Genotype List String: a grammar for describing HLA and KIR genotyping results in a text string

Knowledge of an individual's human leukocyte antigen (HLA) genotype is essential for modern medical genetics, and is crucial for hematopoietic stem cell and solid-organ transplantation. However, the high levels of polymorphism known for the HLA genes make it difficult to generate an HLA genotype that unambiguously identifies the alleles that are present at a given HLA locus in an individual. For the last 20 years, the histocompatibility and immunogenetics community has recorded this HLA genotyping ambiguity using allele codes developed by the National Marrow Donor Program (NMDP). While these allele codes may have been effective for recording an HLA genotyping result when initially developed, their use today results in increased ambiguity in an HLA genotype, and they are no longer suitable in the era of rapid allele discovery and ultra-high allele polymorphism. Here, we present a text string format capable of fully representing HLA genotyping results. This Genotype List (GL) String format is an extension of a proposed standard for reporting killer-cell immunoglobulin-like receptor (KIR) genotype data that can be applied to any genetic data that use a standard nomenclature for identifying variants. The GL String format uses a hierarchical set of operators to describe the relationships between alleles, lists of possible alleles, phased alleles, genotypes, lists of possible genotypes, and multilocus unphased genotypes, without losing typing information or increasing typing ambiguity. When used in concert with appropriate tools to create, exchange, and parse these strings, we anticipate that GL Strings will replace NMDP allele codes for reporting HLA genotypes.

A novel activating function of c-Src and Stat3 on HGF transcription in mammary carcinoma cells

In the normal breast, hepatocyte growth factor (HGF) is primarily expressed by stromal cells, and stimulates in a paracrine manner epithelial cells expressing the HGF receptor (Met). In invasive human breast carcinomas, HGF and Met are frequently overexpressed, possibly establishing an autocrine HGF/Met loop that promotes tumour cell invasion. However, the mechanisms leading to autocrine HGF expression in carcinoma cells are not known. We previously demonstrated a cooperative effect between c-Src and Stat3 in the activation of HGF transcription in mammary carcinoma cells. The present report defines a novel Stat3 consensus site at nt -95 in the HGF promoter that is highly conserved in human and mouse, and is required for c-Src and Stat3 to activate HGF transcription in breast epithelial cells. DNA-protein binding studies demonstrated high affinity binding of a Stat3-containing complex to the nt -95 site. Endogenous Stat3 binding to this region of the HGF promoter in carcinoma cells expressing HGF was demonstrated using a chromatin immunoprecipitation assay. In addition, coexpression of Stat3 and activated c-Src caused increased expression of endogenous HGF mRNA and protein and marked cell scattering in breast epithelial cells. Our results delineate a novel c-Src/Stat3-dependent mechanism that regulates HGF promoter activity, and is linked to transformation of mammary epithelial cells.

Control of mitochondrial biogenesis during myogenesis

We used expression and reporter gene analysis to understand how changes in transcription factors impinge on mitochondrial gene expression during myogenesis of cultured murine myoblasts (C2C12 and Sol8). The mRNA levels for nuclear respiratory factor-1 (NRF-1) and NRF-2α increased 60% by the third day of myogenesis, whereas NRF-1 and NRF-2 reporter gene activity increased by fivefold over the same period. Although peroxisome proliferator activated receptor (PPARα) mRNA levels increased almost 10-fold, the activity of a PPAR reporter was unchanged during myogenesis. The PPAR coactivator PPAR-γ coactivator-1α (PGC1α), a master controller of mitochondrial biogenesis, was not expressed at detectable levels. However, the mRNA for both PGC1α-related coactivator and PGC1β was abundant, with the latter increasing by 50% over 3 days of differentiation. We also conducted promoter analysis of the gene for citrate synthase (CS), a common mitochondrial marker enzyme. The proximal promoter (∼2,100 bp) of the human CS lacks binding sites for PPAR, NRF-1, or NRF-2. Deletion mutants, a targeted mutation, and an Sp1 site-containing reporter construct suggest that changes in Sp1 regulation also participate in mitochondrial biogenesis during myogenesis. Because most mitochondrial genes are regulated by PPARs, NRF-1, and/or NRF-2, we conducted inhibitor studies to further support the existence of a distinct pathway for CS gene regulation in myogenesis. Although both LY-294002 (a phosphatidylinositol 3-kinase inhibitor) and SB-203580 (a p38-MAPK inhibitor) blocked myogenesis (as indicated by creatine phosphokinase activity), only SB-203580 prevented the myogenic increase in cytochrome oxidase activity, whereas only LY-294002 blocked the increase in CS (enzyme and reporter gene activities). Collectively, these studies help delineate the roles of some transcriptional regulators involved in mitochondrial biogenesis associated with myogenesis and underscore an import role for posttranscriptional regulation of transcription factor activity.

Aedes aegypti phosphohexomutases and uridine diphosphate-hexose pyrophosphorylases: comparison of primary sequences, substrate specificities and temporal transcription

Phosphohexomutases reversibly catalyse the transfer of the phosphate group of a glycosyl phosphate between the C6 and C1 positions, and uridine diphosphate (UDP)-hexose pyrophosphorylases catalyse the synthesis of UDP-hexose from uridine triphosphate (UTP) and hexose-1-phosphate. Both enzyme families are essential for nucleoside diphosphate hexose biosynthesis and are therefore critical for various physiological functions in the midgut of mosquitoes after a blood meal. We cloned and sequenced three phosphohexomutase and two UDP-hexose pyrophosphorylase cDNAs from Aedes aegypti. The products of the cDNAs were expressed and substrate specificities were examined. Herein we describe Ae. aegypti phosphoglucomutase 1, phosphoglucomutase 2, phosphoacetylglucosamine mutase, UDP-glucose pyrophosphorylase, and UDP-N-acetylglucosamine pyrophosphorylase. Transcripts of the genes expressing the enzymes are constitutively present in all life stages and blood-feeding does not seem to influence transcript abundance.

External quality assessment for mutation detection in the BRCA1 and BRCA2 genes: EMQN's experience of 3 years

BACKGROUND

The European Molecular Genetics Quality Network (EMQN) was formed in order to improve external quality assessment for molecular genetic testing in Europe. From 1999 to 2002 it received funding from the European Union under the Standards, Measurement and Testing programme (contract no. SMT4-CT98-7515). Since then, its maintenance has been supported through subscription of the participants, and it has been coordinated by the National Genetic Reference Laboratory at Manchester, UK (Rob Elles and Simon Patton; www.emqn.org).

MATERIALS AND METHODS

Among other external quality assessment (EQA) schemes, EMQN has provided an EQA scheme for mutation detection in the breast cancer genes, BRCA1 and BRCA2, designed to cover the two important aspects of genetic testing: (i) genotyping and (ii) interpretation and reporting of results. The fourth full scheme was completed in 2003, with data evaluation pending for the 47 participants.

RESULTS

Analysis of genotyping data has pinpointed two main types of errors: (i) missing a mutation (in nine of the 17 false results a normal sequence was reported); and (ii) description of the observed sequence change by an incorrect nomenclature. Compared with the more technical process of genotyping, the writing of reports displayed a much wider variation between laboratories.

