SKIN DOSE, EFFECTIVE DOSE AND RELATED RISK IN TRANSCATHETER AORTIC VALVE IMPLANTATION (TAVI) PROCEDURES: IS THE CANCER RISK ACCEPTABLE FOR YOUNGER PATIENTS?

The aim of this study was to estimate conversion coefficients for maximum entrance skin dose (MESD) and effective dose (E) for patients undergoing transcatheter aortic valve implantation (TAVI) and to evaluate the risk of exposure-induced cancer death (REID) for prospectively younger patients. Effective doses and risks were estimated for 22 patients using PCXMC whereas MESDs were estimated for a sub-group of 15 patients using Gafchromic film. The estimated conversion coefficients for skin dose [CCS = MESD/dose-area product (DAP)] and E (CCE = E/DAP) were 9.7±1.5 and 0.24±0.02 mSv/Gy cm(2), respectively. The REID ranged from 1:9900 to 1:1400 and by decreasing the age of examination to 40-50 y of age, the REID increased with a factor of 2 for females and 1.5 for males. The organ at risk was the lung. Currently, the patient population is elderly with radiation-induced skin injuries as the main risk. The risk of cancer induction should additionally be considered if younger patient populations are to be treated.

APR-246 overcomes resistance to cisplatin and doxorubicin in ovarian cancer cells.

Two main causes of platinum resistance are mutation in the tumor suppressor gene TP53 and drug-induced increase in intracellular glutathione concentration. Mutations in TP53 occur in about 50% of human tumors. APR-246 (PRIMA-1(MET)) is the first clinical-stage compound that reactivates mutant p53 and induces apoptosis. APR-246 is a prodrug that is converted to the active compound methylene quinuclidinone (MQ), a Michael acceptor that binds to cysteine residues in mutant p53 and restores its wild-type conformation. Here, we show that MQ also binds to cysteine in glutathione, thus decreasing intracellular free glutathione concentration. We also show that treatment with APR-246 completely restores the cisplatin and doxorubicin sensitivity to p53-mutant drug-resistant ovarian cancer cells. We propose that this unique ability of APR-246/MQ to bind to cysteines in both mutant p53 and glutathione has a key role in the resensitization as well as in the outstanding synergistic effects observed with APR-246 in combination with platinum compounds in ovarian cancer cell lines and primary cancer cells. However, MQ binding to cysteines in other targets, for example, thioredoxin reductase, may contribute as well. Strong synergy was also observed with the DNA-damaging drugs doxorubicin and gemcitabine, while additive effects were found with the taxane docetaxel. Our results provide a strong rationale for the ongoing clinical study with APR-246 in combination with platinum-based therapy in patients with p53-mutant recurrent high-grade serous (HGS) ovarian cancer. More than 96% of these patients carry TP53 mutations. Combined treatment with APR-246 and platinum or other DNA-damaging drugs could allow dramatically improved therapy of a wide range of therapy refractory p53 mutant tumors.

Effective dose conversion factors in paediatric interventional cardiology.

Conversion factors for effective dose (CF(E) = effective dose/dose-area product (mSv (Gy cm2)(-1)) in paediatric interventional cardiology were estimated retrospectively for 249 patients using the dose-area product (DAP), irradiation geometry, exposure parameters and tissue-weighting factors (TWFs) from the International Commission on Radiological Protection (ICRP) 60. Two methods for estimating the conversion factors, which differed in the description of the irradiation geometry, were evaluated. The effective doses obtained with the two methods were almost identical. The results showed that irradiation geometry had no significant impact on the CF(E), and a single factor was defined for both diagnostic and interventional examinations. In addition, the effect of the new tissue-weighting factor for breast tissue (TWF(b)) given in ICRP 103 on the effective dose was assessed. The CF(E) was 3.7+/-0.2 mSv (Gy cm2)(-1) (neonate), 1.9+/-0.2 mSv (Gy cm2)(-1) (1 year), 1.0+/-0.1 mSv (Gy cm2)(-1) (5 years), 0.6+/-0.1 mSv (Gy cm2)(-1) (10 years) and 0.4+/-0.1 mSv (Gy cm2)(-1) (15 years). Applying these CFs to the individual DAP values of each patient yielded mean effective doses of 13.0 mSv (neonate), 8.6 mSv (1 year), 6.4 mSv (5 years), 8.6 mSv (10 years) and 12.7 mSv (15 years). The maximum estimated skin dose (15 patients) did not exceed 60 mGy. With the new ICRP value for TWF(b), increases in the CFs in the order of 10-30%, and in the effective dose of 10-20%, were indicated. The results indicated that the effective dose in paediatric interventional cardiology is of much greater concern than the skin dose. Furthermore, age-dependent CF(E) values are required so as not to underestimate the doses to very young patients.

