Studying neurosurgical implants for Parkinson disease: a question of design.

North American researchers' perspectives on designing neurosurgical implant studies for Parkinson disease (PD) challenged the custom of holding surgical trials to less stringent evidentiary standards than other clinical studies. Researchers supported placebo surgery-controlled trials. The framework they used to design and evaluate studies both of deep brain stimulation and cellular implants for PD may be applicable to a broad range of surgical implants for other disorders.

A model for improving coverage policy decisions.

Reasoned and defensible coverage decisions are essential for a fairer and more efficient healthcare system. Because healthcare resources are finite, coverage decisions should be informed by economic evaluations and made from a perspective that attends to the interests of both individuals and the population enrolled in a plan as a whole. Coverage decisions for all healthcare interventions should follow a 2-step procedure that consists of (1) the relatively impartial and objective assessment of an intervention's eligibility for coverage and (2) the distinctively value-laden determination (for which the enrolled population's values and preferences should take priority) to cover, conditionally cover, or not cover an intervention.

Ethical and policy issues in human fetal tissue transplants.

A review of human fetal tissue policies over the past 40 years reveals an increasing awareness that the use of this tissue raises unique ethical and policy issues. Initially it was believed that the use of fetal tissue was no different from using any other abandoned surgical waste specimen. Then state laws were passed requiring fetal tissue to be treated with the same respect and protection as tissue obtained from cadaver donors generally. Most recently, a few state and federal policies suggest that the use of fetal tissue requires a unique set of provisions, that it is unlike either the use of tissue from a routine cadaver donor or the use of tissue from abandoned waste specimens. In this paper we identify four central features of fetal tissue donation that make it a unique type of tissue donation requiring its own framework of respect and protection for the parties involved. We then critically review the most important current state and federal fetal tissue policies, including the NIH Revitalization Act of 1993.

Are there really alternatives to the use of fetal tissue from elective abortions in transplantation research?

PIP: Researchers believe fetal tissue can be easily transplanted into and cure people with incurable debilitating diseases such as Parkinson's disease. In 1988, the Reagan Administration stopped funding transplantation research of fetal tissue from induced abortions. An advisory panel later decided that it is an acceptable public policy as long as certain conditions a re met. Yet the Bush Administration continued the ban. In 1992, it erroneously claimed that transplantation research could use alternative sources of fetal tissue. 1 alternative is fetal tissue obtained from ectopic pregnancies. Yet spontaneously aborted ectopic pregnancies tend not to produce recognizable or viable in culture fetal tissue and if they do the tissue has been ischemic for days. Ectopic pregnancies requiring surgical sterilization tend to be morphologically abnormal. The only likelihood of viable fetal tissue form ectopic pregnancies is a fetus with myocardial contractility before surgery. The administration also recommended use of fetal tissue from spontaneous abortions but these fetuses often have a major chromosomal or other fatal defect. Researchers cannot use chromosomally abnormal fetal tissue since it growth, development, and function are unreliable. Expulsion of the necrotic fetus tends to occur a couple of weeks after death. The Bush Administration also proposed use of tissue from stillbirths but their tissue tends to be nonviable and the tissue, even if it were viable, is generally not at the developmental stage needed for transplantation. The placenta and yolk sac were other suggested alternatives, but the placenta is likely to be less immunogenic than embryonic tissue. It can help develop certain cell lines which produce insulin or neurotransmitters like dopamine, however. The yolk sac could replace fetal liver cells in transplantation. Nevertheless the only advantage of using the suggested alternatives is the perception of them raising less ethical concern than fetal tissue from an induced abortion.^ieng

Fetal tissue research and the misread compromise.

The bill to restore federal funding for human fetal tissue research has been passed by the House and awaits Senate approval. But it requires women who are willing to donate fetal tissue to certify that they did not have an abortion with the intent to donate. It further requires researchers to keep the certifications on file and available for government audit. Both requirements spell trouble.

PIP: H.R. 2507 passed by the US House of Representatives, is an attempt to end the ban on fetal tissue research. However it signals a new era in government violation of privacy and ultimately will undermine its own stated purpose. The law provides that any woman wishing to donate the fetal tissue from an abortion must sign 2 ethical intent forms. The 1st stating that the decision to donate was made independently of the decision to abort. The 2nd stating that the reason for aborting was not to donate fetal tissue. These forms of ethical intent are to be kept on file by the researchers using the fetal tissue and are to be made available for audit to ensure compliance. The law does not have any provision for protecting the confidentiality of these forms, nor does it state whose property they become. It also does not state who allowed to audit the records or whose responsibility it is. The results of this law are that women fearing exposure of their name in a document open to public audit will not want to donate. Further, in many states this failure to sign the forms can be legally viewed as intent to abort for donation and thus the abortion could be denied. In addition, researchers will not want to cover the expense or controversy surrounding these records and as such will refuse to accept fetal tissue.

Pseudoelasticity of excised visceral pleura.

A pseudostrain-energy function is proposed for describing the behavior of excised sheets of canine visceral pleura. Pseudoelastic material constants are determined from experimental biaxial data by employing a nonlinear least-squares algorithm. The agreement between theory and experiment is shown to be quite good. Furthermore, the visceral pleura studied appears to be inelastic and to exhibit in-plane isotropy. Comparison with previous works is discussed.

Quantification of strains in biaxially tested soft tissues.

A technique for the quantification of the strain field in the central region of biaxially tested planar soft tissues is presented. A vidicon-based image analysis system interfaced to a PDP 11/34 minicomputer is employed to track particles affixed to the specimen surface in real-time, from which the strains are inferred. Illustrative results are given for tests on excised canine pleural specimens on which four particles were affixed. The technique is applicable, however, to any planar soft tissue and any number of tracking particles. This procedure is recommended over previously used methods when testing anisotropic tissues.

Mechanical behavior of excised canine visceral pleura.

A computer-controlled optical electromechanical biaxial test system was employed to study the mechanical response of excised sheets of canine visceral pleura. Three classes of tests were performed: uniform biaxial stretching tests and tests in which the specimen was cyclically stretched along one axis while either the load or dimension was maintained at a prescribed level in the orthogonal direction. The tests were defined completely within the software. Strain was inferred from tracking four particles affixed to the central region of the specimen surface. The visceral pleura was found to behave similarly to other biological soft tissues and required preconditioning to yield repeatable responses. In addition, the visceral pleura appeared to possess in-plane transverse isotropic material symmetry and to exhibit strong in-plane mechanical coupling at lower loads. The data presented herein is sufficient for determination of certain three-dimensional constitutive laws which are essential for further biomechanical analyses of the visceral pleura's role in lung response.

A finite element model for macroscopic deformation of the lung.

A finite element model is formulated for determining the macroscopic stress, strain and deformation of the lung parenchyma. The effects of nonlinear elastic behavior, finite deformation, and interfacial tension are included. An incremental approach is used. Illustrative results for deformation of the lung due to its weight are included. The necessity of including surface tension explicitly is demonstrated.