Metal porphyrins catalyse luminol chemiluminescence at pH13 without added peroxide. The effects of 22 different surface active compounds on this reaction were studied using six metal porphyrins and one metal porphyrin conjugate. The most active catalyst was Mn-meso-tetra(4-sulphonatophenyl)porphine. Tween-20 enhanced the activity of this catalyst best at a Tween-20 to luminol ratio of 74:1. However, lauryl sulphate enhanced best at an optimum lauryl sulphate to luminol ratio of over 1000:1 and both detergents enhanced the reaction when present below their critical micelle concentrations. Negatively charged aliphatic compounds such as fatty acids enhanced the reaction but positive-charged aliphatic compounds inhibited it. Small differences in enhancer structure resulted in differing enhancement. For example, linoleic acid enhanced Mn-meso-tetraphenyl porphine more than 10-fold, yet linolenic acid inhibited this catalyst. Conjugation of a metal porphyrin to antibody did not influence its enhancement by detergents. The results indicate that the enhancement mechanism does not require formation of pure detergent micelles but that direct association between enhancer and catalyst may be important.

Hydrogen-Ion Concentration↗

PubMedDate not supplied

Congenital canine myasthenia gravis: I. Deficient junctional acetylcholine receptors.

The neuromuscular junction was studied during growth in two breeds of dog with a congenital familial form of myasthenia gravis (CMG): the Jack Russell terrier and the springer spaniel. Light microscopy revealed no difference in endplate size or nerve terminal morphology in age-matched CMG dogs and unaffected littermates. At all ages there was in individual muscle fibers of CMG dogs an approximately 75% lower postsynaptic membrane density of acetylcholine receptors (AChR). There was no evidence that this abnormality had an autoimmune basis. Measurements of miniature endplate potential amplitude in relation to fiber diameter revealed that the low density of AChR in the postsynaptic membrane of CMG dogs remained constant and did not change with the marked progression of muscle weakness during growth. Antigenic determinants of AChR were deficient in CMG muscle to the same extent as alpha-bungarotoxin (alpha BT) binding sites. Thus, a low density of AChR in the muscle's postsynaptic membrane appears to be the principal abnormality of CMG. The data suggest that the normal increase in number of acetylcholine (ACh) quanta released by nerve impulse may not fully compensate for the reduction in depolarization produced by a single quantum as the muscle fiber diameter increases. This could cause progression of weakness during growth. In addition to being a useful animal model of a rare form of CMG that resembles one form of human CMG, canine CMG offers a unique model for investigating events of synaptogenesis at the neuromuscular junction.

Animals↗

PubMedDate not supplied

Congenital canine myasthenia gravis: II. Acetylcholine receptor metabolism.

Acetylcholine receptor (AChR) metabolism was studied in muscle from juvenile and adult dogs with congenital myasthenia gravis (CMG) and their unaffected littermates. Although the amount of AChR in the junctional region of innervated CMG muscle fibers was 25% of normal, or less, denervation of CMG fibers resulted in the appearance of AChR in extrajunctional membranes at as high a concentration as in denervated normal fibers. The rate of degradation of junctional AChR in CMG fibers explanted to organ culture did not differ significantly from normal. In monolayer cultures derived from enzyme-dissociated CMG muscle, myotubes of normal morphology developed, and the synthesis and degradation of AChR did not differ from normal. Addition of sera from dogs with the acquired autoimmune form of MG accelerated the degradation of AChR on cultured myotubes, but CMG dog sera were without effect. These data suggest that the low junctional membrane density of AChR in CMG does not reflect a primary inability of muscle to synthesize AChR, nor an accelerated degradation of AChR in the postsynaptic membrane, but rather a low insertion rate of AChR in the postsynaptic membrane.

Animals↗

PubMedDate not supplied

Occurrence and transcription of genes for nad1, nad3, nad4L, and nad6, coding for NADH dehydrogenase subunits 1, 3, 4L, and 6, in liverwort mitochondria.

The genes encoding subunits 1, 3, 4L, and 6 of NADH dehydrogenase (nad1, nad3, nad4L, nad6) in the mitochondrial genome of a liverwort, Marchantia polymorpha, were characterized by comparing homologies of the amino-acid sequences of the subunits with those of other organisms. The nad3 and nad4L genes are split by single and double group II introns, respectively. The 5'-half portion of the nad6 gene was repeated at an identity of 89% to form a reading frame consisting of 100 amino-acid residues. The Northern hybridization analysis showed that all four genes are transcribed in the liverwort mitochondria.

Amino Acid Sequence↗

PubMedDate not supplied

Serum acetylcholine receptor antibody measurement in myasthenia gravis. Some trials to background radioactivity in radioimmunoassay.

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Animals↗

PubMedDate not supplied

Age changes of motor innervation and acetylcholine receptor distribution on human skeletal muscle fibres.

Age changes of motor innervation and acetylcholine receptor (AChR) distribution on human intercostal muscle fibres (age 32-76 years) were investigated by using combined silver and acetylcholinesterase (AChE) staining method and [125I]alpha-bungarotoxin autoradiography. In the older subjects, (1) the number of preterminal axons entering an endplate and the length of endplate increased, and (2) the endplate was composed of a greater number of smaller conglomerates of AChRs, as compared with the younger subjects. In addition, (3) perijunctional AChRs were observed in the older subjects, but not in the younger ones. Linear relationships were observed between each of these parameters and age. These results suggest that there are gradual changes in the pre- and postsynaptic components of human skeletal muscle endplate over adult life.

