CD4 counts of normal and HIV-infected south Indian adults: do we need a new staging system?

BACKGROUND

The normal range of CD4 lymphocyte count varies among different ethnic groups. In populations with CD4 counts inherently lower than in the West, the Centers for Disease Control and Prevention (CDC) classification system of HIV-infected individuals may not be appropriate. No such criterion is currently available for ethnic south Indian HIV-infected individuals. We undertook this study to assess the applicability of the western case definition to south Indian HIV patients.

METHODS

The CD4 counts of 104 normal and 79 HIV-infected south Indian adults were estimated by flowcytometry. The mean CD4 counts were estimated and compared between CDC groups A, B and C and controls. Receiver operator characteristics curves were generated to determine the cut-off that correlated best with clinical staging for this population.

RESULTS

The mean CD4 and CD8 cell counts/microl and the CD4/CD8 ratio of the control group were 799.0, 919.6 and 0.94, respectively. For CDC groups A, B and C, the mean CD4 counts/microl were 454.4, 254.4 and 168; mean CD8 counts/microl were 1156, 1070.9 and 1191.3; and mean CD4/CD8 ratios were 0.44, 0.25 and 0.15, respectively.

CONCLUSION

The mean CD4 count among normal south Indians is significantly lower than that in the western population and parallels that of the Chinese. When categorized based on the CDC classification system, the mean CD4 count of HIV-infected individuals was lower. Categories of CD4 counts > 300, 81-300 and < or =80 cells/microl and CD4% > 14, 7-14 and < or = 6 correlate better with disease progression among HIV-infected individuals. A longitudinal study is required before guidelines for the Indian population can be devised.

Molecular mechanisms of IL-2 gene regulation following costimulation through LFA-1

The integrin LFA-1 serves as an accessory molecule in T cell activation. In addition to its well-known role as an adhesion molecule, LFA-1 can contribute to T cell activation and up-regulation of IL-2 gene expression. However, the specific mechanisms by which LFA-1 influences T cell activation have not been elucidated. Therefore, we examined the impact of LFA-1:ICAM-1 interactions on transcriptional and posttranscriptional IL-2 gene regulation, using a costimulation-negative cell line transfected with MHC class II alone, or in combination with ICAM-1 or B7-1. IL-2 transcription was assessed utilizing transgenic mice expressing an IL-2 promoter luciferase reporter construct crossed to DO11.10 TCR-transgenic mice, and IL-2 mRNA stability was evaluated by real-time RT-PCR. Comparison of naive and previously activated T cells demonstrates a dramatic increase in IL-2-luciferase transcription in activated T cells that can, in part, be attributed to downstream signaling events. Costimulation through LFA-1 enhances transcription of the transgenic reporter construct across a wide Ag dose range, but does not affect IL-2 mRNA stability. In contrast, CD28 costimulation is clearly mediated through up-regulation of IL-2 transcription and through enhancement of mRNA stability. These results indicate that the primary pathway whereby engagement of LFA-1 through its ligand ICAM-1 up-regulates IL-2 gene expression is through enhanced IL-2 transcription, in the absence of any effect on IL-2 mRNA stabilization.

Managing awareness: negotiating and coping with a terminal prognosis

This study examined the way in which a terminal cancer prognosis was negotiated by patients and their lay carers, and the complexities involved in managing a context of awareness. Individual semi-structured interviews were undertaken with 16 patients and 14 lay carers. These were transcribed verbatim and analysed using a grounded theory approach. The process started with being given bad news, when the concept of life was no longer open-ended. The need to maintain hope influenced the amount of information sought by patients and their families and was an important strategy in helping patients cope with the knowledge of their disease. Levels of awareness appeared to be influenced less by setting, than by the way the prognosis was managed within individual families. Difficulties facing patients and carers in knowing how to communicate with each other within a context of open awareness suggest that they need help in learning how to do this. Achieving an environment to enable this requires private space and staff skilled in enabling and facilitating the complexities of communication between patients and their carers.

