Substituted 2-(aminomethyl)piperidines: a novel class of selective protein kinase C inhibitors.
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Enzyme Activation↗
Biomedical subjects
J R Connor
Publications and source records attributed to J R Connor.
Activation of the IL-1 gene in UV-irradiated mouse skin: association with inflammatory sequelae and pharmacologic intervention.
The relationship between ultraviolet irradiation, interleukin-1 production, and inflammatory sequelae and the pharmacologic inhibition of these events was investigated in Balb/c mice exposed to ultraviolet irradiation from a bank of six Westinghouse FS40 sunlamps. The resulting edema (66% increase), inflammatory cell infiltration, and rise in the acute-phase reactant (fourfold) serum amyloid P component was preceded by the activation of the interleukin-1 beta gene and enhanced product formation. Administration of dexamethasone, which is known to inhibit interleukin-1 production, inhibited the inflammatory response to ultraviolet irradiation. Thus, production of interleukin-1 may be one of the initial events leading to the consequences of ultraviolet irradiation exposure.
Animals↗
Expression of transferrin mRNA in the CNS of normal and jimpy mice.
Both the iron mobilization protein transferrin and iron itself are found predominantly in oligodendrocytes in the brain and consequently have been hypothesized to have a role in myelination. This study is designed to begin to understand the mechanism(s) that control the expression of transferrin at the gene level in the nervous system using a hypomyelinating murine mutant (jimpy mouse). With this animal model it is possible to determine if transferrin gene expression in the nervous system is dependent on the presence of a mature oligodendrocytic population. The results demonstrate that normally expression of the transferrin gene increases from postnatal day 5 to 22-25 and then levels off in the adult. In the jimpy mouse, the relative amount of transferrin gene expression is less than that of littermate controls at 5 days of age. Furthermore, transferrin gene expression does not increase with age beyond the level observed at postnatal day 5 in the jimpy mouse. It is concluded from this study that the majority of the transferrin mRNA in the mouse brain is expressed by and/or requires the presence of a mature oligodendrocytic population.
Animals↗
Transferrin expression in myelinated and non-myelinated peripheral nerves.
Transferrin and its receptor are involved in the delivery of iron to most cells. Previous studies have demonstrated that transferrin is associated with oligodendrocytes, the myelin-producing cells in the central nervous system. In the peripheral nervous system, the Schwann cell produces myelin. This study used immunohistochemistry and immunoblot analysis to determine whether expression of transferrin is unique to myelinated peripheral nerves. Immunohistochemical examination demonstrated cytoplasmic accumulation of transferrin in Schwann cells of the myelinated sciatic nerve, but not in the unmyelinated cervical sympathetic trunk. Immunoblot analysis revealed there is 10 X the amount of transferrin in the sciatic nerve compared to the cervical sympathetic trunk. These results are consistent with the hypothesis that transferrin may play a role in myelination.
Animals↗
Interleukin-1 release by rat synovial cells is dependent on sequential treatment with gamma-interferon and lipopolysaccharide.
To determine the potential regulatory mechanisms involved in synovial cell interleukin-1 (IL-1) release, the ability of gamma-interferon (gamma-IFN) to influence IL-1 release was assessed. Rat synovial cells cultured in the presence of a variety of stimuli, including lipopolysaccharide (LPS), failed to release IL-1. However, pretreatment of synovial cells with gamma-IFN, followed by LPS stimulation, resulted in increased levels of intracellular IL-1 as well as release of IL-1 from the cell. The level of IL-1 release was dependent on the concentration of both gamma-IFN and LPS, and on length of exposure to the gamma-IFN. The kinetic and dose requirements for gamma-IFN-dependent IL-1 release were similar to those for Ia antigen expression, but LPS was necessary for IL-1 messenger RNA induction, intracellular IL-1 accumulation, and IL-1 release. In addition, sequential treatment, i.e., gamma-IFN followed by LPS, was essential for IL-1 induction. Substitution of phorbol ester or calcium ionophore for gamma-IFN did not result in similar IL-1 release. In addition, induction of IL-1 messenger RNA by another stimulus was not sufficient to result in IL-1 release following LPS treatment. These results suggest that release of IL-1 by rat synovial cells requires the production of a regulatory signal, which is inducible by gamma-IFN.
Animals↗
Cellular distribution of transferrin, ferritin, and iron in normal and aged human brains.
