Trauma-registry survival outcome follow up: 30 days is mandatory and appears sufficient.

INTRODUCTION: Thirty-day in-hospital mortality is a common outcome measure in trauma-registry research and benchmarking. However, this does not include deaths after hospital discharge before 30 days or late deaths beyond 30 days since the injury. To evaluate the reliability of this outcome measure, we assessed the timing and causes of death during the first year after major blunt trauma in patients treated at a single tertiary trauma center. METHODS: We used the Helsinki Trauma Registry to identify severely injured (NISS ≥ 16) blunt trauma patients during 2006 to 2015. The Population Register center of Finland provided the mortality data for patients and Statistics Finland provided the cause of death information from death certificates. Disease, work-related disease, medical treatment, and unknown cause of death were considered as non-trauma related deaths. We divided the 1-year study period into the following three categories: in-hospital death before 30 days (Group 1), death after discharge but within 30 days (Group 2), and death 31 to 365 days since admission (Group 3). RESULTS: We included 3557 patients with a median NISS of 29. Altogether, 21.8% (776/3557) patients died during the first year since the injury. Of these non-survivors, 12.7% (450) were in Group 1, 4.0% (141) in Group 2, and 5.2% (185) in Group 3. Non-traumatic deaths not directly related to the injury increased substantially as the time from the injury increased and were 2.0% (9/450) in Group 1, 13.5% (19/141) in Group 2, and 35.7% (66/185) in Group 3. CONCLUSION: Thirty-day mortality is a proper outcome that measures survival after severe blunt trauma. However, applying only in-hospital mortality instead of actual 30-day mortality may exclude non-survivors who die at another facility before day 30. This could result in over-optimistic benchmarking results. On the other hand, extending the follow-up period beyond 30 days increases the rate of non-traumatic deaths. By combining data from different registries, it is possible to address this challenge in current trauma-registry research caused by lack of follow up.

How to Validate Data Quality in a Trauma Registry? The Helsinki Trauma Registry Internal Audit.

BACKGROUND AND AIMS: Trauma registry data are used for analyzing and improving patient care, comparison of different units, and for research and administrative purposes. Data should therefore be reliable. The aim of this study was to audit the quality of the Helsinki Trauma Registry internally. We describe how to conduct a validation of a regional or national trauma registry and how to report the results in a readily comprehensible form. MATERIALS AND METHODS: Trauma registry database of Helsinki Trauma Registry from year 2013 was re-evaluated. We assessed data quality in three different parts of the data input process: the process of including patients in the trauma registry (case completeness); the process of calculating Abbreviated Injury Scale (AIS) codes; and entering the patient variables in the trauma registry (data completeness, accuracy, and correctness). We calculated the case completeness results using raw agreement percentage and Cohen's κ value. Percentage and descriptive methods were used for the remaining calculations. RESULTS: In total, 862 patients were evaluated; 853 were rated the same in the audit process resulting in a raw agreement percentage of 99%. Nine cases were missing from the registry, yielding a case completeness of 97.1% for the Helsinki Trauma Registry. For AIS code data, we analyzed 107 patients with severe thorax injury with 941 AIS codes. Completeness of codes was 99.0% (932/941), accuracy was 90.0% (841/932), and correctness was 97.5% (909/932). The data completeness of patient variables was 93.4% (3899/4174). Data completeness was 100% for 16 of 32 categories. Data accuracy was 94.6% (3690/3899) and data correctness was 97.2% (3789/3899). CONCLUSION: The case completeness, data completeness, data accuracy, and data correctness of the Helsinki Trauma Registry are excellent. We recommend that these should be the variables included in a trauma registry validation process, and that the quality of trauma registry data should be systematically and regularly reviewed and reported.

Bleeding Pelvic Fracture Patients: Evolution of Resuscitation Protocols.

