bluuebunny/crossref_metadata_2025 huggingface dataset:
Diabetes mellitus, anti-secretory drugs and other risk factors

for campylobacter gastro-enteritis in adults: a case-control study
Authors: NEAL K. R. , SLACK R. C. B.
Published: July 2002

The epidemiology of notified cases of campylobacter gastroenteritis

in adults in Nottingham

Health District was investigated using a case-control study with a

postal questionnaire to

ascertain data on risk factors. Over a 14-month period 531 cases (a

73% response rate of all laboratory confirmed cases) and 512 controls replied.

Conditional logistic regression analysis was used to determine

independent associations with

infection. These included foreign travel (odds ratio (OR) 3·4; 95%

confidence intervals (CI)

2·0–5·7), diabetes mellitus (OR 4·1, CI

1·1–17), medication with omeprazole (OR 3·5, CI

1·1–12)

and H2 and H2 antagonists (OR 3·7, CI

1·3–15), contact with puppies (OR11·3, CI1·2–105),

eating chicken (OR 1·4, CI 1·1–1·8) and drinking

milk from bottles with tops damaged by a

bird (OR 3·3, CI 1·0–11). Preparing main meals

(OR 0·9, CI 0·8–1·0) and drinking delivered

milk (OR 0·6, CI 0·4–0·9) were associated with
a

reduced risk of campylobacter infection.

Foreign travel was reported in 25% of cases and another 15% had

significant associations

with other risk factors. The majority of cases, 60%, remained unexplained,

indicating the need for further evolution of sporadic cases.
The epidemiology of measles in Poland: prevalence of measles virus antibodies in the population
Authors: JANASZEK W. , GUT W. , GAY N. J.
Published: July 2002

WHO has adopted a goal of eliminating indigenous measles from the European Region by the
year 2007. The strategy focuses on reducing the proportion of susceptible individuals in the
population to low levels and maintaining these low levels of susceptibility. Routine vaccination
against measles for children aged 13–15 months was introduced in Poland in 1975, and a
second dose added in 1991. High coverage (> 95%) is achieved with both doses. In order to
assess progress towards measles elimination in Poland, a serological survey was performed to
evaluate the impact of vaccination on the susceptibility profile of population. Three thousand
residual serum samples from individuals aged 1–30 years were collected from hospitals in six
selected voivodeships (administration units) in Poland. These were tested for measles-specific
IgG using a commercial ELISA. Overall 4% (120/3000) were negative for measles virus
antibody. The highest proportion of negatives (8·2%) occurred among cohorts born 1977–81 –
the only cohorts in which susceptibility exceeded the WHO targets. ‘Catch-up’ vaccination
strategies should target these cohorts.
Inhibitory basket cell synaptic input to layer IV simple
cells in cat striate visual cortex (area 17): A quantitative
analysis of connectivity
Authors: BUDD JULIAN M.L.
Published: July 2002

In the absence of a direct and specific marker
for basket cells, the aim of this paper was to use available
data to estimate the density of basket cell synaptic input
to smooth and spiny neurons within layer IV of cat striate
visual cortex (area 17). A linear quantitative analysis
of layer IV basket cell connectivity data suggests that
on average basket cells (1) comprise 25–35% of all
GABAergic neurons in layer IV (3552–4736 cells mm−3),
(2) account for 30–41% of all putative inhibitory
dendritic synapses of layer IV spiny stellate cells (145–195
synapses cell−1) and a similar proportion
of layer IV basket cells (25–37%, 71–107 synapses
cell−1), and (3) provide each layer IV
spiny cell with 13–45 axons and each layer IV basket
cell with 6–29 axons. These estimates suggest that
basket cells may be less common and provide a smaller proportion
of the dendritic synaptic input to layer IV spiny and smooth
neurons than previously thought. In addition, the analysis
indicates that a layer IV spiny stellate cell may receive
on average as many synapses and axons from layer IV basket
cells as from lateral geniculate relay cells. Based on
this potential numerical similarity, a geniculate-basket
synaptic pairing in a spine-shaft microcircuit is hypothesized.
This microcircuit could implement a type of local (dendritic)
push–pull interaction underlying subfield antagonism.
Direct imaging of NMDA-stimulated nitric oxide production
in the retina
Authors: BLUTE TODD A. , LEE MICHAEL R. , ELDRED WILLIAM D.
Published: July 2002

In the retina, nitric oxide (NO) functions in network
coupling, light adaptation, neurotransmitter receptor function,
and synaptic release. Neuronal nitric oxide synthase (nNOS)
is present in the retina of every vertebrate species investigated.
However, although nNOS can be found in every retinal cell
type, little is known about the production of NO in specific
cells or about the diffusion of NO within the retina. We
used diaminofluorescein-2 (DAF-2) to image real-time NO
production in turtle retina in response to stimulation
with N-methyl-D-aspartate (NMDA). In response to NMDA,
NO was produced in somata in the ganglion cell and inner
nuclear layers, in synaptic boutons and processes in the
inner plexiform layer, in processes in the outer plexiform
layer, and in photoreceptor inner segments. This NO-dependent
fluorescence production quickly reached transient peaks
and declined more slowly toward baseline levels at different
rates in different cells. In some cases, the NO signal
was primarily confined to within 10 μm of the source,
which suggests that NO may not diffuse freely through the
retina. Such limited spread was not predicted and suggests
that NO signal transduction may be more selective than
suggested, and that NO may play significant intracellular
roles in cells that produce it. Because NO-dependent fluorescence
within amacrine cells can be confined to the soma, specific
dendritic sites, or both with distinct kinetics, NO may
function at specific synapses, modulate gene expression,
or coordinate events throughout the cell.
Morphology of wide-field bistratified and diffuse human
retinal ganglion cells
Authors: PETERSON BETH B. , DACEY DENNIS M.
Published: July 2002

