Mitochondrial function in human brains is affected by pre- and post mortem factors

AIM

Mitochondrial function and the ensuing ATP synthesis are central to the functioning of the brain and contribute to neuronal physiology. Most studies on neurodegenerative diseases have highlighted that mitochondrial dysfunction is an important event contributing to pathology. However, studies on the human brain mitochondria in various neurodegenerative disorders heavily rely on post mortem samples. As post mortem tissues are influenced by pre- and post mortem factors, we investigated the effect of these variables on mitochondrial function.

METHODS

We examined whether the mitochondrial function (represented by mitochondrial enzymes and antioxidant activities) in post mortem human brains (n=45) was affected by increased storage time (11.8-104.1 months), age of the donor (2 days to 80 years), post mortem interval (2.5-26 h), gender difference and agonal state [based on Glasgow Coma Scale: range=3-15] in the frontal cortex, as a prototype.

RESULTS

We observed that the activities of citrate synthase, succinate dehydrogenase and mitochondrial reductase (MTT) were significantly affected only by gender difference (citrate synthase: P=0.005; succinate dehydrogenase: P=0.01; mitochondrial reductase: P=0.006), being higher in females, but not by any other factor. Mitochondrial complex I activity was significantly inhibited by increasing age (r=-0.40; P=0.05). On the other hand, the mitochondrial antioxidant enzyme glutathione reductase decreased with severe agonal state (P=0.003), while the activity of glutathione-S-transferase declined with increased storage time (P=0.005) and severe agonal state (P=0.02).

CONCLUSION

Our data highlight the influence of pre- and post mortem factors on preservation of mitochondrial function with implications for studies on brain pathology employing stored human samples.

Tumefactive demyelination: clinical, imaging and follow-up observations in thirty-nine patients

PURPOSE

We describe the clinical, neuroimaging and pathological features and therapeutic outcome in a large cohort of 39 patients with tumefactive demyelination.

MATERIALS AND METHODS

A retrospective audit of 39 patients with 'tumefactive demyelination' was performed. The demographic, clinical, MR imaging and pathological details were reviewed.

RESULTS

The clinical course was monophasic (n = 22) or relapsing-remitting (n = 17). Common neurological manifestations at presentation included hemiparesis - 27; ataxia - 11; vomiting - 10; headache -9; ophthalmoplegia - 7; seizure - 5; impaired vision - 4; aphasia - 4; visual field defects - 3; papilloedema - 5; extrapyramidal - 5; intellectual decline - 5; behavioural disturbances - 3; altered sensorium - 5. MRI revealed fronto-parietal lesions, which were isolated in 14 (36%) patients. Moderate perilesional oedema and/or mass effect was noted in 12 (30.8%) patients. Post-contrast MR sequences revealed partial ring enhancement in 15, complete ring in seven, patchy enhancement in six, uniform enhancement in two and lack of enhancement in nine cases. Clinical and MR characteristics did not help distinguish between monophasic and relapsing-remitting subgroups. In the monophasic group, 53.8% had complete recovery, while 38.5% had partial improvement (follow-up duration, 8.31 ± 9.3 months). In the relapsing-remitting subgroup, the median time to relapse was 4 months (n = 12, follow-up, 37.8 ± 39.4 months). Patients with monophasic course or single relapse received steroids. Patients with more than one relapse received cyclophosphamide (2), mycophenolate (1), azathioprine (1) or methotrexate (1).

CONCLUSIONS

A high proportion of cases of tumefactive demyelination follow a relapsing course, thus necessitating a long-term follow-up. MRI, although helpful in diagnosis, does not predict monophasic or relapsing-remitting course. Guidelines for the management of acute episodes and prevention of relapses are required.

Efficacy and limitations of pulse cyclophosphamide therapy in polymyositis and dermatomyositis

OBJECTIVES

To assess the therapeutic response of intravenous (IV) pulse cyclophosphamide therapy in polymyositis and dermatomyositis.

METHODS

Data of 9 patients (M:F = 2:7) who received IV pulse cyclophosphamide therapy were retrospectively analyzed.

