Olfactory neurogenesis and its role in fear memory modulation

Olfaction is a critical sense that allows animals to navigate and understand their environment. In mammals, the critical brain structure to receive and process olfactory information is the olfactory bulb, a structure characterized by a laminated pattern with different types of neurons, some of which project to distant telencephalic structures, like the piriform cortex, the amygdala, and the hippocampal formation. Therefore, the olfactory bulb is the first structure of a complex cognitive network that relates olfaction to different types of memory, including episodic memories. The olfactory bulb continuously adds inhibitory newborn neurons throughout life; these cells locate both in the granule and glomerular layers and integrate into the olfactory circuits, inhibiting projection neurons. However, the roles of these cells modulating olfactory memories are unclear, particularly their role in fear memories. We consider that olfactory neurogenesis might modulate olfactory fear memories by a plastic process occurring in the olfactory bulb.

Rhabdomyolysis following Nuss Procedure: A Prospective Study in Children

INTRODUCTION

 Postoperative rhabdomyolysis (RML) has been documented after several surgical procedures in adults. Musculoskeletal remodeling after Nuss procedure for pectus excavatum (PE) could cause RML. We evaluated the incidence of RML after Nuss procedure in children.

METHODS

 This study was a prospective study from 2018 to 2021. We enrolled all otherwise healthy patients who underwent PE correction with only one bar. Studied variables included demographic and clinical data, duration of surgery, complications, and length of hospitalization. The patients included underwent serial measurements of serum creatine kinase (CK), troponin I, N terminal pro B-type natriuretic peptide (NT-proBNP), serum creatinine, urea, and glomerular filtration rate at 6 and 48 hours postoperatively, and hospital discharge.

RESULTS

 Forty-six patients met criteria (40 males/6 females), with a mean age of 15.1 ± 1.4 years. Mean duration of surgery was 74 ± 28 minutes, and length of hospitalization was 4.6 ± 1.6 days. RML was diagnosed in 30.4% of patients at 6 hours, 91.3% at 48 hours, and 21.7% at hospital discharge. Mean preoperative CK value was 181.1 ± 141.6 IU/L, and postoperative values were 863.3 ± 302.6 IU/L at 6 hours, 1,675.2 ± 561 IU/L at 48 hours, and 850 ± 683.7 IU/L at hospital discharge, with statistically significant differences (p = 0.001). High-sensitivity troponin I and NT-proBNP levels increased significantly during the postoperative time (p = 0.001). Renal function remained stable (p = 0.55).

CONCLUSION

 Nuss technique produces RML without kidney injury in healthy patients. This knowledge should be considered for patients at increased risk of developing acute kidney injury and other complications.

Maternal enrichment increases infantile spatial amnesia mediated by postnatal neurogenesis modulation

Infantile amnesia, the inability to form long-lasting episodic memories, is a phenomenon extensively known but with no clear understanding of its origins. However, a recent study showed that high rates of hippocampal postnatal neurogenesis degrade episodic-like memories in infants a few days after memory acquisition. Additionally, new studies indicate that exposure to an enriched environment in mice leads to high hippocampal neurogenesis in their offspring. Nevertheless, it is still unclear how this intergenerational trait affects the persistence of hippocampal memories. Therefore, we evaluated spatial memory retention in the offspring of enriched female mice after weaning to address this question. Ten days after spatial learning, we tested memory retention, observing that the offspring of enriched dams increased spatial memory failure; this finding correlates with high proliferation rates in the hippocampus. Furthermore, we evaluated the causal relationship between postnatal hippocampal neurogenesis and memory failure using the antiproliferative drug Temozolomide (TMZ), which rescued spatial memory retrieval. Finally, we evaluated neuronal activity in the hippocampus quantifying the cells expressing the immediate early gene c-Fos. This evaluation showed engram modifications between groups. This neural activity pattern indicates that the high neurogenesis rates can modify memory engrams and cognitive performance. In conclusion, the inherited increase of hippocampal neurogenesis by enriched dams leads to plastic changes that exacerbate infantile amnesia in a spatial task.

