Pharmacotherapy of ADHD in Adults With Autism Spectrum Disorder: Effectiveness and Side Effects

Objective: Symptoms of ADHD are expected to be more difficult to treat in patients with a combination of ADHD and autism spectrum disorder (ASD) as opposed to only ADHD. Little evidence is available on the influence of ASD on the effects of pharmacotherapy in adults with ADHD. This study addresses this gap. Method: 60 adults with ADHD and comorbid ASD were selected from an outpatient clinic and compared with 226 adults from the same clinic with only ADHD. Similar treatment regimens were received. Results: Significant decreases in symptoms of ADHD were found in both groups. A diagnosis of ASD did not affect the reduction in symptoms of ADHD. No significant group differences in side effects or vital signs were found. Conclusion: Results show that medication for ADHD can effectively and safely be prescribed to patients with ADHD and comorbid ASD. Suggestions for future research are discussed.

Burden of illness and health care resource utilization in adult psychiatric outpatients with attention-deficit/hyperactivity disorder in Europe

OBJECTIVE

To assess the burden of illness and health care resource utilization of adult nonpsychotic psychiatric outpatients with attention-deficit/hyperactivity disorder (ADHD) in Europe.

METHODS

This was a multicountry, cross-sectional, observational study where unselected routine patients from clinical psychiatric outpatient settings were screened and assessed for ADHD. Patients were evaluated using the Clinical Global Impressions of Severity (CGI-S) scale, the Sheehan Disability Scale (SDS), and the EuroQol-5 Dimensions questionnaire. Data on comorbidities, functional impairment, and health care resource utilization were captured.

RESULTS

The study enrolled 2284 patients, of whom 1986 completed the study. The prevalence of ADHD was 17.4%, of whom 46.0% had a previous ADHD diagnosis. Patients with ADHD had a high clinical burden with psychiatric comorbidities, especially depression (43.0%) and anxiety disorders (36.4%). Substance abuse (9.2% vs. 3.4%) and alcohol abuse (10.3% vs. 5.2%) were more common in the ADHD cohort vs. the non-ADHD cohort. Only 11.5% of the patients with ADHD had no other psychiatric disorder. Various measures indicated a significantly poorer level of functioning for patients with ADHD than without ADHD, as indicated by higher scores for CGI-S (3.8 vs. 3.3) and SDS (18.9 vs. 11.6) and higher percentages of debt (35.5% vs. 24.3%) and criminality (13.8% vs. 6.1%). Lastly, the health care resource utilization was considerable and similar between adult psychiatric outpatients diagnosed and not diagnosed with ADHD.

CONCLUSIONS

Although care was taken when choosing the sites for this study, to make it representative of the general outpatient adult psychiatric population, caution should be advised in generalizing the findings of our study to the general ADHD or psychiatric outpatient population. This was an observational study, thus no inference on causality can be drawn. Having ADHD imposes a considerable health and social burden on patient and health care resource utilization comparable to other chronic psychiatric disorders.

Predictive validity of self-report questionnaires in the assessment of autism spectrum disorders in adults

While various screening instruments for autism spectrum disorders are widely used in diagnostic assessments, their psychometric properties have not been simultaneously evaluated in the outpatient setting where these instruments are used most. In this study, we tested the Ritvo Autism Asperger Diagnostic Scale–Revised and two short versions of the Autism-Spectrum Quotient, the AQ-28 and AQ-10, in 210 patients referred for autism spectrum disorder assessment and in 63 controls. Of the 210 patients, 139 received an autism spectrum disorder diagnosis and 71 received another psychiatric diagnosis. The positive predictive values indicate that these tests correctly identified autism spectrum disorder patients in almost 80% of the referred cases. However, the negative predictive values suggest that only half of the referred patients without autism spectrum disorder were correctly identified. The sensitivity and specificity of each of these instruments were much lower than the values reported in the literature. In this study, the sensitivity of the Ritvo Autism Asperger Diagnostic Scale–Revised was the highest (73%), and the Autism-Spectrum Quotient short forms had the highest specificity (70% and 72%). Based on the similar area under the curve values, there is no clear preference for any of the three instruments. None of these instruments have sufficient validity to reliably predict a diagnosis of autism spectrum disorder in outpatient settings.

[Feasibility and effectiveness of mindfulness training in adults with ADHD: a pilot study]

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a developmental disorder that often continues into adulthood. Stimulant medication is the common treatment for ADHD. However, there is a need for psychosocial interventions in addition to medication.

AIM

To conduct a pilot study which examines the feasibility and effectiveness of mindfulness training for adults with ADHD.

METHOD

Eleven adults with ADHD participated in a mindfulness training scheme lasting 10 weeks. ADHD symptoms, anxiety and depressive symptoms, quality of life, mindfulness skills and attentional tasks were measured before and after the period of mindfulness training.

RESULTS

Nine participants completed the mindfulness training and were satisfied with the training. Eight of these reported improvement in their ADHD symptoms. For all participants, their quality of life, awareness of their actions and executive control had also improved.

CONCLUSION

Mindfulness is a feasible treatment strategy for adults with ADHD and seems to have a positive effect on ADHD symptoms and executive control.

Shared and unique genetic contributions to attention deficit/hyperactivity disorder and substance use disorders: a pilot study of six candidate genes

The shared genetic basis of attention deficit/hyperactivity disorder (ADHD) and substance use disorders (SUDs) was explored by investigating the association of candidate risk factors in neurotransmitter genes with both disorders. One hundred seven methadone maintenance treatment patients, 36 having an ADHD diagnosis, 176 adult patients with ADHD without SUDs, and 500 healthy controls were genotyped for variants in the DRD4 (exon 3 VNTR), DRD5 (upstream VNTR), HTR1B (rs6296), DBH (rs2519152), COMT (rs4680; Val158Met), and OPRM1 (rs1799971; 118A>G) genes. Association with disease was tested using logistic regression models. This pilot study was adequately powered to detect larger genetic effects (OR≥2) of risk alleles with a low frequency. Compared to controls, ADHD patients (with and without SUDs) showed significantly increased frequency of the DBH (rs2519152: OR 1.73; CI 1.15-2.59; P=0.008) and the OPRM1 risk genotypes (rs1799971: OR 1.71; CI 1.17-2.50; P=0.006). The DBH risk genotype was associated with ADHD diagnosis, with the association strongest in the pure ADHD group. The OPRM1 risk genotype increased the risk for the combined ADHD and SUD phenotype. The present study strengthens the evidence for a shared genetic basis for ADHD and addiction. The association of OPRM1 with the ADHD and SUD combination could help to explain the contradictory results of previous studies. The power limitations of the study restrict the significance of these findings: replication in larger samples is warranted.

