A 75-kDa Na+,K+-ATPase competitive inhibitor protein isolated from rat brain cytosol binds to a site different from the ouabain-binding site

A Na+,K+-ATPase inhibitor protein has been purified to homogeneity from rat brain cytosol by ammonium sulphate precipitation, DEAE anion-exchange chromatography and hydroxyapatite adsorption column chromatography. The purified protein migrates as a single polypeptide band of 75 kDa on 7.5% SDS/PAGE. Amino acid composition data shows the presence of a high number of acidic amino acids in the molecule in relation to the pI value of 4.6. The inhibitor binds Na+,K+-ATPase reversibly and blocks ATP binding sites at micromolar concentrations with an I50 of approximately 700 nm. As a result, formation of the phosphorylated intermediate of Na+,K+-ATPase is hindered in the presence of the inhibitor. It does not affect p-nitrophenylphosphatase activity. Tryptophan fluorescence studies and CD analysis suggest conformational changes of Na+,K+-ATPase on binding to the inhibitor.

[Vascular injuries complicating osteosynthesis in proximal femur fractures]

While there are quite a number of reports on vascular injuries complicating hip arthropasty by acetabular component screw fixation, retractor tip pressure or extruding bone cement, the incidence of deep femoral vessel injuries in operative fixation of proximal femoral fractures is comparatively seldom described. We report on two patients with per- and subtrochanteric femoral fractures who sustained injuries of deep femoral artery branches during the implantation of a dynamic hip screw (DHS) and a dynamic condylar screw (DCS), which resulted in a massive thigh hematoma and a fist-size pseudoaneurysm respectively and necessitated surgical intervention in either case. We blame these vascular injuries on the pressure of Hohmann retractors exposing the femoral bone or on the drilling of boreholes for plate attachment. After discussing various operative procedures, we conclude that intramedullar implants are safer than plates with regard to potential vascular complications.

Analysis of two cosmid clones from chromosome 4 of Drosophila melanogaster reveals two new genes amid an unusual arrangement of repeated sequences

Chromosome 4 from Drosophila melanogaster has several unusual features that distinguish it from the other chromosomes. These include a diffuse appearance in salivary gland polytene chromosomes, an absence of recombination, and the variegated expression of P-element transgenes. As part of a larger project to understand these properties, we are assembling a physical map of this chromosome. Here we report the sequence of two cosmids representing approximately 5% of the polytenized region. Both cosmid clones contain numerous repeated DNA sequences, as identified by cross hybridization with labeled genomic DNA, BLAST searches, and dot matrix analysis, which are positioned between and within the transcribed sequences. The repetitive sequences include three copies of the mobile element Hoppel, one copy of the mobile element HB, and 18 DINE repeats. DINE is a novel, short repeated sequence dispersed throughout both cosmid sequences. One cosmid includes the previously described cubitus interruptus (ci) gene and two new genes: that a gene with a predicted amino acid sequence similar to ribosomal protein S3a which is consistent with the Minute(4)101 locus thought to be in the region, and a novel member of the protein family that includes plexin and met-hepatocyte growth factor receptor. The other cosmid contains only the two short 5'-most exons from the zinc-finger-homolog-2 (zfh-2) gene. This is the first extensive sequence analysis of noncoding DNA from chromosome 4. The distribution of the various repeats suggests its organization is similar to the beta-heterochromatic regions near the base of the major chromosome arms. Such a pattern may account for the diffuse banding of the polytene chromosome 4 and the variegation of many P-element transgenes on the chromosome.

"Acting out" and "acting in" as behavioral responses to stress: a qualitative and quantitative study

In a sample of 270 depressed patients, we describe some behaviors in response to stress. One third acknowledged "acting out" behaviors--angry, destructive acts and "out of control" behaviors. Four fifths acknowledged "acting in" behaviors--most commonly withdrawal. As a percentage of subjects acknowledged both response styles (with alternate expression influenced by situation), we developed a dimensional self-report measure within a subsample of 177 who attended a follow-up reassessment. Assignment to four groups with contrasting expressions of "acting out" and "acting in" scores demonstrated differences in age, diagnostic status, age of onset of depression, and self-injurious behaviors.

