On the Application of Beam on Elastic Foundation Theory to the Analysis of Stiffened Plate Strips

The main objective of this thesis is to show that plate strips subjected to transverse line loads can be analysed by using the beam on elastic foundation (BEF) approach. It is shown that the elastic behaviour of both the centre line section of a semi infinite plate supported along two edges, and the free edge of a cantilever plate strip can be accurately predicted by calculations based on the two parameter BEF theory. The transverse bending stiffness of the plate strip forms the foundation. The foundation modulus is shown, mathematically and physically, to be the zero order term of the fourth order differential equation governing the behaviour of BEF, whereas the torsion rigidity of the plate acts like pre tension in the second order term. Direct equivalence is obtained for harmonic line loading by comparing the differential equations of Levy's method (a simply supported plate) with the BEF method. By equating the second and zero order terms of the semi infinite BEF model for each harmonic component, two parameters are obtained for a simply supported plate of width B: the characteristic length, 1/ λ, and the normalized sum, n, being the effect of axial loading and stiffening resulting from the torsion stiffness, nlin. This procedure gives the following result for the first mode when a uniaxial stress field was assumed (ν = 0): 1/λ = √2B/π and nlin = 1. For constant line loading, which is the superimposition of harmonic components, slightly differing foundation parameters are obtained when the maximum deflection and bending moment values of the theoretical plate, with v = 0, and BEF analysis solutions are equated: 1 /λ= 1.47B/π and nlin. = 0.59 for a simply supported plate; and 1/λ = 0.99B/π and nlin = 0.25 for a fixed plate. The BEF parameters of the plate strip with a free edge are determined based solely on finite element analysis (FEA) results: 1/λ = 1.29B/π and nlin. = 0.65, where B is the double width of the cantilever plate strip. The stress biaxial, v > 0, is shown not to affect the values of the BEF parameters significantly the result of the geometric nonlinearity caused by in plane, axial and biaxial loading is studied theoretically by comparing the differential equations of Levy's method with the BEF approach. The BEF model is generalised to take into account the elastic rotation stiffness of the longitudinal edges. Finally, formulae are presented that take into account the effect of Poisson's ratio, and geometric non linearity, on bending behaviour resulting from axial and transverse inplane loading. It is also shown that the BEF parameters of the semi infinite model are valid for linear elastic analysis of a plate strip of finite length. The BEF model was verified by applying it to the analysis of bending stresses caused by misalignments in a laboratory test panel. In summary, it can be concluded that the advantages of the BEF theory are that it is a simple tool, and that it is accurate enough for specific stress analysis of semi infinite and finite plate bending problems.

