Normalization of NF-κB activity in dorsal root ganglia neurons cultured from diabetic rats reverses neuropathy-linked markers of cellular pathology

AIMS/HYPOTHESIS

Dorsal root ganglia (DRG) sensory neurons cultured from 3 to 5 month streptozotocin (STZ)-induced diabetic rats exhibit structural and biochemical changes seen in peripheral nerve fibers in vivo, including axonal swellings, oxidative damage, reduced axonal sprouting, and decreased NF-κB activity. NF-κB is a transcription factor required by DRG neurons for survival and plasticity, and regulates transcription of antioxidant proteins (e.g. MnSOD). We hypothesized that the diabetes-induced decrease in NF-κB activity in DRG contributes to pathological phenomena observed in cultured DRG neurons from diabetic rats.

METHODS

NF-κB localization was assessed in intact DRG and neuron cultures using immunostaining. NF-κB activity was manipulated in sensory neuron cultures derived from age-matched normal or 3-5 month STZ-diabetic rats using pharmacological means and lentiviral expression of shRNA. The impact of diabetes and altered NF-κB activity on neuronal phenotype involved analysis of neurite outgrowth, neurite morphology, oxidative stress (lipid peroxidation) and expression of MnSOD.

RESULTS

STZ-induced diabetes caused a significant decrease in nuclear localization of NF-κB subunits p50 and c-rel, but no change in p65 in intact DRG. Inhibition of NF-κB in normal neuron cultures significantly increased axonal swellings and oxidative stress, and reduced both neurite outgrowth and expression of MnSOD. These phenomena mimicked markers of pathology in cultured DRG neurons from diabetic rats. Enhancement of NF-κB activity in cultured diabetic DRG neurons ameliorated the sub-optimal neurite outgrowth and MnSOD levels triggered by diabetes. Exogenous insulin enhanced nuclear localization of p50 and c-rel but not p65 in diabetic neuronal cultures.

CONCLUSION/INTERPRETATION

The diabetes-induced decrease of nuclear localization of NF-κB subunits p50 and c-rel in DRG contributes to development of in vitro markers of peripheral neuropathy, possibly through impaired mitochondrial ROS scavenging by deficient MnSOD.

Strategy of surgical treatment of giant presacral tumor - a case report

Presacral tumors are uncommon lesions that can be difficult to diagnose because of their nonspecific presenting signs and symptoms. Surgery is the mainstay of treatment as it establishes the diagnosis and prevents the adverse consequences associated with malignant degeneration and secondary bacterial infection. Large, highly vascularised pelvic tumors may pose intraoperative difficulties as bleeding and intraoperative tumor perforation. Cross-sectional imaging is essential in evaluating these lesions to determine the optimal surgical approach and the extent of resection. We emphasize a multidisciplinary expert individualized approach. We report a case of a presacral giant gastrointestinal tumor initially considered as unresectable but further on successfully managed by preoperative vascular embolization followed by resection via abdomino-perineal approach.

Ventilation with low tidal volumes during upper abdominal surgery does not improve postoperative lung function

BACKGROUND

Prolonged postoperative decrease in lung function is common after major upper abdominal surgery. Evidence suggests that ventilation with low tidal volumes may limit the damage during mechanical ventilation. We compared postoperative lung function of patients undergoing upper abdominal surgery, mechanically ventilated with high or low tidal volumes.

METHODS

This was a double-blind, prospective, randomized controlled clinical trial. One hundred and one patients (age ≥ 50 yr, ASA ≥ II, duration of surgery ≥ 3 h) were ventilated with: (i) high [12 ml kg(-1) predicted body weight (PBW)] or (ii) low (6 ml kg(-1) PBW) tidal volumes intraoperatively. The positive end-expiratory pressure was 5 cm H(2)O in both groups and breathing frequency adjusted to normocapnia. Time-weighted averages (TWAs) of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)) until 120 h after operation were compared (P<0.025 considered statistically significant). Secondary outcomes were oxygenation, respiratory and non-respiratory complications, length of stay and mortality.

