Evolution of T1 Relaxation, ADC, and Fractional Anisotropy during Early Brain Maturation: A Serial Imaging Study on Preterm Infants.

BACKGROUND AND PURPOSE: The alteration of brain maturation in preterm infants contributes to neurodevelopmental disabilities during childhood. Serial imaging allows understanding of the mechanisms leading to dysmaturation in the preterm brain. The purpose of the present study was to provide reference quantitative MR imaging measures across time in preterm infants, by using ADC, fractional anisotropy, and T1 maps obtained by using the magnetization-prepared dual rapid acquisition of gradient echo technique. MATERIALS AND METHODS: We included preterm neonates born at <30 weeks of gestational age without major brain lesions on early cranial sonography and performed 3 MRIs (3T) from birth to term-equivalent age. Multiple measurements (ADC, fractional anisotropy, and T1 relaxation) were performed on each examination in 12 defined white and gray matter ROIs. RESULTS: We acquired 107 MRIs (35 early, 33 intermediary, and 39 at term-equivalent age) in 39 cerebral low-risk preterm infants. Measures of T1 relaxation time showed a gradual and significant decrease with time in a region- and hemispheric-specific manner. ADC values showed a similar decline with time, but with more variability than T1 relaxation. An increase of fractional anisotropy values was observed in WM regions and inversely a decrease in the cortex. CONCLUSIONS: The gradual change with time reflects the progressive maturation of the cerebral microstructure in white and gray matter. Our study provides reference trajectories from 25 to 40 weeks of gestation of T1 relaxation, ADC, and fractional anisotropy values in low-risk preterm infants. We speculate that deviation thereof might reflect disturbed cerebral maturation; the correlation of this disturbed maturation with neurodevelopmental outcome remains to be addressed.

Analyzing lifelong learning student behavior in a progressive degree

Peer-reviewed

Childhood community-acquired pneumonia

Background: Community-acquired pneumonia is a leading cause of morbidity and mortality in children worldwide. New, rapid methods are needed to improve the microbiologic diagnosis of pneumonia in clinical practice. The increasing incidence of parapneumonic empyema in children accentuates the importance of the identification of the causative agent and clinical predictors of empyema. Aims and methods: Two prospective studies were conducted to find feasible diagnostic methods for the detection of causative agents of pneumonia. The usefulness of pneumolysin-targeted real-time PCR in the diagnosis of pneumococcal disease was studied in children with pneumonia and empyema, and the clinical utility of induced sputum analysis in the microbiologic diagnosis of pneumonia was investigated in children with pneumonia. In addition, two retrospective clinical studies were performed to describe the frequency and clinical profile of influenza pneumonia in children and the frequency, clinical profile and clinical predictors of empyema in children. Results: Pneumolysin-PCR in pleural fluid significantly improved the microbiologic diagnosis of empyema by increasing the detection rate of pneumococcus almost tenfold to that of pleural fluid culture (75 % vs. 8 %). In whole blood samples, PCR detected pneumococcus in only one child with pneumonia and one child with pneumococcal empyema. Sputum induction provided good-quality sputum specimens with high microbiologic yield. Streptococcus pneumoniae (46 %) and rhinovirus (29 %) were the most common microbes detected. The quantification results of the paired sputum and nasopharyngeal aspirate specimens provided support that the majority of the bacteria (79 %) and viruses (55 %) found in sputum originated from the lower airways. Pneumonia was detected in 14 % of children with influenza infection. A history of prolonged duration of fever, tachypnea, and pain on abdominal palpation were found to be independently significant predictors of empyema. Conclusions: Pneumolysin-targeted real-time PCR is a useful and rapid method for the diagnosis of pneumococcal empyema in children. Induced sputum analysis with paired nasopharyngeal aspirate analysis can be of clinical value in the microbiologic diagnosis of pneumonia. Influenza pneumonia is an infrequent and generally benign disease in children with rare fatalities. Repeat chest radiograph and ultrasound imaging are recommended in children with pneumonia presenting with clinical predictors of empyema and in children with persistent fever and high CRP levels during hospitalization.

