Biomedical subjects
M Irani
Publications and source records attributed to M Irani.
Space-time super-resolution.
We propose a method for constructing a video sequence of high space-time resolution by combining information from multiple low-resolution video sequences of the same dynamic scene. Super-resolution is performed simultaneously in time and in space. By "temporal super-resolution," we mean recovering rapid dynamic events that occur faster than regular frame-rate. Such dynamic events are not visible (or else are observed incorrectly) in any of the input sequences, even if these are played in "slow-motion." The spatial and temporal dimensions are very different in nature, yet are interrelated. This leads to interesting visual trade-offs in time and space and to new video applications. These include: 1) treatment of spatial artifacts (e.g., motion-blur) by increasing the temporal resolution and 2) combination of input sequences of different space-time resolutions (e.g., NTSC, PAL, and even high quality still images) to generate a high quality video sequence. We further analyze and compare characteristics of temporal super-resolution to those of spatial super-resolution. These include: How many video cameras are needed to obtain increased resolution? What is the upper bound on resolution improvement via super-resolution? What is the temporal analogue to the spatial "ringing" effect?
Evidence-based medicine: putting theory into practice.
Evidence-based medicine is an essential tool to ensure the effective and efficient management of patients. A practical and unbiased assessment of clinical evidence can be achieved by asking simple questions about the data. Undertaking this process can reveal a new perspective on traditional treatment approaches.
[Electrical injuries during laparoscopy].
Electrical injury is uncommon during surgical laparoscopy, but may be serious. Following a comprehensive literature review, we describe five mechanisms of burn injuries: direct contact, electric arc, insulation failure, direct or capacitive coupling. We discuss these mechanisms and suggest simple preventive measures designed to ensure optimal safety.
Myocardial revascularization in a hemophiliac.
The case of a mild hemophiliac who underwent a successful and uncomplicated myocardial revascularization is presented. The procedures was safely performed while the patient was receiving factor VIIIC.
Medication use review process and information systems utilized for oncology chemotherapy quality improvement.
Fatal chemotherapy overdoses at prestigious institutions have prompted extensive reviews of policies and procedures in medical centers throughout the country. Improving medication use systems for chemotherapy requires a comprehensive multidisciplinary approach. A process to develop a medical center policy on chemotherapy based on the medication use model adopted by the Joint Commission on Accreditation of Healthcare Organizations will be discussed. This will include the prescribing, preparing, dispensing, administering, and monitoring process as well as quality improvement systems. Pharmacy information systems enhancements that safeguard patients are also discussed including maximum dose checks and specific dosing algorithms for bone marrow transplant patients.
[Early reoperation in chylothorax after thoracic surgery].
Chylothorax is a rare complication of thoracic surgery. The chyle leak can induce serious metabolic and immunological disorders. The ideal treatment of chylothorax has not been clearly established, and opinions are still divided between medical treatment and early or late surgical reoperation after prolonged medical treatment. Out of a total of 1.750 thoracic operations performed at the Centre Chirurgical du Val d'Or over the last 10 years, six cases of chylothorax were reoperated early, an average of five days after the initial operation. The chyle leak was easy to localize in every case. The second operation was performed via the same initial incision. All six patients has an uneventful postoperative course and only one case had a persistent chyle leak which gradually resolved. The mean total hospital stay was 18 days. No systemic infections or deaths were recorded. Early reoperation avoids the complications of prolonged medical treatment, is technically easy and decreases the length of hospital stay.
Fluid replacement in sport and exercise--a consensus statement.
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An unexpected complication following immunoadsorption with a staphylococcal protein A column.
Extracorporeal immune adsorption with staphylococcal protein A (SPA) columns can remove immune complexes and immunoglobulins in the treatment of a variety of diseases. We present the case of an elderly man with neuropathy associated with monoclonal gammopathy, treated by 3 on-line SPA procedures. At the completion of these treatments his neuropathy relapsed, progressing to near-total paralysis. Return to a baseline clinical status required several months. The reason for this severe relapse is not clear. Possible explanations include SPA activation of T-lymphocytes, with release of gamma interferon and increased antigen recognition, or removal of an antiidiotype control mechanism. We advise caution in the application of immunoadsorption to conditions in which it has not yet been evaluated.
Efficacy and improved safety--a new anti-arthritic agent.
Long term studies with nabumetone have confirmed that it is an effective NSAID, comparable to other agents including aspirin and naproxen. Large scale post-marketing studies have shown high response rates and good tolerance.
Cyclic-AMP-dependent switch in initiation of transcription from the two promoters of the Escherichia coli gal operon: identification and assay of 5'-triphosphate ends of mRNA by GTP:RNA guanyltransferase.