Perinatal exposure to nicotine disrupts circadian locomotor and learning efficiency rhythms in juvenile mice

The increased rates of nicotine exposure by electronic nicotine delivery systems (vaping), ingestion, or patches during pregnancy as an alternative to the smoking of tobacco arise concerns about the neurodevelopmental, cognitive, and behavioral long-term consequences in the juvenile offspring. Nowadays, the use of electronic cigarettes as supposed a safer smoking alternative has been increased mainly in young females at reproductive age, due to the "safety" misconception. However, previous studies suggest that exposure to nicotine during pregnancy and prenatal development may lead to detrimental effects in the postnatal lifespan. Nicotine, as an alkaloid, alters the reward system acting as acetylcholine (ACh) agonist on nicotinic cholinergic receptors (nAChRs). In early brain development, the cholinergic system is also involved in neurite outgrowth, cell survival, proliferation, differentiation, neurogenesis, and many other critical processes being considered as a developmental signal marker. The nicotine noxious effect at those early stages may impact the system programming and plasticity in the long-term postnatal life. In this study, we analyze the circadian locomotor activity and learning efficiency rhythms in the juvenile male offspring of mice exposed to nicotine through pregnancy and lactation. Attenuated rhythm amplitude and relative power of the circadian component were found in the nicotine exposed offspring (pN). The acrophase (the best performance during a 24-h cycle) of learning efficiency was delayed and the long-term memory consolidation task failed after 8 days of learning experience. The aforementioned results suggest nicotine exposure in uterus modifies the circadian modulation related to the memory consolidation and locomotor systems as well as its environmental temporal synchronization.

Ketogenic Diet Provided During Three Months Increases KCC2 Expression but Not NKCC1 in the Rat Dentate Gyrus

Ketogenic diet, a high fat and low carbohydrate diet, has been used as a non-pharmacological treatment in refractory epilepsy since 1920. In recent years, it has demonstrated to be effective in the treatment of numerous neurological and non-neurological diseases. Some neurological and neuropsychiatric disorders are known to be caused by gamma-aminobutyric acid (GABA)-mediated neurotransmission dysfunction. The strength and polarity of GABA-mediated neurotransmission are determined by the intracellular chloride concentration, which in turn is regulated by cation-chloride cotransporters NKCC1 and KCC2. Currently, it is unknown if the effect of ketogenic diet is due to the modulation of these cotransporters. Thus, we analyzed the effect of a ketogenic diet on the cation-chloride cotransporters expression in the dentate gyrus. We estimated the total number of NKCC1 immunoreactive (NKCC1-IR) neuronal and glial cells by stereology and determined KCC2 labeling intensity by densitometry in the molecular and granule layers as well as in the hilus of dentate gyrus of rats fed with normal or ketogenic diet for 3 months. The results indicated that ketogenic diet provided during 3 months increased KCC2 expression, but not NKCC1 in the dentate gyrus of the rat. The significant increase of KCC2 expression could explain, at least in part, the beneficial effect of ketogenic diet in the diseases where the GABAergic system is altered by increasing its inhibitory efficiency.

Artificial reproduction of magnetic fields produced by a natural geomagnetic storm increases systolic blood pressure in rats

The incidence of geomagnetic storms may be associated with changes in circulatory physiology. The way in which the natural variations of the geomagnetic field due to solar activity affects the blood pressure are poorly understood and require further study in controlled experimental designs in animal models. In the present study, we tested whether the systolic arterial pressure (AP) in adult rats is affected by simulated magnetic fields resembling the natural changes of a geomagnetic storm. We exposed adult rats to a linear magnetic profile that simulates the average changes associated to some well-known geomagnetic storm phases: the sudden commencement and principal phase. Magnetic stimulus was provided by a coil inductor and regulated by a microcontroller. The experiments were conducted in the electromagnetically isolated environment of a semi-anechoic chamber. After exposure, AP was determined with a non-invasive method through the pulse on the rat's tail. Animals were used as their own control. Our results indicate that there was no statistically significant effect in AP when the artificial profile was applied, neither in the sudden commencement nor in the principal phases. However, during the experimental period, a natural geomagnetic storm occurred, and we did observe statistically significant AP increase during the sudden commencement phase. Furthermore, when this storm phase was artificially replicated with a non-linear profile, we noticed a 7 to 9 % increase of the rats' AP in relation to a reference value. We suggested that the changes in the geomagnetic field associated with a geomagnetic storm in its first day could produce a measurable and reproducible physiological response in AP.

