Two proximal CArG elements regulate SM alpha-actin promoter, a genetic marker of activated phenotype of mesangial cells

Mesangial cells express smooth muscle alpha-actin (SM alpha-actin) in response to glomerular injury in vivo, and SM alpha-actin gene expression serves as a genetic marker characterizing the activated phenotype of mesangial cells. We used a molecular genetic approach to analyze the SM alpha-actin promoter and evaluate transcriptional mechanisms that might direct the genetic switch of mesangial cells to the activated phenotype. The sequence spanning -894 to +1 of the SM alpha-actin promoter directed high levels of transcription that were attenuated in serum-restricted cells and upregulated upon treatment with serum or endothelin-1. Deletional analysis revealed a core promoter fragment, from positions -122 to +1, that was necessary and sufficient for transcription. This core activity was modulated by upstream sequences between -670 and -122. The 122-bp core promoter contains two highly conserved CArG box motifs (designated CB1 and CB2), and introduction of deletion mutations of either CB1 or CB2 reduced transcription in mesangial cells to near basal levels. Further analysis revealed that CB1 and CB2 acted synergistically when subcloned upstream of a heterologous, minimal thymidine kinase promoter. CB2 alone was sufficient to confer serum inducibility to a heterologous promoter, but both CB2 and CB1 were required for maximal levels of serum-induced transcription. Collectively, these results demonstrate that CB1 and CB2 cooperate to mediate serum-induced activation of the SM alpha-actin promoter in mesangial cells.

Expression of gax, a growth arrest homeobox gene, is rapidly down-regulated in the rat carotid artery during the proliferative response to balloon injury

gax is a recently described homeobox gene whose expression in the adult is largely confined to cardiovascular tissues, gax has been shown to be rapidly down-regulated in cultured vascular smooth muscle cells (VSMC) upon stimulation by serum or platelet-derived growth factor. The temporal profile of gax expression in vitro matches that of two families of growth arrest genes: the gas genes and the gadd genes. All of these genes are expressed at their highest levels in quiescent cells and are down-regulated following mitogen activation. Here we report that gax is also down-regulated in vivo in the vascular wall in response to endothelial denudation by balloon angioplasty. The reduction in steady state levels of gax mRNA is transient and occurs with a similar time course to that seen in vitro. The down-regulation of gax in response to balloon injury mirrors the up-regulation seen in a number of early response genes such as c-myc and c-fos. This report is the first to document the in vivo expression of a growth arrest gene which regulates proliferation of vascular smooth muscle cells. In addition, in contrast with previous reports which have demonstrated up-regulation of several genes following balloon injury and/or angioplasty, the present report demonstrates the down-regulation of a regulatory gene within hours of balloon injury. The characteristics of gax suggest it may be required to maintain the gene expression of proteins in VSMC that are associated with the nonproliferative or contractile phenotype in smooth muscle cells.

Parameters that influence the extent of site occupancy by a candidate telomere end-binding protein

The MF3 protein specifically recognizes telomeric and non-telomeric DNA probes that can form G.G base-paired structures (Gualberto, A., Patrick, R. M., and Walsh, K. (1992) Genes & Dev. 6, 815-824). Here we further characterize the nucleic acid recognition properties of MF3 and present a mathematical analysis that evaluates the potential extent of telomere site occupancy by this factor. The substitution of dI at dG positions in telomeric DNA probes revealed that a single dG at any position within the internal repeat was sufficient for high affinity binding to MF3. The RNA analogs of high affinity DNA sites were not bound specifically by MF3, but the substitution of dU for dT in a DNA probe had little or no effect on binding. These data demonstrate that ribose ring structure is a critical feature of nucleoprotein complex formation, and this ribose specificity may enable MF3 to occupy sites of unusual DNA structure while minimizing interactions with cellular RNAs. Collectively, the nucleic acid binding properties of MF3 suggest that it may occupy a significant fraction of sites at telomere ends or other G-rich regions of altered DNA structure in vivo.