Maritime Safety in the Gulf of Finland. Review on Policy Instruments

Suomenlahden lisääntynyt meriliikenne on herättänyt huolta meriliikenteen turvallisuuden tasosta, ja erityisesti Venäjän öljyviennin kasvu on lisännyt öljyonnettomuuden todennäköisyyttä Suomenlahdella. Erilaiset kansainväliset, alueelliset ja kansalliset ohjauskeinot pyrkivät vähentämään merionnettomuuden riskiä ja meriliikenteen muita haittavaikutuksia. Tämä raportti käsittelee meriturvallisuuden yhteiskunnallisia ohjauskeinoja: ohjauskeinoja yleisellä tasolla, meriturvallisuuden keskeisimpiä säätelijöitä, meriturvallisuuden ohjauskeinoja ja meriturvallisuuspolitiikan tulevaisuuden näkymiä, ohjauskeinojen tehokkuutta ja nykyisen meriturvallisuuden ohjausjärjestelmän heikkouksia. Raportti on kirjallisuuskatsaus meriturvallisuuden yhteiskunnalliseen sääntelyn rakenteeseen ja tilaan erityisesti Suomenlahden meriliikenteen näkökulmasta. Raportti on osa tutkimusprojektia ”SAFGOF - Suomenlahden meriliikenteen kasvunäkymät 2007 - 2015 ja kasvun vaikutukset ympäristölle ja kuljetusketjujen toimintaan” ja sen työpakettia 6 ”Keskeisimmät riskit ja yhteiskunnalliset vaikutuskeinot”. Yhteiskunnalliset ohjauskeinot voidaan ryhmitellä hallinnollisiin, taloudellisiin ja tietoohjaukseen perustuviin ohjauskeinoihin. Meriturvallisuuden edistämisessä käytetään kaikkia näitä, mutta hallinnolliset ohjauskeinot ovat tärkeimmässä asemassa. Merenkulun kansainvälisen luonteen vuoksi meriturvallisuuden sääntely tapahtuu pääosin kansainvälisellä tasolla YK:n ja erityisesti Kansainvälisen merenkulkujärjestön (IMO) toimesta. Lisäksi myös Euroopan Unionilla on omaa meriturvallisuuteen liittyvää sääntelyä ja on myös olemassa muita alueellisia meriturvallisuuden edistämiseen liittyviä elimiä kuten HELCOM. Joitakin meriturvallisuuden osa-alueita säädellään myös kansallisella tasolla. Hallinnolliset meriturvallisuuden ohjauskeinot sisältävät aluksen rakenteisiin ja varustukseen, alusten kunnon valvontaan, merimiehiin ja merityön tekemiseen sekä navigointiin liittyviä ohjauskeinoja. Taloudellisiin ohjauskeinoihin kuuluvat esimerkiksi väylä- ja satamamaksut, merivakuutukset, P&I klubit, vastuullisuus- ja korvauskysymykset sekä taloudelliset kannustimet. Taloudellisten ohjauskeinojen käyttö meriturvallisuuden edistämiseen on melko vähäistä verrattuna hallinnollisten ohjauskeinojen käyttöön, mutta niitä voitaisiin varmasti käyttää enemmänkin. Ongelmana taloudellisten ohjauskeinojen käytössä on se, että ne kuuluvat pitkälti kansallisen sääntelyn piiriin, joten alueellisten tai kansainvälisten intressien edistäminen taloudellisilla ohjauskeinoilla voi olla hankalaa. Tieto-ohjaus perustuu toimijoiden vapaaehtoisuuteen ja yleisen tiedotuksen lisäksi tieto-ohjaukseen sisältyy esimerkiksi vapaaehtoinen koulutus, sertifiointi tai meriturvallisuuden edistämiseen