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Melasma is a chronic, relapsing hyperpigmentation disorder that primarily affects photoexposed areas, occurring most frequently in adult women with darker skin phototypes. The primary factors contributing to its development include sun exposure, sex hormones (e.g., pregnancy), and genetic predisposition. Melasma is highly prevalent in Latin America, where many countries lie in intertropical zones and exhibit significant ethnic diversity because of centuries of intermixing among Native Americans, Europeans, and Sub-Saharan Africans. Nine Latin American experts formulated a DELPHI-based consensus to develop a valuable approach for treating melasma in this diverse population. After establishing an accurate diagnosis, assessing the impact on quality of life, and determining disease severity, the consensus recommends mitigating known triggers and promoting rigorous photoprotection. Active therapy should be tailored based on individual characteristics (e.g., pregnancy status, previous treatments, skin sensitivity). Treatment options include topical depigmenting agents, systemic therapies, and procedural interventions such as laser therapy, microneedling, and chemical peels. Periodic reassessment of the treatment is essential, with strategies adjusted if targeted outcomes are not achieved. Once clinical remission is attained, patients should continue using topical depigmenting agents and maintain strict photoprotection measures to prevent recurrence., (© 2024 the International Society of Dermatology.)

Climate change increasingly influences the loss of biodiversity, especially in ectothermic organisms, which depend on environmental temperatures to obtain heat and regulate their life cycle. Studies that aim to understand the impact of temperature variation are important to better understand the possible impacts generated on the homeostasis of ectothermic organisms. Our objective was to characterize the responses of juvenile Liolaemus arambarensis lizards to abrupt changes in temperature, quantifying markers of body condition, intermediary and hormonal metabolism and oxidative balance. We collected 45 juvenile individuals of L. arambarensis (winter: 20 and summer: 25) in Barra do Ribeiro, Brazil. We transported the animals to the laboratory, where they were acclimatized for five days at a temperature of 20 °C, then divided and exposed to temperatures of 10 °C, 20 °C, 30 °C and 40 °C for 24 h. After exposure, the animals were euthanized and the brain, caudal muscle, thigh, and liver tissues were extracted for quantification of biomarkers of metabolism (glycogen and total proteins) and oxidative balance (acetylcholinesterase, superoxide dismutase, catalase, glutathione-S-transferase and lipoperoxidation) and plasma for corticosterone quantification. The results show that L. arambarensis is susceptible to sudden temperature variations, where higher temperatures caused greater activity of antioxidant enzymes, increased lipoperoxidation and higher plasma levels of corticosterone in animals eliminated in winter. The present study demonstrated that abrupt changes in temperature could significantly modify the homeostatic mechanisms of animals, which could lead to oxidative stress and a potential trade-off between survival and growth/reproduction. In this context, the organism mobilizes energy resources for survival, with possible damage to growth and reproduction. Demonstrate that a change in temperature can be a potential factor in extinction for a species given the profile of global climate change., Competing Interests: Declaration of competing interest There was no conflict of interest between the authors. All agree with the submission of the work to the journal., (Copyright © 2024 Elsevier Inc. All rights reserved.)

There are several determinants of mental health symptoms, ranging from individual characteristics to social factors. Consistent with patterns in the general population, students with evening characteristics tend to exhibit more anxiety symptoms and poorer sleep quality compared to morning students. Meal timing also appears to affect sleep and may be associated with mental health symptoms. In this context, the aim of the present study was to investigate the association of the timing of the main and last meals of the day with sleep quality and anxiety levels, according to the chronotype of university students. This study was conducted in colleges in São Paulo, Brazil, and involved application of a questionnaire to 162 university students. The questionnaire collected sociodemographic information meal and study times, and included scales assessing eveningness and morningness, sleep quality, and anxiety. Students demonstrating a phase delay in both chronotype and dinner timing exhibited higher levels of anxiety compared to morning-type students. Although no associations were observed between meal timing and sleep quality, sleeping later was associated with poorer sleep quality. The study suggests that evening students and those who eat late at night are more prone to presenting mental health symptoms. More studies are needed to further investigate this association.