BACKGROUND AND AIMS: Massive transfusion protocol seems to improve outcome in massively bleeding trauma patients, but not pelvic fracture patients. The aim of this study was to evaluate the effect of massive transfusion protocol on the mortality and fluid resuscitation of shocked pelvic fracture patients. MATERIAL AND METHODS: This is a trauma register study from a single hospital. From the trauma registry patients with pelvic fracture, injury severity score >15, admission base excess below -5, age >15 years, blunt trauma, and primary admission from the scene were identified. Patients were divided into two groups: Group 1-pre-massive transfusion protocol (2006-2009) and Group 2-post-massive transfusion protocol (2010-2013). Basic characteristics and intensive care unit length of stay, mortality, and fluid resuscitation data were retrieved from the registry. Standardized mortality ratio was assessed using revised injury severity classification, version II methodology. RESULTS: Altogether, 102 patients were identified. Group 1 ( n = 56) and Group 2 ( n = 46) were comparable in their basic characteristics. The observed mortality was 35.7% and 26.1% in Groups 1 and 2, respectively. The standardized mortality ratio failed to reveal any difference between observed and expected mortality in either group. In the emergency room, the use of crystalloids decreased from 5.3 ± 3.4 to 3.3 ± 1.8 L ( p = 0.002) with increased use of fresh frozen plasma (2.9 ± 4.4 vs 5.1 ± 5.3, p = 0.007). CONCLUSION: No improvement in the adjusted survival of shocked pelvic fracture patients is apparent after implementation of massive transfusion protocol. Implementation of massive transfusion protocol is associated with a higher use of fresh frozen plasma and improved ratio of fresh frozen plasma:red blood cell toward the targeted 1:1 and decreased use of crystalloids.

Accuracy and Coverage of Diagnosis and Procedural Coding of Severely Injured Patients in the Finnish Hospital Discharge Register: Comparison to Patient Files and the Helsinki Trauma Registry.

BACKGROUND AND AIMS: The Finnish Hospital Discharge Register data are frequently used for research purposes. The Finnish Hospital Discharge Register has shown excellent validity in single injuries or disease groups, but no studies have assessed patients with multiple trauma diagnoses. We aimed to evaluate the accuracy and coverage of the Finnish Hospital Discharge Register but at the same time validate the data of the trauma registry of the Helsinki University Hospital's Trauma Unit. MATERIALS AND METHODS: We assessed the accuracy and coverage of the Finnish Hospital Discharge Register data by comparing them to the original patient files and trauma registry files from the trauma registry of the Helsinki University Hospital's Trauma Unit. We identified a baseline cohort of patients with severe thorax injury from the trauma registry of the Helsinki University Hospital's Trauma Unit of 2013 (sample of 107 patients). We hypothesized that the Finnish Hospital Discharge Register would lack valuable information about these patients. RESULTS: Using patient files, we identified 965 trauma diagnoses in these 107 patients. From the Finnish Hospital Discharge Register, we identified 632 (65.5%) diagnoses and from the trauma registry of the Helsinki University Hospital's Trauma Unit, 924 (95.8%) diagnoses. A total of 170 (17.6%) trauma diagnoses were missing from the Finnish Hospital Discharge Register data and 41 (4.2%) from the trauma registry of the Helsinki University Hospital's Trauma Unit data. The coverage and accuracy of diagnoses in the Finnish Hospital Discharge Register were 65.5% (95% confidence interval: 62.5%-68.5%) and 73.8% (95% confidence interval: 70.4%-77.2%), respectively, and for the trauma registry of the Helsinki University Hospital's Trauma Unit, 95.8% (95% confidence interval: 94.5%-97.0%) and 97.6% (95% confidence interval: 96.7%-98.6%), respectively. According to patient records, these patients were subjects in 249 operations. We identified 40 (16.1%) missing operation codes from the Finnish Hospital Discharge Register and 19 (7.6%) from the trauma registry of the Helsinki University Hospital's Trauma Unit. CONCLUSION: The validity of the Finnish Hospital Discharge Register data is unsatisfactory in terms of the accuracy and coverage of diagnoses in patients with multiple trauma diagnoses. Procedural codes provide greater accuracy. We found the coverage and accuracy of the trauma registry of the Helsinki University Hospital's Trauma Unit to be excellent. Therefore, a special trauma registry, such as the trauma registry of the Helsinki University Hospital's Trauma Unit, provides much more accurate data and should be the preferred registry when extracting data for research or for administrative use, such as resource prioritizing.

