Structural changes to the brood pouch of male pregnant seahorses (Hippocampus abdominalis) facilitate exchange between father and embryos

INTRODUCTION

Embryonic growth and development require efficient respiratory gas exchange. Internal incubation of developing young thus presents a significant physiological challenge, because respiratory gas diffusion to embryos is impeded by the additional barrier of parental tissue between the embryo and the environment. Therefore, live-bearing species exhibit a variety of adaptations facilitating respiratory gas exchange between the parent (usually the mother) and embryos. Syngnathid fishes are the only vertebrates to exhibit male pregnancy, allowing comparative studies of the biology and evolution of internal incubation of embryos, independent of the female reproductive tract. Here, we examine the fleshy, sealed, seahorse brood pouch, and provide the first quantification of structural changes to this gestational organ across pregnancy.

METHODS

We used histological analysis and morphometrics to quantify the surface area for exchange across the brood pouch epithelium, and the structure of the vascular bed of the brood pouch.

RESULTS

We show dramatic remodelling of gestational tissues as pregnancy progresses, including an increase in tortuosity of the gestational epithelium, an increase in capillary density, and a decrease in diffusion distance between capillaries and the pouch lumen.

DISCUSSION

These changes produce an increased surface area and expansion of the vascular bed of the placenta that likely facilitates respiratory gas exchange. These changes mirror the remodelling of gestational tissue in viviparous amniotes and elasmobranchs, and provide further evidence of the convergence of adaptations to support pregnancy in live-bearing animals.

Conservation implications of turtle declines in Australia's Murray River system

Conservation requires rapid action to be effective, which is often difficult because of funding limitations, political constraints, and limited data. Turtles are among the world’s most endangered vertebrate taxa, with almost half of 356 species threatened with extinction. In Australia’s Murray River, nest predation by invasive foxes (Vulpes vulpes) was predicted to drive turtle declines in the 1980s. We assessed populations of the broad-shelled turtle (Chelodina expansa), eastern long-necked turtle (C. longicollis), and Murray River turtle (Emydura macquarii) in the Murray River and some of its associated waterways. Our results suggest that the predicted decline is occurring. All three species are rare in the lower Murray River region, and were undetected in many locations in South Australia. Moreover, E. macquarii had considerable population aging almost everywhere, possibly due to comprehensive nest destruction by foxes. Chelodina longicollis also had population aging at some sites. Sustained low recruitment has potential to lead to collapses as turtles age, which is particularly worrying because it was predicted over 30 years ago and may have already occurred in South Australia. Our results show that turtle declines were not mitigated since that prediction. If the crash continues, a vertebrate guild responsible for considerable nutrient cycling in the aquatic ecosystem will disappear. Our results highlight a worst-case outcome when species declines are predicted, but insufficiently mitigated.

The biomechanical, chemical and physiological adaptations of the eggs of two Australian megapodes to their nesting strategies and their implications for extinct titanosaur dinosaurs

Megapodes are galliform birds endemic to Australasia and unusual among modern birds in that they bury their eggs for incubation in diverse substrates and using various strategies. Alectura lathami and Leipoa ocellata are Australian megapodes that build and nest in mounds of soil and organic matter. Such unusual nesting behaviours have resulted in particular evolutionary adaptations of their eggs and eggshells. We used a combination of scanning electron microscopy, including electron backscatter diffraction and energy-dispersive X-ray spectroscopy, to determine the fine structure of the eggshells and micro-CT scanning to map the structure of pores. We discovered that the surface of the eggshell of A. lathami displays nodes similar to those of extinct titanosaur dinosaurs from Transylvania and Auca Mahuevo egg layer #4. We propose that this pronounced nodular ornamentation is an adaptation to an environment rich in organic acids from their nest mound, protecting the egg surface from chemical etching and leaving the eggshell thickness intact. By contrast, L. ocellata nests in mounds of sand with less organic matter in semiarid environments and has eggshells with weakly defined nodes, like those of extinct titanosaurs from AM L#3 that also lived in a semiarid environment. We suggest the internode spaces in both megapode and titanosaur species act as funnels, which concentrate the condensed water vapour between the nodes. This water funnelling in megapodes through the layer of calcium phosphate reduces the likelihood of bacterial infection by creating a barrier to microbial invasion. In addition, the accessory layer of both species possesses sulphur, which reinforces the calcium phosphate barrier to bacterial and fungal contamination. Like titanosaurs, pores through the eggshell are Y-shaped in both species, but A. lathami displays unique mid-shell connections tangential to the eggshell surface and that connect some adjacent pores, like the eggshells of titanosaur of AM L#4 and Transylvania. The function of these interconnections is not known, but likely helps the diffusion of gases in eggs buried in environments where occlusion of pores is possible.

Field metabolic rate and water turnover of red kangaroos and sheep in an arid rangeland: an empirically derived dry-sheep-equivalent for kangaroos

Sustainable management of pastures requires detailed knowledge of total grazing pressure, but this information is critically lacking in Australia’s rangelands where livestock co-occur with large herbivorous marsupials. We present the first comparative measure of the field metabolic rate (an index of food requirement) of Australia’s largest marsupial, the red kangaroo (Macropus rufus), with that of domestic sheep (Ovis aries; merino breed). We tested the assumption that the grazing pressure of red kangaroos is equivalent to 0.7 sheep, and show this to be a two-fold overestimation of their contribution to total grazing. Moreover, kangaroos had extraordinarily lower rates of water turnover, being only 13% that of sheep. Consequently, our data support arguments that the removal of kangaroos may not markedly improve rangeland capacity for domestic stock. Furthermore, given the low resource requirements of kangaroos, their use in consumptive and non-consumptive enterprises can provide additional benefits for Australia’s rangelands than may occur under traditional rangeland practices.

Low Cost of Locomotion in Lizards That Are Active at Low Temperatures

The nocturnality hypothesis of K. Autumn and coworkers states that nocturnal geckos have evolved a low energetic cost of locomotion (C(min)). A low C(min) increases maximum aerobic speed and partially offsets the decrease in maximum oxygen consumption caused by activity at low nocturnal temperatures. We tested whether a low C(min) is unique to nocturnal geckos or represents a more general pattern of convergent evolution among lizards that enables nocturnality and/or cold-temperature activity. We measured C(min) in four carefully selected lizard species from New Zealand (two nocturnal and two diurnal; n=5-9 individuals per species), including a nocturnal and diurnal gecko (a low C(min) is a gecko trait and is not related to nocturnality), a nocturnal skink (a low C(min) is related to being nocturnal), and a diurnal skink active at low temperatures (a low C(min) is related to being active at low body temperatures). The C(min) values of the four species measured in this study (range=0.21-2.00 mL O(2) g(-1) km(-1)) are lower than those of diurnal lizards from elsewhere, and the values are within or below the 95% confidence limits previously published for nocturnal geckos. A low C(min) increases the range of locomotor speeds possible at low temperatures and provides an advantage for lizards active at these temperatures. We accepted the hypothesis that nocturnal lizards in general have a low C(min) and provide evidence for a low C(min) in lizards from cool-temperate environments. The low C(min) in lizards living at high latitudes may enable extension of their latitudinal range into otherwise thermally suboptimal habitats.

