Altered red cell membrane fluidity during schizogonic development of malarial parasites (Plasmodium falciparum and P. lophurae)

The plasma membranes of human or duckling erythrocytes infected with malarial parasites (Plasmodium falciparum and P. lophurae respectively) were stained by the fluorescent dye merocyanine 540 in the presence of serum. Unparasitized erythrocytes from infected ducklings or from in vitro cultures remained unstained in the presence of serum. Because merocyanine 540 has a greater affinity for fluid phased or disordered lipid bilayers the results suggest that upon infection of the red blood cell the erythrocyte plasma membrane becomes disordered or is increased in its fluidity. Such alterations of the host erythrocyte are probably due to parasite-induced modifications in the underlying spectrin network (required for lipid leaflet asymmetry) as well as changes in erythrocyte membrane lipid composition.     

Inhibition of mitogenic lectin induced blast transformation in human peripheral blood mononuclear cells by mefloquine

The effect of mefloquine-HCL, a new 4-quinoline methanol anti-malarial compound, on in vitro blast transformation of human peripheral blood mononuclear cells (MNC) was studied. Mefloquine significantly suppressed lectin-induced blast transformation of MNC from healthy Thai adults but MNC responsiveness in the mixed leucocyte reaction (MLR) and cellular viability were not reduced by the concentrations of mefloquine studied. Both T and non-T MNC responsiveness was lower in cultures containing the drug than in normal control cultures. The addition of serum from individuals on mefloquine chemoprophylaxis caused no significant suppression in the blast transformation assays or the MLR but the data do not rule out any clinically significant in vivo suppressive effect by mefloquine on human cellular immune response.     

Attempts to transmit visceral leishmaniasis to man: Remarks on the histopathology of leishmaniasis

Attempts to transmit kala-azar to five human beings suffering from advanced malignant disease by massive injections of cultures of L. donovani in all the cases and additional injections of leishmania from the livers and spleens of infected Syrian hamsters in two cases were negative in four cases during an observation period of from 8 to 17 months.In one case (Case 3) of cylindrical-celled carcinoma of the stomach, the patient became infected after inoculation of cultures of L. donovani. This is the first record of the successful transmission of visceral leishmaniasis in man. The incubation period was less than 5 months.This case was observed for a period of 9 months and during all this time showed no signs or symptoms of kala-azar in spite of a very heavy infection. There was no marked enlargement of the spleen, no fever and no leucopenia.The histological and haematological findings are discussed.The serum of the infected case was lytic for his own strain of L. donovani. The action of normal human serum or flagellates of Leishmania consists of damage to the nuclear wall and the pouring of the nuclear contents into the protoplasm.Two types of cell infection were noted, one in which the protoplasm is packed with parasites as in the case of reticular cells of the spleen and Kupffer cells in the liver, and one in which the cell is relatively slightly parasitized as in the adventitial cells of arteries, trabeculae Of the spleen, Glisson's capsule, the connective tissue forming the stroma of a carcinoma. The infection of the reticular cells of the bone marrow was intermediate between these two types.In spite of their infection Kupffer cells and other infected cells remained actively phagocytic as evidenced by the inclusion in them of plasma cells, lymphocytes and even other infected cells.Connective tissue cells in the stroma of a cylindrical-celled carcinoma and in Glisson's capsule are shown to be potential phagocytes.The factors which determine individual susceptibility to kala-zar are quite unknown.     

Studies on serum requirements for the cultivation of Plasmodium falciparum. 2. Medium enrichment

Previous experiments using RPMI 1640 medium have indicated that the dialysis of human serum removes components of low relative molecular mass (6000-8000 RMM) that are essential for continuous cultivation of Plasmodium falciparum. To determine which low-RMM components are important for parasite development, we compared growth in normal serum to that in dialysed serum using a number of other commercially available media, which we considered to be richer than RPMI 1640. Through these comparisons, we determined that hypoxanthine was the major dialysable nutrient required for parasite development. High quality bovine serum requires 3 - 12 × 10^-5 mol/litre of hypoxanthine as a supplement to support continuous cultures of P. falciparum. Thus far we have been unable to attain parasite growth in medium containing supplemented bovine serum that is as good as growth in medium containing human serum.     

