601
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Khan SA, Sekulski JM, Erickson BW. Peptide models of protein metastable binding sites: competitive kinetics of isomerization and hydrolysis. Biochemistry 1986; 25:5165-71. [PMID: 3768339 DOI: 10.1021/bi00366a027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
alpha 2-Macroglobulin and the complement components C3 and C4 each contain a metastable binding site that is essential for covalent attachment. Two cyclic peptides are useful models of these unusual protein sites. Five-membered lactam 1 (CH3CO-Gly-Cys-Gly-Glu-Glp-Asn-NH2) contains an internal residue of pyroglutamic acid (Glp). Fifteen-membered thiolactone 2 (CH3CO-Gly-Cys-Gly-Glu-Glu-Asn-NH2 15-thiolactone) contains a thiol ester bond between Cys-2 and Glu-5. These isomeric hexapeptides are spontaneously interconverted in water. Competing with the two isomerization reactions are three reactions involving hydrolysis of 1 and 2. These five processes were found to occur simultaneously under physiologic conditions (phosphate-buffered saline, pH 7.3, 37 degrees C). Best estimates of the five rate constants for these apparent first-order reactions were obtained by comparing the observed molar percentages of peptides 1-4 with those calculated from a set of exponential equations. Both isomerization reactions (ring expansion of 1 to 2, k1 = 6.4 X 10(-5) s-1; ring contraction of 2 to 1, k-1 = 69 X 10(-5) s-1) proceeded faster than any of the hydrolysis reactions: alpha-cleavage of 1 with fragmentation to form dipeptide 3 (k2 = 3.3 X 10(-5) s-1), gamma-cleavage of 1 with ring opening to yield mercapto acid 4 (k3 = 0.35 X 10(-5) s-1), and hydrolysis of 2 with ring opening to give 4 (k4 = 1.9 X 10(-5) s-1). The isomerization rate ratio (k1/k-1 = 10.9) agreed with the isomer ratio at equilibrium (1:2 = 11 starting from 1 and 10 starting from 2). The alpha/gamma regioselectivity ratio (k2/k3 = 9.7) for hydrolysis of the internal Glp residue of 1 was consistent with results for model tripeptides. Part of the chemistry of the protein metastable binding sites can be explained by similar isomerization and hydrolysis reactions.
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602
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Koepsel RR, Murray RW, Khan SA. Sequence-specific interaction between the replication initiator protein of plasmid pT181 and its origin of replication. Proc Natl Acad Sci U S A 1986; 83:5484-8. [PMID: 3461445 PMCID: PMC386311 DOI: 10.1073/pnas.83.15.5484] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The replication of the pT181 plasmid is dependent on the plasmid-encoded initiator protein RepC. We have previously shown that RepC protein has sequence-specific endonuclease and topoisomerase-like activities. In this paper we demonstrate that this initiator protein has sequence-specific DNA-binding properties. Based on filter binding of plasmid restriction fragments, RepC protein specifically recognizes only the pT181 origin region. Using DNase I and neocarzinostatin "footprinting" techniques, we show that RepC protein specifically binds to a 32-base-pair sequence within the origin that is part of the initiator cistron. Using dimethyl sulfate as a chemical probe, we have identified the purine residues that interact with the initiator protein. The features of the DNA region that interacts with RepC protein include sequences with the potential to form Z DNA and/or hairpin structures. The specific DNA-protein interaction at the origin may be critical in the initiation of pT181 DNA replication by RepC protein in association with other host initiation proteins.