CONCLUSIONS

From the reported data it is clear that external quality control should become an integral part of quality assessment in the laboratory, thus contributing to maintaining confidence in the reliability of genetic testing among patients and health professionals.

Leptin and the control of respiratory gene expression in muscle

Leptin plays a central role in the regulation of fatty acid homeostasis, promoting lipid storage in adipose tissue and fatty acid oxidation in peripheral tissues. Loss of leptin signaling leads to accumulation of lipids in muscle and loss of insulin sensitivity secondary to obesity. In this study, we examined the direct and indirect effects of leptin signaling on mitochondrial enzymes including those essential for peripheral fatty acid oxidation. We assessed the impact of leptin using the JCR:LA-cp rat, which lacks functional leptin receptors. The activities of marker mitochondrial enzymes citrate synthase (CS) and cytochrome oxidase (COX) were similar between wild-type (+/?) and corpulent (cp/cp) rats. In contrast, several tissues showed variations in the fatty acid oxidizing enzymes carnitine palmitoyltransferase II (CPT II), long-chain acyl-CoA dehydrogenase (LCAD) and 3-hydroxyacyl-CoA dehydrogenase (HOAD). It was not clear if these changes were due to loss of leptin signaling or to insulin insensitivity. Consequently, we examined the effects of leptin on cultured C(2)C(12) and Sol8 cells. Leptin (3 days at 0, 0.2, or 2.0 nM) had no direct effect on the activities of CS, COX, or fatty acid oxidizing enzymes. Leptin treatment did not affect luciferase-based reporter genes under the control of transcription factors involved in mitochondrial biogenesis (nuclear respiratory factor-1 (NRF-1), nuclear respiratory factor-2 (NRF-2)) or fatty acid enzyme expression (peroxisome proliferator-activated receptors (PPARs)). These studies suggest that leptin exerts only indirect effects on mitochondrial gene expression in muscle, possibly arising from insulin resistance.

Spectral karyotype analysis of colon cancer cell lines of the tumor suppressor and mutator pathway

BACKGROUND AND AIMS

Microsatellite instability (MSI) is characterized by the size variation of microsatellites in tumor DNA as compared to matching normal DNA due to defects in the mismatch repair system. To examine the chromosomal differences in microsatellite-stable (MSS) and -unstable (MSI) tumors in detail, we analyzed MSS (Caco-2, Colo-205, SW948) and MSI (HCT-15, HCT-116, LoVo) cell lines by spectral karyotyping (SKY).

METHODS

SKY is a sensitive method to detect chromosome aberrations by visualizing each chromosome in a different color. Metaphases were hybridized with a SKY probe mixture. Images were visualized with the SpectraCube system and analyzed with the SKYview imaging software.

RESULTS

The average number of chromosomes was 49 in LoVo, 45 in HCT-116, 46 in HCT-15, 71 in Colo-205, 89 in Caco-2 and 66 in SW-948. Three aberrant chromosomes were detected in LoVo, three in HCT-116, two in HCT-15, seventeen in Colo-205, fourteen in Caco-2 and nine in SW948.

CONCLUSION

The karyotypes of MSS colon cancer cells displayed complex numerical and structural aberrations. In contrast the chromosomes of MSI colon cancer cells were mostly unaltered but displayed a few isolated numerical and structural aberrations. We speculate that these isolated aberrations may be specifically involved in the pathogenesis of MSI tumors.

Recent advances in the diagnosis of malignant hyperthermia susceptibility: how confident can we be of genetic testing?

Malignant hyperthermia (MH) is a condition that manifests in susceptible individuals only on exposure to certain anaesthetic agents. Although genetically heterogeneous, mutations in the RYR1 gene (19q13.1) are associated with the majority of reported MH cases. Guidelines for the genetic diagnosis for MH susceptibility have recently been introduced by the European MH Group (EMHG). These are designed to supplement the muscle biopsy testing procedure, the in vitro contracture test (IVCT), which has been the only means of patient screening for the last 30 years and which remains the method for definitive diagnosis in suspected probands. Discordance observed in some families between IVCT phenotype and susceptibility locus genotype could limit the confidence in genetic diagnosis. We have therefore assessed the prevalence of 15 RYR1 mutations currently used in the genetic diagnosis of MH in a sample of over 500 unrelated European MH susceptible individuals and have recorded the frequency of RYR1 genotype/IVCT phenotype discordance. RYR1 mutations were detected in up to approximately 30% of families investigated. Phenotype/genotype discordance in a single individual was observed in 10 out of 196 mutation-positive families. In five families a mutation-positive/IVCT-negative individual was observed, and in the other five families a mutation-negative/IVCT-positive individual was observed. These data represent the most comprehensive assessment of RYR1 mutation prevalence and genotype/phenotype correlation analysis and highlight the possible limitations of MH screening methods. The implications for genetic diagnosis are discussed.

Phenotyping malignant hyperthermia susceptibility by measuring halothane-induced changes in myoplasmic calcium concentration in cultured human skeletal muscle cells

BACKGROUND

Malignant hyperthermia (MH) is a potentially lethal disease triggered by volatile anaesthetics and succinylcholine in genetically predisposed individuals. Because of the heterogenetic nature of MH, a simple genetic-based diagnostic test is not feasible and diagnosis requires an invasive open muscle biopsy followed by the in vitro contracture test (IVCT). Our aim was to establish if measurements of halothane-induced increases in intracellular calcium ion concentration [Ca(2+)](i) in cultured human skeletal muscle cells can be used to phenotype MH susceptibility and if different mutations in the ryanodine receptor (RYR1) gene affect halothane-induced increases in [Ca(2+)](i).

METHODS

Primary cultures of human skeletal muscle cells were established from 54 individuals diagnosed by the IVCT according to the protocol of the European MH Group as: MH susceptible (n=22), MH negative (n=18) or MH equivocal (n=14). All individuals were screened for the presence of the most common mutations in the RYR1 gene. [Ca(2+)](i) was measured by fluorescent digital microscopy using fura-2/AM in 10 cells from each patient at five different halothane concentrations.

RESULTS

The halothane-induced increase in [Ca(2+)](i) differed significantly between the three diagnostic groups. Different mutations of the RYR1 gene did not have a specific impact on halothane-induced increases in [Ca(2+)](i).

CONCLUSIONS

Measurements of [Ca(2+)](i) in human skeletal muscle cells can be used to phenotype MH susceptibility; however, we did not observe a specific effect of any mutation in the RYR1 gene on the halothane-induced increase in [Ca(2+)](i).

