Biomedical subjects

M A Matthews

Publications and source records attributed to M A Matthews.

At least 19 recordsLinked to original sources

PubMed2006

Biocompatibility of supercritical CO2-treated titanium implants in a rat model.

Supercritical phase CO2 is a promising method for sterilizing implantable devices and tissue grafts. The goal of this study is to evaluate the biocompatibility of titanium implants sterilized by supercritical phase CO2 in a rat subcutaneous implantation model. At 5 weeks post implantation titanium implants sterilized by supercritical phase CO2 produce a soft tissue reaction that is comparable to other methods of sterilization (steam autoclave, ultraviolet light radiation, ethylene oxide gas, and radio-frequency glow-discharge), as indicated by the thickness and density of the foreign body capsule, although there were some differences on the capillary density. Overall the soft tissue response to the implants was similar among all methods of sterilization, indicating supercritical phase CO2 treatment did not compromise the biocompatibility of the titanium implant.

Alloys↗

PubMed2005

Effects of sterilization on implant mechanical property and biocompatibility.

This article concisely reviews the effects of sterilization on the mechanical properties and surface chemistries of implantable biomaterials. This article also summarizes the biological effects of the sterilization-related changes in the implant. Because there are so many different types of implant materials currently in use (including metals, polymers, and diverse biological materials), the response of tissue to these different materials varies dramatically. This review further discusses the effects of sterilization on in vivo and in vitro tissue response specifically to implantable metals and polyethylene, with the possibility of future biocompatibility testing of the implants sterilized with supercritical phase carbon dioxide sterilization.

Biocompatible Materials↗

PubMed2000

Changes in grape seed polyphenols during fruit ripening.

The quantity and characterization of extracted flavan-3-ol monomers and procyanidins was determined in seeds from Vitis vinifera cv. Cabernet Sauvignon berries, over the course of ripening and at different levels of vine water status. The per berry extractive yield of all polyphenols decreased with maturity, and followed second-order kinetics. The flavan-3-ol monomers decreased most rapidly, followed by the procyanidin extension units and finally, the terminal units. The relative proportion of procyanidin extension units did not vary with maturity. During fruit ripening, the mean degree of polymerization of extracted procyanidins is unchanged when analyzed intact by HPLC, but decreases by thiolytic degradation. The proportion of extracted procyanidins resistant to acid catalyzed thiolysis increased with maturity. Changes in vine water status affected polyphenol amounts, indicating that cultural practices can be used to influence composition. Oxidation of the seed polyphenols during fruit ripening, could explain these observations.

Flavonoids↗

PubMed1999

Comparison between supercritical carbon dioxide extraction and aqueous surfactant washing of an oily machining waste.

Mathematical models are developed to compare aqueous surfactant washing to supercritical carbon dioxide (SCCO2) extraction. These two cleaning processes are potentially competitive technologies which can be used to remove oily contaminants from a solid waste. In both processes, the cleaning efficiency for a batch of waste is evaluated by quantifying the residual oil content in the treated sample. A mass transfer model is used to simulate a semi-continuous washing process, and the experimental data, obtained in a batch operation, are used to estimate the equilibrium parameters in the model. For SCCO2 extraction, a linear desorption model is used to describe the supercritical desorption of oil from the solid phase into the CO2 phase and the simulated results agreed very well with the experimental data. The oil removal in aqueous surfactant washing is viewed to be controlled primarily by the diffusional transport of oil from the interiors of the waste elements to the surface, thus, it can be significantly affected by the size of the particles. A pre-cleaning pulverization is then recommended to improve the cleaning efficiency without increasing any other operation costs. In SCCO2 extraction, the desorption of oil from the solid waste is the controlling step and consequently, the solvent flow rate has no influence on oil removal. Our theoretical studies show that the difference between the cleaning efficiencies of these two technologies is not significant, with the oil concentration in the washing products approximately 5% lower than that in the extraction products.

Carbon Dioxide↗

PubMed1999

The impact of federal and state laws on children exposed to domestic violence.

