Mechanism of action of insulin on pancreatic exocrine secretion in perfused rat pancreas

In conscious rats, we have previously shown that immunoneutralization of circulating insulin with a rabbit anti-insulin serum abolished the pancreatic exocrine secretion stimulated by a meal or a combination of exogenous secretin and cholecystokinin octapeptide (CCK-8). To investigate the mechanism of endogenous insulin action on the exocrine pancreas, isolated rat pancreata were perfused with intra-arterial infusion of Krebs-Henseleit solution (37 degrees C) at 1.2 ml/min, whereas both pancreatic juice and portal venous effluent were collected separately in 15-min samples. Simultaneous intra-arterial infusion of secretin and CCK-8 in doses of 0.75 and 4.2 pmol/h; respectively, significantly increased volume, bicarbonate, and protein output in 7 rat pancreata (P < 0.01). When a rabbit anti-insulin serum was administered intra-arterially (0.1-ml bolus followed by 0.1 ml for 10 min), pancreatic secretion of volume, bicarbonate, and protein output was profoundly suppressed (n = 7, P < 0.01), whereas a normal rabbit serum failed to influence pancreatic secretion. The decrease in pancreatic secretion by the antiserum coincided with a significant increase in somatostatin in portal venous effluent from 1.4 +/- 0.2 to 4.1 +/- 0.8 pM (n = 6, P < 0.05). The combined administration of a rabbit antisomatostatin serum (0.4 ml) and the anti-insulin serum partially reversed the effect of the anti-insulin serum alone. Thus the pancreatic secretion was significantly greater than that achieved by the anti-insulin serum alone (P < 0.05). These observations strongly suggest that the action of insulin on exocrine pancreas is mediated by its local or paracrine action.(ABSTRACT TRUNCATED AT 250 WORDS)

Activity-dependent variations in conduction velocity of C fibers of rat sciatic nerve

Changes in the conduction velocity and subsequent conduction block were characterized following impulse activity in single C fibers of rat sciatic nerves. C fibers which had the same resting conduction velocities often exhibited quite different profiles of the activity-dependent latency change and/or conduction block following impulses. The results imply underlying variation among C fibers in the activity-dependent excitability changes, especially in the build-up and recovery of the hypoexcitable phases.

Secretion-capture role for apolipoprotein E in remnant lipoprotein metabolism involving cell surface heparan sulfate proteoglycans

To determine the impact of enhanced apolipoprotein (apo) E secretion on the mechanism of remnant lipoprotein uptake, rat hepatoma cells (McA-RH7777) were stably transfected with normal human apoE3 or receptor binding-defective apoE-Leiden. After a 2-h incubation, the human apoE secreted from the transfected hepatocytes was 10-12 times greater than the endogenous rat apoE. The apoE3-transfected cells bound and internalized rabbit beta-very low density lipoproteins (beta-VLDL) to a much greater degree than did apoE-Leiden-transfected cells and nontransfected cells. The apoE3-secreting cells displayed a 2-3.5-fold enhancement of cell-associated beta-VLDL compared to either the apoE-Leiden-transfected or nontransfected cells. Fluorescently labeled beta-VLDL were observed to concentrate within intracellular granules of the apoE3-transfected cells, presumably within endosomes and lysosomes. Furthermore, electron microscopy revealed that the apoE3-secreting cells displayed abundant beta-VLDL and chylomicron remnants on their cell surfaces and microvilli, in contrast to non-transfected or apoE-Leiden-secreting cells. Electron microscopy also revealed an abundance of chylomicron remnants within intracellular vesicles and multivesicular bodies of apoE3-transfected hepatocytes. Heparinase treatment (3 units/ml) completely abolished the increased association of beta-VLDL with apoE3-transfected cells but did not affect the limited association of beta-VLDL with apoE-Leiden-transfected or nontransfected cells. We established that the apoE3-enriched beta-VLDL were bound to cell surface heparan sulfate proteoglycans, as was the newly synthesized and secreted apoE3 (approximately 12% of the total secreted apoE3 was released by heparinase and suramin; 4% by heparin). In addition, reisolation of beta-VLDL by fast performance liquid chromatography after their incubation with exogenous apoE3, with medium from apoE3-secreting cells, or with the apoE3-secreting cells themselves revealed that the particles were enriched in apoE3 and displayed enhanced binding. These results suggest a secretion-capture role for apoE and indicate an important role for heparan sulfate proteoglycans on the cell surface for remnant lipoprotein metabolism.

Effect of digested protein on pancreatic exocrine secretion and gut hormone release in the dog

The hormonal mechanisms mediating protein-stimulated pancreatic exocrine secretion were investigated in four conscious dogs with gastric cannulas and Thomas duodenal cannulas. Pancreatic juice was collected by direct cannulation of the main pancreatic duct in response to intraduodenal infusates prepared with cooked beef liver. When the homogenized liver was administered intraduodenally, cholecystokinin (CCK) in plasma significantly increased. This increase was accompanied by a significant increase in pancreatic exocrine secretion, including volume, bicarbonate, and protein output. The liver homogenate incubated with pancreatic enzymes further increased both plasma CCK and exocrine pancreatic secretion. However, plasma secretin was not affected by the protein digests. Intravenous administration of loxiglumide at the rate of 5.0 and 10.0 mg/kg/h resulted in a significant decrease in the stimulated pancreatic secretion of fluid, bicarbonate, and protein. The study indicates that endogenous CCK released by protein digests exerts not only enzyme secretion but also bicarbonate secretion in dogs.

Type III hyperlipoproteinemic phenotype in transgenic mice expressing dysfunctional apolipoprotein E

Transgenic mice were prepared that expressed a dysfunctional apo E variant, apo E (Arg-112, Cys-142), which is associated with dominant inheritance of type III hyperlipoproteinemia (type III HLP) in humans. Among eight founder mice, plasma apo E (Arg-112, Cys-142) levels varied 100-fold and directly correlated with plasma cholesterol and triglyceride levels. On a normal chow diet, mice expressing high levels (> 70 mg/dl) of the dysfunctional apo E had grossly elevated plasma lipids, with cholesterol levels of up to 410 mg/dl and triglyceride levels of up to 1,210 mg/dl. Upon agarose electrophoresis, plasma from these mice demonstrated beta-very low density lipoproteins (beta-VLDL). Mice expressing low (< 2.5 mg/dl) or intermediate (21 mg/dl) levels of the apo E variant had much less severe hyperlipidemia and did not have beta-VLDL. Although the transgenic mouse beta-VLDL were enriched in cholesteryl esters compared with normal mouse VLDL, they were not as cholesterol enriched as human beta-VLDL from type III HLP subjects. Transgenic mouse beta-VLDL injected into normal mice were cleared from plasma at a significantly slower rate than normal mouse VLDL, demonstrating the impaired catabolism of beta-VLDL. Thus, transgenic mice expressing high levels of the dysfunctional apo E (Arg-112, Cys-142) variant have many characteristics of the human type III HLP phenotype and appear to be a suitable animal model for this disorder.

