Contextual modulation of synchronization to random dots in the cat visual cortex

Synchronization of neuronal activity has been proposed as a binding mechanism for integration of image properties into one coherent percept. In the present study, we investigated the contextual modulation of synchronization to random dot patterns. Coherent motion of random dots evoked well synchronized responses in area 17 of anaesthetized cats when the stimulus was presented in the compound receptive field of recorded sites. Gradually changing the directional coherence of random dots in the surround while maintaining fully coherent motion of the stimulus in the receptive field significantly suppressed synchronization of neuronal activity for some stimulus conditions. However, usually one or two peaks of increased synchronization were found in the surround coherence tuning curves with low (8–12%) and/or moderate (25–50%) coherence in the surround. At the population level, synchronization was significantly depressed with incoherent motion in the receptive field and when both the surround and the receptive field were jointly stimulated with 0% coherence. The intriguing finding was the discovery of two distinct groups of cells with opposite synchronization changes dependent on the presence or absence of significant synchronization in their spontaneous activity. The latter group of neurons showed peaks of increased synchronization with lower surround coherence, thus probably being more sensitive to the direction of the surround motion. Overall, our findings support the notion that binding of stimulus properties can be achieved by synchronized activity of cortical cells. However, our findings go further than the original hypothesis of feature binding by synchrony to show that synchronization of cortical activity may be directly related to the decision making processes, which in turn are related to the threshold of perception of coherent motion.     

Use of the Doppler flowmeter in stroke prevention.

The directional Doppler flowmeter can be used to identify collateral patterns of extracanial arterial blood flow that are associated with hemodynamically significant lesions of the internal carotid artery. The use of this non-invasive technique can identify accurately those patients who are candidates for angiographic confirmation.     

Anxiety during pregnancy and fetal attachment after in-vitro fertilization conception

The aim of this study was to compare 70 couples who had conceived by in- vitro fertilization (IVF) with 63 matched controls for the prevalence of anxiety and quality of attachment to the baby during pregnancy. Results for mothers showed no group differences using a global measure of anxiety, the Spielberger State-Trait Anxiety Inventory. However, pregnancy-specific measures revealed significantly higher levels of anxiety in IVF mothers about the survival and normality of their unborn babies, about damage to their babies during childbirth and about separating from their babies after birth. When IVF mothers were differentiated according to the number of treatment cycles, more differences in anxiety level were revealed, with most increases occurring in mothers who had experienced two or more treatment cycles. IVF fathers did not differ from controls on the global anxiety measure. No data on pregnancy-specific anxiety were available for fathers. Neither IVF mothers nor IVF fathers differed from controls on measures of attachment to the baby during pregnancy. Results are discussed in the context of the need for researchers to employ differentiated and issue-specific measures to identify concerns that may be unique to IVF couples. Clinical implications regarding the need for psychological support during pregnancy are also discussed.      

Effects of placental tissue on immunological responses

Using in vivo assays for alloreactivity, the responsiveness of maternal lymph node cells was shown to be increased when cells were harvested from both syngeneically and allogeneically pregnant mice. In addition, foetal liver and thymus cells induced a state of delayed type hypersensitivity to alloantigens whereas trophoblastic tissue, in the form of 12 to 15 day metrial glands, did not.

The influence of mouse placenta on in vitro immune responses was tested using 7-day ectoplacental cones as sources of trophoblastic tissue. Ectoplacental cones increased a T cell dependent but not a T cell independent antibody response, whereas T cell dependent cytotoxicity was reduced. The findings reported in this paper suggest that murine ectoplacental cones are a particularly useful tissue with which to study both specific and non-specific immunological activities of the trophoblast in syngeneic and allogeneic pregnancies.

     

Are clinicians failing to supply adequate information when requesting a histopathological investigation?

AIMS: There is a perception among histopathologists that specimens are often received without adequate clinical details. This is the first study to determine the adequacy of information provided when histopathological investigations are requested. METHODS: Two thousand sequential requests for histological examination were assessed for adequacy and completeness. RESULTS: There was no significant difference in the demographic details supplied by physicians and surgeons. Clinical details were inadequate in 6.1% of cases: those from physicians were significantly more often adequate (98.7% v 90.6%) and more often included a diagnosis (74.4% v 38.8%) than those from surgeons. Physicians were more likely to supply their name and contact number but requests frequently lacked details of the sender. CONCLUSIONS: Specimens are infrequently received with inadequate demographic details, but clinical details and details of the sender are more often lacking. Education of clinical colleagues is required if pathologists are to manage the demand for the service.     

Mucin is produced by clara cells in the proximal airways of antigen-challenged mice

Airway mucus hypersecretion is a prominent feature of many obstructive lung diseases. We thus determined the ontogeny and exocytic phenotype of mouse airway mucous cells. In naive mice, ciliated (approximately 40%) and nonciliated (approximately 60%) epithelial cells line the airways, and > 95% of the nonciliated cells are Clara cells that contain Clara cell secretory protein (CCSP). Mucous cells comprise < 5% of the nonciliated cells. After sensitization and a single aerosol antigen challenge, alcian blue-periodic acid Schiff's positive mucous cell numbers increase dramatically, appearing 6 h after challenge (21% of nonciliated/nonbasal cells), peaking from Days 1-7 (99%), and persisting at Day 28 (65%). Throughout the induction and resolution of mucous metaplasia, ciliated and Clara cell numbers identified immunohistochemically change only slightly. Intracellular mucin content peaks at Day 7, and mucin expression is limited specifically to a Clara cell subset in airway generations 2-4 that continue to express CCSP. Functionally, Clara cells are secretory cells that express the regulated exocytic marker Rab3D and, in antigen-challenged mice, rapidly secrete mucin in response to inhaled ATP in a dose-dependent manner. Thus, Clara cells show great plasticity in structure and secretory products, yet have molecular and functional continuity in their identity as specialized apical secretory cells.     

The use of successive blood-pressure measurements to estimate blood-pressure variability

Multiple daily, self-determined blood-pressure measurements were obtained from 254 hypertensive patients for 1 month. In an effort to establish a practical and reliable technique for estimating blood-pressure variability, standard deviations from three (at one time of day) or nine (throughout the day) successive self-determinations were compared with a reference value, taken to be the standard deviation for the entire month (252 determinations per subject). Neither the standard deviation of three measures taken on one occasion nor that of nine measures taken throughout the day correlated well with the reference value (average R₃=.21 for SBP, .20 for DBP; average R₉=.39 for SBP, .38 for DBP). However, when a sample consisting of 12 measures (taken three at a time, at the same time of day, weekly for 4 weeks) was used, the average correlation rose to .60 for SBP and .54 for DBP. Thus, it appears that 12 samples taken in this way provide a reliable estimate of the standard deviation for an entire month, and it is suggested that this sampling technique also would enhance the reliability of conclusions drawn from assessments of the prognostic value of blood-pressure variability.