Conditioning reduces metabolic rate and time to steady-state in the lizard Naultinus manukanus (Reptilia: Gekkonidae)

The rate of oxygen consumption (VO2) is commonly used as a measure of whole organism metabolic rate, but requires the animal to be motionless and at rest. Few studies have measured whether animals that appear motionless are truly at rest, or whether being in a novel environment elevates metabolic rate. We investigated whether conditioning of the gecko Naultinus manukanus to experimental procedures influenced the VO2 and probability of achieving a constant rate of oxygen consumption. Metabolic rate was measured at 24 degrees C in 22 individuals until a steady-state was achieved, or for 80 min if no steady-state was reached, once a day on 5 consecutive days (five trials). Geckos in the first trial, when compared with subsequent trials, had a significantly higher mass-adjusted VO2 (0.89+/-0.06 vs. 0.67+/-0.05 ml O2 h(-1), respectively), and time to reach a steady-state VO2 (66+/-8 vs. 47+/-3 min, respectively), as well as a significantly lower probability of reaching a steady-state VO2 (24% vs. 74%, respectively). We conclude that there may be hidden inaccuracies in studies that do not condition animals and that at least one conditioning trial should be used to obtain a metabolic rate at rest for small lizards.

Turtles ( Chelodina longicollis ) regulate muscle metabolic enzyme activity in response to seasonal variation in body temperature

Fluctuations in the thermal environment may elicit different responses in animals: migration to climatically different areas, regulation of body temperature, modification of biochemical reaction rates, or assuming a state of dormancy. Many ectothermic reptiles are active over a range of body temperatures that vary seasonally. Here we test the hypothesis that metabolic enzyme activity acclimatises seasonally in freshwater turtles (Chelodina longicollis) in addition to, or instead of, behavioural regulation of body temperatures. We measured body temperatures in free-ranging turtles (n = 3) by radiotelemetry, and we assayed phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome c oxidase (CCO) activities in early autumn (March, n = 10 turtles), late autumn (May, n = 7) and mid-winter (July, n = 7) over a range of assay temperatures (10 degrees C, 15 degrees C, 20 degrees C, 25 degrees C). Body temperatures were either not different from, or higher than expected from a theoretical null-distribution of a randomly moving animal. Field body temperatures at any season were lower, however, than expected from animals that maximised their sun exposure. Turtles maintained constant PFK, LDH and CCO activities in different months, despite body temperature differences of nearly 13.0 degrees C between March (average daily body temperature = 24.4 degrees C) and July (average = 11.4 degrees C). CS activity did not vary between March and May (average daily body temperature = 20.2 degrees C), but it decreased in July. Thus C. longicollis use a combination of behavioural thermoregulation and biochemical acclimatisation in response to seasonally changing thermal conditions. Ectothermic reptiles were often thought not to acclimatise biochemically, and our results show that behavioural attainment of a preferred body temperature is not mandatory for activity or physiological performance in turtles.

Changes in oviductal morphology of the skink,Lampropholis guichenoti, associated with egg production

We describe changes in the morphology of the oviductal epithelium of an oviparous skink, Lampropholis guichenoti, during the course of egg production and oviposition: to characterize the luminal epithelial changes; to provide a baseline for understanding uterine changes in viviparous species; and to establish whether the plasma membrane transformation of uterine epithelial cells is indeed a feature restricted to viviparous species. Oviducts from vitellogenic, gravid, and postgravid females were observed using scanning electron microscopy. Cellular characteristics of the oviductal epithelium previously used to determine the plasma membrane transformation were assessed morphologically. Three anatomically different areas were defined within the oviduct, but no plasma membrane transformation was observed in the oviparous skink, suggesting that this is a phenomenon particular to viviparity.

Distribution of lipids from the yolk to the tissues during development of the water python (Liasis fuscus)

Energy metabolism during embryonic development of snakes differs in several respects from the patterns displayed by other reptiles. There are, however, no previous reports describing the main energy source for development, the yolk lipids, in snake eggs. There is also no information on the distribution of yolk fatty acids to the tissues during snake development. In eggs of the water python ( Liasis fuscus), we report that triacylglycerol, phospholipid, cholesteryl ester and free cholesterol, respectively, form 70.3%, 14.1%, 5.7% and 2.1% of the total lipid. The main polyunsaturate of the yolk lipid classes is 18:2n-6. The yolk phospholipid contains 20:4n-6 and 22:6n-3 at 13.0% and 3.6% (w/w), respectively. Approximately 10% and 30% of the initial egg lipids are respectively recovered in the residual yolk and the fat body of the hatchling. A major function of yolk lipid is, therefore, to provision the neonate with large energy reserves. The proportion of 22:6n-3 in brain phospholipid of the hatchling is 11.1% (w/w): this represents only 0.24% of the amount of 22:6n-3 originally present in the egg. This also contrasts with values for free-living avian species where the proportion of DHA in neonatal brain phospholipid is 16-19%. In the liver of the newly hatched python, triacylglycerol, phospholipid and cholesteryl ester, respectively, form 68.2%, 7.7% and 14.3% of total lipid. This contrasts with embryos of birds where cholesteryl ester forms up to 80% of total liver lipid and suggests that the mechanism of lipid transfer in the water python embryo differs in some respects from the avian situation.

Epidermal differentiation during ontogeny and after hatching in the snake Liasis fuscus (Pythonidae, Serpentes, Reptilia), with emphasis on the formation of the shedding complex

Differentiation and localization of keratin in the epidermis during embryonic development and up to 3 months posthatching in the Australian water python, Liasis fuscus, was studied by ultrastructural and immunocytochemical methods. Scales arise from dome-like folds in the skin that produce tightly imbricating scales. The dermis of these scales is completely differentiated before any epidermal differentiation begins, with a loose dermis made of mesenchymal cells beneath the differentiating outer scale surface. At this stage (33) the embryo is still unpigmented and two layers of suprabasal cells contain abundant glycogen. At Stage 34 (beginning of pigmentation) the first layers of cells beneath the bilayered periderm (presumptive clear and oberhautchen layers) have not yet formed a shedding complex, within which prehatching shedding takes place. At Stage 35 the shedding complex, consisting of the clear and oberhautchen layers, is discernible. The clear layer contains a fine fibrous network that faces the underlying oberhautchen, where the spinulae initially contain a core of fibrous material and small beta-keratin packets. Differentiation continues at Stage 36 when the beta-layer forms and beta-keratin packets are deposited both on the fibrous core of the oberhautchen and within beta-cells. Mesos cells are produced from the germinal layer but remain undifferentiated. At Stage 37, before hatching, the beta-layer is compact, the mesos layer contains mesos granules, and cells of the alpha-layer are present but are not yet keratinized. They are still only partially differentiated a few hours after hatching, when a new shedding complex is forming underneath. Using antibodies against chick scale beta-keratin resolved at high magnification with immunofluorescent or immunogold conjugates, we offer the first molecular confirmation that in snakes only the oberhautchen component of the shedding complex and the underlying beta cells contain beta-keratin. Initially, there is little immunoreactivity in the small beta-packets of the oberhautchen, but it increases after fusion with the underlying cells to produce the syncytial beta layer. The beta-keratin packets coalesce with the tonofilaments, including those attached to desmosomes, which rapidly disappear in both oberhautchen and beta-cells as differentiation progresses. The labeling is low to absent in forming mesos-cells beneath the beta-layer. This study further supports the hypothesis that the shedding complex in lepidosaurian reptiles evolved after there was a segregation between alpha-keratogenic cells from beta-keratogenic cells during epidermal renewal.

The effects of toothpastes on the residual microbial contamination of toothbrushes

BACKGROUND

Contaminated toothbrushes have been shown to harbor and transmit viruses and bacteria. The authors conducted a study to evaluate the effect of a triclosan-containing toothpaste on the residual anaerobic microbial contamination of toothbrushes.

METHODS

Twenty patients who had Type III or Type IV periodontitis participated in this study. One side of each of their mouths served as a control (no toothpaste). The teeth on the other side were brushed with a regular toothpaste or a triclosan-containing toothpaste. After the toothbrushes were allowed to dry in air for four hours, the authors placed the toothbrush heads in solution, dislodged the microbes from the brushes by vortexing and plated them in culture dishes. The authors anerobically incubated the culture dishes and determined the presence or absence of Prevotella species or Ps; Porphyromonas gingivalis, or Pg; and Actinobacillus actinomycetemcomitans, or Aa.

