Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. III. Intraoperative identification of vessels critical to spinal cord blood supply

Somatosensory evoked potentials were used to locate intercostal arteries critical to spinal cord blood flow in nine dogs. To mimic a clinical situation, the proximal descending thoracic aorta (left subclavian artery to T7) was excluded with cross-clamps, and partial pulsatile left atrial-femoral artery bypass was instituted to maintain distal aortic pressure at 100 mm Hg. Progressively lower aortic segments were excluded (T7-10, T10-L1, L1-3, L3-6, L6-7) until loss of somatosensory evolved potentials occurred. Spinal cord blood flow measurements at the time of evoked potential loss revealed significant ischemia (p less than 0.02 versus baseline) in the excluded segment in seven animals but normal spinal cord blood flow in the remainder of the cord. Upon reperfusion, significant reactive hyperemia (p less than 0.02) was noted only in previously ischemic cord segments. Two animals exhibited no change in somatosensory evoked potentials or spinal cord blood flow despite exclusion of the entire thoracoabdominal aorta, presumably as a result of spinal collaterals. Loss of somatosensory evoked potentials despite adequate distal perfusion indicates that critical intercostal vessels have been excluded from systemic and bypass circulations. Use of evoked potential measurements in both experimental and clinical situations provides a means for assessing adequacy of spinal cord blood flow during cross-clamping and can alert the surgeon to the need for reimplantation of critical intercostal arteries during surgical resection of the thoracoabdominal aorta.     

Trachoma: 1985 update in Western Australia

Aboriginal preschool and school children were surveyed in the Eastern Goldfields Region and the Eastern Kimberley Region of Western Australia between 1979 and 1985. Statistics from these surveys show that there has been an apparent change in pattern of follicular trachoma since the National Trachoma and Eye Health Programme in some of the communities. The prevalence of follicular trachoma in the 0 to 9 year old age groups had declined from 26.4% in 1977 to 8.8% in 1984/1985 in the Eastern Goldfields and Red Centre combined (0.10 greater than p greater than 0.05). The prevalence reduction occurred in areas where there have been improvements in school hygiene and housing. The prevalence of cicatricial trachoma has also apparently declined from 65% in 1977 to 39% in 1985 in the Red Centre, from 39% in 1977 in the Eastern Goldfields to 21.7% in 1985, and from 58% in 1977 to 24.9% in 1985 in the Eastern Kimberley, Communities at risk were identified and recommendations made for frequency of continued screening, depending on age, distribution and location.     

Investigation of the anti-complement agents, FUT-175 and K76COOH, in discordant xenotransplantation

Abstract: We examined whether hyperacute rejection (HAR) of a discordant xenograft in a nonhuman primate model could be inhibited by the anticomplement agents, FUT-175 (FUT) and K76COOH (K76). The inhibitory effect of FUT and K76 on baboon sera was studied in vitro by i) complement-mediated hemolysis of sheep erythrocytes (by measuring serum CH50) and ii) cytotoxicity to cultured pig kidney (PK15) cells. The in vivo administration of FUT (at 0.2–25 mg/kg/h i.v. continuously) and K76 (50 mg/kg i.v. bolus) allowed evaluation of the serum levels of these drugs. Both FUT and K76 inhibited serum CH50 in a concentration-dependent manner. An enhanced effect was obtained by combining K76 with FUT therapy. High concentrations of FUT (>10^-4 M) and K76 (>10³ μxg/ml) were necessary to suppress serum CH50 to <5% of the normal level. However, PK15 cytotoxicity remained at >50% in the presence of i) 10^-4 M of FUT, ii) 10³ μg/ml of K76, and iii) 10^-6 M of FUT + 10³ μg/ml of K76. Pig heart transplantation (HTX) was performed in two baboons receiving FUT (1 mg/kg/h i.v. continuously) and K76 (at 200 mg/kg ×1 or 400 mg/kg + 200 mg/kg × 2 i.v, respectively). Cytotoxicity of the serum to PK15 cells at the time of HTX showed 39% and 1% cell death, respectively, in these two baboons, and the CH50 level was 1% (of control level) and 0%, respectively. Graft survival was 4.5 hours and 10 hours (with death of the baboon), respectively (compared with a mean of 29 minutes in control experiments). Both excised grafts showed typical features of hyperacute rejection. Immunopathological studies revealed deposition of C1q, C3d, C6, properdin, and Factor B, demonstrating that complement activation was not fully inhibited by FUT and K76. We conclude that i) FUT and K76 are indeed potent complement inhibitors, ii) the dosages of FUT and K76 necessary to suppress complement-mediated injury cannot be extrapolated from previously reported data obtained from serum CH50 levels, and iii) higher (possibly toxic) dosages will be required to inhibit complement activation completely. It seems unlikely that HAR will be prevented by these drugs alone, although they may be beneficial when combined with other forms of therapy.     

Exploring pupils' perceptions of the effects of residential schooling on children with emotional and behavioral difficulties

This paper is concerned with a study that was carried out into the effects of residential schooling on boys of secondary school age with emotional and behavioral difficulties (Cooper, 1989). The particular and original focus of the study was pupil experience in two residential schools as revealed through the perceptions of the pupils themselves. The paper reports the reasons for mounting such a study, the methodology used, and the conclusions reached. It is suggested that there is an urgent need for further qualitative studies of this type in this and other areas of special education.Reprinted with permission fromTherapeutic Care and Education, Vol. 1, No. 1, Spring 1992, 22–34.     

