Assessing the impact of a patient education programme on pressure ulcer prevention in patients with spinal cord injuries

OBJECTIVES

There is currently a low level of evidence for the impact of patient education on the management of patients with chronic neurological disease at risk of developing pressure ulcers. The objective of this study was to assess the impact of a patient education programme on pressure ulcer prevention in patients with chronic spinal cord injuries.

MATERIALS AND METHODS

This study included adult patients with any spinal cord injury, regardless of the cause. Participants attended 2 group workshops focusing on pressure ulcer prevention. Various clinical data were gathered during an initial individual interview and at 3, 6 and 12 months, along with rating scale values from the Hospital Anxiety and Depression Scale, Rosenberg self-esteem scale, Schwarzer self-efficacy scale, a quality of life scale (SF-36) and the revised Skin Management Needs Assessment Checklist (Revised SMnac), which was used as the primary endpoint.

RESULTS

Twenty patients were included in the study. The mean patient age was 52 years (SD: 9,8). Sixteen patients had traumatic spinal cord injuries, with a median injury duration of 234 months (IQR: 123-407). Seventy-five percent had had a pressure ulcer in the twelve months prior to the study. Patient education was shown to have a significant impact on skin management ability, with a highly significant increase in the overall revised SMnac score at 3 months. These results were stable over time, from 6 to 12 months. Six patients developed a pressure ulcer during the study (30%).

CONCLUSION

This study supports the hypothesis that a therapeutic educational program conducted at the chronic phase in spinal cord injured individuals has an impact.

Physical training and multiple sclerosis

For many years, patients with multiple sclerosis (MS) were advised to avoid exercise because of the risk of increased neurological impairment. This article reviews the literature related to MS and physical exercise. Physical exercise depends on patients' physiological tolerance and response to exercise. MS patients can exhibit dysfunction of cardiovascular adjustment accompanied by respiratory involvement, which can alter aerobic capacity. These abnormalities tend to increase with the neurological impairment. Muscle weakness is the consequence of not only altered central motor drive but also disuse. Several studies have shown the benefits of physical training, with improvements in aerobic capacity, gait parameters and fatigue, and an influence on quality of life. Regular aerobic physical activity is necessary to maintain the benefit of physical training.

Rickettsia felis, from culture to genome sequencing

Rickettsia felis has been recently cultured in XTC2 cells. This allows production of enough bacteria to create a genomic bank and to sequence it. The chromosome of R. felis is longer than that of previously sequenced rickettsiae and it possess 2 plasmids. Microscopically, this bacterium exhibits two forms of pili: one resembles a conjugative pilus and another forms hair-like projections that may play a role in pathogenicity. R. felis also exhibits several copies of ankyrin-repeat genes and tetratricopeptide encoding gene that are specifically linked to pathogenic host-associated bacteria. It also contains toxin-antitoxin system encoding genes that are extremely rare in intracellular bacteria and may be linked to plasmid maintenance.

Activité sportive et sclérose en plaques

INTRODUCTION

Multiple sclerosis (MS) is a neurological disease of the central nervous system that most often affects young people. It is characterized by various debilitating symptoms. The aim of this study was to assess physical activities in patients with MS and how these affect their quality of life.

METHODS

Forty-five patients were questioned about their physical activities. The following were taken into account: the characteristics of MS within each patient, the level of disease severity (EDSS score) and the quality of life (on the SEP-59 questionnaire).

RESULTS

Fifteen patients had to give up a physical activity because of their illness but more so due to ataxia, fatigue and muscular weakness. Fifteen patients take part in a physical activity, the principal motivation being for their personal well-being. The mean EDSS was 4.2. Answers on the SEP-59 revealed found that patients with MS who took part in a physical activity had significantly better well-being in general.

DISCUSSION AND CONCLUSION

Physical activities seem to improve the quality of life of patients with MS who, in general, already have a poor quality of life in relation to the general population. Knowing that muscular function is improved through exercise in patients with an EDSS less than 6, it would seem advantageous for them to take part in a regular physical activity.

Effects of pregnancy and childbirth on the incidence of urinary disorders in multiple sclerosis

OBJECTIVE

Women with multiple sclerosis frequently pose questions to physicians regarding the potential negative impact of pregnancy, especially on urinary disorders. About 50 to 80% of patients suffer from urinary disorders during the course of the disease. Trauma to the pelvic floor and the urethral sphincter during vaginal delivery may lead to the development of stress urinary incontinence. The purpose of this work was to study the consequences of pregnancy and childbirth on urinary problems.

