[Alcohol use disorder: risks in anesthesia and intensive care medicine]

Approximately 20% of medical and surgical patients in hospital have an alcohol use disorder (AUD). Diagnosis of chronic alcohol abuse is performed by specific medical history, examination and validated tests. Biomarkers are a means of diagnosing chronic alcoholism in sedated, intubated and emergency patients. Chronic alcohol consumption damages the central nervous and cardiovascular system, the liver and the immune system. In medical ICUs more than 50% of liver injuries and chronic pancreatitis are due to chronic alcohol abuse. The alcohol withdrawal syndrome is emerging in 25% of AUD patients in intensive care after reduction of sedative drugs. Long term alcohol abuse also leads to cardiac arrhythmias, dilatative cardiomyopathy and hypotonic circulatory dysregulation. Bleeding complications are two-fold increased during and after surgery. Immune suppression results in an increased incidence of infectious complications like pneumonia, wound infection and urinary tract infection. In particular, septic encephalopathy is often misinterpreted as alcohol withdrawal syndrome. Due to the fact that AUD patients show a two to five-fold higher rate of postoperative complications they require increased attention to avoid latency of treatment and the development of multiple organ failure. Prophylaxis in terms of drug therapy or abstinence intervals and brief intervention strategies can help to prevent or ease some of these complications and can decrease the rate of long-term injuries.

Flow-Erleben unter kontrollierter Beanspruchungssteuerung

Zusammenfassung. Sportliche Aktivitäten wurden von Anbeginn in die Flow-Forschung einbezogen, wobei recht bald deutlich wurde, dass eine verlaufsnahe Diagnostik, also einer Diagnostik während der sportlichen Tätigkeit, dem Flow-Konstrukt am Besten entspricht. Allerdings liefern Feldstudien, welche die Auslösebedingungen für das Auftreten von Flow und die Flow-Leistungsbeziehung bei sportlichen Aktivitäten zu klären versuchen, eher inkonsistente Befunde. Ziel der vorliegenden Laufbandstudie war es daher: 1) zu prüfen, ob die von Csikszentmihalyi (1975) postulierte Anforderungs-Fähigkeits-Passung für Läufer auch unter Laborbedingungen Voraussetzung für das Auftreten von Flow ist und 2) die Dynamik des Flow-Erlebens im Zeitverlauf und in Abhängigkeit physiologischer Leistungsparameter beim Laufen zu dokumentieren. Mit Hilfe einer beanspruchungsorientierten Geschwindigkeitssteuerung des Laufbands gelang es, die Probanden (N = 30) auf einem individuell bestimmten, überdurchschnittlichem Anspruchsniveau kontrolliert 40 Minuten laufen zu lassen. Im Fazit lässt sich feststellen, dass die Probanden über ein tiefes und im Verlauf stabiles Flow-Erleben berichten. Allerdings ist dies davon unabhängig, ob sie subjektiv eine optimale Anforderungs-Fähigkeits-Passung erleben.

Effect of substrate and fibrin polymerization inhibitor on determination of plasma thrombin generation in vitro

BACKGROUND

Thrombin generation potential, a critical haemostatic measure, can be determined by continuous detection of total thrombin or direct subsampling. However, differences between methods exist in area under the curve or peak thrombin calculated. Also, impact of anticoagulants on thrombin generation may vary depending on mode of analysis.

OBJECTIVE

We studied the effect of components on thrombin generation in the presence or absence of anticoagulants.

METHODS

The continuous method was conducted with plasma +/- fibrin(ogen) +/- fibrin polymerization inhibitor. Plasma contained slow-reacting TG5134 substrate at 37 degrees C and reaction was started with dilute thromboplastin in CaCl(2)/Tris buffer. Absorbance (405 nm) was recorded over time and free thrombin calculated from total thrombin activity. For the subsampling method, similar plasma mixtures +/- TG5134 were reacted and free thrombin measured directly as the difference in activity against S2238 substrate of timed subsamples taken into EDTA or EDTA + antithrombin + heparin.

RESULTS

Slow-reacting substrate in the continuous method acted as a competitor for thrombin, giving delayed but greater free thrombin than direct subsampling. These differences persisted to varying extents with all anticoagulants tested. In either method, presence of polymerization inhibitor increased the amount of free thrombin. Continuous method detection of alpha(2)macroglobulin complexes was hampered by sensitivity limits leading to inordinate free thrombin calculations. Especially with hirudin, although free thrombin remained at the end of the subsampling method, continuous method calculations assumed no residual free thrombin.

CONCLUSION

In vitro plasma thrombin generation is delayed and increased by slow-acting substrate and fibrin polymerization inhibitor.

Flow-Erleben beim Marathonlauf

Zusammenfassung. Ausgehend vom Flow-Konzept Csikszentmihalyis (1992 , 2004 ) und Forschungsberichten zum Flow-Erleben, stellt der Beitrag zwei Studien vor, die Flow-Erfahrungen von Marathonläufern (N = 234) dokumentieren und analysieren. Als Messinstrument diente die Flow-Kurzskala von Rheinberg, Vollmeyer und Engeser (2003 ). Auf der Basis der Selbstberichte der Läufer zum Flow-Erleben (Flow-Generalfaktor) und zu ihrer subjektiven Anforderungs-Fähigkeits-Passung sowie den erfassten Laufzeiten werden in den statistischen Analysen folgende Fragestellungen überprüft: 1.) Stellt die Anforderungs-Fähigkeits-Passung eine Voraussetzung für Flow-Erfahrungen dar? und 2.) Steht Flow im Zusammenhang mit den Laufleistungen? Die Ergebnisse zeigen, dass die Passung nicht zwingend als Voraussetzung für Flow-Erfahrungen angesehen werden muss und ein Flow-Leistungs-Zusammenhang für Marathonläufer der mittleren Leistungsfähigkeit (3 bis 4 Stunden Laufzeit) nicht existiert. Im Resümee werden Schlussfolgerungen für die weitere Flow-Forschung im Sport gezogen.