RESULTS

The authors detected Aa and Pg on the control toothbrushes more frequently than they did Ps. This variation in isolation frequency was statistically significant by chi 2 analysis (P < .001). The authors compared the isolation frequency of the three test organisms between the control and regular-toothpaste groups, between the control and triclosan-containing--toothpaste groups, and between the triclosan-containing--toothpaste and regular-toothpaste groups. They found no significant intergroup differences in the isolation frequencies after using chi 2 analysis.

CONCLUSIONS

Toothpaste use reduced the residual microbial contamination for two of three test organisms, but the lower isolation frequencies were not statistically significant. Further study in this area is indicated.

CLINICAL IMPLICATIONS

Dental professionals should advise patients who have systemic, localized or oral inflammatory diseases to disinfect or frequently replace their toothbrushes.

Sex determination. Viviparous lizard selects sex of embryos

No one suspected that temperature-dependent sex determination (TSD), whereby the sex of embryos depends on the temperature at which they develop, might occur in viviparous (live-bearing) reptiles, because thermoregulation in the mother results in relatively stable, raised gestation temperatures. But here we show that developing embryos of the actively thermoregulating viviparous skink Eulamprus tympanum are subject to TSD, offering the mother the chance to select the sex of her offspring and a mechanism to help to balance sex ratios in wild populations.

Utilisation of nutrients by embryos of the enigmatic Australian viviparous skink Niveoscincus coventryi

The Eugongylus species group of Australian lygosomine skinks provides an unparalleled opportunity to study the evolution of placentotrophy. Viviparity and placentotrophy have evolved in two lineages, currently recognised as the genera Pseudemoia and Niveoscincus. The genus Niveoscincus is important because it is the only lineage of squamates in which variation in placental morphology and in the pattern of embryonic nutrition is known. Niveoscincus coventryi has the least complex placental morphology among species currently assigned to the genus. We quantified the net uptake of nutrients across the placenta of N. coventryi for comparison with other species in the genus and with other viviparous and oviparous lizards. The pattern of embryonic nutrition of N. coventryi is similar to other viviparous lizards with simple placentae in that there is no net uptake of dry matter during development but there is a net uptake of water, calcium, potassium, and sodium. There is no net uptake of lipid, nitrogen (an index of protein), or magnesium. We conclude that N. coventryi is predominantly lecithotrophic. Further, if N. coventryi is the sister taxon to Tasmanian Niveoscincus, then the distribution of patterns of embryonic nutrition among members of this clade suggests that the evolution of placentotrophy occurred during radiation of this lineage in Tasmania.

Nutrient uptake by embryos of the Australian viviparous lizard Eulamprus tympanum

Eulamprus tympanum is a high-altitude viviparous lizard that was probably used to help define a Type I chorioallantoic placenta. In this article, we (1) describe the net transport of nutrients across the placenta of E. tympanum, and (2) compare placental uptake in E. tympanum with a previous study of Eulamprus quoyii, which occurs in warmer environments, to assess the potential importance of thermal regime on placentotrophy. Freshly ovulated eggs are 387.3+/-19.7 mg. There is a significant net uptake of water and a net loss of dry matter during development, so the dry neonate is only 84% the size of the dry egg. There is no significant change in the total ash or nitrogen in eggs during embryonic development, with the entire loss of dry matter being lipid. Almost the entire loss of lipid occurs in the triacylglycerol fraction, with no net change in phospholipids. A net increase in total cholesterol suggests that cholesterol is synthesised by the developing embryo. The lipid profile of eggs of E. tympanum reflects that of other species with simple placentae in having a relatively high proportion of triacylglycerol and little cholesterol. The fatty acid composition of eggs reflects that expected in the diet of E. tympanum. There is a preservation and some synthesis of arachidonic (20:4n-6) and docosahexaenoic (22:6n-3) acids in the phospholipid fraction during embryonic development. Despite there being no net uptake of ash, there is a net increase in calcium, potassium, sodium, and magnesium in the neonate compared with the egg. We conclude that E. tympanum, like E. quoyii, is predominantly lecithotrophic with little, if any, uptake of organic molecules but with significant uptake of some inorganic ions and water. In addition, there is no difference in placentotrophy correlated with differences in the environments inhabited by each species.

Utilisation of lipids, protein, ions and energy during embryonic development of Australian oviparous skinks in the genus Lampropholis

The contents of eggs and neonates of the Australian skinks, Lampropholis guichenoti and L. delicata, are described and compared to allow interpretation of nutrient utilisation by the developing embryo. Even though the females are the same size, L. guichenoti lay smaller clutches of larger eggs (egg contents=41.6+/-1.2 mg dry mass) than L. delicata (26.6+/-2.8 mg). The energy density is the same for eggs (30.5+/-0.9 J/g ash-free dry mass for L. guichenoti and 29.9+/-1.1 J/mg for L. delicata) and neonates (22.5+/-1.3 J/mg for L. guichenoti and 23.5+/-0.4 J/mg for L. delicata) between species. The amount of nitrogen (protein) in neonates is only slightly lower than that in eggs, whereas there is a large and significant decline in total lipids. Thus, like some other skinks, protein is a source of metabolic energy during embryogenesis, although not as important as lipid. Triacylglycerol is the major lipid component of the eggs (80% of total lipid), with phospholipid forming only approximately 10% of the total lipid. The fatty acid profile of the phospholipid is distinguished by a high proportion of arachidonic acid (8%), a significant proportion of eicosapentaenoic acid (2-4%) and a relatively low proportion of docosahexaenoic acid (2-3%) compared to chickens. Eggs of both species have remarkably low concentrations of free cholesterol compared to other amniote eggs (0.7% for L. guichenoti and 1.3% for L. delicata). The loss of lipid during embryonic development is almost entirely due to the selective utilisation of yolk triacylglycerol, presumably for energy. By contrast, the amount of phospholipid recovered from the neonates was the same as that originally in the eggs. Moreover, significantly more total cholesterol was present in the neonates than in the eggs, suggesting that biosynthesis of additional cholesterol occurred during development. The phospholipids of the neonates contain higher proportions of arachidonic (11-12%) and docosahexaenoic (8%) acids than the phospholipids of the eggs. Eicosapentaenoic acid is less prevalent in phospholipids in neonates than in eggs. Neonates of both species contain significantly more calcium than the fresh egg contents (L. guichenoti, eggs 0.303+/-0.051 mg, neonates 0.641+/-0.047 mg; L. delicata, eggs 0.187+/-0.013 mg, neonates 0.435+/-0.033 mg), presumably as a result of resorption of calcium from the eggshell. Interestingly, there is also significantly more sodium in neonates than in the contents of fresh eggs (L. guichenoti, eggs 0.094+/-0.010 mg, neonates 0.184+/-0.011 mg; L. delicata, eggs 0.084+/-0.011 mg, neonates 0.151+/-0.010 mg). There is no significant difference in the content of potassium and magnesium in eggs and neonates of either species. Although the fresh eggs of L. delicata have a significantly higher sodium concentration than L. guichenoti, there is no difference in the concentrations of calcium, magnesium, potassium or sodium in the neonates of the two species.

