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At least 451 records · Page 25Linked to original sources
PubMed1985

Analysis of an evolutionarily conserved antigenic site on mammalian cytochrome c using synthetic peptides.

Two synthetic peptides inclusive of the NH2-terminal N-acetyl-Gly-Asp-Val-Glu tetrapeptide of mammalian cytochrome c (cyt c) were used in this study to address the question of whether mammals can respond immunologically to an evolutionarily conserved region of a protein. These peptides were assessed for their capacity (i) to act as immunogens for the production of anti-self cyt c antisera and (ii) to bind rabbit anti-rodent cyt c antibody. The findings from these studies indicate the existence of an immunogenic determinant in an evolutionarily conserved region of cyt c that contains residues 1-4. This determinant can induce anti-self cyt c antibodies whether presented as a peptide on a carrier protein or in the context of the intact molecule as polymerized mammalian cyt c.

Amino Acid Sequence↗
PubMed1987

Genetic analysis of tumorigenesis: a conserved region in the human and Chinese hamster genomes contains genetically identified tumor-suppressor genes.

Regional chromosome homologies were found in a comparison of human 11p with Chinese hamster 3p. By use of probes that recognize six genes of human 11p (INS, CAT, HBBC, CALC, PTH, and HRAS), the corresponding genes were localized by in situ hybridization on Chinese hamster chromosome 3. INS and CAT were located close to the centromere on 3p, whereas HBBC, CALC, and PTH were at 3q3-4 and HRAS at 3q4. Extensive prior data from chromosome studies of tumorigenic and tumor-derived Chinese hamster cells have suggested the presence of a tumor-suppressor gene on 3p. Two tumor-suppressor genes have been described on human 11p, one linked to CAT and one to INS. The present study raises the possibility that the Chinese hamster suppressor may be closely linked to INS or CAT.

Animals↗
PubMed1997

Functional analysis of the evolutionary conserved arginine 182 residue in human glutathione S-transferase P1-1.

The mutational replacement of Arg182 with threonine markedly decreased the specific activities for GSH-conjugation reaction. The Kcat of R182T for GSH-[1-chloro-2,4-dinitrobenzene] conjugation reaction was about 100-fold smaller than that of the wild type. On the other hand, the affinity for GSH of R182T was not significantly affected. The pKa of the thiol group of GSH bound in R182T was approximately 0.9 pK units higher than those in the wild type, but the Kcat/Km1-chloro-2,4-dinitrobenzene values at high pH were not so much lower than those of the wild type. The thermostability of R182T was significantly lower than that of the wild type. Therefore, Arg182 seems to be important for the construction of the active enzyme structure.

Amino Acid Sequence↗
PubMed1996

Comparative analysis of five highly conserved target sites within the HIV-1 RNA for their susceptibility to hammerhead ribozyme-mediated cleavage in vitro and in vivo.

Moloney murine leukemia virus (MMLV)-derived pUCMoTiN-based retroviral vectors were engineered to allow constitutive and Tat (trans-activator of transcription)-inducible expression of five hammerhead ribozymes targeted against highly conserved sequences within the group antigen (Gag), protease (Pro), reverse transcriptase (RT), tat, and envelope (Env) coding regions of human immunodeficiency virus type-1 (HIV-1) RNA. Amphotropic retroviral vector particles were used to infect a human CD4+ lymphocyte-derived MT4 cell line. The pool of stable MT4 transductants expressing these ribozymes were each tested for their susceptibility to HIV-1 infection. RzTat conferred no protection to MT4 cells. RZGag and RzRT completely inhibited virus multiplication for 6 days. RzPro and RzEnv conferred the best protection, as they completely inhibited virus production for 12 and 15 days, respectively. No correlation was found between the degree of HIV-1 resistance conferred and the ability of these ribozymes to cleave their target RNA in vitro. From RzPro-expressing HIV-1-infected cells following virus escape, RzPro and target RNA sequences were amplified and checked for cleavage in vitro. The ribozyme expressed in these cells was shown to cleave the corresponding target RNA. Thus, a mutation in the ribozyme or target RNA does not seem to be the mechanism underlying virus escape.

