Intermittent smokers: a descriptive analysis of persons who have never smoked daily

OBJECTIVES

This study assessed the prevalence of and demographic variables associated with lifetime never-daily smoking in the United States.

METHODS

Descriptive demographic data and logistic regression analyses were used to examine associations with never-daily smoking.

RESULTS

Lifetime never-daily smokers constituted a significant minority of non-White smokers. There was a strong association between never-daily smoking and college education among young adults, particularly men. Although never-daily smoking was associated with initiation behavior among young smokers, it also represented a persistent pattern for some smokers, particularly non-Whites and Hispanics.

CONCLUSIONS

The demographic distribution of never-daily smoking may have implications for developing culturally appropriate smoking prevention and cessation strategies.

[An experimental observation of repair after transection of cauda equina fibers in cat]

OBJECTIVE

To explore the regeneration characteristics after cauda equina transection.

METHODS

Fibrin glue was chosen to repair transected left L6,7 roots in cat, and right roots in situ of the transected ends were served as the control. The characteristics of regeneration were observed by immunohistocytochemistry and morphometric analysis.

RESULTS

Regeneration was found not only in site of anastomosis, but also in corresponding spinal segments and DRGs. Sensory and motor evoked potentials (SEP and MEP) performed before and after transection and before taking specimen revealed the course of functional recovery on severed and regenerated nerve roots. The regeneration of moter roots was better than that of sensory roots, and they were mainly blocked at the site of central-peripheral transition zone.

CONCLUSIONS

The method of adhesion by fibrin glue can replace traditional suture, and it is superior to suture.

Study on the relationship between cytogenetics and phenotypic effect in Turner's syndrome

The cytogenetics and clinical stigmata in 5 cases of Turner's syndrome were studied. Three of them were non-mosaic 1(Xq) and two with partial monosome of a X chromosome short are (Xp21), whose DNA replication patterns of inactive X chromosome were analyzed by RBG technique. Results showed that differences between the replication patterns in cases of X chromosome deletion (Xp21) and normal females existed; that the behavior of abnormal X expressed nonrandom inactivation. It was suggested that the phenotype may be closely related with both X chromosome replication pattern and its inactivation behavior, which might be useful in genetic counselling.

Calcium channels mediate angiotensin II-induced drinking behaviour and c-fos expression in the brain

It is widely accepted that calcium ions are critically important in both short- and/or long-lasting responses of neurons to a stimulus. We have shown previously that NMDA receptors play a role in dipsogenic responses and c-fos expression induced by intracerebroventricular (i.c.v.) infusion of angiotensin II (Ang II). Since NMDA receptors are known to be linked to receptor-operated calcium channels, this study determined whether voltage dependent calcium channels are also involved in Ang II-induced behavioural (drinking) and endocrine responses as well as c-fos expression. The antidipsogenic actions of three L-type calcium channel antagonists, nifedipine, diltiazem and verapamil on Ang II-induced drinking behaviour were studied. These bind to the dihydropyridine, phenylalkylamine and benzothiazepine sites respectively. Rats (Lister-hooded) pre-treated i.c.v. with either 25 or 100 microg nifedipine, followed by 25 pmol Ang II, drank significantly less water than controls during the first 15 min after infusion. However, rats pre-treated with i.c.v. 100 microg diltiazem or verapamil showed no change in Ang II-induced drinking behaviour. The antidipsogenic actions of N- and P-type calcium channel antagonists omega-conotoxin GVIA and omega-conotoxin MVIIC were also evaluated. Rats pre-treated with 5 pmol or 20 pmol omega-conotoxin GVIA did show a slight but not significant suppression of water intake, particularly after the higher dose. Rats pre-treated with omega-conotoxin MVIIC drank almost the same amount of water as those pre-treated with saline. Nifedipine was found to suppress both Ang II-induced corticosterone release and c-fos expression in the following areas: organum vasculosum of the lamina terminalis (OVLT), median preoptic nucleus (MNPO), hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The results described in this paper provide evidence that calcium channels play important roles in the Ang II-induced behavioural and endocrine responses, and in the expression of the immediate-early gene c-fos. This suggests that an L-type calcium channel may participate both short- and longer-term neuronal actions of Ang II.

