PubMed Health⌕ Search

Biomedical subjects

M A Wani

Publications and source records attributed to M A Wani.

At least 19 recordsLinked to original sources
PubMed2004

Clinical guidelines online: do they improve compliance?

BACKGROUND: The introduction of intranet services in a district general hospital provided an opportunity to put evidence based national guidelines online to facilitate access and promote application of best practice in acute medical care. This study evaluated the effectiveness of this approach. METHOD: Local guidelines were made available online at ward terminals after they had been distributed in paper form. An interrupted time series design was used to evaluate the impact on compliance with three preselected guidelines, which addressed the management of suspected deep vein thrombosis, upper gastrointestinal bleeding, and stroke. This was supplemented by a qualitative assessment of the views of medical staff. RESULTS: There was a significant increase in the adherence to the guidelines for stroke when they were made available online, but this was not demonstrable for deep vein thrombosis or upper gastrointestinal bleeding. Qualitative interviews with junior medical staff and consultants after the study was completed revealed that there was confusion regarding the application of the guidelines for deep vein thrombosis and little active support from the gastroenterologists for the guidelines for upper gastrointestinal bleeding. The stroke guidelines were actively promoted by their author and widely supported. CONCLUSION: Making guidelines available online will not be effective unless they are actively promoted and represent a consensus view.

Algorithms↗
PubMed2002

Acute bilateral extradural hematomas.

The occurrence of bilateral extradural hematomas is an uncommon consequence of craniocerebral trauma and its incidence is variable in various studies ranging from 2-25%.1 We studied all cases of head injury brought to our institute over a period of 6 months and found the incidence of bilateral extradural hematomas to be 13.3%.

Adult↗
PubMed2001

Lung Krüppel-like factor contains an autoinhibitory domain that regulates its transcriptional activation by binding WWP1, an E3 ubiquitin ligase.

Lung Krüppel-like factor (LKLF/Krüppel-like factor 2), a member of the Krüppel-like factor family of transcription factors, is expressed predominantly in the lungs, with low levels of expression in other organs such as heart, spleen, skeletal muscle, and testis. LKLF is essential during pulmonary development and single-positive T-cell development and is indispensable during mouse embryogenesis. In this study, we performed a series of experiments to define the activation domain of LKLF as a means to further advance the understanding of the molecular mechanisms underlying transcriptional regulation by this transcription factor. Using deletion analysis, it is shown that LKLF contains a transcriptional activation domain as well as a strong autoinhibitory subdomain. The inhibitory subdomain is able to independently suppress transcriptional activation of other strong activators such as viral protein 16, VP16. This occurs either when the inhibitory domain is fused directly to VP16 or when the inhibitory domain is independently bound to DNA by GAL4 DNA-binding domain independent of the VP16 activator. Overexpression of the LKLF autoinhibitory domain alone potentiates transactivation by wild type LKLF, suggesting that the inhibitory domain binds a cofactor that prevents LKLF from transactivating. A yeast-two hybrid screen identified WWP1, an E3 ubiquitin ligase that binds specifically to the LKLF inhibitory domain but not to other transcription factors. In mammalian cells, WWP1 functions as a cofactor by binding LKLF and suppressing transactivation. These data demonstrate that LKLF contains multiple domains that either potentiate or inhibit the ability of this factor to function as an activator of transcription; moreover, regulation of LKLF transactivation is attenuated by an E3 ubiquitin ligase, WWP1.

Animals↗
PubMed2001

Mdm2 mutant defective in binding p300 promotes ubiquitination but not degradation of p53: evidence for the role of p300 in integrating ubiquitination and proteolysis.