Reverse transcription and polymerase chain reaction technique for quantification of mRNA in primary astrocyte cultures

The reverse transcription and polymerase chain reaction technique (RT-PCR) was assessed for the quantification of changes in mRNA levels from primary astrocyte cultures. The effects of dibutyryl cyclic AMP (dBcAMP) on glial fibrillary acidic protein (GFAP) mRNA and the effects of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and lipopolysaccharide (LPS) on interleukin-6 (IL-6) mRNA were examined. Two quantitative PCR methods were used: one involved carrying out the reaction in the exponential phase and the other involved the coamplification of a competitive target sequence. Increased GFAP mRNA in response to chronic dBcAMP treatment and increased IL-6 mRNA in response to TNF-alpha/IL-1 beta were readily detected. Both RT-PCR techniques were found to be suitable for the detection of large as well as smaller (twofold) changes in mRNA levels. The advantages and limitations of RT-PCR for mRNA quantification are discussed.

Effects of pancreatic polypeptide on insulin action in exocrine secretion of isolated rat pancreas

1. Effects of pancreatic polypeptide (PP) on insulin action in pancreatic exocrine secretion was investigated by using an isolated rat pancreas that was perfused with Krebs-Henseleit solution containing 2.5 mM glucose, 0.1% bovine serum albumin and 3% Dextran T-70 at a vascular flow rate of 1.2 ml min-1. 2. Cholecystokinin-8 (CCK-8) at a concentration of 14 pM stimulated basal flow rate and amylase output of the isolated pancreas. Twenty-five millimolar glucose not only increased the basal flow rate and amylase output but also potentiated the CCK-stimulated flow rate and amylase output. 3. Porcine insulin, administered intra-arterially at a concentration of 100 nM, also increased the basal flow rate and amylase output, and also potentiated the CCK-stimulated flow rate and amylase output. 4. Rat PP, given intra-arterially at a concentration of 10 pM, completely abolished the potentiation effects of both the 25 mM glucose and the exogenous insulin on the CCK-stimulated flow rate and amylase output. Rat PP also inhibited the flow rate and amylase output increased by either 25 mM glucose alone or exogenous insulin alone. However, rat PP did not change the flow rate and amylase output stimulated by CCK-8 alone. 5. These results indicate that insulin is an important stimulatory hormone of pancreatic exocrine secretion, and that PP exerts the inhibitory role in pancreatic exocrine secretion by modulating the insulin action.

Infectious bill atrophy syndrome caused by parvovirus in a co-outbreak with duck viral hepatitis in ducklings in Taiwan

In October 1989, an epizootic duckling disease with high mortality occurred in Taiwan. The disease was characterized by droopiness, inappetence, ataxia, ruffled feathers, and watery diarrhea. Affected ducklings were lame, were unable to stand, showed opisthotonos, and often died 3 or 4 days after the onset of the disease. Tolerant maturing ducklings displayed atrophic upper bills with a protruding tongue and became stunted as they reached maturity. No diagnostic histopathologic lesions were found in these ducklings. Fourteen parvovirus isolates, 33 duck viral hepatitis virus (DVHV) isolates, two adenovirus isolates, and two reovirus isolates were obtained and identified from more than 500 sick ducklings in the epizootic. The epizootic was diagnosed as a co-outbreak of duck parvovirus infections and duck viral hepatitis. The high mortality in ducklings and the bill atrophy syndrome were reproduced in ducklings by inoculating the parvovirus isolates alone. The epizootic was controlled by an emergency immunization program of ducklings with sera collected from recovered ducks or a bivalent inactivated vaccine composed of local DVHV and parvovirus isolates.

Immunohistochemical localization of basic fibroblast growth factor in cultured rat astrocytes and oligodendrocytes

The distribution of basic fibroblast growth factor in cultured astrocytes and oligodendrocytes was examined using immunocytochemistry. The results demonstrate a localization of basic fibroblast growth factor immunoreactivity predominantly in astrocyte nuclei at all stages of differentiation. Cytoplasmic and process staining was best detected during early stages of differentiation, under normal growth conditions or as a result of treatment with dibutyryl cyclic adenosine monophosphate. Astrocytes at all stages of differentiation bound antibody-complexed bFGF, suggesting the presence of cell-associated low affinity binding sites for the growth factor. Our studies also show the presence of immunoreactivity for basic fibroblast growth factor in process-bearing oligodendrocytes. These results suggest a role for endogenous basic fibroblast growth factor in astrocyte and oligodendrocyte growth and function.

Astrogliosis in culture: I. The model and the effect of antisense oligonucleotides on glial fibrillary acidic protein synthesis

Astrogliosis is a predictable response of astrocytes to various types of injury caused by physical, chemical, and pathological trauma. It is characterized by hyperplasia, hypertrophy, and an increase in immunodetectable glial fibrillary acidic protein (GFAP). As GFAP accumulation is one of the prominent features of astrogliosis, inhibition or delay in GFAP synthesis in damaged and reactive astrocytes might affect astrogliosis and delay scar formation. The aim of this study is to investigate the possibility of utilizing antisense oligonucleotides in controlling the response of astrocytes after mechanically induced injury. We scratched primary astrocyte cultures prepared from newborn rat cerebral cortex with a plastic pipette tip as an injury model and studied the astrogliotic responses in culture. Injured astrocytes became hyperplastic, hypertrophic, and had an increased GFAP content. These observations demonstrate that injured astrocytes in culture are capable of becoming reactive and exhibit gliotic behaviors in culture without neurons. The increase in GFAP content in injured astrocytes could be inhibited by incubating the scratched culture with commercially available liposome complexed with 3' or 5' antisense oligonucleotides (20 nt) in the coding region of mouse GFAP. The scratch model provides a simple system to examine in more detail the mechanisms involved in triggering glial reactivity and many of the cellular dynamics associated with scar formation. Antisense oligonucleotide treatment could inhibit the GFAP synthesis in injured astrocytes, hence it may be applicable in modifying scar formation in CNS injury in vivo.