STUDY DESIGN

An inception cohort of 368 consecutive women suffering from multiple sclerosis (MS), according to the Poser criteria, were included in the study between June 1999 and June 2000. For each patient a full urological and obstetrical record was obtained.

RESULTS

Two hundred and seventy-three women (74%) had had at least one pregnancy. The parous women were older at the time of the study (mean age: 45.5 years vs 35.5 years), and were older at MS onset (mean age: 32.8 years vs 25.7 years). The nulliparous women were more rapidly disabled, with a shorter time to reach an EDSS score of 3 from MS onset (mean time of 5.9 years versus 8.2 years in parous women). In parous women, 259 (95%) had had at least one vaginal delivery and 14 (5%) had had a caesarean only. Delivery modalities had no influence on urinary disorder frequency or the type of problems.

CONCLUSION

On the basis of these data, there is actually no clear argument for systematically performing caesarean section in MS women. Urinary disorders in these women were mostly linked to the duration and the severity of the disease but not to pregnancy or delivery modalities. From our point of view, caesarean section must be decided only on classic obstetrical criteria as for healthy women independently of multiple sclerosis. However our data were open and retrospective.

Preliminary Transcriptional Analysis of spoT Gene Family and of Membrane Proteins in Rickettsia conorii and Rickettsia felis

Rickettsiae survival implicates adaptation to different environmental conditions. We hypothesized that multiple copies of genes in bacteria with reduced genomes might account for such a process. Transcription of spoT and sca paralogs was thus analyzed in R. conorii and R. felis.

Maintien à domicile et qualité de vie à distance d'un accident vasculaire cérébral

INTRODUCTION

Stroke is the most disabling chronic disease among adults. The assessment of quality of life is of great importance to improve the management of patients with stroke sequelae returning to the community.

METHOD

A total of 93 patients and their referring clinicians were contacted. Quality of life of patients three years after stroke was assessed by use of the Short-Form Health Survey (SF-36).

RESULTS

Thirteen patients died during this period. Fifty participated in the study. The average age was 66.8 years. The patients who died were older and had an initial greater impairment after stroke than survivors. In most of the cases, a life plan, built during the inpatient rehabilitation period, could be achieved. Just six patients had to change their way of life during the three years after stroke. A total of 44% of the patients needed human assistance for basic daily living activities. Patients with stroke had lower scores on the SF-36 than their healthy peers. All subscale scores differed for patients with stroke, as compared with health peers. Initial disability, the occurrence of falls, age and urinary incontinence at the time of the study indicated poor prognosis.

DISCUSSION

Our results are close to those previously published: a great number of people who survive stroke live with sequelae that requires assistance in the home and have decreased quality of life. These results stress the importance of follow-up by a rehabilitation team to prevent altered quality of life, with a special care to urinary incontinence and falls, especially in old people with abundant sequelae of stroke.

[Interest of visual biofeedback training in rehabilitation of balance after stroke]

OBJECTIVE

The aim of this study was the assessment of visual biofeedback in the management of balance disorders after stroke.

MATERIAL AND METHODS

This is a prospective randomised trial, which compares visual biofeedback training and traditional balance training. Twenty-seven patients took part in this study: 13 in the first group and 14 in the second group. The rehabilitation program in the first group consists in an association of visual biofeedback and traditional training during 3 weeks. For the second group traditional training was used alone. Clinical, functional and forceplate assessments were performed before and after the program of rehabilitation.

RESULTS

All the patients had a clinical and functional improvement. However, patients who have benefited from biofeedback training had a significant improvement of the forceplate parameters with closed eyes.

DISCUSSION AND CONCLUSION

Those results confirm the interest of rehabilitation in balance disorders after stroke. The use of biofeedback training incorporated into functional physiotherapy affords added benefits probably by a best integration of proprioceptive informations.

Renforcement musculaire isocinétique excentrique des ischiojambiers chez des patients atteints de sclérose en plaque

OBJECTIVE

To assess the benefit of a program of rehabilitation involving eccentric isokinetic muscle strengthening for hamstrings of patient with multiple sclerosis.