The iron transport protein, transferrin, and the iron storage protein ferritin were examined immunohistochemically along with iron in a number of brain regions from normal and aged humans. Two age groups were examined: a middle-aged group (28-49 years), and an older group (60-90 years). Transferrin, ferritin, and iron are found throughout all brain regions examined, predominantly in the perikaryal cytoplasm of cells that are small and round, fitting the description of oligodendrocytes. These cells are present in the optic nerve and in both the gray and white matter of the cerebral cortex, cerebellum, and olfactory bulb in both age groups. Ferritin is also found in microglial cells in the gray matter of most of these brain regions. In the subcortical regions examined (corpus striatum, hippocampus, amygdala), in addition to oligodendrocytes, astrocytes can frequently be observed that contain transferrin, ferritin, and iron. There is an age-related alteration in cell labeling: astrocytes in both gray and white matter contained transferrin in the oldest age group, whereas in the younger group the subcortical transferrin immunoreactivity was confined mostly to oligodendrocytes. Ferritin in the subcortical brain regions is also present in astrocytes but is primarily confined to those in the gray matter, even in the oldest age group. Iron is found predominantly in oligodendrocytes, although a few iron-positive astrocytes and microglia can be identified. These results indicate that (1) normally oligodendrocytes contain much of the iron and iron-binding proteins found in the brain; and (2) an increase in age is associated with altered cellular distribution of iron-binding proteins, but the altered distribution is specific to glial cells. These results suggest glial cells may have previously undescribed functions related to metal regulation and sequestration.
Aging↗
Altered cellular distribution of iron in the central nervous system of myelin deficient rats.
Under normal conditions, iron is found predominantly in oligodendrocytes, the myelin producing cell, in the rat brain. A genetic mutant strain of rats known as myelin deficient rats is examined in the present study because their number of oligodendrocytes is decreased and those oligodendrocytes present are structurally abnormal. The levels of iron in the liver (major site of iron storage) and in the pons-cerebellum did not differ statistically between the myelin deficient rats and the littermate control rats, whereas only half of the iron normally found in the cerebrum-midbrain was present in the myelin deficient rat. Histologically, iron was found predominantly in oligodendrocytes in the littermate control rats, as expected. In the myelin deficient rat, iron staining was confirmed to astrocytes and microglia. The results of this study strongly suggest that iron uptake into the brain continues in the absence of normal oligodendrocytes and myelin. Furthermore, these data suggest that iron metabolism can be substantially altered, as indicated by the accumulation of iron in astrocytes and microglia, when normal or near normal levels of iron are quantitatively demonstrated. The response of astrocytes and microglia to sequester the iron (presumably through phagocytosis) in the absence of invasive damage represents, to our knowledge, a new functional observation for these cells. Based on these observations it is clear that iron histochemistry in combination with quantitative analysis is necessary to interpret data regarding iron physiology, at least in neurobiology, and iron accumulation by astrocytes and microglia may provide clues of altered iron metabolism despite normal iron levels.
Animals↗
Aluminum access to the brain: a role for transferrin and its receptor.
The toxicity of aluminum in plant and animal cell biology is well established, although poorly understood. Several recent studies have identified aluminum as a potential, although highly controversial, contributory factor in the pathology of Alzheimer disease, amyotrophic lateral sclerosis, and dialysis dementia. For example, aluminum has been found in high concentrations in senile plaques and neurofibrillary tangles, which occur in the brains of subjects with Alzheimer disease. However, a mechanism for the entry of aluminum (Al3+) into the cells of the central nervous system (CNS) has yet to be found. Here we describe a possible route of entry for aluminum into the cells of the CNS via the same high-affinity receptor-ligand system that has been postulated for iron (Fe3+) delivery to neurons and glial cells. These results suggest that aluminum is able to gain access to the central nervous system under normal physiological conditions. Furthermore, these data suggest that the interaction between transferrin and its receptor may function as a general metal ion regulatory system in the CNS, extending beyond its postulated role in iron regulation.
Aluminum↗
The development of the transferrin-transferrin receptor system in relation to astrocytes, MBP and galactocerebroside in normal and myelin-deficient rat optic nerves.
