Mechanism for Mechanical Wave Break in the Heart Muscle.

Using a reaction-diffusion-mechanics model we identify a mechanism for mechanical wave break in the heart muscle. For a wide range of strengths and durations an external mechanical load causes wave front dissipation leading to formation and breakup of spiral waves. We explain the mechanism, and discuss under which conditions it can cause or abolish cardiac arrhythmias.

Emergence of spiral wave activity in a mechanically heterogeneous reaction-diffusion-mechanics system.

We perform a numerical study of emergent spiral wave activity in a two-dimensional reaction-diffusion-mechanics medium with a regional inhomogeneity in active and passive mechanical properties. We find that self-sustaining spiral wave activity emerges for a wide range of mechanical parameters of the inhomogeneity via five mechanisms. We classify these mechanisms, relate them to parameters of the inhomogeneity, and discuss how these results can be applied to understand the onset of cardiac arrhythmias due to regional mechanical heterogeneity.

Seizures in Children with HIV infection in South Africa: A retrospective case control study.

PURPOSE: Data relating to the role that Human immunodeficiency virus (HIV) contributes towards seizures in HIV-infected children is limited. The management of seizures in this group is complex due to potential interactions between antiseizure medication and antiretroviral therapies. This study explores the seizure semiology and course of a population of affected children based on questions raised from a previous epidemiological study. METHODS: A retrospective case-control study of all patients presenting to an HIV neurology clinic between 2008-2015 was conducted. A multinomial logistic regression model was used to identify risk factors for seizure occurrence in HIV-infected children, as well as factors associated with seizure control. RESULTS: Of 227 HIV-infected children (median 82 months, interquartile range 41-109), 52 (23%) reported a past or present history of seizures. Prior bacterial meningitis (p = 0.03, OR 12.5, 95% CI 1.2-136.1), cerebrovascular accident (CVA, p = 0. 005, OR 8.1, 95% CI 1.9-34.9) and or tuberculous meningitis (TBM, p = 0.0004) was associated with an increased risk of seizures in HIV-infected children. Generalised tonic-clonic seizures were the predominant seizure type (64%) with the majority caused by an infectious aetiology (62%). Thirty-two (62%) of these patients had epilepsy in-line with the latest diagnostic criteria. HIV-infected children with epilepsy who were treated with efavirenz were more likely to have poor seizure control (OR 23.1 95% CI 3.4-159.6, p = 0.0001). CONCLUSIONS: This study provides new data highlighting the complex clinical presentation and management challenges of HIV-infected children with seizures.

Differentiated plasma cell myeloma presenting as a solitary spinal amyloidoma: a case report, possible pitfall and review to the literature.

OBJECTIVE: Solitary spinal amyloidoma is a rare entity. Amyloidomas consist of extracellular amyloid deposits with an insoluble beta-pleated proteinaceous material. Although amyloidomas are slow growing lesions, they may lead to a progressive spinal cord or nerve root compression. Moreover amyloidoma results in destruction of bone with consequence of progressive osteolysis. METHOD: This study is a case presentation and review of the literature and should point out the need to explore any underlying diseases to guarantee the best therapy for the affected patient. In this case report we present a female patient with high-level paraparesis and lumbar stenosis in L2-L3 with combined spondylolisthesis (ASIA Impairemet Scale C). Paraparesis increased shortly after lumbar osteosynthesis. Contrast-enhanced MRI of the thoracic spine revealed medullary compression at the D5 level due to an epidural and paraspinal mass with concomitant bone infiltration. Operative decompression followed. Histopathological examination initially revealed amyloidoma. Finally the lesion was classified as a plasma cell myeloma. RESULTS: Plasma cell myeloma may rarely present as a solitary amyloidoma in the initial pathological examination with the potential to cause spinal cord compression associated to osteolytic lesions of the spine. CONCLUSION: A thorough pathological work-up is mandatory in order to rule out differential diagnosis and exclude possible underlying diseases.

The effects of scopolamine on memory for time in rats and pigeons.

