Distinct atrial natriuretic factor receptor sites on cultured bovine aortic smooth muscle and endothelial cells

Cultured bovine aortic smooth muscle and endothelial cells each display distinct specific binding sites for radiolabeled atrial natriuretic peptide (ANF). 125I-pro-rANF (103-126)I binding to both cell types is rapid, reversible and competitive. Scatchard plots of the binding data show Bmax values of 5.5 and 0.1 - 2.1 X 10(5) sites/cell and Kd values of 2.1 and 0.3 nM for smooth muscle and endothelial cells, respectively. In addition, ANF elevates levels of cGMP substantially in both cell types at concentrations of ANF close to its Kd and Ki for binding. Sodium nitroprusside, however, has essentially no effect on cGMP levels in either cell type. These results show that distinct functionally active receptor sites for ANF exist on both vascular smooth muscle and endothelial cells.

Left ventricular isomyosins in normal and hypertrophied rat and human hearts

Regulation of rat cardiac contractility by changes in the expression of a particular form of myosin (V1-V3) has been demonstrated with a pressure overload. Previous reports of the effect of a volume overload have been controversial. Therefore, we measured the isomyosin composition and mechanical function in the same papillary muscles from rat hearts subjected to a chronic volume overload (aortic insufficiency, AI). A marked change in isomyosin composition from V1 to V3 occurred. Contractility, as assessed by shortening velocity Vmax, was also significantly decreased, and this decrease was correlated with the isomyosin transformation. The changes in isomyosin composition and speed of contraction with AI are thus similar to changes induced by aortic stenosis. Little experimental evidence exists for involvement of such changes in the regulation of human cardiac contractility. Using immunoglobulins highly specific for V1 and V3 in autopsy samples we have observed that the human left ventricle is mostly composed of a V3 isoform (HV3) and that small amounts (1 to 15%) of a V1 type (HV1) are present in foetal and some adult hearts. This HV1 is absent from the left ventricles of patients with valvular disease, assessed at the time of valve replacement (N = 30, samples provided by Dr P. Menasché). Myosin Ca2+-stimulated ATPase activities were not significantly different between normal and hypertrophied hearts. These data demonstrate the heterogeneity of human ventricular myosin, which is composed of V1 and V3 isomyosins, as in other mammalian species. Isomyosin shifts from V1 to V3 are possible in man, but they are quantitatively small and without noticeable influence on overall ATPase activities.

Isomyosins, microtubules and desmin during the onset of cardiac hypertrophy in the rat

Chronic overloading of the rat heart induces a cascade of adaptational events which compensate for the increase in work. Two of these have been extensively described: a qualitative event with an isomyosin change leading to an improved efficiency and a quantitative event resulting in cardiac hypertrophy. By means of immunofluorescence, we investigated if elements of the cytoskeleton, i.e. microtubules and intermediate filaments, could be triggers for these adaptational mechanisms. Studies of overloaded heart were performed in young rats with aortic stenosis or adult rats with aortic insufficiency. Cardiac myocytes were isolated and labelled by immunofluorescence with antibodies raised against V1 or V3 isomyosin, desmin or tubulin. The aim of the work was to visualize: when and where the shift in the expression of isomyosins occurs within the myocytes; the eventual changes in the pattern of intermediate filaments of desmin and/or of microtubules during the adaptation of myocytes to overload. We observed: that the shift from the high (V1) to low (V3) ATPase isomyosin occurred in a population of myocytes soon after stenosis; that changes in the pattern of microtubules occurred soon after induction of hypertrophy; no changes in the distribution or intensity of the staining of desmin.

Messenger RNA content and complexity in normal and overloaded rat heart: a preliminary report