Infection of an Aedes aegypti cell line with infectious arbovirus-antibody complexes

Aedes aegypti cells exposed to infectious complexes of WN or YF virus and homologous antiserum produced lower yields of virus over a 10-day observation period than were produced by Aedes aegypti cells treated with a comparable dose of virus mixed with non-immune serum. When Ae. aegypti cells were infected with WN virus mixed with MVE, NTA, DEN-2 or YF antisera the virus yield over 10 days was lower than in cell cultures infected at similar titres with mixtures of WN virus with non-immune serum. If Ae. aegypti cell cultures were infected with mixtures of YF virus and WN or DEN-2 antiserum the resulting production of virus was lower over 10 days than in virus mixed with non-immune serum.Human serum samples from the field were tested for the presence of antibody by preincubation of the serum with WN virus prior to inoculation on to mosquito cell cultures. The results indicated that this method is as sensitive in detecting antibody as a mouse neutralization test using regression analysis of average survival time.     

Resistant starch and exercise independently attenuate weight regain on a high fat diet in a rat model of obesity

Background

Linoleic acid, with a DRI of 12-17 g/d, is the most highly consumed polyunsaturated fatty acid in the Western diet and is found in virtually all commonly consumed foods. The concern with dietary linoleic acid, being the metabolic precursor of arachidonic acid, is its consumption may enrich tissues with arachidonic acid and contribute to chronic and overproduction of bioactive eicosanoids. However, no systematic review of human trials regarding linoleic acid consumption and subsequent changes in tissue levels of arachidonic acid has been undertaken.

Objective

In this study, we reviewed the human literature that reported changes in dietary linoleic acid and its subsequent impact on changing tissue arachidonic acid in erythrocytes and plasma/serum phospholipids.

Design

We identified, reviewed, and evaluated all peer-reviewed published literature presenting data outlining changes in dietary linoleic acid in adult human clinical trials that reported changes in phospholipid fatty acid composition (specifically arachidonic acid) in plasma/serum and erythrocytes within the parameters of our inclusion/exclusion criteria.

Results

Decreasing dietary linoleic acid by up to 90% was not significantly correlated with changes in arachidonic acid levels in the phospholipid pool of plasma/serum (p = 0.39). Similarly, when dietary linoleic acid levels were increased up to six fold, no significant correlations with arachidonic acid levels were observed (p = 0.72). However, there was a positive relationship between dietary gamma-linolenic acid and dietary arachidonic acid on changes in arachidonic levels in plasma/serum phospholipids.

Conclusions

Our results do not support the concept that modifying current intakes of dietary linoleic acid has an effect on changing levels of arachidonic acid in plasma/serum or erythrocytes in adults consuming Western-type diets.     

Sheep experimentally infected with a human isolate of Anaplasma phagocytophilum serve as a host for infection of Ixodes scapularis ticks

Anaplasma phagocytophilum, first identified as a pathogen of ruminants in Europe, has more recently been recognized as an emerging tick-borne pathogen of humans in the U.S. and Europe. A. phagocytophilum is transmitted by Ixodes spp., but the tick developmental cycle and pathogen/vector interactions have not been fully described. In this research, we report on the experimental infection of sheep with the human NY-18 isolate of A. phagocytophilum which then served as a host for infection of I. scapularis nymphs and adults. A. phagocytophilum was propagated in the human promyelocytic cell line, HL-60, and the infected cell cultures were then used to infect sheep by intravenous inoculation. Infections in sheep were confirmed by PCR and an Anaplasma-competitive ELISA. Clinical signs were not apparent in any of the infected sheep, and only limited hematologic and mild serum biochemical abnormalities were identified. While A. phagocytophilum morulae were rarely seen in neutrophils, blood film evaluation revealed prominent large granular lymphocytes, occasional plasma cells, and rare macrophages. Upon necropsy, gross lesions were restricted to the lymphoid system. Mild splenomegaly and lymphadenomegaly with microscopic evidence of lymphoid hyperplasia was observed in all infected sheep. Female I. scapularis that were allowed to feed and acquire infection on each of the 3 experimentally infected sheep became infected with A. phagocytophilum as determined by PCR of guts (80–87%) and salivary glands (67–100%). Female I. scapularis that acquired infection as nymphs on an experimentally infected sheep transmitted A. phagocytophilum to a susceptible sheep, thus confirming transstadial transmission. Sheep proved to be a good host for the production of I. scapularis infected with this human isolate of A. phagocytophilum, which can be used as a model for future studies of the tick/pathogen interface.     

Immunogenicity of Entamoeba histolytica antigen fractions

Monobacterial cultures of laboratory isolated strains of Entamoeba histolytica were used for preparing antigenic extracts. Fractionation of water soluble antigenic extracts was carried out on Sephadex G-200 columns. Four different fractions designated as peaks F₁, F₂, F₃ and F₄ were obtained. Eluant fractions from peaks F₁ and F₂ behaved as highly potent antigens against immunized serum samples in precipitin and indirect haemagglutination (IHA) tests. Fractions appearing in peaks F₃ and F₄ did not give any positive reaction in the above two tests. Two of the isolated fractions were also found positive in human amoebic serum samples.     

