[Characteristics of the manifest and latent components of the hepatitis A epidemic process in cities of Russia]

Seroepidemiological study of hepatitis A (HA) morbidity was carried out in three Russian cities, with different levels of HA morbidity. The study included the analysis of HA morbidity for 22 years, the determination of antibodies to HA virus (anti-HAV) in 2,958 healthy persons aged 0-12 months to 40 years and older. In one of the cities 7 isolates of HA virus were obtained from unrelated sources and the genotypes of the virus were determined. The study revealed that the frequency of seropositive cases among persons of different ages correlated with the level and prolonged dynamics of HA morbidity. According to the occurrence of anti-HAV, such cities as St. Petersburg, Rostov-on-Don and Yakutsk may be at present classified as territories, moderately endemic in HA. At the same time in the 90 s the epidemic situation in HA was more favorable in Rostov-on-Don than in two other cities. The suggestion was made that a high proportion of seropositive persons among the population of St. Perersburg was linked with an almost twofold rise in HA morbidity in 1993-1995 caused by genotype 1 of the virus. Seroepidemiological studies in HA during the period of a drop in morbidity acquire special importance in the surveillance and control system of this infection.

A novel neural network technique for analysis and classification of EM single-particle images

We propose a novel self-organizing neural network for the unsupervised classification of electron microscopy (EM) images of biological macromolecules. The radical novelty of the algorithm lies in its rigorous mathematical formulation that, starting from a large set of possibly very noisy input data, finds a set of "representative" data items, organized onto an ordered output map, such that the probability density of this set of representative items resembles at its possible best the probability density of the input data. In a way, it summarizes large amounts of information into a concise description that rigorously keeps the basic pattern of the input data distribution. In this application to the field of three-dimensional EM of single particles, two different data sets have been used; one comprised 2458 rotational power spectra of individual negative stain images of the G40P helicase of Bacillus subtilis bacteriophage SPP1, and the other contained 2822 cryoelectron images of SV40 large T-antigen. Our experimental results prove that this technique is indeed very successful, providing the user with the capability of exploring complex patterns in a succinct, informative, and objective manner. The above facts, together with the consideration that the integration of this new algorithm with commonly used software packages is immediate, prompt us to propose it as a valuable new tool in the analysis of large collections of noisy data.

Serious adverse events after measles-mumps-rubella vaccination during a fourteen-year prospective follow-up

BACKGROUND

Several disorders have been attributed to measles-mumps-rubella (MMR) vaccination during the past decade. The aim of this prospective follow-up study was to identify serious adverse events causally related to MMR vaccination.

METHODS

When the MMR vaccination program was launched in Finland in 1982, a countrywide surveillance system was set up to detect serious adverse events associated with MMR. To obtain detailed case histories vaccinees' clinical charts were reviewed. Serum samples were analyzed to trace concurrent infections.

SETTING

All hospitals and health centers in Finland from 1982 through 1996.

RESULTS

Immunization of 1.8 million individuals and consumption of almost 3 million vaccine doses by the end of 1996 gave rise to 173 potentially serious reactions claimed to have been caused by MMR vaccination. In all, 77 neurologic, 73 allergic and 22 miscellaneous reactions and 1 death were reported, febrile seizure being the most common event. However, 45% of these events proved to be probably caused or contributed by some other factor, giving an incidence of serious adverse events with possible or indeterminate causal relation with MMR vaccination of 5.3 per 100,000 vaccinees or 3.2 per 100,000 vaccine doses.

CONCLUSIONS

Causality between immunization and a subsequent untoward event cannot be estimated solely on the basis of a temporal relation. Comprehensive analysis of the reported adverse reactions established that serious events causally related to MMR vaccine are rare and greatly outweighed by the risks of natural MMR diseases.