Base Sequence↗
PubMed1999

Structure-function analysis of an evolutionary conserved protein, DAP3, which mediates TNF-alpha- and Fas-induced cell death.

A novel approach to the isolation of positive mediators of programmed cell death, based on random inactivation of genes by expression of anti sense RNAs, was employed to identify mediators of interferon-gamma-induced apoptosis. One of the several genes identified is DAP3, which codes for a 46 kDa protein with a potential nucleotide-binding motif. Structure-function studies of the protein indicate that the intact full-length protein is required for its ability to induce apoptosis when overexpressed. The N-terminal 230 amino acids, on the other hand, act in a dominant-negative fashion. Both of these functions are dependent on the integrity of the nucleotide binding motif. Expression of anti-sense DAP3 RNA and of the dominant interfering form of DAP3 both protected cells from apoptosis induced by activation of Fas and tumor necrosis factor alpha (TNF-alpha) receptors. Thus, DAP3 is implicated as a positive mediator of these death-inducing stimuli. It functions downstream of the receptor signaling complex and its death promoting effects depend on caspase activity. In the nematode Caenorhabditis elegans, a potential homolog of DAP3 showing 35% identity and 64% similarity to the human protein was isolated. Overexpression of the nematode DAP3 cDNA in mammalian cells induced cell death, indicating that the protein is conserved at the functional level as well as the structural level.

Amino Acid Sequence↗
PubMed2005

Outcome analysis of breast-conservation surgery and immediate latissimus dorsi flap reconstruction in patients with T1 to T2 breast cancer.

BACKGROUND: The latissimus dorsi myocutaneous flap is frequently used for total breast reconstruction; however, few reports have been available regarding clinical outcome following conservative breast surgery. The aim of this study was to perform a retrospective review on 48 patients undergoing immediate latissimus dorsi myocutaneous flap surgery following conservative breast surgery between 1999 and 2004. METHODS: Information on age, body mass index, smoking history, comorbid medical conditions, and oncologic status was collected. Reconstructed breast and donor-site complications were evaluated. RESULTS: Mean follow-up was 16 months. In 56.2 percent of patients, tumors measured 2 cm or less (T1) and in 47.9 percent were located in the upper outer quadrants. Flap complications occurred in seven and donor-site complications occurred in 12 of 48 patients. Dorsal seroma (20.8 percent), dorsal dehiscence (6.2 percent), and partial flap loss (6.2 percent) were the most common complications. Surgical intervention with skin suture was necessary in two cases of dorsal wound dehiscence. Partial flap losses were limited and were treated by a conservative approach. A significant association (p = 0.035) was detected between dorsal seroma and obesity (body mass index or = 30 kg/m) and was associated with a 5.2-fold increase in the odds of developing this complication. No significant association between complications and age, smoking history, hypertension, diabetes, axillary lymph node dissection, or chemotherapy was found. CONCLUSIONS: On the basis of our observations, the latissimus dorsi myocutaneous flap is a consistent technique for reconstruction following conservative breast surgery. Donor-site complications are more often observed in those who are obese; they are higher risk patients.

Adult↗
PubMed2005

Mutational analysis of the avian pneumovirus conserved transcriptional gene start sequence identifying critical residues.

Seven of the eight genes in the avian pneumovirus (APV) genome contain a conserved 9 nt transcriptional start sequence with the virus large (L) polymerase gene differing from the consensus at three positions. The sequence requirements of the APV transcriptional gene start sequence were investigated by generating a series of mutations in which each of the nine conserved bases was mutated to each of the other three possible nucleotides in a minigenome containing two reporter genes. The effect of each mutation was assessed by measuring the relative levels of expression from the altered and unaltered gene start sequences. Mutations at positions 2, 7 and 9 significantly reduced transcription levels while alterations to position 5 had little effect. The L gene start sequence directed transcription at levels approximately 50 % below that of the consensus gene start sequence. These data suggest that there are common features in pneumovirus transcriptional control sequences.