A vitamin D3 analog induces a G1-phase arrest in CaCo-2 cells by inhibiting cdk2 and cdk6: roles of cyclin E, p21Waf1, and p27Kip1

Previous studies by our laboratory have shown that a noncalcemic fluorinated analog of 1alpha,25-dihydroxyvitamin D3, 1alpha,25-dihydroxy-16-ene-23-yne-26,27-hexafluorocholcal ciferol (F6-D3), significantly reduced the frequency of colonic adenomas and completely abolished the development of colonic adenocarcinomas in rats treated with azoxymethane. The mechanisms involved in this analog's chemopreventive actions, however, remain unclear. In the present study, we now show that although both 1alpha,25-dihydroxyvitamin D3 and F6-D3 inhibited the proliferation of CaCo-2 cells, a human colonic adenocarcinoma cell line, by increasing their doubling times, only F6-D3 caused an arrest of these cells in the G1 phase of their cell cycle. This arrest was accompanied by an increase in the expression of the cyclin-dependent kinase (cdk) inhibitor proteins, p2Waf1 and p27Kip1, which served to decrease the activity of cyclin-dependent kinase 2 and cyclin-dependent kinase 6, whereas the expression and phosphorylation of pRB were unchanged. In contrast to the increased expression of these cdk inhibitors, the expression of cyclin E was decreased, which further inhibited the activity of cyclin-dependent kinase 2. Collectively, the inhibition of these cyclin-dependent kinases served to arrest the CaCo-2 cells, independent of changes in pRB. Furthermore, antibody neutralization studies suggest that transforming growth factor-beta may mediate the coassociations between cdk2 and p27Kip1 and cyclin E induced by F6-D3. These data indicate that cell cycle arrest may, at least in part, underlie the chemopreventive actions of F6-D3 observed in the azoxymethane model of colon cancer. Furthermore, if the antiproliferative action observed in CaCo-2 cells also occurs in human colonic epithelium, F6-D3 may have chemopreventive potential against human colon cancer, as well.

Hormone replacement therapy and 24-hour blood pressure profile of postmenopausal women

Menopause is associated with an increase in blood pressure (BP) and a decrease in physiologic nocturnal BP fall. These factors may play a role in the increased risk of cardiovascular events after menopause. Some studies indicate that transdermal estrogen replacement therapy may help restore the 24-h BP profile, but data on the effect of oral conjugated estrogens are lacking. We compared 24-h ambulatory BP profiles of 42 postmenopausal women not receiving hormone replacement therapy (HRT) and 20 women receiving HRT. HRT was associated with a significant increase in the proportion of dippers (50% in women not receiving HRT and 80% in women receiving HRT, P = .048). Increase in nocturnal dipping may account, in part, for the beneficial cardiovascular effects of HRT.

From psycho-social theory to sustainable classroom practice: developing a research-based teacher-delivered sex education programme

This paper describes the development of a theoretically based sex education programme currently undergoing a randomized controlled trial in the UK. It considers some of the practical difficulties involved in translating research-based conclusions into acceptable, replicable and potentially effective classroom lessons. The discussion acknowledges that the implications of social psychological research and the requirements of rigorous evaluation may conflict with accepted principles inherent in current sex education practice. It also emphasizes that theoretical ideas must be carefully embedded in lessons which are informed by an awareness of classroom culture, and the needs and skills of teachers. For example, the use of same-sex student groups to reflect on the gendered construction of sexuality may be problematic. Materials must be tailored to recipients' circumstances, which may require substituting for limited experience with the use of detailed scripts and scenarios. Furthermore, role-play techniques for sexual negotiation that work elsewhere may not be effective in the UK. The use of trigger video sessions and other techniques are recommended. Finally, the problems involved in promoting condom-related skills are discussed. The paper concludes that, if an intervention is to be sustainable beyond the research stage, it must be designed to overcome such problems while remaining theoretically informed.

Clinical benefits of oral irrigation for periodontitis are related to reduction of pro-inflammatory cytokine levels and plaque

BACKGROUND

Although a growing body of evidence indicates that oral irrigation with water has therapeutic benefits in periodontitis, the mechanisms of action have not been elucidated. The aims of this study were: (1) to analyze the effects of oral irrigation (Water Pik Oral Irrigator) on the clinical signs of adult periodontitis (AP) and on the levels of interleukin-1 beta (IL-beta), prostaglandin-E2 (PGE2), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) in GCF, and (2) to analyze the influence of the periodontitis-related IL-1 genotype (IL-1GT) on these variables.

