Hot topics in interventional cardiology: Proceedings from the society for cardiovascular angiography and interventions 2020 think tank

The society for cardiovascular angiography and interventions (SCAI) think tank is a collaborative venture that brings together interventional cardiologists, administrative partners, and select members of the cardiovascular industry community for high-level field-wide discussions. The 2020 think tank was organized into four parallel sessions reflective of the field of interventional cardiology: (a) coronary intervention, (b) endovascular medicine, (c) structural heart disease, and (d) congenital heart disease (CHD). Each session was moderated by a senior content expert and co-moderated by a member of SCAI's emerging leader mentorship program. This document presents the proceedings to the wider cardiovascular community in order to enhance participation in this discussion, create additional dialogue from a broader base, and thereby aid SCAI and the industry community in developing specific action items to move these areas forward.

Effects of Latanoprost and GLC756, a Novel Dopamine D2 Agonist and D1 Antagonist, on Cultured Normal Human Dermal Fibroblasts

Purpose

Proliferation of subconjunctival fibroblasts plays a critical role in scarring and failure of glaucoma filtering surgery. Long-term topical glaucoma medications appear to increase fibroblast proliferation. In this study, the effects of topical antiglaucoma drugs latanoprost and GLC756, a novel dopamine D2 agonist and D1 antagonist, on cultured normal human dermal fibroblasts (NHDF) were examined.

Methods

The NHDF cell line was incubated with latanoprost, prostaglandinF2α (PGF2α), GLC756, or 5-fluorouracil as a positive control at concentrations of 3 and 30 μM for 6, 18, and 24 hours. Fibroblast growth was measured by 5-bromodeoxyuridine (BrdU) uptake using laser scanning cytometry.

Results

Latanoprost and PGF2α had a biphasic response on the number of cultured NHDF positively stained with BrdU. A stimulating effect on proliferation occurred early, 6 hours after incubation, and an inhibitory effect 18 to 24 hours after incubation. GLC756, in contrast, revealed only inhibitory effects on BrdU uptake 18 to 24 hours after incubation. The pattern of GLC756 was similar to that of the positive control 5-fluorouracil.

Conclusions

Latanoprost seemed to have a biphasic response on the proliferation of cultured NHDF. First there was a stimulating thereafter a secondary negative modulating effect. GLC756 had a fully antiproliferative effect on the NHDF, indicating an additional potential of novel dopamine compounds for topical glaucoma medication.

Characterization of nitrotyrosine as a biomarker for arthritis and joint injury

OBJECTIVES

To characterize the utility of nitrotyrosine (NT) as a biomarker for arthritis and joint injury.

DESIGN

Synovial fluid, plasma, and urine from patients diagnosed with osteoarthritis (OA), rheumatoid arthritis (RA), anterior cruciate ligament (ACL) injury, meniscus injury and pseudogout, and knee-healthy volunteers were analyzed for concentrations of NT, nitrate and nitrite (NO(x)), matrix metalloproteinase (MMP)-3, MMP-1, MMP-9, more than 40 chemokines and cytokines.

RESULTS

In OA, plasma and synovial fluid NT were increased versus healthy volunteers. Synovial fluid to plasma NT ratios were elevated in OA patients. Synovial fluid from patients with ACL and meniscus injury and pseudogout had increased levels of NT (P < 0.001). In these samples, NT levels significantly correlated with ARGS-aggrecan neoepitope generated by aggrecanase cleavage of aggrecan (P ≤ 0.001), cross-linked C-telopeptides of type II collagen (P < 0.001), MMP-1 (P = 0.008), and MMP-3 (P ≤ 0.001). In RA, plasma NT decreased following 6 months of anti-tumor necrosis factor (TNF) treatment. For every 1.1% change in log(10) NT, there was a 1.0% change in the log(10) disease activity scores (DAS28-3 CRP). Both predicted and observed DAS28-3 CRP showed a robust linear relationship with NT. RA plasma NT positively correlated with CRP, MMP-3 and interferon γ-induced protein 10.

