Lewy pathology in Parkinson's disease consists of crowded organelles and lipid membranes

Parkinson's disease, the most common age-related movement disorder, is a progressive neurodegenerative disease with unclear etiology. Key neuropathological hallmarks are Lewy bodies and Lewy neurites: neuronal inclusions immunopositive for the protein α-synuclein. In-depth ultrastructural analysis of Lewy pathology is crucial to understanding pathogenesis of this disease. Using correlative light and electron microscopy and tomography on postmortem human brain tissue from Parkinson's disease brain donors, we identified α-synuclein immunopositive Lewy pathology and show a crowded environment of membranes therein, including vesicular structures and dysmorphic organelles. Filaments interspersed between the membranes and organelles were identifiable in many but not all α-synuclein inclusions. Crowding of organellar components was confirmed by stimulated emission depletion (STED)-based super-resolution microscopy, and high lipid content within α-synuclein immunopositive inclusions was corroborated by confocal imaging, Fourier-transform coherent anti-Stokes Raman scattering infrared imaging and lipidomics. Applying such correlative high-resolution imaging and biophysical approaches, we discovered an aggregated protein-lipid compartmentalization not previously described in the Parkinsons' disease brain.

A 100% increase of dopaminergic cells in the olfactory bulb may explain hyposmia in Parkinson's disease

Hyposmia is one of the most prevalent symptoms of Parkinson's disease. It may occur even before the motor symptoms start. To determine whether the olfactory dysfunctions, like the motor symptoms, are associated with a loss of dopamine, the number of dopaminergic cells in the olfactory bulb of Parkinson's disease patients was studied using tyrosine hydroxylase immunohistochemistry. The quantitative analysis reveals that the total number of tyrosine hydroxylase-immunoreactive neurons in the olfactory bulb is twice as high in Parkinson patients compared to age and gender-matched controls. Because dopamine is known to inhibit olfactory transmission in the olfactory glomeruli, we suggest that the increase of dopaminergic neurons in the olfactory bulb is responsible for the hyposmia in Parkinson patients. The increase of dopamine in the olfactory bulb explains why olfaction does not improve with levodopa therapy.

Distribution and Load of Amyloid-β Pathology in Parkinson Disease and Dementia with Lewy Bodies

Parkinson disease (PD), Parkinson disease with dementia (PDD), and Dementia with Lewy bodies (DLB) differ clinically with regard to the presence and timing of dementia. In this postmortem study, we evaluated whether the burden and distribution pattern of amyloid-β (Aβ) pathology differs among these disease entities. We assessed Aβ phases and neuritic plaque scores in 133 patients fulfilling clinical diagnostic criteria for PD, PDD, and DLB, and determined the presence and load of Aβ pathology in 5 cortical and 4 subcortical regions in a subset of patients (n = 89) using a multispectral imaging system. Aβ phases and neuritic plaque scores were higher in DLB versus PDD (both p < 0.001) and in PDD vs PD patients (p = 0.020 and 0.022, respectively). Aβ pathology was more often observed in the entorhinal cortex, amygdala and putamen in DLB versus PDD patients; Aβ load was higher in both cortical and subcortical regions. PDD patients had more frequent Aβ pathology in temporal cortex and higher Aβ load in cortical regions and striatum versus PD patients. Our findings suggest that the load and extent of Aβ pathology may contribute to cognitive dysfunction in PDD and the early-stage severe dementia in DLB.

Kindling induced changes in parvalbumin immunoreactivity in rat hippocampus and its relation to long-term decrease in GABA-immunoreactivity

