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Biomedical subjects

J Walker

Publications and source records attributed to J Walker.

At least 325 records · Page 18Linked to original sources
PubMed1990

The use of molecular probes to distinguish new primary tumors from recurrent tumors in gynecologic malignancies.

This is the first report using DNA molecular probe technology to distinguish between recurrent tumor and a second primary malignancy in a patient. Tumor DNA was extracted from squamous cell carcinoma of the cervix at the time of radical hysterectomy. Eighteen months later a squamous cell cancer was found in a vaginal apex biopsy from which DNA was extracted. Tumor DNA from both lesions was subjected to restriction enzyme digestion and DNA molecular hybridization with human papillomavirus (HPV) probes. Although both lesions were positive for HPV 16, their respective restriction enzyme patterns had different HPV genetic arrangements, thereby demonstrating their distinctness.

Adult↗
PubMed1990

Pathogenesis of colonization and infection in a neonatal surgical unit.

Nosocomial infection with aerobic Gram-negative bacilli is a major cause of morbidity and mortality in neonates. Few prospective studies have been undertaken in neonatal surgical units to investigate colonization and infection rates and the pathogenesis of infection. We prospectively studied 40 infants admitted to a neonatal surgical unit. Ninety-eight percent became colonized in throat/intestine with aerobic Gram-negative bacilli. Thirty-five percent developed infections, with wound and surface infections predominant (61%). Ninety-one percent of infections were caused by Gram-negative bacilli or yeasts. Severe infections (septicemia, pneumonia, meningitis) occurred in 13% of infants. The mortality rate was 5%. In all infections, the pathogenesis was found to be endogenous, and in most, three stages were distinguishable. Neonates always acquired potentially pathogenic organisms in throat/intestine (stage 1) before colonization (stage 2) and infection (stage 3) of other systems occurred. Reduction of digestive tract colonization by these potentially pathogenic microorganisms by means of successful selective decontamination may therefore reduce subsequent infection.

Bacterial Infections↗
PubMed1990

Multiaxis cyclic biomechanical testing of Harrington, Luque, and Drummond implants.

The performance characteristics of Harrington-Moe distraction rods, paired wired Luque rods and Drummond's system were evaluated and compared when subjected to nondestructive cyclic, multidirectional biomechanical testing. Twelve fresh, frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing machine. The instrumented spines were subjected to 207 kN/m2 compression and 49 N-m torsion. Each spine was cycled 28,000 times at 1 cycle per second. Linear and angular displacements were determined by digitizing photographs and video tapes made during testing. A computer program developed and refined for the project was used to complete the data analysis. Approximately 540 items of angular and linear displacement data were collected for each spine. Inspection of the spines after cyclic, multidirectional testing revealed no change in their osteoligamentous integrity compared with pre-testing. Pre- and post-testing radiographs showed no evidence of osseous failure, hook dislodgement or wire breakage. Erosion of laminal bone at the Harrington hook attachment sites was observed. Displacement of the Harrington hooks was seen during off-axis compression-torsion testing. Fretting and deposit of metal wear debris occurred between the sublaminal wires and "L" rods. There was no evidence of loosening of either the Drummond or Luque implants or fatigue failure of any component. Analysis of the linear and angular displacement data showed that the Luque and Drummond instrumented spines displaced less in axial compression, off-axis compression and off-axis compression-torsion than the single Harrington-Moe distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

The expression of gamma delta T cell receptor and the prevalence of primed, activated and IgA-bound T cells in Behçet's syndrome.

Mucosal ulceration of the oral, and to a lesser extent genital tissues is an essential feature of Behçet's syndrome and is associated with changes in the IgA class of immune responses. Indeed, a significant increase in the proportion of cytophilic IgA1 was found in circulating CD8 and CD4 cells (P less than 0.01), with a corresponding decrease in IgA-Fc receptors on these T cells. Furthermore, 30-40% of the cytophilic IgA1 on T cells may have been of the polymeric secretory type and the rest of the monomeric variety. IgA isotype of B cells was also significantly increased (P less than 0.001), without an overall change in circulating B cells. However, a surprising finding was the significant up-regulation of gamma delta T cell receptor in the CD8 (P less than 0.01) in the absence of a change in the proportion of alpha beta T cell receptor. The results suggest that some common microbial antigen might initiate at the mucosal surface an immune defence reaction characterized by T cells with gamma delta receptors and IgA-specific B cells. However, IgA1 bound to circulating T cells may down-regulate the central T cell function.

