Biomedical subjects
Publications and source records attributed to M Fried.
Bone invasion by squamous cell carcinoma (SCC) is very rare in locations other than the head and neck region. The case of a 30-year-old man with slow-growing SCC of the shoulder region, aggressively invading neighboring bony structures, was presented.
The authors describe possible non-surgical treatment of extensive haemorrhoids grade 3 and 4, using Barron's rubber band ligation. To make comparison of therapeutic results possible Dennison's Sheffield classification is used. In the mentioned new approach indications for ambulatory treatment or short-term hospitalization in patients with an advanced grade of internal or external haemorrhoids are extended. From a group of 145 patients treated by this method 126 were free of subjective complains during a check-up 12 months after termination of treatment.
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The Surf-1/Surf-2 bi-directional promoter contains binding sites for at least three transcription factors (Su1, Su2, and Su3). By screening a lambda gt11 HeLa cell cDNA expression library with a concatenated Su2 factor binding site, we isolated a cDNA which encodes a protein with sequence-specific DNA binding activity. Gel retardation assays showed that the cloned factor binds specifically to the Su2 factor binding site present in the human Surf-1/Surf-2 promoter but not to an Su2 site containing mutated base pairs. Co-transfection experiments demonstrated that the cloned cDNA had little or no effect on the expression of a reporter gene under the control of multiple Su2 factor binding sites. Similarly a fusion protein in which the acidic activation domain of HSV VP16 was linked to the cloned factor had no effect, implying that the factor does not function as a DNA binding protein in vivo. DNA sequence analysis revealed that the cloned cDNA is identical to that of human steroid 5 alpha-reductase 1, an enzyme which converts testosterone to dihydrotestosterone. These results are discussed with respect to other putative transcription factors which have been isolated from cDNA expression libraries on the basis of their sequence-specific DNA binding activity.
Gastrointestinal endoscopy is frequently associated with a fall in oxygen saturation and ECG abnormalities. Nevertheless, clinically relevant complications are rare (0.03-0.54%). To date, there is no evidence that electronic monitoring of oxygen saturation or ECG reduces the complication rate of endoscopic procedures, and therefore the routine use of these does not seem justified. However, in high risk patients we recommend prophylactic administration of oxygen (2-4 l/min), if possible combined with pulse oximetry.
The organization of the mouse surfeit locus is unusual in that it contains six housekeeping genes (Surf-1-Surf-6), which are unrelated by sequence homology, in the tightest mammalian gene cluster thus far described. A maximum of only 73 base pairs separates any two of the four well-characterized genes, and two of the genes overlap at their 3' ends. The direction of transcription of each of the five surfeit genes, Surf-1-Surf-5, alternates with respect to that of its neighbor, suggesting cis-interaction or coregulation between the genes by mechanisms such as the sharing of regulatory elements and/or antisense regulation. The Surf-3 gene has been identified as encoding the ribosomal protein L7a (Rpl7a). We have used the high conservation of the Rpl7a gene to clone the chicken gene and surrounding genomic DNA. The tight clustering and juxtaposition of at least five of the surfeit genes (Surf-1-Surf-5) and their associated CpG-rich islands have been found to be conserved over the 600 million years of divergent evolution that separates birds and mammals. This strongly suggests that the surfeit locus represents a different form of gene cluster in which gene organization may play both a positive and negative regulatory role in gene expression possibly via cis-interactions between the closely spaced genes.
