Automated sample preparation for cholesterol determination in foods

An automated sample preparation system has been developed for the determination of cholesterol in a wide range of matrices. Isolation of cholesterol is performed with a robotic arm coupled with a series of modular stations. Samples are introduced into the system which adds the appropriate reagents, carries out the saponification, pH adjustment, solid-phase extraction and drying steps. This system was evaluated using 15 different food matrices. The average recovery for NIST standards exceeded 97%. A solution of n-hexane-2-propanol was substituted for the traditional methanol-chloroform extraction. Manual pH adjustment was replaced with a buffer. Manual and automated methods were compared and no difference was observed at the 95% confidence level.

Inhibition of hexokinase and protein kinase activities of tumor cells by a chloromethyl ketone derivative of lactic acid

A chloromethyl ketone derivative of lactic acid is a potent inhibitor of glycolysis of Ehrlich ascites tumor cells. It inhibited glycolysis of intact cells by about 50% at 200 microM (100 nmol/mg of protein) while cell-free extracts were inhibited 50% at 50 microM (50 nmol/mg of protein). N alpha-(p-Tosyl)-L-lysine chloromethyl ketone and N alpha-(p-tosyl)-L-phenylalanine chloromethyl ketone inhibited only slightly or not at all at this concentration. The inhibition was localized at the hexokinase and phosphofructokinase steps since these two enzymes added to an inactivated extract restored the glycolytic activity, whereas none of the other glycolytic enzymes did. In fact, addition of pyruvate kinase or lactate dehydrogenase, which stimulated glycolysis, resulted in a more pronounced inhibition. Glycolysis and hexokinase activities in extracts of Rous sarcoma virus transformed cells were considerably more sensitive to the inhibitor than the activities from normal chick embryo fibroblasts. Hexokinase from mouse brain required 50 times higher concentrations for inhibition than the enzyme from mouse Ehrlich ascites tumor cells. Yeast hexokinase was unaffected at all concentrations tested. Since 5,5'-dithiobis(2-nitrobenzoate) protected against the inhibition, the chloromethyl ketone appeared to inhibit by interaction with an essential SH group. A pronounced inhibition of protein kinase activity of plasma membranes of Ehrlich ascites tumor cells was observed in the presence of the chloromethyl ketone. As in the case of glycolysis, the chloromethyl ketone of lactic acid was a more potent inhibitor of protein kinase activity than several other chloromethyl ketones that were tested.

Screening of murine monoclonal antibodies against living schistosomula of Schistosoma mansoni by radioimmunoassay

A radioimmunoassay was developed to screen supernatants of murine monoclonal antibodies against surface antigens of living schistosomula of Schistosoma mansoni. Of 196 clones screened, 10% bound schistosomula. Of these, 74% bound only schistosomula. The remaining molecules also reacted with soluble adult worm antigens and soluble egg antigens as determined by enzyme-linked immunosorbent assay. Immunoblot analysis demonstrated that monoclonal antibody 204-3E4 reacted with a 68 kDa protein, a glycoprotein that induces substantial resistance against S. mansoni infection. Recognition of an 18 kDa antigen by 204-3F1 antibody was stage-specific with the antigen being expressed in cercariae, 3- and 24-h-old parasites but not 4-day, lung stage or adult worms. Monoclonal antibody 204-4E3 reacted with purified S. mansoni paramyosin. These data indicate that radioimmunoassay using living schistosomula is a rapid alternative method to identify murine hybridomas that secrete antibodies which react with surface antigens of S. mansoni.

Reversal by estrogen of the effect of dorsal raphe stimulation on release of LH but not prolactin

Electrical stimulation of the dorsal raphe nucleus (DRN) was administered to rats 2-4 weeks after ovariectomy and at least 7 days following implantation of a bipolar electrode. During stimulation the concentration of luteinizing hormone (LH) decreased whereas that of prolactin (Prl) increased in serial plasma samples obtained from the unanesthetized animals via a cannula chronically implanted in the right external jugular vein. Administration of estradiol benzoate (5 micrograms/100 g BW) for 2 days prior to the experiment reversed the effect of stimulation on LH but augmented the Prl response, suggesting modulation by estrogen of the relative effectiveness of opposing pathways ascending from DRN to influence LH release. It is also apparent that LH and Prl release are controlled by distinct mechanisms since estrogen exerted opposite influences on the responses of these two hormones to stimulation of DRN.

Cell membrane phospholipids and their constitutent fatty acids in dividing and nondividing cells of Micrococcus lysodeikticus

Changes occurring in the cell membrane of nondividing cells of Micrococcus lysodeikticus disIIp+ grown in the presence of the mucopeptide synthesis inhibitor D-cycloserine include (a) an increae in the relative amount of diphosphatidylglycerol with a concomitant decrease in the relative content of phosphatidylglycerol, (b) a small increase in the relative palmitic acid content of phosphatidylinositol, and (c) leakage of membrane components into the growth medium. Growth of the organism in the presence of both D-cycloserine and D-alanine (which prevents the effects of D-cycloserine on cell division and mucopeptide synthesis) prevents the above changes in the cell membrane, demonstrating that secondary damage to the cell membrane can occur as a rsult of inhibition in mucopeptide synthesis. Growth of the organism in the presence of D-cycloserine and pantoyl lactone prevents the leakage of membrne components and cell division inhibition. Possible relationships of these changes to cell division are discussed.