The immunoreactivity of parvalbumin (PV), a Ca2+-binding protein present in a subpopulation of interneurons, was studied in the hippocampal CA1 region during kindling epileptogenesis, induced by tetanic stimulation of the Schaffer collateral/commissural fibers. PV-immunoreactivity was increased in comparison to controls after 13 afterdischarges and after the induction of generalized seizures. A quantification of the number of PV-immunoreactive somata showed an increase of 20% in both stages of kindling. This level had returned to baseline level 31 days after the last seizure. These results imply that changes in PV-immunoreactivity are related to seizure activity rather than to the long-term increase in seizure sensitivity in kindled animals. Co-localization study in controls showed that 32% of PV-immunoreactive somata were also immunopositive for GABA. A colocalization study in stratum oriens and pyramidale on the stimulated side of kindled animals 31 days after the last generalized seizure showed neither a reduction in the number of PV-immunoreactive somata nor in the number of GABA-immunopositive cell bodies that co-localized with PV. In contrast, the number of GABA-immunoreactive somata that did not co-localize with PV was reduced by 50%. It has been shown that a large influx of Ca2+ plays a crucial role in epileptogenesis. Here we demonstrate that the presence of the calcium-binding protein parvalbumin seems to exert a protective effect against the process that leads to a decrease in GABA content.

Kindling increases the K(+)-evoked Ca2(+)-dependent release of endogenous GABA in area CA1 of rat hippocampus

The release of endogenous amino acids from hippocampal CA1 subslices under basal conditions and the release evoked by high potassium (50 mM K+) depolarization was studied during kindling epileptogenesis. Emphasis was put on the release of the amino acid neurotransmitters gamma-aminobutyric acid (GABA) and glutamate. Kindling was induced by tetanic stimulation of the Schaffer-collaterals/commissural fibers of the dorsal hippocampus of the rat. The calcium-dependent GABA release in the presence of high K+ was significantly increased (40-46%) in fully kindled animals, 24 h after the last seizure, in comparison to controls. At long-term, 28 days after the last seizure, the calcium-dependent GABA release was still significantly increased (45-49%). An increased release of GABA in kindled animals was still found when GABA uptake was blocked by nipecotic acid. In contrast, no significant alterations were encountered in the basal or high potassium induced release of the excitatory amino acids aspartate and glutamate. These results suggest that kindling epileptogenesis is accompanied by a specific and long-lasting enhancement of GABA exocytosis which may lead to a desensitization of the GABA receptor, and thus determine the increase of seizure sensitivity.

The proteome of the locus ceruleus in Parkinson's disease: relevance to pathogenesis

The locus ceruleus is among the earliest affected brain regions in Parkinson's disease (PD) showing Lewy body pathology and neuronal loss. To improve our understanding of the pathogenesis of PD, we performed the first proteomic analysis ever of post-mortem locus ceruleus tissue of six pathologically confirmed PD patients, and six age- and gender-matched non-neurological controls. In total 2495 proteins were identified, of which 87 proteins were differentially expressed in the locus ceruleus of PD patients compared with controls. The majority of these differentially expressed proteins are known to be involved in processes that have been implicated in the pathogenesis of PD previously, including mitochondrial dysfunction, oxidative stress, protein misfolding, cytoskeleton dysregulation and inflammation. Several individual proteins were identified that have hitherto not been associated with PD, such as regucalcin, which plays a role in maintaining intracellular calcium homeostasis, and isoform 1 of kinectin, which is involved in transport of cellular components along microtubules. In addition, pathway analysis suggests a pathogenetic role for aminoacyl-tRNA-biosynthesis. These findings indicate that the proteome of the locus ceruleus of PD patients and non-neurological controls provides data that are relevant to the pathogenesis of PD, reflecting both known and potentially novel pathogenetic pathways.

Decrease in GABA immunoreactivity and alteration of GABA metabolism after kindling in the rat hippocampus

The kindling model of epilepsy, induced by tetanic stimulation of Schaffer collateral/commisural fibers, was studied in the rat hippocampus. Gamma-aminobutyric acid immunoreactivity was used to quantify the number of GABA-immunoreactive somata per mm2 in CA1 region, 28 days after the last generalized seizure. Comparison of the numbers obtained from kindled animals with those from controls, showed a significant decrease (18%) on the ipsilateral stimulated side but none on the contralateral side. In control rats injection of the GABA-transaminase inhibitor, amino oxyacetic acid (AOAA), led to a 46% increase in the number of cell somata immunoreactive for GABA. This probably results from an accumulation of GABA, reflecting GABA synthesis by glutamate decarboxylase (GAD) activity, in somata of interneurons that had initially a GABA content below the immunocytochemical detection threshold. In kindled rats, 31 days after the last seizure, the number of GABA-immunoreactive cells that could be observed after AOAA-treatment was significantly lower (35% ipsilateral and 25% contralateral) when compared to AOAA-treated controls. This suggests that in kindled animals a GAD dependent increase in GABA content did not take place in a subpopulation of interneurons. The observations for kindled rats are interpreted as a long-term decrease in GABA content and as an alteration in GABA turnover in a subpopulation of interneuron somata, the latter possibly due to a decrease in GAD activity. The long-term enhanced seizure sensitivity, characteristic for kindled animals, may be due to a decreased GABAergic inhibitory control of the neuronal circuitry in the CA1 region of the hippocampus.

