Biomedical subjects

M D Brown

Publications and source records attributed to M D Brown.

296 records · Page 17Linked to original sources

PubMedDate not supplied

Activation of vascular endothelial cell adhesion molecule expression by sickle blood cells.

Microvascular complications in sickle cell disease occur as a result of obstruction of small vessels by deoxygenated sickle cells. Cerebrovascular complications are also common and result from obstruction of large blood vessels by thrombosis with changes in vessels that have some similarity to those found in arteriosclerotic vascular disease. Endothelial damage and activation from sickle cell-endothelial interactions may contribute to both. We find that endothelial cells have increased expression of VCAM-1, E-selectin, and ICAM-1 when exposed to sickle blood cells. The concentration-dependent, sickle-induced, adhesion molecule expression is significantly greater than that promoted by normal cells. The time course of Cell Adhesion Molecule (CAM) expression is similar to that induced by TNF-alpha and IL1. Studies after white cell enrichment and reduction suggest leukocytes are the primary mediators. CAM expression by endothelial cells appears stimulated by soluble factors. Antibody inhibition studies support TNF-alpha and IL-1, produced by sickle leukocytes, as the primary soluble factors responsible for the observed CAM expression. Both the induction of endothelial CAM expression and subsequent endothelial adherence of sickle erythrocytes may play significant roles in the pathophysiology of sickle-related complications, and reduction in CAM expression may provide a new approach to treatment.

Anemia, Sickle Cell↗

PubMedDate not supplied

Pseudohypoparathyroidism: case report.

A patient with pseudohypoparathyroidism is presented. The phenotypic appearance, known as Albright heredity osteodystrophy includes: short stature, round face, brachydactylia, and ectopic calcifications in the soft tissues. Dental manifestations reported in the literature are enamel hypoplasia, hypodontia, malformed roots, enlarged pulp chambers, microdontia, and pulp calcifications. Additional findings in this case are ankylosis and an enlarged frontal sinus. The delayed diagnosis of pseudohypoparathyroidism with the early presentation of multiple dental anomalies is discussed.

Adolescent↗

PubMedDate not supplied

The effect of point-of-use water conditioning systems on community fluoridated water.

The purpose of this investigation was to determine the effect of several point-of-use water conditioning systems on the fluoride concentration in community fluoridated water. Point-of-use water conditioning systems attach at the sink to provide the user with protection from certain water contaminants. A sampling apparatus was constructed to allow collection of water samples before and after conditioning. The apparatus connected the following types of point-of-use water conditioning systems: a faucet water filter, a cellulose fiber filter, an activated carbon filter, a reverse osmosis system, and a distillation unit. These samples were tested by an independent laboratory using colorimetric determination of fluoride concentration. All point-of-use water conditioning systems tested caused a statistically significant reduction in fluoride (P less than .001). Of particular note were reductions in fluoride concentration by the activated carbon filter (81%), the reverse osmosis system (84%), and the distillation unit (99%). These reductions are clinically significant, and necessitate supplementation for optimal fluoride intake. Patients using these water conditioning systems should be advised to have their water tested, and to consider fluoride supplementation to ensure adequate benefit from this caries prevention method.

Carbon↗

PubMedDate not supplied

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management.

One-hundred-four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.

Diagnosis, Differential↗

PubMedDate not supplied

Banking of massive osteoarticular and intercalary bone allografts--12 years' experience.

Preparation and banking of massive osteoarticular allografts and intercalary bone allografts have been performed for the past 12 years. Careful selection of donors as well as extensive laboratory studies of the donor and the allograft have virtually eliminated the danger of transmitting disease from the donor to the recipient. The availability of a variety of allografts in the Tissue Bank allows for the selection, on an anatomic basis, of an allograft best suited for a particular recipient. The authors have supplied several hundred allografts to recipients in many institutions on the premise that excision, preparation, banking, and implantation of bone allografts constitute a clinical service. Thus, the surgeon who excises and prepares the allograft assumes a joint responsibility for the care of the recipient with the surgeon who implants the allograft. This establishes a close working relationship, which encourages frequent consultation between the parties concerned. This relationship is of particular importance in the initial evaluation of the patient and in determining which particular allograft will best serve a given patient. The experience at the authors' institution provides a model for a multiinstitutional facility that may serve as a base for discussion of the methodology involved in the excision, preparation, and storage of bone allografts. The costs associated with the operation of such a facility are not inconsiderable, but the cost of individual osteoarticular and intercalary allografts can be brought down by an increase in the efficiency of operation inherent in the processing of allografts from over 100 donors per year. During the past several years, the cost of excising and preparing intercalary allografts has been $600 per implant, while the cost for osteochondral allografts varied between $900 and $1,200. Such a large multiinstitutional facility offers the advantages of readily available allografts and quality control. However, because of the expense and complexity of operation, it may not be suitable for many medical centers.

Adolescent↗

PubMedDate not supplied

Bone allografts in spinal surgery.

Despite long-standing interest by orthopedic surgeons in the replacement of diseased segments of the spine with grafts from other individuals, progress in this direction does not extend beyond the last two decades. One of the reasons for a relatively slow rate of progress in these endeavors was the lack of individuals and organizations devoted to safely obtaining and preparing bone allografts for routine clinical transplantation. In an effort to overcome this difficulty, a Tissue Bank was established at the University of Miami-Jackson Medical Center. The service offered by this bank provided an impetus for the clinical study and use of freeze-dried bone allografts, not only in our institution but also extended to orthopedic and neurologic surgeons throughout the United States.

Bone Transplantation↗

PubMedDate not supplied

Positioning techniques in spinal surgery.

By keeping in mind the principle of stability, ease of exposure and physiologic restrains on the patient, the optimum safe positioning technique for successful spinal surgery can be selected. We recommend skeletal or head-halter traction for anterior exposure of the cervical spine. Gardner's three-point skeletal fixation or halothoracic immobilization are the methods of choice for posterior cervical spine exposure. Either rolled towels or the Relton-Hall frame are preferred for posterior thoracolumbar surgery. Specific attention to protection of the eyes, bony prominences and peripheral nerves is essential.

Cervical Vertebrae↗

PubMedDate not supplied

Hypotensive anesthesia and autotransfusion in spinal surgery.

Sixty-eight (68) spinal operations performed under normotensive anesthesia were compared with 77 procedures performed under controlled hypotensive anesthesia. Procedures reviewed included Harrington instrumentation and fusion, dorsal arch resection, laminectomies and other spinal fusions. Intraoperative and postoperative blood loss and blood replacement were found to be reduced by approximately 50% in the group undergoing controlled hypotensive anesthesia for each procedure reviewed. This reduction in blood loss was achieved with only a moderate reduction in blood pressure (20 mm Hg systolic). Reduction in systolic blood pressure of greater than 20 mm was not associated with greater reduction in blood loss. Deliberate hypotension was coupled with hemodilution, lowering the hematocrit to 28% to 30% in order to increase cardiac output, increase tissue perfusion and decrease venous stasis. Autotransfusion has further reduced the need for homologous transfusion such that the combined techniques of hypotension and autotransfusion can eliminate the need for homologous blood transfusion in all but the most unusual cases.

Blood Pressure↗