Critical correlation susceptibility relation in random-field systems.
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Journal Article↗
Biomedical subjects
M Schwartz
Publications and source records attributed to M Schwartz.
Brain morphometry in autistic men as measured by volumetric computed tomography.
Brains of 12 physically healthy men, aged 18 to 39 years, with clear childhood diagnoses of infantile autism, and those of 16 healthy age- and sex-matched normal controls, were examined with computed transverse axial tomography. No significant group differences were seen in volumes of cerebrospinal fluid, white matter, gray matter, the third ventricle, the lateral ventricles, the caudate nuclei, lenticular nuclei, or the thalami, or in the relative symmetry of these structures. These results suggest that the cerebral defect in autism is functional or microscopic, without major gross anatomic correlate.
Adolescent↗
Mutations affecting antigenic determinants of an outer membrane protein of Escherichia coli.
The Escherichia coli LamB protein is located in the outer membrane. It is both a component of the maltose and maltodextrin transport system, and the receptor for phages lambda and K10. It is a trimer composed of three identical polypeptide chains, each containing 421 residues. Six independent mutants have been isolated, in which the LamB protein is altered in its interaction with one or more monoclonal antibodies specific for regions of the protein that are exposed at the cell surface. Some of the mutations also altered the binding site for phage lambda. All of the mutations were clustered in the same region of the lamB gene, corresponding to residues 333-394 in the polypeptide. This and previous results strongly suggest that a rather large segment of the LamB polypeptide, extending from residue 315 to 401, is exposed at the outer face of the outer membrane. This segment would bear the epitopes for the four available anti-LamB monoclonal antibodies that react with the cell surface, and part of the binding site for phage lambda.
Amino Acid Sequence↗
Choroideremia: further evidence for assignment of the locus to Xq13-Xq21.
Choroideremia is an X-linked hereditary retinal dystrophy leading to blindness in early adulthood. RFLP analyses in three Danish families were consistent with close linkage between choroideremia and the locus DXYS1, located at Xq13-Xq21. Measurable linkage was found between choroideremia and DXS17, at Xq22. Furthermore, choroideremia was diagnosed in a boy with an interstitial deletion at Xq13-Xq21, strongly suggesting the assignment of the locus for choroideremia to this region of the X chromosome. The deletion also covered DXYS1, but did not include DXS17.
Chromosome Mapping↗
Electrophysiological effect of HeNe laser on normal and injured sciatic nerve in the rat.
The effect of low energy CW HeNe laser irradiation on normal and dissected nerves in the rat was examined. The methods are described. Results are compared to the laser effect on other living tissues. HeNe irradiation was found to increase significantly the action potentials of the nerves. It was found to be a long-lasting effect, keeping an increase in the nerves action potential for more than eight months after irradiation has been stopped. A possible explanation for the way the irradiation acts on the nerve is suggested.
Action Potentials↗
Disparate responses of lymphocyte clones to cells of monozygotic twins discordant for multiple sclerosis.
Spinal fluid and peripheral blood lymphocytes from patients with multiple sclerosis (MS) and other neurologic diseases (OND) were stimulated with a pool of allogeneic MS lymphocytes. Responding cells were cloned and assayed for their proliferative responses to peripheral blood lymphocytes from monozygotic twins discordant for MS. As expected, most (greater than 90%) responding clones proliferated equally well to cells from both members of a twin set. However, some clones were noted that responded to cells from one but not the other of the twin set. These differences could not be explained on the basis of a decreased stimulatory capacity of the twin cells. We cannot definitively explain our observations but they may suggest that environmental factors, perhaps exposure to a virus, could have altered the antigenic phenotypes of cells from identical twins discordant for MS. Further evaluation of the nature of these differences may lead to an understanding of the pathogenesis of the disease.
Clone Cells↗
Nemaline myopathy in an adult with primary hypothyroidism.
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Female↗
Linkage between the loci for cystic fibrosis and paraoxonase.
