Lead inhibits nitric oxide production in vitro by murine splenic macrophages

The heavy metal lead is an environmental toxicant that can compromise host defense systems and induce pathophysiological changes in many organ systems. We report herein that low levels of lead can efficiently block nitric oxide production in vitro by murine splenic macrophages, which could contribute to lead's inhibition of pathogen killing by macrophages. We observed that lead was able to suppress nitric oxide production by concanavalin A-stimulated murine splenocyte cultures. Since splenocyte cultures contain macrophages, lymphocytes, and other cell types, we further delineated the target(s) of the inhibition. High- and low-dose interferon-gamma and tumor necrosis factor-alpha-induced nitric oxide production by macrophages was readily blocked by low levels of lead (ID50 = 0.35-0.95 microM or 0.07-0.19 ppm); however, activated T cell membrane-enhanced nitric oxide production by macrophages was less sensitive to inhibition by lead. Since lead has been reported to preferentially enhance the activation of T helper-2 cells, which produce interleukin-4, a regulator of macrophage activities, the role of interleukin-4 in the inhibition by lead also was assessed. Interleukin-4 did not mediate the inhibition; instead, interleukin-4 appeared to be an enhancing factor for nitric oxide production in vitro. The observed effects of lead on nitric oxide production may provide an explanation for some of the lead-induced abnormalities associated with host defense and organ systems in addition to the immune system.

Composite acupuncture treatment of mental retardation in children

128 children of mental retardation were diagnosed in accordance with the diagnostic standards proposed by WHO in 1985. The patients were treated compositely with acupuncture, auriculo-acupoint pellet pressure and herbal plasters on acupoints, bringing about improved mental developments in intelligence quotient (IQ) and social adaptation behaviour (SAB), as evidenced by recognized intelligence tests for children.

Activated T cells enhance nitric oxide production by murine splenic macrophages through gp39 and LFA-1

Macrophages can be stimulated to produce a relatively large amount of nitric oxide, which is an important component in macrophage-mediated defense mechanisms and regulation of T cell activities. It has been known that T helper (Th) cell activation requires intimate physical interaction between T helper cells and macrophages and that cytokines from activated Th cells regulate macrophage activities including nitric oxide production. The current study indicates that surface molecules on activated Th cells also can synergize with cytokines to substantially enhance nitric oxide production by macrophages through cell-cell contact. The CD40 ligand (gp39) and LFA-1 appear to be two major contributors for T cell dependent nitric oxide production.

Interferon gamma induces intercellular adhesion molecule-1 on murine midterm trophoblast and enhances susceptibility to specific lysis by paternally directed allo-immune cytotoxic T cells

Expression and function of intercellular adhesion molecule-1 (ICAM-1) on murine trophoblast cells and its regulation by interferon gamma (IFN-gamma) were investigated. Flow cytometry was used to detect ICAM-1 and class I major histocompatibility complex (MHC) antigen expression, while a 51Cr release assay was used to investigate the role of ICAM-1 in cytotoxic T lymphocyte (CTL)-mediated lysis and the effect of anti-ICAM-1 antibody blockade on lysis. We found that murine trophoblasts cells from midterm pregnancy (Day 14 postcoitum) express low or undetectable ICAM-1 and MHC antigens but that these are readily inducible by IFN-gamma. Untreated cells resisted lysis by allospecific CTL however, after treatment with IFN-gamma for 72 h, these trophoblasts were readily susceptible to lysis by allospecific CTL. The lysis was significantly reduced by anti-ICAM-1 antibody blocking. This finding which indicates that ICAM-1 can take part in CTL-mediated lysis of midterm trophoblast, has potentially important implications in vivo for the immunological relationship between mother and fetus.

Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells

Glutathione (GSH) is one of the most important physiological antioxidants involved in detoxification of hydrogen peroxide and lipid hydroperoxide. Previous studies have shown that cells can maintain and even increase cellular GSH content in response to sublethal oxidative stress. We hypothesized that gamma-glutamylcysteine synthetase (gamma GCS), the rate-limiting enzyme in de novo GSH synthesis, could be induced by oxidative stress. Rat lung epithelial L2 cells were challenged with 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), generates O2.- and H2O2 continuously through redox cycling. Exposure of confluent L2 cells with sublethal doses of DMNQ caused sustained elevation of cellular GSH levels over a 24-h period (to 2.5-fold with 10 microM). DMNQ caused increases in gamma GCS activity (70% at 24 h with 10 microM), the gamma GCS catalytic heavy subunit (gamma GCS-HS) protein level, and gamma GCS-HS mRNA content (approximately 4-fold after 6 h with 10 microM). The elevation of gamma GCS-HS mRNA by DMNQ was eliminated by co-incubation with actinomycin D. Nuclear run-on experiments demonstrated that the transcriptional rate of the gamma GCS-HS gene was increased by 3- or 6-h exposure to 10 microM DMNQ. Our results suggested that the induction of de novo GSH synthesis by naphthoquinone-induced oxidative stress is associated with the transcriptional activation of the gamma GCS-HS gene and the subsequent elevation in gamma GCS activity. Unlike simpler quinones, DMNQ cannot form a GSH conjugate. Thus, the induction of gamma GCS-HS gene transcription does not require formation of an electrophile-glutathione conjugate.

