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D A Lewis

Publications and source records attributed to D A Lewis.

At least 217 records · Page 12Linked to original sources
PubMed1991

Differential laminar distribution of tyrosine hydroxylase-immunoreactive axons in infant and adult monkey prefrontal cortex.

Immunohistochemical techniques were used to evaluate the laminar distribution of tyrosine hydroxylase (TH)-immunoreactive axons in area 9 of infant and adult rhesus monkey prefrontal cortex. In neonatal animals, TH-positive axons had a bilaminar location in the superficial and deep cortical layers, whereas in the adults, labeled fibers were more evenly distributed across all layers. These differences reflected the fact that fiber density in the superficial layers was over 35% greater in neonates than in adults, but in the middle cortical layers, fiber density was over 100% greater in adults than in neonates. The most striking changes in fiber distribution appeared to occur during the first few months of life. These findings may reveal differences in the role of dopamine in the regulation of prefrontal cortical function in neonatal and adult monkeys.

Aging↗
PubMed1991

A comparative analysis of the distribution of prosomatostatin-derived peptides in human and monkey neocortex.

Comparative analyses were made of the immunohistochemical and biochemical distributions of three prosomatostatin-derived peptides (PSDP) in human, perfused monkey, and unperfused monkey neocortex. The PSDP we examined were the tetradecapeptide somatostatin 14 (SS14); the N-terminal extension of this peptide, somatostatin 28 (SS28); and somatostatin 28(1-12) (SS28(1-12)). In immunohistochemical experiments, numerous SS28-immunoreactive perikarya were located in both superficial and deep layers of perfused monkey cortex, but none were present in the cerebral cortex from unperfused monkey or autopsied human brains. In contrast, the number of SS28(1-12)-immunoreactive neurons was five times greater in the superficial cortical layers of unperfused monkey than of perfused monkey brain. Moreover, unperfused monkey and human cortex contained notably more SS14-immunoreactive processes than perfused monkey cortex. These data suggested that SS28 may have been converted into SS14 and SS28(1-12) in unperfused tissue during the post-mortem interval. This hypothesis was examined biochemically by measuring the levels of immunoreactivity of SS14, SS28, and SS28(1-12) in samples of unperfused monkey cortex frozen at different time intervals after removal from the brain. Samples frozen 10 minutes or longer after removal contained only 10-20% the level of SS28 immunoreactivity measured in samples frozen immediately or 1 minute after removal. The levels of SS14 and SS28(1-12) immunoreactivity did not demonstrate such reductions, and may instead have increased at early time points. To further characterize post-mortem effects on PSDP and to explore for species differences, we performed a detailed comparison of the regional, laminar, and cellular distribution of SS28(1-12) immunoreactivity under the three conditions. A progressive loss of immunoreactivity, particularly in radial fibers, was found at increasing post-mortem intervals in unperfused monkey neocortex, indicating that differences in density and distribution of immunoreactive fibers between human and perfused monkey may result from post-mortem peptide degradation in unperfused tissue. In contrast, the larger size of SS28(1-12)-immunoreactive white matter neurons in humans as compared to monkeys appeared partially due to a post-mortem effect but also reflected a species difference. In addition, the density of white matter neurons was found to be significantly greater in human than in perfused or unperfused monkey. These data indicate that any study of human autopsy material must be assessed in light of possible post-mortem effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Prospective study of postpartum blues. Biologic and psychosocial factors.

Potential biologic and psychosocial causative factors for the postpartum blues were tested in a prospective study of 182 women followed up from the second trimester of pregnancy until postpartum week 9. Personal and family history of depression, depressive symptoms, stressful life events, and social adjustment were all assessed during the second trimester. Levels of progesterone, prolactin, estradiol, free and total estriol, and free and total cortisol were measured on several occasions during late pregnancy and early puerperium. Obstetric and child-care stressors and the postpartum blues were assessed after delivery. Predictors of the postpartum blues were personal and family history of depression, social adjustment, stressful life events, and levels of free and total estriol. Our results support the hypothesis that the postpartum blues is within the spectrum of affective disorders.

Adult↗
PubMed1991

Distribution of choline acetyltransferase-immunoreactive axons in monkey frontal cortex.

