The restorative effect of naps on perceptual deterioration

Human performance on visual texture discrimination tasks improves slowly (over days) in the absence of additional training. This 'slow learning' requires nocturnal sleep after training and is limited to the region of visual space in which training occurred. Here, we tested human subjects four times in one day and found that with repeated, within-day testing, perceptual thresholds actually increased progressively across the four test sessions. This performance deterioration was prevented either by shifting the target stimuli to an untrained region of visual space or by having the subjects take a mid-day nap between the second and third sessions.     

Imagery Vividness Affects Habituation Rate

In order to investigate the effect of individual differences in imagery vividness on habituation rate, 14 subjects were threatened with receiving and then imagined receiving an electric shock. Subjects first habituated to a tone which was then used as an auditory signal for the shock threat and the imagined shock. The skin conductance response (SCR) was used to follow the course of habituation. Results demonstrated that subjects with non-vivid imagery habituated to the tone more rapidly than subjects with vivid imagery when the tone was associated with imagining an electric shock. Implications of this finding for therapeutic techniques using instructed imagery are discussed.     

Roles of Department of Clinical Laboratory in infection control

The Department of Clinical Laboratory plays an important role in the hospital and has much information about patients and pathogens. Laboratory data are essential to support clinical physicians who diagnose and treat patients. For nosocomial infections, laboratory-based surveillance is recognized as essential to confirm outbreaks. Therefore, the role of the Department of Clinical Laboratory is very important in infection control. In Tohoku University Hospital, we have an Infection Control Unit located in the Department of Clinical Laboratory. The core role of the Infection Control Unit is diagnosis, treatment and preventative healthcare associated with infections. The Infection Control Team (ICT) performs rounds in the hospital (The ICT members are ICN, ICD, a microbiological technologist and a dietician), consultations about clinical cases, infection control, and organize the regional infection control network, "Miyagi Infection Control Network". The ICT rounds are performed once a week in two wards, and two times a year for one ward. The consultations are an important role of the ICD, and concern clinical infection cases and infection control in our hospital and the other regional hospitals, and produce advice on appropriate clinical information. The regional network is important for the collection of information about the pathogens and the susceptibility of antimicrobial agents in the region. "Miyagi Infection Control Network" has held a forum 5 times a year from 1999, and 300-400 healthcare workers join the forum and discuss infection control.     

Appearance of prolactin-releasing peptide-producing neurons in the area postrema of adrenalectomized rats

Prolactin-releasing peptide (PrRP) was found to be a novel hypothalamic peptide that stimulates prolactin release in vitro and in vivo. In the normal adult rat brain, PrRP neurons are known to be located in only three areas, i.e. the dorsomedial hypothalamic nucleus, ventrolateral reticular formation; and nucleus of the tractus solitarius in the medulla oblongata. These PrRP neurons project neurites into various brain areas, including regions such as the paraventricular nucleus, supraoptic nucleus, and bed nucleus of the stria terminalis. Both PrRP nerve fibers and a high level of PrRP receptor, UHR-1, mRNA are observed in the area postrema (AP),but no PrRP neurons are detected in the AP of normal rats. In this study, we clearly demonstrated that PrRP-producing cells newly appeared in the AP of adrenalectomized rats by in situ hybridization and immunocytochemistry. Our results suggest that PrRP may have some important roles in the AP of adrenalectomized rats. This is the first report demonstrating the appearance of PrRP-positive cells in the AP.     

Hormone therapy and affect

This study investigated the influence of hormone therapy on affect in a double blind crossover trial. The sample consisted of 49 women who had previously undergone hysterectomy and bilateral oophorectomy. Therapy consisted of 3 mth each of ethinyl oestradiol — 50 μg/day, levonorgestrel — 250 μg/day, “Nordial” — a combination of these two substances, and placebo. Affect was measured by the Hamilton Depression Rating Scale, verbal reports by women and self-ratings on visual analogue scales. Ethinyl oestradiol was found to have a beneficial influence on aspects of affect such as Hamilton scores, anxiety, irritability and insomnia.

The influence of hormones on Hamilton scores could be partly but not fully explained by the alleviation of hot flushes. Norgestrel showed less favourable changes initially but these tended to diminish by the third therapy month. Most of the women studied were not clinically depressed. Anxiety symptoms were the major features exhibited in the group of women investigated. The results of this study suggest that visual analogue rating scales are of questionable validity in assessing affect in patients without any appreciable psychiatric morbidity.     