Rapamycin inhibits production of cytotoxic but not noncytotoxic antibodies and preferentially activates T helper 2 cells that mediate long-term survival of heart allografts in rats

Rapamycin (RAPA) induces unresponsiveness toward heart allografts by at least two mechanisms: selective production of noncytotoxic IgG2c-blocking Ab and preferential activation of Th2 cells. RAPA (0.8 mg/kg/day) delivered via a 14-day osmotic pump to Wistar Furth (WF; RT-1u) recipients prolongs Buffalo (BUF; RT-1b) heart allograft survival from a mean survival time (MST) of 6.5 +/- 0.5 days to 75.0 +/- 18.9 days (n = 18; p < 0.001), with 6 of 18 grafts beating for more than 100 days. Recipient sera or their IgG but not IgM fraction, obtained after postgrafting day 40, passively transfer the unresponsive state to sublethally irradiated secondary recipients in a dose-dependent and immunologically-specific fashion. Sera obtained after untreated WF hosts rejected BUF hearts contained IgG moieties of all subclasses that bound to class I MHC BUF epitopes. In contrast, the unresponsive sera contained predominantly non-C'-fixing IgG2c and only marginal amounts of activated (C') fixing IgG1, IgG2a, and IgG2b Ab. The transcription of IL-2, IL-4, and IL-10 mRNAs was assessed using a PCR method. There were similar increases in the levels of IL-2, IL-4, and IL-10 mRNA in heart allografts from both untreated and RAPA-treated recipients on day 5 postgrafting. In contrast, on days 60 and 300 postgrafting heart allografts from RAPA-treated unresponsive recipients showed increased levels of IL-10 and IL-4 but not of IL-2 mRNA, suggesting preferential activation of Th2 cells. Thus, RAPA treatment selectively inhibits the synthesis of C'-binding of IgG subclasses, spares the non C-binding blocking IgG2c Ab, and preferentially activates Th2 cells.

Rapamycin inhibits production of cytotoxic but not noncytotoxic antibodies and preferentially activates T helper 2 cells that mediate long-term survival of heart allografts in rats

Rapamycin (RAPA) induces unresponsiveness toward heart allografts by at least two mechanisms: selective production of noncytotoxic IgG2c-blocking Ab and preferential activation of Th2 cells. RAPA (0.8 mg/kg/day) delivered via a 14-day osmotic pump to Wistar Furth (WF; RT-1u) recipients prolongs Buffalo (BUF; RT-1b) heart allograft survival from a mean survival time (MST) of 6.5 +/- 0.5 days to 75.0 +/- 18.9 days (n = 18; p &lt; 0.001), with 6 of 18 grafts beating for more than 100 days. Recipient sera or their IgG but not IgM fraction, obtained after postgrafting day 40, passively transfer the unresponsive state to sublethally irradiated secondary recipients in a dose-dependent and immunologically-specific fashion. Sera obtained after untreated WF hosts rejected BUF hearts contained IgG moieties of all subclasses that bound to class I MHC BUF epitopes. In contrast, the unresponsive sera contained predominantly non-C'-fixing IgG2c and only marginal amounts of activated (C') fixing IgG1, IgG2a, and IgG2b Ab. The transcription of IL-2, IL-4, and IL-10 mRNAs was assessed using a PCR method. There were similar increases in the levels of IL-2, IL-4, and IL-10 mRNA in heart allografts from both untreated and RAPA-treated recipients on day 5 postgrafting. In contrast, on days 60 and 300 postgrafting heart allografts from RAPA-treated unresponsive recipients showed increased levels of IL-10 and IL-4 but not of IL-2 mRNA, suggesting preferential activation of Th2 cells. Thus, RAPA treatment selectively inhibits the synthesis of C'-binding of IgG subclasses, spares the non C-binding blocking IgG2c Ab, and preferentially activates Th2 cells.