Misrouted olfactory fibres and ectopic olfactory glomeruli in normal humans and in Parkinson and Alzheimer patients

The presence and distribution of misrouted (MR) olfactory projection fibres were studied in the olfactory bulbs of control human brains and in the brains of people who had suffered from Parkinson's and Alzheimer's disease. It appeared that MR fibres, that is, fibres that terminate deep into the glomerular layer, are a common phenomenon in the bulbs of aged people. In all but one of the bulbs studied, MR fibres are present. The amount of MR fibres is not related to age. With a few exceptions, the MR fibres are restricted to the external plexiform layer (EPL). Only in Parkinson bulbs the MR fibres occasionally form glomerulus-like structures. These pseudo glomeruli are located in the EPL. It is concluded that MR olfactory projection fibres are a normal phenomenon in the human olfactory bulb. In nonhuman mammalians, MR fibres have only been observed in foetal and neonatal olfactory bulbs. Possibly, the age-related loss of mitral cells, which are the natural synaptic targets for the olfactory projection fibres, may play a role in the aberrant behaviour of the MR olfactory receptor cell axons. The ectopic glomerulus-like structures in Parkinson bulbs share some characteristics with normal rat glomeruli that are not observed in normal human olfactory glomeruli. This may refer to possible changes in the genetic content of olfactory structures in Parkinson patients.

Development of changes in endogenous GABA release during kindling epileptogenesis in rat hippocampus

The calcium-dependent gamma-aminobutyric acid (GABA) and glutamate release from rat hippocampal CA1 slices, evoked by a 1-min depolarization with 50 mM K+, was investigated in different stages of kindling epileptogenesis. Kindling was induced by tetanic stimulation of the Schaffer collateral/commissural pathway. In agreement with our previous results, we found a significantly increased calcium-dependent GABA release compared to that of implanted controls, in a group of fully kindled animals 1 day after the last seizure and also 25-36 days after the last seizure. In addition, we found that the increase in GABA release was associated with late phases of kindling epileptogenesis since no significant alterations were found in partly kindled animals that had received only 6 kindling stimulations while a significant increase was apparent in animals that had received 14 tetanic stimuli. When the release protocol was carried out in the presence of SK&F 89776-A, a blocker of the GABA uptake carrier, an additional amount of GABA was found after depolarization. This additional amount of GABA, reflecting the amount of GABA taken up under conditions without blocker, was in kindled animals not different from controls which demonstrates that a reduced GABA uptake does not account for the observed enhanced release in kindled animals. The calcium-dependent release of glutamate evoked by 1 min of high potassium depolarization was not significantly changed in the kindled groups. Only after prolonged depolarization during 4 subsequent minutes a significant increase in animals of the fully kindled group and at long-term after kindling was observed. The threshold K+ concentration for eliciting a calcium-dependent release of GABA and glutamate, was not changed in the kindled animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Soluble glucan protects against endotoxin shock in the rat: the role of the scavenger receptor

