Root meristematic cells of Viola faba were examined, with both light and electron microscopes, in order to study the behaviour of the nucleolar material during the mitotic process. Under light microscopy, the preprophase nucleolus is seen to consist of a densely stained material in which are embedded several unstained vacuole-like structures of varying size. The electron microscope reveals that the dense nucleolar material is formed of two struc turally distinct components, each segregated into irregularly shaped zones blending with one another. One of these components is represented by 150 A granules which, in places, are arranged into thread-like structures approximately 0.1 # in diameter; the other component apparently consists of fibrils 60 to 100 A in diameter. The large and medium sized intranucleolar vacuoles contain loosely scattered granules and fibrils similar to those just described. The granular and fibrillar components of the denser portion of the nucleolus persist as such during prophase and disperse throughout the nuclear cavity at the time of nucleolar disintegration. After nuclear membrane breakdown, these granules and fibrils, as well as those of the nucleoplasm, mix freely with similar elements already present within the forming spindle. No evidence has been obtained that, during or after nucleolar disintegration, the structural components of the nucleolus become associated as such with the chromosomes to form an external or internal matrix. Our observations suggest the existence, of a matrix substance within late prophase, metaphase, and anaphase chromosomes, the fine structure of which bears strong resemblance to that of their constituent coiled chromonemata. Data are presented, moreover, that indicate that part of this matrix substance, presumably formed at some time during prophase, is released from the chromosomes during their anaphasic movement. A number of observations indicate that the main bulk of the next nucleolus is derived from a prenucleolar fibrillogranular material, arranged into thread-like structures some 0.1 # in diameter, which collect in the interchromosomal spaces during early and midtelophase. Finally, our data would seem to favour the view that most of this prenucleolar material results from a resumption of the synthetic activity of the early and midtelophase chromosomes rather than from a mere shedding of a preexisting matrix substance.

Autoradiographic experiments using iodinated vasopressin analog revealed the presence of specific vasopressin-binding sites in the human adrenal cortex (zona glomerulosa and zona fasciculata). These receptors exhibited a good affinity for arginine vasopressin (3.3 nM), with classical V1a pharmacology and densities of 65 and 135 fmol/mg protein-enriched membranes from zona glomerulosa and fasciculata, respectively. Vasopressin receptors present in both glomerulosa and fasciculata cell-enriched primary cultures were coupled to phospholipase C (ED50, 0.9 and 1.8 nM; maximal stimulation, 4.3- and 5.8-fold, respectively). Vasopressin also stimulated an increase in intracellular calcium through at least two distinct mechanisms: the mobilization of intracellular pools via vasopressin-stimulated inositol phosphate accumulation and the activation of calcium influx. In glomerulosa cell-enriched primary cultures, vasopressin increased aldosterone secretion (ED50, 0.4 nM; maximal stimulation, 2.5-fold) and was found to be as potent as angiotensin-II in stimulating aldosterone secretion, phosphoinositide turnover, and calcium mobilization. In fasciculata cells, vasopressin and angiotensin-II were also able to stimulate cortisol secretion and inositol phosphate accumulation. Moreover, perifusion experiments demonstrated that vasopressin was released from the adrenal medulla. Together, these results indicate that vasopressin can be considered a potent paracrine modulator of adrenal steroid secretion in man.

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IntroductionNeuropeptides arginine-vasopressin (AVP), apelin (APL), and stromal-derived factor-1α (SDF-1α) are involved in the dysfunction of the corticotropic axis observed in septic ICU patients. Study aims were: (i) to portray a distinctive stress-related neuro-corticotropic systemic profile of early sepsis, (ii) to propose a combination data score, for aiding ICU physicians in diagnosing sepsis on admission.MethodsThis prospective one-center observational study was carried out in a medical intensive care unit (MICU), tertiary teaching hospital. Seventy-four out of 112 critically ill patients exhibiting systemic inflammatory response syndrome (SIRS) were divided into two groups: proven sepsis and non sepsis, based on post hoc analysis of microbiological criteria and final diagnosis, and compared to healthy volunteers (n = 14). A single blood sampling was performed on admission for measurements of AVP, copeptin, APL, SDF-1α, adrenocorticotropic hormone (ACTH), cortisol baseline and post-stimulation, and procalcitonin (PCT).ResultsBlood baseline ACTH/cortisol ratio was lower and copeptin higher in septic vs. nonseptic patients. SDF-1α was further increased in septic patients vs. normal patients. Cortisol baseline, ACTH, PCT, APACHE II and sepsis scores, and shock on admission, were independent predictors of sepsis diagnosis upon admission. Using the three first aforementioned categorical bio-parameters, a probability score for predicting sepsis yielded an area under the Receiver Operating Curve (ROC) curves better than sepsis score or PCT alone (0.903 vs 0.727 and 0.726: P = 0.005 and P < 0.04, respectively).ConclusionsThe stress response of early admitted ICU patients is different in septic vs. non-septic conditions. A proposed combination of variable score analyses will tentatively help in refining bedside diagnostic tools to efficiently diagnose sepsis after further validation.