Bait traps remain attractive to euglossine bees even after two weeks: a report from Brazilian Atlantic forest

Bait traps are effective and commonly used method in the studies of orchid bees. Important questions in the context of this method, including those related to bait dispersion, how long baits remain attractive, the distance from which males are supposed to be attracted to lures and so on, are still open subjects. Data on the attractiveness of bait traps that have remained in the field during two weeks in a large Atlantic forest preserve are presented. Four main results emerge from the data: (i) the abundance of specimens collected per day decreased in all the attractants as the traps were left on the field; (ii) despite this decrease, the absolute number of individuals collected after eight and fifteen days is remarkably, mostly in eugenol and vanillin baits; (iii) the vast majority of species, 22 of 25, was already collected on the first sample day; (iv) a consistent variation in the relative abundance of individuals collected in each scent as collections were made. We urge that bait traps should not be left in the field beyond what is strictly necessary since there is a real possibility of collecting a significant number of individuals as these traps remain available.     

A retrospective hormonal and immunohistochemical evaluation of 47 acromegalic patients: prognostic value of preoperative plasma prolactin.

This study was performed to investigate the correlations between preoperative prolactin (PRL) plasma values, immunohistochemical picture and the clinical course in growth hormone (GH) secreting pituitary adenomas. In 47 patients (19 males and 28 females; mean age 40 years; range 13 - 70 years), we measured GH, IGF-1 and prolactin plasma values both before and after transsphenoidal surgery, and basal IGF-1 and GH after an oral glucose tolerance test (OGTT) during four years of follow-up. We considered those patients as "controlled" who presented an undetectable growth hormone after OGTT (GH < 1 microg/l), IGF-I plasma values in the normal range, matched for age and sex, and no clinical activity or neuroradiological recurrence after a four-year follow-up. We considered patients as "poorly controlled" who still showed elevated GH and IGF-I plasma levels, uninhibited GH after OGTT (GH > 1 microg/l), presence of clinical activity and/or radiological signs of adenoma recurrence, even if a reduction of tumor size had been demonstrated. RESULTS: Controlled patients (n = 22) exhibited mean preoperative PRL levels (+/- SEM) lower than the group of poorly controlled (n = 25) ones (21.40 +/- 5.51 vs. 38.44 +/- 5.16 microg/l; p < 0.03). From 3 to 12 months after surgery, postoperative PRL levels were also lower in the controlled patients compared to the poorly controlled ones (8.31 +/- 1.20 vs. 25.32 +/- 3.20 microg/l; p < 0.0001). Eighty percent (20/25) of poorly controlled patients showed both PRL and GH positivity after immunostaining. Only 3/22 (13.6 %) of controlled patients showed the same double positivity. In conclusion, preoperative hyperprolactinemia identifies a group of acromegalic patients at elevated risk of disease persistence after surgery. We hypothesize that most of these high-risk patients may have more aggressive mixed GH-PRL secreting adenomas.     

Pyridostigmine enhances even if it does not normalize the growth hormone responses to growth hormone-releasing hormone in patients with Cushing's disease.

Subjects with Cushing's disease have diminished growth hormone (GH) response to growth hormone-releasing hormone (GHRH). The aim of our study was to investigate the underlying mechanism of this diminished GH response in these patients using pyridostigmine (PD), an acetylcholinesterase inhibitor, which is reported to increase GH secretion by reducing somatostatin tone. Eight subjects with untreated Cushing's disease (caused by a pituitary adenoma) and 6 control subjects received GHRH 100 micrograms in 1 ml of saline, as intravenous bolus injection 60 min after (1) placebo (2 tablets, p.o.) or (2) PD (120 mg, p.o.). After GHRH plus placebo, the GH peak (mean +/- SEM) was significantly lower in subjects with Cushing's disease (2.4 +/- 0.5 micrograms/l) compared to control subjects (25.1 +/- 1.8 micrograms/l, p less than 0.05). After GHRH plus PD, the GH peak was significantly enhanced both in subjects with Cushing's disease (7.1 +/- 2.3 micrograms/l, p less than 0.05) and in control subjects (42.3 +/- 4.3 micrograms/l, p less than 0.05). In patients with Cushing's disease, the GH response to GHRH plus PD was lower with respect to the GH response to GHRH alone in normal subjects. We conclude that hypercortisolism may cause a decrease in central cholinergic tone which is in turn hypothesized to be responsible of an enhanced somatostatin release from the hypothalamus. However, other metabolic or central nervous system alterations may act synergistically with hypercortisolism in causing GH inhibition in patients with Cushing's disease.     

Brain Barrier Breakdown as a Cause and Consequence of Neuroinflammation in Sepsis

The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) are important for the maintenance of brain homeostasis. During sepsis, peripheral production of proinflammatory cytokines and reactive oxygen species are responsible for structural alterations in those brain barriers. Thus, an increasing permeability of these barriers can lead to the activation of glial cells such as microglia and the production of cytotoxic mediators which in turn act on the brain barriers, damaging them further. Thereby, in this review, we try to highlight how the brain barrier’s permeability is not only a cause but a consequence of brain injury in sepsis.     

The Cosmic Silence experiment: on the putative adaptive role of environmental ionizing radiation

Previously we reported that yeast and Chinese hamster V79 cells cultured under reduced levels of background environmental ionizing radiation show enhanced susceptibility to damage caused by acute doses of genotoxic agents. Reduction of environmental radiation dose rate was achieved by setting up an underground laboratory at Laboratori Nazionali del Gran Sasso, central Italy. We now report on the extension of our studies to a human cell line. Human lymphoblastoid TK6 cells were maintained under identical in vitro culture conditions for six continuous months, at different environmental ionizing radiation levels. Compared to “reference” environmental radiation conditions, we found that cells cultured in the underground laboratories were more sensitive to acute exposures to radiation, as measured both at the level of DNA damage and oxidative metabolism. Our results are compatible with the hypothesis that ultra-low dose rate ionizing radiation, i.e. environmental radiation, may act as a conditioning agent in the radiation-induced adaptive response.