Stimulation of human monocytes by anti-CD3 monoclonal antibody: induction of inflammatory mediator release via immobilization of Fc receptor by adsorbed immunoglobulin and T-lymphocytes

Human monocytes released superoxide anion, prostaglandin E2, leukotriene B4, IL-1, and TNF when exposed to plastic surfaces coated with murine anti-CD3 monoclonal antibody, OKT 3. Stimulation of mediator release by OKT 3 was dependent on the amount of antibody immobilized onto wells of plastic tissue culture plates. Soluble antibody or antibody adsorbed to monocytes and reacted with an aggregating ("cross-linking") second antibody failed to induce mediator release. Monocytes "armed" with OKT 3 formed rosettes with T cells in a fashion indistinguishable from that seen between monocytes and T cells sensitized with OKT 3. Monocytes with adsorbed OKT 3 antibodies released IL-1 beta and TNF-alpha when exposed to unsensitized T cells, although increased superoxide release could not be detected. OKT 4a, a murine IgG2a antibody that reacts with a different T cell epitope (CD4), failed to induce cytokine release from monocytes when cross-linked by T cells or a CD4+ T cell line, even in the presence of IL-2 or IFN-gamma. These data indicate that certain antibodies bound to Fc receptors (FcR) of monocytes may trigger monocyte function when reacting with cells bearing the appropriate target antigens. FcR-mediated signaling resulting in mediator release may be involved in initiating or regulating the immune response. Furthermore, systemically administered monoclonal antibodies may induce inflammatory responses and their attendant symptomatologies via their interaction with FcR-bearing inflammatory cells.

Differential turnover of enzymes involved in human monocyte eicosanoid metabolism. Selective inhibition of cyclooxygenase product formation by cycloheximide in the absence of effects on 5-lipoxygenase or phospholipase A2

Human monocytes treated with cycloheximide (CHX) demonstrated a concentration- and time-dependent inhibition of prostaglandin E2 (PGE2) synthesis and release in response to stimulation with phorbol myristate acetate, ionomycin, serum-treated zymosan, or concanavalin A. The effect of CHX required preincubation and was largely reversible within 2 hr. Thromboxane A2 release was affected similarly but no comparable effects were observed on labeled arachidonic acid release or leukotriene B4 generation. The PGE2 response was also inhibited by CHX when monocytes were given exogenous arachidonic acid with or without stimulation. CHX pretreatment also comparably decreased the amount of immunoreactive cyclooxygenase in resting and stimulated monocytes. These data indicate that monocyte cyclooxygenase, in contrast to phospholipase A2 or 5-lipoxygenase and their regulatory proteins, turns over rapidly and may be a target for up- or down-regulation by pharmacologic or (potentially) physiologic agents which affect protein synthesis or degradation.

Inflammatory mediator release from human monocytes via immobilized Fc receptors. Its potential role in adverse reactions to systemic monoclonal antibody therapy

Human monocytes released superoxide anion, IL-1, and TNF subsequent to binding of their Fc receptor I to murine IgG2a or rabbit IgG. Fc receptor II binding to murine IgG2b or IgG1 had similar consequences. Immobilized murine monoclonal antibodies, IgG2a anti-CD3 (OKT3) or IgG1 anti-CD44 also induced superoxide anion and monokine production. Monocytes bound OKT3 via FcRI and responded to immobilized OKT3 by inflammatory mediator release in the absence of T cells. These results suggest that direct interaction of immunoglobulins with monocytes via FcR may represent an important phase of the pathophysiology of adverse reactions to systemic monoclonal antibodies.

Neurohormonal mechanism of pancreatic exocrine secretion stimulated by sodium oleate and L-tryptophan in dogs

In the present investigation, we have studied the effect of atropine on the pancreatic secretion stimulated by intraduodenal administration of either sodium oleate or exogenous cholecystokinin (CCK). In four dogs prepared with gastric and Thomas duodenal cannulas, pancreatic juice was collected for measurement of volume, bicarbonate, and protein output, and peripheral venous blood samples were obtained for radioimmunoassay of both secretin and CCK. Volume, bicarbonate, and protein output of the pancreatic juice increased significantly in response to sodium oleate (1-4 mmol/h) in a dose-dependent manner. The increase in pancreatic secretion paralleled the increments in both plasma CCK and secretin. Atropine given intravenously suppressed completely both pancreatic secretion and release of CCK stimulated by sodium oleate, whereas the release of secretin was not affected. Pancreatic secretion was significantly increased in a dose-dependent manner by exogenous CCK octapeptide (CCK-8) at 16, 32, and 64 micrograms (14, 28, and 56 pmol).kg-1.h-1. Atropine inhibited protein output only partially, but it did not influence bicarbonate output. In five additional dogs, the effect of atropine on L-tryptophan-stimulated pancreatic secretion was studied. Interestingly, atropine failed to influence the CCK release and pancreatic secretion of volume and bicarbonate, except for protein secretion, which was significantly inhibited. It was shown previously that atropine inhibited significantly the pancreatic secretion of bicarbonate stimulated by secretin in physiological doses. Thus we conclude that the inhibition by atropine of the pancreatic exocrine secretion stimulated by sodium oleate is mediated by both suppression of CCK release and inhibition of action of secretin on the exocrine pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipopolysaccharide (LPS) from Brucella abortus is less toxic than that from Escherichia coli, suggesting the possible use of B. abortus or LPS from B. abortus as a carrier in vaccines

Brucella abortus may be useful as a component of vaccines. This is because it possesses several unique properties as a carrier that enable it to stimulate human B cells even in the relative absence of T cells. Human immunodeficiency virus type 1 proteins conjugated to B. abortus could induce neutralizing antibodies against human immunodeficiency virus type 1. Recently we showed that the characteristics of lipopolysaccharide (LPS) derived from B. abortus are similar to those of the whole bacterium in that the LPS acts as a T-independent type 1 carrier in mice. In this study we wanted to determine whether LPS derived from B. abortus is associated with the adverse effects seen with other bacterial endotoxins. LPS purified from B. abortus by butanol extraction was shown to have less than 2% (wt/wt) contamination by protein and less than 1% (wt/wt) contamination by nucleic acids and to contain 1% (wt/wt) ketodeoxyoctanic acid. Compared with LPS derived from Escherichia coli, B. abortus LPS was 10,000-fold less potent in eliciting fever in rabbits, 268-fold less potent in killing D-galactosamine-sensitized mice, and 1,400-fold and 400-fold less potent in inducing interleukin-1 beta and tumor necrosis factor alpha production, respectively. These results suggest that B. abortus LPS is much less likely than the LPS from E. coli to evoke endotoxic shock; therefore, it may be feasible to incorporate B. abortus as a component of vaccines.