Study of impact of nutrition & health day strategy on the coverage rates of supplementary nutrition and health interventions among the ICDS beneficiaries in a rural block of Madhya Pradesh

To study the trends of beneficiary coverage (pregnant and lactating women and children less than two years of age) for utilization of supplementary nutrition and health services in a rural block before and after the launch of a strategy to converge Health & Integrated Child Development Services (ICDS) on a single day christened "Nutrition and Health Day" (NHD). It is a before and after intervention design in rural ICDS block Amarwada in district Chhindwada. As a part of intervention, NHD were organised on which convergent services of Health & ICDS were made available to the beneficiaries. On the weekly NHDs, uncooked supplementary nutrition for the week was distributed to pregnant and lactating mothers and children under two. The Health worker visited the Anganwadi Centre (AWC) and immunized children and pregnant women, distributed IFA, Vitamin A and provided health and nutrition education. The study assessed the impact of these interventions on the coverage rates of the services. Study was conducted between May 97 and March 98. The routine monitoring reports of the ICDS and Health System of the state government were used as study tools. The study sample comprised of AWC beneficiaries in the project area. The total population of the block was 89,476. Participation in the supplementary nutrition program (SNP) increased two to three folds in all categories of the target population. Immunization and Vitamin A coverage levels for children also showed an increase of about 3 and 5-8 times from baseline status respectively in a year's time. Among pregnant women, Tetanus Toxoid (TT) and Iron and Folic Acid (IFA) utilization rates have also shown two and five fold increase respectively.

Cloning of mouse gamma-glutamyl hydrolase in the form of two cDNA variants with different 5' ends and encoding alternate leader peptide sequences

Mouse-liver gamma-glutamyl hydrolase (GH) is a lysosomal endopeptidase with an acid pH optimum that is activated by sulfhydryl compounds and preferentially hydrolyzes the most proximal gamma-glutamyl linkage of longer chain polyglutamates of folates and their analogues. We describe the cloning of this mouse lysosomal cDNA enzyme from liver GH mRNA in the form of two cDNA variants (1.295 and 1.268 kb in length) differing 14-fold (Variant I versus Variant II) in relative frequency that exhibited 5'-end heterogeneity and encoded alternate leader peptides. The 5' UTR in these variants also differs in length by 27 nucleotides. Otherwise, the ORF and 3' UTR in each case are the same. These cDNAs encode a protein in which the deduced amino acid sequence shares 78.9 and 69. 1% identity to rat and human GH sequences, respectively. Amino acid sequence comparisons among the three species identified three conserved Asn sites and two conserved Cys residues that may be sites of glycosylation and sulfhydryl compound activation, respectively. Variant I GH mRNA was more abundant than Variant II GH mRNA in all mouse tissues examined. Variant I GH mRNA levels were extremely high in salivary gland, moderately high in kidney, liver, lung, stomach and uterus, low in small intestine, brain and fetal liver and relatively rare in thymus, spleen and skeletal muscle. Abundance of GH mRNA among tumors varied from low to high, with no discernible correlation with their tissue of origin.

Chromosomal localization of the murine RFC-1 gene encoding a folate transporter and its amplification in an antifolate resistant variant overproducing the transporter

