AIM/CD5L ameliorates autoimmune arthritis by promoting removal of inflammatory DAMPs at the lesions

The hallmark of autoimmune arthritis is the preceding autoantibody production and the following synovial inflammation with hyperplasia and tissue destruction of the joints. The joint inflammation is mediated not only by effector lymphocytes and auto-antibodies but also chronic activation of innate immunity, particularly promoted by the danger-associated molecular patterns (DAMPs). Here we show that apoptosis inhibitor of macrophage (AIM, also called CD5L) protein regulates arthritis by promoting removal of lesional DAMPs both physiologically and therapeutically. When the autoimmune arthritis was promoted by injecting a cocktail of anti-collagen antibodies without type-II collagen immunization, AIM-deficient (AIM-/-) mice exhibited more exacerbated and sustained swelling at multiple joints with greater synovial hyperplasia and bone erosion than wild-type mice. Administration of recombinant AIM (rAIM) reduced S100A8/9, a major DAMP known to be involved in arthritis progression, and decreased various inflammatory cytokines at the lesions in antibody-injected AIM-/- mice, leading to marked prevention of arthritis symptoms. In human rheumatoid arthritis (RA) patients, AIM was more activated via dissociating from IgM-pentamer in response to DAMPs-mediated inflammation both in serum and synovial fluid than in healthy individuals or non-autoimmune osteoarthritis patients, suggesting a disease-regulatory potency of AIM also in human RA patients. Thus, our study implied a therapeutic availability of rAIM to prevent arthritis symptoms targeting DAMPs.

AIM/CD5L attenuates DAMPs in the injured brain and thereby ameliorates ischemic stroke

The sterile inflammation caused by damage-associated molecular patterns (DAMPs) worsens the prognosis following primary injury such as ischemic stroke. However, there are no effective treatments to regulate DAMPs. Here, we report that AIM (or CD5L) protein reduces sterile inflammation by attenuating DAMPs and that AIM administration ameliorates the deleterious effects of ischemic stroke. AIM binds to DAMPs via charge-based interactions and disulfide bond formation. This AIM association promotes the phagocytic removal of DAMPs and neutralizes DAMPs by impeding their binding to inflammatory receptors. In experimental stroke, AIM-deficient mice exhibit severe neurological damage and higher mortality with greater levels of DAMPs and associated inflammation in the brain than wild-type mice, in which brain AIM levels increase following stroke onset. Recombinant AIM administration reduces sterile inflammation in the infarcted region, leading to a profound reduction of animal mortality. Our findings provide a basis for the therapies targeting DAMPs to improve ischemic stroke.

Optical imaging of the propagation patterns of neural responses in the rat sensory cortex: comparison under two different anesthetic conditions

Although many studies have reported the influence of anesthetics on the shape of somatic evoked potential, none has evaluated the influence on the spatio-temporal pattern of neural activity in detail. It is practically impossible to analyze neural activities spatially, using conventional electrophysiological methods. Applying our multiple-site optical recording technique for measuring membrane potential from multiple-sites with a high time resolution, we compared the spatio-temporal pattern of the evoked activity under two different anesthetic conditions induced by urethane or α-chloralose. The somatic cortical response was evoked by electrical stimulation of the hindlimb, and the optical signals were recorded from the rat sensorimotor cortex stained with a voltage-sensitive dye (RH414). The evoked activity emerged in a restricted area and propagated in a concentric manner. The spatio-temporal pattern of the evoked activity was analyzed using isochrone maps. There were significant differences in the latency and propagation velocity of the evoked activity, as well as the full width at half maximum of optical signal between the two anesthetic conditions. Differences in the amplitude and the slope of the rising phase were not significant.

Simultaneous determination of delta(15)N and delta(18)O of N2O and delta(13)C of CH4 in nanomolar quantities from a single water sample

We have developed a rapid, sensitive, and automated analytical system to simultaneously determine the concentrations and stable isotopic compositions (delta(15)N, delta(18)O, and delta(13)C) of nanomolar quantities of nitrous oxide (N(2)O) and methane (CH(4)) in water, by combining continuous-flow isotope-ratio mass spectrometry and a helium-sparging system to extract and purify the dissolved gases. Our system, which is composed of cold traps and a capillary gas chromatograph that use ultra-pure helium as the carrier gas, achieves complete extraction of N(2)O and CH(4) in a water sample and separation among N(2)O, CH(4), and the other component gases. The flow path following exit from the gas chromatograph was periodically changed to pass the gases through the combustion furnace to convert CH(4) and the other hydrocarbons into CO(2), or to bypass the combustion furnace for the direct introduction of eluted N(2)O into the mass spectrometer, for determining the stable isotopic compositions through monitoring the ions of m/z 44, 45, and 46 of CO(2) (+) and N(2)O(+). The analytical system can be operated automatically with sequential software programmed on a personal computer. Analytical precisions better than 0.2 per thousand and 0.3 per thousand and better than 1.4 per thousand and 2.6 per thousand were obtained for the delta(15)N and delta(18)O of N(2)O, respectively, when more than 6.7 nmol and 0.2 nmol of N(2)O, respectively, were injected. Simultaneously, analytical precisions better than 0.07 per thousand and 2.1 per thousand were obtained for the delta(13)C of CH(4) when more than 5.5 nmol and 0.02 nmol of CH(4), respectively, were injected. In this manner, we can simultaneously determine stable isotopic compositions of a 120 mL water sample with concentrations as low as 1.7 nmol/kg for N(2)O and 0.2 nmol/kg for CH(4).

