Observations on the retina and 'optical fold' of a mesopelagic sabretooth fish, Evermanella balbo.

The 'optical fold' of Evermanella balbo covers the ventro-lateral cornea and is presumed to capture illumination that would otherwise remain undetected by the tubular eye of this mesopelagic teleost. It contains alternating bands of cellular and acellular material, running approximately perpendicular to the lateral surface of the eye. Only parts of this lamellar body lie within the eyelid-like structure. The cellular lamellae are 2-2.5 µm thick centrally and composed of fibroblast-like cells. The extracellular bands (4.5-5 µm thick) contain regular arrays of collagen fibrils, with layers of thin fibrils sandwiching a region of thicker fibrils. The thin fibrils are organised in alternating sheets where fibrils, although all parallel, change their orientation by 90° between each sheet. All thick fibrils are oriented parallel to the lateral surface of the 'optical fold'. In the main retina, small bundles of rod inner/outer segments are separated by the processes of the retinal pigment epithelium (rpe) laterally. Centrally, the length of tightly packed rods increases, but rpe processes no longer divide them into bundles. Medially, rod length increases further, but packing is less dense. The accessory retina is significantly thinner, and less well-developed than the main retina. Ventrally, the rods show no regular arrangement and are not grouped. Dorsally, however, rods are arranged into bundles, separated by melanosome-filled rpe processes. The thickness of the retina increases as it approaches the crystalline lens. It is on this dorsal accessory retina that light traversing the 'optical fold' most likely falls, facilitating the detection of moving objects in the ventro-lateral field of view.

Fish associated with a subsea pipeline and adjacent seafloor of the North West Shelf of Western Australia.

Information on the potential ecological value of offshore oil and gas infrastructure is required as it reaches the end of its operational life and decisions must be made regarding the best practice option for decommissioning. This study uses baited remote underwater stereo-video systems to assess fish assemblages along an offshore subsea pipeline and in adjacent natural seabed habitats at ∼140 m depth on the North West Shelf of Western Australia. A total of 955 fish from 40 species and 25 families were recorded. Species richness was, on average 25% higher on the pipeline (6.48 ±â€¯0.37 SE) than off (4.81 ±â€¯0.28 SE) while relative abundance of fish was nearly double on the pipeline (20.38 ±â€¯2.81 SE) than in adjacent natural habitats (10.97 ±â€¯1.02 SE). The pipeline was characterised by large, commercially important species known to associate with complex epibenthic habitat and, as such, possessed a biomass of commercial fish ca 7.5 × higher and catch value ca. 8.6 × ($65.11 ±â€¯$11.14 SE) than in adjacent natural habitats ($7.57 ±â€¯$2.41 SE). This study has added to the knowledge of fish assemblage associations with subsea infrastructure and provides a greater understanding of the ecological and fisheries implications of decommissioning, helping to better inform decision-making on the fate of infrastructure.

The effects of surface structure mutations in Arabidopsis thaliana on the polarization of reflections from virus-infected leaves.

The way in which light is polarized when reflected from leaves can be affected by infection with plant viruses. This has the potential to influence viral transmission by insect vectors due to altered visual attractiveness of infected plants. The optical and topological properties of cuticular waxes and trichomes are important determinants of how light is polarized upon reflection. Changes in expression of genes involved in the formation of surface structures have also been reported following viral infection. This paper investigates the role of altered surface structures in virus-induced changes to polarization reflection from leaves. The percentage polarization of reflections from Arabidopsis thaliana cer5, cer6 and cer8 wax synthesis mutants, and the gl1 leaf hair mutant, was compared to those from wild-type (WT) leaves. The cer5 mutant leaves were less polarizing than WT on the adaxial and abaxial surfaces; gl1 leaves were more polarizing than WT on the adaxial surfaces. The cer6 and cer8 mutations did not significantly affect polarization reflection. The impacts of Turnip vein clearing virus (TVCV) infection on the polarization of reflected light were significantly affected by cer5 mutation, with the reflections from cer5 mutants being higher than those from WT leaves, suggesting that changes in CER5 expression following infection could influence the polarization of the reflections. There was, however, no significant effect of the gl1 mutation on polarization following TVCV infection. The cer5 and gl1 mutations did not affect the changes in polarization following Cucumber mosaic virus (CMV) infection. The accumulation of TVCV and CMV did not differ significantly between mutant and WT leaves, suggesting that altered expression of surface structure genes does not significantly affect viral titres, raising the possibility that if such regulatory changes have any adaptive value it may possibly be through impacts on viral transmission.