Turnover of the p53 tumor suppressor protein is mediated by Mdm2 through the ubiquitin proteolysis pathway. p300, a co-activator for p53, also participates in this process by complexing with Mdm2. We now report that the mutant Mdm2, defective in p53 binding, does not promote p53 ubiquitination and degradation in vivo or inhibit p53 transcriptional activation. By contrast, the mutant Mdm2, defective in p300 binding, still retains its activity to promote p53 ubiquitination and to inhibit p53 transcriptional activation but fails in promoting p53 degradation. We also show that both wild-type Mdm2 and the mutant Mdm2, defective in p300 binding, can promote the ubiquitination of cancer-derived p53 mutants, but only wild-type Mdm2 can cause their degradation. Furthermore, adenoviral oncoprotein, 12S.E.1A, but not its deletion mutant that lacks p300 binding, was shown to decrease in vivo ubiquitination of mutant p53. Taken together, these results provide genetic evidence that p300 plays a pivotal role in the regulation of Mdm2-mediated p53 turnover by integrating the cellular ubiquitination and proteolytic processes.

Adenovirus E1A Proteins↗
PubMed2001

Human homologue of yeast Rad23 protein A interacts with p300/cyclic AMP-responsive element binding (CREB)-binding protein to down-regulate transcriptional activity of p53.

The tumor suppressor protein p53 regulates various cellular responses to DNA damage and plays a significant role in DNA repair. The nuclear p300/cyclic AMP-responsive element binding (CREB)-binding protein (CBP) proteins act as coactivators in supporting the transcription function of p53. We examined the role of the human homologue of yeast Rad23 protein A (hHR23A), one of the two human homologues of the Saccharomyces cerevisiae nucleotide excision repair gene product Rad23, in the p300/CBP-associated regulation of p53 activity. Overexpression of wild-type hHR23A inhibits the p53 transcriptional activity and results in a decreased steady-state protein level of cellular p53. The inhibitory effect of hHR23A can be overcome by the concomitant expression of p300, CBP, and p300 segments harboring C/H1 domain and neutralized by the coexpression of HIV accessory protein Vpr, which binds COOH terminus of hHR23A/B. Additionally, hHR23A was shown to interact in vitro and in vivo with p300 segments harboring C/H1 domain. These studies provide evidence for the involvement of hHR23A in the regulation of p53 activity through p300/CBP. Although the precise direct role of hHR23 proteins in regulation of p53 and DNA repair remains to be elucidated, our data suggest that the interaction between hHR23A and p300/CBP has important implications in cross-talk between the p53 pathway and DNA repair.

Animals↗
PubMed2001

Management of Mirizzi syndrome: a new surgical approach.

BACKGROUND: In a prospective study of a patient population of 1,340 with biliary calculus disease, that ran from January 1993 to December 1997, 34 patients (2.53%) were identified as having Mirizzi syndrome. Eight patients were found to have type I (A and B) and 26 patients were found to have type II Mirizzi syndrome. A history of recurrent biliary colic and jaundice was present in the majority of patients. METHODS: Ultrasonography was helpful in five patients and endoscopic retrograde cholangiopancreatography was helpful in 17 patients in the diagnosis of this condition. Because the amount of gall bladder tissue used in choledochoplasty is not yet standardized, a new policy regarding choledochoplasty was adopted. In type IA, retrograde cholecystectomy with simple closure of cystic duct was carried out. In type IB, retrograde cholecystectomy and choledochoplasty with 5 mm cuff of the gall bladder was carried out. In type II lesions the procedure depended on the size of fistula. Patients with fistula sizes of less than one-third of the common bile duct diameter underwent choledochoplasty with 5 mm cuff of the gall bladder, and patients with fistula sizes between one-third and two-thirds of the diameter of the common bile duct underwent choledochoplasty with 10 mm cuff of the gall bladder. Patients with fistula sizes of more than two-thirds of the common bile duct diameter underwent Roux-en-Y hepaticojejunostomy. RESULTS: There was no operative mortality and the complication rate was 17.64%. CONCLUSION: Although, out of 26 choledochoplasties, we encountered only one (3.84%) stump stone in a maximum follow-up period of 59 months, further long-term follow-up studies are required to prove the efficacy of the procedure.

Anastomosis, Surgical↗
PubMed2001

Paraneoplastic limbic encephalitis associated with bronchogenic carcinoma: a case report.