CONCLUSIONS

NT may serve as a useful biomarker for arthritis and joint injury. In RA, NT is highly correlated with several biomarkers and clinical correlates of disease activity and responds to anti-TNF therapy.

Resection and reconstruction of mediastinal great vessels in invasive thymoma

OBJECTIVE

To evaluate the safety, feasibility, and outcome following radical excision of thymoma with resection and reconstruction of invaded mediastinal vessels.

STUDY DESIGN

A retrospective study.

PATIENTS AND METHODS

Six patients with thymoma invading the superior vena cava (SVC) and/or the brachiocephalic veins (BCVs) were reviewed in this study. All the patients underwent radical excision of the tumor along with invaded mediastinal vessels followed by vessel reconstruction or repair. The clinical presentation, operative details, postoperative course, and follow-up were reviewed and analyzed.

RESULTS

Three patients presented with features suggestive of SVC syndrome. Contrast-enhanced computed tomography of the chest was the primary imaging modality, which detected a tumor with invasion of major mediastinal veins. WHO type B2 was the commonest histologic type, which was seen in 4 cases. Intraoperatively, SVC invasion, SVC and BCV invasion, and BCV invasions alone were seen in 1, 2, and 3 cases, respectively. The vessels were reconstructed with a prosthetic graft in 3 patients, and autologous pericardial tube graft was used in 1 patient. Two patients had primary repair of the wall of the involved vessel. Postoperative course was complicated by ventilator support requirement in 2, graft thrombosis in 2, acute renal failure in 1 and pneumonia in 1 patient. All patients are alive at the end of follow-up period ranging between 18 and 24 months.

CONCLUSION

Thymoma excision with the reconstruction of SVC or BCV is safe and feasible in experienced hands.

Effects of three cytochrome P450 inhibitors, ketoconazole, fluconazole, and paroxetine, on the pharmacokinetics of lasofoxifene

AIMS

Two studies were conduced to assess the effects of ketoconazole, a CYP3A4/5 inhibitor; fluconazole, a CYP2C9 inhibitor; and paroxetine, a CYP2D6 inhibitor, on lasofoxifene pharmacokinetics.

METHODS

The first parallel group study was conducted in 45 healthy postmenopausal women (15 per group) to compare the pharmacokinetics of a single dose of lasofoxifene (0.25 mg) administered alone and in combination with ketoconazole (400 mg daily x 20 days) or fluconazole (400 mg daily x 20 days). Lasofoxifene was administered on day 2 and blood samples were collected serially for up to 456 h postdose (20 days). The second study enrolled 20 healthy postmenopausal women (10 per group) to compare the pharmacokinetics of a single dose of lasofoxifene (0.25 mg) alone and in combination with paroxetine (30 mg qd x 21 days). Lasofoxifene was given on day 8 of paroxetine treatment and blood samples were collected serially for up to 336 h postdose.

RESULTS

All subjects completed the study and the treatments were well tolerated. Lasofoxifene C(max) and AUC ratios [90% confidence interval (CI)] with/without ketoconazole were 111% (98.4, 127) and 120% (105, 136), respectively, and were 91.3% (80.3, 104) and 104% (91.4, 118), respectively, with/without fluconazole. Lasofoxifene C(max) and AUC ratios (90% CI) with/without paroxetine were 118% (95.4, 146) and 135% (120, 152), respectively.

CONCLUSIONS

Coadministration of potent inhibitors of CYP3A4/5 and CYP2D6, but not CYP2C9, resulted in a moderate increase in lasofoxifene exposure. No dosage adjustment should be required when lasofoxifene is coadministered with ketoconazole, fluconazole, paroxetine or other agents that inhibit these CYP enzymes.

