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1.
Disabil Rehabil ; 44(7): 1129-1135, 2022 04.
Article in English | MEDLINE | ID: mdl-32720535

ABSTRACT

BACKGROUND AND AIMS: Major trauma impairs health-related quality of life (HRQoL). The aim of this study was the Finnish translation and external validation of the Trauma Quality of Life (TQoL) questionnaire. PATIENTS AND METHODS: The Finnish version of the TQoL questionnaire and the 15D, a generic HRQoL questionnaire, were sent by mail to 417 patients identified from the Helsinki Trauma Registry. RESULTS: Altogether 222 patients (53.2%) returned the questionnaires. Participants' mean age was 49.9 ± 18.1 years and 68.8% were males. The mean 15D score was significantly lower than that of the age- and sex-standardized general Finnish population (0.817 vs. 0.918, p < 0.001). The correlation between the Finnish translation and 15D scores was high (0.805). Factor analysis revealed that the Finnish TQoL questionnaire and the 15D have four common factors. Internal validation identified some differences between the Finnish and the original versions. CONCLUSIONS: The correlation between the Finnish TQoL questionnaire and the 15D was high. The factor structures of the original and Finnish versions of the TQoL questionnaire were not identical, which may be a consequence of cultural or patient population differences.Implications for rehabilitationTrauma causes a long-term decrease in health-related quality of life (HRQoL), and this impact should be assessed in rehabilitation.The Trauma-Specific Quality of Life (TQoL) questionnaire has many shared features with the generic HRQoL questionnaire, but it also contains features related to post-traumatic disorder syndrome.The TQoL questionnaire is a valid tool for monitoring HRQoL after trauma.


Subject(s)
Quality of Life , Translations , Adult , Aged , Factor Analysis, Statistical , Female , Finland , Humans , Male , Middle Aged , Surveys and Questionnaires
2.
Injury ; 51(11): 2517-2523, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32838959

ABSTRACT

BACKGROUND: Trauma registries usually report 30-day or in-hospital mortality as an outcome measure. However, some studies criticize this measure as inadequate; the impact of a major trauma could last longer than 1 month after the injury. We studied the long-term mortality of patients who sustained a major trauma. METHODS: The Helsinki University Hospital's trauma registry was used for patient identification from 2006 to 2015 (New Injury Severity Score ≥ 16 and blunt mechanism of injury). For each trauma registry patient, 10 control persons matched by age, sex, and county of residency were obtained from the Population Register Center of Finland. Cause of death information was obtained from Statistics Finland. RESULTS: We included 3 557 trauma registry patients and 35 502 control persons. Follow-up ranged from 1 year 7 months to 11 years 7 months. The 1-year mortality was 11 times higher in the trauma-patient group (22% vs. 2%). The long-term (approximately 12 years) mortality after the injury was 2.6 times higher in the trauma-patient group (46% vs. 18%). For patients surviving at least 1 year post-trauma, the mortality at 12 years was 2.2 times higher than in the control group (31% vs. 14 %). The cause of death was a disease in 73.3% of the trauma patients and 93.6% of the controls. Accidents were more often a cause of death in the patient population than in the control population (21.2% vs. 4.1%). Suicide was the cause of death in 3.0% of patients and 1.1% in controls. Several factors associated with increased mortality were identified. CONCLUSIONS: Major trauma patients had significantly higher long-term mortality compared to controls. To the best of our knowledge, this is the first study on this subject with a follow up of this duration with patients this severely injured and a cohort this large.


Subject(s)
Wounds and Injuries , Wounds, Nonpenetrating , Finland/epidemiology , Hospital Mortality , Humans , Injury Severity Score , Registries , Retrospective Studies , Trauma Centers
3.
Injury ; 50(11): 1929-1933, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31431335