The poor quality of early evaluations of magnetic resonance imaging

To study the quality of early research on the clinical efficacy of diagnostic imaging with magnetic resonance, we assessed 54 evaluations published in the first four years after introduction of this modality using ten commonly accepted criteria of research methodology. The terms sensitivity, specificity, false-positive or false-negative, accuracy, and predictive values were used infrequently. Nineteen percent of the evaluations used three terms appropriately, 48% used one or two terms, and 33% used none. Data were presented appropriately for one or more of the five terms in 59% of evaluations. A "gold standard" comparison with the results of an independent procedure, such as surgical or autopsy findings, was presented in 22% of evaluations. Results of another imaging procedure were described in 63% of evaluations. Only one evaluation clearly described a prospective study design, although 11 evaluations apparently were planned in advance. Not one evaluation contained an appropriate statistical analysis of the distributions of quantitative readings, "blinded" image readers to diagnosis or other test results, measured observer error, or randomized the order of magnetic resonance imaging and other imaging procedures. We conclude that health care professionals paying for expensive innovative diagnostic technology should demand better research on diagnostic efficacy.     

Profound pulmonary shunting without edema following stereotaxic biopsy of hypothalamic germinoma. Case report

Hypoxemia is a nearly constant accompaniment of head injury. Diverse theories have been proposed to explain this relationship. The authors report the case of a patient who suffered an episode of severe, transient, arterial oxygen desaturation during "controlled" brain trauma: an otherwise uneventful stereotaxic biopsy of a small germinoma of the hypothalamus. Evidence is provided that pure ventilation-perfusion mismatching, without pulmonary edema, underlay the hypoxemia. The hypothalamus is intimately involved in matching pulmonary ventilation to perfusion; the hypoxemia of various brain injuries may be mediated by perturbation of this structure.     

Independent living and the physical environment: aspects that matter to residents

Field interviews were conducted with seven clients with disabilities for the purpose of developing design guidelines for apartments suitable for independent living. Analysis of these data generated six factors that were highly valued and felt to contribute to the success of these individuals' venture into community living. Control appears to be the central construct and to subsume the other concepts: safety/security, accessibility/mobility, function, flexibility and privacy. These findings are presented and discussed here as a working model of environmental control. These ideas are suggested as hypotheses which would need to be tested and refined further before being used as a model to guide clinical interventions.     

Rudimentary meningocele: a variant of "primary cutaneous meningioma"

We studied 5 primary cutaneous meningiomas. All were congenital. Four were nodules or plaques on the scalp, and one was a lumbar polyp. Two were alopecic. A skull defect was present deep to one lesion, and the lumbar polyp was attached to dura. The tumors were concentrated in the subcutis, where strands of meningocytes were embedded in dense collageous tissue. Meningocytes wrapped around collagenous fibers, producing "collagen bodies". These formed the nidus for calcification that included psammoma bodies. Meningocytes also dissected between collagenous fibers, creating anastomosing spaces that mimicked a vascular tumor. Meningothelial-lined clefts, several milimeters in length, were present in 4 cases. Two lesions extended through dermal defects into the superficial dermis, where adnexa were reduced or absent. The meningocytes contained vimentin and epithelial membrane antigen. They lacked cytokeratin, S100 protein, and endothelial markers. The meningothelial lesions described herein lack the nodular and sheet-like growth patterns that typify meningiomas of the central nervous system and most primary ectopic meningiomas, including some that develop within the skin. They appear closely related to meningoceles and should be viewed as developmental abnormalities rather than neoplasms. The term "rudimentary meningocele" seems appropriate for these lesions.     

Who manages the managers? The 1989 Harvey Cushing oration

New medical knowledge is emerging at a tremendous rate. Diseases such as Alzheimer's disease. Parkinson's disease, cancer, and others (diseases once considered beyond the scope of medicine) are receiving a great deal of attention. Yet it is a paradox that, at a time when we are learning more about the biology of the human being, it is more difficult to creatively develop the new knowledge into diagnostic tests, surgical interventions, and preventive strategies. The pace of biomedical innovation is being slowed by an increase in the intervention of nonmedical "managers of care." The driving force behind managed care is concern over cost. The managers of medical care have sought to control costs by controlling the doctor's decision making. This is the focus of managed care. The physicians of today, therefore, face a remarkable challenge. They must respond to the needs of patients while being held accountable to an increasing number of overseers in the public and private sectors. These managers of care justify their activities on the notion that the patient will be better off and the cost less if the doctor-patient encounter is regulated by protocols, statistical comparison, utilization review, and fee schedules. While doctor's decisions are being managed by others, who is managing the managers? The answer should be the medical community, principally doctors. Unfortunately, the answer at the moment is the payors--governmental reimbursement agencies, intermediaries, employers, hospitals, or new corporations designed to manage medical costs. The challenge to the physician is to retain the responsibility for those things for which he or she is held accountable. The challenge should not be ignored.     

The biology and tumour-related properties of monocyte tissue factor

Tissue factor (TF, coagulation factor III, CD142) is not only the main physiological initiator of normal blood coagulation, but is also important in the natural history of solid malignancies in that it potentiates metastasis and angiogenesis and mediates outside-in signalling. TF is expressed constitutively by many tissues which are not in contact with blood and by other cells upon injury or activation; the latter include endothelial cells, tissue macrophages, and peripheral blood monocytes. It can exist encrypted and unavailable functionally in the plasma membrane and the appearance of functional TF may be due to synthesis and/or de-encryption. Inflammatory cells often express TF and act to induce its production or de-encryption by other cells locally and, apparently, at remote sites. Inappropriate expression of TF by endothelial cells, macrophages or monocytes is thought to be an important trigger of coagulation in various pathological conditions. Several studies have shown that measurements of monocyte TF (mTF) may provide clinically significant information, particularly in patients with malignant and inflammatory diseases.