Soluble carboxymethyl-b-1,3-glucan (CMG), a possible ligand for scavenger receptors, has macrophage-activating action but lacks the granulomatose inflammatory side effect: it is a promising immunomodulator that may mitigate the severity of sepsis. This motivated us to study in rats the effect of CMG (25 mg/kg), injected into the tail vein at 48 and 24 h prior to the administration of 5 mg/kg Escherichia coli 0127.B8 endotoxin on survival, hemodynamic condition, and, in vitro, on the chemiluminescence of PMNs and macrophages, and on macrophagal tumor necrosis factor (TNF) production. Acetylated low density lipoprotein (AcLDL) clearance in vivo and in vitro binding to macrophages was used to study scavenger receptor function. In the nonpretreated group 9 of 10 rats died during the first 24 h after endotoxin, but all CMG-pretreated rats survived. CMG-pretreatment prevented severe decreases in cardiac output and blood pressure after endotoxin. Chemiluminescence of macrophages and PMNs from CMG-pretreated rats was about two times less (p < .05) than that from nonpretreated ones; the endotoxin induced TNF production by macrophages also decreased. Pretreatment with CMG increased, but coinjection of CMG and AcLDL decreased the AcLDL clearance, while coinjection of endotoxin and AcLDL decreased the survival rate. In vitro AcLDL uptake by macrophages decreased after coinjection with CMG. Our results thus showed that CMG was protective in rat endotoxin shock, which seemed partly connected with enhancement of endotoxin clearance through scavenger receptors and to decreased TNF production.

Chronic neonatal MK-801 administration leads to a long-lasting increase in seizure sensitivity during the early stages of hippocampal kindling

Persistent effects of chronic neonatal administration of the N-methyl-D-aspartate (NMDA) antagonist MK-801 were investigated by measuring susceptibility to CA1 kindling epileptogenesis in adulthood. Rat pups were chronically treated with MK-801 from postnatal day 8 through day 19. Hippocampal kindling showed an increase in electrical seizure duration in the MK-801-treated group as compared with controls along with a more severe expression of behavioral seizures during the first few kindling stimulations. These results show that neonatal interference with NMDA receptor function leads to a long-lasting increase in hippocampal excitability.

Renal function and oxygen consumption during bacteraemia and endotoxaemia in rats

BACKGROUND

The hypothesis that renal failure during septic shock may occur as a result of hypoxia-related cell dysfunction was investigated in two rat models of distributive shock.

METHODS

Pentobarbitone-anaesthetized rats received either a bolus (1 ml) of living Escherichia coli bacteria (hospital-acquired strain, 1 x 10(9) CFU/ml; BA-group, n = 7), or a 1-h infusion of endotoxin (E. coli O127.B8: 8 mg/kg; ET-group, n = 7), or saline to serve as time matched controls (C-group, n = 7).

RESULTS

Urine flow in the BA- and ET-group reached a nadir at 1 h, but thereafter increased and reached values higher than control at 3 h. At this time point, renal oxygen delivery had decreased, in the BA-group mainly due to a fall in arterial oxygen content and in the ET-group to a fall in renal plasma flow (clearance of 131I-hippurate). However, renal oxygen extraction had significantly increased, by 31% in the BA and by 59% in the ET group, while renal oxygen consumption remained the same. Net tubular sodium reabsorption had decreased by 55% in the BA and by 25% in the ET group, due to a fall in glomerular filtration rate (clearance of creatinine). Hence, an excess oxygen consumption was found which was caused neither by an increased renal glucose release nor by the presence of an increased number of leukocytes stuck in the glomeruli. Renal tubular cells showed normal morphology. An indication that proximal tubular function in the BA and ET group remained largely intact were normal ATP levels, absence of urinary glucose, and a normal fractional excretion of sodium. However, since urine flow had increased in shocked rats at 3 h, water appeared selectively lost.

CONCLUSIONS

Our data indicate that in rat models of septic shock renal failure is not caused by cortical hypoxia or a shortage of cellular energy supply.

Tyrosine hydroxylase immunoreactive structures in the aged human olfactory bulb and olfactory peduncle

We studied the anatomical distribution of dopaminergic structures in the normal, aged, human olfactory bulb and olfactory peduncle with a monoclonal antibody against tyrosine hydroxylase. Three different tyrosine hydroxylase containing cell groups are present in the olfactory bulbs: (1) a group of round, medium-sized cells within and around the glomeruli; (2) cells in the external plexiform layer; and (3) cells that are scattered in the stratum album. Occasionally, a few labeled neurons can be observed in the granule cell layer. In the olfactory peduncle a few labeled cells are present in the superficial layers just underneath the pia. Tyrosine hydroxylase containing terminal-like structures are present in the glomerular layer and the external plexiform layer. In a few cases dense terminal labeling is also observed in the cell groups that constitute the anterior olfactory nucleus. In the olfactory peduncle scattered labeled fibers are present. In addition, the present study makes clear that quantitative differences exist between the individual cases for which no explanation could be found.