Paraneoplastic limbic encephalitis is a rare clinical entity, associated most often with the oat cell carcinoma of the lung. Clinically, it presents with affective changes in personality, memory loss, confusional state, hallucinations, and seizures; with dementia being the common feature as the disorder progresses. Response to treatment is disappointingly poor.

Carcinoma, Bronchogenic↗
PubMed2000

Enhanced sensitivity to anti-benzo(a)pyrene-diol-epoxide DNA damage correlates with decreased global genomic repair attributable to abrogated p53 function in human cells.

DNA damage from exposure to environmental chemical carcinogens and failure of repair systems to eliminate these lesions from the genome are considered as the crucial initial steps in the development of various human malignancies. Many cellular proteins are known to play vital roles to overcome the effects of DNA damage. Among such proteins, p53 is known to respond to DNA damage by accumulating in the nucleus and inhibiting cell cycle progression to facilitate DNA repair and the maintenance of genomic stability. In this study, we have investigated the role of p53 protein in modulating nucleotide excision repair of anti-benzo-(a)pyrene-diol-epoxide (BPDE)-DNA adducts and related effects using human fibroblasts with normal (p53-WT) and altered p53 protein (p53Mut and p53-Null). Interestingly, irrespective of the presence or absence of p53, the anti-BPDE dose-dependent p21 protein induction response was qualitatively comparable in all of the three cell lines. However, cells with defective p53 function were deficient for the removal of anti-BPDE-DNA adducts from the overall genome compared to cells with wild-type p53 activity. Strand-specific repair analysis within the individual strands of the p53 gene revealed decreased repair of adducts from the nontranscribed strand in p53-Mut and p53-Null cells. However, the repair of the transcribed strand appeared to be identical in all of the three cell lines. Furthermore, p53-Mut and p53-Null cells were more sensitive than p53-WT cells and displayed increased levels of anti-BPDE-induced apoptosis. Thus, wild-type p53 is required for the efficient global genomic repair of anti-BPDE-induced DNA adducts from the overall genome, but not for transcription-coupled repair of actively transcribed genes. These findings indicate that inefficient DNA repair of potentially cytotoxic and mutagenic lesions from the nontranscribed strand due to the loss of p53, but not the loss of p21, function might be responsible for enhanced cytotoxicity and apoptosis in human cells upon DNA damage.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2000

Decreased DNA repair efficiency by loss or disruption of p53 function preferentially affects removal of cyclobutane pyrimidine dimers from non-transcribed strand and slow repair sites in transcribed strand.

The tumor suppressor protein p53 plays a central role in modulating the cellular responses to DNA damage. Several recent studies, undertaken with the whole genomic DNA or full-length gene segments, have shown that p53 is involved in nucleotide excision repair and it selectively influences the adduct removal from the non-transcribed strand in the genome. In this study, we have analyzed the damage induction at nucleotide resolution by ligase-mediated polymerase chain reaction and compared the repair of ultraviolet radiation-induced cyclobutane pyrimidine dimers within exon 8 of p53 gene in normal and Li-Fraumeni syndrome fibroblasts as well as in normal and human papillomavirus 16 E6 and E7 protein-expressing human mammary epithelial cells. The results demonstrate that (i) loss or disruption of p53 function decreases efficiency of DNA repair, by preferentially affecting the repair of non-transcribed strand and of intrinsically slow repair sites in transcribed strand; (ii) mutant p53 protein affects DNA repair, at least of non-transcribed strand, in a dominant negative manner; and (iii) pRb does not have an effect on the repair of DNA damage within transcribed or non-transcribed strand. The overall data suggest that p53 could regulate excision repair or related events through direct protein-protein interaction.

Cells, Cultured↗
PubMed2000

p53-degradation by HPV-16 E6 preferentially affects the removal of cyclobutane pyrimidine dimers from non-transcribed strand and sensitizes mammary epithelial cells to UV-irradiation.

