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Inhibition of an anti-Pr1d cold agglutinin by citrate present in commercial red cell preservative solutions.

A patient with known cold autoimmune hemolyticanemia was admitted for surgery. Routine cold agglutinin evaluations, using commercial red cells (RBCs) in modified Alsever's preservative solution, revealed a cold agglutinin titer of 4 to 16. However, using RBCs washed four times with saline, a high-titer (greater than 2000 at 4 degrees C) cold autoagglutinin was demonstrated. The cold agglutinin was shown to be an IgM kappa paraprotein with anti-Pr1d specificity. The addition of Alsever's solution to washed RBCs inhibited the cold agglutinin. Each major component of Alsever's solution (neomycin, chloramphenicol, inosine, dextrose, and citrate) was tested individually; only citrate inhibited the patient's cold agglutinin. Various compounds structurally related to citrate were tested and found to cause various degrees of inhibition. The strongest inhibition correlated with the presence of either three carboxyl groups on molecules devoid of double-bonded carbon atoms or two carboxyl groups in cis configuration. A panel of 54 cold agglutinins, including 7 with anti-Pr specificity, was analyzed. None was significantly inhibited by Alsever's solution, although one with anti-Pr2 specificity was weakly inhibited. In summary, these studies describe an anti-Pr1d cold autoagglutinin that was inhibited by citrate in RBC preservative solutions. The failure to detect such a cold agglutinin can result from not washing RBCs free of citrate before testing.

Aged

Stimulation of benzodiazepine receptor binding by gamma-aminobutyric acid.

The effect of the neurotransmitter gamma-aminobutyric acid (GABA) on high-affinity binding of benzodiazepines to brain membranes has been investigated. GABA stimulated [3H]diazepam binding by more than 100% when extensively washed membranes from brain tissue were used. This GABA-stimulated benzodiazepine binding occurred in all brain regions examined. The stimulation was specific for GABA agonist. It was inhibited by the GABA receptor blocker bicuculline methiodide. A large number of compounds structurally closely related to GABA but without direct effect on the GABA receptor failed to enhance [3H]diazepam binding. The stimulation of benzodiazepine binding was caused by an increase in affinity; the number of binding sites remained unchanged. Half-maximal activation of [3H]diazepam binding occurred in the presence of 300 nM muscimol or 900 nM GABA. beta-Guanidinopropionic acid and imidazoleacetic acid were much weaker activators. It is suggested that the described stimulation of benzodiazepine high-affinity binding is mediated by a receptor for GABA. This site of GABA action exhibits different properties when compared to GABA receptors, as characterized by high-affinity binding of GABA agonists.

Animals

Monoclonal antibodies to digoxin: comparison of in vitro and in vivo immunization.

We compared the primary response in vitro with the secondary response in vivo of A/J inbred and CD-1 outbred mice to digoxin-HSA. The frequencies of hybrid formation and growth, and of the hybridomas that secreted antibody to digoxin were similar in both strains regardless of the immunization procedure. The patterns of cross-reactivity of the monoclonal antibodies to two compounds structurally related to digoxin (ouabain and digitoxin) were likewise similar for both strains and immunization procedures.

Animals

Phase I trial of Taxotere: five-day schedule.

BACKGROUND: Taxotere, a semisynthetic compound structurally related to taxol, has a broad spectrum of activity in murine transplantable tumors; in the B16 melanoma model, it caused a total log cell kill 2.5 times greater than that caused by taxol at equitoxic doses. PURPOSE: We conducted a phase I study of Taxotere (a) to determine its qualitative and quantitative toxic effects and a starting dose for phase II trials, (b) to investigate its clinical pharmacology, and (c) to document its antitumor activity. METHODS: Taxotere was given as a 1-hour infusion at a starting dose of 1 mg/m2 per day for 5 consecutive days. The 5-day course of therapy was repeated every 21 days. Thirty-nine cancer patients with advanced disease were entered in the study; at least three patients were entered at each dose level. Initial dose escalations were planned at 100% increments until biologic activity was observed; subsequent escalations were planned at 50% increments until grade 2 toxicity (the National Cancer Institute's Common Toxicity Criteria) occurred and then at 25% increments until the maximum tolerated dose was established. RESULTS: Thirty-nine patients were entered in the study. Successive dose levels used were 1, 4, 8, 16, 12, and 14 mg/m2 per day. The dose-limiting toxic effects were granulocytopenia and concurrent mucositis. Grade 4 granulocytopenia associated with grade 3 mucositis developed in six of 12 patients treated at a dose of 16 mg/m2 per day, two of 10 treated at 12 mg/m2 per day, and two of eight treated at 14 mg/m2 per day. Because these toxic effects occurred concurrently, all patients so affected developed neutropenic fevers and required hospitalization. Neither cardiac nor neurologic toxic effects were noted. Anti-tumor activity was observed in six patients with ovarian cancer and in one with breast carcinoma. Although pharmacokinetic parameters were consistent between day 1 and day 5 for individual patients, considerable variation existed among those treated at the same dose level. A relationship was observed between the area under the curve for plasma concentration of drug x time (AUC) on day 1 and the percentage decrease in absolute granulocyte counts. CONCLUSION: Granulocytopenia associated with oral mucositis is the dose-limiting toxicity of this schedule. We recommended a starting dose of 14 mg/m2 per day for phase II studies of this 5-day schedule. Dose modifications on days 2-5 based on the day-1 AUC may allow individualized dosing.

