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Al tiempo que la especie humana se caracteriza por una audaz y febril propensión a comprender, hay en el hombre una tendencia instintiva, un sesgo intelectual natural para aceptar con facilidad las constataciones agradables de la vida. Una ancestral inclinación a dar la espalda a una realidad de la cual sospechamos que tiene algo que nos disgusta, nos avergüenza o nos rebaja, en lugar de enfrentarla, conocerla, descubrirla, de curiosear en ella...

Intrathymic (IT) injection of alloantigen has been shown to induce unresponsiveness to allografts although the exact mechanisms of tolerance induction remains unclear, C57BL/10 (H2 b ) cardiac allografts were accepted in C3H/He (H2 k ) mice pretreated with IT inoculation of donor splenocytes (1 × 10 6 ) in combination with a depleting anti-CD4 monoclonal antibody 27 days before cardiac transplantation. To investigate which cell types were responsible for tolerance induction by IT injection of alloantigen, resting B (rB) cells or dendritic cells were used as the thymic inoculum instead of whole splenocytes. IT injection of rB cells induced indefinite graft prolongation in all recipients while only 20%of mice that had received IT injection of dendritic cells accepted grafts for over 100 days. In contrast, IT injection of dendritic cells resulted in significant deletion of donor-specific thymocytes whereas rB cells were relatively ineffective. IT deletion is not essential for the induction of tolerance by IT injection of rB cells; nondeletional mechanisms can be involved.

Although trachoma is a rare disease in most of the United States, it continues to be the major ophthalmological problem among Southwestern Indians. A new trachoma control program on the Navajo Indian Reservation is described.

Background Conventional calculation of mean 24-h ambulatory blood pressure (BP), SBP and DBP based on the average of all BP readings disregards the fact that a larger number of measurements is usually scheduled during the daytime than at night, an imbalance possibly leading to an overestimation of 24-h average BP. The aim of our study was to quantify this possible bias and to explore its determinants.Methods Four hundred and fifty untreated individuals were subdivided into three groups (150 individuals each) with three different ambulatory blood pressure measurement schedules for day/night: group I, four (day)/two (night) readings/h; group II, four (day)/three (night) readings/h; and group III, with BP readings every 30 min throughout 24 h. Hourly and 24-h averages were computed. The conventional 24-h averages of all SBP and DBP values were compared with the averages of hourly SBP and DBP mean values (time-weighted quantification). The difference between 24-h conventional and 24-h time-weighted BP was computed in each group and related to the degree of nocturnal BP dip and to the ratio between the number of readings of day and night.Result In the three groups, 24-h conventional and 24-h time-weighted BP values were highly correlated (r > 0.99), 24-h conventional SBP and DBP being significantly higher (P < 0.01) than the corresponding 24-h time-weighted values in groups I and II but not in group III (Bland-Altman analysis). The bias magnitude was related to the day/night ratio in number of readings and to nocturnal BP dip in groups I and II (P < 0.01) but not in group III.Conclusion The higher number of readings/h during daytime leads to an overestimation of conventional 24-h average BP, particularly in individuals with preserved nocturnal BP dipping. This can be avoided either by scheduling the same number of readings/h throughout 24 h or by performing a time-weighted quantification of 24-h BP. The clinical implications of these different approaches deserve further investigation. J Hypertens 28:459-464 (c) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.