Comparison of meniscal T1rho- and T2*-relaxation times in professional female volleyball players and healthy controls using 3T MRI: A pilot study.

PURPOSE: Comparison of meniscal T1rho- and T2*-relaxation times in professional female volleyball players and healthy controls to determine if relaxation times are prolonged in athletes due to compositional meniscal alterations based on extensive and repetitive joint loading. METHODS: The right knee of 20 asymptomatic professional female volleyball players and 20 female controls were examined at 3T MRI. T1rho- and T2*-measurements were performed in sagittal orientation. For quantitative measurements, two readers independently defined two consecutive central slices with the greatest area of the anterior and posterior horn of the lateral (AHLAT; PHLAT) and medial meniscus (AHMED; PHMED). Both readers repeated measurements after a six-week interval on the original MR images. Statistical analysis included intraclass correlation coefficient (ICC), Wilcoxon signed-rank-, Shapiro-Wilk- & Kolmogorov-Smirnov- and Mann-Whitney U-tests. RESULTS: Mean T1rho-relaxation times in the PHMED were significantly prolonged in professional female volleyball players when compared to controls (24.2 ± 4.0 vs 21.1 ± 2.6 ms; p < 0.005). There were no significant differences for the remaining three meniscal horns. T2*-relaxation times revealed no significant differences between athletes and controls. Prolonged T1rho-relaxation times in the PHMED of female volleyball players did not correlate with significant change in T2*-relaxation times within all meniscal subregions. Reproducibility levels were excellent in all segments (Interobserver-ICC: 0.93-0.97 and intraobserver-ICC: 0.97-0.99). CONCLUSION: T1rho-relaxation times were significantly increased in the PHMED of female volleyball players, potentially indicating a predilection to early degenerative meniscal changes. T1rho may serve as a sensitive biomarker at detecting early compositional meniscal alterations in athletes.

Noise reduction angiographic imaging technology reduces radiation dose during bronchial artery embolization.

PURPOSE: Comparison of radiation doses in patients undergoing angiographic bronchial artery embolization (BAE) before and after a noise reduction imaging technology upgrade. METHODS: We performed a retrospective study of 70 patients undergoing BAE. Procedures were performed before (n=32) and after (n=38) the technology upgrade containing additional filters and improved image-processing. Cumulative air kerma (AK), cumulative dose area product (DAP), number of exposure frames, total fluoroscopy time and amount of contrast agent were recorded. Mean values were calculated and compared using two-tailed t-tests. DSA image quality was assessed independently by two blinded readers and compared using the Wilcoxon signed-rank test. RESULTS: Using the new technology resulted in a significant reduction of 59% in DAP (149.2 (103.1-279.1) vs. 54.8 (38.2-100.7) Gy*cm2, p<0.001) and a significant reduction of 60% for AK (1.3 (0.6-1.9) vs. 0.5 (0.3-0.9) Gy, p<0.001) in comparison to procedures before the upgrade. There was no significant difference between the number of exposure frames in both groups (251±181 vs. 254±133 frames, p=0.07), time of fluoroscopy (28.8 (18.5-50.4) vs. 28.1 (23.3-38.7) min, p=0.73), or the amount of contrast agent used (139.5±70.8 vs. 163.1±63.1ml, p=0.11). No significant difference regarding image quality could be detected (3 (2,3) vs. 3 (2-4), p=0.64). CONCLUSIONS: The new angiographic noise reduction technology significantly decreases the radiation dose during bronchial artery embolization without compromising image quality or increasing time of fluoroscopy or contrast volume.

Radiation dose reduction during transjugular intrahepatic portosystemic shunt implantation using a new imaging technology.

