CACNA1H variants are not a cause of monogenic epilepsy

CACNA1H genetic variants were originally reported in a childhood absence epilepsy cohort. Subsequently, genetic testing for CACNA1H became available and is currently offered by commercial laboratories. However, the current status of CACNA1H as a monogenic cause of epilepsy is controversial, highlighted by ClinGen's recent reclassification of CACNA1H as disputed. We analyzed published CACNA1H variants and those reported in ClinVar and found none would be classified as pathogenic or likely pathogenic per the American College of Medical Genetics classification criteria. Moreover, Cacna1h did not modify survival in a Dravet Syndrome mouse model. We observed a mild increase in susceptibility to hyperthermia‐induced seizures in mice with reduced Cacna1h expression. Overall, we conclude that there is limited evidence that CACNA1H is a monogenic cause of epilepsy in humans and that this gene should be removed from commercial genetic testing panels to reduce the burden of variants of uncertain significance for healthcare providers, families and patients with epilepsy.     

A Human Cadaver Fascial Compartment Pressure Measurement Model

Background

Fresh human cadavers provide an effective model for procedural training. Currently, there are no realistic models to teach fascial compartment pressure measurement.

Objectives

We created a human cadaver fascial compartment pressure measurement model and studied its feasibility with a pre-post design.

Methods

Three faculty members, following instructions from a common procedure textbook, used a standard handheld intra-compartment pressure monitor (Stryker^®, Kalamazoo, MI) to measure baseline pressures (“unembalmed”) in the anterior, lateral, deep posterior, and superficial posterior compartments of the lower legs of a fresh human cadaver. The right femoral artery was then identified by superficial dissection, cannulated distally towards the lower leg, and connected to a standard embalming machine. After a 5-min infusion, the same three faculty members re-measured pressures (“embalmed”) of the same compartments on the cannulated right leg. Unembalmed and embalmed readings for each compartment, and baseline readings for each leg, were compared using a two-sided paired t-test.

Results

The mean baseline compartment pressures did not differ between the right and left legs. Using the embalming machine, compartment pressure readings increased significantly over baseline for three of four fascial compartments; all in mm Hg (±SD): anterior from 40 (±9) to 143 (±44) (p = 0.08); lateral from 22 (±2.5) to 160 (±4.3) (p < 0.01); deep posterior from 34 (±7.9) to 161 (±15) (p < 0.01); superficial posterior from 33 (±0) to 140 (±13) (p < 0.01).

Conclusion

We created a novel and measurable fascial compartment pressure measurement model in a fresh human cadaver using a standard embalming machine. Set-up is minimal and the model can be incorporated into teaching curricula.     

Does spasticity result from hyperactive stretch reflexes? Preliminary findings from a stretch reflex characterization study

Purpose:?To characterize the stretch reflex response of the biceps brachii in stroke patients with elbow spasticity (prior to or within 15?min of treatment with botulinum toxin) and non-impaired volunteers with the aim of quantifying the stretch reflex excitability and observe the differences between the groups.

Methods:?A cross-sectional study. Stretch reflexes from the biceps brachii were elicited following a controlled elbow extension. The amplitude, latency, rise time and duration, calculated from surface EMG recordings from the biceps brachii, were used to characterize the stretch reflex response.

Results:?Seventeen non-impaired and 14 stroke patients participated. The amplitude was significantly lower in stroke patients than in non-impaired volunteers (p?<?0.05). The latency was significantly shorter in stroke patients than in non-impaired volunteers (p?<?0.05). There were no significant differences in rise time or duration (p?>?0.10).

Discussion:?Reduction in the amplitude in stroke patients was unexpected suggesting the stretch reflex is not necessarily hyper-excitable in people with clinically diagnosed spasticity. Latency differences suggest decreased presynaptic inhibition and/or increased motor neurone excitability can occur following a stroke. However, carry over effects from previous botulinum toxin treatment may have confounded amplitude measurements. Further work evaluating the excitability of the stretch reflex independent of Botulinum toxin and its contribution to resistance to passive stretching is being conducted.     

Assessing diagnosis in heart failure: which features are any use?

We assessed the value of symptoms, past history, medications and signs in the evaluation of patients who might have heart failure secondary to left ventricular systolic dysfunction. An open-access echocardiography service was set up to help identify patients with left ventricular systolic dysfunction who might benefit from treatment with an angiotensin-converting-enzyme inhibitor. History and examination were recorded for each of these patients. The patients were divided into groups according to whether left ventricular systolic function was preserved or not and whether various clinical features were present or not. Of 259 consecutive patients studied, 41 had impairment of left ventricular systolic function as assessed by echocardiography. Past history of myocardial infarction and displaced apex beat were the best single predictors of left ventricular systolic dysfunction as assessed by echocardiography. The combination of past history of myocardial infarction and displaced apex had the best positive predictive value of all. Patients with such clinical features or combinations of clinical features may not need echocardiography, and where access to this resource is limited, it could be reserved for patients without such diagnostic features.      

Calcium-alginate beads for the oral delivery of transforming growth factor-β1 (TGF-β1): stabilization of TGF-β1 by the addition of polyacrylic acid within acid-treated beads

The susceptibility of the gastrointestinal tract to the toxic effects of chemotherapeutic drugs remains a complication in chemotherapy. Recent studies have suggested that transforming growth factor-β₁ (TGF-β₁) can be used as a cytoprotectant against cell cycle specific drugs. This work describes the use of alginate beads as a potential oral delivery system for TGF-β₁ designed to release the drug in the lumen of the small intestine. TGF-β₁ encapsulation and extent of release from alginate beads approached 100% as determined by ¹²⁵I-labelled TGF-β₁. However, when assayed by ELISA and a growth inhibition assay, nearly all immunoreactivity and bioactivity was lost, apparently due to a very high affinity of the alginate for TGF-β₁. This limitation was overcome by two novel methods: (1) incorporation of selected polyanions within the alginate beads to ‘shield’ TGF-β₁ from interaction with alginate and (2) exposure of the alginate beads containing TGF-β₁ to 0.1 N HCl (acid treatment) to simultaneously reduce the molecular weight of the alginate and its ability to interact with TGF- β₁. If the beads were only acid treated, just 8% of the immunoreactivity ofTGF-β₁ was retained. If polyacrylic acid (90 kDa) was added to the beads, 50% of the immunoreactivity of TGF-β₁ was retained. However, when TGF-β₁ was released from acid-treated beads also containing polyacrylic acid, more than 80% of the TGF-β₁ remained immunoreactive and bioactive. The retained TGF-β₁ activity after release from the beads was found to continue to increase with increasing concentrations of polyacrylic acid, until a concentration was reached where beads would not form. The dramatic increase in retained TGF-β₁ activity is attributed to the ability of polyacrylic acid to shield TGF-β₁ from interaction with lower molecular fragments of alginate.