RESULTS

The mean symptom duration was 11.33 ± 10.6 months (range, 2-34 months). The cohort comprised (1) primary idiopathic polymyositis (n = 1), (2) primary idiopathic dermatomyositis (n = 1), (3) childhood type associated with vasculitis (n = 1), and (4) associated with collagen vascular disease (n = 6). All patients improved and became clinically asymptomatic after a mean period of 12.33 ± 6.5 months (range, 4-24 months); 5 remained asymptomatic at the end of a median follow-up period of 22 months. All patients received concomitant steroid therapy, and in 6, steroids could be tapered after the initiation of IV pulse cyclophosphamide therapy.

CONCLUSIONS

In this cohort of polymyositis/dermatomyositis, treatment with IV pulse cyclophosphamide was associated with improvement; the therapeutic response was sustained in majority of the patients.

Enterovirus 71 encephalomyelitis and Japanese encephalitis can be distinguished by topographic distribution of inflammation and specific intraneuronal detection of viral antigen and RNA

AIMS

To investigate if two important epidemic viral encephalitis in children, Enterovirus 71 (EV71) encephalomyelitis and Japanese encephalitis (JE) whose clinical and pathological features may be nonspecific and overlapping, could be distinguished.

METHODS

Tissue sections from the central nervous system of infected cases were examined by light microscopy, immunohistochemistry and in situ hybridization.

RESULTS

All 13 cases of EV71 encephalomyelitis collected from Asia and France invariably showed stereotyped distribution of inflammation in the spinal cord, brainstem, hypothalamus, cerebellar dentate nucleus and, to a lesser extent, cerebral cortex and meninges. Anterior pons, corpus striatum, thalamus, temporal lobe, hippocampus and cerebellar cortex were always uninflamed. In contrast, the eight JE cases studied showed inflammation involving most neuronal areas of the central nervous system, including the areas that were uninflamed in EV71 encephalomyelitis. Lesions in both infections were nonspecific, consisting of perivascular and parenchymal infiltration by inflammatory cells, oedematous/necrolytic areas, microglial nodules and neuronophagia. Viral inclusions were absent.

CONCLUSIONS

Immunohistochemistry and in situ hybridization assays were useful to identify the causative virus, localizing viral antigens and RNA, respectively, almost exclusively to neurones. The stereotyped distribution of inflammatory lesions in EV71 encephalomyelitis appears to be very useful to help distinguish it from JE.

Usefulness of stereotactic biopsy and neuroimaging in management of HIV-1 Clade C associated focal brain lesions with special focus on cerebral toxoplasmosis

BACKGROUND

Focal brain lesions (FBL) in HIV/AIDS frequently pose a diagnostic dilemma as the etiology varies from infective (tuberculoma, toxoplasmosis and tuberculous abscesses) to neoplastic lesions like lymphoma. For determining etiology, advanced neuroimaging techniques, serological and molecular biological tests have been evolved with varying sensitivities/specificities. Stereotactic biopsy (STB) of the lesions is reserved for lesions unresponsive to appropriate therapy.

OBJECTIVE AND METHODS

In this study, the diagnostic yield of neuroimaging [cranial CT (n=25), MRI (n=24), and Th201/99Tc SPECT scan (n=18)] is compared with histopathological diagnosis obtained by STB (n=21) or autopsy (n=4) in 25 HIV-1 subtype C seropositive individuals with FBL identified by neuroimaging with special reference to cerebral toxoplasmosis in an eighteen month study period (2006-2007).

RESULTS AND CONCLUSION

Cerebral toxoplasmosis was the most frequent cause of FBL (21/25, 84%), followed by one case each of tuberculoma, progressive multifocal leukoencephalopathy (PML), primary central nervous system lymphoma (PCNSL) and measles inclusion body encephalitis (MIBE), the last two diagnosed at autopsy. Of the 21 cases of cerebral toxoplasmosis, definitive diagnosis with histopathological confirmation was available in 14/21 (66.6%), with indirect evidence suggesting probable toxoplasmosis in seven, all of whom responded to antitoxoplasma therapy. CT and MRI had comparable specificities (75%), while MRI had marginally higher sensitivity (85% versus 80.9%) in detecting multiple lesions. The positive predictive value of both CT and MRI was identical (94.4%), suggesting that CT maybe a cost effective screening tool in resource restricted settings, for evaluating FBL. Sensitivity of 99Tc SPECT scan for diagnosing inflammatory lesions was 75% but failed to differentiate PCNSL from toxoplasmosis. This study is the first of its kind from India analyzing FBL with specific focus on cerebral toxoplasmosis in the setting of HIV-1 subtype C.