Effects of antiglaucoma drugs GLC756, a novel dopamine D2 agonist and D1 antagonist, and timolol on endotoxin-induced TNF-alpha release in serum of rats

PURPOSE

Anti-inflammatory activity of an antiglaucoma drug may be an advantage for long-term treatment of glaucoma since it may reduce the risk of treatment-related inflammatory processes in outer compartments of the eye and probably also prevent or delay progression of glaucomatous retinal neurodegeneration. In this study, the effect of GLC756, a novel mixed dopamine D 2 receptor agonist and dopamine D 1 receptor antagonist, and timolol on endo-toxin-induced cytokine tumor necrosis factor-alpha (TNF-alpha) release in serum was examined.

METHODS

For endotoxin-induced TNF-alpha release, 8-week-old Lewis rats were intravenously injected with 160 microg lipopolysaccharide (LPS) from Salmonella typhimurium. GLC756, timolol, or betamethasone were either systemically (1 mg/kg SC for 5 days) or topically (0.4%, 0.5%, and 0.1%, respectively, 20 microL eye drops given 16 times over 48 hours in left and right eye) administered. TNF-alpha was measured in serum 2 and 48 hours after LPS induction.

RESULTS

A marked TNF-alpha increase in serum was found 2 hours after LPS induction. Administration of GLC756 and betamethasone, systemically and topically, decreased TNF-alpha release. However, due to large scattering of mean values only the effect of systemically administered GLC756 was statistically significant. In contrast, timolol increased TNF-alpha values stronger than LPS alone.

CONCLUSIONS

The significant suppression of LPS-induced TNF-alpha increase by GLC756 suggests an additional anti-inflammatory potential of the dopaminergic compound in the treatment of glaucoma.

Design and evaluation of immunotoxicity studies

The evaluation of potential adverse effects of pharmaceuticals on the immune system is part of the standard drug development procedures and needs to be available prior to the start of phase III clinical trials. Although the histopathological assessment of lymphoid organs/tissues is considered fundamental for the identification and characterization of immunotoxic reactions, additional investigations are now recommended by the European guidelines for repeated-dose toxicity testing of medicinal products in order to achieve an accurate assessment of immune system functionality with regard to immunomodulation. In the present paper, we describe and discuss a study design which permits the investigation of the immune function in a 4-week study in rats following immunization by subcutaneous administration of the T-dependent antigen Keyhole Limpet Hemocynin (KLH). This includes assessment of hematology parameters, titration of KLH-specific antibodies in serum, lymphocyte immunophenotyping in blood, thymus, spleen and lymph nodes, macroscopic pathology and histopathological evaluation of the lymphatic organs/tissues and of the injection sites.

Effects of anti-glaucoma drugs timolol and GLC756, a novel mixed dopamine D2 receptor agonist and D1 receptor antagonist, on endotoxin-induced-uveitis and -arthritis in rats

Anti-glaucoma drugs exhibiting anti-inflammatory properties are desirable for the long-term treatment of glaucoma since they may reduce the risk for treatment-related inflammatory processes in outer compartments of the eye. The purpose of this study was to evaluate potential anti-inflammatory effects of two topically and systemically applied anti-glaucoma drugs i.e. GLC 756, a novel mixed dopamine D2 receptor agonist and D1 receptor antagonist, and timolol a beta-adrenoceptor antagonist using endotoxin-induced uveitis (EIU) and arthritis in rats as an in vivo model. For EIU, 8-week-old Lewis rats were intravenously injected at 160 microg lipopolysaccharide (LPS) from Salmonella typhimurium. GLC756, timolol, or betamethasone, as a positive control, were either topically (0.4%, 0.5%, and 0.1%, respectively, 16-times 20 microL eye drops during 48 h) or systemically (1mg/kg subcutaneous for 5 days) administered. Cell infiltration in tissue of the eye and knee joint were assessed histopathologically and in special compartments of the eye by confocal microscopy 48 h after LPS-induction. Numerous infiltrating cells were detected in the eyes after LPS-induction and half of the animals showed arthritis. Topical and systemic pre-treatment with GLC756 and timolol resulted in reduced cell infiltration in the eye. In addition, GLC756 reduced, whereas timolol increased the incidence of arthritis. Betamethasone suppressed almost completely the cell infiltration in the eye and the incidence of arthritis. In conclusion, the observations that GLC756 reduced cell infiltration in the eye and the incidence of arthritis after LPS-induction is compatible with anti-inflammatory properties of this drug. By contrast, timolol produced no consistent anti-inflammatory effect since both inhibitory as well as stimulatory effects on inflammatory processes were seen.

