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H Kennedy

Publications and source records attributed to H Kennedy.

At least 55 records · Page 3Linked to original sources
PubMed1994

International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B. IV. Comparability of apolipoprotein B values by use of International Reference Material.

We performed temporal and thermal stability studies on SP3-07, a liquid-stabilized reference material for apolipoprotein (apo) B, selected during the previous phase of the International Federation of Clinical Chemistry project on standardization of apolipoprotein measurements. Results indicate that SP3-07 stored at -70 degrees C has the long-term stability required for a reference material. We assigned an accuracy-based apo B value of 1.22 g/L to SP3-07, using a nephelometric method that was calibrated with freshly isolated low-density lipoprotein for which the apo B mass value was determined by a standardized sodium dodecyl sulfate-Lowry procedure. Using a common protocol, the study participants transferred the assigned mass value from SP3-07 to the individual calibrators of the analytical systems and measured the apo B concentration of 20 fresh-frozen samples obtained from individual donors and covering a clinically relevant range of apo B values. The among-laboratory CV on these samples, analyzed by 25 analytical systems, ranged from 3.1% to 6.7%. These results demonstrate the lack of matrix effects of SP3-07 and its ability to provide accurate and comparable apo B values in a variety of immunochemical methods. On the basis of the outcome of these studies, the World Health Organization has endorsed SP3-07 as the International Reference Material for Apolipoprotein B.

Apolipoprotein A-I↗
PubMed1993

Transient cortical pathways in the pyramidal tract of the neonatal ferret.

Anterograde transport of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) was used to study transient axons from the visual cortex in the pyramidal tract. Injections at birth restricted to the visual cortex labeled axons in the vicinity of the pontine nuclei. Two to eight days after birth, axons from the occipital cortex were found posterior to the pontine nucleus, their caudalmost stable target. Transient corticospinal axons from the presumptive primary visual cortex did not grow caudal to the pyramidal decussation. Innervation of more distal targets preceded innervation of proximal targets. Innervation of the pontine nucleus is initiated around 68 hours after birth, when the transient extension in the medullary pyramidal tract has attained its maximum caudal extent. Innervation of the superior colliculus begins 9 days after birth. Retrograde tracers were used to follow the developmental changes in the cortical distribution of the parent neurons giving rise to axons in the pyramidal tract. In the adult, labeled neurons following injection of retrograde tracer in the pyramidal tract occupied less than a third of the neocortex and were centred on the anterior part of the coronal and spleniocruciate gyri. In the immature brain, labeled neurons covered more than two-thirds of the neocortex. Areal density measurements in the neonate showed that peak labeling was centred in the anterior coronal and spleniocruciate gyri, where corticospinal cells in the adult are located. There was a marked rostral-caudal gradient so that labeled neurons were very scarce towards the occipital pole. These results, showing transient neocortical axons in the pyramidal tract in a carnivore, suggest that this may be a common feature of mammalian development. The finding that the adult pattern of corticospinal projections does not emerge from a uniform distribution is discussed with respect to the areal specification of cortical connectivity.

Animals↗
PubMed1993

Modulation of the cell cycle contributes to the parcellation of the primate visual cortex.

An as-yet unresolved issue in developmental neurobiology is whether the discrete areas that form the mammalian cortex emerge from a uniform cortical plate or whether they are already specified in the germinal zone. A feature of the primate striate cortex is that the number of neurons per unit area is twice that of anywhere else in the cerebral cortex. Here we take advantage of this unique structural feature to investigate whether the extra striate cortical cells are due to increased neuron production during neurogenesis. We labelled precursors undergoing terminal cell division with 3H-thymidine and allowed them to migrate to the cortical plate. Cell counts revealed that their rate of production in the germinal zone of striate cortex is higher than in that given rise to extrastriate cortex. Also, we used 3H-thymidine pulse injections to investigate cell cycle dynamics and found that this phase of increased production of striate cortical cells is associated with changes in the parameters of the cell cycle. These results show that cortical area identity is at least partially determined at the level of the ventricular zone.

Animals↗
PubMed1993

The roles of mental representations and mental processes in therapeutic action.