Neonatal clonidine treatment results in long-lasting changes in noradrenaline sensitivity and kindling epileptogenesis

In the present experiment we tested the hypothesis that early interference with noradrenaline transmission can have permanent consequences for brain function in adulthood. Neonatal depletion of noradrenaline by daily subcutaneous injections of clonidine results in supersensitivity to noradrenaline in adult hippocampal CA1 cells as shown in our previous microiontophoretic study. These findings were confirmed and extended here with dose-response curves. Furthermore, we tested whether this form of neonatal interference with noradrenaline also permanently affects long-lasting plasticity as revealed in kindling epileptogenesis in adulthood. The initiation of the epileptic activity after the kindling stimulation was significantly delayed in the clonidine-treated group, and all measured parameters of seizure expression tended to be retarded in comparison with saline-treated control rats. This indicates that noradrenaline supersensitivity induced by neonatal clonidine treatment retards kindling development in adulthood.

Contactin-1 Is Reduced in Cerebrospinal Fluid of Parkinson's Disease Patients and Is Present within Lewy Bodies

Synaptic degeneration is an early phenomenon in Parkinson's disease (PD) pathogenesis. We aimed to investigate whether levels of synaptic proteins contactin-1 and contactin-2 in cerebrospinal fluid (CSF) of PD patients are reduced compared to dementia with Lewy bodies (DLB) patients and controls and to evaluate their relationship with α-synuclein aggregation. Contactin-1 and -2 were measured in CSF from PD patients (n = 58), DLB patients (n = 72) and age-matched controls (n = 90). Contactin concentration differences between diagnostic groups were assessed by general linear models adjusted for age and sex. Contactin immunoreactivity was characterized in postmortem substantia nigra, hippocampus and entorhinal cortex tissue of PD patients (n = 4) and controls (n = 4), and its relation to α-syn aggregation was evaluated using confocal laser scanning microscopy. Contactin-1 levels were lower in PD patients (42 (36-49) pg/mL) compared to controls (52 (44-58) pg/mL, p = 0.003) and DLB patients (56 (46-67) pg/mL, p = 0.001). Contactin-2 levels were similar across all diagnostic groups. Within the PD patient group, contactin-1 correlated with t-α-syn, tTau and pTau (r = 0.30-0.50, p < 0.05), whereas contactin-2 only correlated with t-α-syn (r = 0.34, p = 0.03). Contactin-1 and -2 were observed within nigral and cortical Lewy bodies and clustered within bulgy Lewy neurites in PD brains. A decrease in CSF contactin-1 may reflect synaptic degeneration underlying Lewy body pathology in PD.

Transient increase of cytoplasmic calcium concentration in the rat hippocampus after kindling-induced seizures. An ultrastructural study with the oxalate-pyro-antimonate technique

Kindling stimulations were applied to the Schaffer collateral/commissural fibers in the CA1 area of the dorsal rat hippocampus. In fully kindled animals the ultrastructural distribution of calcium was studied at different time intervals after an induced generalized seizure, using the oxalate-pyro-antimonate technique. Semi-quantitative analysis of the amount of precipitate revealed no change in the investigated structures analysed after 2 h or 24 h: boutons and spines of the Schaffer-collateral/pyramidal-dendrite synaptic contacts, cytoplasm and mitochondria of terminals on pyramidal cell bodies and smooth dendrites. The major change was found 15 min after a seizure, when calcium precipitate in boutons and spines of stratum radiatum was strongly increased, precipitate in somata terminals only slightly, while smooth dendrites were not affected. These results imply a seizure-related increase of the intracellular calcium concentration. The transient character suggests that the investigated cellular compartments in kindled tissue are still capable of maintaining calcium homeostasis. The observed increase in precipitate density for at least 15 min may initiate the neurochemical mechanisms leading to an enhanced seizure sensitivity in the kindling model of epilepsy.