Temperature variation in newborn babies: importance of physical contact with the mother.

BACKGROUND: Hypothermia is a major cause of deterioration and death in the neonatal period. Temperature deviations are key signs of illness. OBJECTIVE: To determine normal patterns of temperature variation in newborn babies and the influence of external factors. METHODS: Abdominal and foot skin temperature were continuously recorded in 27 healthy full term babies during the first two days of life and related to the care situation-that is, whether the baby was with the mother or in its cot. The recordings were made using no wires to avoid interference with the care of the neonate. Ambient temperature was close to 23 degrees C during the study period. RESULTS: Mean rectal and abdominal and foot skin temperature were lower on day 1 than day 2. The foot skin temperature was directly related to the care situation, being significantly higher when the baby was with the mother. The abdominal skin temperature was much less influenced by external factors. When the neonates were with their mothers, the mean difference between rectal temperature and abdominal skin temperature was 0.2 degrees C compared with a mean difference between rectal temperature and foot skin temperature of 1.5 degrees C, indicating a positive heat balance. In the cot the corresponding temperature differences were 0.7 degrees C and 7.5 degrees C. A temperature difference between rectal and foot skin temperature of 7-8 degrees C indicates a heat loss close to the maximum for which a neonate can compensate (about 70 W/m2). CONCLUSION: This study emphasises the importance of close physical contact with the mothers for temperature regulation during the first few postnatal days.

Skin dose alarm levels in cardiac angiography procedures: is a single DAP value sufficient?

Maximum estimated skin doses to patients undergoing coronary angiography procedures were obtained using radiographic slow film and diode dosemeters. Conversion factors of maximum entrance skin dose versus dose-area product (MESD/DAP) for diagnostic (coronary angiography (CA); 20 patients; 2 operators) and interventional procedures (percutaneous transluminal coronary angiography (PTCA); 10 patients; 1 operator) were 4.3 (mean value of 10 CA; operator A), 3.5 (mean value of 10 CA; operator B) and 9.7 (mean value of 10 PTCA; operator B) mGy(Gycm2)(-1), respectively. The results emphasise a need for both operator- and procedure-specific conversion factors. Compared with a single, global factor for all cardiac procedures and/or operators that is commonly applied today, such a refinement is expected to improve the accuracy in skin dose estimations from these procedures. Consequently, reference DAP values used in the clinic to define patients who could suffer from a radiation induced skin injury following a cardiac procedure, should be defined for each operator/procedure. The film technique was found to be superior to the diode in defining conversion factors in this study, and allowed for a rapid and accurate estimation of MESD for each patient. With appropriate positioning of the diode, a combined film/diode technique has a potential use in the training of new angiography operators. The patient body mass index (BMI) value was a good indicator of the variation in average lung dose (critical organ) between patients. The highest lung dose/DAP value was obtained for normal sized patients (BMI: 19-26), and was close to 1.5 mGy(Gycm2)(-1) with both CA and PTCA procedures.

Aspects of MR image distortions in radiotherapy treatment planning.

BACKGROUND: Registration of computed tomography (CT) and magnetic resonance (MR) images are commonly performed to define the different target regions used in radiotherapy treatment planning (RTTP). The accuracy of target definition will then depend on the spatial accuracy of the CT and MR data, and on the technique used to register the images. CT images are usually regarded as geometrically correct, while MR images are known to suffer from geometric distortion. The aim of this paper is to discuss the possible impact of MR image distortions in the radiotherapy treatment planning process. METHODS: The origin, magnitude, and relative impact of the different sources of geometric distortions that affect the MR image data at different magnetic fields and for different acquisition settings are described. Techniques for distortion correction are reviewed, and their limitations are outlined. The sensitivity of image registration techniques to the presence of geometric distortions in the MR data is discussed. Finally, an overview of image registration techniques used and results obtained in clinical radiotherapy treatment planning applications is given. RESULTS: Spatial distortions in MR images vary with field strength and with the image acquisition protocol. The spatial accuracy generally decreases with distance from the magnet isocenter. Distortion correction techniques based on phantom evaluations cannot adequately model patient-induced distortions. CONCLUSION: Image protocols with high gradient bandwidths should be used to reduce the spatial distortions in MR images. Correction techniques based only on phantom measurements could be sufficient at low magnetic fields, while at higher fields additional corrections of patient-related distortions might be needed. Registration techniques based on matching of Landmark points located far from the magnet isocenter are especially prone to MR distortions.