Nosocomial infection and antibiotic utilization in geriatric patients: a pilot prospective surveillance program in skilled nursing facilities

Prospective surveillance of nosocomial infection was conducted at seven skilled proprietary nursing facilities in Orange County, Calif., USA. The average incidence of facility-acquired infection was 5.2 infections/1,000 patient days. The most common source of infection was urinary tract (47%), followed by respiratory tract (26%) and skin (14%). The four most common pathogens isolated were Proteus spp. (20%), Escherichia coli (17%), Staphylococcus aureus (13%) and Pseudomonas spp. (11%). Trimethoprim-sulfamethoxazole (20%) was the most frequently used antibiotic among all prescriptions, followed by ampicillin (16%) and ciprofloxacin (14%). Among all residents surveyed, 33% received at least one course of antibiotics during the study. Of special significance was the fact that 4 (22%) of the 18 strains of Pseudomonas were gentamicin resistant as were 12 of 80 (15%) of the strains of Enterobacteriaceae. Furthermore, 9 of 29 (31%) strains of Pseudomonas tested were found resistant to norfloxacin as were 15 of 129 (12%) strains of enterobacteriaceae. Susceptibility patterns of the isolated pathogens were similar to those of the acute care hospital. This study indicates that infection continues to be a major problem in the skilled nursing facility and that antibiotic-resistant pathogens will be a challenge for the future.

Inhibition of GFAP synthesis by antisense RNA in astrocytes

Glial fibrillary acidic protein (GFAP) accumulation is a prominent feature of astrocytic gliosis. The inhibition or delay in GFAP synthesis might delay scar formation resulting from an insult such as spinal cord injury or central nervous system (CNS) demyelination. The delay in the formation of a physical barrier might allow the neurons and oligodendrocytes to reestablish a functional environment. We delivered antisense GFAP RNA complexed with Lipofectin (LF), a cationic liposome, into cerebral astrocytes in culture and tested the feasibility of inhibiting GFAP synthesis. Our results demonstrate that LF facilitated antisense RNA uptake into astrocytes. Astrocytes took up 3H-antisense GFAP RNA alone and reached an equilibrium of 7-8.8 eta g per mg protein after 2.5 hr. When complexed with LF, astrocytes could increase the uptake to 14 eta g per mg protein and the time for reaching this quantity was shortened to 10 min. This uptake level was further enhanced if experiments were carried out in HEPES buffered saline (HBS). All uptake studies were dose- and time-dependent. Dibutyryl cyclic AMP (dBcAMP) is known to induce an increase of GFAP content in cultured astrocytes. We studied the effect of LF/antisense GFAP RNA on the GFAP content in dBcAMP (0.25 mM)-treated astrocytes. Cultures of astrocytes treated with dBcAMP contained almost twice as much GFAP as untreated cultures after 2 days. Similar cultures treated with LF/antisense RNA in HBS did not show an increase but a 30-40% decrease in GFAP content 2 days after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Absence of modulation of monokine production via endogenous cyclooxygenase or 5-lipoxygenase metabolites: MK-886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]-2,2- dimethylpropanoic acid), indomethacin, or arachidonate fail to alter immunoreactive interleukin-1 beta, or TNF-alpha production by human monocytes in vitro

Human peripheral blood monocytes exposed to MK-886 (3-[1-(4-chlorobenzyl)-3-t-butyl-thio-5-isopropylindol-2-yl]-2,2- dimethylpropanoic acid) at doses which abolish formation of 5-lipoxygenase metabolites showed unaltered interleukin-1 beta (IL-1 beta) or tumor necrosis factor-alpha (TNF-alpha) levels in response to phorbol ester, concanavalin A, serum-treated zymosan, or lipopolysaccharide. Indomethacin (10 microM), alone or in combination with MK-886, also failed to modulate monokine production in response to any stimulus. Exogenous arachidonate (3-30 microM) which augmented the formation of PGE2 and LTB4 in the absence of stimulation, also had no effect on monokine production. LPS-induced IL-1 and TNF production occurred despite stimulation of PGE2 synthesis. The results make a role for endogenous prostaglandins and leukotrienes in the regulation of monocyte IL-1 beta and TNF-alpha production unlikely. These data also indicate that MK-886, a novel inhibitor of 5-lipoxygenase product formation, is a potentially useful leukotriene inhibitor which does not affect monokine production.

Urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) as early markers of renal tubular dysfunction in sick neonates

Urinary beta 2-microglobulin, creatinine, N-acetyl-beta-D-glucosaminidase (NAG), sodium, potassium and plasma beta 2-microglobulin, and creatinine were measured in 34 healthy neonates (including 15 term, 12 prematures with a birth weight between 1.5 and 2.5 kg, 7 prematures with a birth weight less than 1.5 kg), 29 sick neonates (including 6 term, 10 prematures with a birth weight between 1.5 and 2.5 kg, 13 prematures with a birth weight less than 1.5 kg), and 13 term neonates born with meconium-stained amniotic fluid at 1, 3, and 5 days of age. Our data revealed that urinary beta 2-microglobulin, NAG, NAG index (NAG/creatinine), and the sodium concentration were significantly higher in sick preterm and term neonates than in healthy neonates (p less than 0.05). Urinary concentrations of beta 2-microglobulin and NAG were also higher in neonates born with meconium-stained amniotic fluid than in healthy neonates. We conclude that sick neonates have a higher incidence of acute tubular injury. The elevated levels of urinary beta 2-microglobulin and NAG in neonates born with meconium-stained amniotic fluid indicate the existence of tubular dysfunction, probably due to perinatal distress.

