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1.
Annu Int Conf IEEE Eng Med Biol Soc ; 2019: 5465-5468, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31947092

ABSTRACT

Type 1 Diabetes is an autoimmune disease that eliminates endogenous insulin production. Without the crucial hormone insulin, which is necessary to equilibrate the blood glucose level, the patient must inject insulin subcutaneously. Treatment must be personalized (timing and size of insulin delivery) to achieve glycaemic equilibrium and avoid long-term comorbidities. Patients are educated on Functional Insulin Therapy (FIT) in order to independently adjust insulin delivery several times a day (at least prior to each meal and physical activity). Among personalized parameters, the Correction Factor is used to occasionally correct hyperglycemia via the injection of an insulin dose (bolus) and its value determines the bolus size. Although well-known in common diabetes practice for chronically poorly controlled patients, the phenomenon of "hyperglycemia induces insulin resistance" on a short term basis in patients with rather well controlled diabetes is presented here. Using a new database of evidence, we show that the insulin sensitivity factor, depends on the current level of glycaemia. This opens the door to refining dosing rules for patients and insulin delivery devices in artificial pancreas systems.


Subject(s)
Diabetes Mellitus, Type 1 , Insulin Resistance , Pancreas, Artificial , Blood Glucose , Humans , Hypoglycemic Agents , Insulin , Insulin Infusion Systems , Models, Theoretical
2.
Ann Rheum Dis ; 74(9): 1659-66, 2015 Sep.
Article in English | MEDLINE | ID: mdl-24728331

ABSTRACT

OBJECTIVES: To monitor progression to inflammatory arthritis (IA) in individuals with non-specific musculoskeletal (MSK) symptoms and positive anticyclic citrullinated peptide (anti-CCP) antibodies. To develop a pragmatic model to predict development of IA in this patient group. METHODS: In this prospective observational cohort, patients with new non-specific MSK symptoms and positive anti-CCP were recruited from regional primary care and secondary care referrals. Clinical, imaging and serological parameters were assessed at baseline. Cox regression analysis was performed to identify predictors of progression to IA and develop a risk score to stratify patients at presentation. FINDINGS: 100 consecutive patients (73 women, mean age 51 years) were followed up for median 19.8 months (range 0.1-69.0); 50 developed IA after a median 7.9 months (range 0.1-52.4), 34 within 12 months. The majority (43/50) fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism criteria for rheumatoid arthritis. A model for progression to IA was devised using four variables: tenderness of hand or foot joints, early morning stiffness ≥30 min, high-positive autoantibodies, and positive ultrasonographic power Doppler signal. None of the five individuals at low risk (score 0) progressed to IA, compared with 31% of 29 at moderate risk (1-2) and 62% of 66 at high risk (≥3). Adding shared epitope increased the number at low risk (score 0-1; 0/11 progressed). CONCLUSIONS: In patients presenting with non-specific MSK symptoms and anti-CCP, the risk of progression to IA could be quantified using data available in clinical practice. The proposed risk score may be used to stratify patients for early therapeutic intervention. TRIAL REGISTRATION NUMBER: NCT02012764 at ClinicalTrials.gov.


Subject(s)
Arthritis, Rheumatoid/immunology , Autoantibodies/immunology , Peptides, Cyclic/immunology , Adult , Aged , Cohort Studies , Decision Support Techniques , Disease Progression , Female , Humans , Male , Middle Aged , Proportional Hazards Models , Prospective Studies , Young Adult
3.
Clin Toxicol (Phila) ; 52(5): 556-60, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24697801

ABSTRACT

INTRODUCTION: The United Kingdom has recently changed the indications for N-acetylcysteine treatment for acetaminophen intoxication. Any ingestion over 75 mg/kg is now referred to the hospital. A model based on pharmacokinetic parameters was developed to predict 4-h acetaminophen concentration for this and other ingested doses. METHODOLOGY: EMBASE and Medline were searched to obtain values for volume of distribution, absorption, and elimination constants and bioavailability for acetaminophen. Four-hour concentrations were calculated for ingestion doses currently recommended for hospital referral in different countries. Calculated plasma concentrations at 4 h for several doses were plotted against the Rumack-Matthew and the United Kingdom treatment lines. RESULTS: Six articles were used for the calculations (4 adult and 2 pediatric). In order to achieve a 4-h acetaminophen concentration of 100 mg/L, doses (mg/kg ± 99.9CI) of 180.5 ± 43.2 for adults and 396.1 ± 115.5 for children were calculated. DISCUSSION: A dose of 75 mg/kg would likely yield a 4-h acetaminophen concentrations well below 100 mg/L. Medical toxicologists and poison information specialists are left without evidence-based guidance for which patients or which ingestion history would now warrant referral to hospital for acetaminophen concentration measurement. Larger toxicokinetic studies in acetaminophen overdose are needed to define ingestion dose for referral to hospital.