The transcriptional initiation sites of the chicken ribosomal protein L7a (rpL7a) gene have been determined and found to occur at three consecutive cytidine residues at the start of a polypyrimidine tract of 8 base pairs (bp). A comparative analysis of the 5' upstream regions of the mouse, human and chicken rpL7a genes identified two sequence elements (Box A and Box B) conserved over the 600 million years of divergent evolution that separate mammals and birds. Only Box A (nts - 56 to - 39) and Box B (nts - 25 to - 4) sequences were detected to bind nuclear factors from mouse nuclear extracts in an analysis of the mouse rpL7a 5' upstream sequence. Box A and Box B bind different nuclear factors and the factor binding to mouse Box A and mouse Box B sequences could be effectively competed by corresponding homologous sequences from the human and chicken rpL7a promoters. These results indicate that elements of the rpL7a promoter region are conserved between mammals and birds. An in vivo analysis of the mouse rpL7a 5' upstream sequence required for efficient transcription identified the 5' border of the minimal promoter region as lying between nts - 50 and - 56. Constructs containing 56 bp of 5' upstream DNA and the first 25 bp rpL7a exon were very efficiently transcribed indicating that sequences within the first intron are not required for gene expression. No sequence similarity was detected between the rpL7a promoter elements and described promoter elements of other eukaryotic ribosomal protein genes.
Protein-induced DNA bending is of importance in the formation of complex nucleoprotein assemblies such as those involved in the initiation of DNA replication or transcription initiation. We have compared the DNA bending characteristics of the Escherichia coli cyclic AMP receptor protein (CRP or CAP), an archetypal DNA bending protein, to those of TFIID, the eukaryotic TATA-element binding transcription factor. By altering the helical phasing between a CRP binding site and the E. coli melR promoter we have mapped a DNA sequence-directed bend in the downstream region of the promoter. This intrinsic DNA bend may be important in the regulation of the melR promoter by CRP in vivo. Gel retardation assays and DNAse I footprinting show that human TFIID binds to the melR promoter - 10 region. Taking advantage of this fact, and using the CRP-induced DNA bend as a standard, we have employed phase sensitive detection to show that the DNA bend angle induced by TFIID is far less than that induced by CRP. Further evidence to support this conclusion comes from a comparison of the relative mobilities of CRP-DNA and TFIID-DNA complexes. These results place limits on the role of any DNA bending induced by TFIID alone in the initiation of transcription.
A new noninvasive radiation-free method to measure gastric emptying in humans was developed. The upper abdomen was recorded with a magnetic resonance imager after administration of a liquid meal containing Gadolinium tetraazacyclododecane tetraacetic acid as a magnetic resonance image (MRI) marker. Meal volumes, total gastric volumes, and secretory rates were measured. The MRI technique was validated simultaneously by the double indicator method in 5 healthy volunteers and in 5 patients with symptoms of disordered gastric emptying applying gamma camera scintigraphy and MRI in randomized order. Similar gastric meal emptying curves were obtained in volunteers and in patients by MRI and the reference methods as assessed by linear (r greater than 0.90; P less than 0.001) and intraclass correlation analysis (r greater than 0.905) for T1/2, areas under the curve, and percent of gastric meal retained. Furthermore, similar total gastric volumes and gastric secretory rates were measured by MRI and the double indicator technique. The new MRI method correctly reflected gastric emptying disorders in patients. Thus for the first time it is possible to combine these measurements of gastric functions in a single method and to relate them to gastric morphology visualized by the generation of three-dimensional images.
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We prepared a cDNA library from gametocytes of Eimeria maxima and screened it using antibodies raised against an 82-kDa gametocyte antigen. One cDNA clone designated pEM230 was isolated and characterized. It encodes a portion of a 230-kDa gametocyte protein and its DNA sequence shows the presence of several tandem repeats of 42 bp. In order to determine the stage and sex specificity of the mRNA for the 230-kDa protein, Northern blotting and in situ hybridization studies were performed. The 230-kDa protein is encoded for by a 7 kb mRNA, which is expressed exclusively during the macrogamete stage with no detectable expression seen in any other stage of parasite development.