Calcium-dependent eicosanoid metabolism by concanavalin A-stimulated human monocytes in vitro. Synergism with phorbol ester indicates separate regulation of leukotriene B4 synthesis and release

Human monocytes obtained by counter-current centrifugal elutriation released arachidonic acid when challenged in vitro with Con A, as well as with other soluble (PMA or ionomycin) or particulate stimuli (serum-treated zymosan). Cyclo-oxygenase metabolites were the principal eicosanoids detected in the supernatants of Con A-stimulated, [3H]arachidonate-labeled monocytes, 5-Lipoxygenase (5-LO) products, such as leukotriene B4 (LTB4), were conspicuously absent. Release of arachidonate and its metabolites in response to Con A was dependent on the presence of extracellular Ca2+, but not Mg2+. In contrast to serum-treated zymosan challenge, which resulted in increased inositol trisphosphate and LTB4 release, Con A-induced inositol phospholipid hydrolysis in monocytes was limited to phosphatidylinositol or phosphatidylinositol monophosphate. Despite an inability to augment LTB4 release, Con A or PMA induced a loss of 5-lipoxygenase from a cytosolic compartment that was similar to that achieved with a calcium ionophore (ionomycin), a potent stimulus for LTB4 generation. When cell-associated LTB4 was evaluated, evidence for increased LTB4 production was obtained in response to either stimulus (PMA greater than Con A). In combination, however, PMA and Con A treatment resulted in monocyte LTB4 release comparable with that observed with the calcium ionophore or STZ. LTB4 release in response to all stimuli tested was inhibited by MK-886, a drug that binds to 5-lipoxygenase-activating protein. These results indicate the following: 1) Phospholipase A2 activation and attendant arachidonic acid release induced by agents that increase intracellular Ca2+ and/or generate diacylglycerol results in increased synthesis and release of PG and increased synthesis of leukotrienes, but not necessarily leukotriene release. 2) 5-LO translocation, which may occur independently of increased intracellular Ca2+, may be necessary for LTB4 generation but is insufficient for its release. 3) 5-Lipoxygenase-activating protein activity is necessary for 5-LO activation and LTB4 release in response to all stimuli investigated here. 4) Phorbol ester, an activator of protein kinase C, may synergize with agents such as Con A (which by themselves induce a minimal intracellular Ca2+ rise), so as to result in the release of LTB4. Thus, Con A may represent a class of surface receptor-aggregating agents that initiates inflammatory changes or immunomodulation associated with liberation of PG and might predispose to release of other inflammatory mediators, such as leukotrienes, in the presence of additional signals including protein kinase activation.

Enhanced host cell reactivation of damaged plasmid DNA in HeLa cells resistant to cis-diamminedichloroplatinum(II)

Human HeLa cells resistant to cisplatin were established by stepwise selection. The selected cells showed a 15- to 20-fold cisplatin resistance (CPR) at the dose level resulting in 50% inhibition. These cells were cross-resistant to mitomycin C, melphalan, and ethyl methanesulfonate but not to Adriamycin, colchicine, or vinblastine. The expression of cisplatin-damaged plasmid DNA carrying the bacterial chloramphenicol acetyltransferase (CAT) gene after its transfection into CPR cells was enhanced by approximately 3-fold. This did not correlate with the degree of CPR. However, the development of the CPR phenotype paralleled the enhanced CAT activity. The addition of aphidicolin (an inhibitor of DNA alpha-polymerase) to CPR cells effectively diminished the enhanced CAT activity and CPR. These studies have identified an enhanced host cell reactivation of the damaged plasmid in the acquisition of CPR, suggesting that DNA repair is a potential mechanism for the development of CPR phenotype in human cells.

Calcium-dependent eicosanoid metabolism by concanavalin A-stimulated human monocytes in vitro. Synergism with phorbol ester indicates separate regulation of leukotriene B4 synthesis and release

Human monocytes obtained by counter-current centrifugal elutriation released arachidonic acid when challenged in vitro with Con A, as well as with other soluble (PMA or ionomycin) or particulate stimuli (serum-treated zymosan). Cyclo-oxygenase metabolites were the principal eicosanoids detected in the supernatants of Con A-stimulated, [3H]arachidonate-labeled monocytes, 5-Lipoxygenase (5-LO) products, such as leukotriene B4 (LTB4), were conspicuously absent. Release of arachidonate and its metabolites in response to Con A was dependent on the presence of extracellular Ca2+, but not Mg2+. In contrast to serum-treated zymosan challenge, which resulted in increased inositol trisphosphate and LTB4 release, Con A-induced inositol phospholipid hydrolysis in monocytes was limited to phosphatidylinositol or phosphatidylinositol monophosphate. Despite an inability to augment LTB4 release, Con A or PMA induced a loss of 5-lipoxygenase from a cytosolic compartment that was similar to that achieved with a calcium ionophore (ionomycin), a potent stimulus for LTB4 generation. When cell-associated LTB4 was evaluated, evidence for increased LTB4 production was obtained in response to either stimulus (PMA greater than Con A). In combination, however, PMA and Con A treatment resulted in monocyte LTB4 release comparable with that observed with the calcium ionophore or STZ. LTB4 release in response to all stimuli tested was inhibited by MK-886, a drug that binds to 5-lipoxygenase-activating protein. These results indicate the following: 1) Phospholipase A2 activation and attendant arachidonic acid release induced by agents that increase intracellular Ca2+ and/or generate diacylglycerol results in increased synthesis and release of PG and increased synthesis of leukotrienes, but not necessarily leukotriene release. 2) 5-LO translocation, which may occur independently of increased intracellular Ca2+, may be necessary for LTB4 generation but is insufficient for its release. 3) 5-Lipoxygenase-activating protein activity is necessary for 5-LO activation and LTB4 release in response to all stimuli investigated here. 4) Phorbol ester, an activator of protein kinase C, may synergize with agents such as Con A (which by themselves induce a minimal intracellular Ca2+ rise), so as to result in the release of LTB4. Thus, Con A may represent a class of surface receptor-aggregating agents that initiates inflammatory changes or immunomodulation associated with liberation of PG and might predispose to release of other inflammatory mediators, such as leukotrienes, in the presence of additional signals including protein kinase activation.