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603
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Ishimura K, Incefy GS, Wang JG, Komiyama T, Heimer EP, Felix AM, Unson CG, Khan SA, Erickson BW. Antigenic specificity of a rabbit antiserum raised against the 15-28 segment of thymosin alpha 1. Mol Immunol 1986; 23:701-7. [PMID: 2432409 DOI: 10.1016/0161-5890(86)90080-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Thymosin alpha 1, an acidic 28-residue peptide, enhances immune function. We have described a radioimmunoassay for this thymic factor based on a rabbit antiserum raised against a thymosin alpha 1-(15-28) conjugate (Incefy et al., J. Immun. Meth. 1986, in press). The detailed antigenic specificity of this antiserum was determined by measuring the ability of synthetic segments and analogues of thymosin alpha 1 and related peptides to compete with radioiodinated Ac-Tyr-thymosin alpha 1-(15-28) in this radioimmunoassay. The antiserum bound segments Ac-(1-28), (15-28), (20-28) and (21-28) with nearly equal efficiency but failed to bind segments Ac-(1-10), (11-20), (19-24) and (22-28). Thus, the major immunoreactive site seen by the antiserum is the COOH-terminal segment (21-28) (Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH). Immunoreactivity of (21-28) was nearly abolished when the carboxylate groups of Glu-21, Glu-27 and Asn-28 were omitted separately. The antiserum bound to prothymosin alpha and thymosin alpha 11, which lack the alpha-carboxylate group of Asn-28, with 0.9 and 0.2%, respectively, of the efficiency of thymosin alpha 1. But it bound nonspecifically to parathymosin alpha, which contains the internal segment . . . -Glu-Val-Val-Glu-Glu-Glu-Glu-Asn- . . . . Residues Glu-21, Glu-27 and Asn-28 of thymosin alpha 1 may be important features of the antigenic site through their ability to induce helical structure, through the ability of their negatively charged carboxylate groups to bind to specific sites on the antibody or both.
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604
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Khan SA, Beres WP. Projection operator method for resonances in repulsive core potentials. Phys Rev C Nucl Phys 1986; 33:2028-2032. [PMID: 9953384 DOI: 10.1103/physrevc.33.2028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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605
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Abstract
The complete nucleotide sequence of the enterotoxin B gene from Staphylococcus aureus, as well as the 5' and 3' flanking regions, was determined. Starting from an ATG initiator codon, an open reading frame encoded the enterotoxin B precursor that consisted of 266 amino acids (Mr, 31,400). The 5' terminal portion of the gene encodes a signal peptide 27 amino acids long. The deduced amino acid sequence matched, with a few exceptions, the published amino acid sequence of enterotoxin B. The structural gene was flanked on the 5' side by a promoter-like sequence and on the 3' side by a palindromic structure followed by a thymine-rich region that resembled a transcription termination signal. Downstream from the entB gene were two overlapping open reading frames corresponding to 134 and 185 amino acids in the opposite orientation. The signal sequence of the enterotoxin B precursor resembled that of other secreted proteins found in other bacteria.
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606
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Abstract
A retrospective study correlating the blood groups of 141 patients with bladder cancer showed that patients with blood group A had lower grade tumors with lower mortality rates, and those with blood group O(H) had higher grade tumors and higher mortality rates.
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607
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Khan SA, Vatsia SK, Smith NL. A cushingoid man with pneumaturia, diarrhea. Hosp Pract (Off Ed) 1985; 20:32M-32N, 32P. [PMID: 3932387 DOI: 10.1080/21548331.1985.11703183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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608
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Koepsel RR, Murray RW, Rosenblum WD, Khan SA. The replication initiator protein of plasmid pT181 has sequence-specific endonuclease and topoisomerase-like activities. Proc Natl Acad Sci U S A 1985; 82:6845-9. [PMID: 2995991 PMCID: PMC390784 DOI: 10.1073/pnas.82.20.6845] [Citation(s) in RCA: 97] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Initiation of pT181 DNA replication specifically requires the plasmid-encoded RepC protein. Here we demonstrate that highly purified RepC protein has sequence-specific endonuclease and topoisomerase-like activities. A maximum sequence of 127 base pairs containing the pT181 origin of replication is required for nicking-closing by RepC protein. RepC introduces a single strand break within the pT181 origin. The nick site has been shown by DNA sequencing to lie between nucleotides 70 and 71 in the bottom strand of the DNA within the origin sequence. This nick site probably corresponds to the start site of pT181 replication. The results presented here suggest that, unlike most other plasmids, pT181 replicates by a rolling circle mechanism.
