Redefining the Molecular Interplay between Dimethyl Sulfoxide, Lipid Bilayers, and Dehydration.

The potentially damaging action of dimethyl sulfoxide (DMSO) on phospholipid bilayers remains a matter of controversy. We have conducted a series of long-scale molecular dynamics simulations of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers at various levels of hydration in the presence of variable quantities of DMSO. These simulations provide evidence for a non-destructive dehydrating mechanism of action for DMSO on DOPC bilayers across a wide concentration range and levels of hydration. Specifically, under full- and low-hydration conditions, the bilayer underwent a minor lateral contraction, coinciding with surface dehydration in the presence of dilute DMSO solutions (XDMSO < 0.3). At higher DMSO concentrations, this bilayer structure was retained despite a progressive deterioration of the hydration structure at the interface. A similar convergence of bilayer structural properties was observed under dehydration conditions for 0.3 < XDMSO < 0.7. Destabilization occurred for dehydrated bilayers in the presence of XDMSO ≥ 0.7, suggesting the existence of a DMSO concentration and/or dehydration threshold. However, such DMSO concentrations far exceed those established as toxic to other cellular components. Our findings represent a computational model for DMSO-DOPC interactions that is consistent with a range of experimental characterizations, offering new molecular insights into the cryoprotective mechanisms of action of DMSO.

Structural comparison of the finger proximal interphalangeal joint surfaces and those of the third toe: suitability for joint reconstruction.

PURPOSE: This study compared the degree of surface structural similarity between finger proximal interphalangeal joints and third toe articular surfaces to assess the appropriateness of using partial toe articular osteochondral grafts for finger joint reconstruction. METHODS: Computer models were generated from 4 paired cadaver hands and feet and compared the radius of curvature of toe and finger articular surfaces. The angle created by the palmar divergence of adjacent condyles of the same phalanx was also compared and described as the angular difference. The distal articular surfaces of the third toe proximal and middle phalanx were compared to distal articular surfaces of all 4 finger proximal phalanges. The radius of curvature was also compared between the third toe middle phalanx base and those of all 4 fingers. RESULTS: The toe middle phalanx medial and lateral condyles were 66% and 60% the size of the respective finger condyles. The mean angular difference between adjacent condyles of the toe middle phalanx compared to the finger was 20°. The toe proximal phalanx medial and lateral condyles were 75% and 70% the size of the respective finger condyles, with a mean angular difference between adjacent condyles of 6°. The toe middle phalanx medial base was closer in size to that of the finger (95% to 178%) compared to the toe middle phalanx lateral base (205% to 254%). CONCLUSIONS: This study revealed that the third toe proximal phalanx distal articular surface more closely matched the geometric characteristics of the finger proximal phalanx distal articular surface than did the toe middle phalanx distal articular surface. The medial base of the toe middle phalanx more closely approximated the size of the finger middle phalanx base than did the lateral toe middle phalanx base. CLINICAL RELEVANCE: Quantitative data have been provided to help guide third toe osteochondral donor site selection when reconstructing traumatic finger proximal interphalangeal joint defects. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

The effect of ankle joint immobilization on lower limb venous flow.

BACKGROUND: Below-knee cast immobilization is associated with an increased risk of developing deep vein thrombosis secondary to venous stasis. We investigated the effect of weight-bearing in a below-knee cast or pneumatic walking boot on lower limb venous blood flow. METHODS: Duplex ultrasonography was used to measure venous blood flow in the popliteal vein of 10 healthy volunteers. Venous blood flow was measured while at rest, ambulating non-weight-bearing, partial weight-bearing, and full weight-bearing. Measurements were performed without ankle joint immobilization, with the ankle immobilized in a neutral cast, and with the ankle immobilized in a pneumatic walking boot in both neutral and equinus. RESULTS: There was no significant reduction in venous blood flow measurements between full weight-bearing without ankle joint immobilization and full weight-bearing in a neutral cast or neutral pneumatic walking boot. However, venous blood flow was reduced when partial weight-bearing (50%) and when full weight-bearing in a pneumatic walking boot in equinus. CONCLUSION: These results demonstrate that venous blood flow returned to normal levels when the subjects were permitted to fully bear weight in below-knee casts or walking boots, provided that the ankle joint was not in equinus. CLINICAL RELEVANCE: Weight-bearing status and ankle joint position should be appreciated during decisions for the provision of chemical thromboprophylaxis.

Electroconvulsive therapy in Scottish clinical practice: a national audit of demographics, standards, and outcome.

OBJECTIVES: Many of the commonly expressed concerns about the effectiveness of electroconvulsive therapy (ECT) have been addressed by scientific studies. However, this has done little to reassure service users and the public at large about its use in routine clinical practice. This 3-year study between 1997 and 1999 consisted of a series of audit cycles to systematically answer questions about ECT demographics and outcome across Scotland. METHODS: Audit standards were agreed and each ECT clinic was visited at least twice to assess facilities and adherence to protocol as set down by the Royal College of Psychiatrists, UK. Demographics and outcome after ECT were measured during 2 9-month sample periods. Adequacy of teaching and supervision was assessed directly and by questionnaire. RESULTS: Facilities and equipment at ECT centers were up to date and generally of a high standard. ECT was given at a rate of 142 treatments per 100,000, mainly to white adult patients suffering from a depressive disorder. The ratio of females to males was approximately 2 to 1, and ECT was not given disproportionately to the elderly. 76% of patients were of informal status and 82% gave informed consent, with the remaining 18% receiving treatment under the safeguards of the Mental Health (Scotland) Act 1984. There was a definite clinical improvement with treatment, defined as at least a 50% fall in the Montgomery Asberg Depression Scale, in 71% of those treated for depressive illness. 65% of those treated for a non -depressive psychosis were rated as at least 'much improved' on the Clinical Global Impression scale. CONCLUSIONS: ECT given in routine clinical settings across Scotland meets Royal College of Psychiatrists standards and is an effective treatment of the clear majority of patients.