Histochemical Aspects of the Affinity of Mast Cell Granules for Night Blue

The affinity of mast cell granules for night blue was studied in fresh and fixed rat lip, dog mast cell tumor, normal human ileum, and human mast cell and carcinoid tumors. Fixatives used were 10% formalin, 1% trichloracetic acid in absolute alcohol, and Zenker's and Bouin's fluids. Extractions of fresh tissue with hot water, acids, and bases removed the stainable material or prevented staining, but similar treatment of fixed tissue did not. Hot pyridine was without effect as was chloroform-methanol, but methylation blocked mast cell staining by night blue. Chromic acid oxidation and prolonged Zenker and Bouin fixation also prevented staining. Hyaluronidase treatment was without effect. Sulfhydryl and disulfide linkages were changed without altering the stainability.     

Learning to Produce Syllabic Speech Sounds via Reward-Modulated Neural Plasticity

At around 7 months of age, human infants begin to reliably produce well-formed syllables containing both consonants and vowels, a behavior called canonical babbling. Over subsequent months, the frequency of canonical babbling continues to increase. How the infant’s nervous system supports the acquisition of this ability is unknown. Here we present a computational model that combines a spiking neural network, reinforcement-modulated spike-timing-dependent plasticity, and a human-like vocal tract to simulate the acquisition of canonical babbling. Like human infants, the model’s frequency of canonical babbling gradually increases. The model is rewarded when it produces a sound that is more auditorily salient than sounds it has previously produced. This is consistent with data from human infants indicating that contingent adult responses shape infant behavior and with data from deaf and tracheostomized infants indicating that hearing, including hearing one’s own vocalizations, is critical for canonical babbling development. Reward receipt increases the level of dopamine in the neural network. The neural network contains a reservoir with recurrent connections and two motor neuron groups, one agonist and one antagonist, which control the masseter and orbicularis oris muscles, promoting or inhibiting mouth closure. The model learns to increase the number of salient, syllabic sounds it produces by adjusting the base level of muscle activation and increasing their range of activity. Our results support the possibility that through dopamine-modulated spike-timing-dependent plasticity, the motor cortex learns to harness its natural oscillations in activity in order to produce syllabic sounds. It thus suggests that learning to produce rhythmic mouth movements for speech production may be supported by general cortical learning mechanisms. The model makes several testable predictions and has implications for our understanding not only of how syllabic vocalizations develop in infancy but also for our understanding of how they may have evolved.     

Synthesis of L-fucose in thyroid tissue

A de novo pathway for L-fucose synthesis has been detected in porcine thyroid tissue. This system uses guanosine diphospho-alpha-D mannose as a precursor and forms guanosine diphospho-beta-L-fucose as product. The system seems similar to those reported by others to exist in microorganisms and plants in that the first step of the pathway involves a 4-keto sugar nucleotide intermediate. The first enzyme of the pathway, guanosine diphospho-alpha-D-mannose oxidoreductase has been purified 57-fold from crude extracts by virtue of its affinity for Blue Sepharose.     

Studies in parasitic watermolds of Kumaun Himalayas: The host range of five species of olpidiopsis

The host range of five species of Olpidiopsis in some species of Achlya, Aphanomyces, Brevilegnia, Isoachlya, Saprolegnia, Thraustotheca and Pythium was studied. Species were different in their host range.     

Trypanosoma cervi from Alaskan Reindeer,Rangifer tarandus1

Twenty-nine (64.4%) of 45 reindeer, Rangifer tarandus, examined over a two-year period were infected with trypanosomes. Trypomastigotes and dividing epimastigotes were found in the blood of fawns, cows, and bulls. Morphometric analysis of bloodstream trypomastigotes from reindeer and comparison of these parasites with similar stages of trypanosomes from elk, mule deer, and white-tailed deer from the contiguous United States proved them conspecific; the trypanosomes from these members of the Cervidae are identified as Trypanosoma cervi Kingston & Morton, 1975. This is the first report of trypanosomes from reindeer. No pathogenic effects are known to be caused by these parasites.     

Retinol induces platelet aggregation via activation of phospholipase A2

All-trans-retinol induced aggregation of rabbit platelets, and this effect could be inhibited by a cyclooxygenase inhibitor and a thromboxane A2 (TXA2) receptor antagonist, indicating an essential role for endogenously produced TXA2. We found a two-phase arachidonic acid release in retinol-stimulated platelets. The first phase was induced by the action of retinol alone and not inhibited by TXA2 receptor antagonist. The second phase was induced via synergistic action of retinol and initially generated small amount of TXA2, and was inhibited by the antagonist. Moreover, we discussed that the arachidonic acid release may be mediated by the action of phospholipase A2.     

The radiosensitivity of cultured human and mouse keratinocytes

Clonogenic survival assays after gamma-radiation in vitro were performed on freshly isolated and subcultured keratinocytes from mouse skin, mouse tongue and human skin. Survival curves were constructed by fitting the data to a multi-target model of cell survival. When subcultured, keratinocytes from all sites produced survival curves which showed a reduced shoulder region and an increased D0 when compared with their freshly isolated counterparts. Freshly isolated human skin keratinocytes were more radiosensitive than mouse keratinocytes from either skin or tongue.