ABSTRACT

BACKGROUND AND AIMS: We aimed to determine whether the outcome of severely injured patients differs based on admission time (office hours vs. non-office hours) at a tertiary trauma centre without an in-house trauma surgeon consultant available at all times. We also studied subgroups of patients presenting with a New Injury Severity Score (NISS) ≥ 25 and patients experiencing major bleeding. PATIENTS AND METHODS: This trauma registry study consisted of severely injured patients (NISS > 15) with blunt trauma treated between 2006 and 2017 at a single institute. Causes of deaths were obtained from autopsy reports and classified as resulting from brain injury; exsanguination; multi-organ failure, adult respiratory distress syndrome, or sepsis; or other. RESULTS: Among 1853 patients, 497 (27%) were admitted during office hours (OH) and 1356 (73%) during non-office hours (NOH). Further subgroup analysis consisted of 211 OH and 611 NOH patients with NISS ≥ 25, and 51 OH and 154 NOH patients experiencing major bleeding. The 30-day in-hospital mortality was 3.8%-7.4% lower in the NOH groups. We found no significant differences between the study groups in neither the standardised mortality ratio (SMR, defined as the ratio of observed to expected mortality) nor in the causes of death. In both groups, the primary cause of death resulted from brain injury. CONCLUSIONS: We found that arrival time did not affect mortality among patients with severe blunt trauma treated at a tertiary trauma centre without an in-house trauma surgeon consultant available at all times. Thus, this type of unit can maintain a standard of care during non-office hours by investing in precise treatment protocols and continuous education. However, our results do not apply to penetrating trauma injury patients.


Subject(s)
Multiple Organ Failure/mortality , Multiple Trauma/mortality , Registries/statistics & numerical data , Respiratory Distress Syndrome/mortality , Time-to-Treatment/statistics & numerical data , Trauma Centers , Wounds, Nonpenetrating/mortality , Adult , Female , Finland/epidemiology , Glasgow Coma Scale , Hospital Mortality , Humans , Injury Severity Score , Male , Middle Aged , Outcome Assessment, Health Care , Retrospective Studies , Wounds, Nonpenetrating/physiopathology , Wounds, Nonpenetrating/therapy
4.
Eur J Trauma Emerg Surg ; 45(4): 585-595, 2019 Aug.
Article in English | MEDLINE | ID: mdl-30225555

ABSTRACT

PURPOSE: Serious thoracic injuries are associated with high mortality, morbidity, and costs. We compared patient populations, treatment, and survival of serious thoracic injuries in southern Finland and Germany. METHODS: Mortality, patient characteristics and treatment modalities were compared over time (2006-2015) in all patients with Abbreviated Injury Scale (AIS) thorax ≥ 3, Injury Severity Score (ISS) > 15, age > 15 years, blunt trauma mechanism, and treatment in Intensive Care Unit (ICU) in Level 1 hospitals included in the Helsinki Trauma Registry (HTR) and the TraumaRegister DGU® (TR-DGU). RESULTS: We included 934 patients from HTR and 25 448 patients from TR-DGU. Pre-hospital differences were seen between HTR and TR-DGU; transportation in the presence of a physician in 61% vs. 97%, helicopter use in 2% vs. 42%, intubation in 31% vs. 55%, and thoracostomy in 6% vs. 10% of cases, respectively. The mean hospital length of stay (LOS) and ICU LOS was shorter in HTR vs. TR-DGU (13 vs. 25 days and 9 vs. 12 days, respectively). Our main outcome measure, standardised mortality ratio, was not statistically significantly different [1.01, 95% confidence interval (CI) 0.84-1.18; HTR and 0.97, 95% CI 0.94-1.00; TR-DGU]. CONCLUSIONS: Major differences were seen in pre-hospital resources and use of pre-hospital intubation and thoracostomy. In Germany, pre-hospital intubation, tube thoracostomy, and on-scene physicians were more prevalent, while patients stayed longer in ICU and in hospital compared to Finland. Despite these differences in resources and treatment modalities, the standardised mortality of these patients was not statistically different.


Subject(s)
Emergency Medical Services/statistics & numerical data , Thoracic Injuries/therapy , Wounds, Nonpenetrating/therapy , Accidental Falls/statistics & numerical data , Accidents, Traffic/statistics & numerical data , Adolescent , Adult , Age Distribution , Aged , Epidemiologic Methods , Facilities and Services Utilization , Female , Finland/epidemiology , Germany/epidemiology , Hospitalization/statistics & numerical data , Humans , Intubation/statistics & numerical data , Length of Stay/statistics & numerical data , Male , Middle Aged , Patient Care Team/statistics & numerical data , Sex Distribution , Thoracic Injuries/etiology , Thoracic Injuries/mortality , Time-to-Treatment/statistics & numerical data , Transportation of Patients/statistics & numerical data , Wounds, Nonpenetrating/etiology , Wounds, Nonpenetrating/mortality , Young Adult
5.
Injury ; 48(2): 432-435, 2017 Feb.
Article in English | MEDLINE | ID: mdl-28041612

