[Effects of early enteral feeding on nitric oxide synthase activity in small intestine in burned rat]

OBJECTIVE

Our previous studies have proved that early enteral feeding could improve intestine blood flow after burn injury. But the mechanism was far from being clarified. This study was attempted to explore the effects of early enteral feeding on nitric oxide synthase (NOS) activity in burned rat small intestine and the relationship between the intestine mucosa blood flow (IMBF) and the activity of NOS.

METHODS

The rats were randomly divided into three groups: burned control (B), burned and early enteral feeding (EF), and normal control (C). The activity of NOS including constitute NOS(cNOS) and inducible NOS(iNOS), and the IMBF were determined at postburn 0, 3, 6, 12, 24, 48 hours.

RESULTS

It was found that cNOS activity and IMBF were decreased markedly postburn, and there was positive correlation between cNOS and IMBF (r = 0.97, P < 0.01). But the activity of iNOS, total NOS were increased significantly postburn, they had no correlation to the IMBF. In EF group cNOS activity and the IMBF were significantly higher, the iNOS was obviously lower than that of B group and there was no significant difference of total activity of NOS between two groups.

CONCLUSION

Our results suggested that NOS which is catalyzed from cNOS may play main role in adjusting IMBF. By using early enteral feeding the activity of cNOS is increased and the ischemic state in small intestine is improved after burn injury.

[Application of diode laser in the operation of retinal diseases]

OBJECTIVES

To evaluate the effects of diode laser photocoagulation applied on 43 cases of various kinds of fundus diseases with media opacity and on 40 cases during vitreo-retinal surgery.

METHODS

Indirect ophthalmoscope laser photocoagulator was used for fundus diseases, and endolaser used during surgery.

RESULTS

Vision was improved in 24.7% of the eyes, and was unchanged in 62.9% of the eyes. The neovascularization in proliferative diabetic retinopathy regressed in 78.3% of the eyes. All the retinal holes were closed.

CONCLUSIONS

Diode laser can be used for treatment of some retinal diseases and in the operation. Good results can be obtained in the eyes with some extent of media opacity. No obvious side-effect was observed.

Redefining the separation factor: a potential pathway to a unified separation science

Understanding the separation process in capillary electrophoresis (CE) leads to the unification of the theories for separation science. While the separation of analytes is governed by equilibria in chromatography, and by (centrifugal) field in ultracentrifugation, the separation in CE is governed by both equilibria and (electric) field. Therefore, a comprehensive separation theory that describes the separation process of analytes in CE should be able to describe the separation processes in both chromatography and ultracentrifugation. In this paper, we propose that individual capacity factors for each analyte species be used to describe the migration behavior of an analyte. The effect of field on each analyte species, as well as the effect of equilibria are considered in deriving a generalized equation that is applicable for all separation techniques. The separation factor defined at present does not directly relate to the migration rates of the analytes, and therefore can not be used in a generalized theory. We propose that the ratio of the migration rates of a pair of analytes (gamma) should be used as the separation factor, instead of the ratio of the two capacity factors. When gamma is used to describe the separation of two closely migrating analytes, all separation techniques have the same resolution equation.

Ligation of CD2 provides a strong helper signal for the production of the type 2 cytokines interleukin-4 and -5 by memory T cells

In this study, we investigated the efficiency of costimulatory signaling provided by anti-CD2 monoclonal antibodies (mAbs) for the production of type 1 (IL-2 and IFN-gamma) and type 2 (IL-4, IL-5, and IL-10) cytokines by human T cells. We cultured purified human T cells (freshly isolated from blood) with immobilized anti-CD3 mAb, either alone or in combination with anti-CD28 or anti-CD2 mAbs. When compared with the standard costimulatory signal anti-CD28, anti-CD2 mAbs (9-1 plus 9.6) were shown to be more potent costimulators of IL-4 production and to have similar activity for IL-5 production, but to be less potent for costimulation of IL-2, IL-10, and IFN-gamma production. IL-4 production was completely inhibited by cyclosporin A or by blocking IL-2 activity and its receptor. IL-4 and IL-5 were produced by CD45RO+ T cells but not by CD45RA+ T cells, indicating that anti-CD2 in this system costimulated type 2 cytokine production by differentiated memory cells. In the presence of IL-12, the cytokine profile was shifted to high IFN-gamma and IL-10 production and IL-4 and IL-5 production were slightly inhibited. Our data thus suggest that CD2 ligation plays an important role in the upregulation of Th2-like T cell activity (especially IL-4 production), but they also show that this effect is strongly modulated by IL-12, resulting in predominant IL-10 and IFN-gamma production instead.

