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D Bader

Publications and source records attributed to D Bader.

At least 55 records · Page 3Linked to original sources
PubMed1996

Identification of a novel cardiac-specific transcript critical for cardiac myocyte differentiation.

A novel cDNA, pCMF1, which is expressed exclusively and transiently in the myogenic cells of the differentiating chicken heart was isolated and characterized. The full-length cDNA of pCMF1 has one open reading frame encoding 1538 predicted amino acids. While computer analysis predicts the presence of specific structural motifs, the overall sequence of pCMF1 is unique. The pattern of pCMF1 gene expression during heart formation was determined by whole-mount in situ hybridization. pCMF1 is transiently expressed within the myogenic cells of the primitive heart tube from stages 9 to 18 and is not detected in the heart or any other tissue thereafter. A replication-deficient retrovirus was used to mediate pCMF1 antisense expression in cardiogenic mesoderm. These analyses determined that the presence of pCMF1 antisense sequences disrupted myosin heavy chain expression during cardiac mesoderm differentiation. pCMF1 antisense had no effect on myosin heavy chain expression in differentiated cardiac myocytes. These data suggest a potential function for pCMF1 during cardiac myogenesis.

Amino Acid Sequence↗
PubMed1995

QCE-6: a clonal cell line with cardiac myogenic and endothelial cell potentials.

A clonal cell line (QCE-6) sharing many properties with splanchnic mesodermal cells has been derived from 20-methylcholanthrene-treated cardiogenic mesoderm of the Japanese quail. QCE-6 cells which have been stably maintained for over 4 years in vitro display positive staining with antibodies to cytokeratin, vimentin, cingulin, and N-cadherin but were negative for markers of endothelial, fibroblastic, smooth, and skeletal muscle cell lineages. In the present study, we show that addition of retinoic acid and growth factors initiated cardiomyogenic differentiation in approximately 50% of QCE-6 cells as indicated by the expression of muscle- and cardiac-specific proteins. The distribution of these proteins in induced cells was similar to precontractile cardiac myocytes. In addition to these myogenic cells, cultures of induced QCE-6 cells contained endothelial cells as visualized by the presence of QH1 antigen and extracellular matrix molecules associated with endothelial cells. These data demonstrate that the QCE-6 cell is a progenitor of both cardiac myogenic and endothelial cell lineages and along with other recent studies (Linask and Lash, 1993; Garcia-Martinez and Schoenwolf, 1993) suggest that these two cell lineages may have a common embryonic origin.

Animals↗
PubMed1995

Diversification of cardiomyogenic cell lineages in vitro.

The ability of undifferentiated cardiogenic mesoderm to generate diversified myogenic phenotypes was assayed in a minimal culture system. During cardiogenesis in vivo, the anterior and posterior segments of the avian heart have distinct patterns of contractile protein gene expression when they first differentiate. To assess the potential of undifferentiated cardiogenic tissue to diversify into distinct anterior and posterior lineages prior to heart formation, cardiogenic mesoderm and endoderm were removed together from the embryo at Hamburger and Hamilton stages 4-8. Explants from each of these stages differentiated in defined medium as indicated by the expression of muscle-specific genes. However, the ability to express the atrial-specific myosin heavy chain (AMHC) mRNA was confined to posterior cardiac progenitors. Diversification was not dependent on anterior endoderm, suggesting that inductive interactions between the mesoderm and endoderm are not necessary to maintain diversified cardiac lineages after stage 4. The diversified potential of explanted cardiogenic tissue was altered with retinoic acid treatment, resulting in the activation of AMHC1 gene expression in the anterior progenitors. Anterior cardiogenic cells removed from the embryo at stage 8, when the heart begins to differentiate in vivo, are not susceptible to the alteration of diversified phenotype by retinoic acid treatment. Therefore, the potential to form distinct cardiomyogenic cell lineages is present in the anterior lateral plate mesoderm soon after gastrulation and the maturation of these lineages in a positionally dependent manner is maintained in a simple defined culture system in vitro.

Animals↗
PubMed1995

Neonatal urinary uric acid/creatinine [correction of ceratinine] ratio as an additional marker of perinatal asphyxia.