To study the detailed morphology of human retinal
ganglion cells, we used intracellular injection of horseradish
peroxidase and Neurobiotin to label over 1000 cells in
an in vitro, wholemount preparation of the human
retina. This study reports on the morphology of 119 wide-field
bistratified and 42 diffuse ganglion cells. Cells were
analyzed quantitatively on the basis of dendritic-field
size, soma size, and the extent of dendritic branching.
Bistratified cells were similar in dendritic-field diameter
(mean ± s.d. = 682 ± 130 μm)
and soma diameter (mean ± s.d. = 18 ±
3.3 μm) but showed a broad distribution in the extent
of dendritic branching (mean ± s.d. branch
point number = 67 ± 32; range = 15–167). Differences
in the extent of branching and in dendritic morphology
and the pattern of branching suggest that the human retina
may contain at least three types of wide-field bistratified
cells. Diffuse ganglion cells comprised a largely homogeneous
group whose dendrites ramified throughout the inner plexiform
layer. The diffuse cells had similar dendritic-field diameters
(mean ± s.d. = 486 ± 113 μm),
soma diameters (mean ± s.d. = 16 ±
2.3 μm), and branch points numbers (mean ± s.d.
= 92 ± 32). The majority had densely branched dendritic
trees and thin, very spiny dendrites with many short, fine,
twig-like thorny processes. Five of the diffuse cells had
much more sparsely branched dendritic trees (<50 branch
points) and less spiny dendrites, suggesting that there
are possibly two types of diffuse ganglion cells in human
retina. Although the presence of a diversity of large bistratified
and diffuse ganglion cells has been observed in a variety
of mammalian retinas, little is known about the number
of cell types, their physiological properties, or their
central projections. Some of the human wide-field bistratified
cells in the present study, however, show morphological
similarities to monkey large bistratified cells that are
known to project to the superior colliculus.
Voltage-gated Na+ channel EOIII-segment-like
immunoreactivity in fish retinal ganglion cells
Authors: YOSHIKAWA MASAYASU , ANDERSON KAJ , SAKAGUCHI HIRONOBU , FLANNERY JOHN G. , FITZGERALD PAUL G. , ISHIDA ANDREW T.
Published: July 2002

Although single-channel and whole-cell patch-clamp
recordings have demonstrated the presence of Na+
currents in retinal ganglion cell somata, it has not previously
been reported that an anti-Na+-channel antiserum
stains both retinal ganglion cell somata and
proteins with molecular weights corresponding to complexes
of α and β subunits. We probed adult goldfish retinas
for Na+ channel-like immunoreactivity with a
polyclonal antibody directed against the EOIII segment
of vertebrate voltage-gated Na+ channels. In
vertical sections and whole mounts, this antibody consistently
stained the somata, axons, and proximal dendrites of retinal
ganglion cells. Some somata in the proximal third of the
inner nuclear layer were also stained. In Western blots,
this antibody specifically stained multiple protein bands
from retina and optic nerve, all with apparent molecular
weights between 200 and 315 kDa. The largest of these molecular
weights agrees with that reported previously for complexes
of α and β subunits in mammalian neurons, including
retinal ganglion cells. The intermediate and lowest molecular
weights are consistent with the presence of multiple Na+
channel α subunits, either in individual proximal retinal
neurons or in different morphological subtypes.
Cellular proliferation and neurogenesis in the injured retina
of adult zebrafish
Authors: CAMERON DAVID A.
Published: July 2002

The retinas of adult teleost fish can regenerate neurons
following a chemical or mechanical injury. Previous studies
have demonstrated that mechanical excision of fish retina
induces a hyperplasia within the retinal sheet, including
the formation of a proliferative blastema from whence new
retinal cells are produced to fill the excision site. The
current study was designed to address two issues regarding
injury-induced retinal hyperplasia: (1) Retinas of adult
zebrafish can regenerate following a surgical excision,
but compared to other fish they contain very few proliferative
cells: Might retinal injury in adult zebrafish therefore
induce minimal, or perhaps no, hyperplasia? (2) The fate
of injury-induced, proliferative retinal cells outside
surgical excision sites has yet to be determined. Do such
cells produce retinal neurons? Evidence is presented that
mechanical injury to the adult zebrafish retina induces
a dramatic increase in the number of proliferative cells
both within and external to the lesion site, and some of
these cells apparently migrate within the radial dimension
of the retina. Evidence is also presented that injury-induced
proliferative cells outside a lesion site can produce retinal
neurons—including cone photoreceptors, interplexiform
cells, and amacrine cells—that are incorporated into
the extant retina. The results suggest that the adult zebrafish
retina contains a latent population of cells that is induced
to proliferate following retinal injury, and that these cells
might represent a novel avenue for pluripotent neurogenesis
within the intact adult teleost retina.
Long-term maturation of visual pathways
Authors: MADRID M. , CROGNALE M.A.
Published: July 2002

