Pathophysiology of spasticity

Neurological Sciences - Spasticity arises from lesions involving the corticoreticulospinal system in the brain, brainstem or spinal cord. Abnormal suprasegmental influences lead to increased spinal...     

Development of an ELISA test for determination of the urinary trypsin inhibitor: analytical performance and applications

Increased urinary excretion of urinary trypsin inhibitor (UTI) has been reported in various inflammatory conditions and in Alzheimer's subjects, but its diagnostic potential remains to be elucidated. A reliable and specific enzyme-linked immunosorbent assay (ELISA) test for the determination of the UTI in human urine was developed. This assay was performed using 96-well microtiter plates. The plate surface is coated with an anti-UTI polyclonal antibody, the urine sample was added in a dilution range, and the detection was achieved using the enzyme-conjugated antibody. The assay was quantified by the build-up of colored product upon the addition of the substrate. Recoveries were 93%, and the intra- and inter-assay CVs were 4.25% and 21%, respectively. The ELISA showed parallelism of standard and urine samples and no significant interference by the biological matrix. The usefulness of the assay has been demonstrated by applying it to urine samples from Alzheimer's disease patients, and comparing with negative controls. UTI urinary levels are significantly increased in Alzheimer's subjects.     

Central nervous system involvement in systemic lupus erythematosus: a new therapeutic approach with intrathecal dexamethasone and methotrexate

Summary In systemic lupus erythematosus (SLE), neurological involvement has been reported to occur with frequencies ranging from 14% (severe cases) to 83% (mild forms included). In spite of early diagnosis and aggressive treatment, neuropsychiatric SLE may represent a serious problem of management. We describe three cases, one with acute transverse myelitis, one with hemiparesis, and one with signs of focal and diffuse cerebral dysfunction, in whom improvement following intrathecal therapy with methotrexate and dexamethasone was observed.     

Abnormal calcium signaling and sudden cardiac death associated with mutation of calsequestrin

Mutations in human cardiac calsequestrin (CASQ2), a high-capacity calcium-binding protein located in the sarcoplasmic reticulum (SR), have recently been linked to effort-induced ventricular arrhythmia and sudden death (catecholaminergic polymorphic ventricular tachycardia). However, the precise mechanisms through which these mutations affect SR function and lead to arrhythmia are presently unknown. In this study, we explored the effect of adenoviral-directed expression of a canine CASQ2 protein carrying the catecholaminergic polymorphic ventricular tachycardia-linked mutation D307H (CASQ2(D307H)) on Ca2+ signaling in adult rat myocytes. Total CASQ2 protein levels were consistently elevated approximately 4-fold in cells infected with adenoviruses expressing either wild-type CASQ2 (CASQ2(WT)) or CASQ2(D307H). Expression of CASQ2(D307H) reduced the Ca2+ storing capacity of the SR. In addition, the amplitude, duration, and rise time of macroscopic I(Ca)-induced Ca2+ transients and of spontaneous Ca2+ sparks were reduced significantly in myocytes expressing CASQ2(D307H). Myocytes expressing CASQ2(D307H) also displayed drastic disturbances of rhythmic oscillations in [Ca2+]i and membrane potential, with signs of delayed afterdepolarizations when undergoing periodic pacing and exposed to isoproterenol. Importantly, normal rhythmic activity was restored by loading the SR with the low-affinity Ca2+ buffer, citrate. Our data suggest that the arrhythmogenic CASQ2(D307H) mutation impairs SR Ca2+ storing and release functions and destabilizes the Ca2+-induced Ca2+ release mechanism by reducing the effective Ca2+ buffering inside the SR and/or by altering the responsiveness of the Ca2+ release channel complex to luminal Ca2+. These results establish at the cellular level the pathological link between CASQ2 mutations and the predisposition to adrenergically mediated arrhythmias observed in patients carrying CASQ2 defects.     

