101
|
Smith TC, Robinson SC. Effect of H+ on the kinetics of Na+-dependent amino acid transport in Ehrlich ascites tumor cells: evidence for H+ as an alternative substrate. J Cell Physiol 1981; 109:507-16. [PMID: 6274883 DOI: 10.1002/jcp.1041090317] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effects of H+ on the kinetics of alpha-aminoisobutyric acid (AIB) influx in Ehrlich ascites tumor cells have been investigated at different external Na+ concentrations. Elevation of [H+] in the presence of both high (154 mEq/l) and low (10 mEq/l) external Na+ leads to decreases in the maximum influx (Jmax) and increases in the apparent Michaelis-Menten constant (Km) for influx of AIB. In the virtual absence of external Na+ (0.96 +/- 0.04 mEq/l), alterations in [H+] are without measurable effect on AIB flux. Furthermore, addition of AIB (10 mM) to cell suspensions (pH 5.90) stimulates H+ uptake by the cells in either the presence or absence of Na+. The data are consistent with two kinetic models for Na+-dependent amino acid transport: an order bireactant (Na+-binding necessary before AIB binding) system or a random bireactant system. Both models require that H+ serve as an alternative substrate for Na+. The consistency of the models was tested by fit to data from the present study (not used to evaluate the kinetic parameters) and by prediction of the pH dependence of Na+-dependent amino acid transport compared to earlier studies.
Collapse
|
102
|
Dockhorn RJ, Smith TC. Use of a chemically defined hypoallergenic diet (Vivonex in the management of patients with suspected food allergy/intolerance. ANNALS OF ALLERGY 1981; 47:264-6. [PMID: 6895446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The use of a hypoallergenic diet was evaluated in patients suspected of food allergy/intolerance. Symptom scores for one week of regular diet were compared with symptom scores while taking Vivonex. Results indicate that patients had fewer symptoms while on Vivonex than during the preceding week of normal diet.
Collapse
|
103
|
Smith TC. Liver, gall bladder and pancreas. THE PRACTITIONER 1981; 225:597-598. [PMID: 7279847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
|
104
|
Smith TC, Robinson SC. Variable coupling of active Na+ + K+ transport in Ehrlich ascites tumor cells: regulation by external Na+ and K+. J Cell Physiol 1981; 106:407-18. [PMID: 7194348 DOI: 10.1002/jcp.1041060310] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
105
|
Smith TC, Robinson SC. The membrane potential of Ehrlich ascites tumor cells: an evaluation of the null point method. J Cell Physiol 1981; 106:399-406. [PMID: 7217220 DOI: 10.1002/jcp.1041060309] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
|
106
|
Smith TC. Mefenamic acid in urinary retention. BMJ : BRITISH MEDICAL JOURNAL 1981; 282:618. [PMID: 6162504 PMCID: PMC1504448 DOI: 10.1136/bmj.282.6264.618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
107
|
Smith TC, Herlihy JT, Robinson SC. The effect of the fluorescent probe, 3,3'-dipropylthiadicarbocyanine iodide, on the energy metabolism of Ehrlich ascites tumor cells. J Biol Chem 1981; 256:1108-10. [PMID: 7451493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The fluorescent dye, 3,3'-dipropylthiadicarbocyanine iodide, is frequently used to estimate the cell membrane potential of small cells. We have tested the effects of this dye on glycolytic rate, O2 consumption, and cellular ATP content in Ehrlich ascites tumor cells. Addition of the dye to steady state cells in the absence of glucose induces a rapid depletion (half-time approximately equal to 5 min) of cellular ATP, which is secondary to a 76% inhibition of O2 consumption. Aerobic glycolysis is stimulated by 76%. Valinomycin produces an additional stimulation of acid production. Our findings indicate that this fluorescent dye alters energy metabolism of Ehrlich ascites tumor cells. The response is consistent with primary inhibition of oxidative phosphorylation.
Collapse
|
108
|
Smith MT, Smith TC. The unsteady model. An alternative approach to nonlinear pharmacokinetics. Eur J Clin Pharmacol 1981; 20:387-98. [PMID: 7286050 DOI: 10.1007/bf00615410] [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: 01/24/2023]
Abstract
In this paper an alternative approach to nonlinear pharmacokinetics modelling has been developed from first principles. This "Unsteady Model" is able to describe the situation whereby one or more independent drugs and their metabolites compete for free attachment sites in liver, tissue, red blood cells etc. The Unsteady model collapses to well-known existing models viz: Michaelis-Menten, Langmuir tissue binding and the linear compartment models, under certain well-defined, limiting conditions. The Unsteady model and its collapse to existing models is derived mathematically and illustrated with simulations. For several reasons the Unsteady model would appear to have many advantages and wide application.