Previous research in adults has demonstrated the utility
of the visual evoked potential (VEP) to measure the integrity
of the chromatic and achromatic visual pathways. The VEP
has also been shown to be a valuable indicator of maturation
of these pathways in infants up to 1 year of age. The present
manuscript reports changes in the visual pathways from
2 years to adulthood as measured by the spatio-chromatic
VEP. The responses to achromatic reversal stimuli designed
to preferentially activate the low spatial-frequency achromatic
(luminance) pathways appear adult-like by 1 year of age.
The responses to low spatial-frequency isoluminant onset
stimuli designed to preferentially activate the chromatic
pathway do not appear as they do in the adult until after
12–13 years of age. The shapes of the chromatic VEP
waveforms shift from a positive–negative complex
to a negative–positive complex. These changes can
be modeled by a decrease in the latency of a large negative
component between the ages of 1 year and adulthood. The
results suggest that for low spatial-frequency stimuli,
there are long-term changes in the development of the chromatic
pathways that are not observed in the low spatial-frequency
achromatic pathways. The changes in the chromatic VEP waveforms
with age may be a physiological correlate of reported behavioral
changes.
On the performance of biological movement detectors and
ideal velocity sensors in the context of optomotor course
stabilization
Authors: WARZECHA ANNE-KATHRIN , EGELHAAF MARTIN
Published: July 2002

It is often assumed that the ultimate goal of a
motion-detection system is to faithfully represent the
time-dependent velocity of a moving stimulus. This assumption,
however, may be an arbitrary standard since the requirements
for a motion-detection system depend on the task that is
to be solved. In the context of optomotor course stabilization,
the performance of a motion-sensitive neuron in the fly's
optomotor pathway and of a hypothetical velocity sensor
are compared for stimuli as are characteristic of a normal
behavioral situation in which the actions and reactions
of the animal directly affect its visual input. On average,
tethered flies flying in a flight simulator are able to
compensate to a large extent the retinal image displacements
as are induced by an external disturbance of their flight
course. The retinal image motion experienced by the fly
under these behavioral closed-loop conditions was replayed
in subsequent electrophysiological experiments to the animal
while the activity of an identified neuron in the motion
pathway was recorded. The velocity fluctuations as well
as the corresponding neuronal signals were analyzed with
a statistical approach taken from signal-detection theory.
An observer scrutinizing either signal performs almost
equally well in detecting the external disturbance.
Plasticity of neuronal response properties in adult cat
striate cortex
Authors: MCLEAN J. , PALMER L.A.
Published: July 2002

We have utilized an associative conditioning paradigm
to induce changes in the receptive field (RF) properties
of neurons in the adult cat striate cortex. During conditioning,
the presentation of particular visual stimuli were repeatedly
paired with the iontophoretic application of either GABA
or glutamate to control postsynaptic firing rates. Similar
paradigms have been used in kitten visual cortex to alter
RF properties (Fregnac et al., 1988, 1992; Greuel et al.,
1988; Shulz & Fregnac, 1992). Roughly half of the cells
that were subjected to conditioning with stimuli differing
in orientation were found to have orientation tuning curves
that were significantly altered. In general, the modification
in orientation tuning was not accompanied by a shift in
preferred orientation, but rather, responsiveness to stimuli
at or near the positively reinforced orientation was increased
relative to controls, and responsiveness to stimuli at
or near the negatively reinforced orientation was decreased
relative to controls. A similar proportion of cells that
were subjected to conditioning with stimuli differing in
spatial phase were found to have spatial-phase tuning curves
that were significantly modified. Conditioning stimuli
typically differed by 90 deg in spatial phase, but modifications
in spatial-phase angle were generally 30–40 deg.
An interesting phenomenon we encountered was that during
conditioning, cells often developed a modulated response
to counterphased grating stimuli presented at the null
spatial phase. We present an example of a simple cell for
which the shift in preferred spatial phase measured with
counterphased grating stimuli was comparable to the shift
in spatial phase computed from a one-dimensional Gabor
fit of the space-time RF profile. One of ten cells tested
had a significant change in direction selectivity following
associative conditioning. The specific and predictable
modifications of RF properties induced by our associative
conditioning procedure demonstrate the ability of mature
visual cortical neurons to alter their integrative properties.
Our results lend further support to models of synaptic
plasticity where temporal correlations between presynaptic
and postsynaptic activity levels control the efficiency
of transmission at existing synapses, and to the idea that
the mature visual cortex is, in some sense, dynamically
organized.
V4 lesions in macaques affect both single- and multiple-viewpoint
shape discriminations
Authors: MERIGAN WILLIAM H. , PHAM HONG AN
Published: July 2002

