Testing the scanning effect of a range of orientations by visual cortex neurons of the cat

The preservation of the effect of dynamic scanning of a part of the orientation diapason during development of neuron responses in the primary visual cortex of cat was examined after equalization of their latencies and after estimation of only highly significant fragments of their reactions. It was found that this effect was preserved in 13 neurons out of 17 examined ones: it remained invariable in 7 units of this group and was modified due to a shift of the scanning beginning along the diapason of orientations, to an increase of scanning diapason or to a change of scanning direction. The stabilization of the orientational tuning occurred only in 4 cells after equalization of latencies. The obtained results confirm that the dynamic changes of orientation tuning in the majority of visual cortex neurons are connected with reorganization of the time pattern of the reaction, as suggested by the hypothesis of the spatial-temporal orientation coding in the visual system.     

Changes in respiration during acclimatization in the interior of Antarctica

Summary Observations were made at the Soviet antarctic station, Vostok. Tachypnea and considerable hyperventitation were observed during the first days after arrival at the station. With acclimatization, the frequency of respiration restored to the normal, pulmonary ventilation decreased, reaching the lowest level during the polar night period (however, even during that period it is 1 1/2 times greater than the normal value); the depth of respiration increased considerably. During the whole period of stay in Antarctica every individual had Cheyne-Stokes respiration, especially during sleep. Dyspnea increased considerably, even during slight physical strain. Composition of alveolar an became stabilized at a new level corresponding to a partial oxygen pressure of 53–56 mm Hg and to CO₂ pressure of 26–29 mm Hg. The blood oxygenation during quiet respiration was 80–87%, increasing with voluntary hyperventilation to 85–94%. Hypoxemia rose considerably with voluntary breath holding and physical strain.Presented by Active Member AMN SSSR, A. V. Lebedinskii Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 57, No. 1, pp. 20–23, January, 1964     

Adenosine receptors in regulation of dendritic cell differentiation and function

Differentiation of functional dendritic cells (DCs) critically depends on the microenvironment. DCs differentiate in hypoxic tumor sites and inflamed or damaged tissue. Because local concentrations of adenosine reach high physiologically relevant levels in these conditions, we assessed the expression of adenosine receptors and the effect of their activation on differentiation of human monocytes and mouse peritoneal macrophages and hematopoietic progenitor cells (HPCs) into myeloid DCs. Stimulation of adenosine receptors skews DC differentiation toward a distinct cell population characterized by expression of both DC and monocyte/macrophage cell surface markers. Pharmacologic analysis and experiments with cells from A(2B) adenosine receptor knockout mice identified A(2B) receptor as the mediator of adenosine effects on DCs. Unlike normal myeloid DCs, adenosine-differentiated DCs have impaired allostimulatory activity and express high levels of angiogenic, pro-inflammatory, immune suppressor, and tolerogenic factors, including VEGF, IL-8, IL-6, IL-10, COX-2, TGF-beta, and IDO. They promoted tumor growth if injected into tumors implanted in mice. Using adenosine desaminase knockout animals, we showed that DCs with proangiogenic phenotype are highly abundant under conditions associated with elevated levels of extracellular adenosine in vivo. Adenosine signaling through A(2B) receptor is an important factor of aberrant DC differentiation and generation of tolerogenic, angiogenic, and proinflammatory cells.     

A pancreatic intraductal papillary mucinous tumor causing recurrent acute pancreatitis at the onset of menstrual periods

The unusual case of a young woman with pancreatitis recurring at onset of her menstrual periods is reported. The patient was diagnosed with pancreatic intraductal papillary mucinous tumor (IPMT). The temporal relation of clinical exacerbation of pancreatitis to the menstrual cycle is suggestive of a hormonal-mediated mechanism. The hypothesis of a possible role of progesterone receptors was dismissed with verification of the absence of progesterone and estrogen receptors in the neoplastic tissue. The possible role of activin A or inhibin A in our patient's clinical picture is theorized.