ABSTRACT

BACKGROUND AND PURPOSE: Post-operative follow-up after internal fixation of fractures is a common practice. The goal of this study was to evaluate the necessity of a routine follow-up visit after internal fixation of a proximal femoral fracture. Our hypothesis is that these follow-up visits do not result in a change in the treatment plan, but add an extra cost to the health care system and lead to the purposeless utilisation of limited resources. PATIENTS AND METHODS: A retrospective study of 428 consecutive patients (431 fractures) with a scheduled outpatient clinic visit after internal fixation of proximal femoral fractures in a single hospital during years 2012-2013. We noted any changes in the patients' treatment plans based on the first follow-up visits, including scheduled visits up to ten weeks after internal fixation. RESULTS: None of the patients showed signs of infection, implant failure or loss of reduction requiring re-operation at the scheduled follow-up visit. In only one (0.23%) visit a change in treatment plan was made as a result of the scheduled follow-up visit (decision to remove the distal screws from the long intramedullary nail to obtain dynamic compression). Scheduled visits did not occur for the following reasons, death (11.8%), visit to emergency department prior scheduled visit (3.2%), and not known (3.9%). CONCLUSIONS: The first scheduled visit within ten weeks after internal fixation of a proximal femoral fracture leads to no changes in treatment. We recommend considering the need of these follow-up visits.


Subject(s)
Fracture Fixation, Internal/rehabilitation , Hip Fractures/rehabilitation , Office Visits/statistics & numerical data , Adult , Aged , Aged, 80 and over , Female , Finland/epidemiology , Follow-Up Studies , Fracture Fixation, Internal/economics , Fracture Healing , Hip Fractures/economics , Hip Fractures/surgery , Humans , Male , Middle Aged , Office Visits/economics , Outcome Assessment, Health Care , Outpatients , Postoperative Care/economics , Postoperative Care/statistics & numerical data , Radiography/statistics & numerical data , Retrospective Studies , Treatment Outcome , Unnecessary Procedures/economics , Unnecessary Procedures/statistics & numerical data , Young Adult
6.
Injury ; 47(11): 2575-2578, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27622614

ABSTRACT

It is a common practice that patients have a scheduled follow-up visit with radiographs following ankle fracture surgery. The aim of this study was to evaluate whether an early outpatient visit (<3 weeks) after ankle fracture surgery resulted in a change in patient management. For this study, 878 consecutive operatively treated ankle fracture patients with an early outpatient clinical-radiological visit were reviewed. The outcome measure was a change in treatment plan defined as any procedure, medication, or surgical intervention that is not typically implemented during the uncomplicated healing process of an acute fracture. A change in treatment plan was observed in 9.8% of operatively treated ankle fracture patients. The mean age of the patients was 48 years and the mean follow-up time was 64 months. Of the changes in treatment plan, 91% were exclusively due to clinical findings such as infection. Only three of 878 patients required a change in their treatment plan based merely on the findings of the radiographs taken at the outpatient visit. Only 37% of the patients requiring a change in their postoperative management had solicited an unanticipated visit before the scheduled outpatient visit due to clinical problems such as infection or a cast-related issue. Our study showed that every tenth operatively treated ankle fracture patient requires a change in their treatment plan due to a clinical problem such as infection or a cast-related issue. Although at hospital discharge all patients are provided with written instructions on where to contact if problems related to the operated ankle emerge, only one third of the patients are aware of the clinically alarming symptoms and seek care when problems present. Our findings do not support obtaining routine radiographs at the early outpatient visit in an ankle fracture patient without clinical signs of a complication.