Molecular cloning and heterologous expression of an alpha-adrenergic-like octopamine receptor from the silkworm Bombyx mori

A cDNA encoding an octopamine (OA) receptor (BmOAR1) was isolated from the nerve tissue of silkworm (Bombyx mori) larvae. Comparison of amino acid sequences showed that BmOAR1 is highly identical to OA receptors isolated from Periplaneta americana (Pa oa(1)), Apis mellifera (AmOA1), and Drosophila melanogaster (OAMB or DmOA1A). BmOAR1 was stably expressed in HEK-293 cells. OA above 1 microM led to an increase in intracellular cyclic AMP concentration ([cAMP](i)). The synthetic OA-receptor agonist demethylchlordimeform also elevated [cAMP](i) to the same maximal level (approximately 5-fold over the basal level) as that induced by OA. However, other biogenic amines, tyramine and dopamine, and chlordimeform were without effects. The [cAMP](i) level raised by OA was lowered by antagonists; the rank order of antagonist activity was chlorpromazine > mianserin = yohimbine. Cyproheptadine and metoclopramide had little effect. OA above 100 nM induced a transient or sustained increase in intracellular Ca(2+) concentration ([Ca(2+)](i)), depending on the concentration of OA. Sequence homology and functional analysis data indicate that BmOAR1 is an alpha-adrenergic-like OA receptor of B. mori.

Sorbicillinol, a key intermediate of bisorbicillinoid biosynthesis in Trichoderma sp. USF-2690

In the course of our screening program for free radical scavengers from Trichoderma sp. USF-2690, we found an unidentified metabolite (1) that appeared by the method used for HPLC analysis. Metabolite 1 gradually decreased with the production of bisorbicillinoids and was easily missed during the general isolation procedure. The LC-ESI-MS (negative) analysis for 1 gave m/z 247 as the (M-1)- ion peak. The hydrolysis of synthetic 6-O-acetylsorbicillinol (+/- -2) by 0.05 M KOH and acetylation of product 1 in an aqueous solution indicated that the structure of 1 was (6S)-4-(2,4-hexadienoyl)-3,6-dihydroxy-2,6-dimethyl-2,4-cyclohexadien-1-one, designated sorbicillinol, a quinol that has been postulated to be important in bisorbicillinoid biosynthesis.

Semiquantitative analysis of the expression of GABA-A receptor subunits in the developing embryonic chick brain stem

The expression levels of seven types of gamma-aminobutyric acid-A (GABA-A) receptor subunits (alpha1, beta2, beta3, beta4, gamma1, gamma2, and gamma4) were quantified in the embryonic chick brain stem at 2 to 20 d of incubation (E2 to E20) and just after hatching. The expression level of mRNA was measured by using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). When property regions were amplified, two products were observed for each of the beta2, beta4, and gamma2 subunits because of alternative splicing. These were named beta2S and beta2L, beta4S and beta4L, and gamma2S and gamma2L for shorter and longer fragments, respectively. Transcripts of alpha1, beta2L, beta2S, beta3, beta4L, beta4S, gamma1, and gamma2S subunits were first detected from E2 to E5 brain stems. The expression level of each subunit increased gradually with development and reached a plateau at E9 to E12. In contrast, a delay occurred in the appearance of both the gamma4 and gamma2L subunits, which were not detected until E8 to E10. The absence of gamma4 and/or gamma2L subunits may explain differences in the pharmacological characteristics of GABA-A receptors at the early stages of development.

Ingestion of Gelatin Has Differential Effect on Bone Mineral Density and Body Weight in Protein Undernutrition

Malnutrition, particularly protein undernutrition, contributes to the occurrence of osteoporotic fracture by lowering bone mass. In this study, the effects of dietary protein on bone mineral density and body weight in protein undernutrition were compared between gelatin and milk casein. When mice were fed for 10 wk with a low protein diet containing 10(%) casein or 6% casein +4% gelatin, there was no significant difference in the final body weight between the 6% casein+4% gelatin group and the 10% casein group. In contrast, bone mineral content and bone mineral density of the femur were significantly higher in the 6% casein+4% gelatin group than in the 10% casein group. Bone mineral content and bone mineral density did not differ significantly in 14% protein groups between 14% casein and 6% casein +80% gelatin. These results suggest that gelatin has differential effects on bone mineral density and body weight in protein undernutrition.

1,1-Diphenyl-2-picrylhydrazyl radical-scavenging compounds from soybean miso and antiproliferative activity of isoflavones from soybean miso toward the cancer cell lines

Guided by their DPPH radical-scavenging activity, nine compounds were isolated from soybean miso. Of these, 8-hydroxydaidzein, 8-hydroxygenistein and syringic acid had as high DPPH radical-scavenging activity as that of alpha-tocopherol. The antiproliferative activity of four of the isolated isoflavones toward three cancer cell lines was examined. 8-Hydroxygenistein showed the highest activity (IC50=5.2 microM) toward human promyelocytic leukemia cells (HL-60).

Novel fungal metabolites, demethylsorbicillin and oxosorbicillinol, isolated from Trichoderma sp. USF-2690

The novel compounds, demethylsorbicillin (1) and oxosorbicillinol (2), were isolated from a fermentation broth of Trichoderma sp. USF-2690. The structures of these compounds, which were determined from spectroscopic evidence, suggest the possibility that methylation at C-6 and oxidation at C-1 and C-6 of sorbicillin were controlled in the early polyketide stage before the formation of oxidized sorbicillin dimers. In a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay, 2 gave an ED50 value of 87.7 microM.