Subject(s)
Acetaminophen/poisoning , Models, Biological , Referral and Consultation , Acetaminophen/administration & dosage , Acetaminophen/pharmacokinetics , Acetylcysteine/administration & dosage , Acetylcysteine/therapeutic use , Adult , Age Factors , Antidotes/administration & dosage , Antidotes/therapeutic use , Child , Drug Overdose , Humans , Time Factors , Tissue Distribution , United Kingdom
4.
Ann Rheum Dis ; 73(6): 1027-36, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24618266

ABSTRACT

OBJECTIVE: To compare the efficacy of etanercept (ETN) and methotrexate (MTX) versus MTX monotherapy for remission induction in patients with early inflammatory arthritis. METHODS: In a 78-week multicentre randomised placebo-controlled superiority trial, 110 DMARD-naïve patients with early clinical synovitis (≥1 tender and swollen joint, and within 3 months of diagnosis) and either rheumatoid factor, anticitrullinated protein antibodies or shared epitope positive were randomised 1:1 to receive MTX+ETN or MTX+placebo (PBO) for 52 weeks. Injections (ETN or PBO) were stopped in all patients at week 52. In those with no tender or swollen joints (NTSJ) for >26 weeks, injections were stopped early. If patients had NTSJ >12 weeks after stopping the injections, MTX was weaned. The primary endpoint was NTSJ at week 52. RESULTS: No statistically significant difference was seen for the primary endpoint (NTSJ at week 52 (32.5% vs 28.1% [adjusted OR 1.32 (0.56 to 3.09), p=0.522]) in the MTX+ETN and MTX+PBO groups, respectively). The secondary endpoints did not differ between groups at week 52 or 78. Exploratory analyses showed a higher proportions of patients with DAS28-CRP<2.6 in the MTX+ETN group at week 2 (38.5% vs 9.2%, adjusted OR 8.87 (2.53 to 31.17), p=0.001) and week 12 (65.1% vs 43.8%, adjusted OR 2.49 (1.12 to 5.54), p=0.026). CONCLUSIONS: In this group of patients with early inflammatory arthritis, almost a third had no tender, swollen joints after 1 year. MTX+ETN was not superior to MTX monotherapy in achieving this outcome. Clinical responses, however, including DAS28-CRP<2.6, were achieved earlier with MTX+ETN combination therapy. TRIAL REGISTRATION NUMBER: The EMPIRE trial is registered on the following trial registries: Eudract-2005-005467-29; ISRCTN 55428162 (http://www.controlled-trials.com/ISRCTN55428162/EMPIRE). The full trial protocol can be obtained from the corresponding author.


Subject(s)
Antirheumatic Agents/therapeutic use , Arthritis/drug therapy , Immunoglobulin G/therapeutic use , Methotrexate/therapeutic use , Receptors, Tumor Necrosis Factor/therapeutic use , Synovitis/drug therapy , Adolescent , Adult , Aged , Aged, 80 and over , Arthritis/immunology , Arthritis, Rheumatoid/drug therapy , Arthritis, Rheumatoid/immunology , Autoantibodies/immunology , Double-Blind Method , Drug Therapy, Combination/methods , Early Medical Intervention/methods , Etanercept , Female , Humans , Induction Chemotherapy/methods , Male , Middle Aged , Remission Induction/methods , Rheumatoid Factor/immunology , Treatment Outcome , Young Adult
5.
Ann Rheum Dis ; 73(1): 75-85, 2014 Jan.
Article in English | MEDLINE | ID: mdl-23912798