Cholinergic neurons of the nucleus basalis of Meynert project to numerous regions of the cerebral cortex. However, little is known about the regional and laminar distributions of cholinergic axons in monkey frontal cortex. In this study, immunohistochemical techniques were used to identify axons that were immunoreactive for choline acetyltransferase, the enzyme that catalyses the synthesis of acetylcholine, in the frontal cortex of cynomolgus monkeys. Motor cortex contained the greatest density of labeled fibers: the density of labeled fibers was lower in premotor and anterior cingulate cortices and lower still in the association regions of prefrontal cortex. On a laminar basis, choline acetyltransferase-immunoreactive axons were most dense in layer I to superficial layer III. Layer V also contained a distinct band of labeled fibers that was particularly prominent in the agranular regions of frontal cortex. The density of labeled fibers was much lower in the deep portion of layer III to layer IV and in layer VI. These findings demonstrate a specific and regionally distinctive cholinergic innervation of monkey frontal cortex that may reveal the anatomical basis for the influence of acetylcholine on the diverse functions of primate frontal cortex.

Animals↗
PubMed1991

Controlled prospective study of postpartum mood disorders: psychological, environmental, and hormonal variables.

Demographic, psychiatric, social, cognitive, and life stress variables were used to determine the etiology of depression in childbearing (CB; n = 182) and nonchildbearing (NCB; n = 179) women. Hormonal variables in postpartum depression were also evaluated. In the CB group predictors of depression diagnosis were previous depression, depression during pregnancy, and a Vulnerability (V) x Life Stress (LS) interaction; predictors of depressive symptomatology were previous depression, depressive symptoms during pregnancy, life events, and V x LS. Only estradiol was associated with postpartum depression diagnosis. In the NCB group V X LS was the only predictor of depression diagnosis; depressive symptoms during pregnancy and life events were predictors of depressive symptomatology. Previous findings about depression vulnerability were replicated. The significant V x LS interactions support the vulnerability-stress model of postpartum depression.

Adult↗
PubMed1991

The effect of the uptake of particles on the chemotaxis of polymorphonuclear leucocytes in-vitro.

The relationship between the phagocytic uptake of latex microspheres (1.1 microns diam.) and the mobility of rat polymorphonuclear leucocytes (PMNLs) has been investigated in-vitro. The movement of PMNLs was found to be independent of the uptake of particles but about half of the PMNLs were not receptive to the chemo-attractant N-formylmethionyleucylphenylalanine. However, the uptake of particles was greater when particle/cell ratios were high and the greatest number of particles were carried into a cellulose nitrate filter by chemotaxis at the highest particle/cell ratio of 30:1.

Animals↗
PubMed1991

The HXT1 gene product of Saccharomyces cerevisiae is a new member of the family of hexose transporters.

Two novel genes affecting hexose transport in the yeast Saccharomyces cerevisiae have been identified. The gene HXT1 (hexose transport), isolated from plasmid pSC7, was sequenced and found to encode a hydrophobic protein which is highly homologous to the large family of sugar transporter proteins from eucaryotes and procaryotes. Multicopy expression of the HXT1 gene restored high-affinity glucose transport to the snf3 mutant, which is deficient in a significant proportion of high-affinity glucose transport. HXT1 was unable to complement the snf3 growth defect in low copy number. The HXT1 protein was found to contain 12 putative membrane-spanning domains with a central hydrophilic domain and hydrophilic N- and C-terminal domains. The HXT1 protein is 69% identical to GAL2 and 66% identical to HXT2, and all three proteins were found to have a putative leucine zipper motif at a consensus location in membrane-spanning domain 2. Disruption of the HXT1 gene resulted in loss of a portion of high-affinity glucose and mannose transport, and wild-type levels of transport required both the HXT1 and SNF3 genes. Unexpectedly, expression of beta-galactosidase activity by using a fusion of the lacZ gene to the HXT1 promoter in a multicopy plasmid was maximal during lag and early exponential phases of growth, decreasing approximately 100-fold upon further entry into exponential growth. Deletion analysis of pSC7 revealed the presence of another gene (called ORF2) capable of suppressing the snf3 null mutant phenotype by restoring high-affinity glucose transport and increased low-affinity transport.

Amino Acid Sequence↗
PubMed1991

Preservation of endothelial cells in excised rat carotid arteries. Effects of transmural pressure and segment length.

When arteries are excised, they collapse and shorten spontaneously, which can result in damage to the endothelium. To determine if an intact endothelial cell layer could be preserved in excised vessels, we isolated and cannulated rat carotid artery segments (in situ length, Lis, 10-20 mm) at both ends while maintaining both transmural pressure (70 mm Hg) and Lis, while either transmural pressure or Lis, or after allowing vessel collapse and shortening (n = 4 vessels per treatment). After each treatment, vessel segments were perfused with fixative and stained with AgNO3 to visualize endothelial cells. The amount of endothelial cell loss was quantified using stereological analysis of video microscopic images of the luminal surface. Results demonstrated that maintenance of both Lis and transmural pressure minimized endothelial cell denudation (1.6 +/- 0.9%); permitting the vessel to collapse and shorten resulted in the greatest loss of endothelial cells (59.4 +/- 13.2%); and maintenance of either pressure or Lis resulted in intermediate endothelial cell loss (13-30%). We conclude that the spontaneous collapse and shortening that normally accompany the excision of arterial segments result in substantial endothelial cell loss, which can be virtually eliminated with the maintenance of transmural pressure and vessel segment length. These findings have implications for surgical and experimental procedures requiring intact endothelium.