Stimulatory effect of counterflow centrifugal elutriation in large-scale separation of peripheral blood monocytes can be reversed by storing the cells at 37 degrees C

Transfusion of peripheral blood monocytes may be of benefit as adjuvant treatment of leukopenic patients with serious infections. To study the feasibility of this approach, a large-scale monocyte separation procedure employing leukapheresis, density gradient centrifugation, and counterflow centrifugal elutriation was established. By processing 5 to 6 liters of normal donor blood, it was possible to obtain a mean of 1.1 x 10(9) (range: 0.5-1.7 x 10(9) cells) of mononuclear cells, of which 89% (range: 82-94%) were monocytes by Wright's stain morphology. When the elutriation was performed in XVIVO-10, a commercially available, serum-free medium developed for adoptive immunotherapy, spontaneous secretion of superoxide by the monocytes was significantly higher than for monocytes elutriated in Hanks' balanced salt solution without calcium and magnesium or non-elutriated peripheral blood mononuclear cells. This stimulated state of the monocytes was observed both immediately after elutriation and after overnight storage at 4 degrees C, and it was not affected by the type of storage vessel used. Overnight storage of the monocytes at 37 degrees C resulted in a reversal of the stimulated state of the cells. Monocytes elutriated in XVIVO-10 and kept overnight at 4 degrees C released high amounts of arachidonic acid. A subsequent decrease in this release was seen after additional storage at 37 degrees C for 18 hours. These observations demonstrate that separation and storage variables have important effects on the state of stimulation of monocytes. Further investigations of such variables may suggest improved procedures for preparation and storage of these cells, as well as possible ways to stimulate monocytes prior to transfusion.

Increase in glial fibrillary acidic protein following neural trauma

Immunohistochemical staining and quantitative evaluation of glial fibrillary acidic protein (GFAP) were carried out in a stab wound model of neural trauma in the rat. Increased GFAP staining was detected in reactive cortical astrocytes in the vicinity of the wound at 3, 7, and 30 d following injury. Western blots immunostained for GFAP also demonstrated an increase in GFAP in homogenates from the lesioned cortex, compared to the contralateral control side, on days 3, 7, and 30. Specific activity of GFAP expressed as a ratio of lesion/control values showed a fivefold increase from day 0 to day 7, with no further change on day 30. We conclude that neural trauma elicits a quantitative increase in GFAP in the rat cortex during the first week following injury. This increase correlates with both astrocyte hyperthrophy and proliferation. Thus, specific activity of GFAP is a reliable indicator of the onset and progression of astrogliosis in neural trauma.

Phenotypic reversion of cisplatin resistance in human cells accompanies reduced host cell reactivation of damaged plasmid

Revertant cell lines were established from cisplatin (CP) resistant HeLa cells. Expression of CP damaged plasmid DNA carrying bacterial chloramphenicol acetyltransferase (CAT) gene after transfection into cells was measured. Revertant cells showed reduced host cell reactivation of damaged plasmid, as compared to resistant cells. Addition of aphidicolin, an inhibitor for DNA polymerase alpha, to resistant cells effectively blocked enhanced plasmid reactivation and acquired resistance. The results are consistent with the notion that cellular ability in repair CP-damaged DNA is a mechanism for CP resistance.

The insulin-like growth factor binding protein BP-25 is expressed by human breast cancer cells

Specific binding proteins are thought to modulate the effects of IGF-I. Previous work has demonstrated that media conditioned by human breast cancer cells contains IGF-I binding activity. Radiolabelled IGF-I incubated with serum-free conditioned media from the breast cancer cell line MDA-MB 231 eluted with an apparent M.W. of 35-40 kDa when analyzed by gel filtration chromatography at pH 7.4. The M.W. of this binding activity corresponded to that of BP-25, a binding protein cloned from the hepatocellular carcinoma cell line HepG2. Two breast cancer cell lines, MDA-MB 231 and Hs578T, were found to express BP-25 RNA. Specific BP-25 radioimmunoassay detected BP-25 production in the conditioned media of these two cell lines. Immunoprecipitation confirmed that metabolically labelled MDA-MB 231 released 30 kDa BP-25 into its medium. This study demonstrates that some breast cancer cells express the IGF-I binding protein, BP-25.

Epidermal growth factor receptor in meningiomas is expressed predominantly on endothelial cells

The immunohistochemistry of the epidermal growth factor receptor (EGFR) was studied with monoclonal antibodies in 12 meningiomas of various histologic subtypes, nine benign and three malignant. Strong immunoreactivity of EGFR epitopes was found in the endothelia of the tumor vasculature in six cases. A much weaker reaction was detected within tumor cells in six cases, in one of which it was diffuse and five focal. No correlation was established between the presence of EGFR epitopes and the histologic type or biologic behavior of the meningiomas. The results suggest that the EGFR may participate in tumor angiogenesis, but its role in the growth of neoplastic meningioma cells remains elusive.

Radioautographic demonstration of receptors for epidermal growth factor in various cells of the oral cavity

Mouse iodinated epidermal growth factor (EGF) was localized by light and electron microscopic radioautography in basal cells of oral epithelium, papillary cells of the enamel organ, periodontal ligament fibroblasts, preodontoblast precursor cells, and preosteoblasts of the alveolar bone of 13-day-old Sprague-Dawley rats. The specificity of binding in these cells was suggested by an observed reduction of about 90% in the labeling when excess unlabeled EGF was injected along with the 125I-EGF. In contrast, fully differentiated cells, such as ameloblasts, odontoblasts, and osteoblasts, were only poorly labeled. Quantitative analysis of the light microscopic radioautographs revealed that the papillary cells had the highest level of labeling (5.5 grains per 100 micron 2 of cell area). The significance of the rather high labeling of the preosteoblasts of the alveolar bone and the fibroblasts of the periodontal ligament is unknown. However, the well-known effect of EGF in producing precocious eruption of teeth may be a consequence of an effect on these two cell types.

Insulin-like growth factor (IGF) binding protein complementary deoxyribonucleic acid from human HEP G2 hepatoma cells: predicted protein sequence suggests an IGF binding domain different from those of the IGF-I and IGF-II receptors

The primary structure of an insulin-like growth factor (IGF) binding protein produced by human HEP G2 hepatoma cells has been deduced from the cDNA sequence. The 234 amino acid protein has a predicted molecular mass of 25,274 and contains a single, distinctive cysteine-rich region. The N-terminal sequence of this protein is quite similar to the limited sequence data available for a rat IGF binding protein produced by BRL-3A cells and suggests a common ancestral origin. In contrast, the HEP G2 IGF binding protein sequence bears no similarity to the N-terminal 15 amino acids of a 53 kilodalton binding protein purified from human plasma. Comparison of full-length protein sequences for the IGF-I and IGF-II receptors with that of the HEP G2 IGF binding protein also fails to demonstrate any significant similarities among these three proteins, and suggests that each contains a unique binding domain for the IGF peptides.

