Progress of CACNA1S Gene and Hypokalemic Periodic Paralysis

CACNA1 S gene is the gene encoding L-type calcium channel αa-subunit. CACNA1 S gene mutations can cause hypokalemic periodic pa- ralysis （HOKPP）. The related research speculated that CACNA1 S gene was the candidate genes which affect meat quality traits. In the present ar- ticle, the biological characteristics of CACNA1 S gene, structure, genetic diseases and the research development were respectively reviewed so as to provide a reference for further research.

A CLINICAL AND NEUROELECTROPHYSIOLOGICAL STUDY OF HYPERKALEMIC PERIODIC PARALYSIS

A case of atypical hyperkalemic periodic paralysis is reported. The diagnosis was confirmed by hyperkalemic test, cold water test, and differentiation of attack period and rest period by the measurement of motor nerve conduction amplitude. Etio-pathology of this disease is discussed from the view of neuroelectrophysiology.

Exercise test on the patients with normokalaemic periodic paralysis from a Chinese family with a mutation in the SCN4A gene

Background Normokalaemic periodic paralysis （normoKPP） is characterized by transient and recurrent myoasthenia, and some patients also show muscle stiffness induced by cold exposure （paramyotonia congenita, PMC）. It is caused by a mutation in the muscle voltage gated sodium channel alpha subunit （SCN4A） gene. Due to the diversity of the clinical manifestations of patients, it is difficult for clinicians to differentiate some of patients with atypical normoKPP from those who suffer from other periodic paralysis and nondystrophic myotonia. So far, for normoKPP there are almost no ways to assist definite diagnosis besides genetic screening. This research was designed to evaluate an exercise test （ET） in confirming the diagnosis of normoKPP and in assessing the therapeutic effectiveness of some drugs on this disease. Methods ET, described by McMains, was performed on six subjects from a Chinese family, including four patients with overlapping disease of normoKPP and PMC caused by a mutation of SCN4A Met1592Val that is identified by genetic analysis and two normal control members. The change of compound muscle action potential （CMAP） was recorded. Besides the family, two patients were also tested during treatments with acetazolamide. Results All patients showed a slight increase in CMAP immediately after exercise, followed by an abnormal gradual decline, which reached its nadir 25-30 minutes after exercise. CMAP amplitude dropped by more than 40% in patients but less than 23% in controls. In the patients who received treatment with acetazolamide, the change of CMAP amplitude was less than 28% and, at any fixed times, less than pretreatment values. Conclusions The ET may be used as a predictive, easy and reliable method of diagnosing normoKPP under conditions without genetic screening help, and is an objective way to evaluate the therapeutic effectiveness. According to different response patterns, the ET may also be helpful in reducing the scope of genetic screening.

Reference value of long-time exercise test in the diagnosis of primary periodic paralysis

Background The long-time exercise test （ET） is used to diagnose the primary periodic paralyses （PPs）.However the reference values of ET are many and various.This study aimed to investigate the reference value of long-time ET in the diagnosis of PPs.Methods We recruited 108 healthy subjects,68 patients with PPs,and 72 patients with other diseases for the study.The procedure of ET was made on the basis of the McManis＆#39; method.Electrical responses were recorded from right abductor digiti minimi （ADM） muscle when stimulation of the ulnar nerve at the wrist.After the compound muscle action potential （CMAP） was monitored,subjects were then asked to contract the muscle as strongly as possible for 5 minutes.CMAPs were recorded for 2 seconds immediately after cessation of exercise,then every 5 minutes for 10 minutes,and finally every 10 minutes for 50 minutes.In general,the CMAP amplitudes will fall below the pre-exercise levels in an hour.The largest decrease was calculated and used as results of ET.Results The CMAP amplitude decreases had no significant differences between groups when the healthy adults were grouped according to age,gender,height,weight and test time.Decreases in PPs patients （57.76%） were significantly more than in healthy subjects （15.21%） and other disease patients （18.10%,P 〈0.001）.Receiver operating characteristic （ROC） curve analysis showed that the best threshold is 35.50%.Conclusions In the long-time exercise test,threshold of 35.50% for the CMAP amplitude decrease was identified for abnormal.The result is not influenced by age,gender,height,weight,and test time.About 7.4% of healthy subjects were abnormal in ET.

Acute myocarditis presenting as accelerated junctional rhythm in Graves’disease:A case report

BACKGROUND Acute myocarditis is an acute myocardium injury that manifests as arrhythmia,dyspnea,and elevated cardiac enzymes.Acute myocarditis is usually caused by a viral infection but can sometimes be caused by autoimmunity.Graves’disease is an autoimmune disease that is a rare etiology of acute myocarditis.Accelerated junctional rhythm is also a rare manifestation of acute myocarditis in adults.CASE SUMMARY A rare case of new-onset Graves’disease combined with acute myocarditis and thyrotoxic periodic paralysis is reported.The patient was a 25-year-old young man who suddenly became paralyzed and felt palpitations and dyspnea.He was then sent to our emergency department(ED).Upon arrival,electrocardiography revealed an accelerated junctional rhythm and ST-segment depression in all leads,and laboratory findings showed extreme hypokalemia and elevated troponin I,with the troponin I level being 0.32 ng/mL(reference range,0-0.06 ng/mL).Coronary computer tomography angiography was performed,and there were no abnormal findings in the coronary arteries.Subsequently,the patient was admitted to the ED ward,where further testing revealed Graves’disease,along with continued elevated cardiac enzyme levels and B-type natriuretic peptide(BNP)levels.The troponin I level was 0.24 ng/mL after admission.All of the echocardiography results were normal:Left atrium 35 mm,left ventricle 48 mm,end-diastolic volume 102 mL,right atrium 39 mm×47 mm,right ventricle 25 mm,and ejection fraction 60%.Cardiac magnetic resonance was performed on the fifth day of admission,revealing myocardial edema in the lateral wall and intramyocardial and subepicardial late gadolinium enhancement in the lateral apex,anterior lateral,and inferior lateral segments of the ventricle.The patient refused to undergo an endomyocardial biopsy.After 6 d,the patient’s cardiac enzymes,BNP,potassium,and electrocardiography returned to normal.After the patient’s symptoms were relieved,he was discharged from the hospital.During a 6-mo follow-up,the patient was asymptomatic and subjected to thyroid function,liver function,kidney function,troponin I,and electrocardiograph routine tests for medicine adjustments.The hyperthyroid state was controlled.CONCLUSION Acute myocarditis is a rare manifestation of Graves’disease.Accelerated junctional rhythm is also a rare manifestation of acute myocarditis in adults.When the reason for hypokalemia and elevated cardiac enzymes in patients is unknown,cardiologists should consider Graves’disease and also pay attention to accelerated junctional rhythm.

Immobility Responses Affected by Potassium in Old Rats

Four immobility responses (IR): elicited by clamping, bandaging, grasping and inversion, and their modification by potassium and spironolactone was studied in old Wistar rats (body weight, 500 g). When undrugged, only clamping and grasping, but not bandaging and inversion induced an IR in rats. Potassium and spironolactone significantly enhanced the duration of IR induced by clamping but not by grasping. They also induced an immobility response by bandaging, but not by inversion. The data suggest that IR induced by clamping and bandaging are somehow related to changes in the potassium serum levels. Consequently, such a relationship may be a suitable model to study some forms of paralysis in human beings which are related to changes in the potassium serum levels.