A variant of the L1210 cell (L1210/R83) selected in the presence of the lipophilic antifolate, metoprine, and a concentration of the natural diastereoisomer of 5-formyltetrahydrofolate, lL5CHO-folateH4, suboptimum for growth exhibited a 35-fold increase compared to parental L1210 cells in one-carbon, reduced folate transport. This was evidenced by the increase in Vmax for [3H]MTX (methotrexate) influx and a commensurate increase in the amount of the 46 kilodalton (kDa) transport protein and reduced folate carrier (RFC-1) mRNA. The variant is resistant to lipophilic antifolates, but shows collateral sensitivity to classical folate analogues. Karyotype analysis of L1210/R83 cells revealed the presence of several new chromosome abnormalities. One of these was a large, submetacentric marker chromosome comprising a normal #10 and a longer, abnormally banded arm of uncertain origin which exhibited an interstitial, palely staining, HSR-like segment. The results of Southern and Northern blotting showed that the RFC-1 gene copy number and RNA transcript level were markedly increased (30-35 fold) in L1210/R83 cells. Fluorescence in situ hybridization (FISH) analysis revealed that the HSR-like segment in these cells was the site of amplified RFC-1 genes. Independent revertant subclones, obtained following growth in the absence of selection pressure, showed four- to 12-fold decreases in [3H]MTX influx Vmax and in amount of NHS (N-hydroxysuccinimide)-[3H]MTX affinity labeled one-carbon, reduced folate transporter compared to L1210/R83 cells. RFC-1 gene copy number also decreased, and the mean length of the HSR in these revertants declined 1.6- to 5-fold. Based upon genomic nucleotide sequencing, the RFC-1 gene in the normal mouse genome was localized to chromosome 10 in close association with the alpha 1 (Col18a1) collagen gene at 10B3(locus 41cM). The close association of these genes was confirmed by other data showing that the alpha 1 collagen gene was co-amplified in L1210/R83 cells. These results document the amplification at the site of a putative HSR in an L1210 cell variant of the RFC-1 gene regulating expression of the one-carbon, reduced folate transporter.

Alterations in total iron, zinc, and calcium levels and their influence on the hepatic activities of gamma-glutamyl transferase and glucose-6-phosphatase in the host bearing transplantable murine lymphoma

The levels of iron, zinc, and calcium in liver as well as serum, together with the enzymatic activities of gamma-glutamyl transferase (GGT, EC 2.3.2.2) and glucose-6-phosphatase (G-6-Pase, EC 3.1.3.9) in liver, were critically monitored over various periods in male Swiss albino mice bearing Dalton's lymphoma (DL), a transplantable ascites-producing tumor. Both hepatic and serum contents of iron, zinc, and calcium were found to be maximally elevated (p < 0.001) on day 15 after tumor transplantation as compared with their contents in normal animals. There was a gradual increase in the activity of GGT in liver in lymphoma-bearing mice in comparison with their normal counterparts, which showed a maximum peak (p < 0.001) on day 15, followed by a continuous and sharp fall. Hepatic G-6-Pase activity was found to decrease continuously throughout the progression of lymphoma as compared with its levels to normal animals. Tumor-cell counts in peritoneal lymph fluids of mice containing DL yielded a maximum count of 155.7 x 10(3) cells/mm3 on day 15. A significant correlation was observed among the levels of different metals, enzymatic activities, and tumor-cell counts at different periods of study. From these results, it can be concluded that the metals studied may have a role in initiating and controlling cellular proliferations, through their effects on modulating the activities of the possibly preneoplastic and neoplastic marker enzymes named above.

Structural analysis of the human RFC-1 gene encoding a folate transporter reveals multiple promoters and alternatively spliced transcripts with 5' end heterogeneity

The organization and structure of the human RFC-1 gene encoding a folate transporter were determined. The RFC-1 gene spans 22.5kb and was found to be distributed in eight exons, including five primary exons and three alternatives of exon 1. Most splice junctions conform to consensus sequences for such junctions. The human RFC-1 gene differs from the mouse and hamster genes both in terms of the total number of exons and in regard to alternatives of exon 1 which encode 5' end heterogeneity. Previously described cDNA variants (GenBank/EMBL accession no. U19720) are now shown to incorporate one of two alternatives (exons 1a and 1b) to exon 1 and exons 2-6 as a result of RNA splicing. Another variant also described may not be full length in that it incorporates a probable alternative (exon 1c) to exon 1 along with exon 2 and a truncated exon 3. A relatively GC- rich region of the genome 5' of the alternatives to exon 1 appears to be distinctly promoter like and incorporates a number of putative cis-acting elements, including multiple SP1 sites, involved in the regulation of transcription. Primer extension analysis of this upstream region in two human cell types revealed a similar pattern of multiple transcription start sites (tsp) proximal to the 5' end of exon 1. However, there was a greater number of potential tsp within the region immediately upstream of exon 1b than within the regions upstream of exons 1a and 1c. The existence of true alternatives to exon 1 in this gene incorporating different 5' ends indicates that its transcription is under the control of multiple promoters. The identity of two such promoters was obtained by functional deletion analysis, showing that expression of a luciferase reporter gene was directed separately by discrete stretches of nucleotide sequence proximal to exon 1a (promoter 1) or exon 1b (promoter 2) in transient transfection experiments. Promoter 1 appeared to have a three-fold lower basal activity than promoter 2, but was enhanced up to nine-fold in fusion constructs containing an SV40 enhancer element. Also, promoter 2 partly consists of a highly GC-rich direct repeat element containing at least three putative SP-1 and 3 putative MZF1 sites. Finally, the activity of these promoters relative to each other was consistent with the results of primer extension analysis showing a greater multiple and usage of tsp within promoter 2 (exon 1b) than within promoter 1 (exons 1a and 1c), suggesting that the variant incorporating exon 1b was the most abundant.

