1226
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Khan S. Importance of nutrition for female population of reproductive age. J PAK MED ASSOC 1983; 33:264-5. [PMID: 6422077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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1227
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Garud MA, Saraiya UB, Lulla M, Khan S, Paraskar M, Daftary D. Cytology screening program in an urban and rural community in India. Review of a ten-year experience. Acta Cytol 1983; 27:429-31. [PMID: 6576543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
An approach to the detection and management of early cervical cancer and its precursors utilizing basic and inexpensive equipment and a team of workers comprising physicians, cytotechnicians and social workers in an urban and rural community in India is described. In the ten-year period from 1970 to 1979, a total of 26,217 patients had Papanicolaou smears taken; 104 patients had histologically proven carcinoma in situ or microinvasive cancer of the cervix in which the clinical findings at the time of cell study did not indicate malignancy. The policy of management based on judicial conservatism and essential radicalism gave good survival rates and minimum morbidity.
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1228
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Khan S, Berg HC. Isotope and thermal effects in chemiosmotic coupling to the membrane ATPase of Streptococcus. J Biol Chem 1983; 258:6709-12. [PMID: 6222047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We measured rates of ATP synthesis by the proton-translocating ATPase of the motile Streptococcus strain V4051. Starved cells were energized artificially by exposing their membranes to a variable electrical potential difference (internal medium negative) and a fixed pH difference (internal medium alkaline). The initial rates of ATP synthesis increased exponentially with protonmotive force. The results were the same in D2O and H2O; there was no solvent isotope effect. At a fixed protonmotive force, the rates were strongly dependent on temperature, as expected for a reaction with a large enthalpy of activation. At a different protonmotive force, the rates varied with temperature in an identical fashion; there was no change in the enthalpy of activation. We conclude that protonation-deprotonation steps are not rate limiting and that the protons that cross the membrane drive ATP synthesis by mass action. The transmembrane electric field acts by changing the concentrations of the reactants, not by changing the configuration of the enzyme-substrate complex.
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1229
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Khan S, Berg HC. Isotope and thermal effects in chemiosmotic coupling to the membrane ATPase of Streptococcus. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32275-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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1230
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Trewhella J, Anderson S, Fox R, Gogol E, Khan S, Engelman D, Zaccai G. Assignment of segments of the bacteriorhodopsin sequence to positions in the structural map. Biophys J 1983; 42:233-41. [PMID: 6871370 PMCID: PMC1329232 DOI: 10.1016/s0006-3495(83)84391-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Specific amino acid sequence segments have been assigned to locations in the structural map of bacteriorhodopsin using two-dimensional neutron diffraction data and a model building analysis. Models are constructed computationally by building specific regions of the amino acid sequence as alpha helices and then positioning the helices on axes indicated by the density map of Henderson and Unwin (Nature [Lond.]. 1975, 257:28-32). Neutron diffraction data were collected from samples of stacked, oriented "native" purple membranes as well as purple membranes containing different kinds of deuterated amino acids. Models differing in the assignments of helices to specific axes and in rotations of the helices about those axes were tested against the neutron data using a weighted residual factor to rank the models. This residual factor was calculated between observed and predicted intensity differences for pairs of data sets. Using this approach, a small set of related models has been found that predicts the observed intensity changes between five independent data sets. These models are inconsistent with the proposed locations of the retinal chromophore and the carboxyl terminus and with any of the previously proposed models for bacteriorhodopsin.
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1231
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Khan S, Berg HC. Isotope and thermal effects in chemiosmotic coupling to the flagellar motor of Streptococcus. Cell 1983; 32:913-9. [PMID: 6831561 DOI: 10.1016/0092-8674(83)90076-4] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The torque generated by the flagellar motor of Streptococcus strain V4051 has been determined from rates of rotation of cells tethered by a single flagellum in media of different isotopic composition and temperature. Starved cells were energized artificially with either a potassium diffusion potential or a pH gradient. The torque increased linearly with protonmotive force. Identical results were obtained in media made with D2O or H2O; there was no solvent isotope effect. At a fixed protonmotive force, the torque was approximately constant over a temperature range of 4 degrees -38 degrees C. In cells chemotactically inert to changes in cytoplasmic pH, the motor turned counterclockwise when protons moved inward and clockwise when they moved outward. We conclude that the motor is a reversible engine driven by simple acid-base dissociation. A detailed model is discussed.