Nutritional Controlled Preparation and Administration of Different Tomato Purées Indicate Increase of β-Carotene and Lycopene Isoforms,and of Antioxidant Potential in Human Blood Bioavailability: A Pilot Study

The isoforms of lycopene, carotenoids, and their derivatives including precursors of vitamin A are compounds relevant for preventing chronic degenerative diseases such as cardiovascular diseases and cancer. Tomatoes are a major source of these compounds. However, cooking and successive metabolic processes determine the bioavailability of tomatoes in human nutrition. To evaluate the effect of acute/chronic cooking procedures on the bioavailability of lycopene and carotene isoforms in human plasma, we measured the blood levels of these compounds and of the serum antioxidant potential in volunteers after a meal containing two different types of tomato sauce (rustic or strained). Using a randomized cross-over administration design, healthy volunteers were studied, and the above indicated compounds were determined by HPLC. The results indicate an increased bioavailability of the estimated compounds and of the serum antioxidant potential with both types of tomato purée and the subsequently derived sauces (the increase was greater with strained purée). This study sheds light on the content of nutrient precursors of vitamin A and other antioxidant compounds derived from tomatoes cooked with different strategies. Lastly, our study indicates that strained purée should be preferred over rustic purée.     

Changes of copper,iron, and zinc in the serum of patients with silicosis,silicotuberculosis, and active lung tuberculosis

The serum concentrations of copper, iron, and zinc in silicosis were investigated related to the X-ray stage of the disease (according to the I.L.O.-U/C 1971 pneumoconioses international classification), to the TB complication, and to the plasma proteins level. The determination of oligoelements and plasma proteins was performed in 15 subjects suspected of silicosis and in 141 silicotic patients, selected by three criteria: the type criterium (opacity size, p, q, r), category criterium (number of opacities, 1,2,3), and TB complication criterium. The doses of copper, iron, and zinc were also established in 28 active lung TB patients and in a control group. The increase of the copper values in blood serum was noticed, simultaneously with the progress of silicosis, the highest change being found in the subjects with silicotuberculosis and active TB. A decrease of serum iron was also recorded, parallel to the silicosis evolution, as well as a hypozincemia with no variations related to the stage of the silicosis. No correlations were found between the changes of the oligoelements and the changes of plasma proteins.     

Maintenance of infectivity of Trypanosoma congolense in vitro with explants of infected skin at 37 degrees C

Glossina morsitans infected with two stocks of Trypanosoma congolense were fed on rabbits and calves to produce local skin reactions containing trypanosomes. Areas of infected skin were removed from the animals and used to prepare dermal explant cultures in Eagle's MEM and RPMI 1640 culture medium, supplemented with foetal bovine serum and containing penicillin and streptomycin. Cultures were incubated at 37 °C and media were changed at 24 to 48 hour intervals to maintain pH 7·0 to 7·2. There was evidence of trypanosome multiplication in explant cultures set up in both media; one trypanosome stock was maintained equally well in both Eagle's MEM and RPMI 1640, but the other stock survived better in Eagle's MEM. Explant cultures prepared from calf tissues generally yielded more trypanosomes at 24 hours than those prepared from rabbit tissues. The numbers of parasites present near the explants at 24 hours were maintained for up to 14 to 15 days before a decline in parasite concentration occurred. The organisms retained typical blood stream trypomastigote morphology and were infective for mice for periods up to 21 days. The trypanosomes growing in primary explant cultures could not be subpassaged in culture media alone or on to monolayers of fibroblast-like cells of bovine, murine or buffalo origin. Attempts to establish primary cultures by placing infected skin explants directly on to similar monolayers were also unsuccessful.     