DNA-polycation nanospheres as non-viral gene delivery vehicles

Nanospheres synthesized by salt-induced complex coacervation of cDNA and polycations such as gelatin and chitosan were evaluated as gene delivery vehicles. DNA-nanospheres in the size range of 200-750 nm could transfect a variety of cell lines. Although the transfection efficiency of the nanospheres was typically lower than that of lipofectamine and calcium phosphate controls in cell culture, the beta-gal expression in muscle of BALB/c mice was higher and more sustained than that achieved by naked DNA and lipofectamine complexes. This gene delivery system has several attractive features: (1) ligands can be conjugated to the nanosphere for targeting or stimulating receptor-mediated endocytosis; (2) lysosomolytic agents can be incorporated to reduce degradation of the DNA in the endosomal and lysosomal compartments; (3) other bioactive agents or multiple plasmids can be co-encapsulated; (4) bioavailability of the DNA can be improved because of protection from serum nuclease degradation by the polymeric matrix; (5) the nanosphere can be lyophilized for storage without loss of bioactivity.

Marine latitudinal diversity gradients: tests of causal hypotheses

Latitudinal diversity gradients are first-order expressions of diversity patterns both on land and in the oceans, although the current hypotheses that seek to explain them are based chiefly on terrestrial data. We have assembled a database of the geographic ranges of 3,916 species of marine prosobranch gastropods living on the shelves of the western Atlantic and eastern Pacific Oceans, from the tropics to the Arctic Ocean. Western Atlantic and eastern Pacific diversities are similar, and the diversity gradients are strikingly similar despite many important physical and historical differences between the oceans. This shared diversity pattern cannot be explained by: (i) latitudinal differences in species range-length (Rapoport's rule); (ii) species-area effects; or (iii) recent geologic histories. One parameter that does correlate significantly with diversity in both oceans is solar energy input, as represented by average sea surface temperature. If this correlation is causal, sea surface temperature is probably linked to diversity through some aspect of productivity. In this case, diversity is an evolutionary outcome of trophodynamic processes inherent in ecosystems, and not just a byproduct of physical geographies.

A single amino acid difference within the folate transporter encoded by the murine RFC-1 gene selectively alters its interaction with folate analogues. Implications for intrinsic antifolate resistance and directional orientation of the transporter within the plasma membrane of tumor cells