Subject(s)
Ankle Fractures/surgery , Fracture Fixation, Internal/rehabilitation , Outpatients , Postoperative Complications/diagnostic imaging , Radiography/statistics & numerical data , Surgical Wound Infection/diagnostic imaging , Adolescent , Adult , Aged , Aged, 80 and over , Ankle Fractures/diagnostic imaging , Ankle Fractures/physiopathology , Casts, Surgical , Female , Finland/epidemiology , Follow-Up Studies , Fracture Healing , Humans , Male , Middle Aged , Office Visits , Postoperative Care/methods , Range of Motion, Articular , Surgical Wound Infection/prevention & control , Treatment Outcome , Young Adult
7.
Duodecim ; 132(13-14): 1247-51, 2016.
Article in Finnish | MEDLINE | ID: mdl-27522833

ABSTRACT

Contacts between humans and animals inevitably involve encounters possibly resulting in the human being injured. During the period of 2000 to 2014 almost 90 people died in this kind of conflict in Finland. Of these deaths, one third were associated with horses. In addition, over the same period 85 people died in traffic accidents in which an animal was hit by a car. Accidents requiring hospitalization occurred for approx. 8 000 people.


Subject(s)
Horses , Wounds and Injuries/etiology , Accidents, Traffic , Animals , Finland/epidemiology , Hospitalization/statistics & numerical data , Humans , Wounds and Injuries/epidemiology
8.
J Adv Nurs ; 72(9): 2196-206, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27113362

ABSTRACT

AIMS: The aim of this study was to evaluate the influence of tailored patient education on adherence to tyrosine kinase inhibitor medication among patients with chronic myeloid leukaemia. BACKGROUND: Management of chronic myeloid leukaemia has changed dramatically during the last decade. While medication adherence is crucial to clinical response, little is known about how to improve patients' adherence. DESIGN: Randomized multicentre intervention study. METHODS: The study was conducted between June 2012-August 2014. Eighty-six patients with chronic myeloid leukaemia who had been on tyrosine kinase inhibitor medication for at least six months from eight hospitals were randomized into intervention and control groups. Intervention combined nurse-conducted medication counselling, an information booklet, video and website and text message reminders. Patients were interviewed to assess medication adherence using Morisky's 8-Item Medication Adherence Scale at baseline and nine months. RESULTS: Medication adherence improved with the adherence aids used. At nine months, 51% of patients were highly adherent in the intervention group, compared with 21% in the control group. Adherence improved for a higher proportion of patients in the intervention group than the control group (49% vs. 18%). Morisky's score decreased in almost half of control group cases. Patients were most satisfied with face-to-face counselling (86%) and the information booklet (83%) and least satisfied with text messages (9%). CONCLUSION: Tailored patient education improved the medication adherence of patients with chronic myeloid leukaemia. Without this, adherence behaviour tended to decline. Personal communication with a nurse proved to be an essential part of adherence support and should not be ignored.


Subject(s)
Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy , Patient Education as Topic , Protein-Tyrosine Kinases/antagonists & inhibitors , Adult , Aged, 80 and over , Female , Humans , Immunoglobulin G/therapeutic use , Internet , Male , Medication Adherence , Melphalan/therapeutic use , Middle Aged , Reminder Systems , Text Messaging
9.
Injury ; 45(12): 1914-20, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25270692

ABSTRACT

Spinopelvic dissociation is a rare high-energy injury, which is frequently associated with lumbosacral plexus and cauda equina deficits. During an 18-year period, 36 consecutive patients with a H-type sacral fracture and spinopelvic dissociation were treated using lumbopelvic fixation with a minimum follow-up of 18 months. We evaluated factors prognostic of outcome after standardised surgical fixation and neural decompression. Neurological recovery was assessed by Gibbons' criteria. Pelvis Outcome Scale (POS clinical score) was used to evaluate the clinical outcome. Despite excellent or good radiological results in the vertical components of the sacral fractures having been achieved in all patients, 15 patients (42%) had a poor clinical outcome. The degree of initial translational displacement in the transverse sacral fracture was significantly associated with neurological recovery (as defined by a change in Gibbons score) (p = 0.038) and final POS clinical score (p < 0.001). Both neurological recovery and clinical outcome were worse in patients with completely displaced fractures than in patients with a partially displaced sacral fracture. The degree of residual translational displacement and kyphosis in the transverse sacral fracture were also associated with clinical outcome (POS clinical score) (p = 0.011 and p = 0,018, respectively). However, Roy-Camille classification (type 2 vs. type 3), age, gender, ISS, timing of surgery, and sacral laminectomy did not have a statistically significant association with the outcome. Based on the results, Roy-Camille sacral fracture classification (type 2 vs. type 3) was not prognostic of neurological impairment. Thus further categorisation of the transverse sacral fractures as partially displaced or completely displaced could be used to predict the rate of neurological recovery following lumbopelvic fixation. Accurate reduction of all sacral fracture components seems to be associated with better clinical outcome.