RESULTS

The mean (sd) values of TWAs of FVC and FEV(1) were similar in both groups: FVC: 6 ml group 1.8 (0.7) litre vs 12 ml group 1.6 (0.5) litre (P=0.12); FEV(1): 6 ml group 1.4 (0.5) litre vs 12 ml group 1.2 (0.4) litre (P=0.15). FVC and FEV(1) at any single time point and secondary outcomes did not differ significantly between groups.

CONCLUSIONS

Prolonged impaired lung function after major abdominal surgery is not ameliorated by low tidal volume ventilation.

Comparison of the saline infusion test and the fludrocortisone suppression test for the diagnosis of primary aldosteronism

For the diagnosis of primary aldosteronism (PA), confirmatory testing is mandatory and different function tests can be employed. There are, however, sparse data comparing the fludrocortisone suppression test (FST) and the saline infusion test (SIT). Patients with PA (n=90) or essential hypertension (n=65) were studied. They underwent one or the other test or both of them. Using the DPC Siemens aldosterone radioimmunoassay, we found that the SIT led to a stronger suppression of aldosterone than the FST. Post-test aldosterone-to-renin ratios (ARRs) and the percentage of suppression of aldosterone serum concentrations performed worse. The same results were observed in patients who underwent both FST and SIT. Some patients had divergent results in both tests. For the SIT, a lower cutoff value should be used than for the FST for the adequate identification of patients with unilateral PA. Long-term prospective studies are needed to address the question at what cutoff values patients benefit from subtype differentiation of PA. We discuss here possible explanations for divergent results obtained with both tests.

Treatment of hepatitis C virus infection in patients on maintenance hemodialysis: a single United Arab Emirates center experience

BACKGROUND

Hepatitis C is prevalent among hemodialysis patients. In patients with normal kidney function, treatment with pegylated interferon and ribavirin can lead to eradication of HCV (hepatitis C virus). But the treatment is more problematic in patients with impaired kidney function, in part due to the altered pharmacokinetics of these medications. Despite recent guidelines, the optimal strategy in this group of patients is not well defined.

METHOD

In a retrospective study, we reviewed all patients with chronic hepatitis C on hemodialysis treated at Sheikh Khalifa Medical City, in the United Arab Emirates between 2003 and 2009. The aim of our study was to determine the rate of sustained viral response (SVR) and to establish the safety and rate of dropouts in the different treatment regimens used (patients treated with peginterferon only and patients treated with peginterferon and low dose ribavirin).

RESULTS

22 patients were treated during this period. 5 patients received monotherapy with a reduced dose of peginterferon alfa 2b s.c. once weekly while 17 patients were treated with a combination of reduced dose of peginterferon alfa 2a or 2b s.c. once weekly and a low dose ribavirin (200mg/day). A SVR was achieved in 73% (16/22 patients) of the total patient population and in 76% (13/17 patients) in the sub-group of patients treated with a combination therapy. The tolerability was high. No patients had to discontinue their treatment. The use of ESA (erythropoietin stimulating agents) and G-CSF was common in the combination therapy (94% and 53% respectively).

CONCLUSION

In our study of patients on hemodialysis with chronic hepatitis C, the use of peginterferon or a combination of peginterferon with a low daily dose of ribavirin achieved a high rate of SVR and the rate of dropout was low after pursuing an aggressive management of side effects.

[Posterolateral rotatory instability of the elbow secondary to sprain]

We present a case of a 23 year-old man who presented to the emergency department after sustaining indirect trauma to the left elbow with unremarkable physical examination and normal radiographs. He presented again three weeks after with repeated episodes of locking and snapping of the left elbow occurring every time he attempted to rise from a chair while pushing the armrests, and when manoeuvring the steering wheel of his vehicle. On physical examination, the patient was apprehensive to the "lateral pivot shift" test as described by O'Driscoll et al. (1991) [1]. MRI of the left elbow demonstrated avulsion of the proximal epicondylar insertion of the lateral collateral ligament complex (LCLC). The "lateral pivot shift test" was positive under general anaesthesia. Lateral elbow radiograph taken during the test showed widening of the ulno-humeral joint space with posterior subluxation of the radial head. The patient underwent surgical treatment for posterolateral rotatory instability (PLRI) of the elbow. This case report aims to highlight the clinical aspects of the PLRI which may occur after a simple elbow sprain and be easily missed if not suspected; it also aims to draw attention to the importance of the "lateral pivot shift test" and the value of the stress lateral elbow radiograph in establishing the diagnosis of this rare and subtle entity.