Radiological evaluation of tube depth and complications of prehospital endotracheal intubation in pediatric trauma: a descriptive study.

PURPOSE: Pediatric prehospital endotracheal intubation (PHETI) is a difficult and rarely performed procedure that remains the gold standard for prehospital airway management when ventilation and/or anesthesia is required, but high complications rates, including malposition continue to concern. We reviewed the experience in our institution of pediatric intubations with particular emphasis on the position of the endotracheal tube (ETT) tip within the trachea and related complications. METHOD: Intubated pediatric patients presenting directly from the scene to our level 1 trauma center, between 2006 and 2014, were included in our study. Patient records and radiographs were retrospectively reviewed to identify the ETT tip-to-carina distance and possible intubation-related complications. ETT tips identified beyond the carina on radiographs or by clinical diagnosis were defined as misplaced. Because head movement causes a significant ETT movement within the trachea, which is age related, we also defined ETT tip placement (1) less than 2 cm above the carina in children younger than 8 and (2) less than 3 cm above the carina in children 8 years or older as "near miss" intubations. RESULTS: From a total of 34 cases, ETT misplacement was identified in seven cases. Diagnosis was made radiologically in five cases and clinically in two cases. Four of these patients had left lung atelectasis due to tube misplacement. Tube thoracotomy was performed in two of these patients without concurrent evidence of chest injury. "Near miss" intubations accounted for 7/9 and 9/25 in children <8 years and ≥8 years old, respectively, totaling 16/34, with two of these leading to late displacements. CONCLUSIONS: Pediatric endotracheal tube intubation carries a high rate of tube malposition and left lung atelectasis in our experience of pediatric trauma patients, with less than a third of ETTs placed in a safe position.

Missed Injuries in Polytrauma Patients after Trauma Tertiary Survey in Trauma Intensive Care Unit.

BACKGROUND AND AIMS: Injuries are often missed during the primary and secondary surveys in trauma patients. Studies have suggested that a formal tertiary survey protocol lowers the number of missed injuries. Our aim was to determine the number, severity, and consequences of injuries missed by a non-formalized trauma tertiary survey, but detected within 3 months from the date of injury in trauma patients admitted to a trauma intensive care unit. MATERIAL AND METHODS: We conducted a cohort study of trauma patients admitted to a trauma intensive care unit between 1 January and 17 October 2013. We reviewed the electronic medical records of patients admitted to the trauma intensive care unit in order to register any missed injuries, their delay, and possible consequences. We classified injuries into four types: Type 0, injury detected prior to trauma tertiary survey; Type I, injury detected by trauma tertiary survey; Type II, injury missed by trauma tertiary survey but detected prior to discharge; and Type III, injury missed by trauma tertiary survey and detected after discharge. RESULTS: During the study period, we identified a total of 841 injuries in 115 patients. Of these injuries, 93% were Type 0 injuries, 3.9% were Type I injuries, 2.6% were Type II injuries, and 0,1% were Type III injuries. Although most of the missed injuries in trauma tertiary survey (Type II) were fractures (50%), only 2 of the 22 Type II injuries required surgical intervention. Type II injuries presumably did not cause extended length of stay in the intensive care unit or in hospital and/or morbidity. CONCLUSION: In conclusion, the missed injury rate in trauma patients admitted to trauma intensive care unit after trauma tertiary survey was very low in our system without formal trauma tertiary survey protocol. These missed injuries did not lead to prolonged hospital or trauma intensive care unit stay and did not contribute to mortality. Most of the missed injuries received non-surgical treatment.

