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Biomedical subjects

W D Kuhlmann

Publications and source records attributed to W D Kuhlmann.

At least 37 records · Page 2Linked to original sources
PubMed1984

Characterization, localization and regulation of a novel phenobarbital-inducible form of cytochrome P450, compared with three further P450-isoenzymes, NADPH P450-reductase, glutathione transferases and microsomal epoxide hydrolase.

Two cytochromes P450 (PB1 and PB2) have been isolated from the livers of rats treated with phenobarbital. PB2 (mol. wt. 53 500) is novel and is the first example of a phenobarbital-inducible enzyme with a Soret peak at 447 nm. Using an enzyme-linked immunosorbent assay, some immunochemical and structural similarities were observed between these cytochromes. PB1 and PB2 were induced by phenobarbital, Aroclor 1254, trans-stilbene oxide and to a lesser extent by isosafrole. Immunohistochemical localization of these proteins in the liver of untreated rats showed PB1 to be localized in a large area and PB2 in a narrow range of cells around the central vein. This demonstrates the heterogeneity of hepatocytes even within the centrilobular area and indicates that the synthesis of these two proteins is regulated differently although both are induced by the same agent, phenobarbital. Two 3-methylcholanthrene inducible cytochromes MC1 (mol. wt. 54 500) and MC2 (mol. wt. 57 000) were present at very low levels, MC2 mostly in the periportal region but also diffusely distributed throughout the lobule including some centrilobular cells, MC1 concentrated in the centrilobular region. The localization of two major groups of glutathione transferases (GST's) was also different. 'C' type proteins (Yb Yb') and microsomal epoxide hydrolase (EH), were concentrated around the central vein, whereas the 'B' type proteins (Ya Yc) and cytochrome P450 reductase were distributed in a larger area of this region. Thus, the localization was different for some members of the same enzyme family, whilst similarities in the localization existed across the border of the families: (i) PB2, MC1, EH and GST 'C' type proteins were concentrated in a narrow area around the central vein; (ii) PB1 and GST 'B' type proteins occupied a large centrilobular area; (iii) MC2 levels were very low, predominantly periportal but also diffusely distributed throughout the lobule. Treatment of the animals with inducers increased the staining intensity and in several cases extended the areas of cells containing these proteins over the adjacent zone without fundamentally altering their distributions. However, treatment with beta-naphthoflavone led to a shift of MC1 to the periportal area. This suggests that the expression of these proteins in certain cells is not an irreversible quality of differentiation but depends on the degree of suppression and derepression of regulatory components.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Lectin--peroxidase conjugates in histopathology of gastrointestinal mucosa.

Peroxidase (HRP) conjugates of Dolichos biflorus agglutinin (DBA), Arachis hypogaea agglutinin (PNA) and Ulex europaeus agglutinin I (UEA I) were used as specific molecular probes in order to describe histological patterns of carbohydrate moieties in glycoconjugates of gastric mucosa. Specimens of normal mucosa, metaplasias and carcinomas were fixed, embedded in paraffin and stained with lectins by a postembedding technique. In normal mucosa, DBA reacted with surface epithelial, parietal and antral gland cells; neck cells did not react. In single goblet cell metaplasia, with few exceptions, goblet cells showed DBA binding. In contrast, mainly negative goblet cells were seen in intestinal metaplasia. In gastric carcinomas of intestinal or diffuse types, heterogeneous staining patterns were observed. Large numbers of mucus-producing surface epithelial, neck and antral gland cells stained with PNA-HRP conjugates. Parietal cells did not react. Among the chief cells only few showed PNA binding. In single goblet cell metaplasia, equal numbers of goblet cells were positive or negative, whereas goblet cells in intestinal metaplasia were mainly unstained. Carcinomas contained both PNA-positive and PNA-negative cells; PNA-positive cells occurred preferentially in the tumor periphery. UEA I - HRP conjugates stained the bulk of surface epithelial and neck cells; chief cells and antral gland cells were mainly positive, too. Parietal cells did not react. In single goblet cell metaplasia and intestinal metaplasia, UEA I-positive as well as UEA-negative goblet cells occurred. Striated cells exhibited a great variety of lectin reactivity. Carcinomas also showed a heterogeneous staining pattern. Under both normal conditions and in carcinoma development, qualitative and quantitative differences in the composition of glycoconjugates must be expected.

Gastric Mucosa↗
PubMed1983

Cellular localization of lectin-affinity in tissue sections of normal human duodenum.