Rapid characterization of growth-arrest genes in transient transfection assays

We developed a rapid assay for identifying growth-arrest genes to facilitate studies of cell cycle regulation. A7r5 vascular smooth muscle cells were transiently transfected with two plasmids: (i) a pMSV beta Gal reporter construct expressing beta-galactosidase (beta-gal) under transcriptional control of the murine sarcoma virus long terminal repeat; and (ii) a eukaryotic expression vector driving transcription of a potential growth inhibitory c-DNA under control of the cytomegalovirus promoter/enhancer. Twenty-four hours after transfection, cellular DNA was labeled for an additional 24 h with 5-bromo-2-deoxyuridine (BrdU) to label cellular DNA. After fixation, transfected cells were identified by histochemical staining with a beta-gal substrate, 6-chloro-3-indolyl-beta-D-galactopyranoside (i.e., Red-Gal). Transfected cells (beta-gal-positive) that traversed S phase (i.e., DNA synthesis) were quantified by indirect immunocytochemical staining for BrdU. Since autoradiography was not required to score for DNA synthesis, the length of experiments was much shorter than previously described growth-arrest assays performed with transiently transfected cells. Experiments with two growth-arrest genes, p53 and the p21 cyclin-dependent kinase inhibitor, demonstrated the utility of this assay.

Seizure activity causing loss of cardiac output after a Fontan operation

After a Fontan operation pulmonary blood flow is heavily dependent on respiration. Two patients with a Fontan and normal sinus rhythm developed episodes of collapse with loss of cardiac output secondary to the tonic phase of an epileptic fit. The forced expiratory effort during the tonic phase severely compromised systemic venous return and led to collapse due to loss of cardiac output.

Molecular cloning and localization of the human GAX gene to 7p21

The GAX homeobox gene is expressed in the cardiovascular tissues of the adult rat, including heart, lung, kidney, and blood vessels. In the vasculature it is specifically expressed in quiescent smooth muscle cells, but its expression is rapidly down-regulated when these cells are stimulated to proliferate with mitogens. Since vascular smooth muscle cell proliferation is important in the pathology of blood vessel disorders, the human GAX gene was isolated and characterized. The human GAX cDNA was obtained by an anchored-PCR approach using cDNA templates from cardiovascular tissues and amplification primers designed from sequence information of the rat GAX cDNA and the homeodomain-containing exon of the human GAX gene. The human and rat GAX gene coding sequences are 98% conserved at the amino acid level and 83% conserved at the nucleotide level. Similar to rat, the human homolog contains a CAX trinucleotide repeat N-terminal to the homeodomain that encodes for a stretch of 17 consecutive histidine or glutamine residues. The human GAX locus was mapped by fluorescence in situ hybridization to the short arm of chromosome 7 at band p21. The human cDNA sequence will be useful for analyses of GAX gene expression in cardiovascular diseases.

Guidelines for the prevention and control of tuberculosis in the elderly

Tuberculosis (TB) in the elderly is on the rise although the disease is both preventable and curable. The primary practitioner plays a pivotal role in the diagnosis and prevention of TB. The article provides guidelines designed to bring the practitioner up-to-date on the latest recommendations for the prevention and control of TB in the elderly. An overview of TB, current epidemiology, and information on the uniqueness of this disease as it presents in the elderly client is addressed. An in-depth guideline and explanation for all aspects of care are included for both the institutionalized and community-based elder. Current Centers for Disease Control and Prevention recommendations and research are presented. The role of the primary practitioner in the prevention and control of this disease is included with a quick reference tool. The guidelines also address the current diagnostic testing and recommended treatment for TB.

The gene encoding rat phosphoglycerate mutase subunit M: cloning and promoter analysis in skeletal muscle cells

