An Inescapable Cat Odor Exposure Protocol for Studying Innate and Contextual Threat Conditioning in Rats.

Animals respond to threatening situations by exhibiting a number of defensive behaviors, including avoidance, freezing, and risk assessment. An animal model with an ethological approach offers a deeper insight into the biological mechanisms underlying threat responses. This paper describes a methodology to measure defensive behaviors toward both innate and learned aversive stimuli in rats. Animals were individually exposed to predator odor in an inescapable chamber to elicit a measurable, sustained, defensive state. The experimental design involved placing a rat in a familiar chamber for 10 min followed by exposure to cat odor for another 10 min in the same context. The next day, the rats were re-exposed for 10 min to the same context chamber where cat odor exposure occurred. Sessions were video-recorded and defensive behaviors were assessed on both days. The behavioral test was coupled with reversible functional inactivation and c-Fos immunohistochemistry techniques to determine the role of the interoceptive cortex in threat responses. Rats exposed to cat odor on the first day and re-exposed to the context chamber on the second day displayed higher levels of defensive behaviors, and that cat odor elicited a robust increase in the neural activity of the interoceptive cortex. Moreover, muscimol inactivation of the interoceptive cortex reduced the expression of defensive behaviors in response to cat odor and impaired contextual threat memory. These results show that this behavioral assay is a useful tool for studying neural mechanisms of defensive behaviors and may offer insight into mechanisms that mediate fear in humans and its related disorders.

Dorsal CA1 hippocampal place cells form a multi-scale representation of megaspace.

Spatially firing "place cells" within the hippocampal CA1 region form internal maps of the environment necessary for navigation and memory. In rodents, these neurons have been almost exclusively studied in small environments (<4 m2). It remains unclear how place cells encode a very large open 2D environment that is commensurate with the natural environments experienced by rodents and other mammals. Such an ethologically realistic environment would require a complex spatial representation, capable of simultaneously representing space at multiple overlapping fine-to-coarse informational scales. Here, we show that in a "megaspace" (18.6 m2), the majority of dorsal CA1 place cells exhibited multiple place subfields of different sizes, akin to those observed along the septo-temporal axis. Furthermore, the total area covered by the subfields of each cell was not correlated with the number of subfields, and increased with the scale of the environment. The multiple different-sized subfields exhibited by place cells in the megaspace suggest that the ensemble population of subfields form a multi-scale representation of space within the dorsal hippocampus. Our findings point to a new dorsal hippocampus ensemble coding scheme that simultaneously supports navigational processes at both fine- and coarse-grained resolutions. VIDEO ABSTRACT.

Growth, carcass characteristics, cut yields and meat quality of lambs finished with zilpaterol hydrochloride and steroid implant.

Forty hairbreed male lambs were used to evaluate the effects of zilpaterol hydrochloride (ZH, 0 and 0.15 mg/kg BW) and steroid implant (SI, without and with 52.5 mg trenbolone acetate and 7.5 mg 17ß-estradiol) on feedlot performance, carcass characteristics, non-carcass components, wholesale cut yield, and meat quality. Supplemental ZH increased growth rate, feed efficiency, carcass weight, and dressing percentage, with no effect on wholesale cut yields. Feeding ZH increased muscle pH at 24 h. Supplemental ZH increased meat shear force, but decreased lightness, redness, and yellowness after frozen storage followed by a 14-day aging period. The SI administration increased dressing percentage and neck yield, but decreased testicle weight and meat redness, without affecting other variables. The LT area was greater with ZH + SI administration than with individual application of ZH or SI. Compared to individual administration, simultaneous application of ZH and SI did not result in improved growth performance, carcass traits and wholesale cut yields in hairbreed male lambs.

Interoceptive Insular Cortex Mediates Both Innate Fear and Contextual Threat Conditioning to Predator Odor.

