Food intake and weight of lactating rats maintained on different protein-calorie diets, and pup growth

Studies on rats maintained on low-protein-calorie diets during the lactation period show that food intake decreases. This process results in weight loss and a delay in litter development. The purpose of the present study was to determine the alterations in food intake, maternal weight and litter growth during lactation when dams were exposed to diets with different levels of protein and carbohydrate. Female Wistar rats receiving one of 4 different diets, A (N = 14), B (N = 14), C (N = 9) and D (N = 9), were used. Diet A contained 16% protein and 66% carbohydrate; diet B, 6% protein and 77% carbohydrate; diet C, 6% protein and 66% carbohydrate; diet D, 16% protein and 56% carbohydrate. Thus, C and D diets were hypocaloric, while A and B were isocaloric. The intake of a low-protein diet in groups B and C affected the weight of dams and litters during the last two weeks of lactation, while the low-calorie diets limited the growth of D litters at 21 days compared with A litters, but had no effect on the weight of D dams. Group B showed an increase in intake during the first five days of lactation, resulting in a behavioral calorie compensation due to the increase in carbohydrate content, but the intake decreased during the last part of lactation. Food intake regulation predominantly involves the recruitment of a variety of peripheral satiety systems that attempt to decrease the central feeding command system.

Low-cost automatic activity data recording system

We describe a low-cost, high quality device capable of monitoring indirect activity by detecting touch-release events on a conducting surface, i.e., the animal's cage cover. In addition to the detecting sensor itself, the system includes an IBM PC interface for prompt data storage. The hardware/software design, while serving for other purposes, is used to record the circadian activity rhythm pattern of rats with time in an automated computerized fashion using minimal cost computer equipment (IBM PC XT). Once the sensor detects a touch-release action of the rat in the upper portion of the cage, the interface sends a command to the PC which records the time (hours-minutes-seconds) when the activity occurred. As a result, the computer builds up several files (one per detector/sensor) containing a time list of all recorded events. Data can be visualized in terms of actograms, indicating the number of detections per hour, and analyzed by mathematical tools such as Fast Fourier Transform (FFT) or cosinor. In order to demonstrate method validation, an experiment was conducted on 8 Wistar rats under 12/12-h light/dark cycle conditions (lights on at 7:00 a.m.). Results show a biological validation of the method since it detected the presence of circadian activity rhythm patterns in the behavior of the rats

Endogenous vasopressin and the central control of heart rate during dynamic exercise

The present article contains a brief review on the role of vasopressinergic projections to the nucleus tractus solitarii in the genesis of reflex bradycardia and in the modulation of heart rate control during exercise. The effects of vasopressin on exercise tachycardia are discussed on the basis of both the endogenous peptide content changes and the heart rate response changes observed during running in sedentary and trained rats. Dynamic exercise caused a specific vasopressin content increase in dorsal and ventral brainstem areas. In accordance, rats pretreated with the peptide or the V1 blocker into the nucleus tractus solitarii showed a significant potentiation or a marked blunting of the exercise tachycardia, respectively, without any change in the pressure response to exercise. It is proposed that the long-descending vasopressinergic pathway to the nucleus tractus solitarii serves as one link between the two main neural controllers of circulation, i.e., the central command and feedback control mechanisms driven by the peripheral receptors. Therefore, vasopressinergic input could contribute to the adjustment of heart rate response (and cardiac output) to the circulatory demand during exercise.

Evaluation of electromyographic activity and heart rate responses to isometric exercise. The role played by muscular mass and type