Chloramphenicol O-Acetyltransferase↗
PubMed2002

Identification, analysis, and utilization of conserved ortholog set markers for comparative genomics in higher plants.

We have screened a large tomato EST database against the Arabidopsis genomic sequence and report here the identification of a set of 1025 genes (referred to as a conserved ortholog set, or COS markers) that are single or low copy in both genomes (as determined by computational screens and DNA gel blot hybridization) and that have remained relatively stable in sequence since the early radiation of dicotyledonous plants. These genes were annotated, and a large portion could be assigned to putative functional categories associated with basic metabolic processes, such as energy-generating processes and the biosynthesis and degradation of cellular building blocks. We further demonstrate, through computational screens (e.g., against a Medicago truncatula database) and direct hybridization on genomic DNA of diverse plant species, that these COS markers also are conserved in the genomes of other plant families. Finally, we show that this gene set can be used for comparative mapping studies between highly divergent genomes such as those of tomato and Arabidopsis. This set of COS markers, identified computationally and experimentally, may further studies on comparative genomes and phylogenetics and elucidate the nature of genes conserved throughout plant evolution.

Amino Acid Sequence↗
PubMed2005

Cloning, purification, crystallization and preliminary X-ray analysis of XC229, a conserved hypothetical protein from Xanthomonas campestris.

Xanthomonas campestris pv. campestris is a Gram-negative yellow-pigmented pathogenic bacterium that causes black rot, one of the major worldwide diseases of cruciferous crops. Its genome contains approximately 4500 genes, roughly one third of which have no known structure and/or function. However, some of these unknown genes are highly conserved among several different bacterial genuses. XC229 is one such protein containing 134 amino acids. It was overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystal diffracted to a resolution of at least 1.80 A. It is cubic and belongs to space group I2(x)3, with unit-cell parameters a = b = c = 106.8 A. It contains one or two molecules per asymmetric unit.

Bacterial Proteins↗
PubMed1995

Site-directed mutagenesis of varicella-zoster virus thymidylate synthase. Analysis of two highly conserved regions of the enzyme.

We have constructed a series of mutants to study the role of two structurally and functionally important regions of thymidylate synthase (TS) from varicella-zoster virus (VZV). The first centres on a conserved glycine residue in the beta-kink of beta-strand i, a partially buried region of the protein that is important for dimer interactions and the formation of the active site. We show that the glycine residue located in beta-strand i is not essential for enzyme activity and that beta-strand i can readily accommodate several amino acid substitutions and also an insertion. A covariant residue that accommodates these changes was also identified. The second region of interest was the solvent-exposed and highly mobile C-terminal residue which is an essential component of the active site in TS from Lactobacillus casei and Escherichia coli. We demonstrate that removal of the C-terminal residue from VZV TS does not completely inactivate the enzyme, implying that there are significant structural differences between the virus and bacterial enzymes. By combining site-directed mutagenesis and molecular modelling we have identified these differences and propose a model that explains the contrasting activities.

Base Sequence↗
PubMed2004

Mutational analysis of the highly conserved ERY motif of the thromboxane A2 receptor: alternative role in G protein-coupled receptor signaling.

