Insecticidal effectiveness ofMammea Americana (Guttiferae) extracts on larvae ofDlabrotica Virgifera Virgifera (Coleoptera:Chrysomelidae) andTrichoplusia Ni (Lepidoptera:Noctuidae)

Seed and leaf extracts ofMammea americana (mamey apple) have a historical use as a biopesticide with the active components previously characterized. We reexamined the utility of this natural bioinsecticide in light of existing sources of material as a by-product of the fruit processing industry. Our results addDiabrotica virgifera virgifera andTrichoplusia ni to the list of insects which are susceptible to the insecticidal ingredients ofM. americana and confirms earlier reports of activity againstBlatella germanica, Periplaneta americana, andPlutella xylostella. We report LD5Os for crude hexane extracts ofM. americana leaves and seeds againstT. ni. These materials represent renewable sources of bioinsecticides for agriculture, and should regenerate interest in coumarin-type compounds for novel pesticidal action.     

Molecular modeling studies of the intramolecular twist mechanisms of racemization for tris chelate complexes

The preferred mechanisms of racemization for three tris chelate complexes, Co(acac)₃, Fe(phen)₃ ³⁺ and Fe[S₂CN(CH₂)₄]₃, were investigated by molecular modeling. The transition states for both a Bailar twist and a Rây-Dutt twist were considered; semi-empirical calculations (PM3) yielded activation energies. The preferred mechanism was the Bailar twist for Co(acac)₃ and Fe[S₂CN(CH₂)₄]₃ with activation energies of 83.2 and 7.3 kcal mol⁻¹, respectively, and the Rây-Dutt twist for Fe(phen)₃ ³⁺ with an activation energy of 114.4 kcal mol⁻¹. These results are compared with those of geometrical models.     

Functional specialization and differential regulation of short‐chain carboxylic acid transporters in the pathogen Candida albicans

The major fungal pathogen Candida albicans has the metabolic flexibility to assimilate a wide range of nutrients in its human host. Previous studies have suggested that C. albicans can encounter glucose‐poor microenvironments during infection and that the ability to use alternative non‐fermentable carbon sources contributes to its virulence. JEN1 encodes a monocarboxylate transporter in C. albicans and we show that its paralogue, JEN2, encodes a novel dicarboxylate plasma membrane transporter, subjected to glucose repression. A strain deleted in both genes lost the ability to transport lactic, malic and succinic acids by a mediated mechanism and it displayed a growth defect on these substrates. Although no significant morphogenetic or virulence defects were found in the double mutant strain, both JEN1 and JEN2 were strongly induced during infection. Jen1‐GFP (green fluorescent protein) and Jen2‐GFP were upregulated following the phagocytosis of C. albicans cells by neutrophils and macrophages, displaying similar behaviour to an Icl1‐GFP fusion. In the murine model of systemic candidiasis approximately 20–25% of C. albicans cells infecting the kidney expressed Jen1‐GFP and Jen2‐GFP. Our data suggest that Jen1 and Jen2 are expressed in glucose‐poor niches within the host, and that these short‐chain carboxylic acid transporters may be important in the early stages of infection.     

Staff Nurses’ Perceptions and Experiences about Structural Empowerment: A Qualitative Phenomenological Study

The aim of the study reported in this article was to investigate staff nurses’ perceptions and experiences about structural empowerment and perceptions regarding the extent to which structural empowerment supports safe quality patient care. To address the complex needs of patients, staff nurse involvement in clinical and organizational decision-making processes within interdisciplinary care settings is crucial. A qualitative study was conducted using individual semi-structured interviews of 11 staff nurses assigned to medical or surgical units in a 600-bed university hospital in Belgium. During the study period, the hospital was going through an organizational transformation process to move from a classic hierarchical and departmental organizational structure to one that was flat and interdisciplinary. Staff nurses reported experiencing structural empowerment and they were willing to be involved in decision-making processes primarily about patient care within the context of their practice unit. However, participants were not always fully aware of the challenges and the effect of empowerment on their daily practice, the quality of care and patient safety. Ongoing hospital change initiatives supported staff nurses’ involvement in decision-making processes for certain matters but for some decisions, a classic hierarchical and departmental process still remained. Nurses perceived relatively high work demands and at times viewed empowerment as presenting additional. Staff nurses recognized the opportunities structural empowerment provided within their daily practice. Nurse managers and unit climate were seen as crucial for success while lack of time and perceived work demands were viewed as barriers to empowerment.     

