Membrane alterations following interferon treatment

Interferon treatment appears to induce a number of changes in the plasma membrane of uninfected cells. Interferon treatment altered the surface exposure of gangliosides of both Ly and KB cell membranes. The differences were found in the amount and pattern of incorporation of tritium after galactose oxidase treatment. In AKR,C- (AKR-2B) mouse cells, not only was there an apparent increase in the number of intramembranous particles in response to treatment with interferon but also the kinetics of the increase followed that of the establishment of the antiviral activity. The buoyant density of plasma membrane was also found to be significantly increased in interferon-treated cells. Moloney murine leukemia virus produced in interferon-treated mouse thymus and bone marrow cells had a high particle to infectivity ration. This virus contained a prominent glycoprotein with a molecular weight of about 85,000. This large glycoprotein was only a very minor component of Moloney leukemia virus produced in control TB cells and might be an uncleaved precursor to gp 69-71.

Effects of digitalis on the exercise electrocardiogram in normal adult subjects

Controversy continues regarding the effects of administration of digitalis upon the exercise electrocardiogram. Thus, maximal treadmill exercise tests were performed before and two weeks after administration of 0.25 mg of digoxin daily in 15 normal subjects (documented by cardiac catheterization and coronary arteriographic studies). Administration of digitalis induced abnormal findings on exercise tests in all 14 subjects with serum levels of digoxin greater than or equal to 0.5 ng/ml; however, at workloads greater than 75 to 90 percent of maximal predicted heart rate, the changes in the ST segment reverted to a normal configuration in all subjects, thereby providing differentiation of digitalis-induced ST-segment alterations from those due to myocardial ischemia at maximal treadmill stress.

Spontaneous cytomegalovirus mononucleosis with conjunctivitis

Cytomegalovirus (CMV) was isolated from the conjunctiva of a patient with mild unilateral catarrhal conjunctivitis associated with the typical clinical features of CMV mononucleosis syndrome in a previously healthy adult. The diagnosis was confirmed by a marked rise in the complement fixation antibody titers. Prospective studies are needed to determine the frequency of conjunctival involvement in CMV mononucleosis and the relation, if any, to sporadic cases of conjunctivitis.

Linear dose response and quantitative attenuation by potassium of the inotropic action of acetylstrophanthidin

To evaluate the nature of the inotropic dose response of digitalis and to determine the effects of potassium on this response, isometrically contracting isolated supported right ventricular cat papillary muscles were studied relative to their peak tension and peak dT/dt increases to physiologic cumulative doses of acetylstrophanthidin (ACS) in different extracellular potassium concentrations in the muscle bath. The inotropic dose response to ACS was observed to be linear in cumulative glycoside concentrations ranging from 0.40 to 4.23 X 10(-7) M ACS in 3.5 mM K+ medium and from 1.22 to 7.47 X 10(-7) M ACS in 7.0 mM K+ medium. The influence of potassium alterations in the muscle bath from the low to the high K+ concentrations prior to ACS resulted in marked attenuation of the positive inotropic property of ACS. From these data, it is concluded that the dose inotropic response of digitalis is linear, with small doses producing proportionally the same effects as larger doses, and that extracellular potassium markedly influences this linear dose response such that higher K+ concentrations considerably attenuate the positive inotropic response of digitalis.

Effects of thyrotropin on the thyroid cell membrane: hyperpolarization induced by hormone-receptor interaction