Dynamic outcome prediction in a socio-demographically diverse population-based cohort of extremely preterm neonates.

OBJECTIVE: Accurate outcome prediction is crucial for counseling parents and providing individualized treatment to extremely premature infants. We sought to improve upon existing prediction model by using a diverse population-based cohort of extremely premature live births (⩽28 weeks' gestation) for survival and survival without severe neonatal morbidity at different times throughout the first week of life and to evaluate potential differences by race/ethnicity and maternal education. STUDY DESIGN: Retrospective cohort study of all California live births from 2007 through 2011 with linked birth, death and hospital discharge records. RESULTS: A total of 6009 infants were included. In the validation data set at time of delivery, the area under the receiver-operating characteristic curve for the model containing all predictors was 0.863 for survival and 0.789 for survival without severe morbidity. The marginal probability of survival without severe neonatal morbidity of an Asian infant born to a mother with <12 years of education compared with the reference (Caucasian infant, mother with ⩾12 years of education) was -0.23 (95% confidence interval (CI) -0.31 to -0.15) for all infants at time of birth and -0.28 (95% CI -0.39 to -0.18) for infants with attempted resuscitation. Notably, no other differences by racial/ethnic category and maternal education emerged. CONCLUSIONS: Probabilities of survival and survival without major morbidity change rapidly throughout the first week of life. Extremely premature infants born to Asian mothers with less than a high school education appear to have a lower probability to survive without significant morbidity compared with their Caucasian peers.

Population-based risks of mortality and preterm morbidity by gestational age and birth weight.

OBJECTIVE: The objective of this study is to examine the effect of small or large for gestational age (SGA/LGA) status on mortality and morbidity by gestational age. STUDY DESIGN: Logistic binomial regression was used to calculate relative risks (RRs) and 95% confidence intervals for infant mortality and preterm morbidities for SGA or LGA compared with appropriately grown (AGA) deliveries stratified by gestational age group. RESULTS: Compared with AGA infants of similar gestational age, SGA infants were at increased risk for infant mortality. Mortality risk was decreased for LGA infants born between 25 and 27 weeks (RR: 0.6) but increased for LGA infants born between 28 and 31 weeks (RR: 1.9). Risk of preterm morbidity was increased for SGA infants born between 28 and 38 weeks, but decreased for LGA infants born before 37 weeks. CONCLUSION: This study demonstrates the importance of considering birth weight for gestational age when evaluating morbidity and mortality risks.

Visual system evolution and the nature of the ancestral snake.

The dominant hypothesis for the evolutionary origin of snakes from 'lizards' (non-snake squamates) is that stem snakes acquired many snake features while passing through a profound burrowing (fossorial) phase. To investigate this, we examined the visual pigments and their encoding opsin genes in a range of squamate reptiles, focusing on fossorial lizards and snakes. We sequenced opsin transcripts isolated from retinal cDNA and used microspectrophotometry to measure directly the spectral absorbance of the photoreceptor visual pigments in a subset of samples. In snakes, but not lizards, dedicated fossoriality (as in Scolecophidia and the alethinophidian Anilius scytale) corresponds with loss of all visual opsins other than RH1 (λmax 490-497 nm); all other snakes (including less dedicated burrowers) also have functional sws1 and lws opsin genes. In contrast, the retinas of all lizards sampled, even highly fossorial amphisbaenians with reduced eyes, express functional lws, sws1, sws2 and rh1 genes, and most also express rh2 (i.e. they express all five of the visual opsin genes present in the ancestral vertebrate). Our evidence of visual pigment complements suggests that the visual system of stem snakes was partly reduced, with two (RH2 and SWS2) of the ancestral vertebrate visual pigments being eliminated, but that this did not extend to the extreme additional loss of SWS1 and LWS that subsequently occurred (probably independently) in highly fossorial extant scolecophidians and A. scytale. We therefore consider it unlikely that the ancestral snake was as fossorial as extant scolecophidians, whether or not the latter are para- or monophyletic.