Factors associated with in-hospital outcomes in 594 consecutive patients suffering from severe blunt chest trauma.

BACKGROUND AND AIMS: Blunt thoracic injury is a common cause for hospital admission after trauma. The effect of the number of rib fractures on the outcome is controversial. In this study, our hypothesis was that an increasing number of rib fractures correlates with mortality and hospital resource utilization. In addition to mortality, our focus was on the length of stay at hospital and in the intensive care unit, ventilator days, and the days in continuous positive airway pressure. MATERIAL AND METHODS: The present investigation is a retrospective study from a single trauma center. The study includes patients with severe thoracic injury (thoracic Abbreviated Injury Scale (AIS) > 2) admitted to hospital after blunt trauma. Patients with isolated thoracic spine injuries and patients who were dead on arrival were excluded. Vital signs, laboratory results on admission, given care, intensive care unit and hospital length of stay, injuries, and in-hospital mortality were collected for the study. RESULTS: A total of 594 patients from a 5-year period (2003-2007) were included in the study. The mean age of the patients was 45 years, and 76.9% of the patients were males. The average Injury Severity Score was 22, and the patients had on average 5.5 injuries. Overall mortality was 6.4%. In the multivariate analysis, the mortality was associated with base excess and tromboplastin time in admission. The number of rib fractures did not correlate with the outcome measures, but the presence of bilateral rib fractures correlated with the outcome measures other than mortality. CONCLUSIONS: The number of rib fractures does not correlate with mortality or the length of stay in the intensive care unit in blunt trauma patients with severe thoracic injury. Mortality in these patients correlated with the degree of hypoperfusion (base excess) and coagulation abnormalities (tromboplastin time) on admission.

Traumatic deaths at hospital: analysis of preventability and lessons learned.

PURPOSE: The aim of the present study was to characterize traumatic deaths of major trauma patients occurring in a university trauma centre and to assess retrospectively the quality of given care by evaluating whether any of the deaths could be identified as potentially preventable. METHODS: All consecutive deaths of trauma patients between January 1, 2004 and December 31, 2008 in the Töölö Hospital Trauma Centre were retrospectively reviewed. The inclusion criterion was death of a trauma patient occurring during stay at hospital. Patients aged >65 years with an isolated proximal femoral fracture, burn patients, patients with isolated limb fracture other than femoral or tibial shaft fracture, and patients with isolated traumatic brain injuries were excluded as well as patients admitted more than 24 h after injury. RESULT: A total of 130 patients fulfilled the inclusion criteria. The autopsy reports were obtained for 103 of the cases (80.4 %). The majority of the patients were male, and the median age was 58 years (range 1-95 years). Blunt trauma was the most common type of injury. The most common injury mechanisms were fall from a higher level (31 %), fall from the level of the patient (21 %), and motor vehicle accident (17 %). Of the injuries not diagnosed before autopsy, the most common were liver lacerations, rib fractures, pulmonary contusions, sternum fractures, and blunt cardiac injuries. In our study population 12.5 % of the cases were considered potentially preventable. The reasons for preventability were inadequate treatment of coagulopathy, overuse of opioid medication, and loss of airway as well as failing to treat impending pneumonia and DVT. Trauma resuscitation was inadequate in 7.8 % of the cases. CONCLUSIONS: The most common error made was not recognising and treating traumatic coagulopathy adequately.

Angiographic embolization in the treatment of arterial pelvic hemorrhage: evaluation of prognostic mortality-related factors.