[Evaluation of ADC mapping as an early predictor for tumor response to chemotherapy in recurrent glioma treated with bevacizumab/irinotecan: proof of principle]

PURPOSE

The assessment of the radiological response of recurrent glioma is based on the Macdonald or RECIST criteria 8 to 10 weeks from the start of treatment. Magnetic resonance imaging using an apparent diffusion coefficient map may provide an earlier measure for predicting the response to therapy of recurrent glioma.

MATERIALS AND METHODS

Twelve patients with recurrent high-grade glioma were enrolled in a feasibility study of pretreatment MRI on day 1, intra-treatment MRI in week 3, and post-treatment MRI in week 12. Prognostically relevant ADC values (ADCprog) of each recurrent glioma at 3 weeks were calculated as a function of their pre- and intra-therapy ADC values (ADCpre - ADCintra = ADCprog). Because we hypothesized that smaller ADC values correlate with less Brownian motion of water molecules in the extracellular space and that a higher cell density may restrain this water diffusion, we set smaller ADC values at a second time point as "progressive disease" (PD) and higher ADC values as "partial response" (PR). A change in ADCprog of less than 10 × 10⁻⁶mm² /sec was set as "stable disease" (SD). The ADCprog values were always calculated before the final scan after 3 months was performed. The readers were blinded to the future development of the tumor.

RESULTS

In 10 of the 12 patients we could correctly predict the tumor response to chemotherapy. One patient died before the three-month control, and one recurrent glioma did not develop as predicted. ADC mapping is found to predict patient response at 3 weeks from the start of treatment, revealing that early changes in tumor diffusion values could be used as a prognostic indicator also for chemotherapeutically treated recurrences of high-grade glioma.

Magnetization transfer imaging provides no evidence of demyelination in methotrexate-induced encephalopathy

Subacute MTX-induced encephalopathy is characterized by an abrupt onset of focal neurologic deficits within days after intrathecal or systemic therapy. Demyelination is one proposed mechanism. We describe the neuroimaging features of 2 patients with clinical symptoms of subacute encephalopathy after intrathecal and systemic MTX therapy. DWI showed restricted diffusion, indicating cytotoxic edema. MTI yielded no evidence of demyelination in either patient because there was no loss of MTR in areas of restricted diffusion.

[Severe aseptic leucoencephalopathy. Manifested as immune reconstitution inflammatory syndrome in Caucasian and African patients]

BACKGROUND

We hypothesize that CNS immune reconstitution inflammatory syndrome (IRIS) after highly active antiretroviral therapy (HAART) in HIV-1-positive patients may become manifest without any opportunistic infection as an aseptic leucoencephalopathy. This opens a window of opportunity for successful treatment with corticosteroids.

DESIGN

We describe a case series of immunocompromised HIV-1-positive patients who were started on HAART. All of them had clinical laboratory follow-up tests and cerebral MRI in order to investigate the course and the underlying pathophysiology of this aseptic form of IRIS. One African patient died and we performed a neuropathological examination.

RESULTS

No infectious agent was detected before and during HAART. Three of four immunocompromised patients were successfully treated with corticosteroids while HAART was never interrupted and have survived up to now. One African patient died within 2 days despite intensive care due to cerebral oedema.

CONCLUSIONS

Starting HAART, HIV-1-positive patients may develop an aseptic type of IRIS of the CNS without any detectable opportunistic infection, a finding that has not yet been published. This makes them susceptible for successful treatment with corticosteroids. Perhaps IRIS has a higher incidence in African patients and the patients have a poorer outcome than Caucasians.