Characterization of a common precursor population for dendritic cells

Dendritic cells (DCs) are essential for the establishment of immune responses against pathogens and tumour cells, and thus have great potential as tools for vaccination and cancer immunotherapy trials. Experimental evidence has led to a dual DC differentiation model, which involves the existence of both myeloid- and lymphoid-derived DCs. But this concept has been challenged by recent reports demonstrating that both CD8- and CD8+ DCs, considered in mice as archetypes of myeloid and lymphoid DCs respectively, can be generated from either lymphoid or myeloid progenitors. The issue of DC physiological derivation therefore remains an open question. Here we report the characterization of a DC-committed precursor population, which has the capacity to generate all the DC subpopulations present in mouse lymphoid organs---including CD8- and CD8+ DCs, as well as the B220+ DC subset---but which is devoid of myeloid or lymphoid differentiation potential. These data support an alternative model of DC development, in which there is an independent, common DC differentiation pathway.     

Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized,sulpiride-treated and melatonin-replaced rats

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.     

The choroid in the eye of the eel (Anguilla anguilla)

Summary By means of light and scanning electron microscopy evidence of the existence of a normally organized choroid in the eye of the eel,Anguilla anguilla, is presented.     

Induction of electrical excitability in crustacean muscle by 4-cyclopentene-1,3-dione

Summary 4-Cyclopentene-1,3-dione induces electrical activity in inexcitable crustacean muscle. This effect is blocked by previous treatment with p-chloromercuribenzoic acid. These results suggest that crustacean muscle becomes excitable when certain-CH₂-SH side chains are converted to thioethers having carbonyl groups.Acknowledgments. This work was supported by USPHS Nos NS-07464, NS-14938 and GM-05784. Contribution No. 80 of the Laboratory of Neurobiology.     

Mechanisms of coronary vasoconstriction induced by Na arachidonate in experimentally diabetic dogs

Summary Na arachidonate (NaA) enhanced the resting basal tone of isolated coronary arteries from diabetic dogs and depressed it in coronary arteries from normal controls. Inhibitors of thromboxane A₂ biosynthesis and of lipoxygenases abolished the vasoconstrictor effect of NaA on diabetic arteries, whereas inhibitors of cyclooxygenase activity and PGI₂ biosynthesis blocked the vasodilating action of NaA on normal arteries.This work has been supported by grant 6638 from CONICET (Argentina).     

Colloidal carbon as a multilevel marker for experimental lesions

The use of colloidal carbon for the anatomical marking of experimental lesions is proposed. Visualization of the lesion site may be readily performed through this procedure at the macroscopic, light microscopic, and ultrastructural levels in the same specimen. The chemical inertness of the marker and its relative permanency greatly add to its usefulness.     

Die Wirkung einer Leberschädigung durch Thioacetamid auf die mikrosomale Aromatisierung von Testosteron bei der Ratte

Summary Rat liver microsomes, NADPH-regenerating system, and 1, 2-³H-testosterone have been incubated in vitro. The loss of tritium from the steroid, associated with aromatization of testosterone, was linear with time for 20 min and required NADPH. Pre-treatment of the rats with thioacetamide raised the liberation of tritium from 1, 2-³H-testosterone. The results suggest that liver damage by thioacetamide in rats may give rise to increased aromatization of testosterone.