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D Parkinson

Publications and source records attributed to D Parkinson.

At least 19 recordsLinked to original sources
PubMed1992

EMA: a developmentally regulated cell-surface glycoprotein of CNS neurons that is concentrated at the leading edge of growth cones.

To identify cell-surface molecules that mediate interactions between neurons and their environment during neural development, we used monoclonal antibody techniques to define a developmentally regulated antigen in the central nervous system of the mouse. The antibody we produced (2A1) immunolabels cells throughout the central nervous system; we analyzed its distribution in the developing cerebral cortex, where it is expressed on cells very soon after they complete mitosis and leave the periventricular proliferative zone. Expression continues into adult life. The antibody also labels the epithelium of the choroid plexus and the renal proximal tubules, but does not label neurons of the peripheral nervous system in the dorsal root ganglia. In dissociated cell culture of embryonic cerebral cortex, 2A1 labels the surface of neurons but not glia. Immunolabeling of neurons in tissue culture is particularly prominent on the edge of growth cones, including filopodia and the leading edge of lamellipodia, when observed with either immunofluorescence or freeze-etch immunoelectron microscopy. Immunopurification with 2A1 of a CHAPS-extracted membrane preparation from brains of neonatal mice produces a broad (32-36 kD) electrophoretic band and a less prominent 70 kD band that are sensitive to N-glycosidase but not endoglycosidase H. Thus the 2A1 antibody recognizes a developmentally regulated, neuronal cell surface glycoprotein (or glycoproteins) with complex N-linked oligosaccharide side chains. We have termed the glycoprotein antigen EMA because of its prominence on the edge membrane of growth cones. EMA is similar to the M6 antigen (Lagenaur et al: J. Neurobiol. 23:71-88, 1992) in apparent molecular weight, distribution in tissue sections, and immunoreactivity on Western blots, suggesting that the two antigens are similar or identical. Expression of EMA is a very early manifestation of neuronal differentiation; its distribution on growth cones suggests a role in mediating the interactions between growth cones and the external cues that guide them.

Animals↗
PubMed1992

Changes in hippocampal monoamine concentration following halothane anesthesia and concussion.

The concentration of norepinephrine in the hippocampus of rats anesthetized with halothane (Wyeth-Ayerst, Philadelphia, Pa) is found to be markedly increased, presumably due to the stress of handling and administering the anesthetic. This increased norepinephrine concentration persists for about 50 minutes but is obliterated when the anesthetized rat is concussed. This 50-minute period corresponds to the time it takes for a rat (or human), comatose for 1-2 seconds following concussion, to regain normal memory. No changes in 3,4-dihydroxybenzene-acetic acid (DOPAC), 3-(3,4-dihydroxyphenyl) alanine (L-DOPA), and 3,4-dihydroxybenzylamine (DHBA) were noted. 5-Hydroxy indole acetic acid (HIAA) showed a depression at 5 minutes and again at 30 minutes, changes that were consistent but not considered statistically significant.

Anesthesia, Inhalation↗
PubMed1992

The immune response against foot-and-mouth disease virus: influence of the T lymphocyte growth factors IL-1 and IL-2 on the murine humoral response in vivo.

Recombinant and pure "natural" IL-1 and IL-2 were compared with the muramyl dipeptide (MDP) component of Freund's adjuvant for their capacity to enhance the humoral immune response against foot-and-mouth disease (FMD) virus antigen. Using a dose of this antigen which alone did not give a detectable immune response, anti-FMD virus antibody was measured at 14 and 28 days post-vaccination. Although IL-1 could enhance the response against the virus antigen, in particular when administered 24 h before the vaccine, this was not as strong as that obtained when MDP was adjuvant. In contrast, IL-2 was at least as efficient as MDP when applied concomitantly with the antigen. If the IL-2 treatment preceded the vaccination by 24 h, a diminution in the magnitude of the response was seen; however, this was countered by the fact that 10 times less IL-2 was required, compared with concomitant cytokine/vaccine administration, in order to have the maximum effect. When both IL-1 and IL-2 were used together, an even greater enhancement of the immune response against FMD virus antigen was observed, but only when given concomitantly with the antigen. These results demonstrate the relevance of T lymphocyte growth factors to the immune response against FMD virus, and how current immunological and biotechnological knowledge could be applied to the improvement of adjuvant systems in a chemically and biologically defined manner.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

Carboxypeptidase H in bovine pituitary gland: soluble forms are not processed at the C-terminus.

Carboxypeptidase H (CP-H) has been characterized in anterior and posterior lobes of bovine pituitary with regard to subcellular distribution, enzymatic properties, nature of membrane association, number of forms and C-terminal processing. Anterior lobe contained both soluble and membrane forms of CP-H with similar enzymatic properties after extraction at pH 5.5. The soluble forms represented about 70% of the total activity. Two soluble and two membrane forms, of 53 and 56 kDa, were demonstrated by immunoblotting and after purification. The amount of the 56 kDa soluble form increased with the salt content of the extraction buffer. Endoglycosidase digestions showed that the difference in size was not due to differential N-linked glycosylation and also showed that CP-H oligosaccharides do not become resistant to endoglycosidase H. CP-H in posterior lobe was also composed from about 70% soluble and 30% membrane forms. Only 53 kDa CP-H was detected in soluble and membrane fractions of posterior lobe. All forms of CP-H from both lobes reacted with antiserum directed to the C-terminus. These results do not support previous observations that soluble and membrane forms of CP-H can be distinguished by size and C-terminal processing.

Amino Acid Sequence↗
PubMed1992

Concussion is completely reversible; an hypothesis.