Detection of microdeletions in the short arm of the X chromosome by chromosome stretching

The present study was focused on the resolution of "chromosome stretching". In order to determine if this method can be used for the detection of microdeletions, the p-arms of 13 normal X chromosomes were stretched as well as of those with three different deletions of known size within the DMD/BMD region in Xp21 (case A: 0.42-0.45 Mb, case B: 2.3-2.9 Mb and case C: 3.0-3.5 Mb). The process of band splitting was recorded on a video-tape and the resulting banding pattern analyzed. Stretching of the normal Xp-arms led to a splitting on a maximum band level of 1400 and showed in all cases an identical banding pattern with 13 Giemsa-dark subbands. All new Giemsa-dark and -light subbands were derived from the three initial Giemsa-dark bands at the 400 band level according to ISCN (1995): five subbands from Xp21, four subbands from Xp11.3 and Xp22.2, respectively. The origin of these subbands is partly in contrast to the high resolution ISCN (1995) ideograms: subband Xp11.22 does not originate from the Giemsa-light band Xp11.2, but from the Giemsa-dark band Xp11.3; Xp22.12 originates from Xp21; Xp22.32 from Xp22.2. Stretching of the chromosomes containing deletions showed in cases A and B no differences in banding patterns and splitting order compared to normal X chromosomes. Only in patient C was a significant difference with the normal pattern visible due to the absence of one dark subband. In this case only four Giemsa-dark subbands derived from band Xp21. Thus, at least in the DMD/BMD region, the minimal size of a deletion detected by chromosome-stretching-generated high-resolution ideograms is about 3.0-3.5 Mb.

A CREB site in the BRCA1 proximal promoter acts as a constitutive transcriptional element

Transcriptional regulation of the BRCA1 proximal promoter has been suggested to play a role in the decreased expression of BRCA1 observed in sporadic breast cancer. Computer analysis of the sequence of the proximal promoter reveals the presence of a potential CREB site. We have identified CREB/ATF-1 as the factor interacting with this site in nuclear extracts from MCF-7 and T-47D cells. This site is shown to be important for the constitutive expression of the promoter in these cells, as well as in Hep G2 cells. Despite the presence of this site, the BRCA1 promoter is not responsive to cAMP induction. It appears that CREB acts as a constitutive positive element for BRCA1 expression and that any mechanism inactivating CREB function would have a dramatic effect on BRCA1 expression.

Genotype-phenotype comparison of the Swiss malignant hyperthermia population

Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disease, triggered by inhalative anesthetics or depolarizing muscle relaxants in genetically predisposed individuals. Linkage analysis have revealed MH to be a heterogenetic disease with about 50% of MH families linked to the locus of the ryanodine receptor calcium channel (RYR1). We investigated the frequency of the 23 published MH linked RYR1 gene mutations in the Swiss MH population and compared our findings to the results of the in vitro contracture test (IVCT). IVCT was performed following the protocol of the European MH Group and mutation screening was done by PCR amplification of genomic DNA followed by restriction enzyme digestion or SSCP. We identified RYR1 gene mutations in 40% of unrelated MH families (19/48) with a high incidence of the mutation V2168M (27%). IVCT results revealed a significantly stronger functional effect of mutations R614C and V2168M as compared to mutations G2434R and R2458C. This is the first time that such a high incidence of RYR1 gene mutations in an MH population has been found, supporting the use of molecular genetic testing for the diagnosis of MH susceptibility in suitable families. In addition our data show that different RYR1 gene mutations are associated with different IVCT phenotypes.

Clustering of FGFR2 gene mutations inpatients with Pfeiffer and Crouzon syndromes (FGFR2-associated craniosynostoses)

A cohort of 36 unrelated German patients with craniosynostosis syndromes of the Crouzon and Pfeiffer type were analyzed for FGFR mutations. Mutations in FGFR2 were identified in 25 Crouzon and 5 Pfeiffer syndrome patients, whereas no sequence alterations were found in the remaining patients, even after screening of the relevant parts of FGFR1, FGFR3, and TWIST. Mutations in FGFR2 clustered at two critical cysteine residues, 278 and 342, which were involved in 18 of 30 cases (60%). These two mutational hot spots, therefore, are prime targets for an efficient mutation-screening strategy. The spectrum of mutations overlapped the two syndromes and thus reflected the phenotypic similarities observed in both patient groups. In 21 families, the origin of the mutation could be traced by analyzing parents and relatives. Eleven mutations arose de novo, indicating a high mutation rate for FGFR2. In the 10 familial cases, the clinical presentation varied considerably within the pedigree, but both syndromes "bred true," i.e., a Pfeiffer syndrome phenotype was never observed in a Crouzon syndrome family and vice versa.

Proof of genetic heterogeneity in the proximal myotonic myopathy syndrome (PROMM) and its relationship to myotonic dystrophy type 2 (DM2)

Recently, myotonic dystrophy type 2 has been described as a separate disease entity that is distinctive from classical Steinert's disease since it lacks a CTG repeat expansion on chromosome 19q. A gene locus for myotonic dystrophy type 2 has been mapped to chromosome 3q. Independently, proximal myotonic myopathy has been recognized as yet another form of a multisystem myotonic disorder. Its relationship to myotonic dystrophy type 2 remains to be clarified. In our linkage study of 17 German proximal myotonic myopathy families nine of them mapped to the myotonic dystrophy type 2 locus (LOD score 18.9). However, two families with a typical proximal myotonic myopathy phenotype were excluded from this locus (LOD score -7.4). These results confirm genetic heterogeneity in the proximal myotonic myopathy syndrome. Furthermore, in the majority of the proximal myotonic myopathy families the disease phenotype may be caused by allelic mutations in the putative myotonic dystrophy type 2 gene.

GA-binding protein alpha/beta is a critical regulator of the BRCA1 promoter

Decreased expression of BRCA1 may play a role in the etiology of sporadic breast cancer. Deletion and point mutant analysis of proximal promoter elements in the BRCA1 1a promoter revealed a 22 bp region which was critical for the expression of the promoter in MCF-7 cells, but had a much reduced effect in T47D cells. The main transcription factor interacting with this site was identified as GABPalpha/beta, and a discrete DNA binding complex was only observed in nuclear extracts from MCF-7 cells. Cotransfection experiments with GABPalpha and beta1 expression vectors produced transactivation of this element in both lines. These results suggest that GABPalpha/beta is a critical activator of BRCA1 expression, and that its activity may differ in human breast cell lines.

D-site binding protein transactivation requires the proline- and acid-rich domain and involves the coactivator p300

The D-site binding protein (DBP) is a member of the proline- and acid-rich (PAR) domain subfamily of basic/leucine zipper proteins and is involved in transcriptional regulation in the liver. Deletion analysis of the DBP protein was carried out in an effort to define the function of the conserved PAR domain. Internal deletions of the protein, i.e. removing portions of the PAR domain, resulted in a substantial loss in transactivation of a high affinity DBP reporter construct when assayed in Hep G2 cells. These same sequences conferred significant transactivation to GAL4 DNA binding domain fusion proteins, indicating that this region acts as part of an independent activation domain comprised of sequences in both the amino terminus and in the PAR domain of DBP. The coexpression of full-length expression constructs for both DBP and hepatic leukemia factor resulted in a dramatic increase in activation mediated by the GAL4-DBP fusion proteins, suggesting the involvement of a regulated coactivator in this process. DBP transactivation appears to be a p300-dependent process, as a 12 S E1A expression construct disrupted DBP-mediated transactivation, and a p300 expression vector, but not a CREB binding protein vector, was able to restore DBP transactivation. These results suggest that the PAR domain is required for DBP activation, which occurs through a regulated, p300-dependent process.