Studies on the 1,1-diphenyl-2-picrylhydrazyl radical scavenging mechanism for a 2-pyrone compound

The radical scavenging mechanisms for the 2-pyrone compound, 4-hydroxy-3,6-dimethyl-2H-pyrane-2-one (1), and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (4) in several solvent systems were evaluated by the quantitative change in compounds detected at 270 nm and subsequent HPLC analyses. The HPLC profile for each condition suggested that the reaction proceeded by a different mechanism in each solvent system. In organic solvents (CHCl3, iso-propanol, and EtOH), 1-[4-(3,4-dihydro-3,6-dimethyl-2,4-dioxo-2H-pyran-3-yl) phenyl]-1-phenyl-2-picrylhydrazine (2) was produced as an adduct of the DPPH radical and 1. On the other hand, the reaction in a buffer solution (an acetate buffer at pH 5.5) gave several degradation products with 1[4-(2,3-dihydro-2,5-dimethyl-3-oxo-fur-2-yl) phenyl]-1-phenyl-2-picrylhydrazine (5), this being structurally elucidated by spectroscopic analyses. The decrease of the DPPH radical in each reaction system suggests that compound 1 could scavenge about 1.5-1.8 equivalents of the radical in organic solvents and about 3.5-3.9 in the buffer solution.

[Effect of stellate ganglion block on human retinal blood flow]

PURPOSE

The effect of stellate ganglion block (SGB) on human retinal blood flow was evaluated.

METHODS

We measured the diameter of the retinal artery and vein, and retinal venous flow rate by laser speckle retinal blood flow meter simultaneously in 11 eyes of 11 normal volunteers.

RESULTS

The reliable data from 9 eyes of 9 person were used for analysis. SGB did not change the blood pressure, heart rate, retinal arterial diameter, or venous diameter. However SGB increased retinal blood velocity significantly from 9.9 +/- 1.6 (mean +/- standard deviation) mm/s to 11.1 +/- 1.5 mm/s (p < 0.01). Intraocular pressure decreased from 12.3 +/- 2.1 (mean +/- standard deviation)mmHg to 9.4 +/- 2.2 mmHg after SGB (p < 0.01). There was no relationship between the change of ocular perfusion pressure and that of retinal venous blood velocity.

CONCLUSION

SGB increased the retinal venous blood velocity without changing the retinal vessel diameter.

Spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin during the development of chronic contact dermatitis

In order to elucidate how chronic inflammation affects the organization of the extracellular matrix in the skin, a prolonged allergic contact dermatitis was induced in a mouse by repeated application to the ear of 2,4-dinitrofluorobenzene every 3 d for 66 d. Subsequently, the spatiotemporal changes of fibronectin, tenascin-C, fibulin-1, and fibulin-2 in the skin were examined. In the acute phase of inflammation (day 3-day 12), the amount of fibronectin and tenascin-C increased markedly and were degraded, whereas the amount of fibulin-2 changed slightly. Abundant deposition of tenascin-C was observed in the connective tissue. Fibulin-1 and fibulin-2 distributed as fine fibrils. In contrast, the amounts of fibronectin and tenascin-C decreased and their degradation was suppressed in the chronic phase (day 15-day 66), but the amount of fibulin-2 increased. Tenascin-C was observed mainly at and underneath the epidermal basement membrane. In the subepidermal region, many fibulin-2-positive microfibrils were distributed. The amount and distribution of fibulin-1 did not change markedly in either phase. MMP-like enzymes of 62 kDa, probably activated MMP-2, were upregulated in the chronic phase, whereas components of 92, 85, or 67 kDa were highly induced in the acute phase. These results suggest that chronic inflammation in allergic contact dermatitis is associated with temporal changes in the expression, deposition, and degradation of inducible extracellular matrix components.

Phosphate depletion enhances tissue-nonspecific alkaline phosphatase gene expression in a cultured mouse marrow stromal cell line ST2

Alkaline phosphatases (ALP) are highly ubiquitous enzymes present in the majority of animals from bacteria to higher vertebrate. Although their wide distribution in nature has suggested that these enzymes should perform important biological functions, their detailed roles or natural substrates remain unknown. In Escherichia coli, the extracellular phosphate (Pi) limitation induces the ALP gene, indicating the role of extracellular Pi in ALP gene regulation. However, little is known about the similar mechanisms in mammalian cells. This study was designed to examine the effect of low Pi medium on the ALP activity and its expression in the mouse stromal cell line ST2. The enzymatic property was classified into tissue-nonspecific ALP (TNSALP). After treatment by Pi starvation for 3 days, there was a 2-fold increase in the specific activity of TNSALP. RT-PCR analysis revealed that the mRNA of the TNSALP gene was highly stimulated. These results indicated that the effect of Pi depletion on ALP activity was regulated at the TNSALP transcriptional level, suggesting that the possible role of the Pi sensing system for biological functions of ALP might have been conserved in evolution. Our findings also made it possible to discuss the physiological roles of ALP in vivo.

Molecular cloning and characterization of two cDNAs for Glycyrrhiza glabra squalene synthase

Two cDNAs (GgSQS1 and GgSQS2) encoding squalene synthase have been isolated from licorice, Glycyrrhiza glabra L., and characterized. The deduced amino acid sequence of GgSQS1 was 88%, 81%, 78%, 45-44%, and 45-41% identical to those of GgSQS2, Nicotiana, Arabidopsis, mammal and yeast squalene synthases, respectively. Squalene synthase activity was found in the cell-free extracts of Escherichia coli transformed with the recombinant plasmids for GgSQS1 and GgSQS2, respectively. Genomic Southern blot hybridization indicated that there are three squalene synthase genes in the licorice genome. Northern blot analysis showed that GgSQS2 mRNA is mainly expressed during the exponential growth phase of the cultured licorice cells.