OBJECTIVE: To compare patient radiation dose in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) implantation before and after an imaging-processing technology upgrade. METHODS: In our retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), total fluoroscopy time and contrast agent were collected from an age- and BMI-matched collective of 108 patients undergoing TIPS implantation. 54 procedures were performed before and 54 after the technology upgrade. Mean values were calculated and compared using two-tailed t-tests. Two blinded, independent readers assessed DSA image quality using a four-rank likert scale and the Wilcoxcon test. RESULTS: The new technology demonstrated a significant reduction of 57% of mean DAP (402.8 vs. 173.3Gycm2, p<0.001) and a significant reduction of 58% of mean AK (1.7 vs. 0.7Gy, p<0.001) compared to the precursor technology. Time of fluoroscopy (26.4 vs. 27.8min, p=0.45) and amount of contrast agent (109.4 vs. 114.9ml, p=0.62) did not differ significantly between the two groups. The DSA image quality of the new technology was not inferior (2.66 vs. 2.77, p=0.56). CONCLUSIONS: In our study the new imaging technology halved radiation dose in patients undergoing TIPS maintaining sufficient image quality without a significant increase in radiation time or contrast consumption.

Subthreshold diode micropulse panretinal photocoagulation for proliferative diabetic retinopathy.

PURPOSE: To report the visual acuity and clinical outcomes of a pilot study of subthreshold diode micropulse (SDM) panretinal photocoagulation (PRP) for treatment of diabetic retinopathy. METHODS: A retrospective chart review of all patients undergoing PRP for diabetic retinopathy between April 2000 and February 2003 was performed. Treated conditions ranged from severe non-proliferative to severe proliferative diabetic retinopathy. An SDM PRP protocol designed to avoid detectable laser lesions was employed. Treatment failure end points included the development of vitreous haemorrhage or the performance of vitrectomy. RESULTS: Ninety-nine eyes of 63 patients undergoing SDM PRP were identified. Median follow-up was 1.0 year (range of 0.3-2.7 years). Treatment sessions per eye ranged from 1 to 6 (with a median of two sessions per eye). Overall visual acuity remained unchanged. The probability of treatment failure end points at 12 months post-treatment was 12.5% for vitreous haemorrhage and 14.6% for vitrectomy (from Kaplan-Meier survival analysis). Age, sex, diabetes type, and baseline retinopathy status were not significantly associated with the risk of either failure event. No treatment complications were observed. No eye demonstrated any laser lesion detectable clinically or by fluorescein angiography postoperatively. CONCLUSION: SDM pan retinal photocoagulation minimized retinal damage and treatment complications in the management of high-risk non proliferative and proliferative diabetic retinopathy. Visual loss was prevented with a low rate of vitreous haemorrhage and vitrectomy postoperatively. Further study of the safety, efficacy, and optimal treatment parameters of SDM pan retinal photocoagulation for diabetic retinopathy is warranted.

Discrimination of suballeles present at the TNFd microsatellite locus using induced heteroduplex analysis.

Polymorphism at the TNFd locus has been implicated in a number of disease association studies. The TNFd locus consists of three regions of (GA)(n) repeats separated by an imperfect repeat of two guanine bases. TNFd alleles are genotyped by the number of repeats in the first (GA)(n) repeat region, and until now the second repeat region had been thought to be nonpolymorphic. We report the existence of suballeles present within the TNFd microsatellite locus, detected using induced heteroduplex generator (IHG) technology. These alleles cannot be detected using conventional typing strategies as they represent altered distribution of the (GA)(n) repeats or sequence variation within the repeat. The suballeles affect the frequencies of the conventional d3 and d4 alleles leading to significantly altered allele frequencies. Some studies have associated the d3 and d4 alleles with disease outcome. We re-analysed one such study cohort using IHG technology and demonstrated a high proportion of incorrectly assigned TNFd3 alleles.

A novel polymorphism in the human interleukin-13 (IL-13) promoter.

Using PCR-SSCP and automated nucleotide sequencing we have identified a novel single nucleotide C --> T polymorphism in the human IL-13 promoter, at position -1055 relative to the transcription start site. Allele frequency analysis in a population of normal cord blood donors indicated frequencies of 0.833 (C) and 0. 167 (T).

Effects of hydration, ion release, and excluded volume on the melting of triplex and duplex DNA.