Disordered animal multilayer reflectors and the localization of light.

Multilayer optical reflectors constructed from 'stacks' of alternating layers of high and low refractive index dielectric materials are present in many animals. For example, stacks of guanine crystals with cytoplasm gaps occur within the skin and scales of fish, and stacks of protein platelets with cytoplasm gaps occur within the iridophores of cephalopods. Common to all these animal multilayer reflectors are different degrees of random variation in the thicknesses of the individual layers in the stack, ranging from highly periodic structures to strongly disordered systems. However, previous discussions of the optical effects of such thickness disorder have been made without quantitative reference to the propagation of light within the reflector. Here, we demonstrate that Anderson localization provides a general theoretical framework to explain the common coherent interference and optical properties of these biological reflectors. Firstly, we illustrate how the localization length enables the spectral properties of the reflections from more weakly disordered 'coloured' and more strongly disordered 'silvery' reflectors to be explained by the same physical process. Secondly, we show how the polarization properties of reflection can be controlled within guanine-cytoplasm reflectors, with an interplay of birefringence and thickness disorder explaining the origin of broadband polarization-insensitive reflectivity.

Reflecting optics in the diverticular eye of a deep-sea barreleye fish (Rhynchohyalus natalensis).

We describe the bi-directed eyes of a mesopelagic teleost fish, Rhynchohyalus natalensis, that possesses an extensive lateral diverticulum to each tubular eye. Each diverticulum contains a mirror that focuses light from the ventro-lateral visual field. This species can thereby visualize both downwelling sunlight and bioluminescence over a wide field of view. Modelling shows that the mirror is very likely to be capable of producing a bright, well focused image. After Dolichopteryx longipes, this is only the second description of an eye in a vertebrate having both reflective and refractive optics. Although superficially similar, the optics of the diverticular eyes of these two species of fish differ in some important respects. Firstly, the reflective crystals in the D. longipes mirror are derived from a tapetum within the retinal pigment epithelium, whereas in R. natalensis they develop from the choroidal argentea. Secondly, in D. longipes the angle of the reflective crystals varies depending on their position within the mirror, forming a Fresnel-type reflector, but in R. natalensis the crystals are orientated almost parallel to the mirror's surface and image formation is dependent on the gross morphology of the diverticular mirror. Two remarkably different developmental solutions have thus evolved in these two closely related species of opisthoproctid teleosts to extend the restricted visual field of a tubular eye and provide a well-focused image with reflective optics.

Non-polarizing broadband multilayer reflectors in fish.

Dielectric multilayer reflectors that are non-polarizing are an important class of optical device and have numerous applications within optical fibres [1], dielectric waveguides [2] and LEDs [3]. Here we report analyses of a biological non-polarizing optical mechanism found in the broadband guanine-cytoplasm "silver" multilayer reflectors of three species of fish. Present in the fish stratum argenteum are two populations of birefringent guanine crystal, each with their optic axes either parallel to the long axis of the crystal or perpendicular to the plane of the crystal. This arrangement neutralizes the polarization of reflection due the different interfacial Brewster's angles of each population. The fish reflective mechanism is distinct from existing non-polarizing mirror designs [4, 5, 6, 7] with the important feature that there is no refractive index contrast between the low index layers in the reflector and the external environment. It is a mechanism that could be readily manufactured and exploited in synthetic optical devices.