Community-acquired pneumonia in adult patients with special reference to rapid methods for etiological diagnosis

Aikuispotilaan kotisyntyisen keuhkokuumeen etiologinen diagnostiikka mikrobiologisilla pikamenetelmillä Tausta. Keuhkokuume on vakava sairaus, johon sairastuu Suomessa vuosittain n. 60 000 aikuista. Huolimatta siitä, että taudin hoito on kehittynyt, siihen liittyy yhä merkittävä, 6-15%:n kuolleisuus. Alahengitystieinfektion aiheuttajamikrobien tunnistaminen on myös edelleen haasteellista. Tavoitteet. Tämän työn tavoitteena oli tutkia Turun yliopistollisessa keskussairaalassa hoidettujen aikuispotilaiden keuhkokuumeen etiologiaa sekä selvittää uusien mikrobiologisten pikamenetelmi¬en hyödyllisyyttä taudinaiheuttajan toteamisessa. Aineisto. Osatöiden I ja III aineisto koostui 384 Turun yliopistollisen keskussairaalaan infektio-osastolla hoidetusta keuhkokuumepotilaasta. Osatyössä I tutkittiin keuhkokuumeen aiheuttaja¬mikrobeja käyttämällä perinteisten menetelmien lisäksi antigeeniosoitukseen ja PCR-tekniikkaan perustuvia pikamenetelmiä. Osatyö II käsitti 231 potilaasta koostuvan alaryhmän, jossa tutkittiin potilaiden nielun limanäytteestä rinovirusten ja enterovirusten esiintyvyyttä. Osatyössä III potilailta tutkittiin plasman C-reaktiivisen proteiinin (CRP) pitoisuus ensimmäisten viiden sairaalahoitopäi¬vän aikana. Laajoja tilastotieteellisiä analyysejä käyttämällä selvitettiin CRP:n käyttökelpoisuutta sairauden vaikeusasteen arvioinnissa ja komplikaatioiden kehittymisen ennustamisessa. Osatyössä IV 68 keuhkokuumepotilaan sairaalaan tulovaiheessa otetuista näytteistä määritettiin neutrofiilien pintareseptorien ekspressio. Osatyössä V analysoitiin sisätautien vuodeosastoilla vuosina 1996-2000 keuhkokuumepotilaille tehtyjen keuhkohuuhtelunäytteiden laboratoriotutkimustulokset. Tulokset. Keuhkokuumeen aiheuttaja löytyi 209 potilaalta, aiheuttajamikrobeja löydettiin kaikkiaan 230. Näistä aiheuttajista 135 (58.7%) löydettiin antigeenin osoituksella tai PCR-menetelmillä. Suu¬rin osa, 95 (70.4%), todettiin pelkästään kyseisillä pikamenetelmillä. Respiratorinen virus todettiin antigeeniosoituksella 11.1% keuhkokuumepotilaalla. Eniten respiratorisia viruksia löytyi vakavaa keuhkokuumetta sairastavilta potilailta (20.3%). 231 keuhkokuumepotilaan alaryhmässä todettiin PCR-menetelmällä picornavirus 19 (8.2%) potilaalla. Respiratorinen virus löytyi tässä potilasryh¬mässä kaiken kaikkiaan 47 (20%) potilaalta. Näistä 17:llä (36%) löytyi samanaikaisesti bakteerin aiheuttama infektio. CRP-tasot olivat sairaalaan tulovaiheessa merkitsevästi korkeammat vakavaa keuhkokuumetta (PSI-luokat III-V) sairastavilla potilailla kuin lievää keuhkokuumetta (PSI-luokat I-II) sairastavilla potilailla (p <0.001). Yli 100 mg/l oleva CRP-taso neljän päivän kuluttua sairaa¬laan tulosta ennusti keuhkokuumeen komplikaatiota tai huonoa hoitovastetta. Neutrofiilien komple¬menttireseptorin ekspressio oli pneumokokin aiheuttamaa keuhkokuumetta sairastavilla merkitse¬västi korkeampi kuin influenssan aiheuttamaa keuhkokuumetta sairastavilla. BAL-näytteistä vain yhdessä 71:stä (1.3%) todettiin diagnostinen bakteerikasvu kvantitatiivisessa viljelyssä. Uusilla menetelmilläkin keuhkokuumeen aiheuttaja löytyi vain 9.8% BAL-näytteistä. Päätelmät. Uusilla antigeeniosoitus- ja PCR-menetelmillä keuhkokuumeen etiologia voidaan saada selvitettyä nopeasti. Lisäksi näitä menetelmiä käyttämällä taudin aiheuttajamikrobi löytyi huomattavasti suuremmalta osalta potilaista kuin pelkästään tavanomaisia menetelmiä käyttämällä. Pikamenetelmien hyödyllisyys vaihteli taudin vaikeusasteen mukaan. Respiratorinen virus löytyi huomattavan usein keuhkokuumetta sairastavilta potilailta, ja näiden potilaiden taudinkuva oli usein vaikea. Tulovaiheen korkeaa CRP-tasoa voidaan käyttää lisäkeinona arvioitaessa keuhkokuumeen vaikeutta. CRP on erityisen hyödyllinen arvioitaessa hoitovastetta ja riskiä komplikaatioiden ke¬hittymiseen. Neutrofiilien komplementtireseptorin ekspression tutkiminen näyttää lupaavalta pi¬kamenetelmältä erottamaan bakteerien ja virusten aiheuttamat taudit toisistaan. Antimikrobihoitoa saavilla potilailla BAL-tutkimuksen löydökset olivat vähäiset ja vaikuttivat hoitoon vain harvoin.

