Uptake, stimulated release and metabolism of (1-14C)-eicosapentaenoic acid in a perfused organ of the rabbit.

The isolated rabbit ear was prelabeled by perfusion with (1-14C)-eicosapentaenoic acid (EPA). Uptake and distribution in lipids, basal release and, in particular, stimulated release and metabolism was studied. In a series of experiments a comparison with results obtained by labeling the perfused organ with (1-14C)-arachidonic acid (AA) was made. Approximately 80% of the perfused labeled EPA was incorporated into the tissue. The main peak (74% of the incorporated radioactivity) was found in the phospholipids. Following incorporation of labeled EPA, basal release of EPA but ot of trienoic prostaglandins (PGs) could be observed. Bolus injection of bradykinin (3 micrograms) and the calcium-ionophore A23187 (10 micrograms) led to an immediate increased release of radioactivity in the effluent which declined within 10--20 min. Analysis of the extracted effluent by thin layer chromatography (TLC) showed that only the release of EPA and of radioactivity at the Rf-value of 12-L-hydroxy-5,8,10,14-eicosatetraenoic acid (HETE) was increased following stimulation by bradykinin and A23187. No labeled trienoic PGs could be detected. Upon injection of A23187 in the presence of indomethacin (3 micrograms/ml) there was no reduction of any peak of radioactivity on the TLC-plate, indicating that no cyclooxygenase product of EPA was generated. The extremely high dose of 10 micrograms bradykinin or 50 micrograms A23187 led to a small release of labeled PGI3 (A23187) and to a somewhat higher release of labeled PGE3 (bradykinin, A23187). In some experiments release and metabolism of labeled EPA were compared with those of labeled AA.(ABSTRACT TRUNCATED AT 250 WORDS)

[Distribution of 14C-pipemidic acid in the guinea pig ear (author's transl)].

Macroautoradiographic studies on distribution of 14C-pipemidic acid in the guinea pig ear were performed after administration of the drug to provide its disposition for its application in the otolaryngological field. Petrosal bone, cochlea and auditory ossicles contained extremely low levels of 14C-pepemidic acid; blood, mucous tissues of tympanic cavity and tympanic membrane, low levels; tissues of external ear, moderate levels; and outer surface tissues of petrosal bone possibly including periosteum, significant levels. These otological tissue distributions of pipemidic acid suggest the effective applicability of the drug in the field.

Epithelial-mesenchymal tissue interactions guiding otic capsule formation: the role of the otocyst.

The otocyst is the epithelial anlage of the membranous labyrinth which interacts with surrounding cephalic mesenchyme to form an otic capsule. A series of in vitro studies was performed to gain a better understanding of the epithelial-mesenchymal interactions involved in this process. Parallel series of otocyst/mesenchyme (O/M) and isolated periotic mesenchyme (M) explants provided morphological and biochemical data to define the role of the otocyst in organizing and directing formation of its cartilaginous otic capsule. Explants were made from mouse embryos ranging in age from 10 to 14 days of gestation, and organ cultured under identical conditions until the chronological equivalent of 16 days of gestation. Expression of chondrogenesis was determined by both histology and biochemistry. The in vitro behaviour of periotic mesenchyme explanted either with or without an otocyst supports several hypotheses that explain aspects of otic capsule development. The results indicate that prior to embryonic day 12 the otocyst alone is not sufficient to stimulate chondrogenesis of the otic capsule within O/M explants; the otocyst acts as an inductor of capsule chondrogenesis within O/M explants between embryonic days 12 to 13; isolated mesenchyme within M explants taken from 13-day-old embryos are capable of initiating in vitro chondrogenesis, but without expressing capsule morphology in the absence of the otocyst; and the isolated mesenchyme of M explants obtained from 14-day-old embryos expresses both chondrogenesis and otic capsule morphology in the absence of the otocyst. These findings suggest that the otocyst acts as an inductor of chondrogenesis of periotic mesenchyme tissue between embryonic days 11 to 13, and controls capsular morphogenesis between embryonic days 13 to 14 in the mouse embryo.

Fibrogenesis and biosynthesis of elastin in cartilage.

This study presents direct evidence that dissociated chondroblasts from rabbit ear cartilage grown in vitro are capable of synthesizing insoluble elastin. Ultrastructural examination indicated that at an early stage of tissue development, elastogenesis is initiated producing a form of primary fibrils which later condense into an electron dense amorphous material which, unlike other elastin-containing tissues, is heavily stained by metal cations and lacks peripheral microfibrils. Native elastic fibrils and the mature elastic fiber bundles are both susceptible to elastase digestion. Transmission electronmicroscopy demonstrated the presence of many intracellular filaments all showing a substructural organization and localized in close proximity to the nucleus. Their possible contractile nature is discussed. Amino acid analysis of cartilage elastin and of the elastin synthesized in vitro revealed a close chemical similarity between the two molecules. Ultrastructural analysis of the in vitro elastin demonstrated a substructural organization quite similar to that of the elastin observed in an in vivo system.

[Experimental studies on tissue distribution of 14C-labelled antimicrobial agent in the otorhinolaryngological field--application of macro-autoradiography].