Fine structure of the developing epidermis in the embryo of the American alligator (Alligator mississippiensis, Crocodilia, Reptilia)

The morphological transition from the simple epidermis that contacts the amniotic fluid of embryonic crocodilians to the adult epidermis required in a terrestrial environment has never been described. We used light and electron microscopy to study the development, differentiation and keratinisation of the epidermis of the American alligator, Alligator mississippiensis, between early and late stages of embryonic skin formation. In early embryonic development, the epidermis consists of a flat bilayer. As it develops, the bilayered epidermis comes to lie beneath the peridermis. Glycogen is almost absent from the bilayered epidermis but increases in basal and suprabasal cells when scales form. Glycogen disappears from suprabasal cells that accumulate keratin. The peridermis and 1 or 2 subperidermal layers form an embryonic epidermis that is partially or totally lost before hatching. These cells accumulate coarse filaments and form reticulate bodies. Mucous and lamellate granules are produced in the Golgi apparatus and are partly secreted extracellularly. The embryonic cells darken with the formation of larger reticulate bodies that aggregate with intermediate filaments and other cell organelles, as their nuclear chromatin condenses. Thin beta-cells resembling those of scutate scales of birds develop beneath the embryonic epidermis and form a stratified beta-layer that varies in thickness in different body regions. The epidermis differentiates first in the back, tail and belly. At the beginning of beta-cell differentiation, the cytoplasm contains sparse bundles of alpha-keratin filaments, glycogen and lipid droplets or vacuoles apparently derived from the endoplasmic reticulum and Golgi apparatus. These organelles disappear rapidly as irregular bundles of electron-dense beta-keratin filaments accumulate and form larger bundles. The larger bundles consist of 3 nm thick electron-pale keratin microfibrils and are derived from the assemblage of beta-keratin molecules produced by ribosomes. While in mammals the epidermal barrier is formed by alpha-keratinocytes, in the alligator the barrier is formed by beta-keratin cells. The beta-layer is reduced or absent from the small hinge region between scales. In the latter areas the barrier is made of alpha or a mixture of alpha/beta keratinocytes. Thus alligators resemble birds where the beta-keratin molecules are deposited directly over an alpha-keratin scaffold, rather than an initial production of beta-keratin packets which then merge with alpha-keratin, as occurs in the 'Chelonia and Lepidosauria. The pigmentation of the epidermis of embryos is mostly derived from epidermal melanocytes.

Placental nutrition in the Tasmanian skink, Niveoscincus ocellatus

Niveoscincus ocellatus is an important species in historical analyses of the evolution of viviparity because it is the species upon which the type II chorioallantoic placenta was based. Here we describe the net nutrient uptake across the placenta of N. ocellatus for comparison with other species of skinks with complex placentae. N. ocellatus is highly placentotrophic, with neonates being 1.68-times larger in dry matter than the fresh eggs. There is an increase of nitrogen from 6.3 +/- 0.2 mg to 9.2 +/- 0.6 mg, and ash from 3.8 +/- 0.3 mg to 6.7 +/- 0.6 mg. The increase in ash is made up by a more than two-fold increase in the amounts of calcium, potassium and sodium. There is no significant difference in lipids in the neonates compared to fresh eggs, so considerable lipid must have crossed the placenta to provide energy for embryonic development. N. ocellatus is significantly more placentotrophic than Niveoscincus metallicus, which also has a complex chorioallantoic placenta. Discovery of substantial placentotrophy in this genus confirms that two lineages of Australian lygosomine skinks (represented by the genera Pseudemoia and Niveoscincus) have evolved this pattern of embryonic nutrition and supports the hypothesis that the evolution of reptilian placentotrophy involves specialisations in addition to structural modifications of the chorioallantoic placenta.

Paracoccidioides brasiliensis in a postpartum Pap smear. A case report

BACKGROUND

There are several reported cases that describe female genital tract infections with opportunistic fungi, such as Blastomyces dermatitidis, Coccidioides immitis, Aspergillus flavus, Cryptococcus neoformans and Mucor. We describe a case of paracoccidiodomycosis limited to the uterine cervix. To the best of our knowledge, no such case has been described before in the English-language literature.

CASE

A 27-year-old, healthy female, gravida 3, para 2, abortion 1, presented for a routine gynecologic examination at six weeks' postpartum. Her past medical history was unremarkable. A routine cervical/endocervical smear revealed the presence of multiple fungal forms at different stages of development with a characteristic "pilot's wheel" appearance consistent with Paracoccidioides brasiliensis. Detailed medical examination of the patient did not reveal the presence of the primary infection in any other system. Cultures of the endometrium revealed no growth of the fungal organisms. The patient was asymptomatic, and therefore no therapy was initiated. Repeat Papanicolaou smears were negative for organisms.

CONCLUSION

Paracoccidioidomycosis can present as a limited form, involving the cervix only. Identification and recognition of the infection are important in cytopathology.

Lipids of the eggs and neonates of oviparous and viviparous lizards

The purpose of this article is to collate the compositional data for the lipids of the eggs and neonates of ten species of lizards displaying a range of parity modes, to highlight emergent trends and to identify some of the physiological changes central to the evolution of viviparity. The eggs of oviparous species and of viviparous species with a simple (type I) placenta are characterised by very high proportions of triacylglycerol which forms over 80% (wt. /wt.) of the total yolk lipid. The eggs of viviparous species with complex (types II and III) placentae contain lower proportions of triacylglycerol (about 70% of total yolk lipid) and commensurately greater proportions of phospholipid, cholesteryl ester and free cholesterol. The fatty acid compositions of the yolk lipids are very similar for all the lizard species, irrespective of parity mode; in particular, the proportions of docosahexaenoic acid are consistently low. For all the species, the proportions of both docosahexaenoic and arachidonic acids are higher in the phospholipid of the neonate compared with the egg. The difference between the lipid contents of the eggs and the neonates indicates that, in species of Pseudemoia which have a complex (type III) placenta, more than 50% of the total lipid supplied to the embryo is derived from placental transport.

Energy consumption by embryos of a viviparous lizard, Eulamprus tympanum, during development

Energy consumption during development has been measured in many oviparous lizards, but not in viviparous lizards in utero. It has always been assumed that energy consumption by embryos of viviparous lizards during development is similar to that of oviparous species. Estimation of energy consumption of viviparous lizards in vivo are confounded by the possible influence of pregnancy on maternal metabolism. Here we separated maternal and embryonic metabolism in measurements of pregnant Eulamprus tympanum throughout pregnancy. Our data support the hypothesis that the energetic cost of development in viviparous lizards (19.8 kJ g(-1)) is similar to that in oviparous lizards (mean 16.2 kJ g(-1)), at least for a species with a simple placenta. An increase in maternal metabolism of 29% above that for non-pregnant E. tympanum goes to maintain pregnancy, and represents an important component of the reproductive effort in E. tympanum.

Evolution of placentation among squamate reptiles: recent research and future directions

Squamate reptiles are uniquely suited to study of evolution of reproductive mode and pattern of embryonic nutrition. Viviparous species have evolved from oviparous ancestors on numerous occasions, patterns of nutritional provision to embryos range widely from lecithotrophy, at one end of a continuum, to placentotrophy at the other, and structure and function of the maternal-embryonic relationship is highly constrained resulting in parallel evolutionary trajectories among taxa. Embryos of oviparous species primarily receive nourishment from yolk, but also mobilize a significant quantity of calcium from the eggshell. Most viviparous species also are predominantly lecithotrophic, yet all viviparous species are placentotrophic to some degree. Similarities in embryonic development and nutritional pattern between oviparous species and most viviparous species suggest that the pattern of nutrition of oviparous squamates is an exaptation for the evolution of viviparity and that placentotrophy and viviparity evolve concomitantly. The few species of squamates that rely substantially on placentotrophy have structural modifications of the interface between the embryo and mother that are interpreted as adaptations to enhance nutritional exchange. Recent studies have extended understanding of the diversity of embryonic nutrition and placental structure and have resulted in hypotheses for transitions in the evolution of placentotrophy, yet data are available for few species. Indirect tests of these hypotheses, by comparison of structural-functional relationships among clades in which viviparity has evolved, awaits further study of the reproductive biology of squamates.