Mumps and rubella eliminated from Finland

Many countries use trivalent measles-mumps-rubella (MMR) vaccine for their mumps and rubella immunization programs. In Finland, a national 2-dose MMR vaccination program for children, free of charge and on a voluntary basis, was launched in 1982. Serological confirmation of all suspected cases of mumps and rubella has been required since 1987. Despite intensive surveillance, no persistent sequelae or deaths attributable to vaccination have been detected. Indigenous mumps and rubella were eliminated in 1996, but 4 imported cases of mumps and 2 of rubella occurred from 1997 to 1999. Lack of secondary cases indicates sufficient immunity in the community. Compared with an epidemic year, up to thousands of cases of mumps meningoencephalitis and orchitis and around 50 cases of congenital rubella syndrome are now avoided annually. A 2-dose vaccine regimen in children during the last 17 years (1983-1999) has interrupted circulation of the target viruses entirely. Finland is the first country documented to be free of indigenous mumps and rubella (measles was eliminated in 1996). Despite the ongoing possibility of imported disease, major outbreaks probably can be avoided by maintaining high vaccination coverage and the 2-dose policy. JAMA. 2000;284:2643-2647.

Modeling of the in vivo antinociceptive interaction between an opioid agonist, (+)-O-desmethyltramadol, and a monoamine reuptake inhibitor, (-)-O-desmethyltramadol, in rats

The pharmacokinetic-pharmacodynamic (pk-pd) characterization of the in vivo antinociceptive interaction between (+)-O-desmethyltramadol [(+)-M1] and (-)-O-desmethyltramadol [(-)-M1], main metabolites of tramadol, was studied in three groups of rats. (+)-M1 and (-)-M1, both with different pd properties, were studied under steady-state and nonsteady-state conditions, depending on the group. Plasma drug concentration and antinociception were simultaneously measured in each animal by using an enantioselective analytical assay and the tail-flick test, respectively. Respiratory depression also was evaluated in another series of experiments according to the same experimental conditions. The pk behavior was similar for both enantiomers and no significant (P >.05) interaction between two compounds was found at this level. However, a significant (P <.01) potentiation in the antinociceptive effect elicited by (+)-M1 was found during and after (-)-M1 administration. The pd model used to describe the time course of the antinociception in the presence of (+)-M1, (-)-M1, or both is based on previous knowledge of the compounds and includes the following: 1) an effect compartment model to account for the opioid effect of (+)-M1, and 2) an indirect response model accounting for the release of noradrenaline (NA) caused by (+)-M1, and the inhibition of the NA reuptake due to the action of (-)-M1. The model predicts a positive contribution to antinociception of the predicted increasing levels of NA. No significant (P >.05) respiratory effects were seen during or after (+)-M1 and (-)-M1 administration.

The seroepidemiology of rubella in western Europe

Most of the countries in western Europe have now implemented mass infant rubella immunization programmes, instead of or in addition to selective vaccination in order to achieve the elimination of congenital rubella syndrome. The European countries Denmark, England and Wales, Finland, France, Germany, Italy and the Netherlands undertook large, national serological surveys collecting several thousand serum specimens during 1994-8. Antibodies against rubella virus were detected by a variety of enzyme immuno-assays. Comparability of the assay results was achieved by a standardized methodology. The age- and sex-stratified serological results were related to the schedules, coverage of rubella vaccination and the incidence in these countries. The results show widely differing levels of immunity to rubella both in the general population and in the specific age groups of males and females. A low rate (< 5%) of susceptibles in childhood and adolescents of both sexes was obtained only in Finland and the Netherlands. Countries such as Italy with only moderate coverage for the infant immunization programme currently have both high susceptibility levels in the general population and in the at-risk population. The likelihood is of continued epidemics of rubella with cases of congenital rubella syndrome. The continued implementation of selective vaccination will help to offset the impact of this ongoing transmission and to protect women on reaching childbearing age.

[Evaluation of commercial equipment used in blood banks in Córdoba for the detection of anti-HTLV-I/II antibodies]

In order to assess the efficiency of currently used screening tests, Abbott HTLV-I/HTLV-II EIA, Vironostika HTLV-I/II Organon Teknika, Particle Agglutination (PA) assay Serodia Fujirebio Inc. (Tokyo, Japan) for HTLV-I/II antibody detection in blood donors samples, a panel of 100 sera from different blood banks of Córdoba city were studied. An "in house" indirect immunofluorescence assay (IFA) was used as reference test. The correlation rates were: 66% for Abbott HTLV-I/HTLV-II EIA, 97% for Vironostika HTLV-I/II Organon Teknika EIA and 99% for PA Serodia. Vironostika HTLV-I/II Organon Teknika EIA and PA Serodia assay proved to be more reliable for HTlV-I/II antibody screening in blood donors from Córdoba, yielding a very low rate of false positive results as compared with Abbot HTLV-I/HTLV-II EIA.

