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At least 1,243 records · Page 69Linked to original sources
PubMed1984

The overlearning-extinction effect and successive negative contrast in honeybees (Apis mellifera).

In three experiments with free-flying honeybees, the previously discovered overlearning-extinction effect was replicated under different conditions and shown to depend on magnitude of reinforcement: The effect appeared in training with a 50% sucrose solution but not with a 20% solution. The results prompted a fourth experiment in which successive negative contrast was demonstrated: The animals were disturbed to find the 20% solution on a distinctive target that always before had been baited with the 50% solution. The conclusion is that the overlearning-extinction effect is an instance of contrast and can be understood in terms of frustration engendered by unrealized anticipation of reinforcement.

Animals↗
PubMed1983

Classical conditioning of proboscis extension in honeybees (Apis mellifera).

Extension of the proboscis was conditioned in restrained honeybees with odor as the conditioned stimulus (CS) and sucrose solution--delivered to the antenna (to elicit extension of the proboscis) and then to the proboscis itself--as the unconditioned stimulus (US). In a first series of experiments, acquisition was found to be very rapid, both in massed and in spaced trials; its associative basis was established by differential conditioning and by an explicitly unpaired control procedure (which produced marked resistance to acquisition in subsequent paired training); and both extinction and spontaneous recovery in massed trials were demonstrated. In a series of experiments on the nature of the US, eliminating the proboscis component was found to lower the asymptotic level of performance, whereas eliminating the antennal component was without effect; reducing the concentration of sucrose from 20% to 7% slowed acquisition but did not lower the asymptotic level of performance; and second-order conditioning was demonstrated. In a series of experiments on the role of the US, an omission contingency designed to eliminate adventitious response-reinforcer contiguity was found to have no adverse effect on acquisition. In a series of experiments designed to analyze the resistance to acquisition found after explicitly unpaired training in the first experiments, no significant effect was found of prior exposure either to the CS alone or to the US alone, although the unpaired procedure again produced substantial resistance that was shown to be due to inhibition rather than to inattention; extinction after paired training was found to be facilitated by unpaired presentations of the US. The relation between these results for honeybees and those of analogous experiments with vertebrates is considered.

Animals↗
PubMed1993

Determination of sensitivity to antifungal drugs: evaluation of an API kit.

Evaluation of a commercial kit method for testing sensitivity of yeasts to antifungal drugs was performed employing agar gel dilution as the reference method. For the cidal drugs amphotericin B and flucytosine, results were closely comparable. For the three azole drugs tested, miconazole, econazole and ketoconazole, the discrepant results obtained probably relate to a number of factors affecting the end-point when testing these agents. Although easy to perform, the kit method is relatively expensive and the newer antifungal agents (e.g. fluconazole and itraconazole) are not included. Though showing promise, the kit method has limitations in its present format.

Antifungal Agents↗
PubMed1993

One year efficacy and tolerability of clonidine administered by the transdermal route in patients with mild to moderate essential hypertension--a multicentre open label study. The Antihypertensive Patch Italian Study (APIS) Investigators.

The clonidine patch offers for the first time the unique possibility of a once-a-week transdermal therapy of hypertension due to direct absorption of clonidine through the skin. The present study investigates the efficacy and safety of the transdermal administration on a sample of the Italian population. 101 patients entered the study, 51 male, 50 female (mean age: 53 years, SD +/- 10; range: 30-71 years), they were given clonidine by a therapeutical transdermal system as starting dosage. If blood pressure was not adequately controlled (DBP < 90 or 10 mmHg decreased from baseline value) the dosage was increased on a 2 week basis assessment. The patients were then followed for 12 months after the start of treatment. The decrease in both systolic and diastolic blood pressure continued up to one month after start of treatment and remained constant for at least 9 months. A total of 70% of the patients were controlled by the antihypertensive treatment as monotherapy, while in 6% additional combination with a diuretic lead to blood pressure control. 5% of the patients showed no reduction in blood pressure at the end of the titration phase. 24 (23%) patients complained of skin reaction; 21 patients of these (ten male, eleven female) were withdrawn from the trial due to predefined skin reaction criteria. No serious side effects have been observed during the run of the study. No rebound phenomena occurred in the week after treatment discontinuation. It is concluded that the transdermal treatment of hypertension with a clonidine containing transdermal system is therapeutically effective and probably associated with a high acceptability and increased compliance.

Administration, Cutaneous↗
PubMed1976

[Variation of the 9-keto-2-decenoic acid content as a function of age in virgin queen-bees (Apis mellifica ligustica S.)].