Subject(s)
Cauda Equina/surgery , Decompression, Surgical/methods , Fracture Fixation, Internal , Fractures, Bone/surgery , Kyphosis/surgery , Pelvis/surgery , Sacrum/surgery , Adolescent , Adult , Aged , Cauda Equina/injuries , Cauda Equina/pathology , Female , Fractures, Bone/diagnostic imaging , Fractures, Bone/pathology , Humans , Kyphosis/diagnostic imaging , Male , Middle Aged , Pelvis/injuries , Pelvis/pathology , Prognosis , Radiography , Retrospective Studies , Sacrum/injuries , Sacrum/pathology , Treatment Outcome
12.
Eur J Trauma Emerg Surg ; 35(5): 455-62, 2009 Oct.
Article in English | MEDLINE | ID: mdl-26815211

ABSTRACT

OBJECTIVE: The aim of the present study was to characterise traumatic deaths occurring in the emergency room (ER) and to assess retrospectively the quality of given emergency care by evaluating whether any of the deaths could be identified as potentially preventable. METHODS: All consecutive deaths of trauma patients between 1 January 1998 and 31 December 2006 in the ER of the Töölö Hospital Trauma Centre were retrospectively reviewed. The inclusion criterion was death of a trauma patient occurring in the ER. Both the pre- and inhospital medical charts and the autopsy reports of the patients were reviewed. RESULTS: A total of 115 patients fulfilled the inclusion criteria, and the autopsy reports were obtained for all of these cases (100%). The patients were mainly males (n = 84; 73%), and the median age of the patients was 51 years (range 1-93 years). The average injury severity score (ISS) was 34.6. Blunt trauma was the most common type of injury in the study population. A total of 115 injuries in 50 patients were missed in both the clinical and radiological surveys in the ER, i.e., a missed injury was identified in 43% of the cases. Of these patients, 15.7% had a clinically significant missed injury (AIS ≥ 4). Based on our review of all available material, we consider that 11 deaths (9.6%) were potentially preventable. CONCLUSIONS: Missed injuries did not play a major role in the preventable deaths. Seven potentially preventable deaths were considered to be failures in the surgical decision-making process, resulting in futile non-operative treatment or a delay in surgical bleeding control.

13.
Chem Phys Lipids ; 133(1): 51-67, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15589226

ABSTRACT

Lysobisphosphatidic acid (LBPA) can be regarded to represent a unique derivative of phosphatidylglycerol. This lipid is highly enriched in late endosomes where it can comprise up to 10-15 mol% of all lipids and in these membranes, LBPA appears to be segregated into microdomains. We studied the thermotropic behavior of pure dioleoyl-LBPA mono- and bilayers using Langmuir-lipid monolayers, electron microscopy, differential scanning calorimetry (DSC), and fluorescence spectroscopy. LBPA formed metastable, liquid-expanded monolayers at an air/buffer interface, and its compression isotherms lacked any indication for structural phase transitions. Neat LBPA formed multilamellar vesicles with no structural transitions or phase transitions between 10 and 80 degrees C at a pH range of 3.0-7.4. We then proceeded to study mixed LBPA/dipalmitoylphosphatidylcholine (DPPC) bilayers by DSC and fluorescence spectroscopy. Incorporating increasing amounts of LBPA (up to X(LBPA) (molar fraction)=0.10) decreased the co-operativity of the main transition for DPPC, and a decrease in the main phase transition as well as pretransition temperature of DPPC was observed yet with no effect on the enthalpy of this transition. In keeping with the DSC data for DPPC, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC)/LBPA mixed bilayers were more fluid, and no evidence for lateral phase segregation was observed. These results were confirmed using fluorescence microscopy of Langmuir-lipid films composed of POPC and LBPA up to X(LBPA)=0.50 with no evidence for lateral phase separation. As late endosomes are eminently acidic, we examined the effect of lowering pH on lateral organization of mixed PC/LBPA bilayers by DSC and fluorescence spectroscopy. Even at pH 3.0, we find no evidence of LBPA-induced microdomain formation at LBPA contents found in cellular organelles.