Molecular differentiation of neurons from ependyma-derived cells in tissue cultures of regenerating teleost spinal cord

Cells cultured from the caudalmost area of regenerating teleost spinal cord differ both morphologically and in terms of molecular architecture from those of more rostral (more fully differentiated) areas of the cord. The caudalmost regenerating cord consists of an ependymal tube. Cells from this region have flattened or partially flattened cell somas and short spike projections in vitro; they do not exhibit the rounded cell somas nor the long, thin, branching neurites typical of differentiated neurons. A series of cultures taken from different areas along the length of regenerating spinal cord were examined for molecular differentiation by staining with a monoclonal antibody against non-phosphorylated neurofilament protein (SMI 32). None of the cells from the caudalmost culture of the regenerating spinal cord stained with antibody SMI 32. In cultures of more rostral regenerated cord, the cells with neuronal morphology do stain positively with the anti-neurofilament antibody. This result suggests that the cells in the cultures of caudalmost cord represent relatively undifferentiated ependymal cells, or ependyma-derived cells, which later differentiate into neurons and glia in the regenerating spinal cord.

Turnover of glial filaments in mouse spinal cord

Twenty-day-old mice received a single tail vein injection of [guanido-14C]arginine. The cytoskeleton was extracted from the spinal cords at varying lengths of time thereafter. Glial fibrillary acidic protein (GFAP) formed a distinct, broad band that was widely separated from other protein bands in one-dimensional polyacrylamide gels. The purity of the GFAP band was verified by Western blot analysis of one- and two-dimensional electrophoretic patterns. In addition, enzyme-linked immunosorbent assay and quantitative Western blot analysis indicated that 95% of the total spinal cord GFAP was extracted in the cytoskeletal preparation. The specific activity of GFAP was obtained by eluting the protein from the cytoskeletal GFAP band in preparative one-dimensional gels. Specific activity reached a peak 2 h after injection with [14C]arginine. Forty percent of the incorporated radioactivity was still present in cytoskeletal GFAP at 9 weeks, indicating that a significant proportion of glial filaments turns over relatively slowly in vivo.

Geographic variation in infant loss of maternal measles antibody and in prevalence of rubella antibody

Maternal and cord measles and rubella antibodies were compared in 15 populations from Brazil, Ecuador, Chile, India, Jordan, Nigeria, South Africa, Taiwan, and the United States. Review of the literature concerning these countries showed that a higher proportion of children 6-12 months of age responded immunologically to measles vaccine in areas with low per capita product than in wealthier populations. The authors show that this difference reflects differences in maternal antibody titer and differences in efficiency of transport of measles immunity across the placenta. No variation in the half-life of passive measles immunity in the infant was found in comparing three geographic areas. When these biologic factors are fully evaluated, it should be possible to predict the response to be expected from vaccination at any particular age without directly testing the vaccine in children below and above generally recommended ages for vaccination. With regard to rubella, high antibody prevalence rates were found in most of the developing countries, as well as in the United States, and these countries are therefore unlikely to encounter widespread problems with congenital rubella. However, Taiwan, and all of four areas of Brazil have prevalence rates which are no higher than those which pertained in the United States prior to establishment of the rubella immunization program. The authors believe that protection of the infants in these countries is a matter of high priority, but that, if approached hastily, it could exacerbate the problem.

Localization of fibronectin in gingival connective tissue of the beagle dog. Ultrastructural detection with ferritin and peroxidase-conjugated antibodies

Ferritin and peroxidase-conjugated antibodies were used in an indirect antibody method to localize fibronectin in gingival connective tissues. Fibronectin was found in the basal lamina beneath the epithelium and endothelium. Collagen fibrils associated with the basement membranes were also heavily coated by fibronectin. Amorphous patches of fibronectin were found adjacent to the plasma membrane of epithelial cells as well as free in the interepithelial spaces. Fibronectin was present throughout the connective tissue in close association with individual collagen fibrils, apparently serving as an interfibrillar cementing substance. Patches of fibronectin were located at the cell surface of fibroblasts, plasma cells, lymphocytes, endothelial cells, smooth muscle cells, and neutrophils. These amorphous patches were observed to connect adjacent cells across narrow spaces and to connect cells to collagen fibrils. The heavy labeling for fibronectin visualized by fluorescent microscopy around gingival blood vessels (Cho et al., 1985) can be accounted for by a heavy coating of fibronectin on the collagen fibrils and basal laminas associated with endothelial cells, as well as by the presence of abundant deposits of fibronectin along the cell membranes of endothelial cells and in the intercellular spaces of the vessel wall.

Astrocyte culture on nitrocellulose membranes and plastic: detection of cytoskeletal proteins and mRNAs by immunocytochemistry and in situ hybridization

Neonatal rat brain astrocyte secondary cultures were established on nitrocellulose membrane filters (13-mm diameter Millipore disk) and on plastic coverslips in serum-supplemented medium. On these substrata, cultured astrocytes changed their shape from flat and polygonal to stellate in the absence of hormones or growth factor supplements. Cultures became confluent after 4 days, and astrocytes on nitrocellulose filters continued to differentiate morphologically and biochemically, as evidenced by extensive cytoplasmic process formation and glial fibrillary acid protein (GFAP) accumulation. Cultures were immunostained for GFAP and vimentin. mRNAs to GFAP, vimentin, alpha and beta tubulin, and actin also were detected by in situ hybridization with biotinylated cDNA probes. The astrocyte culture method on nitrocellulose provides a simple, versatile means of comparing undifferentiated, morphologically mature, reactive, and neoplastic astrocytes in vitro.

Localization of fibronectin in gingival connective tissue of the beagle dog. Immunofluorescent light microscopic findings

Affinity purified antibodies to plasma fibronectin were used to localize fibronectin in the connective tissues of inflamed and noninflamed beagle gingiva. In noninfiltrated gingival connective tissue, fibronectin was demonstrated in the basement membrane beneath gingival epithelium and around blood vessels as a uniform and intensely stained band about 3 to 10 micron thick. Fibronectin was also distributed throughout the connective tissue in association with collagen fibrils as a more diffuse, less intensely stained pattern. The inflamed gingiva included in this study was characterized by proliferation of epithelial pegs, heavy infiltration of plasma cells and loss of collagen within the subepithelial connective tissue. In these sites, fibronectin was present as an intensely stained band around blood vessels and at the crest of connective tissue papillae nearest the sulcular space. The fibronectin in the basement membrane beneath the epithelium appeared diminished and less uniformly distributed. A delicate network of fibronectin was present around plasma cells and the remaining collagen fibers.