Postnatal development of vascular resistance of the rabbit isolated perfused kidney: modulation by nitric oxide and angiotensin II

Studies were performed on isolated perfused kidneys (IPK) from postnatal developing rabbits to ask 1) whether the high renal vascular resistance (RVR) at birth involves intrinsic renal mechanisms, 2) whether nitric oxide (NO) release is involved in the modulation of renal vascular tone, and 3) whether NO modulates exogenous angiotensin II (AII)-induced vasoconstrictions. Kidneys isolated from 1-wk-old (during nephrogenesis), 3-wk-old (after nephrogenesis), and 6-wk-old rabbits were perfused in the presence of 10(-5) M indomethacin. RVR decreased with age from 12.7 +/- 0.6 at 1 wk to 10.1 +/- 0.5 mm Hg min g mL-1 at 6 wk. N omega-Nitro-L-arginine methyl ester (L-NAME, 10(-4) M) comparably increased RVR by about 30% at 1, 3, and 6 wk. The vasoconstrictions induced by 10(-8) M AII increased basal pressure from 28% at 1 wk to 78% at 6 wk and were potentiated by L-NAME by about 100%. In contrast, the vasoconstrictions induced by 10(-10) M AII decreased from 8% at 1 wk to 0% at 6 wk and were potentiated by L-NAME by about 250% at 1 and 3 wk. We conclude that during postnatal development: 1) RVR in IPK decreases in absence of AII and extrarenal influences, suggesting that high RVR at birth involves intrinsic mechanisms, 2) L-Arg/NO modulates basal tonus in developing IPK, and, 3) renal vasoconstrictor responses to exogenous AII are buffered by NO at early postnatal stages and follow an AII concentration-dependent developmental pattern. A specific neonatal high affinity AII/NO interaction disappearing after nephrogenesis completion precedes a low affinity AII/NO interaction, which progressively increases toward adult ages. These findings are in favor of a specific involvement of AII-NO interactions in the control of developing renal hemodynamics.

CD4+ T cells reactivated with superantigen are both more sensitive to FasL-mediated killing and express a higher level of FasL

Naive CD4(+) T cells proliferate strongly in response to superantigens such as staphylococcal enterotoxin B (SEB). When these cells are rested and challenged a second time, they undergo activation-induced cell death (AICD). Fas/FasL interactions have been shown to mediate AICD, even though the level of Fas expression in the 2 degrees SEB responder populations is no higher than in the 1 degrees cultures. To determine whether the dissimilarity between the 1 degrees and 2 degrees cultures could be attributed to differences in FasL cytotoxic activity or in the sensitivity of the Fas apoptosis signaling pathway, we compared these parameters during the 1 degrees and 2 degrees responses of lpr and gld CD4+ T cells (which do not undergo AICD due to a lack of Fas and an inactive FasL, respectively) so that each parameter could be evaluated independently. The results demonstrate that 2 degrees responders both express a higher level of functional FasL and are more sensitive to FasL-mediated killing. These findings account for the differences between the 1 degrees and 2 degrees responses of CD4+ T cells to superantigen. In addition, we found that the apparent level of FasL-mediated cytotoxic activity in the 2 degrees lpr CD4+ T cell population is much higher than that of wild-type cells, suggesting that deficient Fas expression leads to inordinately high levels of FasL expression or subsaturation of FasL binding sites.

Neural networks and blood cell identification

The objective of this project is to propose a method of identifying cells found in human blood and to classify them based upon their morphological features using neural networks. The project focuses on three major blood cell types, namely, erythrocytes, leukocytes and platelets. The data are collected using peripheral blood smears from clinical patients. The image acquisition requires 100x magnification on all the blood smears, the preprocessing involves the use of median and edge enhance filters; the feature extraction is done by performing the wavelet transform on the images. Finally classification of the blood cell types is done using ALOPEX and Back Propagation trained neural networks. The efficacy of both networks is then compared by comparing their outputs and number of iterations required to reach the final result.

