Experimental emetine myopathy: enzyme histochemical, electron microscopic, and immunomorphological studies

A multi-targeting drug design strategy for identifying potent anti-SARS-CoV-2 inhibitors

The COVID-19, caused by SARS-CoV-2, is threatening public health, and there is no effective treatment. In this study, we have implemented a multi-targeted anti-viral drug design strategy to discover highly potent SARS-CoV-2 inhibitors, which simultaneously act on the host ribosome, viral RNA as well as RNA-dependent RNA polymerases, and nucleocapsid protein of the virus, to impair viral translation, frameshifting, replication, and assembly. Driven by this strategy, three alkaloids, including lycorine, emetine, and cephaeline, were discovered to inhibit SARS-CoV-2 with EC50 values of low nanomolar levels potently. The findings in this work demonstrate the feasibility of this multi-targeting drug design strategy and provide a rationale for designing more potent anti-virus drugs.

Emetine Synergizes with Cisplatin to Enhance Anti-Cancer Efficacy against Lung Cancer Cells

Cisplatin is still the primary therapeutic choice for advanced lung cancers without driver mutations. The occurrence of cisplatin resistance is a major clinical problem in lung cancer treatment. The natural extracted agent emetine reportedly has anticancer effects. This study aimed to explore the possible role of emetine in cisplatin resistance. We used cell viability, Western blot, and Wnt reporter assays to show that emetine suppresses proliferation, β-catenin expression, and Wnt/β-catenin signaling in non-small cell lung cancer (NSCLC). The synergism of emetine and cisplatin was assessed by constructing isobolograms and calculating combination index (CI) values using the Chou-Talalay method. Emetine effectively synergized with cisplatin to suppress the proliferation of cancer cells. Furthermore, nuclear β-catenin and cancer stem cell-related markers were upregulated in the cisplatin-resistant subpopulation of CL1-0 cells. Emetine enhanced the anticancer efficacy of cisplatin and synergized with cisplatin in the cisplatin-resistant subpopulation of CL1-0 cells. Taken together, these data suggest that emetine could suppress the growth of NSCLC cells through the Wnt/β-catenin pathway and contribute to a synergistic effect in combination with cisplatin.

Muscle Toxicity of Drugs: When Drugs Turn Physiology into Pathophysiology

Drugs are prescribed to manage or prevent symptoms and diseases, but may sometimes cause unexpected toxicity to muscles. The symptomatology and clinical manifestations of the myotoxic reaction can vary significantly between drugs and between patients on the same drug. This poses a challenge on how to recognize and prevent the occurrence of drug-induced muscle toxicity. The key to appropriate management of myotoxicity is prompt recognition that symptoms of patients may be drug related and to be aware that inter-individual differences in susceptibility to drug-induced toxicity exist. The most prevalent and well-documented drug class with unintended myotoxicity are the statins, but even today new classes of drugs with unintended myotoxicity are being discovered. This review will start off by explaining the principles of drug-induced myotoxicity and the different terminologies used to distinguish between grades of toxicity. The main part of the review will focus on the most important pathogenic mechanisms by which drugs can cause muscle toxicity, which will be exemplified by drugs with high risk of muscle toxicity. This will be done by providing information on key clinical and laboratory aspects, muscle electromyography patterns and biopsy results, and pathological mechanism and management for a specific drug from each pathogenic classification. In addition, rather new classes of drugs with unintended myotoxicity will be highlighted. Furthermore, we will explain why it is so difficult to diagnose drug-induced myotoxicity, and which tests can be used as a diagnostic aid. Lastly, a brief description will be given of how to manage and treat drug-induced myotoxicity.

Cardiac changes in anorexia nervosa

Introduction Anorexia nervosa is an eating disorder, which is associated with many different medical complications as a result of the weight loss and malnutrition that characterise this illness. It has the highest mortality rate of any psychiatric disorder. A large portion of deaths are attributable to the cardiac abnormalities that ensue as a result of the malnutrition associated with anorexia nervosa. In this review, the cardiac complications of anorexia nervosa will be discussed.

METHODS

A comprehensive literature review on cardiac changes in anorexia nervosa was carried out.

RESULTS

There are structural, functional, and rhythm-type changes that occur in patients with anorexia nervosa. These become progressively significant as ongoing weight loss occurs.

CONCLUSION

Cardiac changes are inherent to anorexia nervosa and they become more life-threatening and serious as the anorexia nervosa becomes increasingly severe. Weight restoration and attention to these cardiac changes are crucial for a successful treatment outcome.

