bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of nitric oxide synthase in the tree shrew
retina
Authors: CAO QI-LIN , MURPHY HEATHER A. , PETRY HEYWOOD M.
Published: July 2002

Nitric oxide (NO) is a novel neuronal messenger
that likely influences retinal function by activating retinal
guanylyl cyclase to increase levels of cGMP. In the present
study, the localization of neuronal nitric oxide synthase
(nNOS, Type I NOS) in the cone-dominant tree shrew retina
was studied using NADPH-d histochemistry and nNOS immunocytochemistry.
Both NADPH-d and nNOS-immunoreactivity (IR) labeled the
inner segments of rods and the myoids of a regular subpopulation
of cones, with their corresponding nuclei outlined. The
labeled cone myoids were co-localized with a marker for
short-wave-sensitive (SWS) cones (S-antigen) and also displayed
the regular triangular packing and density (7%) characteristic
of SWS cones in tree shrew and other mammalian retinas.
These measures confirmed the identity of the labeled cones
as SWS cones. Photoreceptor ellipsoids of all cones were
strongly labeled by NADPH-d reactivity, but lacked nNOS-IR.
Another novel finding in tree shrew retina was that both
NADPH-d and nNOS-IR labeled Müller cells, which have
not been labeled by nNOS-IR in other mammalian retinas.
Consistent with findings in rod-dominant retinas, two types
of amacrine cells at the vitreal edge of the inner nuclear
layer and a subpopulation of displaced amacrine cells at
the scleral edge of the ganglion cell layer were labeled
by both NADPH-d and nNOS-IR. Processes of these labeled
cells were seen to extend into the inner plexiform layer,
where dense punctate label was seen, especially in the
central sublamina. These results show that localization
of NOS in the cone-dominant tree shrew retina shares some
common properties with rod-dominant mammalian retinas,
but also shows some species-specific characteristics. The
new finding of nNOS localization in tree shrew SWS cones
and rods, but not in other cones, raises interesting questions
about the roles of NO in the earliest level of visual processing.
Extracellular compartments of the blowfly eye: Ionic content
and topology
Authors: SCHRAERMEYER U. , POLYANOVSKY A. , PIVOVAROVA N. , ZIEROLD K. , STIEVE H. , GRIBAKIN F.
Published: July 2002

To analyze the elemental composition and topology
of the extracellular compartments of the compound eye,
the eyes of blowflies Calliphora vicina were rapidly
frozen and ultrathin cryosections were freeze dried. Three
zones of an ommatidium, peripheral cytosol of visual cells,
rhabdomeres, and ommatidial cavities were analyzed by X-ray
microprobe analysis. The ommatidial cavity was found to
contain sodium and potassium in proportion similar to that
in the blowfly hemolymph. Potassium-to-sodium ratio in
a cytosol was typical for a cytosol. The rhabdomeres displayed
an electrolyte content intermediate between the above compartments.
Three topologically connected extracellular compartments
were characterized by the experiments with tracers, monastral
blue and lanthanum: (1) common intercellular space of ommatidia
including peripheral clefts between the visual cells, both
tracers entered this compartment; (2) the ommatidial cavity,
which is not accessible for monastral blue, however, as
revealed by our X-ray microanalysis, it was reachable for
lanthanum; (3) rhabdomeric loops, which were accessible
for lanthanum entering either via the cavity or
from the common intercellular clefts. The above characteristics
of the ionic content and topology of ommatidial compartments
might suggest higher sodium and lower potassium content
in the microvilli as compared with the cytosol. The rhabdomeric
and “cavital” plasma membranes are assumed
to be permeable for these ions so that a voltage of only
25–30 mV, negative inside, is probably formed across
them, much lower than the known resting potential −60
mV across the peripheral plasma membrane of a visual cell.
Substance P-immunoreactive neurons in hamster retinas
Authors: LI HAI-BIAO , SO KWOK-FAI , CHEUK WAH
Published: July 2002

Light-microscopic immunocytochemistry was utilized
to localize the different populations of substance P-immunoreactive
(SP-IR) neurons in the hamster retina. Based on observation
of 2505 SP-IR neurons in transverse sections, 34% were
amacrine cells whose pear-shaped or round cell bodies (7–8
μm) were situated in the inner half of the inner nuclear
layer (INL) or in the inner plexiform layer (IPL), while
66% of SP-IR somata (6–20 μm) were located in
the ganglion cell layer (GCL) which were interpreted to
be displaced amacrine cells and retinal ganglion cells
(RGCs). At least three types of SP-IR amacrine cells were
identified. The SP-IR processes were distributed in strata
1, 3, and 5 with the densest plexus in stratum 5 of the
inner plexiform layer. In the wholemounted retina, the
SP-IR cells were found to be distributed throughout the
entire retina and their mean number was estimated to be
4224 ± 76. Two experiments were performed to clarify
whether any of the SP-IR neurons in the GCL were RGCs.
The first experiment demonstrated the presence of SP-IR
RGCs by retrogradely labeling the RGCs and subsequently
staining the SP-IR cells in the retina using immunocytochemistry.
The second experiment identified SP-IR central projections
of RGCs to the contralateral dorsal lateral geniculate
nucleus. This projection disappeared following removal
of the contralateral eye. The number of SP-IR RGCs was
estimated following optic nerve section. At 2 months after
sectioning the optic nerve, the total number of SP-IR neurons
in the GCL reduced from 4224 ± 76 to a mean of 1192
± 139. Assuming that all SP-IR neurons in the GCL
which disappeared after nerve section were RGCs, the number
of SP-IR RGCs was estimated to be 3032, representing 3–4%
of the total RGCs. In summary, findings of the present
study provide evidence for the existence of SP-IR RGCs
in the hamster retina.
The role of spontaneous retinal activity before eye opening
in the maturation of form and function in the retinogeniculate
pathway of the ferret
Authors: COOK P. MILTON , PRUSKY GLEN , RAMOA ARY S.
Published: July 2002