Skin blood flow responses during sleep by laser Doppler flowmetry

Skin surface blood flow at the fingertips was measured in a 21-year-old woman during sleep using laser Doppler flowmetry. Skin blood flow responses (SBFR) are transient reductions in skin blood flow of about 25s in duration. In our subject, SBFR showed a delay time of 8-9s from the onset of skin potential responses (SPR) and appeared more consistently than SPR. The frequency of SBFR decreased during non-rapid eye movement sleep, especially when the sleep stage became deep. These findings indicate the validity of SBFR as a discrete index of autonomic function during sleep.

Optical imaging of the spatiotemporal patterning of neural responses in the embryonic chick superior cervical ganglion

Multiple-site optical recording of transmembrane potential changes with a voltage-sensitive dye was used to reveal the functional expression and developmental changes of the postsynaptic potentials in the early embryonic chick superior cervical ganglion. The ganglia were isolated from five- to 12-day-old chick embryos with preganglionic nerve fibres (vertebral and/or cervical carotic nerves) attached. The preparations were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). Voltage-related optical (absorbance) changes were recorded simultaneously from 127 contiguous loci in the preparation, using a 12 x 12-element photodiode array. Optical changes having two components were evoked by preganglionic nerve stimulation. One component was the fast spike-like signal and another the delayed slow signal. The amplitude of the slow signal was decreased by repetitive stimulation, reduced by low external calcium ion concentrations and eliminated in the presence of manganese or cadmium ions. The slow signals were also eliminated in the presence of D-tubocurarine. Accordingly, we concluded that the slow signal corresponds to cholinergic excitatory postsynaptic potentials. In the five- and six-day-old superior cervical ganglia, only the fast optical signals (referred to as the action potentials) were recorded. Slow optical signals (referred to as the excitatory postsynaptic potentials) were detected from preparations older than seven days. The amplitude of the slow optical signal gradually increased, together with an expansion of the response area, as the developmental stage proceeded from seven to 10 days. To compare the distribution patterns of the neural responses evoked by stimuli applied to the cervical carotic and vertebral nerves, we have mapped and imaged the spatial patterning of the synaptic responses. In the maps, the positions of the peak size regions of the slow signals were assessed, and we found that there were differences in the location of these areas for the cervical carotic vs vertebral nerves. From these experimental results, we conclude that synaptic function within the chick superior cervical ganglion is initiated at the seven-day-old embryonic stage, and reaches a maximum level at 10 days. Synaptic transmission at these stages is mediated solely by nicotinic acetylcholine receptors. The spatial mapping of the synaptic responses reveals that the neural populations related synaptically to the cervical carotic and vertebral nerves are located separately within the ganglion, even at an early developmental stage.

A regional gradient of cardiac intrinsic rhythmicity depicted in embryonic cultured multiple hearts

We used optical methods to examine the spatial gradient of intrinsic rhythmicity in early-stage multiple-heart chick embryos. The latter were induced experimentally in whole-embryo culture. The embryos were cut microsurgically through the tissue of the anterior intestinal portal at the 5- to early 7-somite developmental stage. Spontaneous electrical activity in 4 to 6 segmented hearts, during the 7- to 10-somite stages of development, were monitored simultaneously by means of multiple-site optical recordings of membrane potential activity, using a voltage-sensitive merocyanine-rhodanine dye (NK2761). Each segment of the heart exhibited its own inherent rhythmicity. In quadruple hearts, the order of the rhythmicity was often left-caudal segment>right-caudal segment>left-cephalic segment>right-cephalic segment; the heart rate in the left-caudal segment was often faster than that in the other segments. An atypical pattern of "bursting" rhythm was observed in the cephalic segments suggesting that, in these segments, the development of rhythmicity is relatively poor. These findings strongly emphasize the concept that, in the early phases of cardiogenesis, the formation of a regional gradient of pacemaker activity (i.e. a spatial gradient of intrinsic rhythmicity) results in the functional self-organization of the pacemaking area.

GABA-Induced intrinsic light-scattering changes associated with voltage-sensitive dye signals in embryonic brain stem slices: coupling of depolarization and cell shrinkage

We have found new evidence for gamma-aminobutyric acid (GABA)-induced intrinsic optical changes associated with a voltage-sensitive dye signal in the early embryonic chick brain stem slice. The slices were prepared from 8-day-old embryos, and they were stained with a voltage-sensitive dye (NK2761). Pressure ejection of GABA to one site within the preparation elicited optical changes. With 580-nm incident light, two components were identified in the GABA-induced optical change. The first component was wavelength dependent, whereas the second, slower change was independent of wavelength. Comparison with the known action spectrum of the dye indicates that the first component reflects a depolarization of the membrane and that the second, slow component is a light-scattering change resulting from cell shrinkage coupled with the depolarization. Similar optical changes also were induced by glycine, although the amplitude of both the first and second signals was much smaller than for GABA. The optical changes induced by GABA persisted in the presence of picrotoxin and 2-hydroxysaclofen, suggesting that these optical responses include a novel GABA response, which has been termed GABAD in our previous reports.

Optical mapping of neural responses in the embryonic rat brainstem with reference to the early functional organization of vagal nuclei

We examined the functional organization of the vagal nuclei of the rat embryo during morphogenesis, using multiple-site optical recording with a voltage-sensitive dye. Slice preparations with vagus nerve fibers were dissected from 13- to 16-d-old embryonic (E13-E16) rat brainstems, and they were stained with the dye. Electrical activity in response to vagal stimulation was recorded optically from many sites. In the E13-E14 preparations, two types of spike-like optical signals were recorded: one was a narrow signal (type I), and the other was a broader signal (type II). Comparison with the morphology revealed by DiI labeling suggests that the type I signal response area corresponds to the nucleus of the tractus solitarius, and the type II signal response area corresponds to the dorsal motor nucleus of the vagus nerve. In the E15-E16 preparations, type I signals were followed by a slow signal related to glutamate-mediated excitatory postsynaptic potentials, suggesting that synaptic function is organized in the nucleus of the tractus solitarius by the 15-d-old embryonic stage. In the E14 preparation, a small, slow signal was evoked only in Mg2+-free solution, implying that postsynaptic function related to NMDA receptors emerges, in latent form, at the 14-d-old embryonic stage. In the E15 and E16 preparations, although the nucleus ambiguus is identified morphologically, no neural response-related optical signal was observed there, indicating that the embryonic organization of morphology and physiological function is not necessarily temporally coincident. We have mapped the dynamic spatiotemporal patterns of the evoked optical signals and have outlined the early phase of the functional organization of the cranial nuclei related to the vagus.