The insular cortex (IC), among other brain regions, becomes active when humans experience fear or anxiety. However, few experimental studies in rats have implicated the IC in threat responses. We have recently reported that inactivation of the primary interoceptive cortex (pIC) during pre-training, or the intra-pIC blockade of protein synthesis immediately after training, impaired the consolidation of auditory fear conditioning. The present study was designed to investigate the role of the pIC in innate and learned defensive responses to predator odor. Freezing behavior was elicited by single or repetitive exposures to a collar that had been worn by a domestic cat. Sessions were video-recorded and later scored by video observation. We found that muscimol inactivation of the pIC reduced the expression of freezing reaction in response to a single or repeated exposure to cat odor. We also found that pIC inactivation with muscimol impaired conditioning of fear to the context in which rats were exposed to cat odor. Furthermore, neosaxitoxin inactivation of the pIC resulted in a prolonged and robust reduction in freezing response in subsequent re-exposures to cat odor. In addition, freezing behavior significantly correlated with the neural activity of the IC. The present results suggest that the IC is involved in the expression of both innate and learned fear responses to predator odor.

The ventral hippocampus is involved in multi-goal obstacle-rich spatial navigation.

A large body of evidence shows that the hippocampus is necessary for successful spatial navigation. Various studies have shown anatomical and functional differences between the dorsal (DHC) and ventral (VHC) portions of this structure. The DHC is primarily involved in spatial navigation and contains cells with small place fields. The VHC is primarily involved in context and emotional encoding contains cells with large place fields and receives major projections from the medial prefrontal cortex. In the past, spatial navigation experiments have used relatively simple tasks that may not have required a strong coordination along the dorsoventral hippocampal axis. In this study, we tested the hypothesis that the DHC and VHC may be critical for goal-directed navigation in obstacle-rich environments. We used a learning task in which animals memorize the location of a set of rewarded feeders, and recall these locations in the presence of small or large obstacles. We report that bilateral DHC or VHC inactivation impaired spatial navigation in both large and small obstacle conditions. Importantly, this impairment did not result from a deficit in the spatial memory for the set of feeders (i.e., recognition of the goal locations) because DHC or VHC inactivation did not affect recall performance when there was no obstacle on the maze. We also show that the behavioral performance of the animals was correlated with several measures of maze complexity and that these correlations were significantly affected by inactivation only in the large object condition. These results suggest that as the complexity of the environment increases, both DHC and VHC are required for spatial navigation.

Body composition evaluated by body mass index and bioelectrical impedance vector analysis in women with rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is a complex inflammatory disease that modifies body composition. Although body mass index (BMI) is one of the clinical nutrition tools widely used to assess indirectly nutritional status, it is not able to identify these body alterations. Bioelectrical Vector Analysis (BIVA) is an alternative method to assess hydration and body cell mass of patients with wasting conditions. OBJECTIVE: To investigate the differences in nutrition status according to BMI groups (normal, overweight and obesity) and BIVA classification (cachectic and non-cachectic) in women with RA. METHODS: Women with confirmed diagnosis of RA were included from January 2015 to June 2016. Whole-body bioelectrical impedance was measured using a tetrapolar and mono-frequency equipment. Patients were classified according to BMI as: low body weight (n = 6, 2.7%), normal (n = 59, 26.3%), overweight (n = 88, 39.3%) and obese (n = 71, 31.7%), and each group was divided into BIVA groups (cachectic 51.8% and non-cachectic 48.2%). RESULTS: A total of 224 RA patients were included, with mean age 52.7 years and median disease duration of 12 years. Significant differences were found in weight, arm circumference, waist, hip, resistance/height, reactance/height and erythrocyte sedimentation rate among all BMI groups. However, serum albumin levels were significantly different between cachectic and non-cachectic patients independently of BMI. In all BMI categories, cachectic groups had lower reactance and phase angle than non-cachectic subjects. CONCLUSION: RA patients with normal or even high BMI have a significantly lower muscle component. Evaluation of body composition with BIVA in RA patients could be an option for cachexia detection.