The expression of the gene encoding the muscle-specific (M)-subunit of phosphoglycerate mutase (PGAM-M) is restricted to adult skeletal and cardiac muscle. In order to study its expression in muscle, the rat PGAM-M gene has been isolated and sequenced. Rat PGAM-M spans about 2.2 kb and is composed of three exons: 442, 181 and 186-bp long, and two introns of 97 bp and 1.3 bp. The analysis of the 5'-flanking region reveals a promoter which contains multiple DNA regulatory elements and constitutes an ideal model to study muscle gene transcriptional regulation. Thus, the elements responsible for rat PGAM-M muscle-specific expression have been identified by transient transfection in chicken embryo primary cultures, using chimeric constructs of the rat promoter linked to a cat reporter gene. Here, we report that in spite of the abundance of E-box motifs in the rat PGAM-M promoter known for their involvement in muscle gene expression, two DNA elements regulate the muscle-specific transcription of rat PGAM-M: an A/T motif, the putative MEF-2-binding site (myocyte-specific enhancer-binding factor 2), and a proximal 27-bp element which is conserved between the rat and human genes. These two elements define a small promoter (170 bp) sufficient to support potent and skeletal-muscle-specific expression. The conserved 27-bp region contains a transcriptional regulatory element able to confer muscle-specific expression when located upstream from a heterologous TATA box.

Morphology of left ventricular outflow tract structures in patients with subaortic stenosis and a ventricular septal defect

OBJECTIVE

To compare the incidence and prognosis of subaortic stenosis associated with a ventricular septal defect and to define the morphological basis of subaortic stenosis.

DESIGN

Presentation and follow up data on 202 patients with subaortic stenosis seen at the Royal Liverpool Children's Hospital between 1 January 1960 and 31 December 1991 were reviewed. Survivors were traced to assess their current clinical state. Necropsy specimens of 291 patients with lesions associated with subaortic stenosis were also examined.

RESULTS

In the clinical study; 65 (32.1%) of the 202 patients with subaortic stenosis had a ventricular septal defect (excluding an atrioventricular septal defect). 32 of these patients had a short segment (fibromuscular) subaortic stenosis. 33 had subaortic stenosis produced by deviation of muscular components of the outflow tracts. In 17 patients (51.5%) this was caused by posterior deviation or extension of structures into the left ventricular outflow tract, resulting in obstruction above the ventricular septal defect. In the other 16 patients (48.5%) there was over-riding of the aorta with concordant ventriculoarterial connections, (without compromise to right ventricular outflow) producing subaortic stenosis below the ventricular septal defect. Additional fibrous obstruction occurred in 39% of the patients with deviated structures. The age at presentation was lower (P < 0.01) in patients with deviated structures (median (range) 0.4 (0 to 9.2) months) than in those with short segment obstruction (median (range) 4.2 (0 to 84.9) months). The incidence of aortic arch obstruction was higher (P < 0.002) in patients with deviated structures than in those with short segment obstruction (38%). In the morphological study 35 pathological specimens showed obstructive muscular structures in the left ventricular outflow tract either above or below the ventricular septal defect. 16 had either posterior deviation of the outlet septum or extension of the right ventriculoinfundibular fold, or both of these together into the left ventricle. 19 had anterior deviation of the outlet septum into the right ventricle with overriding of the aorta (without compromise to right ventricular outflow). The earliest age at which additional fibrous obstruction was seen was 9 months. The aortic valve circumference was small in 18% of specimens.

FOLLOW UP

The median (range) duration of follow up in survivors from the clinical study was 6.6 (1 to 25.7) years. 16 patients with deviated musculature (49%) and 16 with short segment fibromuscular stenosis (50%) underwent operation for subaortic stenosis. Patients with deviated structures were younger at operation than those with short segment stenosis (P < 0.005). Patients with posterior deviation or extension of structures into the left ventricular outflow tract underwent operation for subaortic stenosis more frequently (P < 0.05) than those with anterior deviation of the outlet septum and aortic override. The ventricular septal defect required surgical closure more frequently (P < 0.005) in patients with deviation (93.9%) than in those with short segment obstruction (21.9%). There was no significant difference in the mortality between patients with deviation (27%) and those with short segment obstruction (12%).

CONCLUSIONS

32% of patients in the clinical study with subaortic stenosis had a ventricular septal defect. Only 51% of these had obstructive and deviated muscular structures in the left ventricular outflow tract. These patients had a significantly higher incidence of aortic arch obstruction and required surgery for subaortic stenosis at a younger age than those with short segment obstruction. The ventricular septal defect also required surgical closure more frequently in those patients with deviation. The morphological study defined the two sites of obstruction. The presence or absence and type of deviation should be clearly defined in all patients with a ventricular septal defect,

Incidence and prognosis of obstruction of the left ventricular outflow tract in Liverpool (1960-91): a study of 313 patients

OBJECTIVE

To determine the incidence of the various types of obstruction of the left ventricular outflow tract in patients born in the five health districts of Liverpool and to compare their prognosis into early adult life.