During early mammalian development, inputs from
the two retinas intermix within the lateral geniculate
nucleus (LGN), then segregate during the first postnatal
week into layers that receive input from a single retina.
Functionally, the LGN also changes markedly during the
first postnatal month; early geniculate responses to retinal
input are mainly excitatory, then inhibitory circuits mature
within the LGN. These remarkable changes in form and function
of the retinogeniculate pathway occur at a time when patterned
visual activity is not present, but retinal ganglion cells
already manifest spontaneous action potential activity.
To examine the role of early retinal activity in these
critical developmental processes, we placed the slow release
polymer Elvax embedded with tetrodotoxin (TTX) into the
vitreous chamber of one or both eyes of neonatal ferrets.
Animals receiving monocular injection of TTX had the other
eye treated with Elvax containing control citrate buffer.
Intraocular injection of horseradish peroxidase was made
at the end of the period of TTX treatment to reveal the
retinal terminals in the LGN. Chronic monocular or binocular
blockade of retinal activity during the first postnatal
week did not prevent eye-specific segregation, although
it made the boundaries between layers less distinct. Retinal
terminals ended preferentially in the appropriate layer,
but a large number of terminals were also present in the
inappropriate layer. Further segregation was achieved during
the second postnatal week of activity blockade, when most
retinal terminals ended preferentially in the appropriate
geniculate layer and sharper layer boundaries were present.
However, a small but significant number of terminals still
extended into the inappropriate layer. Together, these
findings indicate that monocular as well as binocular blockade
of retinal activity resulted in some anomalous retinogeniculate
projections and delayed eye-specific patterning, but segregation
was largely intact at the end of the second postnatal week.
We also report here that intraocular tetrodotoxin had a
marked effect on the maturation of intrinsic geniculate
circuits prior to eye opening. Whole-cell patch-clamp recordings
in the LGN slice preparation revealed that activity blockade
prevented the maturation of the slow, but not the fast,
hyperpolarizing potential of LGN neurons during the first
postnatal month and up to P38, the oldest age studied.
In conclusion, these results indicate that spontaneous
retinal activity modulates the time course of binocular
segregation but does not alone account for the segregation
of retinogeniculate terminals. However, early retinal activity
plays an important role in developing the intrinsic circuitry
of the LGN.
Contribution of rod, on-bipolar, and horizontal cell light
responses to the ERG of dogfish retina
Authors: SHIELLS R.A. , FALK G.
Published: July 2002

Simultaneous extracellular ERG and intracellular
recordings from horizontal and ON-bipolar cells were obtained
from the dark-adapted retina of the dogfish. The light
intensity–peak response relation (IR) and time course
of on-bipolar cell responses closely resembled that of
the ERG b-wave, but only at low light intensities
[<10 rhodopsin molecules bleached per rod (Rh*)].
Block of on-bipolar cell responses with 50 μM 2-amino-4-phosphonobutyrate
(APB) abolished the b-wave and unmasked a vitreal-negative
wave. Subtraction from the control ERG resulted in the
isolation of a vitreal-positive ERG with an IR which matched
that of on-bipolar cells over the full range of light intensities.
The D.C. component of the ERG arises as a result of sustained
depolarization of on-bipolar cells in response to long
(>0.5 s) dim light stimuli, or following bright light
flashes. The IR of horizontal cells and the vitreal-negative
wave unmasked by APB could be matched by scaling at low
light intensities (<5 Rh*). However, horizontal cell
responses saturated at about 30 Rh*, while the vitreal-negative
wave continued to increase in amplitude. The time course
of horizontal cell membrane current with dim flashes could
be matched to the rising phase of the vitreal-negative
wave, assuming that the delay in generating the voltage
response in horizontal cells is due to their long (100
ms) membrane time constant. Blocking post-photoreceptor
activity resulted in a much smaller vitreal-negative wave
than that unmasked by APB alone. We conclude that the b-wave
arises from on-bipolar cell depolarization, while the leading
edge of the a-wave is a composite of the change
in extracellular voltage drop across the rod layer and
a component (proximal PIII) reflecting a decrease in extracellular
K+ as horizontal cell synaptic channels close
with light.
Effects of norepinephrine upon superficial layer neurons
in the superior colliculus of the hamster: In vitro
studies
Authors: TAN HONGJING , MOONEY RICHARD D. , RHOADES ROBERT W.
Published: July 2002

