Showing papers by "University of Vermont published in 1970"

Hemolysis near an ultrasonically pulsating gas bubble

Abstract: A small volume of an erythrocyte suspension was subjected to the action of a manipulated gas bubble set into stable oscillation at 20 kilohertz. Release of hemoglobin occurred when the oscillation amplitude exceeded a critical threshold. Hydrodynamic stresses resulting from acoustically induced small-scale eddying motion near the bubble may be the mechanism of hemolysis.

Reinforcement of Competing Behavior during Extinction

Abstract: Conditioned behavior declines in frequency when reinforcement is discontinued. In two experiments this extinction process was facilitated when competing behavior was reinforced as the original response was extinguished. When reinforcement for competing behavior was withdrawn, however, rats resumed their original behavior and there were no overall savings in total responses to extinction.

Hemolysis near a transversely oscillating wire.

Abstract: Erythrocyte suspensions were subjected to hydrodynamic forces generated by a partially submerged tungsten wire set into transverse oscillation at 20 kilohertz. Free hemoglobin appears in solution when the oscillation amplitude exceeds a critical threshold value. The hemolysis probably results from stresses exerted on cell by a microstreaming field established near the wire.

An electron microscopic localization of calcium in the small intestine of normal, rachitic, and vitamin-D-treated rats.

Abstract: The intracellular localization of calcium in the mucosal lining of the small intestine of normal, rachitic, and Vitamin D2 treated rats was studied using45Ca-autoradiography, microincineration, and electron microscopy. Small, electron-dense granules and autoradiographic label were seen primarily within microvilli and mitochondria. The granules were sparse in mitochondria from rachitic rats while normal rat mitochondria demonstrated them regularly. The mitochondria of Vitamin-D2-treated rats contained numerous electron dense granules. These granules remained following microincineration. An inverse relation in the amount of granules appearing in the mitochondria and in the microvillus was found. Granules were limited to the microvillus region in the rachitic animals and increased significantly in the mitochondria following treatment with Vitamin D2. This study indicates that a large amount of calcium is absorbed across the cell membrane and is then bound within the microvillus. Vitamin D is apparently necessary for mobilizing this bound calcium from the microvilli. The mobilized calcium enters the mitochondria or passes through the cell to the adjacent blood vessels.

Training consulting teachers to assist elementary teachers in the management and education of handicapped children.

Abstract: A graduate program designed to train consulting teachers is discussed. Students were instructed in behavior modification techniques and in means of assisting regular classroom teachers with the social and academic behaviors of handicapped children. Three case studies illustrating the types of projects conducted by students are presented.

The ultrastructure of the compound eye of a mosquito Aedes aegypti L

Abstract: Each ommatidium in the mosquito compound eye consists of a dioptric apparatus and layer of retinula cells. The dioptric apparatus includes a cuticular cornea, a biconvex lens, and four cone cells. The cone cells have processes which extend into the receptor layer and terminate below the rhabdom as pigment-filled sacs. Two primary pigment cells and an undetermined number of secondary pigment cells surround the dioptric apparatus. In the receptor layer eight retinula cells are found in each ommatidium. Six are peripherally arranged around a central one, whereas the remaining retinula cell is sandwiched between and somewhat external to two of the peripheral retinula cells. Each of the eight retinula cells possesses a well developed rhabdomere, along with the usual array of other intracellular organelles characteristic of arthropod photoreceptor cells.

Influence of polyvalent cations on the activation of muscle end plate receptors.