Laparotomy and renal function during endotoxin shock in rats

Despite the wide use of laparotomy to study kidney function, the possible influence of this procedure on systemic and renal parameters in septic rats is unknown. We studied this in anesthetized Wistar rats with and without endotoxin shock (1 h Escherichia coli O 127.B8: 8 mg.kg-1 infusion). We also compared clearance of creatinine and inulin to measure glomerular filtration rate (GFR). Laparotomy attenuated the endotoxin-induced decrease in cardiac output and abolished the increase in systemic and renal vascular resistance, while renal plasma flow was maintained. Better perfusion in other organs as well was indicated by a more gradual increase in arterial lactate concentration and less intestinal damage. By contrast, GFR decreased considerably during endotoxemia, irrespective of laparotomy. This change in GFR could be reliably assessed using creatinine clearance. The ratio of creatinine-to-inulin clearance averaged between .5 and .75. Renal ATP content did not change and the endotoxin-induced increase in the number of granulocytes lodged in glomeruli was not affected by laparotomy. In conclusion, our study indicates that laparotomy significantly influences the vascular effects caused by endotoxin. Laparotomy also revealed an effect of endotoxin on GFR, independent of renal blood flow.

Influence of fluid resuscitation on renal function in bacteremic and endotoxemic rats

PURPOSE

Fluid resuscitation, which is the most important primary therapy in sepsis, is not always able to prevent acute renal failure. In this study, we investigated in two different rat models of distributive shock whether fluid resuscitation would increase renal plasma flow (RPF) and subsequently glomerular filtration rate (GFR).

MATERIALS AND METHODS

In pentobarbital anesthetized wistar rats Haemaccel (Behring Pharma, Hoechst, the Netherlands) infusion (1.2 mL/100 g/h for 3 hours) was started immediately during either bacteremia (bolus of living Escherichia coli bacteria, 10(9) or endotoxemia (1 hour infusion of E. coli endotoxin, 8 mg/kg), as well as in time-matched healthy controls.

RESULTS

After 3 hours, this treatment had increased RPF (clearance of 131I-hippurate) above normal in control (+67%) and bacteremic rats (+75%), whereas in endotoxemic animals, the significantly decreased RPF was normalized. On the other hand, in bacteremic animals, the lowered GFR (clearance of creatinine; x44%) was normalized, whereas in endotoxemic animals GFR remained depressed (x30%). The lack of improvement in GFR during endotoxemia was also indicated by a profound fall in urine flow, which by contrast steadily increased in control and bacteremic rats owing to volume loading. In both shocked groups, the decreased renal oxygen delivery was normalized, but the higher renal oxygen consumption than expected on the basis of the work needed for sodium reabsorption was not influenced by Haemaccel treatment, despite the fact that it caused this work load to rise in bacteremic but not in endotoxemic rats. In both shock models, renal cortical adenosine triphosphate content did not differ from healthy controls and was not influenced by volume loading.

CONCLUSIONS

In conclusion, our study suggests that a decrease in GFR caused by live bacteria in the circulation may benefit from fluid resuscitation, while during endotoxemia this therapy could not prevent acute renal failure.

Protective role of NO in the regional hemodynamic changes during acute endotoxemia in rats

The role of NO during the first hour of endotoxemia is still controversial. To evaluate whether NO is protective or detrimental to the regulation of systemic blood pressure, cardiac output (CO), and organ perfusion in rats during acute endotoxemia, we have studied the effects of inhibition of NO synthesis. Thirty minutes after 0.1 mg NG-nitro-L-arginine (L-NNA; group L, n = 7, partial inhibition), 1 mg L-NNA (group H, n = 6, complete inhibition), or saline (group E, n = 7) intravenous infusion, anesthetized volume-loaded rats were infused with endotoxin Escherichia coli O127:B8 (8 mg.kg-1 x h-1) from time (t) = 0 to 60 min. Organ blood flow was measured with radioactive microspheres. In group H, at time 0, CO was lower than in group E (by -29%; P < 0.05), and systemic vascular resistance (SVR) was higher than in groups E and L (by 72 and 51%, respectively; P < 0.05). Perfusion of the pancreas, stomach, intestines, and kidney was lower (P < 0.05) and corresponding organ vascular resistance (OVR) higher (P < 0.05) in group H than in groups E and L (except kidney in group L). At t = 60 min, in groups H and L, CO was lower (by -45 and -26%, respectively; P < 0.05) and SVR was higher (by 112 and 54%, respectively; P < 0.05) than in group E. In group L only blood flow to the heart, pancreas, intestines, and kidney was significantly lower than in group E, and corresponding OVR was higher.(ABSTRACT TRUNCATED AT 250 WORDS)