Progressive Purkinje Cell Degeneration in tambaleante Mutant Mice Is a Consequence of a Missense Mutation in HERC1 E3 Ubiquitin Ligase

The HERC gene family encodes proteins with two characteristic domains: HECT and RCC1-like. Proteins with HECT domain shave been described to function as ubiquitin ligases, and those that contain RCC1-like domains have been reported to function as GTPases regulators. These two activities are essential in a number of important cellular processes such as cell cycle, cell signaling, and membrane trafficking. Mutations affecting these domains have been found associated with retinitis pigmentosa, amyotrophic lateral sclerosis, and cancer. In humans, six HERC genes have been reported which encode two subgroups of HERC proteins: large (HERC1-2) and small (HERC3-6). The giant HERC1 protein was the first to be identified. It has been involved in membrane trafficking and cell proliferation/growth through its interactions with clathrin, M2-pyruvate kinase, and TSC2 proteins. Mutations affecting other members of the HERC family have been found to be associated with sterility and growth retardation. Here, we report the characterization of a recessive mutation named tambaleante, which causes progressive Purkinje cell degeneration leading to severe ataxia with reduced growth and lifespan in homozygous mice aged over two months. We mapped this mutation in mouse chromosome 9 and then performed positional cloning. We found a GuA transition at position 1448, causing a Gly to Glu substitution (Gly483Glu) in the highly conserved N- terminal RCC1-like domain of the HERC1 protein. Successful transgenic rescue, with either a mouse BAC containing the normal copy of Herc1 or with the human HERC1 cDNA, validated our findings. Histological and biochemical studies revealed extensive autophagy associated with an increase of the mutant protein level and a decrease of mTOR activity. Our observations concerning this first mutation in the Herc1 gene contribute to the functional annotation of the encoded E3 ubiquitin ligase and underline the crucial and unexpected role of this protein in Purkinje cell physiology.