Chronic hepatitis B: recommendations for therapy based on the natural history of disease in Australian patients

BACKGROUND

Chronic hepatitis B infection (CHB) is a major health problem in Australia and worldwide. CHB is associated with significant long-term morbidity and mortality. Well tolerated treatment is now available, however the development of resistance is common and the optimal timing of treatment is yet to be determined. Identifying the factors that influence the natural history of CHB may help determine which patients need treatment and when to start it.

OBJECTIVE

To determine the demographics, clinical features and virological profile of Australian patients infected with CHB and the influence of these factors on disease activity and severity.

STUDY DESIGN

Review of prospectively collected demographic, clinical and virological features of all patients positive for hepatitis B surface antigen (HBsAg) for more than 6 months who were referred to St. Vincent's Hospital liver clinics. Age, sex and ethnicity were correlated with hepatitis B e antigen status (HBeAg), HBV replication status (ALT and HBV DNA), genotype and liver histology.

RESULTS

703 chronic hepatitis B surface antigen positive patients were identified. The patients were predominantly male with an average age of 44. Eighty two percent of patients were born overseas, primarily from Asian (65%) and Mediterranean countries (14%). Two thirds (426) had an elevated ALT (median 79) at presentation. HBeAg was positive in 37%. Active viral replication, defined as abnormal ALT or positive HBVDNA, was present in 74%, 48% of whom were HBeAg negative. In a subset of 103 patients genotyped, 8% had genotype A, 29% B, 41% C and 22% D. Genotype correlated with ethnicity; patients infected with genotypes A were predominantly Caucasian, B and C were Asian, and D were Mediterranean. Of 296 (42%) patients who underwent liver biopsy, 76 (27%) had advanced fibrosis. Advanced fibrosis was associated with increasing age and Mediterranean ethnicity.

CONCLUSION AND RECOMMENDATIONS

Perinatal or early childhood transmission is predominant mode of infection in Australia. Two thirds of this cohort had active replication and were at increased risk of developing cirrhosis and/or hepatoma. Advanced disease was associated with age and ethnicity. HBeAg negative CHB accounts for almost half of all those with active viral replication. This parallels the rise in this form of CHB in Asia and the Mediterranean basin. Screening should be offered to people born in, or with parents born in areas of high endemnicity. To detect the development of active disease, patients with positive HBsAg but normal ALT should have liver function tests done 6 monthly and those with elevated ALT should be referred for consideration of therapy, irrespective of HBeAg status.

Long-term follow-up of secondary malignancies in adults after allogeneic bone marrow transplantation

The purpose of this study was to evaluate the estimated incidence of secondary malignancies post-allogeneic bone marrow transplantation (BMT) in a cohort of adult patients previously reported now with an additional 8.5 years of follow-up. A cohort of 557 patients older than age 16 years underwent allogeneic BMT between June 1970 and November 1993. Histologic reports confirmed the diagnosis of a secondary malignancy. Multivariate Cox proportional hazards method was utilized to investigate predictors for the development of secondary malignancies. In all, 31 patients in this cohort developed a secondary malignancy a median of 6.79 years after their transplant. The estimated cumulative incidence rate of secondary malignancy was 4.2% at 10 years post transplant. When compared to the general population, the estimated observed/expected ratio of new cancer diagnoses was 5.13. On multivariate analysis, older age at the time of transplant was the only significant predictor for development of secondary cancer (P=0.01). The most common malignancies observed were nonmelanomatous skin cancers and squamous cell cancers of the buccal cavity. The risk of developing a secondary malignancy after allogeneic BMT is significant, particularly in older patients. Long-term survivors of transplant require regular monitoring for early signs of cancer, particularly of the skin and oral cavity.

Investigation of the Affinities of Two New b-Carbolines for Rat Brain Imidazoline2 Receptors

The beta-carbolines are possible endogenous ligands and modulators of the imidazoline binding sites (I-BSs). Relatively little is known about this class of compound and its interaction with the I-BS. Presented here are the binding data for two aryl ring substituted dihydro-beta-carbolines at the imidazoline(2) binding site (I(2)-BS) and alpha(2)-adrenoceptor: BG-326 (5-bromo-4,9-dihydro-3H-b-carboline) and BG-350 (5-methoxy-4,9-dihydro-3H-b-carboline). Both compounds show good affinity and selectivity for the I(2)-BS.