tähtäävät palkinnot. Poliittisella tasolla meriliikenteen aiheuttamat turvallisuusriskit Suomenlahdella on otettu vakavasti ja paljon työtä tehdään eri tahoilla riskien minimoimiseksi. Uutta sääntelyä on odotettavissa etenkin liittyen meriliikenteen ympäristövaikutuksiin ja meriliikenteen ohjaukseen kuten meriliikenteen sähköisiin seurantajärjestelmiin. Myös inhimilliseen tekijän merkitykseen meriturvallisuuden kehittämisessä on kiinnitetty lisääntyvissä määrin huomiota, mutta inhimilliseen tekijän osalta tehokkaiden ohjauskeinojen kehittäminen näyttää olevan haasteellista. Yleisimmin lääkkeeksi esitetään koulutuksen kehittämistä. Kirjallisuudessa esitettyjen kriteereiden mukaan tehokkaiden ohjauskeinojen tulisi täyttää seuraavat vaatimukset: 1) tarkoituksenmukaisuus – ohjauskeinojen täytyy olla sopivia asetetun tavoitteen saavuttamiseen, 2) taloudellinen tehokkuus – ohjauskeinon hyödyt vs. kustannukset tulisi olla tasapainossa, 3) hyväksyttävyys – ohjauskeinon täytyy olla hyväksyttävä asianosaisten ja myös laajemman yhteiskunnan näkökulmasta katsottuna, 4) toimeenpano – ohjauskeinon toimeenpanon pitää olla mahdollista ja sen noudattamista täytyy pystyä valvomaan, 5) lateraaliset vaikutukset – hyvällä ohjauskeinolla on positiivisia seurannaisvaikutuksia muutoinkin kuin vain ohjauskeinon ensisijaisten tavoitteiden saavuttaminen, 6) kannustin ja uuden luominen – hyvä ohjauskeino kannustaa kokeilemaan uusia ratkaisuja ja kehittämään toimintaa. Meriturvallisuutta koskevaa sääntelyä on paljon ja yleisesti ottaen merionnettomuuksien lukumäärä on ollut laskeva viime vuosikymmenien aikana. Suuri osa sääntelystä on ollut tehokasta ja parantanut turvallisuuden tasoa maailman merillä. Silti merionnettomuuksia ja muita vaarallisia tapahtumia sattuu edelleen. Nykyistä sääntelyjärjestelmää voidaan kritisoida monen asian suhteen. Kansainvälisen sääntelyn aikaansaaminen ei ole helppoa: prosessi on yleensä hidas ja tuloksena voi olla kompromissien kompromissi. Kansainvälinen sääntely on yleensä reaktiivista eli ongelmakohtiin puututaan vasta kun jokin onnettomuus tapahtuu sen sijaan että se olisi proaktiivista ja pyrkisi puuttumaan ongelmakohtiin jo ennen kuin jotain tapahtuu. IMO:n työskentely perustuu kansallisvaltioiden osallistumiseen ja sääntelyn toimeenpano tapahtuu lippuvaltioiden toimesta. Kansallisvaltiot ajavat IMO:ssa pääasiallisesti omia intressejään ja sääntelyn toimeenpanossa on suuria eroja lippuvaltioiden välillä. IMO:n kyvyttömyys puuttua havaittuihin ongelmiin nopeasti ja ottaa sääntelyssä huomioon paikallisia olosuhteita on johtanut siihen, että esimerkiksi Euroopan Unioni on alkanut itse säädellä meriturvallisuutta ja että on olemassa sellaisia alueellisia erityisjärjestelyjä kuin PSSA (particularly sensitive sea area – erityisen herkkä merialue). Merenkulkualalla toimii monenlaisia yrityksiä: toisaalta yrityksiä, jotka pyrkivät toimimaan turvallisesti ja kehittämään turvallisuutta vielä korkeammalle tasolle, ja toisaalta yrityksiä, jotka toimivat niin halvalla kuin mahdollista, eivät välitä turvallisuusseikoista, ja joilla usein on monimutkaiset ja epämääräiset omistusolosuhteet ja joita vahingon sattuessa on vaikea saada vastuuseen. Ongelma on, että kansainvälisellä merenkulkualalla kaikkien yritysten on toimittava samoilla markkinoilla. Vastuuttomien yritysten toiminnan mahdollistavat laivaajat ja muut alan toimijat, jotka suostuvat tekemään yhteistyötä niiden kanssa. Välinpitämätön suhtautuminen turvallisuuteen johtuu osaksi myös merenkulun vanhoillisesta turvallisuuskulttuurista. Verrattaessa meriturvallisuuden sääntelyjärjestelmää kokonaisuutena tehokkaiden ohjauskeinoihin kriteereihin, voidaan todeta, että monien kriteerien osalta nykyistä järjestelmää voidaan pitää tehokkaana ja onnistuneena. Suurimmat ongelmat lienevät sääntelyn toimeenpanossa ja ohjauskeinojen kustannustehokkuudessa. Lippuvaltioiden toimeenpanoon perustuva järjestelmä ei toimi toivotulla tavalla, josta mukavuuslippujen olemassa olo on selvin merkki. Ohjauskeinojen, sekä yksittäisten ohjauskeinojen että vertailtaessa eri ohjauskeinoja keskenään, kustannustehokkuutta on usein vaikea arvioida, minkä seurauksena ohjauskeinojen kustannustehokkuudesta ei ole saatavissa luotettavaa tietoa ja tuloksena voi olla, että ohjauskeino on käytännössä pienen riskin eliminoimista korkealla kustannuksella. Kansainvälisen tason meriturvallisuus- (ja merenkulku-) politiikan menettelytavoiksi on ehdotettu myös muita vaihtoehtoja kuin nykyinen järjestelmä, esimerkiksi monitasoista tai polysentristä hallintojärjestelmää. Monitasoisella hallintojärjestelmällä tarkoitetaan järjestelmää, jossa keskushallinto on hajautettu sekä vertikaalisesti alueellisille tasoille että horisontaalisesti ei-valtiollisille toimijoille. Polysentrinen hallintojärjestelmä menee vielä askeleen pidemmälle. Polysentrinen hallintojärjestelmä on hallintotapa, jonka puitteissa kaikentyyppiset toimijat, sekä yksityiset että julkiset, voivat osallistua hallintoon, siis esimerkiksi hallitukset, edunvalvontajärjestöt, kaupalliset yritykset jne. Kansainvälinen lainsäädäntö määrittelee yleiset tasot, mutta konkreettiset toimenpiteet voidaan päättää paikallisella tasolla eri toimijoiden välisessä yhteistyössä. Tämän tyyppisissä hallintojärjestelmissä merenkulkualan todellinen, kansainvälinen mutta toisaalta paikallinen, toimintaympäristö tulisi otetuksi paremmin huomioon kuin järjestelmässä, joka perustuu kansallisvaltioiden keskenään yhteistyössä tekemään sääntelyyn. Tällainen muutos meriturvallisuuden hallinnassa vaatisi kuitenkin suurta periaatteellista suunnanmuutosta, jollaisen toteutumista ei voi pitää kovin todennäköisenä ainakaan lyhyellä tähtäimellä.