Factors associated to inpatient mortality rates in type-2-diabetic patients: a cross-sectional analytical study in three Peruvian hospitals. / Factores asociados a mortalidad intrahospitalaria en pacientes con diabetes mellitus tipo 2: estudio transversal analítico en tres hospitales peruanos.

INTRODUCTION: Diabetes mortality has increased in recent years. In Peru, there are few studies on in-hospital mortality due to type 2 diabetes in the provinces. OBJECTIVE: To determine factors associated to hospital mortality in patients with diabetes mellitus type 2 in three hospitals from Cusco-Peru. METHODS: An analytical cross-sectional study was performed. All patients with diabetes mellitus type 2 hospitalized in the city of Cusco during the 2016 were included. Socio-educational and clinical characteristics were evaluated, with "death" as the variable of interest. The crude (cPR) and adjusted (aPR) prevalence ratios were estimated using generalized linear models with Poisson family and log link function, with their respective 95% confidence intervals (95% CI). The values p <0.05 were considered significant. RESULTS: A total of 153 patients were studied; 33.3% (51) died in the hospital. The mortality rate increased when the following factors were associated: age of the patients increased the mortality rate by one-year increments (aPR: 1.02; CI95%: 1.01-1.03; p<0.001); to have been admitted by the emergency service (aPR: 1.93; CI95%: 1.34-2.77; p<0.001); being a patient who is readmitted to the hospital (aPR: 2.01; CI95%: 1.36-2.98; p<0.001); and patients who have had a metabolic in-hospital complication (aPR: 1.61; CI95%: 1.07-2.43; p=0.024) or renal in-hospital complications (aPR: 1.47; CI95%: 1.30-1.67; p<0.001). Conversely, the mortality rate was reduced when admission was due to a urinary tract infection (aPR: 0.50; CI95%: 0.35-0.72; p<0.001); adjusted by seven variables. CONCLUSIONS: A third of hospitalized diabetes mellitus type 2 patients died during the study period. Mortality was increased as age rises, patients admitted through emergency rooms, patients who were readmitted to the hospital, and patients who had metabolic or renal complications. Patients admitted for a urinary tract infection had a lower mortality rate.

INTRODUCCIÓN: La mortalidad por diabetes se ha incrementado en los últimos años. En Perú, existen escasos estudios acerca de la mortalidad intrahospitalaria por diabetes en provincias. OBJETIVOS: Determinar los factores asociados a mortalidad intrahospitalaria en pacientes con diabetes mellitus tipo 2 en tres hospitales de la sierra sur del Perú. MÉTODOS: Se realizó un estudio de corte transversal analítico. Se incluyó a todos los pacientes con diabetes mellitus tipo 2 hospitalizados en la ciudad del Cusco durante el año 2016. Se evaluó las características socioeducativas y clínicas, teniendo a la “defunción” como variable de interés. Se calculó las razones de prevalencias crudas y ajustadas, mediante los modelos lineales generalizados, con familia Poisson y función de enlace log, con sus respectivos intervalos de confianza al 95%. Se consideró significativos los valores p < 0,05. RESULTADOS: De los 153 pacientes, el 33,3% (51) murió en la hospitalización. Incrementó la frecuencia de mortalidad: por cada año de edad del paciente (razón de prevalencias ajustada 1,02; intervalo de confianza 95%: 1,01 a 1,03; valor p < 0,001), por haber ingresado por el servicio de emergencia (razón de prevalencias ajustada 1,93; intervalo de confianza 95%: 1,34 a 2,77; valor p < 0,001), por ser un paciente que reingresa al hospital (razón de prevalencias ajustada 2,01; intervalo de confianza 95%: 1,36 a 2,98; valor p < 0,001) y por haber tenido una complicación hospitalaria metabólica (razón de prevalencias ajustada 1,61; intervalo de confianza 95%: 1,07 a 2,43; valor p = 0,024) o renal (razón de prevalencias ajustada 1,47; intervalo de confianza 95%: 1,30 a 1,67; valor p < 0,001). En cambio, disminuyó la frecuencia mortalidad el que su causa de hospitalización haya sido por una infección del tracto urinario (razón de prevalencia ajustada 0,50; intervalo de confianza 95%: 0,35 a 0,72; valor p < 0,001); ajustado por siete variables. CONCLUSIONES: La edad, el ingresar por emergencia y el presentar reingresos a la hospitalización fueron factores asociados a mortalidad; así como el presentar complicaciones intrahospitalarias de tipo metabólica o renal.