Reptiles are the least studied vertebrates regarding the impact of pesticides on their health, despite being good models for ecotoxicological studies given their abundance and easy handling. Salvator merianae is widely distributed in South America and often found in agricultural cultivation areas. Here, we compared the morphological, biochemical, and physiological parameters of S. merianae from an exposed area (EA) to pesticides and a reference area (RA) or control. These parameters were measured in plasma (albumin, alanine transaminase, alkaline phosphatase, gamma-glutamyl transpeptidase, glucose, total proteins, uric acid, triglycerides, VLDL, and corticosterone) and in erythrocytes (TBARS, glutathione S-transferase, superoxide dismutase, and catalase activity). Blood samples were collected from 28 lizards (EA: three juveniles, three adult females, and three adult males; RA: nine juveniles, four females, and five males) in southern Brazil during the reproductive period. We observed a decrease in body mass, the ratio between body mass and total length and snout-vent length in juvenile lizards collected at EA. The levels of TBARS, glutathione S-transferase, triglycerides, VLDL, and uric acid were altered for juveniles in EA. When comparing the two areas, females differed in superoxide dismutase activity and total proteins, while males differed in superoxide dismutase, catalase, and glutathione S-transferase activity. This set of results shows that S. merianae, especially juveniles, suffers a negative impact when inserted in an agricultural area. The analyzed biomarkers proved suitable for monitoring these lizards and the quality of this environment., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Magnetic nanoparticles, such as magnetite (Fe 3 O 4 ), exhibit superparamagnetic properties below 15 nm at room temperature. They are being explored for medical applications, and the coprecipitation technique is preferred for cost-effective production. This study investigates the impact of synthesis temperature on the nanoparticles' physicochemical characteristics. Two types of magnetic analysis were conducted. Samples T 40, T 50, and T 60 displayed superparamagnetic behavior, as evidenced by the magnetization curves. The experiments verified the development of magnetic nanoparticles with an average diameter of approximately dozens of nanometers, as determined by various measurement methods such as XDR, Raman, and TEM. Raman spectroscopy showed the characteristic bands of the magnetite phase at 319, 364, 499, and 680 cm -1 . This was confirmed in the second analysis with the ZFC-FC curves, which showed that the samples' blocking temperatures were below ambient temperature. ZFC-FC curves revealed a similar magnetization of about 30 emu/g when applying a magnetic field of 5 kOe., Competing Interests: All authors declare that there are no financial and personal relationships with other people or organizations that could inappropriately influence (bias) our paper., (© 2024 The Authors.)

Objective: The aim of the study was to phenotypically investigate the expression of the enzyme Klebsiella pneumoniae carbapenemase (KPC) in a Proteus mirabilis sample resistant to carbapenems, isolated from the wound of a patient with a venous leg ulcer (VLU) treated at an outpatient referral service., Method: This was a case study conducted with a patient who had a VLU on the lower left limb. Samples were taken for the examination of microbiological material from the patient's wound, using an aseptic technique. The colonies extracted were submitted to Gram staining and biochemical tests to identify the strain. In addition, an antimicrobial susceptibility test, E-test and a modified Hodge test were performed., Results: The identified microorganism was Proteus mirabilis , which showed resistance to cefuroxime and the carbapenems imipenem and meropenem. As well as the minimum inhibitory concentration (MIC) of 3.0μg/ml for imipenem, demonstrating resistance, there was no KPC production by the tested isolate, which presented a negative modified Hodge test., Conclusion: The results highlight the importance of microbiological surveillance, aimed at reducing morbidity and mortality rates associated with infection by multiresistant bacteria.

Sapodilla (Achras zapota L.) is a fruit with a great nutritional potential; however, its perishable nature is a great obstacle for commercialization/exportation. Herein, osmotic dehydration was applied to sapodilla to reduce post-harvest losses and obtain a stable product with acceptable sensorial characteristics. Initially, a 2³ full-factorial design was performed to determine the effect of temperature (30−50 °C), sucrose concentration (40−60% °Brix) and immersion time (90−240 min) on the moisture loss (ML), solid gain (SG) and dehydration efficiency index (DEI). The samples with higher DEI values were subjected to sensory analysis, followed by physicochemical, microbiological and structural analyses. The temperature and the concentration of the osmotic solution had significant influence (p < 0.05) on ML and SG, whereas DEI was significantly influenced (p < 0.05) by the concentration of osmotic solution and the immersion time. The sample produced by osmotic dehydration using the optimized conditions (40 °C, 50 °Brix; 165 min) obtained higher scores on the sensorial attributes, greater compliance with microbiological standards and generated turgor reduction and ruptures of sapodilla cell walls.