Optical monitoring of synaptic transmission in bullfrog sympathetic ganglia using a voltage-sensitive dye

Multiple-site optical recording of neural activity, using a voltage-sensitive merocyanine-rhodanine dye (NK2761) and a 12 x 12-element photodiode array, was employed to monitor the synaptic transmission in the bullfrog lumbar sympathetic ganglion. When the presynaptic nerve fibers were stimulated, the signals had two or three peaks, and their later phase was reduced in a low calcium bathing solution or in a solution containing D-tubocurarine. We conclude that the first phase of the optical signals evoked by the presynaptic stimulation corresponds to the electrical activity of the presynaptic neurons. The signals evoked by the postsynaptic stimulation showed relatively simple shape reflecting the action potential in the ganglion cells.

Optical illustration of glutamate-induced cell swelling coupled with membrane depolarization in embryonic brain stem slices

Using intrinsic- and voltage-sensitive dye optical recordings, we have elucidated coupling of glutamate-induced depolarization and neuronal swelling in early embryonic chick brain stem slices. Twenty-four slices were prepared from 8-day old chick embryos, and stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). The pressure ejection of glutamate to one site within the preparation evoked changes in transmitted light intensity. With 700 nm incident light, three components were identified in glutamate-induced optical changes. The first component was wavelength dependent, while the second and third components were independent of the wavelength. With reference to the action spectrum of the merocyanine-rhodanine dye and osmotic changes in optical properties, we concluded that the first component reflects glutamate-induced depolarization of the membrane, and that the second component is an intrinsic light-scattering change resulting from neural cell swelling coupled with the membrane depolarization.

Optical characterization of a novel GABA response in early embryonic chick brainstem

To examine the functional expression of embryonic GABA receptors, the inhibitory effects were studied of GABA (GABA responses) on the excitatory postsynaptic potentials evoked by vagal stimulus in seven- to 10-day-old embryonic chick brainstem slice preparations. A multiple-site optical recording technique was used, with a multiple element photodiode array system and a fast voltage-sensitive merocyanine-rhodanine dye (NK2761). First, in the GABA response, three components were pharmacologically identified: component 1, related to GABA(A) receptors; component 2, related to GABA(B) receptors; and component 3 which is insensitive to GABA(A) and GABA(B) antagonists, but is stimulated by both GABA(A) and GABA(B) agonists. Subsequently. the embryogenesis and early development of the three components were investigated, and early developmental maps of regional distribution patterns of the three components were constructed. Components 1 and 3 have already emerged in the seven-day-old embryonic brainstem preparation; component 2 appeared in the eight-day-old preparations. No component related to GABA(C) receptors was observed in the seven- to 10-day-old embryonic stages. From the pharmacological properties of component 3, we suggest that it is related to a new subtype, the GABA(D) receptor.

Response and level of beta-adrenergic, vasoactive intestinal peptide, and PACAP receptors during the circadian cycle

PURPOSE

To determine whether a nocturnal increase of ciliary process beta-adrenergic receptor responsiveness can explain the observation that timolol decreased the aqueous flow rate and intraocular pressure (IOP) during the night but not during the day in rabbits.

METHODS

Rabbits were housed in alternating 12-hour periods of light and dark. In vitro stimulation of tissue cyclic adenosine monophosphate (cAMP) levels by isoproterenol (ISO), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating polypeptide (PACAP), or a soluble derivative of forskolin (sFSK) was measured in ciliary processes harvested at mid-light phase and early and late dark phase. Inhibition of ISO and VIP stimulation of ciliary process cAMP by an alpha 2-adrenergic agonist and maximal binding of [125I]I-pindolol, [125I]I-VIP, and [125I]I-PACAP in ciliary process membranes were measured at the same three times.

RESULTS

Although there may have been a nocturnal increase in the sensitivity of ciliary process cAMP levels to stimulation by ISO, this was not observed consistently, VIP, but not PACAP, stimulation increased at night, but there was no change in the response to sFSK. Inhibition by apraclonidine of elevated ciliary process cAMP levels was constant at all three times. Ligand-binding studies showed little change in ciliary process beta-adrenergic, VIP-, or PACAP-receptor levels at the three times.

CONCLUSIONS

There is no convincing evidence for a nocturnal increase in beta-adrenergic receptor sensitivity in rabbit ciliary processes that could explain the difference between day and night effects of timolol on aqueous flow and IOP.

