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1.
Eur J Paediatr Neurol ; 20(4): 524-31, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27155820

ABSTRACT

AIM: To characterise children with cerebral palsy (CP) and pathological drooling in France, and to describe care pathways, assessment and treatment. METHOD: A transversal, observational, descriptive survey of the practices and opinions of 400 health professionals potentially involved in the care of children with CP, was carried out nationally across France in 2013. RESULTS: The response rate was 36%. Seventy-five questionnaires were returned and analysed (52%). A small proportion of children were specifically treated for drooling (<25%). Assessments were carried out in 75% of cases and 91% of professionals prescribed treatments. Use of assessment tools varied widely. The most common treatment was oro-facial rehabilitation (95% of professionals), followed by anticholinergic drugs (Scopolamine(®)) (94%) botulinum toxin injections (BT) (66%) and surgery (34%). Scopolamine was considered to be less effective than BT and to have more side effects. CONCLUSION: The rate of pathological drooling in children with CP is likely underestimated and under treated in France. There is a lack of knowledge regarding assessment tools. Aside from rehabilitation, current practice is to prescribe medication as the first-line treatment, however professionals consider that BT is more effective and has less side effects.


Subject(s)
Cerebral Palsy/complications , Health Knowledge, Attitudes, Practice , Health Personnel/psychology , Sialorrhea/complications , Sialorrhea/therapy , Botulinum Toxins, Type A/therapeutic use , Cerebral Palsy/drug therapy , Cerebral Palsy/therapy , Child , Cholinergic Antagonists/therapeutic use , Female , France , Humans , Male , Sialorrhea/drug therapy , Sialorrhea/rehabilitation , Surveys and Questionnaires
2.
Vet Comp Orthop Traumatol ; 27(1): 1-7, 2014.
Article in English | MEDLINE | ID: mdl-24226972

ABSTRACT

Meniscal tears and subchondral bone marrow lesions have both been described in dogs with cranial cruciate ligament rupture, but their possible concurrence has not been evaluated. In a population of 14 dogs exhibiting signs of stifle pain with surgically confirmed cranial cruciate ligament rupture, a short presurgical 1.5T magnetic resonance (MR) imaging protocol including dorsal proton density, dorsal T1-weighted gradient recalled echo, and sagittal fat-saturated dual echo sequences was tested to further investigate these features and illustrate meniscal tears. Interobserver agreement for detection of medial meniscal tears (k=0.83) and bone marrow lesions (k=0.87) was excellent. Consensus MR reading allowed detection of nine out of 12 surgically confirmed medial meniscal tears and there was no false positive. All dogs had cruciate ligament enthesis-related bone marrow lesions in the tibia, femur or both bones. Additionally, among the 12 dogs with confirmed medial meniscal tears, subchondral bone marrow lesions were present in the caudomedial (9 dogs) and caudoaxial (11 dogs) regions of the tibial plateau, resulting in odds ratios (13.6, p=0.12, and 38.3, p=0.04, respectively) that had large confidence intervals due to the small group size of this study. The other two dogs had neither tibial bone marrow lesions in these locations nor medial meniscal tears. These encouraging preliminary results warrant further investigation using this clinically realistic preoperative MR protocol. As direct diagnosis of meniscal tears remained challenging in dogs even with high-field MR, identification of associated signs such as subchondral bone marrow lesions might indirectly allow suspicion of an otherwise unrecognized meniscal tear.


Subject(s)
Anterior Cruciate Ligament/surgery , Dogs/injuries , Magnetic Resonance Imaging/veterinary , Stifle/surgery , Tibial Meniscus Injuries , Animals , Dogs/surgery , Magnetic Resonance Imaging/methods , Menisci, Tibial/diagnostic imaging , Radiography , Time Factors
3.
Ann Phys Rehabil Med ; 54(8): 506-18, 2011 Nov.
Article in English, French | MEDLINE | ID: mdl-22104482

ABSTRACT

This document is part of a series of documents designed by the French Physical and Rehabilitation Medicine Society (SOFMER) and the French Federation of PRM (FEDMER). These documents describe the needs for a specific type of patients; PRM care objectives, human and material resources to be implemented, chronology as well as expected outcomes. "Care pathways in PRM" is a short document designed to enable the reader (physicians, decision-maker, administrator, lawyer or finance manager) to quickly apprehend the needs of these patients and the available therapeutic care structures for proper organization and pricing of these activities. Stroke patients are divided into four categories according to the severity of the impairments, each one being treated according to the same six parameters according to the International Classification of Functioning, Disability and Health (WHO), while taking into account personal and environmental factors that could influence the needs of these patients.