Cultured thyroid cells accumulate the lipophilic cation triphenylmethylphosphonium, indicating that there is an electrical potential (interior negative) across the plasma membrane. Thyrotropin stimulates the uptake of the lipophilic cation 3-fold, and the proton conductor carbonylcyanide-m-chlorophenylhydrazone causes efflux of triphenylmethylphosphonium accumulated in the presence or absence of thyrotropin. The stimulatory effect of thyrotropin on triphenylmethylphosphonium accumulation is not mimicked by human chorionic gonadotropin, a glycoprotein hormone with a similar structure whose target organ is not the thyroid, and the effect is abolished if the thyrotropin-receptor activity of the cells is destroyed by treatment with trypsin. Analogous effects are observed with thyroid plasma membrane vesicles which are essentially devoid of mitochondrial and soluble enzyme activities. Triphenylmethylphosphonium uptake and stimulation by thyrotropin occurs when NaCl, KCl, or Tris.HCl concentration gradients are artifically imposed across the vesicle membrane ([salt](out) > [salt](in)). It seems likely, therefore, that triphenylmethylphosphonium uptake is driven by a chloride diffusion potential (interior negative) and that thyrotropin either increases the permeability of the membrane to anions or decreases its permeability to cations. Thyrotropin-stimulated triphenylmethylphosphonium uptake in the vesicle preparations reaches a quasi steady-state within 3 min; in contrast, thyrotropin-stimulated adenylate cyclase activity is negligible during this period of time, becomes measurable after about 4 min, and is optimal after 12-15 min. Thus, a primary mode of action of thyrotropin on the thyroid cell may be an alteration in the electrical potential across the plasma membrane. The relevance of this observation to the mechanism of action of other glycoprotein hormones, certain bacterial toxins, and interferon is discussed.

Echocardiographic identification of the mitral valve prolapse syndrome

The data presented herein would indicate that mitral valve prolapse may be represented by a variable spectrum of abnormalities on the echocardiogram. Utilizing all the abnormalities described, echographic evidence of mitral valve prolapse may be detected in most patients with this disorder. However, evidence of mitral valve prolapse may also be observed in a large contingent of asymptomatic patients without other clinical manifestations of cardiac disease. The biologic significance of these echographic abnormalities remains uncertain and constitutes an important area for future investigation.

A relative deficiency of cytochrome P-450 and aryl hydrocarbon [benzo(a)pyrene] hydroxylase in hyperplastic nodules induced by 2-acetylaminofluorene in rat liver

The concentrations of cytochrome P-450 and the activities of aryl hydrocarbon [benzo(a)pyrene] hydroxylase (AHH) and reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase were measured in early (gray-white) and remodeled (brown) hyperplastic nodules induced in the livers of rats with 2-acetylaminofluorene and were compared to the values in control livers and in the liver surrounding the nodules. Cytochrome P-450 content of early (14 weeks) hyperplastic nodules is 30% of the activity of untreated control livers and 48% of the activity of the surrounding liver. AHH activity of the early nodules is 10% of the control activity and 33% of the activity in the surrounding nonnodular liver. Nicotinamide adenine dinucleotide phosphate-cytochrome c reductase activity in the microsomes of early nodules is 76% of the control activity and 78% of the activity in the surrounding liver. In the late remodeled nodules, (22 and 25 weeks), the cytochrome P-450 content is 40% of that of controls and AHH activity is 15% of the control activity. In primary hepatomas induced by 2-acetylaminofluorene, cytochrome P-450 content is 21% of that of controls, AHH activity is 11% of the activity of controls, and reductase is 50% of the control activity. These results, indicating a relative nodule deficiency in some of the cellular components believed to be important in the activation of hepatocarcinogens and hepatotoxins, offer one possible explanation for the relative resistance to carcinogen cytotoxicity of hyperplastic liver nodules.

Use of thyrotropin and cholera toxin to probe the mechanism by which interferon initiates its antiviral activity

Thyrotropin (10 muM) inhibited the antiviral activity of interferon. When added after interferon, thyrotropin (TSH) had no effect on antiviral activity. There was also no inhibition of interferon action in cells washed with medium between incubations with TSH and interferon. 125I-Labeled TSH and 125I-labeled cholera toxin could bind to preparations of mouse L-cell plasma membranes. The binding was specific in that it was prevented by unlabeled thyrotropin or cholera toxin, but not by insulin, glucagon, prolactin, growth hormone, human chorionic gonadotropin, or luteinizing hormone. Mouse interferon inhibited 125I-labeled TSH binding to L-cell plasma membranes. The effect of mouse interferon on 125I-labeled cholera toxon binding was more complex, inhibition occurring only after an initial enhancement at low interferon concentrations. A 10-fold higher concentration of interferon was required to inhibit 125I-labeled TSH binding. Mouse interferon was also able to displace bound 125I-labeled TSH, but not bound 125I-labeled cholera toxin. The interferon interaction with cell membranes was temperature-sensitive. Human interferon could induce changes in binding of 125I-labeled TSH and 125I-labeled cholera toxin to mouse L-cell plasma membranes similar to those induced by mouse interferon. Mouse interferon induced similar changes in plasma membranes of human KB-3 cells, which are insensitive to both human and mouse interferons. In view of these results, the species specificity of interferons does not appear to reside solely at the point of the initial interaction with their binding sites.