Pax-6 is involved in the specification of hindbrain motor neuron subtype

Pax-6 is a member of the vertebrate Pax gene family, which is structurally related to the Drosophila pair-rule gene, paired. In mammals, Pax-6 is expressed in several discrete domains of the developing CNS and has been implicated in neural development, although its precise role remains elusive. We found a novel Small eye rat strain (rSey2) with phenotypes similar to mouse and rat Small eye. Analyses of the Pax-6 gene revealed one base (C) insertion in an exon encoding the region downstream of the paired box of the Pax-6 gene, resulting in generation of truncated protein due to the frame shift. To explore the roles of Pax-6 in neural development, we searched for abnormalities in the nervous system in rSey2 homozygous embryos. rSey2/rSey2 exhibited abnormal development of motor neurons in the hindbrain. The Islet-1-positive motor neurons were generated just ventral to the Pax-6-expressing domain both in the wild-type and mutant embryos. However, two somatic motor (SM) nerves, the abducent and hypoglossal nerves, were missing in homozygous embryos. By retrograde and anterograde labeling, we found no SM-type axonogenesis (ventrally growing) in the mutant postotic hindbrain, though branchiomotor and visceral motor (BM/VM)-type axons (dorsally growing) were observed within the neural tube. To discover whether the identity of these motor neuron subtypes was changed in the mutant, we examined expression of LIM homeobox genes, Islet-1, Islet-2 and Lim-3. At the postotic levels of the hindbrain, SM neurons expressed all the three LIM genes, whereas BM/VM-type neurons were marked by Islet-1 only. In the Pax-6 mutant hindbrain, Islet-2 expression was specifically missing, which resulted in the loss of the cells harboring the postotic hindbrain SM-type LIM code (Islet-1 + Islet-2 + Lim-3). Furthermore, we found that expression of Wnt-7b, which overlapped with Pax-6 in the ventrolateral domain of the neural tube, was also specifically missing in the mutant hindbrain, while it remained intact in the dorsal non-overlapping domain. These results strongly suggest that Pax-6 is involved in the specification of subtypes of hindbrain motor neurons, presumably through the regulation of Islet-2 and Wnt-7b expression.

Optical mapping of conduction patterns of normal and tachycardia-like excitations in the rat atrium

Multiple-site optical recording of transmembrane voltage activity (MSORTV), using a voltage-sensitive dye and a 12 x 12-element photodiode array, was employed to monitor action potentials in the rat atrium. Atrial preparations including the sinus node area, caval area, and atrial septum were dissected from adult rat hearts and stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). For suppression of optical artefacts due to contractile movements, a bathing medium containing 2,3-butanedione monoxime (BDM: 10-20 mM) was used. The spread of spontaneous excitation from the pacemaker was assessed optically by timing the initiation of the action potential-related extrinsic absorption changes. The optical signals were recorded from more than 300 contiguous loci in the atrium by sliding the photodiode array over the image of the preparation; in this way, the intra-atrial conduction pattern of spontaneous excitation was mapped. The obtained maps revealed a non-radial spread of excitatory waves originating in the pacemaking area over the atrium. Furthermore, we also mapped the conduction pattern of long-lasting tachycardia-like excitation evoked by a short train of electrical stimulation (5-10 Hz, 1-2s) applied with a bipolar electrode. These maps suggest that excitatory waves are propagated in a circular pathway which often surrounds the ostium of the superior or inferior vena cava. Various patterns for the pathway were also demonstrated optically.

Incidence of retinal vein occlusion at the Glaucoma Clinic of Hiroshima University

We prospectively surveyed the incidence of retinal vein occlusion (RVO) at the glaucoma clinic of Hiroshima University between 1986 and 1991. Among 433 glaucoma patients, 18 (4.2%) subsequently presented with RVO, 9 had central retinal vein occlusion (CRVO) and 9 exhibited branch retinal vein occlusion (BRVO). Seven of 87 (8.1%) patients with primary angle closure glaucoma exhibited RVO, showing the highest incidence among glaucoma types. The incidence of RVO detected by the general outpatient clinic was 0.59% during the same period. The BRVO/CRVO ratio in the glaucoma clinic was 1.0, while it was 4.3 in the general outpatient clinic. Glaucoma is an important risk factor for the development of RVO, especially CRVO.

Video-imaging assessment of initial beating patterns of the early embryonic chick heart

The spatiotemporal pattern and its developmental changes were assessed of the beating of the early embryonic chick tubular heart at the 9- to 17-somite stages of development using a video-imaging method together with the three-dimensional modeling. In the late 9- and early 10-somite stages, contractions were observed only at the right margin of the ventricular wall. As development proceeded to 12-somite or later stages, the propagation of contractile waves from the atrial pacemaking area towards the root of the ventral aortae was observed. The prototype of the peristaltic pattern of contractions was established by the 14-somite stage of development with an increase in the conduction velocity of the contractile wave.

Ansamycin antibiotics as free radical scavengers isolated from Streptomyces by using the bactericidal action of the hydroxyl radical

Ansamycin antibiotics (1-4) were isolated from the cultured broth of Streptomyces sp. USF-319 strain as a result of our screening for free radical scavengers. They inhibited the bactericidal effect of the Fenton reagent toward Bacillus subtilis by their radical scavenging activity. Some of them also showed inhibitory activity against lipid peroxidation and lipoxygenases.

Optical studies of the biphasic modulatory effects of glycine on excitatory postsynaptic potentials in the chick brainstem and their embryogenesis

Multiple-site optical recording of transmembrane potential activity, using a voltage-sensitive dye, was employed to monitor neural activity from the nucleus tractus solitarius of the chick embryo. Optical signals related to glutamate-mediated excitatory postsynaptic potentials were evoked by a brief square current pulse applied with a microsuction electrode to the vagus nerve, and were recorded simultaneously from many sites in the brainstem slice preparation. We have found that glycine has biphasic modulatory effects on the glutamate-mediated excitatory postsynaptic potentials: at lower concentrations, glycine enhances the glutamate-mediated excitatory postsynaptic potential-related optical signal, and at higher concentrations, it reduces the glutamate-mediated excitatory postsynaptic potential-signal. The enhancing effect was insensitive to strychnine, but the reducing effect was blocked by strychnine, suggesting that the former effect was induced by glycine which increased glutamate binding to N-methyl-D-aspartate receptors, and the latter resulted from an increase in chloride conductance through the strychnine-sensitive inhibitory glycine receptors in postsynaptic neurons. The inhibitory effect of glycine was first observed in the brainstem preparations at the seven-day-old embryonic stage, and the enhancing effect was first observed in the nine-day-old preparations. We determined regional distributions of the biphasic effects of glycine in the seven- to nine-day old embryonic preparations. The spatial distribution of the enhancing effect appeared to be concentrated on the ventral side of the nucleus tractus solitarius, and the inhibitory effect was relatively concentrated in the medial portion. Furthermore, we compared the glycine effect with the effect of Mg(2)+ on N-methyl-D-aspartate receptors, and we have found that the Mg(2)+ site is functionally organized prior to the glycine site during embryonic development.

