p21, p27 and p53 in estrogen and antiprogestin-induced tumor regression of experimental mouse mammary ductal carcinomas

Metastatic mammary carcinoma tumor lines 59-2-HI and C7-2-HI originated in female BALB/c mice treated with medroxyprogesterone acetate and are maintained by syngeneic transplantation. Both lines express estrogen (ER) and progesterone receptors (PR) and regress completely after estradiol (E(2)) or antiprogestin treatment. The BET tumor line, of similar origin and biological features, regresses only after E(2) treatment. To investigate possible differences between E(2)- and antiprogestin-mediated effects we evaluated the morphological features, mitosis and apoptosis, and the differential expression of cell-cycle inhibitors associated with tumor regression. Treatments started when tumors reached 50-100 mm(2). After 24-96 h, tumors were excised and processed for morphological and immunohistochemical studies. Regression was associated with a significant and early decrease in the number of mitosis and with higher percentages of apoptotic cells. These phenomena were accompanied by an increase in p21 and p27 expression in the E(2) and antiprogestin-responsive lines treated with E(2), RU 38.486 or ZK 98.299 (P < 0.05). In BET tumors treated with E(2), p21 expression remained within basal levels and only p27 increased (P < 0.05). p53 was low in control 59-2-HI and C7-2-HI tumors and increased after treatment (P < 0.05) whereas BET untreated tumors already expressed high levels of p53 and MDM2. Although the immunohistochemical findings were compatible with alterations of p53, SSCP evaluation failed to disclose the presence of mutations, suggesting that the defective expression of p21 is related to an impaired p53 pathway. UV irradiation failed to increase p21 expression in BET, but was able to induce p53 and p21 in 59-2-HI and C7-2-HI tumors. The absence of an increased expression of p21 in E(2)-regressing BET lesions suggests that this protein is not necessary for estrogen-induced regression, but may be essential for antiprogestin action. Our results also suggest that p53/MDM2 alterations may be one of the mechanisms responsible for selected hormone resistance in breast carcinomas.     

Immunohistochemical localization of three different prepro-GnRHs in the brain and pituitary of the European sea bass (Dicentrarchus labrax) using antibodies to the corresponding GnRH-associated peptides

The distribution of the cells expressing three prepro-gonadotrophin-releasing hormones (GnRH), corresponding to salmon GnRH (sGnRH), seabream GnRH (sbGnRH), and chicken GnRH-II (cGnRH-II) forms, was studied in the brain and pituitary of the sea bass (Dicentrarchus labrax) by using immunohistochemistry. To circumvent the cross-reactivity problems of antibodies raised to GnRH decapeptides, we used specific antibodies generated against the different sea bass GnRH-associated peptides (GAP): salmon GAP (sGAP), seabream GAP (sbGAP), and chicken-II GAP (cIIGAP). The salmon GAP immunostaining was mostly detected in terminal nerve neurons but also in ventral telencephalic and preoptic perikarya. Salmon GAP-immunoreactive (ir) fibers were observed mainly in the forebrain, although sGAP-ir projections were also evident in the optic tectum, mesencephalic tegmentum, and ventral rhombencephalon. The pituitary only receives a few sGAP-ir fibers. The seabream GAP-ir cells were mainly detected in the preoptic area. Nevertheless, sbGAP-ir neurons were also found in olfactory bulbs, ventral telencephalon, and ventrolateral hypothalamus. The sbGAP-ir fibers were only observed in the ventral forebrain, innervating strongly the pituitary gland. Finally, chicken-II GAP immunoreactivity was only detected in large synencephalic cells, which are the origin of a profuse innervation reaching the telencephalon, preoptic area, hypothalamus, thalamus, pretectum, posterior tuberculum, mesencephalic tectum and tegmentum, cerebellum, and rhombencephalon. However, no cIIGAP-ir fibers were detected in the hypophysis. These results corroborate the overlapping of sGAP- and sbGAP-expressing cells in the forebrain of the sea bass, and provide, for the first time, unambiguous information on the distribution of projections of the three different GnRH forms expressed in the brain of a single species.     

Thalamic stimulation reduces essential tremor but not the delayed antagonist muscle timing

BACKGROUND: Electrical stimulation of the thalamus dramatically reduces essential tremor (ET). It has been hypothesized that the cerebellum and inferior olive are involved in the generation of ET, and thalamic stimulation is presumed to dampen ET through interactions with cerebellar output to the thalamus. Evidence suggests that abnormal timing of agonist and antagonist muscle responses contribute to cerebellar tremor (CbT); however, this relationship has not been investigated for ET. The mechanisms of the tremor and improvement are unknown. OBJECTIVE: To measure the effect of ventral intermediate thalamic stimulation in controlling the ET response to sudden stretch of an agonist muscle and to determine whether, in ET, the timing relationships between the initial agonist and antagonist electromyography (EMG) responses show abnormalities similar to those seen in CbT. METHODS: The authors studied ET subjects (with implanted thalamic stimulators turned off and on) and normal controls as they responded to mechanical torque pulses given at the wrist joint. The wrist joint angle, wrist agonist, and antagonist EMG were recorded. RESULTS: Like CbT, patients with ET showed delayed onsets of antagonist EMG and excessive rebound. Thalamic stimulation reduced the tremor but did not alter the antagonist delay or the rebound. CONCLUSIONS: In ET, antagonist muscle responses to a torque pulse are similar to that in CbT. However, benefit from thalamic stimulation did not alter these EMG responses; therefore, suppression of tremor must be caused by mechanisms other than the re-establishment of normal agonist-antagonist timing.     

