Identifying nature's protein Lego set.
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Amino Acid Sequence↗
Biomedical subjects
S Das
Publications and source records attributed to S Das.
Survey of neuromuscular injuries to the patient and surgeon during urologic laparoscopic surgery.
OBJECTIVES: Laparoscopy may be complicated by neuromuscular injuries, both to the patient and to the surgeon. We used a survey to estimate the incidence of these injuries during urologic laparoscopic surgery, to assess risk factors for these injuries, and to determine preventive measures. METHODS: A survey of neuromuscular injuries associated with laparoscopy submitted to 18 institutions in the United States was completed by 18 attending urologists from 15 institutions. RESULTS: From among a total of 1651 procedures, there were 46 neuromuscular injuries in 45 patients (2.7%), including abdominal wall neuralgia (14), extremity sensory deficit (12), extremity motor deficit (8), clinical rhabdomyolysis (6), shoulder contusion (4), and back spasm (2). Neuromuscular injuries were twice as common with upper retroperitoneal as with pelvic laparoscopy (3. 1% versus 1.5%). Among patients with neuromuscular injuries, those with rhabdomyolysis were heavier (means 91 versus 80 kg) and underwent longer procedures (means 379 versus 300 minutes), and those with motor deficits were older (means 51 versus 42 years of age). Of the surgeons, 28% and 17% reported frequent neck and shoulder pain, respectively. CONCLUSIONS: Although not common, neuromuscular injuries during laparoscopy do contribute to morbidity. Abdominal wall neuralgias, injuries to peripheral nerves, and joint or back injuries likely occur no more frequently than during open surgery, but risk of rhabdomyolysis may be increased. Positioning in a partial rather than full flank position may reduce the incidence of some injuries. Measures to reduce neuromuscular strain on the surgeon during laparoscopy should be considered.
Abdominal Muscles↗
Complement activation in heart diseases. Role of oxidants.
Increasing evidence demonstrated that atherosclerosis is an immunologically mediated disease. Myocardial ischemia/reperfusion injury is accompanied by an inflammatory response contributing to reversible and irreversible changes in tissue viability and organ function. Three major components are recognized as the major contributing factors in reperfusion injury. These are: (1) molecular oxygen; (2) cellular blood elements (especially the neutrophils); and (3) components of the activated complement system. The latter two often act in concert. Endothelial and leukocyte responses are involved in tissue injury, orchestrated primarily by the complement cascade. Anaphylatoxins and assembly of the membrane attack complex contribute directly and indirectly to further tissue damage. Tissue damage mediated by neutrophils can be initiated by complement fragments, notably C5a, which are potent stimulators of neutrophil superoxide production and adherence to coronary artery endothelium. The complement cascade, particularly the alternative pathway, is activated during myocardial ischemia/reperfusion. Complement fragments such as the anaphylatoxins C3a and C5a, are produced both locally and systematically, and the membrane attack complex is deposited on cell membranes and subsequent release of mediators such as histamine and platelet activating factor (PAF), thereby causing an increase in vascular permeability with concomitant manifestation of cellular edema. Complement increases the expression of CD18 on the neutrophils and increases P-selectin expression on the surface of the endothelium. Mitochondria may be a source of molecules that activate complements during ischemia/reperfusion injury to myocardium, providing therewith a stimulus for infiltration of polymorphonuclear leukocytes. Tissue salvage can be achieved by depletion of complement components, thus making evident a contributory role for the complement cascade in ischemia/reperfusion injury. The complexities of the complement cascade provide numerous sites as potential targets for therapeutic interventions designed to modulate the complement response to injury. The latter is exemplified by the ability of soluble form of complement receptor 1 (sCR1) to decrease infarct size in in vitro models of ischemia/reperfusion injury. The mechanism(s) that initiates complement activation is not clearly known, although loss of CD59 (protectin) from cells compromised by ischemia/reperfusion may contribute to direct damage of the coronary vascular bed by the terminal complement complex. Therapeutic approaches to ischemia/reperfusion injury in general, and especially those involving complements, are at the very beginning and their potential benefits have still to be adequately evaluated. It may be noted that complement activation has both positive and negative effects and, therefore, might be modulated rather than abruptly blunted.
Animals↗
Signal transduction mechanism in human neutrophil: comparative study between the zeta and beta-protein kinase isotypes.
