Biomedical subjects
Publications and source records attributed to R L Baker.
A case of invasive cutaneous Trichophyton rubrum infection complicated the course of a patient undergoing chemotherapy for acute lymphocytic leukemia. This dermatophytic disease was well controlled with ketoconazole. Prior experience with these unusual infections is summarized.
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The Application of electron microscopic methods to the study of neutrophils obtained from single sites by crevicular washing is described. A subsequent preliminary study of neutrophils and neutrophil-bacterial interactions at advanced lesions in patients with juvenile periodontitis and juvenile diabetes indicated that the neutrophils are phagocytically active at these sites. It is suggested that in vitro assays of crevicular neutrophil function may exaggerate the extent of impairment of phagocytosis because of cellular activity which has taken place prior to the time of sampling.
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The material adherent to a periodontal probe during the examination of deep periodontal pockets was studied with light and electron microscopy. Most of the specimens contained bacteria with a morphology which has been associated with a pathogenic flora. The findings suggest that periodontal probes may have the potential of transmitting pathogenic bacteria from involved sites to other sites in the mouth, although it remains to be demonstrated that this will result in actual implantation of the organisms at the new sites.
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For the first time, mononuclear cell-mediated ingestion of osteoid in cultures of long bones of fetal rats is described and characterized. The mononuclear cells, located at sites of osteoid deposition, ingest collagen fibrils and clumps of mineral crystals which are segregated within cytoplasmic vacuoles or multivesicular bodies. The ingestion of osteoid continues in cultures treated with agents that normally inhibit osteoclastic bone resorption. Morphologically, the osteoid-containing cells are characterized by a moderate number of mitochondria and short-stranded rough endoplasmic reticulum, a modest Golgi apparatus and variable numbers of vesicles, vacuoles, and multivesicular bodies. The morphologic appearance of the mononuclear cell is consistent with that of a macrophage.
Bone cultures exposed to prostaglandin E2 (PGE2) and revealed an increase in 45Ca release from bone to medium and an increase in osteoclast number compared to control bones. In addition, PGE2-treated osteoclasts contained a more extensive ruffled border region than control osteoclasts. These data suggest that PGE2 activates existing osteoclasts and causes proliferation and differentiation of osteoclast precursor cells. The existence of macrophages in resorbing fetal bone explants was documented. These macrophages contain numerous phagolysosomes and lipid vacuoles and are often located adjacent ot osteoclasts or closely apposed to calcified tissue surfaces. PGE2 caused an early increase in the number of macrophages. It is postulated that fetal bone macrophages are primarily engaged in phagocytosis and digestion of cellular debris, but also play a role in the process of bone resorption.
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Ultrastructural observations on macrophage-mediated resorption of calcified tissue of killed fetal long bones are described and correlated with increased 45Ca release into the medium. Macrophages disrupt calcified tissue extracellularly and appear to engulf large fragments of mineralized matrix. Ruffled borders, which are common features of osteoclasts at sites of resorption of bone, do not develop in macrophages. However, clear zones are seen in macrophages as well as osteoclasts. These findings provide additional evidence for non-osteoclast-mediated resorption of calcified tissue.
In the general population teenage pregnancies present an elevated rate of perinatal mortality compared with pregnancies of women in their 20s. In 2 large-scale university hopsital studies (American and Danish) the teenage pregnancies showed lower perinatal mortality than those of any other age group. This article attempts to determine the origin of these differing results. A comparative analysis was conducted, focusing on methodologies, subject characteristics, and treatment procedures involved in the 2 classes of studies, which involved representative populations and university hospital samples. The uniformly high quality medical treatment provides to all subjects in the university hospital samples contrasted with the uneven quality of treatment found in population studies constituted the most important difference. Since pregnant teenagers generally tend to be of lower socioeconomic status, they are likely to receive inferior medical care. It was argued that this factor could, to a large extent, be responsible for the elevated mortality rates found in teenage pregnancies in representative populations.
The therapeutic effect of goat anti-human thymocyte antiserum globulin (ATG) was assessed in 10 patients with myasthenia gravis. All subjects had far-advanced, debilitating disease poorly responsive to anticholinesterase therapy. Prolonged, low-dose ATG therapy was used, with 1.0 to 2.6 gm ATG protein administered intramuscularly over a 28- to 73-day period. Therapeutic responses of varying degrees were noted in 8 of 10 patients. Completion of a course of ATG treatment and discontinuation of the drug did not lead to acute relapse. Follow-up examinations for over 5 years have been maintained. A mean remission period of approximately 2 years was observed. This therapy deserves further evaluation; subjects with progressive myasthenia gravis despite prior thymectomy may represent ideal candidates.
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A computer-assisted subjective eye examination was administered to 78 patients as they volunteered. They were also examined in the conventional, manual way, some before and some after the computer-assisted examination. Results of the computer-assisted examination were compared to those obtained by conventional subjective methods. For the distance prescription, satisfactory agreement was obtained for 83% of the patients. The 17% unsatisfactory prescriptions were subdivided into about 6% avoidable errors (caused by errors in software, hardware, or optometric flow charts), about 6% errors of undetermined cause, and 4% fundamental errors (caused by patient's physical and mental impairment or confusion). A similar analysis is made for the near add. With further development of the system it is expected that between 90 and 96% of patients in an optometric clinic can be successfully examined by this computer-assisted method.
A case of spherophakia with unilateral traumatic phacometecesis is presented and the treatment of the postextraction sequelae by contact-lens therapy is described.
Rehabilitation is a long-term multidisciplinary, and outcome-oriented process, which requires a more complex data base than one derived from a strictly medical model of diagnosis, treatment, and cure. The rehabilitation data base must document need and potential for benefit, reasons for encounter, intensity of services, response to services in terms of outcome and durability of rehabilitation, and significant modifiers related to the individual and his environment that affect intake, outcome, and follow-through. Research has shown the potential value of functional indices as components of this data base and has illustrated approaches to their validation. A central question is whether a data base designed for patient care can also have utility for institutional management and policy formulation in view of differences in content, level of detail, and timing. Other problems that have become obvious in the past decade of experimentation at the Texas Institute for Rehabilitation and Research include the burden of data collection on professional and technical staff, cost effectiveness of data systems, validity and reliability, too much or irrelevant data in the system, and behavioral obstacles to new systems and their effective use. Despite these problems, multilevel information systems that can be expanded or contracted in detail and are designed to provide data of established utility are clearly needed in rehabilitation.
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