Abstract: The influence of polyvalent cations on the activation of end plate receptors has been studied in vitro on the sartorius muscle of the frog. In the absence of extracellular calcium, the sensitivity of the receptors to depolarizing quaternary ammonium salts was markedly reduced. Maximum receptor activation occurred in those fibers equilibrated in 1.8 mM calcium Ringer solution, with the response being reduced as the calcium concentration was raised or lowered. Magnesium was less efficient than calcium in regulating the sensitivity of the end plate receptors, the maximum receptor response occurring in those fibers equilibrated in 8 mM magnesium Ringer solution. In the presence of lanthanum the end plate response to carbamylcholine or acetylcholine was enhanced. Lanthanum increased the conductance change produced by carbamylcholine both in polarized and in potassium-depolarized fibers. The application of 10-2 mM lanthanum to the end plate increased MEPP's amplitude, rise time, and half-fall time by 19, 54, and 45%, respectively. The results suggest that polyvalent cations influence postjunctional membrane receptor processes in addition to their well-documented prejunctional action.

The timer-game: a variable interval contingency for the management of out-of-seat behavior.

Abstract: The timer-game was demonstrated to be a practical and effective procedure for managing the out-of-seat behavior of elementary school children in a remedial classroom. The timer-game allowed the stu...

Production of interferon following an immune response

Abstract: The r e l a t i o n s h i p between i n t e r f e r o n product ion and immune phenomena -i n viva h a s been l i t t l e s tud ied . 1965 t h a t pas s ive admin i s t r a t ion of an t ibod ie s t o Newcastle d i s e a s e v i r u s (NDV) i n h i b i t e d t h e i n t e r f e r o n product ion of mice chal lenged with the same v i r u s . i n humans who had had a c t i v e measles i n f e c t i o n and who had subsequent ly been challenged wi th a t t enua ted measles v i r u s a s a means of s t i m u l a t i n g i n t e r f e r o n . Borecky , Lackovic, and Waschke3 found t h a t a n t i v i r a l a n t i bodies suppressed t h e a b l l i t y of NDV v i r h s t o cause i n t e r f e r o n appearance, b u t i n c o n t r a s t immunization aga ins t endotoxin enhanced t h e a b i l i t y of mice so immunized t o produce i n t e r f e r o n . Youngner and S t i n e b r i n g l r epor t ed i n

Clinical hypersensitivity to cigarette smoke.

Abstract: Eight individuals were observed to have clinical hypersensitivity to cigarette smoke, as well as lymphocyte stimulation when their peripheral blood lymphocytes were incubated in vitro with cigarette smoke. All eight individuals were nonsmokers with strong allergic backgrounds and all developed immediate upper respiratory discomfort after being exposed to cigarette smoke. Cigarette smoke may be responsible for respiratory distress in nonsmoking sensitized individuals

Ethnobotany of cañihua (Chenopodium pallidicaule), rustic seed crop of the Altiplano

Abstract: Canihua, Chenopodium pallidicaule, is a weedy plant cultivated by Indian fanners on the Altiplano of Peru and Bolivia. Because canihua is resistent to low temperatures, drought, salty soil, disease, and pests, it has achieved importance in the agricultural system, but only because it prospers where other crops are often marginal food producers. Its dual usage of seed and ash, high protein content, and function as an insurance crop explain its persistence, but its future role in Altiplano agriculture may depend on its genetic improvement.