Minimum number of assessment times to compare chemical control treatments for papaya fruit anthracnose

The chemical treatment evaluation in the field to control post-harvest fruit anthracnose (Colletotrichum gloeosporioides) requires a suitable disease incidence assessment on harvested papaya (Carica papaya) fruits. The minimum number of papaya fruit harvests was determined for valid treatment comparison in field trials for anthracnose chemical control. Repeatability analysis was done using previously published data. The coefficient determination (R²) estimate range, using four methods, and based on means of 12 assessment times, was 92.58 < R² < 94.45%. The number of assessment times required for R²=90% varied from seven to nine. The R² values of 85.1 < R² < 91.3% estimated by ANOVA suggested that any seven successive assessment times were sufficient for treatment comparison.

The effect of the birth hospital and the time of birth on the outcome of Finnish very preterm infants

The purpose of this study was to evaluate the effect of the birth hospital and the time of birth on mortality and the long-term outcome of Finnish very low birth weight (VLBW) or very low gestational age (VLGA) infants. This study included all Finnish VLBW/VLGA infants born at <32 gestational weeks or with a birth weight of ≤1500g, and controls born full-term and healthy. In the first part of the study, the mortality of VLBW/VLGA infants born in 2000–2003 was studied. The second part of the study consisted of a five-year follow-up of VLBW/VLGA infants born in 2001–2002. The study was performed using data from parental questionnaires and several registers. The one-year mortality rate was 11% for live-born VLBW/VLGA infants, 22% for live-born and stillborn VLBW/VLGA infants, and 0% for the controls. In live-born and in all (including stillbirths) VLBW/VLGA infants, the adjusted mortality was lower among those born in level III hospitals compared with level II hospitals. Mortality rates of live-born VLBW/VLGA infants differed according to the university hospital district where the birth hospital was located, but there were no differences in mortality between the districts when stillborn infants were included. There was a trend towards lower mortality rates in VLBW/VLGA infants born during office hours compared with those born outside office hours (night time, weekends, and public holidays). When stillborn infants were included, this difference according to the time of birth was significant. Among five-year-old VLBW/VLGA children, morbidity, use of health care resources, and problems in behaviour and development were more common in comparison with the controls. The health-related quality of life of the surviving VLBW/VLGA children was good but, statistically, it was significantly lower than among the controls. The median and the mean number of quality-adjusted life-years were 4.6 and 3.6 out of a maximum five years for all VLBW/VLGA children. For the controls, the median was 4.8 and the mean was 4.9. Morbidity rates, the use of health care resources, and the mean quality-adjusted life-years differed for VLBW/VLGA children according to the university hospital district of birth. However, the time of birth, the birth hospital level or university hospital district were not associated with the health-related quality of life, nor with behavioural and developmental scores of the survivors at the age of five years. In conclusion, the decreased mortality in level III hospitals was not gained at the expense of long-term problems. The results indicate that VLBW/VLGA deliveries should be centralized to level III hospitals and the regional differences in the treatment practices should further be clarified. A long-term follow-up on the outcome of VLBW/VLGA infants is important in order to recognize the critical periods of care and to optimise the care. In the future, quality-adjusted life-years can be used as a uniform measure for comparing the effectiveness of care between VLBW/VLGA infants and different patient groups

Effect of ethephon on hardening of Pachystroma longifolium seedlings

Immediately after planting, tree seedlings face adverse environmental and biotic stresses that must be overcome to ensure survival and to yield a desirable growth. Hardening practices in the nursery may help improve seedling stress resistance through reduction of aboveground plant tissues and increased root volume and biomass. We conducted an assay to quantify changes in the morphogenesis following application of ethephon on seedlings of Pachystroma longifolium (Ness) I. M. Johnst.during hardening. The results showed no effect of the ethephon treatments on the number of leaves but a reduction of up to 50% in seedling height increment, and an increase in stem diameter increment of up to 44% with the 600 mg L-1 ethephon treatment, which consequently altered seedling Dickson Quality Index. Our results indicate that ethephon may help to promote desired morphological changes that occur during seedling hardening in nurseries.

The influence of the season of the year and of dilution on the development of swine manure and wood shaves co-composting

The objective of this research was to study the influence of factors related to the proper management of pig manure (lower dilution) and the season of the year in the progress of the co-composting of pig manure with wood shavings and in the final quality of the compost resulting from the treatments. In the first experiment, two types of swine manure were used: a diluted one (2% Dry Matter - DM), typical from the management usually used in Brazil, and a more concentrated one (6% DM). The manures were incorporated into the wood shavings (6L:1kg) over the course of four weeks. The development of composting was accompanied by monitoring of temperatures inside the piles and the emission of CO2 and CH4 gases during 65 days, including the period of incorporation. The results showed that the diluted manure does not provide the minimum conditions for starting the process. After the incorporation period, any biomass heating was observed and neither the aerobic or anaerobic respiration of the microorganisms, resulting in a compost with low quality. In the second experiment, which evaluated composting in winter and summer during 85 days, it was found that the heat exchange with the environment influences the temperature generated within the piles. The lower temperatures significantly reduced the methanogenesis on the biomass.

Influence of irrigation on wheat crop

The use of irrigation has been increased significantly in wheat crops in Brazil. This study aims to evaluate the effect of irrigation on the productivity, on flour technological quality and on the wheat root system. In a field experiment conducted at IAPAR, in Londrina -state of Paraná (PR), Brazil, the IPR 118 cultivar was grown under sprinkler irrigation (Irrigated Treatment) and without irrigation (Non-irrigated Treatment). The productivity was determined by harvesting three samples of 25 m² per treatment. The same samples were used to evaluate the flour technological quality, considering, among other parameters, gluten strength (W). The evaluation of the root system was performed after the harvest, considering a profile of 0 to 45 cm of soil depth, and sampling eight plants per treatment. The profile wall method was used to determine the roots number (RN) and the monolith method to determine the root dry mass (RDM). Irrigation increased wheat productivity in three times, while W was reduced in the flour. Nevertheless, the value of W found in the Irrigated Treatment (249 10-4 J) was sufficient to keep wheat classification as bread type, the same as IPR 118 cultivar is classified. The measured values of RN and RDM were similar or higher for the Non-irrigated Treatment.