Until recently, few federal and state laws specifically addressed the needs of children in families in which there is domestic violence. Yet, many laws, particularly in the areas of domestic violence, family law, child welfare, welfare reform, and immigration, can have profound effects on the well-being of these children. The growing understanding by legislators and policymakers of the potential harms of domestic violence to children has resulted in recent years in statutory changes, particularly at the state level. However, laws that are enacted and implemented with inadequate knowledge of the complex dynamics of domestic violence and the unique issues battered parents and their children face may have unintended negative consequences for the children these laws are designed to protect. Collaboration across public and private social service agencies and domestic violence training for court personnel are examples of efforts that can bridge this knowledge gap and increase the likelihood that the protective intent of the laws is carried out in practice. This article analyzes current and proposed federal and state civil laws to better understand their potential impact on children affected by domestic violence. A companion article by Lemon in this journal issue examines court decisions related to these laws.

Child↗

PubMed1998

Focal brain injury and its effects on cerebral mantle, neurons, and fiber tracks.

Following a mild cortical impact injury delivered by a piston to the right sensorimotor cortex of the anesthetized rat, we evaluated mantle loss, neuronal changes, and fiber track degeneration by deOlmos silver stains up to 8 weeks after injury. Darkened neurons indicating damage (chromatolysis) occurred widely throughout both hemispheres and were seen from 1 h to 8 weeks after injury. This effect might have occurred from pressure wave damage from piston impact, brain displacement or deafferentation. Cerebral mantle loss was variable but fiber track degeneration related to projection and corticofugal descending tracks associated with the right sensorimotor system was rather constant. Unexpectedly, considerable fiber track degeneration occurred within the cerebellum, especially the inferior vermis. Cells directly under the piston face were surprisingly well-preserved but axon degeneration studies showed that these apparently intact neuronal cell bodies were surrounded by a dense network of degenerating fiber tracks. The intact cells, therefore, may have been functionally cut off from the rest of the brain owing to interruption of their efferents and afferents. The increased susceptibility of axons compared to cell bodies seen with this focal injury is similar to that observed with diffuse brain injury. The early appearing, severe and widespread axon damage we observed suggests that amelioration of focal traumatic brain injury will have to be directed promptly to the preservation of axons as well as cell bodies.

Animals↗

PubMed1996

Traumatic brain injury of the forelimb and hindlimb sensorimotor areas in the rat: physiological, histological and behavioral correlates.

This study characterizes physiological, histological and behavioral effects of traumatic brain injury (TBI) produced by a controlled pneumatic impactor striking the entire right sensorimotor cortex of the anesthetized rat. Damage to both the fore- and hindlimb sensorimotor areas resulted in a hemiparetic animal which allowed us to use four sensitive behavioral/neurological tests to track the recovery sequelae after injury. Initial experiments measured cardiovascular and respiratory effects after cortical impact which depressed the dura to varying depths. Both 0.5 mm and 1 mm cortical depressions produced a momentary decrease (P < 0.05) in mean arterial blood pressure (MABP) while cortical impacts to depths of 2 mm or 3 mm produced a momentary increase (P < 0.05) in MABP. Normotension was re-established within 30 s after the initial response at all injury levels. Respiratory rate was affected only following 3 mm cortical depressions. A 1 mm cortical depression appeared ideal in terms of minimal cardiorespiratory effects, low mortality and lasting behavioral effects. For behavioral and histologic studies, therefore, additional rats were injured by a 1 mm cortical impact and tested for 8 weeks after TBI using four behavioral tests. Injured rats displayed both fore- and hindlimb deficits up to 56 days while traversing a narrow beam (P < 0.001) and up to 28 days when crossing a pegged beam (P < 0.05). Forelimb deficits evaluated on a wire grid platform were evident for 28 days (P < 0.05). Forepaw preference measured in a non-test setting indicated a bias to use the unaffected forepaw for 35 days (P < 0.05). A biphasic pattern of functional recovery was seen on all tests. A period of rapid functional recovery lasting 7 to 10 days was followed by a slower period of functional recovery lasting many weeks. Possible meanings of this biphasic recovery are discussed as issues of behavioral compensation/adaptation versus true neural recovery. Eight weeks after TBI histological analyses indicated that axonal degeneration was present in the areas adjacent to the ipsilateral cortical injury site. Degenerating fibers also extended across the corpus callosum into the homologous area in the contralateral cortex and were seen in the ipsilateral striatum, somatosensory and motor thalamic nuclei and substantia nigra. Significant axonal degeneration occurred bilaterally around the deep cerebellar nuclei. Degenerating fibers extended into the folia and terminated in the cerebellar granule cell layer. Thus the entire sensorimotor control system appeared to have been affected by a cortical injury.