Preparation and Organized Assembly of Nanoparticulate TiO2-Stearate Alternating Langmuir-Blodgett Films

Nanoparticulate TiO2-stearate Langmuir-Blodgett-type monolayers and multilayers were directly obtained by using TiO2 hydrosol as the subphase. The surface pressure-versus-surface area isotherms showed that the monolayer could be compressed to a mean molecular area of 0.25 nm2. The monolayer was transferred onto a CaF2 or Si substrate at a dipping speed of 18 cm/min and surface pressure of 25 mN/m. It exhibited Y-type multilayer films over the range investigated (1-30 layers) with a transfer ratio of 1.0 &plusmn; 0.1. FTIR transmission spectra and linear infrared dichroic spectra provided evidence of the formation of a stable organic/inorganic alternating multilayer with nanoparticulate TiO2 between the organic monolayers. There is only slight absorption in the range of the C;equals;O stretching vibration band of the carboxylic group with the 3- and 6-nm TiO2 nanoparticles. This means that TiO2 particles are packed closely; i.e., the surface coverage is very high. A possible structure consists of layers of nanoparticles in close-packed form with two stearate ion layers inbetween. But it can be seen that there are some carboxylic groups (1700 cm-1) not connected to the 20-nm TiO2 nanoparticle. Electron microscopic (TEM) images of TiO2-stearate monolayers show that high-coverage monolayers were obtained when the surface pressure increased to 25 mN/m and the dipping speed to 18 cm/min. Copyright 1997Academic Press

Interleukin 12 and B7/CD28 interaction synergistically upregulate interleukin 10 production by human T cells

Interleukin 12 (IL-12) is a heterodimeric cytokine which promotes the development of Th1 cells and their interferon gamma (IFN-gamma) production after TCR/CD3 triggering. Previous reports indicate that IL-12 synergizes with accessory signalling through B7/CD28 interaction in inducing proliferation and IFN-gamma production by human T cells. In this study, we investigated the capacity of IL-12 to modify cytokine synthesis by freshly purified human peripheral blood T cells stimulated with anti-CD3 as the primary signal and with CD80 on transfected mouse cells as an accessory signal. Our data demonstrate that IL-12 indeed synergizes with B7/CD28 interaction, not only in inducing IFN-gamma production, but also in enhancing IL-10 synthesis in a dose-dependent manner. In contrast, IL-4 and IL-5 production were slightly inhibited by IL-12. The effect of IL-12 on the secretion of IL-10 was confirmed by stimulating T cells in the absence of accessory cells with immobilized anti-CD3 mAb and soluble anti-CD28 mAb. CD80 and IL-12 mainly costimulated CD4+CD45RO+ T cells but not CD8+ or CD45RA+ T cells to produce IL-10. Cyclosporin A (CsA) partially inhibited, and a neutralizing anti-IL-2 mAb in combination with anti-IL-2R mAbs (anti-Tac and Mik beta1) strongly reduced IL-10 production. On the other hand, IL-12 did not affect IL-2 production. The data thus suggest a model in which optimal IL-10 production by stimulated peripheral blood T cells results from the co-operation of IL-12, B7/CD28 interaction and the ensuing IL-2 activity.