Subject(s)
Lipid Bilayers/chemistry , Lysophospholipids/chemistry , Phosphatidylcholines/chemistry , Calorimetry, Differential Scanning , Fluorescent Dyes , Hydrogen-Ion Concentration , Microscopy, Electron , Monoglycerides , Structure-Activity Relationship , Temperature
14.
Mol Pharmacol ; 66(1): 161-8, 2004 Jul.
Article in English | MEDLINE | ID: mdl-15213308

ABSTRACT

The membrane interactions of pregnanolone, an intravenous general anesthetic steroid, were characterized using fluorescence spectroscopy and monolayer technique. di-8-ANEPPS [4-[2-[6-(dioctylamino)-2-naphthalenyl]ethenyl]-1-(3-sulfopropyl)-pyridinium], a membrane dipole potential (Psi)-sensitive probe, revealed pregnanolone to decrease Psi similarly as reported previously for other anesthetics. The decrement in Psi was approximately 16 and 10 mV in dipalmitoylphosphatidylcholine (DPPC) and DPPC/cholesterol (90:10, mol/mol) vesicles, respectively. Diphenylhexatriene anisotropy indicated pregnanolone to have a negligible effect on the acyl chain order. In contrast, substantial changes were observed for the fluorescent dye Prodan, thus suggesting pregnanolone to reside in the interfacial region of lipid bilayers. Langmuir balance studies indicated increased association of pregnanolone to DPPC monolayers containing cholesterol or 6-ketocholestanol at surface pressures pi > 20 mN/m as well as to monolayers of the unsaturated 1-palmitoyl-2-oleoylphosphatidylcholine. In the same surface pressure range, the addition of phloretin, which decreases Psi, reduced the penetration of pregnanolone into the monolayers. These results suggest that membrane partitioning of pregnanolone is influenced by the spacing of the phosphocholine head groups as well as by membrane dipole potential. The latter can be explained in terms of electrostatic dipole-dipole interactions between pregnanolone and the membrane lipids with their associated water molecules. Considering the universal nature of these interactions, they are likely to affect membrane partitioning of most, if not all, weakly amphiphilic drugs.


Subject(s)
Liposomes/chemistry , Membrane Lipids/chemistry , Pregnanolone/chemistry , Anesthetics/chemistry , Membranes/chemistry , Static Electricity , Surface-Active Agents/chemistry , Water/chemistry
15.
J Med Chem ; 47(7): 1783-8, 2004 Mar 25.
Article in English | MEDLINE | ID: mdl-15027870

ABSTRACT

The present study describes a novel in vitro platform for physicochemical profiling of compounds, based on their impact on the air/water interfacial tension. Interfacial partitioning coefficient, cross-sectional area, and critical micelle concentration were derived from the Gibbs adsorption isotherms recorded for 76 structurally diverse drugs. An approximation for the membrane partitioning coefficient, K(memb), is introduced and calculated for the measured compounds. This methodology provides a fully automatic, high-throughput screening technique for compound characterization, yielding precise thermodynamic information on the partitioning behavior of molecules at air/water interfaces, which can be directly related to their anisotropic interaction with lipid bilayers in biological membranes. The latter represents the barrier for the passive entry of compounds into cells. The surface activity profiles are shown to correlate to the ability of the compounds to pass passively through the blood-brain barrier.


Subject(s)
Blood-Brain Barrier/chemistry , Pharmaceutical Preparations/chemistry , Blood-Brain Barrier/metabolism , Lipid Bilayers/chemistry , Micelles , Permeability , Pharmaceutical Preparations/metabolism , Structure-Activity Relationship , Surface Properties
16.
Biophys J ; 85(4): 2333-41, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14507697

ABSTRACT

The effects of three so-called kosmotropic solutes, namely, betaine, sucrose, and choline chloride on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine large unilamellar vesicles, were studied by measuring the generalized polarization (GP) for the fluorescence emission of the membrane partitioning probe Laurdan. The latter has been shown to be sensitive to the depth of water penetration into phospholipid bilayers. At equal osmotic pressures the three solutes produced different increments in GP, with a qualitative positive correlation. However, the increments in GP correlated also quantitatively with the increase of air-water surface tension caused by the three kosmotropes. Our findings suggest surface tension to determine the impact of these solutes on the lateral packing of the lipid bilayer. Based on the changes in area/lipid at different surface tensions, the equilibrium lateral pressure for a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer at 25 degrees C was estimated to be approximately 34 mN/m.


