination of the cytoplasmic level of expression of embryo genes. The entry rates of the transcripts into the cytoplasm also varied, from a few molecules per embryo per minute to several hundred, depending on the sequence. By comparing the mass of transcripts of a given sequence in the embryo to the mass of transcripts of that sequence accumulating as a result of new synthesis, the point at which embryo transcription accounts for the major fraction of the cytoplasmic molecules could be estimated. This calculation showed that for some sequences maternal transcripts persist well beyond gastrulation, while other embryo poly(A) RNA species are largely the product of transcription in the embryo nuclei from the blastula stage onwards. There is no single stage at which all maternal transcripts are suddenly replaced by newly synthesized embryo transcripts. Primary transcription rates were measured for two sequences by determining accumulation of label in these RNA species soon after addition of [3H]guanosine to the cultures. Comparing these rates to the cytoplasmic entry rates, we did not detect a significantly greater nuclear transcription of the sequence homologous to the cloned probe.

Metabolism of vitamin K and vitamin K 2,3-epoxide via interaction with a common disulfide

The effects of thiols and sulfhydryl blocking reagents on the reduction of vitamin K to vitamin K hydroquinone and vitamin K 2,3-epoxide to vitamin K and vitamin K hydroquinone catalyzed by rat hepatic microsomes were investigated to determine the mechanism(s) for these reactions. Both vitamin K and vitamin K 2,3-epoxide reductions were catalyzed more effectively with dithiols than with monothiols as the reductant. The sulfhydryl reagent N-ethylmaleimide (NEM) inhibited vitamin K and vitamin K 2,3-epoxide reduction much more effectively when microsomes were initially treated with dithiothreitol (prereduced). In prereduced microsomes iodoacetamide was approximately half as effective an inhibitor of vitamin K and vitamin K 2,3-epoxide reduction as NEM, but in microsomes not prereduced it was more effective. Iodoacetic acid was ineffective as an inhibitor. Vitamin K or vitamin K 2,3-epoxide added to prereduced microsomes blocked subsequent inhibition by NEM of vitamin K and vitamin K 2,3-epoxide metabolism, respectively. Vitamin K added to prereduced microsomes also blocked inhibition by NEM of vitamin K 2,3-epoxide metabolism, and vitamin K 2,3-epoxide addition blocked inhibition by NEM of vitamin K metabolism. Vitamin K did not diminish the rate of vitamin K 2,3-epoxide metabolism, however, nor did vitamin K 2,3-epoxide diminish the rate of vitamin K metabolism. These data establish that exogenous thiol compounds promote the reduction of at least one protein disulfide which participates in the metabolism of vitamin K and vitamin K 2,3-epoxide. Presumably, the resultant sulfhydryl groups are reoxidized to the disulfide form during the metabolism of either vitamin which protects them from reaction with NEM.

Differential expression of the actin gene family of Strongylocentrotus purpuratus

Molecular probes that individually recognize the 3' nontranslated regions of six actin genes were utilized in RNA gel blot hybridizations to detect RNAs complementary to each gene in embryonic and adult tissues of Strongylocentrotus purpuratus. In addition the probes were used in DNA excess filter hybridizations to estimate the relative contribution of the different actin genes. All six genes produce relatively stable mRNAs, and each displays a characteristic and distinct pattern of expression. On the basis of their expression in the egg, early embryos, or in adult coelomocytes, it is concluded that genes termed CyI, CyIIa, CyIIb, CyIIIa, and CyIIIb encode cytoskeletal actin proteins. Actin gene M gives rise to mRNAs that are found only in tissues containing muscle. Actin genes CyI, CyIIa, CyIIb, and M are expressed in both adult and embryonic tissues, giving rise to transcripts 2.1-2.2 kb in length. Expression of genes CyIIIa and CyIIIb is confined to the embryo. Gene CyIIIa provides the major embryonic actin mRNA, which is 1.8 kb in length. Three of the cytoskeletal actin genes are linked over a 30-kb distance in the S. purpuratus genome. We show that the actin genes included in this linkage group are not coordinately expressed.