Determination of the effect of calcineurin inhibitors on the rat's immune system after KLH immunisation

The calcineurin inhibitors cyclosporin A (CsA), tacrolimus (FK506) and pimecrolimus (ASM981) are on the market for the oral treatment of psoriasis and atopic dermatitis and topical treatment of atopic dermatitis, respectively. The effect of these treatments on the immune response was investigated in this study after immunisation of rats with keyhole limpet hemocyanin (KLH). Male rats (10 per group) were orally administered pimecrolimus at 10 or 30 mg/kg/day), tacrolimus at 3 mg/kg/day or CsA at 20 mg/kg/day for 4 weeks. Control animals similarly received the vehicle only. The last five animals per group were immunised and challenged with KLH on days 16 and 24, respectively. Eight days after the last injection, the immune function was investigated by detecting KLH-specific antibodies in the serum and by examination of cell infiltration at the site of the KLH-challenge. In addition, a correlation between functional and structural changes was established by quantification of lymphocyte sub-populations in the blood or residing in lymphatic tissue. In KLH-immunised rats, CsA caused complete suppression of the KLH-specific IgM and IgG production, whereas only IgG production was affected by pimecrolimus at 30 mg/kg/day and more so by tacrolimus at 3 mg/kg/day. Immunophenotyping of lymphocyte sub-populations in spleen and lymph node indicated a decrease in T lymphocytes with pimecrolimus at 30 mg/kg/day, tacrolimus and CsA, whereas these changes were marginal for pimecrolimus at 10 mg/kg/day. Immunophenotyping of peripheral white blood cells (WBC) revealed a decrease in the absolute number of T lymphocytes with all three test items. In comparison with non-immunised animals, a slight increase in absolute numbers of T lymphocytes was observed in KLH-immunised animals treated with pimecrolimus at 10 or 30 mg/kg/day. In conclusion, the ability of the immune system to respond to KLH was not affected by pimecrolimus at 10 mg/kg/day whereas a decrease in immune function was noted in the other groups as follows: pimecrolimus (30 mg/kg/day) < tacrolimus (3 mg/kg/day) < CsA (20 mg/kg/day).

Validation of immune function testing during a 4-week oral toxicity study with FK506

Assessment of the immune system's capability to respond to antigens with the generation of specific antibodies, whilst under the influence of a test article, is required in toxicity tests according to the European guideline for repeated dose toxicity testing of medicinal products. The purpose of this study in rats was to validate methodology for the determination of Keyhole Limpet Haemocyanin (KLH)-specific antibodies under the influence of an immunologically active compound. The immunosuppressant FK506, commercially available as Prograf, was administered orally (gavage) to five rats per sex per group at dosages of 0.5mg/kg per day or 3mg/kg per day, for a period of 4 weeks. On days 14 and 22, KLH was administered subcutaneously, with an adjuvant (AluGel), to the two treated groups and a control (i.e. without FK506 treatment) approximately 1h following administration of FK506. Terminal investigations included haematology parameters, titration of KLH-specific antibodies in serum (ELISA), macroscopic pathology, spleen and thymus weights, immunophenotyping of splenocytes (FACS analysis) and histopathology of the lymphatic tissues. At 3mg/kg per day a minimal reduction of subcutaneous KLH-induced granuloma formation and a moderate to marked reduction of germinal centre development (axillary lymph node and spleen) were observed. Reduced CD4+ (T-cell) counts were found in the spleen of males, consistent with a suppressed production of KLH-specific antibodies (IgG in both sexes, IgM in males only) and a higher incidence of atrophy in the periarteriolar lymphoid sheaths of males. Slight-to-moderate lymphopenia was present in both sexes at 3mg/kg per day. These findings are consistent with the known pharmacological activity of FK506. In conclusion, determination of antibody titres following immunisation of rats with KLH, with concurrent exposure to a drug, appears to be a valid method in the context of the immunotoxicity evaluation required by European regulation.