Human PDE5A gene encodes three PDE5 isoforms from two alternate promoters

Sildenafil improves erectile function by inhibiting the cGMP-catalytic activity of phosphodiesterase type V (PDE5). We used rapid amplification of cDNA Ends-polymerase chain reaction (RACE-PCR) to isolate three PDE5 isoforms from human corpus cavernosum. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis on eight human cavernous tissue samples showed that all samples expressed the PDE5A1 at a lower level than the PDE5A2 isoform. Five samples expressed the PDE5A3 isoform at various levels while the other three did not. Analysis on non-penile tissues showed that all tissues expressed the A1 and A2 isoforms while only those that have substantial amounts of smooth muscle expressed the A3 isoform. Cloning and sequencing of the PDE5A gene showed that the isoform-specific 5'-ends of the PDE5 mRNAs are encoded from three alternative first exons arranged in the order of A1-A3-A2. Promoter activities were detected upstream from the A1-specific exon and in the intron preceding the A2-specific exon. The upstream PDE5A promoter is expected to direct the expression of all three PDE5 isoforms while the intronic PDE5A2 promoter only the A2 isoform. Both promoters were upregulated by increasing concentrations of either cAMP or cGMP. Several transcription factor AP2 and Sp1-binding sequences identified in the promoters are likely to be the mediators of cAMP/cGMP-responsiveness.

Crystallizing thoughts about DNA base excision repair

Chemically damaged bases are removed from DNA by glycosylases that locate the damage and cleave the bond between the modified base and the deoxyribose sugar of the DNA backbone. The detection of damaged bases in DNA poses two problems: (1) The aberrant bases are mostly buried within the double helix, and (2) a wide variety of chemically different modifications must be efficiently recognized and removed. The human alkyladenine glycosylase (AAG) and Escherichia coli Alka DNA glycosylases excise many different types of alkylated bases from DNA. Crystal structures of these enzymes show how substrate bases are exposed to the enzyme active site and they suggest mechanisms of catalytic specificity. Both enzymes bend DNA and flip substrate bases out of the double helix and into the enzyme active site for cleavage. Although AAG and AlkA have very different overall folds, some common features of their substrate-binding sites suggest related strategies for the selective recognition of a chemically diverse group of alkylated substrates.

Thrombin receptor signaling to cytoskeleton requires Hsp90

Thrombin is a serine protease that evokes various cellular responses involved in injury and repair of the nervous system through the activation of protease-activated receptor-1 (PAR-1). Signals that modulate cell morphology precede most PAR-1 effects, but the initial signal transduction molecules are not known. Using the yeast two-hybrid system, we identified Hsp90, a chaperone with known signaling properties, as a binding partner of PAR-1. The interaction was confirmed by glutathione S-transferase pull-down, overlay, and co-immunoprecipitation assays. Morphological assays in mouse astrocytes were carried out to evaluate the importance of Hsp90 during cytoskeletal signaling. Reducing Hsp90 levels by antisense treatment or disruption of the Hsp90.PAR-1 complex by the Hsp90-specific drug geldanamycin attenuated thrombin-mediated astrocyte shape changes. Furthermore, overexpression of the PAR-1 cytoplasmic tail abrogated thrombin-induced cytoskeletal changes in neuronal cells. Treatment with geldanamycin specifically inhibited activation of RhoA without affecting thrombin-mediated intracellular calcium release, revealing the regulation of a distinct signaling pathway by Hsp90. Taken together, these studies demonstrate that Hsp90 may be essential for PAR-1-mediated signaling to the cytoskeleton.

Decreased trabecular smooth muscle and caveolin-1 expression in the penile tissue of aged rats

PURPOSE

Because decreased trabecular smooth muscle content is reportedly associated with vasculogenic impotence in men, we performed a rodent study to investigate the effect of aging on trabecular smooth muscle content and caveolin-1 protein expression in penile smooth muscle cells.

MATERIALS AND METHODS

In 6 young (age 3 months) and 6 old (age 24 months) rats erectile function was evaluated by cavernous nerve stimulation. At sacrifice penile tissue samples were collected for Western blot analysis, Masson's trichrome staining, caveolin-1 immunostaining and electron microscopy. The percent of smooth muscle in the trabecular tissue was assessed by computer assisted image analysis.

RESULTS

In the aged rats mean intracavernous pressure plus or minus standard deviation was decreased (70 +/- 8.8 versus 107 +/- 12.3 cm. water) and the latency period was increased (7.8 +/- 1.2 versus 4.5 +/- 0.5 seconds) significantly compared to values in the young rats (p <0.001). The mean ratio of trabecular smooth muscle-to-connective tissue was also significantly altered in old versus young rats (27% +/- 2.9% versus 42.1% +/- 5.1%, p <0.001). Immunostaining for caveolin-1 was noted in each group in the sarcolemma of smooth muscle cells and endothelium of trabecular sinusoids but the staining pattern was less intense and the percent of smooth muscle positive for caveolin-1 was decreased in aged versus young rats (17.9% +/- 2.5% versus 27.5% +/- 3.6%, p <0.001). Moreover, young trabecular smooth muscle cells had more caveolae in the sarcolemma on electron microscopy and a higher expression of caveolin-1 protein on Western blot analysis. In contrast, higher endothelial nitric oxide synthase protein expression was noted in the penile tissue of old rats.

CONCLUSIONS

In these aged rats the decreased ratio of trabecular smooth muscle-to-collagen and the reduced expression of caveolin-1 may contribute to erectile dysfunction.

Using a personal digital assistant to document clinical pharmacy services in an intensive care unit

Management Case Studies describe approaches to real-life management problems in health systems. Each installment is a brief description of a problem and how it was dealt with. The cases are intended to help readers deal with similar experiences in their own work sites. Problem solving, not hypothesis testing, is emphasized. Successful resolution of the management issue is not a criterion for publication--important lessons can be learned from failures, too.