Treatment of snoring and obstructive sleep apnea with a mandibular protruding device: an open-label study.

The study objectives were to describe the changes in signs and symptoms of obstructive sleep apnea (OSA) and snoring using a mandibular protruding device (MPD) and to define the group of responders. The design of the study was a nonrandomized, open-labeled, prospective clinical study with a duration of 6 months. The setting was a hospital sleep laboratory and an ear, nose, and throat and dental outpatient clinic. Patients included 35 individuals treated: 22 with a diagnosis of OSA and 13 who snored without apnea. The intervention before MPD prescription entailed a medical examination, a one-night somnographic registration, a questionnaire, and a clinical jaw function examination. All procedures were iterated at the 6-month follow-up. When the patients used the MPD, the subjective symptoms decreased significantly (p < 0.001). Twenty-four of the 35 patients were classified as responders, i.e., reduced their symptoms > or = 50%. In the groups of OSA patients, the mean peak intensity of the snoring sound decreased from 71.6 dB to 62.0 dB (p < 0.001) and in the group of snorers, from 63.5 dB to 57.5 dB (p < 0.05). Eighteen of the 22 OSA patients decreased their ODI values by > or = 50% (responders). The mean ODI decreased from 15.4 to 3.5 (p < 0.001) and the blood oxygen saturation, SaO(2) nadir, increased from mean 81.9 to 85.7 (n.s.). Most patients with tongue base hyperplasia were classified as responders to the MPD treatment. In conclusion, a 6-month perspective shows that the MPD could be an effective treatment in reducing signs and symptoms of OSA and/or snoring, the compliance was acceptable and only minor adverse events occurred.

Noise-induced aspartate and glutamate efflux in the guinea pig cochlea and hearing loss.

Aspartate and glutamate were monitored in the scala tympani of the guinea pig cochlea using in vivo microdialysis before and during noise exposure. Moderate level broad band noise [105 dB sound pressure level (SPL), 30 min] neither altered the levels of aspartate or glutamate, nor auditory brainstem response (ABR) thresholds. High level noise exposure (135 dB SPL, 30 min) caused a large increase in aspartate (330%), a smaller increase in glutamate (150%), and a permanent ABR threshold shift of 60-75 dB between 2.0 and 12.5 kHz. Morphological analysis of the cochlea revealed a collapse of supporting structures, swelling of the afferent dendrites under the inner hair cells, and outer hair cell loss. Pretreatment with the NMDA antagonist, MK 801 (1 mg/kg body weight, i.p.) 1 h before noise exposure protected the afferent dendrites from swelling but did not protect the collapse of supporting structures, outer hair cell loss, or auditory thresholds. In conclusion, the noise-induced increase in aspartate and glutamate release in the cochlea and the protective effect of NMDA antagonism suggest that these two neurotransmitters are involved in noise-induced hearing loss.

Characterization of hearing in an X,0 'Turner mouse'.

Turner's syndrome is due to total (45,X) or partial (mosaicism) loss of one X-chromosome. The main features are short stature, ovarian dysgenesis with no estrogen production and infertility. In addition to ear and hearing disorders, middle ear problems including acute/serous otitis media and chronic middle ear disease are frequent. Sensorineural hearing loss is often seen with a dip in the mid-frequencies and also an early high frequency loss. In this study, middle-and inner-ear pathology was characterized using physiological and morphological techniques in a 'Turner mouse' that has been generated with the chromosomal aberration X,0. Otitis media was found in some of these X,0 animals, a symptom that is seldom found in control animals. The auditory brainstem responses (ABR) of the Turner mouse showed a progressive hearing loss in the high frequency region that exceeded the normal age-related hearing loss of control mice and increased latencies of the first ABR wave. Outer hair cell loss was apparent in the cochlear basal turn of Turner mice. Decreases in the amplitude of distortion product otoacoustic emissions were correlated with the loss of ABR threshold sensitivity. These results indicate that hearing problems in the Turner mouse seems to be of cochlear origin with an eighth nerve component. This Turner mouse model appears to have ear and hearing problems quite similar to humans and can therefore be used as a model to determine the auditory pathology underlying this syndrome.