[Effects of antisense oligodeoxynucleotides targeting multidrug resistance gene on resistant cell line K562/ AO2]

OBJECTIVE

To investigate the reversal effect of antisense oligodeoxynucleotide on human multidrug-resistant leukemic cell line K562/AO2.

METHODS

Antisense oligodeoxynucleotides (AOD) targeting-6 approximately 9 sites of exon 2 in human multidrug resistance gene(mdr-1), one of which is sequence-strict-complied and linked with polyethyleneglycol (PEG) at 5' end (AP, 15 mer), the other lacks nucleotide complied site-1 (AP', 14mer), were synthesized. AP, AP' and verapamil were simultaneously added to human mdr-1-mRNA positive leukemia cell line K562/AO2 and, mdr-1-mRNA and p170 were detected. AS' and AP'were labelled by FITC and designated as ASF' and APF', respectively. In addition, the intracellular concentration of them was detected by FACS.

RESULTS

AP' significantly enhanced the sensitivity of K562/AO2 to DOX, down-regulated the expression of mdr-1 and MRP-mRNA and p170, elevated the intracellular concentration of the two AOD, while AP had no effect. The uptake of APF' was significantly higher than that of ASF' in K562/AO2, and the fluorescence was observed in the plasma and nuclear of K562/AO2 cells.

CONCLUSION

(AOD targeting mdr-1 promoted the drug sensitivity of drug-resistant tumor cells. 2 AOD had no cytotoxicity to tumor cells. 5 Low molecule PEG enhanced significantly the uptake of AOD by tumor cells.

Angiotensin II interacts with nitric oxide-cyclic GMP pathway in the central control of drinking behaviour: mapping with c-fos and NADPH-diaphorase

Recognition of the role of nitric oxide in cell-to-cell communication has changed the concept of traditional neurotransmission. We have shown previously that N-methyl-D-aspartate receptors mediate dipsogenic responses and c-Fos expression induced by intracerebroventricular infusion of angiotensin II. Since these receptors are known to be linked to the nitric oxide-cyclic GMP pathway, the present study explores the contribution of this path to the behavioural and cellular effects of intracerebroventricular angiotensin II by using behavioural testing, NADPH-diaphorase histochemistry and immunocytochemical staining for the immediate-early gene, c-fos. N(G)-nitro-L-arginine methyl ester (125 and 250 microg, intracerebroventricular), an inhibitor of nitric oxide synthase, and Methylene Blue (100 microg), an inhibitor of guanylate cyclase activation, antagonized water intake induced by intracerebroventricular injection of 25 pmol angiotensin II. The effects of N(G)-nitro-L-arginine methyl ester were reversed by co-injection of L-arginine, the substrate for nitric oxide synthase. However, N(G)-nitro-L-arginine methyl ester did not alter the pattern of angiotensin II-induced c-fos expression in the organum vasculosum of the lamina terminalis, median preoptic nucleus, hypothalamic paraventricular nucleus and supraoptic nucleus. Double staining with NADPH-diaphorase histochemistry and c-Fos immunocytochemistry showed that neurons staining for both were localized to the anterior third ventricle. However, only 19-25% of the c-Fos-positive neurons expressed NADPH. There were also substantial numbers of neurons in which angiotensin II induced c-Fos that were NADPH-negative. Extensive co-distribution of NADPH-diaphorase-stained cells and those expressing c-fos in response to intracerebroventricular injection of angiotensin II, especially in the median preoptic nucleus, imply that nitric oxide might participate in the mechanism of angiotensin II-induced drinking behaviour. However, a low rate of co-localization of the two markers to individual cells suggests that angiotensin II stimulated the production of nitric oxide and c-Fos in different populations of neurons. Since our previous results showed that glutamate blockade, but not nitric oxide synthase inhibition, suppressed angiotensin II-induced c-Fos, the experiments reported here further suggest that nitric oxide release is not an essential requirement for the expression of c-fos elicited by angiotensin II. They also provide evidence that the dipsogenic and c-Fos responses to angiotensin II are dissociated at a cellular level.