METHOD

A single-center, blinded study in otherwise healthy humans (n= 52) with localized mild to moderate AP was carried out, using the following groups: group A (n= 12), no oral hygiene for 14 days; group B (n=20), routine oral hygiene (ROH) for 14 days; group C (n=20), supra-gingival oral irrigation plus ROH for 14 days. Group A patients were crossed-over to group C for 14 days (=day 28) after a professional prophylaxis. Group assignment was randomized by a coin toss, with the exception of group A subjects, who were self-selected as per recommendations of the internal review board for human subjects. GCF was sampled from 3 study teeth per patient and analyzed for IL-1 beta, PGE2, IL-10 and IFN gamma by ELISA on days 0, 7, 14 and 28. Probing pocket depths (PPD), clinical attachment levels (CAL), bleeding on probing (BOP), gingival index (GI) and plaque index (PI) were measured by a calibrated examiner (TWS) on days 0, 14 and 28. Analysis of covariance was performed using SAS 6.12 and Proc Mixed with group and IL-1GT as the factors and the baseline levels as the covariate, with output being least squares means and least significant difference (LSD). Significant differences were declared if the p-value for the F-statistic was < or =0.05.

RESULTS

Oral irrigation plus ROH resulted in a significant reduction in PPD, BOP, GI and PI, as well as IL-beta levels by 7 days and PGE2 levels by 14 days, relative to ROH or no oral hygiene. Interestingly, decreased IL-1 beta levels in patients using oral irrigation plus ROH was accompanied by a trend for increased levels of the "anti-inflammatory" cytokine IL-10. ROH reduced GI, BOP and PI, and PGE2 levels by 14 days, but had no effect on IL-1 beta or IL-10 levels relative to no oral hygiene. The effects of no oral hygiene were reversed by a prophy followed by oral irrigation plus ROH for 14 days. No clinical differences were evident between IL-1 GT (+) patients (n= 1) and GT (-) patients (n=40), but the former had significantly elevated levels of GCF IL-10 and borderline increases in IL-1 beta (p=0.07).

CONCLUSIONS

Oral irrigation with water for 14 days had an improved therapeutic benefit for AP over that of routine oral hygiene alone and this improvement was accompanied by a down-modulation of the pro-inflammatory cytokine profile in GCF.

Streptozotocin dose-response curve in tilapia, a glucose-responsive teleost fish

Streptozotocin (STZ) causes beta cell necrosis and insulin-dependent diabetes in many species. The specificity of this beta cell toxin relates to its structure as an alkylating agent with an attached glucose moiety. STZ uptake by rodent beta cells appears to be via the GLUT-2 glucose transporter. Teleost fish, in general, are severely glucose intolerant. The effects of STZ were examined in tilapia, a teleost fish with highly glucose-responsive islets. Fasted tilapia were given 0, 100, 150, 200, 250, 300, or 350 mg/kg STZ iv. Plasma glucose levels were followed for 72 h and the fish autopsied. Histological sections of islets were stained by immunoperoxidase for tilapia insulin. Severe hyperglycemia was seen in 20, 80, and 100% of fish receiving 250, 300, and 350 mg/kg doses; however, sections of islets showed only partial degranulation with no evidence of beta cell necrosis. Another group of fish receiving the highest dose were followed longer to determine whether beta cell necrosis and permanent hyperglycemia ensued. All fish died or were killed within 9 days because of severe hepatic failure characterized by hepatic necrosis, jaundice, and ascites; islet morphology was relatively normal suggesting, even in a glucose-sensitive species, that fish islets either do not take up STZ or are highly resistant to its "diabetogenic" effects. Tilapia may thus be a useful model to elucidate mechanisms of action of STZ. Furthermore, STZ may provide important insights into differences in glucose uptake and metabolism by mammalian and piscine beta cells.