Chronic nicotine treatment up-regulates alpha3 and alpha7 acetylcholine receptor subtypes expressed by the human neuroblastoma cell line SH-SY5Y

Chronic exposure to nicotine has been reported to increase the number of nicotinic acetylcholine receptors (AChRs) in brain. The mechanism of up-regulation for the alpha4beta2 AChR subtype, which accounts for the majority of high affinity nicotine binding in mammalian brain, has previously been shown to involve a decrease in the rate of alpha4beta2 AChR turnover. Here, we report an investigation of the extent and mechanism of nicotine-induced up-regulation of alpha3 AChRs and alpha7 AChR subtypes expressed in the human neuroblastoma cell line SH-SY5Y. Up-regulation of human alpha3 AChRs and alpha7 AChRs, unlike alpha4beta2 AChRs, requires much higher nicotine concentrations than are encountered in smokers; the extent of increase of surface AChRs is much less; and the mechanisms of up-regulation are different than with alpha4beta2 AChRs. The mechanisms of up-regulation may be different for alpha3 AChRs or alpha7 AChRs. Chronic treatment with nicotine or carbamylcholine, but not d-tubocurarine, mecamylamine, or dihydro-beta-erythroidine, induced a 500-600% increase in the number of alpha3 AChRs but only a 30% increase in alpha7 AChRs. Chronic nicotine treatment did not increase affinity for nicotine or increase the amount of RNA for alpha3 or alpha7 subunits. The effect of nicotine on up-regulation of alpha7 AChRs was partially blocked by either d-tubocurarine or mecamylamine. The effect of nicotine treatment on the number of alpha3 AChRs was only slightly blocked by the antagonists d-tubocurarine, mecamylamine, or dihydro-beta-erythroidine at concentrations that efficiently block alpha3 AChR function. Most of the nicotine-induced increase in alpha3 AChRs was found to be intracellular. The alpha3 AChRs, which accumulate intracellularly, were shown to have been previously exposed on the cell surface by their susceptibility to antigenic modulation. The data suggest that chronic exposure to nicotine may induce a conformation of cell surface alpha3 AChRs that at least in this cell line are consequently internalized but not immediately destroyed.

Quantitative description of analyte migration behavior based on dynamic complexation in capillary electrophoresis with one or more additives

A comprehensive theory is proposed to describe the migration behavior of analytes in capillary electrophoresis (CE) when one or more additives are present in the buffer solution. This theory amalgamates and extends the previous work done by others. The capacity factor (k') in this theory is defined as the product of the equilibrium constant and the additive concentration, thus, k' changes linearly with additive concentration. The net electrophoretic mobility of an analyte is a function of k', therefore, it can be changed by varying the additive concentration. Three parameters are needed to predict the mobility of an analyte in a one-additive CE system: the mobility of the free analyte, the mobility of the complex, and the equilibrium constant for the analyte-additive interaction (which determines the fraction of the free analyte at different additive concentrations). When additives are used, the change in viscosity obscures this relationship, therefore, a viscosity correction factor is required to convert all mobilities to an ideal state where the viscosity remains constant. The migration behavior of an analyte in a solution with multiple additives can be predicted and controlled, once the equilibrium constants of the interactions between the analyte and each of the additives are obtained separately. beta-Cyclodextrin and hydroxypropyl-beta-cyclodextrin are used as additives and the migration behavior of phenol, p-nitrophenol, and benzoic acid are studied as a model system to verify this theory. When the necessary viscosity correction factor is included, the net electrophoretic mobilities of the analytes obtained from experimental results agree with the values predicted by the theory based on dynamic complexation. Although only experiments with one and two additives were carried out to verify the theory, the equations apply to situations when more than two additives are used. The relationship between the theories of electrophoresis and chromatography is clarified.

Life events and anxiety in Chinese medical students

The authors studied a sample of 537 Chinese medical students aged 15-21 years using Zung's Self-Rating Anxiety Scale (SAS) and a life events checklist. The results showed that test pressure, less free time, peer competition, failure in a test, and financial problems were the most common stressful experiences for medical students during the previous 12 months. Social and personal problems were rated the highest on scores of perceived stress. Of all students, 12.5% scored over the cut-off point on the SAS previously established to indicate risk of psychiatric disorder. Using a stepwise regression analysis, it was shown that poor health status, little physical exercise, financial problems in the family, test pressure, conflict with classmates, the personality trait of introversion, getting up late in the morning, and freshman status were independently associated with the presence of anxiety.