[Congenital and other myopathies]

The myopathies presented here fall into two groups: Congenital myopathies and protein aggregate myopathies. These genetic conditions often require all modern diagnostic investigations, including histology, enzyme histochemistry, immunohistochemistry and electron microscopy to pave the way to an adequate individual molecular analysis and diagnosis. This is necessary to provide the patient and his or her family information about disease-characteristics or even disease-specific features. Distal myopathies, although caused by mutations in different genes, and toxic myopathies as acquired neuromuscular conditions largely provide non-specific morphological features a correct nosological interpretation of which only succeeds with additional non-morphological data.

Heart failure in anorexia nervosa: case report and review of the literature

OBJECTIVE

To report the presentation and causes of heart failure complicating anorexia nervosa (AN).

METHOD

Report of a case of heart failure occurring in a patient with AN and a review of the literature.

RESULTS

A 56 year old woman with a 25 year history of AN binge-purge subtype experienced increasing shortness of breath on exertion, orthopnea, and swelling of the ankles. Investigations revealed a reduced left ventricular ejection fraction. A diagnosis of heart failure caused by severe prolonged protein-calorie malnutrition was made. She was treated with a diuretic, a beta adrenergic blocker and an angiotension enzyme inhibitor. Her cardiac function returned to normal after a year of refeeding. Protein-calorie malnutrition, ipecac toxicity, and deficiencies of thiamine, phosphorus, magnesium, and selenium have been reported to cause heart failure in patients with AN.

DISCUSSION

If shortness of breath occurs in AN it may be a symptom of heart failure. The diagnosis is further suggested by increased jugular venous pressure, increasing shortness of breath on exertion, and pulmonary crepitations at the bases of the lungs on physical examination. The chest x-ray usually shows pulmonary venous redistribution, the electrocardiogram may be normal, and the echocardiogram should document a reduced left ventricular ejection fraction. Standard medical therapy for heart failure should be started. In addition, a history of ipecac use should be taken, deficiencies should be corrected, and weight restoration can reverse cardiac abnormalities.

Toxicological aspects of Kampo medicines in clinical use

Among 210 medicinal prescriptions used in present-day Japan, the clinical uses and the acute, chronic and mutagenic toxicity study of 16 Kampo (Japanese herbal) medicines are summarized. These Kampo medicines are classified into two categories; eight prescriptions containing Bupleurum root (Bupleurum falcatum L.) such as Sho-saiko-to and Saiko-keishi-to, and eight prescriptions not containing Bupleurum root such as Juzen-taiho-to and Ninjin-yoei-to. Studies of some potential interaction between herbal medicine and western drugs are also described.

Congenital myopathies at their molecular dawning

The introduction and application of molecular techniques have commenced to influence and alter the nosology of congenital myopathies. Long-known entities such as nemaline myopathies, core diseases, and desmin-related myopathies have now been found to be caused by unequivocal mutations. Several of these mutations and their genes have been identified by analyzing aggregates of proteins within muscle fibers as a morphological hallmark as in desminopathy and actinopathy, the latter a subtype among the nemaline myopathies. Immunohistochemistry has played a crucial role in recognizing this new group of protein aggregate myopathies within the spectrum of congenital myopathies. It is to be expected that other congenital myopathies marked by inclusion bodies may turn out to be such protein aggregate myopathies, depending on analysis of individual proteins within these protein aggregates and their association with putative gene mutations.

Co-existence of nemaline and cytoplasmic bodies in muscle of an infant with nemaline myopathy

A sporadic case of congenital myopathy had severe muscle weakness of neonatal onset. Nemaline and cytoplasmic bodies were detected in muscle biopsies taken at 4 months of age. These findings were consistent with a diagnosis of nemaline myopathy (severe neonatal form). The simultaneous and abundant presence of these two types of sarcoplasmic inclusion has been found in only a few cases. However, these cases suggest that the sarcoplasmic inclusions may be formed, at least partially, by common mechanisms.

Desmin-related neuromuscular disorders

Desmin, the intermediate filament protein of skeletal muscle fibers, cardiac myocytes, and certain smooth muscle cells, is a member of the cytoskeleton linking Z-bands with the plasmalemma and the nucleus. The pathology of desmin in human neuromuscular disorders is always marked by increased amounts, diffusely or focally. Desmin is highly expressed in immature muscle fibers, both during fetal life and regeneration as well as in certain congenital myopathies, together with vimentin. Desmin is also enriched in neonatal myotonic dystrophy and small fibers in infantile spinal muscular atrophy. Focal accretion of desmin may be twofold, in conjunction with certain inclusion bodies, cytoplasmic and spheroid bodies, and in a more patchy fashion, granulofilamentous material. Both lesions have been found in certain families, affected by a myopathy and/or cardiomyopathy. Other proteins, e.g., dystrophin, vimentin, actin, ubiquitin, and alpha-B crystallin, may also be overexpressed. Desmin pathology may be genetically regulated or may merely reflect profoundly impaired metabolism of several proteins within myofibers.