Multibody Simulation Model of the Roller Test Rig

Multibody simulation model of the roller test rig is presented in this work. The roller test rig consists of a paper machine’s tube roll supported with a hard bearing type balancing machine. The simulation model includes non-idealities that are measured from the physical structure. These non-idealities are the shell thickness variation of the roll and roundness errors of the shafts of the roll. These kinds of non-idealities are harmful since they can cause subharmonic resonances of the rotor system. In this case, the natural vibration mode of the rotor is excited when the rotation speed is a fraction of the natural frequency of the system. With the simulation model, the half critical resonance is studied in detail and a sensitivity analysis is performed by simulating several analyses with slightly different input parameters. The model is verified by comparing the simulation results with those obtained by measuring the real structure. Comparison shows that good accuracy is achieved, since equivalent responses are achieved within the error limit of the input parameters.

Induction of mutations for earliness in the soybean cultivar Paraná

Mutation induction breeding through gamma ray seed treatment (22 krad) was used to obtain earliness in the soybean cultivar Paraná. Plants flowering earlier than Paraná were selected at the M3 generation. Eight mutant lines were isolated by further selections through several generations and tested in four yield trials carried out in 85/86 (Piracicaba) and 86/87 (Piracicaba, Sertãozinho and Assis) in São Paulo State. The following data were taken in these trials: number of days to flowering, yield, total plant height and height to pod insertion, flower color, pod pubescence and seed and plant growth type. Two of the mutants are of agronomic interest because they were, on average, seven to 10 days earlier in maturity than the control in all trials. Except for shorter plant height, the other agronomic characteristics remained unaltered.

Effects of caffeine on time to exhaustion in exercise performed below and above the anaerobic threshold

Controversy still exists concerning the potential ergogenic benefit of caffeine (CAF) for exercise performance. The purpose of this study was to compare the effects of CAF ingestion on endurance performance during exercise on a bicycle ergometer at two different intensities, i.e., approximately 10% below and 10% above the anaerobic threshold (AT). Eight untrained males, non-regular consumers of CAF, participated in this study. AT, defined as the intensity (watts) corresponding to a lactate concentration of 4 mM, was determined during an incremental exercise test from rest to exhaustion on an electrically braked cycle ergometer. On the basis of these measurements, the subjects were asked to cycle until exhaustion at two different intensities, i.e., approximately 10% below and 10% above AT. Each intensity was performed twice in a double-blind randomized order by ingesting either CAF (5 mg/kg) or a placebo (PLA) 60 min prior to the test. Venous blood was analyzed for free fatty acid, glucose, and lactate, before, during, and immediately after exercise. Rating of perceived exertion and time to exhaustion were also measured during each trial. There were no differences in free fatty acids or lactate levels between CAF and PLA during and immediately after exercise for either intensity. Immediately after exercise glucose increased in the CAF trial at both intensities. Rating of perceived exertion was significantly lower (CAF = 14.1 ± 2.5 vs PLA = 16.6 ± 2.4) and time to exhaustion was significantly higher (CAF = 46.54 ± 8.05 min vs PLA = 32.42 ± 14.81 min) during exercise below AT with CAF. However, there was no effect of CAF treatment on rating of perceived exertion (CAF = 18.0 ± 2.7 vs PLA = 17.6 ± 2.3) and time to exhaustion (CAF = 18.45 ± 7.28 min vs PLA = 19.17 ± 4.37 min) during exercise above AT. We conclude that in untrained subjects caffeine can improve endurance performance during prolonged exercise performed below AT and that the decrease of perceived exertion can be involved in this process

