Gamma interferon as a crucial host defense against Rickettsia conorii in vivo

Gamma interferon (IFN-gamma) plays an important role as a host defense in rickettsial infection. Swiss Webster mice, which are resistant to Rickettsia conorii (Malish 7 strain) infection, were treated with a monoclonal antibody against mouse IFN-gamma. When the antibody-treated mice were inoculated with 12 50% tissue culture infective doses of R. conorii, the mortality was 47% and the morbidity was 100%. None of the control mice, which received the same dose of R. conorii, died or became ill. The enumeration of rickettsiae in organs by direct immunofluorescence in paraffin sections demonstrated higher quantities of rickettsiae in the spleen had liver of IFN-gamma-depleted mice as compared with those of the infected controls. The kinetic analysis of IFN-gamma levels in sera showed depletion in the treated mice. These results indicate that IFN-gamma plays an important role as a host defense in the early stage of rickettsial infection. Survival of some mice despite continued treatment with antibody to IFN-gamma suggests that other immune mechanisms may also be important.

Fluorometric determination of streptomycin in serum by high-performance liquid chromatography using mobile phase containing fluorogenic reagent

A new postcolumn derivatization method for the fluorometric determination of streptomycin in serum by high-performance liquid chromatography is described. The serum was treated with 3.5% perchloric acid to precipitate proteins and the supernatant was directly injected into the chromatograph. Streptomycin was separated by reversed-phase, ion-pair chromatography with a mobile phase containing ninhydrin as a fluorogenic reagent, octanesulfonate, and 1,2-ethanedisulfonate as counterions, and was detected by fluorescence using continuous-flow, postcolumn derivatization in an alkaline stream with ninhydrin in the mobile phase. This method is sensitive to 1.0 microgram/ml using only 100 microliter of serum. Comparison with a fluorescence polarization immunoassay gave a good correlation coefficient of 0.976.

[DNA transformation activity of a human gastrocarcinoma cell line]

DNAs of three cell lines of human gastrocarcinoma (MGC-803, BGC-823 and PACM-82) and two fresh solid tumors of human stomach cancer were used to transfect NIH3T3 and Rat-1 cells. The transformed cells were selected with high concentration of glucose and low concentration of serum, or with medium containing Geneticin (G418) after co-transfection of pSVneo and DNAs of stomach cancer cell line or primary transformants. From the second round transfection, we had obtained transformants which could grow with high colony forming efficiency in soft agarose and were tumorigenic in nude mice. The southern blot analysis showed that the cellular DNA of the transformants contained human Alu repeat sequence and the transformed gene from stomach cancer cell line (BGC-823) and was homologous to proto-oncogene c-Ha-ras. The transforming gene is able to induce neoplastic transformation of NIH3T3 and Rat-1 cells.

Recovery of secretin in acid small intestinal lumen perfusates in the rabbit

Immunoreactive secretin concentrations were measured in femoral venous plasma and in intestinal perfusates during acid and neutral perfusion of small intestinal segments in anesthetized rabbits. Steady-state plasma and luminal secretin concentrations were less than 20 pg/ml. Duodenal perfusion with with 0.1 N hydrochloric acid stimulated peak plasma immunoreactive secretin concentrations of 200 - 300 pg/ml within five minutes. Acid stimulated plasma concentrations remained constant during 30 minutes of perfusion. Secretin output into the acid perfusate (2000 - 4000 pg/min) accompanied the release into plasma. Subsequent perfusion with a neutral solution resulted in a rapid return to steady-state plasma and luminal secretin concentrations. Sequential acid perfusion of the ileum, jejunum, and duodenum stimulated similar concentrations of secretin in plasma and luminal perfusates.

The pharmacodynamics of bucainide (RHC G233): pharmacokinetic parameters and relationship between plasma levels and the effect on the electrocardiogram in the dog

The pharmacodynamic profile of bucainide dimaleate (RHC G-233) in dogs has been studied. The first observed pharmacologic effect was a change in the ECG pattern (T-wave duration and amplitude) that occurred after an average intravenous dose of 2.7 mg/kg. The average plasma concentration of bucainide was approximately 350 ng/ml. Analysis of data from dogs that received a dual infusion of bucainide indicated that bucainide has an extensive volume of distribution, with an average value of approximately 26 l/kg. An average terminal half-life of 89 minutes was observed. Studies with the radiolabeled drug in rats and dogs also demonstrated the drug's large volume of distribution, and its initial rapid disappearance from the blood. Tissue distribution studies in the rat after administration of the radiolabeled drug showed that bucainide is rapidly taken up by the tissues.

GLC determination of urinary chlorthalidone levels

A sensitive and specific GLC method for the determination of urinary chlorthalidone levels was developed using on-column methylation. Chlorthalidone is converted to a tetramethylated derivative with trimethylanilinium hydroxide in methanol. This method which permits the determination of as little as 0.1 microgram of chlorthalidone/ml of dog urine, should be adequate for use with human subjects receiving a clinical dose.

Chlorthalidone analysis using carbonic anhydrase inhibition

Chlorthalidone was analyzed in the concentration range of 0.1-3.0 microgram/ml with a precision of +/- 0.05 microgram/ml. Chlorthalidone inhibition of the enzymatic hydrolysis rate of p-nitrophenyl acetate by bovine erythrocyte carbonic anhydrase was used as a basis for the determination. The amount of p-nitrophenol formed was measured by monitoring the absorbance at 400 nm, and its formation rate was proportional to the chlorthalidone concentration. The mixing of the enzyme, substrate, and sample, the incubation of the reaction mixture, and the recording of the absorbance were automated. A survey of urine samples from 26 normal human subjects did not reveal any endogenous substances that interfered with the assay. Analyses of urine samples from six subjects after oral administration of 100 mg of chlorthalidone indicated rapid absorption and a biphasic elimination. The alpha-phase half-life was 1.5 hr, and the beta-phase half-life was 35 hr.

GLC determination of nylidrin in human urine samples

A method for the detection of nanogram quantities of nylidrin in human urine is described. The method involves beta-glucuronidase hydrolysis, extraction with chloroform, derivatization by silylation, and GLC determination. The suitability of the method was tested by analysis of urine samples of subjects after oral ingestion of nylidrin hydrochloride.