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PubMed1998

Logic and reliability of evaluations of competence to stand trial.

Because the trier of fact determines the weight to be assigned to an examiner's opinion by assessing the strength and persuasiveness of his or her analysis of the data, it is essential that forensic reports communicate the examiner's reasoning process. This study analyzes community examiners' reports on competence to stand trial (CST), emphasizing the nature of examiners' (1) expressed conceptualizations of CST and (2) reasoning establishing a nexus between CST impairments and symptoms of psychopathology. Expert raters coded 100 randomly selected CST reports with respect to a variety of issues, including the examiners' description of the defendant's psycholegal deficits, provision of specific reasoning to link these deficits to psychopathology, and agreement with a paired examiner's global and specific opinions about the defendant's impairments. CST reports were found to (1) reflect basic operationalizations of competence that fail to incorporate legally relevant facets such as a defendant's decisional capacities and (2) adequately document clinical findings, but fail to describe the reasoning underlying psycholegal conclusions. Examiners demonstrated moderately high levels of agreement on defendant's global CST, but expressed radically divergent bases for this opinion. These findings are discussed in light of legal, ethical, and professional standards of practice.

Adult↗
PubMed1999

Pore-forming peptides of Entamoeba dispar. Similarity and divergence to amoebapores in structure, expression and activity.

Amoebapore, a 77-residue peptide with pore-forming activity from the human pathogen Entamoeba histolytica, is implicated in the killing of phagocytosed bacteria and in the cytolytic reaction of the amoeba against host cells. Previously, we structurally and functionally characterized three amoebapore isoforms in E. histolytica but recognized only one homolog in the closely related but non-pathogenic species Entamoeba dispar. Here, we identified two novel amoebapore homologs from E. dispar by molecular cloning. Despite strong resemblance of the primary structures of the homologs, molecular modeling predicts a species-specific variance between the peptide structures. Parallel isolation from trophozoite extracts of the two species revealed a lower amount of pore-forming peptides in E. dispar and substantially higher activity of the major isoform from E. histolytica towards natural membranes than that from E. dispar. Differences in abundance and activity of the lytic polypeptides may have an impact on the pathogenicity of amoebae.

Amino Acid Sequence↗
PubMed2003

AP-2 and HNK-1 define distinct populations of cranial neural crest cells.

OBJECTIVE: To determine if distinct populations of cranial neural crest cells (CNCC) exist by characterization of their divergent gene expression patterns. DESIGN: Identification of unique populations of CNCC was determined by a combination of lineage and immunohistochemical analyses. SETTING: Department of Pathology, Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, PA 19104. RESULTS: We found antibodies of two proteins previously described as identifying all CNCC, label three populations of CNCC at specific time-points. Furthermore, the activating protein 2 (AP-2) expressing CNCC become neural or mesenchymal NCC derivatives whereas the HNK-1 labeled cells do not participate in the mesenchymal lineage. CONCLUSION: These data provide molecular markers for unique CNCC fates and thus will be invaluable in the characterizing of craniofacial anomalies related to defects in NCCS. In addition, our data suggest AP-2 may function in determining the unique mesenchymal fate of CNCCs.

Animals↗
PubMed1988

Group-specific, major histocompatibility complex class I-restricted cytotoxic responses to human immunodeficiency virus 1 (HIV-1) envelope proteins by cloned peripheral blood T cells from an HIV-1-infected individual.

Freshly separated unfractionated peripheral blood mononuclear cells (PBMC) and cloned cell lines from a healthy human immunodeficiency virus 1 (HIV-1)-seropositive individual were examined for cytotoxic responses to HIV proteins expressed by recombinant vaccinia viruses. It was found that freshly isolated PBMC recognize variant envelope proteins of HIV-1 but not a more distantly related envelope protein derived from the simian immunodeficiency virus (SIVmac). Although the effector cells were predominantly CD8+, both MHC-matched and -unmatched target cells were lysed. Cytotoxic T lymphocyte (CTL) clones were found to lyse cells expressing HIV-1 envelope or reverse transcriptase. In contrast to the cytotoxic response detected with PBMC, the cloned CTLs were major histocompatibility complex (MHC) class I restricted. Our finding that a cloned CTL line lysed cells expressing highly divergent HIV envelopes strongly suggested that a conserved epitope was recognized. Identification of these shared epitopes may assist in designing a vaccine for HIV-1 that could stimulate MHC-restricted cytotoxic responses.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Cross-induction of glc and ace operons of Escherichia coli attributable to pathway intersection. Characterization of the glc promoter.