The presence of highly conserved amino acid stretches in G protein-coupled receptors (GPCRs) usually predicts an important role in receptor function. Considerable attention has therefore been focused on the involvement of the highly conserved Glu/Asp-Arg-Tyr (E/DRY) motif at the cytoplasmic end of transmembrane domain 3 in the regulation of GPCR conformational states and/or the mediation of G protein activation. In the present study, we investigated the role of Glu129 and Arg130 in the ERY of thromboxane A2 receptor alpha (TPalpha) in transfected human embryonic kidney 293 cells. We show that no conservative or nonconservative substitutions of Glu129 and Arg130 generated a constitutively active TPalpha mutant, but a nonconservative mutation of Arg130 (R130V) yielded a mutant receptor with significantly impaired 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prosta-5Z,13E-dien-1-oic acid (U46619)-induced accumulation of inositol phosphates (IPs). This loss-of-function phenotype seems to be caused by the uncoupling of the TPalpha receptor from Gq, as demonstrated by the loss of high-affinity agonist binding, and not by receptor internalization, as shown by localization studies with the R130V-green fluorescent protein fusion protein. It is interesting to note that U46619-induced activation of the nonconservative E129V mutant stimulated the production of IPs with a approximately 10-fold lower EC50 and a approximately 2-fold higher Emax than in the wild-type receptor. Collectively, these data demonstrate that, unlike other GPCRs, mutations of Glu129 do not induce constitutive activity, whereas Arg130 is involved in G protein coupling or recognition, and they suggest the existence within class A GPCRs of at least two different subclasses that make different uses of the highly conserved E/DRY motif.

Amino Acid Motifs↗
PubMed2002

Functional analysis of the highly conserved exon IV of XIST RNA.

X inactivation is effected by a large CIS-acting RNA molecule termed the X inactive specific transcript (XIST). Exon IV of XIST RNA is highly conserved at the primary sequence level and is predicted to form a stable stem-loop structure. These features suggest that it is important for XIST RNA function. We have used homologous recombination to delete exon IV of the mouse XIST gene. Surprisingly we found no detectable effects on X inactivation. Heterozygous female animals show normal random X inactivation and transcripts from the mutant allele were seen to localise IN CIS over the length of the inactive X chromosome. There was however a reduced steady state level of mutant relative to wild type XIST RNA. This effect was not attributable to decreased stability, suggesting that the deletion affects transcription or processing of XIST RNA.

Animals↗
PubMed2004

The spatial extent of contaminants and the landscape scale: an analysis of the wildlife, conservation biology, and population modeling literature.

Many contaminant releases to the terrestrial environment are of small areal extent. Thus, rather than evaluating the ecological impact on species in the immediate vicinity of the release, it may be more ecologically meaningful to determine if population impacts occur at the landscape level. In order to do this, the cumulative impact of all releases in the landscape under consideration must be evaluated. If the release sites are viewed as localized areas that are no longer available for use by ecological receptors (i.e., no longer part of the habitat), this can be thought of as a form of habitat fragmentation. Habitat fragmentation is typically viewed as the loss of large areas of habitat within a landscape, leaving small isolated patches of intact habitat within a hostile matrix. Small-scale contaminant releases, on the other hand, result in small uninhabitable areas within a primarily intact habitat. With this consideration in mind, we analyzed the wildlife and conservation biology literature to determine if information on habitat size requirements such as home-range or critical patch size could inform us about the potential for impact at the landscape level from release sites based on the size of the release alone. We determined that evaluating the impact of release size had to be conducted within a contextual basis (considering the existing state of the landscape). Therefore, we also reviewed the population modeling literature to determine if models could be developed to further evaluate the impact of the spatial extent of chemical releases on the landscape. We identified individual-based models linked to geographic information systems to have the greatest potential in investigating the role of release size with respect to population impacts at the landscape level.

Conservation of Natural Resources↗
PubMed1998

Computer sequence analysis of human highly conserved zinc finger modules.

We defined a sub-family of zinc finger proteins by computer analyses and comparisons of five new finger domains against protein databases. This subclass of the cysteine-cysteine/histidine-histidine motif shows additional well conserved amino acid patterns and belongs to the human kox and gli-Kruppel gene family, sharing also the same stretches of regulatory zinc finger-containing proteins of mouse and Xenopus. We particularly describe ZF6 cDNA which contains the most interesting sequence, encoding a putative multi-domain regulatory protein.