Intracellular recording techniques were used to
evaluate the effects of norepinephrine (NE) on the membrane
properties of superficial layer (stratum griseum superficiale
and stratum opticum) superior colliculus (SC)
cells. Of the 207 cells tested, 44.4% (N = 92)
were hyperpolarized by ≥3 mV and 8.7% (N =
18) were depolarized by ≥3 mV by application of NE.
Hyperpolarization induced by NE was dose dependent (EC50
= 8.1 μM) and was associated with decreased input resistance
and outward current which had a reversal potential of −94.0
mV. Depolarization was associated with a very slight rise
in input resistance and had a reversal potential of −93.1
mV for the single cell tested. Pharmacologic experiments
demonstrated that isoproterenol, dobutamine, and p-aminoclonidine
all hyperpolarized SC cells. These results are consistent
with the conclusion that NE-induced hyperpolarization of
SC cells is mediated by both α2 and β1
adrenoceptors. The α1 adrenoceptor agonists,
methoxamine and phenylephrine, depolarized 35% (6 of 17)
of the SC cells tested by ≥3 mV. Most of the SC cells
tested exhibited responses indicative of expression of
more than one adrenoceptor. Application of p-aminoclonidine
or dobutamine inhibited transsynaptic responses in SC cells
evoked by electrical stimulation of optic tract axons.
Inhibition of evoked responses by these agents was usually,
but not invariably, associated with a hyperpolarization
of the cell membrane and a reduction in depolarizing potentials
evoked by application of glutamate. The present in
vitro results are consistent with those of the companion
in vivo study which suggested that NE-induced
response suppression in superficial layer SC neurons was
primarily postsynaptic and chiefly mediated by both α2
and β1 adrenoceptors.
VEP and PERG acuity in anesthetized young adult rhesus monkeys
Authors: HOEVE JAMES N. VER , DANILOV YURI P. , KIM CHARLENE B.Y. , SPEAR PETER D.
Published: July 2002

This study used the swept spatial-frequency method
to compare retinal and cortical acuity in anesthetized
young adult rhesus monkeys. Visual evoked potentials (VEPs)
and pattern electroretinographic responses (PERGs) were
recorded from 25 monkeys (age range: 4–12 years)
anesthetized with a continuous infusion of propofol. The
stimuli were temporally countermodulated sine-wave gratings
that increased in spatial frequency within a 10.24-s period.
All animals were refracted using acuity estimated from
the zero micro-volt intercept of the linear regression
of evoked potential amplitude on spatial frequency. Average
sweep acuities were 23.7 cycles/deg ± 1.5 S.E.M.
and 23.1 cycles/deg ± 1.8 S.E.M. for the PERG and
VEP, respectively. VEP and PERG acuities were within the
range expected based on acuities estimated from behavioral
studies in macaques. PERG and VEP acuities were highly
correlated (r = 0.90) and equally sensitive to
spherical blur. On a subset of animals, test–retest
reliability of animals, and interocular correlations, were
high (r = 0.87 and r = 0.83, respectively).
Increasing propofol dosage 8-fold did not degrade PERG
or VEP acuity. This study demonstrates that high spatial-frequency
acuities can be rapidly obtained from young adult rhesus
monkeys under a wide dose range of propofol anesthesia
using the swept spatial-frequency method.
Analysis of two types of cone bipolar cells in the retina
of a New World monkey, the marmoset, Callithrix jacchus
Authors: LUO XUEGANG , GHOSH KRISHNA K. , MARTIN PAUL R. , GRÜNERT ULRIKE
Published: July 2002

Two types of cone bipolar cells, the blue cone
bipolar cell and the diffuse bipolar cell (DB3), were labelled
immunohistochemically and investigated in the retina of
a New World monkey, the marmoset. Blue cone bipolar cells
were labelled with an antiserum against cholecystokinin.
Short-wavelength-sensitive (SWS) cones were labelled with
an antiserum against the SWS cone opsin. The DB3 cells
were labelled with antibodies to calbindin. Blue cone bipolar
cells in marmoset do not form a regular mosaic but instead
follow the random distribution of the SWS cones. Nevertheless,
the SWS cone to blue cone bipolar cell connectivity in
marmoset is very similar to that previously described for
macaque. In contrast to the blue cone bipolar cells, the
DB3 cells form a regular mosaic. The synaptic connectivity
of DB3 cells in the inner plexiform layer was analyzed.
They make output synapses onto ganglion cells and amacrine
cells, and gap junctions with each other. Our results provide
further evidence for the existence of parallel bipolar
cell pathways in the primate retina and support the view
that the retinae of Old World and New World primates have
common neuronal connectivity. The random distribution of
SWS cones and blue cone bipolar cells is an exception to
the general rule of a regular mosaic distribution of cell
populations in the retina.
Gamma-atrial natriuretic peptide 1–25 is found in
bipolar cells in turtle and rat retinas
Authors: HAVERKAMP SILKE , KOLB HELGA , BLUTE TODD A. , CAO LUXIANG , ELDRED WILLIAM D.
Published: July 2002