Analysis of west African hunters for foamy virus infections

Foamy viruses are a genus of complex retroviruses that infect a wide variety of mammals. However, a clear association with any disease process has yet to be proven for these viruses. A higher human seroprevalence was reported in African populations, perhaps due to exposure to simian foamy viruses (SFV) endemic in primates. However, the earlier serologic surveys were not confirmed by studies employing nucleic acid amplification. Foamy virus infections of humans clearly do occur as rare zoonoses among primate center or laboratory workers exposed to captive primates or their blood. We sought to detect foamy virus infections in a cohort of humans also presumed to be exposed to SFV, i.e., West African hunters. We constructed recombinant vaccinia viruses that expressed human foamy virus (HFV) Gag or Env polyproteins in mammalian cells. The sera from 17 monkey hunters or several controls were tested in radioimmunoprecipitation assays (RIPAs) against the recombinant HFV proteins. Chimpanzee sera or HFV-positive human sera immunoprecipitated gp130, the HFV Env precursor, as well as p74, the HFV Gag polyprotein. None of the hunters' sera recognized both of these recombinant proteins. We then employed a nested polymerase chain reaction (PCR) analysis of the hunters' DNA but also failed to detect foamy virus infections. Therefore, by utilizing a recombinant RIPA and a nested PCR assay, we have not identified foamy virus infections occurring naturally in hunters exposed to wild monkeys in West Africa.

Immortalization of inbred rabbit keratinocytes from a Shope papilloma and tumorigenic transformation of the cells by EJ-ras

An immortalized cell line of keratinocytes, named SPG1-3, was established from a papilloma induced from cottontail rabbit papillomavirus (CRPV)-infected inbred rabbit skin. The cells have reached 60 passages in culture and are still growing well, but they are not tumorigenic in athymic mice. Although CRPV DNA was present as extrachromosomal episomes in the papilloma from which the cell line was derived from a single colony of keratinocytes, there was no CRPV DNA detectable in the cells. Three sub-cell lines of SPG1-3EJ, SPG1-3EJ1 and SPG1-3EJ2 were then established from the EJ-ras transfected SPG1-3 cells. All of the three sub-lines contained both EJ-ras DNA and a 1.2 kb transcript of EJ-ras, and they are malignantly tumorigenic in athymic mice. These data indicate that CRPV genome and its expression might be essential for the initiation and maintenance of neoplasia, but not for the maintenance of immortalization of the tumor-derived cells. In addition, some oncogenes such as EJ-ras may play an essential role in tumorigenic and malignant conversion of the immortalized cells. These cell lines derived from inbred rabbit skin may provide a useful in vitro system for better understanding of the oncogenic processes of papillomavirus-involved neoplastic progression by transfecting the cells with CRPV genes and serial transplantation to the inbred rabbits for studying host immune responses to the viral oncogenic potential.

Organization of 'nanocrystal molecules' using DNA

Patterning matter on the nanometre scale is an important objective of current materials chemistry and physics. It is driven by both the need to further miniaturize electronic components and the fact that at the nanometre scale, materials properties are strongly size-dependent and thus can be tuned sensitively. In nanoscale crystals, quantum size effects and the large number of surface atoms influence the, chemical, electronic, magnetic and optical behaviour. 'Top-down' (for example, lithographic) methods for nanoscale manipulation reach only to the upper end of the nanometre regime; but whereas 'bottom-up' wet chemical techniques allow for the preparation of mono-disperse, defect-free crystallites just 1-10 nm in size, ways to control the structure of nanocrystal assemblies are scarce. Here we describe a strategy for the synthesis of 'nanocrystal molecules', in which discrete numbers of gold nanocrystals are organized into spatially defined structures based on Watson-Crick base-pairing interactions. We attach single-stranded DNA oligonucleotides of defined length and sequence to individual nanocrystals, and these assemble into dimers and trimers on addition of a complementary single-stranded DNA template. We anticipate that this approach should allow the construction of more complex two- and three-dimensional assemblies.