Cardiac overload is associated with two different changes in gene expression: an increase in overall protein synthesis leading to hypertrophy, and at least two isoenzymic redistributions affecting myosin and creatine kinase. This preliminary report was an attempt to study the cardiac genome in this model. Total RNA (ribonucleic acid) was prepared by a combination of the guanidine-ethanol and phenol procedures. A DNA (deoxyribonucleic acid)-, t(transfer)-RNA-free preparation containing non-degraded 28 and 18 S rRNA and 3% poly A+-m (messenger) RNA was obtained. The poly A+mRNA isolated on an oligo (dT) cellulose column had an average nucleotide length of 1300 to 1800 and its c (complementary) DNA was 600 to 1400 base pairs. The first analysis of the kinetics of hybridation revealed a complex pattern which could be described by division into three components. Northern blot and dot blot using a recombinant cDNA plasmid complementary to myosin heavy chain or to actin mRNA (a gift from A. Weydert and M. Buckingham) indicated the presence of these two mRNA, with the former being frequently degraded. After aortic stenosis, both the content and the concentration of total RNA and poly A+mRNA increased in parallel and peaked by the 4th day at +35%. This is the first suggestion that the control of gene expression is transcriptional in this model.

Atrial natriuretic factor elicits an endothelium-independent relaxation and activates particulate guanylate cyclase in vascular smooth muscle

A 26 amino acid synthetic peptide fragment of atrial natriuretic factor (ANF) relaxed isolated rabbit aortic segments in which the endothelium was either intact or functionally destroyed. The relaxations were temporally associated with increases in levels of cGMP with no change in the levels of cAMP. The ANF-induced increases in cGMP were also observed in aortic segments pretreated with calcium-free buffer or the cGMP phosphodiesterase inhibitor M&B 22,948. Qualitatively similar results were obtained for sodium nitroprusside. ANF selectively activated particulate guanylate cyclase, having no effect on the soluble form of the enzyme. Thus, the direct (endothelium-independent) vasodilator effect of ANF may be mediated via increased tissue levels of cGMP. ANF appears to increase vascular cGMP levels by activation of particulate guanylate cyclase.

[Characterization of total RNA, messenger poly(A)+ RNA and homologous complementary DNA in experimental cardiac hypertrophy]

Two biological modifications are observed during adaptation of cardiac tissue to work overload: an increase in total protein synthesis and a redistribution of myosin isoenzymes. These modifications suggest that changes in DNA transcription are involved in the early response of cardiac tissue to overload. Results are reported in this paper that show a parallel increase in total and polyadenylated RNA content and concentration in cardiac overloaded tissue in the rat. The characterization of cardiac poly (A)+ mRNA by mRNA X cDNA hybridization and the identification of specific mRNAs with recombinant plasmid cDNAs are given in this report as preliminary results.

Preparation of venous allografts. A comparison of techniques

In order to evaluate alternate techniques of preparing veins for use as homografts, 102 femoral veins were harvested from adult mongrel dogs. The veins were treated in four different ways, then transplanted into recipient animals bypassing their ligated femoral arteries. Group I--24 veins (6 cm each) were harvested and immediately transplanted. Group II--24 veins were stored in 15% dimethyl sulfoxide (DMSO) solution at -120 C for 21 days prior to transplantation. Group III--26 veins were stored for 21 days in plasminate solution at -60 C prior to use as allografts. Group IV--28 veins were stored in 0.5% gluteraldehyde solution for 21 days prior to implantation. Animals were randomly sacrificed at 1-month, 2-month, 6-month, and 12-month intervals. Patency of the transplant was determined weekly by ultrasound. Specimens were sent for light and scanning electron microscopy at the time of harvest, prior to implantation, and at sacrifice. Endothelial damage was graded on a scale of 0-16. Veins in Group II had a significantly higher patency rate (68% at 1 year) than Group III (35%) and Group IV (11%) (p less than 0.05). The intimal layer of all patent vessels was replaced by an organized mural thrombus. Partial endothelialization of the luminal surface was most prevalent in Group II. Intimal damage related to storage technique was significant in Group III (p less than 0.01). At sacrifice, severe endothelial damage was present in all groups (p less than 0.01). In conclusion, veins stored in 15% dimethylsulphoxide (DMSO) solution at -120 C have immunologic and physical characteristics that yield patency rates acceptable for clinical use when autogenous tissue is not available.