NiFe and CoFe (MFe) layered double hydroxides (LDHs) are among the most active electrocatalysts for the alkaline oxygen evolution reaction (OER). Herein, we combine electrochemical measurements, operando X-ray scattering and absorption spectroscopy, and density functional theory (DFT) calculations to elucidate the catalytically active phase, reaction center and the OER mechanism. We provide the first direct atomic-scale evidence that, under applied anodic potentials, MFe LDHs oxidize from as-prepared α-phases to activated γ-phases. The OER-active γ-phases are characterized by about 8% contraction of the lattice spacing and switching of the intercalated ions. DFT calculations reveal that the OER proceeds via a Mars van Krevelen mechanism. The flexible electronic structure of the surface Fe sites, and their synergy with nearest-neighbor M sites through formation of O-bridged Fe-M reaction centers, stabilize OER intermediates that are unfavorable on pure M-M centers and single Fe sites, fundamentally accounting for the high catalytic activity of MFe LDHs.

Background: The association between neurofibromatosis type 1 (NF-I) and Chiari I malformation (CMI) is rare, and not many studies are reported in the literature. Performing magnetic resonance imaging (MRI) in patients with NF-1 is essential because several cases of Chiari type I are completely asymptomatic. We emphasize the need for inclusion of Chiari I as diagnosis in association with NF-1., Case Description: The patient was a 51-year-old black man who presented with complaints of pain and decreased motion and sensibility of his hands, wrists, and forearms, along with progressive dysarthria. Even though the computed tomography (CT) scan of the skull did not show changes, the MRI showed hydro/syringomyelia in the cervical spine area. Midline suboccipital craniectomy with total laminectomy of c1 and partial laminectomy of c2 was performed; tonsillectomy was also performed for cistern expansion because of intense thickening and obliteration of the obex by the cerebellar tonsils. Following treatment, the patient showed remission of symptoms., Conclusion: NF-1 in association with CMI is rare, and early diagnosis and surgical treatment are essential to slow down the myelopathy; although they prevent neurological damages, patients with NF-1 must remain under doctor's attention in case of association with CMI. Our literature review showed that symptoms can vary and include headache, gait disturbance, and sensory/motor diminution, until asymptomatic patients. Moreover, the incidence of NF-1 is considerably higher in CMI patients in comparison to the global incidence (8.6-11.8% and 0.775%, respectively). The surgical technique must be evaluated case by case according to the degree of cerebrospinal fluid obstruction.

Background: Fibrous dysplasia (FD) is a benign fibro-osseous lesion related to an abnormal bone development and replacement by fibrous tissue. FD has three clinical patterns namely monostotic, polyostotic, and the McCune-Albright syndrome (MAS). MAS is a rare genetic disorder (about 3% of all FD's) that comprises a triad of polyostotic FD, café-au-lait skin macules, and precocious puberty. MAS can involve the orbit region and cause stenosis in the optic canal, leading the patient to a progressive visual loss., Methods: We reported a case of craniofacial FD in MAS in a 9-year-old male with progressive visual loss, submitted to optic nerve decompression by fronto-orbito-zygomatic approach, with total recovery. A research was made at Bireme, PubMed, Cochrane, LILACS, and MEDLINE with the keywords: FD/craniofacial/McCune-Albright/Optic compression for the clinical review., Results: A clinical review of the disease was made, the multiple, clinical, and surgical management options were presented, and the case report was reported., Conclusion: MAS is a rare disease with a progressive polyostotic FD. Whenever it affects the orbit region, the optic canal, and it is associated with a progressive visual loss, the urgent optic nerve decompression is mandatory, either manually or with a rapid drill. It is known that aggressive approach is associated with less recurrence; it is also associated with worsening of the visual loss in optic nerve decompression. In MAS cases, multiple and less aggressive surgeries seem to be more suitable.

