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Purpose: We investigated whether propidium iodide (PI) enhances DNA damaging effects of ionizing and non-ionizing radiation species (X-rays, alpha-, beta-, auger electron emission and light of various wavelengths, respectively). This biophysical experimental setting allowed us, furthermore, to investigate whether Cherenkov emission can be detected by photodynamic effects and increased DNA damage., Material and Methods: Conformation changes of plasmid DNA were detected and quantified by gelelectrophoresis and fluorescence imaging. Hydrogen peroxide, stannous dichloride, and dimethylsulfoxide were used as chemical modulators, Tc-99m, Re-188, Ra-223, and x-ray (32 kV and 200 kV) reflected radiotoxicity and light (λ = 254 nm, 366 nm and 530-575 nm) induced phototoxicity., Results: Radiotracers and x-rays induced dose dependent DNA damage. PI did not serve as radiosensitizer in radioisotopes, while a low effect was detected in X-rays. The phototoxicity was dependent on the wavelengths of light. Light with a wavelength range of 530-575 nm in combination with PI resulted in direct DNA damage. The yield of Cherenkov emission was far below the photon emission of light irradiation and not distinguishable from general radiotoxicity., Conclusions: PI binds to plasmid DNA, is not chemotoxic, and increases radiotoxicity only to minor extent. Phototoxicity and its stimulation by PI is dependent on the wavelength of the light. No kind of energy deposition was capable of inducing an Auger electron cascade. Furthermore, no increase in DNA damage induced by photodynamic effects from Cherenkov emission was detectable., Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt besteht., (© Georg Thieme Verlag KG Stuttgart · New York.)

27 microorganisms were tested for their ability to degrade extracellular purines as sole sources of carbon, nitrogen, and energy. Beside adenine, guanine, xanthine, hypoxanthine, and urate as free purine bases, this test included 5'-AMP, 5'-GMP, 5'-XMP, and 5'-IMP, as well as DNA and RNA as purine compounds. Generally, only a limited number of microbial species was capable of metabolizing the substances named above. Compared to the other species, Paracoccus denitrificans showed the greatest substrate spectrum, including the free bases as well as the mononucleotides. However, the polymers DNA and RNA were not degraded.

It is becoming increasingly clear that the nucleosome, the basic repeat unit of eukaryotic chromatin, is involved also in gene regulation. In particular, the study of inducible genes has shown that nucleosomes contribute to the repressed basal state, and that they can be rearranged in response to induction. The role of the nucleosomes in gene regulation and possible mechanisms for their structural modulation are discussed.

In 3 experimental groups 9 female Wistar rats (initial live weight 150 g) were fed either the control diet, the control diet supplemented with 5 mg clenbuterol or the combination of 5 mg clenbuterol and 500 mg propranolol per kg diet over a 12-day period. The N-balance was estimated over days 6 to 10 followed by a 15N-tracer experiment for determining the influence of the feed additives on characteristics of protein metabolism on day 12. All differences in the means were concluded to be significant for P < 0.05. Live weight gain and feed efficiency were improved by clenbuterol. The animals treated with clenbuterol had 18%-24% higher muscle weights whereas the combined treatment increased the muscle weights by 10%-16% only. The good correlation between the increase of muscle weights and the total protein content indicates that clenbuterol does not change the relation between protein- and water accumulation. Histological-histochemical investigations showed that the higher muscle weights were achieved through muscle fibre hypertrophy. The number of muscle fibres remained constant. Concerning the distribution of the fibre types, clenbuterol increased the proportion of FTG-fibres (white, fast-twitch, glycolytic) on the expense of the FTO-fibres (fast-twitch, oxidative). While the number of nuclei per muscle fibre did not change, the nucleus-cytoplasm relation decreased by 24%. Compared to the animals fed the control diet, the N-balance in the clenbuterol-treated group was increased by 41%. Feeding the combination of clenbuterol and propranolol resulted in an increase of 24% only. Clenbuterol increased the N-content of the carcass by 6% and reduced the carcass fat content by 30%. In the group fed clenbuterol and propranolol, the N-content of the carcass only tended to be increased and the influence on carcass fat reduction was only 16%. The stimulated N-deposition in the carcass of clenbuterol-treated rats was obtained, since the calculated protein degradation rates were more reduced than protein synthesis rates. In-vitro investigations of the muscle protein synthesis and -protease activities support these results. The clenbuterol-induced increase in muscle protein was accompanied by an inhibition of the Ca-dependent protease activity and an increase of muscle DNA- and RNA-content. The additional application of propranolol reduced these effects of clenbuterol again. Since propranolol partly prevented the effects of clenbuterol on protein metabolism it is suggested that not only the lipolytic but also protein anabolic effects are caused by the beta-adrenergic action of clenbuterol.

