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Biomedical subjects

R L Nelson

Publications and source records attributed to R L Nelson.

At least 91 records · Page 5Linked to original sources
PubMed1990

Blood conservation techniques in orthopaedic surgery.

In summary, reduction of blood loss and coincidental decrease in the number of blood transfusions is now of paramount importance in orthopaedic surgery. Methods to reduce blood loss include preoperative planning, hypotensive anesthesia, and meticulous surgical technique. If transfusion is necessary, autologous replacement is always preferable. Overall, the goals in blood conservation in surgery are first to decrease the amount of blood lost, and second to be sensible in replacement of this loss.

Blood Transfusion↗
PubMed1990

The effect of mild stress on DMH-induced colorectal cancer.

Epidemiologic studies suggest that certain psychosocial factors increase the risk of cancer. Yet, animal studies suggest that psychosocial stress inhibits the development of chemically induced tumorigenesis. The purpose of this study was to examine the effect of three different chronic mild stressors on the development of dimethylhydrazine (DMH)-induced colorectal carcinoma in rats. Results of this study show that the development of DMH-induced colorectal carcinoma was not significantly inhibited or altered by each individual stress treatment. Additionally, results indicate that mild stressors can induce neurochemical changes commonly associated with stress, without the confounding effects of more aversive stressors that are likely to compromise the nutritional and physiological status of the animal and thereby alter tumor formation.

1,2-Dimethylhydrazine↗
PubMed1989

Human genotoxicity: pesticide applicators and phosphine.

Fumigant applicators who, 6 weeks to 3 months earlier, were exposed to phosphine, a common grain fumigant, or to phosphine and other pesticides had significantly increased stable chromosome rearrangements, primarily translocations in G-banded lymphocytes. Less stable aberrations including chromatid deletions and gaps were significantly increased only during the application season, but not at this later time point. During fumigant application, measured exposure to phosphine exceeds accepted national standards. Because phosphine is also used as a dopant in the microchip industry and is generated in waste treatment, the possibility of more widespread exposure and long-term health sequelae must be considered.

Chromosome Aberrations↗
PubMed1989

A case-control study of large bowel cancer and hormone exposure in women.

Several lines of evidence indicate a potential role for hormonal or reproductive factors in the subsequent development of large bowel cancer in women. To evaluate the relationship between hormone exposure and large bowel cancer a case-control study was carried out in 18 Illinois hospitals. Female cases, ages 45-74 (n = 90), and controls (n = 208) were identified from an ongoing large bowel cancer study. Data were obtained from medical records, personal interviews, and a subsequent mail survey with a questionnaire specific to hormone usage. Menopausal estrogen use was found to be protective with respect to the subsequent development of large bowel cancer with an odds ratio of 0.6 (95% CI, 0.33-0.99). This effect remained after controlling individually for age at diagnosis, ever pregnant (yes/no), parity, age at first birth, hysterectomy with documented oophorectomy, cholecystectomy, and appendectomy. Simultaneous adjustment, using logistic regression, for age at diagnosis, parity, hysterectomy, and cholecystectomy resulted in an adjusted odds ratio for menopausal estrogen use and large bowel cancer of 0.5 (95% CI, 0.27-0.90). Subsite analysis revealed the protective effect to be strongest for the rectal cancer cases. These data support the hypothesis that exogenous hormones may alter the risk of large bowel cancer in women.

Adenocarcinoma↗
PubMed1989

Quantitative electron microscopic study on grades of atypia in adenomas of the human large bowel.

Clarification of the ultrastructural features of the three different grades of histologic atypia of adenomas (i.e., mild, moderate, and severe atypia) with reference to carcinoma of the human colon and rectum was undertaken using electron microscopic quantitative analysis. Ten normal epithelia, 36 adenomas (14 with mild atypia, 13 with moderate atypia, and 9 with severe atypia) and 14 carcinomas (well-differentiated adenocarcinoma) were examined with light and electron microscopes. Although it has been generally accepted that malignant transformation of an adenoma gradually proceeds with increasing atypia, using light microscopy, ultrastructural quantitative analysis clearly revealed that fine features of individual atypia did not correspond with histologic grades of atypia. Ultrastructural changes occurred abruptly in moderate atypia and showed similar cellular characteristics to carcinoma cells. Mild atypia was almost similar in appearance to normal epithelial cells. Striking changes in the moderate atypic cells were plane apposition of the cell membrane, decrease of the desmosomes, and increase of the lysosomes. These atypical cells were assumed to play a significant role in the adenoma-carcinoma sequence. Therefore, radical surgical therapy would be required for moderate atypic adenoma of the large bowel that is difficult to remove endoscopically.

Adenocarcinoma↗
PubMed1989

Traumatic cloaca.

Deep laceration of the perineum after an obstetric injury may result in a cloacal deformity of the anus and vagina, causing complete fecal incontinence. A surgical technique consisting of reconstruction of the perineal body (perineoplasty) with puborectalis interposition and overlapping external sphincteroplasty is described to correct the defect and restore continence. This procedure has been used on 43 patients in a 10-year period with excellent anatomic and physiologic results.