Animals↗

PubMed1996

Reference memory and allocentric spatial localization deficits after unilateral cortical brain injury in the rat.

Traumatic brain injury (TBI) produces learning and memory impairments in humans. This study investigated the effects of TBI on memory and spatial localization strategies in rats. Prior to TBI, separate groups of rats were trained in an 8-arm radial maze with either all 8 arms baited (Expt. 1) or only 4 of the 8 arms baited (Expt. 2). TBI was produced by a controlled pneumatic impactor striking the entire right sensorimotor cortex of the anesthetized rat. Rats used in Expt. 1 were selected because they did not use a stereotypic response strategy (going to adjacent arms) in performing the maze before injury. After TBI the rats were not different from control rats in the number of working memory (WM) errors made. They did, however, display a distinct propensity to go to adjacent arms, i.e., exhibit stereotypic behavior, with a right-handed (ipsiversive) bias (P < 0.005). After TBI, rats which were trained with only 4 of 8 arms baited committed more reference memory (RM) errors than control rats (P < 0.05). They did not differ from controls on WM errors. Injured rats took longer to re-attain criteria than controls (P < 0.0001). Injured rats also initially displayed a propensity to enter the adjacent arm sequentially before re-attaining criteria. Further analysis indicated that injured rats re-learned the maze with a right-hand bias (P < 0.0001). The results of both experiments suggest that after TBI, rats shifted from an allocentric to an egocentric strategy to re-learn the maze. It was suggested that damage to the parietal cortex may have been responsible for both RM errors and the shift away from an allocentric strategy to an egocentric strategy. Possibly, the ipsiversive (right-hand) bias may be the result of a behaviorally or injury-induced neurochemical asymmetry within the motor system.

Animals↗

PubMed1993

Transactivation by the human T-cell leukemia virus Tax protein is mediated through enhanced binding of activating transcription factor-2 (ATF-2) ATF-2 response and cAMP element-binding protein (CREB).

The human T-cell leukemia virus type I (HTLV-I)-encoded transcriptional activator protein Tax is strongly implicated in HTLV-I pathogenesis. Tax regulates HTLV-I gene expression through three 21-base pair (bp) repeat enhancer elements located in the transcriptional control region of the virus. Tax does not bind these elements directly, but mediates transactivation through the cellular transcription factors that recognize a cAMP response element (CRE)-like sequence centered within each of the 21-bp repeats. In this report, we identify activating transcription factor-2 (ATF-2) and CRE-binding protein (CREB) as the principal T-cell proteins that bind the three 21-bp repeats in vitro. Purified Tax protein augments the level of RNA synthesis induced by ATF-2 and CREB in a cell-free transcription assay, providing evidence that Tax cooperates with these cellular proteins to activate HTLV-I transcription. Furthermore, Tax dramatically increases the binding of both the T-cell-derived and recombinant forms of ATF-2 and CREB to each of the 21-bp repeats. The target sequences for this enhancement reside within the DNA binding/dimerization domains of these proteins. These data suggest that Tax transactivates HTLV-I gene expression by increasing the number of bound ATF-2 and CREB molecules at the viral promoter.

Activating Transcription Factor 2↗

PubMed1992

Rapid Changes in Cell Wall Yielding of Elongating Begonia argenteo-guttata L. Leaves in Response to Changes in Plant Water Status.

