PubMed Health⌕ Search

Biomedical subjects

M D O'Donnell

Publications and source records attributed to M D O'Donnell.

At least 19 recordsLinked to original sources
PubMed1999

Ultrastructure of lung elastin and collagen in mouse models of spontaneous emphysema.

The tight-skin (Tsk) and beige (bg) mutants of the C57B1/6J strain of mouse spontaneously develop air-space enlargement reminiscent of human emphysema. To determine if this enlargement is accompanied by matrix destruction, as in the human disease, we examined the elastin and collagen matrices of the lungs of both mutants. The ultrastructure of these matrix components was separately visualized by scanning electron microscopy following controlled alkali digestion, which preserves collagen, and formic acid digestion, which enables visualization of elastin. Significant elastin destruction suggestive of an elastolytic process was observed in the lungs of Tsk mice. Thickening of elastin lamellae was observed in the lungs of bg mice, suggesting that congenital matrix remodeling may underlie air-space enlargement in this strain.

Animals↗
PubMed1996

Elastin and collagen remodeling in emphysema. A scanning electron microscopy study.

The relationship between elastin degradation and emphysema is well known. Recent evidence suggests that a complex process of pulmonary remodeling occurs within the emphysematous lung. The aim of this study was to assess the extent of extracellular matrix remodeling in emphysema by ultrastructural examination of elastin and collagen templates in an animal model of emphysema and in human emphysematous lungs. Emphysema was induced in rats by the intratracheal administration of porcine pancreatic elastase. Human lung samples were obtained at surgical resection for lung carcinoma. Emphysema was confirmed morphometrically and quantitated using the mean linear intercept. Matching sections were treated with sodium hydroxide and formic acid to expose collagen and elastin templates, respectively. Scanning electron microscopy with stereo-pair imaging allowed three-dimensional visualization of the exposed templates. In emphysematous lungs from both sources, sheets of elastin were disrupted and perforated with multiple fenestrations. In elastase-induced emphysema, this disintegration was accompanied by a marked increase in thickness of collagen fibrils, which contrasted with the fine fibrillar network of control lungs. Similarly, a pattern of thickened fibrils and disorganized deposition of collagen was observed in human lungs. In conclusion, these findings support the novel concept of increased collagen deposition and aberrant collagen remodeling in the pathogenesis of emphysema.

Animals↗
PubMed1994

Three-dimensional structure of lung elastin demonstrated by scanning electron microscopy/stereo-pair images.

The aim of this study was to expose the inflated 3-D structure of lung elastin. Formic acid digestion followed by freeze-drying unveiled the lamellar framework. The 3-D structure of elastin was well preserved within the alveolar septa and ducts, as demonstrated by scanning electron microscopy/stereo-pair photography. Elastin fibers are seen in the alveolar septa, which are continuous with the lamellae. The removal of collagen fibers and cells by formic acid was visualised as a function of time: The optimum was 48 hours. Transverse sections still retained some collagen fibrils and partially digested cells in addition to elastin as shown by transmission electron microscopy (TEM). Formic acid digestion followed by critical point drying caused damage to the lamellar structures and they appeared to collapse. Sodium hydroxide digestion combined with freeze-drying did not preserve the 3-D lamellar structure of elastin, but converted it into flat ribbonlike bands. The main structures remaining following alkali treatment were identified by TEM as collagen fibrils well preserved in their original locations.

Animals↗
PubMed1991

An alkali digestion method to expose connective tissue fibers: a scanning electron microscopy study of rat lung.

Alkali digestion has been used to remove cellular elements of tissues thus exposing the underlying connective tissue framework. We studied the action of this severe alkali treatment on the delicate tissues of rat lung. The lungs of male Sprague-Dawley rats were perfused with saline to remove blood and then inflated by fixation through the airways at 20 cm pressure. Sections of lung 2 x 5 x 5 mm were immersed in 2.5 M NaOH at 25 degrees C for 6 h, 16 h, 24 h, 48 h, and 72 h. The alkali was changed daily. Tissues were washed to neutral with water (24 h), treated with tannic acid (1%, 3h), post-fixed with osmic acid (1%, 3 h) and processed for SEM. At 6 h, epithelial cells started to peel off the alveolar surface. At 16 h the digestion process was well advanced. At 48 h the cells were completely removed revealing the lattice network of connective tissue fibers within the alveolar surface. The method allows the complete removal of cellular elements of the lung while retaining the very fine 3D structure of the connective tissue matrix.