Immunocytochemistry was used to reveal a population
of bipolar cells that contain γ-atrial natriuretic
peptide 1–25 (γ-ANP) in turtle retina. This same
antibody was also used in rat retina as a comparative control.
The retinas were examined by both conventional light microscopy
and confocal microscopy with double-labeling to determine
whether protein kinase C-α-like immunoreactivity (PKC-α-LI)
was colocalized with the γ-ANP-LI. Some thick sections
of turtle retina immunostained with only the γ-ANP
antibody were also examined by electron microscopy. In
rat, a subpopulation of bipolar cells with axons terminating
close to the ganglion cell layer was labeled. Double-labeling
experiments indicated that the γ-ANP-LI and PKC-α-LI
were colocalized in rat retina, and thus all the bipolar
cells with γ-ANP-LI were rod bipolar cells. In turtle,
the γ-ANP antibody labeled certain bipolar cells that
were characterized by bistratified axon terminals arborizing
on the borders of strata S2/3 and S3/4 in the inner plexiform
layer (IPL). Double labeling with PKC-α antibody indicated
that bipolar cells with γ-ANP-LI were not the same
bipolar cell types with PKC-α-LI. Thus, γ-ANP-LI
appears to be a new marker for a distinct type of bipolar
cell in turtle retina. At the ultrastructural level, the
γ-ANP-LI was visible throughout the cytoplasm of the
bipolar cells from dendrites to axon terminals. In the
outer plexiform layer (OPL), labeled dendrites contacted
photoreceptor pedicles almost exclusively at narrow-cleft
basal junctions, but infrequently formed the central element
at a photoreceptor ribbon synapse. In the IPL, axon terminals
with γ-ANP-LI made ribbon synapses onto a combination
of amacrine and ganglion cells. Since narrow-cleft basal
junctions and photoreceptor ribbon-related junctions are
known to be associated with ON-center bipolar cells in
turtle, and since the axon terminals of bipolars with γ-ANP-LI
stratify primarily in the ON-strata of the IPL, we suggest
that these cells are likely to be ON-center cells. It is
possible that the γ-ANP may be involved in regulating
the activity of Na+/K+ ATPase or
in the modulation of cGMP levels.
Large retinal ganglion cells that form independent, regular
mosaics in the bufonoid frogs Bufo marinus and
Litoria moorei
Authors: SHAMIM K.M. , TÓTH P. , BECKER D.L. , COOK J.E.
Published: July 2002

Population-based methods were used to study labeled
retinal ganglion cells from the cane toad Bufo marinus
and the treefrog Litoria moorei, two visually
competent bufonoid neobatrachians with contrasting habitats.
In both, cells with large somata and thick dendrites formed
distinct types with independent mosaics. The αa,
αab, and αc mosaics of Bufo
in all major respects resembled those of ranids, studied
previously, and could be provisionally matched to the same
functional classes. As in other frogs, some αa
cells were displaced and many α-cells of all types
were asymmetric, but within each type all variants belonged
to one mosaic. Nearest-neighbor analyses and spatial correlograms
confirmed that all three mosaics were regular and independent.
In Litoria, monostratified αa cells
were not found. Instead, two bistratified types were present,
distinguished individually by soma size and dendritic caliber
and collectively by membership of independent mosaics:
the larger (∼0.8% of all ganglion cells) was termed
α1ab and the smaller (∼2.2%) α2ab.
An αc cell type was also present, although
too inconstantly labeled for mosaic analysis. Nearest-neighbor
analyses and spatial correlograms confirmed that the two
αab mosaics were regular and independent.
Densities, proportions, soma sizes, and mosaic statistics
are tabulated for each species. The emergence of a consensus
pattern of α-cell types in fishes and frogs, from which
this treefrog partly diverges, offers new possibilities
for studying correlations between function, phylogeny,
ecology, and neuronal form.
Long-range interactions modulate the contrast gain in the
lateral geniculate nucleus of cats
Authors: FELISBERTI FATIMA , DERRINGTON ANDREW M.
Published: July 2002

In previous work, we have shown that sudden image
displacements well outside the classical receptive field
modulate the visual sensitivity of LGN relay cells. Here
we report the effect of image displacements on the response
versus contrast function. The stimuli consisted
of a central spot of optimal size and polarity (contrast
range: 3–98%), flashed alone or in the presence of
a peripheral annulus (radii: 5–15 deg) containing
a low spatial-frequency grating displaced at saccade-like
velocities (shift). The most consistent effect
of the shift on the response to a central spot was to reduce
the responsiveness of Y relay cells and, to a lesser extent,
of X relay cells. The reduction in responsiveness was primarily
a divisive rather than a subtractive effect and could be
modelled by assuming that a greater contrast was required
to produce a given excitatory response. In the absence
of a central spot, remote motion had inhibitory effects
on the firing rates of the majority of relay cells, but
its effect on retinal ganglion cells was mainly excitatory.
When the shifting grating covered the classical receptive
field and its periphery, facilitatory effects
or suppressive effects, depending on the spatial phase
of the pattern, were observed in both retinal and geniculate
cells. Remote motion strongly suppresses the responsiveness
of relay cells to stimuli within the classical receptive
field. This suppressive effect involves intrageniculate
processing and is primarily associated with a reduction
in contrast gain. It is likely that shift suppression contributes
to the loss of visual sensitivity observed in saccadic
suppression.
Cholinergic and noradrenergic afferents influence the functional
properties of the postnatal visual cortex in rats
Authors: SICILIANO ROSITA , FORNAI FRANCESCO , BONACCORSI IRENE , DOMENICI LUCIANO , BAGNOLI PAOLA
Published: July 2002

Based on previous evidence that acetylcholine (ACh)
and noradrenaline (NA) play a permissive role in developmental
plasticity in the kitten visual cortex, we reinvestigated
this topic in the postnatal visual cortex of rats with
normal vision. In rats, the functional properties of visual
cortical cells develop gradually between the second and
the sixth postnatal week (Fagiolini et al., 1994). Cortical
cholinergic depletion, by basal forebrain (BF) lesions
at postnatal day (PD) 15 (eye opening), leads to a transient
disturbance in the distribution of ocular dominance (Siciliano
et al., 1997). In the present study, we investigated the
development of visual cortical response properties following
cytotoxic lesions of the locus coeruleus (LC) alone or
in combination with lesions of cholinergic BF. The main
result is that early NA depletion impairs the orientation
selectivity of cortical neurons, causes a slight increase
of their receptive-field size, and reduces the signal-to-noise
ratio of cell responses. Similar effects are obtained following
NA depletion in adult animals, although the effects of
adult noradrenergic deafferentation are significantly more
severe than those obtained after early NA depletion. Additional
cholinergic depletion causes an additional transient change
in ocular-dominance distribution similarly to that obtained
after cholinergic deafferentation alone. Comparisons between
depletion of NA on the one hand and depletion of both NA
and ACh on the other suggest that the effects of combined
deafferentation on the functional properties studied result
from simple linear addition of the effects of depleting
each afferent system alone.
AMPA-selective glutamate receptor subunits GluR2 and GluR4
in the cat retina: An immunocytochemical study
Authors: QIN PU , POURCHO ROBERTA G.
Published: July 2002

