A survey of doctorates by thesis among general practitioners in the British Isles from 1973 to 1988.

Doctors who were general practitioners in the period 1973-88 and had written a successful MD or PhD thesis were identified. Of 96 doctorates, 64 were MDs and 32 PhDs. Fourteen doctors had obtained their MD before becoming general practitioners and the remaining 50 after becoming general practitioners.

Methyl vinyl sulphone: a new class of Michael-type genotoxin.

Methyl vinyl sulphone (MVS) is a labile, Michael-reactive chemical, similar in structure to acrylamide (AA). Given that acrylamide is a reference mammalian mutagen and a rodent carcinogen, studies were undertaken to evaluate the potential genotoxicity of MVS. In common with AA, MVS was non-mutagenic to Salmonella but active as an aneugen to cultured mammalian cells.

A comparison of the results of sequential hydrazinolysis-nitrosation and alkali-mediated cleavage-nitrosation of the O-linked oligosaccharides of gastric mucus glycoproteins.

Analysis of the oligosaccharides released from pig gastric mucus glycopolypeptides by hydrazinolysis showed that degradation had occurred. Nitrosation of the products followed by reduction gave a mixture that had a low content of 2,5-anhydro-D-talitol, which implied destruction of much of the terminal reducing 2-amino-2-deoxy-D-galactose. Under the conditions of hydrazinolysis, cellobiose was largely unchanged but laminaribiose gave a complex mixture that probably contained glucose hydrazone (13C-n.

Rapid co-transport of sodium and chloride ions in giant salivary gland cells of the leech Haementeria ghilianii.

1. Double-barrelled Cl(-)-selective microelectrodes were used to measure the apparent intracellular Cl- activity (aiCl) and membrane potential (Em) of leech salivary gland cells. In standard physiological solution buffered with HEPES (10 mM), intracellular Cl- activity (corrected for interference) was 38 +/- 8 mM (n = 11) compared to a value of 12.

Direct binding and lectin-mediated binding of erythrocytes to haemocytes of the insect, Extatosoma tiaratum.

Treatment of Extatosoma haemocytes on a monolayer with fixed rabbit erythrocytes (RE) in the presence of Ca2+ results in ca. 11% plasmatocytes (PL) and 58% spreading granular (SG) cells rosetting. Pretreatment of haemocytes with lactose, D-galactose, or asialofetuin reduces rosetting, suggesting that the membrane-associated receptors involved may be lectins.

Mechanism of potassium uptake in neuropile glial cells in the central nervous system of the leech.

1. Ion-selective double-barreled microelectrodes (ISME) were used to measure intracellular K+ (aKi), Na+ (aNai), and Cl- (aCli) activities of neuropile glial (NG) cells in the central nervous system of the medicinal leech Hirudo medicinalis. Ion fluxes were induced by an increase in extracellular K+ concentration [( K+]o) and analyzed to elucidate the ionic mechanism of the K+ uptake occurring under such conditions.

Restriction site mutation analysis, a proposed methodology for the detection and study of DNA base changes following mutagen exposure.

We propose a methodology for the detection of DNA base changes in restriction enzyme recognition sites. The restriction site mutation (RSM) technique is based upon the detection of DNA sequences resistant to the cutting action of specific restriction enzymes and the amplification of these resistant sequences using the polymerase chain reaction. As outlined, the RSM method has the potential for use in the study of induced base changes in any species, tissue and genes of known DNA sequence for which unique DNA primers are available, and which contains a number of unique restriction enzyme recognition sites.

Studies on the cellular defense reactions of the madeira cockroach, Leucophaea maderae: in vitro phagocytosis of different strains of Bacillus cereus and their effect on hemocyte viability.

Monolayers of Leucophaea maderae hemocytes, consisting of mainly plasmatocytes and coagulocytes, were incubated with three strains of Bacillus cereus of differing pathogenicities, and the levels of phagocytosis and hemocyte viability were determined. Incubation with viable B. cereus strains NCTC 2599, NCIB 3329, and B1 resulted in a significant drop in hemocyte viability after 60 min of incubation compared with the saline-only controls.

Ammonium assimilation by the nitrate-utilizing yeast, Candida nitratophila.

Ammonium-nitrogen was assimilated rapidly by nitrogen-replete cultures of the nitrate-utilizing yeast, Candida nitratophila as long as a suitable source of carbon was available. These cultures contained high activities of an NADPH-dependent glutamate dehydrogenase with a relatively high affinity for ammonium (K = 0.27 mM) and high glutamine synthetase activity.

A study of mitotic division fidelity and numerical chromosome changes in ageing Syrian hamster dermal cells.

Events associated with culture ageing in Syrian hamster dermal cells have been studied from the time of culture isolation during continuous passage until they senesced and died. Microscopic examination of mitotic cells using differential staining of chromosome and spindle apparatus assessed the faithfulness of cell division. Other indicators of the quality of cell division were obtained from chromosome counts, micronucleus frequencies and incidences of binucleate cells.