Rainwater harvesting in schools in Taiwan: system characteristics and water quality

In order to understand the current status of rainwater harvesting (RWH) practices in Taiwan's schools, a study was carried out to examine the RWH system performance, water usage, and water quality in these sites. A total of 29 schools in various regions were selected for this investigation, including 7 in the northern, 7 in the central, 8 in the southern, and 7 in the eastern regions of Taiwan. Water quality indicators tested were: pH, temperature, conductivity, oxidation-reduction potential, suspended solid, total organic carbon, fecal coliform, and total coliform. From this study, it was found that RWH systems in these sites generally had two different designs: one that collected rainwater only, and one that collected both rainwater and grey water. From statistical analysis, it was found that water quality indicators such as suspended solids, total organic carbon, and fecal coliform were significantly affected by the water source and site location. Fecal coliforms in most of the sites we studied were high and not qualified for toilet flushing. The average water retention time of 2.4 months was long and considered to be the main reason to cause high fecal coliform counts. Finally, the benefit analysis was conducted to evaluate economic feasibility of rainwater harvesting for these schools. It turned out that 20% of them were able to gain economic benefits from using rainwater.

Removal of manganese ions from synthetic groundwater by oxidation using KMnO(4) and the characterization of produced MnO(2) particles

The aim of this study is to investigate the conditions for the removal of manganese ions from synthetic groundwater by oxidation using KMnO(4) to keep the concentration below the allowed level (0.05 mg/L). The process includes low-level aeration and addition of KMnO(4) in a Jar test system with Mn(2 + ) concentration of 0.50 mg/L, similar to that of natural groundwater in Taiwan. Different parameters such us aeration-pH, oxidant dose, and stirring speed were studied. Aeration alone was not sufficient to remove Mn(2 + ) ions completely even when the pH was increased. When a stoichiometric amount of KMnO(4) (0.96 mg/L) was used, a complete Mn(2 + ) removal was achieved within 15 min at an optimum pH of 8.0. As the amount of KMnO(4) was doubled, lower removal efficiency was obtained because the oxidant also generated manganese ions. The removal of Mn(2 + ) ions could be completed at pH 9.0 using an oxidant dose of 0.48 mg/L because Mn(2 + ) could be sorbed onto the MnO(2) particles. Finally, The MnO(2) particles were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).

Neural correlates of pragmatic language comprehension in autism spectrum disorders

Difficulties with pragmatic aspects of communication are universal across individuals with autism spectrum disorders (ASDs). Here we focused on an aspect of pragmatic language comprehension that is relevant to social interaction in daily life: the integration of speaker characteristics inferred from the voice with the content of a message. Using functional magnetic resonance imaging (fMRI), we examined the neural correlates of the integration of voice-based inferences about the speaker's age, gender or social background, and sentence content in adults with ASD and matched control participants. Relative to the control group, the ASD group showed increased activation in right inferior frontal gyrus (RIFG; Brodmann area 47) for speaker-incongruent sentences compared to speaker-congruent sentences. Given that both groups performed behaviourally at a similar level on a debriefing interview outside the scanner, the increased activation in RIFG for the ASD group was interpreted as being compensatory in nature. It presumably reflects spill-over processing from the language dominant left hemisphere due to higher task demands faced by the participants with ASD when integrating speaker characteristics and the content of a spoken sentence. Furthermore, only the control group showed decreased activation for speaker-incongruent relative to speaker-congruent sentences in right ventral medial prefrontal cortex (vMPFC; Brodmann area 10), including right anterior cingulate cortex (ACC; Brodmann area 24/32). Since vMPFC is involved in self-referential processing related to judgments and inferences about self and others, the absence of such a modulation in vMPFC activation in the ASD group possibly points to atypical default self-referential mental activity in ASD. Our results show that in ASD compensatory mechanisms are necessary in implicit, low-level inferential processes in spoken language understanding. This indicates that pragmatic language problems in ASD are not restricted to high-level inferential processes, but encompass the most basic aspects of pragmatic language processing.

Association of the dopamine transporter (SLC6A3/DAT1) gene 9-6 haplotype with adult ADHD

ADHD is a neuropsychiatric disorder characterized by chronic hyperactivity, inattention and impulsivity, which affects about 5% of school-age children. ADHD persists into adulthood in at least 15% of cases. It is highly heritable and familial influences seem strongest for ADHD persisting into adulthood. However, most of the genetic research in ADHD has been carried out in children with the disorder. The gene that has received most attention in ADHD genetics is SLC6A3/DAT1 encoding the dopamine transporter. In the current study we attempted to replicate in adults with ADHD the reported association of a 10-6 SLC6A3-haplotype, formed by the 10-repeat allele of the variable number of tandem repeat (VNTR) polymorphism in the 3' untranslated region of the gene and the 6-repeat allele of the VNTR in intron 8 of the gene, with childhood ADHD. In addition, we wished to explore the role of a recently described VNTR in intron 3 of the gene. Two hundred sixteen patients and 528 controls were included in the study. We found a 9-6 SLC6A3-haplotype, rather than the 10-6 haplotype, to be associated with ADHD in adults. The intron 3 VNTR showed no association with adult ADHD. Our findings converge with earlier reports and suggest that age is an important factor to be taken into account when assessing the association of SLC6A3 with ADHD. If confirmed in other studies, the differential association of the gene with ADHD in children and in adults might imply that SLC6A3 plays a role in modulating the ADHD phenotype, rather than causing it.

[Autism spectrum disorders in adults]

Early infantile autism' as defined by Kanner has grown into a spectrum of autistic disorders. The recognition of Asperger's disorder and of pervasive developmental disorder not otherwise specified (PDD-NOS), has led to increased demand for appropriate diagnostic assessment of autism in adults. The expression ofimpairments in social interaction, communication, imagination and mental flexibility changes during development into adulthood. The diagnostic procedure in adult psychiatry should comprise a collateral developmental interview. Autism spectrum disorders in adults may mimic, or be overshadowed by, other psychiatric disorders. For effective diagnosis, the application of structured interviews, such as the 'Autism diagnostic observation schedule' (ADOS), 'Autism diagnostic interview-revised' (ADI-R) or 'Diagnostic interview for social and communication disorders' (DISCO) is recommended.

The absence of benzodiazepine craving in a general practice benzodiazepine discontinuation trial

This study aimed to assess benzodiazepine craving longitudinally and to describe its time course by means of the Benzodiazepine Craving Questionnaire (BCQ). Subjects were long-term benzodiazepine users participating in a two-part treatment intervention aimed to reduce long-term benzodiazepine use in general practice in The Netherlands. Four repeated measurements of benzodiazepine craving were taken over a 21-month follow-up period. Results indicated that (1) benzodiazepine craving severity decreased over time, (2) patients still using benzodiazepines experienced significantly more severe craving than patients who had quit their use after one of the two interventions, and (3) the way in which patients had attempted to quit did not influence the experienced craving severity over time, however, (4) patients who had received additional tapering off, on average, reported significantly more severe craving than patients who had only received a letter as an incentive to quit. Although benzodiazepine craving is prevalent among (former) long-term benzodiazepine users during and after discontinuation, craving severity decreases over time to negligible proportions. Self-reported craving can be longitudinally monitored and quantified by means of the BCQ.