Characterization of Bordetella pertussis strains of recent isolation

During the clinical trial conducted in Italy to evaluate the efficacy of new acellular pertussis vaccines, the most favorable conditions for the recovery and characterization of Bordetella pertussis strains, isolated from children with cough, were adopted. The nasopharyngeal aspirates were collected and sent to the laboratory in refrigerated conditions within 24 hours. Charcoal agar selective and non selective plates were used, and most of the isolates were recovered after 3-4 days of incubation. Confirmation of all suspected colonies included the use of biochemical tests and specific agglutination reaction with B. pertussis antiserum. Serotyping of fimbriae, susceptibility to erythromycin and DNA fingerprinting by Pulsed Field Gel Electrophoresis (PFGE), were performed to characterize B. pertussis isolates and to determine relatedness among different strains. Serotype 1,3 was the most represented in the bacterial population examined. A predominant pulsetype (PTA) characterized most of the isolates accounting for 71.4% of the strains examined. Eight subclones (23.5%) and three unrelated pulsetypes were also found. No resistant strains to erythromycin were detected.

Evaluation of a new procedure for the flow cytometric analysis of in vitro, chemically induced micronuclei in V79 cells

Measurement of the frequency of micronuclei induced in cells by ionizing radiation or by chemical treatment is widely used to analyze cytogenetic damage. The microscopic scoring of micronuclei is a tedious and time-consuming procedure. Therefore, attempts have been made to automate micronuclei scoring by means of image analysis or flow cytometry. A new procedure for the flow cytometric analysis of chemically induced micronuclei in V79 Chinese hamster cells has been established in our laboratory. Debris was separated from micronuclei by means of a new gating procedure using area and width fluorescence of the stained suspension of micronuclei and nuclei. In order to test the sensitivity and specificity of this improved method of flow cytometric analysis, five well-known mutagenic compounds were tested. With the new technique, the frequency of micronuclei measured and analyzed corresponded well with results obtained by conventional microscopy. In addition, a large series of negative compounds, and weak, middle, and strong micronuclei inducers, were tested in order to establish criteria for discrimination between genotoxic and nongenotoxic compounds by flow cytometry. This new procedure for flow cytometric detection of micronuclei represents a quick, reliable, and relatively simple method for in vitro micronucleus testing.

Experimental therapy of systemic lupus erythematosus: the treatment of NZB/W mice with mouse soluble interferon-gamma receptor inhibits the onset of glomerulonephritis

Female NZB/W F1 mice develop an autoimmune disease similar to human systemic lupus erythematosus (SLE), and ultimately die of glomerulonephritis. Starting at the age of 16 weeks NZB/W F1 mice were treated for a period of 19 weeks with soluble interferon-gamma receptor (sIFN-gamma R), anti-IFN-gamma monoclonal antibody (mAb) or IFN-gamma. All mice treated with sIFN-gamma R or anti-IFN-gamma mAb were alive 4 weeks after the treatment was discontinued, whereas 50% of mice died in the placebo groups and 78% of the mice died in the IFN-gamma-treated group. Histologically, there was severe membrano-proliferative glomerulonephritis in IFN-gamma- and placebo-treated mice, and minimal or no mesangioproliferative disease in mice receiving sIFN-gamma R or anti-IFN-gamma mAb. The renal mononuclear infiltrate (T lymphocytes and monocytes), expression of major histocompatibility complex class II antigen and glomerular immunoglobulin and complement deposition were reduced in those mice. These data suggest that an IFN-gamma inhibitor, such as the soluble IFN-gamma R, can be used for SLE therapy in the early stages of the disease.