Effect of prostaglandin E2 on the electrical activity of cat isolated stomach muscle

Prostaglandins (PGs) are believed to be present in the gastrointestinal tract and to increase the tone of longitudinal muscle layer. However the influence of PGs on the gastric slow wave (SW) is not clarified yet. We therefore investigated the effect of prostaglandin E2 (PGE2) on the electrical and the mechanical activities of feline isolated stomach muscle strips (7 X 1.5 cm), using five capillary electrodes (Ag-AgCl) and an isometric force transducer connected to the antral edge. One hundred and ninety-six strips, obtained from the corpus and antrum of 196 anaesthetized cats, were studied in a muscle chamber filled with Krebs solution (pH 7.4, temperature 36 degrees C) bubbled with 5% CO2 in O2. Exogenous PGE2 concentration-dependently increased the gastric SW frequency without affecting the spike and mechanical activities. Indomethacin decreased the SW frequency. These responses to PGE2 or indomethacin were not blocked by phentolamine, propranolol, hexamethonium, atropine or tetrodotoxin. It is therefore suggested that PGE2 facilitates the development of the gastric SW by an action on the muscle that does not involve cholinergic or adrenergic mechanism.

Hormones and growth factors induce the synthesis of glial fibrillary acidic protein in rat brain astrocytes

Glial fibrillary acidic protein (GFAP) is the major constituent of glial filaments and is restricted within the CNS to astrocytes. As with other classes of intermediate filament proteins, the regulation of GFAP expression is poorly understood. Utilizing highly purified cultures of astrocytes and a chemically defined (CD) medium, we have demonstrated that the expression of GFAP is subject to regulation by hormones and growth factors. The concentration of GFAP/mg protein was induced 2-4-fold in the presence of hydrocortisone, putrescine, prostaglandin F-2 alpha (PGF2 alpha), and pituitary fibroblast growth factor (FGF). Augmentation of the levels of GFAP continued for up to 3 weeks after conversion to CD medium and paralleled the morphological maturation of astrocytes. The accumulation of GFAP resulted from an increase in its specific rate of synthesis. Conversion of astrocytes from serum-supplemented (SS) to CD medium did not alter its rate of degradation. GFAP appeared quite stable under both sets of conditions, exhibiting a half-life of approximately 7.5 days. The data demonstrate that GFAP expression in astrocytes is subject to hormonal regulation, which may have implications for gliosis.

The optimal age for vaccination against measles in an Asiatic city, Taipei, Taiwan: reduction of vaccine induced titre by residual transplacental antibody

Children vaccinated when aged between six and thirteen months against measles in Taipei showed a high frequency of response, similar to that reported from Nairobi, Kenya and contrasting with analogous data for the USA. The age for optimal protection against measles mortality by a single dose of vaccine in this group of children is nine months. Maternal antibody exerted a negative effect on measles antibody titre in vaccinees beyond the age at which it blocked the response so that the infants of mothers with the higher titres themselves had lower titres. A separate effect of immunological immaturity on titre of the response could not be demonstrated in children over six months of age.

Monoclonal antibodies reactive with epitopes restricted to glial fibrillary acidic proteins of several species

The highly reproducible histochemical localization of glial fibrillary acidic protein (GFAP)+ qualifies it as an important marker of astrocytes in both research and clinical applications. The primary objective of this study was to produce monoclonal antibodies having the advantage of invariant specificity, affinity, and titer to GFAP-specific epitopes of wide species distribution. We report here the characterization of four monoclonal antibodies that recognize the same or spatially close epitopes specific to GFAP. The epitope(s) detected has been phylogenetically conserved; human, bovine, ovine, canine, porcine, rabbit, guinea pig, rat, murine, and chicken brain homogenates all specifically absorb monoclonal antibody activity. Of importance to the routine application of these new anti-GFAP monoclonal antibodies is the demonstration here of the stability of the antigen-antibody interaction in normal, reactive, and neoplastic astrocytes of both rat and human origin following various methods of fixation.

Catabolism of 2,4,5-trimethyoxybenzoic acid and 3-methoxycrotonic acid

4-Methoxygentisic acid was an intermediate formed when Arthrobacter degraded, 2,4,5-trimethoxybenzoic acid. Isolates of Pseudomonas and Arthrobacter from soil grew at the expense of 3-methoxycrotonic acid. Evidence is presented that enzymatic hydration, with elimination of methanol, accounted for replacement of the methoxyl group of 3-methoxycrotonic acid and also of one methoxyl group of 2,4,5-trimethoxybenzoic acid.

Clearance of myelin basic protein from blood of normal and EAE rabbits

The rate of clearance of porcine myelin basic protein (MBP) from plasma of rabbits was determined following intravenous injection of 20 mg MBP. The MBP level in the plasma was measured by a 2-site immunoradiometric assay with specific antibody to guinea pig MBP produced in rabbits. Plasma MBP-antibody levels were determined by competitive binding radioimmune assay (RIA). Unsensitized and those sensitized with complete Freund's adjuvant (CFA), with porcine MBP in CFA, and with whole porcine spinal cord in CFA were studied. Unsensitized and CFA sensitized rabbits exhibited maximum MBP levels in the plasma within two minutes after injection with rapid decrease to undetectable levels in one hour. Thirty-nine of the unsensitized (control) rabbits exhibited normal, rapid clearance and no subsequent physical signs of EAE while one of the control rabbits exhibited a slightly retarded clearance rate. Histologic examination of autopsy tissues from the control group revealed that five rabbits showed lesions which could be attributed to Encephalitozoan cuniculi or Toxoplasma and one rabbit autopsied 65 days after clearance had minimal EAE lesions. Rabbits sensitized with MBP exhibited a retarded rate of clearance at the acute stage of EAE and following recovery. Rabbits sensitized with whole spinal cord in CFA also exhibited a retarded rate of MBP clearance. Anti (MBP) antibodies were detected in the plasma of all rabbits which exhibited a retarded rate of MBP clearance. Significant rates of retardation were not detected until approximately three weeks after sensitization with CFA-MBP or CFA-spinal cord. While MBP antibody levels in most animals were not detected by the immunodiffusion technique, antibodies were demonstrated by RIA. The 20 mg MBP given intravenously is probably in great antigen excess and conducive to the formation of soluble MBP-anti (MBP) complexes in the blood.

Comparison of two dioxygenases from Pseudomonas putida

Catechol 2,3-dioxygenase and homoprotocatechuate 2,3-dioxygenase were purified from the same strain of Pseudomonas putida. Molecular weights and subunit sizes were similar, but amino acid compositions showed some marked differences.