Adolescent↗
PubMed1989

Allografting for traumatic intercalary femoral defects: a report of three cases.

Fewer than 10 cases of allografts used to fill traumatic massive skeletal defects have been reported (10). The threat of infection following an open fracture is the greatest concern when using allografts to fill these defects since allografts are massive necrotic bone fragments and remain so for prolonged periods of time. Three patients with traumatic intercalary femoral defects treated with allograft substitution were followed until bony union. Two of the patients experienced complications related to the allografts. However, both of these patients have returned to work with painless lower limbs. The third has healed and returned to a more sedentary occupation.

Adult↗
PubMed1989

Cocaine-induced acute aortic dissection.

While cocaine-induced myocardial infarction has been frequently documented, the differential diagnosis of chest pain should include aortic pathology. The successful management of acute aortic dissection secondary to cocaine abuse has not been previously reported to our knowledge. In a 45-year-old man who presented with typical chest pain and wide mediastinum, the successful management of this disease included early and accurate diagnosis and replacement of the aortic valve as well as the torn portion of the ascending aorta.

Aortic Dissection↗
PubMed1989

Pyoderma gangrenosum and adrenocortical carcinoma.

Systemic disorders that have been associated with pyoderma gangrenosum include inflammatory bowel disease, rheumatoid arthritis, paraproteinemias, and hematologic malignancies. We report the case of a 55-year-old woman with pyoderma gangrenosum, IgA monoclonal gammopathy, and a cortisol-secreting adrenocortical carcinoma. Review of the literature revealed one previous case of pyoderma gangrenosum associated with a solid tumor; at autopsy, a carcinoid tumor and an adrenocortical adenoma were found. Our patient's rapid improvement after the carcinoma was resected and her subsequent disease-free course suggests that the two conditions were related. This case suggests that evaluation for underlying malignancy should be considered in patients with pyoderma gangrenosum.

Adrenal Cortex Neoplasms↗
PubMed1988

Adenylate cyclase activity and cyclic adenosine monophosphate levels in colon cancer lines and dermal fibroblasts and the effects of cholera toxin and epidermal growth factor.

The intracellular concentration and rate of cyclic adenosine monophosphate (cAMP) synthesis, as measured by adenylate cyclase (AC) activity, were measured in dermal fibroblast cultures, colon cancer lines, and cells cultured from colonic epithelium and colonic adenomas. Dermal fibroblasts had higher AC activity and intracellular cAMP levels than the colon cancer lines (p less than 0.05). Benign colonic epithelial cultures (mucosa and adenomas) had AC levels similar to those found in dermal fibroblasts. To characterize further these observed differences, similar measurements were made in cultures incubated in cholera toxin (CT) or epidermal growth factor (EGF). CT stimulated AC activity and cAMP accumulation in both cancers and fibroblasts. EGF had no effect on AC activity in cancers or fibroblasts, and no effect on cAMP concentration in cancer, although EGF incubation did increase intracellular cAMP in fibroblasts. Dermal fibroblasts from colon cancer-prone patients had AC activity and cAMP concentration not significantly different, though greater, than fibroblasts from healthy individuals. Therefore, although the product of the oncogene associated with colon cancer has been shown to be an activator of AC in yeast, in human colon cancer, AC activity and intracellular cAMP concentration were much lower than in dermal fibroblasts. This difference was so great that AC activity and intracellular concentration of cAMP might be biochemical markers that can be used to differentiate colon cancer from benign cells in tissue culture.

Adenoma↗
PubMed1988

The protean manifestations of familial polyposis coli.

Although familial polyposis coli (FPC) is often thought to be a discrete disease with uniform clinical presentation and few therapeutic options, review of 16 families encountered in the last five years has shown that marked variation in the clinical manifestations of the syndrome is the rule rather than the exception. Thirty one percent of propositi had negative family histories, 67 percent of observed cancers were in the rectum, three individuals from three families developed cancer under the age of 20. In another family the only cancer was in a 67-year-old patient. Polyp growth rate varied tremendously among individuals and over time within individuals, rectal polyps did not regress after subtotal colectomy, and three patients developed rectal cancer after subtotal colectomy (18 percent). Fifty percent of propositi had cancer on presentation, while only 18 percent of screened family members had cancer. The only extracolonic tumors seen were gastroduodenal polyps and retroperitoneal desmoids in three families. The mode of inheritance of FPC causes this variation and treatment is best tailored to the individual and his family rather than uniformly applied to all patients with FPC.

Adenomatous Polyposis Coli↗
PubMed1988

Oral glucose tolerance test: indications and limitations.

The oral glucose tolerance test has been used in many clinical situations. From a practical standpoint, however, it has limited applicability. The test should never be done to evaluate reactive hypoglycemia. It can be used in the patient whose fasting plasma glucose level is less than 140 mg/dl but who manifests symptoms compatible with complications of diabetes. Finally, all pregnant patients should undergo testing for gestational diabetes with a 50-g glucose screen at 24 to 28 weeks of pregnancy, and a subsequent glucose tolerance test should be performed if the result of that test is abnormal.

