Dose-dependent cytokinetic changes following 1-beta-D-arabinofuranosylcytosine and hydroxyurea in L1210 and S-180 in vivo.

DNA synthesis inhibition and recovery in L1210 and S-180 ascites tumors following 1-beta-D-arabinofuranosylcytosine (Ara-C) and hydroxyurea (HU) were measured autoradiographically as a basis for optimizing drug schedules. Tumor bearing mice, 10(6) cells day 0, were treated on day 4 with 20, 200 or 2000 mg/kg Ara-C or 50, 300 or 1800 mg/kg HU. At various intervals following drug, [3H]thymidine was administered i.p. and mice were killed 1 hr later. Tumor cells were analyzed for labeling index (LI) and grain count (GC) to determine the percentage of cells in S phase and the distribution of DNA synthesis rates among the labeled cells, respectively. Following each dose of HU, DNA synthesis was inhibited completely. Recovery of LI was rapid and approached control values by 6 hr. Following each dose of Ara-C, DNA synthesis was inhibited completely for at least 6 hr. Recovery of LI was first noted 6 hr following 20 mg/kg Ara-C and 9 hr following 200 mg/kg. Following both doses the LI reached 100% of the control value by 26 hr. GC analysis indicated that following Ara-C treatment, DNA synthesis was reinitiated first with cells with low GC from 6 to 12 hr followed by cells with increasing GC from 12 to 20 hr. The labeling intensity reached control values by 20 hr and an 'overshoot' occurred by 26 hr. These data suggest that the recovery of DNA synthesis rate is a gradual process. Survival data for mice receiving two doses of Ara-C indicated that the optimal interval for retreatment following the lower dose of Ara-C occurred by 6 hr as compared to 12--16 hr for the higher dose. These times coincided in both instances with recovery of LI to 33--50% of control values. Early recovery of LI may be the best method currently available for estimating the optimal time for retreatment with an S phase specific drug.     

Parental adenovirus type 2 genomes recovered early or late in infection possess terminal proteins.

At both early (3 h) and late (18 h) times after infection of KB cells with adenovirus 2, more than 90% of parental nuclear viral genomes exist as complexes which contain terminally linked proteins. Density shift experiments employing 5-bromo-2'-deoxyuridine indicate that these parental DNA molecules remain complexed with terminal proteins after DNA replication. The persistent linkage of proteins to the termini of intranuclear viral DNA suggests that these proteins have an essential role in adenovirus replication.     

Effect of chlorine dioxide gas on fungi and mycotoxins associated with sick building syndrome

The growth of indoor molds and their resulting products (e.g., spores and mycotoxins) can present health hazards for human beings. The efficacy of chlorine dioxide gas as a fumigation treatment for inactivating sick building syndrome-related fungi and their mycotoxins was evaluated. Filter papers (15 per organism) featuring growth of Stachybotrys chartarum, Chaetomium globosum, Penicillium chrysogenum, and Cladosporium cladosporioides were placed in gas chambers containing chlorine dioxide gas at either 500 or 1,000 ppm for 24 h. C. globosum was exposed to the gas both as colonies and as ascospores without asci and perithecia. After treatment, all organisms were tested for colony growth using an agar plating technique. Colonies of S. chartarum were also tested for toxicity using a yeast toxicity assay with a high specificity for trichothecene mycotoxins. Results showed that chlorine dioxide gas at both concentrations completely inactivated all organisms except for C. globosum colonies which were inactivated an average of 89%. More than 99% of ascospores of C. globosum were nonculturable. For all ascospore counts, mean test readings were lower than the controls (P < 0.001), indicating that some ascospores may also have been destroyed. Colonies of S. chartarum were still toxic after treatment. These data show that chlorine dioxide gas can be effective to a degree as a fumigant for the inactivation of certain fungal colonies, that the perithecia of C. globosum can play a slightly protective role for the ascospores and that S. chartarum, while affected by the fumigation treatment, still remains toxic.     

Protein Translation Inhibition by Stachybotrys chartarum Conidia with and without the Mycotoxin Containing Polysaccharide Matrix

Recent studies have correlated the presence of Stachybotrys chartarum in structures with SBS. S. chartarum produces mycotoxins that are thought to produce some of the symptoms reported in sick-building syndrome (SBS). The conidia (spores) produced by Stachybotrys species are not commonly found in the air of buildings that have been found to contain significant interior growth of this organism. This could be due in part to the large size of the Stachybotrys spores, or the organism growing in hidden areas such as wall cavities. However, individuals in buildings with significant Stachybotrys growth frequently display symptoms that may be attributed to exposure to the organism's mycotoxins. In addition, Stachybotrys colonies produce a "slime" or polysaccharide (carbohydrate) matrix that coats the hyphae and the spores. The intent of this project was to determine whether the carbohydrate matrix and the mycotoxins embedded in it could be removed from the spores by repeated washings with either aqueous or organic solvents. The results demonstrated that the process of spore washing removed compounds that were toxic in a protein translation assay as compared to spores that were washed with an organic solution, however a correlation between carbohydrate removal during the washing process and the removal of mycotoxins from the spore surface was not observed. These data demonstrated that mycotoxins are not likely to be found exclusively in the carbohydrate matrix of the spores. Therefore, mycotoxin removal from the spore surface can occur without significant loss of polysaccharide. We also showed that toxic substances may be removed from the spore surface with an aqueous solution. These results suggest that satratoxins are soluble in aqueous solutions without being bound to water-soluble moieties, such as the carbohydrate slime matrix.     

