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Biomedical subjects

K A Siegesmund

Publications and source records attributed to K A Siegesmund.

At least 19 recordsLinked to original sources
PubMed1988

Relationship between distention and absorption in rat intestine. I. Effect of luminal volume on the morphology of the absorbing surface.

Previous studies in vivo have suggested that distention of the intestinal lumen may enhance intestinal absorption by augmenting absorptive surface area. The precise anatomic mechanism for this increase in surface area, however, has not been explored in detail. We developed methods for rapidly freezing and fixing intestinal segments in situ in the nondistended or distended state. Distention led to a reduction in villus height (309.2 +/- 9.9 to 230.7 +/- 11.8 micron) and a marked increase in the width of intervillus space in both the transverse (50.4 +/- 4.8 to 298.0 +/- 24.8 micron) and longitudinal (15.2 +/- 3.4 to 76.0 +/- 10.6 micron) dimensions. There was, however, no absolute change in total mucosal surface area. The changes in morphology occurred instantaneously, were entirely reversible, and were demonstrated at pressures that occur spontaneously in the mammalian intestine. These studies demonstrate that luminal distention results in marked alterations in intestinal histology that promote increased access of luminal contents to intervillus transport sites in the intestine in vivo. The resulting alterations could lead to an increase in functional rather than absolute absorptive surface area.

Animals↗
PubMed1988

Welders' pneumoconiosis: tissue elemental microanalysis by energy dispersive x ray analysis.

Histological examination on lung tissue obtained from 10 symptomatic welders was performed by two certified pathologists without the knowledge of the patients' clinical condition. In all cases, there was some degree of interstitial fibrosis; in five the degree of fibrosis was considered to be moderate to pronounced. The tissue was also analysed by energy dispersive x ray analysis and elemental contents were compared with age matched controls. There was a large amount of iron in the lungs of welders but the silicon content did not differ from the control subjects. No specific foreign element was detected. It is concluded that (1) interstitial pulmonary fibrosis is seen in some welders and (2) the cause of fibrosis does not appear to be coexisting silicosis.

Adult↗
PubMed1987

Fluctuations of alpha cell calcium, potassium and sodium during amino acid perifusion of rat pancreatic islets.

Perifusion of rat pancreatic islets with a physiologic, 6-mM amino acid mixture resulted in typical acute and second phase glucagon secretion over 30 min. At various intervals, islets were acutely fixed and processed for scanning electron microscopy, identification of alpha cells, and measurements of single alpha cell content of calcium (Ca), potassium (K) and sodium (Na) with energy-dispersive x-ray analysis. Biphasic glucagon secretion was attended by corresponding biphasic Ca accumulation and a reciprocal, biphasic suppression of K content and acute phase suppression of Na in alpha cells. All secretory and cellular events were preceded by an evanescent upward spike in alpha cell K at 1 min. These results indicate that alpha cell glucagon secretion in response to amino acid mixtures may be initiated by a K signal and is coupled subsequently to phasic changes in alpha cell Ca content. Fluctuations of alpha cell K and Na appear to relate inversely to Ca, suggesting that transmembrane fluxes of the three cations are interrelated.

Amino Acids↗
PubMed1985

Morphometric and elemental microanalytical studies of human lung in health and disease.

Current methods for determining the fibrogenicity of substances are based on relatively long term exposures of animals to the substance and the evaluation of morphological changes occurring in the lung. The use of inhalation chambers, which produce a more physiological environment, suffer from the need for particularly long exposure times (1-3 years). The present study describes a technique using scanning electron microscopy, energy dispersive analysis, and a digitiser pad with a computer to evaluate the fibrogenicity of silica in cases of known exposure. Scanning electron micrographs taken from silicotic lungs were evaluated for the degree of thickening (fibrosis) and the same areas were analysed for silicon content. Correlations between silicon content and septal thickening were shown to be significant (p less than 0.0001). The study also describes the concentrations of elements found in normal lungs. The technique for establishing correlation curves between elemental concentrations and septal thickening could be of value in determining the fibrogenicity of pure substances after short exposures in an environmental chamber.

Aluminum↗
PubMed1984

Value of in situ elemental microanalysis in the histologic diagnosis of silicosis.