[Short- and long-term results of a systematic benzodiazepine discontinuation programme for psychiatric patients]

BACKGROUND

Although guidelines for the use of benzodiazepines emphasise that these drugs should only be prescribedfor short periods of time, in practice long-term usage persists and can be a serious problem. There is afear among patients and among doctors prescribing the drugs that symptoms will become more acute if attempts are made to terminate the regimen.

AIM

To determine the short- and long-term results of a standardized method for discontinuing the use of benzodiazepines (BZD) and to test whether these results were related to the age and gender of the patients, the BZD dosage level and the treatment modality.

METHOD

A retrospective cohort study was performed at the Department of Psychiatry of the Radboud University Nijmegen Medical Centre. A systematic BZD discontinuation programme was offered by the Department of Psychiatry to patients who had been using BZD for at least three months. By studying the medical records, by conducting telephone interviews and by examining the prescription data of the GP or the pharmacy it was ascertained how many patients managed to become abstinent in the short- and long-term.

RESULTS

Upon termination of the discontinuation programme 65% of the patients had managed to stop taking BZD and at follow-up approximately 2 years later 37% of the patients interviewed had not used BZD for the last 3 months. Neither age, nor gender, nor treatment modality predicted BZD usage immediately after the end of the discontinuation programme or at the 2-year follow-up. A high dose of BZD was the only significant predictor of post-programme usage 2 years later.

CONCLUSION

A systematic discontinuation programme seems to be just as effective for psychiatric patients as it isfor general practice patients and deserves to be included in the regular treatment programmes provided by psychiatric practices.

[Predicting the success of a benzodiazepine discontinuation programme: myths or clinical wisdom?]

BACKGROUND

After successful completion of a benzodiazepine withdrawal programme it nevertheless is hard to remain abstinent in the long term.

AIM

To determine to what extent the success of a benzodiazepine discontinuation programme for psychiatric patients with chronic benzodiazepine use (> or = 3 months) can be predicted from the severity of the anxiety, sleep disorders and depressive symptoms, and from the level of benzodiazepine dependence. The predictive values of coping style and personality characteristics were also studied.

METHOD

A prognostic cohort study with patients of the Radboud University Nijmegen Medical Centre was conducted. Before entering the programme 92 patients were given a psychological assessment. Anxiety level, benzodiazepine dependence, coping style and personality traits were measured by means of psychological questionnaires. The DSM-IV axis I classification for each patient was known. Patients who had stopped their medication immediately after the discontinuation programme ended (n = 6o) were compared with patients who had not been successful in completing the programme (n = 32). Thereafter, patients who were still abstinent at the follow-up about 2 years later (n = 25) were compared with patients who at that time /used benzodiazepine (n = 43).

RESULTS

Of all the variables examined, it was only a specific coping style whereby patients expressed their (negative) emotions which was associated with the short- and long-term success of the discontinuation programme. The more patients expressed their negative emotions, the greater the chance of a successful outcome and permanent abstinence. Coping style, however, predicted for only a small proportion of the variance in the success of the discontinuation programme.

CONCLUSION

The psychological characteristics and the DSM-IV axis I classifications should not exert undue influence on the clinician's decision to advise the patient to stop or continue taking benzodiazepines.

Latent trait standardization of the benzodiazepine dependence self-report questionnaire using the Rasch scaling model

The aim of the present study was to obtain standardized scores that correspond with the raw scores on the four Rasch scales of the Benzodiazepine Dependence-Self Report Questionnaire (Bendep-SRQ). The eligible normative group for standardization of the Bendep-SRQ scales consisted of 217 general practice (GP) patients, all using benzodiazepines. Two standardization methods were used and compared: "classical standardization," which transforms raw scores into standard scores on the unit normal distribution, and "latent trait standardization," which transforms raw scores into latent trait scores. The latter requires the Rasch model with the additional assumption of a normally distributed latent trait, which held true for the scales "problematic use," "lack of compliance," and "withdrawal," but not for "preoccupation." The observed unequal item spacing on the "preoccupation" scale was hypothesized to induce a response tendency of nondeviation, causing a local violation of the assumption of a normally distributed latent trait. Nevertheless, comparison of the results of the two standardization methods revealed such a high degree of resemblance, that latent trait standardization could be used for "preoccupation" just as well as classical standardization. The presented standard scores and corresponding percentile ranks make raw Bendep-SRQ scores clinically interpretable in relation to the normative GP sample. Incorporation of the Rasch scaling methodology into the development of the Bendep-SRQ marks the adoption of the item response theory in the field of applied test methodology. In this process, it appears that equal item spacing has to be taken into account to prevent local violations of the Rasch model with the additional assumption of a normally distributed latent trait.

Cross-validation of the benzodiazepine dependence self-report questionnaire in outpatient benzodiazepine users

The aim of this study was to cross-validate the Benzodiazepine Dependence Self-Report Questionnaire (Bendep-SRQ), which reflects the severity of benzodiazepine (BZD) dependence. The Bendep-SRQ, Symptom Checklist-90 (SCL-90) Schedules for Clinical Assessments in Neuropsychiatry (SCAN), and Addiction Severity Index-Revised (ASI-R) were administered to 102 general practice (GP) patients and 126 psychiatric outpatients who were using BZDs. The scalability and reliability of the Bendep-SRQ scales were reassessed in terms of Rasch homogeneity, subject discriminability, item discriminability, and test-retest stability. Present and original Rasch item orders were compared to evaluate construct validity. A matrix of all measures was factor-analyzed to assess concurrent and discriminant validity. The scalability of the Bendep-SRQ scales was confirmed. The reliability results were fairly good. Present and original Rasch item orders corresponded. The Bendep-SRQ scales and concurrent measures had high loadings on one factor, the discriminant measures on two other factors. In spite of some differences with respect to sociodemographic characteristics and pattern of BZD use, the cross-validation results agreed well with the results of the original study on the Bendep-SRQ. The Bendep-SRQ has presently acquired enough support of favorable and consistent results for clinical and scientific use.

Assessment of benzodiazepine dependence in alcohol and drug dependent outpatients: a research report

In this study on 99 outpatients who were being treated for alcohol and/or drug dependence and also using benzodiazepines (BZDs), prevalence rates of DSM-III-R and ICD-10 substance dependence diagnoses were ascertained and scalability, reliability and validity of the scales of the Benzodiaepine Dependence Self-Report Questionnaire (Bendep-SRQ) were assessed. The latter properties were investigated by Rasch analyses, discriminability coefficients, test-retest coefficients and factor analyses. BZD dependence was found to be a prevalent additional diagnosis. The psychometric findings appear to support the use of the Bendep-SRQ at outpatient addiction centers, which could contribute to a more differentiated treatment for poly-substance dependence.