We measured the amount of 9-oxodec-2-enoic acid in virgin Honeybee queens 1 to 50 days old. We chose 4 age ranges: from 1 to 6, from 16 to 20, from 26 to 30, from 40 to 50 days. Queens 16 to 20 days old contain most 9-oxodec-2-enoic acid (average : 1 107 mug). The observed variations in amounts should partly depend on the physiology of attending workers. The authors discuss the mechanisms responsible for the action of 9-oxodec-2-enoic-acid.

Aging↗
PubMed1993

Functional and chemical characterization of Hymenoptaecin, an antibacterial polypeptide that is infection-inducible in the honeybee (Apis mellifera).

As part of our ongoing search for novel antimicrobial agents and their use in singular or combined drug therapy, we have isolated a series of polypeptides from the lymph fluid of honeybees. These polypeptides are synthesized de novo, following experimental infection of the insect with live Escherichia coli cells, and confer a broad-spectrum antibacterial defense to the host. We have dissected this humoral "immune" system into its constituent components. In addition to the previously characterized apidaecins and abaecin, we also isolated a member of the defensin family of peptide antibiotics and, now, a novel 93-amino acid long, cationic polypeptide, termed hymenoptaecin. Detailed analysis established the complete chemical structure, including a 2-pyrrolidone-5-carboxylic acid at the N terminus, and indicated major differences with all known antibacterial polypeptides. Under physiological conditions, it inhibits viability of Gram-negative and Gram-positive bacteria, including several human pathogens. Lethal effects against E. coli are secondary to sequential permeabilization of outer and inner membrane. In combination, the six-constituent "peptide antibiotics" of bee lymph provide wide-spectrum antibacterial protection in vitro by virtue of complementarity rather than synergism.

Amino Acid Sequence↗
PubMed1997

Activity-dependent changes to the brain and behavior of the honey bee, Apis mellifera (L.).

To explore the origins and possible behavioral consequences of structural plasticity in an insect brain, we have taken advantage of the following: (1) the highly compartmentalized nature of the primary antenno-sensory centers (antennal lobes) of the brain, (2) the ease with which individual compartments, or glomeruli, within the antennal-lobe neuropil can be identified, and (3) the predictability of changes to readily identifiable glomeruli in the antennal lobes of the adult worker honey bee. Treatment with the juvenile hormone analog methoprene and hive manipulation techniques are used to induce precocious foraging behavior in young worker honey bees. The impact of these treatments on the ontogeny of olfactory learning performance and on the volumes of readily identifiable glomeruli in the antennal lobes of the bee brain are examined in parallel. The study reveals that (1) significant changes in glomerular volume are activity dependent and (2) associative learning of floral odors improves with experience. Improvements in associative learning performance coincide temporally with increases in glomerular volume. This raises an important question: are changes in glomerular volume that result from shifts in behavior simply a consequence of changes in the use of peripheral sensory pathways, or are they associated with events that underlie learning and the formation of long-term memories?

Animals↗
PubMedDate not supplied

Acquired immunity to Africanized honeybee (Apis mellifera) venom in Brazilian beekeepers.

Seventy-eight Brazilian beekeepers who had been stung on average six times per month were studied. Sixty-eight beekeepers (87.1%) showed restricted local clinical reactions; nine individuals (11.5%) had extensive local reactions, and only one (1.2%) suffered anaphylactic shock. The humoral immunologic pattern of these individuals were studied by using immunoenzymatic methods to determine the serum titles of specific IgE and specific IgG4. Three groups of beekeepers presenting different humoral immunologic patterns were identified, in which the predominant pattern was the absence of specific IgE and high levels of specific IgG4 (38.4%). There was a positive correlation between the high levels of specific IgG4 and the number of bee stings. This correlation was not found in either specific or total IgE. The results of the present study suggest: i) the immunologic response to the number of exposures to Africanized honey-bee venom is not related to the number of exposures; and, ii) other nonhumoral and/or nonimmunologic factors may be involved in the reaction to the insect sting, which are responsible for both the clinical symptoms and protection.

Adolescent↗
PubMed2006

Contamination levels and preliminary assessment of the technical feasibility of employing natural attenuation in 5 priority areas of Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil.