Adult

Preparation of 2'-thio-2'-deoxycytidine 2':3'-phosphorothioate.

The synthesis of a novel ribonucleotide analog 2'-thio-2' deoxycytidine 2':3'-O,S-phosphorothioate is described. In the first step, 2,2'-anhydro 1-beta-D-arabinosylcytosine was thiophosphorylated by the action of dithiophosphate, a process which gave predominantly the 3'-O-phosphorothioate isomer. An intramolecular displacement reaction led to the formation of the title compound. Structure and reactivity of this thioanalog differ substantially from 2':3'-CMP.

Cytosine Nucleotides

Retinoids in cancer prevention and therapy.

Retinoids are a class of compounds structurally related to vitamin A. In preclinical studies, all-trans retinoic acid (tretinoin), 13-cis retinoic acid (isotretinoin) and the aromatic retinoids etretinate and acitretin have preventive and therapeutic effects on carcinogen-induced premalignant and malignant lesions. Clinically, chemoprevention with isotretinoin and etretinate has been tested with some degree of success in such indications as basal cell carcinomas, squamous cell carcinomas, superficial bladder tumors and second primary tumors in patients with squamous cell carcinoma of the head and neck. Limited therapeutic success has also been achieved with retinoid treatment of precancerous and cancerous conditions of the skin, oral cavity, larynx, lung, bladder and vulva. Dramatic therapeutic effects have been observed in the treatment of acute promyelocytic leukemia with tretinoin, which leads to very high rate of complete remission. Excellent results were recently reported in the treatment of squamous cell carcinomas of the skin and cervix with a combination of isotretinoin and recombinant interferon alfa-2a (rIFN alfa-2a, Roferon-A). The mechanism of action of retinoids is through modulation of cell proliferation and differentiation. Retinoids vary in their capacity to induce differentiation and to inhibit proliferation in a series of human transformed hematopoietic and epithelial cell lines. Some cytokines potentiate the retinoid-induced cell differentiation and act synergistically with retinoids to inhibit cell proliferation. The pattern of synergism is dependent upon the combination and tumor cell line tested. The discovery of nuclear retinoid receptors has contributed substantially to the understanding of the mechanism of action of retinoids at the molecular level. Further understanding of the molecular biology of retinoids is expected to contribute to a rational design of new retinoids in the future, which in turn may result in improvements in the prevention and therapy of cancer.

Animals

Cloning and characterization of highly polymorphic porcine microsatellites.

A size-fractionated (200-400 bp) porcine genomic library was screened with the dinucleotide motifs (TG)n and (TC)n. The number of TG- and TC-positive clones was 83 and four, respectively, implying that the former motif is more frequent in the porcine genome, as previously reported in other species. Twenty-six TG-clones were sequenced, and the number of repeats varied between 16 and 42 with different compositions of the repetitive sequences; 17 clones had a perfect stretch of TG-repeats, four had imperfect stretches, and five had a compound structure with TG-repeats followed by TC-repeats. Primers for DNA amplification using the polymerase chain reaction (PCR) were synthesized for six loci. Ten unrelated individuals (two wild boars and eight domestic pigs of the Swedish Yorkshire breed) were screened for microsatellite polymorphism. All six microsatellite loci were polymorphic with two to seven alleles and observed heterozygosities in the range of 0.42-0.84; the inheritance of the observed polymorphism was confirmed by family studies. The characteristics of microsatellites make them highly suitable as genetic markers, and these microsatellites were isolated as a part of a pig gene mapping project.