Lanomycin and glucolanomycin, antifungal agents produced by Pycnidiophora dispersa. II. Structure elucidation

Two novel antifungal agents, lanomycin and glucolanomycin, as well as a biologically inactive degradation product, lanomycinol, were isolated from liquid fermentations of Pycnidiophora dispersa. All three compounds share an E,E,E-triene appended to a pyran ring. Lanomycin contains a glycine ester and glucolanomycin possesses a glucose unit attached to the glycine nitrogen. The structures, including absolute stereochemistry, were determined by spectroscopic analysis and partial chemical degradation. Both of the glycine containing compounds show activity against several pathogenic fungi in vitro.

Growth hormone (GH) secretion in the pituitary-grafted male rat: in vivo effects of GH-releasing hormone and isoproterenol and in vitro release by individual somatotropes

Although the pituitary-grafted rat is a classic model of chronic PRL excess, the presence of somatotropes in grafted pituitary tissue indicates a potential for GH secretion. The current study was designed to investigate GH-releasing hormone (GRH)-induced GH secretion and beta-adrenergic inhibition of GH release in animals bearing ectopic pituitary tissue free from hypothalamic control. Positive findings with regard to these in vivo experiments led us to an initial determination of GH secretion by individual somatotropes from transplanted pituitary tissue. In litters of 10 30-day-old Fisher rats, 2 male animals received subcapsular renal grafts of 3 littermate pituitary glands each. Thirty-five days after grafting, 1 group received saline (SAL) followed by GRH, and the other received the beta-adrenergic agonist isoproterenol (ISO) followed by GRH. Blood samples were taken before and after SAL or ISO treatment, GRH was then infused, and sampling was continued. Plasma was assayed for GH and PRL, and the reverse hemolytic plaque assay was used to determine GH release by individual somatotropes from transplanted pituitary tissue. Plasma PRL was clearly elevated in pituitary-grafted compared to muscle-grafted animals, but there was no difference in either body weight gain or basal GH levels between the groups. As shown previously, ISO itself induced a brief release of GH due to its direct effect on the pituitary gland. The GH response to GRH was greater in pituitary-grafted animals than in muscle-grafted controls after both SAL and ISO. GRH-induced GH release was suppressed by ISO pretreatment in muscle-grafted animals, but not in pituitary-grafted animals. The reverse hemolytic plaque assay unequivocally showed that transplanted pituitary tissue was capable of tonic as well as GRH-stimulated GH release. These results demonstrate that despite similar basal GH levels, animals bearing pituitary grafts release significantly greater amounts of GH in response to GRH. The evidence for GH secretion by individual somatotropes from transplanted pituitary tissue directly shows the grafted tissue to be a source of GRH-stimulated GH. The lack of beta-adrenergic inhibition of GRH-induced GH release in pituitary-grafted animals is consistent with the hypothesis that beta-adrenergic inhibition of GRH-induced GH secretion is mediated by an effect on the hypothalamus.

Molecular forms of immunoreactive pancreatic cationic trypsin in pancreatitis patient sera

The molecular forms of immunoreactive pancreatic cationic trypsin in sera of patients with acute pancreatic inflammation have been characterized using a radioimmunoassay technique that is capable of detecting trypsinogen as well as trypsin bound to alpha 1-antitrypsin. Trypsin bound to alpha 2-macroglobulin is not immunoreactive under normal assay conditions. However, alpha 2-macroglobulin-bound trypsin can be detected after gel filtration of serum on Bio-Gel A-0.5 m and acid treatment of column fractions. The average serum level of immunoreactive cationic trypsin from 20 patients with acute pancreatic inflammation was 1,590 ng/ml. An average normal value of 26 ng/ml has been obtained previously. Serum samples from 14 patients with pancreatic inflammation were chromatographed under conditions that resolve trypsinogen, alpha 1-antitrypsin-bound trypsin, and alpha 2-macroglobulin-bound trypsin. In each case, the major portion of the immunoreactive material eluted at a position corresponding to free trypsinogen, while a minor fraction of the immunoreactive material appeared to be trypsin bound to alpha 1-antitrypsin. The zymogen nature of the major peak was confirmed in one case by activation with human enteropeptidase. In 11 of 14 patients, acid treatment of the alpha 2-macroglobulin peak yielded immunoreactive trypsin.