Antenatal education for expectant mothers results in sustained improvement in knowledge of newborn care.

OBJECTIVE: Basic perinatal education to increase parental knowledge of neonatal illnesses (such as respiratory distress, sepsis, complications of prematurity) could be a feasible way to reduce high neonatal mortality rates in limited-resource nurseries. To assess the efficacy of antenatal education in increasing mothers' knowledge of basic newborn care in a limited-resource nursery, and to determine whether the knowledge is retained postpartum. STUDY DESIGN: In March to April 2008, we implemented a 10-min educational program on basic neonatal care for women receiving prenatal care in a maternal child hospital in Vientiane, Laos. The educational intervention was a structured, face-to-face interactive module taught by Lao providers using pictographic and written materials about temperature control, umbilical cord care and signs of neonatal illness. We assessed knowledge before and immediately after the module using a standardized interview tool. When possible, we reassessed knowledge postpartum to determine whether they retained information after the training. RESULT: We recruited 101 women (average age=26.3 years), and the majority (53%) were primigravidas. Participants were well educated by local standards; 57% of women had >8 years and 28% had >12 years of education. Women's knowledge of neonatal care increased by 10% on immediate posttest (P<0.0001), especially regarding knowledge of umbilical cord care and temperature control (normal temperature ranges, thermometer use). Maternal education (P=0.025) and previous births (P=0.037) correlated positively with higher pretest scores. Higher maternal education correlated with higher posttest scores (P=0.01); however, less-educated women increased their scores as much as did women with more education. Nulliparous women also increased their posttest scores to comparable levels in women with previous deliveries. Women retested after delivery retained the educational message, achieving similar posttest and postdelivery scores (P=0.08). CONCLUSION: Brief antenatal education increases mothers' understanding of basic newborn care. Mothers retain this knowledge into the early postpartum period and during early infancy when it might help reduce morbidity and mortality. The education was efficacious for women with little education. Brief antenatal educational modules seem a feasible, sustainable means of improving mothers' knowledge of newborn care. We speculate that similar programs could improve neonatal morbidity and mortality in developing countries.

MR imaging, MR spectroscopy, and diffusion tensor imaging of sequential studies in neonates with encephalopathy.

BACKGROUND: Although the imaging, spectroscopic, and diffusion characteristics of brains of infants with neonatal encephalopathy have been described, the time course during which these changes evolve is not clear. The results of sequential MR imaging studies--including anatomic MR imaging, proton MR spectroscopy, and diffusion tensor imaging (DTI)--of 10 patients enrolled prospectively in a study of neonatal encephalopathy are reported to help to clarify the time course of changes in different brain regions during the first 2 weeks of life. METHODS: Ten neonates were prospectively enrolled in a study of the evolution of MR findings in neonatal encephalopathy and were studied 2 (8 patients) or 3 (2 patients) times within the first 2 weeks of life. The MR examination included spin-echo T1 and T2-weighted images, DTI, and long echo time (288 milliseconds) proton MR spectroscopy. Diffusion parameters (diffusivity [D(av)], fractional anisotropy [FA], and individual eigenvalues) were calculated for 10 1-cm2 regions of interest in each hemisphere that were placed based on anatomic landmarks. D(av) and FA were then measured manually in the same areas on a workstation. Metabolite ratios (NAA/Ch, Cr/Ch, Cr/NAA, Lac/Ch, and Lac/NAA) were calculated in 7 regions of interest. Imaging appearance, diffusion parameters, and metabolite ratios were then evaluated longitudinally (comparing with other studies on the same patient at different times) and cross-sectionally (comparing all studies performed on the same postnatal day). RESULTS: In most of the patients a characteristic evolution of DTI and MR spectroscopy parameters was seen during the first 2 weeks after birth. Although the anatomic images were normal or nearly normal on the first 2 days after birth in most patients, abnormalities were detected on DTI (both visually and by quantitative interrogation of D(av) maps) and proton MR spectroscopy (abnormal metabolite ratios). These parameters tended to worsen until about day 5 and then normalize, though in several patients abnormal metabolite ratios persisted. Of interest, as areas of abnormal diffusivity pseudonormalized within one region of the brain they would develop in other areas. Therefore, the pattern of injury looked very different when imaging was performed at different times during this evolution. CONCLUSION: Patterns of injury detected by standard anatomic imaging sequences, DTI sequences, and proton MR spectroscopy varied considerably during the first 2 weeks after injury. The appearance of new areas of reduced diffusion simultaneous with the pseudonormalization of areas that had reduced diffusion at earlier times can result in an entirely different pattern of injury on diffusivity maps acquired at different time points. Awareness of these evolving patterns is essential if studies are performed and interpreted during this critical period of time.