PATIENTS AND METHODS

A total of 28 patients with multiple sclerosis and abnormalities when walking who underwent a program of rehabilitation involving eccentric isokinetic muscle strengthening associated with classical neurological rehabilitation. Assessment was by use of an isokinetic test, clinical examination and score on a visual analog scale (VAS) about quality of walking at the beginning and end of the rehabilitation program and three months later. The rehabilitation program involved eccentric isokinetic exercises during 12 sessions.

RESULTS

Patients with multiple sclerosis and difficulty walking showed weak hamstrings on manual muscular testing. After 12 sessions of isokinetic eccentric rehabilitation, hamstring and quadriceps strength increased, VAS score increased, and recurvatum of the knee improved in 26 cases. Three months later, the score for quality of walking remained the same, but that for strength returned to a previous level.

CONCLUSION

Hamstring strength in patients with multiple sclerosis can be improved without complication with use of eccentric isokinetic rehabilitation. This is an interesting way to improve the quality of walking in these patients.

[Recommendations for the installation in the laboratory of metrological functions and corresponding documentation (Document B)]

In order to ensure the quality of analytical results, clinical laboratories shall have a perfect control of process and equipments of measurement. Therefore is recommended individualisation of metrological function, generally entrusted the quality manager. This quality manager will draw up a metrological traceability, verifications and confirmations, control of non conformities, follow-up and evaluation of metrological function.

Influence des variations de la température sur la symptomatologie clinique dans la sclérose en plaques : étude épidémiologique

The effects of the modifications of temperature are well known in patients affected by multiple sclerosis (MS). They are variable and can influence daily living. This sensibility can be used in the management of the disabilities.

METHOD

An epidemiological study was realized on a cohort of 191 patients suffering from MS referred to the MS clinic of Rennes (France). All the patients were questioned about the influence of heat and cold on their clinical symptoms (fatigue spasticity, walking disorders, vision, em leader ). Correlations with the main clinical characteristics were studied.

POPULATION

One hundred ninety-one patients, 129 women and 62 men with an average age of 47.6 +/- 10 years were interviewed. Average score EDSS was of 5.2 +/- 1.5. The mean duration of MS was 13.5 +/- 10 years.

RESULTS

One hundred forty-seven patients (77%) reported a sensibility to the temperature. Heat deteriorated function in 104 cases and 82 patients improved with cold. Paradoxically 20 patients reported to be deteriorated with cold and 19 improved with heat. Fatigue and walking were the most sensitive to temperature fluctuations. No particular clinical profile could be established. Fifty percent of the patients used this sensibility with therapeutic aim in everyday life.

DISCUSSION

The clear influence of temperature fluctuations on the clinical symptom was confirmed in this study. However, there is a great variability from one patient to another. Different hypotheses have been evoked to explain this phenomenon. The most likely is an influence on the nervous specific conductivity. In routine practice cold physiotherapy will be proposed on case by case basis and still has an interesting place in the rehabilitation management.

[Presentation for the use of a clinical laboratories of standards of metrology (Document A)]

Clinical laboratories shall have a perfect control of "in vitro diagnostic medical devices" to ensure the quality of their analytical results. This introductory presentation to a serie of documents of recommendations tackles the different standards of metrology concerning the requirements to reference materials, metrological traceability, metrological confirmation, management of measurement as well as uncertainty of measurement. The standards concerning clinical laboratories are then succinctly described.

[Musculoskeletal disorders in instrumental musicians: epidemiological study]

OBJECTIVES

To evaluate the frequency and types of musculoskeletal problems of French instrumental musicians.

METHODS

Voluntary musicians answered an anonymous questionnaire about their musical practices, their medical history, and the evaluation of the troubles they feel during playing music. The musicians have been contacted in music schools, professional and not-professional orchestras.

RESULTS

During this study 635 musicians received a questionnaire. 141 answered it (22.5%): 76.6% suffer from overuse syndrome, 17% from entrapment neuropathies, 5.7% from occupational hand cramp. The main topographies are spine (60.9%) and wrist and hand (52.5%). Instrumental characteristics are exposed.

CONCLUSION

Instrumental musicians often present musculoskeletal problems. A specific management would be useful to limit eventual drammatical consequences.