DESIGN

Notes of all patients with obstruction of the left ventricular outflow tract born in the study area between 1960 and 1991 were reviewed. Patients with hypoplastic left ventricle, mitral valve atresia, and those with discordant atrioventricular or ventriculoarterial connections were excluded. Survivors were traced and assessed clinically; eight were lost to follow up.

RESULTS

Obstruction of the left ventricular outflow tract occurred in 313 patients (67% male), giving an incidence of 6.1/10,000 live births. The median (range) age at presentation was 13.9 months (0-20 yr). Aortic valve stenosis occurred in 71.2%: subvalve in 13.7%, supravalve in 7.7%, and multilevel in 7.4%. The median (range) duration of follow up was 10.0 (1-29) yr. Aortic regurgitation at presentation occurred more often (p < 0.001) in patients with subvalve stenosis than in those with other types of obstruction, but there was an increased incidence (p < 0.001) at follow up in patients with valve stenosis. Ninety eight patients (31.3%) underwent operation. The reoperation rate was 27% for valve stenosis and 9% for subvalve obstruction. No patients with supravalve stenosis underwent reoperation. The median duration from first operation to aortic valve replacement (17 patients) was 12.3 years. Hazard analysis confirmed that the risk of death was higher in patients presenting at a younger age, with more severe stenosis, and those with subaortic, multilevel obstruction or a syndrome. Hazard analysis also showed that the risk of a clinical event (surgery, balloon dilatation, or endocarditis) was greater in patients who presented at a younger age, with more severe stenosis or aortic regurgitation, and in those with subvalve or multilevel obstruction.

CONCLUSIONS

Aortic valve stenosis was the most common type of obstruction. Hazard analysis indicates that the age and severity of obstruction at presentation have a significant effect on survival and freedom from a clinical event. The risk of premature death in patients presenting with moderately severe valve stenosis is reasonably small, but increases considerably in those with subvalve, supravalve, and multilevel obstruction. Patients who present with mild valve stenosis have a good prognosis. The risk of sudden death is less than previous predictions. Patients with subvalve and multilevel obstruction, even when mild at presentation, are more likely to undergo intervention or develop endocarditis than those with valve or supravalve stenosis. Follow up into adult life is essential.

The mouse creatine kinase paired E-box element confers muscle-specific expression to a heterologous promoter

E-box elements, with the CANNTG sequence motif, occur in numerous promoters and enhancers. We evaluated the tissue-specific expression properties of the paired murine E-box element from the mouse muscle creatine kinase (MCK) enhancer in a minimal heterologous promoter construct. A 46-bp fragment containing the paired E-box element in its wild-type (wt) configuration conferred high levels of muscle-specific expression in transfected embryonic chicken cell cultures. The expression from this paired E-box element was similar to that of the simian virus 40 (SV40) promoter/enhancer, but a 21-bp fragment containing a single E-box was inactive. We conclude that the paired E-box element from the MCK enhancer is sufficient for high levels of muscle-specific expression when placed upstream from a non-muscle TATA element.

In utero pacing for fetal congenital heart block

We report what we believe is the first percutaneous transvenous intracardiac cardiac pacing of a fetus. The case is important because it demonstrates that transvenous fetal cardiac pacing is technically possible and provides a basis for development of the technology.