Collapse
|
109
|
Abstract
In most breathing circuits, ventilation of a patient requires some device to occlude the expiratory limb during inflation. Usually one or another modification of a mushroom exhalation valve is employed. Such valves are found in the Bourns Bear 1 ventilator, the Bennett MA-1 and MA-2 ventilators, and the Emerson postoperative ventilator, as well as in the Frumen valve for manual ventilation. Recently, the authors observed a defect that might cause permanent occlusion, raising the patient's airway pressure to the level of the limiting safety pop-off and effectively applying a prolonged Valsalva maneuver without ventilation. The defect responsible for this malfunction was a half-centimeter laceration in the mushroom valve. Although the defect occurred on a Bourns Bear 1 ventilator, the authors were able to reproduce it on other ventilators of different manufacturers.
Collapse
|
110
|
Wyndham CR, Arnsdorf MF, Levitsky S, Smith TC, Dhingra RC, Denes P, Rosen KM. Successful surgical excision of focal paroxysmal atrial tachycardia. Observations in vivo and in vitro. Circulation 1980; 62:1365-72. [PMID: 7438373 DOI: 10.1161/01.cir.62.6.1365] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A 41-year-old man had chronic, recurrent, drug-resistant paroxysmal right atrial tachycardia. Electrophysiologic studies revealed features suggesting atrial reentrance, including induction and termination of tachycardia with rapid atrial pacing and atrial extrastimuli. Endocardial catheter mapping localized the origin of tachycardia to the right atrial appendage. Intraoperative epicardial mapping refined the localization to the posterolateral rim of the appendage. The appendage was excised and the tachycardia was permanently cured. Microelectrode studies on the excised tissue revealed an inducible rhythm localized to a small area of the atrial endocardium, characterized by rapid pacing induction, rhythmicity generated from a suprathreshold afterdepolarization, low maximum diastolic potential, low overshoot potential and a smooth transition from phase 4 to phase 0, suggesting triggered automaticity. This is the first observation in man of probable triggerable atrial automaticity, which may be a direct counterpart of the clinical arrhythmia. The successful surgical outcome indicates that a focal atrial tachycardia can be excised in selected patients.
Collapse
|
111
|
Silverman DG, LaRossa DD, Barlow CH, Bering TG, Popky LM, Smith TC. Quantification of tissue fluorescein delivery and prediction of flap viability with the fiberoptic dermofluorometer. Plast Reconstr Surg 1980; 66:545-53. [PMID: 7208667 DOI: 10.1097/00006534-198010000-00007] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Quantitative fluorescence assessment with the fiberoptic dermofluorometer has been introduced to overcome the inadequacies of ultraviolet inspection following intravenous administration of fluorescein. Initial applications in the pedicle flap of the rat have indicated that this method can predict flap viability with reproducible precision and accuracy. This minimally invasive technique should be of considerable assistance to the evaluation of hypoperfused states in laboratory and clinical situations.
Collapse
|
112
|
Smith TC, Robinson SC. The effect of the fluorescent probe, 3,3'-dipropylthiodicarbocyanine iodide, on the membrane potential of Ehrlich ascites tumor cells. Biochem Biophys Res Commun 1980; 95:722-7. [PMID: 7417285 DOI: 10.1016/0006-291x(80)90845-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
113
|
Smith TC, Vernon KD. Correlation of the effect of Ca+2 on Na+ and K+ permeability and membrane potential of Ehrlich ascites tumor cells. J Cell Physiol 1979; 98:359-69. [PMID: 570569 DOI: 10.1002/jcp.1040980212] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The effect of Ca+2 on the transport and intracellular distribution of Na+ and K+ in Ehrlich ascites tumor cells was investigated in an effort to establish the mechanism of Ca+2-induced hyperpolarization of the cell membrane. Inclusion of Ca+2 (2 mM) in the incubation medium leads to reduced cytoplasmic concentrations of Na+, K+ and Cl- in steady cells. In cells inhibited by ouabain, Ca+2 causes a 41% decrease in the rate of net K+ loss, but is without effect on the rate of net Na+ accumulation. Net K+ flux is reduced by 50%, while net Na+ flux is unchanged in the transport-inhibited cells. The membrane potential of cells in Ca+2-free medium (-13.9 +/- 0.8 mV) is unaffected by the addition of ouabain. However, the potential of cells in Ca+2-containing medium (-23.3 +/- 1.2 mV) declines in one hour after the addition of ouabain to values comparable to those of control cells (-15.2 +/- 0.7 mV). The results of these experiments are consistent with the postulation that Ca+2 exerts two effects on Na+ and K+ transport. First, Ca+2 reduces the membrane permeability to K+ by 25%. Second, Ca+2 alters the coupling of the Na/K active transport mechanism leading to an electrogenic hyperpolarization of the membrane.