Monohalogenated methanes (methyl chloride, methyl bromide and methyl iodide) are mutagenic and carcinogenic. The possible mechanism of these effects, DNA methylation, was studied. DNA adducts from organs of F344 rats exposed to these chemicals were separated and identified with high performance liquid chromatography (HPLC) and gas-chromatography/mass-spectrometry (GC/MS). DNA adducts, 7-methylguanine (7-MeG) and O6-Methylguanine(0(6)-MeG), incorporation of 14C into de novo synthesis of nucleobases could be observed in enzymatic DNA hydrolysates by HPLC and determination of the radioactivity in the fractions. The formation of DNA adducts in the studied organs was only quantitatively different. The formation of O6-MeG was further proved by analysing the acidic hydrolysates using HPLC with non-radioactive O6-MeG as internal standard. 7-MeG and 3-MeA were identified with GC/MS analysis.

In aging the transformation, nuclei binding, and recycling of glucocorticoid receptor complexes (GRC) seem to be retarded or disturbed, as shown in the rat liver after stress and in an in vitro-system. Reasons of the retarded in vitro-transformation and DNA-binding could be changed properties of the receptor protein or of cytosolic modulators, in which the tested heat-stable factor f is not responsible for the aging changes. The observed aging differences, when studying the nuclei binding after Ca2+ addition, result in the question, to what extent phosphorylation/dephosphorylation processes play a role in transformation and nuclei binding of GRC.

Experiments were undertaken to test for the stable integration of defined prokaryotic genes in mammalian cells. Thus lambda dvgal 88 plasmid DNA were transferred together with the herpes simplex virus type 1 thymidine kinase (TK) gene as a selectable marker to TK- mouse cells. DNA restriction and hybridization analysis of TK+ mouse cell clone DNA revealed (i) the presence of prokaryotic lambda dvgal 88 sequences in the mouse DNA; (ii) the stable integration of the prokaryotic DNA in mouse cell DNA under selective conditions; and (iii) the presence of lambda dvgal fragments in several copies per cell and their integration at different loci within the cell DNA.