The 1.7 A crystal structure of human cell cycle checkpoint kinase Chk1: implications for Chk1 regulation

The checkpoint kinase Chk1 is an important mediator of cell cycle arrest following DNA damage. The 1.7 A resolution crystal structures of the human Chk1 kinase domain and its binary complex with an ATP analog has revealed an identical open kinase conformation. The secondary structure and side chain interactions stabilize the activation loop of Chk1 and enable kinase activity without phosphorylation of the catalytic domain. Molecular modeling of the interaction of a Cdc25C peptide with Chk1 has uncovered several conserved residues that are important for substrate selectivity. In addition, we found that the less conserved C-terminal region negatively impacts Chk1 kinase activity.

Scalability, reliability, and validity of the benzodiazepine dependence self-report questionnaire in outpatient benzodiazepine users

As there is no multidimensional instrument available that reflects the severity of benzodiazepine (BZD) dependence comprehensively, the Benzodiazepine Dependence Self-Report Questionnaire (Bendep-SRQ) was developed and investigated. The Bendep-SRQ, Symptom Checklist-90 (SCL-90), Schedules for Clinical Assessments in Neuropsychiatry (SCAN), and Addiction Severity Index-Revised (ASI-R) were administered to 115 general practice (GP) patients, 124 psychiatric outpatients, and 33 self-help patients who were using BZDs. Factor and Rasch analyses were applied to construct scales. Reliability assessments were made in terms of subject discriminability, item discriminability, and test-retest stability. To support the construct validity of the scales, theoretical rationales were required to explain the specific item order provided by the Rasch scale values. To assess the concurrent and discriminant validity, a matrix consisting of the above-mentioned measures was factor-analyzed. Four Rasch-homogeneous scales were delineated: problematic use, preoccupation, lack of compliance, and withdrawal. Nearly all subject discriminability, item discriminability, and test-retest results indicated good reliability. A BZD dependence factor was extracted with high loadings for the Bendep-SRQ scales and the concurrent measures. The discriminant measures had high loadings on other factors. The scalability, reliability, and validity of the Bendep-SRQ scales appeared to be good. The Bendep-SRQ shows great promise as a useful and easily manageable instrument for assessment of the severity of BZD dependence in clinical practice and scientific research.

Crystal structure of the kinase domain of human vascular endothelial growth factor receptor 2: a key enzyme in angiogenesis

BACKGROUND

Angiogenesis is involved in tumor growth, macular degeneration, retinopathy and other diseases. Vascular endothelial growth factor (VEGF) stimulates angiogenesis by binding to specific receptors (VEGFRs) on the surface of vascular endothelial cells. VEGFRs are receptor tyrosine kinases that, like the platelet-derived growth factor receptors (PDGFRs), contain a large insert within the kinase domain.

RESULTS

We report here the generation, kinetic characterization, and 2.4 A crystal structure of the catalytic kinase domain of VEGF receptor 2 (VEGFR2). This protein construct, which lacks 50 central residues of the 68-residue kinase insert domain (KID), has comparable kinase activity to constructs containing the entire KID. The crystal structure, determined in an unliganded phosphorylated state, reveals an overall fold and catalytic residue positions similar to those observed in other tyrosine-kinase structures. The kinase activation loop, autophosphorylated on Y1059 prior to crystallization, is mostly disordered; however, a portion of it occupies a position inhibitory to substrate binding. The ends of the KID form a beta-like structure, not observed in other known tyrosine kinase structures, that packs near to the kinase C terminus.

CONCLUSIONS

The majority of the VEGFR2 KID residues are not necessary for kinase activity. The unique structure observed for the ends of the KID may also occur in other PDGFR family members and may serve to properly orient the KID for signal transduction. This VEGFR2 kinase structure provides a target for design of selective anti-angiogenic therapeutic agents.

Role of His-224 in the anomalous pH dependence of human stromelysin-1

A plot of the pH dependence of kcat/KM for human stromelysin-1 (HS) exhibits a narrow range of maximal activity extending from pH 5.75 to 6.25 and a broad shoulder in the pH range of 7.5-8.5. In contrast, the pH profiles that have been reported for other members of the matrix metalloproteinase (MMP) family are bell-shaped and exhibit neutral pH optima. We hypothesized that the anomalous pH dependence of HS reflects the ionization of His-224, a residue located in a flexible loop that contributes to the S1' binding pocket of the enzyme. HS is the only known MMP that has a histidine in this position. To test this hypothesis, the H224Q mutant of the short form (lacking the C-terminal hemopexin-like domain) of HS (sHS) has been prepared and studied. The pH profile of H224Q sHS is bell-shaped and similar to those reported for other MMPs. Although H224Q and wild-type sHS possess similar activities at pH <6, the kcat/KM of H224Q sHS is more than 5-fold greater than that of the wild-type enzyme at pH >7. These data strongly suggest that the deprotonation of His-224 attenuates the activity of HS, thereby accounting for its low pH optimum and the characteristic shoulder in its pH profile. This attenuation of activity appears to be predominantly a KM effect, reflecting a decrease in the affinity of the enzyme for the peptide substrate.

An evaluation of DSM-III-R and ICD-10 benzodiazepine dependence criteria using Rasch modelling

AIMS

To evaluate the homogeneity of the elements of the Substance Dependence Syndrome (SDS) as applied to benzodiazepines (BZDs) by Rasch modelling.

MEASUREMENTS

The Rasch scaling model was applied to data obtained by administering the SCAN (Schedules for Clinical Assessments in Neuropsychiatry) substance dependence sections. Subsequently, Rasch-homogeneous sets of DSM-III-R and ICD-10 BZD dependence criteria were assessed for subject and item discriminability. To support their construct validity a theoretical rationale was formulated based on the Rasch scale values.

PARTICIPANTS

A heterogeneous sample of 599 outpatient BZD users.

FINDINGS

Only particular subsets of the DSM-III-R and ICD-10 BZD dependence criteria met the requirements for Rasch-homogeneity, which appears to be due to medical aspects of BZD use. The subject and item discriminability results were sufficiently good.

CONCLUSIONS

The DSM-III-R and ICD-10 BZD dependence constructs may need to be redefined. The use of a BZD dependence severity model based on a Rasch-homogeneous scale appears to have greater clinical value than a dichotomous diagnostic model based on an arbitrary cut-off point. We recommend Rasch modelling to investigate the homogeneity of the elements of the SDS across other psychoactive substances.