UNLABELLED: The diagnosis and evaluation of perinatal asphyxia can be problematic and objective means of assessing its severity are lacking. To study the validity of urinary uric acid as a marker of the degree of perinatal asphyxia, the ratio of urinary uric acid to creatinine (UA/Cr) in urine specimens obtained after birth was measured in two groups of infants. Eighteen term infants with Apgar scores < or = 5 at 5 min and/or an umbilical cord blood pH < or = 7.2, and a base deficit > or = 12 meq/l were compared to 50 healthy controls. The severity of the perinatal asphyxia was determined by using an ASPHYXIA SCORE. The UA/Cr was higher in the asphyxiated group when compared to controls. (2.06 +/- 1.12, vs. 0.64 +/- 0.48; P < 0.001). Within the perinatal asphyxia group, a significant correlation was found between the UA/Cr ratio and the asphyxia score. (r = 0.86, P < 0.01). CONCLUSION: Infants with perinatal asphyxia have a significantly higher urinary UA/Cr ratio. This may be used as an indicator of the severity of perinatal asphyxia.

Asphyxia Neonatorum↗
PubMed1995

Initiation of cardiac differentiation occurs in the absence of anterior endoderm.

Anterior endoderm has been proposed to be a specific inducer of cardiac differentiation in vertebrates (reviewed in Jacobson and Sater, Development 104, 341-359, 1988). The ability of cardiogenic mesoderm to differentiate in a minimal culture system was examined using cardiac-specific gene expression as an assay. Anterior lateral plate mesoderm was explanted from chick embryos with and without associated endoderm at developmental stages from just after gastrulation (stage 4; Hamburger and Hamilton, J. Morph. 88, 49-67, 1951) to just prior to contraction (stage 9). At all stages examined, cardiogenic mesoderm expressed a profile of cardiac-specific mRNAs after two days in minimal medium independent of the presence of endoderm. Our studies indicate that endoderm is necessary for the generation of stable sarcomeric protein expression, organized myofibrils and beating tissue from stage 4-6. Subsequent to this stage, an interaction with anterior endoderm is no longer required. Examination of cardia bifida embryos from which anterior endoderm had been unilaterally removed also showed a stage-dependent effect of endoderm on beating, while cardiac gene expression and heart morphogenesis were unaffected. These results demonstrate that anterior endoderm does not induce or maintain cardiac gene expression, nor is it required for terminal differentiation. Endoderm does appear to be necessary for a short period of time between initiation of cardiac gene expression and the onset of contraction.

Animals↗
PubMed1994

Staging of commitment and differentiation of avian cardiac myocytes.

The present study establishes the earliest time point for commitment of cardiac myocyte progenitors at gastrulation and determines the effects of bromodeoxyuridine (BrdU) on postgastrulated committed cardiac progenitor cells at a molecular level. Using immunochemical and reverse transcription/polymerase chain reaction assays for cardiac muscle-specific gene expression, we found that while both pre- and postgastrulated embryonic cells were capable of cardiogenic differentiation at high cell density, only postgastrulated cells exhibited the ability to differentiate at clonal density. These data indicate that while cardiac myocyte differentiation of pregastrulated cells can occur in vitro, cell-cell interactions are necessary for this to happen. Only gastrulated cardiac progenitor cells are able to differentiate in the absence of cell-cell interactions and are therefore both specified and committed. Next, by exposing postgastrulated committed cardiac progenitor cells from embryos at various stages to BrdU, we demonstrated that these cells from the lateral-plate mesoderm vary in their ability to differentiate into cardiac myocytes in vitro. Differentiation of cardiac myocyte progenitor cells from stages 4 and 5 was completely blocked by BrdU, whereas it was not blocked in cells from stages 7 and 8 and cells from stage 6 were varied in their reaction. Analysis of cardiac myogenesis in vivo revealed that cardiac progenitors acquire BrdU resistance as they migrate, postgastrulation, anteriorly along a rostrocaudal axis. The results from these two experiments suggest that while pregastrulated cells exhibit a limited ability to undergo cardiac myocyte differentiation, only postgastrulated anterior lateral-plate mesoderm contains committed cardiac myocyte progenitors and that these committed progenitors are not equivalent in their ability to differentiate.

Animals↗
PubMed1994

Expression of the atrial-specific myosin heavy chain AMHC1 and the establishment of anteroposterior polarity in the developing chicken heart.

A unique myosin heavy chain cDNA (AMHC1), which is expressed exclusively in the atria of the developing chicken heart, was isolated and used to study the generation of diversified cardiac myocyte cell lineages. The pattern of AMHC1 gene expression during heart formation was determined by whole-mount in situ hybridization. AMHC1 is first activated in the posterior segment of the heart when these myocytes initially differentiate (Hamburger and Hamilton stage 9+). The anterior segment of the heart at this stage does not express AMHC1 although the ventricular myosin heavy chain isoform is strongly expressed beginning at stage 8+. Throughout chicken development, AMHC1 continues to be expressed in the posterior heart tube as it develops into the diversified atria. The early activation of AMHC1 expression in the posterior cardiac myocytes suggests that the heart cells are diversified when they differentiate initially and that the anterior heart progenitors differ from the posterior heart progenitors in their myosin isoform gene expression. The expression domain of AMHC1 can be expanded anteriorly within the heart tube by treating embryos with retinoic acid as the heart primordia fuse. Embryos treated with retinoic acid prior to the initiation of fusion of the heart primordia express AMHC1 throughout the entire heart-forming region and fusion of the heart primordia is inhibited. These data indicate that retinoic acid treatment produces an expansion of the posterior (atrial) domain of the heart and suggests that diversified fates of cardiomyogenic progenitors can be altered.