Collapse
|
114
|
Smith TC, Levinson C. Ehrlich ascites tumor cell surface labeling and kinetics of glycocalyx release. JOURNAL OF SUPRAMOLECULAR STRUCTURE 1979; 12:115-25. [PMID: 544932 DOI: 10.1002/jss.400120109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ehrlich ascites tumor cells spontaneously release cell surface material (glycocalyx) into isotonic saline medium. Exposure of these cells to tritium-labeled 4,4'-diisothiocyano-1,2-diphenylethane-2,2'-disulfonic acid (3H2DIDS) at 4 degrees C leads to preferential labeling of the cell surface coat. We have combined studies of the kinetics of 3H2DIDS-label release, the effects of enzymatic treatment, and cell electrophoretic mobility to characterize the 3H2DIDS-labeled components of the cell surface. Approximately 73% of the cell-associated radioactivity is spontaneously released from the cells after 5 h at 23 degrees C. The kinetics of release is consistent with the first-order loss of two fractions; a slow (tau 1/2 = 360 min) component representing 33% of the radioactivity and a fast (tau 1/2 = 20 min) component representing 26%. The remaining 14% of the labile binding may reflect mechanically induced surface release. Trypsin (1 microgram/ml) also removes approximately 73% of the labeled material within 30 min and converts the kinetics of release to that of a single component (tau 1/2 = 5.5 min). The specific activity (SA) of material released by trypsin immediately after labeling is 83% of the SA of the material spontaneously lost in 1 h. However, trypsinization following a 2-h period of spontaneous release yields material of reduced (43%) SA. Neither 3H2DIDS labeling nor the initial spontaneous loss of labeled material alters cell electrophoretic mobility. However, extended spontaneous release is accompanied by a significant decrease in surface charge density. Trypsinization immediately following labeling or after spontaneous release (2 h) reduces mobility by 32%. We have tentatively identified the slowly released compartment as contributing to cell surface negativity.
Collapse
|
115
|
Boivin LP, Smith TC. Electrically calibrated radiometer using a thin film thermopile. APPLIED OPTICS 1978; 17:3067-3075. [PMID: 20203927 DOI: 10.1364/ao.17.003067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The fabrication and principal characteristics of an electrically calibrated absolute radiometer are described. The receiver substrate incorporates an evaporated chromium-nickel thermopile, an electrical shield, a copper thermal diffuser disk, an evaporated chromium electrical heating element, and a goldblack absorber. All insulating layers are evaporated silicon monoxide; the thermopile and heater are made by a photoetching process. The performances of several radiometers are discussed. For example, a 28-junction version has a responsivity and NEP of 93 mV/W and 50 nW, respectively, in air, with a time constant of 15 sec and a surface responsivity uniform to better than 1%. The radiometers require only a few corrections of small magnitude. An analysis of sources of error and residual uncertainties shows that the over-all precision of this type of radiometer is at least 0.5% for a power level of 50 microW. Comparative radiometric measurements are described that support this claim.
Collapse
|
116
|
Okerholm RA, Peterson FE, Keeley FJ, Smith TC, Glazko AJ. Bioavailability of norethindrone in human subjects. Eur J Clin Pharmacol 1978; 13:35-9. [PMID: 639831 DOI: 10.1007/bf00606680] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A competitive protein binding assay for norethindrone was developed to measure plasma levels in human subjects. The plasma levels were considerably higher in women than in men, especially at low dose levels. The plasma levels were directly related to the dose in men; but greater variations in the plasma levels were observed in women. The plasma half-life was about 5 h in both sexes with single oral doses of 5 to 20 mg. A comparative bioavailability study with norethindrone from 2 different manufacturers, formulated in the same manner, showed no significant differences in absorption characteristics and provided sufficient data for pharmacokinetic analysis.
Collapse
|
117
|
Abstract
We studied calcium transport in vivo and in vitro in large bowel of normally fed young male rats. Solutions containing zero, 1.7, 3.4 and 5.0 mM calcium and isotopic 45Ca as tracer were perfused in vivo through the lumen of cecum and descending colon. In vitro flux studies were also carried out in cecum with 2.0 and 0.2 mM calcium solutions utilizing the technique of Ussing and Zerahn whereby both chemical and electrical gradients across planar sheets of cecal tissues were nulled. The combined findings demonstrated that (i) cecum was more permeable to calcium than descending colon indicating a proximal to distal absorption gradient in large bowel; (ii) the transport of calcium in both segments increased with increasing luminal calcium concentration, and (iii) calcium transport in both cecum and descending colon was passive only. Thus the large bowel appears to play only a minor role in calcium homeostasis in the normally fed rat.
