As part of our effort to sequence the 100-megabase (Mb) genome of the nematode Caenorhabditis elegans, we have completed the nucleotide sequence of a contiguous 2,181,032 base pairs in the central gene cluster of chromosome III. Analysis of the finished sequence has indicated an average density of about one gene per five kilobases; comparison with the public sequence databases reveals similarities to previously known genes for about one gene in three. In addition, the genomic sequence contains several intriguing features, including putative gene duplications and a variety of other repeats with potential evolutionary implications.
We have identified and characterized the gene for a novel zinc finger transcription factor which we have termed lung Krüppel-like factor (LKLF). LKLF was isolated through the use of the zinc finger domain of erythroid Krüppel-like factor (ELKF) as a hybridization probe and is closely related to this erythroid cellspecific gene. LKLF is expressed in a limited number of tissues, with the predominant expression seen in the lungs and spleen. The gene is developmentally controlled, with expression noted in the 7-day embryo followed by a down-regulation at 11 days and subsequent reactivation. A high degree of similarity is noted in the zinc finger regions of LKLF and EKLF. Beyond this domain, the sequences diverge significantly, although the putative transactivation domains for both LKLF and EKLF are proline-rich regions. In the DNA-binding domain, the three zinc finger motifs are so closely conserved that the predicted DNA contact sites are identical, suggesting that both proteins may bind to the same core sequence. This was further suggested by transactivation assays in which mouse fibroblasts were transiently transfected with a human -globin reporter gene in the absence and presence of an LKLF cDNA construct. Expression of the LKLF gene activates this human -globin promoter containing the CACCC sequence previously shown to be a binding site for EKLF. Mutation of this potential binding site results in a significant reduction in the reporter gene expression. LKLF and EKLF can thus be grouped as members of a unique family of transcription factors which have discrete patterns of expression in different tissues and which appear to recognize the same DNA-binding site.
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.
A total of 18 patients aged 69+/-10 years who had a history of chronic atrial fibrillation, dilated cardiomyopathy, and normal activation (ie, QRS< or =120 ms) were screened for permanent DHBP using an electrophysiology catheter. In 14 patients, the His bundle could be reliably stimulated. Of these 14, permanent DHBP using a fixed screw-in lead was successful in 12 patients. Radiofrequency atrioventricular node ablation was performed in patients exhibiting a fast ventricular response. All patients received single-chamber rate-responsive pacemakers. Acute pacing thresholds were 2.4+/-1.0 V at a pulse duration of 0.5 ms. Lead complications included exit block requiring reoperative adjustment and gross lead dislodgment. Echocardiographic improvement in heart function was shown by reductions in the left ventricular end-diastolic dimension from 59+/-8 to 52+/-6 mm (P=0.01) and in the end-systolic dimension from 51+/-10 to 43+/-8 mm (P<0.01), with an accompanying increase in fractional shortening from 14+/-7% to 20+/-10% (P=0.05). The left ventricular ejection fraction improved from 20+/-9% to 31+/-11% (P<0. 01), and the cardiothoracic ratio decreased from 0.61+/-0.06 to 0. 57+/-0.07 (P<0.01). Despite DHBP, 2 patients died at 8 and 36 months. Conclusions-Permanent DHBP is feasible in select patients who have chronic atrial fibrillation and dilated cardiomyopathy. Long-term, DHBP results in a reduction of left ventricular dimensions and improved cardiac function.
Study design: Secure, web-based survey. Objectives: Elicit specific information about sexual function from men with spinal cord injuries (SCI). Setting: World-wide web. Methods: Individuals 18 years or older living with SCI obtained a pass-code to enter a secure website and then answered survey questions. Results: The presence of genital sensation was positively correlated with the ability to feel a build up of sexual tension in the body during sexual stimulation and in the feeling that mental arousal translates to the genitals as physical sensation. There was an inverse relationship between developing new areas of arousal above the level of lesion and not having sensation or movement below the lesion. A positive relationship existed between the occurrence of spasticity during sexual activity and erectile ability. Roughly 60% of the subjects had tried some type of erection enhancing method. Only 48% had successfully achieved ejaculation postinjury and the most commonly used methods were hand stimulation, sexual intercourse, and vibrostimulation. The most commonly cited reasons for trying to ejaculate were for pleasure and for sexual intimacy. Less than half reported having experienced orgasm postinjury and this was influenced by the length of time postinjury and sacral sparing. Conclusion: SCI not only impairs male erectile function and ejaculatory ability, but also alters sexual arousal in a manner suggestive of neuroplasticity. More research needs to be pursued in a manner encompassing all aspects of sexual function.
Major goals of rehabilitation and health interventions in people with spinal cord injury (SCI) are to improve functional independence, increase social participation, and enhance quality of life (QOL). Determining functional areas perceived by consumers as most important can assist in research prioritization, planning for delivery of health services, and policy development. Five high priority areas of functioning for the SCI population (arm/hand use, walking, bladder/bowel control, sexual function, and relief of pain) were chosen to determine the preferences for these five attributes. A discrete choice experiment was conducted involving 151 persons with SCI sampled from Australia and the United States of America. Consistent with prior research, arm/hand function had the highest preference, with odds ratios of subjects being 44-76% more likely to choose arm/hand function over the other four functions. Preference for normal arm/hand function was found to be significantly more preferred by the group with paraplegia compared with those with tetraplegia; that is, retaining and not trading off existing arm/hand function for other improved functions. There were no significant differences found in preferences between bladder/bowel function and walking or elimination of pain, although walking was preferred in earlier (≤ 10) post-injury years and pain amelioration became more important with a longer duration (>10 years) post-injury. Sexual function had the lowest preference when traded against the other four functions. Understanding the functional preferences of persons with SCI will help to inform future research design, as well as enabling successful translation of research into practice and health policy, meeting the needs of people with SCI.
Erythroid Krü ppel-like factor (EKLF) is a zinc finger transcription factor required for -globin gene expression and is implicated as one of the key factors necessary for the fetal to adult switch in globin gene expression. In an effort to identify factors involved in the expression of this important erythroid-specific regulatory protein, we have isolated the mouse EKLF gene and systematically analyzed the promoter region. Initially, a reporter construct with 1150 base pairs of the EKLF 5-region was introduced into transgenic mice and shown to direct erythroid-specific expression. We continued the expression studies in erythroid cells and have identified a sequence element consisting of two GATA sites flanking an E box motif. The three sites act in concert to elevate the transcriptional activity of the EKLF promoter. Each site is essential for EKLF expression indicating that the three binding sites do not work additively, but rather function as a unit. We further show that GATA-1 binds to the two GATA sites and present evidence for binding of another factor from erythroid cell nuclear extracts to the E box motif. These results are consistent with the formation of a quaternary complex composed of an E box dimer and two GATA-1 proteins binding at a combined GATA-E box-GATA activator element in the distal EKLF promoter.
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