The effect of elevated hydrostatic pressure on the spectral absorption of deep-sea fish visual pigments.

The effect of hydrostatic pressure (0.1-54 MPa, equivalent to pressures experienced by fish from the ocean's surface to depths of ca. 5,400 m) on visual pigment absorption spectra was investigated for rod visual pigments extracted from the retinae of 12 species of deep-sea fish of diverse phylogeny and habitat. The wavelength of peak absorption (lambda(max)) was shifted to longer wavelengths by an average of 1.35 nm at 40 MPa (a pressure approximately equivalent to average ocean depth) relative to measurements made at one atmosphere (ca. 0.1 MPa), but with little evidence of a change in absorbance at the lambda(max). We conclude that previous lambda(max) measurements of deep-sea fish visual pigments, made at a pressure close to 0.1 MPa, provide a good indication of lambda(max) values at higher pressures when considering the ecology of vision in the deep-sea. Although not affecting the spectral sensitivity of the animal to any important degree, the observed shift in lambda(max) may be of interest in the context of understanding opsin-chromophore interaction and spectral tuning of visual pigments.

Perinatal stroke in term infants with neonatal encephalopathy.

In a prospective cohort of 124 encephalopathic term infants, six infants had an acute focal stroke. All six encephalopathic patients with strokes presented with seizures. Neurodevelopmental outcome at 30 months was abnormal in all six patients and significantly worse when compared with the entire cohort overall. These findings suggest that in newborns with encephalopathy, acute focal strokes are an uncommon but serious occurrence with substantial risk for abnormal neurodevelopmental outcome.

Seizure-associated brain injury in term newborns with perinatal asphyxia.

BACKGROUND: There is controversy over whether seizures, the most common manifestation of neonatal brain injury, may themselves damage the developing brain. OBJECTIVE: To determine if neonatal seizures are independently associated with brain injury in newborns with perinatal asphyxia. METHODS: Ninety term neonates were studied with MRI and single-voxel (1)H-MRS on median day of life 6 (range 1 to 13 days). The severity of MR abnormality in the (1)H-MRS regions of interest was scored using a validated scale. Seizure severity was scored based on seizure frequency and duration, EEG findings, and anticonvulsant administration. Multivariable linear regression tested the independent association of seizure severity with impaired cerebral metabolism measured by lactate/choline and compromised neuronal integrity measured by N-acetylaspartate/choline in both regions. RESULTS: Clinical seizures occurred in 33 of 90 infants (37%). Seizure severity was associated with increased lactate/choline in both the intervascular boundary zone (p < 0.001) and the basal nuclei (p = 0.011) when controlling for potential confounders of MRI abnormalities and amount of resuscitation at birth. Each increase in seizure score was independently associated with a 21% increase in lactate/choline in the intervascular boundary zone (95% CI, 5.1-38.2%) and a 15% increase in the basal nuclei (95% CI, 0.1-31.7%). Seizure severity was independently associated with diminished N-acetylaspartate/choline in the intervascular boundary zone (p = 0.034). CONCLUSION: The severity of seizures in human newborns with perinatal asphyxia is independently associated with brain injury and is not limited to structural damage detectable by MRI.

The management of extremely premature infants and the perceptions of viability and parental counselling practices of Australian obstetricians.