Elongation and epidermal cell turgor (P) of Begonia argenteoguttata L. leaves were simultaneously measured to determine the wall-yielding behavior of growing leaf cells in response to changes in plant water status. Rapid changes in plant water status were imposed by irrigating the rooting media with solutions of -0.20 and -0.30 MPa mannitol. These treatments caused decreases in P of 0.09 and 0.17 MPa, respectively. The decreases in P were complete within 10 min, and P did not change thereafter. Following treatments, leaf elongation was nil for periods of 25 to 38 min. Subsequently, elongation recovered to steady rates that were 45 or 75% lower than in the well-watered controls. Leaves of plants that were pretreated with -0.30 MPa of mannitol and rewatered showed an increase in P of 0.19 MPa, which was complete within 15 min; P did not change thereafter. Rewatering caused a several-fold increase in leaf elongation rates, which subsequently declined while P was increasing, to reach steady rates similar to that of the controls. Several estimates of elastic deformation indicated that most of the elongation responses to altered P were due to changes in irreversible deformation. The results showed that the initial effects of changes in P on leaf elongation were partially compensated for by changes in the cell wall-yielding properties. We conclude that linear relationships between P and adjusted growth rates are not necessarily indicative of constant wall-yielding properties. Instead, these relationships may reflect the effect of P on wall-loosening processes.

Journal Article↗

PubMed1992

In vitro activation of transcription by the human T-cell leukemia virus type I Tax protein.

The human T-cell leukemia virus type I (HTLV-I) regulatory protein Tax activates transcription of the proviral long terminal repeats and a number of cellular promoters. We have developed an in vitro system to characterize the mechanism by which Tax interacts with the host cell transcription machinery. Tax was purified from cells infected with a baculovirus expression vector. Addition of these Tax preparations to nuclear extracts from uninfected human T lymphocytes activated transcription of the HTLV-I long terminal repeat approximately 10-fold. Transcription-stimulatory activity copurified with the immunoreactive 40-kDa Tax polypeptide on gel filtration chromatography, and, as expected, the effect of recombinant Tax was diminished in HTLV-I-infected T-lymphocyte extracts containing endogenous Tax. Tax-mediated transactivation in vivo has been previously shown to require 21-bp-repeat Tax-responsive elements (TxREs) in the promoter DNA. Stimulation of transcription in vitro was also strongly dependent on these sequences. To investigate the mechanism of Tax transactivation, cellular proteins that bind the 21-bp-repeat TxREs were prepared by DNA affinity chromatography. Recombinant Tax markedly increased the formation of a specific host protein-DNA complex detected in an electrophoretic mobility shift assay. These data suggest that Tax activates transcription through a direct interaction with cellular proteins that bind to the 21-bp-repeat TxREs.

Base Sequence↗

PubMed1992

Selective deafferentation of convergent inputs to trigeminal subnucleus caudalis: effects on calcitonin gene-related peptide distribution.

Electrophysiological studies (Sessle, 1987, 1991) suggest that trigeminal deafferenting injuries can cause an "unmasking" of existing but normally suppressed convergent inputs to the spinal trigeminal nucleus, including many that arise from the cervical spinal cord. However, the spatial arrangement of this projection has not been examined, particularly with reference to nociceptive components that might become involved in pathological changes leading to chronic pain. Therefore, the purpose of this study was to apply selective interruptions of the trigeminal and/or cervical primary afferent inputs to the spinal trigeminal subnucleus caudalis (Vc) in the cat, followed by (1) demonstration and quantification of axonal degeneration in the spinal trigeminal tract to determine the extent of trigeminal-cervical primary afferent overlap; and (2) an analysis of lesion-induced alterations in the distribution of calcitonin gene-related peptide immunoreactivity (CGRP-IR) in laminae I and II of Vc, since recent evidence strongly suggests that CGRP is involved in pathophysiological elevations of central nervous system neuronal excitability. Degenerating fibers were found throughout the spinal tract following a trigeminal rhizotomy or tractotomy, with the largest numbers adjacent to the rostral two-thirds of Vc, but with a significant number extending caudally to at least the level of C2. CGRP-IR was reduced or eliminated from the rostral one-third and periobex region of Vc, except for a dorsomedial zone that was minimally affected. Retention of CGRP-IR was greater at more caudal levels. Following a combined trigmeninal and cervical tractotomy, fiber degeneration was massive throughout the spinal tract, yet a population of small myelinated fibers persisted at 60 days after surgery. Concomitantly, CGRP-IR was profoundly reduced throughout Vc, except for a small dorsomedial zone of retention, which became more extensive caudally. A cervical tractotomy resulted in moderate numbers of degenerating fibers adjacent to the caudal one-third of Vc, and this number declined rostrally; however, degenerating fibers could be seen at the level of the obex. CGRP-IR was reduced in the dorsomedial and ventrolateral zones of Vc, particularly in its caudal one-third. Electron-microscopic analysis revealed a population of CGRP-IR boutons, most of which were of the simple axodendritic type with asymmetrical contacts. A few examples of axoaxonic contacts were observed. Loss of labeled boutons observed with the electron microscope was consistent with light-microscopic quantitative results. Those boutons that were retained were variable in size and displayed simple axodendritic contacts.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1992