Dizocilpine maleate, an N-methyl-D-aspartate antagonist, inhibits dipsogenic responses and C-Fos expression induced by intracerebral infusion of angiotensin II

The interactions between dizocipline, an N-methyl-D-aspartate open channel antagonist, and the induction of water drinking and c-fos expression by intracerebroventricular (i.c.v.) infusion of angiotensin II have been studied. Pretreating male rats with i.c.v. dizocilpine maleate (100 or 300 nmol) or tenocyclidine (150 nmol), both non-competitive N-methyl-D-aspartate antagonists, inhibited the subsequent dipsogenic response to i.c.v. angiotensin II (125 or 50 pmol, 5-10 min later). Dizocilpine also decreased the angiotensin II-evoked expression of c-fos in the median preoptic nucleus, supraoptic nucleus and the medial (parvicellular) and lateral (magnocellular) parts of the hypothalamic paraventricular nucleus, as well as in the nucleus of the solitary tract and the lateral parabrachial nucleus. Double staining showed that suppression of c-fos expression occurred in N-methyl-D-aspartate R1 receptor containing neurons in the hypothalamus. Pretreating rats with any of three competitive glutamate antagonists (2-amino-5-phosphonopentanoic acid, 60 or 160 nmol; gamma-D-glutamylglyine, 400 nmol; (DL-3/(R)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid, 0.1 nmol) or the glycine site antagonist 7-chlorokynurenic acid had no effects on angiotensin II-induced drinking. Neither did pretreating rats with the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid antagonist 6-cyano-7-nitroquinoxaline-2,3-dione [two infusions, 30 min (240 nmol) and 5 min (160 nmol) before angiotensin II]. To eliminate cross-reactivity of dizocilpine with nicotinic receptors, animals were pretreated with nicotinic acetylcholine blocker mecamylamine (250 nmol, i.c.v.), but this had no effect on angiotensin II-dependent drinking or c-fos expression. These results suggest that an N-methyl-D-aspartate-type glutamate receptor is implicated in the dipsogenic and cellular responses to i.c.v. angiotensin II, and point to the existence of a novel set of interactions between excitatory amino acids and this neuropeptide.

[Early diagnosis of pancreatic infection by CT-guided needle-aspiration]

35 CT-guided percutaneous needle-aspirations with bacteriological sampling were performed in 21 patients suspected of pancreatic infection out of 122 patients with severe acute pancreatitis. Thirteen patients were found by smear and staining culture to have pancreatic infection, and diagnosis was confirmed by surgery. The pathogens found were E coli, pseudomonas and fungi. All pancreatic infections were in grade D or E according to the grading system of Balthazar. Seven of 8 patients with sterile aspirates were cured by nonsurgical therapy. We conclude that CT-guided aspiration is a safe, accurate method for identifying infection of the pancreas at the early stage of severe acute pancreatitis.

[Antagonistic effect of calcitonin gene related peptide on arrhythmia in rats]

Premature ventricular contraction (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were developed by endothelin-1 (ET-1) injected into the coronary ostia at the dose of 900 pmol/kg in anesthetized rats. No arrhythmia was elicited but blood pressure fell temporarily by calcitonin gene related peptide (CGRP), the injection into the coronary ostia. After pretreatment with CGRP incidence and severity of arrhythmia decreased at the same ET-1 dose. Arrhythmia score in CGRP 1200 pmol/kg + ET-1 group was lower than that in ET-1 group (P < 0.01). The results revealed that antiarrhythmic effect of CGRP may be partially brought about by its antagonistic effect against ET-1 induced arrhythmia.