In a material of 22 Danish, 26 Canadian, 10 Australian, 5 English and 5 American families with at least 2 children affected with cystic fibrosis (CF) a combined positive LOD score of 3.46 was found for the relationship cystic fibrosis-paraoxonase (PON) at recombination fraction theta = 0.07 in males and theta = 0.13 in females. Assuming a three allele model for PON the LOD score was 4.50 at the same recombination fractions. This confirms our earlier finding of an indication of CF-PON synteny.
Alleles↗
Detection and exclusion of carriers of ornithine transcarbamylase deficiency by RFLP analysis.
By examining a restriction fragment length polymorphism (RFLP) detected by a gene specific DNA probe of ornithine transcarbamylase (OTC), we have been able to follow the segregation of the defective gene in a family with OTC deficiency. We have identified three sisters of the proband as carriers, and excluded a fourth as a carrier.
DNA↗
A neurotrophic factor derived from goldfish brain: characterization and purification.
Previous studies carried out in our laboratory have demonstrated that goldfish brain contains substances that promote neurite extension from regenerating retinae in culture. Fractionation of the brain extract by molecular sieving chromatography revealed the presence of several molecular species, including two peaks that have neurotrophic activity, representing low-molecular-weight substances. One peak was eluted (P-a) with an apparent molecular weight of about 13 kDa and was designated substratum neurite extension factor (SNEF) because it retained its neurotrophic activity when adsorbed onto the substratum. This recovered Sephadex fraction (P-a) when applied in vivo intraocularly caused an earlier capacity of the corresponding retinae to sprout in vitro. Thus, at 3 and 5 days after injury the neuritic growth indices from the factor-treated retinae were of 0.9 +/- 0.2 and 2.8 +/- 0.5, respectively, as compared with indices of 0.3 +/- 0.1 and 0.9 +/- 0.2, respectively, in retinae of injured but nontreated nerves. The factor was further purified by two steps of HPLC (ion exchange followed by reversed phase). The results showed that it is an acidic glycoprotein with an apparent molecular weight of 10 kDa.
Adsorption↗
Extracellular pullulanase of Klebsiella pneumoniae is a lipoprotein.
Pullulanase is a starch-debranching enzyme produced by the gram-negative bacterium Klebsiella pneumoniae. In this organism, the enzyme is first exported to the outer membrane and is subsequently released into the growth medium. Evidence reported here indicates that pullulanase is a lipoprotein. It is apparently synthesized as a precursor with a 19-residue-long signal sequence and modified by the covalent attachment of palmitate to the cysteine residue which becomes the amino terminus after cleavage of the signal sequence. In this respect, pullulanase is similar to some penicillinases produced by gram-positive bacteria which are initially exported to the cell surface and subsequently released into the medium. However, pullulanase and the penicillinases differ in one important aspect, namely, that the extracellular pullulanase still carries the covalently attached fatty acyls, whereas extracellular penicillinases lack the modified amino-terminal cysteine together with a limited number of other residues from the amino terminus.
Amino Acid Sequence↗
Word deafness: one hundred years later.
Since its original description the diagnosis of word deafness has been greatly expanded. Confusion has arisen with regard to the usage of the related terms pure word deafness, auditory agnosia, and cortical deafness. Three new cases of word deafness are presented including one case with CT and necropsy correlation. These cases are compared with 34 previously reported cases of various cortical auditory disorders. Our review establishes that patients with word deafness who have had formal testing of linguistic and non-linguistic sound comprehension and musical abilities always demonstrated a more pervasive auditory agnosia. Despite the spectrum of auditory deficits and associated language abnormalities, patients with word deafness share common features including aetiology, pathology, clinical presentation and course. These common features justify inclusion of heterogeneous cortical auditory disorders under the rubric of word deafness. Despite some limitations the term "word deafness" should be retained for this syndrome, since inability to comprehend spoken words is the most distinctive clinical deficit. Word deafness is most frequently caused by cerebrovascular accidents of presumed cardiac embolisation, with bitemporal cortico-subcortical lesions. The sequence of cerebral injury is not predictive of resulting auditory deficits. Impairment of musical abilities parallels the severity of the auditory disorder.