We constructed a versatile magnetometer assembly for characterizing iron oxide nanoparticles. The magnetometer can be operated at room temperature or inside a cryocooler at temperatures as low as 6 K. The magnetometer's sensor can be easily exchanged and different detection electronics can be used. We tested the assembly with a non-cryogenic commercial Hall sensor and a benchtop multimeter in a four-wire resistance measurement scheme. A magnetic moment sensitivity of 8.5 × 10(-8) Am(2) was obtained with this configuration. To illustrate the capability of the assembly, we synthesized iron oxide nanoparticles coated with different amounts of a triblock copolymer, Pluronic F-127, and characterized their magnetic properties. We determined that the polymer coating does not affect the magnetization of the particles at room temperature and demonstrates that it is possible to estimate the average size of coating layers from measurements of the magnetic field of the sample.

Actimetry has been used to estimate the sleep-wake cycle instead of the rest-activity rhythm. Although algorithms for assessing sleep from actimetry data exist, it is useful to analyze the rest-activity rhythm using nonparametric methods. This would then allow rest-activity rhythm stability, fragmentation and amplitude to be quantified. In addition, sleep and wakefulness efficiency can be quantified separately. These variables have been used in studies analyzing the effect of age, diseases and their respective treatments on human circadian rhythmicity. In this study, we carried out a comprehensive analysis of the main results from published articles and devised a functional model of interaction among the several components involved in generating the sleep-wake cycle. The nonparametric variables render it possible to infer the main characteristics of circadian rhythms, such as synchronization with a zeitgeber, and its amplitude and robustness., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Glioblastoma multiforme (GBM) is the most common glial tumor of the brain system; nevertheless, the giant cell (GC) subtype is uncommon. Recent reviews report for an incidence of 1% in adults and 3% in children. The GCs usually have a better prognosis than GBM and also an increasing long-term survival rate. It is known that the diagnosis of this tumor is due to its histological findings and patterns, such as the unusual increased number of giant cells. Unfortunately, due to its rarity, the immunohistochemical and cytogenetical analysis of this tumor is not well known. Some authors also suggest that there are few subtypes of GCs and their patterns of aggressiveness could be due to cytogenetical markers. It is recognized that maximum safe resection treatment and adjuvant radiotherapy can improve survival rate (5-13 months) similar to GBM patients.

Circadian rhythmicity in humans has been well studied using actigraphy, a method of measuring gross motor movement. As actigraphic technology continues to evolve, it is important for data analysis to keep pace with new variables and features. Our objective is to study the behavior of two variables, interdaily stability and intradaily variability, to describe rest activity rhythm. Simulated data and actigraphy data of humans, rats, and marmosets were used in this study. We modified the method of calculation for IV and IS by modifying the time intervals of analysis. For each variable, we calculated the average value (IVm and ISm) results for each time interval. Simulated data showed that (1) synchronization analysis depends on sample size, and (2) fragmentation is independent of the amplitude of the generated noise. We were able to obtain a significant difference in the fragmentation patterns of stroke patients using an IVm variable, while the variable IV60 was not identified. Rhythmic synchronization of activity and rest was significantly higher in young than adults with Parkinson׳s when using the ISM variable; however, this difference was not seen using IS60. We propose an updated format to calculate rhythmic fragmentation, including two additional optional variables. These alternative methods of nonparametric analysis aim to more precisely detect sleep-wake cycle fragmentation and synchronization.

During sleep, humans experience the offline images and sensations that we call dreams, which are typically emotional and lacking in rational judgment of their bizarreness. However, during lucid dreaming (LD), subjects know that they are dreaming, and may control oneiric content. Dreaming and LD features have been studied in North Americans, Europeans and Asians, but not among Brazilians, the largest population in Latin America. Here we investigated dreams and LD characteristics in a Brazilian sample (n = 3,427; median age = 25 years) through an online survey. The subjects reported recalling dreams at least once a week (76%), and that dreams typically depicted actions (93%), known people (92%), sounds/voices (78%), and colored images (76%). The oneiric content was associated with plans for the upcoming days (37%), memories of the previous day (13%), or unrelated to the dreamer (30%). Nightmares usually depicted anxiety/fear (65%), being stalked (48%), or other unpleasant sensations (47%). These data corroborate Freudian notion of day residue in dreams, and suggest that dreams and nightmares are simulations of life situations that are related to our psychobiological integrity. Regarding LD, we observed that 77% of the subjects experienced LD at least once in life (44% up to 10 episodes ever), and for 48% LD subjectively lasted less than 1 min. LD frequency correlated weakly with dream recall frequency (r = 0.20, p < 0.01), and LD control was rare (29%). LD occurrence was facilitated when subjects did not need to wake up early (38%), a situation that increases rapid eye movement sleep (REMS) duration, or when subjects were under stress (30%), which increases REMS transitions into waking. These results indicate that LD is relatively ubiquitous but rare, unstable, difficult to control, and facilitated by increases in REMS duration and transitions to wake state. Together with LD incidence in USA, Europe and Asia, our data from Latin America strengthen the notion that LD is a general phenomenon of the human species.