The tubulin gene family in Plasmodium falciparum consists of one beta-tubulin and two alpha-tubulin genes (alpha-tubulin I and II). We present here data indicating that alpha-tubulin II is expressed only in male sexual stage parasites. An IgM mAb, 5E7, specifically reacted with stage III (day 4-5) through mature (day 10-11) male gametocytes and with emerging, exflagellating, or freely moving male gametes. No reactivity was detected in female gametocytes, female gametes, sporozoites, or asexual parasites. mAb 5E7 also specifically recognized male gametes of the avian parasite, Plasmodium gallinaceum, and immunoblotted a 50 kDa protein in extracts of male gametes from both species. This 50 kDa antigen was localized by immunoelectron microscopy to axonemes of male gametes in a pattern similar to that obtained with anti-alpha- and anti-beta-tubulin antibodies. Furthermore, mAb 5E7 specifically reacted with recombinant alpha-tubulin II protein obtained using the PCR-amplified alpha-tubulin II gene from a gametocyte-specific cDNA library. The sex-specific expression of alpha-tubulin II and its localization to axoneme of the male parasite suggest a role for this molecule in the morphologic changes that occur during exflagellation and in the motility of the parasite. alpha-Tubulin II and mAb 5E7 may prove useful tools in studies of the biology of sexual stage differentiation and development in P. falciparum in addition to the general understanding of post-translational modifications of tubulin isoforms.
Mammalian ribosomal protein (rp) genes are members of multigene families which are composed predominantly of multiple processed pseudogenes and one functional intron-containing gene. The presence of multiple pseudogenes has hampered the isolation and study of the functional rp genes. We have recently developed a polymerase chain reaction (PCR)-based strategy for the detection of intron-containing genes in the presence of multiple pseudogenes (B. Davies, S. Feo, E. Heard, and M. Fried, 1989, Proc. Natl. Acad. Sci. USA 86: 6691-6695). We have used this technique to identify the intron-containing PCR products of seven human rp genes (rpL19, rpL30, rpL35a, rpL36a, rpS6, rpS11, rpS17) and to map their chromosomal locations. No linkage was found between any of these seven rp genes nor was linkage found to the three other rp genes previously mapped. The wide distribution of the rp genes throughout the human genome strongly suggests that the coordinate regulation of the expression of mammalian ribosomal proteins in response to the cell's varying requirements for protein synthesis is not a result of cis activation of chromosomal regions but is mediated by trans-acting factors.
The intron-containing gene encoding human ribosomal protein S6 (rpS6), the major phosphoprotein in the mammalian ribosome, has been cloned. Using a PCR based cloning strategy we have isolated the rpS6 intron-containing gene in the presence of its many processed pseudogenes and determined the DNA sequence of the entire gene and its upstream and downstream flanking regions. The human rpS6 gene is 3979 bp in length and comprises six exons. Despite lacking a consensus TATA box, primer extension analysis indicates that the start of transcription is located at a single C residue within an 11 bp oligopyrimidine tract. The first exon, which contains the ATG start codon, is 48 bp in length. The DNA sequence in the 5' region of the gene has features of a CpG-rich island. Using fluorescence in situ hybridization (FISH) analysis the position of the rpS6 gene has been sublocalized to human chromosome 9p21. The similarities and differences between rpS6 and other previously characterized ribosomal protein genes are discussed.
Obstructive sleep apnea syndrome (OSAS) is associated with severe cardiac arrhythmias and conduction abnormalities. Cor pulmonale and right-sided heart failure may ensue. Uvulopalatopharyngoplasty (UPPP) is one of several treatment modalities suggested for OSAS. Tracheotomy and CPAP treatment in adult OSAS patients and adenotonsillectomy in children with OSAS were shown to lead to improvement in some cardiac parameters. Cardiac function was prospectively evaluated in 19 OSAS patients before and after UPPP. No significant changes after surgery were noted on electrocardiographic studies. Improvement in global and regional function of both ventricles was seen in 91% of the patients. A trend toward significant elevation in left ventricular ejection fraction and a statistically significant increase in right ventricular ejection fraction were observed (45% +/- 9% to 50% +/- 7% [p = 0.007]). Our results support performance of UPPP in selected OSAS patients for relief of potentially life-threatening cardiac pathologies.
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