Structure of the τ60/Δτ91 Subcomplex of Yeast Transcription Factor IIIC: Insights into Preinitiation Complex Assembly

Yeast RNA polymerase III is recruited upon binding of subcomplexes tauA and tauB of transcription factor IIIC (TFIIIC) to the A and B blocks of tRNA gene promoters. The tauB subcomplex consists of subunits tau60, tau91, and tau138. We determined the 3.2 A crystal structure of tau60 bound to a large C-terminal fragment of tau91 (Deltatau91). Deltatau91 protein contains a seven-bladed propeller preceded by an N-terminal extension, whereas tau60 contains a structurally homologous propeller followed by a C-terminal domain with a novel alpha/beta fold. The two propeller domains do not have any detectable DNA binding activity and mediate heterodimer formation that may serve as scaffold for tau138 assembly. We show that the C-terminal tau60 domain interacts with the TATA binding protein (TBP). Recombinant tauB recruits TBP and stimulates TFIIIB-directed transcription on a TATA box containing tRNA gene, implying a combined contribution of tauA and tauB to preinitiation complex formation.

Prokaryotic Kdp-ATPase: recent insights into the structure and function of KdpB

P-type ATPases are amongst the most abundant enzymes that are responsible for active transport of ions across biological membranes. Within the last 5 years a detailed picture of the structure and function of these transport ATPases has emerged. Here, we report on the recent progress in elucidating the molecular mechanism of a unique, prokaryotic member of P-type ATPases, the Kdp-ATPase. The review focuses on the catalytic parts of the central subunit, KdpB. The structure of the nucleotide-binding domain was solved by NMR spectroscopy at high resolution and a model of the nucleotide-binding mode was presented. The nucleotide turned out to be 'clipped' into the binding pocket by a pi-pi interaction to F377 on one side and a cation-pi interaction to K395 on the other. The 395KGXXD/E motif and thus the nucleotide-binding mode seems to be conserved in all P-type ATPases, except the heavy metal-transporting (class IB) ATPases. Hence, it can be concluded that KdpB is currently misgrouped as class IA. Mutational studies on two highly conserved residues (D583 and K586) in the transmembrane helix 5 of KdpB revealed that they are indispensable in coupling ATP hydrolysis to ion translocation. Based on these results, two possible pathways for the reaction cycle are discussed.

[Combined medical treatment and psychotherapy in early-stage Alzheimer's over a period of 30 months]

The present case delineates the results of a 30-month combined pharmacological and psychotherapeutic treatment in a mildly to moderately depressed patient with early Alzheimer's dementia. At onset and during following visits, clinical examination and standardized test procedures for measuring cognitive and emotional changes were completed. Treatment results reveal a consistent benefit to cognitive levels and emotional distress over time. The present example of a mildly demented, depressed Alzheimer's patient shows a therapeutic outcome which is markedly superior to usual expectations in Alzheimer's treatment and encourages combination of therapeutic strategies in early stages of the disease.

The holo-form of the nucleotide binding domain of the KdpFABC complex from Escherichia coli reveals a new binding mode

P-type ATPases are ubiquitously abundant enzymes involved in active transport of charged residues across biological membranes. The KdpB subunit of the prokaryotic Kdp-ATPase (KdpFABC complex) shares characteristic regions of homology with class II-IV P-type ATPases and has been shown previously to be misgrouped as a class IA P-type ATPase. Here, we present the NMR structure of the AMP-PNP-bound nucleotide binding domain KdpBN of the Escherichia coli Kdp-ATPase at high resolution. The aromatic moiety of the nucleotide is clipped into the binding pocket by Phe(377) and Lys(395) via a pi-pi stacking and a cation-pi interaction, respectively. Charged residues at the outer rim of the binding pocket (Arg(317), Arg(382), Asp(399), and Glu(348)) stabilize and direct the triphosphate group via electrostatic attraction and repulsion toward the phosphorylation domain. The nucleotide binding mode was corroborated by the replacement of critical residues. The conservative mutation F377Y produced a high residual nucleotide binding capacity, whereas replacement by alanine resulted in low nucleotide binding capacities and a considerable loss of ATPase activity. Similarly, mutation K395A resulted in loss of ATPase activity and nucleotide binding affinity, even though the protein was properly folded. We present a schematic model of the nucleotide binding mode that allows for both high selectivity and a low nucleotide binding constant, necessary for the fast and effective turnover rate realized in the reaction cycle of the Kdp-ATPase.