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609
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Khan SA, Beres WP. 28Si. Phys Rev C Nucl Phys 1985; 32:871-876. [PMID: 9952915 DOI: 10.1103/physrevc.32.871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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610
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Ranelli DM, Jones CL, Johns MB, Mussey GJ, Khan SA. Molecular cloning of staphylococcal enterotoxin B gene in Escherichia coli and Staphylococcus aureus. Proc Natl Acad Sci U S A 1985; 82:5850-4. [PMID: 3898073 PMCID: PMC390651 DOI: 10.1073/pnas.82.17.5850] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
We have cloned the Staphylococcus aureus entB gene in Escherichia coli, using pBR322 as the vector plasmid; however, no detectable staphylococcal enterotoxin B (SEB) was produced by the E. coli clones. When the entB gene was placed downstream from the strong lambda phage promoter, PR, SEB was synthesized at readily detectable levels in E. coli. Interestingly, mature SEB was almost exclusively present in the cytoplasmic fraction. The SEB precursor was found associated with the cell membrane. The entB gene was introduced back into S. aureus, and the clones were shown to produce SEB. The entB gene has been located to a 2.1-kilobase-pair region. Maxam-Gilbert sequencing of a part of the entB gene yielded a DNA sequence that corresponds to the known amino acid sequence of SEB. Southern hybridization experiments showed that the entB gene was present on identical restriction fragments in the chromosomes of SEB-producer strains. The entB gene is absent from SEB-nonproducer strains.
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611
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Koepsel RR, Murray RW, Rosenblum WD, Khan SA. Purification of pT181-encoded repC protein required for the initiation of plasmid replication. J Biol Chem 1985; 260:8571-7. [PMID: 2989292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The plasmid pT181 of Staphylococcus aureus consists of 4437 base pairs and encodes resistance to tetracycline. Initiation of pT181 replication specifically requires the plasmid-encoded repC protein. An in vitro system has been shown to carry out semiconservative replication of pT181 and its derivative plasmids (Khan, S A., Carleton, S. M., and Novick, R. P. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 4902-4906). We have used this replication assay to isolate repC protein, which was purified to near homogeneity. The repC gene was cloned into the pKJB825 plasmid that contains the phage lambda temperature-sensitive repressor gene, cI857, and the rightward promoter, PR. Upon temperature induction, Escherichia coli clones containing the recombinant plasmid overproduced repC protein, which was purified in significant quantities. The molecular weight of repC protein under denaturing conditions is 38,000, which is consistent with the size predicted from the DNA sequence data. Presence of repC protein was absolutely essential for the initiation of replication of pT181 and its derivatives in vitro.
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612
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Khan SA, Smith NL, Gonder M, Ravo B, Siddharth P. Gangrene of male external genitalia in a patient with colorectal disease. Anatomic pathways of spread. Dis Colon Rectum 1985; 28:519-22. [PMID: 4017814 DOI: 10.1007/bf02554101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This is the report of a patient with gangrene of the skin and subcutaneous tissue of the scrotum and base of the penis secondary to diverticulitis of the sigmoid colon. Due to high mortality in such patients, the early, rapid, and radical debridement of all devitalized tissues and prompt recognition of the source of sepsis is of utmost importance. Computed tomography (CT) scanning facilitates delineating the extent of disease. Anatomy of the perineal body and pathways of spread are discussed.
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613
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Khan SA, Jayachandran S, Desai PG, Smith N. Contralateral drainage of primary hydrocele. Int Urol Nephrol 1985; 17:171-6. [PMID: 4086233 DOI: 10.1007/bf02082490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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614
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Hameed MA, Khan SA. Effects of sudden exposure to high altitude on pulmonary functions. J PAK MED ASSOC 1985; 35:175-8. [PMID: 3928931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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615
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616
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Abstract
The stage-specific influence of the secretions from rat seminiferous tubules on the LH-stimulated testosterone production by rat Leydig cells in vitro was studied. The spent media from incubated seminiferous tubules (SMST) from stages VII-VIII of the seminiferous epithelial cycle caused about 50% inhibition of the LH-dependent testosterone production by a crude preparation of rat interstitial cells. The SMST from other stages had no effect on testosterone production. Mixed tubules of unidentified stages gave an intermediate response. When SMST from ten different stages of the seminiferous wave were compared, the most pronounced inhibitory activity was found in stages VI and VIII-XI, while SMST from stages I, VII and XIII-XIV had no inhibitory effects on interstitial cell testosterone production. No stimulation was found in this system. Prolonged incubation of the interstitial cells with SMST from stages VIII-XI resulted in loss of inhibitory activity after 12 h of incubation. Maximum inhibitory activity was noted after 3 h of incubation. The inhibitory activity of the SMST from stages VIII-XI was retained after prolonged dialysis, and was unchanged after heating the medium at 60 degrees C for 1 h. The activity did not seem to be due to the presence of proteolytic enzymes, since it was not influenced by addition of protease inhibitors. SMST from stages VIII-XI had no effect on the metabolism of [3H]testosterone added to the interstitial cell preparations. No inhibitory effect was observed when Leydig cells were incubated with dibutyryl cAMP instead of LH, suggesting an early influence on the LH-receptor-adenylate cyclase chain of events.(ABSTRACT TRUNCATED AT 250 WORDS)