In this paper we describe two models of the psychoanalytic treatment of mental disturbance. The first describes the mechanism by which the patient is helped to recover threatening ideas and feelings which have been repudiated or distorted as a result of conflict and defense. The second points to the therapeutic effects of engaging previously inhibited mental processes within the psychoanalytic encounter. The two forms of therapeutic action imply two distinct means available to the individual to deal with psychological conflict. They highlight different aspects of the psychoanalytic process and technique in child and adult psychoanalysis.

Adult↗
PubMed1993

Twilight of the gods: John Henry Mackay's Der Unschuldige.

The writings of the Scotch-German John Henry Mackay are important for the early cultural history of the modern gay movement. This article recalls this unjustly neglected anarchist writer and advocate of man/boy love by tracing his biography and pointing out his contacts with others in the movement. His late novella Der Unschuldige is analyzed to show that Mackay has encoded homosexuality there in a unique and individual way.

Homosexuality↗
PubMed1993

The importance of developmental timing in cortical specification.

Environmental control of gene expression can occur early or late during development, and this is relevant to understanding species differences in cortical specification. Experiments in the developing visual system of the primate show that the areal limits of striate cortex are specified by the thalamic inputs, so that afferent specification of cortex appears as a general feature of mammalian development. Primates differ from nonprimates in that thalamic afferents control very early stages of corticogenesis when symmetrical cell division is forming the pool of striate neuron precursors. Other cortical features are specified much later in primates than in nonprimates. We speculate that the early specification of certain features and the late specification of others contribute to the sophistication of the cerebral cortex characteristic of primates.

Afferent Pathways↗
PubMed1992

Visuotopic organization of corticocortical connections in the visual system of the cat.

It has recently been demonstrated that, in contrast with the retinogeniculocortical projection, the corticocortical connections in the cat present a high degree of convergence and divergence. This suggests that some corticocortical connections link nonvisuotopically corresponding regions. Using fine-grain electrophysiological mapping and anatomical tracing, we have set out to test this possibility by placing a small injection of retrograde tracer in area 17 and by comparing the extent of visual field encoded in the region of area 18 containing labeled cells and that represented in the uptake zone. The results demonstrate that the size of the labeled region on the surface of area 18 is independent of eccentricity and that, despite its anisotrophy, this region of labeling encodes a broadly circular region of visual field that is larger than that encoded in the uptake zone of the tracer in area 17. For example, in the representation of lower visual field, a virtual point in area 17 that encodes a visual field region 4 degrees in diameter receives afferents from a region of area 18 encoding a region 11 degrees wide. Examination of the density of labeled cells in the labeled zone in area 18 reveals that the highest density is observed in a region in visuotopic correspondence with the injection site. However, high labeling density is also occasionally found in patches that do not represent the same visual field region as the injection site. Many receptive fields of neurons recorded in the labeled zone in area 18 only partially overlap or fail to overlap the visual field region encoded by the injection site. The results also demonstrate that the extent of visual field encoded in the labeled zone in area 18 is the same as that represented in the region of intrinsic labeling in area 17. It is suggested that cortical afferents coming from several cortical areas and converging on a column of cells in area 17 cover the same extent of visual field and that this cortical network constitutes the structural basis for the modulatory regions of the receptive field as well as the synchronization of neurons in different cortical areas.

Animals↗
PubMed1992

Zinc absorption in adult men from a chicken sandwich made with white or wholemeal bread, measured by a double-label stable-isotope technique.

Eleven fasted adult men consumed a chicken meat sandwich made with white or wholemeal bread, extrinsically labelled with 2 mg 67Zn, on two different occasions. Immediately after eating the sandwich they were given an intravenous injection of 1.5 mg 70Zn. True Zn absorption (which was approximately 7% higher than apparent absorption) was determined by the faecal balance technique by making an allowance for endogenous excretion from measurements of faecal excretion of 70Zn. There was no significant difference in mean true Zn absorption from the white or wholemeal bread sandwich, 33.6 and 25.4% respectively. It was concluded that the substitution of wholemeal for white bread does not reduce Zn absorption from meat-based sandwiches.

Adult↗
PubMed1992

International Federation of Clinical Chemistry standardization project for measurements of apolipoproteins A-I and B. II. Evaluation and selection of candidate reference materials.