Pulmonary specimens obtained from ten normal subjects and 53 patients with various pulmonary diseases were studied with energy-dispersive x-ray analysis. The amount of silicon in the pulmonary tissue was determined and expressed as a silicon/sulfur (Si/S) ratio. This Si/S ratio was below 0.2 in the ten normal subjects and in 14 patients who had various interstitial pulmonary diseases but had no previous history of exposure to silica or other dusts known to cause pulmonary fibrosis. The Si/S ratio was greater than 0.3 in 19 of 22 patients who had a history of exposure to silica dust and had clear-cut histologic evidence of silicosis. The Si/S ratio was less than 0.2 in 12 and between 0.2 and 0.3 in two of the 14 patients who had a history of exposure to silica dusts but no clinical or histologic evidence of silicosis. We conclude that the determination of the silicon content of tissue by energy-dispersive x-ray analysis is useful in separating the fibrosis due to silicosis from the other causes of pulmonary fibrosis.

Adult↗
PubMed1984

Pneumoconiosis in workers exposed to silicon carbide.

Two men who had been exposed only to silicon carbide for many years in a factory manufacturing refractory bricks developed bilateral reticulonodular densities, as shown on chest radiograms, and complained of dyspnea. An open lung biopsy of one of them showed a large amount of black material in the fibrosed alveolar septums. Studies by X-ray diffraction revealed that the silicon carbide to which they were exposed did not contain quartz; X-ray powder diffraction analysis of the lung tissue revealed at least 6 different silicon carbides, traces of tungsten carbide, and an insignificant amount of quartz. Line-width analysis of the pattern suggested that the lung contained foreign material, with a significant number of particles smaller than 0.1 micron. The etiologic role of silicon carbide for tissue fibrosis is discussed.

Adult↗
PubMed1983

Tolbutamide perifusion of rat islets. Sequential changes in calcium, phosphorus, sodium, potassium, and chlorine in single beta cells.

Fluctuations of calcium, phosphorus, sodium, potassium, and chlorine in beta cells were followed during rat islet perifusion with tolbutamide and related to insulin secretion. In 24 paired experiments two chambers containing 100 islets were perifused with buffered medium containing 4.2 mM glucose alone or with added tolbutamide (200 micrograms/ml). Effluent was collected frequently for insulin determinations. At eight different time intervals from 0 to 20 min islets were acutely fixed, prepared for scanning electron microscopy and beta cells in islet tissue were identified. Element content in 480 single cells was measured by energy dispersive x-ray analysis. Tolbutamide elicited typical monophasic insulin release that exceeded control islet secretory rates from 2 to 6 min with a peak value at 3 min. This pattern was preceded by monophasic calcium accumulation in beta cells that abruptly rose 150% above control cells at 1 min and declined to base line by 4 min. The rapid ascent of calcium was associated with significant depressions of sodium and potassium content without alterations of cell phosphorus. Chlorine fell at 2 min and then rose greater than 50% above control cells at 4 min. After 6 min insulin secretion and element content remained near control levels. We conclude that monophasic calcium accumulation in beta cells is the earliest, most predictive event of islet insulin secretion after a tolbutamide stimulus. Oscillations of beta cell sodium and potassium reciprocally relate to calcium, and an elevation of chlorine content is a relatively late phenomenon in the stimulus-secretion coupling process.

Animals↗
PubMed1981

Fluctuations of calcium, phosphorus, sodium, potassium, and chlorine in single alpha and beta cells during glucose perifusion of rat islets.

To study the relationship between islet hormonal secretion and intracellular content of five elements, a rat islet perifusion technique was used in 24 paired experiments. Control and experimental chambers each containing 100 islets, received 2.8 and 16.7 mM D-glucose, respectively. Effluent was collected frequently for hormone measurements. At eight different time intervals form 0--30 min islets were fixed and prepared for scanning electron microscopy. Over 900 unobscured alpha and beta cells were selected by size and shape criteria. Energy dispersive x-ray analysis was applied to each single cell to determine relative content of calcium (Ca), potassium (K), sodium (Na), chlorine (Cl), and phosphorus (P). Experimental chambers exhibited typical acute (0--9 min) and second phase (10--30 min) insulin secretion in association with suppression of glucagon release after 10 min. At 2 min an abrupt upward K spike in both alpha and beta cells was followed at 3--4 min with a 1.5- to 2-fold rise of Ca and a reciprocal decrease in K, Na, Cl, and P. From 3 to 30 min biphasic insulin secretion. Reduced alpha cell calcium after 6 min preceded suppression of glucagon secretion. After 2 min K related inversely to Ca content in both alpha and beta cells. These results could not be reproduced when D-galactose was substituted for D-glucose. We conclude that sequential changes of Ca content that are reciprocally related to K are predictive of beta cell insulin release and suppression of alpha cell glucagon secretion.

Animals↗
PubMed1980

Tampon-associated vaginal ulcerations.