Peroxidase (HRP) conjugates of Arachis hypogaea agglutinin (PNA), Dolichos biflorus agglutinin (DBA), Ulex europaeus agglutinin I (UEA I) and Bandeiraea simplicifolia agglutinin I (BSA I) were used to detect the expression of carbohydrate moieties in glyco-conjugates of normal human duodenal mucosa. Lectin histology was performed on sections from paraffin embedded specimens of donor blood groups A, B, AB and 0. While PNA, DBA and UEA I staining appeared to be independent of the donor blood groups, BSA I affinity was restricted to the blood groups B and AB. Neither striated columnar cells nor goblet cells stained with PNA-HRP conjugates. Glyco-conjugates of goblet cell mucins reacted with DBA and UEA I, but staining intensities varied in crypts and villi: positive goblet cells occurred preferentially in upper parts of the crypts and in villi. Striated columnar cells also exhibited variation in staining intensities, with binding of DBA and UEA I observed in the upper half of crypts and in villi, occurring predominantly along the brush border and in apical parts of the cells. Glyco-conjugates synthesized by Brunner's gland cells possessed a great variety of lectin reactivity with the lectins employed. Within a given histological section positive gland areas with different staining intensities beside negative cell populations might reflect different functional states.

Blood Group Antigens↗
PubMed1982

Advances in ultrastructural postembedment localization of antigens in Epon sections with peroxidase labelled antibodies.

Procedures for ultrastructural postembedment immunolocalization of antigens were investigated by use of the indirect peroxidase labelled antibody method. Results were compared with those obtained with the ultrastructural preembedment technique. IgG globulins in IgG synthesizing cells of rat lymph nodes served as model. Formaldehyde fixation, ethanol dehydration and embedment in Epon 812 did not abolish immunoreactivity. Sufficient numbers of antigens remained for subsequent postembedment immunohistology. Antigen binding sites were readily localized in ultrathin sections. For this purpose, polymerized resin had to be partially removed. Sodium methoxide in methanol/benzene mixture rapidly dissolved ultrathin sections. Diluted alcoholic sodium hydroxide enabled reliable resin etching and subsequent immunostaining. Treatment of ultrathin sections with hydrogen peroxide alone, did not permit immunolocalization of IgG. Optimal antigen detection was attained with antibodies isolated by affinity chromatography and purified peroxidase conjugates. IgG was stained in the rough-surfaced endoplasmic reticulum, the perinuclear space and the Golgi apparatus; the subcellular distribution corresponded to that obtained with preembedment immunohistology. In the latter technique, substrate accumulation was more homogenous than in postembedment staining.

Animals↗
PubMed1982

Immunohistological localization of alpha 1-fetoprotein in normal and diseased liver.

Cellular alpha 1-fetoprotein (AFP) is localized by light and electron microscopic immunoperoxidase methods. For light microscopic studies we employed ethanol-acetic acid fixed and paraffin embedded liver blocks. For the ultrastructural localization of AFP, formaldehyde-glutaraldehyde fixed tissues were used in preembedding phase. The occurrence of AFP was studied in normal and diseased livers of mice and rats: (a) fetal and neonatal livers; (b) liver regeneration after CCl4 intoxication; (c) chemical hepatocarcinogenesis. During ontogenesis, AFP is detected in perinuclear spaces, in lamellae of the RER and in the Golgi apparatus of fetal and postnatal hepatocytes. After CCl4 intoxication of low and high AFP producing mouse strains, cellular AFP is found in hepatocytes of portal, periportal and intermediate zones. Hepatocytes in front of the necroses usually contain the strongest reactions. In early stage of hepatocarcinogenesis, AFP is localized in proliferating oval-shaped cells when injured livers regenerate. At the stage of malignant conversion, distinct AFP staining and non-AFP staining hepatocellular carcinomas occur.

Animals↗
PubMed1981

Alpha-fetoprotein: cellular origin of a biological marker in rat liver under various experimental conditions.

Alpha1-fetoprotein (AFP) was detected by serological, light and electron microscopic methods in various experimental models. These included (a) liver regeneration after partial hepatectomy or CCl4 intoxication (mouse and rat); (b) liver intoxication by high doses of N-nitrosomorpholine (NNM) and chemical induction of hepatomas (rat). AFP levels varied greatly according to the animal species and strains used. Low and high AFP-producing species and strains were distinguished. In liver regeneration after hepatectomy or CCl4 intoxication, cellular AFP was found in the cytoplasm of hepatocytes. In NNM-intoxicated livers, elevated AFP levels were associated with proliferation of canalicular epithelial cells in which AFP was localized. In early stages of hepatocarcinogenesis, significant AFP increase occurred after high-dose carcinogen feeding and AFP was also localized in proliferating canalicular epithelial cells. On low-dose NNM feeding, no cellular AFP was detected unless hepatomas had developed. At the stage of malignant conversion, distinct AFP staining and non-AFP staining hepatocellular carcinomas appeared in livers.