Plasticity in the Interoceptive System.

The most outstanding manifestations of the plastic capacities of brain circuits and their neuronal and synaptic components in the adult CNS are learning and memory. A reduced number of basic plastic mechanisms underlie learning capacities at many levels and regions of the brain. The interoceptive system is no exception, and some of the most studied behavioral changes that involve learning and memory engage the interoceptive pathways at many levels of their anatomical and functional organization.In this chapter, we will review four examples of learning, mostly in rats, where the interoceptive system has a role. In the case of conditioned taste aversion, the interoceptive system is of outstanding importance. In drug addiction, the role of the insular cortex - the highest level of the interoceptive system- is unusual and complex, as many forebrain regions are engaged by the process of addiction. In the third example, neophobia, the gustatory region of the insular cortex plays a major role. Finally, the role of different areas of the insular cortex in different processes of aversive memory, particularly fear conditioning, will be reviewed.

Forest understory trees can be segmented accurately within sufficiently dense airborne laser scanning point clouds.

Airborne laser scanning (LiDAR) point clouds over large forested areas can be processed to segment individual trees and subsequently extract tree-level information. Existing segmentation procedures typically detect more than 90% of overstory trees, yet they barely detect 60% of understory trees because of the occlusion effect of higher canopy layers. Although understory trees provide limited financial value, they are an essential component of ecosystem functioning by offering habitat for numerous wildlife species and influencing stand development. Here we model the occlusion effect in terms of point density. We estimate the fractions of points representing different canopy layers (one overstory and multiple understory) and also pinpoint the required density for reasonable tree segmentation (where accuracy plateaus). We show that at a density of ~170 pt/m² understory trees can likely be segmented as accurately as overstory trees. Given the advancements of LiDAR sensor technology, point clouds will affordably reach this required density. Using modern computational approaches for big data, the denser point clouds can efficiently be processed to ultimately allow accurate remote quantification of forest resources. The methodology can also be adopted for other similar remote sensing or advanced imaging applications such as geological subsurface modelling or biomedical tissue analysis.

Total Hip Arthroplasty Outcomes: An 18-Year Experience in a Single Center: Is Systemic Lupus Erythematosus a Potential Risk Factor for Adverse Outcomes?

BACKGROUND: In patients with systemic lupus erythematosus (SLE), persistent joint activity and treatment with glucocorticoids are associated with musculoskeletal complications. About 30% of these patients become candidates for surgical treatment. The aim of this study was to evaluate postoperative outcomes after total hip arthroplasty (THA) in SLE patients. METHODS: We performed a retrospective cohort study at a tertiary care center in Mexico City between 1995 and 2013. All patients with SLE who underwent THA during that period were included (n = 58). They were compared with 2 control groups, one from another inflammatory arthropathy (rheumatoid arthritis, n = 58) and other noninflammatory (osteoarthritis, n = 58), matched by gender and date of surgery. The primary outcome was the frequency of postoperative complications during follow-up. RESULTS: We included 174 patients who underwent THA during the study period. Patients with SLE were younger (P < .0001), had a longer hospitalization stay (P = .001), and required more transfusions (P = .004). Global complications in THA in patients with SLE were more prevalent than rheumatoid arthritis (36.2% vs 15.5%, P = .029) and osteoarthritis (36.2% vs 5.1%, P < .0001) patients. After multivariate analysis, risk factors for THA complications were: SLE (hazard ratio 2.8, 95% confidence interval 1.2-6.8; P = .018) and low postoperative hemoglobin (hazard ratio 0.77, 95% confidence interval 0.73-0.83; P < .0001). Long-term complications after THA were similar among groups. CONCLUSION: This is the largest single-center study regarding clinical outcomes after THA in SLE patients. Our data suggest that SLE is an independent risk factor for adverse postoperative outcomes, mainly immediate complications, but the long-term outcome is good enough to offer surgical treatment that will improve quality of life.