The stability of DNA duplex and triplex structures not only depends on molecular forces such as base pairing or tripling or electrostatic interactions but also is sensitive to its aqueous environment. This paper presents data on the melting of Escherichia coli and poly(dA).poly(dT) duplex DNA and on the poly(dT).poly(dA). poly(dT) triplex in a variety of media to assess the contributions from the osmotic status and salt content of the media. The effects of volume exclusion on the stability of the DNA structures are also studied. From thermal transition measurements in the presence of low-molecular weight osmotic stressors, the number of water molecules released upon melting is found to be four waters per base pair for duplex melting and one water for the conversion of triplex to single-strand and duplex. The effects of Na+ counterion binding are also determined in ethylene glycol solutions so that the variation of counterion binding with water activity is evaluated. The data show that there is a modest decrease in the extent of counterion binding for both duplex and triplex as water activity decreases. Finally, using larger polyethylene glycol cosolutes, the effects on melting of volume exclusion by the solutes are assessed, and the results correlated with simple geometric models for the excluded volume. These results point out that DNA stability is sensitive to important conditions in the environment of the duplex or triplex, and thus, conformation and reactivity can be influenced by these solution conditions.

Thermodynamics of transfer of cholesterol from gel to fluid phases of phospholipid bilayers.

The partitioning of cholesterol between gel and fluid phases of model membrane bilayers has been studied by differential scanning calorimetry. The partition coefficients and thermodynamics of transfer between phases of dimyristoyl-, dipalmitoyl-, distearoyl- and diarachidoylphosphatidylcholines were determined using a regular solution model for the partitioning process. The partition coefficient, which is the ratio of cholesterol in fluid to gel phase lipid, varies from 2.3 to 8.4 as the acyl chain length increases from the C14 to the C20 bilayer and determined at the phase transition temperature. The enthalpies of transfer increase from -46 to +32 kcal/mol as the chain length increases, and there is a compensating increase in the entropy of transfer. The results are interpreted in terms of a disruption of gel phase lipid by the cholesterol, which for the thinner bilayers is increased because the cholesterol molecule spans across the two leafs of the bilayer. At bilayer thicknesses between 18 and 19 carbons, the cholesterol can fit into one-half of the gel phase bilayer, and the enthalpy becomes positive, suggesting less disruption in the gel phase relative to the thinner bilayers. The data support the interpretation that cholesterol does mediate fluidity by acting to disrupt gel domains of lipid.

Thermodynamics of transfer of indocarbocyanines from gel to fluid phases of phospholipid bilayers.

Application of the regular solution model to thermal transition data obtained by differential scanning calorimetry has allowed the determination of partition coefficients, Kp, and the thermodynamics of transfer of a series of indocarbocyanine solutes between the gel and fluid phases of phospholipid bilayers. The indocarbocyanines with alkyl chain lengths of 12 to 22 carbons were partitioned between dipalmitoyl- and distearoylphosphatidylcholine phases at the transition temperatures of the gel-liquid-crystal phase transition. The results indicate that as the alkyl chain length of the solute nears that of the acyl chains of the bilayer lipid, the free energy of transfer from gel to fluid is least negative, and the enthalpy of transfer is most positive. There is almost complete entropy-enthalpy compensation in the transfer process. Comparison of the partition coefficients with published values determined by a fluorescence method show good agreement when the differences in temperature of the measurements are accounted for.

Micelle-vesicle transition in phospholipid-bile salt mixtures. A study by precision scanning calorimetry.

A systematic study of the micelle-vesicle transformation in phospholipid-bile salt mixtures using differential scanning calorimetry (DSC) indicates that the lipid undergoes a variety of changes in its thermal properties as mixed micellar solutions are diluted to concentrations at which vesicles form. In the experiments, micellar solutions of 50 mg/mL total lipid, containing sodium taurocholate (TC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), are diluted to concentrations corresponding to differing extents of aggregation of the TC with phospholipid. Turbidity and equilibrium dialysis measurements are used to establish boundaries between where micelles persist and where vesicles are formed and to determine the extent of aggregation of the TC with DPPC. At molar ratios Re of bound TC to DPPC greater than 0.3, micellar solutions are formed, while at Re less than 0.15 vesicles are evident upon dilution. As the transformation from micelles to vesicles occurs, the thermal transitions in the lipid change from broad, low Cp (max) peaks in the micelle region to multiple peaks of high cooperativity in regions of composition where lamellar structures and vesicles form. The DSC curves show that in the composition region corresponding to where bilayer micelles exist a new thermal phase forms, which has a melting transition near 32 degrees C, if the solutions are allowed to equilibrate for 48 h at 21 degrees C. Furthermore, at compositions between Re = 0 and 0.25, there is metastability in the lipid when equilibrated at 21 degrees C, but heating the lipid through the thermal transitions leads to reversible behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Partitioning behavior of indocarbocyanine probes between coexisting gel and fluid phases in model membranes.

