Failure of the gamma-aminobutyric acid (GABA) derivative, baclofen, to stimulate growth hormone secretion in heroin addicts.

In order to establish possible alterations in the gamma aminobutyric acid (GABA)ergic control of growth hormone (GH) secretion in heroin addicts, ten patients (age, 25.8 +/- 1.07 yr (mean +/- SE); duration of heroin addiction, range 3-8 yr; weight, 67.3 +/- 0.87 kg body weight), and ten age (29.1 +/- 0.84 yr)- and weight (69.7 +/- 0.87 kg)-matched normal controls were tested with the GABAergic B-receptor agonist baclofen (10 mg p.o. at 09.00 h) (experimental test) or a placebo (control test). Blood samples for GH assay were taken every 15 min for the next 150 min. Normal controls underwent one control and one experimental test. Heroin addicts were submitted to both baclofen and placebo test twice, once around the time of their admission to a recovery community for drug abusers, when they were still assuming heroin, and again after two months of permanence in the community. From the time of their admission to the community, the patients were forbidden to use heroin. For two weeks after admission they were treated with clonidine and acetylsalicilic acid to attenuate withdrawal symptoms. Thereafter, the patients underwent a period of wash-out of pharmacological treatments for at least 6 weeks before being retested. Basal GH levels were similar in normal controls and heroin addicts in all tests and remained unmodified during control tests in all subjects. The administration of baclofen increased four times the serum GH levels within 120 minutes in the normal controls, whereas it did not modify serum GH concentrations in heroin addicts either during the period of drug abuse or after two months of abstinence. These data show that the control of GH secretion mediated by GABAergic B-receptors is impaired in heroin addicts. It is hypothesized that this neuroendocrine alteration might represent a trait marker of heroin addiction, or more likely, that it was a consequence of a long addiction to heroin persisting after two months of abstinence.     

Reduction of baclofen-, but not sodium valproate-induced growth hormone release in type I diabetic men.

The effects of sodium valproate (a drug enhancing endogenous gamma aminobutyric acid (GABA)-ergic activity) and of the GABA analog baclofen (a GABA B receptor agonist) on serum GH levels was tested in 8 type I diabetic men and 8 normal controls. Sodium valproate (800 mg) or baclofen (10 mg) were given by mouth at 08.30 h on the experimental day. Control tests with a placebo were performed on different occasions. Basal GH levels were similar in controls and diabetic patients. Sodium valproate induced a 7 fold increase in serum GH concentrations in both groups. In contrast, baclofen-induced GH rise was significantly higher in normal controls (mean peak was 3.4 times higher than baseline) than in diabetic patients (mean peak was only 2.1 times higher than basal value). Serum GH levels did not change after placebo administration in any groups. These data suggest the presence of diabetes-induced alterations of a GABAergic pathway mediated by B receptors in the control of GH secretion. Alternatively, the data might indicate a change in diabetic men of other baclofen-sensitive neurotransmissions, different from GABA.     

Hagenia from the early Miocene of Ethiopia: Evidence for possible niche evolution?

Fossil pollen believed to be related to extant Hagenia abyssinica were discovered in the early Miocene (21.73 Ma) Mush Valley paleoflora, Ethiopia, Africa. Both the fossil and extant pollen grains of H. abyssinica were examined with combined light microscopy, scanning electron microscopy, and transmission electron microscopy to compare the pollen and establish their relationships. Based on this, the fossil pollen grains were attributed to Hagenia. The presence of Hagenia in the fossil assemblage raises the questions if its habitat has changed over time, and if the plants are/were wind pollinated. To shed light on these questions, the morphology of extant anthers was also studied, revealing specialized hairs inside the anthers, believed to aid in insect pollination. Pollen and anther morphology are discussed in relation to the age and origin of the genus within a molecular dated phylogenetic framework, the establishment of complex topography in East Africa, other evidence regarding pollination modes, and the palynological record. The evidence presented herein, and compiled from the literature, suggests that Hagenia was an insect‐pollinated lowland rainforest element during the early Miocene of the Mush Valley. The current Afromontane habitat and ambophilous (insect and wind) pollination must have evolved in post‐mid‐Miocene times.     