Cytological observations of the ovarian epithelium in mammals during the reproductive cycle

We have studied the ovarian epithelijm at various stages of the reproductive cycle in a number of mammalian species utilizing light microscopy, scanning microscopy, the freeze-fracture technique, transmission microscopy and by employing specialized tracers that use lanthanum and horseradish peroxidase. We found that the epithelial cells are joined by incomplete tight junctions, gap junctions, and desmosomes. The cytoplasmic matrix contains a large irregularly shaped nucleus, few microtubules, microfilaments, mitochondria, endoplasmic reticulum and a host of coated and non-coated vesicles of varying diameters. The saccules comprising the large Golgi complex and its companion vesicles are associated with a basal body-centriole complex: some of these saccules and affiliated vesicles are acid phosphatase positive. Surface modifications of ovarian epithelial cells include numerous microvilli, some of which have a bulbous tip, and plications of the lateral plasma membrane which are thought to accomodate volume changes of the ovary during follicular development. Many coated and non-coated endocytotic caveolae were found on these cells, particularly in the basal area. These caveolae internalized exogeneously administered horseradish peroxidase. We view the marked endocytotic activity as an efficient transport mechanism for partially removing substances from the interstitium of the ovary and the peritoneum.

Efficacy of cardioselective beta adrenergic blockade with intravenously administered tolamolol in the treatment of cardiac arrhythmias

The efficacy of tolamolol, a cardioselective beta adrenergic blocking agent, was evaluated in the treatment of cardiac arrhythmias in 27 patients. Nineteen patients had supraventricular arrhythmias and eight had ventricular arrhythmias. Evaluation was by doulbe-blind randomized trial in 23 patients. Tolamolol was effective in reducing ventricular rate in 17 (85 percent) of 19 patients with supraventricular arrhythmias and resulted in conversion to sinus rhythm in 2 of the 17. The mean ventricular rate in 17 patients decreased from 135 to 102/min 10 minutes after initiation of administration of tolamolol and gradually decreased further to 93/min after 60 minutes. Reduction in ventricular rate was sustained for 2 hours of monitoring undergone by all patients and for 4 and 6 hours monitoring in two subgroups. Among the eight patients with ventricular ectopic beats, tolamolol reduced their frequency in four patients and had no effect in four. Six patients had chronic obstructive pulmonary disease and experienced no adverse clinical effects on respiratory function in association with administration to tolamolol. Untoward effects occurred in 10 patients, including hypotension in 3, 1 of whom required vasopressor therapy. Other side effects were sedation, nausea, dyspnea and warmth in the chest, all of which were mild and transient, requiring no treatment. Cardioselective beta adrenergic blockade with tolamolol was highly effective in controlling ventricular rate in supraventricular arrhythmias and reduced the frequency of ventricular ectopic beats in half of the small group of patients with this arrhythmia. It is particularly applicable in patients with obstructive pulmonary disease in whom cardiac beta adrenergic blockade is indicated. Hypotension is an important potential side effect.

Comparative effects of morphine, meperidine and pentazocine on cardiocirculatory dynamics in patients with acute myocardial infarction

The cardiocirculatory effects of the commonly used parenteral analgesics, morphine sulfate 15 mg, meperidine hydrochloride 100 mg and pentazocine 60 mg, each administered intravenously, were compared in 12 patients with acute myocardial infarction during cardiac catheterization and by echocardiogram. No untoward hemodynamic effects occurred following the administration of morphine or meperidine. In contrast, pentazocine produced significant (p less than 0.01 to less than 0.05) increases in systemic and pulmonary arterial pressures, left ventricular filling pressure, systemic vascular resistance, and systolic and diastolic dimensions; and decreases in left ventricular ejection fraction and mean velocity of circumferential fiber shortening. These deleterious actions of pentazocine appeared due to peripheral vasoconstriction and negative inotropic properties. Further, pentazocine-induced increases in left ventricular preload and afterload increased myocardial oxygen demands. Since this study demonstrates that pentazocine is hazardous in myocardial infarction, morphine and meperidine are the preferred analgesics in this condition.