Adult↗
PubMed1990

The unexpected relocation of elderly in-patients in response to a threatened strike.

A threatened strike by non-professional hospital employees caused a teaching hospital to halve its in-patient numbers. This paper describes this unexpected, involuntary intervention in patient care in the Department of Geriatric Medicine. Fifty-three patients were discharged, 46 patients were transferred for 12 days to another hospital and 29 remained in the department. There was no evidence of important disruption in patient-care nor exacerbation of patient-distress as seen in ratings of patients' social, emotional and physical functioning. It is suggested that important factors in achieving successful unexpected relocation are: selection of patients who are medically stable albeit with significant physical and mental disability; the preparation and participation of patients and staff; and the continuation of patient care by nursing staff familiar to the patients.

Aged↗
PubMed1990

The relationship between beliefs about nutrition and dietary practices of the elderly.

Data were collected from home interviews of 424 noninstitutionalized individuals, 58 to 100 years old, in the Houston metropolitan area, to assess the relationships between dietary intake, socioeconomic variables, beliefs about nutrition, and use of nutritional supplements. Two-thirds of the subjects took nutritional supplements. The most common forms were vitamin C, calcium, and multivitamins. With the exception of vitamin B-6, magnesium, and dietary fiber, which were higher in diets of users of nutritional supplements than in diets of nonusers, nutrient density (amount of nutrient per 1,000 kcal) did not differ between the two groups. Attitudes toward the use of nutritional supplements, health foods, and/or nutritional quality of conventional foods differed with sex, age, income, and educational level. Nutrient intake of those with more positive feelings about nutritional supplements was higher, perhaps as a result of increased awareness of diet and health. Nutrition education that is targeted to issues of interest to people in this age group is needed; topics such as the role of nutrients in disease prevention and appropriate nutritional supplementation might be explored. This survey indicates that, although the practice of supplementation may be beneficial to augment nutritional quality of the diet for elderly people, use of nutritional supplements is not restricted to those whose dietary intake is of lower nutrient density than that of nonusers.

Age Factors↗
PubMed1989

Photodynamic therapy for cutaneous and subcutaneous malignant neoplasms.

Twenty-seven patients with cutaneous and subcutaneous malignant neoplasms were treated with photodynamic therapy. Therapy was administered to 248 areas during a total of 72 separate treatment sessions after patients received a total of 45 injections of sensitizer. Seven patients had basal cell carcinoma, three had squamous cell carcinoma, three had malignant melanoma, one had liposarcoma, and 12 had breast cancers. One patient had Bowen's disease. Treatment was given either by surface radiation or interstitially. One month after treatment, 48 (67%) of the treatment sessions resulted in a complete response (no clinical evidence of tumor), and 19 (26%) resulted in a partial response (greater than 50% reduction in the number or size of tumors). Fifteen patients were examinable 12 months after treatment, and in this group, 31 treatment sessions were evaluated as a complete response one month after therapy, 15 (48%) of which retained this status at one year after treatment. By comparing the ability of different light-delivery instrumentation, it was concluded that the Yellow Springs radiometer (Yellow Springs Instruments, model 65A, Yellow Springs, Ohio) provided the most reliable spot power density readings. Straight-tipped fibers are nonhomogeneous and can result in overtreatment of the central area with necrosis and pain and in undertreatment of the periphery.

Humans↗
PubMed1989

Management of endobronchial tumors: a comparative study.

Between September 1982 and July 1987 we treated 102 patients with endobronchial or endotracheal disease with one or a combination of the following modalities: CO2 laser, Nd:YAG laser, and photodynamic therapy (PDT). Many patients had multiple treatments and treatment sites. In all, 259 Nd:YAG treatments were performed on 154 sites in 80 patients, 118 PDT treatments were performed on 87 sites in 45 patients, and nine CO2 treatments were performed on nine sites in nine patients. Of the 71 patients who died, 19 lived longer than 6 months, and seven lived longer than 1 year. A total of 11 patients have survived for more than 1 year, including four who are still alive 18, 22, 33, and 54 months after treatment. Five patients achieved a status of "no evidence of disease," and at autopsy, two others had no evidence of disease to the treated site. All seven of these patients were treated with PDT only. There were no intraoperative deaths or cases of intraoperative bleeding or smoke with PDT. Eight patients died from pulmonary hemorrhage 2 to 9 weeks after treatment. Four had been treated with Nd:YAG therapy alone and four with PDT alone. Evaluation of the survival rate in this study must consider that this therapy involves severely ill patients with a high potential for intraoperative or perioperative fatality. Some patients who were near death before treatment have enjoyed quality survival for over 1 year.