The role of cortical area V4 in complex shape discriminations
was studied by testing the effects of V4 lesions in macaques
on the ability to visually discriminate between images
of three-dimensional (3D) objects from different viewpoints.
Stimuli were presented in pairs in the lower left or lower
right visual field quadrants about 4 deg from the fovea,
and the monkeys judged on each trial whether the two views
were of the same or of different objects. Object similarity
was varied to determine a threshold shape difference. V4
lesions caused profound, retinotopic, and apparently permanent
disruptions of discrimination, regardless of whether the
images represented single or multiple viewpoints. In V4
lesioned portions of the visual field, monkeys could discriminate
objects only when they differed much more grossly in shape
than was true in control locations. These effects of the
lesion were virtually identical for discriminations that
had been learned before lesions were placed and for those
learned afterwards. As in previous studies, V4 lesions
elevated contrast thresholds by approximately a factor
of two, but control observations showed that this was not
the basis of the disruption of shape discrimination. Manipulation
of cues to shape showed that in control locations, monkeys
maintained excellent shape discrimination despite a variety
of stimulus alterations, whereas in V4 lesioned areas their
performance was easily disrupted. This finding suggests
that V4 may support visual shape discriminations by facilitating
the use of multiple visual cues. However, the fact that
single-viewpoint and multiple-viewpoint discriminations
were similarly affected indicates that the disruption was
not specific to 3D shape discrimination, but may apply
to a variety of subtle discriminations.
The kinetics of tracer movement through homologous gap junctions
in the rabbit retina
Authors: MILLS STEPHEN L. , MASSEY STEPHEN C.
Published: July 2002

Observation of the spread of biotinylated or fluorescent
tracers following injection into a single cell has become
one of the most common methods of demonstrating the presence
of gap junctions. Nevertheless, many of the fundamental
features of tracer movement through gap junctions are still
poorly understood. These include the relative roles of
diffusion and iontophoretic current, and under what conditions
the size of the stained mosaic will increase, asymptote,
or decline. Additionally, the effect of variations in amount
of tracer introduced, as produced by variation in electrode
resistance following cell penetration, is not obvious.
To examine these questions, Neurobiotin was microinjected
into the two types of horizontal cell of the rabbit retina
and visualized with streptavidin-Cy3. Images were digitally
captured using a confocal microscope. The spatial distribution
of Neurobiotin across the patches of coupled cells was
measured. Adequate fits to the data were obtained by fitting
to a model with terms for diffusion and amount of tracer
injected. Results indicated that passive diffusion is the
major source of tracer movement through gap junctions,
whereas iontophoretic current played no role over the range
tested. Fluorescent visualization, although slightly less
sensitive than peroxidase reactions, produced staining
intensities with a more useful dynamic range. The rate
constants for movement of Neurobiotin between A-type horizontal
cells was about ten times greater than that for B-type
horizontal cells. Although direct extrapolation to ion
conductances cannot be assumed, tracer movement can be
used to give an estimate of relative coupling rates across
cell types, retinal location, or modulation conditions
in intact tissue.
Developmental expression of the rat rod photoreceptor cGMP-gated
cation channel
Authors: CHIANG ROBERT K. , BARNSTABLE COLIN J.
Published: July 2002

The appearance of cGMP-gated cation channel protein
in the postnatal rat retina has been studied by fluorescence
immunocytochemistry of radial retinal sections and immunoblots
of retinal membrane proteins. Channel immunoreactivity
was first detectable with RCNGC1-7H2 monoclonal antibody
at postnatal day 7 (PN7) by both methods. Immunocytochemical
label in retinal sections was localized to the outer segments,
and immunoreactivity increased with increasing age. We
also compared the developmental appearance of the cGMP-gated
cation channel to that of other phototransduction proteins
and developmental markers. RET-P2, a monoclonal antibody
recognizing the 39-kDa rds/peripherin disc protein, first
labeled outer segments at PN7, coincident with cGMP-gated
cation channel expression. Double labeling of the same
section of PN7 rat retina with RET-P2 and R309 (a polyclonal
antiserum against the rod cGMP-gated cation channel) revealed
identical patterns of labelling. Similarly, double labeling
with RCNGC1-7H2 and an antibody against the rod cGMP-phosphodiesterase
gave coincident labeling, suggesting coordinate expression
mechanisms of phototransduction proteins with each other
and with outer segment structural proteins.
A phenomenological model of visually evoked spike trains
in cat geniculate nonlagged X-cells
Authors: GAZÈRES NICOLAS , BORG-GRAHAM LYLE J. , FRÉGNAC YVES
Published: July 2002

The visual information that first-order cortical
cells receive is contained in the visually evoked spike
trains of geniculate relay cells. To address functional
issues such as the ON/OFF structure of visual cortical
receptive fields with modelling studies, a geniculate cell
model is needed where the spatial and temporal characteristics
of the visual response are described quantitatively. We
propose a model simulating the spike trains produced by
cat geniculate nonlagged X-cells, based on a review of
the electrophysiological literature. The level of description
chosen is phenomenological, fitting the dynamics and amplitude
of phasic and tonic responses, center/surround antagonism,
surround excitatory responses, and the statistical properties
of both spontaneous and visually evoked spike trains. The
model, which has been constrained so as to reproduce the
responses to centered light spots of expanding size and
optimal light and dark annuli, predicts responses to thin
and large bars flashed in various positions of the receptive
field. The switching gamma renewal process method has been
introduced for modelling spontaneous and visually evoked
spike trains within the same mathematical framework. The
statistical structure of the spike process is assumed to
be more regular during phasic than tonic visual responses.
On the whole, this model generates more realistic geniculate
input to cortex than the currently used retinal models.
Visual response latencies of magnocellular and parvocellular
LGN neurons in macaque monkeys
Authors: MAUNSELL JOHN H.R. , GHOSE GEOFFREY M. , ASSAD JOHN A. , McADAMS CARRIE J. , BOUDREAU CHRISTEN ELIZABETH , NOERAGER BRETT D.
Published: July 2002