Gel-fluid partition coefficients, Kp, were measured for a series of indocarbocyanine dyes in multilamellar lipid vesicles. The dyes examined had alkyl chain lengths from 12 to 22 carbons. Fluorescence quenching by a spin-labeled phosphatidylcholine-enriched fluid phase created a large difference in quantum yield for indocarbocyanine fluorescence between fluid and gel phases, enabling reliable Kp determinations. The values range from Kp = 8 for the 12-carbon chain, favoring a fluid phase over a Ca2-phosphatidylserine rigid phase, to Kp = 0.02 for the 20-carbon chain dye, favoring a distearoylphosphatidylcholine-rich gel phase over the fluid phase.

Effect of fluorophore linkage position of n-(9-anthroyloxy) fatty acids on probe distribution between coexisting gel and fluid phospholipid phases.

The quenching of probe fluorescence by spin-labeled phospholipid has been used to determine the distribution of a series of n-(9-anthroyloxy) fatty acids between coexisting gel and fluid liquid-crystal phases in multilamellar phospholipid vesicles. The phase distribution ratio in every case is found to favor the fluid lipid phase, but is much greater between fluid and Ca2+-induced gel than between fluid and thermal gel. For a given gel type, n-(9-anthroyloxy)stearic acids with n = 3, 6, 9 or 12 as well as 11-(9-anthroyloxy)undecanoic acid all exhibit similar behavior, favoring the fluid phase by about a factor of 4 over thermally-induced lipid gel phase and by 18 over Ca2+-induced gel phase. 16-(9-Anthroyloxy)palmitic acid, with the bulky probe at the terminus of the 16-carbon chain, favors the fluid phase less strongly, by a factor of 1.5 or 11 over thermally-induced or Ca2+-induced gel phase, respectively, indicating better packing of this probe in phospholipid gel phases.

Precision scanning calorimetry of bile salt-phosphatidylcholine micelles.

Precision scanning calorimetry has been used to examine the thermal behavior of mixed micelles formed between bile salts and dipalmitoylphosphatidylcholine (DPPC). Complex thermal transitions are observed which change dramatically with the mole ratio of bile salt to DPPC, dilution, and ionic strength. Comparison of the behavior of sodium taurocholate (TC) mixed micelles with sodium taurodeoxy-cholate (TDC) mixed micelles indicates similarity in the thermal transitions at high dilution or when the actual micellar composition is similar. It was found through equilibrium dialysis that considerably less TC than TDC is incorporated into mixed micelles with DPPC at a given bile salt concentration. Accounting for these concentration differences provides a means for more direct analysis of changes in the thermal transitions with mole ratio and dilution for the two bile salt components. Resolution of the thermal transitions into several component contributions is employed as an aid to interpretation of the differential scanning calorimetry curves. The curve resolutions lead to estimates of van't Hoff and calorimetric enthalpies of the individual contributions. The results of the curve resolutions, along with the behavior of the total enthalpies of the transitions, are consistent with a transformation in micellar structure occurring when the actual micellar composition is a mole ratio of bile salt to DPPC of about 1 to 1. The transformation region is near that found from X-ray evidence and is thought to correspond to a change from disk-shaped to spherical micelles.

Characteristic proteins systhesized by suspensions of cells isolated from rat gastric mucosa.

The biochemical integrity of rat gastric mucosal cells after isolation with pronase was demonstrated by their synthesis of a wide range of proteins. Approximately 50 bands of pre-existing proteins were detectable by staining on SDS-polyacrylamide electrophoresis gels. Most bands appeared readiolabelled after incubating cells with 14C-leucine or 14C-proline and were detected by autoradiography and fluorography of the gels. Recent synthesis, indicated by the radioactivity of each band, was compared with historical synthesis indicated by the intensity of staining. Densitometric comparisons showed the relative specific radioactivity of certain bands, e.g., one of nominal molecular weight 25000, to be consistently higher than the integrated mean value.