Binding site of brefeldin A at the interface between the small G protein ADP-ribosylation factor 1 (ARF1) and the nucleotide-exchange factor Sec7 domain

Sec7 domains (Sec7d) catalyze the exchange of guanine nucleotide on ARFs. Recent studies indicated that brefeldin A (BFA) inhibits Sec7d-catalyzed nucleotide exchange on ARF1 in an uncompetitive manner by trapping an early intermediate of the reaction: a complex between GDP-bound ARF1 and Sec7d. Using (3)H-labeled BFA, we show that BFA binds to neither isolated Sec7d nor isolated ARF1-GDP, but binds to the transitory Sec7d-ARF1-GDP complex and stabilizes it. Two pairs of residues at positions 190-191 and 198-208 (Arno numbering) in Sec7d contribute equally to the stability of BFA binding, which is also sensitive to mutation of H80 in ARF1. The catalytic glutamic (E156) residue of Sec7d is not necessary for BFA binding. In contrast, BFA does not bind to the intermediate catalytic complex between nucleotide-free ARF1 and Sec7d. These results suggest that, on initial docking steps between ARF1-GDP and Sec7d, BFA inserts like a wedge between the switch II region of ARF1-GDP and a surface encompassing residues 190-208, at the border of the characteristic hydrophobic groove of Sec7d. Bound BFA would prevent the switch regions of ARF1-GDP from reorganizing and forming tighter contacts with Sec7d and thereby would maintain the bound GDP of ARF1 at a distance from the catalytic glutamic finger of Sec7d.

Sensory-motor and genito-sphincter dysfunctions in multiple sclerosis

Multiple sclerosis is a chronic demyeliniting disease of the central nervous system which is characterized by an extreme multiplicity of clinical features. Multiple sclerosis can have a profound impact on the quality of life of patients. The induced handicap varies from one patient to an other, and depends on the location of the demyeliniting lesions. Among the symptoms, sensory-motor disorders and genito-sphincter dysfunctions are some of the more disabling. Thus, up to 70% of patients suffer from urinary troubles, and 15 years after the onset of the illness, 50% of patients have difficulties for deambulation. A good knowledge of these pathologies is necessary to improve the management of patients suffering from multiple sclerosis.

Brefeldin A acts to stabilize an abortive ARF-GDP-Sec7 domain protein complex: involvement of specific residues of the Sec7 domain

We demonstrate that the major in vivo targets of brefeldin A (BFA) in the secretory pathway of budding yeast are the three members of the Sec7 domain family of ARF exchange factors: Gea1p and Gea2p (functionally interchangeable) and Sec7p. Specific residues within the Sec7 domain are important for BFA inhibition of ARF exchange activity, since mutations in these residues of Gea1p (sensitive to BFA) and of ARNO (resistant to BFA) reverse the sensitivity of each to BFA in vivo and in vitro. We show that the target of BFA inhibition of ARF exchange activity is an ARF-GDP-Sec7 domain protein complex, and that BFA acts to stabilize this complex to a greater extent for a BFA-sensitive Sec7 domain than for a resistant one.

Overexpression of the ARF1 exchange factor ARNO inhibits the early secretory pathway and causes the disassembly of the Golgi complex

The small GTPase ARF1 is a key regulator of intracellular membrane traffic. In its active, GTP-bound form, ARF1 is associated with Golgi membranes and promotes the recruitment of the cytosolic coat protein complex, which will result in membrane budding and vesicle formation. ARNO (ARF nucleotide site opener) has been shown to act in vitro as a GTP exchange factor for ARF1. Here, we have investigated the function of ARNO in vivo. By immunofluorescence and cell fractionation, ARNO was found to be mostly cytosolic in HeLa cells. Its overexpression led to a strong inhibition of the secretion of SEAP (secreted form of alkaline phosphatase). Newly synthesized SEAP failed to acquire endoglycosidase H resistance, indicating a block in the early secretory pathway. This effect on secretion was accompanied by a disassembly of the Golgi complex and a redistribution of Golgi resident proteins into the endoplasmic reticulum (ER). On the other hand, ARNO overexpression did not affect the early endocytic pathway. These results show that ARNO functions in vivo in Golgi to ER transport. Its behavior is then consistent with ARNO being an exchange factor for ARF1.

Influence of urinary management on urologic complications in a cohort of spinal cord injury patients

OBJECTIVE

To study urologic complications in patients with spinal cord injury (SCI) in relation to their bladder management.

DESIGN AND SETTING

A cohort study of patients with SCI in a rehabilitation center.

PARTICIPANTS

One hundred eighty-two patients were studied; demographic data, disease characteristics, and urologic history were obtained for each.