Signals relayed through the magnocellular layers
of the LGN travel on axons with faster conduction speeds
than those relayed through the parvocellular layers. As
a result, magnocellular signals might reach cerebral cortex
appreciably before parvocellular signals. The relative
speed of these two channels cannot be accurately predicted
based solely on axon conduction speeds, however. Other
factors, such as different degrees of convergence in the
magnocellular and parvocellular channels and the retinal
circuits that feed them, can affect the time it takes for
magnocellular and parvocellular signals to activate cortical
neurons. We have investigated the relative timing of visual
responses mediated by the magnocellular and parvocellular
channels. We recorded individually from 78 magnocellular
and 80 parvocellular neurons in the LGN of two anesthetized
monkeys. Visual response latencies were measured for small
spots of light of various intensities. Over a wide range
of stimulus intensities the fastest magnocellular response
latencies preceded the fastest parvocellular response latencies
by about 10 ms. Because parvocellular neurons are far more
numerous than magnocellular neurons, convergence in cortex
could reduce the magnocellular advantage by allowing parvocellular
signals to generate detectable responses sooner than expected
based on the responses of individual parvocellular neurons.
An analysis based on a simple model using neurophysiological
data collected from the LGN shows that convergence in cortex
could eliminate or reverse the magnocellular advantage.
This observation calls into question inferences that have
been made about ordinal relationships of neurons based
on timing of responses.
Morphology of wide-field, monostratified ganglion cells
of the human retina
Authors: PETERSON BETH B. , DACEY DENNIS M.
Published: July 2002

To determine the number of wide-field, monostratified
ganglion cell classes present in the human retina, we analyzed
a large sample of ganglion cells by intracellular staining
in an in vitro, whole-mount preparation of the
retina. Over 1000 cells were labeled by horseradish peroxidase
or Neurobiotin; some 200 cells had wide dendritic trees
narrowly or broadly stratified within either the inner
(ON) or outer (OFF) portion of the inner plexiform layer.
Based on dendritic-field size and the pattern and extent
of dendritic branching, we have distinguished six wide-field
cell groups. The giant very sparse ganglion cells included
both inner and outer stratifying cells and were unique
both for their extremely large dendritic field (mean diameter
= 1077 μm) and extremely sparsely branched dendrites.
Four of the cell groups had similarly large dendritic fields,
ranging in mean diameter from 737 to 791 μm, but differed
in the pattern and extent of dendritic branching, with
the number of dendritic branch points ranging from a mean
of 33 to 129. Of these four groups, the large very sparse
group and the large dense group included both inner and
outer stratifying cells, while the large sparse and large
moderate groups consisted of inner stratifying cells only.
The thorny monostratified ganglion cells were distinct
from the other cells in having medium size dendritic fields
(mean diameter = 517 μm) and moderately branched, inner
stratifying dendritic trees with many thin, spiny, twig-like
branchlets. All six groups had medium-size cell bodies,
with mean soma diameters ranging from 17 to 21 μm.
Though the physiological properties and central projections
of human wide-field, monostratified ganglion cells are
not known, some of the cells resemble macaque ganglion
cells known to project to the lateral geniculate nucleus,
the pretectum, or the superior colliculus.
Different types of synapses with different spectral types of cones
underlie color opponency in a bipolar cell of the turtle retina
Authors: HAVERKAMP SILKE , MÖCKEL WOLFGANG , AMMERMÜLLER JOSEF
Published: July 2002

Electrophysiologically, color-opponent retinal
bipolar cells respond with opposite polarities to stimulation
with different wavelengths of light. The origin of these
different polarities in the same bipolar cell has always
been a mystery. Here we show that an intracellularly recorded
and HRP-injected, red-ON, blue/green-OFF bipolar cell of
the turtle retina made invaginating (ribbon associated)
synapses exclusively with L-cones. Non-invaginating synapses
resembling wide-cleft basal junctions were made exclusively
with M-cones. Input from S-cones was not seen. From these
results we suggest sign-inverting transmission from L-cones
at invaginating synapses via metabotropic glutamate
receptors, and sign-conserving transmission from M-cones
at wide-cleft basal junctions via ionotropic receptors.
To explain the pronounced blue sensitivity of the bipolar
cell, computer simulations were performed using a sign-conserving
input from a yellow/blue chromaticity-type (H3) horizontal
cell. The response properties of the red-ON, blue/green-OFF
bipolar cell could be quantitatively reproduced by this
means. The simulation also explained the asymmetry in L-
and M-cone inputs to the bipolar cell as found in the ultrastructural
analysis and assigned a putative role to H3 horizontal
cells in color processing in the turtle retina.
Dual actions of isthmic input to tectal neurons in a reptile,
Gekko gekko
Authors: GEORGE STEPHEN A. , WU GANG-YI , LI WEN-CHANG , WANG SHU-RONG
Published: July 2002