Subject(s)
Aftercare , Critical Pathways/organization & administration , Stroke Rehabilitation , Cognition Disorders/rehabilitation , Critical Pathways/economics , Humans , Mobility Limitation , Needs Assessment , Occupational Therapy , Paralysis/rehabilitation , Physical Therapy Modalities , Postoperative Care , Severity of Illness Index , Speech Therapy , Stroke/psychology , Stroke/therapy
4.
Ann Phys Rehabil Med ; 54(6): 337-47, 2011 Sep.
Article in English, French | MEDLINE | ID: mdl-21868301

ABSTRACT

INTRODUCTION: The flexible derotator is one of the therapeutic resources used to combat primary and secondary abnormalities in walking cerebral palsy children. It was developed to reduce abnormal femoral and tibial torsions and lessen the latter's negative functional impact. OBJECTIVE: To determine the effect of wearing a flexible derotator on anatomic and functional parameters in walking cerebral palsy children. METHODS: We performed a retrospective study of walking cerebral palsy children by gathering data on bone-related parameters (femoral and tibial torsion) and functional parameters (distance and speed gait, and the energy expenditure index (EEI)). Fifteen walking cerebral palsy children were treated with the flexible derotator for one year and 15 untreated walking cerebral palsy children were included as controls. The two groups were compared in terms of the various parameters' change over time between the initial examination (the last examination prior to the start of the study or prior to use of the flexible derotator) and the final examination (after one year of follow-up). RESULTS: Right femoral anteversion and right and left external tibial torsion improved. There was a significant increase in distance and speed gait and a decrease in the EEI in walking cerebral palsy children. CONCLUSION: Our retrospective study revealed a significant improvement in functional parameters in children with cerebral palsy, as a result of wearing the flexible derotator for at least 6 hours a day for a year. Bone parameters only improved slightly. Use of the flexible derotator could improve these children's quality of life.


Subject(s)
Cerebral Palsy/rehabilitation , Femur/physiopathology , Gait Disorders, Neurologic/rehabilitation , Orthotic Devices , Tibia/physiopathology , Anthropometry , Biomechanical Phenomena , Child , Equipment Design , Gait Disorders, Neurologic/physiopathology , Humans , Quality of Life , Retrospective Studies , Torsion, Mechanical , Walking
6.
Osteoarthritis Cartilage ; 17(2): 188-96, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18760939

ABSTRACT

OBJECTIVE: To evaluate in vivo the evolution of osteoarthritis (OA) lesions temporally in a rabbit model of OA with clinically available imaging modalities: computed radiography (CR), helical single-slice computed tomography (CT), and 1.5 tesla (T) magnetic resonance imaging (MRI). METHODS: Imaging was performed on knees of anesthetized rabbits [10 anterior cruciate ligament transection (ACLT) and contralateral sham joints and six control rabbits] at baseline and at intervals up to 12 weeks post-surgery. Osteophytosis, subchondral bone sclerosis, bone marrow lesions (BMLs), femoropatellar effusion and articular cartilage were assessed. RESULTS: CT had the highest sensitivity (90%) and specificity (91%) to detect osteophytes. A significant increase in total joint osteophyte score occurred at all time-points post-operatively in the ACLT group alone. BMLs were identified and occurred most commonly in the lateral femoral condyle of the ACLT joints and were not identified in the tibia. A significant increase in joint effusion was present in the ACLT joints until 8 weeks after surgery. Bone sclerosis or cartilage defects were not reliably assessed with the selected imaging modalities. CONCLUSION: Combined, clinically available CT and 1.5 T MRI allowed the assessment of most of the characteristic lesions of OA and at early time-points in the development of the disease. However, the selected 1.5 T MRI sequences and acquisition times did not permit the detection of cartilage lesions in this rabbit OA model.


