Effect of axial loading on neural foramina and nerve roots in the lumbar spine

The hypothesis that the neural foramina in some patients are critically narrowed by axial compression of the spine has not been studied with direct imaging techniques. Frozen cadaveric motion segments of the lumbar spine (intervertebral disk and contiguous vertebrae) were imaged with computed tomography (CT). The segments were thawed and compressed in a hydrostatic press to simulate axial loading, and then the segments were frozen and imaged again. The motion segments were subsequently sectioned with a cryomicrotome, and the chronic degenerative changes present in the disks were classified. Pre- and post-compression CT images were compared, and anatomic relationships were studied. In 41 randomly selected segments (some with preexisting radial, transverse, and concentric annular tears), compression diminished the diameters and cross-sectional areas of the spinal canal and neural foramina. In no cases were nerve roots displaced, distorted, or compressed by axial loading. This study suggests that axial loading, such as that produced by ordinary weight bearing, does not critically compromise the neural foramina even in the presence of chronic degenerative disk changes.     

Blood pressure control in dialysis patients: importance of the lag phenomenon

Failure by the world dialysis community to understand and use the dry-weight method of blood pressure (BP) control has resulted in an increasing incidence of treatment-resistant hypertension, which remains the principal cause of cardiovascular morbidity and mortality. This failure may in part be because the relationship between the extracellular volume (ECV) and BP is not simple and linear, but complex, because of a lag of several weeks between the normalization of the time-averaged ECV and the decrease in BP. Another cause for this failure may be the unwillingness to taper and stop all antihypertensive medications during the transition from hypertension to normotension. In this report, we describe in detail the lag phenomenon, document its presence during treatment in other populations, and describe how this knowledge is used in the application of the dry-weight method of drug-free BP control in the dialysis population.     

Isoniazid‐induced control of Mycobacterium tuberculosis by primary human cells requires interleukin‐1 receptor and tumor necrosis factor

Proinflammatory cytokines are critical mediators that control Mycobacterium tuberculosis (Mtb) growth during active tuberculosis (ATB). To further inhibit bacterial proliferation in diseased individuals, drug inhibitors of cell wall synthesis such as isoniazid (INH) are employed. However, whether INH presents an indirect effect on bacterial growth by regulating host cytokines during ATB is not well known. To examine this hypothesis, we used an in vitro human granuloma system generated with primary leukocytes from healthy donors adapted to model ATB. Intense Mtb proliferation in cell cultures was associated with monocyte/macrophage activation and secretion of IL‐1β and TNF. Treatment with INH significantly reduced Mtb survival, but altered neither T‐cell‐mediated Mtb killing, nor production of IL‐1β and TNF. However, blockade of both IL‐1R1 and TNF signaling rescued INH‐induced killing, suggesting synergistic roles of these cytokines in mediating control of Mtb proliferation. Additionally, mycobacterial killing by INH was highly dependent upon drug activation by the pathogen catalase‐peroxidase KatG and involved a host PI3K‐dependent pathway. Finally, experiments using coinfected (KatG‐mutated and H37Rv strains) cells suggested that active INH does not directly enhance host‐mediated killing of Mtb. Our results thus indicate that Mtb‐stimulated host IL‐1 and TNF have potential roles in TB chemotherapy.     

Design and preliminary evaluation of an expert system for platelet request evaluation

In spite of growing awareness of the potential risks associated with transfusion, the number of platelet units transfused in the United States continues to increase each year. There is a growing interest in ensuring that all transfusions are administered for appropriate reasons. Prospective review of requests for transfusions has been used to accomplish this goal. Although successful in reducing the number of inappropriate transfusions, this review method requires great time commitments by blood bank personnel and physicians. A knowledge-based system (ESPRE) that aids hospital blood bank personnel in the review of requests for platelet transfusions has been developed. The system automatically obtains most of the required patient data via a direct link to the hospital's main laboratory computers. The system generates a printed report that includes a list of patient-specific data, a list of the conditions for which a transfusion would be appropriate for the particular patient (given the clinical condition), and the conclusions drawn by the system. During a preliminary clinical evaluation of ESPRE, 73 randomly selected platelet transfusion requests were evaluated for approval by laboratory personnel and ESPRE. Overall, ESPRE would have approved 71 of the requests and laboratory staff would have approved 72. Forty-four percent of the requests would have been approved for the same reasons given by the staff. There were only three disagreements on final approval between ESPRE and blood bank personnel. This computerized expert system is a promising approach to the prospective review of all platelet transfusions.     

Patient-related blood drives

Ten patient-related blood drives were evaluated and compared to five other blood drives. The patient-related blood drives were easier to organize, more fruitful, and more satisfying for the donors and workers. The authors suggest a role for patient-related blood drives in the present recruitment system and discuss how hospitals and blood centers can coordinate their efforts to have this type of blood drive. Finally, it is suggested that patient-related blood drives can increase recruitment, especially in large metropolitan areas that suffer from chronic blood shortages.