Study of the effects of ß-myrcene on rat fertility and general reproductive performance

ß-Myrcene (MYR) is a monoterpene found in the oils of a variety of aromatic plants including lemongrass, verbena, hop, bay, and others. MYR and essential oils containing this terpenoid compound are used in cosmetics, household products, and as flavoring food additives. This study was undertaken to investigate the effects of MYR on fertility and general reproductive performance in the rat. MYR (0, 100, 300 and 500 mg/kg) in peanut oil was given by gavage to male Wistar rats (15 per dose group) for 91 days prior to mating and during the mating period, as well as to females (45 per dose group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal day 21. On day 21 of pregnancy one-third of the females of each group were submitted to cesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed, and cleared and stained with Alizarin Red S for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal day 21. Mortality, weight gain and physical signs of postnatal development were evaluated. Except for an increase in liver and kidney weights, no other sign of toxicity was noted in male and female rats exposed to MYR. MYR did not affect the mating index (proportion of females impregnated by males) or the pregnancy index (ratio of pregnant to sperm-positive females). No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. Only at the highest dose tested (500 mg/kg) did MYR induce an increase in the resorption rate and a higher frequency of fetal skeleton anomalies. No adverse effect of MYR on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were slightly delayed in the exposed offspring. On the basis of the data presented in this paper the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance can be set at 300 mg of ß-myrcene/kg body weight by the oral route.

Effect of thyroparathyroidectomy on urinary acidification in diabetic rats

In previous studies we have shown stimulation of renal acid excretion in the proximal tubules of rats with diabetes of short duration, with no important alterations in glomerular hemodynamics; on the other hand, in thyroparathyroidectomized rats (TPTX model), a significant decrease in renal acid excretion, glomerular filtration rate (GFR) and renal plasma flow (RPF) was detected. Since important changes in the parathyroid hormone-vitamin D-Ca axis are observed in the diabetic state, the present study was undertaken to investigate the renal repercussions of thyroparathyroidectomy in rats previously made diabetic by streptozotocin (45 mg/kg). Four to 6 days after the induction of diabetes (DM), a group of rats were thyroparathyroidectomized (DM + TPTX). Renal functional parameters were evaluated by measuring the inulin and sodium para-aminohippurate clearance on the tenth day. The decrease in the GFR and RPF observed in TPTX was not reversed by diabetes since the same alterations were observed in DM + TPTX. Net acid (NA) excretion was unchanged in DM (6.19 ± 0.54), decreased in TPTX (3.76 ± 0.25) and returned to normal levels in DM + TPTX (5.54 ± 0.72) when compared to the control group (6.34 ± 0.14 µmol min-1 kg-1). The results suggest that PTH plays an important vasodilator role regarding glomerular hemodynamics, since in its absence the impairment in GFR and RPF was not reversed by the diabetic state. However, with respect to acid excretion, the presence of diabetes was able to overcome the negative stimulus represented by TPTX.

Probable effect of photoperiod on seasonal variation in the nuclear volume of the adrenal cortex of viscacha (Lagostomus maximus maximus)

The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are arranged in a tube-shaped structure. The fasciculata zone has large cells with central nuclei and clearly visible nucleoli and with a vacuolar cytoplasm. In the reticularis zone there are two of types of cells, one with a nucleus of fine chromatin and a clearly visible nucleolus and the other with nuclear pycnosis. Morphometric analysis showed maximum nuclear volumes during the February-March period with values of 133 ± 7.3 µm3 for the glomerulosa, 286.4 ± 14.72 µm3 for the fasciculata, and 126.3 ± 9.49 µm3 for the reticularis. Minimum nuclear volumes were observed in August with values of 88.24 ± 9.9 µm3 for the glomerulosa, 163.7 ± 7.78 µm3 for the fasciculata and 64.58 ± 4.53 µm3 for the reticularis. The short winter photoperiod to which viscacha is subjected could inhibit the adrenal cortex through a melatonin increase which reduces the nuclear volume as well as the cellular activity.