Comparison of nutrient transport across the placenta of lizards differing in placental complexity

We have reviewed published and new quantitative data on the net uptake of nutrients by embryos of oviparous and viviparous lizards that vary in chorioallantoic placental complexity to better understand the evolution of complex placentae. We assessed net nutrient uptake during embryonic development by measuring the total dry mass, or the mass of separate nutrients, in the egg at about the time of ovulation and in the neonate. There is no significant difference in the fresh egg to neonate dry mass ratio of oviparous and viviparous species that have simple placentae, indicating that there is little, if any, net uptake of nutrients by viviparous species with simple chorioallantoic placentae. In contrast, there is significant uptake of dry matter and individual nutrients across the placenta of species with complex chorioallantoic placentae. Species of the genus Niveoscincus have a range of placentae and nutrient uptakes, even among populations of one species, suggesting that further studies among populations of single species are required. Data are available for relatively few clades, and all the data for the three most complex chorioallantoic placental types are derived from a single genus. Thus, further research on new genera of lizards is required to overcome the potentially confounding effects of phylogeny in our analyses.

The plasma membrane transformation facilitates pregnancy in both reptiles and mammals

Mechanisms of placentation are very diverse in mammals and range from types in which the uterine epithelium is breached by the implanting blastocyst to those where the epithelium remains intact. Despite these differences in mechanisms, the initial response of the plasma membrane of uterine epithelial cells is remarkably similar across mammalian species which has led to the term 'plasma membrane transformation' to encapsulate the concept of a common beginning to implantation. Membrane phenomena similar to those of mammals have now been observed in some viviparous lizards at the ultrastructural level during early pregnancy, and we propose extending the concept of 'plasma membrane transformation' to lizards with live birth.

Genetic disruption of Ptgs-1, as well as Ptgs-2, reduces intestinal tumorigenesis in Min mice

Two isoforms of cyclooxygenase (COX) are known, and to date most studies have implicated COX-2, rather than COX-1, as the isoform involved in colon carcinogenesis. In the present study, we show that homologous disruption of either Ptgs-1 or Ptgs-2 (genes coding for COX-1 or COX-2, respectively) reduced polyp formation in Min/+ mice by approximately 80%. Only COX-1 protein was immunohistochemically detected in normal intestinal tissue, whereas both COX-1 and variable levels of COX-2 protein were detected in polyps. Prostaglandin E2 was increased in polyps compared with normal tissue, and both COX-1 and COX-2 contributed to the PGE2 produced. The results indicate that COX-1, as well as COX-2, plays a key role in intestinal tumorigenesis and that COX-1 may also be a chemotherapeutic target for nonsteroidal anti-inflammatory drugs.

How incubation temperature influences the physiology and growth of embryonic lizards

Eggs of two small Australian lizards, Lampropholis guichenoti and Bassiana duperreyi, were incubated to hatching at 25 degrees C and 30 degrees C. Incubation periods were significantly longer at 25 degrees C in both species, and temperature had a greater effect on the incubation period of B. duperreyi (41.0 days at 25 degrees C; 23.1 days at 30 degrees C) than L. guichenoti (40.1 days at 25 degrees C; 27.7 days at 30 degrees C). Patterns of oxygen consumption were similar in both species at both temperatures, being sigmoidal in shape with a fall in the rate of oxygen consumption just prior to hatching. The higher incubation temperature resulted in higher peak and higher prehatch rates of oxygen consumption in both species. Total amount of oxygen consumed during incubation was independent of temperature in B. duperreyi, in which approximately 50 ml oxygen was consumed at both temperatures, but eggs of L. guichenoti incubated at 30 degrees C consumed significantly more (32.6 ml) than eggs incubated at 25 degrees C (28.5 ml). Hatchling mass was unaffected by either incubation temperature or the amount of water absorbed by eggs during incubation in both species. The energetic production cost of hatchling B. duperreyi (3.52 kJ x g(-1)) was independent of incubation temperature, whereas in L. guichenoti the production cost was greater at 30 degrees C (4.00 kJ x g(-1)) than at 25 degrees C (3.47 kJ g(-1)). Snout-vent lengths and mass of hatchlings were unaffected by incubation temperature in both species, but hatchling B. duperreyi incubated at 30 degrees C had longer tails (29.3 mm) than those from eggs incubated at 25 degrees C (26.2 mm). These results indicate that incubation temperature can affect the quality of hatchling lizards in terms of embryonic energy consumption and hatchling morphology.

Cyclosporin ameliorates traumatic brain-injury-induced alterations of hippocampal synaptic plasticity

Although traumatic brain injury (TBI) often results in impaired learning and memory functions, the underlying mechanisms are unknown and there are currently no treatments that can preserve such functions. We studied plasticity at CA3-CA1 synapses in hippocampal slices from rats subjected to controlled cortical impact TBI. Long-term potentiation (LTP) of synaptic transmission was markedly impaired, whereas long-term depression (LTD) was enhanced, 48 h following TBI when compared to unoperated and sham control rats. Post-TBI administration of cyclosporin A, a compound that stabilizes mitochondrial function, resulted in a highly significant amelioration of the impairment of LTP and completely prevented the enhancement of LTD. Our data suggest that alterations in hippocampal synaptic plasticity may be responsible for learning and memory deficits resulting from TBI and that agents such as cyclosporin A that stabilize mitochondrial function may be effective treatments for TBI.

Lipid composition of eggs of an oviparous lizard (Bassiana duperreyi)

Lipid analysis was performed on freshly ovulated eggs (n = 5) of the oviparous lizard Bassiana duperreyi. The fresh weight of the whole egg contents was 132.0 +/- 4.3 mg (mean +/- SE) of which lipid constituted 21.9 +/- 1.1% (w/w). Triacylglycerol formed an exceptionally high proportion (85.4 +/-0.5%, w/w) of the total lipid, whereas phospholipid, free cholesterol, cholesteryl ester, and free fatty acid, respectively, contributed 11.2 +/- 0.3, 1.4 +/- 0.1, 1.3 +/- 0.1, and 0.6 +/- 0.1% of the total lipid mass. Linoleic and alpha-linolenic acids were the major polyunsaturates of the triacylglycerol fraction, respectively, forming 16.3 +/- 0.1 and 8.3 +/- 0.1% (w/w) of the fatty acids. Linoleic acid was the major fatty acid (29.0 +/- 0.1%) of the total phospholipid, which also contained substantial amounts of arachidonic (6.4 +/- 0.1%) and eicosapentaenoic (3.0 +/- 0.1%) acids, but a relatively low proportion (1.6 +/- 0.1%) of docosahexaenoic acid. Phosphatidylcholine formed the major phospholipid class (73.8 +/- 2.3%) w/w of total phospholipid) and was enriched in linoleic acid, whereas phosphatidylethanolamine, which formed 20.4 +/- 1.9%(w/w) of total phospholipid, contained higher proportions of arachidonic and docosahexaenoic acids.

