Expression of myosin heavy chain isoform mRNA transcripts in the masseter and medial pterygoid muscles / Expresión de transcripciones de ARNm de isoforma de cadena pesada de miosina en los músculos masetero y pterigoideo medial

SUMMARY: Both the masseter and medial pterygoid muscles elevate the mandible, raising the lower jaw by acting simultaneously on the lateral and medial surfaces of the mandibular ramus. Nevertheless, electromyographic studies indicate that these muscles, as well as the superficial and deep heads of the masseter, act in a different way during mastication. We have analyzed by real time quantitative polymerase chain reaction (RT-qPCR) the expression of myosin heavy chain (MHC) isoforms in the masseter and medial pterygoid muscles in humans in order to identify possible differences in the expression patterns that may be related to functional differences identified with electromyography. Our findings indicate that the expression pattern of MHC isoforms in the two muscles is characteristic of fast and powerful phasic muscles. We have also observed a high percentage of expression of the MHC-IIx isoform and the expression of the MHC-M isoform at the mRNA level in both muscles, an isoform that does not translate into protein in the masticatory muscles of humans. The high percentage of expression of the MHC-IIx isoform in humans can be related to a high contractile speed of the masseter and medial pterygoid in humans. On the other hand, the low percentage of expression of the MHC-M isoform at the mRNA level in both muscles can be related to the complex evolutionary process that has reduced the size and force of the masticatory muscles in humans.

RESUMEN: Los músculos masetero y pterigoideo medial elevan la mandíbula actuando de forma simultánea sobre las caras lateral y medial de su rama. Sin embargo, los estudios electromiográficos indican que estos dos músculos actúan de forma diferente durante la masticación, de la misma forma que lo hacen las porciones superficial y profunda del músculo masetero. En el presente estudio hemos analizado mediante PCR en tiempo real la expresión de las isoformas de la cadena pesada de la miosina o myosin heavy chain (MHC) en los músculos masetero y pterigoideo medial en humanos, con la finalidad de identificar diferencias en los patrones de expresión que se puedan relacionar con las diferencias funcionales identificadas con la electromiografía. Nuestros resultados indican que el patrón de expresión de las isoformas de la MHC en los dos músculos es la característica de los músculos rápidos y potentes. También hemos observado un elevado porcentaje de expresión de la isoforma MHC-IIx y la expresión a nivel de ARNm de la isoforma MHC-M en los dos músculos, una isoforma que no se detecta a nivel de proteína en los músculos masticadores humanos. El elevado porcentaje de expresión de la isoforma MHC-IIx que hemos observado se puede relacionar con una elevada velocidad de contracción de los músculos masetero y pterigoideo medial en los humanos. Por otro lado, el bajo porcentaje de expresión de la isoforma MHC-M a nivel de ARNm en ambos músculos se puede relacionar con los procesos evolutivos complejos que han reducido el tamaño y la fuerza de los músculos masticadores en los humanos.

Do PML/RAR-alpha isoforms have clinical significance in patients with acute promyeloctyic leukemia? / 대한내과학회지

Acute promyelocytic leukemia (APL) is characterized by a specific t (15;17) translocation which produce a PML/RAR-alpha fusion messenger RNA and by effectiveness of all-trans retinoic acid (ATRA) differentiation therapy. Breakpoints within PML intron 3 (bcr 3) produce a short PML/RAR-alpha isoform (S-isoform), whereas breakpoints within PML intron 6 (bcr 1) result in a longer form (L-isoform). Additionally, breakpoints within PML exon 6 (bcr 2) make a variable length transcript (V-isoform) in a small number of patients. The influence of breakpoint site on patient outcome remains controversial. Previous reports showed that patients with S-isoform have an increased incidence of clinical relapse and shorter survival compared to those with L-isoform. Others reported no difference in DFS between these patients groups. In this issue, Lee et al. reported that there were 58 L-isoform (62.1%), 32 S-isoform (34.0%), 4 V-isoform (4.3%) and, no significant prognostic factor for EFS from induction therapy using anthracycline plus ATRA among 94 patients with APL. They concluded pretreatment clinical characteristics and treatment outcomes were not significantly different according to PML/RAR-alpha isoform types in this induction group. Recently, it was reported that FLT3/ITD mutation was frequently associated with S-isoform and with the M3v form of leukemia and CNS relapse in APL was mostly related to S-isoform. With previous studies including this article, outcomes of different types of PML/RAR-alpha isoforms are not conclusive. Future researches need to be focused not only on clinical outcomes of different types of PML/RAR-alpha isoforms, but also clinical relevance of PML/RARA-alpha mRNA isoforms with other prognostic factors and particular clinical characteristics.