The factor(s) which control the onset of myelination are unknown. It is now accepted that transferrin (Tf), the major iron transport protein in vertebrates, is found in oligodendrocytes in the adult brain. Because of the importance of iron in basic cell metabolism we have hypothesized that iron (mobilized by Tf) may be a permissive agent in the process of myelination. The present study was designed to determine with immunohistochemistry the relationship of Tf receptor expression, Tf accumulation, and the expression of myelin components myelin basic protein (MBP) and galactocerebroside (GAlC)) in the developing rat optic nerve. In addition to Tf and its receptor, the developmental pattern for GalC reported in this study has not been examined in the rat optic nerve. Furthermore, a myelin mutant strain of rats was used to determine if a lack of myelin production affects the Tf-Tf receptor system. Our study found that Tf receptor was expressed from birth on blood vessels and was first seen in the parenchyma of the nerve at 8 days of age. The expression of the Tf receptor preceded that of Tf, MBP or GalC. The accumulation of Tf by oligodendrocytes occurred about the same time as the intracellular appearance of MBP and GalC which was shortly after the onset of myelination. Tf-positive cells as well as MBP- and GalC-positive cells increased in number and staining intensity with age whereas the expression of the Tf receptor declined after reaching a peak at 15 days of age. In the optic nerves of myelin-deficient rats, the Tf receptor expression and Tf accumulation was confined to the vasculature. The results of this study suggest that the expression of the Tf receptor is an early event in oligodendrocytic maturation and is followed by the intracellular accumulation of myelin components and Tf. The temporal association of Tf and myelin production suggests that further study is warranted regarding the possibility that the Tf-iron system supports or perhaps even permits the initiation of the process of myelination.
Aging↗
Inhibition of IFN-gamma-induced Ia antigen expression on synovial fibroblasts by IL-1.
Naturally occurring substances capable of the negative regulation of class II molecules on synovial fibroblasts may play an important role in controlling the sustained immune processes ongoing in the rheumatoid joint. We report here that rIL-1 is capable of such a negative regulatory process. The simultaneous addition of rIL-1 and rIFN-gamma to rat synovial fibroblasts resulted in decreased Ia Ag and mRNA expression when compared with synovial fibroblasts treated with IFN-gamma alone. Both rIL-1 alpha and rIL-beta inhibited to a similar degree with the level of inhibition being dependent on both the concentration of IL-1 and IFN-gamma. Other cytokines, including IFN-alpha/beta, IL-2, and TNF, had no antagonistic effect on IFN-gamma-induced Ia expression. Time course experiments showed that IL-1 inhibited when present immediately before addition of IFN-gamma or when added during the first 24 h of IFN-gamma stimulation but not at later time points. Indomethacin failed to reverse the IL-1-mediated inhibition, despite the fact that exogenously added PGE2 also inhibited IFN-gamma-induced Ia expression. IL-1 treatment of synovial cells did not alter the ability of IFN-gamma to bind to the cells. These findings provide evidence for a negative regulatory role for IL-1 on synovial fibroblasts independent of PGE2 production and thus suggest that IL-1 is capable of both pro- and antiinflammatory actions within the rheumatoid joint.
Animals↗
Do oligodendrocytes mediate iron regulation in the human brain?
We used immunohistochemical studies to demonstrate that transferrin (the iron mobilization protein) and ferritin (the iron storage protein) are specifically localized in oligodendrocytes in gray and white matter of the human central nervous system. In addition, iron is also localized predominantly in oligodendrocytes. Oligodendrocytes have been well established as the cells responsible for myelin production in the central nervous system. The results of this study suggest that oligodendrocytes (or a subpopulation of oligodendrocytes) might have the additional function of mediating iron mobilization and storage in the central nervous system.
Adult↗
Interleukin-1 induces interleukin-1 alpha and interleukin-1 beta gene expression in synovial fibroblasts and peripheral blood monocytes.
Cellular interactions involved in the chronic inflammatory response, characteristic of those found in the joints of rheumatoid arthritis patients, were investigated by examining the effect of interleukin-1 (IL-1), tumor necrosis factor alpha, and gamma-interferon on the regulation of IL-1 gene expression and production by synovial fibroblasts. Biologically active IL-1 was detected in lysates of IL-1-treated rat and human fibroblasts that had been isolated from synovial tissue by collagenase digestion. Northern blot analysis of RNA isolated from these cells revealed the expression of IL-1 alpha and IL-1 beta transcripts. Neither the IL-1 transcripts nor the biologic activity of IL-1 was found in untreated synovial fibroblasts. The messenger RNA induction in synovial cells was followed by a time- and dose-dependent expression of intracellular IL-1 activity. Human monocytes and human skin fibroblasts also responded to IL-1 treatment by producing IL-1-specific transcripts. These observations suggest that IL-1 plays a key role in stimulating immune and inflammatory responses and in sustaining those responses through continued production at sites of inflammation.