Colposcopically visible alterations of the vaginal mucosa associated with the use of tampons have been identified. These include mucosal drying, epithelial layering, and microulcerations. The pathophysiology of these transient changes appears to involve fluid transfer with subsequent impairment of intercellular bridges and loss of cell coherence. Tampon products containing superabsorbents are significantly more likely to produce microulcerations than are conventional tampons when worn at times other than during active menstruation. Chronic production of these alterations could lead to clinically obvious lesions of the vagina, and should now be considered in the differential diagnosis of vaginal ulcers.

Adolescent↗
PubMed1980

Elemental content in alveolar septa in various pneumoconioses.

The elemental content of alveolar septa in various pneumoconioses was examind for a possible relationship to interstitial fibrosis. Silicon content, as well as heavy metal content, were evaluated to deterrmine possible interrelationships between the various inorganic dusts. Silicon levels were determined on the basis of silicon-sulphur ratios to accommodate for differences in tissue mass. A study of the variation of silicon-sulphur ratios in silicotics and normal individuals showed no false positives by our diagnostic criteria. A study of 11 cases of siderosis revealed that silicon was not responsible for the fibrosis as previously believed. An analysis of the lungs of 25 non-silicotic fibroses revealed that silicon-sulphur ratios were within normal limits. This technique should be useful in quantitating high exposure to certain dusts and in studying the relationship of such dusts to fibrosis.

Electron Probe Microanalysis↗
PubMed1979

Human lymphocyte-tumor cell interaction. A scanning electron microscopy study.

Cells from the metastatic chest wall lesions of a patient with adenocarcinoma of the breast were incubated with autologous lymphocytes. Their interactions were observed in the scanning electron microscope. The lymphocytes first surrounded the cancer cells; cancer cells then were destroyed while the lymphocytes in contact with them lost their microvilli. The heterologous human lymphocytes being used as controls surrounded the tumor cells but did not destroy them. Lymphocytes in the presence of tumor cells showed interconnections through cytoplasmic bridging.

Adenocarcinoma↗
PubMed1979

Morphologic expression of the interactions of human lymphocytes and Pseudomonas aeruginosa as observed by scanning electron microscopy.

When human lymphocytes and Pseudomonas aeruginosa were incubated together and then observed under the scanning electron microscope, four distinct morphologic observations were made: (1) filopods extending between lymphocytes and bacteria; (2) globular structures bulging out in many of the filopods; (3) filopods connecting lymphocytes to each other in the presence of bacteria; and (4) bacteria adhering to the lymphocytes in areas where decreased numbers of microvilli were present.

Adult↗
PubMed1979

A quantitative immunoperoxidase procedure employing energy dispersive x-ray analysis.

A method is described for substituting gold for osmium as a marker in the unlabeled antibody technique. The gold marker can be detected in the light or electron microscope. The gold-labeled reaction product can be detected in lower concentrations than osmium and can be used as the basis for quantitating antigen concentrations in cells and tissues with the scanning electron microscope and energy dispersive x-ray analysis.

3,3'-Diaminobenzidine↗
PubMed1979

Neonatal cystic choristoma in submandibular salivary gland simulating cystic hygroma.

A congenital cystic malformation occurred in the submandibular salivary gland of a neonate. The embryogenesis and differential diagnosis are discussed. Since it seems to be a product of endodermal heterotopic differentiation or entrapment of foregut epithelial rests in the submandibular gland, it is classified as a cystic choristoma.

Choristoma↗
PubMed1977

Energy dispersive x-ray analysis in the study of pneumoconiosis.

Identification of inorganic substances in the lung is an important step towards the establishment of a cause and effect relationship in the study of pneumoconiosis. The conventional methods for this identification usually require an ashing which makes it difficult to study the localisation of these substances in relation to pathology. A method is described to identify foreign substances in the tissue obtained either on biopsy or autopsy without destroying them. The technique employs scanning electron microscopy together with energy dispersive x-ray analysis. This method not only allows simultaneous multi-elemental analysis of over 80 elements, but also permits detailed morphological examination while the tissue is being analysed.

Humans↗
PubMed1976

A diffuse form of pulmonary silicosis in foundry workers.

Pulmonary silicosis usually is characterized by typical hyalinized, concentric nodules as seen under the microscope and in the corresponding roentgenogram. In the case of three foundry workers, lung biopsy specimens contained no nodules. The chest roentgenograms were not suggestive of silicosis. Examination of the biopsy tissue by scanning electron microscopy and energy dispersive x-ray analysis (EDXA) revealed significant (P less than .05) amounts of silicon in the thickened fibrous tissues of septa, pleura, and around blood vessels, enough to permit the diagnosis of silicosis. All three patients had severe functional impairment. It is not clear at this time what factors were responsible for a diffuse distribution of silicon in these cases.

Humans↗