The apparent Km, but not Vmax, for influx of methotrexate (MTX) mediated through the plasma membrane of S180 cells by the one-carbon, reduced folate transporter as well as the KD for binding to the transporter were 4-fold higher than in L1210 cells correlating with the greater intrinsic resistance of the former to this folate analogue. In contrast, no difference was observed between each cell type with regard to efflux of [3H]MTX mediated by this same transporter in ATP-depleted cells. The difference in influx Km in the case of this 10-methyl substituted N1O analogue of folic acid was not seen with more effective permeants, such as the unsubstituted N1O aminopterin or C1O analogues. Thus, values for influx Km for aminopterin, which were 1-1.2 microM in each cell type, increased as a result of substitution at N1O (MTX) 3-fold in L1210 cells but 12-fold in S180 cells. Nucleotide sequencing of reverse transcriptase-polymerase chain reaction-generated cDNA and of polymerase chain reaction-generated genomic DNA identified a single nucleotide difference between each cell type at +890 within exon 3 of the RFC-1 gene. This was in the form of a G (L1210 cells) to A (S180 cells) transition. Codon 297, the site of this transition, encodes either Ser or Asn in L1210 or S180 cells, respectively, which is located between the seventh and eight membrane-spanning helices. This amino acid difference had no effect on the electrophoretic mobility or amount of the transporter in each cell type that was shown by Western blotting with anti-RFC-1 peptide antibodies to migrate as 46 kDa in each case. Proof that this nucleotide difference alone accounted for the alteration in influx between each cell type was obtained by S180 RFC-1 cDNA versus L1210 RFC-1 cDNA transfection of an L1210 cell variant with undetectable MTX influx and RFC-1 gene expression. In this case, the higher Km for MTX influx associated with S180 cells was duplicated only in the S180 RFC-1 transfectants. These results appear to document the first example of a nucleotide alteration within the RFC-1 gene, which influences the interaction of MTX with the encoded plasma membrane transporter. An analysis of topology, in addition to other considerations, suggests that the site of the amino acid difference found in the transporter from L1210 and S180 cells occurs within or near the binding site on the external plasma membrane surface.

RFC-1 gene expression regulates folate absorption in mouse small intestine

Mediated folate compound transport inward in isolated luminal epithelial cells from mouse small intestine was delineated as pH-dependent and non-pH-dependent components on the basis of their differential sensitivity to the stilbene inhibitor, 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid. pH dependence was manifested as higher maximum capacity (Vmax) for influx of l, L-5-CH3-H4folate at acidic pH compared with neutral or alkaline pH with no effect on saturability (Km). The pH-dependent component was relatively insensitive to inhibition by 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid and highly saturable (Km or Ki = 2 to 4 microM) in the case of folic acid, folate coenzymes, and 4-aminofolate analogues as permeants or inhibitors. The non-pH-dependent component was highly sensitive to 4, 4'-diisothiocyanatostilbene-2,2'-disulfonic acid and poorly and variably saturable (Km or Ki = 20 to >2000 microM) with respect to these folate compounds. Only the pH-dependent transport component was developmentally regulated, showing much higher maximum capacity for l,L-5-CH3-H4folate influx in mature absorptive rather than proliferative crypt cells. The increase in pH-dependent influx during maturation was associated with an increase in RFC-1 gene expression in the form of a 2.5-kilobase RNA transcript and 58-kDa brush-border membrane protein detected by folate-based affinity labeling and with anti-mouse RFC-1 peptide antibodies. The size of this protein was the same as that encoded by RFC-1 mRNA. The treatment of mature absorptive cells with either the affinity label or the anti-RFC-1 peptide antibodies inhibited influx of l, L-[3H]-5-CH3-H4folate in a concentration-dependent manner. These results strongly suggest that pH-dependent folate absorption in this tissue is regulated by RFC-1 gene expression.

Organization, structure and alternate splicing of the murine RFC-1 gene encoding a folate transporter

The structural organization of the murine RFC-1 gene encoding a folate transporter has been determined. The entire nucleotide sequence of the L1210 cell RFC-1 cDNA, the 3'- and 5'-untranslated regions and the coding sequence were found to be distributed in eight exons, including six primary exons and alternates to exon 1 and exon 5, spanning 10.4 kb. Splice variants were identified in an L1210 cell cDNA library. The most common incorporates exons 1 through 6, encoding a 58-kDa polypeptide. The two least common incorporate exons 1 and 2, a truncated version of exon 3 and exons 4 through 6; or exons 1 through 4, an alternate to exon 5, and exon 6, encoding polypeptides of 53.6 and 43.4 kDa, respectively. A fourth variant reported earlier (GenBank/EMBL accession No. L36539) by others incorporates what we have found to be an alternate of exon 1 and exons 2 through 6. A relatively GC-rich region of the genome just 5' of exon 1 as well as exon 1a appears to be distinctly promoter-like and encodes a number of putative cis-acting elements. The findings pertaining to alternates of exon 1 suggest that the transcription of RFC-1 variants results from two different promoters.