Nicotinic antagonist-produced frequency-dependent changes in acetylcholine release from rat motor nerve terminals

1. The frequency (0.5-150 Hz) and calcium dependence (0.5-2.0 mM) of the effects of the nicotinic antagonist tubocurarine (0.2 microM) on acetylcholine (ACh) liberation from motor nerve terminals has been examined using binomial analysis of quantal transmitter release. 2. At an extracellular calcium ion concentration ([Ca2+]o) of 2.0 mM, tubocurarine produced a decrease in the endplate current (EPC) quantal content of approximately 30% at high frequencies of motor nerve stimulation (50-150 Hz). In contrast, at low frequencies of stimulation (0.5-1.0 Hz), tubocurarine enhanced the EPC quantal content by approximately 20%. 3. The enhancement of EPC quantal content produced by tubocurarine at low frequencies of motor nerve stimulation was [Ca2+]o dependent, being abolished when [Ca2+]o was lowered from 2.0 to 0.5 mM. In contrast, the decrease in quantal content produced by tubocurarine at high frequencies of motor nerve stimulation was independent of [Ca2+]o, being approximately 30% at all calcium ion concentrations studied. 4. In direct contrast to tubocurarine, the nicotinic antagonist vecuronium (1.0 microM) produced no increase in EPC quantal content at low frequencies of nerve stimulation. However, at high frequencies of nerve stimulation it decreased EPC quantal content to a similar extent to 0.2 microM tubocurarine. The frequency-dependent decrease in EPC quantal content produced by 1.0 microM vecuronium in 2.0 mM [Ca2+]o was very similar to that seen with 0.2 microM tubocurarine in 0.5 mM [Ca2+]o. 5. Binomial analysis revealed that all the changes in EPC quantal content associated with both nicotinic antagonists were due to changes in the size of the pool of quanta in the nerve terminal available for immediate release with no effect on the probability of release of an individual quantum. 6. The results are interpreted in terms of two separately identifiable prejunctional actions of the nicotinic antagonists, both involving an action at nicotinic ACh receptors situated on the motor nerve terminal. Thus, at high frequencies of motor nerve stimulation tubocurarine and vecuronium produce a [Ca2+]o-independent decrease in ACh release, probably through an inhibitory action on a positive-feedback prejunctional nicotinic autoreceptor closely related to the muscle-type nicotinic ACh autoreceptor. However, at low frequencies of motor nerve stimulation we suggest that tubocurarine, but not vecuronium, produces a [Ca2+]o-dependent increase in ACh release through an action at a negative-feedback prejunctional neuronal-type nicotinic ACh autoreceptor.

[Quantitative study of diabetic retinopathy by computerized image analysis]

Composite fluorescein angiographic pictures of 66 eyes with diabetic retinopathy and nonperfusion areas were studied by computerized image analysis, and the ratio of the nonperfusion area to the disc area was calculated. There were 49 eyes with neovascularization (NV), in which the mean ratio +/- standard error was 46.33 +/- 7.01 (8.15 to 298.26), and the corresponding value in the other 17 eyes without NV was 6.90 +/- 1.31 (2.20 to 21.37), the difference being very significant. When the ratios were under 10, from 10 to 30, or over 30, the percentages of eyes manifesting NV were 13.3%, 81.8% and 100% respectively. In the 49 eyes with NV, the majority of the total 267 neovascular clusters were distributed 4-6 DD away from the optic disc, which itself was involved only in 18 eyes.

West Nile virus infection induces susceptibility of in vitro outgrown murine blastocysts to specific lysis by paternally directed allo-immune and virus-immune cytotoxic T cells

Day 3 post-coitum BALB/c and (BALB/c x CBA/H)F1 blastocysts were isolated and hatched in replicate wells. Some were treated with interferon-gamma (IFN-gamma). Whilst others were infected with West Nile Virus (WNV) at 100 plaque-forming units per cell, for 18 h. Controls were mock-treated. Gamma-irradiated (2000 rads) CBA/H, (paternal) WNV-specific and allo(CBA/H)-specific cytotoxic T (Tc) cells were then added to replicates of infected, mock-infected or IFN-gamma-treated cultures for 20 h. [3H]Thymidine was then added for a further 8 h. [3H]Thymidine incorporation was inhibited by 40-50% in WNV-infected cultures exposed to WNV-paternal-specific Tc cells and by 30-40% in WNV-infected cultures exposed to allo-paternal-specific Tc cells compared to similarly exposed, uninfected, or unexposed, WNV-infected, or unexposed, uninfected cultures. No significant differences in [3H]thymidine incorporation were found between these controls and IFN-gamma-treated cultures exposed to allo-paternal-specific Tc cells or IFN-gamma-treated cultures not exposed to Tc cells. Parallel exposure of L929 fibroblasts to the same Tc cells irradiated with 500-8000 rads in doubling doses, showed that irradiation did not alter the efficacy or specificity of the Tc cells. Relevance to maternal anti-viral immune responses during implantation is discussed.