We analyzed postsynaptic potentials and dye-labeled
morphology of tectal neurons responding to electrical stimulation
of the optic nerve and of the nucleus isthmi in a reptile,
Gekko gekko, in order to compare with previously
reported interactions between the optic tectum and the
nucleus isthmi in amphibians and birds. The results indicate
that isthmic stimulation exerts inhibitory and excitatory
actions on tectal cells, similar to dual isthmotectal actions
in amphibians. It appears that dual actions of the isthmotectal
pathway in amphibians and reptiles are shared by two subdivisions
of the nucleus isthmi in birds. The morphology of tectal
cells responding to isthmic stimulation is generally similar
to that of tectoisthmic projecting neurons, but they differ
particularly in that some tectoisthmic cells bear numerous
varicosities whereas cells receiving isthmic afferents
do not. Thus, it is likely that at least some tectoisthmic
cells may not be in the population of tectal cells that
can be affected by isthmic stimulation. Forty-four percent
of injections resulted in dye-coupled labeling, suggesting
extensive electrical connections between tectal cells in
reptiles.
Circadian control of photoreceptor outer segment membrane
turnover in mice genetically incapable of melatonin synthesis
Authors: GRACE MICHAEL S. , CHIBA ATSUHIKO , MENAKER MICHAEL
Published: July 2002

Vertebrate retinal photoreceptors periodically
shed membrane from their outer segment distal tips; this
material is phagocytosed and degraded by the retinal pigmented
epithelium. Both a circadian oscillator and the daily light–dark
cycle affect disk shedding, and the effects of both may
be mediated by melatonin. To clarify melatonin's role
in this process, we asked whether endogenous melatonin
is required for rhythmic disk shedding in mouse retina.
We analyzed disk shedding in two mouse strains: C3H, which
produce melatonin in retina and pineal under the control
of circadian oscillators, and C57BL/6, which do not produce
melatonin. In cyclic light, both strains exhibited a robust
cycle of disk phagosome content in the pigmented epithelium.
Peak shedding occurred just after dawn, and trough levels
occurred during the middle of the dark phase. In constant
darkness, mice exhibited circadian rhythms of locomotor
activity, the characteristics of which were similar between
strains. Both strains also exhibited rhythmic disk shedding
in constant darkness, although amplitudes of the rhythms
were damped. Exogenous melatonin delivered once per day
failed to reestablish high-amplitude cyclic shedding in
mice held in constant darkness. Our results show that,
while disk shedding in cyclic light is robustly rhythmic,
neither rhythmic production of melatonin nor the circadian
oscillator responsible for rhythmic locomotor activity
is sufficient to drive high-amplitude rhythmic shedding
in constant darkness. More importantly, melatonin is required
neither for cyclic changes in the rate of disk shedding
in cyclic light, nor for the circadian rhythm of disk shedding
in constant darkness.
Modulation of voltage-dependent K+ currents (IK(V)) in retinal bipolar
cells by ascorbate is mediated by dopamine D1 receptors
Authors: FAN SHIH-FANG , YAZULLA STEPHEN
Published: July 2002

Ascorbic acid (AA), a neuromodulator in the vertebrate
CNS, is released from glutamatergic neurons in exchange
with glutamate uptake and, in turn, modulates the release
of both glutamate and dopamine. We have reported that voltage-gated
K+ currents (IK(V))
in ON-mixed rod/cone bipolar cells (Mb) were suppressed
60% by 100–200 μM AA when added to an ascorbate-free
solution. However, as the in vivo [AA]o
in retina is about 200 μM, we studied the effects of changes in [AA]o on IK(V)
when [AA]o was varied around a baseline concentration
of 200 μM. Whole-cell currents were recorded with patch-clamp methods
from goldfish Mb cells in retinal slices, bathed in a solution
containing 200 μM AA. We found that (1)
IK(V) was enhanced (180 ±
36%, n = 9) by increases of [AA]o
less than 40 μM with an average latency of 8 min. (2)
However, IK(V) was
suppressed without an appreciable latent period by two
conditions: increases more than 40 μM [AA]o
and decreases by any amount greater than 10 μM. (3)
Effects of Δ[AA]o on
IK(V) were blocked by a D1 dopamine
receptor antagonist, SCH 23390, but not by a D2 receptor
antagonist, spiperone. Increased concentrations of a D1
agonist (SKF 38390) and dopamine had similar concentration-dependent
effects on IK(V) as
did AA, even in the presence of 200 μM ascorbate.
Ascorbate has complicated concentration-dependent effects
on IK(V) of Mb cells
in vitro that were mediated by D1 dopamine receptors,
suggesting that dopamine and ascorbate may be involved
reciprocally in modulating IK(V),
with consequences on the transmission of rod signals to
the inner retina.
Neural plasticity and emotional memory
Authors: POST R. M. , WEISS S. R. B. , LI H. , SMITH M. A. , ZHANG L. X. , XING G. , OSUCH E. A. , MCCANN U. D.
Published: July 2002

Posttraumatic stress disorder is the
pathological replay of emotional memory formed in response to painful, life-threatening, or
horrifying events. In contrast, depression is often precipitated by more social context-related
stressors. New data suggest that different types of life experiences can differentially impact
biochemistry, physiology, anatomy, and behavior at the level of changes in gene expression.
Repeated separation of neonatal rat pups from their mother results in many long-lasting
alterations in biology and behavior paralleling that in depression, including hypercortisolism.
The role of the amygdala in modulating emotional memory is highlighted, as well as some of its
unique properties such as metaplasticity (i.e., the differential direction of long-term adaptation,
either potentiation or depression) in response to the same input as a function of the prior history
of stimulation. The implications of these emerging data on the physiological and molecular
mechanisms underlying emotional memory emphasize the particular importance of prevention
and early intervention.
Bee: an integrated development environment for the Scheme programming language
Authors: SERRANO MANUEL
Published: July 2002

