Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The steric course of the methyl group transfer catalyzed by catechol O-methyltransferase was studied using S-adenosylmethionine (AdoMet) carrying a methyl group made chiral by labeling with 1H, 2H, and 3H in an asymmetrical arrangement. Incubation of the two diastereomers of this substrate with catechol O-methyl-transferase purified from rat liver and epinephrine or protocatechuic acid as acceptor gave the corresponding methylated catechols. These were degraded to convert the methoxy group in a series of stereochemically unambiguous reactions into the methyl group of acetate, which was then analyzed for its configuration. The results indicate that the transfer of the methyl group from AdoMet to either acceptor occurs in an inversion mode. The catechol O-methyltransferase reaction thus involves a direct transfer of the methyl group from the sulfur of AdoMet to the oxygen of the catechol in an SN2 process, without a methylated enzyme intermediate.
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PMID:Stereochemical course of the transmethylation catalyzed by catechol O-methyltransferase. 699 10

To examine whether diffusive interaction in an asymmetrical bronchial tree contributes to cardiogenic mixing, we simulated the changes in nitrogen concentration (FN2) in an asymmetrical two-trumpet model of the lung based on canine anatomy during an inspiration of 100% oxygen and a subsequent breathhold. Results were obtained by solving a second-order differential gas-transport equation for simultaneous convection and diffusion with the assumption that velocity profiles were blunt. Cardiogenic flow pulses were simulated by periodic flow oscillations superimposed on constant respiratory flows. Both during inspiration and breath-holding the simulated pattern of FN2 within conducting airways was qualitatively similar to that observed in open-chested dogs. Despite the assumption of blunt velocity profiles, the apparent enhancement of gas mixing by oscillatory flows was comparable to that attributed to cardiogenic mixing in experimental studies. The results suggest that cardiogenic flow pulses in an asymmetrical bronchial tree may enhance gas mixing within the conducting airways by causing phasic displacements of diffusion fronts toward branchpoints subtending lung units of unequal volume. Diffusion of gas from the smaller units accelerates the decrease in inspired gas concentration within conducting airways.
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PMID:Influence of bronchial asymmetry on cardiogenic gas mixing in the lung. 714 55

An elderly patient with demonstrated asymmetrical intraventricular septal hypertrophy and ventriculo-aortic pressure gradient was anaesthetized with nitrous oxide with oxygen, narcotic, and muscle relaxant for abdominal surgery. In addition to the cardiovascular variables customarily monitored, a systolic time interval (STI) measured from the Q wave of the ECG to the foot of the radial pulse (the QF interval) was calculated in milliseconds beat-to-beat by a computer. With anaesthesia, and particularly following the beginning of operation, the QF interval lengthened as an indication of either decreased cardiac inotropy or increased pressure gradient across the aortic outflow tract. When halothane 0.25 per cent was added to the anaesthetic mixture, the QF interval shortened by about 20 milliseconds without an observed change in direct arterial pressure. Since halothane is a cardiac depressant and normally lengthens the STI, it apparently relaxed the muscular stenosis of the ventricular outflow tract and reduced the pressure gradient and, subsequently, the QF interval. By measuring cardiovascular function with this STI, the beneficial action of cardiac depression from low-dose halothane was observed, which would have escaped detection by common monitoring indices.
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PMID:The use of halothane in a patient with asymmetrical septal hypertrophy: a case report. 719 62

Oxygen tension differences across the mouse ear have been measured polarographically under conditions of no blood flow. For some experiments the ear was split into two by cleavage along the central cartilage plate, and the diffusion of oxygen measured in both directions across these asymmetrical preparations. Measurements were also made on ears from which the stratum corneum had been removed by stripping with Sellotape. It was possible to relate these results to a simple multi-layer diffusion model. The main barrier to diffusion of oxygen resides in the stratum corneum, whose permeability is estimated to be 1 . 2 X 10(-8) ml O2 atm-1 cm-1 S-1. The permeability of the rest of the ear is 4 . 7 X 10(-7) ml O2 atm-1 cm-1 S-1. The inhibition of tissue respiration by the local injection of solutions of sodium amytal, potassium cyanide and other substances reduced the oxygen gradients by factors of between 3 and 7. Cooling the ear from room temperature to 0 degree C reduced the gradients by a factor of about 4.
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PMID:Diffusion of oxygen through the mouse ear. 725 78