Cyclosporin A attenuates acute mitochondrial dysfunction following traumatic brain injury

Experimental traumatic brain injury (TBI) results in a rapid and significant necrosis of cortical tissue at the site of injury. In the ensuring hours and days, secondary injury exacerbates the primary damage, resulting in significant neurological dysfunction. Recent reports from our lab and others have demonstrated that the immunosuppressant cyclosporin A (CsA) is neuroprotective following TBI. The opening of the mitochondrial permeability transition pore (MPTP) is inhibited by CsA, thereby maintaining the mitochondrial membrane potential and calcium homeostasis in isolated mitochondrial. In the present study we utilized a unilateral controlled cortical impact model of TBI to assess mitochondrial dysfunction in both isolated mitochondria and synaptosomes to elucidate the neuroprotective role of CsA. The results demonstrate that administration of CsA 15 min postinjury significantly attenuates mitochondrial dysfunction as measured using several biochemical assays of mitochondria integrity and energetics. Following TBI, mitochondria isolated from the injured cortex of animals treated with CsA demonstrate a significant increase in mitochondria membrane potential and are resistant to the induction of mitochondrial permeability transition compared to vehicle-treated animals. Similarly, synaptosomes isolated from CsA-treated animals demonstrate a significant increase in mitochondria membrane potential, accompanied by lower levels of intramitochondrial Ca2+ and reactive oxygen species production than seen in vehicle-treated animals. These results suggest that the neuroprotective properties of CsA are mediated through modulation of the MPTP and maintenance of mitochondria homeostasis. Amelioration of cortical damage with CsA indicates that pharmacological therapies can be devised which will significantly alter neurological outcome after injury.

Placental nutrition in the viviparous lizard Niveoscincus metallicus: the influence of placental type

The ion, energy, lipid, nitrogen and fat-soluble vitamin contents of freshly ovulated eggs and neonates of the viviparous lizard Niveoscincus metallicus were measured to quantify uptake of nutrients across the placenta. This species is particularly interesting because it has a chorio-allantoic placenta that is intermediate in complexity compared to viviparous species that have been the focus of other studies. Newly ovulated eggs have a wet mass of 79.6+/−4.6 mg and a dry mass of 41.8+/−2.8 mg, compared to the neonates that have a wet mass of 224.2+/−8.2 mg and dry mass of 37.9+/−1.2 mg. Thus, there is no significant net uptake of dry matter across the placenta. Neonates have significantly less lipid (6.2+/−0.4 mg) than eggs (12.7+/−0.5 mg), but no significant difference in nitrogen (4.1+/−0.3 mg) compared to eggs (4.5+/−0.2 mg). Energy densities reflect the protein and lipid composition and the relative dry masses of the eggs and neonates. There is significantly more energy (1029.1+/−80.0 J) in the egg than in the neonate (858.2+/−38.6 J). The increase in the ash content of the neonates (2.9+/−0.2 mg) compared to fresh eggs (2.1+/−0.3 mg) was not significant, even though there was an approximately threefold increase in the amount of sodium (0.11+/−0.01 mg in neonates, 0.34+/−0.01 mg in eggs) and potassium (0.12+/−0.017 in neonates, 0.40+/−0.01 mg in eggs) in neonates compared to eggs. There was no significant uptake of calcium and magnesium during development. The egg lipids consisted of triacylglycerol (66.7+/−2.3 %), phospholipid (18.9+/−0.7 %), cholesteryl ester (4.9+/−1.6 %) and free cholesterol (5.6+/−1.5 %). The egg phospholipid contained comparatively high proportions of arachidonic and eicosapentanoic acids but low levels of docosahexaenoic acid (DHA), whereas the phospholipid of the neonate was greatly enriched in DHA. In the egg, the predominant vitamin E was (α)-tocopherol (62.6+/−3.4 mg g(−)(1)), although there was some (γ)-tocotrienol (3.5+/−0.3 mg g(−)(1)), and vitamin A was present (1.5+/−0.2 mg g(−)(1)). The ratio of neonate dry mass to egg dry mass of N. metallicus (0.91) lies between that of species with type I (0.78) and type III (1.70) chorio-allantoic placentae, confirming our conclusion that the placenta of N. metallicus is functionally intermediate, as well as intermediate in complexity, between these other two types.

Epidermal differentiation in the developing scales of embryos of the Australian scincid lizard Lampropholis guichenoti

Formation of the first epidermal layers in the embryonic scales of the lizard Lampropholis guichenoti was studied by optical and electron microscopy. Morphogenesis of embryonic scales is similar to the general process in lizards, with well-developed overlapping scales being differentiated before hatching. The narrow outer peridermis is torn and partially lost during scale morphogenesis. A second layer, probably homologous to the inner peridermis of other lizard species, but specialized to produce lipid-like material, develops beneath the outer peridermis. Two or three lipogenic layers of this type develop in the forming outer surface of scales near to the hinge region. These layers form a structure here termed "sebaceous-like secretory cells." These cells secrete lipid-like material into the interscale space so that the whole epidermis is eventually coated with it. This lipid-like material may help to reduce friction and to reduce accumulation of dirt between adjacent extremely overlapping scales. At the end of their differentiation, the modified inner periderm turns into extremely thin cornified cells. The layer beneath the inner peridermis is granulated due to the accumulation of keratohyalin-like granules, and forms a shedding complex with the oberhautchen, which develops beneath. Typically tilted spinulae of the oberhautchen are formed by the aggregation of tonofilaments into characteristically pointed cytoplasmic outgrowths. Initially, there is little accumulation of beta-keratin packets in these cells. During differentiation, the oberhautchen layer merges with cells of the beta-keratin layer produced underneath, so that a typical syncytial beta-keratin layer is eventually formed before hatching. Between one-fourth distal and the scale tip, the dermis under epidermal cells is scarce or absent so that the mature scale tip is made of a solid rod of beta-keratinized cells. At the time of hatching, differentiation of a mesos layer is well advanced, and the epidermal histology of scales corresponds to Stage 5 of an adult shedding cycle. The present study confirms that the embryonic sequence of epidermal stratification observed in other species is basically maintained in L. guichenoti.

Epidermal differentiation during carapace and plastron formation in the embryonic turtle Emydura macquarii

As part of a large comparative study on the development of reptilian skin, we provide the first ultrastructural description of differentiation of the epidermis of the carapace and plastron in the Chelonia, using the Australian pleurodiran turtle Emydura macquarii as a model. The epidermis is initially composed of an external flat peridermis and a basal layer of cuboidal cells. During differentiation, the peridermis darkens, flakes off and is partially lost before hatching. Four to 6 layers of flat cells containing lipids and mucus form from the basal layer beneath the external peridermis. Because such cells are found only during embryogenesis, we have referred to these layers as embryonic epidermis. They contain reticulate bodies made of a meshwork of coarse filaments similar to those described in the inner peridermis of lizard and bird embryos. In advanced embryos, cells of the embryonic epidermis condense into a thin dark stratum which is subsequently lost after hatching. The lowermost 2 layers of the embryonic epidermis keratinise, as for a typical lepidosaurian alpha-layer. A splitting zone is progressively formed beneath the alpha-layer to separate the embryonic epidermis from the underlying beta-layer. Patterns of cytodifferentiation of the beta-synthesising cells over the carapace and plastron essentially resemble those of the lepidosaurian epidermis. The beta-keratin matrix initially accumulates among ribosomes as round bodies not clearly surrounded by a membrane. These bodies appear not to be derived from the Golgi apparatus. Melanosomes and other dark granules of uncertain nature are present among early differentiating beta-cells. The round beta-keratin bodies merge with the dense bodies to produce the definitive variegated pattern of the mature beta-keratin layer. The histochemistry suggests that calcium combines with organic molecules within beta-keratinising cells to harden the tissue. In contrast to the beta-keratin cells of lizards and snakes, cells of the mature beta-keratin layer of E. macquarii maintain their cell boundaries in part or completely, a characteristics shared with the beta-keratin layer of Sphenodon and crocodilians.