Effects of trabecular bone on marrow relaxation in the tibia.

The effects of bone on marrow relaxation in the trabecular volume of the most proximal 3 cm in the left tibia were studied with a RF-spoiled gradient echo MRI protocol on a 1.0 T MR unit. The MR measurements were performed on six healthy volunteers, and repeated within one month in order to assess the precision of the method. In the same subjects, the area bone mineral density (BMD, g/cm2) was measured at the left proximal femur using dual-energy X-ray absorptiometry. The calcaneus of the same side was examined with quantitative ultrasound. The marrow T2* relaxation deviated from a mono-exponential decay, and resembled the decay of subcutaneous fat. The shape of the relaxation curve reflected the presence of several spectral components in bone marrow, and was further influenced by the amount and structure of the surrounding trabecular bone. The bone marrow decays showed substantially reduced inter-subject variability after normalisation of the marrow data fit parameters to corresponding values for s.c. fat. This suggests the use of an internal adipose tissue reference in order to correct for diet-related variations of marrow T2* estimates. The mean relative precision of the MR measurements was between 5% and 10% depending on the data fit model. Moderate-to-strong correlations between DXA BMD indices in the proximal femur and MR parameters were found (r(max)=-0.96; p < 0.01), while ultrasound-derived measures of bone strength measured on the calcaneus demonstrated significantly weaker correlations to the MR parameters (r(max)=-0.78; p > 0.05). The method employed in this study showed reasonable precision and a moderate to good correlation compared to other bone parameters derived at the same extremity, and is a promising tool for the use on patients.

Medial olivocochlear efferent terminals are protected by sound conditioning.

Synaptophysin immunoreactivity was used as a marker for the olivocochlear efferent system that innervates the outer hair cells of the cochlea. An intense noise exposure at either 6.3 kHz or 1.0 kHz caused a significant reduction in anti-synaptophysin immunoreactivity within the 8-6 mm or 14-11 mm distance from the round window, respectively. In the region of the main lesion, the reduction in synaptophysin immunoreactivity for both the 6.3 and 1.0 kHz exposures correlated well with outer hair cell loss. In regions peripheral to the main lesion, some remnants of efferent nerve endings could remain even when their associated outer hair cells were missing. Pre-treatment with a low level sound conditioner (either at 6.3 tone or 1.0 kHz) effectively reduced the efferent and outer hair cell pathology induced by the 6.3 and 1.0 kHz intense noise exposures, respectively. The results demonstrate the feasibility of using anti-synaptophysin immunoreactivity as an effective means of quantifying pathological alterations to the medial cochlear efferent terminals throughout the cochlea. Furthermore, the results show that sound conditioning significantly reduces damage to the efferent terminals.

Verification of single beam treatment planning using a ferrous dosimeter gel and MRI (FeMRI).

A method for analysing and comparing treatment planning system (TPS) data and ferrous dosimeter gel measurements evaluated with MRI (FeMRI) was developed, including image processing to final absorbed dose images. Measurements were analysed according to this method and FeMRI data were thereby compared with the TPS-calculated dose distribution. For photons, differences between FeMRI- and TPS dose data were mainly within +/- 2%. Minor shortcomings found in both the FeMRI system and the TPS are explained and discussed. For electron beams, there was an overall good agreement. It was found that the TPS underestimates the lateral scattering dose outside the primary beam, but the reported dose difference corresponds to a small spatial deviation (less than 2 mm). It is important to consider this single beam data comparison when the method is extended to more complicated situations, for example when using several beams.

[Alcohol-induced cognitive impairment is reversible. Neuropsychological tests but not MRT show improvement after abstinence]. / Alkoholinducerad kognitiv påverkan kan gå i regress. Neuropsykologiska test men inte MRT visar förbättring efter abstinens.

Of alcoholic patients who underwent MRI (magnetic resonance imaging) of the brain and neuropsychological tests shortly after discontinuation of heavy drinking, a subgroup underwent repeat MRI scans and neuropsychological assessment one year later. The reduction in drinking habits was associated with cognitive improvement but no significant difference in MRI variables including T1-relaxation time.

Improvements in absorbed dose measurements for external radiation therapy using ferrous dosimeter gel and MR imaging (FeMRI).