Prenatal protein malnutrition induces a phase shift advance of the spontaneous locomotor rhythm and alters the rest/activity ratio in adult rats

Evidence is accumulating for significant structural and functional changes within the central nervous system (CNS) following prenatal protein malnutrition. Included among the structures that are likely to be affected are the suprachiasmatic nuclei (SCN) involved in the regulation of locomotor activity, sleep-wake cycle, and drinking behavior. To determine the effects of prenatal protein malnutrition on the spontaneous activity rhythm, 24 h radiotelemetric measurements were recorded over an 8-day period. Male offspring of rats provided with protein-deficient (6% casein) or adequate (25% casein) diets for 5 weeks prior to mating and throughout pregnancy were studied. Well nourished rats displayed a rise in activity level during the first hour of the 12h light phase, whereas prenatally malnourished rats displayed this increase during the 12h dark phase, approximately 50 min before lights on, reflecting a significant phase advance in this group. In addition, cosinor analysis revealed that the alpha/rho relationship was affected in the previously malnourished group, the activity phase being shorter than in the well-nourished animals. These findings suggest changes in the regulatory systems controlling the locomotor activity rhythm as a consequence of prenatal protein malnutrition. Alterations in entrainment to the light-dark cycle, and/or in the coupling force of the circadian oscillators are all candidate mechanisms.

[Thoracic epidural analgesia vs patient-controlled analgesia with intravenous fentanyl in children treated for pectus excavatum with the Nuss procedure]

BACKGROUND AND OBJECTIVE

Thoracic epidural analgesia and patient-controlled analgesia (PCA) with intravenous fentanyl have both been shown to be effective in pediatric patients treated surgically for pectus excavatum using the Nuss procedure. We compare the efficacy and safety of these techniques.

METHODS

Retrospective study of pediatric cases in which the Nuss procedure was used to treat pectus excavatum between October 1997 and February 2009. Weight, age, sex, and Haller index were analyzed. Pain was assessed every 8 hours on a visual analog scale of 0 to 10 or on a scale based on observation of distress (LLANTO scale). Daily use of analgesics was also recorded. The incidence of catheter-related complications or adverse events of treatment such as nausea, vomiting, and respiratory depression were also noted.

RESULTS

We identified 31 patients in 2 groups: the epidural group (n=22) and the PCA group (n=9). Demographic characteristics, the incidences of complications or adverse events, and mean (SD) pain scores (epidural group, 1.8 [3.8]; PCA group, 2.1 [3.4]; P = .775) were statistically similar in the 2 groups. However, analgesic requirements and the duration of analgesic use in days differed significantly, at 2.9 (1.1) days in the epidural group and 5.9 (1.4) days in the PCA group (P =.001).

CONCLUSIONS

The efficacy and safety of thoracic epidural analgesia is similar to that of PCA with intravenous fentanyl, although the use of epidural analgesia is associated with a markedly shorter duration of requirement for postoperative analgesia.

Prenatal malnutrition and sleep states in adult rats: effects of restraint stress

Independently, prenatal malnutrition and psychological/physical stress have been shown to affect sleep architecture in adult rats. As malnutrition and stress commonly co-exist in malnourished human populations, the objective of the present study was to ascertain the combined effects of these two insults by examining sleep-wake parameters following a brief restraint stress in prenatally protein malnourished rats. The male offspring of rats provided with a protein deficient diet (6% casein) for 5 weeks prior to mating and throughout pregnancy were implanted with recording electrodes beginning at postnatal day 90. Polygraph recordings were obtained to quantify sleep states during the first 4 h of the dark phase of the cycle on 2 consecutive days. The first followed a 24-h habituation session to the recording chamber (baseline). The second occurred at the same time of day but followed 20 min of restraint stress in a Plexiglas tube. During baseline, prenatally malnourished rats spent more time in rapid eye movement sleep (REMS) in the first 2 h after "lights off" (block 1), and greater amounts of wakefulness (W) with a corresponding reduction in slow wave sleep (SWS) in the second two hours (block 2), as compared with controls. Following stress, the sleep architecture of both groups of rats remained unaltered in block 1 relative to their baseline day. In block 2, both groups exhibited significant reductions in SWS and REMS with significantly greater reductions being expressed in the prenatally malnourished group (most dramatically, REMS was completely eliminated). These findings suggest that sleep disturbances may be more severe in those malnourished human populations subjected to acutely stressful experiences.

Anesthetic management of a patient with MERRF syndrome

There are several specific considerations regarding anesthesia in patients with mitochondrial disease. We describe the successful administration of a combined general and epidural anesthesia with sevoflurane maintenance in a patient with myoclonic epilepsy with ragged red fibers (MERRF syndrome) scheduled for surgical treatment of bilateral clubfoot.