Sea urchin actin gene subtypes. Gene number, linkage and evolution

The actin gene family of the sea urchin Strongylocentrotus purpuratus was analyzed by the genome blot method, using subcloned probes specific to the 3' terminal non-translated actin gene sequence, intervening sequence and coding region probes. We define an actin gene subtype as that gene or set of genes displaying homology with a given 3' terminal sequence probe, when hybridized at 55 degrees C, 0.75 M-Na+. By determining the often polymorphic restriction fragment band pattern displayed in genome blots by each probe, all, or almost all of the actin genes in this species could be classified. Our evidence shows that the S. purpuratus genome probably contains seven to eight actin genes, and these can be assigned to four subtypes. Studies of the expression of the genes (Shott et al., 1983) show that the actin genes of three of these subtypes code for cytoskeletal actins (Cy), while the fourth gives rise to a muscle-specific actin (M). We denote the array of S. purpuratus actin genes indicated by our data as follows. There is a single CyI actin gene, two or possibly three CyII genes (CyIIa, CyIIb, and possibly CyIIc), three CyIII actin genes (CyIIIa, CyIIIb, CyIIIc), and a single M actin gene. Comparative studies were carried out on the actin gene families of five other sea urchin species. At least the CyIIa and CyIIb genes are also linked in the Strongylocentrotus franciscanus genome, and this species also has a CyI gene, an M actin gene and at least two CyIII actin genes. It is not clear whether it also possesses a CyIIc actin gene, or a CyIIIc actin gene. The genome of a more closely related congener, Strongylocentrotus dröbachiensis, includes 3' terminal sequences suggesting the presence of a CyIIc gene. In S. franciscanus and S. dröbachiensis the first intron of the CyI gene has remained homologous with intron sequences of both the CyIIa and CyIIb genes, indicating a common origin of these three linked cytoskeletal actin genes. Of the four S. purpuratus 3' terminal subtype probe sequences only the CyI 3' terminal sequence has been conserved sufficiently during evolution to permit detection outside of the genus Strongylocentrotus. An unexpected observation was that a sequence found only in the 3' untranslated region of the CyII actin gene in the DNA of S. dröbachiensis and S. purpuratus is represented as a large family of interspersed repeat sequences in the genome of S. franciscanus.

Thiazides III. Evidence of dose proportionality of hydrochlorothiazide 25, 50 and 100 mg tablets

A pilot bioavailability study was carried out where two subjects each were administered a dose of 25, 50 or 100 mg of commercially available hydrochlorothiazide (HCT) tablets. Plasma and urine samples were collected and analyzed by HPLC. A maximum plasma concentration of 50-285 ng/ml was reached in 1-2 hours, and plasma levels declined very rapidly with a half life of about 2-4 hours during first 12 hours period. The AUC was calculated using the trapezodial rule. A linear correlation was seen between the dose administered and amount of drug excreted.

Effects of nucleoside analogues on the expression of herpes simplex type 1-induced proteins

Exposure of herpes simplex virus type 1 (HSV-1)-infected Vero cells to the nucleoside analogues 5-iodo-5'-amino-2',5'-dideoxyuridine (AIdUrd), 5-iodo-2'-deoxyuridine (IdUrd) or 5'-amino-2',5'-dideoxythymidine (5'-AdThd) resulted in altered expression of HSV-1-induced proteins. Infected cell proteins (ICPs) synthesized in the presence of the nucleoside analogues were compared by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis to ICPs from non-drug-treated cells and it was found that there was no effect on HSV-1-induced alpha proteins but beta and gamma proteins were reduced as much as 60%. There were three exceptions: ICP 35 (Mr = 46,000) and ICP 39 (Mr = 36,000) were not reduced and ICP 36 (Mr = 42,000) was increased during drug treatment. Progeny virions were isolated from drug-treated infected Vero cells and were compared to progeny isolated from control cells with respect to their polypeptide make-up and for their ability to induce HSV-1 proteins in non-drug-treated Vero cells. The progeny virus from drug-treated cells exhibited altered protein patterns on SDS-polyacrylamide gels with respect to control HSV-1. The progeny virions from AIdUrd- or IdUrd- but not from 5'-AdThd-treated cells were defective in their abilities to induce proteins upon subsequent infection of non-drug-treated Vero cells. Two unusual phosphoproteins were detected; one with an apparent molecular weight of 30,000 was induced by progeny virus from AIdUrd-treated cells and another at approximately 69,000 was induced by progeny virus from 5'-AdThd-treated cells.