Posttranscriptionally mediated decreases in folylpolyglutamate synthetase gene expression in some folate analogue-resistant variants of the L1210 cell. Evidence for an altered cognate mRNA in the variants affecting the rate of de novo synthesis of the enzyme

L1210 cell variants resistant to edatrexate (EDX) were isolated by selection in vivo during therapy with this folate analogue. Among the variants selected, seven (L1210/EDX-4 to -7 and L1210/EDX-12 to -14) were found to exhibit 2-23-fold lower levels of folylpolyglutamate synthetase (FPGS) activity compared with parental L1210 cells. Lower levels of FPGS activity in cell-free extract from these variants using EDX as substrate were characterized by the same relative decrease in value for Vmax with no change in apparent Km. The results of an analysis of FPGS activity in mixtures of variant and parental cell extract suggested that no endogenous inhibitors in the variant cells or stimulatory factors in parental cells accounted for the differences observed. Also, FPGS from variant and parental cells showed no difference in thermostability. Decreases in a 60-61-kDa protein as shown by immunoblotting with anti-FPGS peptide antibody were found to occur commensurately with the decrease in FPGS activity in cell extract from the variants compared with parental cells. However, no evidence was obtained for a difference in turnover of FPGS protein during measurement of the decay of FPGS activity in cycloheximide-treated variant and parental cells. In addition, Northern blotting of poly(A)+ RNA did not reveal any difference in the size or level of FPGS mRNA among these various cell types. Studies of in vitro translation of hybridization-selected FPGS mRNA from L1210 cells showed that both mitochondrial and cytosolic forms of FPGS were generated during the reaction. Moreover, FPGS mRNA from the variant cells was significantly less effective in mediating formation of the FPGS peptide product in a manner correlating with FPGS activity and protein found in the cytosol of the various cell types. These results suggest that FPGS gene expression in these variants is posttranscriptionally altered at the level of the cognate mRNA itself and that this alteration constitutively down-regulates the steady-state level of FPGS in these variants.

Additional organizational features of the murine folylpolyglutamate synthetase gene. Two remotely situated exons encoding an alternate 5' end and proximal open reading frame under the control of a second promoter

Nucleotide sequence analysis of independently isolated clones from a mouse liver cDNA library identified two additional splice variants of folylpolyglutamate synthetase (FPGS) mRNA with novel sequence at the 5' end. These variants incorporate two new alternatives (exons A1a and A1b) of exon 1 in the murine FPGS gene which are also spliced to exon 2. Exon A1a encodes most of the 5'-untranslated region. Exon A1b encodes a downstream segment of the 5'-untranslated region, two ATG start codons, and a unique mitochondrial leader peptide as well as 15 additional amino acids of cytosolic FPGS not encoded by all previously identified (Roy, K., Mitsugi, K., and Sirotnak, F. M. (1996) J. Biol. Chem., 271, 23820-23827) splice variants. It was also found by direct sequencing of genomic fragments that although exon A1b is spliced to exon 2, these new alternatives (i.e. exons A1a and A1b) to exon 1 are found approximately 9.5 kilobases upstream from exons B1a, B1b, and B1c. Exons A1a and A1b are separated from each other by a 124-nucleotide intron. Sequencing of the region 5' to exon A1a revealed a nucleotide sequence that was promoter-like and different from the downstream promoter region in the content of putative cis-acting elements. Primer extension analysis identified a number of potential transcription start sites within the more 3' end of this region. FPGS RNA transcripts incorporating exons A1a and A1b were detected in both normal mouse tissues, particularly, liver and kidney, and also to a varying extent in tumors; FPGS RNA transcripts incorporating exons B1a, B1b, and B1c were detected mainly in tumors. Thus, transcription of the FPGS gene in this tissue-specific manner appears to reflect the different usage of alternates to exon 1 under the control of different promoters. An unusual splice variant identified infrequently in a mouse liver cDNA library was 2.67 kilobases in size and incorporated exons A1a and A1b and a segment of the downstream promoter region along with exons B1c and B1b and exons 2-15.