A ferrous gel, based on ferrous (Fe) sulphate and agarose, was used with a clinical magnetic resonance imaging (MRI) scanner to obtain relative dose distribution data from therapeutic photon and electron beams. The FeMRI gel was scanned using a new MRI acquisition protocol optimized for T1 measurements. Thorough comparisons with silicon semiconductor detector and ionization chamber measurements, as well as with Monte Carlo calculations, were performed in order to quantify the improvements obtained using FeMRI for dose estimations. Most of the relative doses measured with FeMRI were within 2% of the doses measured with other methods. The larger discrepancies (2-4%) found at shallow depths are discussed. The uncertainty in relative dose measurements using FeMRI was significantly improved compared with previously reported results (5-10%, one standard deviation, 1 SD), and is today between 1.6% and 3.3% (depending on dose level, 2 SD). This corresponds to an improvement in the minimum detectable dose (3 SD above background) from approximately 2 Gy to better than 0.6 Gy. The results obtained in this study emphasize the importance of obtaining basic FeMRI dose data before the method is extended to complicated treatment regimes.

Reducing noise damage by using a mid-frequency sound conditioning stimulus.

Sound conditioning guinea pigs to a 6.3 kHz tone at 78 dB SPL for either 13 or 24 days provides significant physiological (auditory brain stem responses, ABR; and distortion product otoacoustic emissions, DPOAE) and morphological (cochleograms) protection against a subsequent traumatic exposure (6.3 kHz, 100 dB SPL for 24 h) delivered 2 h after sound conditioning. Threshold shifts (ABR, DPOAE) were significantly reduced and the degree of hair cell loss was minimal. When a 1 week pause was given between the end of the sound conditioning and the traumatic exposure, protection was still observed, but to a lesser degree. These findings demonstrate that mid-frequency sound conditioning protects against noise trauma and that the protective effect is maintained for at least 1 week.

Dosimeter gel and MR imaging for verification of calculated dose distributions in clinical radiation therapy.

A dosimeter gel, based on an agarose gel infused with a ferrous sulphate solution and evaluated in a magnetic resonance scanner, was used for complete verification of calculated dose distributions. Two standard treatment procedures, treatment of cancer in the urinary bladder and treatment of breast cancer after modified radical mastectomy, were examined using pixel-by-pixel and dose volume histogram comparison. The dose distributions calculated with the dose planning system was in very good agreement with the measured ones. However, in the case of the more complicated breast cancer treatment, some discrepancies were found, mainly at the beam abutment region. This may be explained by field displacements errors and by a small limitation of the dose planning utilising small electron beams in this region. The dosimeter gel system have proven to be a useful tool for dosimetry in clinical radiation therapy applications.

Magnetic resonance imaging of lower extremity muscles and isokinetic strength in foot dorsiflexors in patients with prior polio.

The thigh and lower leg of six patients with prior polio were examined using magnetic resonance imaging (MRI), and the strength of their weak foot dorsiflexors was measured isokinetically. Spinecho images of the lower extremities were visually evaluated on a semi-quantitative four-point scale, and T1 and T2 relaxation times of the lower leg anterior compartment were analysed. There were prominent MRI signs of randomly distributed muscle degeneration. The high signal intensity changes in the affected muscles on T1-weighted images and T1 and T2 values indicated replacement of muscle fibres with fat and the accumulation of tissue water, respectively. MRI findings were compared with isokinetic strength in foot dorsiflexor muscles. Foot dorsiflexor peak torque values at 30 deg/s ranged from 6 to 29 Nm. There was no significant correlation between MRI visual scoring, T1 and T2 relaxation times and peak torque values at 30 deg/s. However, the most severe MRI changes with visual scoring and T2 relaxation times were observed in the patients with the most pronounced muscle weakness.

Morphological and functional preservation of the outer hair cells from noise trauma by sound conditioning.