INTERVENTION

Patients responding to a questionnaire were given a clinical exam. Their medical records were reviewed, with particular attention given to the following urologic complications: lithiasis, urinary infections, orchiepididymitis, urethral trauma, vesicorenal reflux, and renal failure.

RESULTS

Results are reported for 123 patients. Time since SCI was 8 years. Intermittent catheterization was the main method of bladder management. Only 32 patients had changed their method of vesical voiding. Urinary complications had developed in 75% of patients. The most common complication was urinary infection. Vesicoureteral reflux occurred in 26% of patients using percussion. Trauma related to catheterization was the main problem with intermittent catheterization, responsible for a high rate of orchiepididymitis.

CONCLUSION

Intermittent catheterization is the most-used method of bladder management, but with a nonnegligible rate of urethral trauma in men. Percussion and Credé maneuver appear to be acceptable techniques of bladder management if the patient is closely monitored.

ARNO3, a Sec7-domain guanine nucleotide exchange factor for ADP ribosylation factor 1, is involved in the control of Golgi structure and function

Budding of transport vesicles in the Golgi apparatus requires the recruitment of coat proteins and is regulated by ADP ribosylation factor (ARF) 1. ARF1 activation is promoted by guanine nucleotide exchange factors (GEFs), which catalyze the transition to GTP-bound ARF1. We recently have identified a human protein, ARNO (ARF nucleotide-binding-site opener), as an ARF1-GEF that shares a conserved domain with the yeast Sec7 protein. We now describe a human Sec7 domain-containing GEF referred to as ARNO3. ARNO and ARNO3, as well as a third GEF called cytohesin-1, form a family of highly related proteins with identical structural organization that consists of a central Sec7 domain and a carboxy-terminal pleckstrin homology domain. We show that all three proteins act as ARF1 GEF in vitro, whereas they have no effect on ARF6, an ARF protein implicated in the early endocytic pathway. Substrate specificity of ARNO-like GEFs for ARF1 depends solely on the Sec7 domain. Overexpression of ARNO3 in mammalian cells results in (i) fragmentation of the Golgi apparatus, (ii) redistribution of Golgi resident proteins as well as the coat component beta-COP, and (iii) inhibition of SEAP transport (secreted form of alkaline phosphatase). In contrast, the distribution of endocytic markers is not affected. This study indicates that Sec7 domain-containing GEFs control intracellular membrane compartment structure and function through the regulation of specific ARF proteins in mammalian cells.

Molecular and biochemical analysis of Saccharomyces cerevisiae cox1 mutants

We report on the molecular and biochemical analysis of a set of 13 respiratory deficient mutants of Saccharomyces cerevisiae which are specifically altered in COX1, the gene encoding the subunit Cox1p of cytochrome c oxidase. DNA sequence analysis shows that three are due to frameshift mutations, two to nonsense mutations, and eight to missense mutations. All, except the missense mutant S157L, have impaired electron transfer and respiratory activity. Analysis of the mitochondrial translation products shows that when Cox1p is absent, Cox2p and Cox3p are still synthesized. In the missense mutants, the steady state levels in the mitochondrial membranes of the three mitochondrially encoded subunits Cox1p, Cox2p and Cox3p and the nuclear-encoded subunit Cox4p are reduced. In the frameshift and nonsense mutants, Cox1p is absent and Cox2p, Cox3p and Cox4p are considerably decreased or undetectable. A comparison of the steady state levels of Cox1p through Cox4p in the COX1, COX2, COX3 and COX4 mutants shows the interdependance of the accumulation of these four subunits in the mitochondrial membranes.

A glutamic finger in the guanine nucleotide exchange factor ARNO displaces Mg2+ and the beta-phosphate to destabilize GDP on ARF1

The Sec7 domain of the guanine nucleotide exchange factor ARNO (ARNO-Sec7) is responsible for the exchange activity on the small GTP-binding protein ARF1. ARNO-Sec7 forms a stable complex with the nucleotide-free form of [Delta17]ARF1, a soluble truncated form of ARF1. The crystal structure of ARNO-Sec7 has been solved recently, and a site-directed mutagenesis approach identified a hydrophobic groove and an adjacent hydrophilic loop as the ARF1-binding site. We show that Glu156 in the hydrophilic loop of ARNO-Sec7 is involved in the destabilization of Mg2+ and GDP from ARF1. The conservative mutation E156D and the charge reversal mutation E156K reduce the exchange activity of ARNO-Sec7 by several orders of magnitude. Moreover, [E156K]ARNO-Sec7 forms a complex with the Mg2+-free form of [Delta17]ARF1-GDP without inducing the release of GDP. Other mutations in ARNO-Sec7 and in [Delta17]ARF1 suggest that prominent hydrophobic residues of the switch I region of ARF1 insert into the groove of the Sec7 domain, and that Lys73 of the switch II region of ARF1 forms an ion pair with Asp183 of ARNO-Sec7.