Cloning and sequence analysis of homeobox transcription factor cDNAs with an inosine-containing probe

Much effort has been directed toward the isolation and characterization of homeobox cDNAs from numerous cell types because they encode transcription factors important to many cellular processes, including pattern formation in the embryo, cell growth and cell differentiation. Many novel homeobox cDNAs have been isolated by screening libraries by hybridization with degenerate oligonucleotides designed from conserved amino acid sequences in the third helix of the homeodomain. However, the degeneracy of the genetic code necessitates that these oligonucleotides be highly degenerate, often precluding their use as sequencing primers to rapidly determine clone identity. Here we describe a screening protocol for homeobox cDNAs that utilizes a short oligonucleotide probe with inosine residues incorporated at positions of maximum codon degeneracy. This probe specifically hybridizes to many classes of homeobox transcription factor cDNAs, but its primary advantage is that it also serves as an effective sequencing primer, which allows the investigator to rapidly determine whether the clones encode a protein of interest. In a screen of 500,000 plaques of a rat aorta cDNA library by this method, we identified 13 positive plaques of which 12 were found to contain homeobox cDNAs representing 5 distinct genes, and, using this probe, it was possible to obtain initial high-quality sequence information from every clone isolated that contained a homeodomain.

Evaluation of the use of general practice age-sex registers in epidemiological research

AIM

This study set out to show how well samples from general practice registers compare with census data, to describe those characteristics of the population and of the register that influence the response to postal surveys, and to demonstrate how general practice records can be used to assess non-response bias.

METHOD

The data for this study were obtained from a large postal survey about low back pain among the general adult population aged 20-59 years in eight areas of the United Kingdom, using general practice age-sex registers as the sampling frame.

RESULTS

The overall response rate was 59%. In the areas chosen, general practice registers yielded samples of size and age-sex composition close to that predicted from national census data. Responses were more likely to be obtained from women, from older age groups and from practices where the sample lists had been inspected for errors. The use of computerized registers and a letter of recommendation from the general practitioner had no effect on the response rate. Inspection of the general practice records of subsamples of respondents and non-respondents to determine consultation rates suggested that there was little response bias in respect of the subject of the survey.

CONCLUSION

General practice registers can provide a suitable sampling frame for epidemiological purposes. Inaccuracies in the register can be reduced to some extent by careful inspection, but an irreducible minimum remain. Information held in general practice records can be useful in assessing response bias in health surveys.

The progression of mild congenital aortic valve stenosis from childhood into adult life

We studied 187 patients who presented with mild congenital aortic valve stenosis or a bicuspid aortic valve without stenosis at presentation; 63% were males. Information on all clinical events was obtained, and patients were traced to assess current clinical status.

RESULTS

The median age at presentation was 2 years (range, 0-15). Additional cardiac lesions occurred in 51 patients, more commonly in patients presenting under 1 year of age (P < 0.0001). The median duration of follow-up was 10 years (range, 1-28); seven patients were lost to follow-up. Thirty-two patients progressed to require intervention (28 surgical, five balloon valvuloplasty) at a median age of 10.5 years. No patient who presented with a bicuspid aortic valve required intervention. Two patients developed endocarditis. There were eight deaths; four after surgery for aortic stenosis and four due to other cardiac lesions. There were no sudden deaths. Actuarial and hazard analysis showed that progression beyond mild stenosis was closely related to duration of follow-up.

CONCLUSIONS

Congenital aortic valve stenosis is most frequently mild at presentation. Progression is related to duration of follow-up. Fewer than 20% of patients are likely to still have mild stenosis after 30 years. Follow-up into adult life is essential.

Long-term administration of valproic acid in the treatment of affective symptoms in people with mental retardation

We report the results of an open trial of valproic acid in the treatment of affective symptoms in people with mental retardation. The study population consisted of 209 people with mental retardation who were serially referred to a tertiary-care medical center for the evaluation of behavioral symptoms. Criteria for treatment included the presence of three of the four following symptoms: irritability, sleep disturbance, aggressive or self-injurious behavior, and behavioral cycling. Twenty-one patients met enrollment criteria and were studied prospectively for a 2-year period. Two patients were lost to follow-up. One patient experienced severe drug side effects. Eighteen patients completed the study. Fourteen patients (78%) responded favorably to treatment and were maintained on valproic acid for the 2 years of the study (p < 0.001). Medications prescribed at the time of enrollment were usually discontinued, including neuroleptic medication in 9 of 10 patients and in all patients (N = 3) who were receiving phenobarbital. A history of epilepsy or a suspicion of seizures was strongly associated with a favorable response to valproic acid (p < 0.005). The results of this study suggest that people with mental retardation and concurrent affective disorders can be recognized by a cluster of developmentally appropriate symptoms such as those listed above. In addition, affective symptoms can be successfully treated with valproate with reductions in neuroleptic and barbiturate anticonvulsant medication. Further study of the comparative benefit of valproate and carbamazepine in this population is warranted.