Ultrastructural characterization of substance-P-immunoreactive synaptic terminals in the cat's normal and rhizotomized trigeminal subnucleus caudalis.

Deafferenting injuries often cause transient or permanent physiological alterations within the central projection field of affected primary afferent fibers. Aberrant sensory perceptions, dysesthesias, and hyperalgesias represent the clinical sequelae of such injuries; however, the results of experimental deafferentations have been subject to a variety of interpretations (Rodin and Kruger, 1984b). Neurochemical studies show an increased sensitivity of partially deafferented neurons to substance P (SP). Our previous studies (Hoffmann et al., 1991) documented, primarily at the light-microscopic level, a moderate transient loss of SP-immunoreactive (SPIR) boutons in the trigeminal subnucleus caudalis (Vc)--a loss that seemed to preferentially affect the slightly larger, possibly complex boutons with multiple contacts. However, despite the elimination of the trigeminal input, the larger boutons reappeared. In the present study, therefore, we examined Vc using electron-microscopic immunocytochemistry, in order to document these changes over time and to clarify the structure and relationships of this population of boutons. SPIR boutons occurred in lamina I and II degrees of the substantia gelatinosa of Vc, ranged in size from 1 to 5 microns in diameter, and displayed mixed populations of clear and dense-core vesicles. Most formed single or multiple axodendritic junctions, but a significant number engaged in axoaxonic contacts with both SPIR-labeled and unlabeled terminals. A small number appeared to be the central element of a typical glomerulus, particularly in lamina II degrees. Three to seven days following an ipsilateral retrogasserian rhizotomy, synaptic degeneration was evident in the substantia gelatinosa and often involved glomerular terminals. However, most of these were SPIR-negative and occurred primarily in lamina II degrees. Those SPIR boutons that displayed degenerative features often made single or multiple axodendritic contacts, and in some instances were scalloped. By 30 days, most remaining SPIR boutons were small, with a lower incidence of contacts; however, some of these were axoaxonic. In addition, many SPIR terminals were only very lightly stained--a feature not encountered to such an extent in the contralateral Vc. At 45 days, complex SPIR boutons were again evident in the field, and some showed densely packed vesicles. An increased incidence of clusters of two to four SPIR axoaxonic contacts was also observed. Finally, almost all SPIR boutons encountered at this stage were intensely stained. It is suggested that these alterations represent a compensatory neuroplastic response on the part of overlapping cervical and cranial primary afferents to the partial deafferentation resulting from the interruption of the trigeminal root.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1990

Interaction of host cell proteins with the human T-cell leukemia virus type I transcriptional control region. II. A comprehensive map of protein-binding sites facilitates construction of a simple chimeric promoter responsive to the viral tax2 gene product.

We present a map describing the binding of cellular proteins to a 300-base pair (bp) region of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat. The map accounts for nearly all of the DNase I protection reported in a previous study using crude nuclear extracts. Notable features include a complex arrangement of overlapping binding sites encompassing the 21-bp repeat elements (see accompanying paper) as well as binding sites for the transcription factors Sp1 and NF-I that significantly deviate from the previously defined consensus recognition sequences. Based on the binding results, we constructed simple chimeric promoters containing 21-bp repeat elements, Sp1-, and nuclear factor I-binding sites upstream of a TATA box. Transient transfection experiments show that these promoters are expressed in T-cells and are regulated by the viral tax2 gene product. Deletion of the Sp1 and nuclear factor I sites abolishes tax-induction, suggesting that one or both of these proteins play a role in mediating the tax-responsiveness conferred by the 21-bp repeat element.