Role of protein kinase C (PKC) isotypes in the regulation of neutrophil function are not clearly known. In the present study we purified the beta-PKC and zeta-PKC isotypes from human neutrophil. Both the isotypes are immunoreactive only to their respective antibodies. Zeta-PKC was further confirmed by RT-PCR using specific primer. Co-factor requirements for both the kinases were found to be different when DG and ceramide were used as second messenger. Selective substrate specificities were determined for both beta and zeta-PKC using isotype specific pseudosubstrates viz., [Ser25]PKC[19-31] and [Ser119]PKC[113-130] respectively. Endogenous protein phosphorylation by purified beta-PKC and zeta-PKC showed their functional differences in neutrophil. Beta-PKC phosphorylated 13, 15, 19, 33, 36, 47, 80 and 92 kDa proteins and zeta-PKC phosphorylated 19, 22, 42, 47, 75 and 87 kDa proteins, only exception was the phosphorylation of 47 kDa protein which had been phosphorylated by both the kinases. Differences in phosphorylation between beta-PKC and zeta-PKC clearly indicate the selective role for these PKC isotypes in the activation sequences of neutrophil.
Base Sequence↗
On the roles of heterochromatin and euchromatin in meiosis in drosophila: mapping chromosomal pairing sites and testing candidate mutations for effects on X-Y nondisjunction and meiotic drive in male meiosis.
Mapping of pairing sites involved in meiotic homolog disjunction in Drosophila has led to conflicting hypotheses about the nature of such sites and the role of heterochromatin in meiotic pairing. In the female-specific distributive system, pairing regions appear to be exclusively heterochromatic and map to broad regions encompassing many different sequences. In male meiosis, autosomal pairing sites appear to be distributed broadly within euchromatin but to be absent from heterochromatin, whereas the X-pairing site maps in the centric heterochromatin. The X site has been shown to coincide with the intergenic spacer (IGS) repeats within the rDNA arrays shared between the X and Y. It has not been clear whether the heterochromatic location of this pairing site has any significance. A novel assay for genic modifiers of X-Y chromosome pairing was developed based on the intermediate nondisjunction levels observed in males whose X chromosome lacks the native pairing site but contains two transgenic insertions of single rDNA genes. This assay was used to test several mutations in Su(var) (Suppressor of position effect variegation), PcG (Polycomb-Group) recombination defective, and repair-defective genes. No strong effects on disjunction were seen. However, the tests did uncover several mutations that suppress or enhance the meiotic drive (distorted X-Y recovery ratio) that accompanies X-Y pairing failure.
Animals↗
Somatic segregation errors predominantly contribute to the gain or loss of a paternal chromosome leading to uniparental disomy for chromosome 15.
Paternal uniparental disomy (UPD) for chromosome 15 (UPD15), which is found in approximately 2% of Angelman syndrome (AS) patients, is much less frequent than maternal UPD15, which is found in 25% of Prader-Willi syndrome patients. Such a difference cannot be easily accounted for if 'gamete complementation' is the main mechanism leading to UPD. If we assume that non-disjunction of chromosome 15 in male meiosis is relatively rare, then the gain or loss of the paternal chromosome involved in paternal and maternal UPD15, respectively, may be more likely to result from a post-zygotic rather than a meiotic event. To test this hypothesis, the origin of the extra chromosome 15 was determined in 21 AS patients with paternal UPD15 with a paternal origin of the trisomy. Only 4 of 21 paternal UPD15 cases could be clearly attributed to a meiotic error. Furthermore, significant non-random X-chromosome inactivation (XCI) observed in maternal UPD15 patients (p < 0.001) provides indirect evidence that a post-zygotic error is also typically involved in loss of the paternal chromosome. The mean maternal and paternal ages of 33.4 and 39.4 years, respectively, for paternal UPD15 cases are increased as compared with normal controls. This may be simply the consequence of an age association with maternal non-disjunction leading to nullisomy for chromosome 15 in the oocyte, although the higher paternal age in paternal UPD15 as compared with maternal UPD15 cases is suggestive that paternal age may also play a role in the origin of paternal UPD15.
Adult↗
Preformed laryngeal masks.
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Equipment Design↗
Herpes simplex virus type 1 as a cause of widespread intracorneal blistering of the lower limbs.
Herpes simplex virus (HSV) infections often manifest as acute self-limiting eruptions of grouped vesicles, which have a tendency to recur. Common manifestations include that of gingivostomatitis, vulvovaginitis, recurrent erythema multiforme, herpetic whitlow, and eczema herpeticum. We report a case of HSV-1 presenting as a symmetrical intracorneal blistering eruption involving the lower limbs in a patient with no previous history of herpes simplex infection.
Blister↗
Thyroid hormone-induced morphological differentiation and maturation of astrocytes are mediated through the beta-adrenergic receptor.
