Long-term Effects of Botulinum Toxin on Neuromuscular Function

Background: Recent reports indicate increased incidence of Clostridium botulinum infections, particularly among drug abusers and tissue allograft recipients. Botulinum toxin also has potential application in biochemical warfare. The neurotoxin-induced paralysis often requires mechanical ventilation with and without muscle relaxants. The authors investigated the long-term effects of botulinum toxin on muscle function, expression of nicotinic acetylcholine receptors (nAChRs), and their interaction with muscle relaxant, atracurium.

Methods: Rats (n = 30) were injected with varying doses (0.625, 2.5, and 10 U) of botulinum toxin into the tibialis muscle. Control animals (n = 9) received an equivalent volume of saline. At 128 days after injection, neuromuscular function, pharmacodynamics of atracurium, and nAChRs were evaluated.

Results: Nerve-evoked tensions, including tetanic tension and muscle mass, were decreased on the toxin-injected side in a dose-dependent manner relative to saline-injected controls as well as the contralateral side. Specific muscle tension and specific tetanic muscle tension (tensions/muscle mass) were not reduced. The ED10 of atracurium was reduced, the ED50 was unchanged, and the ED90 was increased in the highest (10-U) dose of toxin group. The atracurium plasma concentration to maintain a steady state 50% paralysis was significantly reduced in the 10-U toxin group. The nAChR concentrations in the tibialis muscle were significantly increased in a dose-dependent manner in all experimental groups.     

In vitro characterization of SLV308 (7-[4-methyl-1-piperazinyl]-2(3H)-benzoxazolone, monohydrochloride): a novel partial dopamine D2 and D3 receptor agonist and serotonin 5-HT1A receptor agonist

Present Parkinson's disease treatment strategies are far from ideal for a variety of reasons; it has therefore been suggested that partial dopamine receptor agonism might be a potential therapeutic approach with potentially fewer side effects. In the present study, we describe the in vitro characterization of the nonergot ligand SLV308 (7-[4-methyl-1-piperazinyl]-2(3H)-benzoxazolonemonohydrochloride). SLV308 binds to dopamine D(2), D(3), and D(4) receptors and 5-HT(1) (A) receptors and is a partial agonist at dopamine D(2) and D(3) receptors and a full agonist at serotonin 5-HT(1) (A) receptors. At cloned human dopamine D(2,L) receptors, SLV308 acted as a potent but partial D(2) receptor agonist (pEC(50) = 8.0 and pA(2) = 8.4) with an efficacy of 50% on forskolin stimulated cAMP accumulation. At human recombinant dopamine D(3) receptors, SLV308 acted as a partial agonist in the induction of [(35)S]GTPgammaS binding (intrinsic activity of 67%; pEC(50) = 9.2) and antagonized the dopamine induction of [(35)S]GTPgammaS binding (pA(2) = 9.0). SLV308 acted as a full 5-HT(1) (A) receptor agonist on forskolin induced cAMP accumulation at cloned human 5-HT(1) (A) receptors but with low potency (pEC(50) = 6.3). In rat striatal slices SLV308 concentration-dependently attenuated forskolin stimulated accumulation of cAMP, as expected for a dopamine D(2) and D(3) receptor agonist. SLV308 antagonized the inhibitory effect of quinpirole on K(+)-stimulated [(3)H]-dopamine release from rat striatal slices (pA(2) = 8.5). In the same paradigm, SLV308 had antagonist properties in the presence of quinpirole (pA(2) = 8.5), but the partial D(2) agonist terguride had much stronger antagonistic properties. In conclusion, SLV308 combines high potency partial agonism at dopamine D(2) and D(3) receptors with full efficacy low potency serotonin 5-HT(1) (A) receptor agonism and is worthy of profiling in in vivo models of Parkinson's disease.     