Conceptualizing quality of life for elderly people with stroke

PURPOSE

Despite increased interest in quality of life (QOL) as an outcome measure and as a means of identifying client needs in health care, its conceptualisation and the identification of its constituents have been poorly researched for elderly people with stroke in Hong Kong.

METHOD

This article analysed the literature to identify components relevant to the QOL of Chinese elderly people with stroke living in the community in Hong Kong.

RESULTS

While common components of QOL for elderly people with and without stroke and regardless of cultural background were identified, a number were specific to an elderly Chinese stroke population.

CONCLUSION

Recommendations for future research have been made with reference to further exploring and validating these components for the target population. A clear understanding of these aspects is essential for the development of sensitive QOL measures to guide and evaluate service delivery to this population.

MDM2 and MDMX can interact differently with ARF and members of the p53 family

Members of the p53 family of transcription factors have essential roles in tumor suppression and in development. MDM2 is an essential regulator of p53 that can inhibit the transcriptional activity of p53, shuttle p53 out of the nucleus, and target p53 for ubiquitination-mediated degradation. Little is known about the interaction and selectivity of different members of the p53 family (p53, p63, and p73) and the MDM2 family (MDM2 and MDMX). Here we show that the transcriptional activities of p53 and p73, but not that of p63, were inhibited by both MDM2 and MDMX. Consistent with these, we found that MDMX can physically interact with p53 and p73, but not with p63. Moreover, ectopically expressed MDM2 and MDMX could induce alterations in the subcellular localization of p73, but did not affect the subcellular localization of p53 and p63. Finally, we demonstrate that while ARF can interact with MDM2 and inhibit the regulation of p53 by MDM2, no interaction was found between ARF and MDMX. These data reveal that significant differences and selectivity exist between the regulation of different members of the p53 family by MDM2 and MDMX.

Identification and regulation of human PDE5A gene promoter

PDE5A gene encodes type 5 phosphodiesterase (PDE5), the principal cGMP-catalyzing enzyme in the penis and the primary target of sildenafil (Viagra). We have isolated a 3.7-kb DNA fragment that contains the human PDE5A gene promoter. The DNA fragment contains a sequence of 234 nucleotides at its 3' end that corresponds to most of the untranslated region of the PDE5A1 mRNA. The remaining 3.5-kb upstream flanking sequence contains no apparent TATA box but has several sequences that resemble binding sequences for transcription factors such as androgen receptor (AR), AP1, AP2, AP4, Sp1, MyoD, Myc, and CArG. In search of promoter activities, we used a luciferase reporter system to examine 10 DNA fragments that cover various regions of the 3.7-kb fragment. We found that a full basal promoter activity was confined to a 139-bp region that includes 78 bp of the PDE5A1-specific first exon. A lesser basal promoter activity was still detectable in a 94-bp fragment that contains the same 78-bp PDE5A1-specific exon plus 16 bp of upstream sequence. Either the 139-bp or the 94-bp promoter fragment responded minimally to cAMP or cGMP (2 mM) stimulation. Longer fragments that contain either a 308-bp 5' extension (from the 138-bp fragment) or a 156-bp 3' extension (all exon sequence) responded at higher levels to cAMP and cGMP stimulation. The 5' and 3' extensions cooperated with each other to provide the highest level of responses to cAMP and cGMP stimulation. DNase I footprint analysis identified four AP2- and two Sp1-binding sites in the 5' extension and four Sp1-binding sites in the 3' extensions. Cyclic AMP and cGMP had similar stimulatory effects on the PDE5A promoter.

Regulation of human PDE5A2 intronic promoter by cAMP and cGMP: identification of a critical Sp1-binding site

PDE5A gene encodes type 5 phosphodiesterase (PDE5), the principal cGMP-catalyzing enzyme in the penis and the primary target of sildenafil (Viagra). We have previously reported the isolation of three alternatively spliced PDE5A isoforms in humans. We also reported the identification of three corresponding alternative first exons and an intronic promoter in the human PDE5A gene. The intronic promoter is situated upstream from the PDE5A2-specific first exon but downstream from the PDE5A1- and A3-specific first exons. In the current study we showed that the intronic promoter could be upregulated by either cAMP or cGMP. In order to identify possible regulatory elements in the promoter, we created deletion and base-substitution mutants targeting one AP2- and four Sp1-binding sequences. Loss of function of these mutants to bind to the respective transcription factors was verified by DNase I footprint analysis, and changes in promoter function were analyzed with a luciferase reporter system. Mutation of the AP2-binding sequence and deletion of the 3'-most Sp1-binding site (within the exon) had little effects on the basal or the cyclic nucleotide-inducible promoter functions. Mutation of the 5'-most Sp1-binding site had much more severe effects on the basal and the cyclic nucleotide-inducible promoter functions. Mutation of a neighboring site that contains two overlapping Sp1-binding sequences completely nullified the basal and cyclic nucleotide-inducible promoter activities. Thus, the PDE5A2 intronic promoter depends on the overlapping Sp1-binding site for basal and cyclic nucleotide-inducible functions.