We investigated the binding of azure B to DNA (calf thymus) over a wide range of concentrations of the dye (CF) and the nucleic acid (CN) using absorption spectroscopy [CF and CN represent the total concentrations of the ye (F) and the mononucleotide units (N) of the DNA, respectively]. The binding isotherms of the dye to DNA in aqueous solutions were determined. In addition, we analysed the composition of insoluble DNA/azure B precipitates that are formed in presence of an excess of azure B. These precipitates are of particular interest, because Giemsa staining is usually performed using high dye concentrations. Azure B easily forms dimers in aqueous solutions. When determining the binding isotherms, the equilibrium between free monomers and dimers must be taken into account. Therefore, we determined the dimerisation constant (Kd) of azure B from the concentration dependency of its absorption spectra in water at the standard temperature T = 298 K (25 degrees C), Kd = 6.5 X 10(3) M-1 (experimental conditions: tris buffer, pH 7.2; concentration of Na ions, CNa = 0.002 M). As the CNa value increases, the dimerisation constant rises rapidly. When the azure B concentration is very low and there is an excess of DNA, ordinary Scatchard and Langmuir isotherms are observed. Monomer dye cations are bound to DNA, these cations being in equilibrium with free monomers in the solution. In order to obtain the Scatchard binding constant (Ks) and the binding parameter (n) spectroscopically, it is necessary to determine the extinction coefficient (epsilon Fb) of the monomer bound (b) dye molecules (F) at one analytical wave number (upsilon a). The three constants can be determined simultaneously using an iterative technique that combines Scatchard isotherms and the Benesi-Hildebrand extrapolation, CN----infinity. We obtained Ks = 1.8 X 10(5) M-1 and n = 0.18 (25 degrees C; tris buffer, pH 7.2; CNa = 0.002 M). At very low dye (CF) and competitor (CNa) concentrations, only 18% of the anionic binding sites of the DNA are capable of binding the dye cations. With increasing CNa values the concentration of bound azure B cations decreases rapidly. The Na cations displace the bound dye cations and act as a competitor. The Ks value also greatly depends on the competitor concentration (CNa).(ABSTRACT TRUNCATED AT 400 WORDS)

Addition of cortisol (hydrocortisone; 1.4 X 10(-7) M) to the culture medium (BME with non-essential amino acids and 10% fetal calf serum) of human fibroblasts resulted in increased proliferative activity--in regard to cell number and incorporation rates of [3H]-thymidine into DNA and [14C]-leucine into protein--and in an increased saturation density. Glycosaminoglycan (GAG) synthesis rates (as measured by incorporation of [14C]-glucosamine or [35S]-sulfate) of the various GAG types secreted into the culture medium (hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate) were evenly inhibited by ca. 25% in the case of cortisol-treated Phase-II cultures. The dose-effect relationship revealed a median effective cortisol dose of ca. 0.01 microM for Phase-II cultures. Phase-III ("senescent") cultures revealed an elevated sensitivity as well in regard to cortisol concentration as to the extent of the inhibitory effect. Contrary to the medium GAGs, the pattern of the cell-bound GAGs was changed by cortisol (1.4 X 10(-7) M), with an increase of hyaluronic acid synthesis and a decrease of the sulfated GAGs. This cell-bound hyaluronic acid was predominantly removable by trypsin-treatment and therefore regarded to be localized at the cell surface or pericellularly. Also, following long-term cultivation (ca. 15 population-doublings) in the presence of cortisol, the synthesis of cell-bound hyaluronic acid was stimulated. Since cellular hyaluronic acid decreases during senescence of WI-38 cultures (Sluke et al., 1981), the cortisol effect in regard to GAG synthesis is in line with a "counter-aging" influence.(ABSTRACT TRUNCATED AT 250 WORDS)

New aspects on the mechanism of action of known environmental carcinogens are described. These compounds are not active as such, but are bioactivated in the mammalian metabolism via chemically reactive intermediates to electrophilic reactants, forming with information-bearing biopolymeres covalent bonds. This change in the genetic code is in agreement with the mutation hypothesis of carcinogenesis. Aflatoxin B1, N-nitroso compounds and benzo(a)pyrene are taken as examples. "Threshold levels", e.g. no-effect-levels derived from animal experiments with all their inherent limitations, are compared with data from human exposure to benzo(a)pyren, aflatoxine, N-nitroso compounds and vinyl chloride. The difficulties of such risk evaluations are discussed.

