Marker and function analysis of natural killer and alloreactive T cells during early stages of dimethylbenzanthracene carcinogenesis. The immunity system during the precancer period

The effect of the chemical carcinogen dimethylbenzanthracene (DMBA) on cellular immunity was studied at a 6-mg dose which induces adenocarcinomas and adenoacanthomas in more than 70% of BalB/c mice within 1 year after administration. DMBA caused a significant reduction of splenic natural killer (NK) activity and responsiveness to alloantigens in mixed lymphocyte reactions (MLR). These activities decreased soon after the carcinogen treatment and remained suppressed during the entire tumor induction period. There was a linear correlation between the reduction in NK activity and a selective decrease in the number of asialo GM1 positive cells in the spleen. However, cell sorting experiments using the flow cytometer have shown that the lytic activity per cell of asialo GM-1 positive cells in untreated mice and in DMBA-treated ones was similar. There was no correlation between the suppressed response of the T cells in MLR and the percentage of T cell subpopulations residing in the spleen of the DMBA-treated mice. The decrease in the number of NK cells and the reduced MLR activity in the spleen occurred simultaneously with a decrease in the potential of bone marrow precursor cells to reconstitute NK and MLR activity in the spleen of lethally irradiated mice. These results indicate that the carcinogen DMBA effects the immune system at various levels and either eliminates or inactivates precursor cells as well as mature lymphoid cells.     

Eicosanoids from the Rhodophyta: new metabolism in the algae

Red marine algae are shown in this work to be a rich source of eicosanoid-type natural products. This is the first isolation of several of these mammalian arachidonic acid metabolites from any marine or terrestrial plant source (12-HETE, 12-HEPE, 6(E)-LTB4, hepoxilin B3). A few of these represent truly novel substances never previously isolated from nature [12(R), 13(S)-diHETE]. Inherent in these seaweed natural product structures is evidence for a highly evolved lipoxygenase-type metabolism that matches or exceeds the complexity of comparable metabolic routes in mammalian systems. As these compounds are produced by algae in relatively large quantities (0.1–5.0% of crude lipid extracts), these plants could be important commercial resources for these expensive and rare biochemicals. Further, we suggest that this metabolism is important to physiological processes in red algae that are completely unknown at present. For example, it is possible that they act in an exocrine sense to coordinate reproductive events, a hypothesis under current investigation through culture studies.This paper was presented at the mini-symposium Bioactive Compounds from Algae, Y. Shimizu, Convener.     

Lycopene is superior to moringa in improving fertility markers in diet-induced obesity male rats

Obesity is a condition of chronic tissue inflammation and oxidative stress that poses as a risk factor for male infertility. Moringa oleifera oil extract is known to have cholesterol-lowering properties and a potential to treat obesity, while lycopene is a potent antioxidant. We hypothesize that Moringa or lycopene may improve male fertility markers in an animal model of diet-induced obesity. Male Albino rats (n = 60) were randomized to receive regular chow (RC) or high-fat diet (HFD) for 12 weeks (n = 30 each). Animals in each arm were further randomized to receive gavage treatment with corn oil (vehicle), lycopene (10 mg/kg), or Moringa (400 mg/kg) for four weeks starting on week 9 (n = 10 each). Animals were sacrificed at 12 weeks, and blood was collected to assess lipid profile, serum testosterone, and gonadotropin levels. The testes and epididymides were removed for sperm analysis, oxidative stress and inflammatory markers, and histopathological assessment. In comparison to their RC littermates, animals on HFD showed an increase in body weights, serum lipids, testosterone and gonadotrophin levels, testicular oxidative stress and inflammatory markers, as well as sperm abnormalities and disrupted testicular histology. Moringa or lycopene reduced body weight, improved oxidative stress, and male fertility markers in HFD-fed animals with lycopene exhibiting better anti-antioxidant and anti-lipidemic effects. Lycopene is superior to Moringa in improving male fertility parameters, possibly by attenuating oxidative stress.     

Lactic acid production by loofah-immobilized Rhizopus oryzae through one-step fermentation process using starch substrate

Rhizopus oryzae PTCC 5263 capacity in synthesis of lactic acid (LA) from 10 g/l of soluble potato starch was determined using one-step fermentation process. Pellets were the favorable growing form of the free cells. The extent of the natural ability of the test fungus on biofilm formation on loofah sponge was examined by immobilizing R. oryzae (LIRO). The maximum LA concentration for the free cells and LIRO within 96 h was 3 and 4 g/l, respectively. In terms of specific starch utilization rate (\(q_{\text{s}}\)) and specific LA formation (\(q_{\text{p}}\)), LIRO performed more favorably compared to the free cells (\(q_{{{\text{s}}_{\text{F}} }} > q_{{{\text{s}}_{\text{LIRO}} }}\) and \(q_{{{\text{p}}_{\text{F}} }} < q_{{{\text{p}}_{\text{LIRO}} }}\)). Cell immobilization strategy was undertaken for the column reactor studies based on the statistically optimized levels of the inoculum size and temperature. Maximum production of the LA by the LIRO using an airlift reactor with net draft tube was 5 g/l obtainable within 48 h.

