Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.     

Acute toxicity of chlorpyrifos to the non-target organism Cnesterodon decemmaculatus

Chlorpyrifos is the most used insecticide in Argentina. Cnesterodon decemmaculatus is a widely distributed, endemic fish from Neotropical America. It attains high densities in the shallow water assemblages of Argentina and Brazil. The aim of this study was to assess the acute toxicity of chlorpyrifos to C. decemmaculatus. The mean 96-h LC₅₀ of three independent determinations was 105.3 (±?3.1) μg/L. Sublethal effects were observed. Swimming behavioral changes at each chlorpyrifos exposure concentration were reported. C. decemmaculatus represents a good model for ecotoxicological risk assessment.     

真空微波工艺条件对香脆鳙鱼片品质的影响

研究了预脱水鱼片含水量、微波功率、真空度对真空微波加工香脆鳙鱼片品质的影响,在此基础上,采用混合正交试验进一步优化了真空微波制备香脆鳙鱼片的工艺条件。研究结果表明,适宜的水分含量和微波功率可以提高鱼片的膨化率和脆度,改善鱼片的感官品质。高真空度可以改善鱼片的膨化作用和脆性,提高微波加热的效率,很大程度上避免了鱼片出现焦黑点。最佳的真空微波加热条件是预脱水鱼片水分质量分数控制在(15.3±1)%(50℃鼓风干燥3.5 h),微波功率设定为高火档(686±3.5)W,在真空度0.095 MPa下加热12 s后,间歇摇匀后再加热10 s。     

鱼油抗大鼠动脉粥样硬化的实验研究

以大鼠高脂血症及动脉粥样硬化模型观察鱼油的作用，并与舒降之、诺衡比较。鱼油组血清总胆固醇（ＴＣ）、甘油三酯（ＴＧ）、低密度脂蛋白胆固醇（ＬＤＬ－Ｃ）及ＬＤＬ－Ｃ／ＴＣ显著低于高脂组（均为Ｐ＜０．０１）；生化与病理检查提示鱼油能防止肝内脂质沉积，减少肝组织脂质过氧化物水平；鱼油能明显抑制高脂饮食造成的早期动脉粥样硬化病变。鱼油降ＴＧ的作用与舒降之及诺衡无明显差异，降ＴＣ的效果优于诺衡（Ｐ＜０．０５），改变脂蛋白成分的作用不及舒降之与诺衡。研究表明鱼油能延缓大鼠高脂血症和动脉粥样硬化的发生与发展。     

普拉固和鱼油对高胆固醇血症患者血脂与心脑血管事件影响的比较

目的:比较普拉固和鱼油对高胆固醇血症患者的血脂、血粘度、血管内皮功能和心脑血管事件的影响。方法:对266例原发性高胆固醇血症患者经2周洗脱期后,随机分为两组,普拉固组,初服10mg,每晚一次,8周后若TC仍>5.2mmol/L,LDL—ch>3.12mmol/L,则加量至20mg/d,每8周再查血脂,以达到TC<5.2mmol/L,LDL—ch<3.12mmol/L的量作治疗量继续服用。鱼油组,服美国深海鱼油一日三次,一次3g,均于服药8周复查血脂、血粘度及血管内皮功能等并作16月随访。结果:治疗8周,TC,普拉固组下降26％,鱼油组下降12％(P<0.01)。LDL—ch,普拉固组下降31％,鱼油组下降11％(P<0.01),肱动脉流量介导的舒张与硝酸甘油介导的舒张,普拉固组分别增加104％和19％,鱼油组无明显改变。全血低切粘度,普拉固组减少23％,鱼油组减少10％(P<0.01)。平均随访16月,普拉固组中脑出血1例(0.8％),鱼油组发生心脑血管事件7例(5.3％),死亡1例(P<0.05)。两组均无明显的不良反应。结论:普拉固是一个安全有效的降脂药,能改善血管内皮功能,降低血粘度,减少高胆固醇血症病人心脑血管事件发生。     

Electrophysiological characteristics of the Mauthner cell of the weakly electric fish Gymnotus carapo

The Mauthner cell (M-cell) of the ‘weakly electric fish’ Gymnotus carapo was investigated with electrophysiological techniques. The antidromic action potential, the recurrent inhibitory input and the posterior VIIIth nerve excitatory input in this cell exhibited characteristics similar to those described in the goldfish. In addition, we found an excitatory input evoked by spinal stimulation at intensities subthreshold for M-cell axons.     

