Raman imaging of hemozoin within the food vacuole of Plasmodium falciparum trophozoites

Micro-Raman spectra of hemozoin encapsulated within the food vacuole of a Plasmodium falciparum-infected erythrocyte are presented. The spectrum of hemozoin is identical to the spectrum of beta-hematin at all applied excitation wavelengths. The unexpected observation of dramatic band enhancement of A(1g) modes including nu(4) (1374 cm(-1)) observed when applying 780 nm excitation enabled Raman imaging of hemozoin in the food vacuole. This unusual enhancement, resulting from excitonic coupling between linked porphyrin moieties in the extended porphyrin array, enables the investigation of hemozoin within its natural environment for the first time.     

Thioredoxin reductase and cancer cell growth inhibition by organotellurium compounds that could be selectively incorporated into tumor cells

The thioredoxins are small ubiquitous redox proteins with the conserved redox catalytic sequence-Trp-Cys-Gly-Pro-Cys-Lys, where the Cys residues undergo reversible NADPH dependent reduction by selenocysteine containing flavoprotein thioredoxin reductases. Thioredoxin expression is increased in several human primary cancers including lung, colon, cervix, liver, pancreatic, colorectal and squamous cell cancer. The thioredoxin/thioredoxin reductase pathway therefore provides an attractive target for cancer drug development. Organotellurium steroid, lipid, amino acid, nucleic base, and polyamine inhibitors were synthesized on the basis that they might be selectively or differentially incorporated into tumor cells. Some of the newly prepared classes of tellurium-based inhibitors (lipid-like compounds 3b and 3e, amino acid derivative 5b, nucleic base derivative 8b, and polyamine derivatives 14a and 14b) inhibited TrxR/Trx and cancer cell growth in culture with IC(50) values in the low micromolar range.     

Blood lactate and stroke parameters during front crawl in elite swimmers with disability

The purpose of this investigation was to compare the blood lactate concentration ([La]), stroke distance (D(s)), and swim index (SI) during an incremental swim test (IST) in elite swimmers who had a loss in mobility (LM) (n = 6) or who had full mobility (FM) (n = 5) of the lower limbs. The IST consisted of 5 repeats of either 100 or 200 m front crawl depending upon the ability level of the swimmer. The [La] and heart rate measured during the IST showed no significant differences (p > 0.05). However, velocity (V(s)) and D(s) were all significantly lower (p < 0.01) during the IST. SI was significantly (p < 0.01) lower during repeats 1 to 3 and 5, but not repeat 4. These data indicate that the [La] response to incremental exercise is similar during incremental front crawl activity in swimmers suffering from loss of lower limb mobility. However, a critical V(s) is reached in LM swimmers where swimming efficiency is optimal compared with FM swimmers.     

Forage nutritive quality in the Serengeti ecosystem: the roles of fire and herbivory

Fire and herbivory are important determinants of nutrient availability in savanna ecosystems. Fire and herbivory effects on the nutritive quality of savanna vegetation can occur directly, independent of changes in the plant community, or indirectly, via effects on the plant community. Indirect effects can be further subdivided into those occurring because of changes in plant species composition or plant abundance (i.e., quality versus quantity). We studied relationships between fire, herbivory, rainfall, soil fertility, and leaf nitrogen (N), phosphorus (P), and sodium (Na) at 30 sites inside and outside of Serengeti National Park. Using structural equation modeling, we asked whether fire and herbivory influences were largely direct or indirect and how their signs and strengths differed within the context of natural savanna processes. Herbivory was associated with enhanced leaf N and P through changes in plant biomass and community composition. Fire was associated with reduced leaf nutrient concentrations through changes in plant community composition. Additionally, fire had direct positive effects on Na and nonlinear direct effects on P that partially mitigated the indirect negative effects. Key mechanisms by which fire reduced plant nutritive quality were through reductions of Na-rich grasses and increased abundance of Themeda triandra, which had below-average leaf nutrients.     