The molecular mechanisms associated with thyroid hormone (TH)-induced maturation of astrocytes have been studied using primary cultures. We have previously demonstrated that unlike normal astrocyte cultures, hypothyroid cultures fail to differentiate from flat polygonal cells with epithelioid morphology into mature process-bearing cells with stellate morphology. Addition of TH to the hypothyroid cells reverses the effect, and astrocytes transform into stellate cells. The beta-adrenergic receptor (beta-AR) agonist isoproterenol (ISP) has a similar effect, whereas simultaneous addition of the beta-adrenergic antagonist propranolol blocks the differentiation induced by TH or ISP. Addition of TH or ISP to hypothyroid cultures is also associated with a decrease in the level of filamentous cytoskeletal (F(i)) actin and an increase in the level of actin mRNA. Although addition of propranolol inhibited the decline in the level of F(i) actin in the TH- or ISP-supplemented cells as well as the induction of actin mRNA by TH, it partially inhibited the ISP-induced actin mRNA in these cultures. The hormone-induced maturation appears to be selectively regulated through the beta(2)-AR. The overall results indicate that the beta-adrenergic system plays an obligatory role in promoting TH-induced differentiation and maturation of astrocytes and in regulating the hormone-induced expression of actin and its intracellular organization in a way conducive to the morphological differentiation of the cells.
Actins↗
Hepatic damage caused by chronic arsenic toxicity in experimental animals.
OBJECTIVE: Noncirrhotic fibrosis of the liver is common in subjects chronically consuming ground water geologically contaminated with arsenic, but the mechanism of the hepatic fibrosis is not known. Because lipid peroxidation has been implicated in the development of several other forms of hepatic fibrosis, including iron and copper overload, we have explored the roles of oxidative stress and lipid peroxidation in the causation of hepatic fibrosis in a murine model of chronic arsenic toxicity. METHODS: Male BALB/c mice were given drinking water contaminated with arsenic (3.2 mg/L) or arsenic-free (<0.01 mg/L, control) ad libitum. Mice were sacrificed at 3, 6, 9, 12, and 15 months for examination of hepatic histology and assays of hepatic reduced glutathione content, lipid peroxidation, enzymes of the antioxidant defense system, and membrane-bound sodium/potassium ATPase (Na+/K+ ATPase). RESULTS: After 12 months of arsenic feeding, the liver weights increased significantly as did serum aspartate aminotransferase and alanine aminotransferase. After 6 months of arsenic feeding, hepatic glutathione and the enzymes glucose-6-phosphate dehydrogenase and glutathione peroxidase were significantly lower than those of the control group. Hepatic catalase activity was significantly reduced at 9 months in the arsenic-fed group, while glutathione-S-transferase and glutathione reductase activities were also significantly reduced at 12 and 15 months. Plasma membrane Na+/K+ ATPase activity was reduced after 6 months while lipid peroxidation increased significantly after 6 months of arsenic feeding. Liver histology remained normal for the first 9 months, but showed fatty infiltration after 12 months of arsenic feeding. Histologic evidence of fibrosis was observed after 15 months. CONCLUSION: We have demonstrated hepatic fibrosis due to long-term arsenic toxicity in an animal model. Initial biochemical evidence of hepatic membrane damage, probably due to reduction of glutathione and antioxidant enzymes, may be seen by 6 months. Continued arsenic feeding resulted in fatty liver with serum aminotransferase and alanine aminotransferase elevated at 12 months and hepatic fibrosis at 15 months. The murine model is proposed as relevant to epidemic human toxicity in areas of arsenic contamination.
Alanine Transaminase↗
The use of bone morphogenetic protein gene therapy in craniofacial bone repair.
Bone morphogenetic proteins (BMPs) are capable of inducing endochondral bone formation when applied on biologic carriers in numerous mammalian in vivo assay systems. Bone morphogenetic protein gene therapy is also currently being developed to promote osteogenesis for clinical indications such as spinal fusions, craniofacial bone loss, and osteoporosis. In this study, critical-sized mandibular defects were treated with a control adenoviral vector (Ad-beta-gal), a BMP-2 adenoviral vector (Ad-BMP-2), or a BMP-9 adenoviral vector (Ad-BMP-9). Gross tissue examination, radiographic analysis, and histologic analysis demonstrated significant bony healing in the BMP treated groups compared to controls. Osteogenesis was limited to the bony defect, without extension into the surrounding soft tissues. The study suggests that with further development, BMP gene therapy may be potentially useful for repair of bony defects in the craniofacial region.