Pre- and post-natal protein malnutrition alters the effect of rapid eye movements sleep-deprivation by the platform-technique upon the electrocorticogram of the circadian sleep-wake cycle and its frequency bands in the rat

Selective deprivation of paradoxical (or rapid eye movements) sleep (REMS) in protein malnourished young male rats, results in circadian and homeostatic alterations. By means of electrocorticographic recordings, we have examined the sleep-wake cycle as a functional maturity index, and its circadian and homeostatic mechanisms in prenatal (PM) and chronically (CM) protein malnourished young male rats. The effects of rapid eye movements sleep-deprivation (REMS-D), by the platform technique in a "conflict experiment" (i.e. recovery from REMS-D begun during the circadian phase of activity), revealed that in PM animals, wake (WAK) was increased significantly during recovery days 1 and 2 (RD1, RD2); and slow wave sleep (SWS) was reduced significantly during these days. Prenatal protein-malnutrition altered the phase of WAK and REMS rhythms, and the amplitude of SWS rhythm was decreased. The REMS compensatory increase after REMS-D (REMS rebound) was confined to the first 4-h block of the activity phase in all experimental groups and 24 h later another REMS rebound was displayed in PM animals. The paradoxical sleep-rebound in CM animals was significantly higher than control and PM rats and it was only shown at the first 4-h block after REMS-D. Before and after REMS-D the circadian distribution of both sleep states, and the electrocortical frequency bands showed different circadian phases at the same day-time in control, PM and CM rats. The aforementioned indicates that protein malnutrition exerts important effects on the circadian and homeostatic mechanisms driving sleep. Therefore, the temporal structure of the malnourished rats may not allow proper synchronization of some sleep parameters, particularly REMS, to the environmental time cues.

[Pulmonary artery primary sarcoma: diagnosis with transthoracic and transesophageal echocardiogram]

Pulmonary artery sarcoma is a rare malignant disease and diagnosis before surgery or autopsy is difficult. We present a case of a pulmonary artery sarcoma diagnosed with transtoracic and transesophagic echocardiogram which was treated surgically.

Determination of the Atmospheric-Water-Vapor Content in the 940-nm Absorption Band by Use of Moderate Spectral-Resolution Measurements of Direct Solar Irradiance

We have analyzed three methods that can be used to determine the integrated water vapor of the atmosphere in the 940-nm band by means of modeled and measured direct solar spectral irradiance. The experimental irradiance data were obtained with a commercial LI-COR 1800 spectroradiometer, based on a monochromator system, of high to moderate spectral resolution (6 nm) in the 300-1100-nm range. The modeled data are based on monochromatic approaches to determine atmospheric transmittance constituents; for those of water vapor we used the lowtran7 model. The first method is a curve-fitting procedure that makes use of the entire shape band absorption information to retrieve a unique water-vapor value. The second method makes use of the monochromatic approach of the absorption transmittance formula to determine the amount of water vapor at each wavelength of the absorption band, and the third method is the classic differential absorption technique suitably applied to our data. Spectral analysis showed the advantages and disadvantages of each method, such as problems linked to the various spectral resolutions of the experimental and the modeled data, the width of the spectral range used to define the water-vapor absorption band, and the dependence of the retrieval on the choice of the two selected wavelengths in the last-named technique. All these problems were considered so they could be avoided or minimized and the associated errors estimated. We used the methods to determine water-vapor values for the period from March to November 1995 at a rural station in Vallodolid, Spain, allowing for the evaluation of the differences in real monitoring conditions. Finally, the contribution of continuum absorption was also evaluated, yielding lower water-vapor values between 13 and 30%. These differences were considerably greater than those that were due to the problems that we have just enumerated.

Preventing iron deficiency in infants and preschool children in Argentina

This paper summarizes the results of most major studies of iron deficiency and anemia in infants and children in Argentina. Possible reasons for high prevalences of iron deficiency and anemia in certain population groups are given, and plans for future interventions, based on these data, are discussed.

Effects of acute prenatal ethanol exposure on Bergmann glia cells early postnatal development

The effects of acute ethanol exposure during the prenatal phase of Bergmann glia cell (Bgc) generation were evaluated in three postnatal days. Ethanol exposed rats showed Bgc with reduced soma size, decreased number and width of their fibers, and increased fiber length, when compared with control animals. These differences, however, were significant at postnatal day 12. Our results demonstrate that acute, prenatal exposure to ethanol during critical stages of brain development disrupts Bgc early postnatal development.