Expression of human pro-matrix metalloproteinase 3 that lacks the N-terminal 34 residues in Escherichia coli: autoactivation and interaction with tissue inhibitor of metalloproteinase 1 (TIMP-1)

Human pro-matrix metalloproteinase 3 (proMMP-3) lacking the N-terminal 34 amino acids and the C-terminal hemopexin-like domain was expressed in E. coli and used to investigate the process of proenzyme activation and its interaction with an endogenous inhibitor TIMP-1 during activation. The truncated precursor was purified from the E. coli extract in the presence of 5mM EGTA. The active 23.5 kDa form was generated simply by exposure to Ca2+ and Zn2+ but not either by Ca2+ alone or by Zn2+ alone. The rate of MMP-3(deltaC) formation was concentration dependent, indicating that autoactivation is a bimolecular reaction. The truncated precursor was able to interact with the N-terminal domain of TIMP-1 without losing the 48 residue-long propeptide. However, upon a longer incubation, the propeptide was slowly processed, indicating that the association of the N-terminally truncated proMMP-3 with TIMP-1 is weaker than that of the fully activated MMP-3 and TIMP-1. These results indicate that the expression of MMP activities is regulated by endogenous inhibitor TIMPs during their activation processes which provide an additional control mechanism of extracellular matrix breakdown.

High prevalence of benzodiazepine dependence in out-patient users, based on the DSM-III-R and ICD-10 criteria

Despite the fact that there have been many reports on benzodiazepine (BZD) dependence, consensus about its definition has not been reached. Reliable prevalence data to estimate the dependence liability of BZDs are therefore lacking. This study is the first to assess the prevalence of BZD dependence in out-patient BZD users (115-general practice (GP) patients, 124 psychiatric out-patients and 33 self-help patients) on the basis of the DSM-III-R and ICD-10 substance dependence criteria. Past year and lifetime diagnoses of BZD dependence were made by means of the Schedules for Clinical Assessments in Neuropsychiatry (SCAN). High prevalence figures were found, ranging from 40% in the GP patients (DSM-III-R past year) to 97% in the self-help patients (ICD-10 lifetime), indicating that BZD users run a high risk of developing BZD dependence. The clinical management of BZD use could benefit from further development of diagnostic instruments such as a self-report questionnaire which reflects the severity of BZD dependence.

Comparison of human cytomegalovirus (HCMV) protease sequences among laboratory strains and seven clinical isolates

The nucleotide sequence of the human cytomegalovirus (HCMV) protease gene from two laboratory strains and seven clinical isolates, both ganciclovir-sensitive and -resistant, was examined to determine the genetic variability of the HCMV protease catalytic domain and to identify changes that may alter the efficacy of designed protease inhibitors. The Towne strain varied from AD169 at 12 nucleotides and led to one amino acid change at position 12 (Ala to Thr). The clinical isolates had amino acid substitutions relative to the laboratory strains, with a Ser to Pro change at position 8, a His to Tyr change at position 44 and s Gly to Ser change at position 47. None of these changes occurred in any of the conserved domains of the protease, nor do they appear necessary to confer ganciclovir resistance in the isolates. These findings suggest that no changes exist in the protease of the clinical isolates examined that may diminish the effectiveness of a drug targeting the HCMV protease. 1977 Elsevier Science B.V. All rights reserved.

Structure of the human cytomegalovirus protease catalytic domain reveals a novel serine protease fold and catalytic triad

Proteolytic processing of capsid assembly protein precursors by herpesvirus proteases is essential for virion maturation. A 2.5 A crystal structure of the human cytomegalovirus protease catalytic domain has been determined by X-ray diffraction. The structure defines a new class of serine protease with respect to global-fold topology and has a catalytic triad consisting of Ser-132, His-63, and His-157 in contrast with the Ser-His-Asp triads found in other serine proteases. However, catalytic machinery for activating the serine nucleophile and stabilizing a tetrahedral transition state is oriented similarly to that for members of the trypsin-like and subtilisin-like serine protease families. Formation of the active dimer is mediated primarily by burying a helix of one protomer into a deep cleft in the protein surface of the other.

Dimerization of the human cytomegalovirus protease: kinetic and biochemical characterization of the catalytic homodimer

The single-chain 28 kDa human cytomegalovirus (HCMV) protease catalytic domain containing the A143Q mutation has been kinetically and conformationally characterized. The specific activity of the HCMV A143Q protease (HCMVp) increases as the protease concentration increases, suggesting that this protease oligomerizes at high protein concentration to form a more active species. Both cross-linking and light-scattering studies of HCMVp show the existence of a homodimer with an apparent molecular mass of 56 kDa under low ionic strength and high protein concentration. The cosolvent and solute effects of glycerol, trisodium citrate, and NaCl as well as the temperature effects on the HCMVp activity and quaternary structure were investigated. The effects induced by cosolvents and temperature can largely be explained by their influences in the dimerization or oligomerization state of HCMVp. The dissociation constant (Kd) for the HCMVp homodimer was determined to be 8 +/- 1 microM with all activity attributed to the dimeric form. Monomeric HCMVp is inactive. This report demonstrates that in vitro, HCMV A143Q protease exists as an obligate catalytic homodimer. This protease dimerization may have regulatory significance during viral replication.

Purification of human matrilysin produced in Escherichia coli and characterization using a new optimized fluorogenic peptide substrate

Human promatrilysin (matrix metalloproteinase-7) has been produced in Escherichia coli as an N-terminal fusion protein with ubiquitin. The insoluble product was solubilized, refolded, and activated with amino-phenylmercuric acetate. Activation of the fusion protein demonstrated kinetics and intermediates that were very similar to those observed during activation of promatrilysin produced in Chinese Hamster Ovary (CHO) cells. Following activation, matrilysin was purified to > 95% homogeneity using a Sepharose-Pro-Leu-Gly-NHOH affinity column. The matrilysin purified by this procedure is indistinguishable from the enzyme purified from CHO cells with respect to the kinetic parameters for hydrolysis of a peptide substrate and the ability to obtain diffraction quality crystals in the presence of an inhibitor of the enzyme. Additionally, to facilitate detailed kinetic analyses of matrilysin, a new fluorogenic peptide substrate with the optimized sequence Dnp-Arg-Pro-Leu-Ala-Leu-Trp-Arg-Ser (Dnp, dinitrophenyl) has been synthesized. This peptide is the best substrate developed for matrilysin thus far with Km and kcat values of 26 microM and 5.0 s-1, respectively.

Single-chain recombinant human cytomegalovirus protease. Activity against its natural protein substrate and fluorogenic peptide substrates

We report here the production of active recombinant single-chain human cytomegalovirus protease in Escherichia coli and development of a continuous assay for this protease. In order to produce the human cytomegalovirus (HCMV) protease for structural studies and accurate kinetic analysis, mutation of alanine 143 at an internal cleavage site was introduced to prevent auto-proteolysis. The resulting soluble 29-kDa A143Q protease was purified to homogeneity as a stable single-chain protein by hydrophobic interaction and ionic-exchange chromatography. The in vivo protein substrate, assembly protein precursor, was also expressed and purified for activity studies. To develop a continuous protease assay, fluorescent synthetic peptide substrates similar to the cleavage sequence P5 to P5' of the maturation site containing anthranilic acid and nitrotyrosine as a resonance energy transfer donor-acceptor pair were designed. Purified HCMV A143Q protease cleaved the recombinant assembly protein precursor with Km and kcat values of 3.0 +/- 1.0 microM and 13.3 +/- 1.6 min-1. The Km for peptide substrates is at least 45-fold higher than for the natural protein substrate, but the kcat values are similar. A sensitive assay was developed using fluorescent peptide substrates, which can detect nM HCMV protease activity.