Amino Acid Sequence↗
PubMed1993

Analysis of sweat during soft tissue breakdown following pressure ischaemia.

This paper examines the nature of tissue metabolites collected in thermally induced sweat following the application of different loading regimes on the soft tissues of able-bodied subjects. Loading was produced by 1) external application on the forearm via both a tourniquet and a uniaxial indenter system, and 2) ischial support on a wheelchair and sacral support on an examination bed. In each case sweat pads were attached to the tissue areas of a group of able-bodied subjects and interface pressures were recorded. After a prescribed period, the pads were removed and a quantitative analysis of a range of metabolites was performed. Results indicated that tissues subjected to pressure ischemia produced a general increase in concentrations of lactate, chloride, urea, and urate associated with a decreased sweat rate. In the reperfusion phase, some of these metabolites returned to unloaded levels. It is proposed that specific metabolites may be used as an indicator of soft tissue damage.

Adult↗
PubMed1993

[Treatment of perennial non-allergic rhinopathy with capsaicin].

Twenty-seven patients suffering from perennial non-allergic rhinitis were treated with capsaicin. The drug was applied intranasally seven times during intervals ranging from 4-7 days. The regimen involved application of a 0.5 ml of a 10 micromolar capsaicin solution on the first day of treatment, 0.5 ml of a 30 micromolar solution on the 2nd and 3rd days of treatment and 0.5 ml of a 100 micromolar solution on the 4th to 7th days of treatment. Two patients dropped out, one because he developed an exanthema of both forearms and the other for unknown reasons. Other side-effects observed were epistaxis (1 case) and increased dryness of the nasal mucosa. Twenty-two patients had experienced nasal obstruction, hypersecretion, nasal itching, sneezing, mucosal dryness and headache before and 6 months following capsaicin application and judged the success of therapy 6 months following treatment. Three patients did not take part in the follow-up. Fifteen of 27 patients felt no change had occurred in nasal complaints, while 7/27 scored significant improvement. Additionally, 11/27 subjects would not undergo this treatment a second time because it had been unsuccessful and/or painful. The mean symptom scores for nasal obstruction, hypersecretion, itching, dryness and headache revealed no significant changes before and 6 months following treatment with capsaicin. Blockers did not benefit from capsaicin treatment. The best change to benefit from intranasal capsaicin application involved patients with nasal hypersecretion and sneezing without substantial obstruction.

Administration, Intranasal↗
PubMed1992

Supplemental oxygen and exercise performance in patients with cystic fibrosis with severe pulmonary disease.

Patients with cystic fibrosis (CF) and advanced pulmonary disease have pulmonary limitation of exercise, often associated with arterial oxygen desaturation. Improving oxygenation during exercise by providing supplemental oxygen may improve exercise performance in these patients. To test this, we performed graded exercise stress tests in 22 CF patients with severe pulmonary disease (mean PaO2, 64 +/- 2 mm Hg [+/- SE]; PaCO2 46 +/- 2 mm Hg; RV/TLC, 57 +/- 4 percent; FEV1, 38 +/- 4 percent of predicted; FEF25-75%, 13 +/- 2 percent of predicted; median age, 26 years) and compared them to 21 controls (RV/TLC, 27 +/- 4 percent; FEV1, 112 +/- 2 percent of predicted; FEF25-75%, 80 +/- 4 percent of predicted; median age, 29 years). Each subject performed graded exercise stress tests while breathing FIO2 of 0.21 and FIO2 of 0.30. Subjects were blinded to the composition of the inspired gas, and the order of testing was randomized. We found that CF subjects exercised longer, had a higher maximal VO2, higher O2 pulse, and less arterial oxygen desaturation when receiving supplemental O2. Control subjects exercised longer when breathing supplemental O2 but had no significant change in maximal VO2, O2 pulse, or SaO2. Both CF and control subjects had increased end-tidal PCO2 when exercising while breathing supplemental O2. We conclude that CF patients with advanced pulmonary disease have increased exercise tolerance and aerobic capacity when exercising while breathing supplemental O2.