Design and performance of a field exposure system for evaluation of the ecological effects of SO2 on native grassland

We describe the design and performance of two replicate field exposure systems for evaluating the ecological effects of chronic SO2 exposure on 0.5 ha plots of native Montana grassland. The SO2 was supplied at a constant rate to each plot through a network of 2.5-cm inside diameter aluminum pipes set parallel to and approximately 0.7 m above the ground with 0.8-mm SO2 release holes at 3-m intervals. The resulting SO2 concentrations on the plots varied with micrometeorological conditions. Fumigations were essentially continuous from April through October for 5 yr on one set of four plots and for 4 yr on another set of four plots. Frequency distributions of SO2 concentrations were approximately log-normal and qualitatively similar to those from various area and point sources. The diurnal pattern of SO2 concentrations was strongly correlated with the reciprocal of windspeed. Nighttime concentrations averaged almost double daytime concentrations. The diurnal concentration pattern resembled an area source more closely than a point source, a direct result of using constant SO2 source strength. Plume strikes could be simulated by turning the system on only during pre-specified meteorological conditions. Similarly, seasonal variations in area source concentrations could be simulated by varying source strength on the plots. The data from 5 years use of the system indicate that the fine-scale behavior of SO2 concentrations would be realistic.

Incorporation of E-5-(2-halovinyl)-2'-deoxyuridines into deoxyribonucleic acids of herpes simplex virus type 1-infected cells

E-5-(2-Bromovinyl)-2'-deoxyuridine (BrvdUrd) and E-5-(2-iodovinyl)-2'-deoxyuridine (IvdUrd) are among the most potent and selective inhibitors of herpes simplex virus type 1 (HSV-1) replication. To elucidate the site of inhibition, we examined whether the halovinyl analogs are incorporated into DNA using two approaches. (i) In assays with purified DNA polymerases omitting dTTP from the reaction system, addition of either BrvdUTP or IvdUTP increased the polymerization reaction, indicating that these two analog triphosphates can be alternate substrates. (ii) When HSV-1-infected Vero cells were grown in the presence of either BrvdUrd or IvdUrd, there was an increase in the density of both the viral and cellular DNA. The viral DNA had 40% of its thymidine moiety substituted by IvdUrd when the concentration of [125I]IvdUrd was 24 microM (in the absence of added thymidine). At 30 microM BrvdUrd and 1 microM [2-14C]thymidine, the viral DNA had only 11% of its thymidine moiety substituted by BrvdUrd, presumably because of the presence of added thymidine. Following digestion of [125I]IvdUrd-substituted DNA with DNase 1, venom phosphodiesterase, and alkaline phosphatase, the radioactivity co-migrated with nonradioactive IvdUrd in thin layer chromatography. Under similar conditions, no detectable incorporation of either [125I]IvdUrd or BrvdUrd into mock-infected Vero cell DNA was observed. Thus, IvdUrd and BrvdUrd are incorporated into DNA of HSV-1 infected cells but not into DNA of uninfected cells.

Anterior interbody fusion in fractures and fracture-dislocations of the spine

Twenty-five cases of unstable fractures and fracture-dislocations of the spine are reviewed. They were treated at the Catholic Medical College and Centre in a 3-year period, 1975 to 1978. 1. Eleven of the 25 patients were treated by anterior interbody fusion performed at 6 to 8 weeks from injury or initial surgery. 2. Eleven patients had neurological deficits, 3 with incomplete lesions and 8 with complete lesions. Open reduction and decompression laminectomies were performed on patients having neurological deficits prior to anterior interbody fusion. Two patients with incomplete paraplegia showed marked neurological recovery whilst one with complete paraplegia regained some sensation. 3. Solid clinical fusion was obtained in all but one patient within four months of interbody fusion. 4. Amongst the 18 patients with kyphosis at the time of admission 10 had a final improvement of their kyphosis ranging from 3 to 10 degrees (average 6 degrees). Three had no change and 5 demonstrated a mild increase of kyphosis (average 4 degrees). 5. Pain was relieved in 21 patients out of 25. The advantages of this technique include effective stabilization, prevention of late deformity and relatively early mobilization without internal fixation.

Primary structure, gene organization and polypeptide expression of poliovirus RNA

The primary structure of the poliovirus genome has been determined. The RNA molecule is 7,433 nucleotides long, polyadenylated at the 3' terminus, and covalently linked to a small protein (VPg) at the 5' terminus. An open reading frame of 2,207 consecutive triplets spans over 89% of the nucleotide sequence and codes for the viral polyprotein NCVPOO. Twelve viral polypeptides have been mapped by amino acid sequence analysis and were found to be proteolytic cleavage products of the polyprotein, cleavages occurring predominantly at Gln-Gly pairs.