Characterization of the Phe-81 and Val-82 human fibroblast collagenase catalytic domain purified from Escherichia coli

Soluble recombinant human fibroblast collagenase catalytic domain was highly expressed and purified from Escherichia coli. The expression construct utilized the T7 gene 10 promoter for transcription of a two-cistron messenger RNA which encoded the ubiquitin-collagenase catalytic domain fusion protein as the second cistron. The ubiquitin domain was attached to the collagenase catalytic domain with the linker sequences Gly-Gly-Thr-Gly-Asp-Val-Ala-Gln (wild type) or Gly-Gly-Thr-Gly-Asp-Val-Gly-His (mutant) which served as cleavage sites for in vitro activation. The last four residues of the linker were included based on the crystal structure of human prostromelysin-1 catalytic domain. Soluble fusion proteins purified from E. coli retained the proteolytic activity of the collagenase catalytic domain. The collagenase catalytic domain was released by either autoproteolytic or stromelysin-1-catalyzed cleavage, purified to homogeneity, and separately possess Phe-81, Val-82, or Leu-83 as the amino-terminal residue. Very similar kcat/Km values were determined for the Phe-81 and Val-82 forms using continuous fluorogenic and chromogenic peptide cleavage assays.

Ionizing radiation acts on cellular membranes to generate ceramide and initiate apoptosis

Recent investigations provided evidence that the sphingomyelin signal transduction pathway mediates apoptosis for tumor necrosis factor alpha (TNF-alpha) in several hematopoietic and nonhematopoietic cells. In this pathway, TNF-receptor interaction initiates sphingomyelin hydrolysis to ceramide by a sphingomyelinase. Ceramide acts as a second messenger stimulating a ceramide-activated serine/threonine protein kinase. The present studies show that ionizing radiation, like TNF, induces rapid sphingomyelin hydrolysis to ceramide and apoptosis in bovine aortic endothelial cells. Elevation of ceramide with exogenous ceramide analogues was sufficient for induction of apoptosis. Protein kinase C activation blocked both radiation-induced sphingomyelin hydrolysis and apoptosis, and apoptosis was restored by ceramide analogues added exogenously. Ionizing radiation acted directly on membrane preparations devoid of nuclei, stimulating sphingomyelin hydrolysis enzymatically through a neutral sphingomyelinase. These studies provide the first conclusive evidence that apoptotic signaling can be generated by interaction of ionizing radiation with cellular membranes and suggest an alternative to the hypothesis that direct DNA damage mediates radiation-induced cell kill.

Structure of and kinetic channelling in bifunctional dihydrofolate reductase-thymidylate synthase

The bifunctional enzyme dihydrofolate reductase-thymidylate synthase catalyses both the reductive methylation of 2'-deoxyuridylate and the subsequent reduction of dihydrofolate to yield 2'-deoxythymidylate and tetrahydrofolate at two spacially discrete sites situated on different protein domains. The X-ray structure of dihydrofolate reductase-thymidylate synthase from Leishmania major indicates that transfer of dihydrofolate between these sites does not occur by transient binding at both sites but rather by movement of dihydrofolate across the surface of the protein. The enzyme has an unusual surface charge distribution that could account for this channelling of dihydrofolate between active sites.

Activation of the sphingomyelin signaling pathway in intact EL4 cells and in a cell-free system by IL-1 beta

The mechanism of interleukin-1 (IL-1) signaling is unknown. Tumor necrosis factor-alpha uses a signal transduction pathway that involves sphingomyelin hydrolysis to ceramide and stimulation of a ceramide-activated protein kinase. In intact EL4 thymoma cells, IL-1 beta similarly stimulated a rapid decrease of sphingomyelin and an elevation of ceramide, and enhanced ceramide-activated protein kinase activity. This cascade was also activated by IL-1 beta in a cell-free system, demonstrating tight coupling to the receptor. Exogenous sphingomyelinase, but not phospholipases A2, C, or D, in combination with phorbol ester replaced IL-1 beta to stimulate IL-2 secretion. Thus, IL-1 beta signals through the sphingomyelin pathway.

Heterologous expression and purification of active human phosphoribosylglycinamide formyltransferase as a single domain

We report here for the first time that the GART domain of the human trifunctional enzyme possessing GARS, AIRS, and GART activities can be expressed independently in Escherichia coli at high levels as a stable protein with enzymatic characteristics comparable to those of native trifunctional protein. Human trifunctional enzyme is involved in de novo purine biosynthesis, and has long been recognized as a target for antineoplastic intervention. The GART domain was expressed in E. coli under the control of bacteriophage T7 promotor and isolated by a three-step chromatographic procedure. Two residues, Asp 951 and His 915, were shown to be catalytically crucial by site-directed mutagenesis and subsequent characterization of purified mutant proteins. The active monofunctional GART protein produced in E. coli can serve as a valuable substitute of trifunctional enzyme for structural and functional studies which have been until now hindered because of insufficient quantity, instability, and size of the trifunctional GART protein.

Structures of apo and complexed Escherichia coli glycinamide ribonucleotide transformylase

The three-dimensional structure of phosphoribosylglycinamide formyltransferase (10-formyltetrahydrofolate:5'-phosphoribosylglycinamide formyltransferase, EC 2.1.2.2) has been solved both as an apoenzyme at 2.8-A resolution and as a ternary complex with the substrate glycinamide ribonucleotide and a folate inhibitor at 2.5-A resolution. The structure is a modified doubly wound alpha/beta sheet with flexibility in the active site, including a disordered loop in the apo structure, which is ordered in the ternary complex structure. This enzyme is a target for anti-cancer therapy and now for structure-based drug design.