Animals↗
PubMed1981

Resin embedment of organs and postembedment localization of antigens by immunoperoxidase methods.

Various procedures for nonpolar and polar resin embedment were applied to mouse and rat livers for the study of postembedment immunolocalization of alpha 1-fetoprotein, albumin and the microsomal enzyme epoxide hydrolase. Fixations with formaldehyde and with formaldehyde-glutaraldehyde mixtures were used for tissue stabilization. Both fixation schedules did not abolish immunoreactivity. Treatment of liver with inert compounds such as polyvinylpyrrolidones or chemical modification of antigens with ethyl acetimidate prior to embedment improved immuno-staining. Either the low-polarity solvent ethanol or the highly polar ethylene glycol could be employed as dehydrating agents. Antigens were readily localized in sections from Epon 812 embedded livers. For this purpose, polymerized resin had to be partially removed. On the other hand, immunoreactivity of antigens was only faint after embedment in an epoxy-resin based on diepoxide octane. Also, antigens reacted faintly in sections from livers which were embedded at 0 degrees C in the polar acrylate-methacrylate based Lowicryl K4M resin. The indirect peroxidase labelled antibody method was as specific and sensitive as the PAP technique. Optimal antigen detection was attained with antibodies isolated by affinity chromatography and purified peroxidase conjugates. Apart from purified immunological reagents, the addition of high molarity sodium chloride and bovine serum albumin to the wash solutions enhanced immunohistological specificity.

Albumins↗
PubMed1980

Correlation of histology and alpha 1-fetoprotein resurgence in rat liver regeneration after experimental injury by galactosamine.

Intraperitoneal injections of galactosamine-HCl in rats were followed by transitory elevations of serum alpha-fetoprotein (AFP) concentrations. These were associated with regeneration of the damaged liver; a maximum of serum AFP was reached on day 4 (2.08 +/- 0.67 microgram/ml). In sera of untreated rats, serum AFP levels were less than 0.1 microgram/ml and no cellular AFP was detected in liver sections. Two days after galactosamine injections, AFP was localized for the first time in the cytoplasm of epithelial cells of bile ducts and canaliculi in portal spaces. The intensity of AFP staining reached a maximum between days 3 and 4. In addition, faint but distinct AFP-positive reactions were seen in the cytoplasm of randomly distributed hepatocytes. After day 5, AFP-staining cells rapidly disappeared. A strong correlation was noted between reappearance of AFP in sera, intensity of epithelial bile duct proliferation and cellular AFP staining.

Animals↗
PubMed1980

Functional localization of avian intrapulmonary CO2 receptors within the parabronchial mantle.

To determine the location of avian intrapulmonary CO2 receptors, we changed the CO2 stimulus at different regions within the parabronchial mantle and measured the resulting changes in breathing pattern. Three procedures were used to vary the CO2 stimulus: (1) reverse the direction of pulmonary perfusion; (2) stop pulmonary ventilation while maintaining perfusion; and (3) stop pulmonary perfusion while maintaining ventilation. Right and left lungs of adult, anesthetized White Leghorn type chickens were independently, unidirectionally ventilated. The right lung was used to maintain the bird while the left pulmonary artery and vein were cannulated and connected to an extracorporeal gas exchanger, thereby isolating this lung's perfusion. The innervation to both lungs remained intact. When left pulmonary perfusion was reversed, the bird's breathing pattern remained unchanged. The change in breathing pattern that resulted from stopping left pulmonary ventilation was the same during forward perfusion (pulmonary artery to pulmonary vein) as during backward perfusion (pulmonary vein to pulmonary artery). The change in breathing pattern that resulted from stopping forward perfusion was the same as that resulting from stopping backward perfusion. The results indicate that CO2 receptors are not concentrated on the peripheral side of the parabronchial mantle, where venous blood would influence tham, or on the luminal side of the mantle, where arterialized blood would influence them. The CO2 receptors are either distributed symmetrically between the peripheral and luminal sides of the mantle or located in the epithelial lining of the parabronchial lumen.

Animals↗
PubMed1980

Control of respiration in the chicken: effects of venous CO2 loading.