Subject(s)
Arthritis, Experimental/diagnosis , Animals , Arthritis, Experimental/diagnostic imaging , Arthritis, Experimental/pathology , Cartilage, Articular/diagnostic imaging , Cartilage, Articular/pathology , Disease Progression , Exudates and Transudates/diagnostic imaging , Exudates and Transudates/metabolism , Magnetic Resonance Imaging/methods , Male , Osteophyte/diagnosis , Osteophyte/diagnostic imaging , Osteosclerosis/diagnosis , Osteosclerosis/diagnostic imaging , Rabbits , Sensitivity and Specificity , Tomography, X-Ray Computed/methods
7.
Osteoarthritis Cartilage ; 17(2): 197-204, 2009 Feb.
Article in English | MEDLINE | ID: mdl-18757215

ABSTRACT

OBJECTIVE: To assess bone mineral density (BMD) at different depths from the articular surface in vivo and temporally in a rabbit model of osteoarthritis (OA) using clinical computed tomography (CT) equipment. METHODS: The knee joints of rabbits (N=10 with Anterior cruciate ligament transection (ACLT) and contralateral sham joints, and N=6 unoperated controls) were scanned in a transverse image plane with a single-slice helical CT scanner. BMD was calculated at defined depths from the articular surface to the growth plate in the lateral femoral condyle (LFC), medial femoral condyle (MFC), lateral tibial plateau (LTP) and medial tibial plateau (MTP). Baseline BMD was measured at 2 weeks before surgery, and then repeated at weeks 2, 4 and 8 post-surgery in all 10 operated rabbits, and again at week 12 in five of the operated rabbits and at weeks -2 and 8 in the six control rabbits. RESULTS: In the control joints, BMD decreased with increasing distance into the epiphysis and remained stable over time within each depth. A significant reduction in BMD was observed at week 2 post-operatively in three compartments (LFC, MFC and MTP) in the ACLT joints and persisted to week 12. A modest reduction in BMD occurred in the LTP and MTP of the sham joints at week 12 alone. CONCLUSION: Clinical CT equipment permitted rapid, repeated, in vivo, non-invasive BMD assessment in a rabbit model of OA. A marked BMD reduction was measured with progression of OA until the end point at 12 weeks.


Subject(s)
Arthritis, Experimental/physiopathology , Bone Density , Animals , Anterior Cruciate Ligament Injuries , Arthritis, Experimental/diagnostic imaging , Arthritis, Experimental/etiology , Disease Progression , Femur/diagnostic imaging , Femur/physiopathology , Male , Rabbits , Tibia/diagnostic imaging , Tibia/physiopathology , Tomography, X-Ray Computed/methods
8.
Equine Vet J ; 41(9): 859-64, 2009 Dec.
Article in English | MEDLINE | ID: mdl-20383982