Identification and characterization of a transcript for a novel Rac GTPase-activating protein in terminally differentiating 3T3-L1 adipocytes

Using differential display, we sought to identify novel genes expressed in the early stages of 3T3-L1 adipocyte differentiation. A gene which we have named "band25" was identified, and a full-length cDNA sequence was assembled. Sequence analysis revealed that the 2842-bp cDNA encodes a putative 628-amino acid protein product, which is a member of the GTPase-activating protein (GAP) family. This gene may be the murine homolog of the human MgcRacGAP protein, which was identified in male germ cells. Other closely related proteins include the Drosophila protein Rotund, several chimerins, and the human breakpoint cluster region (Bcr) protein. These GAP proteins all specifically inactivate Rac, a member of the Ras-like family of proteins. A consensus sequence for a diacyl glycerol/phorbol ester-binding domain was also found in the Band25 sequence. The expression of band25 mRNA is regulated during the differentiation of both adipocytes and myoblasts. Its mRNA was shown to be expressed at a low level in confluent 3T3-L1 preadipocytes and in differentiated 3T3-L1 adipocytes. Expression of band25 was increased 15.5 fold by 24 h after the induction of differentiation, when 3T3-L1 cells undergo several rounds of postconfluent cell division. Expression was also high in growing 3T3-L1 and C2C12 cells but decreased progressively as C2C12 cells underwent differentiation. These observations suggest that the expression of band25 is growth regulated and that the protein could play a role in the regulation of growth-related processes.

Linkage of proximal myotonic myopathy to chromosome 3q

We performed genetic linkage analysis in nine German proximal myotonic myopathy (PROMM) families using DNA-markers D3S1541 and D3S1589 from the region of the recently discovered gene locus of myotonic dystrophy type 2 (DM2) on chromosome 3q. Two-point analysis supplied an lod score of 5.9. We conclude that a gene causing PROMM is located on chromosome 3q. PROMM and DM2 may be allelic disorders or may be caused by closely linked genes.

Genomic sequence and organization of the human gene for cytochrome c oxidase subunit (COX7A1) VIIa-M

Cytochrome c oxidase (COX, EC 1.9.3.1), the last component of the mitochondrial electron transfer chain, is built up by 13 polypeptides; 3 of them are encoded by the mitochondrial genome while the 10 smaller subunits are encoded by the nuclear genome. Several nuclear-encoded subunits occur in two different tissue-specific isoforms, a constitutive "L"-form and an "M"-form specific for skeletal and heart muscle. In this article, we describe the genomic sequence and organization of the human gene for COX subunit VIIa-M (COX7A1) located on chromosome 19q13.1 and compare it to its bovine homologue. The coding region of the gene extends over 1.45 kb of genomic sequence, organized in four exons. Intron-exon boundaries are well conserved between cattle and humans. Although it is a gene for a tissue-specific isoform, it has some features of a housekeeping gene: it is located in a CpG island, like its bovine homologue, and no TATA or CCAAT boxes were found in the 5' flanking sequence. Southern hybridization of COX7A1 to human genomic DNA revealed no pseudogenes. Putative binding sites for ubiquitous transcription factors like Sp1 and specific expression in skeletal as well as in heart muscle have been found. In contrast to the bovine gene, the human gene contains putative binding sites for nuclear respiratory factor 2 (NRF-2), which is implicated in the activation of other respiratory enzymes. Therefore, the human and the bovine genes, although well conserved in their coding regions, could differ in the tissue-specific regulation of gene expression. Knowledge of the gene structure will facilitate the analysis of the involvement of subunit VIIa in mitochondrial myopathies and may provide clues to the function of this subunit in a multicomponent enzyme.

A genome wide search for susceptibility loci in three European malignant hyperthermia pedigrees

Malignant hyperthermia (MH) is an autosomal dominant disorder which is potentially lethal in susceptible individuals on exposure to commonly used inhalational anaesthetics and depolarising muscle relaxants. Crises reflect the consequences of disturbed skeletal muscle calcium homeostasis. Susceptibility was first localised to chromosome 19q13.1 and the skeletal muscle ryanodine receptor, RYR1 (the calcium release channel of the sarcoplasmic reticulum). Defects in this gene have been identified which cosegregate with the MHS phenotype and evidence as to their potential causal roles has accumulated. MH has, however, been shown to be genetically heterogeneous, additional loci on chromosomes 3q, 17q and 7q being proposed. Pedigrees remain in Europe where linkage status is still unclear. In a collaborative search of the human genome conducted with three pedigrees whose disease status was classified according to the European IVCT protocol we have evidence to suggest that at least two further loci exist for MH susceptibility. One of these locates to chromosome 1q, the site of a candidate gene, CACNL1A3, encoding the alpha-subunit of the dihydropyridine receptor. The second region resides on chromosome 5p to where no known candidate has been mapped to date. The third family exhibited inconclusive results which suggests the existence of at least one other locus. This study adds to the evidence for considerable genetic heterogeneity in MH and will provide a route to further our understanding of the molecular pathology of the condition.

Casein kinase II-mediated phosphorylation of the C terminus of Sp1 decreases its DNA binding activity

We have previously observed that Sp1, a ubiquitous zinc finger transcription factor, is phosphorylated during terminal differentiation in the whole animal, and this results in decreased DNA binding activity (Leggett, R. W., Armstrong, S. A., Barry, D., and Mueller, C. R. (1995) J. Biol. Chem. 270, 25879-25884). In this study, we demonstrate that casein kinase II (CKII) is able to phosphorylate the C terminus of Sp1 and results in a decrease in DNA binding activity. This suggests that CKII may be responsible for the observed regulation of Sp1. Mutation of a consensus CKII site at amino acid 579, within the second zinc finger, eliminates phosphorylation of this site and the CKII-mediated inhibition of Sp1 binding. Phosphopeptide analysis confirms the presence of a CKII site at Thr-579 as well as additional sites within the C terminus. No gross changes in CKII subunit levels were seen during de-differentiation associated with liver regeneration. The serine/threonine phosphatase PP1 was identified as the endogenous liver nuclear protein able to dephosphorylate Sp1 but again no gross changes in activity were observed in the regenerating liver. Okadaic acid treatment of K562 cells increases Sp1 phosphorylation and inhibits its DNA binding activity suggesting that steady state levels of Sp1 phosphorylation are established by a balance between kinase and phosphatase activities.

Genomic structure of the human D-site binding protein (DBP) gene

The human gene for the D-Site Binding Protein (DBP) has been sequenced and characterized. This gene is a member of the b/ZIP family of transcription factors and is one of three genes forming the PAR subfamily. DBP has been implicated in the diurnal regulation of a variety of liver-specific genes. Examination of the genomic structure of DBP reveals that the gene is divided into four exons and is contained within a relatively compact region of approximately 6 kb. These exons appear to correspond to functional divisions of the DBP protein. Exon 1 contains a long 5' UTR, and conservation between the rat and the human genes of the presence of small open reading frames within this region suggests that it may play a role in translational control. Exon 2 contains a limited region of similarity to the other PAR domain genes, which may be part of a potential activation domain. Exon 3 contains the PAR domain and differs by only 1 of 71 amino acids between rat and human. Exon 4, containing both the basic and the leucine zipper domains, is likewise highly conserved. The overall degree of homology between the rat and the human cDNA sequences is 82% for the nucleic acid sequence and 92% for the protein sequence. Comparison of the rat and human proximal promoters reveals extensive sequence conservation, with two previously characterized DNA binding sites being conserved at the functional and sequence levels.