Nucleotide excision repair (NER), the most versatile and ubiquitous mechanism for DNA repair, operates to remove many types of DNA base lesions. We have studied the role of p53 function in modulating the repair of DNA damage following UV irradiation in normal and p53-compromised human mammary epithelial cells (HMEC). The effect of UV-induced DNA damage on cellular cytotoxicity and apoptosis was determined in conjunction with global, gene- and strand-specific repair. Cytotoxicity studies, using clonogenic survival and MTT assays, showed that HPV-16 E6-expressing HMEC were more UV sensitive than p53-WT cell lines. High apoptotic index obtained with p53-compromised cells was in conformity to both the low clonogenic survival and the low cellular viability. No discernible differences in the formation of initial UV-induced cyclobutane pyrimidine dimers (CPD) were observed in the cell lines of varying p53 functional status. However, the extent and the rate of damage removal from genome overall were highest for p53-WT cells. Further examination of strand-specific repair in the p53 gene revealed that the removal of CPD in the non-transcribed strand (NTS) was slower in p53-compromised cells compared to the normal p53-WT cell lines. These results suggest that loss of p53 function, in the absence of other genetic alterations, decreased both overall amount of CPD repaired and their removal rate from the genome. Additionally, normal function of p53 is required for the repair of the NTS, but not of the transcribed strand (TS) in genomic DNA in human epithelial cells. Thus, failure of quantitative removal of CPD by global genomic repair (GGR), due to loss of p53 function, causes the enhanced UV sensitivity and increased damage-induced apoptosis via a p53-independent pathway. Nevertheless, recovery of cells from UV damage requires normal p53 function and efficient GGR.

Apoptosis↗
PubMed2000

AnkB, a periplasmic ankyrin-like protein in Pseudomonas aeruginosa, is required for optimal catalase B (KatB) activity and resistance to hydrogen peroxide.

In this study, we have cloned the ankB gene, encoding an ankyrin-like protein in Pseudomonas aeruginosa. The ankB gene is composed of 549 bp encoding a protein of 183 amino acids that possesses four 33-amino-acid ankyrin repeats that are a hallmark of erythrocyte and brain ankyrins. The location of ankB is 57 bp downstream of katB, encoding a hydrogen peroxide-inducible catalase, KatB. Monomeric AnkB is a 19.4-kDa protein with a pI of 5.5 that possesses 22 primarily hydrophobic amino acids at residues 3 to 25, predicting an inner-membrane-spanning motif with the N terminus in the cytoplasm and the C terminus in the periplasm. Such an orientation in the cytoplasmic membrane and, ultimately, periplasmic space was confirmed using AnkB-BlaM and AnkB-PhoA protein fusions. Circular dichroism analysis of recombinant AnkB minus its signal peptide revealed a secondary structure that is approximately 65% alpha-helical. RNase protection and KatB- and AnkB-LacZ translational fusion analyses indicated that katB and ankB are part of a small operon whose transcription is induced dramatically by H(2)O(2), and controlled by the global transactivator OxyR. Interestingly, unlike the spherical nature of ankyrin-deficient erythrocytes, the cellular morphology of an ankB mutant was identical to that of wild-type bacteria, yet the mutant produced more membrane vesicles. The mutant also exhibited a fourfold reduction in KatB activity and increased sensitivity to H(2)O(2), phenotypes that could be complemented in trans by a plasmid constitutively expressing ankB. Our results suggest that AnkB may form an antioxidant scaffolding with KatB in the periplasm at the cytoplasmic membrane, thus providing a protective lattice work for optimal H(2)O(2) detoxification.

Amino Acid Sequence↗
PubMed2000

Modulation of transcriptional activity of p53 by ultraviolet radiation: linkage between p53 pathway and DNA repair through damage recognition.