PURPOSE: The control of arterial bleeding associated with pelvic ring and acetabular fractures (PRAF) remains a challenge for emergency trauma care. The aim of the present study was to uncover early prognostic mortality-related factors in PRAF-related arterial bleedings treated with transcatheter angiographic embolization (TAE). METHODS: Forty-nine PRAF patients (46 pelvic ring and three acetabular fractures) with arterial pelvic bleeding controlled with TAE (within 24 h) were evaluated. RESULTS: All large arterial disruptions (n = 7) were seen in type C pelvic ring injuries. The 30-day mortality in large vessel (iliac artery) bleeding was higher (57 %) than in medium- or small-size artery bleeding (24 %). Overall 30-day mortality was 29 %. No statistically significant difference in the first laboratory values between the survivors and nonsurvivors was found. However, after excluding patients dying of head injuries (n = 5), a reasonable cut-off value was identified for the base excess (BE; lower than -10 mmol/l) obtained on admission. CONCLUSIONS: PRAF patients with exsanguinating bleeding from the large pelvic artery have the worst prognosis. Very low BE values (<-10.0 mmol/l) on admission for exsanguinating patients have a negative predictive value for survival, thus anticipating a poor outcome in bleeding controlled with TAE only and an increased risk of death. In critical cases, an aggressive bleeding control protocol prompts extraperitoneal pelvic packing prior to TAE. PRAF-related rupture of the external iliac artery is rare and indicates surgical techniques in controlling and restoring blood supply to the lower leg.

Accidental falls related to shovelling snow from rooftops: analysis of injuries in an extraordinary epidemic in southern Finland.

BACKGROUND AND AIMS: Exceptional amount of snow led to snow removal attempts from the rooftops resulting in a relative unique and extraordinary epidemic of accidental falls in winter of 2010. MATERIAL AND METHODS: The injury pattern, hospital care, surgical operations, and the total costs of the primary hospital stay of accidentally fallen patients treated in Helsinki University Hospital trauma unit were analyzed. RESULTS: Forty-six patients were admitted to hospital during the study period of three months. Majority of the patients were males (N = 43, 93%) with the average age of 52.9 years. Seven patients were admitted to ICU. The average length of primary hospital stay was 4.7 days with 0% mortality. Total amount of fractures was 65 (63%) of all 97 injuries. The most common injuries were fractures of upper and lower extremity, and spinal column. CONCLUSIONS: Preventing similar unnecessary epidemics of accidental falls in the future it is important to have professional opinion of the need of snow removal along with understanding of the risk of injury. Wearing appropriate safety equipments, and use professional help when necessary is advisable.

Severe pelvic fracture-related bleeding in pediatric patients: does it occur?

PURPOSE: Pediatric pelvic fractures are rare and less likely to cause hemodynamic instability than similar injuries in adult patients. The associated injuries are common, and they have a major impact on mortality. The aim of the present study was to evaluate the risk of life-threatening hemorrhage associated with unstable pelvic fractures in children. METHODS: We identified retrospectively all pediatric pelvic fractures (ring and acetabulum) treated at Helsinki University Central Hospital during a 10-year period (1998-2007). Stable A-type fractures (fractures not involving the pelvic ring) were excluded. All available pre- and in-hospital medical records were reviewed. The collected data consisted of patient characteristics, mechanisms of injury, vital signs, laboratory tests, care given, other injuries diagnosed, and the 30-day survival rate. RESULTS: There were 71 (40 males) pediatric patients (median age 14, range 1-16 years) with unstable pelvic fractures; 66 pelvic ring and 5 acetabulum fractures. The most common mechanism of injury was traffic accident (69%). Four patients had life-threatening bleeding. All had fracture of a mature pelvic ring, but the source of massive bleeding was pelvic ring fracture in only two patients (2.8% of all patients). No acetabulum fracture-related major pelvic bleeding was observed. One patient (age 16 years) required emergency surgery and angioembolization for pelvic bleeding. No life-threatening pelvic bleeding was seen among patients with immature bony pelvis. Pelvic ring fractures were surgically treated in 25 patients. Two patients died from head injuries (overall mortality 2.8%), but there were no bleeding-related deaths. CONCLUSIONS: We conclude that life-threatening bleeding from pelvic or acetabular fractures in pediatric patients is rare (2.8%), and does not contribute to the overall mortality.

Long-term outcome of a transglenoid suture technique for anterior shoulder instability in young adults.