The metabolic pathways specified by the glc and ace operons in Escherichia coli yield glyoxylate as a common intermediate, which is acted on by two malate synthase isoenzymes: one encoded by glcB and the other by aceB. Null mutations in either gene exhibit no phenotype, because of cross-induction of the ace operon by glycolate and the glc operon by acetate. In this study, the regulation of the glc operon, comprising the structural genes glcDEFGB, was analyzed at the molecular level. This operon, activated by growth on glycolate, is transcribed as a single message and is under the positive control of GlcC encoded by a divergent gene. Expression of the glc operon is strongly dependent on the integration host factor (IHF) and is repressed by the global respiratory regulator ArcA-P. In vitro gel-shift experiments demonstrated direct binding of the promoter DNA to IHF and ArcA-P. Mutant analysis indicated that cross-induction of the glc operon by acetate is mediated by the GlcC protein that recognizes the compound as an alternative effector. The similar pattern of regulation of the Glc and Ace systems by IHF and ArcA-P ensures their effective cross-induction.

Acetic Acid↗
PubMed2001

Characterization of a novel isoform of caspase-9 that inhibits apoptosis.

We have identified a novel isoform of rat caspase-9 in which the C terminus of full-length caspase-9 is replaced with an alternative peptide sequence. Casp-9-CTD (where CTD is carboxyl-terminal divergent) is expressed in multiple tissues, with the relative highest expression observed in ovary and heart. Casp-9-CTD was found primarily in the cytoplasm and was not detected in the nucleus. Structural predictions suggest that in contrast to full-length caspase-9, casp-9-CTD will not be processed. Our model is supported by reduced protease activity of casp-9-CTD preparations in vitro and by the lack of detectable processing of casp-9-CTD proenzyme or the induction of cell death following transfection into cells. Both neuronal and non-neuronal cell types transfected with casp-9-CTD were resistant to death evoked by trophic factor deprivation or DNA damage. In addition, cytosolic lysates prepared from cells permanently expressing exogenous casp-9-CTD were resistant to caspase induction by cytochrome c in reconstitution assays. Taken together, our observations indicate that casp-9-CTD acts as a dominant-negative variant. Its expression in various tissues indicates a physiological role in regulating cell death.

Amino Acid Sequence↗
PubMed2005

Matters of scale: positive allometry and the evolution of male dimorphisms.

The developmental independence of alternative phenotypes is key to evolutionary theories of phenotypic plasticity and the origins of diversity. Male dimorphisms associated with alternative reproductive tactics are widely cited examples of such facultative expression of divergent fitness optima. Current models for the evolution of male dimorphisms invoke a size-dependent threshold at which the phenotype is reprogrammed. We use predictions derived from allometric modeling to test for the existence of reprogramming thresholds in two species of beetle, Onthophagus taurus and Onthophagus binodis, and the European earwig Forficula auricularia. We also compare the allometry of a number of morphological traits to determine whether minor males suppress their secondary sexual traits. The intercept of the horn allometry was suppressed, but there was no evidence of reprogramming of horn growth in either beetle species. There was reprogramming in the earwig. In the beetles, the horn length in all males can be explained largely in terms of exponential horn growth following an extraordinarily steep power function. The asymptote in O. taurus can be explained by exponential growth meeting the constraint of resource exhaustion. These findings question the currently held view that beetle horn dimorphisms showcase the importance of developmental independence in the evolution of diversity.

Animals↗
PubMed1995

Rat growth hormone receptor/growth hormone-binding protein mRNAs with divergent 5'-untranslated regions are expressed in a tissue-specific manner.