Cholera toxin interactions with thyrotropin receptors on thyroid plasma membranes

Unlabeled cholera toxin inhibits [125I]thyrotropin binding to thyrotropin receptors on thyroid plasma membranes. Maximal inhibition by cholera toxin does not exceed 40%, whereas unalbeled thyrotropin completely inhibits [125I]thyrotropin binding to these same membranes. Kinetic analyses of the binding data are compatible with the view that the cholera toxin decreases the number of receptor sites available to thyrotropin and that the mechanism by which the cholera toxin inhibits [125I]thyrotropin binding to these receptor sites involves both competitive and noncompetitive elements.

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors

Gangliosides inhibit 125I-labeled thyrotropin binding to the thyrotropin receptors on bovine thyroid plasma membranes, on guinea pig retro-orbital tissue plasma membranes, and on human adipocyte membranes. This inhibition by gangliosides is critically altered by the number and location of the sialic acid residues within the ganglioside structure, the efficacy of inhibition having the following order: GD1b greater than GT1 greater than GM1 greater than GM2 = GM3 greater than GD1a. The inhibition results from the interaction of thyrotropin and gangliosides, rather than the interaction of membrane and gangliosides. Fluorescence studies show that the inhibition is associated with a distinct conformational change of the thyrotropin molecule and that the progression from a "noninhibitory conformation" to an "inhibitory conformation" parallels exactly the order of effectiveness in inhibiting 125I-labeled thyrotropin binding. The ganglioside inhibition of 125I-labeled thyrotropin binding appears to be hormonally specific in that it is not affected by albumin, glucagon, insulin, prolactin, follicle-stimulating hormone, growth hormone, or corticotropin. The possibility that a ganglioside or ganglioside-like structure is a component of the thyrotropin receptor is suggested by the finding that gangliosides more complex than N-acetylneuraminylgalactosylglucosylceramide are present in bovine thyroid membranes in much higher quantities than have been previously found in extraneural tissue. The finding that the B component of cholera toxin, which also interacts with gangliosides, has a peptide sequence in common with the beta subunit of thyrotropin, suggests that thyrotropin and cholera toxin may be analogous in their mode of action on the membrane.

Preparation and in vitro antifungal activities of some quinolizidine derived hemiaminals and beta-tert-amino sulfides

New alpha-thiohemiaminals, 7alpha-phenylthio-7-epideoxynupharidin-6-ol, the diasteriomeric 7beta-phenylthiodeoxy-nupharidin-6-ol, and 3-methyl-3-methylthio-4-hydroxyquinolizidine, were prepared and reduced to the corresponding beta-tert-amino sulfides. The configuration at C-7 of the beta-tert-amino sulfides was determined by observing the direction of the solvent-induced shift of the C-7 methyl proton resonance. The configuration at C-7 of the new alpha-thiohemiaminals was established by correlations with the beta-tert-amino sulfides and confirmed, in the case of the deoxynupharidine derivatives, by circular dichroism and ascertaining the sterochemistry of deuteride incorporation upon sodium borodeuteride reduction of the alpha-thiohemiaminal. The in vitro antifungal activities of six compounds possessing the quinolizidine skeleton, including all the newly synthesized compounds as well as some previously reported ones, and amphotericin B were tested against several human pathogenic fungi. Besides amphotericin B, only the two deoxynupharidine alpha-thiohemiaminals were active, especially against Histoplasma capsulatum and Blastomyces dermatitidis. The observations indicate activity is derived from the 3-furyl group and the functionality from which alpha-thioimmonium ions can be produced.