[Effect of stimulation of the superior and inferior spermatic nerves on testosterone secretion and testicular blood flow]

The effects of testicular nerves on regulation of androgen secretion were examined by determining testicular blood flow and testosterone in testicular vein at 10 minute interval before, during, and 10, 20, 30 min after stimulation (Pre. Est. Post. 10. Post 20. Post 30 respectively) of superior or inferior spermatic nerves (SSN or ISN) with 25 Hz high (50-70 V) or low (20-25 V) currency. Blood flow and blood samples of the testicular vein were obtained through a cannula in left side under anesthesia of pentobarbital sodium. Under the stimulation of SSN, blood flow in testicular vein decreased by 44.87% in Est with high voltage whereas with low voltage no change appeared in Est but decreased by 27.25% in the period of poststimulation; although with high voltage of stimulation of SSN a transient fall of testosterone (42.01%) was observed in Est, 2.5 times increase of testosterone occurred in the period of poststimulation, meanwhile the testosterone rose by 87.33% in Est of SSN stimulation with low voltage and was further elevated up to 4 times in post-stimulated period. Unlike the stimulation of SSN, there was no influence of stimulating ISN on testosterone with either high or low voltage whereas there was significant increase of blood flow (12.31%) in the period of Est with high voltage then it tended to decrease after stimulation. The present work supported the hypothesis that testicular nerves involve in regulation of androgen secretion in testis and provided a strong evidence for further investigation of nervous regulation of endocrine in testis.

NOTE

Atomic force microscopy was used to investigate the mixed monolayer of FC- and HC-amphiphiles. Clear topographic images showing domain structure of the mixed monolayer and the data of the domain size have been provided. It is revealed that in the mixed monolayer the sodium octadecanesulfonate molecules construct the hexagonal domain dispersing in the continuous two-dimensional phase of perfluorononanoic acid. These results strongly support that, due to the mutual-phobicity between fluorocarbon chain and hydrocarbon chain, there exists phase separation in the mixed monolayer of fluorocarbon and hydrocarbon amphiphiles, albeit the pi-A curves would obey the simple additive rule.

[Teniposide, cyclophosphamide and dexamethasone combination treatment for stage III multiple myeloma: a report of 21 cases]

OBJECTIVE

To evaluate the efficacy and toxicites of combination chemotherapy of teniposide, cyclophosphamide, and dexamethasone (VCD) for stage III multiple myeloma (MM).

METHODS

Twenty-one patients with stage III MM were treated with VCD regimen. Among 21 evaluable patients, 16 were in stage IIIA; 5 in stage IIIB. Teniposide was given 30 mg/m2 by intravenous(i.v.) infusion on days 1-3; cyclophosphamide 200 mg/m2 i.v. on day 1, 3, 5; dexamethasone 10-20 mg daily p.o. on days 1-7. The treatment was recycled every 28 days.

RESULTS

The overall response rate was 76%(16/21), including partial response 38%(8/21); improvement 38%(8/21) and failure 24%(5/21). The survival time was 3-31 months; medium survival time (MST) 13 months; MST of MM patients in stage IIIA, IIIB were 11, 12 months, respectively. The medium duration of response was 5 months; the medium cycle for initial response was 2. Among 21 cases, leukopenia and thrombocytopenia were detected respectively in 10%, 54%, 31%, 5% and 67%, 17%, 13%, 3% according to WHO grade 0, I, II, III criteria. The gastrointestinal reaction was mild. No cardiovascular, renal and hepatic toxicites were observed.

CONCLUSION

VCD regimen is an effective treatment for stage III multiple myeloma.

[The development of hematomanometer auto test instrument]

This paper introduces the development of hematomanometer auto test instrument of a news measurement standard. The hard-ware and soft-ware and the circuit structure of it are described in detail.