Unexpected structural and functional consequences of the R33Q homozygous mutation in cardiac calsequestrin: a complex arrhythmogenic cascade in a knock in mouse model

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmogenic disorder characterized by life threatening arrhythmias elicited by physical and emotional stress in young individuals. The recessive form of CPVT is associated with mutation in the cardiac calsequestrin gene (CASQ2). We engineered and characterized a homozygous CASQ2(R33Q/R33Q) mouse model that closely mimics the clinical phenotype of CPVT patients. CASQ2(R33Q/R33Q) mice develop bidirectional VT on exposure to environmental stress whereas CASQ2(R33Q/R33Q) myocytes show reduction of the sarcoplasmic reticulum (SR) calcium content, adrenergically mediated delayed (DADs) and early (EADs) afterdepolarizations leading to triggered activity. Furthermore triadin, junctin, and CASQ2-R33Q proteins are significantly decreased in knock-in mice despite normal levels of mRNA, whereas the ryanodine receptor (RyR2), calreticulin, phospholamban, and SERCA2a-ATPase are not changed. Trypsin digestion studies show increased susceptibility to proteolysis of mutant CASQ2. Despite normal histology, CASQ2(R33Q/R33Q) hearts display ultrastructural changes such as disarray of junctional electron-dense material, referable to CASQ2 polymers, dilatation of junctional SR, yet normal total SR volume. Based on the foregoings, we propose that the phenotype of the CASQ2(R33Q/R33Q) CPVT mouse model is portrayed by an unexpected set of abnormalities including (1) reduced CASQ2 content, possibly attributable to increased degradation of CASQ2-R33Q, (2) reduction of SR calcium content, (3) dilatation of junctional SR, and (4) impaired clustering of mutant CASQ2.     

Pancreolauryl Test for Pancreatic Exocrine Insufficiency

Pancreolauryl test (PLT), a tubeless pancreatic function test, was performed in 40 consecutive patients suffering from chronic pancreatitis, in 21 patients with miscellaneous digestive diseases, and in 18 control subjects to assess its diagnostic sensitivity and specificity. N-benzoyl- l -tyrosyl- p -aminobenzoic acid test (PABA test) and sccretin-cerulein test were also carried out to compare the diagnostic value of PLT with that of these two pancreatic function tests. PLT was abnormal in 22 of 40 patients with chronic pancreatitis (55%). In particular, pathological results were found in all patients with severe pancreatic insufficiency and only in four of 14 patients with mild to moderate insuffieiency. PABA test showed a slightly lower sensitivity in severe insufficiency, and the same sensitivity in mild-moderate insufficiency. PLT was normal in ail control subjects and in 17 of 21 patients with nonpancreatic digestive diseases. Its specificity (90%) was slightly higher than that of PABA test (82%). The results indicate that PLT may be used to support a diagnosis of severe panereatic exocrine insufficiency, while in mild or moderate insufficiency its diagnostic value is limited.     

Precision Medicine in Catecholaminergic Polymorphic Ventricular Tachycardia: JACC Focus Seminar 5/5

In this final of a 5-part Focus Seminar series on precision medicine, we focus on catecholaminergic polymorphic ventricular tachycardia (CPVT). This focus on CPVT allows us to take a “deep dive” and explore the full extent of the precision medicine opportunities for a single cardiovascular condition at a level that was not possible in the preceding articles. As a new paradigm presented in this article, it has become clear that CPVT can occur as either a typical or atypical form. Although there is a degree of overlap between the typical and atypical forms, it is notable that they arise due to different underlying genetic changes, likely exhibiting differing mechanisms of action, and presenting with different phenotypic features. The recognition of these differing forms of CPVT and their different etiologies and mechanisms is an important step toward implementing rapidly emerging precision medicine approaches that will tailor novel therapies to specific gene defects.     

Familial autoimmunity as a risk factor for systemic lupus erythematosus and vice versa: a case-control study

The objective of this multicentric case-control study was to investigate if a history of autoimmune disease (AD) in first-degree relatives (FDR) is a risk factor for systemic lupus erythematosus (SLE) and to evaluate the risk of AD among FDR of SLE patients. Cases were Italian SLE patients consecutively enrolled. Controls were orthopaedic inpatients without any autoimmune diseases. The strength of the association between family history of AD and SLE was measured as an odds ratio (OR) calculated from the coefficient of an unconditional regression model. To calculate the risk of AD among FDR of SLE patients, the extended generalized estimating equation technique was used. In total, 154 SLE cases and 140 controls were enrolled. A family history of AD was reported by 22.7% of SLE patients and by 5.7% of the controls. The risk of SLE increased with the number of FDR with AD (one FDR affected, OR = 4.1; two or more, OR = 11.3). The probability of having AD was higher among FDR of SLE cases in comparison to FDR of controls (RR = 4.6; 95%CI 1.9-11.1). A female SLE patient conferred an increased risk of AD to her FDR; this risk is doubled in females (OR 10.3; 95% CI 3.1-34.4).