Animals

Differentiation-inducing-factor dechlorinase, a novel cytosolic dechlorinating enzyme from Dictyostelium discoideum.

Differentiation-inducing factor 1 (DIF-1) is a dichlorinated alkyl phenone (1-[(3,5-dichloro-2,6-dihydroxy-4-methoxy)phenyl]hexan-1-one) from Dictyostelium discoideum, that induces amoebae to differentiate into stalk cells. It was shown previously that DIF-1 is rapidly metabolized into a series of more polar compounds by living cells [Traynor, D. & Kay, R.R. (1991) J. Biol. Chem. 266, 5291-5297]. The first step in DIF-1 metabolism is the formation of DIF metabolite 1 (now known to be DIF-3) by a monodechlorination. We report here the discovery of the enzyme activity catalyzing this dechlorination. A very sensitive enzyme assay was developed, using [3H]DIF-1 and a TLC system to separate DIF-1 from the product, DIF-3. DIF-1 3(5)-dechlorinase is present in the high-speed supernatant of cell lysates, and uses glutathione, at physiological concentrations, as cofactor. Kinetic measurements indicate a Km for DIF-1 of about 70 nM. The enzyme activity is inhibited by DIF-2 (the pentan-1-one analogue of DIF-1), with a median inhibitor concentration (IC50) of 1 microM, and DIF-3 (IC50 = 5 microM), which presumably act as substrates, but other compounds structurally related to DIF-1 were much less effective. Aurothioglucose, an inhibitor of selenocysteine enzymes, inhibited DIF-1 3(5)-dechlorinase with IC50 = 100 nM. DIF-1 3(5)-dechlorinase activity is developmentally regulated. It is essentially absent from growing cells and increases at the end of aggregation to reach a first peak of activity at the first finger stage, with a further rise at culmination.

Animals

Effects of membrane-energy mutations and cations on streptomycin and gentamicin accumulation by bacteria: a model for entry of streptomycin and gentamicin in susceptible and resistant bacteria.

Several mutants of Escherichia coli affecting aerobic energy generation and energization of the bacterial membrane have been examined for their effect on streptomycin and gentamicin accumulation and susceptibility. A heme-deficient mutant (K207) and two mutants (CJ-8 [colicin K insensitive] and NR-70) associated with defective aerobic active transport were associated with decreased transport of streptomycin and gentamicin and increased resistance to those antibiotics. These mutants also exhibited increased resistance to several other aminoglycoside antibiotics, but not the aminocyclitol spectinomycin. The same observations were made with a ubiquinone-deficient mutant, but a strA derivative of this mutant was shown additionally to be saturable for streptomycin accumulation at a concentration four or more times lower than that required for saturation of the parent. A mutant uncoupled for adenosine 5'-triphosphate synthesis from electron transport and membrane Mg-adenosine 5'-triphosphatase deficient was hypersensitive to those aminoglycosides tested and spectinomycin, and showed enhanced transport of streptomycin and gentamicin. A variety of compounds structurally related to streptomycin were examined at high concentrations for inhibition of streptomycin uptake in a strA mutant of E. coli K-12 SA 1306, but no evidence for competition was detected, suggesting the absence of a common transport carrier. Four different divalent cations were shown to inhibit streptomycin and gentamicin accumulation in E. coli K-12 SA 1306. Divalent cations were shown to inhibit uptake of these two drugs in two bacterial species with distinct cell wall structures, Pseudomonas aeruginosa and Staphylococcus aureus, and to inhibit streptomycin uptake in spheroplasts of streptomycin-susceptible and -resistant E. coli. However, calcium had almost no inhibitory effect on streptomycin uptake by the ubiquinone-deficient mutant E. coli AN66. These and previous findings have been used to formulate a model for aminoglycoside entry into bacteria using a low-affinity membranous complex involved in membrane energization that includes respiratory quinones, which probably act to bind and transport aminoglycosides across the cell membrane. This phase of transport is associated with the lowest accumulation rate (termed energy-dependent phase I) that is rate limiting for susceptibility. It is further proposed that subsequent association of the membrane-bound aminoglycoside with higher-affinity binding sites on membrane-associated ribosomes carrying out a normal ribosomal cycle and protein synthesis results in a more rapid transport rate (termed energy-dependent phase II). The increased rate could result from a state of membrane energization analogous to that causing enhanced aminoglycoside transport rates seen in the uncoupled mutant, AN120. How this model explains the mechanism by which enzymatically modified aminoglycosides render cells resistant to unmodified aminoglycosides is also discussed.