US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs

The diagnosis of nerve entrapment at osteofibrous tunnels relies primarily on clinical and electrodiagnostic findings. Recently, the refinement of high-frequency broadband transducers with a range of 5-15 MHz, sophisticated focusing in the near field, and sensitive color and power Doppler technology have improved the ability to evaluate peripheral nerve entrapment in osteofibrous tunnels with ultrasonography (US). In the upper limb, osteofibrous tunnels amenable to US examination include the carpal tunnel for the median nerve and the cubital and Guyon tunnels for the ulnar nerve. In the lower limb, these tunnels include the fibular neck for the common peroneal nerve, the tarsal tunnel for the posterior tibial nerve, and the intermetatarsal spaces for the interdigital nerves. High-resolution US allows direct imaging of the involved nerves, as well as documentation of changes in nerve shape and echotexture that occur in compressive syndromes. A spectrum of extrinsic causes of entrapment, such as tenosynovitis, ganglia, soft-tissue tumors, bone and joint abnormalities, and anomalous muscles, can also be diagnosed with US. With continued experience, it is likely that this technique will be increasingly used to evaluate nerve entrapment syndromes.

The European Sero-Epidemiology Network: standardizing the enzyme immunoassay results for measles, mumps and rubella

The ESEN (European Sero-Epidemiology Network) project was established to harmonize the seroepidemiology of five vaccine preventable infections including measles, mumps and rubella in eight European countries. This involved achieving comparability both in the assay results from testing in different centres and also sampling methodology. Standardization of enzyme immunoassay results was achieved through the development of common panels of sera by designated reference centres. The panels were tested at the reference laboratory and then distributed to each participating laboratory for testing using their routine methods. Standardization equations were calculated by regressing the quantitative results against those of the reference laboratory. Our study found large differences in unitage between participants, despite all using an EIA method standardized against an international or local standard. Moreover, our methodology adjusted for this difference. These standardization equations will be used to convert the results of main serosurvey testing into the reference country unitage to ensure inter-country comparability.

Duration of rubella immunity induced by two-dose measles, mumps and rubella (MMR) vaccination. A 15-year follow-up in Finland

A national two-dose vaccination program with a combined measles, mumps and rubella (MMR-II) vaccine was introduced in Finland, in 1982, immunizing children at the ages of 14-18 months and 6 years. Antibody levels were determined from serial samples from a group of originally 350 children during 15 years. The latest samples were taken 15.5 years after the first vaccination and 70% of the children could still be reached. The aim of this study was to determine the kinetics of rubella antibodies induced by the MMR-II vaccine in these individuals. Rubella antibodies were analyzed from three different cohorts: Group I seronegative children (n=166) vaccinated at 14-18 months and 6 years, Group II seronegative children (n=139) and Group III seropositive children (n=16) vaccinated at 6 and 11-13 years. Samples collected 0-9 years after vaccination were analyzed by hemolysis-in-gel (HIG) and later samples by enzyme immunoassay (EIA) techniques. The primary vaccination induced 100% seropositivity in vaccinees with a mean zone diameter of 10 (+/-1.3), 10.2 (+/-1.1) and 11.5 (+/-0.9) mm, in Groups I, II and III, respectively. The seropositivity rate was still high at 15 years, 99%, 100% and 100% with the geometric mean titer 23, 46 and 105 IU/ml, respectively. At 15 years, antibody levels <15 IU/ml which is the suggested protective level, were found in 31, 9 and 0% of children in Groups I, II and III, respectively. Because almost a third of the individuals in Group I now, at the age of 17 years, had low levels of rubella antibodies, it is possible that rubella infections may re-emerge during pregnancy. A careful surveillance including serological follow-up is therefore very important.

Sex hormone-binding globulin as a marker for hyperinsulinemia and/or insulin resistance in obese children

OBJECTIVE

A relationship between hyperinsulinemia and decreased serum sex hormone-binding globulin (SHBG) has been described in adults. We evaluated the usefulness of SHBG as an index of hyperinsulinemia and/or insulin resistance in obese children (aged 6-9 years) of both sexes and its possible influence on the androgenic status.