ABSTRACT

OBJECTIVES: In disease modifying antirheumatic drug (DMARD)-naive early rheumatoid arthritis (RA), to compare the efficacy of methotrexate (MTX) and infliximab (IFX) with MTX and intravenous corticosteroid for remission induction. METHODS: In a 78-week multicentre randomised controlled trial, double-blinded to week 26, 112 treatment-naive RA patients (1987 American College of Rheumatology classification criteria) with disease activity score 44 (DAS44)>2.4 were randomised to MTX + IFX or MTX + single dose intravenous methylprednisolone 250 mg. A treat-to-target approach was used with treatment escalation if DAS44>2.4. In the IFX group, IFX was discontinued for sustained remission (DAS44<1.6 for 6 months). The primary outcome was change in modified total Sharp-van der Heijde score (mTSS) at week 50. RESULTS: The mean changes in mTSS score at week 50 in the IFX and intravenous steroid groups were 1.20 units and 2.81 units, respectively (adjusted difference (95% CI) -1.45 (-3.35 to 0.45); p=0.132). Radiographic non-progression (mTSS<2.0) occurred in 81% vs 71% (OR 1.77 (0.56 to 5.61); p=0.328). DAS44 remission was achieved at week 50 in 49% and 36% (OR 2.13 (0.91 to 5.00); p=0.082), and at week 78 in 48% and 50% (OR 1.12 (0.47 to 2.68); p=0.792). Exploratory analyses suggested higher DAS28 remission at week 6 and less ultrasound synovitis at week 50 in the IFX group. Of the IFX group, 25% (14/55) achieved sustained remission and stopped IFX. No substantive differences in adverse events were seen. CONCLUSIONS: In DMARD-naive early RA patients, initial therapy with MTX+high-dose intravenous steroid resulted in good disease control with little structural damage. MTX+IFX was not statistically superior to MTX+intravenous steroid when combined with a treat-to-target approach.


Subject(s)
Antibodies, Monoclonal/administration & dosage , Antirheumatic Agents/administration & dosage , Arthritis, Rheumatoid/drug therapy , Steroids/administration & dosage , Adolescent , Adult , Aged , Aged, 80 and over , Antibodies, Monoclonal/adverse effects , Antirheumatic Agents/adverse effects , Arthritis, Rheumatoid/diagnosis , Dose-Response Relationship, Drug , Double-Blind Method , Female , Humans , Infliximab , Injections, Intravenous , Male , Middle Aged , Remission Induction , Treatment Outcome , Young Adult
6.
Ann Rheum Dis ; 70(1): 15-24, 2011 Jan.
Article in English | MEDLINE | ID: mdl-20724311

ABSTRACT

OBJECTIVE: To develop evidence-based recommendations on how to investigate and follow-up undifferentiated peripheral inflammatory arthritis (UPIA). METHODS: 697 rheumatologists from 17 countries participated in the 3E (Evidence, Expertise, Exchange) Initiative of 2008-9 consisting of three separate rounds of discussions and modified Delphi votes. In the first round 10 clinical questions were selected. A bibliographic team systematically searched Medline, Embase, the Cochrane Library and ACR/EULAR 2007-2008 meeting abstracts. Relevant articles were reviewed for quality assessment, data extraction and synthesis. In the second round each country elaborated a set of national recommendations. Finally, multinational recommendations were formulated and agreement among the participants and the potential impact on their clinical practice was assessed. RESULTS: A total of 39,756 references were identified, of which 250 were systematically reviewed. Ten multinational key recommendations about the investigation and follow-up of UPIA were formulated. One recommendation addressed differential diagnosis and investigations prior to establishing the operational diagnosis of UPIA, seven recommendations related to the diagnostic and prognostic value of clinical and laboratory assessments in established UPIA (history and physical examination, acute phase reactants, autoantibodies, radiographs, MRI and ultrasound, genetic markers and synovial biopsy), one recommendation highlighted predictors of persistence (chronicity) and the final recommendation addressed monitoring of clinical disease activity in UPIA. CONCLUSIONS: Ten recommendations on how to investigate and follow-up UPIA in the clinical setting were developed. They are evidence-based and supported by a large panel of rheumatologists, thus enhancing their validity and practical use.