Serum folate is a reliable indicator of hyperhomocysteinemia and borderline hyperhomocysteinemia in young adults

Serum folate has been shown to correlate well with fasting plasma homocysteine; however, erythrocyte folate concentration is a better index of tissue folate stores and probably could be a more reliable indicator for reflecting long-term supply of the vitamin and homocysteine status. The present study was undertaken to test the hypothesis that serum folate and erythrocyte folate levels had a different degree of correlation to fasting plasma homocysteine in young Taiwanese adults. This study had a cross-sectional design. Healthy young adults were divided into either a hyperhomocysteinemia (HHcy; ≥14.9 μmol/L; n = 13), borderline HHcy (BHcy; fasting homocysteine, 14.9-10.2 μmol/L; n = 52), or normohomocysteinemia (fasting homocysteine, <10.2 μmol/L; n = 65) groups based on fasting homocysteine levels. The concentrations of plasma fasting homocysteine, serum folate, erythrocyte folate, vitamin B₁₂, and plasma pyridoxal 5′-phosphate were measured. Fasting homocysteine was only significantly and inversely affected by serum folate (β = −0.21, P < .05) concentration after adjusting for potential confounders. Only serum folate concentration remained to decrease the risk of fasting HHcy (odds ratio, 0.73; confidence interval, 0.56-0.95) after the other B vitamins were additionally adjusted. Serum folate also had the highest area under the receiver operating characteristic (AUC) curve to predict the risk of HHcy (AUC, 0.81) and BHcy (AUC, 0.77). Serum folate is a reliable indicator of fasting hyperhyperhomocysteinemia and BHcy in young adults.     

Identification of tubercle bacilli from Indian patients with pulmonary tuberculosis

Pretreatment cultures of bacilli from Indian patients with active pulmonary tuberculosis admitted to a controlled domiciliary chemotherapy study by the Tuberculosis Chemotherapy Centre, Madras, were subjected to a series of in vitro tests designed to identify the bacilli as human or bovine tubercle bacilli, or as anonymous mycobacteria. For the purposes of comparison, pretreatment cultures from British patients with pulmonary tuberculosis were examined by the same series of identification tests.     

Activation of complement by Naegleria

Neither Naegleria nor its culture supernatant was found to be directly chemotactic for human neutrophils. Interaction of Naegleria with human serum, however, resulted in the generation of a strong chemotactic stimulus. The reduction of serum activity by heat-inactivation indicated a dependence on serum complement for the interaction. The ability of Naegleria to activate the alternative complement pathway was demonstrated with the use of C2-deficient serum.     

Correlation of phage type, biotype and source in strains of Salmonella typhimurium

A series of 2092 cultures of Salmonella typhimurium isolated from human, animal and other sources in 57 countries were differentiated into 204 phage types and 19 primary and 147 full biotypes. Different biotypes belonged to the same phage type and different phage types to the same biotype, so the combination of typing methods differentiated strains more finely than either method alone: 574 different `phage type/biotypes'' were distinguished in 1937 cultures belonging to the 204 recognized phage types.     

The Impact of Sample Type on Vitamin D Quantification and Clinical Classification during Pregnancy

Measurement of vitamin D status has significant use in clinical and research settings, including during pregnancy. We aimed to assess the agreement of total 25-hydroxyvitamin D (25(OH)D) concentration, and its three analytes (25-hydroxyvitamin D₃ (25(OH)D₃), 25-hydroxyvitamin D₂ (25(OH)D₂) and Epi-25-hydroxyvitamin D₃ (Epi-25(OH)D₃)), in plasma and serum samples collected during pregnancy, and to examine the proportion of women who change vitamin D status category based on sample type. Matching samples were collected from n = 114 non-fasting women between 12–25 weeks gestation in a clinical trial in Newcastle, Australia. Samples were analysed by liquid chromatography-tandem mass-spectrometry (LC-MS/MS) to quantify total 25(OH)D and its analytes and examined using Bland-Altman plots, Pearson correlation (r), intraclass correlation coefficient and Cohen’s Kappa test. Serum total 25(OH)D ranged from 33.8–169.8 nmol/L and plasma ranged from 28.6–211.2 nmol/L. There was a significant difference for total 25(OH)D based on sample type (measurement bias 7.63 nmol/L for serum vs plasma (95% Confidence Interval (CI) 5.36, 9.90, p ≤ 0.001). The mean difference between serum and plasma concentrations was statistically significant for 25(OH)D₃ (7.38 nmol/L; 95% CI 5.28, 9.48, p ≤ 0.001) and Epi-25(OH)D₃ (0.39 nmol/L; 95% CI 0.14, 0.64, p = 0.014). Of 114 participants, 28% were classified as vitamin D deficient (<50 nmol/L) or insufficient (<75 nmol/L) based on plasma sample and 36% based on serum sample. Nineteen (16.7%) participants changed vitamin D status category based on sample type. 25-hydroxyvitamin D quantification using LC-MS/MS methodology differed significantly between serum and plasma, yielding a higher value in plasma; this influenced vitamin D status based on accepted cut-points, which may have implications in clinical and research settings.     