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1232
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1233
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Pandya KP, Khan S. Effect of n-octane and n-nonane administration on alkaline phosphatase activity in tissues of female rats. Biochem Pharmacol 1982; 31:201-3. [PMID: 7059361 DOI: 10.1016/0006-2952(82)90211-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Studies on alkaline phosphatase were conducted in albino rats exposed to n-octane or n-nonane for 2 and 7 days; there was an increase in alkaline phosphatase activity of liver, spleen and bone marrow. Increase in spleen alkaline phosphatase activity persisted up to 42 days after single dose of n-octane or n-nonane. Pretreatment with protein synthesis inhibitors, cycloheximide or ethionine removed this observed increase of alkaline phosphatase activity in liver and spleen.
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1234
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DiMauro S, Miranda AF, Khan S, Gitlin K, Friedman R. Human muscle phosphoglycerate mutase deficiency: newly discovered metabolic myopathy. Science 1981; 212:1277-9. [PMID: 6262916 DOI: 10.1126/science.6262916] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Muscle phosphoglycerate mutase activity was decreased (5.7 percent of the lowest control value) in a 52-year-old man with intolerance for strenuous exercise and recurrent pigmenturia since adolescence. All of the other enzymes of glycolysis had normal activities, and glycogen concentration was normal. Electrophoretic, heat lability, and mercury inhibition studies showed that the small residual activity in the patient's muscle was represented by the brain (BB) isoenzyme of phosphoglycerate mutase, suggesting a genetic defect of the M subunit which predominates in normal muscle. The prevalence of the BB isoenzyme in other tissues, including muscle culture, may explain why symptoms were confined to muscle.
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1235
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Ghose JC, Chaudhury A, Khan S, Kumar P. Risk of advanced heart block during surgery in patients with bifascicular block. THE JOURNAL OF THE ASSOCIATION OF PHYSICIANS OF INDIA 1981; 29:435-8. [PMID: 7319997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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1236
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Khan S, Pandya KP. Biochemical studies on the toxicity of n-octane and n-nonane. ENVIRONMENTAL RESEARCH 1980; 22:271-276. [PMID: 6250816 DOI: 10.1016/0013-9351(80)90139-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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1237
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Khan S, Macnab RM. The steady-state counterclockwise/clockwise ratio of bacterial flagellar motors is regulated by protonmotive force. J Mol Biol 1980; 138:563-97. [PMID: 6774099 DOI: 10.1016/s0022-2836(80)80018-0] [Citation(s) in RCA: 119] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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1238
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Khan S, Macnab RM. Proton chemical potential, proton electrical potential and bacterial motility. J Mol Biol 1980; 138:599-614. [PMID: 6774100 DOI: 10.1016/s0022-2836(80)80019-2] [Citation(s) in RCA: 110] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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1239
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Khan S, Feldman M, Hollander VP. The biological significance of estradiol receptor binding to DNA. Cancer Res 1980; 40:1050-3. [PMID: 7357535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
MTW9-D, a rat mammary tumor derived from MTW9 by chronic administration of the dopamine antagonist drug R33,812 shows ovariectomy-induced regression (OIR). MTW9-MtT is also a variant of MTW9, grown by coimplantation of a mammosomatotropic tumor MtTW10, but it does not show OIR. However, when the mammosomatotropic tumor (MtT) is resected, the tumor regresses and shows rapid OIR; implantation of MtT into animals bearing MTW9-D prevents OIR following drug withdrawal. The estradiol receptor (ER) from MTW9-D cytosol binds to DNA-cellulose significantly more than that from MTW9-MtT. After MtT resection, the mammary tumor ER binds to DNA-cellulose, as well as ER from MTW9-D, whereas implantation of MtT into animals bearing MTW9-D decreases ER binding to DNA-cellulose. The significance of these findings in relation to possible clinical application is discussed.
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1240
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Diamond EJ, Khan S, Paul MA, Koprak S, Hollander VP. Chronic administration of pharmacological doses of ovine prolactin decreases hormone disappearance rate. Endocrinology 1980; 106:952-8. [PMID: 7353554 DOI: 10.1210/endo-106-3-952] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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1241
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Ghosh CK, Khan S. Heterocyclic Systems; 91. Reaction of 4-Oxo-4H-1-benzopyran-3-carboxaldehydes(3-Formylchromones) with 1,2-Diamines. SYNTHESIS-STUTTGART 1980. [DOI: 10.1055/s-1980-29176] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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1242
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Hollander VP, Khan S. The ether-catalyzed dissociation rate of estradiol-receptor complex distinguishes between hormone-sensitive and resistant rat mammary tumors. JOURNAL OF STEROID BIOCHEMISTRY 1980; 12:131-4. [PMID: 6252377 DOI: 10.1016/0022-4731(80)90262-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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1243
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Khan S, Mukhtar H, Pandya KP. n-Octane and n-nonane induced alterations in xenobiotic metabolising enzyme activities and lipid peroxidation of rat liver. Toxicology 1980; 16:239-45. [PMID: 7423533 DOI: 10.1016/0300-483x(80)90120-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
After 2 and 7 days on n-octane and n-nonane administration (intraperitoneally) to female albino rats, alterations in the levels of hepatic xenobiotic metabolising enzyme activities and TBA reactants were observed. Fifty to eighty per cent reduction in the specific activities of benzo[a]pyrene hydroxylase, benzphetamine-N-demethylase, p-nitroanisole-O-demethylase and glutathione-S-transferase were observed. Cytochrome P-450 and free sulfhydryl contents of liver were also decreased significantly after 7 days treatment on n-octane and n-nonane. A 2- and 3- fold increase in liver lipid peroxidation estimated as TBA reactants was observed in the animals treated for 2 or 7 days with n-octane or n-nonane.