Subject(s)
Arthritis/diagnosis , Arthritis, Rheumatoid/diagnosis , Biomarkers/blood , Diagnosis, Differential , Evidence-Based Medicine/methods , Humans , International Cooperation , Long-Term Care/methods , Prognosis , Severity of Illness Index
7.
Paediatr Anaesth ; 11(5): 607-10, 2001.
Article in English | MEDLINE | ID: mdl-11696127

ABSTRACT

Advances in the treatment of congenital heart disease have led to a new group of adolescents or adults patients with cardiac anomalies. The anaesthetic management of these patients can be challenging especially when they are scheduled for major noncardiac surgery inducing haemodynamic instability. We report the case of a 14-year-old boy scheduled for posterior spinal fusion for idiopathic scoliosis who underwent a Fontan operation in infancy for pulmonary atresia with right ventricle hypoplasia. The preoperative investigations and the anaesthetic management are described.


Subject(s)
Anesthesia, Intravenous/methods , Anesthetics, Combined/administration & dosage , Scoliosis/surgery , Adolescent , Androstanols/administration & dosage , Fentanyl/administration & dosage , Fontan Procedure , Heart Defects, Congenital/complications , Heart Defects, Congenital/surgery , Heart Ventricles/abnormalities , Humans , Male , Midazolam/administration & dosage , Pulmonary Atresia/surgery , Rocuronium , Scoliosis/complications , Spinal Fusion , Thiopental/administration & dosage
8.
Can J Gastroenterol ; 14 Suppl B: 59B-62B, 2000.
Article in English | MEDLINE | ID: mdl-10938507

ABSTRACT

Cirrhotic patients who undergo liver transplantation are at risk of acquiring de novo hepatitis B virus (HBV) infection at the time of transplantation. It is common practice to immunize these patients against HBV, but the efficacy of vaccination is uncertain. The response to vaccination with a recombinant HBV vaccine was examined in 49 patients with cirrhosis before liver transplantation. Patients received three doses (20 mg) of Engerix-B (SmithKline Beecham) at zero, one and two months before transplantation, and their response was measured on the day of liver transplantation (9.3+/-1.2 months after the initial dose of vaccine). Results were compared with those reported in healthy adults vaccinated according to the same schedule. Fourteen of 49 cirrhotic patients (28%) developed antibodies to hepatitis B surface antigen (anti-HBs) levels of more than 10 U/L after vaccination compared with 97% of healthy controls. Four patients (8%) had anti-HBs levels of more than 100 U/L compared with 83% in healthy individuals. Mean anti-HBs titre in the 14 responders was 62 U/L compared with 348 U/L in controls. No factor was identified that predicted response to vaccination. One of 49 patients acquired de novo HBV infection at the time of liver transplantation. Current HBV vaccination of cirrhotic patients waiting for liver transplantation is ineffective, and new strategies need to be developed to increase the response rate.


Subject(s)
Hepatitis B Vaccines , Hepatitis B/prevention & control , Liver Cirrhosis/surgery , Liver Transplantation/adverse effects , Female , Hepatitis B/etiology , Humans , Liver Transplantation/methods , Male , Middle Aged , Retrospective Studies , Risk Factors , Treatment Failure
9.
Can J Anaesth ; 46(10): 970-4, 1999 Oct.
Article in English | MEDLINE | ID: mdl-10522585

ABSTRACT

PURPOSE: To describe the anesthetic and ventilatory management of an infant with diffuse pulmonary bullous lesions. CLINICAL FEATURES: Four successive operations were scheduled for an infant with diffuse pulmonary bullous lesions. At the age of seven weeks, conventional positive pressure ventilation during laparotomy for intestinal occlusion led to arterial desaturation. This was corrected by returning to spontaneous respiration and deep inhalation anesthesia with halothane. Based on our ICU experience and due to a potential impaired oxygenation during conventional ventilation, we chose high-frequency oscillatory ventilation (HFOV) for bilateral sequential thoracotomies for bullectomies at the age of five months. We elected the same ventilatory mode for laparotomy for intestinal obstruction secondary to a polyp at the age of six months. This ventilatory mode was combined with total intravenous anesthesia and epidural analgesia and provided optimal oxygenation and ventilation as well as vital signs stability. CONCLUSION: High frequency oscillatory ventilation is a safe technique that may be used in the operating room in cases where conventional ventilation failed to provide satisfactory gas exchange.