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617
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Dush MK, Sikela JM, Khan SA, Tischfield JA, Stambrook PJ. Nucleotide sequence and organization of the mouse adenine phosphoribosyltransferase gene: presence of a coding region common to animal and bacterial phosphoribosyltransferases that has a variable intron/exon arrangement. Proc Natl Acad Sci U S A 1985; 82:2731-5. [PMID: 3921964 PMCID: PMC397639 DOI: 10.1073/pnas.82.9.2731] [Citation(s) in RCA: 138] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We have determined the nucleotide sequence of a functional mouse adenine phosphoribosyltransferase (APRT) gene and its cDNA. The amino acid sequence of the enzyme is deduced from an open reading frame in the cDNA and predicts a protein with a molecular weight of 19,560. The protein coding region of the gene is approximately 2 kilobases, and it is composed of five exons and four introns. While the body of the gene is 53% G + C, the 200 nucleotides upstream from the ATG translation start codon are 66% G + C and contain three copies of the sequence C-C-G-C-C-C. The mouse APRT enzyme shares a homologous 20-amino acid sequence with mouse, hamster, and human hypoxanthine phosphoribosyltransferases (HPRTs) and several bacterial phosphoribosyltransferases. This sequence has previously been shown to be a likely catalytic domain in human HPRT and Escherichia coli glutamine phosphoribosyltransferase. Because of the similarities in function of these proteins, both eukaryotic and prokaryotic, it is not unexpected that they should exhibit one or more regions of homology, particularly at the 5-phosphoribosyl-1-pyrophosphate and purine binding sites, especially if they are related via a common evolutionary lineage. This homologous sequence is interrupted by a single intron in the mouse APRT gene and by two introns in the mouse HPRT gene. Furthermore, the positions of both introns in the HPRT sequence are different from that of the single intron in the corresponding sequence of the APRT gene.
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618
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Ravo B, Khan SA, Ger R, Mishrick A, Soroff HS. Unusual extraperitoneal presentations of diverticulitis. Am J Gastroenterol 1985; 80:346-51. [PMID: 3158193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extraperitoneal presentations of complicated diverticular disease are unusual. The initial clinical presentations of these extraperitoneal manifestations have been described in the perineum, scrotum, buttock, hip, joints, thigh, lower extremities, mediastinum, and neck. These presentations render the diagnosis difficult and may lead to the delay of the proper therapy. The purpose of this report is to call attention to these unusual extraperitoneal presentations of complicated diverticular disease to describe the routes of spread and to present a case in point. Reviewing the literature, we have concluded that these unusual presentations occur more commonly in women and the elderly, that a delayed diagnosis significantly increases the mortality rate, and that the most common site of an extraperitoneal presentation is in the area of the hip.
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619
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620
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Smith NL, Ravo B, Soroff HS, Khan SA. Successful fibrinolytic therapy for superior vena cava thrombosis secondary to long-term total parenteral nutrition. JPEN J Parenter Enteral Nutr 1985; 9:55-7. [PMID: 3918204 DOI: 10.1177/014860718500900155] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thrombosis of the superior vena cava and other major central veins is an unusual and infrequent complication of total parenteral nutrition. When it does occur, it may be life threatening and prompt therapy is indicated. A case of superior vena cava thrombosis secondary to an indwelling Broviac catheter for long-term parenteral nutrition is presented, which was successfully treated with Streptokinase with reestablishment of flow through the catheter and veins.
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621
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Abstract
The role of blood group ABO(H) surface isoantigen measurement in bladder cancer is discussed. The basis for this test is examined and an attempt is made to place the current status of this test in proper perspective.
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622
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623
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Hannon R, Butler CP, Day CL, Khan SA, Quitoriano LA, Butler AM, Meredith LA. Alcohol use and cognitive functioning in men and women college students. Recent Dev Alcohol 1985; 3:241-52. [PMID: 3975451 DOI: 10.1007/978-1-4615-7715-7_19] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Two studies of the relationship between alcohol consumption and cognitive functioning in men and women college students are presented. Study 1 showed several predicted relationships of decreased cognitive performance on various tests with increased quantity of alcohol per occasion and total lifetime consumption in both women and men. Study 2a was designed to replicate study 1, but the pattern of relationship of cognitive and consumption variables was quite different, e.g., increased cognitive performance was associated with increased quantity per occasion for several tests in males. Study 2b was designed to demonstrate reversibility of the negative effects of consumption on cognition by randomly assigning half of the subjects to abstain for two weeks. Reversibility was not demonstrated. Difficulties in studying these effects in college students are discussed.