Animals↗
PubMed1990

The skeletal framework of human kidney and renal cell carcinoma. A scanning electron microscopic study.

The three dimensional architecture of the connective tissue framework of normal human kidney and three renal cell carcinomas was studied. A sodium hydroxide maceration technique was used to remove the cellular elements thus exposing the underlying connective tissue structures. The collagen fibrillar network was visualized using the scanning electron microscope. In normal kidney the fibres were fine, and smooth, and corresponded to the shapes of the original parenchymal constituents. The fibres of the kidney tumours were coarse in nature and irregularly distributed. The technique provides a rapid method for studying connective tissue fibres in normal and diseased tissue. The three dimensional architecture thus exposed enhances our knowledge of tumour stroma.

Carcinoma, Renal Cell↗
PubMed1983

Suitability of control materials in the differential inhibition assay for human pancreatic and salivary amylase.

We investigated the behavior of 26 quality-control sera with the inhibitor method for differential amylase (EC 3.2.1.1) assay. We also studied the sensitivity to the wheat-derived inhibitor of pancreatic amylases from 10 different animals in comparison with human pancreatic and salivary amylase. The results indicate that only control materials containing human amylases can be measured accurately. The animal amylases (bovine, equine, porcine) used in many quality control sera are relatively insensitive to the inhibitor as compared with human pancreatic and salivary amylase.

Amylases↗
PubMed1981

Problems associated with the radioimmunoassay of serum trypsin.

A commercial trypsin radioimmunoassay (RIA) kit was used for its ability to measure trypsin bound to the serum protease inhibitors, alpha 2 macroglobulin (alpha 2 M) and alpha 1 anti-trypsin (alpha 1 AT). Only 20% of trypsin bound to alpha 2 M and 70% bound to alpha 1 AT was detected by the assay system. Recovery of trypsin added to human serum varied from 0 to 20%. Standard curves prepared from purified human cationic trypsin did not exhibit parallelism with the kit standard curves. Inclusion of horse serum in the standard solutions improved the parallelism observed. Immunoreactive trypsin (IRT) levels obtained for serum samples were found to vary considerably depending on the standard curve used to calculate the assay results. Lower IRT levels were observed when trypsin standards prepared in the absence of horse serum were used as reference.

Humans↗
PubMed1980

Plasma pancreatic and salivary-type amylase and immunoreactive trypsin concentrations: variations with age and reference ranges for children.

The differential alpha-amylase (EC 3.2.1.1) assay was applied to 166 control children in the age range 0.1--13 years. Circulating levels of both pancreatic and salivary-type amylase were very low (mean 20 U/l) in the first four months of life. Pancreatic levels increased gradually with age, reaching adult levels (mean 74 U/l) by the age of eight years. Salivary amylase levels showed a sharp rise in the 0.9--1.9 year period reaching maximum levels (mean 99 U/l) by age 5--6 years. While linear regression analysis showed significant correlation between age of subject and pancreatic and salivary amylase levels, no such correlation was evident between age and plasma immunoreactive trypsin levels over the age range studied. Plasma trypsin levels in children were lower than reported adult values. Reference ranges for pancreatic and salivary-type amylase and immunoreactive trypsin in children are presented. The importance of age-matching, when pancreatic amylase and plasma trypsin are being investigated in children, is emphasised.

Aging↗
PubMed1978

Renal clearance of pancreatic and salivary amylase relative to creatinine in patients with chronic renal insufficiency.

Pancreatic and salivary amylase/creatinine clearance ratios in patients with various degrees of renal impairment were compared with those obtained for control subjects. In chronic renal insufficiency (mean GFR 30 ml/min +/- 15 SD; n = 13) the clearance ratios for pancreatic (mean 3.5 +/- 1.85 SD) and salivary (mean 2.3 +/- 1.3 SD) amylase were significantly higher (P less than 0.05) than those in controls. Corresponding control values (n = 26) were 2.64 +/- 0.86 (pancreatic) and 1.64 +/- 0.95 (salivary). Three patients showed values above the normal limit. In the diabetic group (mean GFR 41 ml/min +/- 22 SD; n = 10) salivary amylase/creatinine clearance ratios (mean 2.36 +/- 1.55 SD) were significantly higher than in controls (P less than 0.05). Three patients showed raised values. Pancreatic amylase clearance was raised in only one of these patients. Three patients with terminal disease (mean GFR 10 ml/min) showed markedly raised (two- to threefold) clearance ratios for both salivary and pancreatic amylase. Of a total of 26 patients, eight had increased total amylase/creatinine clearance ratios. Pancreatic amylase/creatinine clearance was increased in seven patients, while nine patients showed raised salivary amylase/creatinine ratios. Patients with raised clearance ratios did not have clinical evidence of pancreatitis. We suggest that, in the presence of impaired renal function, a high amylase/creatinine clearance ratio need not be indicative of pancreatic disease.