Subject(s)
High-Frequency Ventilation , Lung Diseases/therapy , Anesthesia, Epidural , Anesthesia, Intravenous , Blood Gas Analysis , Carbon Dioxide/blood , Female , Hemodynamics , Humans , Infant , Lung/diagnostic imaging , Lung Diseases/diagnostic imaging , Lung Diseases/surgery , Oxygen/blood , Radiography , Thoracotomy
10.
Acta Paediatr ; 88(4): 422-7, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10342542

ABSTRACT

The accurate assessment of pain in children constitutes a challenge for health professionals and, in the case of young children, parents are generally the main source of information. The objective of this study was to validate and to compare three pain scales in preschool children and their parents. A total of 104 children between 4 and 6 y of age and their parents participated in the study while undergoing an immunization procedure in the outpatient department of a tertiary pediatric care hospital. Three pain scales were used, the McGrath Facial Affective Scale (FAS), the Hester Poker Chip Tool (HPCT) and the Multiple Size Poker Chip Tool (MSPCT). There were 47 (45%) boys and 57 (55%) girls, with 54 (52%) 4-y-olds, 34 (33%) 5-y-olds and 16 (15%) 6-y-olds. Twenty-eight children (27%) had memories of pain experienced during a former hospitalization. Correlations were very high both in children (r = 0.78) and their parents (r = 0.96) when comparing immunization pain scores obtained from the HPCT versus the MSPCT. Correlations between McGrath's FAS and HPCT or MSPCT ranged from r = 0.34-0.43 in children and r = 0.38-0.39 in parents. There was a good correlation between parents and children during the immunization procedure on all three scales, with the highest correlation using the FAS (r = 0.76), followed by the MSPCT (r = 0.69), and the HPCT (r = 0.66). Subgroup analyses based on the criteria of age, sex and previous hospitalization showed no consistent relationship. Parents tended to underestimate their child's pain when using HPCT or MSPCT. It seems that both HPCT and MSPCT measure a similar dimension of pain, whereas the FAS addresses a different aspect of pain. Although parents play an important role in their child's pain assessment, they tend to underestimate the intensity of pain when using HPCT or MSPCT.


Subject(s)
Pain Measurement/methods , Pain Measurement/statistics & numerical data , Parents , Age Factors , Child , Child, Preschool , Female , Humans , Immunization/adverse effects , Male , Memory , Sex Factors , Statistics, Nonparametric
11.
Sante Ment Que ; 24(2): 126-42, 1999.
Article in French | MEDLINE | ID: mdl-18253565

ABSTRACT

The authors describe the evolution of certain mental health services of the Centre hospitalier Robert-Giffard : treatment centres, specialized clinics as well as treatment services implemented in the community. The authors identify the principles that have presided over the organization of these treatement.

12.
Int Orthop ; 20(5): 295-9, 1996.
Article in English | MEDLINE | ID: mdl-8930721

ABSTRACT

One hundred adolescents undergoing posterior spinal fusion for scoliosis were reviewed to assess the adequacy of postoperative patient-controlled analgesia. There were 94 females and 6 males. The mean settings for morphine dosage were a loading dose of 114.5 micrograms.kg-1, a bolus dose of 24.8 micrograms.kg-1, and a lockout interval of 9.9 minutes. This was used for an average of 75.8 h, with a 52.2% success rate. Adolescents using patient-controlled analgesia showed a great variability in morphine requirements with greater use as they became older. The requirement was not significantly different on the 1st, 2nd and 3rd postoperative days and the total consumption was 52.2 micrograms.kg-1.h-1. Nausea and vomiting occurred in 45% and pruritus in 15%. There were 7 cases of respiratory depression who all recovered promptly and completely. This method is associated with high morphine requirements in adolescents, but can be used safely.