The diet and digestive energetics of an Australian short-necked turtle, Emydura macquarii

We described the diet of Emydura macquarii, an omnivorous turtle from south-eastern Australia, compared its digestive performance on diets of fish or plants at two temperatures, and related how both diet and temperature affect its food selection in nature. Filamentous algae constituted 61% of the stomach content of E. macquarii. The turtles rarely fed on motile prey, but selected carrion from the lagoon bottom and terrestrial insects (Diptera, Hymenoptera and Coleoptera) trapped on the surface of the water. Digestive efficiency of E. macquarii was affected little by body temperature, in contrast to consumption rates and rates of passage which were strongly influenced by both temperature and diet. In combination, these responses resulted in a slower rate of digestion at 20 degrees C than at 30 degrees C. Digestive efficiency of E. macquarii on a herbivorous diet at 30 degrees C (49%) was about half that of turtles on a carnivorous diet (91%), but they had longer transit times (118 h on the plant diet versus 70 h). Lower consumption rates and longer mean retention times in turtles fed plants compared those fed fish relate to slower digestive processing of the plant. Rapid processing and higher consumption rates of fish by E. macquarii resulted in higher energy gains compared to turtles consuming plants (almost 100 times more energy at 30 degrees C). The laboratory results suggest that fish carrion and aquatic and terrestrial invertebrates are probably essential dietary items of E. macquarii in the wild, because its metabolic requirements cannot be met from aquatic macrophytes alone.

Placental ontogeny of the Australian scincid lizards Niveoscincus coventryi and Pseudemoia spenceri

Models for the evolution of placentation among squamate reptiles have been strongly influenced by early work on one lineage of Australian scincid lizards: one of three lineages that include species with specialized allantoplacentation. The discovery of two types of complex allantoplacentae among species currently assigned to the Eugongylus species group led Weekes ([1935] Proc. Zool. Soc. Lond., 2:625-645) to propose that a graded evolutionary sequence was exemplified by the morphological series of allantoplacental types that existed among Australian skinks. One of the model's strengths is the incorporation of testable inferences of the relationship between placental structure and function. However, descriptions of placental structure for some species are incomplete and subsequent taxonomic revisions have resulted in confusion concerning the species studied. One of the ambiguities is the identity of Lygosoma weekesae (Kinghorn [1929] Proc. Linn. Soc. N.S.W., 54:32-33), one of two species for which the most specialized type of allantoplacenta was defined. The distinguishing characteristic of this placental type is the presence of a structure known as a placentome. Subsequent to the original species description, Lygosoma weekesae was named a synonym for Pseudemoia spenceri (Rawlinson [1974] Mem. Natn. Mus. Vict., 35:87-96), yet the placental description (Weekes [1929] Proc. Linn. Soc. N.S.W., 54:34-60) is thought to be of Niveoscincus coventryi (Rawlinson [1975] Mem. Natn. Mus. Vic., 36:1-16). We describe placental ontogeny of N. coventryi and P. spenceri as a contribution to study of comparative placentation among lygosomatine skinks. We conclude that the placental description for L. weekesae could not have been N. coventryi, because a placentome is not a component of the allantoplacenta of N. coventryi. Further, the allantoplacenta of this species does not conform to previously defined categories for Eugongylus group skinks. The allantoplacenta of P. spenceri contains a placentome that is structurally congruous with the original description of placentation for L. weekesae (Weekes [1929] Proc. Linn. Soc. N.S.W., 54:34-60). Comparison of extraembryonic membrane and placental structure among the four viviparous and one oviparous species of Eugongylus group skinks for which data are available shows that each species exhibits characters that distinguish it from other species, while additional characters are shared among all, or some, species. Based on a recent phylogenetic hypothesis, the distribution of allantoplacental types among these species does not support Weekes' ([1935] Proc. Zool. Soc. Lond., 2:625-645) model of a graded sequence for the evolution of squamate placentation.

Use of ursodeoxycholic acids in a dog with chronic hepatitis: effects on serum hepatic tests and endogenous bile acid composition

A dog with severe cholestasis secondary to chronic hepatitis was treated with ursodeoxycholic acid (UDCA) PO. After 2 weeks of daily treatment, the dog was more active and had an improved appetite. Monthly serum biochemical determinations and analysis of individual bile acid profiles documented improvement in hepatobiliary tests and a marked reduction in the concentrations of potentially hepatotoxic endogenous bile acids. These effects were maintained for approximately 6 months. The findings in this dog are similar to those reported for human patients treated with UDCA and provide preliminary evidence in support of its continued evaluation in the treatment of cholestatic liver disease in the dog.

Effects of oral ursodeoxycholic acid in healthy cats on clinicopathological parameters, serum bile acids and light microscopic and ultrastructural features of the liver

A blind, placebo-controlled study evaluated the effects of ursodeoxycholic acid (UDCA) given orally, at a dose of 15 mg kg-1 per day for eight weeks, on the physical condition, haematological and serum biochemical profiles, urinalysis, total serum bile acids (TSBA) and hepatic histology of four healthy cats. There were no clinically important significant differences between the groups or within the treatment groups in clinicopathological parameters. TSBA concentrations or histology. A significant lower concentration/proportion of taurochenodeoxycholic acid was observed in the treated cats (P = 0.05). Only one treated cat accumulated measurable quantities of UDCA, and the compound appeared to be non-toxic. It did not increase the concentration of TSBA, and accumulated minimally in the serum. It should be investigated for therapeutic use in cats with hepatobiliary disease.

Frequency and relationships of clinical chemistry and liver and kidney histopathology findings in 13-week toxicity studies in rats

The relative sensitivities of eight commonly used clinical chemistry end points and histopathology to detect potential toxic effects in liver and kidney were evaluated for a series of 61 13-week rat toxicity studies conducted for the National Toxicology Program. The data consisted of 1-,2- to 3-, and 13 week clinical chemistry measurements and 13-week histopathological assessments of liver and kidney. Except for serum alkaline phosphatase, treatment-related alterations of individual clinical chemistry variables occurred in 20-48% of the studies, depending on the analyte, sampling time, and sex. Liver and kidney lesions were reported for 31% and 41% of the studies respectively. There was an association between treatment-related increases in alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) activities and histopathological changes in the liver. SDH activity had greater positive and negative predictive values than similar changes in ALT; by week 1 in females and weeks 2-3 in both sexes. SDH predicted morphological hepatic change at study termination with 75% or better accuracy. If increases in activities of both enzymes occurred simultaneously, however, terminal histopathological changes could be predicted, in both sexes, with 75% accuracy by week 1, increasing to 100% by weeks 2-3. There also was an association between treatment-related increases in urea nitrogen (UN) and creatinine (Cre) concentrations and morphological kidney change. Cre concentration had greater positive predictive values than similar changes in UN; by weeks 2-3 in males and week 13 in both sexes. Cre predicted morphological renal change at study termination with 56% or better accuracy. UN concentration was associated and predictive of morphological kidney change only in females at week 13. Depending on time point and sex, serum alkaline phosphatase activity increased in 5-22% of the studies. Increases in total bile acid concentration occurred in 33-48% of the studies. Because both tests are used as markers of cholestasis, this marked discrepancy was unexpected. Treatment-related decreases in alkaline phosphatase activity occurred, however, in 39-56% of the studies; serum alkaline phosphatase may be more useful as an indicator of decreased food intake (decreased activity) than of cholestasis (increased activity). In summary, treatment-related alterations of clinical chemistry and histopathology occurred frequently in this series of toxicity studies in rats. Changes in the chemistry end points also occurred frequently at interim time points, indicating that clinical chemistry evaluations can be useful for detecting potential treatment effects throughout a study. This observation is important, since histopathological evaluations are limited to animal termination and not useful for detecting transient responses or the onset of treatment-related effects.