Different distributions of microtubules, desmin filaments and isomyosins during the onset of cardiac hypertrophy in the rat

To elucidate the role of the cytoskeleton in the development of adult heart, microtubules and intermediate filaments of desmin were studied in young and adult rat heart myocytes during the onset of growth, after mechanical overloading induced by aortic stenosis. Such overloading is known to cause heart hypertrophy by stimulating overall protein synthesis, and to initiate a shift in myosin isozymes. For this study, we used double immunolabelling of isolated myocytes with specific antibodies raised against tubulin, desmin, and the two main isomyosins V1 and V3. Whereas desmin remained unchanged, tubulin was redistributed in arrays parallel to the long axis of the myocytes, and was densest around the nuclei. Alterations in the microtubule pattern were observed very early after aortic stenosis, during the onset of heart growth; they were transitory, and did not occur simultaneously in all myocytes. Chronological examination of myocytes labelling with both antitubulin and anti V3 myosin clearly suggested that the transitory alteration in the microtubule pattern was an early event preceding the change in the expression of the myosin gene. Results, observed in young rats, in which mitosis is stimulated by overloading, and in adult rats, exhibiting no mitosis, showed that microtubules are involved in the development of cells in which mitosis does not occur. This work provides the first evidence of a correlation in functional adult heart, between the reorganization of cytoplasmic microtubules and the onset of growth.

Myosin types in the human heart. An immunofluorescence study of normal and hypertrophied atrial and ventricular myocardium

Two distinct myosin heavy chain isoforms, referred to as alpha and beta, were identified in the human heart with specific antimyosin antibodies. By indirect immunofluorescence, myosin heavy chain alpha was found to be a major component of atrial myosin and a minor component of ventricular myosin, while heavy chain beta was found to be a major component of ventricular myosin and a minor component of atrial myosin. In the normal heart, there was marked individual variability in the proportion of ventricular myocytes reactive for heavy chain alpha. Atrial myocytes staining for heavy chain beta were rare in the left atrium and more numerous in the right atrium, especially in the crista terminalis and in the interatrial septum. Surgical and autoptic specimens from hypertrophied left ventricles of patients with mitral regurgitation showed a myosin immunoreactivity pattern similar to that of normal specimens. Very rare muscle cells reactive for heavy chain alpha were seen in the hypertrophied left ventricles of subjects with hypertension and in the hypertrophied right ventricles of subjects with tetralogy of Fallot. A dramatic transformation of myosin heavy chain composition was observed in hypertrophied left atria of patients with mitral stenosis, with a shift to heavy chain beta in a large proportion of atrial myocytes. The findings indicate that chronic exposure to hemodynamic overload can induce marked changes in the myosin heavy chain composition of human atria, whereas it affects only slightly that of the ventricles.

The relation of cytomegalovirus and Epstein-Barr virus antibodies to T-cell subsets in homosexually active men

Eighty-nine homosexual men participated in a study of sexual practices, T-cell subsets, and antibody titers to cytomegalovirus (CMV) and Epstein-Barr virus (EBV). The prevalence of antibody to CMV was 96% and to EBV, 94%. Titers to CMV were higher in those practicing receptive anal intercourse. The CMV antibody titers were positively correlated with the T-helper/suppressor ratio, number of partners and venereal disease episodes, number of T-suppressor cells, and EBV titers. Twelve percent of the participants had a low ratio only, 18% T-suppressor augmentation, and 3% T-helper deficiency. The CMV titer and prevalence of receptive anal intercourse were higher in those with a low ratio only, T-suppressor augmentation, and T-helper deficiency. These results suggest that CMV infection is acquired through receptive anal intercourse and is associated with an increase in T-suppressor cells and, in some persons, a decrease in T-helper cells.

Comparison of the tryptic digestion pattern of subfragments 1 from V1 and V3 rat cardiac isomyosins

The limited tryptic digestion patterns of the chymotryptic subfragment 1 (S1) of the two rat ventricular isomyosins V1 and V3, were compared under several conditions. Pure S1V1 was obtained from 3-week-old rats and pure S1V3 from adult rats 6 weeks after hypophysectomy. To localize the sites of trypsin susceptibility and to determine the distribution of the peptides along the S1 molecule, we used, as a probe, antibodies raised against a pig cardiac 29-kDa peptide. We demonstrate that this peptide contains the N-acetyl group located on the N-terminal part of the cardiac myosin molecule. In S1V1 we observed two major sites of proteolysis, independently of the digestion conditions: they are located at 27kDa and 80kDa from the N terminus as in skeletal muscle S1.S1V3 appears much more sensitive to the proteolysis conditions: at least two additional sites of cleavage are present in the 50-kDa peptide when digested at pH 8.0. Decrease in the pH from 8.0 to 7.0 or the presence of Mg-ATP have no effect on the digestion of S1V1 while these ambient factors protect the 50-kDa peptide of S1V3 from breakdown. We conclude that the 50-kDa peptide is a variable portion of the myosin molecule, the conformation of which is sensitive to ambient factors such as the pH or the presence of nucleotides.