Beneficial effects of chronic oxytocin administration and social co-housing in a rodent model of post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is in part due to a deficit in memory consolidation and extinction. Oxytocin (OXT) has anxiolytic effects and promotes prosocial behaviors in both rodents and humans, and evidence suggests that it plays a role in memory consolidation. We studied the effects of administered OXT and social co-housing in a rodent model of PTSD. Acute OXT yielded a short-term increase in the recall of the traumatic memory if administered immediately after trauma. Low doses of OXT delivered chronically had a cumulating anxiolytic effect that became apparent after 4 days and persisted. Repeated injections of OXT after short re-exposures to the trauma apparatus yielded a long-term reduction in anxiety. Co-housing with naive nonshocked animals decreased the memory of the traumatic context compared with single-housed animals. In the long term, these animals showed less thigmotaxis and increased interest in novel objects, and a low OXT plasma level. Co-housed PTSD animals showed an increase in risk-taking behavior. These results suggest beneficial effects of OXT if administered chronically through increases in memory consolidation after re-exposure to a safe trauma context. We also show differences between the benefits of social co-housing with naive rats and co-housing with other shocked animals on trauma-induced long-term anxiety.

The Histaminergic Tuberomamillary Nucleus Is Involved in Appetite for Sex, Water and Amphetamine.

The histaminergic system is one component of the ascending arousal system which is involved in wakefulness, neuroendocrine control, cognition, psychiatric disorders and motivation. During the appetitive phase of motivated behaviors the arousal state rises to an optimal level, thus giving proper intensity to the behavior. Previous studies have demonstrated that the histaminergic neurons show an earlier activation during the appetitive phase of feeding, compared to other ascending arousal system nuclei, paralleled with a high increase in arousal state. Lesions restricted to the histaminergic neurons in rats reduced their motivation to get food even after 24 h of food deprivation, compared with intact or sham lesioned rats. Taken together, these findings indicate that the histaminergic system is important for appetitive behavior related to feeding. However, its role in other goal-directed behaviors remains unexplored. In the present work, male rats rendered motivated to obtain water, sex, or amphetamine showed an increase in Fos-ir of histaminergic neurons in appetitive behaviors directed to get those reinforcers. However, during appetitive tests to obtain sex, or drug in amphetamine-conditioned rats, Fos expression increased in most other ascending arousal system nuclei, including the orexin neurons in the lateral hypothalamus, dorsal raphe, locus coeruleus and laterodorsal tegmental neurons, but not in the ventral tegmental area, which showed no Fos-ir increase in any of the 3 conditions. Importantly, all these appetitive behaviors were drastically reduced after histaminergic cell-specific lesion, suggesting a critical contribution of histamine on the intensity component of several appetitive behaviors.

A role for the interoceptive insular cortex in the consolidation of learned fear.

A growing body of evidence suggests that learned fear may be related to the function of the interoceptive insular cortex. Using an auditory fear conditioning paradigm in rats, we show that the inactivation of the posterior insular cortex (pIC), the target of the interoceptive thalamus, prior to training produced a marked reduction in fear expression tested 24h later. Accordingly, post-training anisomycin infused immediately, but not 6h after, also reduced fear expression tested the following day, supporting a role for the pIC in consolidation of fear memory. The long-term (ca. a week) and reversible inactivation of the pIC with the sodium channel blocker neosaxitoxin, immediately after fear memory reactivation induced a progressive decrease in the behavioral expression of conditioned fear. In turn, we observed that fear memory reactivation is accompanied by an enhanced expression of Fos and Zif268, early genes involved in neural activity and plasticity. Taken together these data indicate that the pIC is involved in the regulation of fear memories.