Muscle growth and myosin isoform transitions during development of a small teleost fish, Poecilia reticulata (Peters) (Atheriniformes, Poeciliidae): a histochemical, immunohistochemical, ultrastructural and morphometric study

The myosin composition of lateral muscle in Poecilia reticulata from birth to adult was studied by ATPase histochemistry and immunostaining with myosin isoform-specific antibodies. At birth the muscle consists of two layers containing developmental isoforms of myosin. In deep layer fibres the developmental myosin is replaced by the adult fast-white isoform soon after birth. In the epaxial and hypaxial monolayer fibres the myosin composition present at birth (J1) is replaced within 3 days by another (J2). In some fibres, this J2 composition is retained in the adult, but in others it is slowly replaced by the adult slow-red muscle isoform. Close to the lateral line, all monolayer fibres are already in transition between the J2 myosin and the adult slow-red form at birth, and rapidly complete the transition to slow-red form. These fibres, together with others generated de novo in an underlying hyperplastic zone, form the red muscle layer of the adult. The pink muscle develops during the first month after birth, and by 31 days it consists of an outer, middle and inner layer. A few middle layer fibres are already present at birth, while the outer layer fibres first appear 3 days after birth. The thin inner layer is probably a transitional form between the middle pink and adult white types, and appears at about 31 days. A morphometric analysis showed that growth of the white muscle occurs principally by hypertrophy. Even at the magnification level of the electron microscope, no satellite cells or myoblasts which could give rise to new fibres were found in the white muscle, except in the far epaxial and hypaxial regions and only in the first 10 days. A zone of hyperplastic growth was also found lying just under the superficial monolayer close to the lateral line, and this presumably contributes fibres to the red and pink muscle layers.     

Prevalence of occupational allergy due to live fish bait

BACKGROUND: Larvae of insects and worms, used as live fish bait (LFB), are a common source of allergy in anglers and occupationally exposed workers, but the prevalence and predictors have not yet been investigated. OBJECTIVE: This study assessed the prevalence and associated factors of occupational allergy in workers exposed to LFB. METHODS: We assessed the prevalence of sensitization to LFB and work-related symptoms (WRS) in 76 workers occupationally exposed to it. All workers completed a case history questionnaire and underwent skin prick tests (SPT) for common aeroallergens and bluebottle (Calliphora vomitoria), bee moth (Galleria mellonella), mealworm (Tenebrio molitor), and gusano rojo (Cilecomadia moorei). Specific IgE were tested in 64 subjects. Two-thirds of the workers had a high level of LFB exposure. RESULTS: Sensitization to LFB was found in 24 workers (31.6%). Seven subjects (9.2%) reported WRS (asthma in 3, rhinoconjunctivitis in 5, and contact urticaria in 1), and 5 were positive for SPT and serum IgE to one or more LFB extracts. One was also exposed to LFB while fishing. Sensitization to LFB extracts and WRS were strongly associated (Odds Ratio = 6.6, P < 0.05). The 7 subjects with WRS had been exposed longer than asymptomatic subjects with positive skin tests to LFB (P < 0.05). No differences in sex, age, smoking habit, duration or level of exposure, and atopy were detected in symptomatic or in sensitized subjects, compared with normal workers. CONCLUSION: Sensitization to LFB and WRS are relatively frequent in occupationally exposed workers. No associated factors of occupational allergy to LFB could be detected.     

Reduced breast cancer mortality among fishermen's wives in Norway

International comparisons show that populations having a high consumption of fish experience low incidence of breast cancer. We compared death rates from breast cancer among socioeconomic groups in a prospective study of 533,276 Norwegian women aged 35–54 years who were followed from 1970 through 1985. Compared with the reference group (wives of unskilled workers) the fishermen's wives had a decreased risk of breast cancer with a relative risk (RR) of 0.67 (95% confidence interval [CI]=0.47–0.94) adjusted for age and the number of children. Among fishermen's wives who were parous, adjustment for age at first birth gave an RR of 0.62 (CI=0.43–0.91). This study supports the hypothesis that certain aspects of diet, i. e., fish consumption, may be associated with lower breast-cancer mortality.Drs Lund and Bønaa are with the Institute of Community Medicine, University of Tromsø, Tromsø, Norway. Address correspondence to Dr Lund, Institute of Community Medicine, University of Tromsø, N-9037 Tromsø, Norway.     

Mortality studies of machining fluid exposure in the automobile industry III: A case-control study of larynx cancer

A case-control study of larynx cancer was conducted within a cohort of automobile workers exposed to metal working fluids, commonly referred to as machining fluids (MF). Results are based on 108 cases of larynx cancer and 5:1 matched controls. Risks associated with specific types of MF, as well as specific components of the fluids were evaluated. Based on a retrospective exposure assessment, lifetime exposures to straight and soluble fluids, grinding particulate, biocides, selected metals, sulfur, and chlorine were examined. Exposure to asbestos and acid mists at two of the three study sites was also characterized. Results suggest that straight mineral oils are associated with almost a two-fold excess in larynx cancer risk. There was also evidence of an association with elemental sulfur, commonly added to straight MF to improve the integrity of the materials under extreme pressure and heat. It is not clear whether sulfur is causally related to an excess relative risk of larynx cancer or whether the observed association is the result of unmeasured confounding by another contaminant or process feature. For example, the high stress operations that require MF enriched with sulfur are also more likely to produce polycyclic aromatic hydrocarbons (PAHs) during the process. Thus, the observed association with sulfur may be due to an association with PAH. The finding of excess risk of laryngeal cancer associated with MF is consistent with several previous reports in the literature. This is the first study, however, to distinguish straight mineral oils from other types of MF. Based on these findings, a general reduction in concentrations of straight mineral oil particulate in occupational environments would be prudent.