Towards industrial biological hydrogen production: a review.

Increased production of renewable energy sources is becoming increasingly needed. Amidst other strategies, one promising technology that could help achieve this goal is biological hydrogen production. This technology uses micro-organisms to convert organic matter into hydrogen gas, a clean and versatile fuel that can be used in a wide range of applications. While biohydrogen production is in its early stages, several challenges must be addressed for biological hydrogen production to become a viable commercial solution. From an experimental perspective, the need to improve the efficiency of hydrogen production, the optimization strategy of the microbial consortia, and the reduction in costs associated with the process is still required. From a scale-up perspective, novel strategies (such as modelling and experimental validation) need to be discussed to facilitate this hydrogen production process. Hence, this review considers hydrogen production, not within the framework of a particular production method or technique, but rather outlines the work (bioreactor modes and configurations, modelling, and techno-economic and life cycle assessment) that has been done in the field as a whole. This type of analysis allows for the abstraction of the biohydrogen production technology industrially, giving insights into novel applications, cross-pollination of separate lines of inquiry, and giving a reference point for researchers and industrial developers in the field of biohydrogen production.

The state of cortical microcircuits during wakefulness and sleep.

Wakefulness and sleep are two qualitatively different behavioral states. The mechanisms underlying these behavioral states can be traced back to the coordinated functioning of cortical microcircuits. The stereotypical activity of cortical microcircuits during wakefulness and sleep shapes a cortical state, defined as an organized neuronal network functioning across time. Cortical microcircuits are conformed by pyramidal cells and several interneurons, organized into a six-layer structure that contains well defined connections across excitatory and inhibitory cells. In this organization, inhibitory interneurons play an important role in the transitions between wakefulness and sleep, through their actions in the regulation of the excitatory/inhibitory balance. Yet, we do not know what mechanisms underlie cortical microcircuits transitions between different behavioral states. The aim of this review is to examine how the action of specific interneurons can shape the outcome of cortical microcircuits. We discuss the role of interneurons, as main modulators of sleep and wake states and the communication regimes of microcircuits observed during different cortical states. The literature here reviewed suggests the importance of inhibitory interneurons as the main modulator of the function of cortical microcircuits. We finally discuss some future research perspectives about cortical states and their different interneurons subtypes.

Source-reconstruction of the sensorimotor network from resting-state macaque electrocorticography.

The discovery of hemodynamic (BOLD-fMRI) resting-state networks (RSNs) has brought about a fundamental shift in our thinking about the role of intrinsic brain activity. The electrophysiological underpinnings of RSNs remain largely elusive and it has been shown only recently that electric cortical rhythms are organized into the same RSNs as hemodynamic signals. Most electrophysiological studies into RSNs use magnetoencephalography (MEG) or scalp electroencephalography (EEG), which limits the spatial resolution with which electrophysiological RSNs can be observed. Due to their close proximity to the cortical surface, electrocorticographic (ECoG) recordings can potentially provide a more detailed picture of the functional organization of resting-state cortical rhythms, albeit at the expense of spatial coverage. In this study we propose using source-space spatial independent component analysis (spatial ICA) for identifying generators of resting-state cortical rhythms as recorded with ECoG and for reconstructing their functional connectivity. Network structure is assessed by two kinds of connectivity measures: instantaneous correlations between band-limited amplitude envelopes and oscillatory phase-locking. By simulating rhythmic cortical generators, we find that the reconstruction of oscillatory phase-locking is more challenging than that of amplitude correlations, particularly for low signal-to-noise levels. Specifically, phase-lags can both be over- and underestimated, which troubles the interpretation of lag-based connectivity measures. We illustrate the methodology on somatosensory beta rhythms recorded from a macaque monkey using ECoG. The methodology decomposes the resting-state sensorimotor network into three cortical generators, distributed across primary somatosensory and primary and higher-order motor areas. The generators display significant and reproducible amplitude correlations and phase-locking values with non-zero lags. Our findings illustrate the level of spatial detail attainable with source-projected ECoG and motivates wider use of the methodology for studying resting-state as well as event-related cortical dynamics in macaque and human.

Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.

Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions.

A DCM study of spectral asymmetries in feedforward and feedback connections between visual areas V1 and V4 in the monkey.