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624
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Hameed MA, Khan SA. Peak expiratory flow rate in healthy Pakistani adults. J PAK MED ASSOC 1984; 34:363-4. [PMID: 6441023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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625
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Srinivas V, Chiu KW, Khan SA. Ureteral narrowing without urinary symptoms: two cases. Hosp Pract (Off Ed) 1984; 19:145-6, 148. [PMID: 6438128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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626
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Hameed MA, Khan SA, Chaudhry KS, Khan SJ. Haemoglobin A2 levels--reference values in healthy Pakistani adults. J PAK MED ASSOC 1984; 34:339-44. [PMID: 6441850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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627
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Novick RP, Adler GK, Projan SJ, Carleton S, Highlander SK, Gruss A, Khan SA, Iordanescu S. Control of pT181 replication I. The pT181 copy control function acts by inhibiting the synthesis of a replication protein. EMBO J 1984; 3:2399-405. [PMID: 6499834 PMCID: PMC557700 DOI: 10.1002/j.1460-2075.1984.tb02146.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
pT181 is a fully sequenced 4.4-kb 20 copy Tcr plasmid from Staphylococcus aureus. Its replication system involves a unique unidirectional origin embedded in the coding sequence for a plasmid-determined protein, RepC, that is required for initiation. When joined to a 55 copy carrier plasmid, pE194, pT181 excludes autonomous isologous replicons by inhibiting their replication. Two types of spontaneous pT181 copy mutants have been isolated, one that eliminates sensitivity to this inhibition and another that does not. A spontaneous 180-bp deletion, delta 144, eliminates both the inhibitory activity and sensitivity to it. This deletion increases copy number by 50-fold and RepC production by at least 10-fold. It is located directly upstream from the repC coding sequence and the deletion-bearing plasmid supports the replication of inhibitor-sensitive plasmids in cells containing active inhibitor. This effect is probably due to the overproduction of RepC by the delta 144 plasmid. On the basis of these results, it is suggested that RepC synthesis is negatively controlled by an inhibitor that is encoded directly upstream from the repC coding sequence and acts as a tareget set in the same region. It is likely, therefore, that pT181 replication rate is determined by the level of RepC.
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628
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Beksac MS, Khan SA, Eliasson R, Skakkebaek NE, Sheth AR, Diczfalusy E. Evidence for the prostatic origin of immunoreactive inhibin-like material in human seminal plasma. Int J Androl 1984; 7:389-97. [PMID: 6526511 DOI: 10.1111/j.1365-2605.1984.tb00796.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Inhibin is defined as a gonadal peptide exerting an inhibitory effect on the secretion of follicle-stimulating hormone (FSH) by the pituitary. Using a radioimmunoassay (RIA) procedure developed for a homogeneous inhibin-like peptide with a molecular weight of 14 000 daltons isolated from human seminal plasma, immunoreactive inhibin-like matrial (ILM) was quantitated in serum, urine and semen of men in order to investigate its origin. Vasectomy did not result in a significant reduction in seminal plasma ILM. Determination of ILM immunoreactivity in ejaculates form normal men and semen samples characterized by prostate-rich and prostate-deficient secretions, indicated high levels of ILM in the prostatic secretions. Immunoreactive ILM levels estimated in different fractions of split ejaculates from normal men paralleled those of zinc and acid phosphatase activity and were significantly higher in fractions representing prostatic secretions compared to those representing the secretions of seminal vesicles. Estimation of ILM in semen, serum and urine from bilaterally gonadectomized men showed that immunoreactive ILM levels remained high after gonadectomy. It is concluded that the bulk of the immunoreactive ILM present in the semen, blood and urine of men is not secreted by the testes. The principal site of origin of this material, at least in semen, appears to be the prostate.