Treatment of detrusor sphincter dyssynergia by transperineal injection of botulinum toxin

Detrusor-sphincter dyssynergia is an involuntary contraction of the external urethral sphincter during the detrusor contraction. It causes voiding dysfunction and can lead to urologic complications such as hydroureteronephrosis and renal failure. Patients with spinal cord injuries are particularly vulnerable. Botulinum toxin has been used via cystoscopy to decrease the activity of the external urethral sphincter. This report describes the treatment of 5 tetraplegic patients by single transperineal injections of botulinum toxin for detrusor-sphincter dyssynergia, proved by a urodynamic study with electromyography. A total of 15 injections was given, resulting in improved bladder function in all patients. Urodynamic assessment after treatment showed an increase of the functional detrusor capacity and a decrease of the maximal detrusor pressure during voiding. These results confirm the consideration of botulinum toxin as a treatment for detrusor sphincter dyssynergia. A single transperineal injection is a valuable, less invasive treatment using a cystoscopic technique.

Structure of the Sec7 domain of the Arf exchange factor ARNO

Small G proteins switch from a resting, GDP-bound state to an active, GTP-bound state. As spontaneous GDP release is slow, guanine-nucleotide-exchange factors (GEFs) are required to promote fast activation of small G proteins through replacement of GDP with GTP in vivo. Families of GEFs with no sequence similarity to other GEF families have now been assigned to most families of small G proteins. In the case of the small G protein Arf1, the exchange of bound GDP for GTP promotes the coating of secretory vesicles in Golgi traffic. An exchange factor for human Arf1, ARNO, and two closely related proteins, named cytohesin 1 and GPS1, have been identified. These three proteins are modular proteins with an amino-terminal coiled-coil, a central Sec7-like domain and a carboxy-terminal pleckstrin homology domain. The Sec7 domain contains the exchange-factor activity. It was first found in Sec7, a yeast protein involved in secretion, and is present in several other proteins, including the yeast exchange factors for Arf, Geal and Gea2. Here we report the crystal structure of the Sec7 domain of human ARNO at 2 A resolution and the identification of the site of interaction of ARNO with Arf.

Vesicourethral dysfunction and urodynamic findings in multiple sclerosis: a study of 149 cases

OBJECTIVE

Vesicourethral dysfunction is common in people with multiple sclerosis and results in significant impairment. We studied the clinical and urodynamic findings in such patients to define risk factors for incontinence and upper urinary tract infections.

DESIGN AND SETTING

A cohort study of 149 patients with multiple sclerosis and urinary symptoms seen in our urodynamic laboratory.

INTERVENTION

A complete urodynamic study of each patient with urethrocystometry and continuous recording of the urethral sphincter electromyography and assessment of postvoid residual.

RESULTS

Detrusor hyperreflexia and sphincter dyssynergia were the main dysfunctions. No significant relation between clinical features and urodynamic patterns was found. Women with low maximal urethral pressure were particularly prone to incontinence, which occurred in 69% of the patients. Pyelonephritis was associated with a postvoiding residual urine of > 30% of the functional detrusor capacity, and was found more often in the male population.

CONCLUSION

Urodynamic assessment of bladder function is critical to direct therapy for urinary complaints in people with multiple sclerosis.