Improvement of coping abilities in patients with systemic lupus erythematosus: a prospective study

OBJECTIVE

To evaluate a novel specific psychological intervention aimed at improving coping in patients with systemic lupus erythematosus (SLE).

METHODS

34 community living SLE patients were recruited for the study. Intervention was undertaken in groups of up to eight patients and in two blocks over six months each. Eight patients were enrolled as a waiting list group. The 18 group sessions focused on information about the disease and specific problems of SLE patients, combining psychoeducative and psychotherapeutic elements. Psychological and medical evaluations were conducted at baseline and after three, six, and 12 months, using validated instruments.

RESULTS

The 34 SLE patients (91% female, mean age 42 years) improved significantly over a six month period on most of the psychological measuring instruments applied, such as depression, anxiety, and overall mental burden. The waiting list group showed no significant changes.

CONCLUSIONS

Conceptualised psychoeducational support may produce a significant and sustained improvement in coping skills of SLE patients and hence in their quality of life.

[Treatment of Alzheimer's disease utilising the best available evidence-based medicine -- utopia?]

STUDY OBJECTIVES

To practice evidence-based medicine is considered to improve health care, particularly of chronically ill patients. Taking Alzheimer's as an example the objective of this study is to explore as to how far ambulatory Alzheimer's patients receive the medical treatment with the best evidence available.

METHOD

In 2000 and 2002 the health care situation of Alzheimer's disease patients was assessed by conducting telephone interviews with one hundred randomly selected general practitioners and specialists listed in the panel of the Institut fur Medizinische Statistik (IMS -- Institute for Medical Statistics). By means of a standardised questionnaire the interviewees' prescriptions were assessed as well as their knowledge of the medical therapy for Alzheimer's and the use of non-medical therapeutic measures. Besides, the interviewees' prescriptions were checked on the basis of quantitative data taken from the IMS panel. Cholinesterase inhibitors (ChE-I), which are accorded the best evidence presently available in the medical treatment of Alzheimer's, were seen as a marker for the improvement of health care in the course of the study.

RESULTS AND CONCLUSIONS

The interviewed physicians considered the evidence of medical Alzheimer's disease therapy with cholinesterase inhibitors high. 67 % of the interviewees would use ChE-I as the drug of first choice if a near relative fell ill with Alzheimer's. However, the ChE-I prescriptions were limited to 13 % in the base year 2000 and to 24 % in the base year 2002. Obviously, the implementation of this medical therapy is hampered by budgetary regulations. The interviewees find it particularly disadvantageous that the prescription of ChE-I may overstrain the budgets allocated to their practices. As a consequence, the effort to improve the quality of health care by implementing evidence-based medicine is thwarted by the increasing pressure on German physicians to prescribe drugs according to economic viability.

Inter-domain motions of the N-domain of the KdpFABC complex, a P-type ATPase, are not driven by ATP-induced conformational changes

P-type ATPases are involved in the active transport of ions across biological membranes. The KdpFABC complex (P-type ATPase) of Escherichia coli is a high-affinity K+ uptake system that operates only when the cell experiences osmotic stress or K+ limitation. Here, we present the solution structure of the nucleotide binding domain of KdpB (backbone RMSD 0.17 A) and a model of the AMP-PNP binding mode based on intermolecular distance restraints. The calculated AMP-PNP binding mode shows the purine ring of the nucleotide to be "clipped" into the binding pocket via a pi-pi-interaction to F377 on one side and a cation-pi-interaction to K395 on the other. This binding mechanism seems to be conserved in all P-type ATPases, except the heavy metal transporting ATPases (type IB). Thus, we conclude that the Kdp-ATPase (currently type IA) is misgrouped and has more similarities to type III ATPases. The KdpB N-domain is the smallest and simplest known for a P-type ATPase, and represents a minimal example of this functional unit. No evidence of significant conformational changes was observed within the N-domain upon nucleotide binding, thus ruling out a role for ATP-induced conformational changes in the reaction cycle.

[Outpatient treatment of patients suffering from Alzheimer dementia. Two exploratory studies on the characteristics of therapy in medical practice]

In two exploratory studies on the outpatient treatment of patients suffering from Alzheimer dementia research was done into the characteristics of therapy in medical practice on the basis of exemplary interviews of 100 doctors in 2000 and 2002. The interviewers discern the burden of the disease for the patients and their relatives. However, medical treatment is still too scarce and inappropriate as the prescribing of antidementia drugs shows, among which especially acetylcholinesterase inhibitors as drugs of first choice. The spectrum of non-pharmacological interventions is applied but psychosocial measures are under-represented. To maintain the Alzheimer patient's functional level and to thus relieve the caring relatives a multimodal therapy should be intensified preferably by comprehensive co-operations.