AMPA-selective glutamate receptors play a major
role in glutamatergic neurotransmission in the retina and
are expressed in a variety of neuronal subpopulations.
In the present study, immunocytochemical techniques were
used to visualize the distribution of GluR2 and GluR4 subunits
in the cat retina. Results were compared with previous
localizations of GluR1 and GluR2/3. Staining for GluR2
was limited to a small number of amacrine and ganglion
cells whereas GluR4 staining was present in A-type horizontal
cells, many amacrine cells including type AII amacrine
cells, and the majority of the cells in the ganglion cell
layer. Analysis of synaptic relationships in the outer
plexiform layer showed the GluR4 subunit to be concentrated
at the contacts of cone photoreceptors with A-horizontal
cells. In the inner plexiform layer, both GluR2 and GluR4
were postsynaptic to cone bipolar cells at dyad contacts
although GluR2 staining was limited to one of the postsynaptic
elements whereas GluR4 immunoreactivity was often seen
in both postsynaptic elements. Unlike GluR2, GluR4 was
also postsynaptic to rod bipolar cells where it could be
visualized in processes of AII amacrine cells. The data
indicate that GluR3 and GluR4 subunits are colocalized
in a number of cell types including A-type horizontal cells,
AII amacrine cells, and alpha ganglion cells, but whether
they are combined in the same multimeric receptors remains
to be determined.
The fountain amacrine cells of the rabbit retina
Authors: WRIGHT LAYNE L. , VANEY DAVID I.
Published: July 2002

We have characterized a distinctive type of bistratified
amacrine cell in the rabbit retina at both the single cell
and population levels. These cells correspond to the “fountain”
amacrine cells recently identified by MacNeil and Masland
(1998). The fountain cells can be distinguished in superfused
retinal wholemounts labeled with nuclear dyes, thus enabling
them to be targeted for intracellular injection with Neurobiotin.
This revealed that the primary dendrites ascend steeply
to sublamina b of the inner plexiform layer, where
they form an irregular arbor at the border of strata 4
and 5. These dendrites then give rise to multiple varicose
processes that descend obliquely to sublamina a,
where they form a more extensive arbor in stratum 1. The
fountain amacrine cells show strong homologous tracer coupling
when injected with Neurobiotin, and this has enabled us
to map their density distribution across the retina and
to examine the dendritic relationships between neighboring
cells. The fountain amacrine cells range in density from
90 to 360 cells/mm2 and they account for 1.5%
of the amacrine cells in the rabbit retina. The thick tapering
dendrites in sublamina b form highly territorial
arbors that tile the retina with minimal overlap, whereas
the thin varicose processes intermingle in sublamina a.
The fountain cells are immunopositive for γ-aminobutyric
acid and immunonegative for glycine. We further propose
that these cells are homologous to the substance P-immunoreactive
(SP-IR) amacrine cells in the cat retina and that they
may account for a subset of the SP-IR amacrine cells in
the rabbit retina.
Effect of branchial parasites on the efficiency of the gills of a freshwater catfish, Wallago attu
Authors: Ojha Jagdish , Hughes G. M.
Published: July 2002

For the first time, an attempt has been made to quantify the effect of a copepod parasite (Ergasilus bengalensis) on the respiratory efficiency of the gills of a riverine catfish (Wallago attu) using an important parameter – the diffusing capacity. In addition, scanning electron microscopy has been used to demonstrate the effect of a monogeneid fluke on the gill lamellae of this catfish. The anchorage of E. bengalensis towards the leading edge of the interlamellar channels (pores) will affect laminar flow of water through the gill sieve. About 35% of the water flow (1.23×10−3 cm3/s) and lamellar area (15.41 mm2) of an infected gill filament (4.46 mm) is affected by the copepod parasite (1.59 mm). Other effects of the monogeneid flukes on the catfish included fusion of the tips of gill filaments and distortion of lamellar epithelium. Parasite‐induced changes in the branchial organization are discussed in relation to oxygen uptake efficiency of the gills of the catfish.
Prey and prey‐size selection by the short‐toed eagle (Circaetus gallicus) during the breeding season in Granada (south‐eastern Spain)
Authors: Gil José M. , Pleguezuelos Juan M.
Published: July 2002