Lipophosphoglycan from Leishmania suppresses agonist-induced interleukin 1 beta gene expression in human monocytes via a unique promoter sequence

Leishmania are parasites that survive within macrophages by mechanism(s) not entirely known. Depression of cellular immunity and diminished production of interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha are potential ways by which the parasite survives within macrophages. We examined the mechanism(s) by which lipophosphoglycan (LPG), a major glycolipid of Leishmania, perturbs cytokine gene expression. LPG treatment of THP-1 monocytes suppressed endotoxin induction of IL-1 beta steady-state mRNA by greater than 90%, while having no effect on the expression of a control gene. The addition of LPG 2 h before or 2 h after endotoxin challenge significantly suppressed steady-state IL-1 beta mRNA by 90% and 70%, respectively. LPG also inhibited tumor necrosis factor alpha and Staphylococcus induction of IL-1 beta gene expression. The inhibitory effect of LPG is agonist-specific because LPG did not suppress the induction of IL-1 beta mRNA by phorbol 12-myristate 13-acetate. A unique DNA sequence located within the -310 to -57 nucleotide region of the IL-1 beta promoter was found to mediate LPG's inhibitory activity. The requirement for the -310 to -57 promoter gene sequence for LPG's effect is demonstrated by the abrogation of LPG's inhibitory activity by truncation or deletion of the -310 to -57 promoter gene sequence. Furthermore, the minimal IL-1 beta promoter (positions -310 to +15) mediated LPG's inhibitory activity with dose and kinetic profiles that were similar to LPG's suppression of steady-state IL-1 beta mRNA. These findings delineated a promoter gene sequence that responds to LPG to act as a "gene silencer", a function, to our knowledge, not previously described. LPG's inhibitory activity for several mediators of inflammation and the persistence of significant inhibitory activity 2 h after endotoxin challenge suggest that LPG has therapeutic potential and may be exploited for therapy of sepsis, acute respiratory distress syndrome, and autoimmune diseases.

[Treatment of preterm labor with ritodrine]

OBJECTIVE

To investigate the treatment of preterm labor with the beta-adrenergic agonist ritodrine.

METHODS

126 women with preterm labor were randomly assigned to intravenous infusion of ritodrine or magnesium sulfate treatment. Using minimal effective dosage for inhibition of uterine activity, terminating therapy on time, and repeating the i.v. infusion if contraction restarted were the strategy for treatment.

RESULTS

Ritodrine was significantly more effective both in the treating period for suppression of contraction (2.33 +/- 0.63 hr for initiation of inhibiting uterine activity, 9.38 +/- 3.88 days of accumulative treating period) and prolongation of gestation (4.81 +/- 2.83 wks) than that of the magnesium sulfate (P < 0.001, 0.005 and 0.01 respectively), and had a term labor of 73.44%. There was no serious cardiac and pulmonary complications in the ritodrine group.

CONCLUSION

The present study has shown that ritodrine as a tocolytic agent is highly effective for the management of preterm labor and relative safe for mother and fetus.

Quinidine enhances and suppresses Kv1.2 from outside and inside the cell, respectively

We studied the effects of quinidine on two K channel clones expressed in Xenopus oocytes, Kv1.2 and Kv1.4. Quinidine had an agonist (enhancement) and a blocker (suppression) action on Kv1.2, whereas only the blocker action was seen with Kv1.4. For both, the blocker action was exerted from the intracellular side of the membrane due to quinidine binding in its protonated form to a site in the membrane electrical field. The agonist action on Kv1.2 was exerted from the extracellular side of the membrane. A quaternary analog of quinidine, Q+1C, that had a low membrane permeability allowed the agonist action to be separated from the blocker action. Experiments with Q+1C showed that the agonist action was caused by a parallel shift of the voltage dependence of Kv1.2 activation in the negative direction. There was no increase in channel conductance when channel activation reached a plateau. Q+1C had little or no effect on the rate of Kv1.2 activation, but significantly slowed Kv1.2 deactivation at voltages as negative as - 160 mV. These changes in channel gating could be largely reproduced by a simple kinetic model, assuming that the agonist action was caused by a decrease in the rate constants for transitions from the activated to the rested states. In oocytes coexpressing Kv1.2 and Kv1.4 at approximately a 1:1 ratio, the response to Q+1C was similar to that of oocytes expressing Kv1.2 alone, suggesting that heteromultimer channels of Kv1.2 and Kv1.4 subunits could respond to the agonist action of quinidine.