Carcinomatous meningitis: Yet another cause for rapidly progressive dementia and triphasic waves in electroencephalograph!

We report a 65-year-old woman who manifested with progressive cognitive impairment, abnormal behavior, slurred speech, inability to carry out activities with right upper limb, gait disturbances, emotional liability, and double incontinence that evolved progressively over the last 8 months. A clinical syndrome of “rapidly progressive dementia” was considered. The MRI of brain was unremarkable except for small para third ventricular enhancing lesion was detected in the left thalamic region. There was bi/tri-phasic sharp waves in the routine scalp EEG occurring at periodically 1.5–2.0 Hz, mimicking Creutzfeldt–Jakob disease (CJD). She was later diagnosed to have carcinomatous meningitis based on cerebrospinal fluid (CSF) cytology. This case is being discussed for rarity and interesting EEG observations in patients with carcinomatous meningitis and to highlight the importance of CSF cytology in an appropriate clinical setting. One needs to be careful in concluding CJD as possible diagnosis in such scenario.

An unusual case of unilateral limb hypertrophy: Lipoma of sacral roots

We report an unusual case of unilateral limb pseudo hypertrophy in a 21-year-old lady who developed progressive enlargement of the right calf followed by thigh in association with chronic leg pain. Magnetic resonance imaging (MRI) of the affected limb confirmed enlargement of various muscles. Electromyography revealed neurogenic features consistent with S1 radiculopathy. MRI of the lumbosacral spine showed tethered cord with a lipoma infiltrating multiple sacral roots. Our case illustrates that muscular pseudo hypertrophy may follow chronic denervation as a consequence of spinal neural compressive disease. The various mechanisms postulated for this distinct condition are outlined.

Rosette-forming glioneuronal tumor -- evidence of stem cell origin with biphenotypic differentiation

Rosette-forming glioneuronal tumor (RGNT) of the fourth ventricle is a new addition to the WHO classification of central nervous system tumors. To date, 72 cases have been described in literature. In the present study, we report the clinical and imaging features, with detailed histopathological and immunohistochemical profile, of eight cases. Confocal microscopic evidence of stem cell origin with biphenotypic, glial and neurocytic differentiation is presented with a comprehensive review of literature.

Usefulness of superficial peroneal nerve/peroneus brevis muscle biopsy in the diagnosis of vasculitic neuropathy

Sensitivity, specificity, and diagnostic yield of the superficial peroneal nerve (SPN)/peroneus brevis muscle (PBM) biopsy in 43 patients with clinically suspected vasculitic neuropathy was studied. Biopsies were classified as "definite", "suspicious" or "possible" in accordance with established criteria. Vasculitis was detected in 27 patients (21 with non-systemic vasculitis, and six with systemic vasculitis). In patients with "definite" vasculitis (n=13), the sensitivity of SPN/PBM biopsy was 76.4% with 100% specificity. By including patients suspicious for vasculitis (n=10), sensitivity increased to 85.1% but the specificity dropped to 87.5%. The overall diagnostic yield of SPN biopsy in those patients with definite vasculitis was 76.9% (10/13), and 53.8% (7/13) for muscle biopsy. The addition of muscle biopsy increased the diagnostic yield by 23%. Asymmetric nerve fiber loss, Wallerian degeneration and presence of hemosiderin were statistically significant markers of probable vasculitis. Muscle tissue was more likely to show hemosiderin (85.7%) than a nerve biopsy (71%). A combined SPN/PBM biopsy offers excellent diagnostic yield in the diagnosis of vasculitic neuropathy.

Eddy-driven stratification initiates North Atlantic spring phytoplankton blooms

Springtime phytoplankton blooms photosynthetically fix carbon and export it from the surface ocean at globally important rates. These blooms are triggered by increased light exposure of the phytoplankton due to both seasonal light increase and the development of a near-surface vertical density gradient (stratification) that inhibits vertical mixing of the phytoplankton. Classically and in current climate models, that stratification is ascribed to a springtime warming of the sea surface. Here, using observations from the subpolar North Atlantic and a three-dimensional biophysical model, we show that the initial stratification and resulting bloom are instead caused by eddy-driven slumping of the basin-scale north-south density gradient, resulting in a patchy bloom beginning 20 to 30 days earlier than would occur by warming.