The diet of the short‐toed eagle (Circaetus gallicus) was studied during the breeding season by analysing pellets and remains generated by adults and nestlings. The raptor proved to be a specialist feeder, as snake prey comprised almost 95% of the diet, in both frequency and biomass. We gathered information on prey availability and prey size availability (1499 specimens of nine different species) by searching for snakes in the study area. Regressions of vertebra centrum length and dorsal‐scale length on snout–vent length (SVL) of the snakes were used to calculate prey size. The taxonomic diet composition differed depending on the sample analysed – remains or pellets – but we failed to find between‐year diet differences. Most of the snakes identified (140 out of 141) belonged to only three species, Malpolon monspessulanus, Elaphe scalaris, and Coluber hippocrepis. Other prey included Lacerta lepida, Natrix maura, Bufo bufo, and Alectoris rufa, and many secondary prey (prey from stomach of the prey) were also detected in the pellets. The three main prey species were consumed according to their availability in the study area, but the eagles selected on the basis of prey size. Large snakes within 700–1000 mm SVL were positively selected, whereas snakes under 600 mm SVL were negatively selected. Adult eagles consumed the same prey species as those carried to the nest to feed their single nestling, although prey given to nestlings proved larger in size and biomass, suggesting that adults consumed the smallest prey, reserving the largest for nestlings.
Stress and development: Behavioral and biological consequences
Authors: BREMNER J. DOUGLAS , VERMETTEN ERIC
Published: July 2002

Childhood abuse is an important public health problem; however, little is known about the
effects of abuse on the brain and neurobiological development. This article reviews the behavioral
and biological consequences of childhood abuse and places them in a developmental context.
Animal studies show that both positive and negative events early in life can influence
neurobiological development in unique ways. Early stressors such as maternal separation result in
lasting effects on stress-responsive neurobiological systems, including the
hypothalamic–pituitary–adrenal (HPA) axis and noradrenergic systems. These
studies also implicate a brain area involved in learning and memory, the hippocampus, in the
long-term consequences of early stress. Clinical studies of patients with a history of abuse also
implicate dysfunction in the HPA axis and the noradrenergic and hippocampal systems; however,
there are multiple questions related to chronicity of stress, developmental epoch at the time of the
stressor, presence of stress-related psychiatric disorders including posttraumatic stress disorder
and depression, and psychological factors mediating the response to trauma that need to be
addressed in this field of research. Understanding the effects of abuse on the development of the
brain and neurobiology will nevertheless have important treatment and policy implications.
Moving boundary problems and non-uniqueness for the thin film equation
Authors: KING J. R. , BOWEN M.
Published: July 2002

A variety of mass preserving moving boundary problems for the thin film equation,
ut = −(unuxxx)x,
are derived (by formal asymptotics) from a number of regularisations, the case in
which the substrate is covered by a very thin pre-wetting film being discussed in most detail.
Some of the properties of the solutions selected in this fashion are described, and the full
range of possible mass preserving non-negative solutions is outlined.
Hypertension in the elderly
Authors: Scott Andrew K
Published: July 2002

Hypertension is a common problem in elderly people. The actual prevalence is uncertain and depends on the diagnostic methods used. Hypertension is an important factor in the two most common causes of death in elderly patients in the UK: heart disease and stroke. Next to age, hypertension is the most important risk factor for acute stroke and an important risk factor for ischaemic heart disease and cardiac failure. There are well defined methods of diagnosis and guidelines on management such as those issued by the British Hypertension Society (BHS). A new version is in preparation. Several trials have confirmed the benefits of treatment in older patients, particularly in terms of stroke reduction. Since the last review in this journal, in 1994, the most important developments have been the publication of more outcome studies, some of which have used calcium antagonists as first-line treatment. This review again focuses on the over-65 age group. Since there are still insufficient data in older subjects, information from research on younger patients has been included to support arguments for various aspects of management.
Sequent combinators: a Hilbert system for the lambda calculus
Authors: GOGUEN HEALFDENE , GOUBAULT-LARRECQ JEAN
Published: July 2002

This paper introduces Hilbert systems for λ-calculus, called sequent combinators, addressing
many of the problems of Hilbert systems that have led to the more widespread adoption of
natural deduction systems in computer science. This suggests that Hilbert systems, with their
uniform approach to meta-variables and substitution, may be a more suitable framework
than λ-calculus for type theories and programming languages. Two calculi are introduced
here. The calculus SKIn captures λ-calculus reduction faithfully, is confluent even in the
presence of meta-variables, is normalizing but not strongly normalizing in the typed case,
and standardizes. The sub-calculus SKInT captures λ-reduction in slightly less obvious ways,
and is a language of proof-terms not directly for intuitionistic logic, but for a fragment of S4
that we name near-intuitionistic logic. To our knowledge, SKInT is the first confluent,
first-order calculus to capture λ-calculus reduction fully and faithfully and be strongly
normalizing in the typed case. In particular, no calculus of explicit substitutions has yet
achieved this goal.
Recent advances in endometrial ablation
Authors: Parkin DE
Published: July 2002

The original title that I was given when asked to write this article was “Recent advances in endometrial resection”. Whilst there have been a number of recent important publications regarding the results and place of endometrial resection, there have been no advances in the technique itself. There have however been a number of recent advances in other methods of endometrial ablation. I therefore changed the title so as to encompass all the advances in this area and I use the term endometrial ablation to cover all methods of resecting or destroying the endometrium.
Hospital Ethics Committees in Paris
Authors: Mino Jean-Christophe
Published: July 2002

Even if the term bioethics is used all over
the world, its meanings are multiple and different,
especially between American and European countries, depending
on local cultural and medical contexts. These differences
concern the issues discussed or the institutional form
bioethics takes. In France, bioethics was used from the
end of the 1970s and focused on research ethics and issues
at the beginning of life. At the national level, a permanent
commission, the “national consultative ethics committee
on life sciences and health” (Comité Consultatif
National d'Ethique, CCNE) was created by President
François Mitterrand in 1983. Its recommendations
dealt essentially with procreative medicine and biomedical
research ethics.
Terminal Sedation as Palliative Care: Revalidating a Right
to a Good Death
Authors: SMITH GEORGE P.
Published: July 2002