Subject(s)
Analgesia, Patient-Controlled , Scoliosis/surgery , Spinal Fusion , Adolescent , Adult , Analgesia, Patient-Controlled/adverse effects , Analgesics, Opioid/administration & dosage , Analgesics, Opioid/adverse effects , Child , Female , Humans , Male , Morphine/administration & dosage , Morphine/adverse effects , Morphine/therapeutic use , Nausea/chemically induced , Pain, Postoperative/drug therapy , Retrospective Studies , Time Factors , Vomiting/chemically induced
13.
Can J Physiol Pharmacol ; 69(6): 752-60, 1991 Jun.
Article in English | MEDLINE | ID: mdl-1913322

ABSTRACT

The effect of three volatile anesthetics (halothane, enflurane, and isoflurane) on coronary flow and metabolic state of isolated rat hearts was studied. These anesthetics are coronary dilators and their effects are dose dependent. At 2 MAC (minimum alveolar concentration), isoflurane, enflurane, and halothane increase coronary flow by 114 +/- 5.9, 93 +/- 6.1, and 77 +/- 6.4%, respectively (p less than 0.001). At these concentrations, they also have a modest but significant metabolic effect causing a 30% reduction in myocardial ATP and phosphocreatine levels, with no significant modification in ADP and AMP concentrations. Energy charge and lactate/pyruvate ratio were also unaffected by these anesthetics. The vascular and metabolic effects were reversible within 2 and 30 min, respectively. Perfusion of the hearts with a Krebs-Henseleit solution without Pi did not interfere with the vascular and the metabolic effect of the anesthetics; however, in this case, ATP and phosphocreatine concentration did not return to control levels after their discontinuation despite full recovery of the vascular effect. These data suggest that the volatile anesthetics have direct coronary vascular and myocardial metabolic effects and that these effects occur independently.


Subject(s)
Coronary Circulation/drug effects , Energy Metabolism/drug effects , Enflurane/pharmacology , Halothane/pharmacology , Heart/drug effects , Isoflurane/pharmacology , Adenosine Diphosphate/metabolism , Adenosine Monophosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , In Vitro Techniques , Magnetic Resonance Spectroscopy , Myocardium/metabolism , Perfusion , Phosphocreatine/metabolism , Rats , Rats, Inbred Strains
14.
Anesth Analg ; 72(4): 454-61, 1991 Apr.
Article in English | MEDLINE | ID: mdl-2006736

ABSTRACT

Active vasoconstriction of epicardial coronary arteries can cause myocardial ischemia in patients with coronary artery disease. Relief of vasoconstriction can improve blood flow to the heart. The purpose of this study was to determine if 1.5 MAC halothane and 1.5 MAC isoflurane would each attenuate contractions evoked by three putative mediators of coronary constriction in coronary arteries removed from the hearts of human beings. Hearts were obtained in the operating room from five patients undergoing cardiac transplantation and from six brain-dead patients undergoing organ donation procedures. Coronary arteries were dissected free, cut into rings, and studied in organ chambers. Endothelium-dependent relaxations to 10(-6) M bradykinin were examined; they indicated a variable degree of endothelial dysfunction in vessels used in the experiments. Contractile responses to 40 mM KCl were tested and were used as control contractions. Contractions evoked by serotonin, histamine, and prostaglandin F2 alpha were measured and were expressed as a percent of contractile responses evoked by 40 mM KCl. Halothane depressed the agonist-induced contractions. Maximal contractile responses to serotonin were 130% +/- 28% in untreated rings and 63% +/- 10% in rings exposed to halothane (P less than 0.03). Responses to histamine were 183% +/- 46% untreated and 121% +/- 26% during halothane administration (P less than 0.05), and responses to prostaglandin F2 alpha were 227% +/- 42% untreated and 148% +/- 18% with halothane (P less than 0.05). Isoflurane had no effect on contractions. The results demonstrate that 1.5 MAC halothane, but not 1.5 MAC isoflurane, attenuates contractile responses evoked by putative mediators of coronary vasoconstriction in coronary arteries removed from the hearts of human beings.


Subject(s)
Halothane/pharmacology , Isoflurane/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/drug effects , Adult , Coronary Vessels/drug effects , Dinoprost/pharmacology , Female , Histamine/pharmacology , Humans , In Vitro Techniques , Male , Middle Aged , Serotonin/pharmacology
16.
Ultrasonics ; 26(6): 348-51, 1988 Nov.
Article in English | MEDLINE | ID: mdl-3263724

ABSTRACT

The effect of ultrasound on the transport of oxygen across excised frog abdominal skin has been studied. Samples were mounted in an exposure chamber in which the Ringer's solution on one side was saturated with oxygen while the other side of the skin had a low initial oxygen concentration. They were treated with ultrasound at 1, 1.5 and 2 W cm-2 SATA c.w., respectively, and increases in the rate of oxygen transport were observed at all intensities. These increases ranged from 38 +/- 4% at 1 W cm-2 to 55 +/- 8% at 2 W cm-2. Variation in the pulse lengths from 25 to 200 ms and a constant average intensity did not affect the rate of transport significantly provided that the temporal intensity was constant. Since the peak acoustic pressure within the pulse increased with decreasing pulse length and increasing acoustic pressure increases the probability of cavitation occurring, the mechanism responsible for this phenomenon is probably not cavitation.