We have studied the initiation of transcription of the gal operon in Escherichia coli (i) by analyzing the 5'-triphosphate ends and (ii) by measuring the level of promoter-proximal gal mRNA made in vivo. The 5' termini were identified and quantified by capping with GTP:mRNA guanyltransferase, and the mRNA levels were determined by hybridization of pulse-labeled [32P]RNA with a specific DNA probe. Our results conclusively demonstrate the in vivo activities of two promoters, P1 and P2, with separate initiation sites (S1 and S2) as suggested before from in vitro and in vivo experiments (S. Adhya and W. Miller, Nature [London] 279:492-494, 1979; R. E. Musso, R. DiLauro, S. Adhya, and B. de Crombrugghe, Cell 12:847-854, 1977). We have also studied the effect of cyclic AMP (cAMP) on in vivo gal transcription and found that whereas total gal transcription remains largely unchanged, the relative proportions of the S1 and S2 mRNAs are influenced by the level of cAMP in the cell. In strains devoid of cAMP (cya), transcription initiates equally at S1 and S2; in cAMP-proficient cells (cya+), the S1 initiation increases twofold with a concomitant decrease in S2 initiation. Addition of a saturating amount of exogenous cAMP to cya mutant cells results in a relatively larger switch from S2 to S1. Our results clearly show that while cAMP is an inhibitor of S2, it is not an absolute requirement for transcription initiation at S1, but only acts to increase low-level transcription from the P1 promoter. Using these approaches, we have also studied gal promoter mutants (P211, P18, and P35) which show altered behavior in transcription initiations and in response to cAMP. On the basis of these results, we have discussed models by which transcription initiates at the two overlapping gal promoters (P1 and P2) and discussed how cAMP level modulates the switch between them.
Transcription of the ADH2 gene in Saccharomyces cerevisiae is limited by positive factors that bind competitively to its intact promoter region on multicopy plasmids.
Transcription of the ADH2 gene in the yeast Saccharomyces cerevisiae was inhibited by excess copies of its own promoter region. This competition effect was promoter specific and required the upstream activation sequence of ADH2 as well as sequences 3' to the TATA box. Introducing excess copies of ADR1, an ADH2-specific regulatory gene, did not alleviate the competition that was observed in these circumstances during both constitutive and derepressed ADH2 expression. Excess copies of the upstream region did not release ADH2 from glucose repression, consistent with the view that ADH2 is regulated by positive trans-acting factors.
Candidiasis of the extrahepatic biliary tract.
A case of isolated candidal cholecystitis and cholangitis involving the extrahepatic biliary tract is described. A 72-year-old man developed fever and unexplained jaundice following repair of a descending thoracic aortic aneurysm. Candidemia was noted, and therapy with amphotericin B was instituted. The patient died of a cerebral infarct, and at autopsy the gallbladder was noted to be partly necrotic and contained blastospores and pseudohyphae of Candida albicans. The common bile duct was markedly stenosed and chronically inflamed. Candidiasis of the extrahepatic biliary tract with or without systemic involvement is rare; to our knowledge, only nine cases have been reported. Although this condition represents a diagnostic challenge, the treatment is highly effective with most patients who were described having recovered.
Cyclic AMP-dependent constitutive expression of gal operon: use of repressor titration to isolate operator mutations.
When the gal operator region is present in a multicopy plasmid it binds to all ("titrates") the gal repressor and "induces" the chromosomal gal operon. To make operator mutations (Oa) with reduced affinity toward the repressor, plasmid DNA was irradiated with UV light and mutant derivatives were isolated that were unable to release the chromosomal gal genes from repression. Then with such an Oa plasmid operator revertants were isolated that had reacquired the ability to release repression. Both sets of mutations have been localized by DNA sequence analysis. When the Oa mutations were transferred from the plasmid to the chromosome by recombination these mutant operators were found to make gal expression constitutive (independent of repressor) but still dependent on cAMP, whereas the previously reported gal operator mutants (Oc) are constitutive both in the presence and in the absence of cAMP. The titration method of isolating mutants enables the isolation of strains with operator mutations that also affect normal promoter activity, and it provides an easy way to isolate revertants of operator mutations.
Isolation of mutant promoters in the Escherichia coli galactose operon using local mutagenesis on cloned DNA fragments.
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The collagen gene: evidence for its evolutinary assembly by amplification of a DNA segment containing an exon of 54 bp.
We have determined the size and sequence of 8 exons in the gene that specifies chick type 1 alpha 2 collagen. These 8 exons represent three different segments of the gene, but all encode information for the helical portion of the protein. Seven exons have a length of 54 bp, and the 8th has a size of 99 bp. The sequences within these exons vary except for th glycine codons, which occur every third triplet. Each exon begins with a glycine codon and ends with a triplet that precedes a glycine codon. The size and the sequences of the introns do not show any homology except at their ends. Of 7 introns examined the first six bases at the 5' end of 5 of these are identical. The sequences at the 3' end of the introns also show homologies. Our results imply that the ancestral gene for collagen arose by multiple duplications of a single genetic unit containing a 54 bp condig segment. The sequences within these exons drifted by successive point mutations and in some cases by additions or deletions of 9 bp or multiples of 9 bp.
Isolation and characterization of Escherichia coli mutants defective in enzymes of glycolysis.
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Oto-palato-digital syndrome.
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