The attitudes of Australian obstetricians to the resuscitation of extremely premature infants are reported. A structured questionnaire including questions regarding antenatal parent counselling, resuscitation practices, survival rates and personal attitudes about life support was distributed to obstetricians working in Australian hospitals with a Level 3 nursery Eighty-nine (48% response rate) replies were received from 12 units located in seven major cities. Obstetricians are more likely to discuss resuscitation with prospective parents with increasing gestation with a major shift occurring at 23-24 weeks' gestation. They strive for consensus with parents regarding resuscitation options and they act upon the opinion of both the prospective parents and their paediatric colleagues. Threat of litigation rarely influences the decision to limit resuscitation of an extremely preterm infant. Obstetricians may underestimate the prognosis for extremely preterm infants. The data presented offer useful insights into current attitudes and practice of tertiary hospital obstetricians.

Antenatal counselling, resuscitation practices and attitudes among Australian neonatologists towards life support in extreme prematurity.

A questionnaire survey of Australian neonatologists was conducted to ascertain their antenatal counselling and resuscitation practices, and attitudes towards life support in the extremely preterm infant. This study showed that in antenatal parental counselling, whether a paediatrician was given the opportunity to participate depends on the gestation at the time of the threatened preterm delivery The counselling employed almost invariably covered mortality and morbidity. The obstetrician's opinion was considered to be of utmost importance. Both financial and moral obligations were found to be of little importance in counselling and resuscitation. Only one-third of institutions had guidelines for limiting resuscitation. The onus remained on the neonatologists concerning which infant to resuscitate, and the level of the resuscitation to be conducted. In Australia, resuscitation at birth was restricted to infants of 23 weeks' gestation or above, and neonatologists did not believe the legal system has a role to play in limiting or mandating resuscitation of extremely preterm infants. Neither were they concerned with the threat of litigation when they decide to limit resuscitation. The majority of neonatologists agreed with their institution's approach to life support in extremely preterm infants. One grey area was the question of withholding assisted feeding in an infant for which the decision to withdraw life support has been made. Australia lacked a current consensus policy on selective non-treatment. The establishment of national guidelines would be helpful to aid Australian obstetricians and neonatologists in their clinical practice.

Proton spectroscopy and diffusion imaging on the first day of life after perinatal asphyxia: preliminary report.

BACKGROUND AND PURPOSE: MR techniques have proved useful in assessing brain injury from perinatal asphyxia when the injury is subacute or chronic. Recent advances in understanding the molecular mechanisms of brain injury have made medical intervention plausible, creating a need for assessment of the brain within the first few hours of life. We report the results of early (first 24 hours after birth) MR imaging in seven patients, including proton MR spectroscopy in six. METHODS: MR studies were performed within the first 24 hours of life in seven consecutive patients who were encephalopathic after complicated deliveries. Standard T1-, T2-, and diffusion-weighted sequences were performed in all patients; single-voxel MR spectroscopy was performed in two locations in six of the seven patients. Follow-up MR studies were performed in four patients at ages 7, 8, 9, and 15 days, respectively. RESULTS: T1-weighted images were normal in all seven patients. T2-weighted images were normal in three patients and showed T2 prolongation in the basal ganglia or white matter in the other four. Diffusion images showed small abnormalities in the lateral thalami or internal capsules in all seven patients. Comparison with clinical course in all seven patients and with follow-up MR studies in four showed that the diffusion images underestimated the extent of brain injury. Proton MR spectroscopy showed substantial lactate elevation in all six of the patients studied. Two patients died in the neonatal period and the other five were left with clinically significant neurologic impairment. CONCLUSION: MR spectroscopy performed in the first 24 hours after birth is sensitive to the presence of hypoxic-ischemic brain injury, whereas diffusion imaging may help identify but underestimate the extent of the injury. Further studies are ongoing in an attempt to expand upon this observation.

The molecular basis for spectral tuning of rod visual pigments in deep-sea fish.