DESIGN

We carried out a cross-sectional study of cases and controls. We studied 61 obese children (22 males, 39 females) with body mass index (BMI) superior to the 90(th) percentile and a control group of age- and sex-matched non-obese children. We measured serum glucose, insulin, TSH, free thyroxine, 17beta-estradiol, testosterone and SHBG. Also, we correlated these parameters with anthropometric measures.

RESULTS

The obese group presented significantly elevated levels of insulin (P=0.001) and insulin/glucose ratio (P=0.0012) compared with the control group. SHBG (P=0.0001) and testosterone (P=0.0169) levels were significantly lower than those in the non-obese group. We did not find any difference in the free androgen index (FAI). Fasting insulin (r=-0.4512; P<0.001), BMI (r=-0.3185; P<0.05) and testosterone (r=-0.3705; P<0.01) were inversely correlated with SHBG concentration. According to multivariate analyses, insulin was the only independent predictor factor for serum SHBG concentration in the obese group (r partial=0.1280; P=0.0171).

CONCLUSIONS

In summary, at this age there is a strong relationship between insulin and SHBG. The changes in SHBG levels of the obese group did not affect FAI and, therefore, they did not cause changes in the androgenic status. Our data support the role of insulin in the regulation of serum SHBG levels.

[Ultrasonography features of the diaphragmatic crura: normal anatomy and its variants]

PURPOSE

To report the various US patterns of the diaphragmatic crura and the changes occurring during the different phases of respirations. The diaphragm has two US patterns: the central membranous part appears highly reflective while the posterior, upper and lateral muscular portions are hypoechoic and thick. The crura can sometimes appear quite bulky, which appearance is easy to misinterpret.

MATERIAL AND METHODS

We carried out a three-stage work: first we reviewed the US examinations of 23 subjects with a nodular appearance of the posteromedial bundles and studied the changes in thickness during respiration. Second we studied the diaphragmatic crura in 30 subjects aged 18-71 years, 15 men and 15 women. We used a commercially available unit with sector and convex 3.5 MHz probes at baseline and during breath hold and acquired multiple parasagittal and transverse scans. The crura thickness was measured in all patients. Last, we studied the diaphragmatic regions of 10 patients with right pleural effusion and of 8 patients with associated ascites and pleural effusion using 2.0-5.0 MHz convex phased-array transducers.

RESULTS

We found focal thickening of the crura in 11 of 23 patients with US findings of diaphragmatic nodules, but only in deep inspiration. The thickening was 1.5-2.2 cm long and maximum thickness was 10 mm. In the other 12 subjects we found 9 small lobules in the right and 3 in the left crus. In the anatomic study, we observed a 3-band appearance of the diaphragmatic crura, probably referable to muscle bundles, in 30 subjects on sagittal images, in 12 on coronal images and in 28 on anterior transverse images. The diaphragmatic crura were identified in 26 subjects only. The left posterior crus was identified in 29 subjects on left coronal images and in 15 on anterior transverse images; it was demonstrated on anterior sagittal images in close proximity to the aorta in only 4 subjects. Right crus thickness, measured on sagittal scans, ranged 3-10 mm in deep inspiration and 1-4 mm in expiration while the left crus was 3-6 mm in inspiration and 1-2 mm in expiration. The length of the right crus, studied in the preaortic portion, ranged from 7 cm in deep inspiration to 9.7 cm in expiration while the left one was 6.5 to 8.8 cm. The right lateral diaphragmatic bundles were seen in 28 subjects only on repeated subcostal oblique scans and the the left ones in 11 subjects only. Finally the thin anterior bundles were shown on parasagittal images in 13 cases in the right side and in 2 in the left. A 2-band appearance of the diaphragm was seen in 10 patients with pleural effusion and in 8 patients with associated ascites. A single band was found only in the tendinous portion of the diaphragm.

DISCUSSION AND CONCLUSIONS

US is presently considered the imaging method of choice in the assessment of changes in thickness and length of the diaphragmatic crura. These structures have different US patterns and can sometimes appear quite bulky and thus be easily mistaken for other anatomic or abnormal structures; orthogonal scans may be required for the differential diagnosis.