Adolescent↗
PubMed1991

Structure and developmental expression of troponin I isoforms. cDNA clone analysis of avian cardiac troponin I mRNA.

We isolated avian (chicken and quail) cardiac troponin I (TnIcardiac) cDNA clones for studies of Tn-Icardiac protein structure/evolution and developmental gene regulation. Comparison of the cDNA-predicted avian TnIcardiac amino acid sequences with known TnI sequences indicated 1) that the presence of an N-terminal extension sequence carrying a dual protein kinase A phosphorylation target site and an adjacent proline-rich segment is an ancient cardiac-specific feature of TnI which has been conserved since the bird/mammal divergence, 2) that features of the near-N-terminal troponin C (TnC)-binding site sequence suggest isoform-specific adaptation of TnI and TnC, and 3) that the avian TnIcardiac internal actin/TnC-binding, actomyosin-inhibitory, domain shows significant sequence divergence from mammalian TnIcardiac sequences, including the absence of a protein kinase C target site which is a cardiac-specific feature of TnI in mammals. Use of the cDNA clones to probe TnIcardiac mRNA expression during striated muscle development showed active expression in cardiac muscle from early developmental times (day 4 in ovo), but not in embryonic or adult skeletal muscle or in embryonic skeletal muscle cell cultures. Transcriptional run-on analysis showed that the heart-specific expression of TnIcardiac mRNA in embryonic striated muscle reflects transcriptional control of TnIcardiac gene expression. In many other contractile protein gene families, genes encoding cardiac isoforms are expressed early in skeletal muscle development and are later repressed. Thus, the restriction of active TnIcardiac gene expression to the cardiac muscle cell lineage is an unusual expression pattern for cardiac contractile protein genes and indicates that diverse gene regulatory mechanisms direct the differential expression of cardiac and skeletal muscle isoforms in different muscle gene families.

Amino Acid Sequence↗
PubMed1991

Identification and characterization of a ventricular-specific avian myosin heavy chain, VMHC1: expression in differentiating cardiac and skeletal muscle.

To investigate the initial differentiative processes of avian cardiac and skeletal myogenesis, we have isolated and characterized a molecular marker of the cardiac myocyte cell lineage, ventricular myosin heavy chain 1 (VMHC1). Our goal in this initial study was to use a gene-specific probe to analyze the expression pattern of VMHC1 RNA during development. DNA sequence analysis confirmed that VMHC1 represented a novel member of the MHC gene family. PCR analysis using gene-specific primers determined that the VMHC1 RNA is first expressed in the stage 7 cardiac primordia, much earlier than the appearance of a tubular beating heart. RNA blot analyses determined that the VMHC1 message was present in the embryonic and adult ventricles but not in the embryonic or adult atria or skeletal muscle tissues of either the fast or slow type after definitive muscle structures were formed. Still, PCR and in situ hybridization analyses of the initial phases of cardiac and skeletal myogenic differentiation determined that VMHC1 was expressed in both progenitor populations at the initiation of myogenesis regardless of the source of myoblast or site of initial differentiation. The transient expression in skeletal muscle precursors coincided with the onset of differentiation in these cells. These data suggest that the differentiative programs of cardiac and skeletal myocytes overlap during their initial phases, then quickly become distinct. The VMHC1 gene should provide a model for identification of transcription factors involved in cardiac myocyte differentiation.

Amino Acid Sequence↗
PubMed1991

Confronting conflict. A nursing home staff comes to grips with an elderly patient's decision to refuse nutrition.

For the most part, cases involving young or middle-aged persons such as Nancy Cruzan and Paul Brophy have shaped the legal and ethical landscape regarding the obligation to provide nutrition and hydration to nutritionally compromised patients. But the issue of care givers' responsibility in this area also arises frequently in the long-term care setting. One of the most difficult situations to address is what to do when an elderly patient begins to refuse adequate nutrition. Staff at Apartment Community of Our Lady of the Snows, Belleville, IL, had to wrestle with this question when Jane, a 90-year-old resident, decided her life had become too unbearable to continue. She refused to eat and demanded that nutrition not be forced on her. As they considered her situation, staff had to ask whether they clearly understood Jane's position, what actions would be in her best interest, what their professional obligations were, what they could do if her decision conflicted with professional or institutional values, and whether Church teaching shed any light on the issue. Unable to devise an alternative course of action acceptable to Jane, staff eventually acquiesced to Jane's request. Although they realized the difficulty of knowing with certainty what the right course of action is in such a case, they found support for their decision in Church teaching and in legal rulings on conflicts between the state's interest in preserving life and a patient's right to privacy.

Aged↗