Histopathology of dairy cows' hooves with signs of naturally acquired laminitis

The purpose of this study was to investigate histological changes in dairy cows' hooves with or without injuries from naturally acquired laminitis. Cull cows with no clinical signs of hoof abnormalities (G1, n=9) and those with macroscopic lesions associated with laminitis without (G2, n=23) or with lameness (G3, n=7) were used in the study. After slaughter, samples of dermo-epidermal junctions of sole, axial and dorsal regions of the hoof were obtained and histologically processed using HE and PAS staining. Congestion, hemorrhage and inflammatory infiltrate in the dermis of sole, axial and dorsal regions were blindly and semiquantitatively evaluated by the same researcher. Inflammatory infiltrate was evaluated in the dermal laminae of axial and dorsal regions. The morphology of epidermal cells and the presence of irregularities in three regions of the basement membrane (BM) length were examined using PAS staining. Scores of lesions in different regions of the hoof in the same group and in different groups for each region of the hoof were compared using non-parametric analyses. Inflammatory infiltrate in the dermis of all regions of the hoof was detected in all groups with no significant statistical difference. Cows with no clinical signs of hoof abnormalities secondary to laminitis (G1) have inflammation scores and epidermal cell changes similar to those of groups with laminitis injuries, suggesting the existence of a prodromal phase for this disease in bovines. BM had irregularities with a variable intensity along its length, however, with no difference among groups. The pattern of BM irregularities found has not been reported so far and does not resemble the BM collapse described in horses and cattle with induced acute laminitis. Is it concluded that even in the absence of macroscopic hoof signs associated to laminitis, dairy cows have histological injuries compatible with inflammation of the dermo-epidermal junction as in affected animals. Basement membrane of cows with or without laminitis associated lesions had irregularities with an irregular distribution along its length which need to be further studied.

Slurry flows in progressive cavity and in hose pumps

The aim of this thesis was to research how slurry’s viscosity and rheology affect to pumping in peristaltic hose pump and in eccentric progressive cavity pump. In addition, it was researched the formed pressure pulsation in hose pump. Pressure pulsation was studied by pumping different slurries and by using different pipe materials. Pressure and power curves were determined for both used pumps. It was also determined NPSHR curve for the progressive cavity pump. Literature part of the thesis considered to distribute fluids to different rheology types, as well as theories and models to identify different rheology types. Special attention was paid to non-Newtonian fluids, which were also used in experimental part of this thesis. In addition, the literature part discusses about pumps, parameters for pump sizing, and pressure pulsation in hose pump. Starch, bentonite, and carboxymethyl cellulose slurries were used in the experimental part of this thesis. The slurries were pumped with Flowrox peristaltic hose pump (LPP-T32) and eccentric progressive cavity pump (C10/10). From the each slurry was taken a sample, and the samples were analyzed for concentration, viscosity and rheology type. The used pipe materials in pressure pulsation experiments were steel and elastic, and it was also used a prototype of pulsation dampener. The pulsation experiments indicated that the elastic pipe and the prototype of pulsation dampener attenuated pressure pulsation better than the steel pipe at low pressure levels. The differences between different materials disappeared when pressure level and pump rotation speed increased. In slurry experiments, pulsation was different depending on rheology and viscosity of the slurry. According to experiments, the rheology did not significantly affect to pump power consumption or efficiency.

Cytokines in innate and acquired immunity to Trypanosoma cruzi infection

Resistance to Trypanosoma cruzi infections is critically dependent on cytokine-mediated activation of cell-mediated immune effector mechanisms. This review focuses on the role of IL-10, TNF-a, IFN-g and IL-12 in controlling T. cruzi replication by the innate and specific immune systems of the vertebrate host. A study performed on mice with disrupted recombinase-activating genes (RAG/KO), which lack T and B lymphocytes, revealed the importance of IL-12, IFN-g and TNF-a in the resistance against T. cruzi mediated by the innate immune system. In addition, data from experiments using IL-10 KO, RAG/KO and double RAG/IL-10 KO mice indicating an in vivo regulatory role of IL-10 in innate and T. cruzi-specific immunity are discussed

Cell proliferation and migration in the jejunum of suckling rats submitted to progressive fasting