The Romanowsky-Giemsa staining (RG staining) has been studied by means of microspectrophotometry using various staining conditions. As cell material we employed in our model experiments mouse fibroblasts, LM cells. They show a distinct Romanowsky-Giemsa staining pattern. The RG staining was performed with the chemical pure dye stuffs azure B and eosin Y. In addition we stained the cells separately with azure B or eosin Y. Staining parameters were pH value, dye concentration, staining time etc. Besides normal LM cells we also studied cells after RNA or DNA digestion. The spectra of the various cell species were measured with a self constructed microspectrophotometer by photon counting technique. The optical ray pass and the diagramm of electronics are briefly discussed. The nucleus of RG stained LM cells, pH congruent to 7, is purple, the cytoplasm blue. After DNA or RNA digestion the purple respectively blue coloration in the nucleus or the cytoplasm completely disappeares. Therefore DNA and RNA are the preferentially stained biological substrates. In the spectrum of RG stained nuclei, pH congruent to 7, three absorption bands are distinguishable: They are A1 (15400 cm-1, 649 nm), A2 (16800 cm-1, 595 nm) the absorption bands of DNA-bound monomers and dimers of azure B and RB (18100 cm-1, 552 nm) the distinct intense Romanowsky band. Our extensive experimental material shows clearly that RB is produced by a complex of DNA, higher polymers of azure B (degree of association p greater than 2) and eosin Y. The complex is primarily held together by electrostatic interaction: inding of polymer azure B cations to the polyanion DNA generates positively charged binding sites in the DNA-azure B complex which are subsequently occupied by eosin Y anions. It can be spectroscopically shown that the electronic states of the azure B polymers and the attached eosin Y interact. By this interaction the absorption of eosin Y is red shifted and of the azure B polymers blue shifted. The absorption bands of both molecular species overlap and generate the Romanowsky band. Its strong maximum at 18100 cm-1 is due to the eosin Y part of the DNA-azure B-eosin Y complex. The discussed red shift of the eosin Y absorption is the main reason for the purple coloration of RG stained nuclei. Using a special technique it was possible to prepare an artificial DNA-azure B-eosin Y complex with calf thymus DNA as a model nucleic acid and the two dye stuffs azure B and eosin Y.(ABSTRACT TRUNCATED AT 400 WORDS)

The mechanism of carcinogenesis is not yet understood. There is increasing evidence justifying the assumption that an unifying concept of carcinogenesis should be possible at the molecular level. New insights into the molecular mechanism of carcinogenesis were mainly obtained in studies on both chemical and viral carcinogenesis. In the present paper, selected results of these studies are reviewed. It is concluded that the interaction of different carcinogenic agents with the cellular DNA results in alterations of DNA. Only some of these alterations, however, seem to be relevant to carcinogenesis. Alterations of DNA can be caused by reaction of electrophilic agents with DNA constituents, by increased infidelity of DNA replication, by integration of viral genomes or by recombination events involving integrated proviruses.

Sperm populations from 65 patients with fertility disturbances were investigated by pulse cytophotometry. The determination of the cell number showed 21 normospermias, 14 hypospermias, 19 oligospermias, 9 polyspermias, and 2 cryptospermias. As controls were used sperm samples of fertile men. The pulse cytophotometric DNA histograms were made full use quantitative and qualitative. The results of these investigations represent a methodical contribution for the diagnosis of fertility disturbances of men.

The influence of sodium fluoride therapy on semiconservative DNA-synthesis and DNA-excision repair was investigated in lymphocytes of the peripheral blood of 6 patients with osteoporosis. The daily dose of sodium fluoride was 25 mg in the first week, and subsequent 50 mg during a period of 15 to 37 weeks. No significant effect on the tested parameters was found in 5 subjects. One patient showed significantly inhibited DNA-repair in the lymphocytes up to the ninth week, but during subsequent therapy normal values were obtained in this patient also. In conclusion sodium fluoride seems to have no effect on DNA-metabolism in lymphocytes of patients with osteoporosis.

Dry mass of cell nuclei was studied in 34 explant cultures of normal epithelium (8), persisting dysplasias (7), Ca in situ (9) and cervical carcinomas (10) by interference microscopic determination. Dysplasias, Ca in situ and carcinomas can be distinguished from normal epithelium by a significantly higher dry mass value. Such a difference does not exist between dysplasia and Ca in situ. The percentage of dispersion of the dry mass is significantly higher in carcinomas than in all other examined tissues. The biological meaning of these results is discussed. The interference microscopic determination of dry mass of the cell nuclei is a suitable parameter for the characterization of properties of cervical carcinomas and their intraepithelial prestages cultivated in vitro.