Kidney transplantation and waiting list for renal transplantation for human immunodeficiency virus patients

Introduction

The aim of this study was to evaluate the experience of a renal transplantation unit in the management of human immunodeficiency virus (HIV)-infected patients with end-stage renal disease (ESRD).

Methods

A prospective study was performed between 2005 and 2010 among 23 patients with ESRD.

Results

In this study 83% of HIV- infected patients with ESRD were included on the waiting list for renal transplantation with 4 patients in a clinical evaluation phase. During the follow-up, 52% of waiting list patients (n = 11) received a renal transplant, and 1 patient underwent a simultaneous kidney-pancreas transplantation. Among the waiting list group we observed a significant later exclusion (43%; n = 3). Among the transplanted group there was a high but clinically inconsequential prevalence of acute tubular necrosis (36%; n = 4) and acute rejection episodes (36%; n = 4). The renal function showed a serum creatinine of 1.1 mg/dL at a follow-up of 24 + 12 months. All patients on the waiting list and after the transplantation are prescribed combined antiretroviral treatment (cART) with a low viral load <50 with CD4 >200.

Conclusions

HIV-infected patients with ESRD should be considered to be candidates for renal transplantation if they meet the HIV inclusion criteria. Renal transplantation in adequately selected HIV-infected patients is a safe procedure with acceptable patient and graft survivals.     

Febrile urinary tract infection in children: ampicillin and trimethoprim insufficient as empirical mono-therapy

The aim of this study was to characterize the pathogens and their antibiotic susceptibilities in defined groups of children (total number 694) with urinary tract infection (UTI) regarding age, first UTI (FUTI) or recurrent UTI (RUTI), renal abnormalities or vesico-ureteric reflux (VUR) in order to optimize empirical antibiotic therapy and prophylaxis. In patients aged between 1 month and 24 months with a first febrile UTI (FUTI; n = 205) the leading pathogen was Escherichia coli (E. coli) (83.4%). In comparison with patients with FUTI, those with RUTI (n = 24) had more Enterococcus and Enterobacter infections and higher resistance rates of E. coli against trimethoprim (TMP), trimethoprim/sulfamethoxazole (SXT) or ampicillin (AMP). Boys with ultrasound-detected renal abnormalities (n = 71) showed 14.2% Pseudomonas and 59.1% E. coli infections versus girls (n = 48) (2.1% Pseudomonas and 93.7% E. coli). Of 390 patients who underwent voiding cysto-urethrography, 31.5% had VUR. Of them, 45.5% received antimicrobial prophylaxis with SXT (n = 30) or cefazolin (n = 26). There was no difference between girls (n = 242) and boys (n = 148) regarding the frequency of VUR and pathogens. There were more TMP- and SXT-resistant E. coli cultures from patients with VUR (37.8%) than from those without VUR (25.8%). Treatment with TMP, SXT and AMP alone appeared to be insufficient in many cases because of high resistance rates of E. coli and other uropathogens.     

Serum and cerebrospinal fluid magnesium in severe traumatic brain injury outcome

Serum magnesium concentration has a neuroprotective effect in experimental models of traumatic brain injury (TBI). This study was designed to assess the relationship between initial serum magnesium, cerebrospinal fluid (CSF) magnesium, neurological outcome and the efficacy of magnesium replacement therapy (MgSO4). A retrospective analysis was performed on a prospectively collected dataset from 216 patients admitted during 1996-2006 to the University of Pittsburgh Medical Center with severe TBI. Admission serum and CSF magnesium were dichotomized into low and normal magnesium concentration groups for serum and normal and high concentration groups for CSF. A logistic-regression analysis was performed with 6-month Glasgow Outcome Scale (GOS) scores as outcome variable. The outcome of a subset of 31 patients who presented with low serum magnesium and who were rapidly corrected within 24 h of admission was also analyzed. Low initial serum magnesium was measured in 56.67% of all patients. Patients with an initial serum magnesium of <1.3 mEq/L were 2.37 times more likely to have a poor outcome (CI: 1.18-4.78, p = 0.016). The prognostic significance of depressed serum magnesium remained, even in patients whose serum magnesium levels were corrected within 24 h (OR = 11.03, CI: 1.87-68.14, p = 0.008). Patients with an initial high CSF magnesium were 7.63 more likely to have a poor outcome (p = 0.05). Elevated CSF magnesium correlated with depressed serum magnesium only in patients with poor outcome (p = 0.013). Patients with low serum magnesium and high CSF magnesium are most likely to have poor outcome after severe TBI. Rapid correction of serum magnesium levels does not reverse the prognostic value of these markers.     