Effects of prenatal protein malnutrition on mossy fibers of the hippocampal formation in rats of four age groups

The present study was undertaken to investigate the effect of prenatal protein deprivation on the postnatal development of the mossy fiber plexus of the hippocampal formation on postnatal (P) days 15, 30, 90, and 220. Although there is extensive information about the effects of malnutrition on cell body and dendrite morphology, little attention has been paid to axons or axon plexuses. The mossy fiber plexus represents the dentate gyrus granule cell axonal projection to areas CA4 and CA3 of the hippocampal formation and is readily demonstrated with Timm's heavy metal stain. With the use of this stain, the plexus was measured at 13 levels throughout the hippocampal complex. There was no effect of the diet on the anatomical distribution of the plexus. The current study, however, does show significant effects of prenatal protein malnutrition on postnatal development of the mossy fiber plexus that are age dependent. The prenatally malnourished rats show significant deficits in the total rostro-caudal extent and volume of the plexus on P15, P90, and P220, with the most marked dietary effect on P220. There was no significant diet effect on P30 in either extent or volume.

Effects of prenatal protein malnutrition on hippocampal CA1 pyramidal cells in rats of four age groups

The present study was undertaken to investigate the effect of prenatal protein deprivation on area CA1 hippocampal pyramidal cells on postnatal (P) days 15, 30, 90 and 220 using Golgi techniques. Age related changes in both groups and diet related changes between groups were assessed. There were significant diet effects at all four ages, with one of 12 different measurements showing a significant diet effect on P15, five on P30, one on P90, and seven on P220. The most marked effect of the diet was on pyramidal cell dendrite spine density in the stratum moleculare and stratum radiatum, with a different pattern of diet effects in the two strata. In pyramidal cell dendrites in the stratum moleculare, there was a deficit in spine density that was significant at three of the four ages and there were similar age-related changes in the two diet groups. Spines on pyramidal cell dendrites in the stratum radiatum showed a lack of synchrony of age-related changes in the two diet groups, with an increased spine density in the malnourished rats on P30 and a widening deficit in this parameter on P90 and P220. The bimodal distribution to these changes, with most marked deficits occurring on P30 and P220, with an intervening period of apparent "catch-up" on P90, is of interest and may be a significant brain adaptation to malnutrition. The present study is the final of three morphometric studies on the effect of prenatal protein restriction on three key neurons in the hippocampal trisynaptic circuit. When compared to our previous studies on the dentate granule cell and the CA3 pyramidal cell, it is noted that there is an effect of the low protein diet on all these neurons, with the most marked effect on the predominantly postnatally generated dentate granule cells.

[Intravenous streptokinase in acute myocardial infarction. A Mexican multicentric study]

To evaluate the benefits of intravenous streptokinase (SQIV) in acute myocardial infarction (AMI), we joined a group of ten Mexican university hospitals, that were coordinated by the National Institute of Cardiology of Mexico. We included patients less than 70 years of age admitted to the hospital with less than 6 hours from the onset of chest pain during their first myocardial infarction. All patients had ST segment elevation of 1.5 mm or more, and none had contraindication for SQIV. They received 1.5 millions of SQIV in one hour. Reperfusion criteria included absence of pain, ST segment reduction and a rapid rise and fall of enzyme levels. Angiographic criterion for reperfusion was the permeability of the affected coronary vessel. Of 66 patients studied, 57 (86%) had clinical reperfusion; of the 24 available angiographic studies, 92% demonstrated reperfusion. Eight (12%) of the patients had minor complications and 7 (10%) had serious complications. There were 0 deaths. We concluded that SQIV is a useful therapeutic procedure, easy to perform in general hospitals.

[Importance of the tissue polypeptide antigen level in neoplastic patients. Its correlation with other tumor markers]

In order to know the behavior of the tissue polypeptide antigen (TPA) as a tumor marker, the authors determine its amount in serum by means of radioimmunoassay (TPA Prolifigen RIA) in 441 patients having respiratory, digestive, urogenital, hematopoietic, mammary and other malignant tumors. The obtained results indicate that: TPA has no tumor specificity; however it increases in tumors without any other known tumor marker. TPA has no diagnostic value, but it is useful for the following up of digestive, mammary, respiratory, ovarian and testicular cancer; amounts of TPA comprised between 90 and 120 U/l are not specific and have no clinical significance; and it is very useful the simultaneous determination of CEA and TPA in the respiratory, digestive and mammary malignant neoplasms to help the clinical data in the evaluation of tumor mass (CEA) and tumor activity (TPA) without indication of tumor localization.