Assembly of human neuronal nicotinic receptor alpha5 subunits with alpha3, beta2, and beta4 subunits

Nicotinic acetylcholine receptors formed from combinations of alpha3, beta2, beta4, and alpha5 subunits are found in chicken ciliary ganglion neurons and some human neuroblastoma cell lines. We studied the co-expression of various combinations of cloned human alpha3, beta2, beta4, and alpha5 subunits in Xenopus oocytes. Expression on the surface membrane was found only for combinations of alpha3beta2, alpha3beta4, alpha3beta2alpha5, and alpha3beta4alpha5 subunits but not for other combinations of one, two, or three of these subunits. alpha5 subunits assembled inside the oocyte with beta2 but not with alpha3 subunits or other alpha5 subunits. alpha5 subunits coassembled very efficiently with alpha3beta2 or alpha3beta4 combinations. The presence of alpha5 subunits had very little effect on the binding affinities for epibatidine of receptors containing also alpha3 and beta2 or alpha3 and beta4 subunits. The presence of alpha5 subunits increased the rate of desensitization of both receptors containing also alpha3 and beta2 or alpha3 and beta4 subunits. In the case of receptors containing alpha3 and beta4 subunits, the addition of alpha5 subunits had little effect on the responses to acetylcholine or nicotine. However, in the case of receptors containing alpha3 and beta2 subunits, the addition of alpha5 subunits reduced the EC50 for acetylcholine from 28 to 0.5 microM and the EC50 for nicotine from 6.8 to 1.9 microM, while increasing the efficacy of nicotine from 50% on alpha3beta2 receptors to 100% on alpha3beta2alpha5 receptors. Both alpha3beta2 and alpha3beta2alpha5 receptors expressed in oocytes sedimented at the same 11 S value as native alpha3-containing receptors from the human neuroblastoma cell line SH-SY5Y. In the receptors from the neuroblastoma alpha3, beta2, and alpha5 subunits were co-assembled, and 56% of the receptor subtypes containing alpha3 subunits also contained beta2 subunits. The beta2 subunit-containing receptors from SH-SY5Y cells exhibited the high affinity for epibatidine characteristic of receptors formed from alpha3 and beta2 or alpha3, beta2, and alpha5 subunits rather than the low affinity exhibited by receptors formed from alpha3 and beta4 or alpha3, beta4, and alpha5 subunits. Nicotine, like the structurally similar toxin epibatidine, also distinguishes by binding affinity two subtypes of receptors containing alpha3 subunits in SH-SY5Y cells. The affinities of alpha3beta2 receptors expressed in oocytes were similar to the affinities of native alpha3 containing receptors from SH-SY5Y cells for acetylcholine, cytisine, and 1,1-dimethyl-4-phenylpiperazinium.

Accessory signaling by CD40 for T cell activation: induction of Th1 and Th2 cytokines and synergy with interleukin-12 for interferon-gamma production

The interaction of CD40 ligand (CD40L) on activated T cells with CD40 on B cells, monocytes and dendritic cells is essential for humoral immunity and for up-regulation of antigen-presenting cell (APC) functions, as a result of signaling through CD40. There are also some indications that after interaction with CD40, CD40L can directly signal T cells. In this study we demonstrate that upon stimulation of human peripheral blood T cells through the T cell receptor (TCR)/CD3 complex, CD40/CD40L interaction strongly enhances the production of Th1 cytokines such as interleukin (IL)-2 and interferon (IFN)-gamma and Th2 cytokines such as IL-4, IL-5 and IL-10 by a direct effect on T cells. Furthermore, CD40/CD40L interaction synergizes with IL-12 in selectively enhancing IFN-gamma production by purified anti-CD3-stimulated T cells. These effects were observed at both the protein and the mRNA level. Both CD4+ and CD8+ T cells were able to produce IFN-gamma in the presence of helper signals from IL-12 and CD40, although CD8+ T cells were less active. Since CD40/CD40L interaction also up-regulates IL-12 production and B7 expression by APC, our results suggest that CD40/CD40L interaction is bidirectional, and promotes activation of both APC and T cells.