Role of protein-phospholipid interactions in the activation of ARF1 by the guanine nucleotide exchange factor Arno

Arno is a 47-kDa human protein recently identified as a guanine nucleotide exchange factor for ADP ribosylation factor 1 (ARF1) with a central Sec7 domain responsible for the exchange activity and a carboxyl-terminal pleckstrin homology (PH) domain (Chardin, P., Paris, S., Antonny, B., Robineau, S., Béraud-Dufour, S., Jackson, C. L., and Chabre, M. (1996) Nature 384, 481-484). Binding of the PH domain to phosphatidylinositol 4,5-bisphosphate (PIP2) greatly enhances Arno-mediated activation of myristoylated ARF1. We show here that in the absence of phospholipids, Arno promotes nucleotide exchange on [Delta17]ARF1, a soluble mutant of ARF1 lacking the first 17 amino acids. This reaction is unaffected by PIP2, which suggests that the PIP2-PH domain interaction does not directly regulate the catalytic activity of Arno but rather serves to recruit Arno to membranes. Arno catalyzes the release of GDP more efficiently than that of GTP from [Delta17]ARF1, and a stable complex between Arno Sec7 domain and nucleotide-free [Delta17]ARF1 can be isolated. In contrast to [Delta17]ARF1, full-length unmyristoylated ARF1 is not readily activated by Arno in solution. Its activation requires the presence of phospholipids and a reduction of ionic strength and Mg2+ concentration. PIP2 is strongly stimulatory, indicating that binding of Arno to phospholipids is involved, but in addition, electrostatic interactions between phospholipids and the amino-terminal portion of unmyristoylated ARF1GDP seem to be important. We conclude that efficient activation of full-length ARF1 by Arno requires a membrane surface and two distinct protein-phospholipid interactions: one between the PH domain of Arno and PIP2, and the other between amino-terminal cationic residues of ARF1 and anionic phospholipids. The latter interaction is normally induced by insertion of the amino-terminal myristate into the bilayer but can also be artificially facilitated by decreasing Mg2+ and salt concentrations.

Suppressors of cis-acting splicing-deficient mutations that affect the ribozyme core of a group II intron

Many of the cis-dominant mutations that lead to respiratory deficiency by preventing maturation of specific yeast mitochondrial transcripts are found to affect the ribozyme core of group I and group II introns. We have searched for suppressors of mutations in the ribozyme-encoding sections of a group II intron, the first intron in the COX1 gene of Saccharomyces cerevisiae, which was independently subjected to in vitro site-directed mutagenesis. Three of the original mutants bore multiple mutations, which act synergistically, since for most individual mutations, suppressors could be obtained that ensured at least partial recovery of respiratory competence and splicing. Out of a total of ten suppressor mutations that were identified, three were second-site substitutions that restored postulated base-pairings in the ribozyme core. Remarkably, and as is observed for group I introns, at least half of the cis-dominant mutations in the first two group II introns of the COX1 gene affect sites that have been shown to participate in RNA tertiary interactions. We propose that this bias reflects cooperativity in the formation of ribozyme tertiary but not secondary structure, on the one hand, and the need for synergistic effects in order to generate a respiratory-deficient phenotype in the laboratory on the other. Finally, a novel in vivo splicing product of mutant cells is attributed to bimolecular splicing at high concentrations of defective transcripts.

A human exchange factor for ARF contains Sec7- and pleckstrin-homology domains

The small G protein ARF1 is involved in the coating of vesicles that bud from the Golgi compartments. Its activation is controlled by as-yet unidentified guanine-nucleotide exchange factors. Gea1, the first ARF exchange factor to be discovered in yeast, is a large protein containing a domain of homology with Sec7, another yeast protein that is also involved in secretion. Here we characterized a smaller human protein (relative molecular mass 47K) named ARNO, which contains a central Sec7 domain that promotes guanine-nucleotide exchange on ARF1. ARNO also contains an amino-terminal coiled-coil motif and a carboxy-terminal pleckstrin-homology (PH) domain. The PH domain mediates an enhancement of ARNO exchange activity by negatively charged phospholipid vesicles supplemented with phosphatidylinositol bisphosphate. The exchange activity of ARNO is not inhibited by brefeldin A, an agent known to block vesicular transport and inhibit the exchange activity on ARF1 in cell extracts. This suggests that a regulatory component which is sensitive to brefeldin A associates with ARNO in vivo, possibly through the amino-terminal coiled-coil. We propose that other proteins with a Sec7 domain regulate different members of the ARF family.

Sequence of a 39,411 bp DNA fragment covering the left end of chromosome VII of Saccharomyces cerevisiae

We have sequenced a DNA fragment of 39,411 bp which includes part of the left telomere of chromosome VII of Saccharomyces cerevisiae. We have identified 19 open reading frames (ORFs); six correspond to known yeast genes (ADH4, FZF1, HKB, RTG2, HFM1 and PDE1), nine have similarity with other genes and four exhibit no significant similarity with any known gene. The average size of these ORFs seems to be related to their location, the eight ORF's nearest the telomere being shorter than the 11 others. These two groups of genes are separated by a region of 4.5 kb devoid of significant ORFs. One ORF, NRF120, is a new member of the seripauperine family, represented once in all sequenced yeast chromosomes, in a subtelomeric location.