Abnormalities in the regional circulations accompanying congestive heart failure

In congestive heart failure, patients appear to have alimited ability to dilate their resistance vessels in skeletal muscle in response to a metabolic stimulus. This is true whether the metabolic stimulus is ischemia, dynamic, or static exercise. The mechanism for this limited arteriolar capacity is at least twofold; an increased sodium content of the vessels as well as an increased tissue pressure which is seen in edematous states. This can be considered a positive compensatory mechanism in that it helps to maintain systemic arterial pressure during exercise when the cardiac output fails to increase normally. If the resistance vessels were to dilate normally, then in the face of a limited cardiac output, exercise syncope would be expected to occur...

Influence of experimental edema on metabolically determined blood flow

To evaluate the effects of edema and elevated tissue pressure on metabolically determined blood flow, forelimb vascular resistance was determined by two techniques. Peak reactive hyperemic blood flow after release of a 5-minute arterial occlusion was bilaterally measured in the brachial arteries of 11 dogs before and after venous congestion of one limb for 4 hours at 70 mm Hg and after infusion of 1,000 ml of 6% Dextran 70. Before determining peak reactive hyperemic blood flow, congestion was released; venous pressure was then similar in both limbs. Congestion reduced peak reactive hyperemic blood flow from 23.9 ± 5.7 (SE) to 16.0 ± 3.6 ml/min 100 g -1 ( P < 0.05). Peak reactive hyperemic blood flow was unchanged in the uncongested control limb (21.2 ± 5.2 to 20.4 ± 4.5 ml/min 100 g -1 , P > 0.5) at the time when it was reduced in the congested limb. Total tissue pressure measured with a needle was greater in the congested limb (9.1 ± 1.7 mm Hg) than it was in the uncongested limb (2.5 ± 1.5 mm Hg, P < 0.01). Likewise, pressure in a chronically implanted perforated capsule was -2.1 ± 2.0 mm Hg in the control limb but was +7.2 ± 1.5 mm Hg ( P < 0.01) in the contralateral limb following congestion. Dextran 70 was infused after venous congestion; this procedure produced peak reactive hyperemic blood flows and tissue pressures which were similar in both limbs. Similarly, minimum vascular resistance following an ischemic stimulus in an isolated, denervated constant-perfused forelimb was increased from 17.7 ± 2.2 to 23.9 ± 1.8 mm Hg/ml min -1 100 g -1 ( P < 0.01) following congestion in five dogs. Brachial arterial sodium content was unchanged in four dogs following 4 hours of congestion. These data suggest that, in the presence of edema, metabolic arteriolar dilation may be impaired.

Comparison by controlled clinical trial of streptokinase and heparin in treatment of life-threatening pulmonay embolism

Treatment with heparin or streptokinase was allocated randomly to 30 patients with life-threatening pulmonary embolism verified by angiography. Treatment was given for 72 hours and pulmonary angiography was repeated. There was significantly greater (P < 0.001) evidence of thrombolysis in those patients treated with streptokinase compared with those treated with heparin. The reduction of systolic and mean pulmonary arterial pressures was also significantly greater (P < 0.05 and P < 0.02 respectively) in the streptokinase group.Seven patients failed to complete 72 hours of the trial treatment: five successfully underwent pulmonary embolectomy. Six of these "failures" had initial pulmonary angiographic scores of 24 or more and systemic systolic blood pressure recordings of 100 mm Hg or less. Patients with these features should probably be considered for pulmonary embolectomy as the initial treatment.A febrile reaction commonly occurred in the streptokinase group; otherwise side effects were no more common than in the heparin group.

Calf tendon procollagen peptidase: its purification and endopeptidase mode of action

The procollagen peptidase activity of calf tendon has been purified. The enzyme has a high degree of specificity for native procollagen and converts both pro alpha1 and alpha2, to alpha1 and alpha2, respectively. The purified enzyme is an endopeptidase which excises the amino terminal peptide extensions of the precursor chains in block; the molecular size and amino-acid composition of the excised peptides compare favorably with those predicted in previous reports. Antisera to the enzyme and to procollagen have been prepared and have been used to characterize the enzyme, the enzymatically excised peptides, and the enzyme-peptide complex in reaction mixtures.