Evaluation of the neuropharmacodynamics of paroxetine in vivo utilizing microdialysis

The effect of paroxetine, a selective serotonin reuptake inhibitor used in the treatment of depression, on extracellular serotonin levels was evaluated in freely moving conscious rats. Microdialysis, a powerful in vivo technique to monitor the extracellular levels of neurotransmitters, was used to monitor the baseline changes in the levels of serotonin in rat brain anterior lateral striatum post paroxetine administration, which is a measure of the neuropharmacodynamic effect of the drug. Microdialysis sampling was performed for 210 min prior to and for 240 min after intraperitoneal administration of paroxetine (10 mg/kg). Paroxetine caused a statistically significant increase in the extracellular levels of serotonin in the anterior lateral striatum sampled by microdialysis. The present study demonstrates the utility of microdialysis for studying the in vivo neuropharmacodynamics of paroxetine in conscious rats.

SQ 30,957, a new antibiotic produced by Penicillium funiculosum. Taxonomy, fermentation, isolation, structure determination, synthesis and antibacterial activity

A new antibiotic, SQ 30,957, 4-diazo-3-methoxy-2,5-cyclohexadien-1-one, has been isolated from fermentation broths of Penicillium funiculosum. The structure (1) was deduced from its spectroscopic properties and its degradation reaction. SQ 30,957 has excellent activity against anaerobic bacteria such as Clostridium and Bacteroides and has moderate activity against aerobic bacteria. The compound has an LD50 of less than 17 mg/kg in mice by intraperitoneal administration.

Differential time- and dose-dependent effects in the haloperidol blockade of luteinizing hormone release and ovulation

The capacity of haloperidol (Haldol) to block luteinizing hormone (LH) release and ovulation was investigated with particular reference to its effectiveness during the "critical period" on the afternoon of proestrus in normal, cycling female rats. Haldol was injected subcutaneously at 13.30 h in one of five dosage levels (0.125, 0.25, 0.5, 1.0, or 4.0 mg/kg), or at 09.30 h in a single dose of 1.0 mg/kg. Control animals received the corn oil vehicle at 13.30 or 09.30 h. Blood samples were taken by means of intra-atrial catheters which had been implanted on the day prior to Haldol treatment. Oviducts were examined for the presence of ova at 10.00 h on the day following the experiment (estrus). Haldol was found to be ineffective at 13.30 h when given at dosage levels which were shown by previous authors, and in the present experiment, to be capable of blocking LH release and ovulation after injection at 09.30 h. Although LH levels and the numbers of ova released were inversely related to the dose of Haldol administered at 13.30 h, well-defined LH surges were still present and the occurrence of ovulation was not significantly inhibited. Haldol was found to block LH release and ovulation, however, when injected at 13.30 h at the highest dosage level (4.0 mg/kg). The fact that low doses of Haldol blocked in the morning but not in the afternoon indicates that the morning blockade must be mediated by a secondary action of the drug which required a certain period of time to be effective. The blockade by the high dose of Haldol in the afternoon, however, was probably due to a direct action on LH releasing mechanisms.

Function and expression of a human idiotypic network in Schistosomiasis japonica

The cross-reactive idiotype (Hu-SJ-CRIM) is defined by polyclonal human anti-idiotypic antibodies derived from chronically S. japonicum infected patients. The present study shows that serum levels of Hu-SJ-CRIM expressed by antibodies to S. japonicum soluble egg antigen (SEA) are associated with acute infection and hepatosplenic disease. Xenogeneic anti-idiotypic antisera (anti-Hu-SJ-CRIM) suppressed human lymphocyte blastogenesis to SEA in vitro by 47-82% (P < 0.05). These anti-idiotypic antibodies also suppressed in vitro granuloma formation induced by SEA coated heads in a dose dependent manner. This immunosuppression was antigen specific in that mitogen (PHA) or non-related antigen (PPD) induced blastogenic responses were not suppressed. Surprisingly, anti-idiotypic antibodies (anti-SJ-CRIM), which describe the mouse correlate CRIM were not suppressive in the human blastogenesis or in vitro granuloma formation assays. These data indicate a dichotomy in the function and specificity of the idiotype/anti-idiotype human and murine immune networks in S. japonicum infection. Thus, only the patient derived molecules and serology form the basis for an immunoregulatory network in Schistosomiasis japonica.

Effects of sesquiterpene lactones on the growth of Bacillus thuringiensis

Two sesquiterpene lactones, hymenovin and tenulin, were tested for their effect on growth of two strains of Bacillus thuringiensis. Growth of both strains was 98% inhibited by 0.6 mg of tenulin per ml, but only 15 to 20% was inhibited by the same level of hymenovin. Hymenovin appeared to have a mutagenic effect on B. thuringiensis cultures resulting in production of several variant strains. Some of the variant strains had lost their ability to form spores and crystals. Hymenovin also induced B. thuringiensis to produce significant levels of bacteriophage. All variant strains were as susceptible to phage as the parent strain. Although the bactericidal activity of tenulin was two times as great as of hymenovin, tenulin did not appear to have a mutagenic effect on the bacteria.