Neuropeptide Y levels in the aqueous humor of rabbits

The concentration of neuropeptide Y in the aqueous humor (NPYaq) did not change during the circadian cycle in rabbits. However, NPYaq also did not decrease after superior cervical ganglionectomy or preganglionic section of the cervical sympathetic trunk (decentralization). Nor did NPYaq change after either stimulation, with para-aminoclonidine, or blockade, with rauwolscine, of prejunctional ocular alpha2-adrenergic receptors. Therefore, NPYaq does not reflect NPY release from ocular sympathetic nerves in rabbits.

Protein glycation inhibitors from thyme (Thymus vulgaris)

Nonenzymatic glycation of bovine serum albumin (BSA) was inhibited in vitro by some extracts of 34 kinds of spices. The methanol extract of thyme (Thymus vulgaris) had the most potent inhibitory activity among them. Chromatographic purification yielded four flavonoids, quercetin (1), eriodictyol (2), 5,6,4'-trihydroxy-7,8,3'-trimethoxyflavone (3), and cirsilineol (4). These known flavonoids suppressed the levels of advanced glycation end products (AGEs) and fructosamines, shown by the measurement of specific fluorescent groups and the reduction of nitroblue tetrazolium (NBT), respectively. The inhibitory activities were compared with those of other structure-related flavonoids and aminoguanidine.

A novel gamma-aminobutyric acid response in the embryonic brainstem as revealed by voltage-sensitive dye recording

Using a multiple-site optical recording technique employing a fast voltage-sensitive dye, we found a novel type of gamma-aminobutyric acid (GABA) response, which is insensitive to GABAA and GABAB antagonists, but is stimulated by either GABAA or GABAB agonist. This evidence was identified in the early embryonic brainstem slice preparation.

USF-19A, a new lipoxygenase inhibitor from Streptomyces sp

USF-19A, a soybean lipoxygenase (SBL) and human 5-lipoxygenase (5-LO) inhibitor, was isolated from Streptomyces sp. USF-19 strain. Its chemical structure was determined by spectroscopic evidence to be a new member of the antimycin antibiotic family. The IC50 value of USF-19A against 5-LO was 28.0 microM.

Evaluation of optimal voltage-sensitive dyes for optical monitoring of embryonic neural activity

To evaluate the suitability of a variety of fast voltage-sensitive dyes for optical recording of rapid transmembrane potential activity in the embryonic nervous system, we screened over twenty dyes, including several newly synthesized probes, in three different embryonic neural preparations: cervical vagus nerve bundle, nodose ganglion, and brainstem from 7-day old chick embryos. Measurements of voltage-related optical signals were made using a multiple-site optical recording system. Signal size, signal-to-noise ratio, photobleaching, and phototoxicity were examined. Several promising new merocyanine-rhodanine dyes for embryonic nervous systems were found.

Responses to glossopharyngeal stimulus in the early embryonic chick brainstem: spatiotemporal patterns in three dimensions from repeated multiple-site optical recording of electrical activity

In an effort to assess the spatial patterning of glossopharyngeal responses in the early embryonic chick brainstem, we used a multiple-site optical recording system with a 12 x 12 element photodiode array and a voltage-sensitive merocyanine-rhodanine dye (NK2761) to monitor neural transmembrane voltage activities. Seven and 8 d old embryonic chick brainstems were sliced into 1400-1600 microns thick sections with the glossopharyngeal and vagal nerves attached, and then stained with the dye. Neural voltage-related optical signals were evoked by a positive brief (depolarizing) square current pulse applied to the glossopharyngeal nerve with a microsuction electrode, and then recorded simultaneously from many loci in the objective two-dimensional image plane of a compound microscope. In addition to the multiple-site optical recording technique, we tried to introduce an optical sectioning method by changing the focal plane of the microscope to obtain three-dimensional information. Thus, we have been able to assess semiquantitatively the three-dimensional profiles of two glossopharyngeal response areas corresponding to the nucleus of the glossopharyngeal nerve (nucleus nervi glossopharyngei) and the nucleus of the tractus solitarius. Furthermore, glutaminergic excitatory postsynaptic potentials were determined within the response area corresponding to the nucleus of the tractus solitarius. In addition, we also compared the glossopharyngeal and vagal response areas and found that the cores of the related nuclei are separated in three dimensions.

A new simultaneous 1020-site optical recording system for monitoring neural activity using voltage-sensitive dyes

We have constructed a new 1020-site optical system for simultaneous recording of transmembrane electrical activity, using a 34 x 34-element photodiode array. This new apparatus permits analyses of the spatio-temporal pattern of neural activity, such as action potentials and postsynaptic potentials, in the central nervous system, at higher spatial and temporal resolutions.