Interleukin-6 exacerbates glomerulonephritis in (NZB x NZW)F1 mice

The ability of interleukin-6 (IL-6) to modulate immune parameters and mesangial cell function suggests a role for this cytokine in the development of autoimmune glomerulonephritis. This hypothesis was tested in 6-month-old female (NZB x NZW)F1 mice that were administered recombinant human IL-6 (rhIL-6) (50 and 250 micrograms/kg s.c.) for 12 weeks, resulting in an accelerated and severe form of membranoproliferative glomerulonephritis associated with marked upregulation of mesangial major histocompatibility complex class II antigen and glomerular ICAM-1 expression. To distinguish direct effects of rhIL-6 on the renal mesangium from those mediated through the immune system, (NZB x NZW)F1 mice were immunosuppressed with cyclosporin. Immunosuppression by cyclosporin inhibited the development of glomerulonephritis, decreased class II antigen expression, and abrogated IL-6-mediated effects. Administration of neutralizing anti-IL-6 antibody had no effect on the spontaneous development of glomerulonephritis in (NZB x NZW)F1 mice. This finding, together with undetectable IL-6 serum levels, makes a pathogenetic role of endogenously produced IL-6 in this disease model unlikely. In contrast to (NZB x NZW)F1 mice, parental NZW or BALB/c mice given high doses of rhIL-6 (500 micrograms/kg) or recombinant murine IL-6 (100 micrograms/kg) daily for 4 weeks failed to develop morphological or biochemical evidence of glomerulonephritis. Induction of acute phase proteins, anemia, thrombocytosis, and induction of renal class II antigen confirmed the biological activity of IL-6 in these mice. In conclusion, while non-nephritogenic in normal mice, IL-6 accelerates the development of the genetically determined glomerulonephritis of (NZB x NZW)F1 mice through effects mediated by a modulated immune system. Since neutralizing IL-6 antibody treatment did not prevent the development of glomerulonephritis, it is unlikely that increased IL-6 production plays a role in the pathogenesis of lupus nephritis.

Modulation of adoptively transferred viable motheaten pathology in sublethally irradiated normal recipient mice by normal hematopoietic cells

"Adoptive mev" chimeras were created by grafting hematopoietic cells (HC) from B6 viable motheaten (mev) mice into bg or wild sublethally irradiated (SI) mice: the chimeras developed mev-type symptoms such as paw inflammation and necrosis, lung damage, thymus atrophy, and high serological IgM concentration and autoantibody levels as well as rapid death. The phenotype of adoptive mev mice could be obtained even after two to three successive passages into SI mice (Kuntz et al., 1991. Immunology 73, 356). In the present study, mixed HC transfer experiments showed that bg or wild HC could not prevent or delay neither the serological symptoms nor the pathology conferred by cotransferred mev HC. Nevertheless, when cotransferred with adoptive mev chimera HC, bg or wild HC could block the development of the pathology and the morbidity, although only delayed the emergence of the serological abnormalities. This shows that the differentiation of mev HC in a bg or wild normal-type environment does not allow the maintenance of all mev HC-dependent abnormalities.

[The incidence of HBsAg in different population groups of Moldavia in 1991 compared to 1973]

AgHBs incidence in various population groups from the Iaşi region was relatively high in 1991, ranging from 3.8% in blood donors to 75.0% in patients with severe acute virus hepatitis. As compared to the incidence values recorded in 1973, 18 years ago, in the population of the same territory, some mutations were observed, the most important being the more then threefold reduction of the AgHBs incidence in blood donors. In subjects with liver diseases and in risk groups, the frequency of AgHBs carriers maintains at a high level.