Mental stress experienced by first-year residents and expert surgeons with robotic and laparoscopic surgery interfaces

Prior research has indicated that novices experienced a beneficial stress profile in the robotic surgery (da Vinci) training environment when compared to the laparoscopic surgery training environment. The objective of this study was to assess whether this finding generalizes to expert surgeons. Towards that end, first-year residents’ and attending surgeons’ performances and subjective stress experiences were assessed in a surgical training task that was performed with the da Vinci and laparoscopic surgery interfaces. This study indicated that both groups exhibited superior performance and lower stress with the da Vinci surgical system than the laparoscopic system. The results provide further support for the sensitivity of the Dundee Stress State Questionnaire in identifying different stress responses experienced by trainees and experts in the minimally invasive surgery environment.     

Generating automated kidney transplant biopsy reports combining molecular measurements with ensembles of machine learning classifiers

We previously reported a system for assessing rejection in kidney transplant biopsies using microarray‐based gene expression data, the Molecular Microscope^® Diagnostic System (MMDx). The present study was designed to optimize the accuracy and stability of MMDx diagnoses by replacing single machine learning classifiers with ensembles of diverse classifier methods. We also examined the use of automated report sign‐outs and the agreement between multiple human interpreters of the molecular results. Ensembles generated diagnoses that were both more accurate than the best individual classifiers, and nearly as stable as the best, consistent with expectations from the machine learning literature. Human experts had ≈93% agreement (balanced accuracy) signing out the reports, and random forest‐based automated sign‐outs showed similar levels of agreement with the human experts (92% and 94% for predicting the expert MMDx sign‐outs for T cell–mediated (TCMR) and antibody‐mediated rejection (ABMR), respectively). In most cases disagreements, whether between experts or between experts and automated sign‐outs, were in biopsies near diagnostic thresholds. Considerable disagreement with histology persisted. The balanced accuracies of MMDx sign‐outs for histology diagnoses of TCMR and ABMR were 73% and 78%, respectively. Disagreement with histology is largely due to the known noise in histology assessments (ClinicalTrials.gov NCT01299168).     

The role of complete surgical resection in stage IV neuroblastoma

The purpose of this study was to examine the outcome of attempted radical surgical resection in patients with stage IV neuroblastoma. Between 1989 and 2003, 20 (median age 2.4 years, range 0.5–8.7 years) children with stage IV neuroblastoma were treated at the Department of Pediatrics. Surgery was performed in 7 consecutive children (6 male and 1 female) between July 1997 and February 2002 at the Department of Urology in Bonn. Mean age at diagnosis was 57 months (21–104 months). Mean age at the time of surgery was 54 months (8–390 months). Follow-up was available for all patients (100%) and mean follow-up after the operation was 32.5 months (4–56 months). Primary localization of the tumor was retroperitoneal in all cases; 4 out of 7 patients (57%) also had additional adrenal, 3 out of 7 (42%) paraganglion and 1 out of 7 (14%) thoracic primaries. Bone marrow and lymph node metastases were found in all patients (100%). Surgery led to complete tumor resection in 6 out of 7 patients (85%). Surgical approach was abdominal (chevron incision) in 6 out of 7 (85%) of the patients, in one patient the approach was thoraco-abdominal. After induction chemotherapy and delayed surgery, 6 out of 7 (86%) patients showed a complete remission (CR) and the mean CR lasted for about 27.7 months (range 3.1–55.4 months). At the last time of follow-up 5 out of 7 (71%) patients were alive, 2 had died due to recurrent disease. Mean time to recurrent disease was 24 and 51 months, respectively. Mean overall survival time since diagnosis was 38.3 months (11–64 months) and mean event-free survival was 34.5 months (11–60.3 months). The final outcome, overall survival and event-free survival time was influenced by metastatic or local relapse. Tumor resection is beneficial but the value of surgery can only be judged when we are able to control metastatic disease in stage IV neuroblastoma. The final outcome may rely on the extent of complete surgical resection, but is also related to treatment of metastases. A longer follow-up period is indicated to detect long term outcome.     