Optical mapping of early embryonic expressions of Mg(2+)-/APV-sensitive components of vagal glutaminergic EPSPs in the chick brainstem

Multiple-site optical recording of transmembrane voltage activity, using a voltage-sensitive dye (NK2761) and a 12 x 12 element photodiode array, was employed to monitor neural responses in the slice preparations that were dissected from 6-9-d-old embryonic brainstems. Transmembrane voltage-related optical responses evoked by a brief square current pulse applied with a microsuction electrode to the vagus nerve were recorded simultaneously from many sites in the preparation. In preparations from 6-d-old embryos, only action potential-related spike-like optical signals were often detected in the normal bathing solution containing 0.5 mM Mg2+. However, in several loci of some preparations, excitatory postsynaptic potential-related slow signals were elicited in a Mg(2+)-free bathing medium, and these elicited slow signals were blocked by DL-2-amino-5-phosphonovaleric acid (2-APV). These results show a possible embryonic expression of NMDA receptor-mediated excitatory postsynaptic potentials. The slow signals were usually detected from tested preparations from 7-9-d-old embryos in normal bathing solution. The later phase of the slow signals was enhanced in a Mg(2+)-free bathing medium, and the enhanced component was also sensitive to 2-APV and insensitive to 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). There were regional differences in the degree of the enhancement of the slow signals in the Mg(2+)-free bathing medium, and of the 2-APV-induced reduction of the slow signals. We have constructed early developmental maps of the spatial patterns of the slow signals related to Mg(2+)- and 2-APV-sensitive postsynaptic potentials. These maps reflect the spatial distribution of functional expression of the NMDA receptors during early development of the chick brainstem. The present findings are new data that have not been reported previously, and they have been obtained for the first time using the multiple-site optical recording technique with a voltage-sensitive dye.

Optical assessment of spatial patterning of strength-duration relationship for vagal responses in the early embryonic chick brainstem

The spatial patterning of strength-duration relationship for neural responses to vagus nerve stimulation in the early embryonic chick brainstem preparation was assessed by means of an optical method for monitoring neural activity using a voltage-sensitive dye. Intact brainstem, and brainstem slice preparations, together with the attached vagus nerve, were dissected from 6- to 8-day (d)-old chick embryos. They were stained with a voltage-sensitive merocyanine-rhodanine dye (NK2761). Application of depolarizing square current pulses to the vagus nerve fibers using a micro-suction electrode evoked voltage-related optical (absorption) responses in the brainstem. The optical responses were recorded simultaneously from 127 contiguous sites in both the intact and slice preparations, using a 12 x 12-element photodiode array. The amplitude of the evoked signals and the extent of the response area depended on the strength and duration of the stimulating current pulse. Thus, we determined the threshold current strength needed to evoke the fast spike-like optical signal, corresponding to the action potential, in response to vagal stimulation at a given duration, and we obtained strength-duration curves for 100-200 contiguous regions in the preparation. The strength-duration curves could be apparently fitted by the empirical formula of Weiss. From these curves we obtained the rheobasic currents as a possible indication of neural responsiveness to peripheral vagus stimulation, and we constructed the map of the spatial distribution of the rheobasic currents. The rheobasic current is smallest in the central region of the response area, and it is distributed in a layered pattern of increasing value. In accordance with such a pattern, the minimum rheobasic current decreased and the response area expanded developmentally. The results suggest that the ordered patterns of spatial distributions of the size of the axon, the specific membrane resistance, sodium channel activity, and other electrophysiological factors underlie the initial process of functional organization of the dorsal motor nucleus within the brainstem during early embryonic development.

Optical monitoring of early appearance of spontaneous membrane potential changes in the embryonic chick medulla oblongata using a voltage-sensitive dye

Using a voltage-sensitive merocyanine-rhodamine dye (NK2761) and a 12 x 12-element photodiode matrix array, we recorded optically spontaneous membrane potential changes in a slice preparation from the embryonic chick brain stem during early development. The spontaneous optical signals, related to membrane potential changes, showed a simple monophasic shape with a relatively long duration, and they were synchronized among the different regions in the medulla oblongata. The spontaneous signals were first detected from seven-day-old embryos, and were not present in six-day-old embryos. The spontaneous signals appeared sporadically, and their frequency was very low. Three modes of optical signals termed "singlet-mode", "doublet-mode", and "triplet-mode" were observed. In the doublet- and triplet-modes, the spatial pattern of the first signal was primarily similar to that of the singlet-mode signal, whereas the signal size and spatial extent of the second and third signals appeared to decay.

[Modulation of the adenylate cyclase-cAMP pathway by protein kinase C in chick retinal pigment epithelium]

I investigated stimulation of cyclic adenosine 3':5'-monophosphate (cAMP) production by isoproterenol and forskolin in cultured chick embryo retinal pigment epithelium. In addition, in order to study the interaction between signal transduction systems, I studied the effects of phorbol 12-myristate, 13-acetate (PMA), a protein kinase C (PKC) activator, on isoproterenol- or forskolin-stimulated cAMP production. After stimulation with 10(-9)-10(-5) M isoproterenol and forskolin, a marked and concentration-dependent increase in cAMP level was observed. However, addition of 10(-10)-10(-5) M PMA had no effect on the cAMP level. Preincubation of isoproterenol and forskolin with 100 nM PMA suppressed the increase of cAMP. The suppressive effect of PMA was stronger on isoproterenol-stimulated production than on forskolin-stimulated production. 4 alpha-phorbol 12, 13, didecanoate, a weak activator of PKC, had a weak suppressive effect on cAMP-production stimulated by isoproterenol. Both staurosporin and H-7, 1-(5-isoquinolinylsulfonyl)-methylpiperazine, inhibitors of PKC, decreased the suppression of cAMP production by PMA. It is speculated that in chick retinal pigment epithelium PKC stimulators, such as PMA, may inhibit the adenylate cyclase pathway.