Effect of insular cortex inactivation on autonomic and behavioral responses to acute hypoxia in conscious rats.

The present work was aimed to evaluate the contribution of interoception to the autonomic and behavioral responses to hypoxia. To address this issue, we studied whether the inactivation of the primary interoceptive posterior insular cortex (pIC) may disrupt the autonomic and behavioral effects of hypoxia in conscious rats. Rats were implanted with telemetric transmitters and microinjection cannulae placed bilaterally in the pIC. After one week, rats were injected with bupivacaine (26.5µM 1µL/side) and saline (1µL/side) into the pIC, and exposed to hypoxia (∼6% O2) for 150s, and autonomic and behavioral responses were recorded. Hypoxia produces hypertension, tachycardia followed by bradycardia, and hypothermia. When O2 dropped to ∼8%, rats showed escape behavior. Baseline cardiovascular variables and the pattern of hypoxia-induced autonomic and behavioral responses were not disrupted by pIC inactivation. However, pIC inactivation produced a modest but significant temperature decrease, higher bradycardic and hypertensive responses to hypoxia, and a minimal delay in escape onset. In addition, we measured the hypoxia-induced Fos activation in the nucleus tractus solitarius (NTS), the periaqueductal gray matter (PAG) and the pIC, which are key components of the interoceptive pathway. Hypoxia increased the number of Fos-positive neurons in the NTS and PAG, but not in the pIC. Present results suggest that pIC is not involved in the hypoxia-induced behavioral response, which seems to be processed in the NTS and PAG, but has a role in the efferent control of autonomic changes coping with hypoxia.

Histamine and motivation.

Brain histamine may affect a variety of different behavioral and physiological functions; however, its role in promoting wakefulness has overshadowed its other important functions. Here, we review evidence indicating that brain histamine plays a central role in motivation and emphasize its differential involvement in the appetitive and consummatory phases of motivated behaviors. We discuss the inputs that control histaminergic neurons of the tuberomamillary nucleus (TMN) of the hypothalamus, which determine the distinct role of these neurons in appetitive behavior, sleep/wake cycles, and food anticipatory responses. Moreover, we review evidence supporting the dysfunction of histaminergic neurons and the cortical input of histamine in regulating specific forms of decreased motivation (apathy). In addition, we discuss the relationship between the histamine system and drug addiction in the context of motivation.

A role for the insular cortex in long-term memory for context-evoked drug craving in rats.

Drug craving critically depends on the function of the interoceptive insular cortex, and may be triggered by contextual cues. However, the role of the insula in the long-term memory linking context with drug craving remains unknown. Such a memory trace probably resides in some neocortical region, much like other declarative memories. Studies in humans and rats suggest that the insula may include such a region. Rats chronically implanted with bilateral injection cannulae into the high-order rostral agranular insular cortex (RAIC) or the primary interoceptive posterior insula (pIC) were conditioned to prefer the initially aversive compartment of a 2-compartment place preference apparatus by repeatedly pairing it to amphetamine. We found a reversible but long-lasting loss (ca. 24 days) of amphetamine-conditioned place preference (CPP) and a decreased expression in the insula of zif268, a crucial protein in memory reconsolidation, when anisomycin (ANI) was microinjected into the RAIC immediately after the reactivation of the conditioned amphetamine/context memory. ANI infusion into the RAIC without reactivation did not change CPP, whereas ANI infusion into pIC plus caused a 15 days loss of CPP. We also found a 24 days loss of CPP when we reversibly inactivated pIC during extinction trials. We interpret these findings as evidence that the insular cortex, including the RAIC, is involved in a context/drug effect association. These results add a drug-related memory function to the insular cortex to the previously found role of the pIC in the perception of craving or malaise.