Adult↗
PubMed1989

Diabetic choroidal and iris vasculature scanning electron microscopy findings.

Scanning Electron Microscopy (SEM) was used to study vascular casts of twenty-four autopsy eyes taken from patients with long-standing insulin-dependent Diabetes Mellitus. These casts were compared to casts of ten 'normal' autopsy eyes from patients without a history of diabetes or other vascular disease. The SEM findings in the choroidal vessels of the diabetic eyes included: increased tortuosity, focal vascular dilations and narrowings, hypercellularity, vascular loops and microaneurysm formation, 'drop-out' of choriocapillaries, and sinus-like structure formation between choroidal lobules in the equatorial area. In the iris, neovascularization was evident in the vascular casts in cases with clinically recognized rubeosis iridis. These findings indicate that there is significant involvement of the uveal tract in diabetic eyes. The present study strongly supports the Hidayat and Fine light microscopic observation that the diabetic choroid demonstrates significant vascular changes (e.g. narrowed vessels with possible 'drop-out' of capillaries and neovascularization). Changes in the diabetic choroid, especially in the choriocapillaris, may be a contributing factor in diabetic retinopathy, resulting in decreased oxygenation of the outer layer of the retina. Short reviews and updated information of diabetic eye disease provide some additional insights into the vascular problems in the eye.

Adult↗
PubMed1989

Prolonged hyperinsulinemia reduces plasma fatty acid levels in the major lipid groups in fetal sheep.

The offspring of women with poorly controlled diabetes have increased total body fat. Experimental fetal hyperinsulinemia has previously been associated with increased fat accumulation in rhesus monkey fetuses and increased lipid content and lipogenesis in rat fetuses. We hypothesized that prolonged fetal hyperinsulinemia would alter plasma total fatty acids and the individual fatty acids in each major lipid group. Fatty acids determined by gas-liquid chromatography were measured in the arterial blood of 12 chronically catheterized fetal sheep after 10 to 12 days of insulin (n = 7) or placebo (n = 5) infusion. Plasma concentrations of insulin were 412 +/- 63 microU/ml and 9 +/- 3 microU/ml (mean +/- SE) in the insulin- and placebo-treated fetal sheep, respectively. Prolonged fetal hyperinsulinemia was associated with lower circulating total fatty acid levels in each lipid class except cholesterol esters. Although the precursor of arachidonic acid, 18:2 (linoleic acid), was not decreased in any lipid class, insulin infusion was associated with reduced arachidonic acid in each lipid class. We conclude that prolonged fetal hyperinsulinemia decreases circulating total fatty acid and the individual fatty acids in each of the major lipid classes, except for the cholesterol esters. We speculate that these reductions in circulating fatty acids represent an insulin-mediated increase in tissue deposition.

Animals↗
PubMed1989

Effects of sex, thyro-parathyroidectomy, and light regime on levels and circadian rhythms of wheel-running in rats.

Intact and thyro-parathyroidectomized (TPX) Sprague-Dawley rats of both sexes were observed for 24 days under a 12:12 light:dark cycle (Entrainment), followed by 20 days in constant dim red light (Free-Run). Circadian periods and levels of wheel-running activity were examined. Intact females and TPX males were significantly more active and had significantly shorter free-running circadian periods than intact males, and the effects of TPX in females were different from those in males. Circadian periods in TPX females were slightly, but not significantly, shorter than in intact females, and activity levels in TPX females were nonsignificantly depressed relative to intact females. It was also found that day versus night activity levels differed more in TPX animals than in intact animals, especially during entrainment, suggesting that TPXs may be more sensitive to some effects of light. A number of possible explanations for the effects of TPX are considered, including changes in thyroid and calcitonin levels, interactions with gonadal hormones, and possible developmental effects of thyroid hormones on the circadian system. It is also possible that rhythm changes are secondary to alterations in activity levels. Human manic depressives reportedly have an unusually high incidence of thyroid, parathyroid, and calcium regulation abnormalities, display shortened circadian sleep-wake rhythms and abnormal levels of activity, and may also be hypersensitive to some effects of light; in addition, depression predominates in women, whereas mania predominates in men. The present results suggest that thyroid dysfunction could be partially responsible for the some of these abnormalities, and for sex differences in the manifestations of these disorders.

Animals↗