Topology of the components of the DNA packaging machinery in the phage phi29 prohead

Chromosome condensation inside dsDNA viral particles is a complex process requiring the coordinated action of several viral components. The similarity of the process in different viral systems has led to the suggestion that there is a common underlying mechanism for DNA packaging, in which the portal vertex or connector plays a key role. We have studied the topology of the packaging machinery using a number of antibodies directed against different domains of the connector. The charged amino-terminal, the carboxyl-terminal, and the RNA binding domain are accessible areas in the connector assembled into the prohead, while the domains corresponding to the 12 large appendages of the connector are buried inside the prohead. Furthermore, while the antibodies against the carboxyl and amino-terminal do not affect the packaging reaction, incubation of proheads with antibodies against the RNA binding domain abolishes the packaging activity. The comparison of the three-dimensional reconstructions of bacteriophage phi29 proheads with proheads devoid of their specific pRNA by RNase treatment shows that this treatment removes structural elements of the distal vertex of the portal structure, suggesting that the pRNA required for packaging is located at the open gate of the channel in the narrow side of the connector.

Infantile obesity: a situation of atherothrombotic risk?

Obesity is a major risk factor for cardiovascular disease frequently associated with hypertension, dyslipidemia, and diabetes. In recent years, alterations in the hemostatic system have been added to these dysfunctions. We analyzed some of these alterations in coagulation and fibrinolysis in obese children (6 to 9 years old) of both sexes. We studied 61 obese children (mean body mass index [BMI], 22.35 kg/m2; 95% confidence interval [CI], 21.82 to 22.87) and 70 non-obese children (mean BMI, 16.58 kg/m2; 95% CI, 16.24 to 16.93) as a control group. The obese subjects presented significantly elevated values for insulin (P < .001), tissue-plasminogen activator ([t-PA] P < .001), plasminogen activator inhibitor-1 ([PAI-1] P < .001), and fibrinogen (P < .001) with respect to the control group. We found no significant differences in the concentration of glucose and fragment 1 + 2 of prothrombin (F1 + 2). In the obese subjects, insulin, PAI-1, and F1 + 2 were positively correlated with the BMI. On the other hand, t-PA was correlated with insulin and PAI-1 but not with the BMI. Therefore, in the obese children, there was an increment of the risk factors for cardiovascular disease.

Pharmacokinetic-pharmacodynamic modeling of the antinociceptive effects of main active metabolites of tramadol, (+)-O-desmethyltramadol and (-)-O-desmethyltramadol, in rats

The pharmacokinetics and pharmacodynamics of the two main metabolites of tramadol, (+)-O-desmethyltramadol and (-)-O-desmethyltramadol, were studied in rats. Pharmacodynamic endpoints evaluated were respiratory depression, measured as the change in arterial blood pCO(2), pO(2), and pH levels; and antinociception, measured by the tail-flick technique. The administration of 10 mg/kg (+)-O-desmethyltramadol in a 10-min i.v. infusion significantly altered pCO(2), pO(2), and pH values in comparison with baseline and lower-dose groups (P <.05). However, 2 mg/kg administered in a 10-min i.v. infusion was enough to achieve 100% antinociception without respiratory depression. Moreover, the beta-funaltrexamine pretreatment completely eliminated the antinociception of the 2-mg/kg dose, suggesting that such an effect is due to mu-opioid receptor activation. To describe and adequately characterize the in vivo antinociceptive effect of the drug, (+)-O-desmethyltramadol was given at different infusion rates of varying lengths (10-300 min). Pharmacokinetics was best described by a two-compartmental model. The time course of response was described using an effect compartment associated with a linear pharmacodynamic model. The estimates of the slope of the effect versus concentration relationship were significantly decreased (P <. 05) as the length of infusion was increased, suggesting the development of tolerance. Doses of up to 8 mg/kg (-)-O-desmethyltramadol given in 10-min i.v. infusion did not elicit either antinociception in the tail-flick test or respiratory effects. These in vivo results are in accordance with the opiate and nonopiate properties reported for these compounds in several in vitro studies.

An investigation of the clinical use of the house-tree-person projective drawings in the psychological evaluation of child sexual abuse

Identification and evaluation of child sexual abuse is an integral task for clinicians. To aid these processes, it is necessary to have reliable and valid psychological measures. This is an investigation of the clinical validity and use of the House-Tree-Person (HTP) projective drawing, a widely used diagnostic tool, in the assessment of child sexual abuse. HTP drawings were collected archivally from a sample of sexually abused children (n = 47) and a nonabused comparison sample (n = 82). The two samples were grossly matched for gender, ethnicity, age, and socioeconomic status. The protocols were scored using a quantitative scoring system. The data were analyzed using a discriminant function analysis. Group membership could not be predicted based on a total HTP score.