THREE-DIMENSIONAL RECONSTRUCTION OF THE ANTERIOR OLFACTORY NUCLEUS IN THE HUMAN OLFACTORY BULB AND PEDUNCLE. Reconstrucción tridimiensional del núcleo olfatorio anterior en el bulbo y pedúnculo olfatorio humano

El bulbo y pedúnculo olfatorio humano contienen muchos grupos celulares más o menos separados que habitualmente son considerados como parte del núcleo olfatorio anterior retro-bulbar (AON). La presunción que estos grupos celulares sean considerados como extensión rostral del AON en el hemisferio rostral retrocede a la descripción de un único caso por Crosby y Humphrey (1941). Para mejorar nuestra comprensión de la anatomía del AON bulbar y peduncular humano investigamos la morfología, forma y tamaño de estas partes en este núcleo en tejido post-mortem de individuos de edades conocidas. Se obtuvieron seis bulbos y pedúnculos olfatorios, incluyendo la sustancia perforada anterior (SPA), de cerebros donados; se realizaron cortes seriales horizontales a 40µm y se tiñó con substancia de Nissl. Las neuronas de tamaño mediano a grande de esta parte del AON se tiñeron intensamente y tenían un diámetro promedio de 16µm. La reconstruc-ción tridimensional demostró que en todos los casos, excepto uno, el AON bulbar y peduncular consistieron en una cadena discontinua de grupos celulares conectados por puentes de neuropilas pobres o libres de células. El número de grupos celulares y de puentes conectores difiere en cada individuo. Concluimos que las porciones bulbar y peduncular del AON humano debería ser considerado como una especialización humana más que como una extensión rostral del área AON retro-bulbar. Esto es acorde con las propiedades neuro-clínicas previamente publicadas y la degeneración temprana selectiva, pre-clínica, de estos nichos celulares en la enfermedad neuro-degenerativa. The human olfactory bulb and peduncle contain several more or less separated cell groups that are usually regarded to be part of the retrobulbar anterior olfactory nucleus (AON). The assumption that these cell groups are to be considered as the rostral extension of the AON in the rostral hemisphere goes back to the description of one single case by Crosby and Humphrey (1941). To improve our understanding of the anatomy of the human bulbar and peduncular AON, we investigated the morphology, size and shape of these parts of this nucleus in postmortem tissue of aged individuals. Six olfactory bulbs and peduncles including the substantia perforata anterior (SPA) were obtained from donor brains and 40µm horizontal serial sections were cut and stained with Nissl substance. The medium to large sized neurons of these parts of the AON were intensely stained and had an average diameter of 16µm. Three dimensional reconstruction demonstrated that in all but one of the cases the bulbar and peduncular AON consisted on a discontinuous chain of cell groups connected by cell poor to cell free bridges of neuropile. The number of cell groups and the connecting bridges differ in every individual. We arrived at the conclusion that the bulbar and peduncular parts of the human AON should be regarded a human specialization rather than just being rostral extensions of the retrobulbar AON area. This is in line with previously published neurochemical properties and the selective early, preclinical degener-ation of these cell clusters in neurodegenerative diseases. 