Amino Acid Sequence↗
PubMedDate not supplied

[Comparative radiographic analysis of surgical and conservative treatment of unstable injuries of the thoracic and lumbar spine].

INTRODUCTION: Treatment of fractures and dislocations of the thoracolumbar spine is aimed at achieving a stable and painless spine. Concerning mode of treatment therapists are divided into two groups--those for conservative approach and those who advocate operative stabilization of spinal column. The objective of this paper was to compare radiological findings of both modes of treatment on the basis of our clinical material. MATERIALS AND METHODS: The examination included radiographs of 96 patients with radiolographic signs of unstable spine, treated at Clinic of Orthopaedic Surgery and Traumatology of the Institute of Surgery of the Clinical Center in Novi Sad from 1984 to 1998. Among 48 operated patients (average age of 40.7), there were more females--25, and among nonoperated, there were more males--33. The average age of conservatively treated patients was 52. Dynamic radiographs evaluated the angle of local kyphosis on the spot of injury (Cobb's angle), reduction of dimensions of the body of injured vertebra and sagittal movement of the body on affected level. Measured values were corrected by values of sagittal index. RESULTS: Initially the average angle of local kyphosis among operated was 26.9, among conservatively treated it was 19.7. Control values for operated were 14.7 and for conservatively treated 25.6. Initially, a wedge-shaped deformity larger than half of the front part of the injured vertebra body had 42 nonoperated and 32 operated patients. Initially, the average sagittal movement of the injured vertebra body among operated patients was 6.97 mm, and at control 1.34 mm. Among nonoperated, the average movement of the body was 1.71 mm initially and 3.23 mm at control. DISCUSSION: Similar results of angular deformity were found by other examiners. Their results are also in favor of operative treatment of unstable injuries of Th-L spine. The number of those proclaiming good results of conservative treatment of injures of thoracolumbar spine in patients with initially high values of angular deformity is much less. Willen, Mumford, Andreycik and others using wedge-shaped deformity and sagittal movement of the body as parameters in their studies had similar results as those in this study, and they conclude that the stability of segment is much higher among operated patients and that operative treatment finally ends in better radiological results. CONCLUSION: Radiological results of operative treatment of unstable injuries of thoracolumbar and lumbar spine are better than those of conservative treatment. In order to obtain a stable spine, which is the aim of treatment of unstable spine injuries, operative stabilization is necessary.

Adult↗
PubMedDate not supplied

[Surgical treatment of hepatic hydatidosis. Analysis of results of conservative and radical surgery in our experience].

The authors review a series of 194 cases of hepatic hydatidosis submitted to surgery over the period from July 1973 to December 2001, comparing the results of conservative and radical operatins. In this period we performed 164 conservative operations (140 indirect marsupialisations, 5 delaminations with capitonnage of the residual cavity and 19 partial pericystectomies), 26 total pericystectomies and 4 liver resections. The main outcome measures analysed were postoperative hospital stay, mortality, morbidity and recurrence rates. The median postoperative hospital stay was 17.5 days for conservative operations and 12.5 days for radical surgical procedures. No deaths occurred in either group. The morbidity was 26.8% after conservative treatment (34 biliary fistulas, 3 cases of jaundice, 5 residual cavity infections and 2 subphrenic abscesses) and 13.3% after total pericystectomy and liver resection (3 wound infections and 1 pleural effusion). Recurrences occurred only in the group treated by marsupialisation (12/140 = 8.5%) and were managed by total pericystectomy in 5 cases and by a second drainage procedure in 7. The surgical procedure for the treatment of hepatic hydatidosis should be tailored to the needs of each patient, depending on the size, location and complications of the cyst and high surgical risk should be avoided in view of the benign nature of the disease. No deaths occurred in either of our patient groups, but postoperative hospital stay, morbidity and recurrence rates were better in those undergoing radical treatment.

Adolescent↗