Not everyone finds a “salvific meaning”
in suffering. Indeed, even those who do subscribe to this
interpretation recognize the responsibility of each
individual to show not only sensitivity and compassion
but render assistance to those in distress. Pharmacologic
hypnosis, morphine intoxication, and terminal sedation
provide their own type of medical “salvation”
to the terminally ill patient suffering unremitting pain.
More and more states are enacting legislation that recognizes
this need of the dying to receive relief through regulated
administration of controlled substances. Wider legislative
recognition of this need would go far toward allowing physicians,
in the exercise of their reasonable medical judgment, to
administer a range of narcotics and barbiturates to the
terminally ill without fear of legal sanctions. Sadly, social
attitudes and governmental concerns about the spread of drug
addiction provide an undeniable policy nexus that impedes unduly
a rational approach or exception for the treatment of pain
experienced by the dying.
Placentation in intrauterine growth retardation
Authors: Fox H
Published: July 2002

A baby may be small for a variety of reasons, but there are certain overt maternal and fetal factors which may lead to, or are associated with, a poor fetal growth rate. Pre-eminent amongst the maternal factors is severe pre-eclampsia and in women with this disease the smallness of the baby is almost certainly due to the inadequacy of the uteroplacental circulation. Other maternal factors of importance are cigarette smoking, drug abuse and certain infections such as malaria. The most obvious fetal factors associated with a low birth weight are congenital malformations and chromosomal abnormalities, and there the failure of the fetus to achieve a normal weight is clearly an expression of a generalised disorder of growth and is unrelated to the adequacy or otherwise of the placenta. If cases such as these are removed from consideration, there remains an important residue of unduly small infants who are delivered after an apparently uncomplicated pregnancy, are free from congenital malformations and have a normal karotype; it is this group which is considered here.
Evidence for impaired sentence comprehension in early Alzheimer's
disease
Authors: CROOT KAREN , HODGES JOHN R. , PATTERSON KARALYN
Published: July 2002

We investigated sentence comprehension in 46 patients
with probable minimal (very mild), mild, or moderate dementia
of the Alzheimer type (DAT), comparing their performance
on the Test for the Reception of Grammar (TROG), with that
of 20 age- and education-matched controls. Performance
on the TROG was generally related to dementia severity,
independent of lexicosemantic and working memory (digit
span) impairments, but related to at least 1 measure of
attention. Some patients in the minimal group showed sentence
comprehension deficits while others in the moderate group
did not, indicating that DAT may impair sentence comprehension
at the very earliest stages of disease, but that its effects
are heterogeneous. Patients were most impaired on sentences
with 2 propositions and noncanonical word order, suggesting
difficulties with both interpretative and postinterpretative
stages of sentence processing. Further investigation is
needed into the relationship between attentional processes,
interpretative and postinterpretative stages of syntactic
processing in DAT. (JINS, 1999, 5, 393–404.)
A mitochondrial DNA control region phylogeny of the Cervinae: speciation in Cervus and implications for conservation
Authors: Randi Ettore , Mucci Nadia , Claro‐Hergueta Françoise , Bonnet Amélie , Douzery Emmanuel J. P.
Published: July 2002

Sequences from complete mitochondrial control regions (mtDNA CR) were used to infer phylogenetic relationships in 25 Cervinae taxa. Cervus splits into clades that are partially discordant with current species delimitations. Nominate Cervus elaphus includes two divergent clades that must be referred to as species elaphus (European elaphoid deer) and canadensis (Eurasian and North American wapitoid deer). Cervus nippon splits into Japanese and continental plus Taiwan sika. Père David's deer is nested within Cervus, suggesting that Elaphurus should be merged with Cervus. European and Persian fallow deer are genetically divergent and distinct species. Sequence length varied due to a CR‐I insertion, tandemly repeated twice in rusa and sambar deer, sika and wapiti, and repeated up to six times in a clade of Japanese sika. Variable copy numbers of this repeat are also fixed in different sika subspecies, and could be used as a diagnostic marker for subspecies. Sequence variability at the mtDNA CR is informative for defining species and subspecies boundaries, and for locating the geographical origin of captive‐reared stocks. Natural and farmed populations of some species have been deeply affected by human management and the conservation of deer populations would be aided by the appropriate identification of the different evolutionary and taxonomic units.
Determining the species status of one of the world's rarest frogs: a conservation dilemma
Authors: Holyoake Andrew , Waldman Bruce , Gemmell Neil J.
Published: July 2002

New Zealand's native frogs (genusLeiopelma) are considered to be archaic amphibians of exceptional scientific interest that appear to have remained virtually unchanged for 160‐200 million years. They are among the rarest extant amphibians and are highly restricted in distribution, confined to isolated, highly disjunct, populations on the North Island and a few small offshore islands in Cook Strait. Previous investigations have suggested, based on patterns of allozyme variation, that the Stephens Island frog (Leiopelma hamiltoni) and Archey's frog (L. archeyi) are sister taxa to the exclusion of the Maud Island frog, a species in close geographical proximity to the Stephens Island frog and previously viewed as a population of this species. As a consequence of these data, a new species,L. pakeka, the Maud Island Frog, has been described. This new species definition has dramatically enhanced the conservation status ofL. hamiltoni, of which there are probably fewer than 150 individuals. In this study we re‐examine the systematics of the Leiopelmatidae using mtDNA sequence analyses. Partial 12 S ribosomal RNA and cytochromeb(Cytb) gene sequences were obtained for 57 frogs from six populations representing all four extantLeiopelmaspecies. Contrary to previous reports we findL. pakekaandL. hamiltonito be monophyletic. The amount of variation evident between these present species (<1% for Cytb) is comparable to that seen between populations ofL. archeyi. Based on these data, classification ofL. pakekaandL. hamiltonias separate species appears to be unwarranted, but they may be sufficiently distinct to warrant classification as evolutionarily significant units.
Costs of sexual traits: a mismatch between theoretical considerations and empirical evidence
Authors: KOTIAHO JANNE S.
Published: July 2002