The distribution of antimicrobial agents in infected target tissues would be essential for their application to treat the sites of infection. Taking accounts of the view point, we had reported the distribution of 3 nalidixic acid analogs in tissues which are related to otorhinolaryngology by macro-autoradiography and radiometry. We investigated here in the distribution of a nalidixic acid analog OPC-7241. This agent is 9-fluro-5-methyl-8-(4-methyl-1-piperaginyl)-6, 7-dihydro-1-oxo-1H, 5H-benzo [ij]quinoligine-2-carboxylic acid supplied by Otsuka Pharmaceutical Co., Ltd. Autoradiography was performed 30 minutes after intravenous administration of 14C-OPC-7241 in 2.96 MBq(80.0 microCi)/12.5mg/kg to New Zieland White rabbit. Radiometry was performed 30 minutes, 1 hour and 3 hours after intravenous administration of 14C-OPC-7241 in 740 kBq (20.0 microCi)/10.0 mg/kg to NZW rabbits. Such care was taken in filling the carboxymethyl cellulose paste into the paranasal cavity, nasal cavity, oral cavity and external ear canal not to damage mechanically. Horizontal frozen sections parallel to mandibular basis were cut in 50 microns thickness in a cryostadt. Blackening of 14C-OPC-7241 was most significant in soft palate and its expanse which is apparently the same gland-like tissues as soft palate when stained with hematoxylin and eosin. Significant radioactivity was recognized in tonsils, the cartilage of external ear canal, septal cartilage, periodontal membrane, dental pulp, muscle and concha nasalis ventralis. The levels was low in ethmoid cells, mucosa of tympanic cavity, cochlea, maxillary sinus and bone. Quantitatively, the levels of 14C-OPC-7241 radioactivity were high in soft palate, mandibular gland and tonsils. Radioactivity was significant in tongue and concha nasalis ventralis. The levels were low in turbinates, ethmoid cells, maxillary sinus, septal cartilage, septal mucosa, cochlea, brain, optic nerve and lens. Thus radiometric results agreed with the above autoradiographic findings. Macro-autoradiography can be one of useful means for the evaluation chemotherapeutic agents for possible clinical application.

The effect of different cooling temperatures and immersion fluids on post-burn oedema and survival of the partially scalded hairy mouse ear.

One ear of NMRI hairy mice was first scalded and then immediately immersed in cold water or saline at 8 degrees C, 15 degrees C, 20 degrees C, 25 degrees C or 30 degrees C for a period of 30 min in order to study oedema formation and the therapeutic effect at 4 days. Oedema was determined by wet-dry weight measurements of punch biopsies from the ear and expressed as an increase in tissue water content. The therapeutic effects at 4 days were determined by observing the survival of the ear; the area of necrosis was expressed in per cent of the total area of the ear. Significant oedema was found in all scalded ears. A partial (15 per cent) dry necrosis of the untreated burned ear had developed within 4 days. Cooling in 8 degrees C water or saline for 30 min post-burn significantly reduced oedema in this model as determined 2h post-burn. However, 4 days post-burn all cooled ears showed a 15 per cent necrosis.

Immunopotentiating effects of amphotericin B. I. Enhanced contact sensitivity in mice.

Contact sensitivity responses to dinitrofluorobenzene (DNFB) or oxazolone were enhanced by amphotericin B (AmB) administration. This adjuvant effect of AmB was documented in mice by ear thickness measurements, ear histology, and the 5-iodo-2'-deoxyuridine-125I ear assay. The optimum immunopotentiating effect of AmB required its simultaneous administration at the time of skin sensitization. AmB-induced adjuvant effects were also observed in adoptive transfer experiments in which syngeneic recipients of lymph node cells from animals sensitized with DNFB plus AmB gave stronger contact sensitivity responses than recipients of cells from mice sensitized with DNFB alone. AmB also interfered with tolerance induction by i.v. dinitrobenzene sulfonic acid, suggesting that its adjuvant effects involve inhibition of suppressor cells or their precursors.

Gentamicin ototoxicity dissociated from glucose uptake and utilization.

The hypothesis was tested that gentamicin causes loss of cochlear microphonic potentials by interfering with glucose transport or metabolism in cochlear structures. Gentamicin (3 or 10 mM), applied by perilymphatic perfusion in the guinea pig, reduced cochlear microphonics in a dose-dependent manner. The presence of 5 mM glucose lowered the initial rate but not the final (60 min) loss of cochlear microphonics. Glucosamine (2-deoxy-2-aminoglucose), a reported inhibitor of glucose transport, had no effect at concentrations as high as 20 mM. Glucose utilization was measured by introducing radiolabeled deoxyglucose into the perfusate and determining its uptake into inner ear tissues. Concentrations of deoxyglucose-6-phosphate in organ of Corti and in stria vascularis increased linearly with time and remained unaffected by the presence of 3 mM gentamicin. Ten mM gentamicin reduced deoxyglucose uptake by 30% in the lateral wall tissues but not in the organ of Corti preparation. The lack of correlation between loss of microphonics and glucose utilization does not support interference with glucose metabolism as a primary mechanism of aminoglycoside ototoxicity.

Immunohistochemical localization of keratin in head and neck neoplasms and normal tissues.

Immunohistochemical localization of keratin antigens using keratin antisera and the immunoperoxidase technique have been shown to be helpful in identifying certain epithelial cells. Our study was designed to evaluate the application of this technique to head and neck neoplasms and normal tissues using two keratin antibody preparations. Our data indicate that the keratin antibodies stained normal epithelial structures in the head and neck except for cells with active secretory functions such as mucus, cerumen, or salivary secretion. Neoplasms of the head and neck showed keratin antibody staining for epithelial neoplasms and negative staining for mesenchymal neoplasms. The immunohistologic demonstration of keratin is useful in distinguishing undifferentiated or poorly differentiated epithelial malignancies from sarcomas or lymphomas and demonstrating myo-epithelial cells in salivary neoplasms.