To determine if ventilation in unanesthetized chickens is adjusted sufficiently to prevent alterations in the partial pressure of carbon dioxide in arterial blood (PaCO2) when the CO2 content of mixed venous blood is changed, hypercapnic (PCO2 about 533 Torr) and hypocapnic (PCO2 less than 10 Torr) blood was infused into the left jugular vein of decerebrate chickens at 38 ml . min-1 for 30 sec. Ventilation and PaCO2 were assessed by determining respiratory frequency (f), tidal volume (VT), and the end-tidal CO2 fraction while serial samples of arterial blood were withdrawn from the sciatic artery. Infusion of hypercapnic blood resulted in an increase VT and minute ventilation (VE) as well as an increase in PaCO2. Infusion of hypocapnic blood resulted in a decrease in VT and VE and a small, transient decrease in PaCO2; the PaCO2 often returned to control levels before the end of the infusion period. The respiratory control system in the chicken appears to be better able to maintain a constant PaCO2 when perturbed by a reduced venous CO2 load reaching the lung than when perturbed by a reduced venous CO2 load reaching the lung than when perturbed by an increased CO2 load. These results are consistent with the hypothesis that intrapulmonary CO2 receptors, whose sensitivity to PCO2 is highest at low PCO2, are involved in the breath-to-breath control of breathing in birds.

Animals↗
PubMed1980

Arterial and mixed venous blood gas tensions in exercising ducks.

Adult White Pekin ducks were exercised at three work levels on a treadmill at speeds of .9, 1.47, and 2.16 km/hr for 20 min with a 90 min rest period following each exercise period. Blood gas and pH analyses were performed on samples simultaneously withdrawn from the brachial artery and the right ventricle (as an estimate of mixed venous blood) at predetermined intervals during the experiment. Both arterial and mixed venous PCO2 significantly decreased with the increases in the level of exercise. Arterial pH did not change significantly from resting values at any level of exercise. Mixed venous pH decreased at the onset of exercise but returned to near resting value by the end of each exercise period. These measurements indicate that ducks increase their ventilation during exercise above that required to eliminate the generated CO2. Because the increased ventilation produces a reduction in arterial PCO2, it is unlikely that peripheral or central CO2-sensitive chemoreceptors are responsible for the ventilatory drive.

Animals↗
PubMed1979

Respiratory and cardiovascular responses to exercise in the duck.

Adult White Pekin ducks were exercised for 20 min on a treadmill (3 degrees incline) at two speeds: 0.9 and 1.47 km/h. Each exercise period was followed by a 90-min rest. Heart rate and systolic and diastolic blood pressure increased significantly during each exercise period. During exercise, tidal volume decreased and respiratory frequency increased. Minute ventilation markedly increased at the onset of exercise and continued to increase throughout, whereas clavicular air sac PCO2 (PCSCO2) decreased. Both PACO2 and PVCO2 decreased as the running speed increased. pHv decreased at the onset of exercise, but returned to near resting values by the end of an exercise period. During either exercise period pHa did not significantly change from control values. PAO2 exhibited significant increases at both exercise speeds. Both arterial and mixed venous plasma [HCO3-] decreased significantly with each exercise period. Body temperature increased 1-2 degrees C during each run. Because the increased ventilation produced a reduction in PaCO2 and Pcsco2, it is unlikely that peripheral or central CO2 receptors were responsible for the ventilatory drive: that drive may result from hyperthermia or activity of certain muscle afferents.

Air Sacs↗
PubMed1979

Cardiopulmonary responses to inhaled sulfur dioxide in the chicken.

Selected cardiopulmonary variables were measured in anesthetized, male, White Leghorn type chickens before, during, and after 60 min exposure to various inhaled SO2 concentrations ranging from 0 to 5000 ppm. In one series of experiments, birds breathed through their nostrils and mouth; in a second series they breathed through a tracheal cannula. Exposure to 5000 ppm SO2 rapidly caused death in all birds with cannulated tracheae and in 4 of 5 birds with an intact respiratory system; one bird in each series of experiments died when exposed to 1000 ppm. Inhaling 100 ppm SO2 did not alter heart rate, blood pressure, tidal volume, respiratory frequency, or arterial blood gases and pH. Airway resistance was decreased by inhaling 500 ppm SO2 and was initially decreased but later greatly increased by inhaling 1000 ppm. Respiratory frequency and minute volume were decreased and PaCO2 was increased by inhaling 1000 ppm. The cardiopulmonary responses to inhaling 5000 ppm were generally augmentations of those responses which occurred when 1000 ppm was inhaled. The SO2 could not be detected in caudal thoracic or abdominal air sac gas at any concentration inhaled but vascular congestion and areas of brown discoloration appeared in the lungs of all birds that inhaled 5000 ppm and some that inhaled 1000 ppm. Mucous secretion in the trachea increased in some birds that inhaled 500 ppm SO2 and in most that inhaled higher concentrations. Chickens appear to have more tolerance for inhaled SO2 than most mammals but the pollutant gas at high concentrations detrimetally affects the cardiopulmonary system.

Airway Resistance↗