We reviewed the outcome of arthroscopic stabilisation of anterior glenohumeral instability in young adults using the transglenoid suture technique. A questionnaire was sent to 455 consecutive patients who had undergone this procedure between 1992 and 2000. Of these, 312 patients (68.5%) with 313 affected shoulders and a mean age of 20 years (18 to 28) responded. Outcome was determined by the number of re-dislocations or, in patients who had not re-dislocated, by the disease-specific quality of life as measured by the Western Ontario Shoulder Instability index. During a mean follow-up of 6.4 years (1 to 14), 177 patients (56%) sustained a re-dislocation, including 70 who required a further operation. In 136 patients (44%) who reported neither re-dislocation nor re-operation, the index scores were good (median 90.4%; 28.9% to 100%). No significant peri- or pre-operative predictors of re-dislocation or re-operation were found. We found a high rate of re-dislocation after transglenoid suture repair in young, physically active patients.

Comparison of the effects of clozapine, chlorpromazine, and haloperidol on membrane lateral heterogeneity.

The interactions of three neuroleptic drugs, clozapine (CLZ), chlorpromazine (CPZ), and haloperidol (HPD) with phospholipids were compared using DSC and Langmuir balance. Main emphasis was on the drug-induced effects on the lateral organization of lipid mixtures of the saturated zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and the unsaturated acidic phosphatidylserine, brainPS. In multilamellar vesicles (MLV) phase separation was observed by DSC at X(PS)> or =0.05. All three drugs bound to these MLVs, abolishing the pretransition at X(drug)> or =0.03. The main transition temperature (T(m)) decreased almost linearly with increasing contents of the drugs, CLZ having the smallest effect. In distinction from the other two drugs, CLZ abolished the phase separation evident in the endotherms for DPPC/brainPS (X(PS)=0.05) MLVs. Compression isotherms of DPPC/brainPS/drug (X(PS)=X(drug)=0.05) monolayers revealed the neuroleptics to increase the average area/molecule, CLZ being the most effective. Penetration into brainPS monolayers showed strong interactions between the three drugs and this acidic phospholipid (in decreasing order CPZ>HPD>CLZ). Hydrophobic interactions demonstrated using neutral eggPC monolayers decreased in a different order, CLZ>CPZ>HPD. Fluorescence microscopy revealed domain morphology of DPPC/brainPS monolayers to be modulated by these drugs, increasing the gel-fluid domain boundary length in the phase coexistence region. To conclude, our data support the view that membrane-partitioning drugs could exert part of their effects by changing the lateral organization and thus also the functions of biomembranes.

Binding of novel peptide inhibitors of type IV collagenases to phospholipid membranes and use in liposome targeting to tumor cells in vitro.

We have recently described a novel cyclic peptide inhibitor CTTHWGFTLC (CTT) for matrix metalloproteinases (MMP)-2 and MMP-9, also called type IV collagenases or gelatinases (E. Koivunen et al., NAT: BIOTECHNOL:, 17: 768-774, 1999). As indicated by its amino acid composition, CTT is hydrophobic, and its partitioning into phospholipid films could be verified by the monolayer technique. Augmented fluorescence emission anisotropy (from 0.064 to 0.349) and reduced collisional quenching by I(-) of the Trp residue in CTT was evident in the presence of unilamellar phosphatidylcholine/phosphatidylethanolamine liposomes, revealing the association of CTT with the lipid bilayers. Gelatinases are potential targets of therapeutic intervention in cancer, and inhibitors of these enzymes can prevent tumor progression in animal models. CTT enhanced 3- to 4-fold the cellular uptake of liposome-encapsulated water-soluble fluorescent marker, rhodamine B by gelatinase-expressing cells. Gelatinase targeting seems to be essential, as modified peptides that were less potent gelatinase inhibitors were also less efficient in promoting the cellular uptake of liposomes. Augmented killing ( approximately 4-fold) of U937 leukemia and HT1080 sarcoma cells was obtained by the CTT-enhanced delivery of Adriamycin-containing liposomes, compared with control liposomes administered without the peptide. These results suggest a novel type of utility for small gelatinase inhibitors in targeted cancer therapy.