Genetic imbalances in pT2 breast cancers of southern Chinese women

While much information has been reported on the genetic alterations in breast cancers of Caucasians, little is known about the Oriental populations where breast cancers currently rank the second most common neoplasm. As a first step toward understanding the underlying genetics changes in this population, we used comparative genomic hybridization (CGH) to the genome-wide analysis of forty pT2 tumors from patients of a racially homogenous population in southern China. A complex pattern of genetic alterations emerged with the commonest chromosomal gains identified on 1q (58%), 8q (55%), 11q13 (25%), 16p (28%), 17q (53%) and 20q (35%), and frequent losses on 8p (38%), 11q (28%), 13q (30%) and 18q (25%). When breast cancers with and without lymph-node metastasis were compared, a higher copy gain of 10p was identified in the node-positive group (P=.036). An overall increase in the average number of genetic aberrations was also identified in the late onset group (>45 years)(P=.042) with a higher incidence of genetic losses noted (P=.035). In particular, losses on 16q were detected in 30% of the late onset patients but none in the early onsets (P=0.049). In this study, we have illustrated the pattern of genetic changes in breast tumors of southern Chinese females. While frequent 1q, 8q, 17q and 20q gains, and common 8p and 13q deletions detected were consistent to those aberrations reported from the Caucasian populations, the difference in genetic changes associated in lymph-node metastasis and age of onset identified should provide the basis for additional investigations into the underlying tumorigenesis in the Oriental population.

During ontogeny primitive (CD34(+)CD38(-)) hematopoietic cells show altered expression of a subset of genes associated with early cytokine and differentiation responses of their adult counterparts

Comparison of gene expression profiles in closely related subpopulations of primitive hematopoietic cells offers a powerful first step to elucidating the molecular basis of their different biologic properties. Here we present the results of a comparative quantitative analysis of transcript levels for various growth factor receptors, ligands, and transcription factor genes in CD34(+)CD38(-) and CD34(+)CD38(+) cells purified from first trimester human fetal liver, cord blood, and adult bone marrow (BM). In addition, adult BM CD34(+)CD38(-) cells were examined after short-term exposure to various growth factors in vitro. Transcripts for 19 of the 24 genes analyzed were detected in unmanipulated adult BM CD34(+)CD38(-) cells. Moreover, the levels of transforming growth factor beta (TGF-beta), gp130, c-fos, and c-jun transcripts in these cells were consistently and significantly different (higher) than in all other populations analyzed, including phenotypically similar but biologically different cells from fetal or neonatal sources, as well as adult BM CD34(+) cells still in G(0) after 2 days of growth factor stimulation. We have thus identified a subset of early response genes whose expression in primitive human hematopoietic cells is differently regulated during ontogeny and in a fashion that is recapitulated in growth factor-stimulated adult BM CD34(+)CD38(-) cells, before their cell cycle progression and independent of their subsequent differentiation response. These findings suggest a progressive alteration in the physiology of primitive hematopoietic cells during development such that these cells initially display a partially "activated" state, which is not maximally repressed until after birth. (Blood. 2000;96:4160-4168)

The environmental effects of dental amalgam

Dental amalgam is one of the most commonly used materials in restorative dentistry. However, one of its major components, mercury, is of particular concern due to its potential adverse effects on humans and the environment. In this review, the environmental impact of dental amalgam will be discussed, with particular reference to the effects attributed to its mercury component. Mercury commonly occurs in nature as sulfides and in a number of minerals. Globally, between 20,000-30,000 tons of mercury are discharged into the environment each year as a result of human activities. According to a recent German report, approximately 46 per cent of the freshly triturated amalgam is inserted as new amalgam restorations and the rest is waste. Depending on the presence of an amalgam separating unit, some of the generated amalgam-contaminated sludge is discharged into the sewage system. Lost or extracted teeth with amalgam fillings and amalgam-contaminated waste, such as trituration capsules and cotton rolls are discharged with the solid waste and, in most instances, are incinerated. Use of disinfectants containing oxidizing substances in dental aspirator kits may contribute to remobilization of mercury and its subsequent release into the environment. Nevertheless, dental mercury contamination is only a small proportion of terrestrial mercury (3-4 per cent), which is quite insignificant compared with industrial pollution and combustion of fossil fuels by vehicles. The environmental impact of dental mercury is mainly due to the poor management of dental amalgam waste. Proper collection of mercury-contaminated solid waste prevents the release of mercury vapour during combustion. In addition, the use of amalgam separating devices reduces the amount of amalgam-contaminated water released from dental clinics.

Inhibition of neuronal apoptosis by docosahexaenoic acid (22:6n-3). Role of phosphatidylserine in antiapoptotic effect

Enrichment of Neuro 2A cells with docosahexaenoic acid (22:6n-3) decreased apoptotic cell death induced by serum starvation as evidenced by the reduced DNA fragmentation and caspase-3 activity. The protective effect of 22:6n-3 became evident only after at least 24 h of enrichment before serum starvation and was potentiated as a function of the enrichment period. During enrichment 22:6n-3 incorporated into phosphatidylserine (PS) steadily, resulting in a significant increase in the total PS content. Similar treatment with oleic acid (18:1n-9) neither altered PS content nor resulted in protective effect. Hindering PS accumulation by enriching cells in a serine-free medium diminished the protective effect of 22:6n-3. Membrane translocation of Raf-1 was significantly enhanced by 22:6n-3 enrichment in Neuro 2A cells. Consistently, in vitro biomolecular interaction between PS/phosphatidylethanolamine /phosphatidylcholine liposomes, and Raf-1 increased in a PS concentration-dependent manner. Collectively, enrichment of neuronal cells with 22:6n-3 increases the PS content and Raf-1 translocation, down-regulates caspase-3 activity, and prevents apoptotic cell death. Both the antiapoptotic effect of 22:6n-3 and Raf-1 translocation are sensitive to 22:6n-3 enrichment-induced PS accumulation, strongly suggesting that the protective effect of 22:6n-3 may be mediated at least in part through the promoted accumulation of PS in neuronal membranes.