Collapse
|
118
|
Brandon FB, Shillis JL, Beardmore WB, Smith TC, Brackett RG. Ether-treated, subunit Hsw1N1 influenza vaccines: response of immunologically primed subjects to two antigenic variants. J Infect Dis 1977; 136 Suppl:S539-45. [PMID: 606773 DOI: 10.1093/infdis/136.supplement_3.s539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Two bivalent, ether-treated, subunit influenza vaccines were compared in adults greater than or equal to 45 years old. Both vaccines contained 200 chick cell-agglutinating (CCA) units of A/Victoria/3/75 antigen/dose. The Hsw1N1 components, also at a level of 200 CCA units/dose and designated A/Shope and A/X-53, were antigenically representative of the A/swine/1976/31 and A/New Jersey/8/76 viruses, respectively. A/Shope virus possessed about 100 times more neuraminidase activity than A/X-53 virus. The two vaccine groups had equivalent geometric mean titers (GMTs) of antibody to A/NJ virus, with about 95% of each group having titers of greater than or equal to 1:40 after vaccination. Group GMTs of antibody to A/Vic virus were also equivalent. Failure of the A/X-53 vaccinees to respond according to the dogma of original antigenic sin and a highly significant between-group difference in response to A/PR/8/34 antigen are interpreted as due to a difference in vaccine neuraminidase levels. It is suggested that, although A/Shope was as serologically effective against A/NJ virus as A/X-53 in this age group, under similar conditions a recombinant with the A/NJ hemagglutinin and the stable A/swine neuraminidase antigens might be more effective against A/NJ than either of the present vaccines.
Collapse
|
119
|
|
120
|
Smith TC. Use of ritodrine in pregnant diabetics. BRITISH MEDICAL JOURNAL 1977; 2:124. [PMID: 871785 PMCID: PMC1630931 DOI: 10.1136/bmj.2.6079.124-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
121
|
Smith TC, Adams R. Intracellular compartmentation of Na+, K+ and Cl- in the Ehrlich ascites tumor cell: correlation with the membrane potential. J Membr Biol 1977; 35:57-74. [PMID: 560490 DOI: 10.1007/bf01869940] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The intracellular distribution of Na+, K+, Cl- and water has been studied in the Ehrlich ascites tumor cell. Comparison of the ion and water contents of whole cells with those of cells exposed to La3+ and mechanical stress indicated that La3+ treatment results in selective damage to the cell membrane and permits evaluation of cytoplasmic and nuclear ion concentrations. The results show that Na+ is sequestered within the nucleus, while K+ and Cl- are more highly concentrated in the cell cytoplasm. Reduction of the [Na+] of the incubation medium by replacement with K+ results in reduced cytoplasmic [Na+], increased [Cl-] and no change in [K+]. Nuclear concentrations of these ions are virtually insensitive to the cation composition of the medium. Concomitant measurements of the membrane potential were made. The potential in control cells was -13.7 mV. Reduction of [Na+] in the medium caused significant depolarization. The measured potential is describable by the Cl- equilibrium potential and can be accounted for in terms of cation distributions and permeabilities. The energetic implications of the intracellular compartmentation of ions are discussed.
Collapse
|
122
|
Smith TC, Kinkel AW. Bioavailability of two brands of quinidine gluconate administered on a multiple-dose regimen. CURRENT THERAPEUTIC RESEARCH 1977; 21:128-34. [PMID: 401707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
123
|
Smith TC, Kinkel A. Absorption and metabolism of phenytoin from tablets and capsules. Clin Pharmacol Ther 1976; 20:738-42. [PMID: 791565 DOI: 10.1002/cpt1976206738] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Crossover studies were conducted to compare plasma levels of phenytoin and urinary throughput of the major metabolite, 5-(p-hydroxyphenyl)-5-phenylhydantoin (HPPH), after ingestion of single 250-mg oral doses as tablets or as capsules. Plasma levels of phenytoin did not differ significantly for the 2 formulations except at 8 and 12 hr after ingestion of drug, when the mean values for the tablets were higher than for the capsules. The normalized area under the curve, however, did not differ significantly for either preparation, indicating that equivalent amounts of each preparation were absorbed. Urinary throughput of HPPH did not differ significantly between the 2 preparations. The results suggest that the 2 preparations provide equivalent therapeutic effects.
Collapse
|
124
|
Heinrich RA, Smith TC, Moyer CE. Equivalency of two lots of heparin and their effects on various coagulation tests. CURRENT THERAPEUTIC RESEARCH 1976; 20:725-34. [PMID: 825358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
125
|
Abstract
Twenty subjects, in a double-blind, controlled, rising dose study, were given ethosuximide either once daily or 3 times daily. Steady-state plasma levels and urinary throughput were proportional to dose and were equivalent whether the daily dose was given as a single or divided dose. This finding adds validity to consideration of the single daily dose regimen as a therapeutic possiblity. The metabolic principles should be considered both in patient management and in the treatment of overdosage.
Collapse
|