Animals↗
Interleukin 1 stimulates prostaglandin synthesis and cyclic AMP accumulation in Swiss 3T3 fibroblasts: interactions between two second messenger systems.
Biochemical events elicited by interleukin 1 (IL-1) were studied in Swiss 3T3 fibroblasts. One hour after its addition, IL-1 stimulated synthesis of prostaglandin E2 (PGE2), which continued to accumulate for 4 days. IL-1 also stimulated cAMP accumulation. Indomethacin blocked cAMP accumulation in response to IL-1, suggesting that PGE2 was responsible for the increase. Addition of exogenous PGE2 to indomethacin-treated cells restored cAMP accumulation. IL-1 enhanced thymidine incorporation, and indomethacin attenuated responses to lower concentrations. Thus, PGE2 appeared to play a role in the ability of low concentrations of IL-1 to stimulate thymidine incorporation. PGE2 augmented thymidine incorporation by increasing cAMP accumulation because in the presence of indomethacin addition of exogenous cAMP enhanced thymidine incorporation in response to low concentrations of IL-1. Elevated cAMP further stimulated PGE2 synthesis. Thus, PGE2 and cAMP interacted to potentiate their mutual accumulation. In summary, IL-1 stimulates PGE2 synthesis. PGE2, in turn, stimulates cAMP accumulation which potentiates IL-1-stimulated PGE2 synthesis and thymidine incorporation.
Animals↗
The kallikrein-kininogen-kinin system in chronic inflammation.
We examined bradykinin's effects on macrophages and fibroblasts, two cell types important in the pathogenesis of chronic inflammation. Bradykinin stimulated release of proteins of 18 kDa from macrophages. These proteins caused increased thymocyte proliferation (interleukin 1, IL-1) and completely inhibited lipoprotein lipase (tumor necrosis factor, TNF). When fibroblasts were incubated with bradykinin, PGE2 synthesis was stimulated. Pretreatment with IL-1 or TNF dramatically amplified bradykinin-stimulated PGE2 synthesis. Thus, bradykinin is involved in a positive feedback loop in which bradykinin activates macrophages to release potent inflammatory cytokines; these in turn amplify responsiveness of bradykinin target tissues.
Chronic Disease↗
Interleukin 1 amplifies receptor-mediated activation of phospholipase A2 in 3T3 fibroblasts.
Human recombinant interleukin 1 alpha (IL-1 alpha) and IL-1 beta stimulated prostaglandin E2 synthesis in 3T3 fibroblasts in a time- and concentration-dependent manner. Enhanced prostaglandin E2 synthesis after IL-1 treatment was apparent by 1 hr and continued to increase for at least 2 days. Half-maximal stimulation occurred at 0.5 pM IL-1 alpha or IL-1 beta, and both interleukins were equally effective, with maximal stimulation occurring in response to 5-10 pM IL-1. In contrast to IL-1, bradykinin stimulation of prostaglandin E2 synthesis is rapid; its effect is maximal by 5 min. In cells that had been pretreated with IL-1 for 24 hr, prostaglandin E2 synthesis in response to bradykinin was amplified more than 10-fold. IL-1 also amplified the receptor-mediated formation of prostaglandin E2 by bombesin and thrombin. The lymphokine did not affect bradykinin receptor number or affinity. IL-1 treatment induced phospholipase A2 and cyclooxygenase but not phospholipase C or prostaglandin E isomerase. It also enhanced bradykinin-stimulated GTPase activity, suggesting possible induction of the GTP-binding regulatory protein coupled to the bradykinin receptor. Thus, IL-1 enhanced receptor-mediated release of prostaglandin E2 in response to bradykinin, bombesin, and thrombin by increasing the cellular levels of phospholipase A2, cyclooxygenase, and GTP-binding regulatory protein(s).
Animals↗
Bradykinin as a pain mediator: receptors are localized to sensory neurons, and antagonists have analgesic actions.
Autoradiographic studies localize [3H]bradykinin receptor binding sites to the substantia gelatinosa, dorsal root, and a subset of small cells in both the dorsal root and trigeminal ganglia of the guinea pig. [3H]Bradykinin labeling is also observed over myocardial/coronary visceral afferent fibers. The localization of [3H]bradykinin receptors to nociceptive pathways supports a role for bradykinin in pain mediation. Several bradykinin antagonists block bradykinin-induced acute vascular pain in the rat. The bradykinin antagonists also relieve bradykinin- and urate-induced hyperalgesia in the rat paw. These results indicate that bradykinin is a physiologic mediator of pain and that bradykinin antagonists have analgesic activity in both acute and chronic pain models.