Immunological evidence for the expression of the Fas antigen in the infant and adult human ovary during follicular regression and atresia

Immunohistochemical localization of the Fas antigen in the infant and adult human ovary during follicular growth, regression, and atresia was examined by the avidin/biotin immunoperoxidase method with a monoclonal antibody to the Fas antigen. Western blotting was used to confirm the presence of the Fas antigen protein. In primordial and primary follicles within the normal adult ovary, only the oocyte showed moderate immunostaining for the Fas antigen. In secondary and antral follicles, only the oocyte showed weak staining for the Fas antigen, while in preovulatory follicles, neither the oocyte nor the granulosa and theca cells were immunostained for the Fas antigen. In corpora lutea, the Fas antigen staining became apparent in the granulosa lutein cells during the early luteal phase and intensified during the mid luteal phase, while the theca lutein cells became positive for the Fas antigen staining during the mid luteal phase. During the late luteal phase, the staining intensity of the Fas antigen in the regressing corpora lutea further increased. As the regressing corpora lutea were converted into corpora albicans, the staining intensity decreased, and the corpora albicans and stromal cells were negative for the Fas antigen. In atretic primordial and primary follicles, only the degenerating oocyte showed the Fas antigen staining. By contrast, in atretic antral follicles, the Fas antigen staining was profound in the degenerating granulosa cells at the early stage of atresia, and at the mid stage of atresia it was intensified in the cell surface of the scattered granulosa cells and became apparent in the theca cells. At the late stage of atresia the Fas antigen remained only in the hypertrophied theca cells. In the infant ovary, only the oocyte in primordial and primary follicles exhibited intense staining for the Fas antigen. In the postmenopausal ovary, the Fas antigen staining was entirely negative. Western blot analysis revealed the presence of the Fas antigen protein with a molecular mass of 45 kDa in luteal tissues. On the basis of the recent evidence, that the Fas antigen mediates an apoptotic signal in a variety of cells, the abundant expression of the Fas antigen in the regressing corpora lutea and atretic follicles suggests that the Fas antigen participates in luteal regression and follicular atresia through the apoptotic process. Furthermore, notable expression of the Fas antigen in the oocyte of primordial and primary follicles within the infant and adult human ovary followed by the decrease in the Fas antigen expression in the oocyte with the advance of follicular maturation suggests that the Fas antigen expression in the oocyte may play a role in follicular selection.

Inhibitory effect of suberogorgin on acetylcholinesterase

AIM

To study the selection, reversibility, and kinetics of suberogorgin (Sub) on acetylcholinesterase (AChE).

METHODS

The human plasma was used as butyrylcholinesterase (BuChE). The activity of ChE was determined with colorimetry.

RESULTS

Sub obviously inhibited the AChE in vitro with pl50 4.03, 4.92, 3.82, and 4.67 in RBC membranes (of rat and human) and tissue extracts (of rat brain and earthworm dorsal muscle), respectively. No inhibition on BuChE was observed. The inhibition of Sub on AChE was far lower than that of physostigmine, but was close to that of galanthamine. Sub decreased the AChE activity to the lowest within 3 min after it was incubated with AChE. Centrifugalization washing reactivated the AChE which had been inhibited by Sub. The double-reciprocal plots of different concentrations of Sub on AChE showed parallel lines.

CONCLUSION

Sub was a selective, reversible, and contra-competetive inhibitor of AChE at the binding site on the peripheral anion region of AChE.

Comparison of immunocytologic localization of insulin-like growth factor binding protein-4 in normal and polycystic ovary syndrome human ovaries