In Experiment 1, pigeons were trained to match short (2 s) and long (8 s) sample durations to red and green comparison stimuli and red and green samples to vertical and horizontal line comparisons. They received injections of scopolamine hydrobromide (0.02 mg/kg), scopolamine methylbromide (0.02 mg/kg), or saline, and the delay interval was manipulated (0, 1, 3, and 9 s). In Experiment 2, rats were trained to discriminate short (2 s) or long (12 s) durations of house-light illumination using a choice procedure. During the test phase of each trial, the left and right levers were presented with the cue light on above one of them (cued lever) while the other was off (uncued lever). For half of the rats, the correct response following the short sample was to press the cued lever, whereas following the long sample, it was to press the uncued lever. This was reversed for the remaining rats. The rats received injections of scopolamine hydrobromide (0.15 mg/kg), scopolamine methylbromide (0.15 mg/kg), or saline, and the delay interval was manipulated (0, 1, 3, and 9 s). In pigeons, scopolamine equivalently disrupted both temporal and nontemporal memory. Memory for time, in both rats and pigeons, was significantly poorer following scopolamine injections than following methylscopolamine or saline injections. No choose-short effect was observed in either rats or pigeons during saline test sessions. The data indicate that central cholinergic blockade in both pigeons and rats disrupts the accuracy of delayed temporal discriminations. However, scopolamine does not appear to accelerate the rate at which memory for temporal events is foreshortened.

[Surgical treatment of hepatic alveolar echinococcosis]. / Chirurgische Therapie beim Echinococcus alveolaris der Leber.

INTRODUCTION: Alveolar hydatid disease is an uncommon parasitosis found in the northern hemisphere, caused by the larval stage of a tapeworm growing in the liver: Echinococcus multilocularis. It behaves like a malignant tumor, producing liver necrosis and invading the biliary tract, main vessels and surrounding structures. METHODS: Review of the different therapeutic approaches in hepatic alveolar echinococcosis over 21 years in an epidemic area. RESULTS: The various surgical approaches (all types of hepatectomy, palliative surgical procedures and liver transplantation) were combined with medical, endoscopic and radiological interventional treatment. Recently, asymptomatic forms were more frequently encountered. CONCLUSIONS: The wide use of ultrasonography and specific serological tests have led to early diagnosis, allowing more curative hepatectomies.

The tremor network targeted by successful VIM deep brain stimulation in humans.

OBJECTIVE: Deep brain stimulation (DBS) of the ventral intermediate nucleus of thalamus (VIM) is a treatment option in medically intractable tremor, such as essential tremor or tremor-dominant Parkinson disease (PD). Although functional studies demonstrated modulation of remote regions, the structural network supporting this is as yet unknown. In this observational study, we analyzed the network mediating clinical tremor modulation. METHODS: We studied 12 patients undergoing VIM stimulation for debilitating tremor. We initiated noninvasive diffusion tractography from tremor-suppressive VIM electrode contacts. Moreover, we tested for the contribution of primary motor projections in this structural correlate of a functional tremor network, comparing the connectivity of effective DBS contacts with those of adjacent, but clinically ineffective, stimulation sites. RESULTS: VIM stimulation resulted in decrease of tremor and improvement in quality of life. Tractography initiated from the effective stimulation site reconstructed a highly reproducible network of structural connectivity comprising motor cortical, subcortical, and cerebellar sites and the brainstem, forming the anatomic basis for remote effects of VIM stimulation. This network is congruent with functional imaging studies in humans and with thalamic projections found in the animal literature. Connectivity to the primary motor cortex seemed to play a key role in successful stimulation. CONCLUSIONS: Patients undergoing DBS provide a unique opportunity to assess an electrophysiologically defined seed region in human thalamus, a technique that is usually restricted to animal research. In the future, preoperative tractography could aid with stereotactic planning of individual subcortical target points for stimulation in tremor and in other disease entities.

Debridement and spinal instrumentation as a single-stage procedure in bacterial spondylitis/spondylodiscitis.