Adenosine Triphosphatases

Degradation of [14C]photodieldrin by Trichoderma viride as affected by other insecticides.

Various soil fungi were tested for their capacity to degrade the insecticide [14C]photodieldrin. Of nine species investigated, Trichoderma viride was the only one which degraded the insecticide to an appreciable extent into water-soluble, non-insecticidal compounds within 4-5 weeks. These products amounted to 32-41% of the radiocarbon applied to the culture media. The degradation was a function of live mycelia, which metabolized the insecticide and excreted water-soluble compounds into the culture media. Since soils usually contain a mixture of pesticide residues, the effects of several chlorinated hydrocarbon insecticides on the capacity of the fungus to degrade [14C]photodieldrin were studied. Thus, in fungal cultures treated with compounds structurally similar to photodieldrin, such as aldrin and dieldrin, only 4-17% of the applied radiocarbon was water-soluble and more photodieldrin remained. In controls, however, 35% of the applied radiocarbon was in the form of water-soluble products and less photodieldrin remained. The degradation of [14C]photodieldrin by T. viride, with time, was associated with a continuous decline of hexane-soluble radiocarbon and a steady increase of water-soluble metabolites, which appeared in the fungal media. The amount of hexane-soluble radiocarbon in mycelia was directly related to the fungal mass.

Biodegradation, Environmental

Microbial degradation of [C14C]polystyrene and 1,3-diphenylbutane.

Microbial degradation of [beta-14C]polystyrene and 1,3-diphenylbutane, a compound structurally representing the smallest repeating unit of styrene (dimer), was investigated in soil and liquid enrichment cultures. Degradation rates in soil, as determined by 14CO2 evolution from applied [14C]polystyrene, varied from 1.5 to 3.0% for a 4-month period. Although relatively low, these percentages were 15 to 30 times greater than values previously reported. Enrichment cultures, containing 1,3-diphenylbutane as the only carbon souce, were used to determine the mechanisms of microbial oxidation of the polymer chain ends. Metabolism of 1,3-diphenylbutane appeared to involve the attack by a monooxygenease to form 2-phenyl-4-hydroxyphenylbutane followed by a further oxidation and subsequent fission of the benzene ring to yield 4-phenylvaleric acid and an unidentified 5-carbon fragment via the classic meta-fission pathway. Phenylacetic acid was probably formed from 4-phenylvaleric acid by subsequent beta-oxidation of the side chain, methyl-oxidation and decarboxylation. An initial examination of the population of microorganisms in the diphenylbutane enrichment cultures indicated that these oxidative reactions are carried out by common soil microorganism of the genera Bacillus, Pseudomonas, Micrococcus, and Nocardia.

Bacteria

Calcium stimulates glucose transport in skeletal muscle by a pathway independent of contraction.

In this study we investigated the possibility that an increase in cytoplasmic Ca2+ concentration that is too low to cause muscle contraction can induce an increase in glucose transport activity in skeletal muscle. The compound N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), which induces Ca2+ release from the sarcoplasmic reticulum (SR), caused a dose-dependent increase in tension in rat epitrochlearis muscles at concentrations more than approximately 200 microM. Although 100 microM W-7 did not increase muscle tension, it accelerated loss of preloaded 45Ca2+. Glucose transport activity, measured with the nonmetabolizable glucose analogue 3-O-methylglucose, increased sixfold in muscles treated for 100 min with 50 microM W-7 (P less than 0.001) and eightfold in response to 100 microM W-7 (P less than 0.001). The increase in glucose transport activity was completely blocked with 25 microM cytochalasin B. There was no decrease in ATP or creatine phosphate concentrations ([approximately P]) in muscles incubated with 50 microM W-7. Dantrolene (25 microM), which blocks Ca2+ release from the SR, blocked the effects of W-7 both on 45Ca2+ release and on glucose transport activity. 9-Aminoacridine, another inhibitor of Ca2+ release from the SR, also blocked the stimulation of hexose transport by W-7. Caffeine, a compound structurally unrelated to W-7 that also releases Ca2+ from the SR, also increased glucose transport activity. Incubation of muscles with 3 mM caffeine for 30 min, which did not cause contraction or lower [approximately P], induced a threefold increase in 3-O-methylglucose transport (P less than 0.001). These results provide evidence suggesting that an increase in cytoplasmic Ca2+ too low to cause contraction or [approximately P] depletion can bring about an increase in glucose transport activity in skeletal muscle.

