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Biomedical subjects

H Denk

Publications and source records attributed to H Denk.

At least 163 records · Page 9Linked to original sources
PubMed1976

[The lung phospholipid content in newborn infants with idiopathic respiratory distress syndrome in relation to lung histology and survival time (author's transl)].

In an autopsy series on 25 newborn infants who died in the perinatal period (19 with and 6 without respiratory distress syndrome [RDS]) the total phospho-lipid, lecithin, and sphingomyelin content was determined in lung homogenates as parameters of the surfactant content. Histologically, the newborn infants with RDS were subdivided into those with and those without hyaline membranes. Newborn infants with RDS hat a lower lung phospho-lipid content than mature newborn infants without RDS but there was no difference in phospholipid content in relation to the presence or absence of hyaline membranes. The lecithin content of the lungs in those infants with RDS who had survived for more than 24 hours was higher in the absence of hyaline membranes than in their presence.

DNA↗
PubMed1976

Blood group isoantigens in human benign and malignant vascular tumors.

Paraffin material of 31 benign and malignant vascular tumors was investigated with respect to their blood group isoantigen (BG) content by the mixed cell agglutination reaction (MCAR). In capillary hemangioma, BG was found in endothelial cells as well as in solid buds. Benign hemangioendothelioma found in endothelial cells as well as in solid buds. Benign hemangioendothelioma found in children differed from that found in adults in that in juvenile cases only endothelial cells expressed BG whereas in adult cases BG isoantigenity was present in endothelial cells as well as in intercapillary cellular elements. In pericytomas only endothelial cells were BG positive, whereas the tumor cells lacked BG. Similar results were obtained with glomus tumors. All but one hemangiosarcoma were BG negative. In one case, however, which probably resembled a "true" malignant hemangioendothelioma (Stout and Lattes, 1967) the tumor cells contained BG in conspicuous amounts.

Adult↗
PubMed1976

Biochemical properties of rat liver mitochondrial aldehyde dehydrogenase with respect to oxidation of formaldehyde.

The oxidation of formaldehyde by rat liver mitochondria in the presence of 50 mM phosphate was enhanced 2-fold by exogenous NAD+. Absolute requirement of NAD+ for formaldehyde oxidation was demonstrated by depleting the mitochondria of their NAD+ content (4.6 nmol/mg of protein), followed by reincorporation of the NAD+ into the depleted mitochondria. Aldehyde (formaldehyde) dehydrogenase activity was completely abolished in the depleted mitochondria, but the enzyme activity was restored to control levels following reincorporation of the pyridine nucleotide. Phosphate stimulation of formaldehyde oxidation could not be explained fully by the phosphate-induced swelling which enhances membrane permeability to NAD+, since stimulation of the enzyme activity by increased phosphate concentrations was still observed in the absence of exogenous NAD+. The Km for formaldehyde oxidation by the mitochondria was found to be 0.38 nM, a value similar to that obtained with varying concentrations of NAD+; both Vmax values were very similar, giving a value of 70 to 80 nmol/min/mg of protein. The pH optimum for the mitochondrial enzyme was 8.0. Inhibition of the enzyme activity by anaerobiosis was apparently due to the inability of the respiratory chain to oxidize the generated NADH. The inhibition of mitochondrial formaldehyde oxidation by succinate was found to be due to a lowering of the NAD+ level in the mitochondria. Succinate also inhibited acetaldehyde oxidation by the mitochondria. Malonate, a competitive inhibitor of succinic dehydrogenase, blocked the inhibitory effect of succinate. The respiratory chain inhibitors, rotenone, and antimycin A plus succinate, strongly inhibited formaldehyde oxidation by apparently the same mechanism, although the crude enzyme preparation (freed from the membrane) was slightly sensitive to rotenone. The mitochondria were subfractionated, and 85% of the enzyme activity was found in the inner membrane fraction (mitoplast). Furthermore, separation into inner membrane and matrix components indicated a distribution of aldehyde dehydrogenase activity similar to malic dehydrogenase.

Aldehyde Oxidoreductases↗
PubMed1976

Inhibition of nadph-driven microsomal lipid peroxidation by cytosol factor(s). Effect of a fat-free, high carbohydrate diet.

Male Swiss mice were given free access to a fat-free, high carbohydrate diet. The liver cytosol fraction from these mice contained a heat-sensitive factor that markedly inhibited microsomal, ferric pyrophosphate stimulated, NADPH-driven lipid peroxidation. The diet-induced factor was apparently incorporated into the microsomes after 12 days of continuous feeding, since lipid peroxidation by these microsomes was strongly diminished. The factor disappeared from the cytosol after 24 h of fasting and reappeared after refeeding the mice with the fat-free, high carbohydrate diet.