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1244
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Khan S, Haust MD. Variations in the aortic origin of intercostal arteries in man. Anat Rec (Hoboken) 1979; 195:545-52. [PMID: 507408 DOI: 10.1002/ar.1091950313] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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1245
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Abstract
The relationship between the activity of the cystic fibrosis serum ciliary dyskinesia factor, detected by the rabbit tracheal bioassay, and clinical status of the patient has been investigated in children, 1-24 years old, with cystic fibrosis. No significant correlation was found between the amount of serum factor activity and age, clinical status assessed by the Schwachman score, pulmonary function (vital capacity, functional residual capacity, total lung capacity, residual volume, maximum breathing capacity, maximal midinspiratory flow, and maximal midexpiratory flow) or blood gas levels (pCO2, pO2). The activity showed no significant relationship to serum galactosyltransferase activity in children with cystic fibrosis.
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1246
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Srivastava RC, Khan S, Shankar U, Pandya KP. Distribution of Fe59 in benzene and iomex treated rats. Arch Toxicol 1979; 42:43-9. [PMID: 454184 DOI: 10.1007/bf00351823] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The distribution of Fe59 in plasma and blood at various time intervals has been studied in control, benzene and iomex administered, and anemic rats. A significant difference between control and benzene, and iomex treated animals was observed in the rate of reappearance of Fe59 in blood circulation. The accumulation of Fe59 in various organs was noted at the end of 48 h. A significant increase in the radio-iron content was observed in bone marrow, spleen and liver of benzene and iomex treated rats as compared to those of control rats.
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1247
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El-Domeiri AA, Khan S. Tumours of the parotid gland: the significance of tumour size and facial nerve involvement. Clin Oncol (R Coll Radiol) 1979; 5:17-24. [PMID: 421384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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1248
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1249
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DeLap RJ, Rush MG, Zouzias D, Khan S. Isolation and preliminary characterization of the small circular DNA present in African green monkey kidney (BSC-1) cells. Plasmid 1978; 1:508-21. [PMID: 107539 DOI: 10.1016/0147-619x(78)90008-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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1250
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Khan S, Macnab RM, DeFranco AL, Koshland DE. Inversion of a behavioral response in bacterial chemotaxis: explanation at the molecular level. Proc Natl Acad Sci U S A 1978; 75:4150-4. [PMID: 360210 PMCID: PMC336069 DOI: 10.1073/pnas.75.9.4150] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Certain cheU mutants of Salmonella show inverted chemotactic behavior, being repelled by attractants and attracted by repellents. Such a dramatic change in behavioral pattern would seem at first glance to require drastic and complex alterations in the sensory processing system. In fact, the behavior can be explained by a simple shift in the level of a response regulator and the subtle effects of this shift on flagellar function. Flagella can exist in either a left-handed or a right-handed structure depending on applied torsion. Wild-type cells swim smoothly by counterclockwise rotation of a left-handed helical bundle and tumble when the motors briefly reverse to clockwise rotation (normal random motility). The cheU mutation causes a shift in response regulator level relative to the critical threshold value, resulting in extended clockwise operation so that the flagella are fully converted to the right-handed helical form. These cells therefore swim smoothly by clockwise rotation of a right-handed bundle and tumble when the motor briefly reverses to counterclockwise rotation (inverse random motility). Thus, tumbling is associated with brief reversals and not with a particular sense of rotation. A wild-type cell, with its steady-state response regulator level placing it initially in normal random motility, will swim smoothly on addition of attractant, whereas a cheU mutant with inverse random motility will tumble given the same stimulus. The phenomenon illustrates the profound behavioral consequences that can result from a single mutation in a key gene.
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