Adult↗

PubMedDate not supplied

A case of Isaacs syndrome with high CSF protein and a large cisterna magna.

An 11-year-old boy exhibited continuous muscle fiber activity. He had suffered from stiffness of his hands, difficulty in relaxing his hands after gripping, and making skilled movements with his fingers. His clinical symptoms improved after treatment with carbamazepine. Electromyography (EMG) showed that he had continuous electrical discharges both at rest and during sleep. These discharges completely disappeared after the peripheral nerve was blocked with Lidocaine. An evoked electromyogram showed suppression of abnormal discharges after the F response. These electrophysiological findings indicated that the disorder originated in the spinal anterior horn cells. CT scanning showed a large cisterna magna in the posterior cranial fossa. Protein in the cerebrospinal fluid was elevated.

Carbamazepine↗

PubMedDate not supplied

Spinal somatosensory evoked potentials in mice and their developmental changes.

Spinal somatosensory evoked potentials (SEP) were recorded in 58 normal mice (C3H strain) divided into 4 groups according to age (3-, 6-, 9- and 12 weeks). Monopolar recordings of spinal SEP were made by subdermal needle electrodes from 3 vertebral levels, "low-lumbar", "high-lumbar" and "mid-thoracic", by stimulating the tibial nerve bilaterally at the ankle. Three negative peaks, NI, NII and NIII, presumably due to conduction through muscle afferents, cutaneous afferents (in the dorsal root or dorsal white column) and spinocerebellar tract, respectively, were recorded at the high-lumbar level in the 12-week-old mouse. Besides the NI and NII peaks, a small ventral root potential was also occasionally recorded at the low-lumbar level. At the mid-thoracic level, only NI and NIII were recordable. At both the high-lumbar and mid-thoracic levels, the negative peaks were superimposed over long duration "summation potentials" of opposite polarities. Well-defined standing potentials were also recorded at these two levels. The standing potentials could be the "entry potential" due to the entry of S1 root into the spinal cord at the T13 vertebral level. The summation potential presumably is due to a fixed generator located between the T7 and T12 vertebral levels resulting from intense synaptic activity at this level. In 3- and 6-week-old mice, the entry point potential was recorded in the low-lumbar SEP also, possibly due to less axial growth of the vertebral column at this stage of development.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMedDate not supplied

Synthesis and preliminary evaluation of [11C]KF17837, a selective adenosine A2A antagonist.

An 11C-labeled selective adenosine A2A antagonist, (E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-[11C]-methylxanthine ([11C]KF17837), was prepared by reaction of (E)-8-(3,4-dimethoxystyryl)-1,3-dipropylxanthine and [11C]methyl iodide with decay-corrected radiochemical yield of 19-50%, radiochemical purity of > 99%, sp. act. of 17-100 GBq/mumol and preparation time of 20-25 min. In mice, the myocardium showed the highest (13.4% ID/g) at 5 min after i.v. injection, which decreased gradually with time. The specific myocardial uptake was visualized by gamma-camera. In the brain region the radioactivity level was higher in the A2A receptors-rich striatum than in the cortex and cerebellum. The specific striatal uptake in rats was clearly demonstrated by PET. These results have shown that [11C]KF17837 is a potential PET radioligand for mapping the adenosine A2A receptors in the heart and brain.

Animals↗

PubMedDate not supplied

Struma ovarii: MR findings.

PURPOSE: The purpose of this study was to determine the MR appearance of struma ovarii correlating with the pathological features. METHOD: MR findings of two patients with struma ovarii were retrospectively reviewed and compared with the pathological findings. RESULTS: Both tumors were complex masses composed of multiple cysts and solid components. The size and signal intensity of multiple cysts varied within the tumor. Hyperintense cystic areas on T1-weighted images were thought to correspond pathologically to hemorrhagic cysts and follicles containing viscous proteinaceous colloid. Solid components had as high a signal intensity as did uterine endometrium on T2-weighted images and as intermediate a signal intensity as did uterine muscle layer on T1-weighted images. After intravenous administration of gadolinium-DTPA, the solid components showed marked contrast enhancement. There was also ascitic fluid associated with adhesion and peritoneal thickening. CONCLUSION: The characteristic MR appearance of struma ovarii is thought to be a mixed mass composed of T2-hyperintense solid components with intense contrast enhancement and multiple T1-hyperintense cystic areas suggestive of hemorrhagic degeneration and viscous proteinaceous colloid.

Adult↗

PubMedDate not supplied

Prediction for prognosis from radiologic measurements of patients treated with the Pavlik harness for congenital dislocation of the hip.

Radiologic measurement was made in 96 hips of 96 female patients with congenital dislocation of the hip (CDH) treated only with the Pavlik harness before reaching age 6 months until time of maturity. Radiographs were retrospectively examined to determine whether prognosis of the hip joints was predictable up to approximately 3 years of age. Highly accurate prediction was possible using multivariate analysis. The patient group assessed as "satisfactory" with discriminant analysis had an incidence of Severin's classification of group III or lower of < 1% of significance level. This analysis appears to be a useful screening method for judging CDH after treatment.

Child, Preschool↗