Costs of sexual traits are of central importance to the theory of sexual selection. To qualify as a cost in line with theoretical models, empirical studies must demonstrate that sexual traits cause negative effects on one component of fitness of the trait bearer. Moreover, it must be demonstrated that the costs are differential such that negative effects on fitness are more severe for individuals in poor condition than for individuals in good condition. However, in the current literature, there is confusion over what qualifies as a cost, and costs are often anticipated based on findings of increased expenditure. Consequently, it seems that the generally accepted notion that sexual traits are costly is in fact based almost exclusively on indirect evidence and that direct empirical evidence is very scarce.
The Aberrant Cell Walls of Boron-Deficient Bean Root Nodules Have No Covalently Bound Hydroxyproline-/Proline-Rich Proteins
Authors: Bonilla I. , Mergold-Villasenor C. , Campos M. E. , Sanchez N. , Perez H. , Lopez L. , Castrejon L. , Sanchez F. , Cassab G. I.
Published: July 2002

B-deficient bean (Phaseolus vulgaris L.) nodules examined by light microscopy showed dramatic anatomical changes, mainly in the parenchyma region. Western analysis of total nodule extracts examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that one 116-kD polypeptide was recognized by antibodies raised against hydroxyproline-rich glycoproteins (HRGPs) from the soybean (Glycine max) seed coat. A protein with a comparable molecular mass of 116 kD was purified from the cell walls of soybean root nodules. The amino acid composition of this protein is similar to the early nodulin (ENOD2) gene. Immunoprecipitation of the soybean ENOD2 in vitro translation product showed that the soybean seed coat anti-HRGP antibodies recognized this early nodulin. Furthermore, we used these antibodies to localize the ENOD2 homolog in bean nodules. Immunocytochemistry revealed that in B-deficient nodules ENOD2 was absent in the walls of the nodule parenchyma. The absence of ENOD2 in B-deficient nodules was corroborated by performing hydroxyproline assays. Northern analysis showed that ENOD2 mRNA is present in B-deficient nodules; therefore, the accumulation of ENOD2 is not affected by B deficiency, but its assembly into the cell wall is. B-deficient nodules fix much less N2 than control nodules, probably because the nodule parenchyma is no longer an effective O2 barrier.
Rhamnogalacturonan α-d-Galactopyranosyluronohydrolase1
Authors: Mutter Margien , Beldman Gerrit , Pitson Stuart M. , Schols Henk A. , Voragen Alphons G.J.
Published: July 2002

A new enzyme, rhamnogalacturonan (RG) α-d-galactopyranosyluronohydrolase (RG-galacturonohydrolase), able to release a galacturonic acid residue from the nonreducing end of RG chains but not from homogalacturonan, was purified from an Aspergillus aculeatus enzyme preparation. RG-galacturonohydrolase acted with inversion of anomeric configuration, initially releasing β-d-galactopyranosyluronic acid. The enzyme cleaved smaller RG substrates with the highest catalytic efficiency. A Michaelis constant of 85 μm and a maximum reaction rate of 160 units mg−1 was found toward a linear RG fragment with a degree of polymerization of 6. RG-galacturonohydrolase had a molecular mass of 66 kD, an isoelectric point of 5.12, a pH optimum of 4.0, and a temperature optimum of 50°C. The enzyme was most stable between pH 3.0 and 6.0 (for 24 h at 40°C) and up to 60°C (for 3 h).
The Kinetics of Zeaxanthin Formation Is Retarded by Dicyclohexylcarbodiimide1
Authors: Heyde Sandra , Jahns Peter
Published: July 2002

The de-epoxidation of violaxanthin to antheraxanthin (Anth) and zeaxanthin (Zeax) in the xanthophyll cycle of higher plants and the generation of nonphotochemical fluorescence quenching in the antenna of photosystem II (PSII) are induced by acidification of the thylakoid lumen. Dicyclohexylcarbodiimide (DCCD) has been shown (a) to bind to lumen-exposed carboxy groups of antenna proteins and (b) to inhibit the pH-dependent fluorescence quenching. The possible influence of DCCD on the de-epoxidation reactions has been investigated in isolated pea (Pisum sativum L.) thylakoids. The Zeax formation was found to be slowed down in the presence of DCCD. The second step (Anth → Zeax) of the reaction sequence seemed to be more affected than the violaxanthin → Anth conversion. Comparative studies with antenna-depleted thylakoids from plants grown under intermittent light and with unstacked thylakoids were in agreement with the assumption that binding of DCCD to antenna proteins is probably responsible for the retarded kinetics. Analyses of the DCCD-induced alterations in different antenna subcomplexes showed that Zeax formation in the PSII antenna proteins was predominantly influenced by DCCD, whereas Zeax formation in photosystem I was nearly unaffected. Our data support the suggestion that DCCD binding to PSII antenna proteins is responsible for the observed alterations in xanthophyll conversion.