Structure-function analysis of Leishmania lipophosphoglycan. Distinct domains that mediate binding and inhibition of endothelial cell function

We have shown that Leishmania lipophosphoglycan (LPG) inhibits IL-1 beta gene expression in human monocytes. Here, we show that LPG can bind in a time-dependent manner and suppress endothelial cell activation, possibly via specific LPG domains. Endotoxin (10 ng/ml, 4 h) consistently caused endothelium to increase monocyte adhesion (approximately 20-fold). LPG pretreatment (2 microM, 2 h) completely blocked endotoxin-mediated monocyte adhesion. LPG did not grossly suppress endothelial functions because TNF-alpha- and IL-1 beta-mediated adhesion toward monocytes were not affected. Using four highly purified LPG fragments (namely, repeating phosphodisaccharide (PGM), phosphoglycan, phosphosaccharide core-lyso-alkyl-phosphatidylinositol (core-PI), and lyso-alkyl-phosphatidylinositol (lyso-PI)), we examined whether these fragments can independently inhibit endothelial adhesion. In contrast to that of intact LPG, neither the four LPG fragments (2 microM, 2 h) independently nor the co-addition of phosphoglycan and core-P1 fragments blocked the endotoxin-mediated adhesion to monocytes. To determine whether the fragments can reverse the effect of intact LPG, endothelial cells were first pretreated with the LPG fragments (10 microM, 15 min), followed by the addition of LPG (2 microM). All four LPG fragments fully reversed the effect of LPG. Simultaneous addition of LPG fragments and intact LPG caused only partial suppression (approximately 45%), while the addition of LPG fragments 14 min later had no reversal effect. Flow cytometry revealed that only core-P1 and lyso-P1 competitively inhibited (approximately 30%) LPG binding. Conversely, LPG competed with the binding of [3H]lyso-P1 (approximately 30%). Furthermore, mAb against the PGM reversed (approximately 70%) the effect of LPG. Thus, the lyso-P1 domain on LPG mediates binding to endothelial cells, whereas the PGM domain mediates the cell inhibitory effect.

Structure-function analysis of Leishmania lipophosphoglycan. Distinct domains that mediate binding and inhibition of endothelial cell function

We have shown that Leishmania lipophosphoglycan (LPG) inhibits IL-1 beta gene expression in human monocytes. Here, we show that LPG can bind in a time-dependent manner and suppress endothelial cell activation, possibly via specific LPG domains. Endotoxin (10 ng/ml, 4 h) consistently caused endothelium to increase monocyte adhesion (approximately 20-fold). LPG pretreatment (2 microM, 2 h) completely blocked endotoxin-mediated monocyte adhesion. LPG did not grossly suppress endothelial functions because TNF-alpha- and IL-1 beta-mediated adhesion toward monocytes were not affected. Using four highly purified LPG fragments (namely, repeating phosphodisaccharide (PGM), phosphoglycan, phosphosaccharide core-lyso-alkyl-phosphatidylinositol (core-PI), and lyso-alkyl-phosphatidylinositol (lyso-PI)), we examined whether these fragments can independently inhibit endothelial adhesion. In contrast to that of intact LPG, neither the four LPG fragments (2 microM, 2 h) independently nor the co-addition of phosphoglycan and core-P1 fragments blocked the endotoxin-mediated adhesion to monocytes. To determine whether the fragments can reverse the effect of intact LPG, endothelial cells were first pretreated with the LPG fragments (10 microM, 15 min), followed by the addition of LPG (2 microM). All four LPG fragments fully reversed the effect of LPG. Simultaneous addition of LPG fragments and intact LPG caused only partial suppression (approximately 45%), while the addition of LPG fragments 14 min later had no reversal effect. Flow cytometry revealed that only core-P1 and lyso-P1 competitively inhibited (approximately 30%) LPG binding. Conversely, LPG competed with the binding of [3H]lyso-P1 (approximately 30%). Furthermore, mAb against the PGM reversed (approximately 70%) the effect of LPG. Thus, the lyso-P1 domain on LPG mediates binding to endothelial cells, whereas the PGM domain mediates the cell inhibitory effect.