The Bee is an integrated development environment for the Scheme programming language.
It provides the user with a connection between Scheme and the C programming language, a
symbolic debugger, a profiler, an interpreter, an optimizing compiler that delivers stand alone
executables, a source file browser, a project manager, user libraries and online documentation.
This article details the facilities of the Bee, its user interface, and presents an overview of the
implementation of its main components.
FUNCTIONAL PEARL Lazy wheel sieves and spirals of primes
Authors: RUNCIMAN COLIN
Published: July 2002

The popular method of enumerating the primes is the Sieve of Eratosthenes.
It can
be programmed very neatly in a lazy functional language, but runs rather slowly.
A little-known alternative method is the Wheel Sieve, originally formulated as a
fast imperative algorithm for obtaining all primes up to a given limit, assuming
destructive access to a bit-array. This article describes functional variants
of the wheel sieve that enumerate all primes as a lazy list.
Explaining binomial heaps
Authors: HINZE RALF
Published: July 2002

Functional programming languages are an excellent tool for teaching algorithms and
data structures. This paper explains binomial heaps, a beautiful data structure for
priority queues, using the functional programming language Haskell (Peterson and
Hammond, 1997). We largely follow a deductive approach: using the metaphor of a
tennis tournament we show that binomial heaps arise naturally through a number
of logical steps. Haskell supports the deductive style of presentation very well: new
types are introduced at ease, algorithms can be expressed clearly and succinctly,
and Haskell's type classes allow to capture common algorithmic patterns. The paper
aims at the level of an undergraduate student who has experience in reading and
writing Haskell programs, and who is familiar with the concept of a priority queue.
Physical capabilities, exercise and aging
Authors: Bassey EJ
Published: July 2002

Being able to perform physically at a level which ensures a
satisfying and independent life is taken for granted in youth, but it
comes under threat as physical capabilities deteriorate with advancing
age. An independent lifestyle requires muscle strength, muscle power,
cardiorespiratory endurance, as well as balance and motivation. It used
to be assumed that deterioration in these capabilities with the passage
of time in later life was inevitable. Now it is clear that much of the
deterioration is due to reduced levels of physical activity. This means
that it can be reversed. If physical activity increases so do physical
capabilities, even in extreme old age.
Population sizes, status and habitat associations of forest birds in Chu Yang Sin Nature Reserve, Dak Lak Province, Vietnam
Authors: HILL MIKE , EAMES JONATHAN C. , TRAI LE TRONG , CU NGUYEN
Published: July 2002

Chu Yang Sin Nature Reserve, Dak Lak Province, Vietnam, is within an area of high bird endemism and supports a
number of globally threatened and restricted-range species. Data were collected on the bird communities of the Reserve
and their habitat in 1995, to ascertain habitat associations of some of the endemic and threatened taxa. Birds were
surveyed in circular plots around a recording point. Habitat associations were investigated using Discriminant Function
analysis, and populations estimated using DISTANCE.

Seven restricted-range species and 38 restricted-range subspecies were recorded in the survey. The number of
contacts with some of the endemic species was low, which limited the statistical investigation of the habitat require
ments of these species. When analysis was possible, altitude was the most important of the factors measured determining species distributions, while measures of forest architecture seemed less important. The area appears to support
important populations of several restricted-range taxa and, provided that protection and management of the protected
area can be enhanced, it remains one of the most important areas for bird conservation in southern Vietnam. Some
drawbacks of the techniques used in the survey are discussed.
Double-pushout graph transformation revisited
Authors: HABEL ANNEGRET , MÜLLER JÜRGEN , PLUMP DETLEF
Published: July 2002

In this paper we investigate and compare four variants of the double-pushout approach to
graph transformation. As well as the traditional approach with arbitrary matching and
injective right-hand morphisms, we consider three variations by employing injective
matching and/or arbitrary right-hand morphisms in rules. We show that injective matching
provides additional expressiveness in two respects: for generating graph languages by
grammars without non-terminals and for computing graph functions by convergent graph
transformation systems. Then we clarify for each of the three variations whether the
well-known commutativity, parallelism and concurrency theorems are still valid and – where
this is not the case – give modified results. In particular, for the most general approach with
injective matching and arbitrary right-hand morphisms, we establish sequential and parallel
commutativity by appropriately strengthening sequential and parallel independence.
Non-commutative logic II: sequent calculus and phase semantics
Authors: RUET PAUL
Published: July 2002

Non-commutative logic, which is a unification of commutative linear logic and cyclic linear
logic, is extended to all linear connectives: additives, exponentials and constants. We give two
equivalent versions of the sequent calculus (directly with the structure of order varieties, and
with their presentations as partial orders), phase semantics and a cut-elimination theorem.
This involves, in particular, the study of the entropy relation between partial orders, and the
introduction of a special class of order varieties: the series–parallel order varieties.
Effect of gap junction uncoupling in full-grown Bufo arenarum ovarian follicles: participation of cAMP in meiotic arrest
Authors: Villecco Evelina I. , Aybar Manuel J. , Genta Susana B. , Sánchez Sara S. , Riera Alicia N. Sánchez
Published: July 2002