This paper reports a dynamic causal modeling study of electrocorticographic (ECoG) data that addresses functional asymmetries between forward and backward connections in the visual cortical hierarchy. Specifically, we ask whether forward connections employ gamma-band frequencies, while backward connections preferentially use lower (beta-band) frequencies. We addressed this question by modeling empirical cross spectra using a neural mass model equipped with superficial and deep pyramidal cell populations-that model the source of forward and backward connections, respectively. This enabled us to reconstruct the transfer functions and associated spectra of specific subpopulations within cortical sources. We first established that Bayesian model comparison was able to discriminate between forward and backward connections, defined in terms of their cells of origin. We then confirmed that model selection was able to identify extrastriate (V4) sources as being hierarchically higher than early visual (V1) sources. Finally, an examination of the auto spectra and transfer functions associated with superficial and deep pyramidal cells confirmed that forward connections employed predominantly higher (gamma) frequencies, while backward connections were mediated by lower (alpha/beta) frequencies. We discuss these findings in relation to current views about alpha, beta, and gamma oscillations and predictive coding in the brain.

Recording of brain activity across spatial scales.

Brain activity reveals exquisite coordination across spatial scales, from local microcircuits to brain-wide networks. Understanding how the brain represents, transforms and communicates information requires simultaneous recordings from distributed nodes of whole brain networks with single-cell resolution. Realizing multi-site recordings from communicating populations is hampered by the need to isolate clusters of interacting cells, often on a day-to-day basis. Chronic implantation of multi-electrode arrays allows long-term tracking of activity. Lithography on thin films provides a means to produce arrays of variable resolution, a high degree of flexibility, and minimal tissue displacement. Sequential application of surface arrays to monitor activity across brain-wide networks and subsequent implantation of laminar arrays to target specific populations enables continual refinement of spatial scale while maintaining coverage.

Contrast gain control and horizontal interactions in V1: a DCM study.

Using high-density electrocorticographic recordings - from awake-behaving monkeys - and dynamic causal modelling, we characterised contrast dependent gain control in visual cortex, in terms of synaptic rate constants and intrinsic connectivity. Specifically, we used neural field models to quantify the balance of excitatory and inhibitory influences; both in terms of the strength and spatial dispersion of horizontal intrinsic connections. Our results allow us to infer that increasing contrast increases the sensitivity or gain of superficial pyramidal cells to inputs from spiny stellate populations. Furthermore, changes in the effective spatial extent of horizontal coupling nuance the spatiotemporal filtering properties of cortical laminae in V1 - effectively preserving higher spatial frequencies. These results are consistent with recent non-invasive human studies of contrast dependent changes in the gain of pyramidal cells elaborating forward connections - studies designed to test specific hypotheses about precision and gain control based on predictive coding. Furthermore, they are consistent with established results showing that the receptive fields of V1 units shrink with increasing visual contrast.

[Diagnostic image (204). A man with abdominal pain and fever]. / Diagnose in beeld (204). Een man met buikpijn en koorts.

In a 53-year-old man with acute sigmoid diverticulitis abdominal CT revealed septic thrombophlebitis with gas configurations in the inferior mesenteric vein.

Aesthesioneuroblastoma in a woodworker.

A case is described of aesthesioneuroblastoma in a woodworker who had been exposed to wood dust for 25 years, without any individual or environmental protection. The case described supports the contention that occupational exposure to wood dust may have caused the neoplasm.

Fatty acid synthase expression in melanoma.

BACKGROUND: Fatty acid synthase (FAS), the key enzyme responsible for the synthesis of fatty acids, is weakly expressed in some normal human tissues. Recently, FAS has been demonstrated to be overexpressed in many non-neoplastic highly proliferative lesions and in aggressive carcinomas with poor outcome, including colon, breast and ovary carcinomas. METHODS: In order to evaluate the prognostic significance of FAS in human melanoma, we analysed by means of immunohistochemistry, using a monoclonal anti-FAS antibody, 77 primary melanomas and 30 nodal and cutaneous metastasis. Thirty nevi (15 dermal and 15 junctional nevi) were used as controls. All patients were followed-up for 5 years. RESULTS: Thirty-four melanomas expressed strong FAS immunostaining; the remaining 43 cases showed weak expression or were negative. All cutaneous and nodal metastasis were strongly positive. All patients with metastases deceased during the follow up period. Control specimens expressed weak staining. None of these patients developed recurrence. Statistical analysis revealed significant association of FAS expression with Breslow thickness (p = 0.012). The intensity of FAS immunostaining was also predictive of prognosis (p = 0.049). CONCLUSIONS: FAS is a reliable prognostic marker in human melanomas. FAS predictive strength is increased when associated with Breslow thickness. The observation of FAS in human melanomas may stratify patients for stricter follow-ups and suggest different therapeutic approaches.

[Primary venous mesenterial thrombosis in three patients]. / Primaire veneuze mesenteriale trombose bij 3 patiënten.