Animals↗
PubMed1991

Human anterior pituitary response to exogenous arginine vasopressin.

The adrenocorticotropin-releasing effect of arginine vasopressin is well known. The effects of AVP on other anterior pituitary hormones remain confusing, with few in vivo human data available. Two human studies of exogenous AVP effects on ACTH, GH, TSH and prolactin are described. In the dosage and route of administration used, AVP was found to be a specific ACTH secretagogue.

Adult↗
PubMed1990

Cholecystokinin innervation of monkey prefrontal cortex: an immunohistochemical study.

Knowledge of the circuitry of chemically identified systems in primate prefrontal cortex is limited. Although cholecystokinin is very abundant in prefrontal cortex (Geola et al.: Journal of Clinical Endocrinology and Metabolism 53(2):270-275, 1981; Taquet et al.: Neuroscience 27(3):871-883, 1988), the organization of cholecystokinin-containing structures in primate prefrontal cortex has not been investigated. Using immunohistochemical and retrograde transport techniques, we characterized the cholecystokinin innervation of prefrontal cortex in macaque monkeys. The use of two antibodies directed against different portions of the cholecystokinin molecule revealed that distinct forms of the molecule were differentially localized in the same cortical neurons. These small, nonpyramidal cholecystokinin-positive neurons had a variety of somal morphologies and the density of labeled cells did not differ among cytoarchitectonic regions. Labeled neurons had a distinctive laminar distribution with the greatest density of cells present in layers II-superficial III. Labeled fibers also had a distinctive laminar pattern of distribution that differed from that of the immunoreactive neurons. In granular prefrontal cortex, terminal fields were evident in layers II, IV, and VI, with the greatest density in layer VI. Agranular area 24 exhibited a bilaminar pattern of immunoreactivity with a band in layer II and a very dense terminal field in layers V-VI. A high density of cholecystokinin-binding sites has been found in layers III-IV of prefrontal cortex and other association areas in the monkey; this finding has been attributed to possible cholecystokinin-containing afferents from the thalamus (Kritzer et al.: Journal of Comparative Neurology 263:418-435, 1987). The mediodorsal nucleus of the thalamus is known to be a source of afferents which terminate in layer IV of prefrontal cortex. However, combined retrograde transport and immunohistochemical techniques failed to reveal the presence of cholecystokinin-positive neurons in the mediodorsal nucleus of the thalamus that project to prefrontal cortex. These findings, and other observations, suggest that the terminal field in layer IV is formed by descending axons that arise from cholecystokinin-containing neurons in layers II and superficial III. This study demonstrates that the cholecystokinin innervation of prefrontal cortex has a laminar specific organization that is preserved across cytoarchitectonic regions. This distribution of immunoreactive structures suggests a distinctive role of cholecystokinin in cortical circuitry that is common to every region of prefrontal cortex.

Animals↗
PubMed1990

Heterogeneity of chandelier neurons in monkey neocortex: corticotropin-releasing factor- and parvalbumin-immunoreactive populations.