The histaminergic tuberomammillary nucleus is critical for motivated arousal.

Obtaining food, shelter or water, or finding a mating partner are examples of motivated behaviors, which are essential to preserve the species. The full expression of such behaviors requires a high but optimal arousal state. We tested the idea that tuberomammillary nucleus (TMN) histamine neurons are crucial to generate such motivated arousal, using a model of the appetitive phase of feeding behavior. Hungry rats enticed with food within a wire mesh box showed intense goal-directed motor activity aimed at opening the box, an increase in core temperature, a fast histamine release in the hypothalamus and an early increase in Fos immunoreactivity in TMN and cortical neurons. Enticing with stronger-tasting food induced stronger motor, temperature and Fos immunoreactivity brain responses than ordinary food pellets. TMN lesion greatly decreased all of those responses. We conclude that histamine neurons increase arousal and vegetative activity, allowing the normal unfolding of voluntary, goal-directed behavior such as obtaining food.

Inactivation of the interoceptive insula disrupts drug craving and malaise induced by lithium.

Addiction profoundly alters motivational circuits so that drugs become powerful reinforcers of behavior. The interoceptive system continuously updates homeostatic and emotional information that are important elements in motivational decisions. We tested the idea that interoceptive information is essential in drug craving and in the behavioral signs of malaise. We inactivated the primary interoceptive cortex in amphetamine-experienced rats, which prevented the urge to seek amphetamine in a place preference task. Interoceptive insula inactivation also blunted the signs of malaise induced by acute lithium administration. Drug-seeking and malaise both induced Fos expression, a marker of neuronal activation, in the insula. We conclude that the insular cortex is a key structure in the perception of bodily needs that provides direction to motivated behaviors.

Valor predictivo de la historia clínica perinatológica para morbimortalidad neonatal en el Hospital Regional del Cusco / Predictive value of the perinatological clinical history for neonatal morbimortality in the Hospital Regional of Cusco

El presente estudio trata de evaluar la utilidad de la Historia Clínica Perinatal utilizada en el Servicio de Neonatología del Departamento de Pediatría del Hospital Regional del Cusco para predecir la ocurrencia de enfermedades neonatales. Se realizó el estudio en un universo de 2,739 niños nacidos entre julio de 1992 y junio de 1993 en el Servicio de Neonatología del Departamento de Pediatría del Hospital Regional del Cusco. El mencionado universo se dividió en 2 subpoblaciones: una subpoblación o grupo de control que lo conformaban las historias perinatales de los niños sanos y un grupo o subpoblación de estudio representado por las historias perinatales de los niños que manifestaron enfermedad neonatal. Para facilitar el estudio sólo se tomaron en cuenta las 4 enfermedades neonatales más frecuentes que en el período de trabajo fueron: Asfixia neonatal, Prematurez, Sepsis neonatal, Pequeño para la edad gestacional. Se trabajó con la totalidad de la población de estudio (303), mientras que para la población control se determinó una muestra de 47 historias perinatales de niños sanos. Evaluando diferentes factores de riesgo para las enfermedades neonatales más frecuentes y confrontándolas con la presencia o no de estos mismos factores en las historias de niños que no presentaron patología, a través de tablas de doble entrada, se determinó la sensibilidad y especificidad de la mencionada historia mediante fórmulas aplicadas a los resultados que las tablas de doble entrada arrojaban, para predecir el nacimiento de neonatos en riesgo. Se concluye, luego de evaluados los resultados que la mencionada Historia Clínica Perinatal tiene valor para predecir el nacimiento de niños asfixiados, prematuros o que desarrollarán sepsis neonatal, mas no para niños que nacerán pequeños para la edad gestacional.