The first phase of an international collaborative study for standardization of test systems for measuring apolipoprotein (apo) A-I and apo B demonstrated that uniformity of apo A-I and apo B measurements can be achieved if suitable common reference materials are used to calibrate the different systems. The objective of the second phase was to evaluate the linearity and parallelism or proportionality of the candidate reference materials selected in phase one and to determine whether any of them could be proposed as international reference materials. We evaluated the proposed reference materials with 37 test systems for apo A-I and 38 for apo B, involving 23 manufacturers and five research laboratories. Two lyophilized preparations were proposed for apo A-I, SP1 from Behringwerke AG and SP2 from Daiichi Pure Chemicals Co., and two liquid preparations were proposed for apo B, SP3 from Behringwerke AG and SP4 from Reagents Applications. The linearity of the candidate reference materials was compared with the linearity of a frozen serum pool or interim serum reference material distributed to all the participants and with that of a fresh serum pool prepared by each participant. SP1 and SP3 exhibited linearity and parallelism similar to that of the fresh frozen serum pool and had among-laboratory CVs less than or similar to those obtained on normolipidemic serum samples (approximately 6% for apo A-I and approximately 7% for apo B).

Apolipoprotein A-I↗
PubMed1991

The effects of bilateral enucleation in the primate fetus on the parcellation of visual cortex.

Bilateral enucleation in the macaque fetus causes an areal reduction of an otherwise normal striate cortex. Here we show that in early operated animals this reduction is accompanied by a separation of striate and prostriate cortices which are normally contiguous. However this induced separation does not correspond to the areal reduction of striate cortex, indicating that extrinsic signals regulate either the proliferation and/or survival of striate cortical neurons.

Animals↗
PubMed1991

Cost efficiency of bone scans in breast cancer.

A total of 110 consecutive females who presented in 1987 with primary carcinoma of the breast were staged according to the UICC TNM staging system. Of these, 90 patients had bone scans at presentation, of which seven were positive. The rate of positive initial scans for Stages I-II was 3.5%. Of these only one patient subsequently had bone metastases confirmed, to diagnose which by bone scan, the estimated cost was pounds 1300. Follow-up information was obtained for 95 patients, repeat scans being performed in 22 who had symptoms suggestive of bone metastases. Ten patients with negative initial scans converted to scan-positive within a mean time of 15 months. Only four of these had radiological confirmation of bone metastases. The cost of detecting bone metastases by follow-up scan was approximately pounds 80 per patient. The false-positive rate and the false-negative rate were both calculated as 10%. The specificity of the test was calculated as 90%. It is recommended that bone scanning should be reserved for patients with Stages III and IV disease and to evaluate symptoms suggesting bone metastases.

Adult↗
PubMed1991

Reflections on the aim of child analysis.

Childhood disturbances can best be studied in a developmental frame of reference. Following Anna Freud, the authors distinguish between outcome aims and intermediary aims. They present the analyses of a child and an adolescent to demonstrate how these aims affect the nature and progression of treatment.

Adolescent↗
PubMed1991

Segregation of callosal and association pathways during development in the visual cortex of the primate.

The segregation of callosal and association pathways in the developing visual cortex of the monkey was studied using the retrograde tracers fast blue and diamidino yellow. Quantitative analysis of the laminar distribution of labeled callosal and association neurons made it possible to reveal the shifting pattern of connections that characterizes the development of these two pathways. In the adult, callosal neurons are restricted to supragranular layers, where they are concentrated at the bottom of layer 3. Association neurons are located both in infra- and supragranular layers. Supragranular layer association neurons are concentrated in layer 2, with limited spread into layer 3 so that there is little overlap with callosal neurons. In the immature brain, callosal neurons are characterized by a tangential distribution that is more widespread than in the adult, while their laminar distribution undergoes little developmental change. Association neurons show two types of changes in their laminar distribution: (1) in the early fetus, there is a large excess of association neurons in supragranular layers, the adult distribution being achieved some time after birth; and (2) during maturation there is a selective elimination of at least 50% of the projections originating from the lower part of layers 2/3. Hence, the adult radial segregation of association and callosal pathways is achieved in part by regressive phenomena. The developmental reduction of bihemispheric projections is largely independent of changes in the organization of association neurons. Quantitative analysis of the morphology and spatial location of neurons sending axon collaterals to both hemispheres suggests that they constitute a subset of callosal neurons and that their frequency is determined by factors that regulate directly this population. These results are discussed with respect to the specification of visual cortical pathways during ontogenesis.