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629
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Khan SA, Desai PG, Jayachandran S, Smith N. Fascial pathways of extravasation of blood in lower abdomen following angiography-anatomic and clinical correlation. Angiology 1984; 35:672-5. [PMID: 6497050 DOI: 10.1177/000331978403501009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The extravasation of urine following traumatic rupture of the urethra or periurethral abscess is well known to clinicians. The extravasation of blood following angiography, in the same anatomical space, is rare. Extravasation of fluids in the lower abdomen, groin and external genitalia follows distinct anatomical pathways. This case illustrates the anatomical pathways and emphasizes their clinical importance.
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630
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631
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Khan SA. We need a more human perspective. Int Nurs Rev 1984; 31:82-4. [PMID: 6565000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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632
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Khan SA, Siddiqui AQ, Siddiqui MA. Lithium-induced changes in brain amino acids, alpha-ketoacids & transaminases. Indian J Med Res 1984; 79:514-9. [PMID: 6490115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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633
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Khan SA, Qazi MH, Diczfalusy E. The significance of in vitro bioassays for the estimation and characterization of human luteinizing hormone (LH). J Endocrinol Invest 1984; 7 Suppl 3:1-22. [PMID: 6399296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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634
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635
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636
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Abstract
pT181 is a naturally occurring Staphylococcus aureus plasmid, encoding inducible resistance to tetracycline. The plasmid has a copy number of about 20 per cell, and belongs to the incompatibility group inc3. The complete nucleotide sequence of pT181 has been determined and consists of 4437 bp. The nucleotide sequence contains 69.8% A-T and 30.2% G-C pairs. pT181 was found to contain four open reading frames capable of coding for polypeptides containing more than 50 amino acids. All the putative polypeptides are coded by one strand. The molecular weights of the four putative polypeptides are (in daltons): A, 37,500; B, 35,000; C, 23,000, and D, 18,000. Polypeptide A corresponds to the repC protein, earlier shown to be specifically required for pT181 replication. Polypeptide B (and possibly polypeptide D) are involved in tetracycline resistance. No role has yet been established for polypeptide C; deletion of the coding sequence for the C polypeptide has no detectable effect on any property of the pT181 plasmid. A region consisting of about 1200 bp contains information for the replication and copy number control of this plasmid. The sequencing results are discussed in relation to the replication properties and tetracycline resistance associated with the pT181 plasmid.
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637
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Khan SA, Diczfalusy E. Heterologous radioimmunoassays for monkey gonadotrophins. I. Assessment of the reagents proposed for the assay of FSH. Acta Endocrinol (Copenh) 1983; 104:15-22. [PMID: 6312719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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638
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Abstract
A functional mouse adenine phosphoribosyltransferase (APRT) gene was identified and cloned by screening a mouse sperm genomic DNA library in lambda Charon 4A. The probe utilized for screening was a restriction fragment encoding much of the hamster APRT gene. Six recombinants that hybridized with the probe were identified, and after digestion with restriction enzymes EcoRI and PvuII revealed three different patterns of digestion for each enzyme. Of the six recombinants, five representing two of the restriction patterns possessed transforming activity. A sixth recombinant, which has a unique restriction pattern, lacks transforming activity but hybridizes well with hamster APRT coding sequences and is a possible candidate for a pseudogene. We used three criteria for conclusively identifying the mouse APRT genes. (1) DNA from the recombinant lambda phage hybridizes with DNA encoding hamster APRT. (2) The recombinant lambda phages and their DNAs transform mouse, hamster and human APRT- cells to the APRT+ phenotype. (3) The hamster and human transformants display APRT activity that migrates with a mobility characteristic of mouse APRT and not of hamster or human. A 3.1-kb EcoRI-SphI restriction fragment which retains transforming activity has been subcloned into the plasmid pBR328. Comparison of restriction enzyme sites with those contained in a mouse APRT cDNA, coupled with loss of transforming activity after enzyme digestion, indicates that the mouse APRT gene is larger than 1.8 kb and contains at least three introns.