A synthetic ceramide analog, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, selectively inhibits adherence during macrophage differentiation of human leukemia cells

Prior studies have demonstrated that sphingomyelin synthesis is involved in adherence during macrophage differentiation of HL-60 cells (Dressler, K. A., Kan, C.-C., and Kolesnick, R. N. (1991) J. Biol. Chem. 266, 11522-11527). The present studies show that glycosphingolipid synthesis is also involved. Initial studies demonstrated that the potent phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates a 6- and 12-fold increase in the levels of sialosyllactosylceramide (GM3) and glucosylceramide (GlcCer), respectively, during development of an adherent macrophage population. In contrast, the level of lactosylceramide (LacCer) decreased to 20% of unstimulated controls. These effects were specific to adherent macrophages as nonadherent cells had minimal alteration in the glycosphingolipid profile. D-Threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), a competitive inhibitor of UDP-glucose:ceramide glucosyltransferase (EC 2.4.1.80), selectively blocked adherence during macrophage differentiation. PDMP markedly reduced basal levels of GlcCer, LacCer, and GM3 and prevented TPA-stimulated effects. PDMP (0.03-10 microM) reduced adherence after TPA from 30 to 6% of the total population. PDMP did not block other aspects of phorbol ester-induced macrophage differentiation including growth inhibition, expression of mRNA transcripts for the proto-oncogenes c-fos and c-myc, development of the specific enzyme markers alpha-naphthyl acetate esterase and acid phosphatase, and the gross morphologic changes associated with macrophage differentiation. PDMP appeared to have no short term or prolonged toxic effect on HL-60 cells. These studies show that PDMP selectively blocked adherence of HL-60 cells during phorbol ester-induced macrophage differentiation and suggest that this compound may be useful in the description of the biologic roles of glycosphingolipids.

Rates of spontaneous exchange of synthetic radiolabeled sterols between lipid vesicles

14C-labeled sterols with structural variation in the polar function [3 alpha-OH, 3-O(CH2)2O-(CH2)2O(CH2)2OH, 3 alpha-NH2, 3 beta-NH2, and 3-OC(O)CHN = N] and at the 7 position (7-oxo, 7 alpha-OH, and 7 beta-OH) were synthesized and incorporated into unilamellar vesicles for studies of the rates of transfer to an excess of acceptor vesicles. Cholesterol, cholestanol, and epicholesterol underwent full exchange in a single kinetic pool, and 90% of the 3 alpha-triethoxycholesterol was exchangeable in one pool. Biphasic kinetics with full exchangeability were observed for cholesterylamines, which bear a positive charge at the 3 position; the slow phase reflects the high activation energy for inner-to-outer leaflet movement of the charged lipid. Biphasic kinetics were also found for cholesteryl diazoacetate, indicating that this photoaffinity probe and cholesterol have different mechanisms of transfer. Sterols that are more hydrophilic than cholesterol as estimated by reversed-phase high-performance chromatography (elution with acetonitrile-2-propanol, 4:1 v/v, with varying proportions of water) gave faster exchange rates than cholesterol, whereas sterols that are more hydrophobic gave slower exchange rates. However, the rates of [14C]sterol desorption from the lipid-water interface are not correlated with the relative sterol hydrophobicity as estimated by the logarithm of the capacity factors using acetonitrile-2-propanol-water as the mobile phase. These studies suggest that the interaction of sterols with phospholipids provides the principal physical-chemical basis for determining the rates of spontaneous exchange of sterols between bilayers.

Interaction of cholesterol with sphingomyelin in bilayer membranes: evidence that the hydroxy group of sphingomyelin does not modulate the rate of cholesterol exchange between vesicles

Cholesterol undergoes exchange between membranes containing sphingomyelin at a much slower rate than between membranes lacking sphingomyelin. To investigate the role of the hydroxy group at the 3-position of sphingomyelin in the interaction between sphingomyelin and cholesterol, we have measured the rates of [4-14C]cholesterol exchange between unilamellar vesicles prepared with N-stearoylsphingomyelin or with synthetic analogues in which the hydroxy group is replaced with an O-alkyl group or with hydrogen. Vesicles prepared from 3-deoxy- and 3-O-methyl-N-stearoylsphingomyelin had the same rate of [14C]-cholesterol desorption. The half-times for exchange from vesicles prepared with 3-O-methyl- and 3-deoxy-N-stearoylsphingomyelins and 10 mol % of cholesterol were only slightly faster (a factor of only 1.5) than that found from vesicles prepared from N-stearoylsphingomyelin and 10 mol % cholesterol. The rate of cholesterol desorption from vesicles could be accelerated by preparing vesicles from bulky 3-O-alkyl analogues of sphingomyelin. Vesicles containing 3-O-ethyl-N-stearoylsphingomyelin and 3-O-tetrahydropyranyl egg sphingomyelin gave rate enhancements of approximately 14 and 35, compared with the rates observed in vesicles made from N-stearoyl- and egg sphingomyelin, respectively. These data indicate that insertion of sterically bulky groups at the 3-position of sphingomyelin (such as ethoxy and tetrahydropyranyloxy) in place of hydroxy interferes markedly with the molecular packing of cholesterol and sphingomyelin in bilayer membranes; however, the hydroxy group of sphingomyelin is not critical for the strong interaction of cholesterol with sphingomyelin.(ABSTRACT TRUNCATED AT 250 WORDS)

Phospholipids containing nitrogen- and sulfur-linked chains: kinetics of cholesterol exchange between vesicles

We have examined the kinetics of [14C]cholesterol exchange between unilamellar vesicles formed from the following synthetic glycerophosphatidylcholines: (a) those having acyl (OC(O)R), acylamino (NHC(O)R), carbamoyl (NHC(O)OR), and acylthio (SC(O)R) chains at the sn-2 position, and (b) those having alkyl (OR) and thioalkyl (SR) chains at the sn-1 position. Replacement of the glycerol oxygen atom at the sn-2 position of PC with a NH group did not affect the rate of cholesterol exchange to a significant extent, suggesting that the amide group of sphingomyelin is not primarily responsible for the very slow rate of exchange of cholesterol observed from sphingomyelin vesicles. Replacement of the glycerol oxygen at the sn-2 position of phosphatidylcholine with a sulfur atom caused the rate of spontaneous cholesterol exchange to increase by a factor of 1.6. Substitution of an O-alkyl chain for the acyl chain at the sn-1 position of 2-acylthiophosphatidylcholine or substitution of a thioalkyl chain for the O-alkyl sn-1 chain of 1-alkyl-2-acylaminodeoxyphosphatidylcholine also did not result in a marked difference in cholesterol exchange rate. The data suggest that interactions other than intermolecular hydrogen bonding are involved in determining the rates of intermembrane cholesterol exchange. Significantly, these kinetic studies also lend support to the continued use in model membranes of synthetic sulfur- and nitrogen-substituted phosphatidylcholines, which have been employed to study properties of lipolytic enzymes, since synthetic acylamino- and acylthio-phospholipids form vesicles that give cholesterol exchange rates that closely resemble those found in vesicles prepared with diester-phosphatidylcholines.

