Baseline oxygen consumption decreases with cortical depth

The cerebral cortex is organized in cortical layers that differ in their cellular density, composition, and wiring. Cortical laminar architecture is also readily revealed by staining for cytochrome oxidase—the last enzyme in the respiratory electron transport chain located in the inner mitochondrial membrane. It has been hypothesized that a high-density band of cytochrome oxidase in cortical layer IV reflects higher oxygen consumption under baseline (unstimulated) conditions. Here, we tested the above hypothesis using direct measurements of the partial pressure of O2 (pO2) in cortical tissue by means of 2-photon phosphorescence lifetime microscopy (2PLM). We revisited our previously developed method for extraction of the cerebral metabolic rate of O2 (CMRO2) based on 2-photon pO2 measurements around diving arterioles and applied this method to estimate baseline CMRO2 in awake mice across cortical layers. To our surprise, our results revealed a decrease in baseline CMRO2 from layer I to layer IV. This decrease of CMRO2 with cortical depth was paralleled by an increase in tissue oxygenation. Higher baseline oxygenation and cytochrome density in layer IV may serve as an O2 reserve during surges of neuronal activity or certain metabolically active brain states rather than reflecting baseline energy needs. Our study provides to our knowledge the first quantification of microscopically resolved CMRO2 across cortical layers as a step towards better understanding of brain energy metabolism.publishedVersio

High rate of hepatitis B virus DNA positivity in anti-HBc only-positive patients [?zole anti-HBc pozitif hastalarda saptanan yüksek hepatit B virusu DNA oran?]

PubMed ID: 18822901In hepatitis B virus (HBV) infections, detection of only anti-HBc in the absence of HBsAg and anti-HBs is known as 'anti-HBc only' situation. In this study we investigated the rate of HBV-DNA positivity in anti-HBc only-positive 45 patients (29 male, 16 female; mean age: 39.2 ± 12.3 years) who were followed in the outpatient clinics of a University Hospital in Düzce (located at northern west part of Turkey). HBV markers were investigated by 3rd generation ELISA (ME-IA Axsym-Abbott), and HBV-DNA were searched by real-time PCR [extraction: Minielute (Qiagen, Germany); PCR kits: Florion HBV (Iontek, Turkey); detection: i-cycler IQ5 (BioRad, USA)] methods. As a result, 24.4% (11/45) of the patients were found HBV-DNA positive (> 103 copies/ml). There was no statistically significant difference of HBV-DNA positivity rates between males (9/29; 31%) and females (2/16; 12.5%), (p=0.15). It was concluded that there may be a serious risk of HBV transmission from anti-HBc only-positive patients since the rate of HBV-DNA positivity was found high in our study. Thus HBV-DNA screening should be performed in 'anti-HBc only' patient groups

High rate of hepatitis B virus DNA positivity in anti-HBc only-positive patients

In hepatitis B virus (HBV) infections, detection of only anti-HBc in the absence of HBsAg and anti-HBs is known as 'anti-HBc only' situation. In this study we investigated the rate of HBV-DNA positivity in anti-HBc only-positive 45 patients (29 male, 16 female; mean age: 39.2 ±12.3 years) who were followed in the outpatient clinics of a University Hospital in Düzce (located at northern west part of Turkey). HBV markers were investigated by 3rd generation ELISA (MEIA Axsym-Abbott), and HBV-DNA were searched by real-time PCR [extraction: Minielute (Qiagen, Germany); PCR kits: Florion HBV (lontek, Turkey); detection: i-cycler IQ5 (BioRad, USA)] methods. As a result, 24.4% (11/45) of the patients were found HBV-DNA positive (> 103 copies/ml). There was no statistically significant difference of HBV-DNA positivity rates between males (9/29; 31 %) and females (2/16; 12.5%), (p 0.15). It was concluded that there may be a serious risk of HBV transmission from anti-HBc only-positive patients since the rate of HBV-DNA positivity was found high in our study. Thus HBV-DNA screening should be performed in 'anti-HBc only' patient group

Effects of comorbidities associated with COVID-19 cases in Intensive Care Unit on mortality and disease progression

OBJECTIVE: The patient’s age, gender and the presence of certain concomitant diseases have been reported to play a part in the course and progression of COVID-19 in the literature. In this study, we aimed to compare the comorbidities causing mortality in critically ill Intensive Care Unit (ICU)-patients diagnosed with COVID-19. PATIENTS AND METHODS: The data as regards the COVID-19 cases followed up in the ICU were retrospectively reviewed. 408 COVID-19 patients with positive PCR test were included in the study. In addition, a subgroup analysis was performed in patients treated with invasive mechanical ventilation. While the primary aim of this study was to evaluate the difference in survival rates due to comorbidities in critical COVID-19 patients, we also aimed to assess the comorbidities in severely intubated COVID-19 patients in terms of mortality. RESULTS: A statistically significant increase in mortality was observed in patients with underlying hematologic malignancy and chronic renal failure (p=0.027, 0.047). Body mass index value in the mortal group was significantly higher in both the general study group and subgroup analysis (p=0.004, 0.001). CONCLUSIONS: Advanced age and comorbidities such as chronic renal failure and hematologic malignancy in COVID-19 patients are associated with poor survival prognosis in critically ill COVID-19 patients

Therapeutic plasma exchange in patients with neurological diseases: Multicenter retrospective analysis

Therapeutic plasma exchange (TPE), is a procedure, changing pathologic substances in the plasma of patients with replacement fluid. TPE has an increasing list of indications in recent years such as neurological, connective tissue, hematological, nephrological, endocrinological and metabolic disorders. We report our multicenter data about therapeutic plasma exchange in patients with neurological diseases. Six University Hospitals' aphaeresis units medical records about neurologic diseases were reviewed retrospectively. Hundred and fifteen patients and 771 TPE sessions from six aphaeresis units' were included to this study. Of the 115 patients, 53 (46%) were men and 62 (54%) were women. The median age was 50 (range: 5-85) years. Of these patients 58.3% were Guillain-Barre syndrome (GBS), 17.4% were acute disseminated encephalomyelitis (ADEM), 10.4% were chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 7% were multiple sclerosis, 6.1% were myasthenia gravis (MG) and 0.9% were Wilson disease (WD). The median number of TPE sessions per patient was 5 (range 1-72). Human albumin was used as a replacement fluid in 66% and fresh frozen plasma was used in 34% of cases. TPE was done through central venous catheters in 66%, and peripheral venous access in 34% of patients. Some complications were seen in patients (18.3%) during TPE sessions. These complications were, complications related to catheter placement procedure (8.7%), hypotension (3.5%), hypocalcaemia (3.5%) and allergic reactions (1.7%). The complication ratios were 2.7% in total 771 TPE procedures. TPE procedure was terminated in 6% of sessions depending on these complications. Overall responses to TPE were noted in 89.5% of patients.In conclusion; Therapeutic plasma exchange is an effective treatment option in several neurologic diseases. © 2013 Elsevier Ltd