The reflex sympathetic dystrophy syndrome in patients who have had a spinal cord injury

Patients suffering from a spinal cord injury often present with a pain syndrome. Although the reflex sympathetic syndrome is a common diagnosis in some forms of neurological disease such as patients with a stroke, it is less frequent in those with a spinal lesion. The authors report eight patients with reflex sympathetic dystrophy who had a spinal cord injury. The diagnosis and treatment are discussed along with a review of literature.

Mutations in the mitochondrial split gene COXI are preferentially located in exons: a mapping study of 170 mutants

We have analysed the precise location of a large number (170) of mutations affecting the structural gene for subunit I of the cytochrome c oxidase complex. This gene, COXI, is 12.9 kb long and the major part of the sequence (i.e. 11.3 kb) is composed of introns. Several conclusions can be drawn from this study: (1) A significant proportion (84/170) of the mutations cannot be assigned to a single position within the gene by deletion mapping, in spite of clearly being located in it. These mutations are probably large deletions or multiple mutations. (2) Four mutants carry distant double mutations, which have been individually localized. (3) Eighty-two mutants have lesions that are restricted to very short regions of the gene and we therefore conclude that they are most probably due to single hits; amongst these single mutations, 41 are unambiguously located in exons and 28 in introns. This result implies that, at least in this particular split gene, the probability of selection of a mutant phenotype in an exon is, on the average, 13.3 times greater than in an intron, in spite of the existence, within most of these introns, of open reading frames specifying intronic proteins. The evolutionary significance and biological implications of these results are discussed.

[Heterotopic ossification and vascular compression]

Heterotopic ossification is common in patients with spinal cord or brain injury. Whereas the articular complications of heterotopic ossification have been well documented, the vascular complications are less well known. We report three cases with vascular compression and discuss the diagnosis and treatment in the light of a review of the literature.

Sequence analysis of three deficient mutants of cytochrome oxidase subunit I of Saccharomyces cerevisiae and their revertants

Three respiratory-deficient mutants of cytochrome oxidase subunit I in the yeast mitochondrion have been sequenced. They are located in, or near, transmembrane segment VI, the catalytic core of the enzyme. Respiratory-competent revertants have been selected and studied. The mutant V244M was found to revert at the same site in valine (wild-type), isoleucine or threonine. The revertants of the mutant G251R were of three types: glycine (wild-type), serine and threonine at position 251. A search for second-site mutations was carried out but none were found. Among 60 revertants tested, the mutant K265M was found to revert only to the wild-type allele.

The unusual reversion properties of a mitochondrial mutation in the structural gene of subunit I of cytochrome oxidase of Saccharomyces cerevisiae reveal a probable histidine ligand of the redox center

We have analyzed a mutation in the mitochondrial gene oxi3 coding for subunit I of cytochrome-oxidase in the yeast Saccharomyces cerevisiae. This mutation replaces one of the seven invariant histidines of the polypeptide (position 378) by a tyrosine, and leads to a respiratory deficient phenotype. A total of 157 revertants, which have recovered the ability to grow on a respiratory substrate, have been selected from this mutant (tyrosine 378). The nature of the reversion has been analysed by a rapid screening procedure and 32 of the revertants have been sequenced. They are all true back-mutations reintroducing the histidine in position 378. This very exceptional situation suggests that this histidine is a ligand of the redox center of cytochrome oxidase.

The differential overamplification of short sequences in the mitochondrial DNA of rho- petites in Saccharomyces cerevisiae stimulates recombination

It is well known that the yeast Saccharomyces cerevisiae can be affected by mutations, called 'petite colonie', which correspond to the loss of the major part of the mitochondrial DNA and the concomitant amplification of the remaining sequence, the basic repeat unit (BRU). We describe here a new phenomenon, the internal overamplification (IOA), due to the differential amplification (up to 20-fold) of short sequences within the BRU. These IOAs are very stable and stimulate the recombination. We discuss here the possible mechanisms giving rise to the appearance and maintenance of the IOAs within the BRU and their effect on the recombination process.