Several lines of evidence converge to the idea that rapid eye movement sleep (REMS) is a good model to foster our understanding of psychosis. Both REMS and psychosis course with internally generated perceptions and lack of rational judgment, which is attributed to a hyperlimbic activity along with hypofrontality. Interestingly, some individuals can become aware of dreaming during REMS, a particular experience known as lucid dreaming (LD), whose neurobiological basis is still controversial. Since the frontal lobe plays a role in self-consciousness, working memory and attention, here we hypothesize that LD is associated with increased frontal activity during REMS. A possible way to test this hypothesis is to check whether transcranial magnetic or electric stimulation of the frontal region during REMS triggers LD. We further suggest that psychosis and LD are opposite phenomena: LD as a physiological awakening while dreaming due to frontal activity, and psychosis as a pathological intrusion of dream features during wake state due to hypofrontality. We further suggest that LD research may have three main clinical implications. First, LD could be important to the study of consciousness, including its pathologies and other altered states. Second, LD could be used as a therapy for recurrent nightmares, a common symptom of depression and post-traumatic stress disorder. Finally, LD may allow for motor imagery during dreaming with possible improvement of physical rehabilitation. In all, we believe that LD research may clarify multiple aspects of brain functioning in its physiological, altered and pathological states., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Mammals exhibit daily anticipatory activity to cycles of food availability. Studies on such food anticipatory activity (FAA) have been conducted mainly in nocturnal rodents. They have identified FAA as the behavioral output of a food entrained oscillator (FEO), separate of the known light entrained oscillator (LEO) located in the suprachiasmatic nucleus (SCN) of hypothalamus. Here we briefly review the main characteristics of FAA. Also, we present results on four topics of food anticipation: (1) possible input signals to FEO, (2) FEO substrate, (3) the importance of canonical clock genes for FAA, and (4) potential practical applications of scheduled feeding. This mini review is intended to introduce the subject of food entrainment to those unfamiliar with it but also present them with relevant new findings on the issue.

The Brazilian Cerrado is the second largest biome in Brazil and is considered a biodiversity hotspot. In this work, we compared the bacterial communities in Cerrado soil associated with four types of native vegetation (Cerrado Denso, Cerrado sensu stricto, Campo Sujo, and Mata de Galeria) by ribosomal RNA intergenic spacer analysis, terminal fragment restriction length polymorphism and pyrosequencing. The fingerprinting results were very similar. The bacterial communities of Cerrado Denso and Cerrado sensu stricto grouped together and were distinct from those in Campo Sujo and Mata de Galeria. Pyrosequencing generated approximately 40,000 16S rRNA gene sequences per sample and allowed the identification of 17 phyla in soil samples under Cerrado vegetation. Acidobacteria were dominant in all areas studied with a relative frequency of 40-47 %, followed closely by Proteobacteria accounting for 34-40 % of the sequences. Results from all molecular techniques used suggested that the bacterial communities of Cerrado sensu stricto and Cerrado Denso are very similar to each other, while Campo Sujo forms a separate group, and Mata de Galeria is the most distinct with higher species richness. This is the first extensive study of native Cerrado soil microbiota, an important but endangered biome.