Blood Glucose↗
PubMed1988

A comparison of dietary fish oil and corn oil in experimental colorectal carcinogenesis.

Rats fed either fish oil (n = 16) or corn oil (n = 16) in calorically and nutritionally balanced diets were injected with 1,2-dimethylhydrazine, which is a colorectal specific carcinogen; differential colorectal tumor induction was then measured. In addition, plasma peroxide concentrations were measured in rats in each dietary group as well as in a group receiving a low-fat diet, either with or without prior carcinogen treatment (n = 3 for each of the 6 groups). Tumor incidence did not differ between groups fed corn oil and fish oil. Tumor yield in the left colon was significantly lower in rats fed fish oil (p = 0.0499). Total colorectal tumors induced were also fewer in the rats fed fish oil (p = 0.065). Plasma peroxide concentrations were difficult to interpret because of the wide variation within groups. The data on tumor yield in the left colon support the hypothesis that a diet rich in n-3 fatty acids, which are found in fish oil, may be less supportive of colorectal tumor development than a diet rich in n-6 fatty acids, which is found in corn oil. However, the mechanism by which fish oil decreases tumor induction is still unknown.

1,2-Dimethylhydrazine↗
PubMed1988

Chromosomal and c-K-ras oncogene alterations induced by a chemical carcinogen and phorbol ester in skin fibroblasts of individuals with familial polyposis coli.

Skin fibroblasts derived from three patients with familial polyposis coli (FPC) were treated in vitro with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) alone or in combination with the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). None of the cultures treated four times with MNNG alone (1 microgram/ml) or in combination with TPA (eight applications, 0.1 microgram/ml each) showed either morphological transformation or anchorage-independent growth for 18 months after treatments. FPC cells treated with MNNG alone showed cell growth inhibition, breakage and loss of chromosomes, as well as the deletion of 5.7 kilobase (kb) EcoRI fragment in the c-K-ras locus as detected by Southern blot analysis with v-K-ras specific probe (clone KBE-2). The control cells contained two EcoRI fragments of 5.7 and 4.2 kb. On the other hand, cells treated with MNNG first and then followed by treatment with TPA not only showed an increase in the rate of cell growth but also exhibited two novel EcoRI fragments of 9.4 and 12 kb. Treatment with TPA alone appeared to stimulate cell division long after application and to induce chromosomal aberrations but had no effect on c-K-ras sequences. The most likely explanation for the appearance of chromosome pulverization and hyperploidy in FPC cells treated with TPA is the induction of premature chromosome condensation of the S phase cells due to fusion with the mitotic chromosomes.

Adenomatous Polyposis Coli↗
PubMed1988

Effect of activity-stress on experimental rat colon carcinogenesis: early histopathologic changes and colon tumor induction.

The effect of stress on experimental colon carcinogenesis was investigated in the rat by adapting the activity-stress ulcerogenesis model to the 1,2-dimethylhydrazine (DMH) rat colon carcinogenesis model. Activity-stress was applied intermittently (normal housing conditions alternated with activity-stress conditions on an equal time basis) to DMH-injected rats either throughout the experiment (AS-DMH) or following completion of DMH injections (DMH-AS). The AS-DMH treatment was associated with reduced colonic tumor induction compared with controls, as was to a lesser degree with DMH-AS condition. In a separate study, the early histopathologic effects on the colon of a single DMH injection, an activity-stress treatment, or the combination of both DMH and activity-stress treatments were compared with those of controls. Activity-stress moderated DMH-induced increases in colonic epithelial cell proliferation and nuclear hyperchromia when compared with DMH treatment alone. The findings of activity-stress-associated protection on colon tumor induction and the concordance of these results with quantitative early histopathologic alterations demonstrate that in the rat activity-stress exerts a protective influence in colon carcinogenesis. In addition, these results suggest further that risk modifiers of colon cancer can be assessed in short-term studies that quantify early histopathologic alterations.

Animals↗
PubMed1987

Non-insulin-dependent diabetes mellitus. Current status of oral hypoglycemic therapy.

Proper treatment of non-insulin-dependent (type II) diabetes presents the physician with a number of choices. Diet and exercise should be tried first in many patients; if this regimen is unsuccessful, treatment with either insulin or a first- or second-generation sulfonylurea must be considered. Theoretically, second-generation agents are more advantageous than first-generation agents because they do not interact with other drugs. I do not believe that they are more efficacious, however, and they probably do not have fewer side effects if chlorpropamide (Diabinese) is eliminated from consideration. Future well-designed crossover studies may help to clarify this issue. Combined insulin and sulfonylurea therapy can be tried in obese patients resistant to large doses of insulin, although results are not dramatic. In all patients the goal is to reach acceptable fasting glucose levels and near-normal glycosylated hemoglobin values.

Blood Glucose↗