Binding of the Ets factor GA-binding protein to an upstream site in the factor IX promoter is a critical event in transactivation

Factor IX is an essential vitamin K-dependent serine protease that participates in the intrinsic pathway of coagulation. The protein is expressed exclusively in the liver. The rare Leyden form of hemophilia B (inherited factor IX deficiency) results from point mutations in three proximal promoter elements that decrease factor IX expression. Recovery of expression occurs following puberty, with factor IX protein levels rising into the normal range. We have previously implicated the PAR domain D-site-binding protein (DBP) as well as an upstream element, site 5, as playing important roles in the phenotypic recovery of hemophilia B Leyden. Here we demonstrate that site 5 binds both the CCAAT/enhancer-binding protein (C/EBPalpha) and the ubiquitous Ets factor GA-binding protein (GABPalpha/beta). Transactivation of the factor IX promoter by the PAR proteins DBP and hepatic leukemia factor (HLF) is dependent on the binding of GABPalpha/beta to site 5, and coexpression of these two factors is required for optimal activation of this promoter. The binding of C/EBPalpha to site 5 also augments the activity of GABPalpha/beta. Analysis of the developmental regulation of site 5-binding proteins in rat liver has shown that C/EBPalpha and the GABPbeta subunit increase markedly in the 2 weeks after birth. These observations establish a functional association between the Ets factor GABPalpha/beta and C/EBPalpha and indicate that the two PAR proteins, DBP and HLF, may play complementary roles in factor IX activation. Given the developmental changes exhibited by these proteins, it is likely that they play a role in regulation of the normal factor IX promoter as well as promoters carrying hemophilia B Leyden mutations.

Role of the liver-enriched transcription factor hepatocyte nuclear factor 1 in transcriptional regulation of the factor V111 gene

Coagulation factor VIII is an essential cofactor required for normal hemostatic function. A deficiency in factor VIII results in the bleeding disorder hemophilia A. Despite the fact that the factor VIII gene was cloned a decade ago, the mechanisms which control its transcription remain unresolved. In our studies, we have characterized 12 protein binding sites within the factor VIII promoter by DNase I protection assays performed with rat liver nuclear extracts. Three of these elements (sites 1 to 3) are situated within the 5' untranslated region of the gene, while three other sites (sites 4 to 6) lie within the first 100 bp upstream of the transcriptional start site. We have identified an additional site (site 7) approximately 300 bp upstream from site 6, as well as a cluster of five sites in a 250-bp region which terminates approximately 1 kb from the transcriptional start site. Seven of these binding sites (sites 2, 3, 4, 6, 7, 9, and 10) bind members of the C/EBP family of transcription factors. DBP also binds to five of these sites (sites 3, 4, 6, 7, and 9). Utilizing transient transfection studies in HepG2 cells, we have shown that deletion of the factor VIII promoter sequences distal to nucleotide -44 results in a significant but small increase in promoter activity. The activity of each of the various 5' deletion constructs is significantly enhanced by cotransfection of C/EBPalpha and D-site-binding protein expression plasmids, while cotransfection of both C/EBPalpha and C/EBPbeta plasmids resulted in a further enhancement of transactivation. These studies also provide evidence of a repressor element located between nucleotides -740 and -1002. Since the minimal promoter sequence (-44 to +148) maintains the transcriptional activity of the full-length promoter sequence, we proceeded to identify additional factors binding to sites 1 to 4. Competition studies revealed that a ubiquitous transcription factor, NF-Y, binds to site 4, while the liver-enriched transcription factor hepatocyte nuclear factor I (HNF-1) binds to site 1. Mutation analysis of the minimal promoter demonstrated that HNF-1 is critical for activating transcription of the factor VIII gene in vitro. Our results also suggest that the multiple upstream elements that we have identified may act as a backup regulatory region in the event of disruption of the HNF-1 element in the 5' untranslated region.

Trocar site seeding of inapparent gallbladder carcinoma during laparoscopic cholecystectomy

There are increasing reports of seeding of tumor at the trocar sites following laparoscopic cholecystectomy in patients with unexpected or inapparent gallbladder carcinoma. A patient is reported here whose primary tumor appeared controlled by surgery and radiation, but who died of the disease after developing implant metastases at three untreated trocar sites. The second case report illustrates the difficulty in identifying gallbladder cancer during laparoscopic cholecystectomy, and the importance of a diligent preoperative effort to establish the diagnosis. Current literature suggests that tumor implantation occurring during laparoscopic cholecystectomy for inapparent carcinoma adversely affects prognosis, and, until the effect of laparoscopy on the spread of this tumor is better understood and controlled, open operation should be performed when carcinoma of the gallbladder is suspected. When laparoscopic cholecystectomy is done for inapparent gallbladder cancer, surgical and adjuvant radiotherapy to the trocar sites appears to improve outcome in association with extended treatment to the gallbladder bed and adjacent areas. Recent reports suggest that progress in diagnostic, surgical, and adjuvant techniques could substantially improve survival in carcinoma of the gallbladder.

Multidisciplinary research of multimodal stimulation of premature infants: an integrated review of the literature

PURPOSE

To review and integrate current multidisciplinary research literature about multiple sensory stimulation of premature infants.

SOURCES

Computer search using CINAHL, MEDLINE, PSYLIT, SOCIAL SCIENCE INDEX and the topics "premature," "infant," "neonate," and "stimulation." Review of the results of the research and integration of findings for nursing.

RESULTS

Overall, infants responded positively to the interventions reviewed, including immediate and long-term effects, some up to 2 years.

IMPLICATIONS FOR NURSING PRACTICE

Nursing research of multiple sensory stimulation of premature infants can be improved by the use of (a) a theoretical base for research, (b) better descriptions of the infant samples and the environmental context of the research, and (c) individualization of infant stimulation to permit conservation of epigenetic integrity of the infant.

Sp1 is phosphorylated and its DNA binding activity down-regulated upon terminal differentiation of the liver

Using nuclear extracts prepared from rat liver it was demonstrated that binding of a transcription factor to site II of the D-site binding protein promoter could be induced by dephosphorylation of these extracts. Competition band shifts and supershift assays reveal this protein to be the general transcription factor Sp1. Phosphorylation of Sp1 appears to occur as a result of terminal differentiation of the liver. Proteins from both 1-day-old rat liver and adult liver undergoing regeneration have less of the phosphorylated form of Sp1 present with consequent increased DNA binding activity. Sp1 is similarly phosphorylated in brain, kidney, and spleen with phosphatase treatment of the extracts significantly increasing the level of DNA binding activity. Dephosphorylation of Sp1 results in a 10-fold increase in the affinity of Sp1 for its cognate site. Two-dimensional gel electrophoresis reveals that approximately 20% of the detectable protein appears to be in the phosphorylated form in adult liver extracts. Another protein with similar characteristics also appears to be present in the liver. Decreasing Sp1 DNA binding activity by phosphorylation may be an important mechanism for regulating gene expression, and possibly bringing about growth arrest during terminal differentiation.

Treatment of metastatic carcinoid tumors using multimodality therapy of octreotide acetate, intra-arterial chemotherapy, and hepatic arterial chemoembolization

BACKGROUND

Overall survival and quality of life in patients with metastatic carcinoid tumors depend on control of tumor growth and suppression of amine-induced symptoms.