Isozymes of myosin in growing and regenerating rat muscles

Native myosin isozymes of rat muscles have been isolated by electrophoreses in non-dissociating conditions. Their mobilities were measured, using taenia coli myosin as an internal standard and their relative concentrations were determined by computer planimetry of the electrophoretograms. Three isozymes were observed in extensor digitorum longus (EDL), two in soleus (SOL), four in neonatal muscles three days before birth. Regenerates of minced EDL or SOL muscles in adult animals had no native myosin the third day after surgery; they were similar to neonatal muscles 15 days after surgery and to adult muscles 60 days after surgery.

Quantitative changes in T helper or T suppressor/cytotoxic lymphocyte subsets that distinguish acquired immune deficiency syndrome from other immune subset disorders

Quantitative measurements of the immune cell subgroups, T helper (Leu 3+/OKT4+) cells and T suppressor/cytotoxic (Leu 2+/OKT8+) cells, were made in patients having acquired immune deficiency syndrome (AIDS) with Kaposi's sarcoma and in patients with AIDS and opportunistic infection, as well as in three other relevant populations. These included patients with lymphadenopathy syndrome, e.g., homosexually active males with lymphadenopathy who sought medical care for additional symptoms, and healthy male homosexuals, as well as a control population. Decrease in the number of T helper cells is characteristic of AIDS with Kaposi's sarcoma or opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population is rare in AIDS with Kaposi's sarcoma but is more frequent in AIDS with opportunistic infection. Augmentation of the T suppressor/cytotoxic cell population, however, may occur in a variety of circumstances, including cytomegalovirus and other viral infections, in healthy, homosexually active males, and in otherwise healthy hemophiliac subjects receiving factor VIII treatment. Reduced T helper:T suppressor/cytotoxic cell ratio can be caused by either decrease in the number of T helper cells or augmentation of the T suppressor/cytotoxic cell population. Lowered T helper:T suppressor/cytotoxic cell ratio does not, by itself, help to distinguish between AIDS and other causes of reduced ratios. Quantitative measurements are needed to define the T subset changes. AIDS is characterized by decrease in the number of T helper cells and reduced T helper:T suppressor/cytotoxic cell ratio. The T helper (Leu 3+) and T suppressor/cytotoxic (Leu 2+) cell subpopulations can change independently. Identification of decrease in the number of T helper cells as an alteration that occurs independently of numerical change in other lymphoid subpopulations, such as T suppressor/cytotoxic cells and B cells, and the close association of the decrease in the number of T helper cells with AIDS are consistent with a distinct pathogenesis (and cause) for AIDS.

Microtubules and desmin filaments during the onset of heart growth in the rat

Microtubules and intermediate desmin filaments were visualized in rat cardiomyocytes during the onset of heart growth by double immunolabelling of isolated myocytes, with specific antibodies raised against tubulin and desmin. Heart growth was stimulated either by mechanical overloading induced by aortic stenosis, or by injection of thyroxine into hypothyroid rats. In both experimental models, alterations in the microtubule pattern were observed soon after stimulation of growth whereas desmin filament organization remained unchanged. Microtubules were redistributed in arrays parallel to the long axis of the myocytes and were more numerous around the nuclei. Microtubules therefore appeared to be involved in the cellular events occurring during stimulated heart growth irrespective of the nature of the stimulus.

Adrenal pseudotumors on CT due to dilated portosystemic veins

The adrenal and periadrenal venous systems are part of the portosystemic collateral pathways that may enlarge in portal hypertension. The cross-sectional image of the resulting enlarged venous channels may simulate an adrenal mass. Three examples of such computed tomographic (CT) scans are presented with selective venographic correlation. Patients with portal hypertension and suspected adrenal pathology may require enhanced or dynamic CT scans.