Traditionally, chronotype classification is based on the Morningness-Eveningness Questionnaire (MEQ). It is implicit in the classification that intermediate individuals get intermediate scores to most of the MEQ questions. However, a small group of individuals has a different pattern of answers. In some questions, they answer as "morning-types" and in some others they answer as "evening-types," resulting in an intermediate total score. "Evening-type" and "Morning-type" answers were set as A(1) and A(4), respectively. Intermediate answers were set as A(2) and A(3). The following algorithm was applied: Bimodality Index = (Sigma A(1) x Sigma A(4))(2) - (Sigma A(2) x Sigma A(3))(2). Neither-types that had positive bimodality scores were classified as bimodal. If our hypothesis is validated by objective data, an update of chronotype classification will be required.

Food is critical for all animal species. Its temporal availability is a relevant signal for organizing behavioral and physiological parameters. When food is restricted to a few hours per day, rats, mice, and other mammals exhibit anticipatory activity before mealtime (food-anticipatory activity). There is considerable evidence suggesting that this anticipation is mediated by a food-entrainable oscillator (FEO) with circadian properties, but located outside the suprachiasmatic nucleus of the hypothalamus (the light-entrainable oscillator). However, the locus of the FEO as well as the mechanisms by which food entrainment occurs is unclear. In this review, we summarize data about the potential input pathways to the FEO and propose a model for understanding it as a network of interconnected brain structures entrained by fluctuation of different humoral signals.

Circadian rhythms are regarded as essentially ubiquitous features of animal behavior and are thought to confer important adaptive advantages. However, although circadian systems of rodents have been among the most extensively studied, most comparative biology is restricted to a few related species. In this study, the circadian organization of locomotor activity was studied in the subterranean, solitary north Argentinean rodent, Ctenomys knightii. The genus, Ctenomys, commonly known as Tuco-tucos, comprises more than 50 known species over a range that extends from 12 degrees S latitude into Patagonia, and includes at least one social species. The genus, therefore, is ideal for comparative and ecological studies of circadian rhythms. Ctenomys knightii is the first of these to be studied for its circadian behavior. All animals were wild caught but adapted quickly to laboratory conditions, with clear and precise activity-rest rhythms in a light-dark (LD) cycle and strongly nocturnal wheel running behavior. In constant dark (DD), the rhythm expression persisted with free-running periods always longer than 24 h. Upon reinstatement of the LD cycle, rhythms resynchronized rapidly with large phase advances in 7/8 animals. In constant light (LL), six animals had free-running periods shorter than in DD, and 4/8 showed evidence of "splitting." We conclude that under laboratory conditions, in wheel-running cages, this species shows a clear nocturnal rhythmic organization controlled by an endogenous circadian oscillator that is entrained to 24 h LD cycles, predominantly by light-induced advances, and shows the same interindividual variable responses to constant light as reported in other non-subterranean species. These data are the first step toward understanding the chronobiology of the largest genus of subterranean rodents.

The motor activity (MA) patterns of rodents are commonly detected in the laboratory using infrared photo-beams or running wheels. In chronobiological studies, the MA rhythm is considered as a behavioural output of the circadian pacemaker. This paper describes a method to obtain long-term records of MA in rodents, with a 1mm spatial resolution and a 1s temporal resolution. The device comprised a square platform laid on top of three force transducers, allowed the calculation of the coordinates of the centre of force exerted by a freely moving rodent, and continuously monitored its displacements. A specific computer program processed the trajectories, providing an exhaustive analysis of motion. To test this method, motor behavioural activity was studied in rats exposed to conditions that favoured rhythmicity: light-dark cycles of both 24 h (LD) and 22 h (T22), and constant darkness (DD). In addition, arrhythmicity patterns were studied under constant light (LL) conditions, and in animals with permanent lesions of the hypothalamic suprachiasmatic nucleus (SCNx). A single description of the general MA distribution at 24 h was obtained using infrared photo-beams. By contrast, under LD conditions, a 24-h rhythm with ultradian components was seen in the total distance travelled, whereas that detected in the number of slow motions showed less ultradian components. In addition, a regional preference in the nesting place was detected under both LD and DD conditions. In one SCNx animal and another exposed to LL conditions, both showing arrhythmicity in photo-beam-detected MA, a 24 h rhythm was observed in regional preference; other LL animal presented a 24 h rhythm in the number of slow motions. This method has capabilities lacking in commonly used techniques. The potential uses of this approach, principally in cronobiological studies, are discussed.