Pancreatic endocrine tumours associated with WDHA syndrome

Summary Nine pancreatic endocrine tumours of patients with watery diarrhoea hypokalaemia achlorhydria (WDHA) syndrome were examined by immunohistochemistry and electron microscopy. All cases revealed neoplastic proliferation of VIP (vasoactive intestinal peptide)-immunoreactive (IR) cells. Immunoreactivity to a novel peptide hormone PHM-27, which is processed from a common big precursor peptide of VIP (prepro VIP/PHM-27), was identified in VIP-IR cells of 8 tumours. VIP-PHM-IR cells had secretory granules measuring about 130 to 220 nm in diameter. Radioimmunoassay of tumour tissue extracts showed high VIP and PHM contents in proportional amounts in most cases. According to the results of immunostaining, the 8 tumours fell into two large groups; 5 with PP (pancreatic polypeptide)-IR cells and 3 with CT (calcitonin)-IR cells. The former group demonstrated VIP cells and PP cells intermingled in various proportions, including one tumour in which coexistence of PP-IR and VIP-IR in the same cells was demonstrated. Cell heterogeneity of the tumours and possible relationships of VIP, PP and CT cells were discussed.This work was supported in part by Grants-in-Aid for Cancer Research from the Ministry of Health and Welfare and from the Ministry of Education, Science and Culture, Japan     

Identification of neural genes using Xenopus DNA microarrays.

To isolate novel genes regulating neural induction, we used a DNA microarray approach. As neural induction is thought to occur by means of the inhibition of bone morphogenetic protein (BMP) signaling, BMP signaling was inhibited in ectodermal cells by overexpression of a dominant-negative receptor. RNAs were isolated from control animal cap explants and from dominant-negative BMP receptor expressing animal caps and subjected to a microarray experiment using newly generated high-density Xenopus DNA microarray chips representing over 17,000 unigenes. We have identified 77 genes that are induced in animal caps after inhibition of BMP signaling, and all of these genes were subjected to whole-mount in situ hybridization analysis. Thirty-two genes showed specific expression in neural tissues. Of the 32, 14 genes have never been linked to neural induction. Two genes that are highly induced by BMP inhibition are inhibitors of Wnt signaling, suggesting that a key step in neural induction is to produce Wnt antagonists to promote anterior neural plate development. Our current analysis also proves that a microarray approach is useful in identifying novel candidate factors involved in neural induction and patterning.     

Mouse embryonic diastema region is an ideal site for the development of ectopically transplanted tooth germ.

The anterior eye chamber and the kidney capsule of the mouse have been traditionally used for long-term culture of tooth germ grafts. However, although these sites provide an excellent growth environment, they do not represent real in situ sites for the development of a grafted tooth germ. Here, we describe a protocol to transplant a tooth germ into the mandibular diastema region of mouse embryos using exo utero surgery. Our results demonstrate that the mouse embryonic diastema region represents a normal physiological environment for the development of transplanted tooth germs. Transplanted tooth germs developed synchronically with and became indistinguishable from the endogenous ones. These ectopic teeth were vascularized and surrounded with nerve fibers, and were able to erupt normally. Thus, the exo utero transplantation approach will provide a new avenue to study tooth development and regeneration.     

Restricted expression of transgenic HLA-DRA gene in thymic epithelial cells and its role in acquisition of T cell tolerance to self-superantigens and processed DRα-derived peptide

We have established a set of transgenic mouse lines in which the HLA-DRA gene was expressed in different cell types. In one line (DRα-24), DRαEβ^b molecules were expressed on thymic medullary and cortical epithelial cells and all lineages of bone marrow-derived antigen-presenting cells (APC) except for thymic macrophages. By contrast, expression of the molecules in another line (DRα-30) was found on thymic medullary and cortical epithelial cells but not on bone marrow-derived APC in the thymus and periphery. To evaluate the role of thymic epithelial cells in acquisition of T cell tolerance, comparative analysis of DRα-24 and DRα-30 was performed. In DRα-30, T cells expressing TcR Vβ5 and Vβ11 were eliminated to comparable levels to those in DRα-24, suggesting that expression of the DRαEβ^b molecules on thymic epithelial cells are sufficient for clonal deletion of the self-superantigen-reactive T cells. In addition, CD4⁺ T cells from DRa-30 as well as those from DRα-24 were tolerant to DRα-derived peptide/I-A^b complex expressed on spleen cells from DRα-24 even in the presence of exogenous interleukin-2. These observations suggest that expression of the DRα chain in thymic epithelial cells could induce T cell tolerance directed toward naturally processed DRα-derived peptide bound to I-A^b molecules, probably via clonal deletion of the self-reactive T cells.