3-O-Methylglucose

Effects of endothelin-1 and sarafotoxin S6b on regional hemodynamics in the conscious dog.

Endothelin, a potent vasoconstrictor, also is capable of producing transient vasodilation in some situations. We examined the changes in regional hemodynamics in response to constant infusions of endothelin-1 (ET-1) at 5, 10, or 20 ng.kg-1.min-1 for 1 h into conscious dogs. The dogs were instrumented with ultrasonic flow probes for measurement of blood flow in the ascending aorta (cardiac output) and in the coronary, mesenteric, renal, and iliac arteries. A compound structurally similar to ET-1, sarafotoxin S6b (S6b), was also infused in identical experiments to determine whether the responses to these two peptides might differ. Basal plasma levels of immunoreactive ET-1 averaged approximately 6 pg/ml. After 55 min of infusion of ET-1 at 5, 10, and 20 ng.kg-1.min-1, plasma immunoreactive ET-1 increased to approximately 55, 130, and 520 pg/ml, respectively. When given at 20 ng.kg-1.min-1, ET-1 increased total peripheral resistance and arterial pressure and decreased cardiac output and heart rate. ET-1 decreased coronary, mesenteric, and renal blood flow but did not change iliac flow. In comparison with ET-1, S6b produced relatively smaller changes in total peripheral resistance, cardiac output, heart rate, and coronary, mesenteric, and renal blood flow. Iliac resistance did not change in response to ET-1, but it increased during infusions of S6b. Similar but less pronounced responses were observed when these peptides were infused at 5 and 10 ng.kg-1.min-1. The regional variability in the hemodynamic response to ET-1 and the difference in regional responses to ET-1 and S6b are consistent with the existence of heterogenous receptor subtypes for these peptides.

Animals

[Vitamin E and selenium in the feed of farm animals (author's transl)].

A survey is given of vitamin E and selenium deficiency syndromes in farm animals. Some syndromes can be attributed to the exclusive deficiency of one of the above-mentioned feed components. In some cases with practically complete lack of both componentspathological symptoms can be cured by the addition of one of them to the feed in sufficient amount. A synergistic effect of vitamin E and selenium is sometimes found to recur. The most important theory about the functioning of vitamin E is that it acts as an antioxidant. This theory presumes that, in case of a vitamin E deficiency, peroxidation of unsaturated lipids can occur everywhere in the body leading to oxidative chain reactions. The free radicals thus produced might participate in non-specific reactions with functional and structural compounds. Vitamin E is considered able to reduce lipid peroxides or scavenge free radicals from chain reactions. The pros' and cons' of this theory are discussed. The role of vitamin E has further been associated with thenium is part of the enzyme glutathione peroxidase. This enzyme catalyses the reaction of reduced glutathione with peroxides, whereby hydroxy-acids and oxidized glutathione are generated. Most probably the glutathione peroxidase has its antioxidative action in the cytosol, whereas vitamin E is mainly located in the membranes of the cell.

Adipose Tissue

Exposure of phosphatidylserine on the surface of apoptotic lymphocytes triggers specific recognition and removal by macrophages.

During normal tissue remodeling, macrophages remove unwanted cells, including those that have undergone programmed cell death, or apoptosis. This widespread process extends to the deletion of thymocytes (negative selection), in which cells expressing inappropriate Ag receptors undergo apoptosis, and are phagocytosed by thymic macrophages. Although phagocytosis of effete leukocytes by macrophages has been known since the time of Metchnikoff, only recently has it been recognized that apoptosis leads to surface changes that allow recognition and removal of these cells before they are lysed. Our data suggest that macrophages specifically recognize phosphatidylserine that is exposed on the surface of lymphocytes during the development of apoptosis. Macrophage phagocytosis of apoptotic lymphocytes was inhibited, in a dose-dependent manner, by liposomes containing phosphatidyl-L-serine, but not by liposomes containing other anionic phospholipids, including phosphatidyl-D-serine. Phagocytosis of apoptotic lymphocytes was also inhibited by the L isoforms of compounds structurally related to phosphatidylserine, including glycerophosphorylserine and phosphoserine. The membranes of apoptotic lymphocytes bound increased amounts of merocyanine 540 dye relative to those of normal cells, indicating that their membrane lipids were more loosely packed, consistent with a loss of membrane phospholipid asymmetry. Apoptotic lymphocytes were shown to express phosphatidylserine (PS) externally, because PS on their surfaces was accessible to derivatization by fluorescamine, and because apoptotic cells expressed procoagulant activity. These observations suggest that apoptotic lymphocytes lose membrane phospholipid asymmetry and expose phosphatidylserine on the outer leaflet of the plasma membrane. Macrophages then phagocytose apoptotic lymphocytes after specific recognition of the exposed PS.