The increase in the p53 activity in response to DNA damage is thought to be one of the important mechanisms by which p53 contributes to transcriptional activation of p21(wafl), mdm2, and other downstream regulatory genes. To investigate the p53 response to ultraviolet (UV) type of DNA damage, p53 protein level, its transcriptional activity and in vivo ubiquitination were compared in repair-proficient normal human fibroblasts (NHFs) and repair-deficient xeroderma pigmentosum (XP) group A and group C (XP-C) fibroblasts subsequent to irradiation with UV light. Accumulation of p53 protein level was observed with increasing UV doses in all the cell lines; however, discordance between p53 and p21(waf1) and mdm2 levels was observed in NHF and XP-A cells. Induction of p21(waf1) and mdm2 was inhibited by UV irradiation, requiring higher doses in NHF and lower doses in XP-A cells. However, inhibition of p21(waf1) and mdm2 induction was not observed in XP-C cells. Ubiquitin-p53 conjugates could be detected in irradiated or unirradiated NHF and XP-A cells but not in XP-C cells irradiated with 30 and 50 J/m(2) UV light. Using a p53 reporter assay, p53 transcriptional activities were found to be induced by 10 J/m(2) UV exposure and dramatically inhibited with increasing UV doses in NHF cells. Compared with repair-proficient NHF cells, UV inhibition of p53 transcriptional activity was relatively more sensitive in XP-A cells but resistant in XP-C cells. These results indicate that DNA damage by UV, in addition to inducing p53, acts as a trigger for inhibition of p53 transcriptional activity. Overall, recognition of DNA damage links both p53 induction and p53 degradation to DNA repair mechanisms.

Cell Line↗
PubMed1999

cDNA isolation, genomic structure, regulation, and chromosomal localization of human lung Kruppel-like factor.

Lung Kruppel-like factor (LKLF) is a zinc finger transcription factor critical for embryonic development. We have previously identified and isolated the mouse LKLF gene and examined its role using gene targeting. In this report, we describe the isolation and molecular characterization of the human homolog of murine LKLF. The human and mouse LKLF homologs exhibit an 85% nucleotide identity and share 90% amino acid similarity. Furthermore, the 5' sequence in the proximal promoter region and 3' untranslated region are also conserved between the two species. Of particular interest is the finding that while sequences in the proximal promoter have diverged between mouse and human, a region of 75 nucleotides is essentially identical. Site-directed mutagenesis in this region impairs the ability of the LKLF promoter to drive reporter gene expression, indicating that it represents a novel transcriptional element important in the regulation of LKLF gene expression. The activation domain is highly proline-rich and, similar to mouse LKLF, contains 22% proline residues. The human LKLF transcriptional unit is located in a genomic region of approximately 3 kb on chromosome 19p13.1. This region of chromosome 19 is known to contain genes involved in various human diseases. Like mouse LKLF, human LKLF consists of three exons that are interrupted by two small introns. The locations of intron/exon boundaries and splice sites are conserved between two homologs. Northern analysis shows that LKLF is expressed in lung in addition to heart, skeletal muscle, placenta, and pancreas. The isolation and chromosomal mapping of human LKLF will make it possible to initiate studies devoted to assess the involvement of this gene in human disease(s).

Amino Acid Sequence↗
PubMed1999

Lung Kruppel-like factor, a zinc finger transcription factor, is essential for normal lung development.

Lung Kruppel-like factor (LKLF) is a member of the Kruppel-like factor family of transcription factors and is highly expressed in lung with limited distribution in other tissues. Mice lacking LKLF due to inactivation of LKLF by gene targeting die in utero at midgestation around day 12.5 due to severe hemorrhage, making it difficult to study the role of this transcription factor in lung development and function. However, in vitro organ culture of lung buds removed from 11.5-day-old LKLF(-/-) embryos show normal tracheobronchial tree formation. To examine later stages of lung development, the embryonic lethality due to germ line LKLF null mutation was circumvented by constructing LKLF homozygous null mouse embryonic stem cells, using a two-step gene targeting procedure, and determining whether these cells give rise to lung tissue. The targeted cells were used to produce chimeric animals, and the contribution of LKLF-deficient cells to the formation of various internal organs was analyzed. In chimeric mice that survived after birth, null embryonic stem cells contributed significantly to all of the major organs except the lungs. On the other hand, some highly chimeric animals died at birth, and histopathological examination of their lungs suggested abnormalities in their lung development. These studies show that LKLF plays an important role in normal lung development.