Animals↗
Infectious keratitis in climatic droplet keratopathy.
PURPOSE: To report the ulcer characteristics, microbiologic data, and outcome of infectious keratitis associated with climatic droplet keratopathy (CDK), suggesting that CDK is a predisposing factor for infectious keratitis. METHODS: Medical records of 32 patients (34 eyes) in whom infectious keratitis was seen in association with CDK were retrospectively reviewed. Data were collected regarding the nature of CDK lesions, infiltrate characteristics, organisms isolated, and outcome. RESULTS: CDK was peripheral in 16 (47.1%) eyes, central in 8 (23.5%), and diffuse in 10 (29.4%). The CDK lesions were nodular and elevated in all eyes. The infiltrate was adjacent to the CDK lesions in 28 eyes (82.4%). The infiltrate size (widest dimension) ranged 2-6 mm in 18 eyes (52.9%) and was >6 mm in 7 (20.5%). The infiltrate was full thickness in 15 eyes (44.1%) and was involving up to the middle third of the corneal stroma in another 18 (52.8%). Hypopyon was seen in all. Bacteria were commonly isolated. Staphylococcus epidermidis (six eyes) and Streptococcus pneumoniae (five eyes) were the common bacteria isolated. Resolution with medical treatment was seen in 20 (58.8%) eyes. CONCLUSIONS: CDK is a predisposing factor for infectious keratitis. Treatment should be considered for advanced and nodular lesions, even if they are peripheral, to prevent infectious keratitis.
Adult↗
Prevention of carcinogen-induced mouse skin papilloma by whole fruit aqueous extract of Momordica charantia.
The anticarcinogenic effect of aqueous extract of fruit of Momordica charantia (bitter gourd), which is widely used as a vegetable in India, was studied in a two-step skin carcinogenesis model in mice. The possible mode of action was also investigated. Oral administration of the fruit extract was found to have an adverse effect on the general health and lifespan of the animals when used at a high concentration. But when this dose was reduced by half, the test extract afforded protection from the development of skin tumour and increased life expectancy. Carcinogen-induced lipid peroxidation in liver and DNA damage in lymphocytes were found to be reduced following treatment with Momordica. The fruit extract was found to significantly activate the liver enzymes glutathione-S-transferase, glutathione peroxidase and catalase (P < 0.001), which showed a depression following exposure to the carcinogen. The results suggest a preventive role of water-soluble constituents of M. charantia fruit during carcinogenesis, which is mediated possibly by their modulatory effect on enzymes of the biotransformation and detoxification system of the host.
9,10-Dimethyl-1,2-benzanthracene↗
Borrelia burgdorferi gene expression in vivo and spirochete pathogenicity.
Borrelia burgdorferi spirochetes that do not cause arthritis or carditis were developed and used to investigate Lyme disease pathogenesis. A clonal isolate of B. burgdorferi N40 (cN40), which induces disease in C3H/HeN (C3H) mice, was repeatedly passaged in vitro to generate nonpathogenic spirochetes. The passage 75 isolate (N40-75) was infectious for C3H mice but did not cause arthritis or carditis, and spirochetes were at low levels or absent in the joints or hearts, respectively. N40-75 could, however, cause disease in severe combined immunodeficient (SCID) mice, suggesting that the response in immunocompetent mice prevented effective spirochete dissemination and the subsequent development of arthritis and carditis. Administration of immune sera at 4 days after spirochete challenge aborted N40-75, but not cN40, infection in SCID mice. A B. burgdorferi genomic expression library was differentially probed with sera from cN40- and N40-75-infected mice, to identify genes that may not be effectively expressed by N40-75 in vivo. N40-75 was defective in the up-regulation of several genes that are preferentially expressed during mammalian infection, including dbpAB, bba64, and genes that map to the cp32 family of plasmids. These data suggest that adaptation and gene expression may be required for B. burgdorferi to effectively colonize the host, evade humoral responses, and cause disease.
Animals↗
Use of RNA arbitrarily primed-PCR fingerprinting to identify Vibrio cholerae genes differentially expressed in the host following infection.