Adult↗
PubMed1978

Pancreatic and salivary amylase/creatinine clearance ratios in normal subjects and in patients with chronic pancreatitis.

The clearance of pancreatic and salivary amylase relative to creatinine was measured in 26 control subjects and 22 patients with chronic pancreatitis. Control values for pancreatic amylase clearance (+/- SD) were 2.64 +/- 0.86% compared with 1.54 +/- 0.95% for salivary amylase. In chronic pancreatitis, pancreatic amylase clearance ratios were significantly higher than controls (P less than 0.0005, mean 4.09 +/- 1.63 SD). The difference in clearance rate of salivary amylase did not reach a level of significance when compared with the control group. Twelve of the 22 patients showed pancreatic amylase clearance values above the normal limit of 4.4, while only five were abnormal when the clearance of total amylase was measured. The patients also showed statistically higher (P less than 0.0005) levels of serum salivary amylase when compared with 69 control sera. No such difference was found for the pancreatic component of serum amylase. Comparison of beta2-microglobulin clearance values showed no statistical difference between patients and controls.

Adult↗
PubMed1977

Changes in pancreatic and intestinal enzyme activities following chenodeoxycholic acid feeding.

The effect of CDCA feeding on pancreatic and intestinal enzymes was studied. Mice were fed 0.5% w/w chenodeoxycholic acid in a normal diet. Pancreatic lipase concentration was significantly increased after 3 days on the CDCA diet, while amylase and trypsin concentrations were significantly higher at 23 days when compared with the controls. At 70 days there was a significant increase in the concentrations of amylase, trypsin, and lipase. Protein concentrations paralleled the rise in enzyme levels. Amylase and lipase, when measured as specific activities, were still higher than the controls at 70 days. Intestinal amylase levels did not change during the experiments, but intestinal alpha-glucosidase activity increased significantly in the CDCA-treated animals. The results are discussed in terms of their similarity with those reported to occur after feeding soybean trypsin inhibitor.

Amylases↗
PubMed1977

Differential serum amylase determination by use of an inhibitor, and design of a routine procedure.

We describe a new method for measuring pancreatic and salivary-type amylases in serum that requires no electrophoresis or chromatography. An inhibitor protein (from wheat) with a 100-fold greater specificity for human salivary than for human pancreatic amylase was used to analyze mixtures of the two enzymes. The concentration of pancreatic and salivary amyalase was determined in 141 normal sera (72 men and 69 women). Statistically significant differences were found for serum pancreatic amylase between mean and women, higher values being shown in women. No sex-related difference was found for the salivary component of serum amylase. With this method, the increase in serum amylase activity in pancreatitis was shown to be attributable to the pancreatic component. In mumps, the increase is attributable to the salivary component. In pancreatic insufficiency, serum pancreatic amylase activities were significantly lower than in the controls. Our method is simple and rapid; our results agree well with those of other authors who used chromatographic or electrophoretic methods.

Adolescent↗
PubMed1976

Purification and properties of an alpha-amylase inhibitor from wheat.

Four inhibitors of alpha-amylase (EC 3.2.1.1) were separated from an alcohol extract of wheat by ion-exchange chromatography on DE52-cellulose. One inhibitor, which showed the greatest specificity for human salivary amylase relative to human pancreatic amylase, has been purified by the following steps: (a) alcohol fractionation (60--90%) of water extract (b) ion-exchange chromatography on QAE-Sephadex A-50; (c) re-chromatography on DE52-cellulose and (d) gel filtration on Sephadex G-50. The purified inhibitor is 100 times more specific for human salivary amylase than for human pancreatic amylase. It shows an electrophoretic mobility of 0.2 on disc gel electrophoresis and a molecular weight of about 21 000. This inhibitor contributes about 16% to the total salivary amylase inhibiting power of the wheat extract.

Amylases↗