METHODS

We report on a series of 10 patients with carcinoid tumors metastatic to the liver who were treated with long-term octreotide acetate therapy (100 to 500 micrograms three times a day), sequential intra-arterial 5-fluorouracil (5-FU) infusions, and hepatic tumor chemoembolization.

RESULTS

All 10 patients remained asymptomatic or had extremely mild symptoms after combined modality therapy (mean follow-up duration of 51.5 months). Sixty percent of the patients had a > 50% reduction of their tumor size (mean duration 42 months). An additional 30% experienced stabilization of tumor growth for 6 months or longer. Five of the 10 patients are currently alive. The mean group survival is 58 months since diagnosis (range 33 to 115) and 40 months since starting therapy (range 12 to 65).

CONCLUSIONS

Combining octreotide acetate, intra-arterial 5-FU, and tumor chemoembolization effectively retards tumor growth while providing excellent symptom control.

Transcriptional control of the factor IX gene: analysis of five cis-acting elements and the deleterious effects of naturally occurring hemophilia B Leyden mutations

Hemophilia B Leyden is a rare form of inherited factor IX deficiency in which patients experience spontaneous postpubertal recovery of factor IX levels. The mutations resulting in this disorder are localized in a 40-nucleotide region encompassing the major transcriptional start site for factor IX. Here we report the further characterization of five cis-acting elements in the factor IX promoter and the effects on protein binding and transcriptional activation of five Leyden mutations (at nucleotides +13, -5, -6, -20, and -26) that occur within the proximal three elements (sites 1 through 3). Bandshift studies using nuclear extracts from four different rat tissues have shown that at least some of the proteins binding to each of the five sites are ubiquitous in nature. The pattern of DNA binding at site 1 suggests that this element plays an important role in mediating the liver-specific expression of factor IX. Additional studies with liver nuclear extracts obtained at several different points in development have shown an increase in DNA binding at sites 1, 4, and 5 between 1 day and 1 week. Using DNase I footprint analysis and competition bandshift studies, we have shown that the binding of nuclear proteins to each of the mutant sites is disrupted to a variable extent. There appears to be some, although reduced, protein binding to all of the mutant oligonucleotides apart from the -26 mutant. In vitro transcription assays have shown that each of the mutations reduces the global proximal promoter activity by approximately 40%. Two double mutant promoters did not show any additional downregulation in the in vitro transcription assay. In experiments designed to assess the relative transcriptional activity mediated from each of the five sites independently, we have tested artificial homopolymer promoters of each site in the in vitro transcription assay. These studies show that sites 4 and 5 are the strongest activators and that transactivation from site 5 is further enhanced by the albumin D site-binding protein. In summary, these investigations show deleterious effects of each of the Leyden mutations tested on the binding of trans-acting factors and also show disruption of transcriptional activation in a functional in vitro transcription assay. Our results also show that cis-acting elements 4 and 5 are the principal activators of this locus.

Retinoblastoma control element binding proteins are induced during in vivo terminal differentiation of the liver and bind to the DBP promoter

Growth regulation of terminal differentiation was studied by analysis of the promoter of the transcription factor D-site binding protein (DBP) using nuclear extracts from rat liver undergoing regeneration or from normal liver early in development. Four proximal binding sites for nuclear proteins were identified, three of which showed significant quantitative or qualitative changes in associated factors upon growth induction. Two of these sites bound factors common to the retinoblastoma control element and these proteins were induced upon terminal differentiation of the liver. These factors were also rapidly down-regulated upon induction of regenerative growth and consequent dedifferentiation. These results provide a link between the regulation of growth and differentiation in an in vivo model system.

Pharmacokinetics and results of dose escalation in cis-platin hyperthermic isolation limb perfusion

BACKGROUND

We analyzed prospectively collected data on 145 cis-platin hyperthermic isolation limb perfusion (HILPs) for melanoma and soft-tissue sarcoma to determine the pharmacokinetics and maximum tolerable dose of cis-platin. There were 70 melanoma and 75 sarcoma patients. Dosages ranged from 26 to 265 mg/m2. Perfusate and systemic cis-platin levels were measured in patients perfused at doses of 190-200 mg/m2. Tissue levels were measured in patients perfused at 123-209 mg/m2.

METHODS

Cis-platin HILP was well tolerated up to doses of 250 mg/m2 for lower extremities. Higher doses produced toxicities of rhabdomyolysis, myoglobinuria, hyponatremia, and neuropathy. Systemic levels of cis-platin were equivalent to those of routine intravenous administration, while perfusate levels were 33 times higher. Tissue levels of cis-platin were five to six times higher than effective intravenous levels.

RESULTS

Six melanoma patients have developed local recurrences. All were perfused at doses < 120 mg/m2. However, regional nodal recurrences have occurred in six other patients perfused at doses < or = 200 mg/m2. Four sarcomas have recurred locally, but three of them were present at the time of perfusion.

CONCLUSIONS

We conclude that 250 mg/m2 is the maximum tolerable dose of cis-platin for lower-extremity HILPs. Neoadjuvant cis-platin HILP may improve local control rates for sarcomas. However, no tolerable dose of cis-platin provides control of nodal metastases from melanoma.

Synergy between transcription factors DBP and C/EBP compensates for a haemophilia B Leyden factor IX mutation

Haemophilia B Leyden is characterized by low childhood levels of factor IX which gradually increase after puberty, eventually resulting in a return to health. The disease is the result of single nucleotide substitutions within a 40 bp region encompassing the major transcriptional start site. We have characterized transcription factor binding sites within the factor IX promoter. Five sites were identified and a Leyden mutation at nucleotide -5 was shown to interfere with the binding of proteins to one of three newly identified sites. The correlation between the post-pubertal recovery of these mutants and the induction of the transcription factor DBP led us to the discovery of a synergistic interaction between DBP and C/EBP responsible for the recovery of normal transcriptional activity of the -5 mutant promoter and may play a role in the resolution of other Leyden mutants.

The carbamyl phosphate synthetase promoter contains multiple binding sites for C/EBP-related proteins

The promoter of the gene (CPS) encoding rat carbamyl phosphate synthetase I has been mapped 5' to a segment of about 525 nucleotides upstream from the transcription start point and, when analyzed in liver nuclear extracts, contained six well-defined protein-recognition elements, designated CPS sites I-VI. All six elements were recognized, with varying affinities, by CAAT and enhancer-binding protein (C/EBP alpha) produced in bacteria. Oligodeoxyribonucleotides corresponding to CPS site II or to the C/EBP alpha-recognition element of the ALB promoter, site D, competed with the six CPS-promoter elements in footprinting assays. However, mutagenesis of the C/EBP alpha-recognition element, 5'-GTTGCAAC, at the core of site II was sufficient to abolish transactivation of the CPS promoter by C/EBP alpha in co-transfected HepG2 cells. These findings indicate that the CPS promoter contains multiple recognition elements for factors with DNA-binding specificities similar to C/EBP proteins. Activation by C/EBP alpha, however, requires promoter site II.