[Incidence of HBsAg among different population groups in Moldavia in 1991 compared with 1973]

AgHBs incidence in various population groups from the Iassy region was relatively high in 1991, ranging from 3.8% in blood donors to 75.0% in patients with severe acute virus hepatitis. As compared to the incidence values recorded in 1973, 18 years ago, in the population of the same territory, some mutations were observed, the most important being the more then threefold reduction of the AgHBs incidence in blood donors. In subjects with liver diseases and in risk groups, the frequency of AgHBs carriers maintains at a high level.

Calcium, calmodulin and 3',5'-cyclic nucleotide phosphodiesterase activity in human muscular disorders

3',5'-Cyclic nucleotide phosphodiesterase (PDE) is known to play an important role in the regulation of cyclic nucleotide levels in various tissues including the muscle. Previous studies have estimated the level of this enzyme in several neuromuscular disorders but the results have been variable. Moreover, there was no attempt made to correlate the enzyme levels with the levels of calcium and calmodulin, both of which regulate diverse biological processes including muscle contraction. In the present study we have estimated phosphodiesterase in the muscle of normal controls as well as patients with myotonic (MyD) and Duchenne muscular dystrophy (DMD) and amyotrophic lateral sclerosis (ALS). PDE was found to be increased significantly in all of the diseased muscles as compared to controls (P less than 0.01). But the increase could be coupled with an increase in calcium and calmodulin only in Duchenne dystrophic muscle.

Adoptive transfer of viable motheaten pathology in sublethally irradiated beige recipient mice

B6 viable motheaten (mev) mice are short-living autoimmune and immunodeficient mice. Most of the mev pathology is transferable into the B6 beige (bg) irradiated mouse by injection of mev haematopoietic cells. Indeed there is a rapid establishment of lung damage, thymus aplasia, inflammation and necrosis of peripheral joints, an increase of serological IgM concentrations and autoantibody levels as well as a rapid death. This mev-type pathology can be again obtained by transferring haematopoietic cells of these [mev----bg] chimeras into other irradiated bg mice, although the appearance of these serological and phenotypical symptoms seems to be more and more delayed when doing cascade transfers.

Isolation and characterization of the gene and cDNA encoding human mitochondrial creatine kinase

Creatine kinase (CK; EC 2.7.3.2) isoenzymes play prominent roles in energy metabolism. Nuclear genes encode three known CK subunits: cytoplasmic muscle (MCK), cytoplasmic brain (BCK), and mitochondrial (MtCK). We have isolated the gene and cDNA encoding human placental MtCK. By using a dog heart MCK cDNA-derived probe, the 7.0-kb EcoRI fragment from one cross-hybridizing genomic clone was isolated and its complete nucleotide sequence determined. A region of this clone encoded predicted amino acid sequence identical to residues 15-26 of the human heart MtCK NH2-terminal protein sequence. The human placental MtCK cDNA was isolated by hybridization to a genomic fragment encoding this region. The human placental MtCK gene contains 9 exons encoding 416 amino acids, including a 38-amino acid transit peptide, presumably essential for mitochondrial import. Residues 1-14 of human placental MtCK cDNA-derived NH2-terminal sequence differ from the human heart MtCK protein sequence, suggesting that tissue-specific MtCK mRNAs are derived from multiple MtCK genes. RNA blot analysis demonstrated abundant MtCK mRNA in adult human ventricle and skeletal muscle, low amounts in placenta and small intestine, and a dramatic increase during in vitro differentiation induced by serum-deprivation in the non-fusing mouse smooth muscle cell line, BC3H1. These findings demonstrate coordinate regulation of MtCK and cytosolic CK gene expression and support the phosphocreatine shuttle hypothesis.

