Simultaneous determination of 4-hydroxy-3-methoxy-phenylacetic (homovanillic) acid and other monoamine metabolites in human lumbar cerebrospinal fluid : An improved high-performance liquid chromatographic study with electrochemical detection

We describe a direct analysis for the simultaneous quantitative determination of 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid and other monoamine metabolites in human lumbar cerebrospinal fluid, utilizing reversed-phase high-performance liquid chromatography with amperometric detection. In addition, a rapid isocratic separation was developed for homovanillic acid in the presence of other endogenous compounds.Twenty-five unselected diagnostic specimens of human lumbar cerebrospinal fluid were extracted with ethyl acetate and subsequently analyzed using the described method. Chromatographic peaks were identified on the basis of retention behavior and ratio of responses at several oxidation potentials.Although our quantitative results correlate well with the literature values, the data were not interpreted clinically since samples were obtained from routine, diagnostic testing of patients admitted to the medical or neurologic services at the Mount Sinai Hospital.     

Growth and formation of poly (hydroxybutyric acid) by Methylobacterium rhodesianum at methanol concentrations of above 25 g/I

Methylobacterium rhodesianum MB 126 was cultivated using extended cultures without outflow. The feeding regime was based on the pH-regulated synchronous dosages of ammonia, methanol, phosphatc and trace elements according to supposed stoichiometric relations. The acidity of the culture medium was kept constant at pH 6.8, whereas the dissolved oxygen concentration was adjusted at 80% of saturation by autoregulation of the stirrer speed. However, besides testing technical conditions, two types of fermentations were discovered which are described in this paper. Firstly, although at the beginning of the bioprocesses the impeller speed increased up to 2,000 rpm, a decrease of dissolved oxygen down to zero was unavoidable. Secondly, methanol was accumulated temporarily up to 44 g/l and 26 g/l at 23 h of fermentation time and without inhibition of growth at least up to 30 g/l or PHB production. During this accumulation of the carbon substrate, exponential growth phases were detected showing growth rates of μ = 0.20/h and 0.21/h. But then, phases of retarded growth followed, whereas the methanol disappeared either continuously or after a steady level. In the course of a 54-h fermentation period, the synthesized PHB amounted to a content of above 50% of cell dry mass. From this data, a volumetric productivity of 0.4 g PHB/lxh was estimated. Moreover, the growth related yield coefficients were calculated to Y_X/MeOH = 0.21 and Y_X/MeOH = 0.14, whereas the product related yield coefficients amounted to Y_PHB/MeOH = 0.12 and Y_PHB/MeOH = 0,09. Since the shift down of growth rates as well as the production of PHB agreed in time with partial oxygen limitation (40% oxygen saturation), the competition observed between the tricarboxylic acid cycle and PHB synthesis was discussed. Summarizing the results, it was concluded that the frequently described inhibitory effect of methanol of above 2 g/l seems to be rather an effect of experimentally chosen conditions than of a general physiological phenomenon. Therefore, it could be demonstrated that the toxicity of methanol could be overcome if it was not dosed at different times but simultaneously with other medium components.     

Neutrophil association and degradation of normal and acute-phase high-density lipoprotein 3.

The interaction of normal and acute-phase high-density lipoproteins of the subclass 3 (N-HDL3 and AP-HDL3) with human neutrophils and the accompanying degradation of HDL3 apolipoproteins have been studied in vitro. The chemical composition of normal and acute-phase HDL3 was similar except that serum amyloid A protein (apo-SAA) was a major apolipoprotein in AP-HDL3 (approx. 30% of total apolipoproteins). 125I-labelled AP-HDL3 was degraded 5-10 times faster than 125I-labelled N-HDL3 during incubation with neutrophils or neutrophil-conditioned medium. Apo-SAA, like apolipoprotein A-II (apo-A-II), was more susceptible than apolipoprotein A-I (apo-A-I) to the action of proteases released from the cells. The amounts of cell-associated AP-HDL3 apolipoproteins at saturation were up to 2.8 times greater than N-HDL3 apolipoproteins; while apo-A-I was the major cell-associated apolipoprotein when N-HDL3 was bound, apo-SAA constituted 80% of the apolipoproteins bound in the case of AP-HDL3. The associated intact apo-SAA was mostly surface-bound as it was accessible to the action of exogenous trypsin. alpha 1-Antitrypsin-resistant (alpha 1-AT-resistant) cellular degradation of AP-HDL3 apolipoproteins also occurred; experiments in which pulse-chase labelling was performed or lysosomotropic agents were used indicated that insignificant intracellular degradation occurred which points to the involvement of cell-surface proteases in this degradation.     

Ultrastructural features of gametogenesis during the life cycle in Branchiura sowerbyi Beddard (Oligochaeta,Tubificidae)

An ultrastructural analysis of the gametogenetic phases in Branchiura sowerbyi, a tubificid oligochaete, has been accomplished. These phases mostly conform to the usual pattern for the family, however, some interesting peculiarities are pointed out. The regression of sexual apparatus after reproductive period and its regeneration up to a new period of sexual maturity, has been followed throughout the year.