In the rat, the growth hormone receptor (GH-R) gene generates two transcripts, one encoding the transmembrane GH-R, and a shorter one encoding the GH-binding protein (GH-BP). These transcripts exhibit a high degree of heterogeneity in their 5'-untranslated regions (5'-UTRs). Some of the exons encoding these 5'-UTR variants may be flanked by distinct promoter regions whose activity would result in the tissue-specific expression of the GH-R gene. To assess this possibility, we used single-sided polymerase chain reaction (PCR) amplification to characterize 5'-UTR variants in rat GH-R cDNAs, and by using 5'-UTR-specific probes, we determined their pattern of expression in several tissues. Besides two previously described variants (V1 and V2), three new 5'-UTR variants were identified, extending 56 nucleotides (V3), 135 nucleotides (V4), and 209 nucleotides (V5) upstream of the ATG translation initiation codon. The expression of GH-R and GH-BP transcripts was clearly tissue specific. In the liver, GH-BP mRNA was the predominant transcript, whereas in other tissues, there was equivalent expression of both transcripts or predominant expression of GH-R mRNA. With respect to the tissue distribution of the 5'-UTR variants in particular, variants V1 and V5 exhibited a pattern of expression closely resembling that seen with an exon 2 probe, with the overall expression of variant V1 being much higher than that of variant V5. The V2 species was exclusively expressed in liver. Variant V3 was expressed at low levels in liver, muscle, heart, and kidney; in muscle and heart, it was preferentially associated with GH-BP transcripts. Variant V4, although present in liver, was more abundant in extrahepatic tissues and predominantly found in GH-R mRNA transcripts. Southern blot analyses were consistent with exon 2 and the exons encoding the V1 and V2 sequences being in proximity, with the other 5'-UTR sequences being encoded by exons located further upstream of exon 2. These findings support the concept that different 5'-UTR variants are the result of the different promoters acting in a tissue-specific manner. The association of specific 5'-UTR variants with either GH-R or GH-BP transcripts raises the possibility that the alternative splicing process that generates GH-BP mRNA in the rat might be controlled by the 5'-flanking region regulating the expression of specific leader exons.

Animals↗
PubMed2001

The invertebrate odorant-binding protein LUSH is required for normal olfactory behavior in Drosophila.

The invertebrate odorant-binding proteins consist of a large family of low-molecular-weight, highly divergent proteins expressed exclusively in the chemosensory sensilla of insects. Each member of this family studied to date is secreted into the sensillum lymph of a small subset of sensilla by non-neuronal support cells. These expression patterns suggests an odor-specific function for these proteins as opposed to a general role in sensillum biology. Consistent with this notion, mutants defective for LUSH, a Drosophila member of this family, have odor-specific defects in olfactory behavior. The Drosophila genome contains at least 32 members of this gene family, rivaling the number of odorant receptors in this species. The relationship between these two protein families and how they act to determine odor specificity of olfactory neurons will be the topic of future studies.

Animals↗
PubMed1999

The GATA factor AreA is essential for chromatin remodelling in a eukaryotic bidirectional promoter.

The linked niiA and niaD genes of Aspergillus nidulans are transcribed divergently. The expression of these genes is subject to a dual control system. They are induced by nitrate and repressed by ammonium. AreA mediates derepression in the absence of ammonium and NirA supposedly mediates nitrate induction. Out of 10 GATA sites, a central cluster (sites 5-8) is responsible for approximately 80% of the transcriptional activity of the promoter on both genes. We show occupancy in vivo of site 5 by the AreA protein, even under conditions of repression. Sites 5-8 are situated in a pre-set nucleosome-free region. Under conditions of expression, a drastic nucleosomal rearrangement takes place and the positioning of at least five nucleosomes flanking the central region is lost. Remodelling is strictly dependent on the presence of an active areA gene product, and independent from the NirA-specific and essential transcription factor. Thus, nucleosome remodelling is independent from the transcriptional activation of the niiA-niaD promoter. The results presented cast doubts on the role of NirA as the unique transducer of the nitrate induction signal. We demonstrate, for the first time in vivo, that a GATA factor is involved directly in chromatin remodelling.

Aspergillus nidulans↗
PubMed1986

Regulation of the put operon in Salmonella typhimurium: characterization of promoter and operator mutations.

The two genes required for proline utilization by S. typhimurium form a divergent operon. Expression of the put operon is induced by proline and subject to catabolite repression. Genetic evidence suggests that putA protein autogenously represses transcription of the putA and putP genes. In order to establish the molecular mechanism of put operon regulation we isolated regulatory mutations in the put control region. These mutants were selected using two phenotypes: the ability to degrade a toxic proline analogue, dehydroproline, due to overexpression of putA enzyme activity, or overexpression of lacZ from put::Mud operon fusions. The effect of each mutation on transcription in both directions was determined by measuring lacZ expression from putA and putP operon fusions. These regulatory mutations were cis-dominant when the putA protein was provided in trans, and they map in a region between the two genes. The phenotypes of the mutants suggest that the put regulatory region has a single operator site where the putA protein binds to repress transcription in both directions, and the putA and putP promoters overlap.