Schizophrenia and indeterminacy: the problem of validity.

The paper attempts to account for the confusion over the validity of the concept of 'schizophrenia' in terms of two closely related aspects of conceptual indeterminacy. Firstly, it is identified on the basis of a breakdown in intelligibility, but what constitutes such a breakdown is indeterminate. Secondly, the concept sits between the categories of natural disease or illness on the one hand, and character trait or moral failing or gift on the other.

Cytidylate cyclase: development of assay and determination of kinetic properties of a cytidine 3',5'-cyclic monophosphate-synthesizing enzyme.

A method is described for the separation of cytidine 3',5'-cyclic monophosphate (cyclic CMP) from cytidine tri-, di- and mono-phosphates and from cytidine 3',5'-cyclic pyrophosphate, cytidine 2'-monophosphate-3',5'-cyclic monophosphate, cytidine 2'-O-aspartyl-3',5'-cyclic monophosphate and cytidine monophosphate, compounds previously shown to be the result of putative cytidylate cyclase activity. This separation, involving elution of a novel bilayer column of QAE-Sephadex and alumina with 0.03 M-HCl, has been incorporated into an assay protocol to determine the enzyme-catalysed conversion of radiolabelled CTP to cyclic CMP.

DNA alkylations and mutation after exposure to ethyl methanesulphonate in mammalian cell lines routinely used in mutagenicity testing.

DNA ethylations were measured in four mammalian cell lines, Chinese hamster ovary CHO, mouse lymphoma L5178Y t k+/-, human lymphoblastoid TK6 and Chinese hamster V79, following exposure to [3H]ethyl methanesulphonate. Concurrent estimates of cytotoxicity and gene mutation were also carried out. Total DNA-binding and relative levels of ethylation at N-7 guanine (N-7G), O6 guanine (O6G) and N-3 adenine (N-3A) were essentially the same in all four cell lines.

Activity and preliminary characterization of Branchiostoma lanceolatum agglutinin.

The physical and chemical properties of a hemagglutinin from whole-body homogenates of the cephalochordate, Branchiostoma lanceolatum, are described. The hemagglutinin is proteinaceous since it is precipitated by trichloroacetic acid and ammonium sulphate, and all activity is lost at 60 degrees C or by treating with proteases. Carbohydrate moieties are probably also present since activity is lost after incubation with sodium metaperiodate.

Biosynthesis of the tropane-related cyanobacterial toxin anatoxin-a: role of ornithine decarboxylase.

A study was made of the biosynthesis by Anabaena flos-aquae of the tropane-related alkaloid anatoxin-a. Evidence is presented that the toxin arises from ornithine via putrescine (1,4-diaminobutane) and that ornithine decarboxylase (EC 4.1.

Lipoxins are major lipoxygenase products of rainbow trout macrophages.

Rainbow trout macrophages synthesize lipoxins as major lipoxygenase products entirely from endogenous fatty acids. High-performance liquid chromatographic analysis of the supernatants from macrophages challenged with calcium ionophore A23187 revealed a range of lipoxygenase products including mono-hydroxy fatty acids, leukotrienes B4 and B5 and four major peaks with retention times and UV spectra characteristic of lipoxins (lambda max 302 nm). Cochromatography with authentic standards, UV spectroscopy and radiolabeling with [14C]arachidonate and eicosapentaenoate allowed tentative identification of the two largest peaks as lipoxin A4 and A5.

Effect of type of opponent on aggression in male mice with particular reference to studies with antihormones.

The potential influence of the type of opponent used in intermale aggression encounters to assess the actions of drugs was examined. Two experiments were carried out, one with the antiandrogen Cyproterone Acetate and the other with the antioestrogen CI-680 (both administered every three days over 25 days). In both experiments the antihormone-treated subjects encountered different opponents, namely: a) an antihormone-treated male, b) a non aggressive anosmic male or c) a vehicle-treated male.

Inorganic-carbon transport in some marine eukaryotic microalgae.

Inorganic-carbon transport was investigated in the eukaryotic marine microalgaeStichococcus minor, Nannochloropsis oculata and aMonallantus sp. Photosynthetic O2 evolution at constant inorganic-carbon concentration but varying pH showed thatS. minor had a greater capacity for CO2 rather than HCO 3 (-) utilization but forN.

Measurement of internal pH in the coccolithophoreEmiliania huxleyi using 2',7'-bis-(2-carboxyethyl)-5(and-6)carboxyfluorescein acetoxymethylester and digital imaging microscopy.

Internal pH (pHi) was determined inEmiliania huxleyi (Lohmann) using the probe 2',7'-bis-(2-carboxyethyl)-5(and-6)carboxyfluoresceinacetoxymethylester (BCEF-AM) and digital imaging microscopy. The probe BCECF-AM was taken up and hydrolysed to the free acid by the cells. A linear relationship was established between pHi and the 490/450 fluorescence ratio of BCECF-AM over the pH range 6.