Creatine kinase, an ATP-generating enzyme, is required for thrombin receptor signaling to the cytoskeleton

Thrombin orchestrates cellular events after injury to the vascular system and extravasation of blood into surrounding tissues. The pathophysiological response to thrombin is mediated by protease-activated receptor-1 (PAR-1), a seven-transmembrane G protein-coupled receptor expressed in the nervous system that is identical to the thrombin receptor in platelets, fibroblasts, and endothelial cells. Once activated by thrombin, PAR-1 induces rapid and dramatic changes in cell morphology, notably the retraction of growth cones, axons, and dendrites in neurons and processes in astrocytes. The signal is conveyed by a series of localized ATP-dependent reactions directed to the actin cytoskeleton. How cells meet the dynamic and localized energy demands during signal transmission is unknown. Using the yeast two-hybrid system, we identified an interaction between PAR-1 cytoplasmic tail and the brain isoform of creatine kinase, a key ATP-generating enzyme that regulates ATP within subcellular compartments. The interaction was confirmed in vitro and in vivo. Reducing creatine kinase levels or its ATP-generating potential inhibited PAR-1-mediated cellular shape changes as well as a PAR-1 signaling pathway involving the activation of RhoA, a small G protein that relays signals to the cytoskeleton. Thrombin-stimulated intracellular calcium release was not affected. Our results suggest that creatine kinase is bound to PAR-1 where it may be poised to provide bursts of site-specific high-energy phosphate necessary for efficient receptor signal transduction during cytoskeletal reorganization.

The role of working memory in analogical mapping

The impact of a working-memory load on analogical mapping was examined in two experiments, using a dual-task paradigm. In Experiment 1, we used a phonological working-memory load; in Experiment 2, we used a phonological working-memory load and an executive working-memory load. The subjects were required to identify correspondences between visual scenes, either for single objects or for three objects simultaneously. The results indicated that the imposition of either a phonological or an executive working-memory load decreased the frequency with which the subjects identified correspondences between scenes based on relations and increased the frequency with which they identified correspondences based on object attributes. The frequency with which subjects made relational mappings was increased by the instruction to find correspondences for multiple objects in a scene simultaneously, rather than for just one. These results indicate that mapping on the basis of relations places greater demands on both modality-specific buffers and executive components of working memory than does mapping on the basis of object attributes.

Structural studies of human alkyladenine glycosylase and E. coli 3-methyladenine glycosylase

Human alkyladenine glycosylase (AAG) and Escherichia coli 3-methyladenine glycosylase (AlkA) are base excision repair glycosylases that recognize and excise a variety of alkylated bases from DNA. The crystal structures of these enzymes have provided insight into their substrate specificity and mechanisms of catalysis. Both enzymes utilize DNA bending and base-flipping mechanisms to expose and bind substrate bases. Crystal structures of AAG complexed to DNA suggest that the enzyme selects substrate bases through a combination of hydrogen bonding and the steric constraints of the active site, and that the enzyme activates a water molecule for an in-line backside attack of the N-glycosylic bond. In contrast to AAG, the structure of the AlkA-DNA complex suggests that AlkA substrate recognition and catalytic specificity are intimately integrated in a S(N)1 type mechanism in which the catalytic Asp238 directly promotes the release of modified bases.

On the concentrations of cyclins and cyclin-dependent kinases in extracts of cultured human cells

Cyclins and cyclin-dependent kinases (CDKs) are key regulators of the human cell cycle. Here we have directly measured the concentrations of the G(1) and G(2) cyclins and their CDK partners in highly synchronized human cervical carcinoma cells (HeLa). To determine the exact concentrations of cyclins and CDKs in the cell extracts, we developed a relatively simple method that combined the use of (35)S-labeled standards produced in rabbit reticulocyte lysates and immunoblotting with specific antibodies. Using this approach, we formally demonstrated that CDC2 and CDK2 are in excess of their cyclin partners. We found that the concentrations of cyclin A2 and cyclin B1 (at their peak levels in the G(2) phase) were about 30-fold less than that of their partner CDC2. The peak levels of cyclin A2 and cyclin E1, at the G(2) phase and G(1) phase, respectively, were only about 8-fold less than that of their partner CDK2. These ratios are in good agreement with size fractionation analysis of the relative amount of monomeric and complexed forms of CDC2 and CDK2 in the cell. All the cyclin A2 and cyclin E1 are in complexes with CDC2 and CDK2, but there are some indications that a significant portion of cyclin B1 may not be in complex with CDC2. Furthermore, we also demonstrated that the concentration of the CDK inhibitor p21(CIP1/WAF1) induced after DNA damage is sufficient to overcome the cyclin-CDK2 complexes in MCF-7 cells. These direct quantitations formally confirmed the long-held presumption that CDKs are in excess of the cyclins in the cell. Moreover, similar approaches can be used to measure the concentration of any protein in cell-free extracts.