Susceptibility of Serratia marcescens to Human Serum: Antagonism of Serum Bactericidal Activity by IgG Immunoglobulins of Homologous Rabbit Anti-O Sera

Absorption of fresh human serum with boiled or live homologous O-cells of Serratia marcescens in the cold (4 °C, 1 hour) completely abrogated killing activity against “delayed serum-sensitive” (DSS) strains of S. marcescens. In contrast, previously “promptly serum-sensitive” (PSS) strains of S. marcescens and the PSS control strain Escherichia coli C were killed kinetically in a slightly “delayed” fashion by antibody-depleted fresh human serum.Addition of 40 vol% of heat-inactivated homologous rabbit anti-O immune sera to 50 vol% of fresh human serum “blocked” bactericidal activity against DDS and PSS assay strains of S. marcescens. The “blocking” activity of rabbit anti-O immune sera was shown to reside in the crude gamma globulin fractions derived therefrom through precipitation with ammonium sulfate. Absorption of rabbit anti-O immune sera with boiled homologous O-cells failed to remove the “blocking” activity; the O-agglutination titers were reduced to nondetectable levels. However, dual absorptions of rabbit anti-O immune sera with killed cells of Staphylococcus aureus Cowan I (protein A) almost completely abolished “blocking” activity; the O-agglutinin titers of these immune sera were not reduced more than 4-fold. Immunoelectrophoresis and rocket electroimmuno assays, employing heavy chain-specific goat anti-rabbit IgG and IgM sera, respectively, established that dual protein A-absorption selectively removed rabbit IgG, but not rabbit IgM, immunoglobulins. It was concluded that rabbit immunoglobulins of the IgG class accounted for the observed in vitro antagonism of the bactericidal activity of fresh human serum against DSS and PSS strains of S. marcescens.     

Direct isolation in vitro of Trypanosoma brucei from man and other animals, and its potential value for the diagnosis of gambian trypanosomiasis.

A recently described simple kit for isolating African trypanosomes in vitro (KIVI) was tested further with blood samples from man and other animals in C?te d'Ivoire and République du Congo. A high rate of success was achieved, with positive cultures being found 5-36 d after inoculation. The method was also of value in diagnosis. Parasitaemia was initially detected by the haematocrit method; in addition, the mini-anion exchange column was used for human blood and lymph fluid from patients with swollen glands was examined. The card agglutination test (CATT) was applied to the human blood samples. In C?te d'Ivoire, all 5 parasitaemic patients, who were also positive by CATT, yielded positive KIVI cultures. Of 15 animals, 2 parasitaemic and 10 apparently aparasitaemic individuals gave positive cultures. In the Congo, none of the 22 animals was parasitaemic and none gave a positive culture. Of 647 human subjects initially screened, 61, mostly with a positive CATT, were examined by KIVI; 20 gave positive cultures. Seven of these cultures originated from patients in whom no trypanosome had been seen in blood or lymph fluid, although blood from 2 parasitaemic patients failed to yield positive KIVI cultures. Some patients with CATT-negative whole blood and/or serum were positive by KIVI.     

Serum and plasma brain-derived neurotrophic factor (BDNF) in abstinent alcoholics and social drinkers

Although the effects of alcohol on brain-derived neurotrophic factor (BDNF) have been extensively studied in rodents, BDNF levels have rarely been measured in abstinent, alcohol-dependent (AD) individuals. Interpretation of reported group comparisons of serum BDNF levels is difficult due to limited information regarding analytical variance, biological variability, and the relative contribution of platelet and plasma pools to serum BDNF. Analytical variance (intra- and inter-assay coefficients of variation) of the enzyme-linked immunosorbent assay (ELISA) was characterized. Within- and between-subject variability, and group differences in serum and plasma BDNF, was assessed on three separate days in 16, 4-week abstinent AD individuals (7M/9F) and 16 social drinkers (SDs; 8M/8F). Significantly higher mean (±sd) serum BDNF levels were observed for the AD group compared to the SD (p = 0.003). No significant difference in mean baseline plasma BDNF levels was observed between AD and SD groups. The low analytical variance, high day-to-day within-individual stability and the high degree of individuality demonstrates the potential clinical utility of measuring serum BDNF levels. The low correlations that we observed between plasma and serum levels are congruent with their representing separate pools of BDNF. The observation of higher basal serum BDNF in the AD group without a concomitant elevation in plasma BDNF levels indicates that the elevated serum BDNF in AD patients is not due to greater BDNF exposure. Further research is warranted to fully elucidate mechanisms underlying this alteration and determine the utility of serum BDNF as a predictor or surrogate marker of chronic alcohol abuse.