The availability of new therapeutic interventions, including neuroprotective agents and endovascular thrombolysis, has given new hope to patients suffering an acute stroke. Early intervention remains a key factor in the effectiveness of these new and traditional treatments. More importantly, the capability to assess the viability and reversibility of the ischemic tissue became essential for better delineation and differentiation of infarcted versus ischemic tissue and patient management. Abnormal MR imaging (MRI) findings during acute stroke usually reflect the underlying pathophysiologic changes, which can be classified into three sequential stages: (a) hypoperfusion, (b) cellular dysfunction and (c) breakdown of the blood-brain barrier. The first stage is a kinetic phenomenon (not biologic) and, therefore, can be detected immediately. Contrast agents accentuate the abnormal flow kinetics and facilitate the early diagnosis of ischemia using either conventional MRI or newly developed echo-planar perfusion imaging (EPPI). The demonstration of abnormal arterial or parenchymal enhancement on conventional MRI during acute stroke provides the earliest sign of vascular occlusion/stenosis. EPPI, in contrast, provides information related to microcirculation (< 100 microns) and tissue reserve (cerebral blood volume) that cannot be obtained by conventional angiography and is directly related to the target end-organ. Further information obtained from both contrast MRI and EPPI may have a predictive value in the clinical outcome of acute stroke patients.

Acute Disease↗

PubMedDate not supplied

One- and two-dimensional 15N exchange CP/MAS NMR studies of the structure and electronic properties of the intermolecular N-H...N hydrogen bond in imidazole crystal.

The hydrogen bond of the type N-H...N in imidazole crystal has been studied by one and two-dimensional 15N exchange CP/MAS NMR measurements as well as the powder NMR spectrum. The chemical shift anisotropies for -N= and -N< were determined from the powder 1D spectrum. In 2D exchange CP/MAS NMR spectrum, the cross peaks between the 15N main resonance peaks for -N= and -N< were observed, implying that magnetization exchange between -N= and -N< takes place. The 1D exchange CP/MAS NMR measurements determined the exchange rate of magnetization at 289 K to be 1.3 and 1.5 s(-1) for -N= and -N<, respectively. The proton-driven spin-diffusion model interprets the experimental values, and the exchange rate depends strongly on the RF power of the proton decoupling field, suggesting that the magnetization transfer between -N= and -N< takes place by the 1H-driven spin-diffusion mechanism.

Anisotropy↗

PubMedDate not supplied

Response of Nitella internodal cell to chemical stimulation. A model for olfactory receptor system.

Electrical response to excitable internodal cell of Nitella was studied by applying various kinds of odorants to the cell. Changes in membrane potential and resistance during responses induced by odorants were measured intracellularly under a variety of ionic environments in the media. Results were: 1) Some odorants (coumarin, isoamylacetate, methylacetate, 1-octanol, 1-butanol, 1-propanol) produced an all-or-nothing type action potential when the concentration of odorant exceeded a certain threshold. The action potential was followed by a gradual depolarization of the potential whose amplitude depended on the odorant concentration, C. Other odorants (heptanoic acid, beta-ionon) induced gradual depolarization of the membrane potential without evoking an action potential. 2) Membrane resistance Rm changed in various ways during depolarization: some odorants led to a temporal or gradual decrease in Rm, and others caused an increase in Rm when the membrane potential was depolarized by the application of odorants. 3) Magnitude of response to odorants OR was found to be represented by the following equation: OR =(alpha + beta square root I) log (C/Cth) for C greater than or equal to Cth where alpha and beta are constants for a given odorant, I the ionic strength in the medium, and Cth the threshold concentration of the odorant. 4) Plots of olfactory threshold of human and of internodal cell of Nitella gave a straight line having slope unity. 5) Local application of odorants on the internodal cell induced impulses which transmitted from the part treated by odorants to the other portion. Physico-chemical and physiological implications of the results obtained were discussed.

1-Propanol↗

PubMedDate not supplied

Segmental dilatation of the ileum.

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Child, Preschool↗

PubMedDate not supplied

Serial CT scans in subacute sclerosing panencephalitis.

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Brain↗

PubMedDate not supplied

Nonsurgical treatment of posterior fossa epidural hematoma.