Base Sequence↗

PubMed1990

Comparison of sympathetic neurons in orofacial and upper extremity nerves: implications for causalgia.

This study compared nerves of the orofacial region with nerves frequently associated with causalgia to determine if there is a significant difference in the proportion of sympathetic neurons within these nerves, which may account for the lower incidence of orofacial causalgia. Three orofacial and two upper extremity nerves were examined. Each nerve was transected and labeled with horseradish peroxidase to identify the cell bodies of neurons contributing axons to the nerve. The study included two trials per nerve, for a total of 10 trials in eight cats. The trigeminal and dorsal root ganglia, containing sensory neurons (SN), and the stellate, middle, and superior cervical ganglia, containing postganglionic sympathetic neurons (PGSN), were sectioned and reacted with tetramethyl benzidine to visualize the labeled neurons. The total number of labeled PGSN and SN were counted and the ratio (PGSN:SN) determined for each of the five nerves. The average PGSN:SN ratio from upper extremity nerves (0.40) is 2 1/2 times greater than the ratio determined for branches of the trigeminal nerve (0.16). The lower proportion of sympathetic neurons within the trigeminal nerves provides an anatomic explanation for the lower incidence of orofacial causalgia consistent with the currently accepted etiology.

Animals↗

PubMed1989

Synaptic substrates for enkephalinergic and serotoninergic interactions with dental primary afferent terminals in trigeminal subnucleus interpolaris: an immunocytochemical study using peroxidase and colloidal gold.

Pain processing in the trigeminal complex has been thought to reside primarily in the spinal subnucleus caudalis (Vc). However, trigeminal tractotomies eliminating primary afferent input to Vc and severance of secondary trigemino-thalamic fibers from Vc do not disturb pain perception from the central face and oral cavity. Furthermore, large numbers of neurons that are highly responsive to noxious stimuli and suppressed by inputs from the periaqueductal gray and raphe complex have been identified in subnuclei interpolaris (Vi) and oralis (Vo). Therefore, the purpose of this study was to assess the distribution and spatial arrangements of nociceptive modulatory transmitters with nociceptive afferents and trigemino-thalamic relay cells in the rostral portion of the spinal trigeminal nuclear complex. The dental pulp contains predominantly nociceptors that project to all three subdivisions of the trigeminal spinal complex. These projections were visualized by anterograde transganglionic transport of horseradish peroxidase or by degeneration following administration of toxic ricin to the pulp chambers. The spatial arrangements of dental primary afferents with enkephalinergic (ENK) and serotoninergic (5HT) inputs was then assessed by employing avidin-biotin peroxidase and protein-A colloidal gold double-labeling immunocytochemistry. Trigemino-thalamic relay cells were also labeled by retrograde transport of HRP after stereotaxic injections into the ventrobasal thalamus. ENK and 5HT immunoreactivity was found in the ventrolateral quadrant and lateral margin of Vi, together with the adjacent interstitial nucleus (IN). This activity extended from the caudal pole of Vi and the periobex region, where it was most dense, rostrally to a position approximately 2.9 mm from the Obex. Neither ENK nor 5HT immunoreactivity was observed in Vo. Primary dental afferents projected into the ventromedial quadrant of rostral Vi and were found in the ventrolateral quadrant and dorsal aspect of the subnucleus farther caudally. They appeared as simple boutons with single contacts or as larger, sometimes scalloped terminals that formed multiple contacts. Postsynaptic elements were usually small dendritic profiles, although relay cell somata rarely received primary afferent inputs. Many primary afferents entered areas of synaptic clustering and contacted enkephalinergic dendrites, some of which were also postsynaptic to serotoninergic synapses. Alternatively, primary afferents contacted unlabeled processes that were also postsynaptic to the enkephalinergic element to form a triad arrangement. The least common occurrence was axo-axonic contacts in which enkephalinergic synapses were presynaptic to primary afferents. Both enkephalinergic and serotoninergic synaptic categories displayed round vesicles and generally formed asymmetric junctions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Golgi and immunocytochemical analysis of neurons in trigeminal subnucleus interpolaris: correlations with cellular localization of enkephalin.