Glass microspheres were used for a diffuse pulmonary microembolisation, as a modell for shock lung. Microembolisation is regarded as an important factor in pathogenesis of shock lung. The capacity of lung for lecithin synthesis was measured with palmitat-1-14-C incorporation. The phospholipid content and the composition of the fatty acids of lecithin were investigated. From the results it was possible, that the surfactant system may alterated by the vascular blocking. The dates supporting the importance of microembolisation in pathogenesis of shock lung.

Syrian hamster kidney cultures of line 14-1b were synchronized by excess of thymidine. Thereafter in the phase of DNA synthesis cell cultures were exposed to extract and fractions of city smog, derived from a polluted area at the river Rhine and Ruhr. Using impulscytophotometry and estimation of mitotic frequency cell cycle analyses were conducted on synchronized exposed and control cultures. The total extract obtained by methanol treatment of city smog was further fractionated by organic solvents leading to fractions of cyclohexane, polyaromates and propanol. Cell cycle progression of synchronized cultures was inhibited in a dose dependent manner by increasing concentration of city smog extract and its fractions. This inhibition led to a prolongation of DNA synthetic phase and to an accumulation of cells in G2(+ M)-phase. The total cell cycle showed a prolongation of 3-5 h. The strongest effect was induced by the total extract. We have to emphasize that already amounts of city smog which were found in air volumes of 2-5 m3 exerted strong effects. With a declining sequence of toxicity followed the fractions of cyclohexane, propanol and of polyaromates. Our results show, that samples of city smog from polluted areas contain substances which induce heavy alterations in cell cycle progression of mammalian cells in vitro. These highly effective toxic substances are dangerous for human health, especially after a long-time exposition.

The alkylation of chromatin constituents (DNA, histones and non-histones) in liver cell nuclei was investigated at various times after intraperitoneal injection of rats with 3H-cyclophosphamid. The highest alkylation was found in the DNA, the lowest in the histones; the euchromatic portions were alkylated several times higher compared to those of the heterochromatin. The eventual elimination of 3H-activity with time indicates that cyclophosphamid leads to repair processes in the DNA, this conclusion being supported by other experimental observations. In some of the 16 subfractions of the nonhistone proteins, alkylated portions are apparantly eliminated by normal protein turnover; however, in other nonhistones this elimination is inhibited, whereby in one subfraction it seems to be accelerated. The results of analog experiments with 14C-tryptophan as a precursor for nonhistone protein synthesis serve as a reference for this. In supplementary in-vitro model experiments using triaziquon as an alkylating agent indications for DNA-Protein-cross-links in chromatin could be obtained by the technique of X-ray low angle scattering, and according to sedimentation behaviour.

In 8 patients with rheumatoid arthritis the influence of intra-articular (i.a.) injections of prednisolone-21 -acetate on the DNA metabolism of synovial fluid cells was examined. Two hours after an i.a. injection of 25 mg prednisolone acetate a significant decrease of the sedimentation of nucleoids was found. After a 60 minute incubation the sedimentation of nucleoids became normal. An inhibition of DNA repair by 25 mg prednisolone acetate could not be demonstrated.

Prediction tests were performed in vitro an organ cultures of different solid human tumors. The effectivity of the antineoplastic drugs was determined by means of the remained 3H-thymidine incorporation into DNA. DNA control values of different tumors (without drug) varying in a very high degree are analyzed and correspond to drug response rate in vitro. The correlation between results of sensitivity tests in vitro and therapeutic effectivity in vivo is discussed.

Research in molecular neurobiology has recently entered a new phase of rapid development as a result of the application of the techniques of molecular genetics. This is illustrated by recent work on the electric ray (Torpedo marmorata and T. californica), whose electric organ is a rich source of cholinergic synapses. Other examples from recent literature of the application of the recombinant DNA technique to the mammalian central nervous system are given and possible future developments are discussed.