Placental haemozoin and malaria in pregnancy

Malaria infections in pregnant women cause poor birth outcomes. Malaria pigment (haemozoin) accumulates in the placenta within macrophages and extracellularly, but its pathological significance is not understood. In order to study the potential role of haemozoin in malaria pathogenesis, we enrolled primigravid women at a Malawian government antenatal clinic and followed them through delivery. One hundred and thirteen women (71 per cent) out of 159 women followed through delivery were parasitaemic at least once. Mean placental haemozoin concentrations were significantly higher in women with delivery parasitaemias (223 ng/mg protein) than in women who never had a detectable parasitaemia (43 ng/mg protein; P<0.05), but were not significantly higher in women who were parasitaemic only during the antenatal period (67 ng/mg protein). Haemozoin was not associated with preterm delivery (PTD) or intrauterine growth retardation (IUGR) (P -values, 0.307-0.787). Thus, placental haemozoin is associated with malaria infection at the time of delivery and does not seem to be associated with poor birth outcome.

Patterns of outcome measurement in Parkinson's disease clinical trials

The study examines the pattern of use and clinimetric properties of clinical endpoints used in randomized trials for Parkinson's disease (PD). Randomized drug trials for PD were identified through a Medline search conducted from January 1966 until August 1998. The endpoints used in these trials were abstracted. Reports examining the clinimetric properties of the disease-specific scales used in these trials were also abstracted. Data regarding the consistency, accuracy, discrimination and feasibility of scales used in at least 10% of trials were determined. One hundred and thirty-seven articles met the inclusion criteria; 70.8% of trials used some clinical scale for PD as an endpoint. The Unified Parkinson's Disease Rating Scale (UPDRS) was the most commonly used scale (32.8%). Factors independently associated with the use of the UPDRS included: the study location in the US, mean age of subjects over 62.7 years and publication after 1994. The UPDRS was more thoroughly studied and superior in most clinimetric domains compared to scales developed earlier. Few studies included generic health status (2.9%) or cognitive measures (16.8%) as secondary endpoints. There have been definite improvements in the area of disease-specific measurement in PD trials since the introduction of the UPDRS. The results of studies that used instruments with poor or unreported clinimetric properties should be critically interpreted.

Identification of three alternative first exons and an intronic promoter of human PDE5A gene

In the accompanying paper we present evidence for the existence of three PDE5A isoforms that differed only in the 5' end of the mRNAs. In this paper we present evidence that the three isoform-specific 5' ends were encoded by three alternative first exons that were arranged in the order of A1-A3-A2. Because the isoform-specific mRNAs could be transcribed from individual promoters, DNA fragments of the two intronic regions (A1-A3 and A3-A2) were tested for possible promoter activities. The intron between A1- and A3-specific exons did not exhibit any promoter activities even in smooth muscle cells that expressed the A3 isoform (see accompanying paper). In contrast, the intron between A3- and A2-specific exons had promoter activities in PDE5A2-expressing COS-7 and smooth muscle cells. This intronic promoter was bound by transcription factors AP-2 and Sp1, but not by AP-1, as shown by DNase I footprint analysis. However, the sequence bound by AP-2 (5'-GGGAAACGCTCGCGGGAGAGTTGG) is unusual in that it bears little resemblance to the consensus AP-2-binding sequence.

Expression of three isoforms of cGMP-binding cGMP-specific phosphodiesterase (PDE5) in human penile cavernosum

Inhibition of cGMP-specific phosphodiesterase type V (PDE5) has been shown to improve penile erection in patients with erectile dysfunction. We report here the cloning of three PDE5 isoforms from human penile tissues. Two of the isoforms were identical to PDE5A1 and PDE5A2, respectively, which had been isolated from nonpenile tissues. The third isoform was novel and hence called PDE5A3. The deduced amino acid sequence of PDE5A3 was the same as the C-terminal 823-residue sequence of PDE5A1 and PDE5A2. While PDE5A1 and A2 isoforms were expressed in all tissues examined, the A3 isoform was confined to tissues with a smooth muscle or cardiac muscle component. When expressed in COS-7 cells, PDE5A1, A2, and A3 isoforms had similar cGMP-catalytic activities with K(m) of 6.2, 5.75, and 6.06 microM, respectively. Their cGMP-catalytic activities were inhibited by zaprinast with IC(50) values of 3.2 microM, 1.3 microM, and 1.6 microM, respectively, and by sildenafil with IC(50) of 28, 14, and 13 nM, respectively.

Degradation of cyclin A does not require its phosphorylation by CDC2 and cyclin-dependent kinase 2

Many cyclins are degraded by the ubiquitination/proteasome pathways involving the anaphase-promoting complex and SCF complexes. These degradations are frequently dependent on phosphorylation by cyclin-dependent kinases (CDKs), providing a self-limiting mechanism for CDK activity. Here we present evidence from in vitro and in vivo assay systems that the degradation of human cyclin A can be inhibited by kinase-inactive mutants of CDK2 and CDC2. One obvious interpretation of these results is that like other cyclins, CDK-dependent phosphorylation of the cyclin A may be involved in cyclin A degradation. Our data indicated that CDK2 can phosphorylate cyclin A on Ser-154. Site-directed mutagenesis of Ser-154 abolished the phosphorylation by recombinant CDK2 in vitro and the majority of cyclin A phosphorylation in the cell. Activation of CDK2 and binding to SKP2 or p27(KIP1) were not affected by the phosphorylation of Ser-154. Surprising, in marked contrast to cyclin E, where phosphorylation of Thr-380 by CDK2 is required for proteolysis, degradation of cyclin A was not affected by Ser-154 phosphorylation. It is likely that the stabilization of cyclin A by the kinase-inactive CDKs was mainly due to a cell cycle effect. These data suggest an important difference between the regulation of cyclin A and cyclin E.