Cognitive predictors of adherence to malaria prophylaxis regimens on return from a malarious region: a prospective study

Cases of 'imported malaria' into countries where malaria is not endemic are increasing and evidence suggests that non-use of malaria prophylaxis and lack of adherence are contributing to this increase. Non-adherence may be especially likely because chemoprophylaxis regimens require travellers to continue to take medication for 4 weeks after their return from a malarious region. This study investigated the extent to which cognition measures specified by the theory of planned behaviour and the health belief model could distinguish between those who reported greater or lesser adherence after their return. Cognitions were measured using a brief questionnaire on the day of departure from the malarious region and reports of adherence were collected between 5 and 7 weeks later. Data from two longitudinal samples of UK tourists returning from The Gambia were analysed; 106 mefloquine users and 61 chloroquine and proguanil users. Results suggested that malaria prophylaxis adherence could be improved. 22.5% of mefloquine users and 31% of chloroquine and proguanil users reported adherence for 3 weeks or less. A model based on the theory of planned behaviour explained approximately 50% of the variance in reported adherence amongst mefloquine users and 40% amongst chloroquine and proguanil users, comparing favorably with other published applications of the theory. Findings suggest that targeting key cognitions could enhance adherence on return from malarious regions. Enhancing perceived control over adherence may be important as well as emphasising susceptibility to malaria infection. Reassuring mefloquine users concerning potential side effects of the drug may also encourage adherence on return. Implications for future research are discussed.

The dependence for leukocyte function-associated antigen-1/ICAM-1 interactions in T cell activation cannot be overcome by expression of high density TCR ligand

The leukocyte-specific integrin, LFA-1, can enhance T cell activation. However, it is unclear whether the binding of LFA-1 to its ligand, ICAM-1, functions through intercellular adhesion alone, resulting in an augmentation of the TCR signal, or involves an additional LFA-1-mediated cellular signal transduction pathway. We have previously shown that naive CD4+ lymph node T cells, isolated from DO11.10 TCR transgenic mice, are activated by increasing doses of exogenous OVA peptide presented by transfectants expressing both class II and ICAM-1, but not by cells expressing class II alone. To determine whether LFA-1/ICAM-1 interactions were simply enhancing the presentation of low concentrations of specific MHC/peptide complexes generated from exogenously added peptide, we transfected cells with class II that is covalently coupled to peptide, alone or in combination with ICAM-1. These cells express 100-fold more specific class II/peptide complexes than can be loaded onto class II-positive cells at maximum concentrations of exogenous peptide. Despite this high density of TCR ligand, activation of naive CD4+ T cells still requires the coexpression of ICAM-1. LFA-1/ICAM-1 interactions are not required for effective conjugate formation and TCR engagement because presentation of class II/peptide complexes in the absence of ICAM-1 does induce up-regulation of CD25 and CD69. Thus, high numbers of engaged TCR cannot compensate for the lack of LFA-1/ICAM-1 interactions in the activation of naive CD4+ T cells.

Psychosocial correlates of heterosexual condom use: a meta-analysis

Despite increasing incidence of HIV/AIDS, there has been no systematic review of correlates of condom use among heterosexual samples. To rectify this, the present study used meta-analysis to quantify the relationship between psychosocial variables and self-reported condom use. Six hundred sixty correlations distributed across 44 variables were derived from 121 empirical studies. Variables were organized in terms of the labeling, commitment, and enactment stages of the AIDS Risk Reduction Model (Catania, Kegeles, & Coates, 1990). Findings showed that demographic, personality, and labeling stage variables had small average correlations with condom use. Commitment and enactment stage variables fared better, with attitudes toward condoms, behavioral intentions, and communication about condoms being the most important predictors. Overall, findings support a social psychological model of condom use highlighting the importance of behavior-specific cognitions, social interaction, and preparatory behaviors rather than knowledge and beliefs about the threat of infection.

Psychosocial correlates of heterosexual condom use: a meta-analysis

Despite increasing incidence of HIV/AIDS, there has been no systematic review of correlates of condom use among heterosexual samples. To rectify this, the present study used meta-analysis to quantify the relationship between psychosocial variables and self-reported condom use. Six hundred sixty correlations distributed across 44 variables were derived from 121 empirical studies. Variables were organized in terms of the labeling, commitment, and enactment stages of the AIDS Risk Reduction Model (Catania, Kegeles, & Coates, 1990). Findings showed that demographic, personality, and labeling stage variables had small average correlations with condom use. Commitment and enactment stage variables fared better, with attitudes toward condoms, behavioral intentions, and communication about condoms being the most important predictors. Overall, findings support a social psychological model of condom use highlighting the importance of behavior-specific cognitions, social interaction, and preparatory behaviors rather than knowledge and beliefs about the threat of infection.

Progression of steroid-associated osteoporosis after heart transplantation

BACKGROUND

Osteoporosis has been recognized as an important side effect of long-term and of pulsed steroid application after heart transplantation.