Animals↗
PubMed1976

Immunofluorescence studies on pathologic routine material: application to malignant lymphomas.

In an attempt to apply immunmorphologic techniques to pathologic routine material, malignant lymphomas of the Non-Hodgkin- and the Hodgkin-type were studied by indirect immunofluorescence. To minimize nonspecific background staining formalin fixed paraffin sections were treated with protease prior to incubation with the antisera. The usefullness of this procedure in providing additional diagnostic criteria was tested on specimens of malignant lymphomas (chronic lymphocytic leukemias, immunocytic lymphomas, plasmocytic lymphomas, centrocytic lymphomas, centroblastic-centrocyctic lymphomas, centroblastic lymphomas, immunoblastic lymphomas, lymphoblastic lymphomas of Burkitt, convoluted and unclassified type, Hodgkin's disease). In addition, cases of nonspecific lymphadenitis were studied. The discrimination of single cells particularly of the B-cell line was facilitated using immunofluorescence and different patterns were easily recognized thus aiding the diagnosis based on light microscopic criteria. In addition, preliminary evidence was obtained that lymphoblastic lymphomas categorized as "others" may be further characterized.

Fluorescent Antibody Technique↗
PubMed1976

Hepatic organelle interaction. IV. Mechanism of succinate enhancement of formaldehyde accumulation from endoplasmic reticulum N-dealkylations.

Further evidence for organelle interaction during drug metabolism by the liver is presented. The apparent stimulation by succinate of formaldehyde accumulation in the medium, which was reported to occur with liver slices and homogenates as well as with mitochondria plus microsomes, has been shown to be the result of succinate inhibition of mitochondrial aldehyde dehydrogenase. The mechanism of succinate inhibition is shown to be by reverse electron transport, and an increase in the NADH to NAD+ ratio in the mitochondria; the aldehyde dehydrogenase requires the oxidized form of the pyridine nucleotide as its cofactor. Studies on in vitro N-demethylation by liver microsomes and endoplasmic reticulum segments which cosediment with the mitochondria indicate that formaldehyde produced by the mixed function oxidase is handled differently from formaldehyde added to the medium. The latter is mainly retained in the medium containing 5 mM semicarbazide, while the generated formaldehyde is more than 50% consumed by the mitochondria. Electron microscopy has indicated that the microsomes and the endoplasmic reticulum fragments have a tendency to align themselves close to the mitochondria when present in the same medium. Consequently, it is possible that formaldehyde released to the medium adjacent to the mitochondria, as by N-demethylation, would be exposed to semicarbazide for shorter periods than that added directly to the medium. In agreement with this suggestion, complexing of formaldehyde with semicarbazide was observed spectroscopically not to be an extremely rapid reaction even at 37 degrees C. This is believed to be the reason for the greater extent of consumption of formaldehyde generated by the endoplasmic reticulum.

Aldehyde Oxidoreductases↗
PubMed1976

Spontaneous rosette formation by lymphocytes. Differential effect of cytochalasin B on thymocytes and thymus-related peripheral blood lymphocytes in the guinea-pig.

In the present investigation the differences in the capacity of thymocytes (Th) and thymus-related peripheral blood lymphocytes (TBL) of the guinea-pig to form spontaneous rosettes with rabbit erythrocytes (RRBC) were further evaluated. Cytochalasin B (CB) inhibited TBL rosette formation but was largely ineffective with respect to Th. This suggests that membrane modulation and microfilament function are requirements for the formation of TBL but not of Th rosettes. A certain critical RRBC receptor density on the lymphocyte may be necessary for a stable rosette. Our results suggest that different RRBC receptor densities on Th and TBL account for the differences in rosette forming capacity of these two cell types. In native Th, the receptor density may be high enough to warrant stable rosette formation. In TBL, however, active membrane movement and perhaps clustering of receptors may be necessary to achieve the local critical receptor density as prerequisite of a stable rosette.

Animals↗
PubMed1976

Experimental induction of hepatocellular hyalin (Mallory bodies) in mice by griseofulvin treatment. 1. Light microscopic observation.

Griseofulvin (GF) feeding of mice resulted in protoporphyria, liver cell damage, bile duct alterations, and finally hepatoma formation. In addition, hepatocellular hyalin developed, resembling in its morphology classic Mallory bodies (MB) as seen in alcoholic and nonalcoholic liver disorders in man. Liver cells containing MB often displayed features of severe cell damage and MB were finally released into the sinusoids and degraded by macrophages. The rapid disappearance of MB following GF discontinuation and the reappearance after resumption of GF feeding suggest an intimate relationship between metabolic alterations in the hepatocytes exerted by the drug and MB formation. This assumption is further supported by the fact that MB change their tinctoreal properties in chromotrope aniline blue-stained sections after GF discontinuation, possibly relfecting degeneration. Long term GF treatment apparently primed the liver for MB formation since the cells were able to respond almost instantly with MB to a GF challenge after a 1-month GF-free period.

