Use and value of serologic tests for the diagnosis of systemic candidiasis in cancer patients: A prospective study of 146 patients

Sera from 146 cancer patients at risk for disseminated candidiasis were studied prospectively with immunodiffusion (ID), counterelectrophoresis (CEP), and latex agglutination (LA) tests to determine their diagnostic value in the detection of antibodies to theCandida species. Serial serum samples, cultures, and clinical data were obtained after a malignancy was diagnosed. Patients were classified into three groups (I, II, and III) on the basis of cultural, histological, and clinical evidence for superficial (Group I) versus disseminated (Group III)Candida infection. Thirty-two of 78 patients (41%) in Group I had positive ID, CEP, and LA titers. In Group II, those patients lacking histological confirmation of disseminated infection, 16 of 18 (89%) had positive titers. Thirty-six of 50 (72%) in Group III were positive by all three tests. Heavy colonization of the gastrointestinal tract, without evidence of tissue invasion, produced positive test results. Negative serologic tests were encountered in immunosuppressed patients with rapidly progressive candidiasis.C. krusei infections produced specific antibody titers detected by the homologous antigen but not byC. albicans antigen. Stable or decreasing LA titers were correlated with clinical improvement in patients receiving effective antifungal therapy.     

The sub-membrane reticulum of the human erythrocyte: A scanning electron microscope study

A web-like reticulum underlying the human erythrocyte membrane was studied at a resolution of 5–10 nm by means of a scanning electron microscope. The network was visualized in isolated membranes (ghosts) torn open to reveal their interior space and in residues derived from ghosts extracted with Triton X-100. It formed a continuous (rather than patchy) cover over the entire cytoplasmic surface, except where lifted off or torn away. Filaments (5–40 nm in diameter), annular figures (40–60 nm in diameter), and nodes (30–100 nm in diameter) were prominent in different networks. The dimensions of the filaments and the interstices in the reticulum varied with conditions, suggesting that the network has elastic properties. This reticulum is probably related to the erythrocyte membrane proteins spectrin and actin.     

Tomato alcohol dehydrogenase: Purification and substrate specificity

Alcohol dehydrogenase of tomato (Lycopersicon esculentum) has been purified to homogeneity, using affinity chromatography on Cibacron F3GA-agarose. The enzyme is a dimer, M_r 90,000–100,000. The coenzyme is NAD⁺; no NADP⁺-dependent activity was detected even in crude extracts. Among saturated substrates, ethanol and acetaldehyde show the lowest apparent K_m values (2.67 and 0.174 mm, respectively) and highest V values, supporting a primary role in acetaldehyde metabolism, with action also on “flavor aldehydes”; 2-unsaturated alcohols show still lower K_m values, probably due to a more favorable K_eq. This enzyme and other plant alcohol dehydrogenases form a definite class, intermediate in specificity between liver and yeast alcohol dehydrogenases: they differ from the former in being essentially inactive on secondary and aromatic substrates, from the latter in showing only a mild decrease in V with increasing chain length of alkyl substrates, and from both in showing the lowest K_m as well as highest V on ethanol and acetaldehyde. The tomato enzyme differs from other reported plant enzymes in showing substantial activity on geraniol. Kinetic studies are in agreement with an ordered sequential mechanism. The enzyme is inhibited slowly by iodoacetamide, and reversibly by acetamide and zinc-chelating compounds.     

The structure of human mitochondrial DNA variation

Summary Restriction analysis of mitochondrial DNA (mtDNA) of 3065 humans from 62 geographic samples identified 149 haplotypes and 81 polymorphic sites. These data were used to test several aspects of the evolutionary past of the human species. A dendrogram depicting the genetic relatedness of all haplotypes shows that the native African populations have the greatest diversity and, consistent with evidence from a variety of sources, suggests an African origin for our species. The data also indicate that two individuals drawn, at random from the entire sample will differ at approximately 0.4% of their mtDNA nucleotide sites, which is somewhat higher than previous estimates. Human mtDNA also exhibits more interpopulation heterogeneity (G_ST=0.351±0.025) than does nuclear DNA (G_ST=0.12). Moreover, the virtual absence of intermediate levels of linkage disequilibrium between pairs of sites is consistent with the absence of genetic recombination and places constraints on the rate of mutation. Tests of the selective neutrality of mtDNA variation, including the Ewens-Watterson and Tajima tests, indicate a departure in the direction consistent with purifying selection, but this departure is more likely due to the rapid growth of the human population and the geographic heterogeneity of the variation. The lack of a good fit to neutrality poses problems for the estimation of times of coalescence from human mtDNA data.     

Carbon Flow in Mercury Biomethylation by Desulfovibrio desulfuricans

Radiocarbon incorporation from pyruvate and serine into monomethylmercury by Desulfovibrio desulfuricans was consistent with the proposal that the methyl group originates from C-3 of serine. Immunodiagnostic assays measured 4 to 35 μg of tetrahydrofolate and 58 to 161 ng of cobalamin or a closely related cobalt porphyrin per g of cell protein in D. desulfuricans. The light-reversible inhibition of mercury methylation by propyl iodide in D. desulfuricans indicates methyl transfer by a cobalt porphyrin.     

The sensory functions of the cerebellum of the thornback ray,Platyrhinoidis triseriata

Summary Single unit spikes and evoked field potentials were recorded in different parts and depths of the corpus cerebelli and auricle of immobilized rays before and after stimulating with light, electric fields, touch, tail bending and direct shock to mechanoreceptive nerves of the lateral line.Discrete areas of the cerebellum are responsive to these modalities and the areas show limited overlap; they are all distinct from the area reported by Plassmann to be responsive to angular acceleration. The visual and tactile-proprioceptive areas are large; the electric area is small. Most units are excited only by one modality.The tail is represented only in the posterior lobe; trigeminal innervation extends from the posterior onto the anterior lobe, suggesting some topographic projection.The dynamic characteristics of the responses were examined particulary in the visual units. To a flash, units discharge up to six bursts of spikes in 500 ms. This pattern is reduced at repetition rates > 1/s; above ca. 4/s units tend to fire irregularly. Various kinds of units are found in respect to the succession of responses to short trains of flashes. Some units fire much better to objects moving in a limited visual field with a certain direction and rate.Abbreviation EP evoked potential     

Inhibition of porphobilinogen synthase by heme and an enol-ether amino acid

The enol-ether amino acid, L-2-amino-4-methoxy-$\text{trans}$-butenoic acid (AMTB) is an inhibitor of porphobilinogen synthase (PBG synthase) when added prior to the addition of the substrate δ-aminolevulinic acid. The inhibition of PBG synthase by several stereoisomers and analogues of AMTB was investigated to determine those structural features of AMTB which may be necessary for inhibition. The D-$\text{trans}$ isomer was also an inhibitor after preincubation, whereas the L-$\text{cis}$ isomer inhibited with or without preincubation. The amino acid analogues, DL-vinylglycine, DL-2-aminobutanoic acid, the reduced form of L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid, L-2-amino-4-(2-aminoethoxy)-$\text{trans}$-3-butenoic acid and its reduced congener did not inhibit PBG synthase even with preincubation. This structure activity relationship indicates that the $\text{trans}$ double bond and methoxy moiety of L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid are probably required for inhibition.Heme, when preincubated with PBG synthase, was an inactivator of the enzyme. However, when both L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid and heme were simulatneously preincubated with PBG synthase, inactivation of the enzyme was greater than with either compound separately. The possibility of multiple catalytic sites was suggested by the use of multiple inhibition kinetics in the presence of heme and L-2-amino-4-methoxy-$\text{trans}$-3-butenoic acid.