METHODS

In June 1989 a prospective clinical trial was started to study bone demineralization by quantitative computed tomographic scan. All patients received vitamin D and calcium. In group I (n = 30) synthetic calcitonin (40 Medical Research Council Standard Units subcutaneously per day was administered in 14-day cycles, whereas group II patients (n = 31) received a placebo preparation. Repeat trabecular and cortical quantitative computed tomographic scans of the thoracic (T12) and lumbar spine (L1, L2, L3) were obtained within 48 weeks after heart transplantation.

RESULTS

Expressed as the means of T12, L1, L2, and L3, trabecular bone density decreased significantly from 100+/-24 to 79+/-29 mg/mL within 3 weeks after heart transplantation, followed by a further reduction to 67+/-29 mg/mL after 3 months in the calcitonin group. The values for cortical bone density decreased significantly from 229+/-37 to 202+/-40 mg/mL (calcitonin) 3 weeks after heart transplantation. Comparable results were obtained in the placebo group. In both groups bone density remained stable thereafter. Intergroup differences were not of statistical significance.

CONCLUSIONS

In heart transplant recipients progressive trabecular bone demineralization is limited to the first 3 postoperative months. Thereafter, bone density remained stable. A positive effect of synthetic calcitonin in addition to prophylactic calcium and vitamin D application could not be proved by repeat quantitative computed tomography.

Towards a psycho-social theoretical framework for sexual health promotion

Numerous interventions have been designed to promote safer sexual behaviour amongst young people. However, relatively few have proved effective, which is, at least partially, due to the lack of development of theoretically based programmes. An understanding of the origins and control of sexual behaviour can be derived from basic social science research. Unless this is applied to the design of behaviour-change programmes they are unlikely to target the most important determinants of young people's sexual behaviour and are, therefore, unlikely to be effective. This paper outlines some of the key theoretical insights which have been drawn upon in the development of a new sex education programme currently being tested in Scottish schools. The theoretical basis is intentionally eclectic, combining social psychological cognitive models with sociological interpretations, since we are not concerned to advance any particular theory but to find which are most useful in promoting sexual health. First, the social influences on sexual behaviour are considered, and then the way in which these translate into individual perceptions and beliefs. Finally, the paper attempts to develop a theoretical understanding of sexual interaction and the social contexts of sexual behaviour.

Can social cognitive models contribute to the effectiveness of HIV-preventive behavioural interventions? A brief review of the literature and a reply to Joffe (1996; 1997) and Fife-Schaw (1997)

A recent debate in the British Journal of Medical Psychology has considered the role of social cognitive models, such as the theory of reasoned action and the theory of planned behaviour, in understanding HIV-preventive behaviour. In this paper we clarify some of the assumptions involved in applications of social cognitive models. We briefly review available evidence on the capacity of such models to predict HIV-preventive sexual behaviour and outline a number of criteria for judging their predictive success. The importance of behavioural prediction for the development of effective HIV-preventive behavioural interventions is discussed and recent evaluations of interventions based on these models are reviewed. We conclude that the models are effective in predicting HIV-preventive behaviours and provide empirically supported theoretical guidance on psychological changes likely to result in HIV-preventive behaviour change. In addition we argue that, to date, evaluations of theoretically specified interventions are encouraging. Further development and rigorous testing of HIV/AIDS interventions based on social cognitive models is recommended.

Scientific thinking in ophthalmology

Science, medicine and ophthalmology have all evolved and progressed through varied but powerful influences over the centuries. While the tremendous technological advances in ophthalmology in the past 20 years are readily appreciated, many clinicians fail to grasp the impact of the several clinical trials that have contributed to better patient care. This article briefly traces the history of science, medicine and ophthalmology, and explains how scientific thinking could be applied to the clinical and academic aspects of ophthalmology.

Protein kinase C alpha modulates growth and differentiation in Caco-2 cells

BACKGROUND & AIMS

Caco-2 cells have been used extensively to elucidate events involved in intestinal cell proliferation and differentiation. Because individual isoforms of protein kinase C (PKC) and p21waf1, a cyclin-dependent kinase inhibitor, may regulate these processes, their role(s) on the growth and differentiation of Caco-2 cells were assessed.

METHODS

Protein abundance and subcellular distribution of several PKC isoforms, as well as the expression of p21waf1, were examined in preconfluent and postconfluent cells.