Effects of diazepam on Mycobacterium bovis-induced infection in hamsters

The in utero exposure of hamsters to low doses of diazepam results in impaired host defense against Mycobacterium bovis during adulthood. Delayed developmental immunotoxicity, however, represents a specific situation that might not be general. The present experiment was undertaken to investigate the effects of diazepam on hamster resistance to M. bovis using adult animals. The effects of diazepam treatment on serum cortisol levels were also studied. Adult hamsters (N = 10 for each group) were treated with diazepam (E1 = 1.0, E2 = 2.0 or E3 = 3.0 mg kg-1 day-1 subcutaneously) or with control solution (C) for 30 days. Seven days after the beginning of the treatment, the animals received identical inoculum concentrations of M. bovis. Hamsters treated with the higher (2.0 and 3.0 mg kg-1 day-1) doses of diazepam exhibited: 1) increased granuloma areas in the liver (C = 1.81 ± 1.39, E2 = 10.29 ± 4.64 and E3 = 15.80 ± 4.82) and lung (C = 0.54 ± 0.55, E2 = 6.28 ± 3.85 and E3 = 6.31 ± 3.56) and 2) increased scores of M. bovis colony-forming units isolated from liver (C = 2.0, E2 = 3.0 and E3 = 3.5), lung (C = 1.0, E2 = 3.0 and E3 = 3.5) and spleen (C = 1.0, E2 = 2.5 and E3 = 4.0). These effects were dose dependent, and were not detected or were less severe in animals treated with the lowest (1.0 mg/kg) dose of diazepam as well as in those of the control group. Furthermore, diazepam treatment (3.0 mg kg-1 day-1 for 30 days) increased (E3 = 71.32 ± 2.99; N = 10) the serum levels of cortisol compared to control hamsters (C = 22.61 ± 2.75; N = 10). The present data, that demonstrate an impaired defense against M. bovis in adult hamsters treated with diazepam, were tentatively explained on the basis of a direct and/or indirect action of diazepam on the cytokine network. The effects may be related to stimulation of peripheral benzodiazepine receptor binding sites (PBR) by macrophages and/or lymphocytes, or they may be mediated by PBR stimulation of the adrenals.

Protective effect of policosanol on atherosclerotic lesions in rabbits with exogenous hypercholesterolemia

Policosanol is a mixture of higher aliphatic alcohols purified from sugar cane wax, with cholesterol-lowering effects demonstrable in experimental models and in patients with type II hypercholesterolemia. The protective effects of policosanol on atherosclerotic lesions experimentally induced by lipofundin in rabbits and rats and spontaneously developed in stumptail monkeys have been described. The present study was conducted to determine whether policosanol administered orally to rabbits with exogenous hypercholesterolemia also protects against the development of atherosclerotic lesions. Male New Zealand rabbits weighing 1.5 to 2 kg were randomly divided into three experimental groups which received 25 or 200 mg/kg policosanol (N = 7) orally for 60 days with acacia gum as vehicle or acacia gum alone (control group, N = 9). All animals received a cholesterol-rich diet (0.5%) during the entire period. Control animals developed marked hypercholesterolemia, macroscopic lesions and arterial intimal thickening. Intima thickness was significantly less (32.5 ± 7 and 25.4 ± 4 µm) in hypercholesterolemic rabbits treated with policosanol than in controls (57.6 ± 9 µm). In most policosanol-treated animals, atherosclerotic lesions were not present, and in others, thickness of fatty streaks had less foam cell layers than in controls. We conclude that policosanol has a protective effect on the atherosclerotic lesions occurring in this experimental model.