Ameliorating neglect with prism adaptation: visuo-manual and visuo-verbal measures

Previous studies have shown that adaptation to rightward displacing prisms improves performance of neglect patients on visuo-manual (VM) tasks such as line cancellation, figure copying, and line bisection [Nature 395 (1998) 166]. The present study further evaluated the effect of prism adaptation (PA) on neglect symptoms by investigating: (a) the range of beneficial effects on common visuo-spatial deficits as well as less frequent phenomena like neglect dyslexia; (b) the duration of improvement following a single exposure to the right optical deviation; (c) the extent to which visuo-spatial performance can be comparatively ameliorated in VM tasks and visuo-verbal (VV) tasks (i.e. involving or not the adapted arm, respectively) and (d) the presence and duration of the manual visuo-motor bias induced by the prismatic adaptation (i.e. the after-effect). We investigated these issues in a group of neglect patients with right hemispheric damage who were also affected by neglect dyslexia. Following a single, brief prismatic adaptation the results showed that (a) several visuo-spatial abilities, including accuracy in reading single words and non-words, considerably improved, (b) the amelioration was long-lasting, continuing for at least 24h, (c) the presence, amount, and duration of neglect amelioration was not limited to VM tasks, but extended to VV tasks and (d) the presence and duration of the after-effect induced by prismatic adaptation remarkably paralleled the presence and duration of the improvement of neglect symptoms. These findings clearly demonstrate that beneficial effects induced by a single PA are very long-lasting and spread over a wide range of visuo-spatial deficits, independent of the type of response required. In addition, our results strongly suggest that the process of adaptation, as revealed by the presence of a visuo-motor after-effect, might be essential for establishing amelioration. In light of its characteristics, the prismatic adaptation technique should be a priority tool for the rehabilitation of the multifaceted hemispatial neglect syndrome.     

Long-term angiotensin II inhibition increases mitochondrial nitric oxide synthase and not antioxidant enzyme activities in rat heart

OBJECTIVE: To provide insight into the subcellular mechanisms involved in the improvement of cardiovascular structure and function by long-term inhibition of the renin-angiotensin system. DESIGN: The activities of antioxidant enzymes and mitochondrial free radical production were determined in the heart of control (C), enalapril-treated (E), and losartan-treated (L) rats to test the hypothesis of increased antioxidant enzyme activities and participation of mitochondria in the effects of chronic treatments with angiotensin II inhibitors. METHODS: At 6 and 18 months of treatment, superoxide dismutases (SOD), Se-glutathione peroxidase, and catalase activities were determined in left ventricle homogenates by spectrophotometric methods and nitric oxide (NO) production in submitochondrial membranes by the oxyhemoglobin oxidation assay. The maximal rate of hydrogen peroxide (H2O2) production by submitochondrial membranes was also evaluated at 18 months by the scopoletin-horseradish peroxidase method. RESULTS: No significant increase was found in the antioxidant enzymes measured. At 6 months, Mn-SOD was actually decreased in E and catalase in both E and L, whereas at 18 months Se-glutathione peroxidase was decreased in L. Production of NO by submitochondrial particles was 64% higher at 6 months in E and 105% higher at 18 months in E and L. Maximal hydrogen peroxide production was lower at 18 months in both groups. CONCLUSIONS: Results do not support the hypothesis of an increase in antioxidant enzyme activity by long-term treatment with angiotensin II inhibitors as previously suggested and point towards a role for the NO produced by mitochondrial nitric oxide synthase (mtNOS) in the protective effect of these drugs.     

Motion sickness and postoperative vomiting in children

BACKGROUND: Motion sickness is considered an important risk factor for postoperative nausea and vomiting in children. The aim of this study was to verify the impact of motion sickness on the incidence of vomiting after routine surgery in children, and to compare the incidence of vomiting, after combined regional/general anaesthesia, using either halothane or sevoflurane. METHODS: We prospectively studied 420 children (369 males and 51 females) who received general anaesthesia and inguinal field block for common paediatric surgery. The children were randomly allocated into one of two groups (halothane or sevoflurane). In the 200 children in the first group (H), general anaesthesia was induced and maintained with halothane, whereas in the 220 children in the second group (S), anaesthesia was induced and maintained with sevoflurane. RESULTS: There were 79 children with a prior history of motion sickness (MS+) and 341 without such a history (MS-). In the MS+ population, the incidence of vomiting was similar in both H and S groups, being around 33%. However, repeated episodes of vomiting in MS+ children were more frequent when halothane was used. In the MS- group, the incidence of vomiting was significantly greater in the H group (19%) than in the S group (8%). CONCLUSIONS: In the postoperative period, we found that MS+ children vomit more than MS- children, regardless of the inhalation anaesthetic used. However, MS- children displayed a higher incidence of vomiting when halothane was used rather than sevoflurane.     

An outbreak of Serratia marcescens bloodstream infections associated with misuse of drug vials in a surgical ward.

We report an outbreak of Serratia marcescens bloodstream infection due to contamination of total parenteral nutrition solution by insulin or poligeline solution when single-use vials were used for multiple doses in a surgical ward. Four patients had severe sepsis, and no patient died. Multidose vials, used either correctly or incorrectly, may be associated with bloodstream infection.