Three patients, a woman aged 72, a man aged 25 and a woman aged 42 years, presented at the casualty department with a subacute form of primary venous mesenterial thrombosis. As symptoms and laboratory findings are aspecific, CT scan is the gold standard for the diagnosis of this condition. In these patients no cause or predisposing factor was detected, so the disease was considered to be primary. Treatment generally consists of anticoagulant therapy and if peritonitis is present operation is indicated. Hyperdynamic circulation and inotropica are indicated after surgery and in cases of critical illness. Based on clinical findings the third patient was treated successfully with anticoagulants only. The other two also underwent partial small intestinal resection. All three patients were discharged in good health and were prescribed lifelong anticoagulants. If a cause of venous mesenterial thrombosis can be found, this must first be treated before deciding on whether lifelong treatment with anticoagulants is indicated.

Acquired cystic kidney disease following long-term peritoneal dialysis for congenital nephrotic syndrome.

We describe here the clinicopathological findings in a child with congenital nephrotic syndrome (CNS) non-responsive to medical therapy who developed acquired cystic kidney disease (ACKD) in both native kidneys after long-term peritoneal dialysis. This case indicates that CNS is a further pathologic condition related to the development of ACKD.

Unique pineal gland metastasis of clear cell renal carcinoma: case report and review of the literature.

The metastatic involvement of the pineal gland is an extremely unusual event; it has a 4% incidence in patients with disseminated neoplasias. Most metastatic pineal lesions are asymptomatic. Only in a small number of cases the symptoms produced by metastatic involvement of this organ precede those of the primary tumor or those of another metastatic site. To our knowledge the herein reported case is the first in which the pineal gland was apparently the unique metastatic site of a primitive kidney carcinoma and where the symptoms produced by metastasis in the pineal region were the first sign of the disease.

111 renal neoplasms of childhood: a clinicopathologic study.

PURPOSE: The aim of this study was to perform a clinicopathologic evaluation of a single pediatric institution renal tumor series. Most patients were treated within the frame of 3 consecutive SIOP trials, which included preoperative chemotherapy as their main feature. METHODS: Medical records and diagnoses of 111 patients were reviewed. The association of pathologic features with outcome was investigated by means of the Kaplan-Meier method, the Cox model, and a logistic multivariate analysis. Comparison among different trial results was carried out. RESULTS: In 98 patients (88%), nephroblastoma was diagnosed, followed by 6 adult-type renal tumors, 3 cystic nephromas, 2 mesoblastic nephromas, and 2 clear cell sarcomas. For nephroblastoma, a statistically significant correlation between grade and both disease-free survival rate and 5-year survival rate, and between stage and overall survival rate was shown. Lymph node involvement, local relapse, nephrogenic rests, and older age at presentation appeared to be less important prognostic factors. Tumor spillage was very sensitive to chemo or radiotherapy. No significant difference in outcome was observed among different trials. CONCLUSIONS: Wilms' tumor was the most frequent neoplasm and resulted in a 5-year cure rate of 90%. Clinical course was influenced mainly by diffuse anaplasia and, to a minor extent, by lymph node involvement. Because some tumors followed an unpredictable course, it is likely that also other biological factors played a significant role.

Acquired glomerulocystic kidney disease following hemolytic uremic syndrome.

Glomerulocystic kidney disease (GCKD) is a rare congenital condition that is usually reported in infants and young children. Only five cases of acquired GCKD after an acquired renal disease have been reported. Among these, two patients have developed cystic glomerular lesions following hemolytic uremic syndrome (HUS). We report a third case in a 2-year-old patient with this association. Common features between these three cases include atypical HUS, development of GCKD after prolonged peritoneal dialysis treatment, severe hypertension, and normal-sized kidneys without development of macroscopic cysts. Pathology findings in our patient include heavy expression of epidermal growth factor receptor in proximal tubules and evidence of obstruction of the glomerular outflow. We speculate that cystic dilatation of the Bowman's capsule may be secondary to ischemic lesions leading to proximal tubular obstruction.

Fatal infantile leukodystrophy: a severe variant of CACH/VWM syndrome, allelic to chromosome 3q27.