Secondary measles vaccine failures identified by measurement of IgG avidity: high occurrence among teenagers vaccinated at a young age

Failure to seroconvert (primary vaccine failure) is believed to be the principal reason (approx. > 95%) why some vaccinees remain susceptible to measles and is often attributed to the persistence of maternal antibodies in children vaccinated at a young age. Avidity testing is able to separate primary from secondary vaccine failures (waning and/or incomplete immunity), but has not been utilized in measles epidemiology. Low-avidity (LA) and high-avidity (HA) virus-specific IgG antibodies indicate primary and secondary failure, respectively. Measles vaccine failures (n = 142; mean age 10.1 years, range 2-22 years) from an outbreak in 1988-9 in Finland were tested for measles-virus IgG avidity using a protein denaturating EIA. Severity of measles was recorded in 89 failures and 169 non-vaccinees (mean age 16.2 years, range 2-22 years). The patients with HA antibodies (n = 28) tended to have clinically mild measles and rapid IgG response. Among failures vaccinated at < 12, 12-15 and > 15 months of age with single doses of Schwarz-strain vaccine in the 1970s, 50 (95% CI 1-99), 36 (CI 16-56) and 25% (CI 8-42) had HA antibodies, respectively. When a single measles, mumps and rubella (MMR) vaccine had been given after 1982 at 15 months of age, only 7% (CI 0-14) showed HA antibodies. Omitting re-vaccinees and those vaccinated at < 15 months, Schwarz-strain recipients had 3.6 (CI 1.1-11.5) higher occurrence of HA responses compared to MMR recipients. Apart from one municipality, where even re-vaccinees had high risk of primary infection, 89% (CI 69 to approximately 100) of the infected re-vaccinees had an HA response. Secondary measles-vaccine failures are more common than was more previously thought, particularly among individuals vaccinated in early life, long ago, and among re-vaccinees. Waning immunity even among individuals vaccinated after 15 months of age, without the boosting effect of natural infections should be considered a relevant possibility in future planning of vaccination against measles.

Large T-antigen double hexamers imaged at the simian virus 40 origin of replication

The initial step of simian virus 40 (SV40) DNA replication is the binding of the large tumor antigen (T-Ag) to the SV40 core origin. In the presence of Mg(2+) and ATP, T-Ag forms a double-hexamer complex covering the complete core origin. By using electron microscopy and negative staining, we visualized for the first time T-Ag double hexamers bound to the SV40 origin. Image processing of side views of these nucleoprotein complexes revealed bilobed particles 24 nm long and 8 to 12 nm wide, which indicates that the two T-Ag hexamers are oriented head to head. Taking into account all of the biochemical data known on the T-Ag-DNA interactions at the replication origin, we present a model in which the DNA passes through the inner channel of both hexamers. In addition, we describe a previously undetected structural domain of the T-Ag hexamer and thereby amend the previously published dimensions of the T-Ag hexamer. This domain we have determined to be the DNA-binding domain of T-Ag.

Alpha 1-acid glycoprotein (AAG) and serum protein binding of methadone in heroin addicts with abstinence syndrome

OBJECTIVE

To quantify serum protein levels and protein-binding of methadone in vitro in heroin-addicted patients showing objective signs of heroin abstinence.

SUBJECTS AND METHODS

Serum samples were obtained from patients (n = 27) hospitalized to participate in a methadone detoxification program and from healthy volunteers (n = 21). The severity of the abstinence syndrome was assessed before blood sampling using a standardized scale. Concentrations of both albumin and alpha1-acid glycoprotein (AAG) were measured in all serum samples. The protein-binding of alpha1-methadone was determined by the ultrafiltration technique and the unbound concentration was measured by liquid scintillation counting.

RESULTS

The mean of the AAG concentrations was significantly increased in patients showing signs of withdrawal while the albumin concentrations did not change. Also, the unbound methadone was significantly decreased in this group when compared to the control. A positive correlation (Pearson r = 0.48; p < 0.005) indicates that AAG levels rise during abstinence as the score of withdrawal symptoms increases. Additionally, pooled data from all individuals show the binding of methadone to be related to AAG (r = 0.46; p < 0.05) levels and not to albumin.