Central antagonism of atrial natriuretic peptides on behavioral and hormonal responses to angiotensin II: mapping with c-fos

The expression of the immediate early gene (IEG) c-fos has been used to map the antagonistic effects between atrial natriuretic peptide (ANP) and angiotensin II (Ang II). Intracerebroventricular (i.c.v.) infusions of ANP (100, 250, 1000 or 2000 pmol) did not induce detectable c-fos expression in the forebrain when compared with CSF-treated rats. Neither did C-type natriuretic peptide (CNP, 10, 100, 500 or 1000 pmol), another member of the natriuretic peptide family, which appears to be predominant in the brain. ANP was found to inhibit the water intake and corticosterone release induced by i.c.v. infusions of Ang II. However, ANP could not suppress the c-fos expression in the organum vasculosum of the lamina terminalis (OVLT), medial preoptic nucleus (MNPO), subfornical organ (SFO), supraoptic (SON) and paraventricular (PVN) nuclei of forebrain induced by the same dose of Ang II. The activation of second messenger pathways following i.c.v. infusion of Ang II may result in two different sets of effects: immediate behavioural and physiological responses (presumably through postsynpatic responses in neurons sensitive to Ang II), and the delayed expression of c-fos (and other IEGs proteins) which control the expression of late response genes. Whilst there is considerable, and growing evidence that IEGs mark the pattern of neuronal activity induced by peptides such as Ang II, the precise role played by these gene products is still problematical and awaits clarification by further experiments.

L-arginine decreases infarct size in rats exposed to environmental tobacco smoke

This study examined the effects of L-arginine on myocardial infarct size, hemodynamics, and vascular reactivity in environmental tobacco smoke (ETS)-exposed and non-ETS-exposed rats. We previously demonstrated that exposure to ETS increased myocardial infarct size in a rat model of ischemia and reperfusion. If reduced reperfusion was caused by endothelial cell damage and increased vascular tone, L-arginine (ARG) would increase nitric oxide and better protect the heart. Sixty Sprague-Dawley rats were randomly divided into four groups: ETS or non-ETS (control) with and without ARG (2.25% ARG in drinking water). The ETS groups were exposed to passive smoking (4 Marlboro cigarettes per 15 minutes, 6 hours a day) for 6 weeks. After 6 weeks, all rats were subjected to 35 minutes of left coronary artery occlusion and 120 minutes of reperfusion, with hemodynamic monitoring. Aortic rings were harvested to evaluate vascular reactivity. Average air nicotine, carbon monoxide, and total particulate concentrations were 1304 +/- 215 microgram/m3, 78 +/- 2.0 ppm, and 31 +/- .7 mg/m3 (mean +/- SEM) for the ETS-exposed rats. Infarct size (infarct mass/risk area x 100%) increased with ETS exposure but decreased significantly in the ETS-with-ARG group compared with the ETS-without-ARG group (42% +/- 6% vs 64% +/- 6%, mean +/- SEM; p = 0.043). The benefit of ARG was dependent on ETS exposure (ETS x ARG interaction, p = 0.043). There were no significant differences between groups in heart rate, systolic pressure, and rate-pressure product. ARG significantly decreased myocardial infarct size after ischemia and reperfusion in ETS-exposed rats. Neither the adverse effects of ETS on infarct size nor the blockage of this effect by ARG appears to be the result of ETS-induced alterations in hemodynamics.