The down-regulation of albumin transcription during regeneration is due to the loss of HNF-1 and the D-site transcription factors

Liver regeneration has served as an important in vivo model for studying the control of differentiation. The molecular mechanisms responsible for the negative regulation of the albumin promoter during regeneration have not been examined previously. Changes in the proteins interacting with the albumin promoter were characterized using nuclear extracts prepared from the livers of rats undergoing chemically induced regeneration. Reduction in the activities of both hepatocyte nuclear factor-1 (HNF-1) and factors binding to the D site are responsible for the loss of albumin transcription during regeneration. No evidence for the involvement of a transcriptional repressor in this process was found.

Effective palliative treatment of metastatic carcinoid tumors with intra-arterial chemotherapy/chemoembolization combined with octreotide acetate

Survival in patients with metastatic carcinoid tumors is dependent on control of tumor growth and adequate palliation of vasoactive amine-induced symptoms of flushing, diarrhea, wheezing, and valvular heart disease. Eight patients with carcinoid tumors metastatic to the liver were treated with long-term octreotide acetate therapy (100 to 500 micrograms three times a day), intra-arterial 5-fluorouracil infusion (2 g/day x 5 days), and hepatic tumor chemoembolization. All eight patients became asymptomatic and have remained so with a mean follow-up duration of 22 months from the time of first infusion. Following institution of subcutaneous octreotide acetate, intra-arterial infusion, and tumor chemoembolization, all patients are alive with a mean survival of 40 months from the time of diagnosis of carcinoid syndrome (range: 2 to 108 months). Four patients had greater than a 50% decrease in tumor size after therapy (mean follow-up duration: 10.6 months), and the other four patients have had stable disease after institution of therapy. It appears that combinations of long-term subcutaneous administration of octreotide acetate, intra-arterial 5-fluorouracil, and tumor chemoembolization effectively control progressive liver metastasis and provide excellent symptomatic palliation in patients with hepatic metastasis from functional carcinoid tumors.

Acute gastric pH changes alter intraluminal but not plasma peptide levels

Gastric acidity is influenced by systemic and local peptide effects. Previous work by others has shown that intraluminally secreted peptides may have a role in local control of gastric acidity; however, the response of these peptides to acute changes in gastric pH is unknown. To determine the effects of acute changes in pH on systemic and intraluminal peptide levels, 14 normal volunteers underwent placement of a nasogastric tube after an overnight fast. Blood and gastric fluid were analyzed on a control day, 2 hours after completion of 24 hours of aluminum-magnesium antacid therapy and after 24 hours of H2 blockade. Plasma and acid-alcohol-extracted gastric peptide levels were measured with specific radioimmunoassays. Specimens were subdivided into two groups: 28 gastric fluid specimens with a pH less than 4 and 10 specimens with a pH greater than 4. In the patients with a pH greater than 4, the luminal peptides, motilin, neurotensin, pancreatic polypeptide, somatostatin, substance P, and gastrin, were decreased by 50% to 90% and gastrin-releasing peptide was decreased by 36% compared with specimens with a pH less than 4. Conversely, intraluminal vasoactive intestinal polypeptide and calcitonin levels were elevated by 60% and 27%, respectively, in the samples with a pH greater than 4. Intraluminal peptide concentrations are responsive to changes in intragastric pH; however, this response was not seen in plasma peptide levels.

Phase I-II trial of hyperthermic isolated limb perfusion with cisplatin in the treatment of high risk malignant melanoma of the extremities

Between 1983 and 1990, 59 patients with malignant melanoma were retrospectively reviewed to assess the safety, efficacy and the maximal tolerated dose of cisplatin used in hyperthermic isolated limb perfusion. The median follow-up was 29 months (range 3-54 months). The local recurrence rate was 12% in Stage I, 33% in Stage II and 30% in Stage III patients. The maximal tolerated dose of cisplatin in hyperthermic isolated limb perfusion was 3.2 mg/kg for forequarter perfusions and 6 mg/kg for hindquarter perfusions based on lean body weight. At these dosages, there is an 8% major complication rate and only one patient experienced long-term sequelae. Hyperthermic isolated limb perfusion using cisplatin in the dosages of 3-6 mg/kg lean body weight is associated with low morbidity and appears to have efficacy comparable to L-phenylalanine mustard for the control of locally recurrent malignant melanoma.

DBP, a liver-enriched transcriptional activator, is expressed late in ontogeny and its tissue specificity is determined posttranscriptionally

The full-length cDNA for a transcriptional activator, DBP, that binds to the D site of the albumin promoter has been cloned. DBP belongs to a family of related transcription factors including Fos, Jun, CREB, and C/EBP, which share a conserved basic domain. However, unlike most other members of this family, DBP does not contain a "leucine zipper" structure. Among several rat tissues tested, significant levels of its protein are only observed in liver; yet, with the exception of testis, DBP mRNA is present in all of the examined tissues. DBP as well as its mRNA accumulate to significant levels only in adult animals. During chemically induced liver regeneration, DBP expression is rapidly down-regulated, suggesting that DBP may be involved in the proliferation control of hepatocytes. This cell growth-dependent expression of DBP, in contrast to its tissue specificity, appears to be controlled at the level of mRNA accumulation.

Differential in vitro transcription from the promoter of a rat alpha 2u globulin gene in liver and spleen nuclear extracts

When used in an in vitro transcription assay, the promoter of a cloned alpha 2u globulin gene is much more active in liver than in spleen nuclear extracts. Promoter deletion experiments suggest that both positive and negative regulatory mechanisms may be involved in the differential in vitro transcription from the alpha 2u globulin promoter in these two nuclear extracts. Interestingly, removal of promoter elements upstream from position -74 results in a significant increase of in vitro transcription in spleen but not in liver nuclear extracts, and thus reduces the difference in transcription observed with longer alpha 2u promoters in these two extracts. Deletion of additional nucleotides to position -43 strongly reduces the in vitro transcription efficiency of the promoter in extracts from both tissues. None of the examined promoters containing between 3000 and 22 nucleotides of 5' flanking regions are differentially transcribed in liver nuclear extracts from either male or female rats. Thus, in contrast to cell-type specificity, sex-specificity could not be observed in our in vitro transcription experiments. DNase I protection experiments with crude nuclear extracts and partially or highly purified nuclear proteins suggests the presence of six recognition sites for DNA-binding factors between the TATA element and position -210. Some of these factors could be identified as proteins that also bind to elements within the albumin gene promoter.

The polyomavirus enhancer comprises multiple functional elements

The polyomavirus enhancer occupies 244 base pairs within noncoding sequences between the early and late transcription units. To define more precisely the DNA sequences that make up the enhancer, we cloned it together with the viral early promoter upstream of a reporter gene, isolated mutants bearing deletions introduced in vitro in the enhancer, and measured the capacity of the various mutant genomes to express the cat gene after transient transfection into mouse 3T3 cells. Analysis of a large number of deletion mutants revealed that the enhancer is between 102 and 172 base pairs long and can be divided into at least three functional elements. Relative to the entire enhancer, individual elements possessed little or no enhancer activity. However, pairs of elements enhanced transcription to levels much higher than the sum of individual elements approximating the activity of the complete enhancer. These findings support the view that the polyomavirus enhancer is composed of multiple sequence elements that function combinatorily and imply that a measure of cooperation exists in the interaction between cellular protein factors bound to their cognate sites in the enhancer and the transcriptional machinery of the cell.