Gram-negative shock in rats depends on the presence of capsulated bacteria and is modified by laparotomy

To develop a hyperdynamic sepsis model in rats, four Escherichia coli strains were used, which differed in the presence or absence of a capsule or K antigen (K1 and K-, respectively) and/or in O serogroup (O9 and O18). Of the two clinical isolates, O9K- did not survive in rat serum, whereas O18K1 and two isogenic laboratory strains (O18K1 and O18K-) were able to resist serum bacteriolysis. Pentobarbital-anesthetized rats (n = 21) received an intravenous bolus of 10(9) bacteria. In contrast to the two noncapsulated strains, both capsulated strains induced hyperdynamic shock; arterial lactate rose from a mean value of .91 to 3.09 mmol.L-1, systemic vascular resistance dropped from 1.15 to .78 mmHg.min.mL-1, and cardiac output transiently increased from 98 to 115 mL.min-1; renal plasma flow remained at 3-4 mL.min-1, whereas glomerular filtration rate decreased from 1.3 to .7 mL.min-1. Laparotomy, which is often performed to study kidney function, completely abolished the hyperdynamic condition, while glomerular filtration rate was still decreased. We conclude that in rats, in contrast to humans, capsulated bacteria are required to induce a hyperdynamic septic shock; the hyperdynamic characteristics of the shock do not occur in animals subjected to a laparotomy.

Tuberculin skin test reaction depends on type of purified protein derivative: implications for cut-off values

SETTING: Due to purified protein derivative (PPD) RT23 stock-outs in 2014, PPD-Tubersol and PPD-Bulbio have been used for latent tuberculosis infection (LTBI) testing in the Netherlands.OBJECTIVE: To determine whether PPD-RT23, PPD-Tubersol and PPD-Bulbio were associated with differential indurations and confirmation using interferon-gamma release assays (IGRAs).DESIGN: LTBI surveillance data from 2013 to 2016 were extracted. Regression analyses were used to determine whether IGRA confirmation of TST-positive indurations depended on PPD, controlling for sex, age, incidence in country of origin, and bacille Calmette-Guérin (BCG) status.RESULTS: A total of 20 956 individuals were tested with PPD-RT23: 10 382 with PPD-Tubersol and 18 562 with PPD-Bulbio. Overall, 21% with PPD-Bulbio had an induration of ≥5 mm compared to 12% of those tested with PPD-RT23 and PPD-Tubersol. Compared to PPD-RT23, PPD-Bulbio indurations ≥5 mm were significantly less often IGRA-confirmed among contacts (aOR 1.3, 95% CI 1.1-1.6) and BCG-vaccinated immigrants (PPD-RT23, aOR 2.4, 95% CI 1.4-4.1). Increasing the PPD-Bulbio cut-off from ≥5 to ≥10 mm would save respectively 26%, 42%, and 35% of IGRAs among contacts, health care workers (HCWs) and BCG-vaccinated immigrants, with small absolute numbers of positive IGRAs missed (range 0-55 annually).CONCLUSION: PPD-Bulbio shows larger TST indurations than other PPDs, but is less often IGRA-confirmed. Increasing the TST cut-off from 5 to 10 mm prior to testing with an IGRA in HCWs and immigrants is recommended.

Distinct ultrastructural phenotypes of glial and neuronal alpha-synuclein inclusions in multiple system atrophy

Multiple system atrophy is characterized pathologically by the accumulation of alpha-synuclein (aSyn) into glial cytoplasmic inclusions (GCIs). The mechanism underlying the formation of GCIs is not well understood. In this study, correlative light and electron microscopy was employed to investigate aSyn pathology in the substantia nigra and putamen of post-mortem multiple system atrophy brain donors. Three distinct types of aSyn immuno-positive inclusions were identified in oligodendrocytes, neurons and dark cells presumed to be dark microglia. Oligodendrocytes contained fibrillar GCIs that were consistently enriched with lysosomes and peroxisomes, supporting the involvement of the autophagy pathway in aSyn aggregation in multiple system atrophy. Neuronal cytoplasmic inclusions exhibited ultrastructural heterogeneity resembling both fibrillar and membranous inclusions, linking multiple systems atrophy and Parkinson's disease. The novel aSyn pathology identified in the dark cells, displayed GCI-like fibrils or non-GCI-like ultrastructures suggesting various stages of aSyn accumulation in these cells. The observation of GCI-like fibrils within dark cells suggests these cells may be an important contributor to the origin or spread of pathological aSyn in multiple system atrophy. Our results suggest a complex interplay between multiple cell types that may underlie the formation of aSyn pathology in multiple system atrophy brain and highlight the need for further investigation into cell-specific disease pathologies in multiple system atrophy.