Prevalence of myocardial bridges in the Mexican population: A morphometric and histological analysis.

Background: Myocardial bridge (MB) is described as an abnormal band of myocardium covering a variable portion of any coronary artery.

Methods: The current study explores the presence of MB throughout the coronary arterial system and provides a morphometric description through instrumented dissection of a sample of 100 human hearts. The study shows a higher prevalence of MB in the Mexican population than in previous reports.

Effect of a light-darkness cycle on the body weight gain of preterm infants admitted to the neonatal intensive care unit.

The Continuous bright light conditions to which premature infants are subjected while hospitalized in Neonatal Intensive Care Units (NICU) can have deleterious effects in terms of growth and development. This study evaluates the benefits of a light/darkness cycle (LDC) in weight and early hospital discharge from the NICU. Subjects were recruited from three participating institutions in Mexico.

Midazolam reduction with pre-operative melatonin in abdominal hysterectomy: double-blind randomized clinical trial.

Introduction: Midazolam is a benzodiazepine used for sedation, however, can cause respiratory depression and increases morbidity in patients. Melatonin is an effective alternative to manage anxiety in the perioperative period and could help to reduce the use of benzodiazepines during surgery. The aim of this clinical trial was to determine the efficacy of pre-operative sedation with a single-dose melatonin to reduce intraoperative use of midazolam in women under total abdominal hysterectomy (TAH).

Development of the circadian system and relevance of periodic signals for neonatal development.

Circadian rhythms are generated endogenously with a period of approximately 24h. Studies carried out during the last decade indicate that the circadian system develops before birth, and that the suprachiasmatic nucleus, a structure that is considered the mammalian circadian clock, is present in primates from the middle of pregnancy. Recent evidence shows that the infants' circadian system is sensitive to light from very early stages of development; it has also been proposed that low-intensity lighting can regulate the developing clock.

The pterional approach for the surgical resection of an orbital cholesteatoma: a case report.

Background: Cholesteatomas are benign tumors mainly composed of cholesterol crystals that rarely arise within the orbit. However, orbital cholesteatomas require a complete surgical resection due to their recidivating potential. Transcranial approaches offering a broad surgical exposure of the orbital cavity have been scarcely used for the management of these tumors.

A Complete and State of the Art Pre-mortem Diagnostic Approach to Creutzfeldt-Jakob Disease: A Case Report.

Sporadic Creutzfeldt-Jakob disease (sCJD) is a fatal and rapidly progressive form of dementia caused by the spread of a prion protein within the brain. Its real incidence is unknown since its definitive diagnosis requires histopathological analysis of brain specimens. However, novel tests that detect prion proteins in cerebrospinal fluid samples, such as the real-time quaking-induced conversion (RT-QuIC) technique, now allow the pre-mortem diagnosis of sCJD.

Chocolate for breakfast prevents circadian desynchrony in experimental models of jet-lag and shift-work.

Night-workers, transcontinental travelers and individuals that regularly shift their sleep timing, suffer from circadian desynchrony and are at risk to develop metabolic disease, cancer, and mood disorders, among others. Experimental and clinical studies provide evidence that food intake restricted to the normal activity phase is a potent synchronizer for the circadian system and can prevent the detrimental metabolic effects associated with circadian disruption. As an alternative, we hypothesized that a timed piece of chocolate scheduled to the onset of the activity phase may be sufficient stimulus to synchronize circadian rhythms under conditions of shift-work or jet-lag.

Scheduled meal accelerates entrainment to a 6-h phase advance by shifting central and peripheral oscillations in rats.

Travelling across several time zones requires a fast adjustment of the circadian system and the differential adjustment speeds of organs and systems results in what is commonly referred as jet lag. During this transitory state of circadian disruption, individuals feel discomfort, appetite loss, fatigue, disturbed sleep and deficient performance of multiple tasks. We have demonstrated that after a 6-h phase advance of the light-dark cycle (LD) scheduled food in phase with the new night onset can speed up re-entrainment.