Lactational response to soybean meal, heated soybean meal, and extruded soybeans with ruminally protected methionine

Seventy-three high producing Holstein cows were arranged in a 3 X 2 factorial to evaluate three protein supplements (soybean meal, heat-treated soybean meal, and extruded blend of soybeans and soybean meal) without or with 15 g/head/d of ruminally protected DL-methionine during wk 4 through 16 postpartum. Total mixed diets contained (DM basis) 30% corn silage, 15% alfalfa hay, and 55% of the respective concentrate mix. Milk production was higher when cows were fed either heated soybean product instead of soybean meal. Methionine supplementation increased production when fed with soybean meal (32.2 and 33.8 kg/d) but not when fed with heat-treated soybean meal (34.5 and 33.0 kg/d) or extruded soybeans (36.2 and 34.4 kg/d). Milk fat percentages were lower with extruded soybeans (3.01, 2.93, and 2.66) and were similar without (2.83) or with (2.90) supplemental methionine. Milk protein percentages were highest when fed soybean meal, lowest with extruded soybeans (3.02, 2.92, and 2.87), and higher with supplemental methionine (2.91 and 2.96). Dry matter intake was higher when fed supplemental methionine (20.0 and 21.3 kg/d). Production of milk in early lactation high producing dairy cows was increased by supplementing a soybean meal diet with ruminally protected methionine or by replacing the soybean meal with heat-treated soybean meal, soybeans, or a mixture of the two.

Protected methionine supplementation with extruded blend of soybeans and soybean meal for dairy cows

Methionine may be the first amino acid limiting milk production in early lactation cows. To evaluate this further, 23 high producing Holstein cows (9 multiparous and 14 primiparous) were fed an extruded blend of soybeans and soybean meal (40:60) without or with 15 g of added DL-methionine as 50 g of ruminally protected methionine product during wk 4 to 16 postpartum. Cows were fed a 15.8% crude protein total mixed ration consisting of 30% (dry basis) corn silage, 15% alfalfa hay, and 55% concentrate mix. Covariant-adjusted yields of milk (35.3 and 33.9 kg/d) and solids-corrected milk (29.3 and 28.2 kg/d) were lower for cows fed ruminally protected methionine, whereas yields of 4% fat-corrected milk (28.2 and 27.4 kg/d) were similar. Percentages of fat (2.68 and 2.69) and solids-not-fat (8.82 and 8.83) were similar, and percentages of protein (2.86 and 2.90) were higher from cows fed supplemental methionine. Dry matter intakes (20.5 and 21.6 kg/d) were higher for cows fed ruminally protected methionine. Methionine concentrations in arterial and venous serum were elevated slightly by feeding supplemental methionine. Although methionine was still the first-limiting amino acid as calculated by two different methods, supplementation of this diet with ruminally protected methionine did not increase production of early lactation cows.

Location of sequences in polyomavirus DNA that are required for early gene expression in vivo and in vitro

To define the DNA sequences required for the expression of the polyomavirus early transcription unit, we cloned part of the viral genome in a plasmid vector, isolated mutants bearing lesions introduced in vitro within DNA sequences upstream of the transcriptional start site, and measured the capacity of these various mutant genomes to transform cells and to function as templates for transcription in vitro by comparison with wild-type DNA. One set of mutants bore 5' unidirectional deletions beginning at position -810 and extending downstream to position +4. Another set of mutants bore 3' undirectional deletions starting at position +4 and progressing upstream to position -311. The last set of mutants bore internal deletions between positions -810 and +4. Analyses of the properties of these mutant DNAs led us to conclude that the region between positions -403 and -311 includes an enhancer of gene expression. Deletion of this area from the viral genome reduced gene expression in vivo to 1 to 2% of wild-type levels, as measured by transformation assays. Moreover, this region increased the frequency of transformation of thymidine kinase-negative Rat-2 cells by the herpes simplex virus thymidine kinase (tk) gene from 5- to 20-fold. This occurred only if the polyomavirus sequences were covalently linked to the tk gene and then occurred independently of their orientation or position relative to the tk gene. A second transcriptional element is located downstream of the enhancer between positions -311 and -213. This element together with the enhancer was sufficient to bring about transformation of Rat-1 cells at nearly wild-type frequencies, and together these elements constitute the minimal sequences required for gene expression in vivo. The sequences making up the second element may be functionally duplicated downstream of position -165 (between positions -165 and -60). This was revealed by the characterization of mutant genomes with deletions between positions -349 and -60. The role of these redundant elements is not known; however, they may be analogous to the 21-base-pair repeats of simian virus 40. Finally, sequences between positions -57 and -1 were required for accurate and efficient transcription in vitro. However, this DNA stretch, which includes the TATA box and major transcriptional start sites, was not absolutely required for gene expression in vivo. We conclude that the polyomavirus promoter comprises multiple functional elements which are distributed across a DNA stretch of about 400 base pairs.

Polyomavirus large T antigen binds independently to multiple, unique regions on the viral genome

To map the polyomavirus large T antigen binding sites on the viral genome we employed a quantitative immunoassay. Defined, radiolabeled fragments of the viral genome were reacted with crude nuclear extracts prepared from lytically infected mouse 3T6 cells, and the fragments bound by large T antigen were immunoprecipitated with anti-T serum and Formalin-fixed Staphylococcus aureus. The immunoprecipitated DNA was then analyzed by gel electrophoresis and autoradiography. By the use of a variety of restriction endonuclease-generated fragments of wild-type and mutant viral DNAs, the region of high-affinity binding was localized to a 153-base-pair stretch between nucleotides 5292 and 152. At least two independent binding sites lie within this region, one upstream and the other downstream of the Bg/I site at nucleotide 87. One of the binding sites is located within sequences required in cis for DNA replication; the other overlaps the TATA box and cap sites of the early transcription unit. The two sites share a common sequence, A/TGAGGC-N4/5-A/TGAGGC, which may serve as the recognition sequence for large T antigen.

Polyomavirus origin for DNA replication comprises multiple genetic elements

To define the minimal cis-acting sequences required for polyomavirus DNA replication (ori), we constructed a number of polyomavirus-plasmid recombinants and measured their replicative capacity after transfection of a permissive mouse cell line capable of providing polyomavirus large T antigen in trans (MOP cells). Recombinant plasmids containing a 251-base-pair fragment of noncoding viral DNA replicate efficiently in MOP cells. Mutational analyses of these viral sequences revealed that they can be physically separated into two genetic elements. One of these elements, termed the core, contains an adenine-thymine-rich area, a 32-base-pair guanine-cytosine-rich palindrome, and a large T antigen binding site, and likely includes the site from which bidirectional DNA replication initiates. The other, termed beta, is located adjacent to the core near the late region and is devoid of outstanding sequence features. Surprisingly, another sequence element named alpha, located adjacent to beta but outside the borders of the 251-base-pair fragment, can functionally substitute for beta. This sequence too contains no readily recognized sequence features and possesses no obvious homology to the beta element. The three elements together occupy a contiguous noncoding stretch of DNA no more than 345 base pairs in length in the order alpha, beta, and core. These results indicate that the polyomavirus origin for DNA replication comprises multiple genetic elements.