Animals↗
PubMed1999

A gene encoding an intestinal-enriched member of the Krüppel-like factor family expressed in intestinal epithelial cells.

The Krüppel-like factors make up a multigene family of transcription factors that have discrete patterns of expression, implying they play important biological roles in the tissues in which they are expressed. We have identified and characterized the cDNA for a novel murine transcription factor that is an additional member of the Krüppel-like family of transcription factors, named intestinal-enriched Krüppel-like factor (IKLF). This gene appears to be a homolog of the human BTEB-2 gene, although it exhibits a different pattern of tissue expression and the translated product is larger. IKLF is expressed in a limited number of tissues; the highest levels of IKLF expression are found in the digestive tract. IKLF shows temporal changes in expression during embryogenesis indicating that this gene is developmentally regulated. In addition, IKLF expression is limited to the epithelial lining of the intestine and is localized primarily to the base of the crypts in the adult intestine. The IKLF cDNA encodes for a 446 amino acid protein and is able to transactivate by binding specific DNA elements that are also recognized by other members of the Krüppel-like family. In addition, mutations in the activation domain attenuate the ability of this protein to function as a transcription factor. Collectively, these findings show that we have identified a transcription factor that is expressed predominantly in the epithelial crypt cells of the gastrointestinal tract and is a member of the Krüppel-like family of transcription factors.

Amino Acid Sequence↗
PubMed1999

Influence of p53 tumor suppressor protein on bias of DNA repair and apoptotic response in human cells.

A network of interacting cellular components is known to mediate the regulatory role of tumor suppressor protein p53 in genomic stability. DNA repair machinery is considered to be one of these vital cellular components. To investigate the modulatory function of p53 on the repair of DNA damage and related effects, we have studied the responses of human p53-wild-type (p53-WT), p53-mutant (p53-Mut) and p53-nullizygous (p53-Null) cells following exposure to UV irradiation. Absence of wild-type p53 function coincided with an enhanced sensitivity to UV, as well as induction of apoptosis. However, the lack of wild-type p53 expression did not affect the response of its signal transducer protein, p21. Repair analysis of specific genomic sequences, at a single nucleotide resolution, revealed that the removal of cyclobutane pyrimidine dimers in a non-transcribed strand was significantly slower in p53-Mut and p53-Null cell lines compared with the normal p53-WT cells. However, the repair of the transcribed strand was comparable in the three cell lines. Thus, p53 is required for the efficient nucleotide excision repair (NER) of the global genomic DNA, but not for the transcription-coupled repair of the essential genes. The decreased global NER, due to the lost p53 function, seems to be responsible for the conjoined cytotoxicity and apoptosis of human cells subjected to DNA stress damage.

Apoptosis↗
PubMed1998

Loss of LKLF function results in embryonic lethality in mice.

Lung Kruppel-like factor (LKLF) is a member of the Kruppel-like family of zinc finger transcription factors and is closely related to erythroid kruppel-like factor (EKLF), which is necessary for beta-globin gene expression. While EKLF is expressed exclusively in erythroid cells, LKLF is expressed temporally during early embryonic development and predominantly in the adult mouse lung. To understand the role this novel transcription factor plays in development as well as tissue differentiation and function, animals lacking LKLF were produced using gene targeting technology. Mice lacking LKLF die in utero between day 11.5 and 13.5 of embryonic life and exhibit retarded growth, craniofacial abnormalities, abdominal bleeding and signs of anaemia. Although the yolk sac erythropoiesis is normal in mutant embryos, in vitro fetal liver cultures of these embryos fail to give rise to erythroid cells. Expression of other erythroid specific genes such as EKLF, GATA1 and GATA3 is unaltered in these animals. These findings demonstrate the LKLF function is indispensable during normal embryonic development, and although both LKLF and EKLF recognize common DNA motifs, they do not substitute for each other.

Animals↗