Cell proliferation and migration in the intestinal crypts, and cell migration in the villus are controlled by different mechanisms in adult rats. In the present study, weanling rats and fasting rats were used to quantitatively study the correlation of cell cycle parameters and epithelial cell migration in crypts and intestinal villi. Eighteen-day-old rats received a single injection of tritiated thymidine [3H]TdR (23:00 h); half of the pups were submitted to fasting 5 h earlier. Cell proliferation was determined in radioautographs of jejunal crypts, on the basis of the labeling indices (LI) taken 1, 8, 13 and 19 h after [3H]TdR. The results showed that the labeling index did not differ 1 h or 19 h after [3H]TdR between the fed (38.7% or 48%) and fasting groups (34.6% or 50.4%). The modified method of grain count halving indicated that cell cycle time did not differ between fed (16.5 h) and fasting rats (17.8 h); the growth fraction, however, had lower values in fasting (59%) than in fed rats (77%). Cell migration in the crypt, estimated by the LI obtained for each cell position, did not change with treatment. As for the villi, the cell migration rate was significantly retarded by 3 cell positions (8%). These results suggest that the cell migration in the villi of weanling pups does not depend directly on the cell proliferation and migration in the intestinal crypt, but is directly affected by the absence of food in the lumen

Changes in red blood cell osmotic fragility induced by total plasma and plasma fractions obtained from rats bearing progressive and regressive variants of the Walker 256 tumor

Two variants (A and B) of the widely employed Walker 256 rat tumor cells are known. When inoculated sc, the A variant produces solid, invasive, highly metastasizing tumors that cause severe systemic effects and death. We have obtained a regressive variant (AR) whose sc growth is slower, resulting in 70-80% regression followed by development of immunity against A and AR variants. Simultaneously with the beginning of tumor regression, a temporary anemia developed (~8 days duration), accompanied by marked splenomegaly (~300%) and changes in red blood cell osmotic fragility, with mean corpuscular fragility increasing from 4.1 to 6.5 g/l NaCl. The possibility was raised that plasma factors associated with the immune response induced these changes. In the present study, we identify and compare the osmotic fragility increasing activity of plasma fractions obtained from A and AR tumor bearers at different stages of tumor development. The results showed that by day 4 compounds precipitating in 60% (NH4)2SO4 and able to increase red blood cell osmotic fragility appeared in the plasma of A and AR tumor bearers. Later, these compounds disappeared from the plasma of A tumor bearers but slightly increased in the plasma of AR tumor bearers. Furthermore, by day 10, compounds precipitating between 60 and 80% (NH4)2SO4 and with similar effects appeared only in plasma of AR tumor bearers. The salt solubility, production kinetics and hemolytic activity of these compounds resemble those of the immunoglobulins. This, together with their preferential increase in rats bearing the AR variant, suggest their association with an immune response against this tumor.

The decreased oxygen uptake during progressive exercise in ischemia-induced heart failure is due to reduced cardiac output rate

We tested the hypothesis that the inability to increase cardiac output during exercise would explain the decreased rate of oxygen uptake (VO2) in recent onset, ischemia-induced heart failure rats. Nine normal control rats and 6 rats with ischemic heart failure were studied. Myocardial infarction was induced by coronary ligation. VO2 was measured during a ramp protocol test on a treadmill using a metabolic mask. Cardiac output was measured with a flow probe placed around the ascending aorta. Left ventricular end-diastolic pressure was higher in ischemic heart failure rats compared with normal control rats (17 ± 0.4 vs 8 ± 0.8 mmHg, P = 0.0001). Resting cardiac index (CI) tended to be lower in ischemic heart failure rats (P = 0.07). Resting heart rate (HR) and stroke volume index (SVI) did not differ significantly between ischemic heart failure rats and normal control rats. Peak VO2 was lower in ischemic heart failure rats (73.72 ± 7.37 vs 109.02 ± 27.87 mL min-1 kg-1, P = 0.005). The VO2 and CI responses during exercise were significantly lower in ischemic heart failure rats than in normal control rats. The temporal response of SVI, but not of HR, was significantly lower in ischemic heart failure rats than in normal control rats. Peak CI, HR, and SVI were lower in ischemic heart failure rats. The reduction in VO2 response during incremental exercise in an ischemic model of heart failure is due to the decreased cardiac output response, largely caused by depressed stroke volume kinetics.