The cytologic localization and cellular levels of insulin-like growth factor binding protein-4 (IGFBP-4) in follicular and stromal compartments of normal and polycystic ovary syndrome (PCOS) ovaries during follicular growth and regression were investigated by the avidin/biotin immunoperoxidase method with a polyclonal antibody to human IGFBP-4, and a comparative assessment of IGFBP-4 expression in normal and PCOS ovaries was provided. In normal human ovaries, IGFBP-4 was immunolocalized to the oocyte throughout follicular growth, while the surrounding granulosa and theca cells were negligible for IGFBP-4 immunostaining in primordial, preantral and antral follicles. IGFBP-4 immunostaining became apparent, however, in the lutein cells of corpora lutea and the granulosa and theca cells of atretic follicles. In PCOS ovaries, prominent immunostaining for IGFBP-4 was apparent not only in the oocyte, but also in the surrounding granulosa cells in preantral follicles. In antral follicles from PCOS women without hyperinsulinemia, IGFBP-4 immunostaining was more prominent in the granulosa cells than the theca cells, whereas in antral follicles from PCOS women with hyperinsulinemia IGFBP-4 immunostaining was more prominent in the theca cells than the granulosa cells. Furthermore, in atretic follicles within PCOS ovaries IGFBP-4 immunostaining was prominent in the theca cells, regardless of the association of hyperinsulinemia. These results demonstrate for the first time that there is a great difference in cellular expression of IGFBP-4 between normal and PCOS human ovaries. In light of the high affinity of IGFBP-4 for IGF-1, the abundant expression of IGFBP-4 in granulosa and theca cells of preantral and antral follicles of PCOS ovaries may lead to decreases in the bioavailability of IGF-I in those follicles. The decrease in IGF-I-mediated stimulation of gonadotropin actions on granulosa and theca cells in preantral and antral follicles may impair the induction of aromatase activity, causing an androgenic microenvironment which is characteristic of atretic follicles and PCOS follicles.

Effects of suberogorgin and its derivates on learning and memory in mice

AIM

To study the relationship between the effects of suberogorgin (Sub) and its derivates on memory and their anti-acetylcholinesterase (AChE) actions.

METHODS

The step-down latency (SDL) and the escape latency (EL) of mice were determined at the same time in a passive avoidance task after Sub, N-suberogorgamide-N-N-dicyclohexyl urea (Sub-DU), or N-cyclohexyl suberogorgamide (N-CS) was injected i.p. The AChE activities in brain hemogenates were determined with colorimetry.

RESULTS

Sub 1.9, Sub-DU 3.0, or physostigmine (Phys) 0.15 mg.kg-1 obviously lengthened the SDL by 195%, 271%, and 210%, and shortened the EL by 56%, 61%, and 33%, and the two formers inhibited the brain AChE activities by 17% and 19%, respectively in aging (3-4 months) mice. These actions were decreased in a dose-dependent manner when Sub or Sub-DU was increased to 2.9-4.3 or 4.5-6.7 mg.kg-1 respectively. Sub 1.9, Sub-DU 2.0, and Phys 0.15 mg.kg-1 also lengthened the SDL by 187%, 209%, and 152%, and shortened the EL by 52%, 62%, and 57%, respectively in aged (12-14 months) mice. Sub 1.3-1.9, Sub-DU 0.9-2.0, or Phys 0.15 mg.kg-1 reversed the cycloheximide- or scopolamine-induced disruptions of memory retention. No obvious effect of N-CS on the acquisition of memory and the AChE activity in mice was observed.

CONCLUSION

The improvements of Sub and Sub-DU on memory were chiefly related to their anti-AChE actions.

Tyrosine phosphorylation of extracellular signal-regulated protein kinase 4 in response to growth factors

Extracellular signal-regulated protein kinases (ERKs) are members of the mitogen-activated protein kinase family that are rapidly phosphorylated and activated in response to various extracellular stimuli, including growth factors. Of these, the ERK1 and ERK2 forms are by far the most abundant and the most studied. Much less is known about other ERK forms, including one previously designated ERK4 on the basis of its cross-reactivity with ERK1 and ERK2. We report here that ERK4 in rat PC12 pheochromocytoma cells can be immunoprecipitated by anti-ERK antiserum R2 and have used this re-agent to characterize this species further. We find that ERK4 rapidly becomes tyrosine-phosphorylated in response to nerve growth factor (NGF) and epidermal growth factor (EGF) and, to a lesser degree, in response to insulin and a permeant cyclic AMP analogue. As in the case of ERK1 and ERK2, tyrosine phosphorylation of ERK4 occurs by a ras-dependent pathway in response to NGF and EGF and shows prolonged kinetics for NGF but not EGF treatment. Recognition by multiple antisera directed against various domains of ERK1 supports classification of ERK4 within the ERK family; however, two-dimensional gel analysis clearly distinguishes ERK4 from isoforms of ERK1. These findings thus reveal an additional member of the ERK family that is responsive to growth factors and that could play a distinct role in intracellular signaling.