Subject(s)
Oxygen/metabolism , Skin/metabolism , Ultrasonics , Abdomen , Animals , Biological Transport , Diffusion , In Vitro Techniques , Rana catesbeiana
17.
Cell Biol Toxicol ; 4(1): 61-80, 1988 Mar.
Article in English | MEDLINE | ID: mdl-3067829

ABSTRACT

Immunofluorescence staining with antibodies to tubulin, neurofilaments and glial filaments was used to study the effects of methylmercury on the differentiation of retinoic acid-induced embryonal carcinoma cells into neurons and astroglia and on the cytoskeleton of these neuroectodermal derivatives. Methylmercury did not prevent undifferentiated embryonal carcinoma cells from developing into neurons and glia. Treatment of committed embryonal carcinoma cells with methylmercury doses exceeding 1 microM resulted in the formation of neurons with abnormal morphologies. In differentiated cultures, microtubules were the first cytoskeletal element to be affected. Their disassembly was time- and concentration-dependent. Microtubules in glial cells and in neuronal perikarya were more sensitive than those in neuronal processes. Neurofilaments and glial filaments appeared relatively insensitive to methylmercury treatment but showed reorganization after complete disassembly of the microtubules. The data demonstrate 1) the sensitivity of microtubules of both neurons and glia to methylmercury-induced depolymerization, and 2) the heterogeneous response of neuronal microtubules to methylmercury, presumably reflecting posttranslational modifications of different subpopulations of microtubules in the perikarya and neurite.


Subject(s)
Methylmercury Compounds/toxicity , Neurons/cytology , Tretinoin/pharmacology , Animals , Cell Differentiation/drug effects , Cells, Cultured , Cytoskeleton/drug effects , Drug Interactions , Embryonal Carcinoma Stem Cells , Female , Fluorescent Antibody Technique , Humans , Mice , Microtubules/metabolism , Neoplastic Stem Cells/drug effects , Neoplastic Stem Cells/pathology , Pregnancy , Teratoma/pathology
20.
Mol Cell Biol ; 3(12): 2271-9, 1983 Dec.
Article in English | MEDLINE | ID: mdl-6656766

ABSTRACT

We have previously shown that the P19 line of embryonal carcinoma cells develops into neurons, astroglia, and fibroblasts after aggregation and exposure to retinoic acid. The neurons were initially identified by their morphology and by the presence of neurofilaments within their cytoplasm. We have more fully documented the neuronal nature of these cells by showing that their cell surfaces display tetanus toxin receptors, a neuronal cell marker, and that choline acetyl-transferase and acetyl cholinesterase activities appear coordinately in neuron-containing cultures. Several days before the appearance of neurons, there is a marked decrease in the amount of an embryonal carcinoma surface antigen, and at the same time there is a substantial decrease in the volumes of individual cells. Various retinoids were able to induce the development of neurons in cultures of aggregated P19 cells, but it did not appear that polyamine metabolism was involved in the effect. We have isolated a mutant clone which does not differentiate in the presence of any of the drugs which are normally effective in inducing differentiation of P19 cells. This mutant and others may help to elucidate the chain of events triggered by retinoic acid and other differentiation-inducing drugs.


Subject(s)
Mutation , Neoplastic Stem Cells/physiopathology , Neurons/physiology , Stem Cells/physiopathology , Teratoma/physiopathology , Tretinoin/pharmacology , Animals , Cell Differentiation/drug effects , Cell Line , Embryonal Carcinoma Stem Cells , Mice , Mice, Inbred C3H , Neoplastic Stem Cells/drug effects , Neuroglia/physiology , Neurons/drug effects , Teratoma/genetics , Tetanus Toxin
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