RESULTS

In cells at confluence (approximately 7 days postplating) and during their postconfluent phase (up to 20 days postplating), both total protein expression of PKC-alpha and its particulate distribution increased compared with their 3-day postplated counterparts. These findings were in agreement with those obtained by immunocytochemistry of PKC-alpha. In contrast, neither the total expression nor the subcellular distribution of PKC-betaI, -betaII, -delta, or -zeta changed significantly during these time periods. In addition, the expression of p21waf1, which can be induced by PKC-alpha, increased in postconfluent cells.

CONCLUSIONS

PKC-alpha, but not other isoforms of PKC, may modulate the proliferation and differentiation of Caco-2 cells. This regulation appears to be mediated, at least in part, via a mechanism involving p21waf1.

Decreased PKC-alpha expression increases cellular proliferation, decreases differentiation, and enhances the transformed phenotype of CaCo-2 cells

Previous studies have shown that PKC-alpha protein expression is decreased in sporadic human colon cancers, as well as in colonic tumors of rats induced by chemical carcinogens. To elucidate the potential role of PKC-alpha on several phenotypic characteristics of colon cancer cells, we have transfected cDNAs for PKC-alpha in sense or antisense orientations into CaCo-2 cells, a human colonic adenocarcinoma cell line. Transfected clones were isolated that demonstrated approximately 3-fold increases (sense transfectants) and approximately 95% decreases (antisense transfectants) in PKC-alpha expression with no significant alterations in other PKC isoforms. Transfection of CaCo-2 cells with PKC-alpha in the antisense orientation resulted in enhanced proliferation and decreased differentiation, as well as in a more aggressive transformed phenotype compared with empty vector-transfected control cells. In contrast, cells transfected with PKC-alpha cDNA in the sense orientation demonstrated decreased proliferation, enhanced differentiation, and an attenuated tumor phenotype compared with these control cells. These data show that alterations in the expression of PKC-alpha induce changes in the proliferation, differentiation, and tumorigenicity of CaCo-2 cells. Furthermore, these findings indicate that loss of PKC-alpha expression in sporadic human and chemically induced colonic cancers may confer a relative growth advantage during colonic malignant transformation.

1,25 dihydroxyvitamin D3 stimulates phospholipase C-gamma in rat colonocytes: role of c-Src in PLC-gamma activation

Our laboratory has previously demonstrated that 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) rapidly stimulated polyphosphoinositide (PI) hydrolysis, raised intracellular Ca2+, and activated two Ca2+-dependent protein kinase C (PKC) isoforms, PKC-alpha and -betaII in the rat large intestine. We also showed that the direct addition of 1,25(OH)2D3 to isolated colonic membranes failed to stimulate PI hydrolysis, but required secosteroid treatment of intact colonocytes, suggesting the involvement of a soluble factor. Furthermore, this PI hydrolysis was restricted to the basal lateral plasma membrane of these cells. In the present studies, therefore, we examined whether polyphosphoinositide-phospholipase C-gamma (PI-PLC-gamma), a predominantly cytosolic isoform of PI-PLC, was involved in the hydrolysis of colonic membrane PI by 1,25(OH)2D3. This isoform has been shown to be activated and membrane-associated by tyrosine phosphorylation. We found that 1,25(OH)2D3 caused a significant increase in the biochemical activity, particulate association, and the tyrosine phosphorylation of PLC-gamma, specifically in the basal lateral membranes. This secosteroid also induced a twofold increase in the activity of Src, a proximate activator of PLC-gamma in other cells, with peaks at 1 and 9 min in association with Src tyrosine dephosphorylation. 1,25(OH)2D3 also increased the physical association of activated c-Src with PLC-gamma. In addition, Src isolated from colonocytes treated with 1,25(OH)2D3, demonstrated an increased ability to phosphorylate exogenous PLC-gamma in vitro. Inhibition of 1,25(OH)2D3-induced Src activation by PP1, a specific Src family protein tyrosine kinase inhibitor, blocked the ability of this secosteroid to stimulate the translocation and tyrosine phosphorylation of PLC-gamma in the basolateral membrane (BLM). Src activation was lost in D deficiency, and was reversibly restored with the in vivo repletion of 1,25(OH)2D3. These studies demonstrate for the first time that 1,25(OH)2D3 stimulates PLC-gamma as well as c-Src in rat colonocytes, and indicate that PLC-gamma is a direct substrate of secosteroid-activated c-Src in these cells.