Fumaric acid may not be regarded as an antipsoriatic drug. Beneficial effects on psoriatic lesions may be explained by secondary changes such as the acidification of gastric juice in cases of anacidity or hypacidity . Monoethylfumarate exerts true antipsoriatic activities but is by far too toxic for clinical use. Experimental investigations have confirmed an inhibitory action of the above-mentioned fumarate on nucleic acid synthesis and protein synthesis of PHA-stimulated human lymphocytes.

Twenty two patients with cystic fibrosis, 7 to 17 years of age, underwent each two bronchoscopic investigations, the second six months later than the first, in general anaesthesia with muscle relaxation using a ventilation bronchoscope and taking small biopsies of the mucous membrane. The degree of reddening, swelling of the mucous membranes and hypersecretion was in some agreement with the intensity of the cellular infiltration and the production of pus (microscopic investigation). Secondary ultrastructural changes were detected in nearly all children: e.g. cellular oedema, protrusion of cells and fusion of cilia, microtubular abnormalities of the cilia, lesions of the apical cell membranes and increased number of goblet cells. These changes of ultrastructure were not correlated to the mentioned signs of inflammation.

After intraperitoneal application of 14C-orotic acid the tracer distribution and the labelling of total RNA in different organs of two groups of Wistar rats (5 and 22,5 months old) were represented. After 60 min 2/3 of tracer were found in liver and kidney. The uptake by liver of old animals is decreased significantly. The interactions between the tracer distribution in the organism, the time related uptake by the organs, the organ function (influenced by methimazol) and the specific activity of RNA were represented. From the results the conclusion is drawn that the comparison of the specific activities of total RNA alone--especially in comparison of young with old animals--is not sufficient for the examination of RNA synthesis.

Feulgen-cytophotometric examinations of 61 keratoacanthomas of the skin have revealed 3 types differing from each other in their DNA distribution. Keratoacanthomas type I are characterized by a diploid DNA distribution--comparable to epidermis cells. An increasing average DNA content (x) and mean distribution (Sx) compared with diploid cells are, however, conspicuous. Keratoacanthomas type II display DNA peaks in the triploid phase and increasing x and Sx. Keratoacanthomas type III show DNA tumor stem lines in the hypotetraploid, tetraploid and hypertetraploid phases, with x and Sx further increasing. The occurrence of two tumor cell populations of aneuploid localization is noteworthy in part of the keratoacanthomas. Transitional types among the tumors mentioned above are possible. Only type I does not allow cytophotometric demarcation of epidermis cells or tissue lymphocytes based on statistical analysis. The three types of keratoacanthomas can be significantly defined against each other. These cytophotometric findings explain the occurrence of clinical variations of keratoacanthomas with tumor ulceration, increased growth and recidivity. As a rule total excision and careful histological examinations are advisable. The occurrence of paraneoplastic keratoacanthomas and carcinomata disguished as keratoacanthomas is mentioned. Spontaneous healing should not be waited for despite the possible occurrence of benign keratoacanthomas.

DNase deficient mutants of Proteus mirabilis selected for reduced toluene induced DNA degradation were isolated. Their defect in DNA degradation was shown not only after treatment by toluene but also in crude extracts after cell disintegration by ultrasonic and in untreated starved cultures. The degradation mutants behave just as the wild type with respect ot their in vivo functions proffed. The results inidcate that the affected DNase does not have an essential function in vivo but acts in postmortem DNA degradation. Probably the DNase in question concerns the endonuclease I of P. mirabilis described by Goebel and Helinski (1971 a, b).

