Biomedical subjects
Publications and source records attributed to L Herman.
Two patients with aneurysmal bone cysts of the pelvis were imaged using a 1.5-T magnetic resonance imaging device. Findings included multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. These findings allow a specific diagnosis of aneurysmal bone cyst to be made.
An electron microscope study is reported of structural changes during ATP-induced contraction of glycerinated rabbit psoas. In the absence of ATP, A-band length is constant at sarcomere lengths above 1.9 micron, with average length of 1.54 mu. In ATP-treated fibers, A-band length is also constant at sarcomere lengths above 2.0 microns, but the apparent length of A-band decreases to approximately 1.3 micron, as sarcomere length decreases from 1.9 micron to 1.5 mu. The occurrence of short A-bands cannot be attributed to crumpling of thick filaments against Z-lines, since I-bands remain patent; nor to the presence of heterogeneous filaments, since resting muscle does not show comparable heterogeneity, nor to compressive artifacts, which are minor when knife edge is oriented parallel with fiber axis during microtomy . The decrease of A-band length appears related, at least in part, to disarray of terminal cross-bridges as the thick filaments encroach upon the N-line, a structure which becomes evident within the I-band during contraction of glycerinated fibers. In preliminary studies, optical transforms of A-bands from individual sarcomeres reveal a characteristic myosin layer-line pattern as low as 1.5 micron sarcomere length. A cross-bridge repeat of 143 A is obtained for sarcomeres above 1.6 micron length; however, an appreciable proportion of sarcomeres in the range from 1.5 micron to 1.9 mu length generate meridional reflections less than 143 A, and as low as 130 A.
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Stereological methods were applied to obtain morphometric data related to pancreatic islets of Langerhans in the normal rabbit. By light microscopy, it was found that 1 mm3 of pancreatic parenchyma contained 47.7 islets, constituting 2.2% of its volume. Approximately 69% of the islets had diameters less than 80 micrometer; 31% were greater than 80 micrometer. The former group of islets, however, composed only 13% of the volume of the endocrine pancreas and the latter group, 87%. Using electron microscopy, a unit volume of islet tissue was observed to consist of 86% beta cells, 7.7% alpha cells, and 2.2% delta cells. The average beta-cell volume was 1260 micrometer 3 and its cytoplasm consisted of 52.6% matrix, 12.7% rough endoplasmic reticulum, 10.2% secretory granules, 7.8% mitochondria, and 3.3% Golgi apparatus. A typical beta cell contained 662 mitochondria, intermediate (10-nm) filaments whose length totalled 50 mm, and 9,200 secretory granules with a ratio of four mature granules to each immature or "pale" granule. Within alpha and beta cells, three parameters were used for the quantitation of organelles or their component parts: 1) volume; 2) surface; and 3) numerical densities. In the beta cell, the surface densities of rough endoplasmic reticulum and Golgi membranes exceeded, by two- or threefold, their counterparts in alpha cells. Similarly, the number of beta-cell mitochondria exceeded by 30% that of alpha cells; but beta-cell mitochondrial volume was twice that of the alpha cell, as were surface densities of both inner and outer mitochondrial membranes. Volume and surface densities of secretory granules within beta cells were half the values obtained for alpha cells. An alpha cell contained three times the number of granules present in a beta cell.
The pyroantimonate technique was employed to identify the binding sites for calcium in unfertilized Arbacia punctulata and Strongylocentrotus purpuratus eggs. Since antimony is non-specific and binds with a variety of cations, the indentification of calcium was established by specific chelation with ethyleneglycol tetra-acetic acid (EGTA) and X-ray microprobe analysis. Antimony deposits were observed on the egg's membranes, i.e. plasma, cortical (secretory) granule, pigment granule, smooth-surfaced vesicle, and yolk platelet. Deposits were also observed in the mitochondria, rod-containing vesicles, and the vitelline layer. Two types of yolk platelets were observed: a more numerous electron-opaque platelet which had precipitate along its limiting membrane as well as within the stored-matrix substance, and a less-frequently seen platelet with lower electron opacity which contained precipitate only along its limiting membrane. Deposits were reduced at all sites following exposure of eggs to EGTA either prior to or after osmium-antimonate fixation. Initial fixation in glutaraldehyde followed by postfixation in osmium-antimonate solutions provided better preservation of structure but less precipitation than direct fixation in osmium-antimonate. The organelle sites of calcium binding identified within unfertilized sea-urchin eggs may participate in stimulus-secretion coupling (exocytosis of the cortical granules) and the activation of embryogenesis at fertilization.
