The assay of 4-hydroxy-3-methoxymandelic acid in urine by HPLC with electrochemical detection using bonded-phase silica sorbents for rapid, simple and selective extraction

A method is reported for the determination of 4-hydroxy-3-methoxymandelic acid (HMMA) by HPLC with electrochemical detection. The preparation of sample prior to HPLC has been studied and an efficient and selective extraction procedure described. Bonded-phase silica extraction columns and a vacuum manifold were used for the simple and rapid processing of batches of urine samples. Combining a reverse-phase C18 and an anion exchange column ensures selective isolation of HMMA. This simplified greatly the subsequent chromatography. The method was combined into a simple scheme for the routine analysis of urine HMMA, catecholamines and 5-hydroxyindole-3-acetic acid. The HPLC was standardised such that a single mobile phase was used with minor modification for each of the assays.

The colonization of patients in an intensive treatment unit with gram-negative flora: the significance of the oral route

An extensive survey of patients and the environment in a newly refurbished intensive care unit showed that the principle species on patients in sites other than the rectum were Pseudomonas aeruginosa, Klebsiella pneumoniae, Serratia marcescens, Acinetobacter anitratus and Enterobacter cloacae. Multiple episodes of cross-infection were occurring with 10 different strains of these organisms. Three oral solutions (mouthwashes, 'Clinifeeds' and residual water from nasogastric aspiration apparatus) were heavily contaminated with coliforms including some epidemic strains and this corresponded with the finding that colonization with the above species usually occurred first in the mouth or respiratory tract. Attempts to eliminate contamination of the solutions reduced colonization and cross-infection by over 50%, but did not eradicate it. Two sinks without heat-traps on the drains possibly provided a long term reservoir of epidemic strains.

Laser lateralization for bilateral vocal cord abductor paralysis

Unilateral laser excision of the thyroarytenoid muscle combined with suture lateralization of the vocal ligament was successful in 13 of 14 patients (93%) treated for bilateral abduction immobility sufficient to require tracheotomy. Among the four patients requiring revision surgery, three had cricoarytenoid fixation and one had vocal cord paralysis. All patients had a satisfactory voice after surgery. The anesthetic management of laser microsurgery is discussed.

Impaired intestinal absorption of riboflavin in experimental uremia

Increased plasma and red blood cell concentrations of riboflavin have been reported in uremia. The possible role of altered intestinal absorption of riboflavin in the genesis of this abnormality is not known. For this reason we examined the intestinal absorption of riboflavin in rats made uremic by subtotal nephrectomy and sham-operated (control) rats in vivo using the recycling perfusion technique and in vitro using the everted-sac technique. Paradoxically, the results showed a significant impairment of intestinal absorption of riboflavin in vivo in uremic rats compared to the control group. However, no significant difference was observed in riboflavin transport in vitro. We conclude that the intestinal absorption of riboflavin is decreased in experimental uremia and cannot account for the reported increase in its plasma and red blood cell concentrations.

A rhodopsin is the functional photoreceptor for phototaxis in the unicellular eukaryote Chlamydomonas

Rhodopsin is a visual pigment ubiquitous in multicellular animals. If visual pigments have a common ancient origin, as is believed, then some unicellular organisms might also use a rhodopsin photoreceptor. We show here that the unicellular alga Chlamydomonas does indeed use a rhodopsin photoreceptor. We incorporated analogues of its retinal chromophore into a blind mutant; normal photobehaviour was restored and the colour of maximum sensitivity was shifted in a manner consistent with the nature of the retinal analogue added. The data suggest that 11-cis-retinal is the natural chromophore and that the protein environment of this retinal is similar to that found in bovine rhodopsin, suggesting homology with the rhodopsins of higher organisms. This is the first demonstration of a rhodopsin photoreceptor in an alga or eukaryotic protist and also the first report of behavioural spectral shifts caused by exogenous synthetic retinals in a eukaryote. A survey of the morphology and action spectra of other protists suggests that rhodopsins may be common photoreceptors of chlorophycean, prasinophycean and dinophycean algae. Thus, Chlamydomonas represents a useful new model for studying photoreceptor cells.

A minor class of 5S rRNA genes in Saccharomyces cerevisiae X2180-1B, one member of which lies adjacent to a Ty transposable element

In Saccharomyces cerevisiae the majority of the genes for 5S rRNA lie within a 9kb rDNA sequence that is present as 100-200 tandemly-repeated copies on Chromosome XII. Following our observations that about 10% of yeast 5S rRNA exists as minor variant sequences, we screened a collection of yeast DNA fragments cloned in lambda gt for 5S rRNA genes whose flanking sequences differed from those adjacent to 5S rRNA genes of the rDNA repeat. Three variant 5S rRNA genes were isolated on the basis of such dissimilarity to rDNA repeat sequences. They display a remarkable conservation of their DNA in the vicinity of the 5S coding region, and are examples of a minor form of 5S rRNA coding sequence present in a small number of copies in the yeast genome. These variant sequences appear to be transcribed as efficiently as 5S rRNA genes of the rDNA repeat. In one of our isolates of the variant sequence a Ty transposable element is inserted 145bp upstream of the initiation point for 5S rRNA synthesis.