Expression of 60 kDa heat shock protein (Hsp60) on plasma membrane of Daudi cells

In Daudi cells, a fraction of the 60 kDa heat shock protein (Hsp60), which is typically a mitochondrial protein, is located on cell membrane. This was demonstrated by the recovery of biotinylated Hsp60 in the anti-Hsp60 immunoprecipitate obtained from cells in which surface-exposed proteins were selectively labeled with biotin. In further experiments, isolated membrane proteins (obtained by two different biochemical methods) were probed in Western blot with two antibodies (N-20 and K-19) directed against different epitopes located, respectively, at the amino- and at the carboxyl-terminus of the Hsp60. Both these antibodies recognized, among the isolated membrane proteins, a unique band with an electrophoretic mobility identical to that of the cytoplasmic Hsp60, thus demonstrating that Hsp60 is present on cell surface as an intact, full-length, protein. FACS analysis, performed with the same two highly specific anti-Hsp60 antibodies, confirmed that both the N-terminus and the C-terminus of the Hsp60 are exposed outside the cell and are accessible for recognition by the corresponding antibody. Moreover, quantitative analysis of the data showed that constitutive cell surface expression of the Hsp60 is limited to a small fraction (about 10%) of the whole cell population.     

Serum total prostate-specific antigen assay in women with Cushing's disease or alcohol-dependent pseudo-Cushing's State

BACKGROUND: The distinction between Cushing's disease (Cushing's syndrome dependent on adrenocorticotropic hormone (ACTH)-secreting tumors of pituitary origin) and pseudo-Cushing's states (Cushingoid features and hypercortisolism sometimes present in alcoholic, depressed or obese subjects) can present a diagnostic challenge in clinical endocrinology. Recently, the availability of a highly sensitive immunofluorometric assay for the measurement of total prostate-specific antigen (PSA) provided the possibility to measure serum PSA levels in women. Interestingly, PSA gene expression and protein production has been found to be upregulated by steroid hormones, such as androgens, glucocorticoids, mineral corticoids and progestins. In fact, serum total PSA concentrations appear to be higher in female patients with Cushing's disease than in normal women. We wondered whether a similar phenomenon also occurs in pseudo-Cushing's state. METHODS: In order to answer this question, we compared the serum total PSA levels measured in 10 female subjects with alcohol-dependent pseudo-Cushing's state with those observed in 8 female patients with Cushing's disease and in 15 age-matched healthy women. Serum testosterone, ACTH and cortisol, and 24-hour urinary cortisol levels were measured; cortisol suppression after dexamethasone was also tested in all subjects. RESULTS: The basal serum levels of ACTH and cortisol were significantly lower in normal subjects than in patients with Cushing's disease or pseudo-Cushing's state; these latter groups showed similar basal hormonal values. Dexamethasone administration was unable to suppress serum cortisol levels in 5 subjects with Cushing's disease and 6 subjects with pseudo-Cushing's state. Serum testosterone values in the group with Cushing's disease were higher than in the other groups. No differences were observed between pseudo-Cushing's and normal subjects. Serum total PSA levels were significantly higher in women with Cushing's disease than in subjects with pseudo-Cushing's state and normal controls; these latter groups showed similar PSA values. When serum total PSA and testosterone levels were considered together, a significant positive correlation was observed in the group with Cushing's disease, but not in the other groups. CONCLUSIONS: These data indicate that the steroid milieu responsible for the elevation in serum PSA in women with Cushing's disease is not present in subjects with alcohol-dependent pseudo-Cushing's state, suggesting the possible use of PSA as a marker of differentiation between these pathological conditions in women.     

Epidermal micromorphology in Dioon: did volcanism constrain Dioon evolution?