Releases of Norepinephrine and Dopamine in Ventriculocisternal Perfusions in Hepatectomized and Laparotomized Rats

Abstract: The completely hepatectomized rat has frequently been used as a model to study changes in the economy of norepinephrine (NE) and dopamine (DA) in hepatic coma. Hypothermia characteristically develops in hepatectomized rats and also occurs in patients in hepatic coma and is associated with improved survival in both. The aims of the present study were to measure both release and uptake of NE and release of DA in brain in warm (37°C) and cool (30–32°C) rats at 3–5 h after laparotomy or hepatectomy. Ventriculocisternal perfusions of the brain were performed on rats under basal conditions and during releases evoked by 40 m M K⁺. Basal releases of NE and DA and evoked release of DA were greater in the warm hepatectomized rats than in all other groups. In some studies, 10⁻⁵ M amitriptyline was added to the perfusates to assess whether neuronal uptake was changed after hepatectomy. Uptake of released NE was equally robust in cool hepatectomized as in cool laparotomized rats but could not be measured in warm hepatectomized rats because of amitriptyline toxicity in these rats. Decreases in NE and increases in DA content were found in most areas of the brain after perfusion. Increased releases of NE and DA may contribute to the pathogenesis of hepatic encephalopathy.     

Relative efficiency of preferred and nonpreferred patterns of lateralized foraging in the gentle lemur (Hapalemur griseus)

Lateralized patterns of hand use in species-typical bamboo shoot foraging were evaluated for efficiency in five female and six male gentle lemurs (Hapalemur griseus sp.). Efficiency was defined as amount of time required to complete a foraging response sequence. The foraging pattern consisted of four component movements: PULL-IN, COUNTERFORCE, TURN, and FEED-IN. These component movements had been shown in a previous study to incorporate lateral hand biases that formed subsets of patterns that were characteristic for each gentle lemur. The duration of each foraging sequence was measured from the beginning of the first component to the initiation of the terminal component. Frequency of use scores were employed to divide the pattern sequences of each subject into preferred and nonpreferred categories. A within-subjects comparison of the mean durations of preferred patterns (M = 2.56 sec) with those of non- preferred patterns (M = 3.02 sec) found that preferred patterns were executed more rapidly, t(10) = 3.36, P = .007. A multiple regression showed that order of pattern preference accounted for 89% of the variance in mean duration of response time (R² = .89, P = .056). Thus, the use of preferred lateralized hand patterns resulted in more rapid bamboo shoot harvesting. Speed in foraging may be regarded as an adaptive strategy for a species that subsists on a high bulk, low nutrient density food such as bamboo. © 1995 Wiley-Liss, Inc.     

Release of Free DNA by Membrane-Impaired Bacterial Aerosols Due to Aerosolization and Air Sampling

We report here that stress experienced by bacteria due to aerosolization and air sampling can result in severe membrane impairment, leading to the release of DNA as free molecules. Escherichia coli and Bacillus atrophaeus bacteria were aerosolized and then either collected directly into liquid or collected using other collection media and then transferred into liquid. The amount of DNA released was quantified as the cell membrane damage index (I_D), i.e., the number of 16S rRNA gene copies in the supernatant liquid relative to the total number in the bioaerosol sample. During aerosolization by a Collison nebulizer, the I_D of E. coli and B. atrophaeus in the nebulizer suspension gradually increased during 60 min of continuous aerosolization. We found that the I_D of bacteria during aerosolization was statistically significantly affected by the material of the Collison jar (glass > polycarbonate; P < 0.001) and by the bacterial species (E. coli > B. atrophaeus; P < 0.001). When E. coli was collected for 5 min by filtration, impaction, and impingement, its I_D values were within the following ranges: 0.051 to 0.085, 0.16 to 0.37, and 0.068 to 0.23, respectively; when it was collected by electrostatic precipitation, the I_D values (0.011 to 0.034) were significantly lower (P < 0.05) than those with other sampling methods. Air samples collected inside an equine facility for 2 h by filtration and impingement exhibited I_D values in the range of 0.30 to 0.54. The data indicate that the amount of cell damage during bioaerosol sampling and the resulting release of DNA can be substantial and that this should be taken into account when analyzing bioaerosol samples.