A novel method to visualise the three-dimensional organisation of the human cerebral cortical vasculature.

Current tissue-clearing protocols for imaging in three dimensions (3D) are typically applied to optimally fixed, small-volume rodent brain tissue - which is not representative of the tissue found in diagnostic neuropathology laboratories. We present a method to visualise the cerebral cortical vasculature in 3D in human post-mortem brain tissue which had been preserved in formalin for many years. Tissue blocks of cerebral cortex from two control cases, two Alzheimer's brains and two cases from Alzheimer's patients immunised against Aß42 were stained with fluorescent Lycopersicon esculentum agglutinin (Tomato lectin), dehydrated and cleared using an adapted three-dimensional imaging of solvent cleared organs (3DISCO) protocol to visualise the vascular endothelium. Tissue was imaged using light sheet and confocal microscopy and reconstructed in 3D using amira software. The method permits visualisation of the arrangement of the parallel penetrating cortical vasculature in the human brain. The presence of four vascular features including anastomosis, U-shaped vessels, spiralling and loops were revealed. In summary, we present a low cost and simple method to visualise the human cerebral vasculature in 3D compatible with prolonged fixation times (years), allowing study of vascular involvement in a range of normative and pathological states.

What Is the Role of Developmental Disability in Patient Selection for Pediatric Solid Organ Transplantation?

The National Organ Transplant Act stipulates that deceased donor organs should be justly and wisely allocated based on sound medical criteria. Allocation schemes are consistent across the country, and specific policies are publicly vetted. Patient selection criteria are largely in the hands of individual organ transplant programs, and consistent standards are less evident. This has been particularly apparent for patients with developmental disabilities (DDs). In response to concerns regarding the fairness of transplant evaluations for patients with DDs, we developed a transplant centerwide policy using a multidisciplinary, community-based approach. This publication details the particular policy of our center. All patients should receive individualized assessments using consistent standards; disability should be neither a relative nor an absolute contraindication to transplantation. External review can increase trust in the selection process. Patients in persistent vegetative states should not be listed for transplantation.

Controversy and consensus on pediatric donation after cardiac death: ethical issues and institutional process.

Donation after cardiac death (DCD) remains controversial in some pediatric institutions. An evidence-based, consensus-building approach to setting institutional policy about DCD can address the controversy openly and identify common ground. To resolve an extended internal debate regarding DCD policy at Children's Hospital Boston, a multidisciplinary task force was commissioned to engage in fact finding and deliberations about clinical and ethical issues in pediatric DCD, and attempt to reach consensus regarding the development of a protocol for pediatric DCD. Issues examined included values and attitudes of staff, families, and the public; number of possible candidates for DCD at the hospital; risks and benefits for child donors and their families; and research needs. Consensus was reached on a set of foundational ethical principles for pediatric DCD. With assistance from the local organ procurement organization (OPO), the task force developed a protocol for pediatric kidney DCD which most members believed could meet all the requirements of the foundational ethical principles. Complete consensus on the use of the protocol was not reached; however, almost all members supported initiation of kidney DCD for older pediatric patients who had wished to be organ donors. The hospital has implemented the protocol on this limited basis and established a process for considering proposals to expand the eligible donor population and include other organs.

Closed-form expressions for ocean reverberation and signal excess with mode stripping and Lambert's law.

Closed-form expressions for two-way propagation and reverberation in variable depth ducts are derived for isovelocity water by using ray invariants and acoustic flux. These expressions include the transition to single mode propagation at long range. Three surface scattering laws are considered: Lambert, Lommel-Seeliger, and angle independent, and these are compared with a point target to give explicit signal-to-reverberation ratios. In particular, there is interesting and sometimes surprising behavior when the propagation obeys mode-stripping (the high angles are preferentially attenuated by bottom losses) whilst the scattering obeys Lambert's law (high angles are preferentially back-scattered). There may be conditions where the signal-to-reverberation ratio is independent of range so that there is no reverberation range limit. Bottom slope dependence of both target echo and reverberation is surprisingly weak. The implications of refraction are discussed. The angle dependence for a point or surface scatterer at a given range can be translated into arrival time, so it is possible to calculate the received pulse shape for one-way or two-way paths. Because the tail is exponential with a range-independent half-life that only depends on bottom reflection properties there is scope for extracting geoacoustic information from the pulse shape alone. This environmental time spread is also of use to sonar designers.

Geoacoustic inversion of ambient noise: a simple method.

The vertical directionality of ambient noise is strongly influenced by seabed reflections. Therefore, potentially, geoacoustic parameters can be inferred by inversion of the noise. In this approach, using vertical array measurements, the reflection loss is found directly by comparing the upward- with the downward-going noise. Theory suggests that this simple ratio is, in fact, the power reflection coefficient-potentially a function of angle and frequency. Modeling and parameter searching are minimized, and the method does not require a detailed knowledge of the noise source distribution. The approach can handle stratified environments and is believed to tolerate range dependence. Experimental data from five sites, four in the Mediterranean, one on the New Jersey Shelf, are described. Most of the Mediterranean sites had temporally varying noise directionality, yet yielded the same reflection properties, as one would hope. One site was visited in conditions of very low surface noise. This paper concentrates on an experimental demonstration of the feasibility of the method and data quality issues rather than automatic search techniques for geoacoustic parameters.

Review of a bronchial hygiene evaluation program.

In the 1970s the demand in our hospital for bronchial hygiene therapy (aerosols, IPPB, incentive spirometry, chest physical therapy) had increased to such a level that 20-30% of the ordered therapy was not being administered. Because the respiratory therapists and medical directors were convinced that much of the ordered therapy was unnecessary, the Respiratory Therapy Department began a program in 1978 in which specially trained respiratory therapists were authorized to evaluate all non-intensive-care patients for whom bronchial hygiene therapy had been ordered. The program protocol consists of a medical record review, a physical assessment of the patient, the development of a patient-care plan, and a re-evaluation every 2-3 days of the patient's continued need for therapy. We found that initiation of the program has led to improved documentation of the need for bronchial hygiene therapy and a significant decrease in total procedures performed, not merely a substitution of therapies. After being adjusted to the 1981 Consumer Price Index (CPI), total charges for bronchial hygiene therapy were markedly decreased even though hospital charges increased 77.4% above the CPI inflation rate. Since the program was begun, the respiratory therapy staff has been able to administer all ordered respiratory care services to patients in a critical care setting and not less than 90% of ordered bronchial hygiene therapy to patients outside the intensive care unit. House staff, attending physicians, and patients and their families appear to be satisfied with the therapist-evaluators, and the morale of respiratory therapists seems to have improved as a result of their being able to take a more role in the treatment of their patients and to apply their skills to the patients most in need of them.