Psychische St�rungen bei rheumatischen Erkrankungen am Beispiel des Systemischen Lupus Erythematodes (SLE)

Among the rheumatic diseases, systemic lupus erythematosus (SLE) reveals the highest frequency of central nervous symptoms. Psychiatric abnormalities are present in over 90% of the patients, if very mild cognitive impairment is included. The psychiatric syndromes listed by the American College of Rheumatologists encompass cognitive syndromes, including the acute confusional state, anxiety disorders, depressive symptomatology and psychosis. Associations between cognitive impairment and demographic and disease variables, i. e. disease severity, have not been clearly identified so far. The same holds true for the evolution of depressive symptoms. Reactive depression in coping with a chronic disease is, however, a psychologically plausible factor in addition to specific cerebral lesions. Therapeutic interventions in SLE should consist of a combined pharmacological and nonpharmacological treatment. Corticosteroid drugs, however, may be effective in alleviating mild psychiatric symptoms as well.

[Early diagnosis and treatment of Alzheimer's disease. Implementation in the doctor's office]

The efficacy of antidemential agents proven in comprehensive studies and by clinical experience, now justifies an active and positive approach by the general physician to the diagnosis and treatment of patients with dementia. The proposals on how to implement diagnostic and therapeutic measures in the doctor's office comply both with medical quality criteria and the requirements for appropriateness of treatment and considerations of economy stipulated by German law. They therefore provide the basis for a modern diagnostic work-up and treatment strategy, which will also meet economical demands.

Infantile Alexander disease: a GFAP mutation in monozygotic twins and novel mutations in two other patients

Alexander disease (AD) is a rare disorder of cerebral white matter due to a dysfunction of astrocytes. The most common infantile form presents as a megalencephalic leukodystrophy. Recently, heterozygous de novo mutations in the glial fibrillary acidic protein gene (GFAP) have been demonstrated to be associated with AD. We report heterozygous mutations in GFAP in 5 patients, including a pair of monozygotic twins, with clinical and neuroradiological features of infantile AD. Novel mutations were detected affecting nucleotides 304 T --> C (L97 P) and 730 G --> C (R239 P) in two other patients. None of the parents of our patients carried the mutations stressing dominant de novo mutations as the cause of AD. The presence of an identical mutation 250 G --> A (R79 H) in both monozygotic twins with infantile AD points to the origin of these GFAP mutations in germ cells or very early postzygotic stages.

[Is it Alzheimer disease? Recognizing the first signs of dementia syndrome]

Today, early diagnosis of different forms of dementia is possible with a relatively easy-to-apply set of diagnostic tools. The quality of the medical history, including the information supplied by relatives and friends, together with the psychological and physical findings, determine the diagnostic hit rate. Laboratory investigations and imaging techniques are indispensable for detecting the underlying cause of existing dementia. Standardized rapid screening procedures for the identification of mild cognitive deficits have speeded up the reliable selection of suspicious cases needing referral to a specialist. Identification of individual day-to-day problems and non-cognitive disorders round off the diagnosis of dementia, and establish the conditions for planning a suitable treatment strategy.

Improvement of agitation and anxiety in demented patients after psychoeducative group intervention with their caregivers

OBJECTIVES

It has been convincingly demonstrated that in dementia, psychoeducative group intervention with caregivers positively impacts on motivation for care and satisfaction of the caregivers. It has, however, been neglected to examine the effect of psychoeducative group intervention on the behavioural and psychological symptoms of the demented patients.

METHODS

In a 3-month, expert-based and conceptualized group intervention with caregiving relatives of demented patients we investigated whether behavioural and psychological symptoms may improve and which of a set of independent variables may predict improvement.

RESULTS

The 3-month group intervention yielded a significant improvement in agitation and anxiety of the demented patients. The presence of an additional somatic disease in the patients and male gender predicted a less positive outcome of the intervention related to the presence of agitation.

CONCLUSIONS

This study demonstrated that psychoeducative group intervention with the caregivers of demented patients is helpful for the demented patients themselves. This evidence of a positive mediator effect of the group intervention on the behavioural and psychological symptoms of the patients underscores the importance of nonpharmacological strategies in the treatment of dementia.