Interaction of S 21007 with 5-HT3 receptors. In vitro and in vivo characterization

The interaction of S 21007 [5-(4-benzyl piperazin-1-yl)4H pyrrolo [1,2-a]thieno[3,2-e]pyrazine] with serotonin 5-HT3 receptors was investigated using biochemical, electrophysiological and functional assays. Binding studies using membranes from N1E-115 neuroblastoma cells showed that S 21007 is a selective high affinity (IC50 = 2.8 nM) 5-HT3 receptor ligand. As expected of an agonist, S 21007 stimulated the uptake of [14C]guanidinium (EC50 approximately 10 nM) in NG 108-15 cells exposed to substance P, and this effect could be prevented by the potent 5-HT3 receptor antagonist ondansetron. In addition, like 5-HT and other 5-HT3 receptor agonists (phenylbiguanide and 3-chloro-phenylbiguanide), S 21007 (EC50 = 27 microM) produced a rapid inward current in N1E-115 cells. The 5-HT3 receptor agonist action of S 21007 was also demonstrated in urethane-anaesthetized rats as this drug (120 micrograms/kg i.v.) triggered the Bezold-Jarisch reflex (rapid fall in heart rate), and this action could be prevented by pretreatment with the potent 5-HT3 receptor antagonist zacopride. Finally, in line with its 5-HT3 receptor agonist properties, S 21007 also triggered emesis in the ferret. Evidence for 5-HT3 receptor antagonist-like properties of S 21007 was also obtained in some of these experiments since previous exposure to this compound prevented both the 5-HT-induced current in N1E-115 cells and the Bezold-Jarisch reflex elicited by an i.v. bolus of 5-HT (30 micrograms/kg) in urethane-anaesthetized rats. These data suggest that S 21007 is a selective 5-HT3 receptor agonist which can exhibit antagonist-like properties either by triggering a long lasting receptor desensitization or by a partial agonist activity at 5-HT3 receptors in some tissues.

Systemic inflammatory response syndrome after cardiac operations

BACKGROUND

A systemic inflammatory response after open heart operation may be responsible for hyperdynamic circulatory instability and organ dysfunction. To what extent mediator release is involved needs to be clarified.

METHODS

Ten patients with postoperative hyperdynamic circulatory dysregulation (group I) requiring application of alpha-constrictors and 10 patients with routine cardiac procedures and stable postoperative hemodynamic indices (group II) were analyzed for mediator release and metabolic and hemodynamic changes until the third postoperative day.

RESULTS

Group I patients showed a significantly increased cardiac index and decreased systemic vascular resistance after bypass (cardiac index, group I: 5.2 +/- 1.2 L.min-1.m-2, group II: 2.5 +/- 1.6 L.min-1.m-2; systemic vascular resistance, group I: 495 +/- 204 dyne.s. cm-5, group II: 1,356 +/- 466 dyne.s.cm-5) and at 3 hours (cardiac index, group I: 4.4 +/- 0.8 L.min-1.m-2, group II: 2.9 +/- 0.6 L.min-1.m-2; systemic vascular resistance, group I: 567 +/- 211 dyne.s.cm-5, group II: 1,053 +/- 273 dyne.s.cm-5). Significantly higher serum levels of interleukin-6 were assessed in group I (postbypass, group I: 6,812 +/- 9,293 pg/mL, group II: 295 +/- 303 pg/mL; 3 hours, group I: 3,474 +/- 5,594 pg/mL, group II: 286 +/- 296 pg/mL). Concentrations of elastase, tumor necrosis factor, soluble tumor necrosis factor receptor, and interleukin-8 were elevated in group I (not significant). Early postoperative levels of soluble E-selectin and soluble intercellular adhesion molecule were also higher in group I (not significant). Continuously increased levels of endotoxin could be detected in only 3 of 10 patients in group I. Severe lactic acidosis (> or = 5 mmol/L) occurred in group I only.

CONCLUSIONS

Postoperative hyperdynamic instability after open heart operations appears to be associated with a certain pattern of mediator release. In particular, interleukin-6 appears to be involved in circulatory dysregulation and metabolic derangement.