[Effect of gossypol on the proliferation of rat prostate cells studies in vivo and in vitro]

The effect of gossypol on prostate cells of rat was studied both in vitro and in vivo. For in vivo study, mature male Sprague Dawley rats were given gossypol orally, 5 mg/day, 5 times a week for one month. Then the prostates were examined histologically. By adding gossypol to the culture system directly, NbE-1 cells were used in vitro study. Several parameters, including histological structure, cell growth, DNA synthesis and mitotic cycle of cells were measured by different methods. The prostate size and weight in experimental rats decreased and significant differences between acini in controls and gossypol treated animals were noted. Acini of control prostate were full of protruding folds constituted by columnar epithelial cells, whereas, the most of the acini in treated animals were composing of cubic or square epithelial cells and epithelial folds were rarely seen. Thus, acini with normal appearance were about 14% less than that in controls. In the in vitro experiments, both cell proliferation and DNA synthesis decreased from 0 to 80% and from 0 to 90% respectively, when the concentrations of gossypol were increased from 0 to 20 micrograms/ml. It seems that 10 micrograms/ml of gossypol could cause the most significant inhibition in these two cellular functions. The cell mitotic assay showed that in treated groups, the cell number of S phase was decreased from 43 to 31%, this fact indicated that the inhibition on cell proliferation caused by gossypol might be due to preventing cells to enter S phase. Besides, inhibition effect on the proliferation of prostatic epithelial cells was dosage dependent and related to the duration of treatment.

RELATIVE PRE- AND POSTJUNCTIONAL EFFECTS OF A NEW VECURONIUM ANALOGUE, ORG 9426, AT THE RAT NEUROMUSCULAR JUNCTION

We have studied the relative pre- and postjunctional neuromuscular blocking effects of Org 9426 in the isolated rat hemidiaphragm muscle using twitch tension and electrophysiological recording techniques. Postjunctional effects were assessed from decreases in twitch height and from end-plate current amplitude and time constant of decay. Prejunctional effects were assessed from the fade of tetanic twitch tension and end-plate current amplitude rundown. There were no significant differences between the relative pre- and postjunctional effects of Org 9426 and those of previously studied steroidal neuromuscular blocking compounds. It is concluded, therefore, that the rapid onset and short duration of Org 9426 seen in vivo is not a consequence of a strong prejunctional, relative to postjunctional, blocking effect of the compound.

[Influence of experimental varicocele on the junctions of seminiferous epithelium]

Experimental varicoceles were created in adult male Wistar rats by partially occluding the left renal vein. The affect of the varicocele on ipsilateral testis was studied at intervals over 15 weeks via ultrathin sections and freeze-etching replica technique examined under electron microscope. Observations showed that varicocele resulted in injuries of Sertoli-Sertoli cell and Sertoli cell-spermatid junctional complexes. Abnormal changes of Sertoli cell-spermatid junctional complexes might lead to spermiogenic arrest and spermatids slough, while those of Sertoli-Sertoli cell junctional complexes to dysfunction of barrier and abnormal alteration of microenvironment of seminiferous tubule. Probably, this is one of the reasons that the fertility was not improved in some patients even after high level ligation of the internal spermatic vein.

[Changes in platelet aggregation, TXB2 and 6-keto-PGF1 alpha in surgical shock]

Platelet aggregation rate (PAR), plasma concentration of TXB2 and 6-Keto-PGF1 alpha were measured in 26 patients with shock (hypovolumic shock 10 and septic shock 16) and 10 controls. PAR, plasma TXB2 and 6-Keto-PGF1 alpha were increased during shock, with TXB2 increased more significantly than 6-Keto-PGF1 alpha, accordingly the TXB2/6-Keto-PGF1 alpha ratio were raised during shock, especially in the septic cases. PAR, plasma TXB2 and 6-Keto-PGF1 alpha will decrease while shock become subsiding, and elevate while shock become irreversible. As a rule, the change of PAR is parallel with the concentration of plasma TXB2. The speed of platelet aggregation and plasma TXB2 concentration were higher in eleven mortal cases.

Electron microscopic observations of the effects of gossypol on the human endometrium

Gossypol treatment of endometriosis and uterine myomas in 15 cases was started with a daily dose of 20 mg of gossypol-acetic acid twice a day for 20 days as a loading dose, followed by 40 mg (20 mg twice weekly). A maintenance dose of 20 mg was given weekly. The total course of treatment lasted about 6 months. Light and electron microscopic examination of the endometrium was carried out before treatment and 2, 3, 4, and 6 months after gossypol treatment. After gossypol treatment three different characteristics of the endometrium were noted: (1) irregular secretory activity, (2) proliferative activity, and (3) atrophy. On electron microscopic examination it was shown that there were important changes of the organelles, indicating suppressed secretory activity. Based on the above results, the nature and significance of the ultrastructural changes of the endometrium induced by gossypol were analyzed and the possibility of developing a new field of research in female contraception with gossypol was considered.