Genes, Bacterial↗
PubMed1992

Microculture-based chemosensitivity testing: a feasibility study comparing freshly explanted human melanoma cells with human melanoma cell lines.

BACKGROUND: The culture of cancer cells has many applications in chemosensitivity testing and new drug development. PURPOSE: Our goal was to adapt simple semiautomated microculture methods for testing the chemosensitivity of melanoma cells freshly recovered from patients' tumors. METHODS: Cells were cultured on a substrate of agarose and exposed continuously to cytotoxic drugs, the effects of which were measured by determining the uptake of [3H]thymidine 4-7 days later. RESULTS: Immunocytochemical staining of cells cultured with 5-bromo-2'-deoxyuridine demonstrated that tumor cells were responsible for the measured thymidine incorporation. The effects of cytotoxic drugs were calculated as logarithmic 50% inhibitory concentrations and expressed as divergences from the mean in a log-mean graph. The inhibitory effects of amsacrine, etoposide, doxorubicin, cisplatin, mitomycin C, and fluorouracil were tested. Tumors differed widely in their sensitivity to these drugs, although sensitivity to the three topoisomerase-II-directed agents was highly correlated. Cells from two non-neoplastic hematopoietic progenitor cell lines (FT and 32D) showed chemosensitivity patterns distinct from those in the melanoma cells, indicating tissue selectivity. Two established melanoma cell lines, MM-96 and FME, were tested under the same conditions and showed sensitivity typical of at least some fresh specimens. CONCLUSIONS: These results support the validity of melanoma cell lines as models of freshly resected melanoma cells. If successfully applied to other tumor types, such semiautomated approaches could find wide application in routine hospital laboratories for the chemosensitivity testing of patients' tumor cells.

Animals↗
PubMed2004

Functional microsatellite polymorphism associated with divergent social structure in vole species.

Forebrain vasopressin/vasotocin systems regulate a diverse set of complex social behaviors in a species-specific manner. Among mammals, vasopressin gene sequences and peptide distributions in the brain are highly conserved across species. In contrast, vasopressin V1a receptors (V1aR) are conserved at the protein level, but not at the level of gene structure or neuroanatomical distribution of the receptor. Here, we examine the functional role of a microsatellite segment in the 5' region of V1aR that differs significantly between monogamous and nonmonogamous vole species with divergent V1aR expression patterns. Using luciferase reporter assays, we demonstrate that this microsatellite plays a significant role in transcriptional regulation in a cell-type-specific manner. These results suggest that significant evolutionary changes in social behavior can occur through variation in regulatory regions of genes already involved in social behavior.

Analysis of Variance↗
PubMed1979

"Pseudosarcoma" of the larynx.

Polypoid epidermoid carcinoma of the larynx with a cellular, often atypical stroma has also been classified as pseudosarcoma, carcinosarcoma, pleomorphic carcinoma, or spindle cell sarcoma. The nature of the spindle-shaped stromal cells has clinical significance, but pathologists do not agree about the origin and potential of these cells. This paper describes two laryngeal tumors, one with an abundant osseous component in which light-microscopic, ultrastructural, and clinical features suggest the origin of these fusiform cells from reactive pluripotential mesenchyme. In a second case, atypical fusiform cells within the stroma show ultrastructural epithelial characteristics. These findings suggest a varied histogenesis for pseudosarcoma of the larynx and may explain divergent theories expressed in the literature.

Carcinoma, Squamous Cell↗
PubMed1982

Unusual pericytic proliferation in a meningotheliomatous meningioma: an ultrastructural study.