Binding of adriamycin to liposomes as a probe for membrane lateral organization.

A stopped-flow spectrofluorometer equipped with a rapid scanning emission monochromator was utilized to monitor the binding of adriamycin to phospholipid liposomes. The latter process is evident as a decrease in fluorescence emission from a trace amount of a pyrene-labeled phospholipid analog (PPDPG, 1-palmitoyl-2-[(6-pyren-1-yl)]decanoyl-sn-glycero-3-phospho-rac-++ +glyce rol) used as a donor for resonance energy transfer to adriamycin. For zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes, fluorescence decay was slow, with a half-time t1/2 of approximately 2 s. When the mole fraction of the acidic phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG), was increased to XPG >/= 0.04, the decay of fluorescence became double exponential, and an additional, significantly faster process with t1/2 in the range between 2 and 4 ms was observed. Subsequently, as XPG was increased further, the amplitude of the fast process increased, whereas the slower process was attenuated, its t1/2 increasing to 20 s. Increasing [NaCl] above 50 mM or [CaCl2] above 150 microM abolished the fast component, thus confirming this interaction to be electrostatic. The critical dependence of the fast component on XPG allows the use of this process to probe the organization of acidic phospholipids in liposomes. This was demonstrated with 1, 2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes incorporating PPDPG (XPPDPG = 0.03), i.e., conditions where XPG in fluid bilayers is below the required threshold yielding the fast component. In keeping with the presence of clusters of PPDPG, the fast component was observed for gel-state liposomes. At approximately 34 degreesC (i.e., 6 degrees below Tm), the slower fluorescence decay also appeared, and it was seen throughout the main phase transition region as well as in the liquid-crystalline state. The fluorescence decay behavior at temperatures below, above, and at the main phase transition temperature is interpreted in terms of thermal density fluctuations and an intermediate state between gel and liquid-crystalline states being involved in the phospholipid main phase transition. This is the first observation of a cluster constituted by acidic phospholipids controlling the membrane association of a drug.

Interactions of cyclosporin A with phospholipid membranes: effect of cholesterol.

Cyclosporin A (CsA) is a highly hydrophobic drug used to prevent graft rejection after organ transplantation. Interactions of CsA with phosphatidylcholine as well as with binary mixtures containing phosphatidylcholine and cholesterol were investigated by measuring the penetration of CsA into lipid monolayers at an air/water interface, by differential scanning calorimetry, and by imaging with fluorescence microscopy the effects of CsA on the lateral distribution of a fluorescent probe, 1-palmitoyl-2-(N-4-nitrobenz-2-oxa-1, 3-diazol)aminocaproyl-phosphocholine, in monolayers. Film penetration studies revealed the association of CsA with lipids to be a biphasic process. Cholesterol diminished the intercalation of CsA into the monolayer at surface pressures of >19 mN/m. CsA broadened the main transition of dimyristoylphosphatidylcholine (DMPC)/beta-cholesterol (10:1, mol/mol) multilamellar vesicles. The behavior of the transition enthalpy was more complex; the behavior of DMPC/beta-cholesterol multilamellar vesicles in the XCsA of 0 to 0.1 showed at most ratios a increase, but several well distinct dips were observed. The results are interpreted in terms of regular structures in tertiary alloy. Influence of CsA on lateral organization could be verified for lipid domains observed by fluorescence microscopy of lipid monolayers. More specifically, CsA altered the distribution of 1-palmitoyl-2-(N-4-nitrobenz-2-oxa-1, 3-diazol)aminocaproyl-phosphocholine in a dipalmitoylphosphatidylcholine film and in DPPC/beta-cholesterol (88:10, mol/mol) mixtures in a manner that suggests that CsA partitions into the boundaries between fluid and gel domains. To our knowledge, this constitutes the first demonstration of a change in lipid domain morphology to be induced by a drug molecule.