Herpes simplex virus type 1 enters human epidermal keratinocytes, but not neurons, via a pH-dependent endocytic pathway

Herpes simplex virus (HSV) enters some laboratory cell lines via a pH-dependent, endocytic mechanism. We investigated whether this entry pathway is used in human cell types relevant to pathogenesis. Three different classes of lysosomotropic agents, which raise endosomal pH, blocked HSV entry into primary and transformed human keratinocytes, but not into human neurons or neuroblastoma lines. In keratinocytes, incoming HSV particles colocalized with markers of endocytic uptake. Treatment with the isoflavone genistein, an inhibitor of protein tyrosine kinases, reduced the delivery of incoming viral particles to the nuclear periphery and virus-induced gene expression in keratinocytes but not neurons. Moreover, in keratinocyte monolayer islets, HSV infected both the inner and outer cells in a genistein-sensitive manner, suggesting viral endocytosis from both basolateral and apical plasma membrane surfaces. Together, the results indicate that HSV enters human epidermal keratinocytes, but not neurons, by a low-pH, endocytic pathway that is dependent on host tyrosine phosphorylation. Thus, HSV utilizes fundamentally different cellular entry pathways to infect important target cell populations.     

Rapid Cytochemical Identification of Phagosomes in Various Tissues of the Rat and their Differentiation from Mitochondria by the Peroxidase Method

1. Granules characterized by their ability to segregate foreign proteins (phagosomes) were identified in the cells of many rat organs after intravenous administration of horseradish peroxidase, by using the conventional test with benzidine for the histochemical detection of peroxidase. The largest numbers of phagosomes were identified in kidney and liver. Considerable numbers were observed cytochemically in pancreas, prostate, epididymis, thymus, spleen, bone marrow, small intestine, heart, pituitary, and mouse mammary carcinoma. 2. The variation in size of the phagosomes ranging from the limit of microscopic visibility up to 5 µ diameter, previously described for kidney, was also observed to occur in many of the other organs. The average size of the phagosomes in different organs was also different, the phagosomes of the liver, for example being on the average smaller than those of the kidney, pancreas, and prostate. 3. In squash preparations of kidney and liver, the phagosomes appeared often in curved rows following the course of the cell membranes of epithelial cells. In several other organs, they appeared aggregated in cells located in the vicinity of blood or lymphatic vessels or capillaries. 4. After injection of peroxidase directly into the brain of a rabbit, a striking concentration of peroxidase was observed in phagosomes of endothelial cells of capillaries and vessels, surrounding the site of injection. It was suggested that this localization may offer an explanation for the so called blood-brain barrier. 5. The cytochemical peroxidase method was applied to smears of isolated fractions of kidney and liver. Only the isolated phagosomes, but not the isolated nuclei, mitochondria, and microsomes, reacted with benzidine after administration of peroxidase. The contamination of conventionally prepared nuclear, mitochondrial, and microsomal fractions of kidney and liver with phagosomes of different sizes was observed. By correlating the cytochemical peroxidase test of smears of isolated fractions with the colorimetric determination of peroxidase, acid phosphatase, and cytochrome oxidase in the same fractions, the differentiation of the phagosomes from mitochondria and other cell granules was facilitated. 6. The marked difference in the osmotic properties of phagosomes and mitochondria, detectable after treatment with 70 per cent alcohol, and the difference in their affinities towards basic fuchsin, made it possible to differentiate the phagosomes from the mitochondria. It was found by this simple procedure that kidney cells of normal rats contain a large number of phagosomes ranging in size from 0.5 to 3 µ, whereas liver cells of normal rats contain relatively few phagosomes of this size but many smaller ones (0.2 to 0.5 µ diameter). These increased in size after treatment of the rats with horseradish peroxidase.     