ABSTRACT

REASONS FOR PERFORMING STUDY: Marginal osteophytes represent a well known component of osteoarthritis in man and animals. Conversely, central subchondral osteophytes (COs), which are commonly present in human knees with osteoarthritis, have not been reported in horses. OBJECTIVES: To describe and compare computed radiography (CR), single-slice computed tomography (CT), 1.5 Tesla magnetic resonance imaging (MRI), and histological features of COs in equine metacarpophalangeal joints with macroscopic evidence of naturally-occurring osteoarthritis. METHODS: MRI sequences (sagittal spoiled gradient recalled echo [SPGR] with fat saturation, sagittal T2-weighted fast spin echo with fat saturation [T2-FS], dorsal and transverse T1-weighted gradient-recalled echo [GRE], and sagittal T2*-weighted gradient echo with fast imaging employing steady state acquisition [FIESTA]), as well as transverse and reformatted sagittal CTI and 4 computed radiographic (CR) views of 20 paired metacarpophalangeal joints were acquired ex vivo. Following macroscopic evaluation, samples were harvested in predetermined sites of the metacarpal condyle for subsequent histology. The prevalence and detection level of COs was determined for each imaging modality. RESULTS: Abnormalities consistent with COs were clearly depicted on MRI, using the SPGR sequence, in 7/20 (35%) joints. They were identified as a focal hypointense protuberance from the subchondral plate into the cartilage, at the palmarodistal aspect (n=7) and/or at the very dorsal aspect (n=2) of the metacarpal condyle. COs were visible but less obvious in 5 of the 7 joints using FIESTA and reformatted sagittal CT, and were not identifiable on T2-FS, T1-GRE or CR. Microscopically, they consisted of dense bone protruding into the calcified cartilage and disrupting the tidemarks, and they were consistently associated with overlying cartilage defects. CONCLUSIONS: Subchondral osteophytes are a feature of osteoarthritis of equine metacarpophalangeal joints and they may be diagnosed using 1.5 Tesla MRI and CT. POTENTIAL RELEVANCE: Central subchondral osteophytes on MRI represent indirect evidence of cartilage damage in horses.


Subject(s)
Forelimb/pathology , Horse Diseases/pathology , Magnetic Resonance Imaging/veterinary , Osteoarthritis/veterinary , Osteophyte/veterinary , Animals , Cadaver , Horses , Osteoarthritis/pathology , Osteophyte/pathology
9.
Neuropediatrics ; 39(3): 184-7, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18991200

ABSTRACT

Mutations in the gene for the ganglioside-induced-differentiation-associated-protein 1 on 8q21 were recently reported to cause autosomal recessive Charcot-Marie-Tooth sensorimotor neuropathy. We report a detailed clinical, electrophysiological and genetic study of two young patients harbouring missense GDAP1 mutations. The two patients presented severe neuropathy with an early onset. One of the mutations (Tyr279Cys) has never been hitherto reported. Electrophysiological investigations suggested a predominant axonal damage in both patients. Despite the similitude of the type of mutations and electromyographic features, the clinical course was different for the patients, highlighting the complexity of genotype/phenotype relationships among GDAP1 mutations.


Subject(s)
Charcot-Marie-Tooth Disease/genetics , Charcot-Marie-Tooth Disease/physiopathology , Mutation, Missense , Nerve Tissue Proteins/genetics , Charcot-Marie-Tooth Disease/diagnosis , Child , Child, Preschool , Electrophysiology/methods , Female , Genotype , Humans , Male , Pedigree , Phenotype
10.
Osteoarthritis Cartilage ; 16(11): 1307-11, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18462957

ABSTRACT

OBJECTIVE: To assess the evolution of bone marrow lesions (BMLs) in a canine model of knee osteoarthritis (OA) using three different magnetic resonance imaging (MRI) sequences. DESIGN: Three MRI sequences [coronal, T1-weighted three-dimensional fast gradient recalled echo (T1-GRE), sagittal fat-suppressed 3D spoiled gradient echo at a steady state (SPGR), and sagittal T2-weighted fast spin echo with fat saturation (T2-FS)] were performed at baseline, and at week 4, 8 and 26 in five dogs following transection of the anterior cruciate ligament. The same reader scored (0-3) subchondral BMLs twice, in blinded conditions, according to their extent in nine joint subregions, for all imaging sessions, and independently on the three MRI sequences. Correlation coefficients and Bland-Altman plots evaluated intra-reader repeatability. Readings scores were averaged and the nine subregions were summed to generate global BML scores. RESULTS: BMLs were most prevalent in the central and medial portions of the tibial plateau. Intra-reader repeatability was good to excellent for each sequence (r(s)=0.87-0.97; P<0.001). Maximal intra-reader variability (24%) was reached on T2-FS and was associated to higher scores (P<0.05). Global BML scores increased similarly on all three sequences until week 8 (P<0.05). At week 26, score on T2-FS was decreased, being lower when compared to T1-GRE and SPGR (P<0.05). CONCLUSION: In this canine OA model, the extent of BMLs varies in time on different MRI sequences. Until the complex nature of these lesions is fully resolved, it is suggested that to accurately assess the size and extent of BMLs, a combination of different sequences should be used.