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639
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Hu KN, Khan SA, Smith NL. Bilateral pelvic lymphadenectomy from a lower abdominal transverse skin incision and pararectal approach. Surg Gynecol Obstet 1983; 156:443-8. [PMID: 6836460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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640
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Shenbagamurthi P, Baffi R, Khan SA, Lipke P, Pousman C, Becker JM, Naider F. Structure-activity relationships in the dodecapeptide alpha factor of Saccharomyces cerevisiae. Biochemistry 1983; 22:1298-304. [PMID: 6340736 DOI: 10.1021/bi00274a047] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ten analogues of His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr, the dodecapeptide alpha factor of Saccharomyces cerevisiae, were synthesized by conventional solution phase techniques and purified by using high-performance liquid chromatography. The dodecapeptide was also synthesized attached at its carboxyl terminus to poly(ethylene oxide), a macromolecular protecting group. Analogues in which Lys6 or His1 was modified exhibited high biological activity as evidenced by their ability to elicit aberrant morphologies in a cells of S. cerevisiae. These results suggest that neither a free alpha-amine nor a protonatable side chain at position 6 is necessary for biological activity of the dodecapeptide alpha factor. Although Ala2- and Phe2-dodecapeptides were not biologically active, they competed with the natural alpha factor and several active analogues. Thus binding of the alpha factor is not sufficient to elicit a biological response; it appears that the side chain in position 2 is critical for triggering morphological alterations in a cells.
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641
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Abstract
Human tissues were incubated in vitro with radiolabeled amino acids to determine whether plasma apolipoproteins are synthesized in human kidney. Subsequently, tissue extracts were screened with antisera directed against apolipoprotein E (apo E), apolipoprotein B (apo B), apolipoprotein AI (apo AI), and bulk apolipoproteins of high density lipoprotein (HDL). Newly synthesized apo E, but not apo AI or apo B, was identified in kidney and adrenal cortex. Estimates of relative rates of apo E synthesis in vitro suggest that a substantial portion of adrenal and kidney protein synthesis is committed to apo E synthesis. The relative rate of apo E synthesis was 4-6 times greater in kidney cortex than in kidney medulla. Analysis of immunoreactive apo E showed that kidney and adrenal apo E species have the same electrophoretic mobility in NaDodSO4/polyacrylamide gels as does plasma apo E. Further characterization by high resolution two-dimensional gel analysis indicated that the isoforms of newly synthesized kidney and adrenal apo E correspond to specific isoforms of plasma apo E. These findings suggest that apolipoproteins arising from peripheral tissues may play an important role in lipid transport and metabolism.
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642
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Sasvary DH, Tzakis AG, Smith NL, Khan SA, Soroff HS. Randomized prospective study of the comparative efficacy of spectinomycin and gentamicin in urinary tract infections. Urol Int 1983; 38:135-7. [PMID: 6223430 DOI: 10.1159/000280877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A prospective, randomized study was undertaken in 32 hospitalized patients with urinary tract infections to compare the efficacy of spectinomycin versus gentamicin. Spectinomycin was found to be of equal efficacy if not more efficacious in eradicating Escherichia coli, Klebsiella and Proteus mirabilis in our patient population. No significant side-effects were noted. A review of the literature with emphasis on the use of spectinomycin in infections other than anogenital gonorrhea is made.
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643
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Arslan M, Khan SA, Qazi MH. Effect of an LHRH analogue on testicular function in the immature monkey (Macaca mulatta). Int J Androl 1982; 5:607-12. [PMID: 6819235 DOI: 10.1111/j.1365-2605.1982.tb00294.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Response of the immature monkey testis to an LHRH analogue, D-Ser-(TBu)6-EA10-LHRH, has been assessed by measuring testicular androgen production in the immature rhesus monkey. Administration of the analogue (2.5 micrograms X 2 daily) for 5 days induced a significant increase in testicular testosterone compared with untreated animals. The response of the control and the LHRH-agonist treated monkey testis to gonadotrophin (hCG) was assessed by in vitro androgen production. Whereas the testicular tissue from LHRH analogue primed monkeys responded to in vitro stimulation of hCG, no significant increase in androgen production was observed when testicular tissue from untreated animals was incubated with the gonadotrophin. The present data suggest a functional differentiation of the immature monkey testis following the LHRH analogue treatment.
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644
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Khan SA, Smith NL, Hu KN. New perspectives in diagnosis and management of thrombophlebitis of the superficial dorsal vein of the penis. J Dermatol Surg Oncol 1982; 8:1063-7. [PMID: 7153404 DOI: 10.1111/j.1524-4725.1982.tb01095.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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645
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Abstract
Three cases of rectal bleeding within a series of 120 transrectal prostatic biopsies are reported. The precipitating factor was the presence of hemorrhoids which were unsuspected prior to prostatic biopsy. Rectal bleeding in these patients was arrested by ballon tamponade with a 24 French Foley catheter. In situ monitoring of the rectal Foley catheter was discontinued when no further rectal bleeding was ascertained. There were no complications due to this simple, safe, and effective technique. When hemorrhoids are suspected, preliminary proctoscopy aids and alerts surgeons to choose alternative routes to the prostatic bed.