Alterations of intermediate filaments in various histopathological conditions

Intermediate filament proteins belong to a multigene family and constitute an important cytoskeletal component of most vertebrate cells. Their pattern of expression is tissue specific and is highly controlled during embryonic development. Numerous pathologies are known to be associated with modifications of intermediate filament organisation, although their precise role has not yet been elucidated. The present review focuses on the most recent data concerning the possible causes of intermediate filaments disorganization in specific pathologic conditions affecting the epidermis, the liver, and the nervous system. We discuss the formation of abnormal intermediate filament networks that arise as a consequence of mutations that directly affect intermediate filament structure or are induced by multifactorial causes such as modifications of post-translational processes and changes in the levels of expression.

Effects of myotoxins on skeletal muscle fibers

This review highlights various aspects of a number of experimental myological alterations, induced by different chemical toxicants, including anticholinesterase, colchicine, vincristine, chloroquine, tetanus toxin, botulinum toxin, reserpine and emetine. Despite their chemical diversity and mechanism(s) of action, it is evident from the data discussed here that remarkably different toxic agents exert quite similar effects and induce toxic myopathies. The latter include preferential involvement of slow-twitch red muscle, mitochondrial derangement, denervation-like alterations, formation of membranous whorls, tubular aggregates, autophagic vacuoles and axonal sprouts. The non-invasive experimental models discussed here are valuable in studying various aspects of myopathology in the absence of any mechanical damage to the innervating elements from neurons to axonal terminals.

Disruption of intermediate filament organization leads to structural defects at the intersomite junction in Xenopus myotomal muscle

In mature striated muscle, intermediate filaments (IFs) are associated with the periphery of Z-discs and sites of myofibril-membrane attachment. Previously T. Schultheiss, Z. X. Lin, H. Ishikawa, I. Zamir, C. J. Stoeckert and H. Holtzer (1991) J. Cell Biol. 114, 953) reported that the disruption of IF organization in cultured chick myotubes had no detectable effect on muscle cell structure. Cultured muscle is not, however, under the mechanical loads characteristic of muscle in situ. The dorsal myotomal muscle (DMM) of the Xenopus tadpole provides an accessible model system in which to study the effects of mutant IF proteins on an intact, functional muscle. DNAs encoding truncated forms of Xenopus vimentin or desmin were injected into fertilized Xenopus eggs. Embryos were allowed to develop to the tadpole stage and then examined by confocal or electron microscopy. DMM cells containing the truncated IF polypeptides displayed disorganized IF systems. While the alignment of Z-lines appeared unaffected, cells accumulating mutant IF polypeptides displayed abnormal organization at the intersomite junction. Myocyte termini are normally characterized by deep invaginations of the sarcolemma. In myocytes expressing mutated IF polypeptides, these membrane invaginations were reduced or completely absent. Furthermore, the attachment of myofibrils to the junctional membrane was often aberrant or completely disrupted. These results suggest that in active muscle IFs play an important role in the organization and/or stabilization of myofibril-membrane attachment sites.

Intermediate filaments: new proteins, some answers, more questions

The past year has seen significant progress in the characterization of intermediate filament proteins. New proteins have been identified and physiologically significant differences between known proteins have been revealed. Changes in intermediate filament organization have been linked to changes in cell behavior, and mutational analyses are beginning to reveal the connection between intermediate filament expression, network formation, cellular behavior and disease.

Desmin pathology in neuromuscular diseases

Desmin is an intermediate filament protein that in striated muscle is normally located at Z-bands, beneath the sarcolemma, and prominently at neuromuscular junctions. It is abundant during myogenesis and in regenerating fibers, but decreases in amount with maturation; in regenerating and denervated muscle fibers it is co-expressed with vimentin. Aggregates of desmin occur as nonspecific cytoplasmic bodies or cytoplasmic spheroid complexes, similar to the aggregates of keratin filaments in Mallory bodies or the neurofilament aggregates in Lewy bodies. In all three instances, alpha-B crystallin may be associated with desmin. There are now increasing numbers of neuromuscular disorders in which abnormal amounts of desmin, some abnormally phosphorylated, feature prominently in muscle fibres. Several of these diseases, including spheroid body myopathy, granulo-filamentous body myopathy and the dystrophinopathies, are familial. Ultrastructural and immunohistochemical studies of desmin have considerably broadened our understanding of the pathology of the cytoskeleton in muscle fibers and in certain hereditary neuromuscular diseases.