Expression and biologic significance of human estrogen receptor-alpha and -beta, progesterone receptor A and B, androgen receptor in benign, borderline, and malignant epithelial ovarian tumors / 대한산부인과학회지

OBJECTIVE: The object of this study was to provide a better understanding of the roles played by sex hormones in ovarian carcinogenesis. METHODS: 1) The expressions of estrogen receptor-alpha and -beta, progesterone receptor A and B, androgen receptor in normal ovarian tissue, benign, borderline, and malignant ovarian tumor were analyzed using immunohistochemical stains. 2) Expression of mRNA of sex hormone receptors of cell lines from postmenopausal normal surface epithelial cells, ovarian cancer, and breast cancer were studied using real time quantitative PCR methods. 3) Expression of PR isoforms after treatment with estradiol, expression of AR after treatment with testosterone were analyzed using RT-PCR and immunoblotting methods. 4) Apoptosis after treatment with levonorgestrel in cell lines from ovarian cancer were analyzed using flowcytometry. RESULTS: There was no significant difference in results shown by immunohistochemical staining between sex hormonal receptors of normal ovarian tissue (n=8), benign tumor (n=10), borderline tumor (n=8) and malignant tumor (n=24) according to malignant change. But, PRA was significantly reduced in epithelial ovarian cancer. 1) Expressions of ER-alpha and ER-beta, PRA, PRB and AR mRNA were seen in normal ovarian epithelial cells. 2) Deletion of exons of ER-alpha, ER-alpha wild type and variant, ER-beta variant were seen in many cell lines. 3) Down regulation of PR mRNA isoforms (especially PRA) in cell lines of ovarian cancer. 4) Flowcytometry showed that apoptotic cells markedly increased during exposure of progestins in ovarian cancer cell lines. CONCLUSION: These results suggest that down-regulation of ER-alpha and PRA is associated with the development of ovarian epithelial carcinoma. Progestins can activate the apoptotic pathway in the ovarian epithelium for protection of normal tissue from neoplastic transformation suggests that progestins deserve further evaluation as potential ovarian cancer preventive agents.

Expression and Distribution of the Na+ : HCO3- Cotransporter(NBC) and K+ : Cl- Cotransporter(KCC) mRNA in Human Nasal Mucosa and Nasal Polyp / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Electrolyte transport by nasal epithelia has been suggested to be important for controlling the quantity and composition of the nasal fluid and may play an important role in the development of nasal polyps. Transepithelial transport of ion and water in various fluid-transporting epithelia is strictly dependent on the localization of specific membrane proteins in the polarized epithelial cells. Na+ : HCO3-cotransporter (NBC) transports Na+ and HCO3- into the intracellular from extracellular space and induces the evacuation of H+, regulating pH. K+ : Cl- cotransporter (KCC) controls the cell volume and resorption of NaCl which is associated with the extracellular transport of K+ and Cl-. The present study evaluated the presense of mRNA for NBC and KCC in human inferior turbinate and nasal polyp. MATERIALS AND METHOD: The expression of NBC and KCC mRNA isoforms in inferior turbinate mucosa and nasal polyp was evaluated, using RT-PCR and in situ hybridization. RESULTS: RT-PCR revealed that the inferior turbinate and nasal polyp mucosa expressed kNBC, KCC1 and 4 mRNA. In in situ hybridization, their distribution was noted in the epithelial layer and submucosal glands of both mucosa. CONCLUSION: These results indicate that these types of ion transporters are expressed in human nasal mucosa and nasal polyp, controlling the fluid and ion transport in nasal epithelium and submucosal glands.

Quantitative Analysis of Myosin Heavy Chain (MHC) mRNA expression in Thyropharyngeus muscle and Cricopharyngeus muscle in Rats / 대한이비인후과학회지

BACKGROUNDS: The inferior pharyngeal constrictor muscle (IPC), which consists of the thyropharyngeus (TP) and cricopharyngeus (CP) muscles, plays an important role during deglutition, but their function is different when analysed by radiographic, manometric and electromyographic studies. OBJECTIVES AND MATERIALS: The purpose of this study is to quantify the expression levels of MHC mRNA isoforms (2B, 2X, 2A, 2L, beta-cardiac, neonatal and embryonic) in thyropharyngeus and cricopharyngeus muscles of rats using competitive PCR. RESULTS: The thyropharyngeus muscle was mainly consisted of three fast-twitching MHC isoforms, mostly 2X isoform (85.2%). On the other hand, the cricopharyngeus muscle contained two-third of fast-twitching isoforms(65.1%) and one-third of neonatal MHC(34.9%). CONCLUSIONS: The thyropharyngeus muscle could be characterized as a fast-twitching muscle and the cricopharyngeus muscle is probably considered as a sarcomeric regenerating muscle that is caused by frequently mechanical damage on deglutition.