CONCLUSIONS

The observed changes in protein-binding in abstinence individuals suggest the need for increased dosages of methadone when such patients are treated. Levels of AAG or protein-binding appear to be components of the interindividual variance observed in the response to methadone treatment, hence these variables could be included in future kinetic and dynamic studies.

Characterization of ATP and DNA binding activities of TrwB, the coupling protein essential in plasmid R388 conjugation

TrwB is the conjugative coupling protein of plasmid R388. TrwBDeltaN70 contains the soluble domain of TrwB. It was constructed by deletion of trwB sequences containing TrwB N-proximal transmembrane segments. Purified TrwBDeltaN70 protein bound tightly the fluorescent ATP analogue TNP-ATP (K(s) = 8.7 microM) but did not show measurable ATPase or GTPase activity. A single ATP binding site was found per TrwB monomer. An intact ATP-binding site was essential for R388 conjugation, since a TrwB mutant with a single amino acid alteration in the ATP-binding signature (K136T) was transfer-deficient. TrwBDeltaN70 also bound DNA nonspecifically. DNA binding enhanced TrwC nic cleavage, providing the first evidence that directly links TrwB with conjugative DNA processing. Since DNA bound by TrwBDeltaN70 also showed increased negative superhelicity (as shown by increased sensitivity to topoisomerase I), nic cleavage enhancement was assumed to be a consequence of the increased single-stranded nature of DNA around nic. The mutant protein TrwB(K136T)DeltaN70 was indistinguishable from TrwBDeltaN70 with respect to the above properties, indicating that TrwB ATP binding activity is not required for them. The reported properties of TrwB suggest potential functions for conjugative coupling proteins, both as triggers of conjugative DNA processing and as motors in the transport process.

Do magnesium ions influence barium mucosal coating of the large bowel?

The aim of the present study was to verify whether the presence of magnesium in the colon lumen at the time of the double-contrast barium enema (DCBE) examination changes the quality of barium mucosal coating. The two members of 38 pairs of patients undergoing DCBE with a standardised technique were randomly subjected to bowel preparation with sennosides and magnesium sulphate, or sennosides and sodium sulphate. Mucosal coating, residual fluid and colon cleansing were assessed independently by three radiologists. The null hypothesis was tested by means of Wilcoxon's signed-rank test. Barium mucosal coating was judged to be better in the members to whom magnesium sulphate was administered (p = 0.0007). There was no difference in the amount of residual fluids (p = 0.3198). Colon cleansing was judged to be better in the members to whom sodium sulphate was administered (p = 0.0166). These results demonstrate, in a simple way, that magnesium ions increase barium coating of the colon mucosa in vivo. The underlying mechanisms (increase in viscosity of barium suspension through water subtraction owing to the hydrophilism of magnesium ions, or interactions with the polysaccharide additives) need further investigation. A first clinical application could be the integration of magnesium ions in a newly designed isotonic electrolyte solution containing polyethylene glycol for the oral colon wash-out.

Domain architecture of the bacteriophage phi29 connector protein

Viral connectors are essential components of the DNA packaging machinery. They interact with nucleic acids and other viral components to translocate DNA inside the viral head. We have attempted to locate the different structural and functional domains of the phage Phi29 connector using a combination of approaches to generate different antigenic probes. Complexes of native connectors with either monoclonal or monospecific antibodies were studied by immunoelectron microscopy and image averaging methods. The data were merged in a model of the connector domain structure at 2-3 nm resolution. This epitope mapping provides a general outline of the folding architecture of the connector polypeptide, following a complicated threading that places the amino and carboxyl-terminals in close alignment in the narrower domain at 2-3 nm from the top of the connector. The appendages are built up by a long and highly immunogenic sequence (amino acid residues 153 to 206). The RNA binding domain forms part of the top of the narrow conical area of the connector, a flexible region that undergoes structural changes during viral morphogenesis. The DNA binding domain is located not far away, 2-3 nm below, in the outer side of the narrow conical part. The precise location of the functional domains of the connector, as well as their relative positions provide the first experimental framework for understanding the connector function.