Processing of the 3' sequence extensions upon the 5S rRNA of a mutant yeast in Xenopus laevis germinal vesicle extract

A processing endonuclease acts to remove a short sequence from the 3' end of transcripts of the Saccharomyces cerevisiae 5S ribosomal RNA gene in generating the mature sequence of 5S RNA. Cells bearing the nuclear mutation rna82 .1 lack this activity and accumulate 5S forms with additional nucleotides at their 3' termini. 5S RNAs labelled during short pulse- labellings of the mutant are essentially primary transcripts that mostly have the sequence U-U-A-U-U-U-C[U-U-U-U(U-U)] added to the 3' end of normal yeast 5S RNA. They are subjected in vivo to a series of slow processing events whereby this sequence is ultimately replaced by: U-U(A)1-9 in a substantial proportion of the 5S RNA molecules of the mutant [Piper, P. W., Bellatin , J. A. and Lockheart , A. (1983) EMBO J. 2, 353-359]. In higher eukaryotes no endonuclease cleavage occurs during 5S RNA maturation, yet processing at the 3' ends of certain transcripts made by RNA polymerase III, most notably transfer RNA precursors, is still important. Since the enzymes involved in this processing have not been well characterised, we investigated how the additional sequences upon rna82 .1 yeast 5S RNA are processed in vitro in a system from a higher eukaryote that is often used for studying transcription by RNA polymerase III, the Xenopus laevis germinal vesicle extract. Our results are consistent with slow digestion of these 5S molecules by a 3'----5' exonuclease until they become 122-123 nucleotides in length, whereupon digestion ceases. This activity probably participates in the processing of certain Xenopus RNA polymerase III transcripts.

8-Anilino-1-naphthalenesulphonate, a fluorescent probe for the regulatory light chain binding site of scallop myosin

Regulatory light chain (RLC) dissociation from scallop myofibrils, myosin or its subfragments was accompanied by an increase in binding of the hydrophobic fluorophore, 8-anilino-1-naphthalene-sulphonate (ANS) to the denuded proteins. The binding was monitored by the large increase in fluorescence emission at 460 nm when excited directly at 380 nm or via energy transfer from nearby tryptophan residues at 295 nm. ANS thus provides a convenient probe for following the kinetics of RLC dissociation in the presence of EDTA and its association in the presence of divalent metal ions. The observed RLC dissociation rate constant for myosin at 20 degrees C was 7.5 X 10(-3)S-1. The association rate constant, which was independent of the RLC concentration, was 5 X 10(-3) S-1. Subfragment 1, prepared by digestion of myosin in the presence of divalent metal ions to protect the light chains [S1(+LC)], showed reversible ANS binding qualitatively similar to the parent molecule. However when prepared in the presence of EDTA, subfragment 1 lacked RLC [S1(-LC)], its heavy chain molecular weight was reduced by about 4000 and it lacked the ANS binding region attributed to the RLC site. The tryptic digestion pattern of of S1(+LC) and S1(-LC) suggested that the 4000 difference peptide is at the C-terminus. Tryptic digestion of S1(+LC) has been shown to lead to the production of a regulatory peptide, comprising the two light chains and a heavy chain fragment, which displayed reversible ANS binding on addition of EDTA. Evidence is presented which suggests that this domain is at the C-terminus of subfragment 1.

A study of the biosynthesis of the tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine in a beta-lactam-negative mutant of Cephalosporium acremonium

A cell-free extract of Cephalosporium acremonium (Takeda N-2) was obtained that synthesized the tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine and also the dipeptide delta-(L-alpha-aminoadipyl)-L-cysteine from the corresponding L-amino acids.

Arterial steroid receptors and their putative role in the mechanism of hypertension

Data from clinical and experimental studies indicate that mechanism(s) for action of mineralocorticoids, other than renal, must be involved in the overall effect of mineralocorticoids on circulation--increased peripheral resistance and hypertension. We have postulated existence of such a mechanism in the arterial wall and have looked for the evidence for its presence. We have found high affinity, specific binders for mineralocorticoids, and glucocorticoids, with characteristics of steroid receptors, in the cytosol of rabbit aorta and femoral and carotid arteries. These binders possess physico-chemical properties of steroid receptors and, moreover, they translocate to cell nuclei (as steroid-receptor complexes) and bind to relatively specific "acceptor-sites" on nuclear chromatin. This provides evidence for the existence in the arterial wall of a molecular mechanism for a direct in situ action of mineralocorticoids and glucocorticoids. The mineralocorticoid receptors are not present in veins. We have also found that chronically elevated levels of 11-desoxycorticosterone (DOC) result in a marked increase in permeability of arterial smooth muscle cell membrane to sodium ions; this is in accord with findings of other investigators in the rat. This change presumably leads, through a chain of biochemical events, to increased arterial and arteriolar smooth muscle contractility, increased peripheral resistance and hypertension. Study is in progress to determine whether the effect of DOC on arterial smooth muscle cell-membrane permeability to electrolytes is elicited through the receptor-mediated mechanism for the in situ action of mineralocorticoids in the arterial wall. It is postulated that this mechanism is primarily responsible for "mineralocorticoid hypertension", but may well be instrumental also in pathogeneses of various other forms of hypertension, including "essential".