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646
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Khan SA, Erickson BW. An equilibrium model of the metastable binding sites of alpha 2-macroglobulin and complement proteins C3 and C4. J Biol Chem 1982; 257:11864-7. [PMID: 6181062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Two cyclic structures, the 15-membered thiolactone A and the 5-membered lactam P, have been proposed for the metastable binding sites of the serum proteins C3, C4, and alpha 2-macroglobulin. Neither structure alone adequately explains two unusual reactions of these sites, namely, covalent attachment to nucleophiles with liberation of a thiol group and spontaneous hydrolysis (autolysis) of an internal peptide bond. The metastable binding sites of these proteins were modeled with the 15-membered thiolactone 1 (Khan, S. A., and Erickson, B. W. (1981) J. Am. Chem. Soc. 103, 7374-7376) and the isomeric 5-membered lactam 2, which contains an internal pyroglutamyl (Glp) residue. Under physiologic conditions (phosphate-buffered saline, pH 7.3, 37 degrees C), thiolactone 1 and lactam 2 exist in dynamic equilibrium. Since the molar ratio of 2/1 is 11:1 at equilibrium, lactam 2 is 15 kcal/mol more stable than thiolactone 1. The activation energy for isomerization of 1 into 2 is 18 kcal/mol, which is about 5 kcal/mol lower than that for hydrolysis of the acyclic thiolester N,S-diacetyl-L-cysteine methylamide. Part of the chemistry of the metastable binding sites can be explained by an analogous equilibrium between protein structures A and B. Lactam B may be a key intermediate in the biosynthesis of thiolactone A. Under denaturating conditions, thiolactone A could either bind covalently to a receptive surface or isomerize into lactam B, which could undergo spontaneous hydrolysis of the Glu-Glp peptide bond.
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647
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Khan SA, Erickson BW. An equilibrium model of the metastable binding sites of alpha 2-macroglobulin and complement proteins C3 and C4. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33643-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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648
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Khan SA, Smith NL, Hu KN, Dailey BD. An unusual case of delayed rectosigmoid compression by pelvic mass following cystectomy: report of a case. Dis Colon Rectum 1982; 25:720-2. [PMID: 7128377 DOI: 10.1007/bf02629548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A rare case of rectosigmoid compression by an enormous obscure pelvic mass after cystectomy is reported. Pelvic collections in the form of abscess, hematoma, lymphocele, and urinoma are not uncommon in the early postoperative period following pelvic surgery. However, delayed appearance of a benign pelvic mass as a late complication of surgery is very rare. Localized pelvic masses discovered years after cystectomy for bladder tumor may lead to an erroneous clinical impression of local recurrence of the primary neoplasm. Differential diagnosis of common pelvic masses, diagnostic studies, and treatment are discussed.
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649
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Khan SA, Purow E. Leiomyosarcoma of the colon with hepatic metastases. Am J Proctol Gastroenterol Colon Rectal Surg 1982; 33:14-6, 22. [PMID: 7137330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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650
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Khan SA, Adler GK, Novick RP. Functional origin of replication of pT181 plasmid DNA is contained within a 168-base-pair segment. Proc Natl Acad Sci U S A 1982; 79:4580-4. [PMID: 6956881 PMCID: PMC346718 DOI: 10.1073/pnas.79.15.4580] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We have used a recently developed in vitro replication system from Staphylococcus aureus to determine the origin and direction of replication of pT181 plasmid DNA. The origin was located to within 168 base pairs by two methods: (i) sequential labeling of restriction endonuclease fragments after synchronous initiation in vitro in the presence of various amounts of dideoxy-TTP and (ii) by constructing in vitro deletions of pT181 DNA close to the origin of replication and testing for their ability to replicate in vitro pT181 plasmid was found to replicate unidirectionally and anticlockwise, as the map is conventionally drawn. The nucleotide sequence of the region containing the origin of replication has been determined and found to be partially or entirely contained within the coding sequence for the repC protein, which is uniquely required for pT181 plasmid replication. Preliminary evidence suggesting that pT181 replicates by a rolling circle mechanism is discussed.
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