Five priority areas of potential impact by contaminants (API) were investigated at the Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil with the following aims: (i) to identify both organic and inorganic contaminants present in soil and groundwater; (ii) to define the environmental conditions relevant for microbial activity at the site and (iii) to evaluate the feasibility of employing natural attenuation for treatment of the hydrocarbon contamination. One area (API 1) was an uncontrolled landfill, where waste materials from the refinery were deposited between 1954 and 1986, and four areas (API 4, 5, 7 and 11) were located in the operational section of the refinery. Soil contamination by regulated BTEX compounds (benzene, toluene, total xylenes) was restricted to two samples from API 1. Nonregulated ethylbenzene was detected in one soil sample from API 4, one from API 5 and two from API 1. No soil contained regulated PAH above threshold levels. Several nonregulated PAHs were found in 6 soil samples from API 1, 3 soil samples from API 4 and 1 soil sample from API 5. Site soils contained very high aluminium concentrations, but metal contamination was restricted to one soil sample from API 1, which contained nickel above threshold limits. BTEX contamination of groundwater was due mostly to benzene. Of the 17 PAH molecules tested, only naphthalene and 2-methylnaphthalene occurred in groundwater. The sum of total BTEX and total PAH exceeded 200 microg/L in only a few monitoring wells in API 4, 5 and 11 and was always below 2.640 microg/L. Be, Cd, Cr, Cu, Hg, Ni, Se, Ag, Tl and Zn were not detected in groundwater, which was contaminated in a few locations by aluminium (mostly below 1 mg/L), lead (<0.066 mg/L) and arsenic (<0.056 mg/L). S, K, Ca, Mg and Fe were present in groundwater in excess of physiological requirements for microbial growth, but low concentrations of N and P could become growth limiting. However, BTEX were efficiently degraded in saturated and unsaturated zone microcosms and nutrient amendments did not stimulate biodegradation rates measurably. The inorganic carbon pool in groundwater was up to one order of magnitude larger than the organic carbon pool. Total inorganic carbon (TIC) in API groundwater exceeded TIC of clean groundwater by factors of 2 (API 4), 6 (API 5, 7 and 11) or 10 (API 1). Most of the inorganic carbon incorporated into groundwater beneath the refinery originated from biodegradation in the unsaturated soil, which contained a microbiota (10(6) cells/g on average) capable of growth with most of the pure (benzene, toluene, ethylbenzene and xylene) and mixed hydrocarbons tested (diesel oil, gasoline, naphtha, condensate, aromatic residue and fuel oil). A viscous hydrocarbon paste uncovered in API 1 was insoluble in water but dissolved in dichloromethane. Many organic components of this paste were biodegradable as evidenced by weight reduction of the hydrocarbon paste and by the growth of suspended and attached biomass in saturated zone microcosms, where the paste was the only carbon source. This study indicates that monitored natural attenuation may be a technically feasible and efficient means for plume control in API 1, 4 and 5, provided the plumes in API 4 and 5 are not expanding. This technique is not suitable for contaminant reduction in API 11.

Biodegradation, Environmental↗
PubMed2000

Characterization and determination of the complex between prostate-specific antigen and alpha 1-protease inhibitor in benign and malignant prostatic diseases.

Prostate-specific antigen (PSA) is a tissue-specific serine protease which forms complexes with protease inhibitors such as alpha 1-antichymotrypsin and alpha 2-macroglobulin. We have studied the interaction between PSA and alpha 1-protease inhibitor (API) in vitro and found that 15% of the added PSA binds to API while the majority of API is cleaved between Met358 and Ser359 when PSA is incubated with a 5-fold excess of API at 37 degrees C for 7 days. The complex between PSA and API (PSA-API) formed in vitro displays the same chromatographic behavior, molecular size and immunoreactivity as endogenous PSA-API occurring in serum, indicating that they are identical. PSA-API can be detected in serum by a time-resolved immunofluorometric assay (IFMA), in which a monoclonal antibody to PSA is used as a catcher and a polyclonal antibody to API labeled with a Eu-chelate is used as a tracer. Purified PSA-API formed in vitro is used as a calibrator. PSA-API in serum represents 1.0-7.9% (median 2.4%) of total PSA (tPSA) in prostate cancer (PCa, n = 82) and 1.3-12.2% (median 3.6%, p < 0.01) in patients with benign prostatic hyperplasia (BPH, n = 66). The IFMA for PSA-API in serum is hampered by a variable background, which is caused by non-specific adsorption of the huge excess of API in serum to the solid phase. The background can be determined by an assay using the same tracer as in the IFMA for PSA-API but PSA-unrelated antibody on the solid phase. The background signal is subtracted from the PSA-API signal. The clinical utility of PSA-API in serum has been evaluated in PSA-positive subjects from the Finnish PCa screening trial. After subtraction of the background, the proportion of PSA-API in relation to tPSA is lower in PCa than in controls, 0.9% vs. 1.6%, respectively (p < 0.001). Logistic regression analysis showed that the concentration of PSA-API was independent of the proportion of free PSA as a diagnostic variable among subjects with a tPSA of 4-10 micrograms/l (p = 0.009). The probability of PCa calculated by logistic regression using the concentration of PSA-API and the proportion of free PSA in serum significantly improved cancer specificity at high sensitivity levels (85-95%) as compared to the proportion of free PSA alone.

Humans↗