OBJECT: The best surgical technique for patients with bacterial spinal infections is still discussed controversially. But recent publications suggest that titanium implants can be used safely in infectious sites in combination with debridement and antibiotic therapy. The purpose of this study is to provide further evidence in support of debridement and instrumentation as a single-stage procedure for spinal infection. METHODS: Twenty-four cases with cervical, thoracic, and lumbar spondylitis/spondylodiscitis were analyzed. In 17 cases, anterolateral stabilization was performed with titanium cages. No autologous or homologous bone grafts were used. Transpedicular screw/rod fixation following posterior debridement of the intervertebral space was performed in the other 7 cases. RESULTS: WBC and C-reactive protein levels decreased significantly after surgical debridement. Pain levels decreased from a preoperative median of 4 (on the Denis Pain Scale) to a postoperative median of 2. Twenty-two of the 24 patients were fully mobilized within 2 weeks after surgery. The Barthel Index improved from 60 (10-85) before surgery to 90 (65-100) after surgery. No recurrence of the initial infection was noticed during a mean follow-up period of 18 months. The fusion rate was 90.5%. The mortality rate was 1 out of 24 (4.2%). CONCLUSIONS: These findings support the position that debridement and instrumented fusion can be performed as a single-stage procedure without an increase in the recurrence rate or morbidity, compared with the use of autologous bone grafting or staged procedures. Same-stage instrumentation allows early postoperative mobilization of the patient, which is advantageous, especially for an increasingly elderly population and in patients with comorbidities.

[Perspective of tuberculosis control--role of preventive chemotherapy (author's transl)]. / Perspektiven der Tuberkulosebekämpfung--Rolle der präventiven Chemotherapie.

After a short review of measures for control and eradication of infectious diseases in general and especially of tuberculosis, the indications of chemoprophylaxis and preventive chemotherapy of tuberculosis are discussed. Using results of a double-blind controlled trial on preventive chemotherapy in a high risk group (persons with fibrotic lung lesions), cost, benefit and side effects of preventive chemotherapy are analysed. Preventive chemotherapy in high risk persons is an effective measure in advanced stage of tuberculosis control. Recommendations to reduce side effects are given.

[Whipple's disease]. / Ein Beitrag zum Morbus Whipple.

With regard to three cases, one of them relapsing after four years, a short survey on Whipples's disease is given. The 3 male patients of medium age suffered from malabsorption and foregoing arthralgia. These symptoms are typical. In most cases first of all chronic infectious or neoplastic diseases are taken into consideration. The finding of PAS-positive macrophages in biopsies of the duodenal mucosa is key to the diagnosis, allowing the successful antibiotic therapy, with preference to oxytetracyline.

[The frequency and form of manifestation of liver damage under INH therapy]. / Uber die Häufigkeit und Manifestationsform von Leberschädigungen unter INH-Therapie

It is reported on 305 clinically examined patients with the diagnosis of a functional colon syndrome. In 65 patients somatic diseases were found to be the possible triggering factors. In contrast to a comparative group in the other 240 patients in the former anamnesis more frequently allergies, appendectomies and chronic application of purgatives were to be established. The most frequent complaints were irregularity of defaecation in form of spastic obstipation (62.9%) or diarrhoea (35.4%), intolerance to foodstuff (100%), pain in the colon(66.7%) and meteorism (65.4%). The 4th decennium was most frequently concerned in men as well as in women.

Genetic determinants of drug-induced agranulocytosis: potential risk of olanzapine?

Whether or not olanzapine causes bone marrow toxicity is still a matter of debate. In spite of pre-marketing and post-marketing clinical trials, and although there have been no cases in animals of olanzapine-induced neutropenia or agranulocytosis, the risk of bone marrow toxicity cannot be excluded. The present paper addresses the following questions: what is the potential background of drug-induced agranulocytosis? Are there any case reports supporting the view that olanzapine has relevant bone marrow toxicity? What strategies might be helpful in identifying the pathological mechanisms underlying this side effect?