Hemangiopericytomas are controversial tumors of the central nervous system and are regarded by many neuropathologists as variants of meningioma. A unique vascular change which may have bearing on this relationship was encountered in a sphenoid wing meningioma in a 93-year-old man. By light and electron microscopy, the tumor showed classical features of a meningotheliomatous meningioma. In addition, however, there was striking proliferation of small dark cells within vessel walls, extending into the parenchyma, and often dominating the picture. Ultrastructurally, the small cells, in contrast to the meningothelial cells, were totally invested by basal laminae, showed extensive pinocytosis, and subplasmalemmal condensations, i.e., pericytic features. The two cell populations, although intimately intermingled, maintained distinct features. This case may represent an expression of divergent mesodermal differentiation of meningeal cells, either as a unique vascular reactive change or alternatively as an early stage in the development of a hemangiopericytic tumor of the meninges.

Aged↗
PubMed1999

Perioperative antibiotic prophylaxis in cataract surgery.

PURPOSE: To review the rationale for various methods of perioperative prophylaxis in elective cataract surgery. METHODS: The surgical and ophthalmologic literature is reviewed to determine accepted principles for the use of perioperative prophylactic agents in clean elective surgical procedures. RESULTS: After an assessment of the nonophthalmic surgical literature, specific principles are applied to the use of antimicrobial agents in perioperative prophylaxis of cataract surgery. Current practice patterns and specific techniques of perioperative prophylaxis are scrutinized. The emerging problem of antimicrobial resistance in the world and specifically in ophthalmology is addressed. Recommendations are offered balancing the needs of the individual patient with the best interests of society as a whole. CONCLUSION: Potent therapeutic agents should be reserved for therapy. A method of perioperative prophylaxis is suggested, with a stratified approach indicated in selected circumstances. A clear consensus is probably not possible with divergent views expressed.

Animals↗
PubMed1992

Regulation of C4 Gene Expression in Developing Amaranth Leaves.

Immunofluorescence microscopy and in situ hybridization were used to examine the expression of genes encoding C4 photosynthetic enzymes during early leaf development in the C4 dicotyledonous grain plant amaranth. During early developmental stages, the chloroplast-encoded large subunit and nuclear-encoded small subunit genes of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCase) were expressed in both bundle sheath and mesophyll cells in a C3-type pattern. The RuBPCase proteins and mRNAs became specifically localized to bundle sheath cells in the characteristic C4-type pattern as the leaves continued to expand and develop. Changes in the localization of the RuBPCase proteins corresponded closely with changes in the localization of their mRNAs, indicating that the cell-specific expression of genes encoding RuBPCase is controlled, at least in part, at the level of transcript accumulation. Genes encoding pyruvate orthophosphate dikinase were expressed specifically in mesophyll cells at all developmental stages examined. Immunolocalization with antibodies raised against phosphoenolpyruvate carboxylase (PEPCase) showed that this enzyme is present only in leaf mesophyll cells, even though RNA sequences with homology to PEPCase gene sequences were present in both bundle sheath and mesophyll cells. These results suggest that the regulation of genes encoding PEPCase in amaranth is complex and could involve the differential expression of divergent PEPCase genes or possibly regulation at the post-transcriptional level.

Journal Article↗
PubMed1996

Bach proteins belong to a novel family of BTB-basic leucine zipper transcription factors that interact with MafK and regulate transcription through the NF-E2 site.

Members of the small Maf family (MafK, MafF, and MafG) are basic region leucine zipper (bZip) proteins that can function as transcriptional activators or repressors. The dimer compositions of their DNA binding forms determine whether the small Maf family proteins activate or repress transcription. Using a yeast two-hybrid screen with a GAL4-MafK fusion protein, we have identified two novel bZip transcription factors, Bach1 and Bach2, as heterodimerization partners of MafK. In addition to a Cap'n'collar-type bZip domain, these Bach proteins possess a BTB domain which is a protein interaction motif; Bach1 and Bach2 show significant similarity to each other in these regions but are otherwise divergent. Whereas expression of Bach1 appears ubiquitous, that of Bach2 is restricted to monocytes and neuronal cells. Bach proteins bind in vitro to NF-E2 binding sites, recognition elements for the hematopoietic transcription factor NF-E2, by forming heterodimers with MafK. Furthermore, a DNA binding complex that contained MafK as well as Bach2 or a protein related closely to Bach2 was found to be present in mouse brain cells. Bach1 and Bach2 function as transcription repressors in transfection assays using fibroblast cells, but they function as a transcriptional activator and repressor, respectively, in cultured erythroid cells. The results suggest that members of the Bach family play important roles in coordinating transcription activation and repression by MafK.

Amino Acid Sequence↗