Chandelier neurons are a unique subclass of cortical nonpyramidal neurons. The axons of these neurons terminate in distinctive vertically arrayed cartridges that synapse on the axon initial segment of pyramidal neurons. In this study, the rapid Golgi method and immunohistochemical techniques were used to characterize the morphology, regional distribution, laminar location, and biochemical content of chandelier neurons in the prefrontal and occipital cortices of three monkey species. As in our previous studies of visual areas V1 and V2 (Lund: Journal of Comparative Neurology 257:60-92, 1987; Lund et al.: Journal of Comparative Neurology 202:19-45, 1981, 276:1-29, 1988), Golgi impregnations of areas 46 and 9 of macaque prefrontal cortex show chandelier neurons to be present in layers 2 through superficial 5. The vertical arrays of terminal boutons (axon cartridges) typical of this neuron class are also present in layers 2-6 of the prefrontal cortex, but are not found in layer 1 or the subcortical white matter. In immunohistochemical studies, a calcium-binding protein, parvalbumin, and a neuropeptide, corticotropin-releasing factor (CRF), identify rod-like structures that are morphologically similar to the axon cartridges of chandelier neurons seen in the Golgi material. In addition, both parvalbumin- and CRF-immunoreactive cartridges are located below the somata of unlabeled pyramidal neurons and appear to outline the axon initial segment of these neurons. However, we find that parvalbumin and CRF are present in only subpopulations of chandelier axon cartridges. For example, in adult primary visual cortex, parvalbumin-labeled cartridges are present in very low numbers only in layers 2-3, whereas in prefrontal and occipital association cortices these cartridges are a very prominent component of layers 2-superficial 3 and are present in much lower density in the deeper cortical layers. In contrast to these findings in adult macaque monkeys, prefrontal and occipital association cortices of infant macaque monkeys contain a very high density of parvalbumin-labeled cartridges in layer 4 and relatively few in the superficial cortical layers. Furthermore, in adult squirrel monkey prefrontal cortex, CRF-labeled cartridges are predominately present in layer 4, but these CRF-immunoreactive structures have not been observed in the homologous regions of infant or adult macaque monkeys. These findings indicate that even for neurons of such distinctive morphology and presumably constant functional role as chandelier neurons, factors such as regional and laminar location, age, and primate species are associated with differences in the biochemical content of subpopulations of these neurons.

Animals↗
PubMed1990

From programs to lives: a comment.

Reviewed the article by Bond et al., and suggested that the perspective used to frame the issues distorts the nature of the problems we currently face in mental health policy. The conventional evaluative frame is no longer useful in the "inclusionary" system of care that operates. Researchers should study lives, placing programs in the background and putting the person in the foreground.

Assertiveness↗
PubMed1990

A bacteriological study of the effect on the environment of using a one- or two-trolley system in theatre.

In a survey of 53 hospitals, 62% still had a transfer zone in theatre, involving the use of two trolleys. Reluctance to use one trolley without patient transfer was probably because of concerns about excessive bacterial contamination of the theatre. In an attempt to see if these concerns were justified, air in the operating theatre was sampled for bacterial content, as were the surfaces and wheels of trolleys and the floor in the theatre, anaesthetic room and at the 'red line' in the transfer zone. Samples were taken during the first and second cases on the list of each session in one plenum-ventilated theatre over a four-week period, alternating each week between a one- and two-trolley system. Using one trolley did not significantly influence the bacterial counts in the theatre and anaesthetic room. There were significant differences between counts from the trolley wheels and from the floor of the transfer zone, with counts being higher for one trolley than two. These differences were greatly diminished after the trolleys were washed half way through the study. We conclude that there is no deleterious effect on the environment of the operating theatre, the most sensitive area, if only one trolley is used. If it is considered desirable to decrease the contamination of less important areas when using a one-trolley system, trolleys should be washed regularly, particularly the wheels.

Air Microbiology↗
PubMed1990

The organization of chemically-identified neural systems in monkey prefrontal cortex: afferent systems.

1. Immunohistochemical methods were used to identify dopaminergic, noradrenergic, cholinergic and serotonergic axons in cynomolgus monkey prefrontal cortex. 2. The densities of dopaminergic and noradrenergic systems varied in a similar fashion across prefrontal cortical regions, whereas the densities of cholinergic and serotonergic axons were regionally homogeneous. 3. In contrast, the laminar distributions of labeled axons were very different among these four systems. 4. The different patterns of organization of axons arising from these four afferent systems indicate that they may differ substantially in their regulation of prefrontal cortical function.

Afferent Pathways↗
PubMed1990

Relationship between right atrial and mixed venous oxygen saturation and heart rate during exercise in normal subjects and patients with cardiac disease.

An ideal sensing variable for use in rate responsive pacemakers should measure a physiological parameter that closely correlates with heart rate during various activities in a diverse group of subjects. Nineteen patients, 12 normal and 7 patients with heart disease, were studied to assess the relationship between mixed venous oxygen saturation and heart rate. In patients with heart disease right atrial oxygen saturation and heart rate were also compared. Each subject underwent pulmonary artery catheterization and performed seated cycle ergometer exercise. Gas exchange and heart rate were measured continuously and blood sampled at frequent intervals. Normal patients were studied at rest and during steady-state exercise (mean work rate 149 watts). Patients were studied at rest, steady-state exercise (mean work rate 37 watts), and during incremental exercise (5-10 watts/min) to tolerance. There were 248 paired right atrial or mixed venous oxygen saturation/heart rate observations obtained. Changes in mixed venous oxygen saturation and heart rate were not substantially altered by fitness or cardiac disease. Rate responsive pacemakers sensing changes in oxygen saturation may be a superior sensing variable for both normal and patients with heart disease.

Adult↗