Guinea pigs were sound conditioned to a low-level, long-term pure tone stimulus (1 kHz, 81 dB SPL, 24 days) before exposure to a traumatic noise (1 kHz, 105 dB SPL, 72 h). Auditory brainstem response thresholds and distortion product otoacoustic emissions were obtained at selected frequencies before sound conditioning and at day 1, 5, 10, and 15 during sound conditioning as well as on the final 24th day. Auditory brainstem responses at 1 and 2 kHz were not affected at any time during sound conditioning. The amplitude of the distortion product otoacoustic emission showed minor alterations (below 10 dB) at selected frequencies only during the initial stages (day 1, 5, and 10) of sound conditioning in some, but not all the animals. Distortion product amplitudes were similar to control values on the 15th and 24th day of conditioning. Surface preparations of the organ of Corti did not reveal any significant hair cell loss induced by sound conditioning. The effect of a traumatic exposure (1 kHz, 105 dB SPL, 72 h) on a control group and a sound conditioned group was determined. The distortion product otoacoustic emission amplitude measured 4 weeks after the cessation of the traumatic exposure revealed significant differences. The amplitude of the distortion product otoacoustic emission for the control group was depressed at all tested frequencies and at lower frequencies (2.8, 2.1, and 1.75 kHz) the emissions did not show an increase in response to increases in intensity, of the primaries. The sound conditioned group showed increases in distortion product amplitude with increases in the intensity of the primaries for all tested frequencies and statistically significant reductions from the pre-exposure values were not found. Surface preparations from the control group indicated that the traumatic noise exposure affected nearly 100% of the outer hair cells around the 14 mm distance from the round window. The sound conditioned group showed a significantly less (50%) outer hair cell loss than the control group. The sound conditioned group illustrated an altered pattern of damage after subsequent noise trauma. There were two distinct regions of outer hair cell loss, one being around the 16 mm distance and the other around the 12 mm distance from the round window. These results imply that the intrinsic properties of the outer hair cells and/or the organ of Corti have been altered by sound conditioning.

Distribution of muscle degeneration in Welander distal myopathy--a magnetic resonance imaging and muscle biopsy study.

Seven patients with Welander distal myopathy were subjected to magnetic resonance imaging (MRI) of the lower extremity, and muscle biopsies of the tibialis anterior, soleus and vastus lateralis muscles. MRI revealed abnormalities in both the anterior and posterior compartments of the lower leg in three of the patients, and in only the posterior compartment in the rest of the patients. No MRI abnormalities were found in either the proximal muscles of the leg or in the peroneal or posterior tibial muscle groups. Affected muscles had T1- and T2-values indicating a replacement of muscle fibres with fat tissue. Muscle biopsies showed pathological changes varying from slight to severe in tibialis anterior and soleus muscles in all patients. No muscle fibre abnormalities were seen in the vastus lateralis muscle in any of the patients. In accordance with earlier reports from patients with Welander distal myopathy, there was muscle degeneration of tibialis anterior muscles corresponding to the weakness of dorsal extension of the feet, but also degeneration in the muscles of the posterior compartment. The patients did not, however, show any clinical signs of weakness related to posterior muscle groups. There is no evidence of involvement of proximal muscles of the leg clinically, with MRI or in muscle biopsies.

Phase equilibria and formation of vesicles of dioleoylphosphatidylcholine in glycerol/water mixtures.

The lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) forms a lamellar liquid crystalline phase (L alpha) in arbitrary mixtures of glycerol and water. The phase has been characterized by means of X-ray diffraction, 31P-NMR spectroscopy and differential scanning calorimetry (DSC). In the L alpha state, and for DOPC concentrations greater than 50% (w/w), the thickness of the lipid bilayer decreases, while the area of the polar head group increases with increasing glycerol concentration. The phase transition from gel to L alpha state occurs in the range of 240 to 260 K. Contrary to a previous (McDaniel, R.V., McIntosh, T.J. and Simon, S.A. (1983) Biochim. Biophys. Acta 731, 97) study of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) we find that in the gel state, the thickness of the DOPC lipid bilayer is greater than that in the L alpha state. This suggests that in the gel state, the lipid acyl chains of DOPC are in extended configuration. The lamellar phase reaches its maximum swelling at about 50% (w/w) of DOPC. At lower DOPC concentrations a two-phase system is formed where the lamellar phase exists in equilibrium with excess of solvent. Unilamellar vesicles can be prepared from a diluted suspension of the lamellar phase either by using the sonicator or extruder technique. We show this by means of 31P-NMR, EPR and fluorescence spectroscopy. The mean radius of the vesicles, prepared by a sonicator, has been determined at different glycerol/water mixtures. It is found to decrease continuously from 100 A at 100% water to a minimum of 75 A at about 50% water in the solvent mixture. By further decreasing the water content in the solution, the radius rapidly increases, and a mean radius of 450 A is estimated at a water content of 10%. The rotational relaxation times of a fluorescent probe and two EPR spin probes, solubilized in DOPC vesicles, have been measured at different glycerol/water mixtures. It is found that the rotational rates are always much slower in the systems containing glycerol.