Recanalisation of an occluded modified Blalock-Taussig shunt by balloon dilatation

A four year old boy with pulmonary atresia and ventricular septal defect had an acute cyanotic episode three years after undergoing a right-sided, 6 mm diameter, modified Blalock-Taussig shunt. On admission no continuous murmur could be heard from the shunt and the typical high velocity, continuous flow profile of the shunt could not be identified by Doppler echocardiography. At catheterisation a right subclavian artery angiogram confirmed shunt occlusion. From the subclavian artery, an 0.035 inch wire was used to enter the occluded shunt and then the pulmonary artery. Balloon angioplasty of the entire length of the shunt was performed with 6 mm diameter balloon. After angioplasty the arterial oxygen saturation increased from 63% to 83%. The patient was treated with intravenous heparin followed by warfarin. Repeat catheterisation and angiography eight days later confirmed wide patency of the shunt.

Spectral Doppler flow profiles in neonates with obstructive lesions of the aortic arch

The aim was to assess the value of continuous and pulsed wave Doppler ultrasound in the detection and differentiation of obstructive lesions of the aortic arch in neonates. In 31 neonates with proven arch obstruction (pre- or juxtaductal coarctation in 19 patients; postductal coarctation in five patients; interrupted aortic arch in four patients; aortic arch atresia in three patients), continuous wave Doppler interrogation of the descending aorta from the suprasternal notch revealed a high velocity jet (greater than 2.2 m/s) directed away from the transducer in 12 patients. Of these, four neonates had preductal coarctation, and five postductal coarctation. The remaining three patients had arch interruption or atresia. Image guided pulsed Doppler ultrasound recordings were obtained from the arch upstream from the obstruction, the descending aorta distal to the obstruction, and from the arterial duct. Patients with coarctation had a prominent diastolic flow directed away from the transducer in the arch upstream from the obstruction, representing a diastolic coarctation gradient, or diastolic steal either by the patent arterial duct or by collateral vessels. In contrast, patients with arch interruption or atresia had only a systolic flow signal in the proximal arch. Ductal flow was either bidirectional (preductal coarctation, arch interruption, arch atresia), continuous right to left flow from pulmonary artery to aorta (one case each of juxtaductal coarctation and arch atresia), or continuous left to right flow from aorta to pulmonary artery (postductal coarctation). In neonates wide patency of the duct often precludes the development of a large pressure drop across a coarctation. Conversely, a high velocity signal may be recorded from a patent but restrictive duct. In conjunction with imaging, pulsed Doppler velocity profiles from the arch and patent duct permit a meaningful interpretation of the haemodynamics of arch obstruction.

Molecular cloning of a diverged homeobox gene that is rapidly down-regulated during the G0/G1 transition in vascular smooth muscle cells

Adult vascular smooth muscle cells dedifferentiate and reenter the cell cycle in response to growth factor stimulation. Here we describe the molecular cloning from vascular smooth muscle, the structure, and the chromosomal location of a diverged homeobox gene, Gax, whose expression is largely confined to the cardiovascular tissues of the adult. In quiescent adult rat vascular smooth muscle cells, Gax mRNA levels are down-regulated as much as 15-fold within 2 h when these cells are induced to proliferate with platelet-derived growth factor (PDGF) or serum growth factors. This reduction in Gax mRNA is transient, with levels beginning to rise between 8 and 24 h after mitogen stimulation and returning to near normal by 24 to 48 h. The Gax down-regulation is dose dependent and can be correlated with the mitogen's ability to stimulate DNA synthesis. PDGF-AA, a weak mitogen for rat vascular smooth muscle cells, did not affect Gax transcript levels, while PDGF-AB and -BB, potent mitogens for these cells, were nearly as effective as fetal bovine serum. The removal of serum from growing cells induced Gax expression fivefold within 24 h. These data suggest that Gax is likely to have a regulatory function in the G0-to-G1 transition of the cell cycle in vascular smooth muscle cells.