Autoradiographic studies using tritiated thymidine as a precursor of DNA synthesis show that the process of wound healing of the corneal endothelium in both rhesus monkeys and rabbits following scarification and cryocoagulation takes place for the most part by means of cell proliferation. After injection of tritiated thymidine into the anterior chamber immediately prior to sacrifice, autoradiographically labeled flat mounts and cross-section preparations of the corneas of 7 rhesus monkeys and 14 rabbits were examined at lesion ages ranging from 4 hours to 10 days. In the monkeys scarcely 10% of the endothelial cells in the areas of the corneal lesions or at their borders were in the S-phase in the autoradiographically labeled flat mounts 24 hours to 3 days after injury, whereas up to 39% of those in the rabbits were seen to be so after 18 hours. In the monkeys one could discern mitoses between the 2nd and 5th days, and amitoses (binuclear cells) were found in 1-day and 3-day animals. In rabbits numerous mitoses could be discerned between the 1st and 5st days, but no multinuclear cells were seen. Healing of the corneal endothelium in the monkeys occurred some-what later and was less pronounced than in the rabbits.

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.

The trophoblast giant cells of the mouse placenta are mitotically inactive. Nucleolar RNA synthesis is apparently at a standstill. The high nuclear DNA contents of these cells shown by 3H-thymidine marking is conceived by us to be a synthesis of metabolic nuclear DNA. Thus protein synthesis in trophoblast giant cells has been taken over by a metabolic DNA.

In this paper the DNA content as a quantitative parameter of the cell content was analyzed on selected rat organs. Aging changes in parenchymatous and connective tissue (= mesenchymal) organs were examined. Further, some pilot studies on experimental animal models of human diseases (experimental shock and liver fibrosis) and their therapy were carried out. In these simulations of human diseases only some preliminary indications about changes in cell or DNA content, resp., of the various organs could be obtained. The results show that these pilot studies justify intensified continuation (in larger series).

The authors investigated in 60 cases the healing process after gingivectomy. The investigation was performed by means of fluorescence microscopy, the presence of nucleic acids (RNA, DNA) and of polysaccharides in the cells being demonstrated. The cytochemical RNA reactions were the most sensitive indicator of wound healing after gingivectomy. Solcoseryl gel accelerated the epithelization of the gingival wound after the surgical intervention, which shortens the period of recuperation.

A method is described for the administration of suspended material into the rat lung. The rat is narcotized by CO2/air, the trachea is punctured and the suspension is sucked into the lung by the inhaled air (pertracheal administration, p. t. a.). BaP administered by this method is eliminated from the lung rapidly, while metabolites persist for a longer period. The radioactivity detected in the blood can be attributed predominantly to metabolites, a small fraction is unmetabolized benzo(a)pyrene. The activity of benzo(a)pyrene hydroxylase is induced in the lung after p. t. a. of extracts from airborne particulate matter. The activity increases depending on the dose until a plateau of activity is reached at high doses. Pertracheally administered BaP is bound to DNA of the lung. Pretreatment with extracts p.t.a. enhances the binding. After enzymatic digestion of DNA BaP-nucleoside adducts are detected by HPLC. According to data published in the literature to adducts are supposed to be derived from BaP-phenols and BaP-diolepoxides. It is concluded tht the components of airborne particulates can modify the activity of metabolizing enzymes and increase the rate of formation of adducts in the lung in vivo.

The resistance of nuclear chromatin against acid hydrolysis with hydrochloric acid was studied in cell nuclei of different organs from young and old rats and after application of cortisol. Suspensions of cell nuclei from liver, spleen, kidney, heart muscle and mucosa from small intestine were stained with ethidium bromide without and after hydrolysis. The relative fluorescence intensity (FI) of every pair was measured by flow through cytophotometry. Always the FI of the diploid peaks of the hydrolysed samples was diminished. The resistance against hydrolysis was greater in old animals than in young. After application of cortisol in vivo in all organs, except in the liver, the resistance against hydrolysis was increased. Only the nuclei of liver from old animals showed a diminution of resistance after cortisol. It is assumed, that the greater resistance in age is due to the diminished functional ability of the nuclear chromatin. In the most organs, the inhibitory activity of cortisol to the cell metabolism is known, only in the liver cell it stimulates the synthesis of RNA and protein. This is in agreement with our findings.