Aged↗
Effects of NaSCN and omeprazole on resistance and potential of fundus of Rana pipiens.
Thiocyanate (SCN) produced a rapid inhibition of acid secretion and a concurrent rapid increase in the transmucosal potential difference (PD) and resistance. After inhibition, resistance rapidly peaked and then decreased. In contrast, omeprazole produced a slow inhibition of secretion and a slow increase in PD and resistance. The peak increase in resistance with SCN was significantly greater than the steady-state increases for both SCN and omeprazole. All increases were significant. The increases in PD and resistance are greater at high H+ rates than at low H+ rates. We postulate that the peak SCN increase in resistance is due to the increase in resistance of the secretory membrane, which is followed by a decrease in resistance of the nutrient membrane. On this basis the omeprazole increase in resistance that occurs concurrently with the slow decrease in the H+ rate is a result of a concurrent change of the resistances of the two opposing membranes.
Animals↗
Sites of resistance changes with inhibition of acid secretion in frog stomach.
The primary purpose of this study was to determine the sites of resistance changes from thiocyanate inhibition of secretion to better evaluate models of the gastric proton pump. The potential difference, resistance, and H+ secretory rate were measured with various tonicities of the secretory fluid. Thiocyanate (SCN) inhibition generally produces a resistance increase, but with nutrient Ba, the resistance is high and SCN decreases it. The latter effect is also seen with cimetidine. In the secreting fundus a hypotonic secretory solution has a small effect on resistance, but in the inhibited fundus the effect is huge, due to increase of resistance of the lumen-tubular cell pathway. With a hypotonic secretory solution, for inhibited fundus (cimetidine or omeprazole) and antrum, SCN does not decrease the resistance of the surface cells and/or the transintercellular pathways with or without Ba. The SCN resistance decrease with Ba is via the tubular cell pathway. With Ba the resistance of the nutrient membrane of the tubular cells decreases after SCN or cimetidine inhibition. The findings further support the concept that under standard conditions the resistance via the lumina and tubular cells is low and that via the surface cells and transintercellular pathways is high.
Animals↗
Linkage between the cystic fibrosis locus and markers on chromosome 7q.
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Child↗
Linkage of cystic fibrosis to the pro alpha 2(I) collagen gene, COL1A2, on chromosome 7.
A linkage has been detected between the locus for cystic fibrosis (CF) and the pro alpha 2(I) collagen gene (COL1A2) which is located in the region q21.3----q22.1 of chromosome 7. Based on the combined linkage data derived from 50 informative two-generation nuclear families collected in Canada and Denmark, the distance between COL1A2 and CF is estimated to be 19 centiMorgans. Close linkage has also been detected between COL1A2 and the DNA marker D7S15 (formerly D0CRI-917) and the serum enzyme activity marker paraoxonase (PON), both of which have previously been found linked to CF. The results of the two-point and three-point linkage analyses indicate that the most probable order of these four genetic loci is COL1A2-D7S15 - PON - CF.
Chromosomes, Human, 6-12 and X↗
Quantitative computed tomography in dementia of the Alzheimer type.
Men and women with dementia of the Alzheimer type (DAT) had more brain atrophy and ventricular dilatation, measured by quantitative CT, than did respective age- and sex-matched healthy controls (p less than 0.05). The male DAT patients with mild dementia had a larger mean third ventricle volume, whereas male patients with severe dementia had larger lateral and third ventricle volumes, more CSF, and less gray matter than did controls. Statistically significant and appropriate correlations between several dementia scales and CT measures in the DAT patients indicated that brain atrophy and ventricular dilatation were related to the severity of dementia.
Age Factors↗
Choroideremia in interstitial deletion of the X chromosome.
An earlier reported family with a deletion of the proximal long arm of the X chromosome was reinvestigated with special attention to the presence of choroideremia. Two females were identified as carriers of choroideremia while a tapeto-retinal dystrophy was ascertained in a mentally retarded boy. RFLP analysis revealed that the interstitial deletion covered the locus DXYS1 and not DXS17. Chromosome studies indicated a deletion within the Xq21 area.
Abnormalities, Multiple↗