Subject(s)
Bone Marrow Diseases/pathology , Bone Marrow/pathology , Knee Joint/pathology , Magnetic Resonance Imaging/methods , Osteoarthritis, Knee/pathology , Animals , Dogs , Models, Animal
11.
Ann Rheum Dis ; 67(7): 926-32, 2008 Jul.
Article in English | MEDLINE | ID: mdl-17962236

ABSTRACT

OBJECTIVES: Osteoarthritis (OA) structural changes take place over decades in humans. MRI can provide precise and reliable information on the joint structure and changes over time. In this study, we investigated the reliability of quantitative MRI in assessing knee OA structural changes in the experimental anterior cruciate ligament (ACL) dog model of OA. METHODS: OA was surgically induced by transection of the ACL of the right knee in five dogs. High resolution three dimensional MRI using a 1.5 T magnet was performed at baseline, 4, 8 and 26 weeks post surgery. Cartilage volume/thickness, cartilage defects, trochlear osteophyte formation and subchondral bone lesion (hypersignal) were assessed on MRI images. Animals were killed 26 weeks post surgery and macroscopic evaluation was performed. RESULTS: There was a progressive and significant increase over time in the loss of knee cartilage volume, the cartilage defect and subchondral bone hypersignal. The trochlear osteophyte size also progressed over time. The greatest cartilage loss at 26 weeks was found on the tibial plateaus and in the medial compartment. There was a highly significant correlation between total knee cartilage volume loss or defect and subchondral bone hypersignal, and also a good correlation between the macroscopic and the MRI findings. CONCLUSION: This study demonstrated that MRI is a useful technology to provide a non-invasive and reliable assessment of the joint structural changes during the development of OA in the ACL dog model. The combination of this OA model with MRI evaluation provides a promising tool for the evaluation of new disease-modifying osteoarthritis drugs (DMOADs).


Subject(s)
Arthritis, Experimental/pathology , Osteoarthritis, Knee/pathology , Animals , Cartilage, Articular/pathology , Disease Models, Animal , Disease Progression , Dogs , Magnetic Resonance Imaging/methods , Osteophyte/pathology , Severity of Illness Index
12.
Ann Readapt Med Phys ; 50(6): 510-9, 499-509, 2007 Jul.
Article in English, French | MEDLINE | ID: mdl-17532521

ABSTRACT

INTRODUCTION: Training programs are increasingly being prescribed for occupational therapy for adults affected by chronic illness and/or handicap, but their use is more recent for children and teenagers. OBJECTIVE: A review of the literature to synthesize information concerning training programs for children, whether healthy or with disease or handicap, considering the target population, methodology, the results and limitations. METHODS: We searched the Medline database with use of the key words retraining, training, training programs, physical activity, physical training, fitness program, sport, children, disability, and handicap. We also searched references of the selected articles for appropriate studies. DISCUSSION/CONCLUSION: Physical activity seems to be a good means of primary preventing adverse health in the healthy child and secondary prevention in children with chronic disease or handicap. Thus, training programs could be adapted and integrated into the global treatment of sick or handicapped children in the health care situation or in the home. These programs are feasible and do not undermine children's health, but few studies have shown clear data on the methods of the programs. The suggested training programs, not always validated, included two to five sessions from 30 to 60 min/week, for 6-16 weeks, of variable activity and intensity, adapted to the condition and the objectives of therapy. Training programs adapted to children should be validated to allow their accessibility by health care professionals dealing with children with chronic disease and/or handicap.