Animals

Modulation of casein kinase II activity by the polar head group of an insulin-sensitive glycosyl-phosphatidylinositol.

A phospho-oligosaccharide, whose production is stimulated by insulin, modulated the activity of partially purified casein kinase II. Whereas at 2 microM the phospho-oligosaccharide stimulated casein kinase II 1.3-fold, higher concentrations of this molecule were inhibitory. 50% inhibition of the enzyme was obtained at 15 microM phospho-oligosaccharide. This biphasic effect of the phospho-oligosaccharide on casein kinase II activity was observed using as substrate both casein or the specific peptide for casein kinase II, Arg-Arg-Arg-Glu-Glu-Glu-Thr-Glu-Glu-Glu. The effect of the phospho-oligosaccharide on casein kinase II was still observed after gel filtration. Deamination of the phospho-oligosaccharide with nitrous acid abolished both the activation and the inhibition of casein kinase II. The glycophospholipid precursor of the phospho-oligosaccharide did not affect casein kinase II activity. Moreover, modulation of casein kinase II activity was not observed with other compounds structurally related to the phospho-oligosaccharide, when used in the micro-molar range. In conclusion, the present results indicate that the phospho-oligosaccharide that mimics and might mediate some of the actions of insulin modulates casein kinase II activity in vitro.

Amino Acid Sequence

Stimulation of granulocytic cell iodination by tannins and related compounds.

Tannic acid stimulated the iodination (incorporation of radioactive iodine into an acid-insoluble fraction) of human peripheral blood polymorphonuclear cells (PMN) and human promyelocytic leukemic HL-60 cells, without affecting the iodination of 9 other cultured cell lines. The stimulation of both PMN and HL-60 cells depended on incubation time and temperature, and was significantly suppressed by myeloperoxidase inhibitors. Among chemically defined natural polyphenols, condensed tannins (epicatechin gallate oligomers) and monomeric and oligomeric hydrolyzable tannins potently stimulated PMN iodination, whereas polyphenols of lower molecular weight (gallic acid, alkyl gallates, epicatechin, epicatechin gallate, epigallocatechin, caffeic acid derivatives and licorice flavonoids) had much less activity. Various synthetic polyphenolic compounds structurally unrelated to tannins also stimulated PMN iodination depending upon their molecular weight, but to a slightly lesser extent. The results suggest that the stimulation activity of tannins and related polyphenols might depend more on their molecular weights than the number of hydroxyl groups on each benzene ring in the molecule, or the presence of sugars or hexahydroxydiphenoyl groups.

Animals

Rosoxacin and cinoxacin distribution in prostate, vagina, and female urethra. An experimental study in dogs.

Rosoxacin and cinoxacin, two new compounds structurally related to nalidixic acid, were investigated in dogs. Our primary interest was in the beneficial effects of the two drugs when used in the treatment of urinary tract infections. The distribution of rosoxacin and cinoxacin was investigated in prostatic tissue, prostatic interstitial fluid, and prostatic secretion, and in vaginal and female urethral secretions. Concentrations of both antibiotics were also measured in plasma, various tissues, and spinal fluid. The amounts of rosoxacin and cinoxacin in all tested tissues, fluids, and secretions were in the range of the minimal inhibitory concentrations for most Gram negative organisms found in urinary tract infections. This suggested possible beneficial effects of these drugs when the infection involves the above tissues. Rosoxacin concentration ratios were higher than those of cinoxacin relative to plasma concentration in prostatic, vaginal, and urethral secretions, as well as in prostatic and other tissue. These ratio differences were explained by the different physiochemical properties of the two drugs.

Animals