Bile acids in the assessment of hepatocellular function

Bile acids, which are synthesized in the liver from cholesterol, are important in the production of bile flow, excretion of cholesterol, and intestinal digestion and absorption of fats and fat-soluble vitamins. Increases and/or alterations in concentrations of bile acids in serum are specific and sensitive indicators of hepatobiliary disorders. Synthesis of bile acids in hepatocytes involves steps in endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. Other important hepatocellular processes involving bile acids include active uptake by the basolateral membrane, intracellular transport, P-450-mediated conjugations and hydroxylations, and canalicular secretion. Hydrophobic bile acids produce hepatotoxicity in vivo and in vitro. In experimental and epidemiologic studies, some of these forms have been identified as causative agents in the development of colon and liver (experimental only) cancer. Conversely, several hydrophilic forms, primarily ursodeoxycholic acid, have demonstrated cytoprotective properties in a variety of clinical and experimental hepatobiliary diseases and disorders. Because bile acids can have dramatically different properties and effects, determination of mechanisms of action of these compounds has become an active area of research. Primary isolated hepatocytes provide an opportunity to investigate bile acid-related functions and effects in well-designed, carefully controlled studies. Short-term cultures have been used to study a variety of issues related to bile acids, including cytotoxicity, synthesis, and hepatocellular processing. With these systems, however, many functions of mature hepatocytes, including those pertaining to bile acids, can be lost when cultures are maintained for more than several days. Recent developments in culture techniques permit long-term maintenance of functionally stable, differentiated cells. Pertaining to bile acid research, these systems remain to be fully characterized but, in appropriate situations, they should provide important alternatives to in vivo studies and short-term in vitro assays.

Heterothermy, torpor, respiratory gas exchange, water balance and the effect of feeding in Gould's long-eared bat Nyctophilus gouldi

The effects of temperature and nutritional status on the metabolic rate of Nyctophilus gouldi were examined. Bats fed marked meals first defecated approximately 1.34 h after feeding and were calculated to have a mean retention time of 5.38 +/- 0.57 h but to be truly post-absorptive after 9 h. Over the temperature range 1-35 degrees C, the metabolic rate (Vo2) and body temperature (Tb) of fasted bats were extremely labile. Below 30 degrees C, the bats all entered torpor and between 10 and 15 degrees C showed a mean 84% reduction over the maximal Vo2. Body temperature was also minimal over this range (Tb = 12.5 degrees C, Ta = 10-15 degrees C). Both total and dry thermal conductance increased in a curvilinear manner with temperature, total conductance from 3.38 +/- 0.65 J g-1 h-1 degree C-1 at 1 degree C to 24.25 +/- 1.99 J g-1 h-1 degree C-1 at 35 degrees C (mean +/- S.E.M.), while the rate of evaporative water loss increased with Ta by a maximum of 10-fold from 0.21 mg g-1 h-1 at 5 degrees C to 2.69 mg g-1h-1 at 35 degrees C. Between 10 and 25 degrees C, intermittent respiration characterised by episodic bouts of breathing/gas exchange and periods of apnoea with no measurable Vo2 occurred. Although the duration of apnoea decreased when temperature was increased, the volume of oxygen taken up in each episode did not change. Mean respiratory exchange ratio (RER) was low (0.64-0.77) in post-absorptive bats, typical of fat utilisation, but during torpor ranged from near 0 to near 2, indicating discontinuous and disproportional gas exchange. Feeding produced a condition of relatively sustained homeothermy and high RER in the bats which persisted for 9 h, after which the N. gouldi became torpid. Immediately after feeding, the Vo2 of the bats increased fivefold above the post-absorptive level, while the Vco2 increased by more than eightfold. Similarly, body temperature also increased, declining to torpid values after 9. The RER in immediately post-feeding bats was near 1.0 but subsequently declined to near 0.7, indicating a switch from carbohydrate to fat utilisation. Therefore, the N. gouldi were heterothermic, exhibited a highly labile metabolic rate, and rates of heat and water loss, and Tb which were influenced both by ambient temperature and by nutritional status.

Toxicology studies of a chemical mixture of 25 groundwater contaminants: hepatic and renal assessment, response to carbon tetrachloride challenge, and influence of treatment-induced water restriction

Because groundwater contamination is an important environmental concern, we examined the hepatic and renal effects of repeated exposure to a mixture of 25 chemicals frequently found in groundwater near hazardous-waste disposal sites and the effect of such exposure on carbon tetrachloride (CCI4) toxicity. Adult male F-344 rats received ad libitum deionized water and feed (Ad Lib Water) or ad libitum 10% MIX (referring to 10% of a technically achievable stock mixture) and feed for 14 d. Because exposure to the 25-chemical mixture via the drinking water resulted in decreased water and feed consumption, restricted deionized water and feed controls (Restricted Water) were included. On d 14, rats were gavaged with 0, 0.0375, 0.05, 0.075 or 0.15 ml CCl4/kg, and hepatic and renal toxicity assessed 24 h later. Little or no hepatic and renal toxicity was observed in rats exposed to 10% MIX alone. No hepatic or renal lesions occurred that could be attributed to 10% MIX alone. Slight but statistically significant alterations, of uncertain biological significance, resulted from the water treatments: 10% MIX increased alanine aminotransferase, urea nitrogen (BUN), and BUN/creatinine ratio; Restricted Water increased 5'-nucleotidase and decreased alkaline phosphatase. Relative kidney weight was increased by both 10% MIX and Restricted Water. CCI4 resulted in significant dosage-dependent hepatotoxicity in all three water treatment groups but had little or no effect on renal indicators of toxicity. Relative to Ad Lib Water, significantly greater hepatotoxicity occurred in both 10% MIX and Restricted Water rats. The response to CCI4 in the Restricted Water rats was similar to that of 10% MIX rats, indicating that a substantial portion of the effect of 10% MIX on CCI4 hepatotoxicity is due to decreased water and feed intake.

Fine needle aspiration cytology of lymphoepitheliomalike carcinoma of the parotid gland. A case report

Lymphoepitheliomalike carcinoma is a rare primary neoplasm of the salivary gland that has also been reported to occur in other primary sites. In this report we document the clinical, cytomorphologic and histologic findings of a case affecting the parotid gland. The patient was a 48-year-old, white woman with a two-month history of a swelling on the left side of the face and associated pain. Physical examination and computed tomography revealed a left parotid mass with spread to the superior cervical lymph nodes. Fine needle aspiration (FNA) of the parotid and upper cervical nodes revealed multiple, irregular aggregates of epithelial cells with a high nuclear/cytoplasmic ratio and finely granular chromatin. Prominent, single, round nucleoli were present. Multiple chromocenters were also noted. These aggregates were found in a background of abundant, benign, small and large lymphocytes. The patient underwent parotidectomy with radical neck dissection. Histopathologic examination of the parotid showed a poorly differentiated carcinoma in a benign lymphoid background consistent with lymphoepitheliomalike carcinoma, with metastatic tumor involving two lymph nodes of the parotid compartment. To our knowledge, this is the first reported case of FNA biopsy of this unusual entity. The cytomorphologic features of these neoplasms when aspirated from the salivary gland are sufficiently distinctive to allow a specific diagnosis of lymphoepitheliomalike carcinoma.

The effects of guided imagery on anxiety levels and movement of clients undergoing magnetic resonance imaging

This randomized, experimental study examined the effects of guided imagery on anxiety levels and on movement of clients undergoing nonemergency magnetic resonance imaging (MRI). Subjects who listened to a guided imagery/relaxation tape (n = 20) before their MRI scan and used guided imagery during their scan had lower levels of state anxiety than the control group (n = 21). Based on subject report and operator report, the experimental group moved less frequently during the MRI than the control group. The results of this investigation support the use of guided imagery as a therapeutic intervention and Rogers' Science of Unitary Human Beings.