Most species of deep-sea fish possess of a rod-only retina with a pigment that is generally shortwave shifted in lambda(max) towards the blue region of the spectrum. In addition, the lambda(max) values of different species tend to cluster at particular points in the spectrum. In this study, the rod opsin gene sequences from 28 deep-sea fish species drawn from seven different Orders are compared. The lambda(max) values of the rod pigments vary from approximately 520 nm to <470 nm, with the majority lying between 490 nm and 477 nm. The 520 nm pigment in two species of dragon fish is associated with a Phe261Tyr substitution, whereas the shortwave shifts of the pigments in the other 26 species are accountable by substitutions at a further eight sites (83, 122, 124, 132, 208, 292, 299 and 300). Clustering of lambda(max) values does not, however, involve a common subset of these substitutions in the different species. A phylogenetic analysis predicts that the pigment in the ancestral species would have had a lambda(max) of approximately 480 nm. A total of 27 changes is required to generate the pattern of substitutions seen in the different species, with many sites undergoing multiple changes.

Is the ultraviolet waveband a special communication channel in avian mate choice?

There is growing evidence that ultraviolet (UV) wavelengths play an important role in avian mate choice. One of the first experiments to support this idea showed that female zebra finches (Taeniopygia guttata) prefer UV-reflecting males to males whose ultraviolet reflection has been removed. The effect was very strong despite little or no UV reflection from several plumage areas. However, it is not clear how the importance of the UV waveband compares to other regions of the bird-visible spectrum. We tested whether the response of female zebra finches to the removal of male UV reflection is greater than to the removal of other wavebands. We presented females with a choice of males whose appearance was manipulated using coloured filters. The filters removed single blocks of the avian visible spectrum corresponding closely to the spectral sensitivities of each of the zebra finch's single cone classes. This resulted in males that effectively had no UV (UV-), no short-wave (SW-), no medium-wave (MW-) or no long-wave (LW-) plumage reflection. Females preferred UV- and SW- males. LW- and MW- males were least preferred, suggesting that female zebra finches show the greatest response to the removal of longer wavelengths. Quantal catches of the single cone types viewing body areas of the male zebra finch are presented for each treatment. Our study suggests it is important to consider the role of the UV waveband in avian mate choice in conjunction with the rest of the avian visible spectrum.

Three-dimensional proton MR spectroscopic imaging of premature and term neonates.

BACKGROUND AND PURPOSE: Previous studies have primarily used single-voxel techniques to obtain MR spectra from the neonatal brain. In this study, we applied 3D MR spectroscopic imaging techniques to detect the spatial distribution of MR spectroscopic imaging-detectable compounds in premature and term infants. The goals were to test the feasibility of obtaining 3D MR spectroscopic images of newborns, assess the spatial variations of metabolite levels, and determine age-dependent differences in MR spectroscopic imaging data. METHODS: MR spectroscopic imaging data were acquired from nine premature (postconceptional age, 30-34 weeks) and eight term (postconceptional age, 38-42 weeks) neonates, all with normal clinical and neurologic outcomes. A specialized point-resolved spectroscopy sequence with very selective saturation pulses was used to select a region encompassing the majority of the brain. Phase encoding in three dimensions was performed in a 17-minute acquisition time to obtain 3D spectral arrays with a 1.0 cm(3) nominal spatial resolution. RESULTS: This study showed the feasibility of detecting the 3D distributions of choline, creatine, and N-acetylaspartate resonances in the neonatal brain. Significant spectral differences were detected among anatomic locations and between the premature and term groups. CONCLUSION: This initial study indicates that 3D MR spectroscopic imaging of the neonatal brain can detect anatomic and age-dependent variations in metabolite levels. This technique seems to be a powerful tool to assess the metabolic differences between anatomic regions and to follow the changes in cellular metabolites with brain maturation. This study also indicates the need for determining topologic and age-matched normative values before metabolic abnormalities in neonates can be accurately assessed by MR spectroscopy.