The purpose of the present study was to examine the relationship between the electromyographic (EMG) activity and heart rate (HR) responses induced by isometric exercise performed by knee extension (KE) and flexion (KF) in men. Fifteen healthy male subjects, 21 ± 1.3 years (mean ± SD), were submitted to KE and KF isometric exercise tests at 100% of maximal voluntary contraction (MVC). The exercises were performed with one leg (right or left) and with two legs simultaneously, for 10 s in the sitting position with the hip and knee flexed at 90o. EMG activity (root mean square values) and HR (beats/min) were recorded simultaneously both at rest and throughout the sustained contraction. The HR responses to isometric exercise in KE and KF were similar when performed with one and two legs. However, the HR increase was always significantly higher in KE than KF (P<0.05), whereas the EMG activity was higher in KE than in KF (P<0.05), regardless of the muscle mass (one or two legs) involved in the effort. The correlation coefficients between HR response and the EMG activity during KE (r = 0.33, P>0.05) and KF (r = 0.15, P>0.05) contractions were not significant. These results suggest that the predominant mechanism responsible for the larger increase in HR response to KE as compared to KF in our study could be dependent on qualitative and quantitative differences in the fiber type composition found in each muscle group. This mechanism seems to demand a higher activation of motor units with a corresponding increase in central command to the cardiovascular centers that modulate HR control.

Scientist-friendly policies for non-native English-speaking authors: timely and welcome

That English is the lingua franca of today's science is an indisputable fact. Publication in English in international journals is a pre-requisite for a research paper to gain visibility in academia. However, English proficiency appears to be taken for granted in the scientific community, though this language can be a hurdle for a number of authors, particularly from non-native English-speaking countries. The influence of English proficiency on the publication output of Brazilian authors has never been assessed. We report our preliminary data on the relationship between the English proficiency of 51,223 researchers registered in the CNPq database and their publication output in international journals. We have found that publication rates are higher for those authors with good command of English, particularly written English. Although our research is still underway and our results are preliminary, they suggest that the correlation between written English proficiency and research productivity should not be underestimated. We also present the comments of some Brazilian scientists with high publication records on the relevance of communication skills to the scientific enterprise.

Suomalaisen ja yhdysvaltalaisen mekanisoidun komppanian johtamisen eroavaisuudet hyökättäessä kohtaamisolosuhteissa

Nykyaikaisella taistelukentällä sodankuvan muutos, joukkojen mekanisoituminen ja rintamalinjojen hämärtyminen ovat kasvattaneet kohtaamishyökkäysten mahdollisuutta. Tällöin tarkkaa tietoa vihollisesta ei ole ja saatetaan törmätä hyökkäävään tai puolustukseen ryhmittyneeseen viholliseen. Tutkimuksen tarkoituksena on löytää eroja yhdysvaltalaisen ja suomalaisen mekanisoidun komppanian johtamisympäristöistä, hyökkäyksen suunnittelu- ja valmisteluvaiheen johtamisesta sekä taistelun johtamisesta hyökättäessä kohtaamistaisteluolosuhteissa. Tutkimus on luonteeltaan kvalitatiivinen. Aineisto on hankittu asiakirja- ja kirjallisuustutkimuksen keinoin molempien maiden ohjesäännöistä ja sotilaskirjallisuudesta. Havaintoja suomalaisen komppanian johtamisesta on täydennetty haastattelemalla kokenutta panssarijääkärikomppanian päällikköä. Tutkimuksessa on ensin tutkittu molempien maiden ohjesääntöjä koskien mekanisoitujen joukkojen johtamista kohtaamistaisteluolosuhteissa. Näitä havaintoja on pyritty täydentämään tutkimalla uusimpia sotia ja kertausharjoituksia. Tärkeimpiä lähteitä ovat olleet yhdysvaltojen armeijan kenttäohjeet (field manuals), panssarijääkäriopas, sekä sotakokemuksista kertova Leadership and command on the battlefield. Johtopäätöksenä voidaan todeta, että molempien maiden taktiset toimintatavat ovat hyvin samankaltaisia. Suurimmat erot löytyvät maiden välillä organisaatioista ja johtamiskulttuurista. Komppanian avainhenkilöiden erilaiset tehtävät vaikuttavat itse komppanian johtamiseen. Komppanian organisaatioon lisättävä ammattialiupseerin virka yhdysvaltalaisen first sergeant mallin mukaisesti mahdollistaisi komppanian päällikön tehokkaamman johtamisen sekä komppanian varapäällikön tehtävän kuvan muuttumisen enemmän joukkojen taistelun johtamiseen.