Subject(s)
Lipid Bilayers/chemistry , Liposomes/chemistry , Membrane Fluidity , Models, Molecular , Phosphatidylcholines/chemistry , Solvents/chemistry , Water-Electrolyte Balance , Water/chemistry , Betaine/chemistry , Choline/chemistry , Computer Simulation , Osmotic Pressure , Solutions , Sucrose/chemistry , Surface Properties , Surface Tension
17.
Biophys J ; 83(2): 932-43, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12124275

ABSTRACT

Macroscopic consequences of the formation of diacylglycerol by phospholipase C (PC-PLC) in giant 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) unilamellar vesicles (GUVs, diameter 10-100 microm) were studied by phase contrast and fluorescence microscopy. PC-PLC caused a series of fast stepwise shrinkages of fluid SOPC GUVs, continuing until the vesicle disappeared beyond the optical resolution of the microscope. The presence of N-palmitoyl-sphingomyelin (mole fraction X = 0.25) in the GUVs did not affect the outcome of the PC-PLC reaction. In addition to hydrolysis, PC-PLC induced adhesion of vicinal vesicles. When multilamellar SOPC vesicles were used only a minor decrease in their diameter was evident suggesting that PC-PLC can exert its hydrolytic activity only in the outer monolayer. A series of stepwise shrinkages was observed also for 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) GUVs above their main phase transition temperature, T(m), i.e., when the bilayer is in the liquid crystalline state. However, this process was not observed for DMPC GUVs in the gel state, below T(m). These results are supported by the enhanced activity of PC-PLC upon exceeding T(m) of DMPC large unilamellar vesicles (diameter approximately 0.1 microm) used as a substrate. Studies on SOPC monolayers revealed that PC-PLC can exert its hydrolytic activity only at surface pressures below approximately 30 mN/m. Accordingly, the lack of changes in the gel state DMPC GUVs could be explained by the equilibrium lateral pressure in these vesicles exceeding this critical value.


Subject(s)
Liposomes/metabolism , Type C Phospholipases/chemistry , Type C Phospholipases/metabolism , Bacillus cereus/enzymology , Biophysical Phenomena , Biophysics , Chromatography, Thin Layer , Membranes, Artificial , Microscopy, Fluorescence , Microscopy, Phase-Contrast , Platinum/chemistry , Temperature , Time Factors
18.
Biophys J ; 83(2): 954-67, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12124277

ABSTRACT

Poly(ethylene glycol)(2000)C(20)ceramide (PEG-Cer) containing monolayers at an air/water interface were characterized by measuring their surface pressure versus area/molecule (pi-A) and surface potential versus area/molecule (Delta V-A) isotherms. The behavior of pi-A as well as Delta V versus lipid density (Delta V-n) and Delta V-pi isotherms for PEG-Cer are in keeping with two transitions of the lipopolymer, starting at pi approximately equal to 9 and 21 mN/m. We also investigated the effects of PEG-Cer on the binding of adriamycin, cytochrome c and bovine serum albumin to monolayers containing varying mole fractions X of PEG-Cer. PEG-Cer impedes the penetration of these ligands into lipid monolayers with similar effects at both X = 0.04 and 0.08. This effect of PEG-Cer depends on the conformation of the lipopolymer and the interactions between the lipid surface and the surface-interacting molecule as well as the size of the latter.


Subject(s)
Ceramides/chemistry , Cytochrome c Group/metabolism , Doxorubicin/metabolism , Lipids/chemistry , Polyethylene Glycols/chemistry , Serum Albumin/metabolism , Air , Animals , Antibiotics, Antineoplastic/chemistry , Antibiotics, Antineoplastic/metabolism , Biophysical Phenomena , Biophysics , Chickens , Cytochrome c Group/chemistry , Doxorubicin/chemistry , Horses , Ligands , Membrane Potentials , Microscopy, Fluorescence , Phosphatidylethanolamines/chemistry , Serum Albumin/chemistry , Temperature , Water
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