Social jet-lag potentiates obesity and metabolic syndrome when combined with cafeteria diet in rats.

Background/objectives: Modern lifestyle promotes shifted sleep onset and shifted wake up time between weekdays and weekends, producing a condition termed "social-jet lag." Disrupted sleep promotes increased appetite for carbohydrate and fat-rich food, which in long term leads to overweight, obesity and metabolic syndrome. In order to mimic the human situation we produced an experimental model of social-jet lag (Sj-l).

Loss of melatonin daily rhythmicity is asociated with delirium development in hospitalized older adults.

Delirium is associated with circadian rhythm disruption. In this study we have explored whether circadian variation of melatonin is an indicator for delirium. Melatonin levels were determined from the first day of hospitalization and up to three days after the onset of delirium.

A light/dark cycle in the NICU accelerates body weight gain and shortens time to discharge in preterm infants.

Background: Bright constant light levels in the NICU may have negative effects on the growth and development of preterm infants

Objective: The aim of this study is to evaluate the benefits of an alternating light/dark cycle in the NICU on weight gain and early discharge from the therapy in premature infants.

Patients And Methods: A randomized interventional study was designed comparing infants in the NICU of Hospital Juarez de México, exposed from birth either to an LD environment (LD, n=19) or to the traditional continuous light (LL, n=19). The LD condition was achieved by placing individual removable helmets over the infant's heads.

Disruption of circadian rhythms due to chronic constant light leads to depressive and anxiety-like behaviors in the rat.

Depression is strongly associated with the circadian system, disruption of the circadian system leads to increased propensity to disease and to mood disorders including depression. The present study explored in rats the effects of circadian disruption by constant light on behavioral and hormonal indicators of a depressive-like condition and on the biological clock, the suprachiasmatic nucleus (SCN). Exposure to constant light for 8 weeks resulted in loss of circadian patterns of spontaneous general activity, melatonin and corticosterone.

Scheduled food hastens re-entrainment more than melatonin does after a 6-h phase advance of the light-dark cycle in rats.

Circadian desynchrony occurs when individuals are exposed to abrupt phase shifts of the light-dark cycle, as in jet lag. For reducing symptoms and for speeding up resynchronization, several strategies have been suggested, including scheduled exercise, exposure to bright light, drugs, and especially exogenous melatonin administration. Restricted feeding schedules have shown to be powerful entraining signals for metabolic and hormonal daily cycles, as well as for clock genes in tissues and organs of the periphery.

Scheduled meals and scheduled palatable snacks synchronize circadian rhythms: consequences for ingestive behavior.

Food is a potent time signal for the circadian system and has shown to entrain and override temporal signals transmitted by the biological clock, the suprachiasmatic nucleus, which adjusts mainly to the daily light/dark (LD) alternation. Organisms mostly ingest food in their active period and this permits a correct coordination between the LD and the food elicited time signals with the circadian system. Under conditions when feeding opportunities are shifted to the usual resting/sleep phase, the potent entraining force of food, shifts circadian fluctuations in several tissues, organs, and brain structures toward meal time, resulting a desynchrony within the body and between the organism and the external LD cycle.

Interaction between hypothalamic dorsomedial nucleus and the suprachiasmatic nucleus determines intensity of food anticipatory behavior.

Food anticipatory behavior (FAA) is induced by limiting access to food for a few hours daily. Animals anticipate this scheduled meal event even without the suprachiasmatic nucleus (SCN), the biological clock. Consequently, a food-entrained oscillator has been proposed to be responsible for meal time estimation.

Circadian disruption leads to loss of homeostasis and disease.

The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of "night work" using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease.

In a rat model of night work, activity during the normal resting phase produces desynchrony in the hypothalamus.