The recommended treatment for posterior fossa epidural hematoma has been prompt surgical evacuation. We report 2 patients who were treated conservatively. Both patients were younger than 10 years of age and developed subacute symptoms and signs. Serial computed tomography demonstrated complete resolution of the hematomas and no development of hydrocephalus during nonsurgical treatment. They recovered well without any neurologic deficits. In order to evaluate an indicative factor for nonsurgical treatment in young children with posterior fossa epidural hematoma, we review both of our patients and 36 well-documented patients from the literature, all of whom were younger than 10 years of age. The results demonstrate that the development of hydrocephalus is a critical factor in clinical progression. Nonsurgical management can be applied in these circumstances until spontaneous resolution of the hematoma unless early signs of medullary compression appear acutely after head trauma or serial computed tomography demonstrates the development of hydrocephalus followed by medullary compression.

Child↗

PubMedDate not supplied

Peripheral lymphocyte reduction in severe acute pancreatitis is caused by apoptotic cell death.

To investigate impairment of cellular immunity in severe acute pancreatitis, alterations of peripheral lymphocytes in acute pancreatitis were examined. In 48 patients with severe acute pancreatitis, the mean peripheral lymphocyte count on admission was 959 + 105/mm3, and it was significantly decreased in the patients with subsequent infection (623 +/- 90/mm3 ) in comparison to those without infection (1084 +/- 135/mm(3)). According to an analysis of lymphocyte subsets, although both B and T lymphocytes were decreased in peripheral circulation in the patients with infection, it was primarily CD8-positive lymphocytes that decreased in these subsets. Cell cycle analysis of lymphocytes collected from these patients indicated that apoptotic changes occurred after 24 hours' incubation in lymphocytes from patients with severe pancreatitis but not in lymphocytes from healthy control subjects. In a rat model of experimental necrotizing pancreatitis, total peripheral lymphocytes and T lymphocytes were significantly decreased 5 hours after induction of pancreatitis. In severe pancreatitis, peripheral lymphocytes are eliminated from systemic circulation possibly as a result of apoptosis. It has been suggested that impairment of cellular immunity due to peripheral lymphocyte apoptosis is linked to the development of subsequent infectious complications in acute pancreatitis.

Acute Disease↗

PubMedDate not supplied

Ca2+ release from endoplasmic reticulum is mediated by a guanine nucleotide regulatory mechanism.

Ca2+ accumulation and release from intracellular organelles is important for Ca2+-signalling events within cells. In a variety of cell types, the active Ca2+-pumping properties of endoplasmic reticulum (ER) have been directly studied using chemically permeabilized cells. The same preparations have been extensively used to study Ca2+ release from ER, in particular, release mediated by the intracellular messenger inositol 1,4,5-trisphosphate (InsP3). So far, these studies and others using microsomal membrane fractions have revealed few mechanistic details of Ca2+ release from ER, although a recent report indicated that InsP3-mediated Ca2+ release from liver microsomes may be dependent on GTP. In contrast to the latter report, we describe here the direct activation of a specific and sensitive guanine nucleotide regulatory mechanism mediating a substantial release of Ca2+ from the ER of cells of the neuronal cell line N1E-115. These data indicate the operation of a major new Ca2+ gating mechanism in ER which is specifically activated by GTP, deactivated by GDP, and which appears to involve a GTP hydrolytic cycle.

Animals↗

PubMedDate not supplied

Clinical significance of augmented fluorine-18 deoxyglucose uptake in remote normoperfused myocardium in patients with acute coronary syndrome under fasting conditions.