Imaging Neuroinflammation in Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system CNS), where inflammation and neurodegeneration lead to irreversible neuronal damage. In MS, a dysfunctional immune system causes auto‐reactive lymphocytes to migrate into CNS where they initiate an inflammatory cascade leading to focal demyelination, axonal degeneration and neuronal loss. One of the hallmarks of neuronal injury and neuroinflammation is the activation of microglia. Activated microglia are found not only in the focal inflammatory lesions, but also diffusely in the normal‐appearing white matter (NAWM), especially in progressive MS. The purine base, adenosine is a ubiquitous neuromodulator in the CNS and also participates in the regulation of inflammation. The effect of adenosine mediated via adenosine A2A receptors has been linked to microglial activation, whereas modulating A2A receptors may exert neuroprotective effects. In the majority of patients, MS presents with a relapsing disease course, later advancing to a progressive phase characterised by a worsening, irreversible disability. Disease modifying treatments can reduce the severity and progression in relapsing MS, but no efficient treatment exists for progressive MS. The aim of this research was to investigate the prevalence of adenosine A2A receptors and activated microglia in progressive MS by using in vivo positron emission tomography (PET) imaging and [11C]TMSX and [11C](R)‐PK11195 radioligands. Magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) was performed to evaluate structural brain damage. Non‐invasive input function methods were also developed for the analyses of [11C]TMSX PET data. Finally, histopathological correlates of [11C](R)‐PK11195 radioligand binding related to chronic MS lesions were investigated in post‐mortem samples of progressive MS brain using autoradiography and immunohistochemistry. [11C]TMSX binding to A2A receptors was increased in NAWM of secondary progressive MS (SPMS) patients when compared to healthy controls, and this correlated to more severe atrophy in MRI and white matter disintegration (reduced fractional anisotropy, FA) in DTI. The non‐invasive input function methods appeared as feasible options for brain [11C]TMSX images obviating arterial blood sampling. [11C](R)‐PK11195 uptake was increased in the NAWM of SPMS patients when compared to patients with relapsing MS and healthy controls. Higher [11C](R)‐PK11195 binding in NAWM and total perilesional area of T1 hypointense lesions was associated with more severe clinical disability, increased brain atrophy, higher lesion load and reduced FA in NAWM in the MS patients. In autoradiography, increased perilesional [11C](R)‐PK11195 uptake was associated with increased microglial activation identified using immunohistochemistry. In conclusion, brain [11C]TMSX PET imaging holds promise in the evaluation of diffuse neuroinflammation in progressive MS. Being a marker of microglial activation, [11C](R)‐ PK11195 PET imaging could possibly be used as a surrogate biomarker in the evaluation of the neuroinflammatory burden and clinical disease severity in progressive MS.

Assessment of the progressive nature of cell damage in the pilocarpine model of epilepsy

Pilocarpine-induced (320 mg/kg, ip) status epilepticus (SE) in adult (2-3 months) male Wistar rats results in extensive neuronal damage in limbic structures. Here we investigated whether the induction of a second SE (N = 6) would generate damage and cell loss similar to that seen after a first SE (N = 9). Counts of silver-stained (indicative of cell damage) cells, using the Gallyas argyrophil III method, revealed a markedly lower neuronal injury in animals submitted to re-induction of SE compared to rats exposed to a single episode of pilocarpine-induced SE. This effect could be explained as follows: 1) the first SE removes the vulnerable cells, leaving behind resistant cells that are not affected by the second SE; 2) the first SE confers increased resistance to the remaining cells, analogous to the process of ischemic tolerance. Counting of Nissl-stained cells was performed to differentiate between these alternative mechanisms. Our data indicate that different neuronal populations react differently to SE induction. For some brain areas most, if not all, of the vulnerable cells are lost after an initial insult leaving only relatively resistant cells and little space for further damage or cell loss. For some other brain areas, in contrast, our data support the hypothesis that surviving cells might be modified by the initial insult which would confer a sort of excitotoxic tolerance. As a consequence of both mechanisms, subsequent insults after an initial insult result in very little damage regardless of their intensity.