The aim of the present study was to determine the presence of the connexins Cx43, Cx32 and Cx26 in Bufo arenarum ovarian follicles during the breeding season as well as to analyse the possible alterations in the meiotic process when connexins are blocked by specific antibodies. Western blot analysis revealed that the Cx43 and Cx32 proteins were present but not Cx26. We demonstrated that the anti-Cx43 and anti-Cx32 antibodies produced the uncoupling of the gap junctions. When these junctions are blocked the maturation process is triggered in the oocytes. We determined that dbcAMP exerts an inhibitory effect on the maturation induced by the uncoupling of the gap junctions when the oocytes are injected or pretreated with this metabolite. We propose the idea that cAMP is the regulatory molecule in meiotic arrest in this amphibian species.
Extrafollicular mediation of oocyte maturation by radial nerve factor in starfish Pisaster ochraceus
Authors: Schuetz Allen W.
Published: July 2002

In starfish ovaries follicle cells that envelop each oocyte are thought to mediate the production of a maturation inducing substance (MIS), identified as 1-methyladenine, that induces maturation and spawning of oocytes after exposure to a gonadotropic substance secreted by the radial nerve (RNF). Studies were carried out to assess the possible role of extrafollicular cells within the ovarian wall in mediating this signal transduction process in the ovary of Pisaster ochraceus. Oocyte maturation and spawning occurred following the addition of RNF to intact ovarian tissue in vitro whereas no maturation occurred following the addition of RNF to germinal vesicle (GV) oocytes or GV oocytes surrounded by follicle cells. In contrast, oocyte maturation occurred when small ovarian wall fragments, lacking mature follicles, were incubated with GV oocytes and RNF. Neither actinomycin D nor cycloheximide altered RNF induction of oocyte maturation in the presence of the ovarian wall tissue whereas preheating (boiling water for 5 min) the tissue obliterated its response to RNF. Non-ovarian tissues failed to produce MIS in response to RNF. Results suggest that ovarian components other than the follicle cells that envelop fully grown immature oocyte are responsive to RNF and represent a significant and previously unrecognised intra-ovarian source of MIS.
Mitogen-activated protein kinase in human eggs
Authors: Sun Qing-Yuan , Blumenfeld Zeev , Rubinstein Sara , Goldman Shlomit , Gonen Yael , Breitbart Haim
Published: July 2002

Mitogen-activated protein (MAP) kinase in human eggs has been investigated by using immunoblotting with both anti-Active MAPK and anti-ERK2 antibodies. The results showed that the main form of MAP kinase was p42ERK2. It was in a dephosphorylated form in oocytes at the germinal vesicle stage, but fully phosphorylated in unfertilised mature eggs. MAP kinase phosphorylation was significantly decreased when pronuclei were formed after intracytoplasmic sperm injection. Neither MAP kinase expression nor activity was detected in morphologically degenerated eggs. Although MAP kinase still existed in early embryos arrested at the 8-cell or morula stages, little, if any, activity could be detected. These data suggest that MAP kinase may play an important role in the cell cycle regulation of human eggs, as in other mammalian species.
AUTOBIOGRAPHY WITHOUT BORDERS
Authors: Bodenheimer Rosemarie
Published: July 2002

WHERE IS “Victorian autobiography” in the late 1990s? Everywhere and nowhere. Always contested as a genre, autobiography has stretched its fragile boundaries and diffused itself among the many forms of self-representation that interest contemporary critics: travel narratives, letters, journals, fiction, poetry, essays, biography. This diffusion is in many ways a fruitful development, although it raises the question of whether “Victorian autobiography” is still a meaningful category to use in describing critical work. Although I concentrate here on a number of recent books that flourish the word “autobiography” in their titles, I come to this review with a sense that some of the most vital work on Victorian self-representation may be flying under different banners.
“THE DISTURBANCES OVERSEAS”: A COMPARATIVE REPORT ON THE FUTURE OF ENGLISH STUDIES
Authors: Gagnier Regenia
Published: July 2002

This is an adaptation of a talk first presented to the Council for College and University English (CCUE) conference on English for the Millennium, Sept. 1996. CCUE is the British professional body that represents the discipline and departments of English in England, Scotland, and Wales. The talk was meant to provide a transatlantic perspective on the future of the discipline. Originally it was published in CCUE News (June 1997) and later adapted to presentations throughout the U.K. The excerpts here focus on issues of multiculturalism, interdisciplinarity, and cultural studies.

WHEN I DRAW ON MY EXPERIENCE in the United States it is not because I am unaware that the centrality of English literary history is less controversial in England than in its former colony, but because the areas that I see as fundamental to the future of English — a diverse Anglophone population and the demands of the marketplace — are fundamental to both. Twenty years ago, American and British academics were different worlds. The formal democratization of the university and official ideologies of neoliberalism, or market orientation, have brought them closer together. My argument is that the future of English depends less on theories or ideas than on human geographies, institutional conditions, and our embeddedness in market society.
The consequences of European unification for legal education in the member states
Authors: STORME MARCEL
Published: July 2002

It is clear that European unification will affect legal education in Europe. Political integration and the increasing coming together of the legal systems in Europe need a new approach from universities teaching law studies. This article examines the goals of legal education and how they can be reached. In addition, it defends the thesis that a law faculty must not teach law, but must train lawyers: they must become technicians able to solve social and human problems by the legal route and they must be agents of peaceful change. It is argued that, in addition to national law schools, top law schools in Europe should be structured on the American model with very strict selection.