Relationships between blue‐green and red algae *

Abstract: The past decade has seen a revolution in biological thinking comparable in many respects to the period following the publication of Charles Darwin’s Origin o f Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle f o r Life. We have witnessed and participated in the advent and flowering of molecular genetics, molecular biophysics, and molecular biochemistry, biological disciplines whose impact will continue to influence our teaching and our researches. The concepts that are now part of the present world of biological thought have, as they should and must, provided new orientations and new horizons. Morphology and taxonomy, fields that are basic to our evaluation of life, are actively participating in molecular approaches and their child, evolutionary theory, is more sophisticated as a consequence. Phylogeny, the study of the evolutionary relationships among organisms, is an ugly duckling, by its very nature not susceptible to the experimental method of external verification and interlocking proofs. The operational word in phylogenetic study is “reasonable.” The phylogeneticist hesitates a long time before becoming so rash as to use the word “possible” and “probable” is a word that scarcely passes his lips. Those who speculate on the relationships among plants realize that we are as much philosophers as scientists and although most have Doctor of Philosophy degrees, we tend to be uncomfortable in the role. Although to some, the attempt to separate organisms into taxa, i.e., into hierarchical rankings based on presumed genetic and evolutionary relationships, is a sterile pedantic exercise, I submit that such speculations are reasonable activities and that they have heuristic values in biological thought. As a base for such thinking, the first major task is the ancient one of determining the minimum number of supertaxa needed to include all the organisms that have ever lived. The arguments on this point have centered on the question of whether there should be two, three, four, or more Kingdoms. As we 24 and Allsopp3 have stated, the two-Kingdom approach is favored with the proviso that there be an amorphous grouping of ancient living things that can be termed Archaic. This position is the classical one, a term which has regrettably acquired a pejorative connotation in several recent publications.Il3 2 5 ~ 34 Indeed, the fervor with which the concept of the Kingdom Protista is embraced is surprising in view of its classical history, Ernst Haeckel 21 coined the term in 1866 to include all unicellular organisms not easily seen by the unaided eye. Later developments in optics and laboratory manipulations have resulted in the extension of Haeckel’s operational construct to contain the bacteria (including the Rickettsiales, etc.) , the algae, fungi (including the slime molds), the protozoa and, apparently by

Purified Influenza Vaccine: Clinical and Serologic Responses to Varying Doses and Different Routes of Immunization

Abstract: Recently a purified bivalent influenza vaccine prepared by zonal ultracentrifugation was described, which appeared to be highly antigenic and to cause few side reactions [1, 2]. During the 1968-1969 epidemic of influenza caused by the Hong Kong variant of influenza A2 virus, a highly purified monovalent influenza vaccine was prepared in a similar manner and made available for field testing. Because it was highly purified and could be concentrated in the zonal ultracentrifuge, the vaccine was available in preparations of different potency. This made it possible to give the vaccine at different levels of dosage and to compare antigenic response and incidence of side reactions to a single subcutaneous inoculation. Although the usual route of immunization employed with killed influenza vaccines is the subcutaneous one, physicians have frequently used the intradermal route in patients who have given a history of previous severe local reactions to the vaccine or when vaccine is in short supply. Recent reports have also suggested that administration of the vaccine intranasally may be a more effective way of obtaining local antibody and

Antibacterial activity of gentamicin sulfate in tissue culture.

Abstract: Gentamicin is a more effective in vitro bacterial inhibitor than combined penicillinstreptomycin, is nontoxic to tissue culture monolayers, and does not inhibit virus replication.

Ribonuclease-inhibitor system abnormality in dystrophic mouse skeletal muscle.

Abstract: Skeletal muscle extracts from mice with muscular dystrophy contain severalfold higher than normal levels of free alkaline ribonuclease II activity and none of the free ribonuclease inhibitor normally present. This abnormal pattern is not seen in heart or liver extracts from dystrophic mice.

Conversion of Histidine to Hercynine by Neurospora crassa

Abstract: Cell-free extracts of Neurospora crassa mycelium catalyze the methylation of l-histidine to form hercynine (histidine betaine). The partially methylated compounds, α-N-methyl-l-histidine and α-N,N-dimethyl-l-histidine, are also methylated by the same enzyme preparation to form hercynine. All three methylation reactions are stimulated by the addition of S-adenosylmethionine.

Examination of “Species Specificity” of Avian Interferons

Abstract: INTERFERON preparations usually show some degree of species specificity in their antiviral effects, exerting their greatest effect on growth of viruses in cells of the species which produced the interferon, and being less active or totally inactive in cells of other species1–3. Recent studies have shown that species specificity is far from absolute: certain human and primate interferons have proved active in rabbit cells4; the activity of monkey interferon in human cells was first noted by Isaacs et al.5, and cross-reactivity of human and monkey interferon systems at the level of the taxonomic family has been demonstrated6. Mouse serum interferon expresses one-twentieth of its mouse cell activity on other rodent cells7.