Myosin isoenzymes in normal and hypertrophied human ventricular myocardium

We tested the hypothesis that hypertrophy of the human heart is associated with the redistribution of ventricular isomyosins. Human cardiac myosin was isolated from autopsy samples of left ventricular free wall of patients with cardiac hypertrophy and of fetal, young, and adult subjects without heart disease. The following parameters were studied: electrophoretic migration in denaturing and non-denaturing conditions; immunological cross-reactivities with three different types of antibodies; and early phosphate burst size and steady state ATPase activities stimulated by K+-EDTA, Ca++, Mg++, and actin. The antibodies were chosen for their ability to recognize selectively the rat V1 and V3 cardiac isomyosins. The first type was a monoclonal antibody, CCM-52, prepared against embryonic chick cardiac myosin, the second was an anti-beef atrial myosin, and the third was an anti-rat V1 myosin. CCM-52 reacted with a greater affinity with rat V3 than with rat V1, and was a probe of mammalian V3. Anti-beef atrial myosin and anti-rat V1 myosin both recognized specifically beef atrial and rat V1 myosins, and were thus considered as probes of mammalian V1. Under non-denaturing conditions, human myosins migrated as rat V3 isomyosin; under denaturing conditions, no difference was observed in any of the electrophoretic parameters between all samples tested, except for the fetal hearts which contained a fetal type of light chain. The immunological studies indicated that human myosins were composed mostly of a V3 type (HV3), but contained also some V1 isomyosin. A technique was developed to quantify the amount of human VI isomyosin which was found to range from almost 0 to 15% of total myosin, and to vary from one heart to the other, regardless of the origin of the heart. Enzymatic studies showed no significant difference between normal, hypertrophied, and fetal hearts in any of the activities tested. However, there was a significant correlation between Ca++-stimulated ATPase activities and HV1 amount (at 0.05 M KCl, n = 18, r2 equal 0.49, P less than 0.01; at 0.5 M KCl, n = 18, r 2 = 0.5, P less than 0.01). These data demonstrate the heterogeneity of human ventricular myosin, which appears to be composed, as in other mammalian species, of V1 and V3 isoforms of different ATPase activities (V1 greater than V3). However it seems that V1 to V3 shifts do not appear to be of physiological significance in the adaptation of human heart to chronic mechanical overloads.

Immunological quantitation and localization of tubulin in adult rat heart isolated myocytes

Isolated myocytes were purified from adult rat heart. Identification and localization of microtubules and quantitation of tubulin in these cells were performed by immunochemical procedures. Antibodies were raised against brain tubulin and purified by affinity chromatography. An enzyme-linked immunosorbent assay, ELISA, was developed for quantitation of tubulin. It allowed the measurement of 10 to 500 ng of tubulin. Tubulin content in adult rat cardiac myocytes was found to be approximately 10 micrograms per 100 mg of the total protein content. By means of a double immunofluorescence technique, the microtubule network, identified with antitubulin, was studied in reference to the sarcomeric A band labeled with antibodies specific to myosin heavy chains. The basis for identifying the microtubule network have included the use of specific antitubulin immunoglobulins and the sensitivity of the specific labeling of the network to antimitotic drugs and low temperature. It was found that microtubules were organized mainly around the nuclei, with important concentrations at the poles, showing extensions in the cone and in the cytoplasm as loosely organized loops. The shape of adult cardiac myocyte was not dependent upon the integrity of the microtubule network.

Relation between sexual practices and T-cell subsets in homosexually active men

27% of 89 young, non-ill, homosexually active men in Los Angeles had a Leu-3(OKT4)/Leu-2(OKT8) ratio less than or equal to 0 . 8. The low ratio was due to a significantly raised mean number of Leu-2 cells, whereas individuals with acquired immune deficiency syndrome had a decrease in both Leu-3 and Leu-2 cells. The term "acquired immune augmentation" may be appropriate for those with a low ratio due to raised numbers of Leu-2 cells. Those practising passive (receptive) anal intercourse had a significantly higher mean number of Leu-2 cells than did those practising only active (insertive) anal intercourse or no anal intercourse. The results of this study suggest that two distinct conditions occur in homosexually active men. Whether acquired immune augmentation is a precursor of the rarer acquired immune deficiency syndrome or is an unrelated disorder needs to be determined. In this study passive anal intercourse was associated with acquired immune augmentation.