The effect of pregnancy and delivery on the function and ultrastructure of the rat bladder and urethra

OBJECTIVE

To examine the effect of pregnancy and delivery on the function and ultrastructure of the bladder and urethra in rats. Material and methods The study comprised six virgin and 18 pregnant rats; both groups underwent cystometry (at the 19th day of gestation, and 2 days and 6 weeks after parturition). Tissues from the bladder and urethra were collected for electron microscopy, western blotting and immunostaining for caveolin-1 and caveolin-3.

RESULTS

The bladder capacity was greater and the modified leak-point pressures lower in pregnant and 2-day postpartum rats than in virgin and 6-week postpartum rats. The residual volume was significantly higher in the pregnant group. Electron microscopy showed more sarcolemmal caveolae in the smooth muscle cells of both the bladder and urethra of virgin rats than in the other groups. Lipid droplets and subsarcolemmal mitochondria accumulated in pregnant and 2-day postpartum rats. Caveolin-1 protein was detected in the cytoplasmic membrane of urethra and bladder smooth muscle cells. Caveolin-3 was detected in the membrane of striated muscle in the intrinsic sphincter. Western blotting showed increased caveolin-1 protein expression in the bladder and urethra of 2-day postpartum rats; in contrast, levels of caveolin-1 were lower in pregnant rats than in virgin and 6-week postpartum rats.

CONCLUSION

s During pregnancy there was a significant decrease in sarcolemmal caveolae and caveolin-1 in the smooth muscle cells of the rat bladder and urethra. The changes in caveolae and the membrane protein caveolin may play a role in the functional changes associated with pregnancy and after delivery.

Upregulation of L-plastin gene by testosterone in breast and prostate cancer cells: identification of three cooperative androgen receptor-binding sequences

L-Plastin is normally a leukocyte-specific actin-binding protein; it is also expressed in the majority of human cancer cell lines that are derived from many types of solid tumors. We have previously reported the isolation of the L-plastin gene promoter, in which we identified several potential steroid receptor-binding sequences. We now obtained evidence that L-plastin gene expression was positively regulated by testosterone in androgen receptor (AR)-positive prostate and breast cancer cells. DNase I footprint analysis identified three AR-binding elements (ARE) located in a 545-bp region approximately 1.1 kb upstream from the transcription initiation site. However, each of these three AREs exhibited very little testosterone/AR-responsive enhancer activities toward a test promoter (of the thymidine kinase gene) when tested in MCF-7 breast cancer cells. Their testosterone/AR responsiveness became evident only when two or three of them were combined. In PC-3 prostate cancer cells, cooperation among L-plastin AREs was still evident although individually they had moderate levels of testosterone/AR responsiveness. Thus, the three L-plastin AREs, despite their imperfect sequences compared with the consensus ARE, could cooperate with each other to become a potent testosterone/AR-responsive unit, which was likely responsible for the inducibility of the L-plastin gene by testosterone.

MDM2 and MDMX inhibit the transcriptional activity of ectopically expressed SMAD proteins

Transforming growth factor-beta (TGF-beta) inhibits cell proliferation in many cell types, and acquisition of TGF-beta resistance has been linked to tumorigenesis. One class of proteins that plays a key role in the TGF-beta signal transduction pathway is the SMAD protein family. MDM2, a key negative regulator of p53, has recently been shown to suppress TGF-beta-induced growth arrest in a p53-independent manner. Here we show that MDM2 and the structurally related protein MDMX can inhibit the transcriptional activity of ectopically expressed SMAD1, SMAD2, SMAD3, and SMAD4. Immunofluorescence staining indicated that ectopically expressed SMAD4 was present in both the cytoplasm and nucleus, and MDM2 and NIDMX were localized mainly to the nucleus and cytoplasm, respectively. When SMAD4 was coexpressed with either MDM2 or MDMX, nuclear accumulation of SMAD4 was strikingly inhibited. We have no evidence that SMAD4 binds directly to MDM2 or MDMX; hence, the inactivation and nuclear exclusion of SMAD4 by MDM2/MDMX may involve other indirect mechanisms.

Frequency of meiotic trisomy depends on involved chromosome and mode of ascertainment

Although maternal meiotic errors predominate in most studies of nonmosaic trisomy, studies of trisomy ascertained through confined placental mosaicism (CPM) have shown a high rate of somatic errors. However, origin of trisomy of many of the chromosomes involved in CPM has not been evaluated previously in cases ascertained through spontaneous abortions (SAs). Therefore, it was impossible to determine if the relative lack of meiotic errors in trisomy-CPM cases was a characteristic of the specific chromosome involved or due simply to ascertainment through a mosaic state. In the present study, parental and meiotic/somatic stages of origin of trisomy were determined in 89 SAs involving trisomy of chromosomes 2, 4 to 10, 12, 15, 17, and 20. Comparisons were then made to origin of trisomy in cases of confined and generalized trisomy mosaicism. Although somatic errors are generally more common in mosaic cases, this depends on the specific chromosome involved. The results suggest that there are chromosome-specific differences in the relative frequency of somatic chromosome gain or loss and/or the ability of an early somatic loss of one chromosome from a trisomic conceptus to "rescue" the pregnancy. As mean maternal age was less in the somatic than meiotic origin cases (P < 0.01), the age distribution of the study population should also influence the probability of detecting a somatic error. No phenotypic differences were apparent when cases were subdivided based on either parent or stage of origin of the trisomy.