Background: Recently, several papers have shown that a small subset of retinal ganglion cells (RGCs), which project to the suprachiasmatic nucleus (SCN) and contain a new photopigment called melanopsin, are the photoreceptors involved in light-dark entrainment in rodents. In our primate colony, we found a couple of common marmosets (Callithrix jacchus) that had developed progressive and spontaneous visual deficiency, most likely because of retinal degeneration of cones and/or rods. In this study, we evaluated the photoresponsiveness of the circadian system of these blind marmosets., Methods: Two blind and two normal marmosets were kept in cages with a controlled light-dark cycle (LD) to study photoentrainment, masking, and phase response to a dark pulse., Results: Blind marmosets were entrained with the new LD cycle when light onsets were delayed and advanced by 6 hours. In constant light conditions, blind marmosets free-ran with a period of 23.2 hours, while normal animals free-ran with a period of 23.6 hours. All marmosets responded to dark pulses in the early subjective day with phase delays and with phase advances in the late subjective day., Conclusion: Our results demonstrate that light can synchronize circadian rhythms of blind marmosets and consequently, that this species could be a good primate model for circadian photoreception studies.

The sleep-wake cycle of students is characterized by delayed onset, partial sleep deprivation and poor sleep quality. Like other circadian rhythms, the sleep-wake cycle is influenced by endogenous and environmental factors. The aim of the present study was to determine the effects of different class starting times on the sleep-wake pattern of 27 medical students. The data were collected during two medical school semesters having different class starting times. All subjects answered the Portuguese version of the Horne and Ostberg Morningness/Eveningness Questionnaire, the Pittsburgh Sleep Quality Index (PSQI) and kept a sleep diary for two weeks during each semester. Better sleep quality (PSQI = 5.3 vs 3.4), delayed sleep onset (23:59 vs 0:54 h) and longer sleep duration (6 h and 55 min vs 7 h and 25 min) were observed with the late schedule. We also found reduced sleep durations during weekdays and extended sleep durations during weekends. This pattern was more pronounced during the semester with the early class schedule, indicating that the students were more sleep deprived when their classes began earlier in the morning. These results require further investigation regarding the temporal organization of our institutions.

An attempt has been made to define semen seasonality in a horse in the Southern Hemisphere. Repeated measurements of three variables in the semen were made for 36 months (Jan/90-Dec/92) in a 21-year old "Mangalarga" stallion living under natural photoperiod and temperature conditions in a farm situated in São José do Rio Pardo, São Paulo, Brazil (latitude 21 degrees) 36'S; longitude 46 degrees 53' W). The horse fed on natural pasture and a nutritionally balanced feed twice a day (11:00 and 17:00 h). Water and mineral supplement were available ad libitum. Semen was collected almost daily by an artificial vagina and showed annual changes in volume of ejaculate, sperm motility, and sperm concentration. Spectral and rhythmometric analyses of the semen data were performed according to the fast Fourier transform (FFT) and cosinor techniques (tau = 365 days). Statistically significant annual rhythms for semen volume, motility, and concentration of sperm were present. Acrophases occurred in the spring (October) for ejaculate volume and in autumn (May) for sperm concentration and motility.

The objective of the present study was to investigate the circadian and the ultradian rhythms of drinking behavior in Wistar rats maintained under conditions of constant darkness. Six mature male rats (weighing 270-350 g) were exposed to light-dark 12:12-h cycles (LD 12:12, light on at 12:00 h) for 35 days and then switched to constant darkness (DD) conditions for at least 2 weeks. Drinking behavior was monitored continuously with a standard drinkometer circuit and the data was stored in 5-min bins. A modification of Enright's periodogram technique was used to evaluate the free-running drinking behavior circadian rhythm. Ultradian rhythms in drinking behavior were estimated by the Fast Fourier Transform (FFT) technique. Two of the animals (rats 4 and 6) showed no statistically significant circadian or ultradian rhythms and the other four showed free-running drinking circadian rhythm behavior shorter than 24 h (ranging from 23.333 to 23.967 h). Ultradian rhythms of drinking behavior of 12- and 8-h periods were detected in 4 (rats 1, 2, 3 and 5) and 2 (rats 1 and 5) animals, respectively. The relation of the compound structure of the circadian and ultradian rhythms is discussed demonstrating that drinking behavior is a good marker for studies of physiology of temporal organization.