Recharacterization of fungal dinucleoside polyphosphate (HS3)

Three polyphosphorylated dinucleosides given the pseudonyms of HS3, HS2, and HS1 that were erroneously described as diguanosine polyphosphates (LéJohn, H. B., Cameron, L. E., McNaughton, D. R. & Klassen, G. R. (1975) Biochem, Biophys, Res, Commun. 66, 460-467) have been repurified and partially recharacterized. They have proved to be extremely complex molecules; chemical (HCl and KOH hydrolysis), physical (ultraviolet-light spectral analysis and ion-exchange chromatography), and enzymic (nucleotide pyrophosphatase and bacterial alkaline phosphatase hydrolysis) studies showed that (i) all three HS compounds are uracil rich and (ii) only HS3 contains a purine nucleoside and glutamate. The partial structure of HS3 was deciphered as a moiety of ADP--sugar X--glutamate (the mode of attachment of glutamate is obscure) that is covalently linked to another moiety composed of UDP, mannitol, and four phosphates. Sugar X had chromatographic characteristics of ribitol, but the chromatographic isolate also contained a ninhydrin-sensitive entity presumed to be an amino group. Sugar X, THEREFore, may be an amino sugar polyol. Only the general chemical compositions of HS2 and HS1 were determined. Each contained two uridines and HS2 had 10 phosphates whereas HS1 had 12.     

The Use of Corticosteroid (Dexamethasone) in the Treatment of Acute Laryngotracheitis

Many practitioners have considered that steroids, with their anti-inflammatory properties, should be efficacious in the treatment of acute laryngotracheitis. To examine this theory, 200 consecutive cases of acute laryngotracheitis admitted to The Hospital for Sick Children, Toronto, were included in a double-blind study using dexamethasone-21-phosphate and placebo according to a random selection code. All other therapy was kept constant. Each patient was assessed by one observer according to seven clinical parameters.The results of this study were subjected to statistical analysis and significantly favoured the steroid-treated group in four parameters only. In view of the risks inherent in steroid therapy, this degree of difference is not sufficient to warrant routine use of this drug for patients with acute laryngotracheitis.     

Film Reviews

Book reviewed in this article:
The Tree of Iron . 1988. A film by Peter O'Neill, Frank Muhly, Jr ., and Peter Schmidt
The Blooms of Banjeli: Technology and Gender in African Ironmaking . 1986. A film by Carlyn Saltman, Candice Goucher , and Eugenia Herbert     

GENETIC AND ENVIRONMENTAL CONTROL OF GLYCOLIC ACID OXIDASE ACTIVITY IN ECOTYPIC POPULATIONS OF TYPHA LATIFOLIA

Glycolic acid oxidase activity at 25 C in leaf homogenates of ecotypic populations of Typha latifolia varied according to native climate of the population and current growing conditions. Activity of plants grown under warm/short day conditions was positively correlated with maximum summer temperature at the site of population origin. Activity of plants grown under cool/ long day conditions was negatively correlated with length of growing season at the site of origin. Populations from sites characterized by a long growing season are much less susceptible to environmental regulation of enzymic level than populations originating in short growing season sites. Enzyme activity is not a secondary reflection of differentiation at the level of chlorophyll or cofactor concentration. Enzymic differences between ecotypic populations reflect differences in control systems at the level of protein synthesis and genetic structure.     

Rubella Virus Infections During Pregnancy,Toronto, 1963-66

Among 670 pregnant women who attended the antenatal clinics of two Toronto city hospitals and one suburban hospital between May 1963 and January 1966, 29 of 550 patients apparently acquired rubella neutralizing antibodies, including 12 whose initial sera were collected during the first trimester. None developed overt rubella. Although rubella antibodies were detected in 61 to 79% of mothers aged 20 years or more, and antibody conversions were detected in 4 to 10% of mothers in each five-year age group between 16 and 39 years, tho rubella syndrome did not appear among any of their offspring. Five of seven other infants, aged 4 to 22 weeks, with the rubella syndrome excreted rubella virus. Rubella neutralizing antibodies were detected in all seven of these infants; these persisted at least 56 weeks in one subject. One mother who received gamma globulin during the first trimester was delivered of an infant who showed signs of the rubella syndrome.