Amidines↗
PubMed1990

Incidence of visual cortical neurons which have axon collaterals projecting to both cerebral hemispheres during prenatal primate development.

Fast blue was injected massively in extrastriate cortex of one hemisphere Diamidino yellow in area 17 of the other hemisphere, in adult and prenatal cynomolgus monkeys. After a suitable survival period the brains were processed for fluorescent dyes. Counts were made of the total number of labeled neurons and of those neurons which were labeled by both dyes and which project therefore to both hemispheres by means of bifurcating axon collaterals. At 122 and 135 days after conception (E122 and E135), shortly after cortico-cortical pathways are established, double-labeled neurons constituted 0.45% and 0.46% of the total population of labeled neurons in area V2. In V2 in the adult the range of values of double-labeled neurons was 0.03-0.08%.

Animals↗
PubMed1989

Convergence and divergence in the afferent projections to cat area 17.

We have examined the topography of the afferent connections to area 17 in the cat by means of double retrograde label tracing techniques. Injections of two fluorescent retrograde tracers, diamidino yellow and fast blue, were made with variable separations in area 17 and the spatial distributions of the resulting populations of labeled cells examined in afferent cortical areas and subcortical structures. When injections were separated rostrocaudally, the topographic organizations of the projections were characterized quantitatively with two graphic methods: the labeling density curve and the connectivity graph. The labeling density curve measures labeled neuron density in successive rostrocaudal sections, whereas the connectivity graph provides a two-dimensional model of the topography of a given connectivity. The connectivity graph makes it possible to define two parameters that characterize the topography of the connection: the convergence and the divergence. The convergence is defined as the extent of an afferent structure that contains neurons converging on a line normal to the cortical surface in area 17. The divergence is the extent of area 17 that is innervated by neurons contained in an infinitely small region of the afferent structure. The results show that a number of subcortical structures project to area 17 in a nontopographic manner, i.e., that in each of these structures neurons contained in an infinitely small region send projections to the whole of area 17 and that a line normal to the surface of area 17 is innervated by neurons distributed throughout the afferent structure in question. Nontopographic projections are found from the intralaminar nuclei, the ventral mesencephalic tegmental region, the diagonal band of Broca, and the locus coeruleus. All remaining subcortical structures and cortical areas send topographically organized projections to area 17. The extent of the convergence and divergence, however, varies between structures. Only the projection from the A laminae of the LGN was found to approximate a point-to-point projection with a convergence of 0.4 mm and 2 mm in divergence. Much larger convergence and divergence values are found in the projections from the claustrum and the cortical areas. For example, the divergence reaches 20 mm for the projections from area 20 or from the anterior part of the lateral suprasylvian sulcus. Knowing the convergence and divergence values and the retinotopic organizations of area 17 and a number of its afferents, it becomes possible to test whether connections in the visual system link regions representing the same zone of the visual field.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1989

Maturation and connectivity of the visual cortex in monkey is altered by prenatal removal of retinal input.

In several species, the peripheral input from the eyes partly determines the pattern of interconnections between the visual areas of the two cerebral hemispheres through the fibre tract termed the corpus callosum. In the macaque monkey, the neurons projecting through the callosum are largely restricted to area 18 throughout ontogeny, whereas area 17 is characterized by few or no callosal projections. Here, we show that suppressing the peripheral input by prenatal removal of the eyes leads to a marked reduction in the extent of area 17, resulting in a large shift in the position of the histologically identifiable boundary between the two areas. Even so, the boundary continues to separate an area rich with callosal connections (area 18) from one poor in such projections (area 17), indicating there is no effect on the callosal connectivity of area 17. In contrast, in area 18, eye removal results in many more neurons with callosal projections than in normal animals. The results suggest that the factors that determine the parcellation of cortical areas also specify their connectivity.

Animals↗