Distribution of myosin isozymes within single cardiac cells. An immunohistochemical study

Isozymes of myosin have been localized with respect to individual cardiac myocytes in hearts from 3-week-old, adult controls, and adult hypophysectomized rats, and in cultured cardiac cells. For this purpose, affinity-purified antibodies reacting specifically with the heavy chains of each of the two major myosin isozymes of adult rat heart, V1 and V3, were used. The distribution of the two isomyosins was determined by double immuno-labeling of the same cell, V1 myosins being revealed by rhodamine and V3 myosins by fluorescein. A procedure is described which allows optimum immunological visualization of the myosin filaments of rod-shaped isolated myocytes. It was found that the response of the cardiac cells to the two antimyosins varied depending on the state of the animal. In 3-week-old rats, all cells were stained with the anti-V1, and almost none with the anti-V3 myosin. In the hypophysectomized animals, on the contrary, all cells were stained with the anti-V3 and none with the anti-V1. A mixed pattern of reactivity was observed in adult controls since 50% of the cells reacted with the anti-V1, 10% with the anti-V3, and 40% with both antibodies. In the latter case, the distributions of V1 and V3 reactivities were homogeneous throughout the cell, and absolutely superimposable. The same double reactivity and homogeneous repartition were observed in cultured cells. These findings indicate that myocytes from adult rat myocardium are heterogeneous in terms of their isomyosins content and show for the first time that two isomyosins can coexist and be equally distributed in one cardiac cell. These observations are relevant to the regulation of individual heart cell contractility.

Amphibian brain gangliosides: pattern analysis by two-dimensional thin-layer chromatography

Gangliosides were extracted from brains from ten amphibian species, representing six different genera from two orders, and analyzed by two-dimensional thin-layer chromatography (2D-TLC). Qualitatively distinct differences were detected at the family level, while differences within the same family or genus were primarily quantitative.

Comparisons of rat cardiac myosins at fetal stages in young animals and in hypothyroid adults

Rat cardiac ventricular myosins were obtained from fetuses, from young normal animals, and from hypophysectomized adults. The purified proteins were compared by several techniques: (i) electrophoresis in non-denaturing conditions (pyrophosphate buffer), (ii) one- and two-dimensional analysis after proteolytic cleavage, (iii) immunological blotting after electrophoretic purification, and (iv) competitive enzyme-linked immunosorbent assay. Antibodies specific to each of the two major isoenzymes of adult rat heart (V1 and V3 according to the terminology of Hoh et al. (Hoh, J. F. Y., McGrath, P. A., and Hale, P. T. (1978) J. Mol. Cell. Cardiol. 10, 1053-1076) were used for the immunological studies. The heavy chains of the ventricular myosin isoenzymes of fetuses (V3F) were indistinguishable from those of the V3H isoenzyme present in hypophysectomized adults; both proteins differed from the V1 isoform of young animals. The light chains of V3F, V3H, and V1 were the same, except that V3F contained in addition a small amount of the embryonic light chain (Whalen, R. G., and Sell, S. M. (1980) Nature 286, 731-733). These results strongly suggest that adaptation of the adult rat heart to the hormonal deficiencies of hypophysectomy is mediated by the synthesis of the same myosin heavy chain form which is predominant in fetal hearts.

Denervation of newborn rat muscle does not block the appearance of adult fast myosin heavy chain

Several observations, both in vivo and in vitro, have indicated that the development and maturation of mammalian skeletal muscle fibres is influenced by nerve-muscle interactions. Morphological maturation of newly regenerated adult mouse muscle fibers in an organotypic nerve-muscle culture system depends on the presence of spinal cord neurones. Sciatic nerve transection in newborn rats has been shown to modify the development of the histochemical and contractile properties of the denervated muscles. In addition, neural influences are important for the appearance of certain of the myosin small subunits. It has been proposed that the nerve also controls the changes in myosin heavy chain isozymes appearing during development. One such transition occurs in rat muscle where the neonatal form of myosin heavy chain is replaced by the adult form during the second post-natal week. Here we demonstrate that innervation of the rat gastrocnemius muscle (a fast-contracting muscle in the adult) is not required for the appearance of the adult form of myosin heavy chain.