     

Mobility of enzymes on insoluble substrates: the beta-amylase-starch gel system

The movement of enzymes along the surfaces of biopolymers containing enzyme-susceptible sites can be described as a lateral diffusion process characterized by an apparent diffusion coefficient [E. Katchalski-Katzir, J. Rishpon, E. Sahar, R. Lamed, and Y. I. Henis (1985) Biopolymers 24 , 257–277]. Studies on the diffusion of enzymes on biopolymer substrates can therefore provide important information on the mechanism of enzyme–biopolymer interaction. For this reason, the motion of fluorescently labeled β-amylase [α-D -(1 → 4)glucan maltohydrolase; E.C. 3.2.1.2] on the surface of starch gels was studied by fluorescence photobleaching recovery. The results indicate that the motion of β-amylase on the surface of the gel substrate occurs by both lateral diffusion along the surface (over micron distances) and exchange between bound and free enzyme molecules in the solution covering the gel, and that the two processes occur concomitantly and in a random manner. Surface diffusion also appears an important process with respect to the action of the enzyme on the substrate sites, since this component of the motion disappears upon inactivation of the enzyme, leaving only exchange to contribute to the measured motion.     

Physician choices in pulmonary embolism testing

BACKGROUND:Evidence-based guidelines advise excluding pulmonary embolism (PE) diagnosis using d-dimer in patients with a lower probability of PE. Emergency physicians frequently order computed tomography (CT) pulmonary angiography without d-dimer testing or when d-dimer is negative, which exposes patients to more risk than benefit. Our objective was to develop a conceptual framework explaining emergency physicians’ test choices for PE.METHODS:We conducted a qualitative study using in-depth interviews of emergency physicians in Canada. A nonmedical researcher conducted in-person interviews. Participants described how they would test simulated patients with symptoms of possible PE, answered a knowledge test and were interviewed on barriers to using evidence-based PE tests.RESULTS:We interviewed 63 emergency physicians from 9 hospitals in 5 cities, across 3 provinces. We identified 8 domains: anxiety with PE, barriers to using the evidence (time, knowledge and patient), divergent views on evidence-based PE testing, inherent Wells score problems, the drive to obtain CT rather than to diagnose PE, gestalt estimation artificially inflating PE probability, subjective reasoning and cognitive biases supporting deviation from evidence-based tests and use of evidence-based testing to rule out PE in patients who are very unlikely to have PE. Choices for PE testing were influenced by the disease, environment, test qualities, physician and probability of PE.INTERPRETATION:Analysis of structured interviews with emergency physicians provided a conceptual framework to explain how these physicians use tests for suspected PE. The data suggest 8 domains to address when implementing an evidence-based protocol to investigate PE.

Pulmonary embolism (PE) occurs when a blood clot lodges in the pulmonary arteries. If left untreated, the disorder can progress, causing worsening morbidity and may become fatal.¹ Because of the acute nature of this condition, many patients with PE present to the emergency department.Diagnosing and excluding PE using computed tomography pulmonary angiography (CTPA) alone can be problematic because of radiation exposure, anaphylaxis to contrast, misdiagnosis and “overdiagnosis” of inconsequential PE² (leading to unnecessary anticoagulation therapy and psychological distress³). Choosing Wisely^4,5 and the guideline from the American College of Physicians⁶ recommend the use of risk stratification tools, including the Pulmonary Embolism Rule-out Criteria (PERC) clinical decision rule,⁷ the Wells score⁸ and blood concentration of d-dimer. These tools use different predetermined diagnostic algorithms to indicate the need for CTPA.^8–11 Evidence-based guidelines discourage further testing in patients at lower risk who have normal d-dimer levels, where imaging can cause more harm than benefit.^12,13 However, many emergency physicians opt for CTPA as a stand-alone test for PE.^14–17It remains unclear why emergency physicians sometimes do not use validated diagnostic PE tools. Furthermore, implementation of computerized decision support systems has had little success in modifying this behaviour.^18,19 We sought to develop a conceptual framework to describe how Canadian emergency physicians test for PE, and to document the cognitive and contextual barriers to using existing evidence-based diagnostic PE pathways.     

Adherence ofStaphylococcus epidermidis to pharyngeal epithelial cells mediated by lipoteichoic acid

Prior treatment of pharyngeal epithelial cells (PEC) with lipoteichoic acid (LTA) derived fromStaphylococcus epidermidis produced a marked inhibition of adherence of the homologous strain and two heterologous strains. The inhibition was dose dependent and saturable with 100 µg/ml of LTA. However, pretreatment of PEC with deacylated LTA did not block the adherence of the three strains tested. A similar but less marked blocking effect on the adherence ofS. epidermidis to PEC was also observed with LTAs derived fromS. aureus andStreptococcus pyogenes. On treatment of bacteria with substances capable of binding to LTA, such as polyclonal mouse anti-LTA antibodies or with human albumin, a marked inhibition of bacterial adherence was observed. Immunofluorescence studies showed that anti-LTA antiserum bound readily to the surface of bacterial cells. These findings provide clear evidence that the lipid component of LTA located on the bacterial surface is centrally involved in the adherence ofS. epidermidis to human mucosal cells.