Animals↗
PubMed1975

Epithelial blood group antigens in colon polyps. I. Morphologic distribution and relationship to differentiation.

The distribution patterns of epithelial blood group AB antigens (BG) in colon polyps of varying degrees of differentiation were studied by the mixed cell agglutination reaction. BG appeared in colon polyps if a certain degree of dedifferentiation was present. Two different distribution patterns were recognized: 1) association of BG with the secretory part of goblet cells with slight-to-moderate atypia and 2) association of BG with the whole cells in cases of pronounced dedifferentiation and loss of secretory activity. The second type resembled the distribution pattern of BG found previously in colon carcinomas. With respect to BG, the mucosa of colon polyps behaved similarly to embryonal colon mucosa. The detection of BG represents a useful method to assess objectively the degree of dedifferentiation in most colon polyps.

ABO Blood-Group System↗
PubMed1975

Mouse model for protoporphyria. I. The liver and hepatic protoporphyrin crystals.

Outbred albino mice were rendered protoporphyric by a diet containing 2.5% (weight) of griseofulvin. There was a 5-fold increase in liver weight, hepatocellular degeneration and necrosis, cholestasis, ductular proliferation and cirrhosis. Liver protoporphyrin values were elevated and brown pigment granules were present in hepatocytes, Kupffer cells, and bile ducts. The granules showed red fluorescence, birefringence, and, at the ultrastructural level, consisted of aggregates of needle-like crystals. Crystals isolated from such livers showed solubility and absorption characteristics of protoporphyrin; in vitro recrystallization of protoporphyrin, extracted from protoporphyric mouse livers, yielded crystals identical with those observed in vivo, and commercial protoporphyrin exhibited similar morphologic features. The liver pathology and protoporphyrin crystals observed in these animals are identical to the liver pathology and crystals observed in the human disease, erythropoietic protoporphyria. In this mouse model, protoporphyrin crystals are intimately associated with hepatocellular injury and it appears that their accumulation within hepatocytes leads to hepatocellular destruction. A similar pathogenesis is postulated for the hepatic damage that occurs in some cases of erythropoietic protoporphyria.

Animals↗
PubMed1975

Adherence of rabbit erythrocytes to guinea-pig brain structures. Evidence for antigenic correlation between guinea-pig thymus and brain?

Similar to thymocytes in the thymic cortex, certain brain structures, such as nerve tracts and nerve cells of the Ammon's horn, show an affinity to rabbit erythrocytes (RRBC) which is exemplified by the adherence of RRBC to frozen brain sections. The experimental conditions of this adherence reaction are identical with that previously found with guinea-pig thymus and lymph node sections. From the results it may be concluded that receptor substances similar in nature on thymocytes and brain are responsible for this adherence phenomenon.

Aging↗
PubMed1975

[The diagnostic and prognostic significance of epithelial blood group isoantigens in carcinomas and polyps of the colon (author's transl)].

Blood group isoantigens (BG) were detected in carcinomas and polyps of the colon and were related to the degree of differentiation, the histologic type, the age of the patients and the histologic signs of malignancy. 1. BG were found in 60-70% of colon carcinomas regardless of their differentiation. 2. BG-positive carcinomas were less often surrounded by lymphocytes and plasma cells than BG-negative ones. 3. BG were present in colon polyps as mucusassociated and as membrane-associated antigens depending on the differentiation of the cells. Hence, BG-activity can be regarded as additional criterium to assess objectively the differentiation of the tumor cells in a polyp. 4. The percentage of BG-positive polyps increased with dedifferentiation. 5. Polyps with foci of malignant degeneration were consistently BG-positive. 6. Villous polyps contained BG more often than the adenomatous ones. 7. The results support the concept that both villous and adenomatous polyps of the colon are precancerous lesions.

Blood Group Antigens↗
PubMed1975

Hepatocellar hyalin (Mallory bodies) in long term griseofulvin-treated mice: a new experimental model for the study of hyalin formation.

Experimental studies on the significance and origin of hepatocellular "alcoholic" hyalin (Mallory bodies) are hampered by the lack of a suitable animal model. In the present paper, the experimental production of hepatocellular hyalin identical with human alcoholic hyalin both light and electron microscopically in long term griseofulvin-treated mice is described. Moreover, the results conclusively disprove the specificity of Mallory alcoholic hyalin for alcohol-induced liver cell damage.

Alcoholism↗