The genus Dioon occupies an important phylogenetic position as sister to the other Zamiaceae. However, its epidermal morphology is still poorly known. We employed scanning and transmission electron microscopy, confocal microscopy and light microscopy to examine the epidermal and cuticular morphology of 12 of the 14 currently recognized species of Dioon, examining cultivated plants and herbarium specimens. Epidermal characters separate Dioon quite clearly from the other genera of the cycads. Within the genus, the major subgroups can be distinguished by their epidermal morphology. Some characters, such as the degree of stomatal protection, reflect ecological specializations in species within the subgroups. Several epidermal characters of the crown group Dioon seem to be absent in the Cenozoic fossils usually associated with the genus, which have been used as calibrations in many recent molecular dating analyses. The presence of similar characters in a Mesozoic fossil adapted to volcanic stress offers a new key in the interpretation of Dioon evolution. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 236–254.     

Different effects of the GABAergic agent sodium valproate on the oxytocin responses to angiotensin II and insulin-induced hypoglycemia in normal men.

The present study was performed in order to establish whether angiotensin II (ANG II) and/or insulin-induced hypoglycemia exert their oxytocin (OT)-releasing effects by interacting with a GABAergic pathway. For this purpose, in 14 normal men the OT responses to ANG II (infusion for 60 min of successively increasing doses of 4, 8 and 16 ng/kg.min, each dose for 20 min; n = 7) or to insulin (0.15 IU/kg)-induced hypoglycemia (n = 7) were evaluated with or without previous treatment with the GABAergic agonist sodium valproate (600 mg in 3 divided doses, p.o.). In all subjects insulin produced a similar hypoglycemic response regardless of sodium valproate administration. Both ANG II and insulin-induced hypoglycemia produced significant increases in plasma OT levels (mean peaks were about 60% higher than baseline). The pretreatment with sodium valproate was unable to change the OT response to hypoglycemia, whereas it abolished the ANG-II-induced OT rise. These data suggest that in man a GABAergic mechanism is involved in the regulation of the OT response to ANG II, but not in the mediation of poglycemia-induced OT release.     

Increased arginine-vasopressin response to hypertonic stimulation and upright posture in idiopathic hyperprolactinemia

To evaluate the possible influence of idiopathic hyperprolactinemia on the arginine-vasopressin (AVP) response to osmotic and pressure-volumetric stimuli, 14 idiopathic hyperprolactinemic women and 13 normoprolactinemic women were studied during a hypertonic saline infusion test (0.51M NaCl infusion for 2h) and an orthostatic test (standing upright and maintaining an orthostatic position for 20min). In both experimental conditions, the AVP response was significantly higher in women with idiopathic hyperprolactinemia than in normal normoprolactinemic women. These results indicate that in women hyperprolactinemia influences the AVP response to hyperosmotic and hypovolemic stimuli.     

Effects of hypoxia on animal burrow construction and consequent effects on sediment redox profiles

We conducted a laboratory experiment to investigate the effects of mild hypoxia on the burrowing behavior of three marine species (the hard clam Mercenaria mercenaria, the polychaete worm Neanthes virens, and the amphipod Leptocheirus plumulosus) and consequent effects on sediment redox profiles. Animals were introduced into defaunated sediment and allowed to burrow for four months at mildly hypoxic (2 mg l^− 1) and normoxic (7 mg l^− 1) dissolved oxygen (DO) levels. Sediment redox profiles were measured 10 times during the course of the experiment. At the end of the experiment, the sediment was imaged using computer-aided tomography to quantify burrow volume and location. For the three species, burrow volume remained constant over DO treatments, but amphipod and clam burrows were shallower in hypoxic treatments compared with normoxic treatments. Redox profile discontinuity (RPD) depth was shallower in hypoxic treatments compared with normoxic treatments for experiments without animals, indicating that water column oxygen concentration alone influences diffusion of oxygen into the sediment. Worms, but neither clams nor amphipods, increased the RPD depth relative to no-animal controls in both hypoxic and normoxic treatments, but the effect was greater in normoxic conditions. These results suggest that although hypoxia can reduce burrowing depth, infauna can still increase the depth to which oxygen penetrates the sediment, but not to the same degree as they would under normoxic conditions.