The present paper demonstrates region-dependent variations in the oxygenation and hemodynamics of the brain hemispheres due to three different types of mental stimulation. The variations were observed with a four-channel optical imaging system using tissue-transparent near-infrared light and described changes from baseline of both the hemoglobin oxygenation state and blood volume during three kinds of psychological or mental tasks. During the mirror drawing task, a lateralized hemisphere response (the dominant hemisphere response pattern) was observed in 57% of 14 right handed volunteers in the frontal region (Brodmann's area 10), while in the temporal region (area 38), 80% showed the bilateral response pattern. A large majority of the subjects showed the bilateral response pattern in the frontal and temporal regions while calculating. A smaller majority showed this while looking at anatomical charts, though 30% did not show any response at all in the temporal region. This showed that there were region-dependent asymmetrical or symmetrical variations of the oxygen delivery-oxygen utilization relationship due to different types of mental stimuli.
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PMID:Region-dependent asymmetrical or symmetrical variations in the oxygenation and hemodynamics of the brain due to different mental stimuli. 758 Apr 3

Our objective was to examine the changes in regional ventilation during histamine-induced bronchoconstriction in stable asthma. We measured regional ventilation by a new method which measures regional distribution of inhaled 127Xe during tidal breathing by a gated method and, by simultaneously measuring 99mTc counts from labelled macroaggregates, allowed for changes in lung shape during the breathing cycle. We studied 10 asthmatic patients [forced expiratory volume in 1 s (FEV1 2.04-4.37 litres)] and measured, in addition to the regional ventilation, oxygen saturation (SaO2), minute ventilation (VE) and tidal volume (Vt) before and after inhaling enough histamine to lower FEV1 by > 20% and/or SaO2 by > 4%. Histamine inhalation reduced FEV1 by 0.44-1.15 liters and SaO2 by 0-4%. It increased VE and functional residual capacity (FRC) in 8 of the 10 patients. The FEV1 fall did not correlate with the SaO2 fall, VE or FRC changes. Histamine inhalation increased apical ventilation in most patients, but the changes in regional ventilation in the left and right lungs were asymmetrical in 17 out of the 30 lung regions studied (upper, middle and lower paired regions in 10 patients). These results demonstrate that histamine bronchial challenge causes uneven regional ventilation. Any resultant change in ventilation-perfusion balance may be the underlying mechanism of oxygen desaturation seen in this procedure and in spontaneous attacks of asthma.
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PMID:Changes in regional ventilation during histamine bronchial challenge in stable asthma. 800 90

We reported here 19-year-old man suffering from circadian sleep-wake (S-W) rhythm disturbance after total tumor resection and whole brain irradiation. This 19-year-old man was diagnosed as having astrocytoma in the right temporal lobe by CT scan and angiography at the age of 6 months. After total tumor resection and whole brain irradiation (60Co 60 Gy), he showed profound psychomotor retardation, endocrinologic dysfunction including hypothyroidism and growth hormone deficiency, and sleep-wake rhythm disturbance. At the age of 19, brain MRI revealed asymmetrical low intensity in the hypothalamic region. On endocrinological examination panhypopituitarism due to primary hypothalamic lesion was evident. His S-W rhythm was disturbed showing a dispersed type sleep, i.e., sleep periods were dispersedly distributed throughout the 24 hours. So he showed a lethargic tendency in the daytime. All-day polysomnography revealed abnormal sleep structure such as the absence of sleep spindle and hump, peripheral apnea, snoring and low oxygen saturation. After L-thyroxine supplementation his daily activity improved gradually. The decrease in short time sleep and tendency of a free-running rhythm were observed and oxygen saturation improved remarkably. Peripheral apnea and snoring disappeared. The wakening effect of L-thyroxine administration may be due to improvement of hypothyroidism symptom such as myxoedematous pharynx. In addition, it seems related to the alteration of the central S-W rhythm regulation, because free-running rhythm appeared after L-thyroxine administration. Vitamin B12 (VB12), which has been reported to be effective for sleep-wake rhythm disorders, was not effective for our patient's free-running rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Circadian rhythm disturbance after radiotherapy for brain tumor in infantile period--clinical effect of L-thyroxine and vitamin B12]. 821 1