Subject(s)
Exercise Therapy , Exercise , Child , Chronic Disease , Disabled Children , Humans , Motor Activity
13.
Equine Vet J ; 39(2): 158-63, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17378445

ABSTRACT

REASONS FOR PERFORMING STUDY: Previous studies have shown that in man ultrasonography is more accurate than radiography for detecting rib fractures. OBJECTIVES: To describe clinical, radiographic and ultrasonographic findings related with rib fractures in newborn foals in an equine critical care unit; and to compare diagnostic accuracy of ultrasonography to radiography. METHODS: A prospective ultrasonographic study was performed on 29 foals presented to the emergency unit. This study was performed at the Centre Hospitalier Universitaire Vétérinaire (CHUV), University of Montreal. Physical examination as well as radiographic and ultrasonographic examinations were performed. RESULTS: Thoracic radiographs revealed 10 rib fractures in 5 of 26 (19%) foals. Ultrasonography revealed 49 fractures in 19 of 29 (65%) foals of which fillies (n = 13; 68%) were significantly over represented as were fractures to the left thorax (n = 15; 78%). Seventeen of 19 foals (90%) had rib fractures located 3 cm or less from the costochondral junction, the distal part of the rib being displaced laterally in all cases. In 2 foals, where both thoracic radiographs and ultrasonography detected rib fractures, the site of fractures was located on the mid portion of the rib. Rib fractures were detected only by thoracic radiographs in one foal. Sixty-five percent (32/49) of fractured ribs had a moderate displacement (1-4 mm). CONCLUSIONS: Rib fractures are seen frequently in newborn foals in equine critical care units. Ultrasonography is more accurate than radiography and reveals fractures in most patients presented in emergency. The position (costochondral junction) of rib fractures and of the fragments suggest that most thoracic trauma probably occurs during parturition. POTENTIAL RELEVANCE: Ultrasound imaging increases awareness and improves the diagnosis of rib fractures in newborn foals.


Subject(s)
Birth Injuries/veterinary , Horses/injuries , Physical Examination/veterinary , Radiography, Thoracic/veterinary , Rib Fractures/veterinary , Ultrasonography/veterinary , Animals , Animals, Newborn/injuries , Birth Injuries/diagnosis , Birth Injuries/diagnostic imaging , Critical Care , Female , Male , Physical Examination/methods , Pregnancy , Prospective Studies , Radiography, Thoracic/methods , Rib Fractures/diagnosis , Rib Fractures/diagnostic imaging , Risk Factors , Sensitivity and Specificity , Sex Factors , Thoracic Injuries/diagnosis , Thoracic Injuries/diagnostic imaging , Thoracic Injuries/veterinary , Ultrasonography/methods
14.
Ann Readapt Med Phys ; 45(4): 154-8, 2002 Apr.
Article in French | MEDLINE | ID: mdl-11960659

ABSTRACT

UNLABELLED: To evaluate the impact of handicap on quality of life in children with cerebral palsy and living in family. METHOD: A descriptive study by investigation was conducted in children with cerebral palsy, with the ability to walk, from 4 to 12 years of age, and in their family. Quality of life was evaluated with the AUQUEI questionnaire. Another questionnaire was given to the parents to collect the different variables, which could influence quality of life of the child. RESULTS: The mean age was 9 years. Associations between the studied variables and the quality of life were observed for motor function, number of siblings and the quantity of hours of reeducation given by the family. Parents evaluated their quality of life on the visual scale at 72.23 mm (95CI: 51.60-92.84). There was no correlation between the assessment of quality of life of parents and children. DISCUSSION-CONCLUSION: The better the child's motor function the less satisfied he was. This result shows the poor correlation between quality of life and general condition, impairment or disability. The greater the number of children in the family the less satisfied the child was within the family and the more satisfied the child was at school. A handicapped child has perhaps a more difficult place in the close family and an easier time in a school where the environment is more neutral. The more time that is devoted by the family to reeducation the less the child is satisfied. Quality of life seems to be influenced negatively by the demands of physical therapy, which do not correspond to the reality of the abilities of the child.