A GABAergic tecto–tegmento–tectal pathway in pigeons

Previous studies have demonstrated that the optic tecta of the left and right brain halves reciprocally inhibit each other in birds. In mammals, the superior colliculus receives inhibitory γ‐aminobutyric acid (GABA)ergic input from the basal ganglia via both the ipsilateral and the contralateral substantia nigra pars reticulata (SNr). This contralateral SNr projection is important in intertectal inhibition. Because the basal ganglia are evolutionarily conserved, the tectal projections of the SNr may show a similar pattern in birds. Therefore, the SNr could be a relay station in an indirect tecto–tectal pathway constituting the neuronal substrate for the tecto–tectal inhibition. To test this hypothesis, we performed bilateral anterograde and retrograde tectal tracing combined with GABA immunohistochemistry in pigeons. Suprisingly, the SNr has only ipsilateral projections to the optic tectum, and these are non‐GABAergic. Inhibitory GABAergic input to the contralateral optic tectum arises instead from a nearby tegmental region that receives input from the ipsilateral optic tectum. Thus, a disynaptic pathway exists that possibly constitutes the anatomical substrate for the inhibitory tecto–tectal interaction. This pathway likely plays an important role in attentional switches between the laterally placed eyes of birds. J. Comp. Neurol. 524:2886–2913, 2016. © 2016 Wiley Periodicals, Inc.     

Polysialylation and lipopolysaccharide‐induced shedding of E‐selectin ligand‐1 and neuropilin‐2 by microglia and THP‐1 macrophages

Microglia are tissue macrophages and mediators of innate immune responses in the brain. The protein‐modifying glycan polysialic acid (polySia) is implicated in modulating microglia activity. Cultured murine microglia maintain a pool of Golgi‐confined polySia, which is depleted in response to lipopolysaccharide (LPS)‐induced activation. Polysialylated neuropilin‐2 (polySia‐NRP2) contributes to this pool but further polySia protein carriers have remained elusive. Here, we use organotypic brain slice cultures to demonstrate that injury‐induced activation of microglia initiates Golgi‐confined polySia expression in situ. An unbiased glycoproteomic approach with stem cell‐derived microglia identifies E‐selectin ligand‐1 (ESL‐1) as a novel polySia acceptor. Together with polySia‐NRP2, polySia‐ESL‐1 is also detected in primary cultured microglia, in brain slice cultures and in phorbol ester‐induced THP‐1 macrophages. Induction of stem cell‐derived microglia, activated microglia in brain slice cultures and THP‐1 macrophages by LPS, but not interleukin‐4, causes polySia depletion and, as shown for stem cell‐derived microglia, a metalloproteinase‐dependent release of polySia‐ESL‐1 and polySia‐NRP2. Moreover, soluble polySia attenuates LPS‐induced production of nitric oxide and proinflammatory cytokines. Thus, shedding of polySia‐ESL‐1 and polySia‐NRP2 after LPS‐induced activation of microglia and THP‐1 macrophages may constitute a mechanism for negative feedback regulation. GLIA 2016 GLIA 2016;64:1314–1330