Altered lipid profile in liver amoebiasis and its emendation with metronidazole treatment

Liver amoebic abscess was produced by introducing 16,000 trophozoites of Entamoeba histolytica directly into the livers of growing hamsters. A group of the infected animals received orally 64 mg metronidazole/kg body weight for 5 days from the day of the infection. The treated group was autopsied 7 or 14 days after the treatment. Histologically, liquefaction of large parenchymal areas and biochemically, elevation in cholesterol, triglycerides, bile acids and decrease in phospholipids were observed in infected livers. The infected hamsters exhibited hyperlipidemia and hypocholesterolemia. With metronidazole treatment all the values tended to shift towards control levels. The magnitude of the shift was determined by the post-treatment period.

Orientation of neurite growth by extracellular electric fields

Extracellularly applied steady electric fields of 0.1 to 10 V/cm were found to have marked effects on the neurite growth of single dissociated Xenopus neurons in culture: (1) neurites facing the cathode showed accelerated growth, while the growth of those facing the anode was reduced. Neurites growing relatively perpendicular to the field axis were prompted to curve toward the cathode. (2) More neurites appeared to be initiate from the cathodal side of the cell. (3) The number of neurite-bearing neurons per culture and the average neurite length were increased. These effects are absent in cultures treated with electric fields of similar strength but alternating polarity and cannot be attributed either to a gradient of extracellular diffusible substances or to the flow of culture medium produced by the field. The field effects are reversible: (1) removal of the electric field resulted in the loss of neurite orientation in a few hours and (2) reversal of the polarity of the electric field led to a rapid reversal in the neurite orientation. To determine the cellular loci of these field effects, we treated the neurons with a number of pharmacological agents or altered their ionic environments. Incubation with concanavalin A (Con A) was found to abolish these filed effects completely. Since the binding of Con A to the neuronal surface was shown to prevent field-induced accumulation of the Con A receptors toward the cathodal side of these neurons, our finding is accumulation of the Con A receptors toward the cathodal side of these neurons, our finding is consistent with the notion that cathodal accumulation of growth-controlling surface glycoproteins by the field is the underlying mechanism of the field-induced orientation of neurite growth toward the cathode.

Studies on high affinity binding of mineralo- and glucocorticoids in rabbit aorta cytosol

High affinity, specific binding-sites to mineralocorticoids and glucocorticoids, with characteristics of steroid receptors, have been found in rabbit aorta cytosol. Binding parameters (dissociation constants and number of binding sites per mg of cytosol protein) were determined from Scatchard plots, after statistical treatment of the data with the aid of a computer program, for the following tritiated steroids: 11-desoxycorticosterone (DOC), aldosterone (Aldo), progesterone (Prog), corticosterone (BK), cortisol (FK) and dexamethasone (Dex). The specificity of binding was then examined by means of steroid competition studies. The results of these experiments indicate that three different types of high-affinity binding sites to adrenal steroids are present in aorta cytosol: Type A, with the highest affinity for DOC; Type B, with the highest affinity for FK; Type C, with the highest affinity for Dex. In accordance with the relative competitive potencies of various steroids for these binding sites, Type A is designated as the "arterial mineralocorticoid binder", clearly differing in its binding characteristics from the cytoplasmic mineralocorticoid binders in known target tissues to these steroids (e.g. the renal receptor), while Type C is designated as the "arterial glucocorticoid binder", closely resembling the classical glucocorticoid receptor in known target tissues to glucocorticoids. Type B exhibited some of the binding characteristics of transcortin and may represent a modified, intracellular transcortin. While Types B and C are present also in the cytosol of inferior vena cava. Type A was only in the aorta. The role of these binders is not known at present. Arguments are presented in favor of a hypothesis that the Type A (mineralocorticoid) binder represents an arterial wall; and that, under certain conditions, this action leads to an increased contractility of arterial and arteriolar smooth muscles, increased peripheral resistance and hypertension.

Recovery of o'nyong-nyong virus from Anopheles funestus in Western Kenya

O'nyong-nyong (ONN) virus first appeared nearly 20 years ago and was responsible for one of the largest arbovirus outbreaks ever documented. Since the original outbreak ended, ONN activity, as determined serologically, gradually declined on the Kano Plain in western Kenya. In June, 1978, a virus similar or identical to ONN was isolated from a pool of Anopheles funestus Giles captured at Ahero on the Kano Plain. The possible implications of this isolation are discussed.