Recent electrophysiological evidence shows that rostral levels of the trigeminal spinal complex are concerned with pain processing from receptive fields in the face and oral cavity. The ventrolateral quadrant of the subnucleus interpolaris contains concentrations of enkephalin, dynorphin, serotonin, substance P and GABA [Matthews M. A., Hernandez T. V. and Liles S. L. (1987) Synapse 1, 512-529; Matthews M. A., McDonald G. K. and Hernandez T. V. (1988) Somatosensory Res. 5, 205-217]. These transmitters have also been localized to the fusiform and stalked cells in Laminae I and II of the subnucleus caudalis [Basbaum A. I. and Fields H. L. (1984) A. Rev. Neurosci. 7, 309-338]. The present study compares Golgi impregnations of the subnucleus interpolaris with sections at the same levels immunoreacted against enkephalin to determine if comparable cells exist in the subnucleus interpolaris and if they occur predominantly in the ventrolateral quadrant of the subnucleus. Twelve, young adult cats were killed by perfusion, the brainstems removed and either processed for rapid Golgi impregnation or sectioned and immunoreacted for enkephalin using the avidin-biotin Vectastain method. Golgi impregnated tissue was sectioned in the coronal, transverse or sagittal plane to insure the most advantageous visualization of cells with a directional bias in their dendritic arbors. The subnucleus interpolaris contained several distinctive cell types. The predominant neuron throughout the subnucleus was the smooth pyramidal cell or multipolar cell, characterized by a large round soma (15-25 microns diameter) and a spherical dendritic arborization which allowed its identification in all planes of section. The second cell type was the fusiform cell which had a smaller ovoid soma (10-15 microns) with narrow, less ramified, dendritic arbors oriented dorsoventrally, thus giving a bipolar appearance. Fusiform cells were most concentrated along the lateral margin of the subnucleus interpolaris. Examination of sections at the same level reacted for enkephalin revealed cells with a bipolar appearance in these same locations. An additional cell population which tended to predominate in the lateral zone was the stalked cell. These displayed a rounded soma (12-20 microns) and were evident only in the transverse or sagittal plane. Two to four primary dendrites arose from the soma and extensively ramified into a dense spiny arbor directed into the body of the subnucleus interpolaris. Many examples contained enkephalin. Islet cells, characterized by a very small oval soma (6-12 microns) and dense, rostrocaudally oriented dendrites, were less common than stalked cells and were located deeper in the nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Water transport properties of cortical cells in roots of nitrogen- and phosphorus-deficient cotton seedlings.

Growth-limiting deficiencies of N or P substantially decrease the hydraulic conductance of cotton (Gossypium hirsutum L.) roots. This shift could result from decreased hydraulic conductivity of cells in the radial flow pathway. A pressure microprobe was used to study water relations of cortical cells in roots of cotton seedlings stressed for N or P. During 10 days of seedling growth on a complete nutrient solution, root cell turgor was stable at 0.4 to 0.5 megapascal, the volumetric elastic modulus increased slowly from 6 to 10 megapascals, and the half-time for water exchange increased from 10 to 15 seconds. In seedlings transferred to N-free solution for 10 days, final values for each of those parameters were approximately doubled. Root cell hydraulic conductivity (cell Lp) was 1.4 x 10(-7) meters per second per megapascal at the time of transfer. In the well-nourished controls, cell Lp decreased over 10 days to 38% of the initial value, but in the N-stressed plants it decreased much more sharply, reaching 6% of the initial value after 10 days. Transfer to solutions without P or with an intermediate level of N also decreased cell Lp. The changes in root cell Lp were consistent with nutrient effects on intact-root water relations demonstrated earlier. However, cell Lp was about half that of the intact root, implying that substantial water flow may follow an apoplastic pathway, bypassing the cortical cells from which these values were derived.

Journal Article↗