Subject(s)
Cerebral Palsy/pathology , Disabled Children/psychology , Quality of Life , Walking , Adolescent , Cerebral Palsy/complications , Cerebral Palsy/psychology , Child , Child, Preschool , Cross-Sectional Studies , Family Health , Female , Humans , Male , Parent-Child Relations , Physical Therapy Modalities
15.
Protein Expr Purif ; 21(3): 438-45, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11281719

ABSTRACT

Antifreeze proteins and antifreeze glycoproteins are structurally diverse molecules that share a common property in binding to ice crystals and inhibiting ice crystal growth. Type II fish antifreeze protein of Atlantic herring (Clupea harengus harengus) is unique in its requirement of Ca(2+) for antifreeze activity. In this study, we utilized the secretion vector pGAPZalpha A to express recombinant herring antifreeze protein (WT) and a fusion protein with a C-terminal six-histidine tag (WT-6H) in yeast Pichia pastoris wild-type strain X-33 or protease-deficient strain SMD1168H. Both recombinant proteins were secreted into the culture medium and properly folded and functioned as the native herring antifreeze protein. Furthermore, our studies demonstrated that expression at a lower temperature increased the yield of the recombinant protein dramatically, which might be due to the enhanced protein folding pathway, as well as increased cell viability at lower temperature. These data suggested that P. pastoris is a useful system for the production of soluble and biologically active herring antifreeze protein required for structural and functional studies.


Subject(s)
Antifreeze Proteins, Type II/biosynthesis , Antifreeze Proteins, Type II/metabolism , Cold Temperature , Fishes , Pichia/genetics , Recombinant Fusion Proteins/biosynthesis , Animals , Antifreeze Proteins, Type II/genetics , Antifreeze Proteins, Type II/isolation & purification , Blotting, Western , Calcium/metabolism , Cell Count , Cell Division , Cell Survival , Chromatography, High Pressure Liquid , Genetic Vectors/genetics , Histidine/genetics , Histidine/metabolism , Pichia/cytology , Pichia/metabolism , Protein Conformation , Protein Folding , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/metabolism , Solubility , Time Factors
16.
Biotechnol Bioeng ; 72(1): 1-11, 2001 Jan 05.
Article in English | MEDLINE | ID: mdl-11084587

ABSTRACT

A Mut(S) Pichia pastoris strain that had been genetically modified to produce and secrete sea raven antifreeze protein was used as a model system to demonstrate the implementation of a rational, model-based approach to improve process productivity. A set of glycerol/methanol mixed-feed continuous stirred-tank reactor (CSTR) experiments was performed at the 5-L scale to characterize the relationship between the specific growth rate and the cell yield on methanol, the specific methanol consumption rate, the specific recombinant protein formation rate, and the productivity based on secreted protein levels. The range of dilution rates studied was 0. 01 to 0.10 h(-1), and the residual methanol concentration was kept constant at approximately 2 g/L (below the inhibitory level). With the assumption that the cell yield on glycerol was constant, the cell yield on methanol increased from approximately 0.5 to 1.5 over the range studied. A maximum specific methanol consumption rate of 20 mg/g. h was achieved at a dilution rate of 0.06 h(-1). The specific product formation rate and the volumetric productivity based on product continued to increase over the range of dilution rates studied, and the maximum values were 0.06 mg/g. h and 1.7 mg/L. h, respectively. Therefore, no evidence of repression by glycerol was observed over this range, and operating at the highest dilution rate studied maximized productivity. Fed-batch mass balance equations, based on Monod-type kinetics and parameters derived from data collected during the CSTR work, were then used to predict cell growth and recombinant protein production and to develop an exponential feeding strategy using two carbon sources. Two exponential fed-batch fermentations were conducted according to the predicted feeding strategy at specific growth rates of 0.03 h(-1) and 0.07 h(-1) to verify the accuracy of the model. Cell growth was accurately predicted in both fed-batch runs; however, the model underestimated recombinant product concentration. The overall volumetric productivity of both runs was approximately 2.2 mg/L. h, representing a tenfold increase in the productivity compared with a heuristic feeding strategy.


Subject(s)
Pichia/growth & development , Pichia/genetics , Biotechnology/methods , Escherichia coli/genetics , Fermentation , Genetic Engineering/methods , Genetic Vectors , Glycerol , Methanol , Recombination, Genetic , Transformation, Genetic
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