Analgesia↗
Astrocytes in rat fetal cerebral cortical homografts following implantation into adult rat spinal cord.
The present experiment examines astrocytes in fetal cerebral cortical homografts to adult rat spinal cords. The purpose of this study is to determine if astrocytes are structurally organized within the graft. Also, the presence or absence of astrogliosis may be an indicator of the metabolic status of the graft. Embryonic cerebral cortex was taken at 14 days gestational age and transplanted into adult spinal cord at the level of the sixth thoracic vertebra. The homografts were examined at the light and electron microscopic levels from 7 days postimplantation (PI) to 6 months PI with glial fibrillary acidic protein antiserum which is a specific immunohistochemical marker for astrocytes. At 7 days PI, immunoreactive astrocytes were present only at the periphery of the graft and appeared to be associated with blood vessels. By 30 days PI, normal protoplasmic astrocytes were present throughout the graft. No hypertrophied astrocytes are present at 30 days PI, but the numerical density of astrocytes is greater than that of normal cerebral cortical gray matter. Fibrous astrocytes are present in the periphery of the implant and many of these astrocytes extended their processes between the host and the graft. Occasional glial scarring is observed between the gray matter of the host and graft, but generally no glial scar occurred in the interface between the graft and the host gray matter. By 45 days PI, hypertrophied astrocytes can be seen in the graft, but are confined in this age group to perivascular regions.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Regulation of arachidonic acid metabolism in resident and BCG-activated alveolar macrophages: role of lyso(bis)phosphatidic acid.
To dissect mechanisms of arachidonic acid (20:4) metabolism in pulmonary alveolar macrophages (PAM), two distinct cell populations were investigated, resident and BCG-activated rabbit alveolar macrophages. After purified resident PAM were labeled overnight with [3H]20:4, radioactivity was localized primarily within lyso(bis)phosphatidic acid (L(bis)PA) (13.1% +/- 1.7), phosphatidylethanolamine (PE) (22.8% +/- 0.8), and phosphatidylcholine (PC) (26.7% +/- 1.7), with lesser amounts recovered in phosphatidylserine plus phosphatidylinositol (PS/PI) (9.2 +/- 0.8%). By contrast, analysis of the phospholipid classes from prelabeled BCG-activated PAM revealed that the amount of [3H]20:4 contained in L(bis)PA was profoundly decreased (4.7% +/- 0.4), p less than 0.003), whereas [3H]20:4 contained within other BCG phospholipids remained unchanged. Moreover, L(bis)PA, which composed 18.6% +/- 1.2 of the total phospholipid phosphorus of resident PAM, was reduced to 4.1% +/- 0.1 in BCG-activated macrophages (p less than 0.01). Phospholipase A2 from snake venom or from pancreas failed to release 20:4 from L(bis)PA, and lipase (phospholipase A1) from Rhizopus delmar liberated no more than one-third of this arachidonate. These results suggest that much of the arachidonate is not mobilized by classical phospholipases A1 and A2. When [3H]20:4-labeled PAM were stimulated with 1 microM 12-O-tetradecanoyl-phorbol-13-acetate (TPA), a loss of [3H]20:4 was observed from L(bis)PA, PE, PC, and PS/PI, with a concomitant increase in the synthesis of Hete and leukotriene C4. BCG-activated PAM exposed to either TPA or 3.8 microM calcium ionophore A23187 liberated [3H]20:4 solely from PE and PC, with diminished 20:4 oxidative metabolism. Analysis of the specific radioactivities of phospholipids obtained from resident PAM prelabeled with [3H]20:4 or [32P]i demonstrated that the specific activity of [32P]L(bis)PA was negligible, whereas that of [3H]20:4 was quite high. In addition, L(bis)PA deacylation induced by TPA in resident PAM was always accompanied by a corresponding loss of [3H]20:4 from phosphatidylinositol (PI), suggesting that metabolism of this novel phospholipid proceeded by a deacylation-reacylation reaction rather than by de novo synthesis. BCG-activated PAM, which exhibited depressed eicosanoid formation, consistently failed to deacylate [3H]20:4 from L(bis)PA or PI. These studies demonstrate that, unlike 20:4 derived from PE and PC by BCG-activated PAM, L(bis)PA may indeed provide a novel source of 20:4 that is tightly coupled to the lipoxygenase pathway.
Animals↗