Serum and fibroblast growth factor inhibit myogenic differentiation through a mechanism dependent on protein synthesis and independent of cell proliferation

Myogenesis is accompanied by the withdrawal of proliferating myoblasts from the cell cycle, their fusion to form myotubes, and the coordinate expression of a variety of muscle-specific gene products, such as the muscle isoenzyme of creatine kinase (MCK). In the present study we used the nonfusing muscle cell line, BC3H1, to examine the mechanisms involved in regulation of MCK mRNA expression. Proliferating BC3H1 cells, in media with 20% fetal calf serum, had undetectable levels of MCK mRNA. Exposure of undifferentiated cells to media containing 0.5% serum resulted in withdrawal of cells from the cell cycle and in a several hundred-fold increase in the steady state level of MCK mRNA. Induction of this muscle-specific mRNA could be rapidly reversed by exposure of quiescent differentiated cells to media containing either 20% serum or pituitary fibroblast growth factor. The decline in the steady state level of MCK mRNA following mitogenic stimulation was not dependent upon reentry of cells into the cell cycle, but it did require protein synthesis. Together, these data indicate that fibroblast growth factor can specifically inhibit muscle-specific gene expression through a mechanism independent of cell proliferation. The finding that MCK mRNA was down-regulated by a mechanism that required protein synthesis suggests that mitogen-inducible early gene products may be involved in regulation of muscle gene expression.

Complete nucleotide sequence of dog heart creatine kinase mRNA: conservation of amino acid sequence within and among species

Creatine kinase (CK; EC 2.7.3.2) plays an important role in energy metabolism in brain and muscle. Expression of CK isoenzymes is regulated during development and is tissue specific. To define the structures of canine CK isoenzymes and to elucidate the mechanism of regulation in their expression, CK cDNA clones from dog myocardium were isolated. Myocardial CK mRNA is predicted to encode a protein of 381 amino acids. The nontranslated regions of the mRNA comprise at least 38 bases at the 5' end and exactly 345 bases before the poly(A) tail. Partial protein sequences of dog muscle (M) CK and brain (B) CK subunits were determined and compared with the derived amino acid sequence of the myocardial enzyme and of M CK subunits of other species. The M CK subunits from different species share a very high degree (83-96%) of sequence identity. Dog M and B subunits share extensive sequence identity (74%), a degree of similarity not previously suspected. Southern blot analysis suggests that a CK gene family exists. These observations imply that evolutionary changes in the M CK subunit structure are constrained by the need for preservation of functional properties other than the kinase activity. This conservation is consistent with the possibility that the M subunit plays a structural role in cardiac and skeletal muscle.

The integrative role of the intralaminar system of the thalamus in visual orientation and perception in the cat

Electrical stimulation with repetitive pulses (6/sec) was applied to the internal medullary lamina and produced tonic contraversive turning movements of eyes and head which were associated with recruiting responses in the visual cortex. Optical gratings of a spatial frequency of 0.5 c/deg which alternated with diffuse illumination of equal intensity were then presented to the animal during conjugated adversive eye movements induced by intralaminar stimulation with continuous sine-wave alternating currents of 5000 c.p.s. The head of the animal was fixed except for rotation in the horizontal plane. Prior to intralaminar stimulation it was turned in the direction opposite to the induced eye movements so that the animal always viewed the central area of the screen. The potential recorded in the visual cortex in response to the gratings consisted of an initial positive-negative potential of the order of 20 muV followed by later deflections of irregular shape. The size of this initial potential was measured during induced gazing and in the absence of intralaminar stimulation. A significantly greater potential in response to the gratings was found during gazing. Diminishing the visual acuity of the animal resulted in a marked decrease of the initial potential and in this condition very little increase was obtained during gazing. No enhancement of the potential was seen when stimulation was applied to other thalamic structures that yielded no visual orientation. It is concluded that perception of contrast is improved during visual orientation and that the effect is due to a concomitant activation of unspecific intralaminar afferents to the visual cortex.

Schizophrenia-like psychosis following 'Mandrax' overdose

In recent years a number of new hypnotics have been introduced which are claimed to give a more natural sleep than barbiturates, and to be free from the dangers of addiction and of respiratory depression when taken in overdosage. Among these drugs is methaqualone, which is used either on its own (Melsed), or in combination with the antihistamine diphenhydramine hydrochloride (Mandrax).