Electron microscopic x-ray microprobe analysis of pyroantimonate precipitates in platelets fixed in osmium tetroxide-pyroantimonate revealed calcium localization in the nucleoids of alpha-granules. This pool of calcium had largely disappeared within 10 sec after stimulation of platelets by thrombin. Such a rapid change suggests that this calcium pool may have a regulatory role in stimulus-response coupling.
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The morphologic effects of actinomycin D (ACTD) on normal and regenerating rat pancreas at three dosage levels were studied. ACTD at 1.0 and 0.5 mug/g total body weight produced reversible nucleolar and cytoplasmic changes in the acinar cells of the normal rat pancreas. The nucleolar alteration, zonal segregation, preceded the appearance of cytoplasmic lesions, implying a precursor relationship of the former to the latter. ACTD-induced cytoplasmic lesions were similar to those produced by ethionine. Since ethionine failed to produce nucleolar changes, it is suggested that the primary mechanisms of action of these two compounds are different, although the cytoplasmic lesions may occur by a common metabolic route. Regeneration of exocrine pancreas after injection of ethionine was affected by ACTD to different degrees depending upon the time of ACTD administration. Regeneration was prevented when ACTD, 0.5 mug/g, was given at day 11, the first day after the ethionine regimen; it was markedly decreased when ACTD was given at day 12, but much less affected when ACTD was given at later days. The effects at days 11 and 12 may have been related to prevention of DNA transcription and the formation of mRNAs at these days. The 0.05 mug/g dosage of ACTD had much less effect on normal and regenerating acinar cells, causing reduced cytoplasmic basophilia, decreased ergastoplasm and fewer free ribosomes, which suggests impairment of rRNA synthesis.
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The purpose of this study was to evaluate the technical efficacy and safety of iv ferumoxides (Feridex), a superparamagnetic iron oxide contrast agent for detection of hepatic lesions using conventional spin-echo and fast spin-echo MR images. Precontrast and postcontrast MR studies were performed on 25 patients with suspected focal hepatic lesions. Conventional T1- and T2-weighted MR images, as well as fast spin-echo and fat suppressed fast spin-echo MR images, were evaluated. Quantitative assessment of the contrast agent was performed obtaining region of interest measurements of the liver, spleen, and selected hepatic lesions. The pulse sequences were also evaluated subjectively for overall image quality and a subjective assessment of lesion detection. The use of a superparamagnetic iron oxide contrast agent led to a decrease in hepatic signal intensity on all pulse sequences. Lesion-to-liver contrast increased 41.1%, 36.5%, and 32.0% on the conventional T2, fast spin-echo, and fat suppressed fast spin echo pulse sequences, respectively. Lesion-to-liver contrast decreased on the T1-weighted postcontrast pulse sequence by 23.8%. Despite improvement in lesion-to-liver contrast, radiologists subjectively preferred the precontrast sequences because of overall better image quality. At a dose of 10 mumol/kg, ferumoxides favorably impacts lesion-to-liver contrast, and may be useful in hepatic imaging, more with conventional T2-weighted spin-echo pulse sequences than with T2-weighted fast spin-echo pulse sequence.
This report describes the development of a new procedure for assessing neurodevelopmental delay in young children. The Primitive Reflex and Postural Adjustment Assessment procedure is designed to measure degrees of occurrence of remnants of primitive reflexes and immature postural adjustment. Preliminary findings show that the Primitive Reflex and Postural Adjustment Assessment procedure can successfully identify degrees of neurodevelopmental delay in young children, and that the procedure differentiates normal children from mentally retarded and emotionally disturbed children. Additional work is needed to assess the validity and reliability of this procedure.