Putative projection of phrenic afferents to the limbic cortex in humans studied with cerebral-evoked potentials

Straus, Christian, Marc Zelter, Jean-Philippe Derenne,Bernard Pidoux, Jean-Claude Willer, and Thomas Similowski.Putative projection of phrenic afferents to the limbic cortex inhumans studied with cerebral-evoked potentials. J. Appl. Physiol. 82(2): 480-490, 1997.Respiratorysensations may rely in part on cortical integration of respiratoryafferent information. In an attempt to study such projections, werecorded evoked potentials at scalp and cervical sites in 10 normalvolunteers undergoing transcutaneous phrenic stimulation (0.1-ms squarepulses, intensity liminal for diaphragmatic activation, series of 600 shocks at 2 Hz). A negative cerebral component of peak latency(12.79 ± 0.54 ms; N13) was constant, and a negativespinal component (7.09 ± 1.04 ms; N7) could also be recorded, allresults being reproducible over time. Monitoring of cardiac frequency,skin anesthesia, and stimulation adjacent to the phrenic nerve made thephrenic origin of N7 and N13 the foremost hypothesis. Increasingstimulation frequency and comparison with median nerve stimulationprovided arguments for the neural nature of the signals and theircerebral origin. Recordings from intracerebral electrodes in a patientshowed a polarity reversal of the evoked potentials at the level of the cingulate gyrus. In conclusion, phrenic stimulation could allow one tostudy projections of phrenic afferents to the central nervous system inhumans. Their exact site and physiological meaning remain to beclarified.

     

Comparison of magnetic and electrical phrenic nerve stimulation in assessment of phrenic nerve conduction time

Similowski, Thomas, Selma Mehiri, Alexandre Duguet,Valérie Attali, Christian Straus, and Jean-Philippe Derenne.Comparison of magnetic and electrical phrenic nerve stimulation inassessment of phrenic nerve conduction time. J. Appl.Physiol. 82(4): 1190-1199, 1997.Cervicalmagnetic stimulation (CMS), a nonvolitional test of diaphragm function,is an easy means for measuring the latency of the diaphragm motorresponse to phrenic nerve stimulation, namely, phrenic nerve conductiontime (PNCT). In this application, CMS has some practical advantagesover electrical stimulation of the phrenic nerve in the neck (ES).Although normal ES-PNCTs have been consistently reported between7 and 8 ms, data are less homogeneous for CMS-PNCTs, with some reportssuggesting lower values. This study systematically compares ES-and CMS-PNCTs for the same subjects. Surface recordings ofdiaphragmatic electromyographic activity were obtained for sevenhealthy volunteers during ES and CMS of varying intensities. Onaverage, ES-PNCTs amounted to 6.41 ± 0.84 ms and were littleinfluenced by stimulation intensity. With CMS, PNCTs were significantlylower (average difference 1.05 ms), showing a marked increase as CMSintensity lessened. ES and CMS values became comparable for a CMSintensity 65% of the maximal possible intensity of 2.5 Tesla. Thesefindings may be the result of phrenic nerve depolarization occurringmore distally than expected with CMS, which may have clinicalimplications regarding the diagnosis and follow-up of phrenic nervelesions.

     

Die Wirkung negativer Luftionisation auf die Länge des Oestruszyklus bei Ratten

Zusammenfassung Bei 20 ausgewachsenen weiblichen Ratten mit verlängertem und unregelmässigem Oestruszyklus (13 ± 10 Tage) wurde nach 25 Tagen einer täglichen einstündigen Behandlung mit negativen Luftionen die Zykluslänge auf 6 ± 3 Tage reduziert.

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The irregular and prolonged oestrus cycle of 13 ± 10 days in 20 adult female rats was reduced to 6 ± 3 days after an 1-hr daily treatment with small negative ions for a period of 25 days.

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Resume 20 femelles de rats dont le cycle menstruel était irrégulier et prolongé (13 ± 10 jours) ont été exposées durant 25 jours à de l'air enrichi de petits ions négatifs et cela à raison de 1 heure par jour. Leur cycle en a été réduit à 6 ± 3 jours.

     

MAIZE ENDOSPERM TISSUE GROWN IN VITRO III. DEVELOPMENT OF A SYNTHETIC MEDIUM

Straus , Jacob . (U. Oregon, Eugene.) Maize endosperm tissue grown in vitro. III. Development of a synthetic medium. Amer. Jour. Bot. 47(8) : 641–647. Illus. 1960.—The development of a synthetic medium for the growth of endosperm tissue cultures derived from the maize variety, ‘Black Mexican Sweet,‘ is described. Previously, these tissues required yeast extract, casein hydrolyzate, or tomato juice in the medium in order to grow. The growth-supporting activity of these complexes could be attributed to their organic nitrogen content. The effect of juice extracted from fresh tomatoes is enhanced by autoclaving under acid conditions. Presumably this treatment increases the free amino acid content of the tomato juice. One-dimensional paper chromatograms of tomato juice autoclaved under acid conditions indicated the presence of a large amount of free amino acids. Addition of 1.5 × 10^–2 M asparagine to the basal mineral-sugar-vitamin medium (White's medium plus Nitsch's trace-element solution) resulted in better growth than that supported by yeast extract, tomato juice, or casein hydrolyzate. Arginine was ineffective. Glutamine, glutamic acid and aspartic acid (all at 1.5 × 10^–2 M) supported appreciable growth of the tissue but none of them were nearly so good as asparagine in this respect. Thus, a medium containing minerals, sugar, vitamins, and asparagine is capable of supporting excellent growth of maize endosperm tissue cultures.