Evidence suggests that a repertoire of Vibrio cholerae genes are differentially expressed in vivo, and regulation of virulence factors in vivo may follow a different pathway. Our work was aimed at characterization of in vivo-grown bacteria and identification of genes that are differentially expressed following infection by RNA arbitrarily primed (RAP)-PCR fingerprinting. The ligated rabbit ileal loop model was used. The motility of in vivo-grown bacteria increased by 350% over that of in vitro-grown bacteria. Also, the in vivo-grown cells were more resistant to killing by human serum. By using the RAP-PCR strategy, five differentially expressed transcripts were identified. Two in vitro-induced transcripts encoded polypeptides for the leucine tRNA synthatase and the 50S ribosomal protein, and the three in vivo-induced transcripts encoded the SucA and MurE proteins and a polypeptide of unknown function. MurE is a protein involved in the peptidoglycan biosynthetic pathway. The lytic profiles of in vivo- and in vitro-grown cells suspended in distilled water were compared; the former was found to be slightly less sensitive to lysis. Ultrathin sections of both cells observed under the transmission electron microscope revealed that in contrast to the usual wavy discontinuous membrane structure of the in vitro-grown cells, in vivo-grown cells had a more rigid, clearly visible double-layered structure. The V. cholerae murE gene was cloned and sequenced. The sequence contained an open reading frame of 1,488 nucleotides with its own ribosome-binding site. A plasmid containing the murE gene of V. cholerae was transformed into V. cholerae 569B, and a transformed strain, 569BME, containing the plasmid was obtained. Ultrathin sections of 569BME viewed under a transmission electron microscope revealed a slightly more rigid cell wall than that of wild-type 569B. When V. cholerae 569B and 569BME cells were injected separately into ligated rabbit ileal loops, the transformed cells had a preference for growth in the ileal loops versus laboratory conditions.
Amino Acid Sequence↗
Mutational analysis of mammalian translation initiation factor 5 (eIF5): role of interaction between the beta subunit of eIF2 and eIF5 in eIF5 function in vitro and in vivo.
Eukaryotic translation initiation factor 5 (eIF5) interacts with the 40S initiation complex (40S-eIF3-AUG-Met-tRNA(f)-eIF2-GTP) to promote the hydrolysis of ribosome-bound GTP. eIF5 also forms a complex with eIF2 by interacting with the beta subunit of eIF2. In this work, we have used a mutational approach to investigate the importance of eIF5-eIF2beta interaction in eIF5 function. Binding analyses with recombinant rat eIF5 deletion mutants identified the C terminus of eIF5 as the eIF2beta-binding region. Alanine substitution mutagenesis at sites within this region defined several conserved glutamic acid residues in a bipartite motif as critical for eIF5 function. The E346A,E347A and E384A,E385A double-point mutations each caused a severe defect in the binding of eIF5 to eIF2beta but not to eIF3-Nip1p, while a eIF5 hexamutant (E345A,E346A, E347A,E384A,E385A,E386A) showed negligible binding to eIF2beta. These mutants were also severely defective in eIF5-dependent GTP hydrolysis, in 80S initiation complex formation, and in the ability to stimulate translation of mRNAs in an eIF5-dependent yeast cell-free translation system. Furthermore, unlike wild-type rat eIF5, which can functionally substitute for yeast eIF5 in complementing in vivo a genetic disruption of the chromosomal copy of the TIF5 gene, the eIF5 double-point mutants allowed only slow growth of this DeltaTIF5 yeast strain, while the eIF5 hexamutant was unable to support cell growth and viability of this strain. These findings suggest that eIF5-eIF2beta interaction plays an essential role in eIF5 function in eukaryotic cells.
Alanine↗
Investigation of the increased incidence of gonorrhoea diagnosed in GUM clinics in England, in 1994-6.
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Female↗
Use of bone morphogenetic protein-9 gene therapy to induce spinal arthrodesis in the rodent.
OBJECT: Bone morphogenetic proteins (BMPs) have been shown to have significant osteoinductive activity in numerous in vitro and in vivo assay systems, and BMP-2 and BMP-7 are currently being evaluated in human clinical studies. In the spinal region, BMPs have been shown to promote spinal arthrodesis at a higher rate than autologous bone alone. The delivery of BMPs via direct or ex vivo gene therapy techniques is also currently being evaluated and has shown promise in several mammalian models. The present study was designed to evaluate the efficacy of the use of direct, percutaneous BMP-9 adenoviral gene therapy to promote spinal fusion in the rodent. METHODS: Each animal was injected with 7.5x10(8) pfu of a BMP-9 adenoviral vector in the lumbar paraspinal musculature and allowed to survive 16 weeks. Computerized tomography studies and histological analysis demonstrated massive bone induction at the injection sites, clearly leading to solid spinal arthrodesis, without evidence of pseudarthroses, nerve root compression, or systemic side effects. CONCLUSIONS: The results of this study strongly support the advancement of BMP gene therapy techniques toward clinical use.
Adenoviridae↗