Effect of acetylcholine on the norepinephrine-induced positive chronotropy and increase in cyclic nucleotides of isolated rabbit sinoatrial node

Transmural stimulation of, or application of nicotine to, the isolated rabbit sinoatrial (SA) node resulted in initial negative and late positive chronotropy. Simultaneous application of acetylcholine and norepinephrine produced a similar biphasic chronotropic effect. These procedures produced an initial increase in cyclic guanosine 3':5'-monophosphate (cyclic GMP) and a delayed elevation in cyclic adenosine 3':5'-monophosphate (cyclic AMP). The initial and late effects on rate and nucleotide levels were inhibited by pretreatment with atropine and propranolol, respectively. Pretreatment with atropine shortened the time of maximum increase in cyclic AMP level and heart rate from 3 to 1 minute after the simultaneous application of acetylcholine and norepinephrine and enhanced the positive chronotropic effect. Physostigmine prolonged the duration of the increase in cyclic GMP and negative chronotropic effect after the simultaneous application. These results suggest that when acetylocholine and norepinephrine are present simultaneously in the SA node region, the former interacts predominantly with muscarinic receptors and stimulates the cyclic GMP system, which in effect delays the cyclic AMP elevation and reduces the positive chronotropic effect of norepinephrine. However, these effects of acetylcholine cannot be explained solely on the basis of changes in the cyclic GMP level, because sodium nitroprusside produced a marked elevation of the cyclic GMP levels without decreasing the heart rate and did not affect the norepinephrine-induced increase in pacemaker rate and cyclic AMP. Sodium nitroprusside may affect cyclic GMP pools other than those susceptible to acetylcholine. These cyclic GMP pools may not exert chronotropic effects.

Effect of cholera enterotoxin on pacemaker rate and cyclic adenosine 3':5'-monophosphate in isolated rabbit sinoatrial node

The positive chronotropic effect of cholera enterotoxin on isolated rabbit sinoatrial (S-A) node was investigated. This toxin produced a time and dose-related increase in pacemaker rate and cyclic adenosine 3':5'-monophosphate (cyclic AMP) levels and shifted to the left the dose-response curves of norepinephrine on the pacemaker rate and cyclic AMP content in the S-A node. Thus, the sensitivity of the S-A node to norepinephrine was increased by the toxin. These effects of the toxin were not blocked by propranolol. There was a linear relation between the increases in pacemaker rate and cyclic AMP content after application of both the toxin and norepinephrine. However, the slope of the regression line relating pacemaker rate to cyclic AMP level differed with these two agents. These results suggest that cholera enterotoxin increases pacemaker rate with activation of the adenylate cyclase system in the S-A node, but the mechanism differs from that of norepinephrine.

Selective toxicity of purine deoxynucleosides for human lymphocyte growth and function

A role for the enzymes adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) and purine-nucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyl-transferase, EC 2.4.2.1) in the functional maturation of lymphoid cells has been revealed by the association of inherited deficiencies of these enzymes and profound immune deficiency. Previous studies have suggested that the selective toxicity for lymphocytes may be mediated by the accumulation of toxic deoxynucleoside metabolites, likely through the action of specific kinases enriched in lymphoid cells. In order to study possible mechanisms whereby lymphocyte function may be impaired in these disorders, we have studied the effect of nucleosides and their deoxy analogues on both T and B lymphocyte growth and function. In the presence of deoxyguanosine, there was marked inhibition of T lymphoblast growth, phytohem-agglutinin-induced cell proliferation, and T suppressor cell activity. T helper cell activity and the differentiation of B cells to an antibody-secreting stage were unaffected. Deoxyadenosine was much less inhibitory, but in the presence of an inhibitor of adenosine deaminase, its effects on lymphocyte growth and function were markedly potentiated. The addition of deoxycytidine prevented deoxyadenosine toxicity in all assays, whereas it only interfered with deoxyguanosine effects on T lymphoblast growth. These studies provide some initial understanding for the selective loss of specific lymphocyte functions in individuals with inborn errors of purine metabolism.

Protein aggregation in C-phycocyanin. Studies at very low concentrations with the photoelectric scanner of the ultracentrifuge

Solutions of C-phycocyanin of very low concentrations were examined by sedimentation-velocity studies in the Spinco model E ultracentrifuge equipped with a photoelectric scanning system and a monochromator. At sufficiently low concentrations complete disaggregation from the hexamer to the monomer was observed. The equilibrium constant of monomer to hexamer was estimated to be approx. 10(30). For studies of aggregation over the complete range of concentration, C-phycocyanins from Phormidium luridum and Lyngbya sp. were used. Sedimentation-velocity studies at high concentration with schlieren optics are reported for C-phycocyanins from Anabaena variabilis and Lyngbya sp. The pH-dependence of aggregation and the temperature-dependence of trimer-hexamer equilibrium for phycocyanins from these algae were found to be similar to those of other C-phycocyanins. The principal feature of the pH-dependence is the dominance of hexamers at the isoelectric point. Increasing temperature increased the amount of hexamer and decreased the amount of trimer.

