Microorganisms and ion absorption by roots

Résumé Les comparaisons des taux d'absorption de K par des racines d'orge stériles et non-stériles,Hordeum vulgare, dans l'ordre de concentration de 0,02–50 mM, ont montré que le double mode de transport d'ion décrit auparavant pour des racines non-stériles, s'applique également aux racines stériles. La microflore de la racine n'a influencé que légèrement les taux d'absorption de K.

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I thankD. L. Fredrickson for assistance with these experiments andF. E. Broadbent for advice. This research was supported by a grant from the Office of Saline Water, United States Department of the Interior.     

Immunoglobulin synthesis by cord blood lymphocytes

Summary The IgG, IgA and IgM synthesis by adult peripheral blood and cord blood lymphocytes incubated alone and with pokeweed mitogen was quantitated. The cord blood lymphocytes produced no immunoglobulin even with mitogen stimulation while the adult peripheral blood lymphocytes responded to the mitogen with a significant (p<0.04) increase in immunoglobulin production.     

Immunoglobulin synthesis by cord blood lymphocytes.

The IgG, IgA and IgM synthesis by adult peripheral blood and cord blood lymphocytes incubated alone and with pokeweed mitogen was quantitated. The cord blood lymphocytes produced no immunoglobulin even with mitogen stimulation while the adult peripheral blood lymphocytes responded to the mitogen with a significant (p less than 0.04) increase in immunoglobulin production.     

Carcinogenicity of tetraethyl lead

Zusammenfassung Ein vermehrtes Vorkommen von Lymphomas zeigte sich bei mit Tetraäthylblei behandelten weiblichen Mäusen (12%) im Gegensatz zu den entsprechenden Kontrollen (0%). Die carcinogene Wirkung von Tetraäthylblei wurde durch parenterale Administration einer totalen Dosis von 0.6 mg an neugeborenen Schweizer Mäusen gezeigt.

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Supported by Grant No. C-6516 from the National Cancer Institute, USPHS.     

An improved noninfections murine skin model of organized granulomatous inflammation

Summary An improved model of granulomatous inflammation in skin was developed by second passage skin grafting of isolated, lyophilized skin granulomas, originally elicited in naive mice by inoculations of lyophilized hepatic schistosome egg granulomas. The tissue reaction is caused by a single exposure to a noninfectious, acellular granulomagenic stimulus and occurs in healthy mice free of systemic disease. The model should prove useful for isolation of granuloma initiation factor(s). Furthermore, because there is a time lag before new granuloma formation begins, a window exists for analytical dissection of the initiation process. In this study we described the responses of host cells by autoradiography, and light and electron microscopy. The activity of angiotensin-converting enzyme and proline-specific endopeptidase showed a modulation during granuloma formation. In addition we found that severe immunosuppression with high dose cyclosporine therapy did not alter granuloma formation, supporting the idea that initiation of organized granulomas is T-cell independent.     

Mitochondrial activity: A possible determinant of anoxic injury in renal medulla

Summary In brain¹, heart² and kidney³, cell work in the absence of oxygen has been thought to precipitate anoxic damage by increasing the rate of depletion of cellular energy stores. In the medullary thick ascending limb of isolated perfused rat kidneys, however, reduction of ATP synthesis by a variety of mitochondrial or metabolic inhibitors caused ATP depletion comparable to that produced by oxygen deprivation but did not reproduce the lesions of anoxia. In these cells, unrestrained mitochondrial activity may be an important source of anoxic injury.     

Flow in the phloem and the immobility of calcium and boron: A new hypothesis in support of an old one

Résumé Contrairement à la plupart des éléments nutritifs, le calcium et le bore sont en grande partie exclus des tubes criblés et par conséquent ne sont pas efficacement distribués dans la plante, ce qui est apparemment désavantageux. On suppose que l'exclusion de ces deux éléments des tubes criblés favorise leur maintien comme conduits ouverts.