OBJECTIVE: To describe clinical and neuropathologic studies and linkage analysis on two sisters with a severe form of leukodystrophy. METHODS: A detailed study was performed on the second sister. Genotyping markers for chromosome 3, including eight additional markers surrounding the vanishing white matter (VWM) locus, were used. RESULTS: During the first year of life, two sisters developed a severe neurologic condition after an intercurrent infection. It was accompanied by irritability and stupor with rapid loss of their motor abilities. Results of extensive metabolic studies were negative. Brain MRI showed severe and diffuse abnormalities of the encephalic white matter. Neuropathologic examination showed a severe lack of myelin with diffuse vacuolating white matter lesions in the brain, associated with an increased density of oligodendrocytes and a reduced number of astrocytes on morphometric analysis. In sharp contrast, the spinal cord white matter was preserved. The affected sibpairs shared a common haplotype for a broad region in chromosome 3. They were homozygous between markers D3S1565 and D3S3669, including the VWM locus. CONCLUSIONS: This condition is an unusual variant of childhood ataxia with diffuse central hypomyelination (CACH)/VWM, with characteristic shrinking and perivascular clustering of astrocytes. Haplotype analysis suggests that this variant is allelic to the VWM locus located on chromosome 3q27.

Neuronal ceroid lipofuscinosis: an ultrastructural, genetic, and clinical study report.

The term "neuronal ceroid lipofuscinosis" (NCL) describes a complex of inherited neurodegenerative conditions associated with storage of lipopigments in brain tissue. In 1989 Dyken proposed a classification of NCL based on the age, clinical symptoms, and ultrastructural aspects of the lipopigments. At the ultrastructural level it is possible to distinguish 5 different patterns of osmiophilic lipopigments: usual lipofuscin, fingerprint deposits, granular profiles, curvilinear bodies, and microtubular aggregates. The concept that each ultrastructural pattern was the counterpart of a specific clinical type has been proved not to be true. Advances in molecular genetic techniques have allowed the identification of defective genes and their protein products in several NCL clinical forms. Ceroid lipofuscin deposits may be ultrastructurally observed not only in neuronal cells, but also in several other sites, such as trophoblastic cells, thus permitting prenatal diagnosis. In spite of recent advances in immunohistochemical identification of biochemical markers, the ultrastructural identification of lipofuscinic pigments remains the gold standard to identify NCL, together with clinical aspects and respective gene defects. This study describes the ultrastructural aspects observed in 8 cases of NCL syndromes (3 juvenile, 3 infantile, 1 late infantile, and 1 congenital clinical form). In these patients, genetic analysis was also performed.

[Hemorrhage caused by the rupture of a pancreatic pseudoaneurysm. Case report]. / Hemorragia por ruptura de pseudoaneurisma pancreático. Caso clínico.

We report a 52 year old man with a pancreatic pseudocyst, that was admitted with severe abdominal pain, severe vomiting, fever and malaise. The clinical picture was considered secondary to a pseudocyst infection and the patient was operated, draining the infected cyst performing a necrosis surgery and pancreatojejunostomy. Forty eight hours after the operation, an ostomy bleeding was detected. A upper mesenteric artery angiography showed two pseudoaneurysms in the gastroduodenal artery, that were embolized. Bleeding stopped initially, but seven days later, it reappeared. The patient was subjected to an emergency pancreatoduodenectomy. Postoperative evolution was uneventful and the patient was discharged two weeks later. Spontaneous bleeding of pseudoaneurysms secondary to chronic pancreatitis is a complication with a 15 to 40% mortality that must be bore in mind.

Two familial giant pituitary adenomas associated with overweight: clinical, morphological and genetic features.

OBJECTIVE: Pituitary adenomas are usually sporadic, although rare familial cases have been described. Here we report two first degree female cousins with giant pituitary adenoma and overweight. Both presented with secondary amenorrhoea, occasional headache and weight gain. MATERIALS AND METHODS: In both patients clinical, morphological and genetic studies were performed. Both patients underwent surgery and post-operative medical therapy with somatostatin analogues and dopamine agonist, followed by a conventional radiotherapy course. RESULTS: Clinical examination at presentation revealed an acromegaloid habitus only in the second patient. Basal and dynamic hormonal evaluation showed high serum GH and serum IGF-I values, higher in the second than in the first patient, and a mild hyperprolactinaemia only in the first patient. On optical and electron microscopy, both tumours were oncocytic adenomas, immunopositive for GH in the first patient and GH/prolactin in the second. The genetic analysis for germ-line mutations of the multiple endocrine neoplasia type 1 gene was negative. Two years after radiotherapy a remarkable shrinkage of both tumours was observed, whereas the overweight worsened in both patients, accompanied by high plasma leptin values. CONCLUSION: To our knowledge, this is the first report of familial pituitary adenomas including one case of a clinically silent GH-secreting adenoma. In addition, it provides further evidence that familial pituitary tumours can occur as a multiple endocrine neoplasia type 1 unrelated disease.