Sphingomyelin synthesis is involved in adherence during macrophage differentiation of HL-60 cells

Prior studies demonstrated that sphingomyelin degradation via a sphingomyelinase antagonized phorbol ester-mediated differentiation of HL-60 cells into macrophages (Kolesnick, R.N. (1989) J. Biol. Chem. 264, 7617-7623). The present studies show that phorbol esters induce early sphingomyelin synthesis in HL-60 cells and that this event may play a direct role in development of an adherent macrophage population. A maximally effective concentration of the potent phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA; 1 x 10(-7) M) stimulated an elevation in the sphingomyelin level at 24 h from 560 to 700 pmol/10(6) cells; a peak level of 1400 pmol/10(6) cells was achieved at 48 h. Phosphatidylcholine levels did not change significantly, indicating sphingomyelin synthesis was selective. The phosphatidylcholine:sphingomyelin ratio decreased from 10.3 to 7.9 at 24 h and to 5.3 at 48 h. Phorbol ester-induced sphingomyelin synthesis was biphasic. A burst of synthesis, detectable within 1 h and linear for 4 h, was followed by a prolonged phase at a slower rate. Ceramide synthesis was also biphasic. Ceramide levels decreased initially consistent with activation of the enzyme, phosphatidylcholine:ceramide cholinephosphotransferase and increased during the prolonged phase of sphingomyelin synthesis. During phorbol ester-induced differentiation, an adherent macrophage population was demonstrable by 14 h. This population contained the entire elevation of sphingomyelin levels. This demonstrates that early sphingomyelin synthesis defines a population of cells destined to become adherent macrophages. Studies were performed to directly manipulate sphingomyelin levels. Small unilamellar vesicles containing sphingomyelin did not directly induce macrophage differentiation but rather potentiated the effect of submaximal concentrations of phorbol ester. Sphingomyelin vesicles (2 x 10-6 M) enhanced TPA (5 x 10-10 M)-induced adherence 2-fold from 12 to 24% of the total population. Sphingosylphosphorylcholine (5 x 10-6 M), which may be acylated to sphingomyelin, was similarly effective. Further, exogenous sphingomyelinase, but not various phospholipases A2 and C, induced detachment of adherent macrophages. In sum, these studies demonstrate that phorbol esters induce early, selective synthesis of sphingomyelin in HL-60 cells. This event defines a population of cells destined to become adherent macrophages and may play a direct role in the adherence process.

[Reasons for rejection of articles vor publication in the Nederlands Tijdschrift voor Geneeskunde in 1990]

To deduce recommendations for authors which decrease the rejection probability we investigated retrospectively which reasons were mentioned in 1990 by the editorial board of the 'Nederlands Tijdschrift voor Geneeskunde' when it rejected original articles, reviews, clinical lessons and case reports, and whether length of the article, professional status of the first author, most relevant specialism and origin of the article influenced the rejection probability. Out of 547 articles 38% (208) were rejected; case reports were rejected most often (49%), reviews least often (33%). Peer review of original articles was the most thorough, of case studies the least. The most frequent reason for rejection in all categories was 'substantial shortcomings', particularly in the original articles (80%). Rejection of clinical lessons and case studies was relatively often due to criteria concerning the clinical message. Both rejected and accepted articles on average exceeded the length limit. Professional status and specialism were associated with a difference in rejection probability (chi 2, p less than 0.05). Specialists had the lowest rejection probability (31%). Nonspecialists benefited from specialist supervision. Articles originating from non-academic institutions were more often rejected than articles from academic centres. We advise authors to judge their articles by means of the criteria mentioned. Consultation of (methodological) experts, literature data bases, and (or) the editorial board can improve their chances. Non-specialists can benefit from the experience and expertise of specialists. In general, scientific attitude and willingness to alter the article according to editorial advice appear to have beneficial results.

[Early diagnosis of fragile X mental retardation syndrome]

Conducting an inquiry among 32 parents of 46 children with fragile-X mental retardation, we investigated the problems on early recognition of the syndrome. From the first call for medical help until establishment of the diagnosis, on average 2 years elapsed. The family history is very important, since in 82.5% of the cases mental retardation also occurred in other family members. We recommend that investigations should be performed in all children who do not repeat words and/or do not walk without help, at the age of 18 months. A high priority must then be given to specific investigations on the X-chromosomal fragile site.

Sequence of rat liver alpha 2-macroglobulin and acute phase control of its messenger RNA

Six alpha 2-macroglobulin cDNA clones were isolated from two liver cDNA libraries produced from rats undergoing acute inflammation. The coding sequence for rat alpha 2-macroglobulin including its 27-residue signal peptide and the 3' - and part of the 5' nontranslated regions were determined. The mature protein consisting of 1445 amino acids is coded for by a 4790 +/- 40 nucleotide messenger RNA. It contains a typical internal thiol ester region and 25 cysteine residues which are conserved between rat and human alpha 2-macroglobulin. Although the amino acid sequences of rat and human alpha 2-macroglobulin share 73% identity, two small divergent areas of 17 and 38 residues were found, corresponding to 29 and 11% identity, respectively. These areas are located in the bait region and, therefore, may confer specific proteinase recognition capabilities on rat alpha 2-macroglobulin. Following an inflammatory stimulation, rat alpha 2-macroglobulin mRNA levels increased 214-fold over control values and reached a maximum at 18 h. By 24 h the levels had decreased to less than 30% of the maximum value. Transcription rates from the alpha 2-macroglobulin gene as measured in nuclear run-on experiments showed a less than 3-fold increase in nuclei from acutely inflamed rats as compared to controls. These results suggest that the accummulation of alpha 2M mRNA is due to the combined effects of increased transcription rates and post-transcriptional processing.

Nucleotide sequence of cDNA encoding human alpha 2-macroglobulin and assignment of the chromosomal locus

Six alpha 2-macroglobulin (alpha 2M) cDNA clones were isolated from a human liver cDNA library by using synthetic oligonucleotides as hybridization probes. One of these, p alpha 2M1, carries a 4.6 kilobase-pair insert, which was sequenced. The insert contains the coding sequences for the mature alpha 2M polypeptide (1451 amino acids) and for a 23-amino acid signal peptide at the NH2 terminus of the precursor pro-alpha 2M. At the 3' end of the insert a poly(A) addition signal A-A-T-A-A-A and part of the poly(A) tail of the messenger RNA were found. The protein sequence deduced from the nucleotide sequence agrees with the published alpha 2M amino acid sequence for all except three residues. The alpha 2M locus was assigned to human chromosome 12 by Southern blot analysis with DNA from a panel of mouse/human somatic cell hybrids, using alpha 2M cDNA as a hybridization probe.

Nucleotide sequence of cDNA and derived amino acid sequence of human complement component C9

The nucleotide sequence coding for the ninth component of human complement (C9) has been determined and the corresponding amino acid sequence has been derived. A human liver cDNA library was screened by the colony-hybridization technique using two radiolabeled oligonucleotide probes that correspond to known regions of the C9 amino acid sequence. Two recombinant plasmids were isolated and their cDNA inserts were sequenced. The derived protein sequence consists of 537 amino acids in a single polypeptide chain. A profile of the hydropathic index versus sequence number indicates that the amino-terminal half of C9 is predominantly hydrophilic in character whereas the carboxyl-terminal section of this protein is more hydrophobic. The amphipathic organization of the primary structure of C9 is consistent with the known potential of polymerized C9 to penetrate lipid bilayers, causing the formation of transmembrane channels.