It is hypothesized that there is an entity properly called 'concussion', a transient loss of neuronal function without permanent neuronal damage, as defined years ago by Derek-Denny Brown. This implies that multiple concussions leave no deficit. n +1 times zero is still zero. Arguments are presented indicating that there is a margin of safety between the acceleration inducing 1-10 s loss of function (concussion) and that inducing permanent damage (contusions, lacerations).

Boxing↗
PubMed1992

Production of fluorine-18 labeled (3-N-methyl)benperidol for PET investigation of cerebral dopaminergic receptor binding.

The multi-millicurie synthesis of the D-2 receptor ligand [18F](3-N-methyl)benperidol (NMB; 1-[3-(4'- [18F]fluorobenzoyl)propyl]-4-(2-keto-3-methyl-1- benzimidazolinyl)piperidine) is described. [18F]NMB was produced via a 3-step reaction sequence with an overall radiochemical yield of 5-10% and a specific activity greater than 3000 Ci/mmol within 100 min. In vitro binding assays indicated that NMB has high affinity for D-2 receptors in primate brain (K1 = 3.6 nM), with a receptor specificity exceeding that of spiperone. The technique described here permits the routine production of 10-20 mCi of this promising radiopharmaceutical for PET study of D-2 receptor binding in vivo.

Animals↗
PubMed1992

Carboxypeptidase H processing and secretion in rat clonal beta-cell lines.

Carboxypeptidase H (CP-H, EC 3.4.17.10) removes C-terminal basic amino acids from insulin and many other peptide hormone intermediates in endocrine and neural tissues. CP-H was studied in two rat insulinoma-derived clonal beta-cell lines that were chosen in part because their profile of hormone production is restricted. Although RIN 1046-38 cells predominantly produce insulin and RIN 1046-44 cells contain no known polypeptide hormone, both cell lines contain comparable levels of CP-H. The distribution of CP-H in RIN cells differs from primary tissues since only 25% of cellular CP-H is soluble whereas approximately 75% is associated with the membrane fraction. Immunoblotting with both N- and C-terminal antibodies detects a single 54 kilodalton (kDa) band corresponding to the mature form of CP-H in soluble and membrane RIN cell extracts and incubation media. Pulse-chase analysis shows that a 56 kDa precursor is initially synthesized and rapidly processed to a mature 54 kDa form. Newly synthesized, mature CP-H is detectable in the media by 30 min. Approximately 50% is retained within cells after 3 h of incubation. Secretion of CP-H activity from both RIN cell types and insulin from 1046-38 cells is acutely stimulated by membrane depolarization with KCl and attenuated by 10 mM MgCl2. Dense core secretory vesicles characteristic of the regulated secretory pathway are evident on transmission electron microscopy of both RIN cell lines. Thus, mature CP-H exists primarily as a membrane-associated form in RIN cells, but all forms of CP-H, including soluble and secreted enzyme, retain an intact C-terminus.

Animals↗
PubMed1991

The effect of age on binding of MK-801 in the cat visual cortex.

We have examined the effect of age on the binding of (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine maleate (MK-801) in the cat visual cortex. We hypothesized that this binding might change with age because: (1) MK-801 binds to a site associated with the N-methyl-D-aspartate (NMDA) receptor; (2) the NMDA receptor complex has been implicated in neural plasticity; (3) plasticity in the cat visual cortex is age dependent. We used standard receptor binding techniques to measure MK-801 binding in membrane homogenates in cats aged 7 days (d), 21 d, 43 d, 83 d, 7-8 months (mo) and over 2 years. Glutamate (100 microM), glycine (30 microM) and spermidine (20 microM) were used to enhance binding. We found that MK-801 binding is maximal at about 6 weeks of age, decreases slightly by 83 days and then decreases more dramatically in adults. Saturation analysis showed that the of binding with age resulted from variation in number of binding sites and not from variation in affinity. The ability of Mg2+ to inhibit MK-801 binding did not change with age. Dark rearing did not alter the development of MK-801 binding sites.

Aging↗
PubMed1991

Effects of dark-rearing on the retinal dopaminergic system in the neonatal and postnatal guinea pig.

To appraise the extent of light responsivity of the retinal dopaminergic system in the early postnatal period, dopamine content (DA) of retinas of cycling-light-reared and dark-reared guinea pigs was determined. DA storage postnatally was suppressed in dark-reared animals. Their retinas responded to a brief light stimulus by rapidly increasing DOPA synthesis and DA utilization, but not to the extent of the response of cycling-light-reared animals. Dopaminergic retinal neurones depend on light stimulus for the complete development of some of their neurochemical characteristics.

Animals↗
PubMed1991

Human spinal arachnoid septa, trabeculae, and "rogue strands".

This study was undertaken because of confusion arising from a diversity of names, descriptions, and drawings of the human spinal subarachnoid septa and trabeculae in the standard texts and dictionaries. Sixty-two complete human cords were examined under the dissecting scope. The finely "woven" adult arachnoid membrane was two-layered, and there were essentially no connecting septa or trabeculae between the cord and the arachnoid membrane anteriorly. Posteriorly, in the upper cervical region there is a scanty series of connecting fibers and fenestrated sheets 1 or 2 mm on either side of the midline; these become progressively more extensive in the lower cervical region, remain extensive to the lumbar enlargement, beyond which they progressively dwindle to end abruptly at the filum terminale origin. Throughout the cauda equina, strands are haphazardly arranged connecting the roots and supporting blood vessels. These occasionally become tangentially adherent to the arachnoid membrane. Throughout the length there are many unexplained, redundant, nonbranching, beaded, thicker "rogue strands". All of the above are of a different character from the right-angle fiber arrangement of the denticulate ligament, the two leaves of which are often separated form segmental longitudinal tunnels. The nerve rootlets (fila radicularia) for each dermatome are joined by strands and webs to each other. There was no evidence of change in number or type of connection with age.

Adolescent↗