Dengue-associated transient muscle dysfunction: clinical, electromyography and histopathological changes

BACKGROUND

Dengue is commonly associated with myalgia, but there is paucity of studies on the frequency, severity, and basis of muscle involvement. The aim of this study was to document the clinical, electromyographic, and histological changes in dengue-associated muscle dysfunction.

MATERIALS AND METHODS

Seropositive dengue patients admitted to the neurology ward during 2010 were enrolled in this study. Detailed medical history, including bleeding diathesis and organomegaly, were noted. Muscle power on a 0-5 scale, muscle tone, reflex, sensations and coordination were tested. Blood counts, hemoglobin, and serum chemistry, including creatine kinase (CK) evaluations, were carried out. Concentric needle electromyography (EMG) and muscle biopsy were performed when clinical conditions were suitable.

RESULTS

The study cohort comprised 39 patients with dengue, with a median age of 28 years. Of these, 31 patients showed evidence of muscle involvement-16 with clinical and 15 with subclinical muscle involvement. Eight of these patients had severe weakness and five had hyporeflexia. Thrombocytopenia was present in 26 patients, elevated serum creatinine in three patients and liver dysfunction in 31 patients. The median CK level was 837 (range 194-3,832) U/L. The EMG revealed polyphasic normal to short duration motor unit potentials, but spontaneous activity was absent. Muscle biopsy in three patients revealed interstitial hemorrhage with occasional necrosis and myophagocytosis. There was no vasculitis, but subtle inflammatory changes were present in one patient. The severity of muscle weakness correlated with the platelet count and CK level. All patients improved by 15 days of treatment initiation.

CONCLUSION

Dengue commonly results in benign and self-limiting transient muscle dysfunction.

Impact of episodic vertical fluxes on sea surface pCO2

Episodic events like hurricanes, storms and frontal- and eddy-driven upwelling can alter the partial pressure of CO(2) (pCO(2)) at the sea surface by entraining subsurface waters into the surface mixed layer (ML) of the ocean. Since pCO(2) is a function of total dissolved inorganic carbon (DIC), temperature (T), salinity and alkalinity, it responds to the combined impacts of physical, chemical and biological changes. Here, we present an analytical framework for assessing the relative magnitude and sign in the short-term perturbation of surface pCO(2) arising from vertical mixing events. Using global, monthly, climatological datasets, we assess the individual, as well as integrated, contribution of various properties to surface pCO(2) in response to episodic mixing. The response depends on the relative vertical gradients of properties beneath the ML. Many areas of the ocean exhibit very little sensitivity to mixing owing to the compensatory effects of DIC and T on pCO(2), whereas others, such as the eastern upwelling margins, have the potential to generate large positive/negative anomalies in surface pCO(2). The response varies seasonally and spatially and becomes more intense in subtropical and subpolar regions during summer. Regions showing a greater pCO(2) response to vertical mixing are likely to exhibit higher spatial variability in surface pCO(2) on time scales of days.

Clinicopathological profile of polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes (POEMS) syndrome

Patients with polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes (POEMS) syndrome caused by underlying plasma cell dyscrasias, although rare, may present with peripheral neuropathy. In this retrospective study we describe the clinical, electrophysiological and pathological profile of 29 patients (27 males and two females, with a mean age of 45.9±7.9 years) seen between 1983 to 2009 who satisfied the Dispenzieri criteria. Polyneuropathy with weakness and paresthesias of the limbs evolving over 8.3±9.1 months, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes were seen in all patients. Other features included pedal edema (25 patients), papilledema (24), weight loss (23), clubbing (20) and Castleman disease (three patients). We report the pathological features seen in nerve biopsies, osteosclerotic lesions, skin biopsies, lymph node biopsies and bone marrow aspirates. We report the method of a diagnosis confirmation and compare the clinicopathological features of our patients with other published series. Our findings highlight the importance of a meticulous systemic examination and systematic laboratory investigations in the diagnosis of POEMS syndrome.