OBJECTIVES: We evaluated the relation between increased fluorine-18 deoxyglucose (FDG) uptake in remote normoperfused areas and acute ischemic events in patients with ischemic heart disease. METHODS: We performed nitrogen 13 ammonia (NH3) and FDG positron emission tomography (PET) on 67 patients (46 men, mean age 65 years) with ischemic heart disease (46 with myocardial infarction, 21 with angina pectoris). PET images were analyzed in only remote normoperfused areas (excluding infarct-related areas, areas containing coronary arteries with significant stenosis and/or showing vasoconstriction, and areas showing abnormal left ventricular wall motion). RESULTS: Seventeen patients (group 1) exhibited increased FDG uptake, as defined by our institution's guidelines, in remote normoperfused areas and 50 (group 2) did not. The plasma glucose levels (90.8+/-10.9 mg/dL vs. 94.9+/-11.8 mg/dL) and the serum insulin levels (7.3+/-2.9 IU/L vs. 8.6+/-3.4 IU/L) did not vary between the 2 groups. The serum free fatty acid levels were lower in group 1 than in group 2 (0.46+/-0.21 mEq/L vs. 0.62+/-0.29 mEq/L; P = .02). Patients were subsequently reclassified into either the acute coronary syndrome (ACS) group (n = 16), which consisted of patients exhibiting subacute myocardial infarction and unstable angina, or the non-ACS group (n = 51). A total of 11 (69%) of 16 ACS group patients but only 6 (12%) of 51 non-ACS group patients were included in group 1 (P<.0001). The serum free fatty acid levels were not different between ACS group and non-ACS group (0.52+/-0.21 mEq/L vs. 0.60+/-0.29 mEq/L; P = .17). CONCLUSIONS: Our data suggest that increased FDG uptake in remote normoperfused areas is closely related to the acute myocardial ischemia, suggesting that myocardial ischemic events may produce acceleration in glucose utilization even in remote nonischemic myocardium.

Adult↗

PubMedDate not supplied

Point mutation of alanine (31) to valine prohibits the folding of reduced lysozyme by sulfhydryl-disulfide interchange.

In the preceding paper in this issue, we described the overproduction of one mutant chicken lysozyme in Escherichia coli. Since this lysozyme contained two amino acid substitutions (Ala31----Val and Asn106----Ser) in addition to an extra methionine residue at the NH2-terminus, the substituted amino acid residues were converted back to the original ones by means of oligonucleotide-directed site-specific mutagenesis and in vitro recombination. Thus, four kinds of chicken lysozyme [Met-1Val31Ser106-, Met-1Ser106-, Met-1Val31- and Met-1 (wild type)] were expressed in E. coli. From the results of folding experiments of the reduced lysozymes by sulfhydryl-disulfide interchange at pH 8.0 and 38 degrees C, followed by the specific activity measurements of the folded enzymes, the following conclusions can be drawn: (i) an extra methionine residue at the NH2-terminus reduces the folding rate but does not affect the lysozyme activity of the folded enzyme; (ii) the substitution of Asn106 by Ser decreases the activity to 58% of that of intact native lysozyme without changing the folding rate; and (iii) the substitution of Ala31 Val prohibits the correct folding of lysozyme. Since the wild type enzyme (Met-1-lysozyme) was activated in vitro without loss of specific activity, the systems described in this study (mutagenesis, overproduction, purification and folding of inactive mutant lysozymes) may be useful in the study of folding pathways, expression of biological activity and stability of lysozyme.

Alanine↗

PubMedDate not supplied

Therapeutic plasmapheresis for liver failure after hepatectomy.

Therapeutic plasmapheresis (PP) for liver failure following the resection of primary liver cancer was evaluated retrospectively. PP was repeated two to three times per week using plasma exchange (PE) with fresh frozen plasma as a substitution fluid in all eight cases and direct hemoperfusion (DHP) in two cases. PE effectively decreased serum bilirubin and/or improved hepatic encephalopathy in six of eight patients and prolonged survival time (p less than 0.05, chi-square test). DHP was not effective. Liver failure following the resection of damaged liver differs from acute liver failure in both the condition itself and the reaction to PP. Fractionation of serum bilirubin using high performance liquid chromatography showed differences in the ratio of delta bilirubin in one survivor versus two who died and was effective in selecting a patient who would respond to PE. In conclusion, PE is effective in prolonging survival time after liver failure in hepatectomized patients compared to conventional therapy.

Bilirubin↗

PubMedDate not supplied

Pericallosal lipomas: MR features.

We report on six cases of pericallosal lipomas. The T1-weighted sagittal images best demonstrated the relationship between the lipoma and the corpus callosum. In four cases the lipomas surrounded the splenium of the corpus callosum and in two cases the tumors were situated posteriorly and caudally to the splenium. In no case did we encounter an exclusively dorsal pericallosal localization.

Adolescent↗