Internal synchrony among external cycles and internal oscillators allows adaptation of physiology to cyclic demands for homeostasis. Night work and shift work lead to a disrupted phase relationship between external time cues and internal rhythms, also losing internal coherence among oscillations. This process results in internal desynchrony (ID) in which behavioral, hormonal, and metabolic variables cycle out of phase.

Altered Fos immunoreactivity in the hypothalamus after glucose administration in pre- and post-weaning malnourished rats.

The present study explored the effects of malnutrition and nutritional rehabilitation on the response to glucose in hypothalamic nuclei involved in metabolic homeostasis. Male Wistar rats were malnourished during gestation-lactation (MGL) or at weaning to 55 days (MPW). Two groups of rats were rehabilitated with a balanced diet until 90 days (MGL-R and MPW-R, respectively).

Food intake during the normal activity phase prevents obesity and circadian desynchrony in a rat model of night work.

Shift work or night work is associated with hypertension, metabolic syndrome, cancer, and other diseases. The cause for these pathologies is proposed to be the dissociation between the temporal signals from the biological clock and the sleep/activity schedule of the night worker. We investigated the mechanisms promoting metabolic desynchrony in a model for night work in rats, based on daily 8-h activity schedules during the resting phase.

The suprachiasmatic nucleus participates in food entrainment: a lesion study.

Daily feeding schedules entrain temporal patterns of behavior, metabolism, neuronal activity and clock gene expression in several brain areas and periphery while the suprachiasmatic nucleus (SCN), the biological clock, remains coupled to the light/dark cycle. Because bilateral lesions of the SCN do not abolish food entrained behavioral and hormonal rhythms it is suggested that food entrained and light entrained systems are independent of each other. Special circumstances indicate a possible interaction between the light and the food entrained systems and indicate modulation of SCN activity by restricted feeding.

Peripheral oscillators: the driving force for food-anticipatory activity.

Food-anticipatory activity (FAA) and especially the food-entrained oscillator (FEO) have driven many scientists to seek their mechanisms and locations. Starting our research on FAA we, possibly like many other scientists, were convinced that clock genes held the key to the location and the underlying mechanisms for FAA. In this review, which is aimed especially at discussing the contribution of the peripheral oscillators, we have put together the accumulating evidence that the clock gene machinery as we know it today is not sufficient to explain food entrainment.

Differential effects of a restricted feeding schedule on clock-gene expression in the hypothalamus of the rat.

Restricted feeding schedules (RFS) entrain digestive, hormonal, and metabolic functions as well as oscillations of clock genes, such as Per1 and Per2, in peripheral organs. In the brain, in particular the hypothalamus, RFS induce and shift daily rhythms of Per1 and Per2 expression. To determine whether RFS affect clock genes in extra-SCN oscillators in a uniform manner, the present study investigated daily rhythms of Per1, Per2, and Bmal1 expression in various hypothalamic regions.

Expectancy for food or expectancy for chocolate reveals timing systems for metabolism and reward.

The clock gene protein Per 1 (PER1) is expressed in several brain structures and oscillates associated with the suprachiasmatic nucleus (SCN). Restricted feeding schedules (RFS) induce anticipatory activity and impose daily oscillations of c-Fos and clock proteins in brain structures. Daily access to a palatable treat (chocolate) also elicits anticipatory activity and induces c-Fos expression mainly in corticolimbic structures.

Internal desynchronization in a model of night-work by forced activity in rats.

Individuals engaged in shift- or night-work show disturbed diurnal rhythms, out of phase with temporal signals associated to the light/dark (LD) cycle, resulting in internal desynchronization. The mechanisms underlying internal desynchrony have been mainly investigated in experimental animals with protocols that induce phase shifts of the LD cycle and thus modify the activity of the suprachiasmatic nucleus (SCN). In this study we developed an animal model of night-work in which the light-day cycle remained stable and rats were required to be active in a rotating wheel for 8 h daily during their sleeping phase (W-SP).