The requirement for cobalt of sheep grazed on cobalt-deficient pastures

Experimental proof is presented that cobalt injected intravenously or into the abomasum at the rate of 1 mg/day is without any measurable effect on the cobalt deficiency syndrome in sheep. Similarly, depot therapy with colloidal cobalt is of no benefit. It is confirmed that, to be effective, cobalt supplements must be introduced frequently into the rumen, by mouth or by direct injection; although administration by other routes leads to a considerable accumulation of cobalt in the tissues this does not reach the rumen in effective amounts, if at all. For sheep grazing grossly cobalt-deficient pastures the total intake of cobalt necessary to ensure optimum growth and haemoglobin production was found to be equivalent to almost precisely 0.08 mg/day when supplementary cobalt was provided three times each week; in growing lambs the requirement was greater. Analytical evidence is presented in support and the findings are discussed in relation to certain conclusions arrived at by others.

Protein aggregation. Studies of larger aggregates of C-phycocyanin

Aggregates of phycocyanin sedimenting at 17s, 22s and 27s are demonstrated to constitute more than 40% of crude blue-green-algal extracts, pH6.0 and I0.1, and are retained in highly purified preparations. Sedimentation-velocity studies of the large aggregates as a function of pH are reported. Sucrose-density-gradient experiments performed as a function of time of sedimentation indicate that: (1) with increasing time of sedimentation, the largest aggregates are dissipated at the leading protein boundary and the several phycocyanin species present are not completely resolved; (2) phycocyanin fractions with the largest aggregates exhibit the highest E(620)/E(280) ratio and the largest relative fluorescence efficiency. Gel-filtration experiments with Sephadex G-200 do not resolve the species completely, and reapplication of phycocyanin gel-filtration fractions to the column results in an elution pattern similar to the original, except that there is an enhancement of the allophycocyanin fraction and the amount of denatured protein. Increasing the sedimentation times in a sucrose density gradient also enhances the allophycocyanin fraction. Fluorescence results demonstrate that there are possibly three excitation maxima, one corresponding to the monomer (approx. 600mmu), one for higher aggregates (625-630mmu) and one for the allophycocyanin fraction (approx. 650mmu). Only a single fluorescence-emission band is detected, which is fairly symmetrical and which has a red shift with higher aggregation and with the appearance of allophycocyanin. The appearance of allophycocyanin may be correlated with the irreversible disaggregation of the largest phycocyanin species. It is suggested that the largest protein aggregates are in the size range of the biliprotein aggregates reported in electron microscopy of algal cells.

Protein aggregation. The effect of deuterium oxide on large protein aggregates of C-phycocyanin

The amount of 11s aggregate in phycocyanin, normally stimulated by hydrophobic forces, is dramatically increased by the presence of deuterium oxide. Proteins in which hydrophobic forces are not proposed as a mechanism for aggregation are unaffected by deuterium oxide. These observations are consistent with the lower critical micelle concentration reported for ionic detergents in deuterium oxide. Phycocyanin samples containing a majority of material sedimenting faster than 11s were also investigated in the presence of deuterium oxide with the following findings: the most rapidly sedimenting species in water buffer is 24s; in deuterium oxide more than 10% of the protein sediments at 67s and substantial amounts of other species with sedimentation coefficients larger than 24s are present. These large quantities of species sedimenting faster than 24s are found in deuterium oxide buffers from pD5.5 to 7.0. Sucrose-density-gradient studies in deuterium oxide at pD6.0 confirm the presence of large amounts of more rapidly sedimenting species. Spectrophotometric studies on fractions from the sucrose-density-gradient experiments indicate with the presence of higher aggregates a red shift of the visible-absorption maximum and an enhancement of the E(620)/E(280) ratio. Fluorescence-emission studies show a greater relative fluorescence efficiency for these higher aggregates and are consistent with the suggested enhancement of higher aggregates in deuterium oxide. The existence of phycocyanin aggregates of such a large size is suggested to be of importance in vivo, with phycocyanin playing a role as a structural protein.