The neuropathy associated with diabetes mellitus is arguably the most common peripheral neuropathy in the developed world. It can be classified into symmetrical and asymmetrical forms. The symmetrical form is predominantly sensory and autonomic, whereas the asymmetrical form can be sensory, or motor, or both, and can affect individual cranial or peripheral nerves. Pathologic and electrophysiologic studies indicate that the symmetrical polyneuropathy is characterized by a distally accentuated loss of myelinated and unmyelinated axons. The multifocal nature of the axonal degeneration and its association with vascular disease in the same pathologic specimens strongly suggest an ischemic cause involving the endoneurial microvascular circulation. The underlying biochemical abnormality appears to be the production of advanced glycosylated end products (AGEPs), in the presence of chronic hyperglycemia, which accumulate on endothelial proteins, causing basement membrane thickening and endothelial cell change. This produces multifocal vascular disease that, in turn, reduces nerve blood flow, causing endoneurial hypoxia and generating oxygen free radicals. Multifocal ischemic neuronal damage results. Currently, there is no accepted treatment, although long-term control of hyperglycemia is beneficial. Symptomatic relief of the burning pain is the most vexing therapeutic problem; tricyclic antidepressants and anticonvulsants have been used alone and together with varying success.
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PMID:Diabetic neuropathy. 822 54

We report 2 cases of corticobasal degeneration (CBD) with reference to the clinical and pathological features and neuroimaging including MRI, positron emission tomography (PET) and single photon emission tomography (SPECT). Case 1 was a 66-year-old right-handed woman. Her spontaneity had been gradually impaired, and she showed a progressive course of naming difficulty, memory disturbance, and right unilateral spatial neglect in addition to the right hemi-parkinsonism and bilateral pyramidal tract signs. Cortical and subcortical atrophy was predominant in the left hemisphere on MRI. As compared with the right side, both cerebral blood flow (CBF) and oxygen metabolism (CMRO2) were decreased in the left hemisphere on the PET which was performed 4 years after onset. She showed further clinical deterioration, and exhibited a bilateral parkinsonism 6 years after the onset. The follow-up SPECT revealed diffusely bilateral hypoperfusion except for the basal ganglia and occipital lobes 6 years after the onset. Case 2 was a 56-year-old right-handed woman. She exhibited a progressive course of bilateral parkinsonism, hallucinations and vertical eye movements disturbance. She died of infection 42 months after the onset of the initial symptoms. Bilateral frontal atrophy was seen on X-ray CT and MRI. PET revealed a diffuse moderate decrease in CBF and CMRO2 particularly in the frontal cortex, central semiovale, paraventricular white matter and cingulate gyrus bilaterally. Pathological examination disclosed a mild frontal atrophy, and there was diffuse neuronal loss, gliosis, and achromasia in the cerebral cortices. There was moderate neuronal cell loss and gliosis in the thalamus, whereas the globus pallidus, striate and substantia nigra were severely affected. Neuronal inclusions termed corticobasal inclusions were present in the substantia nigra, nuclei raphes, and Meynert's nuclei, and none of these regions contained Pick's cell. PET and SPECT studies revealed an asymmetrical decrease in CBF and CMRO2 in the initial stage and diffuse bilateral decrease in the advanced stage in Case 1, whereas Case 2 showed a bilateral decrease in the late stage. This may indicate that the patterns of hypoperfusion and/or hypometabolism differs according to the clinical stages of CBD.
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PMID:[Corticobasal degeneration: a combined clinical, PET and pathological study]. 875 83

The proton affinity of individual surface groups has been calculated with a redefined version of the multi site complexation (MUSIC) model. In the new approach the proton affinity of an oxygen originates from the undersaturation of the oxygen valence. The factors valence and coordination number, which are the basis of Pauling's definition of bond valence, in combination with the number of coordinating (Me and H) ions, are dominant in determining the proton affinity. The neutralization of an oxygen by Me ion(s) is calculated on the basis of the actual bond valence, which accounts for structural details, resulting from an asymmetrical distribution of charge in the coordination environment. An important role in the new version of the MUSIC model is given to the H bonds. The model shows that the proton affinity is determined not only by the number of donating H bonds but also by the number of accepting H bonds. The proton affinity of surface groups and of solution complexes can be understood in one theoretical framework, on the basis of a different number of donating and accepting H bonds. The MUSIC model predicts the variation in proton affinity constants for surface groups in particular those with the same number of coordinating Me ions but with a different structural position. The model is able to predict on the basis of the proton affinity of the individual groups the correct PZC of Me hydroxides, oxohydroxides, and oxides, and explains previous exceptions. The model can also be applied in general to other minerals.
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PMID:Intrinsic Proton Affinity of Reactive Surface Groups of Metal (Hydr)oxides: The Bond Valence Principle 897 74


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