Enantiomeric separation of tramadol and its active metabolite in human plasma by chiral high-performance liquid chromatography: application to pharmacokinetic studies

A sensitive and stereoselective high-performance liquid chromatographic assay for the quantitative determination of the analgesic tramadol and O-demethyltramadol, an active metabolite, is described in this work. Ketamine was used as internal standard. The assay involved a single tert-butymethylether extraction and liquid chromatography analysis with fluorescence detection. Chromatography was performed at 20 degrees C on a Chiracel OD-R column containing cellulose tris-(3,5-dimethylphenylcarbamate) as stationary phase, preceded by an achiral end-capped C18 column. The mobile phase was a mixture of phosphate buffer (containing sodium perchlorate (0.2 M) and triethylamine (0.09 M) adjusted to pH 6) and acetonitrile (80:20). The method developed was validated. The limit of quantitation of each enantiomer of tramadol and its active metabolite by this method was 0.5 ng/mL; only 0.5 mL of the plasma sample was required for the determination. The calibration curve was linear from 0.5 to 750 ng/mL for tramadol enantiomers, and from 0.5 to 500 ng/mL for O-demethyltramadol enantiomers. Intra and interday precision [coefficient of variation (CV)] did not exceed 10%. Mean recoveries of 95.95 and 97.87% for (+)R,R- and (-)S,S-tramadol and 97.70 and 98.79% for (+)R,R- and (-)S,S-O-demethyltramadol with CVs < 2.15% were obtained. Applicability of the method was demonstrated by a pharmacokinetic study in normal volunteers who received 100 mg of tramadol by the intravenous route.

Selection of antibody probes to correlate protein sequence domains with their structural distribution

We propose a new approach that permits correlation of specific domains defined by their primary sequence with their location in the structure of complex macromolecular aggregates. It is based on the combination of well-established structural analysis methods that incorporate the use of overlapping peptides on cellulose membranes for the isolation and purification of specific antibodies from a polyclonal antiserum. Monospecific antibodies to the connector protein of bacteriophage phi29 were isolated from polyclonal antisera using a new development of the spotscan method. These antibodies can be purified in quantities that allow antigenicity testing in enzyme-linked immunosorbent assays, Western blotting and immunoprecipitations, demonstrating the specificity of this isolation procedure. This approach has allowed us to generate direct antibody probes for immunoelectron microscopy mapping of different connector protein domains in a low resolution three-dimensional epitope map.

Bowel preparation for the double-contrast barium enema: how to maintain coating with cleansing?

AIM

Poor mucosal coating, due to excess of fluid in the colon lumen, is a problem when the oral lavage method (4 litres of an iso-osmotic saline solution containing polyethylene glycol) is used as a preparation for double-contrast barium enema. Our aim was to assess the value of prior administration of sennosides to obtain a clean colon with a reduced volume of polyethylene glycol (PEG)-saline solution, but maintaining good mucosal coating.

MATERIALS AND METHODS

After a 2-day low-residue diet, three different oral preparations were compared: (i) 4 litres of a PEG-saline solution (SELG) and 15 mg of bisacodyl (116 patients, SELG-4 group); (ii) 156 mg of sennosides, 15 g of magnesium sulphate, and 2 litres of water (116 patients, SennMg group); (iii) 156mg of sennosides and 2 litres of SELG (116 patients, SennSELG group). Compliance, complaints, cleansing, mucosal coating, and fluid retention were evaluated.

RESULTS

Compliance was > 94% in every group. A higher percentage of mild nausea was observed in SELG-4 group, of mild abdominal cramping in SennMg group, of substantial abdominal cramping in SennSELG group (P < 0.02). Cleansing was better in SennSELG than in both the SELG-4 (P = 0.0003) and SennMg (P = 0.0353) group. Mucosal coating was better in SennMg than both SELG-4 (P = 0.0034) and SennSELG (P < 0.0001) group. There was more residual fluid in the SennSELG group than both in SELG-4 (P = 0.0029) and SennMg (P = 0.0059) group.

CONCLUSION

For colon cleansing, the combination of sennosides and PEG-saline solution was better than either the 4 litre PEG protocol or the combination of sennosides and magnesium sulphate. For mucosal coating, the protocol combining sennosides and magnesium sulphate was more effective than either protocols using the PEG-saline solution. This may be due to the interaction of residual magnesium ions in the colon lumen with the barium suspension.