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Biomedical subjects

R L Nelson

Publications and source records attributed to R L Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1987

The effect of dietary milk and calcium on experimental colorectal carcinogenesis.

This investigation was based on an epidemiologic association of milk consumption and decreased intestinal cancer risk. Furthermore, there is also some indirect evidence that calcium supplementation in humans and animals may decrease colon cancer risk and that calcium, by inference, may be the protective factor in milk. In order to investigate these associations in a controlled laboratory setting, dietary supplementation of low fat dried milk (37 g/kg diet; N = 18) and calcium carbonate (40 mg/kg rat/day; N = 17) were compared separately to regular diet controls in the rat-dimethylhydrazine colon carcinogenesis model. The results of this investigation showed that neither milk-supplemented rats nor calcium carbonate-supplemented rats had fewer DMH-induced colorectal (P = .374) or total gastrointestinal tumors (P = .291) than did regular diet controls (N = 10; by analysis of variance [ANOVA]). Milk supplementation did result in a significant decrease in tumor burden when measured by incidence of metastases (P = .035) and of intestinal obstruction (P = .011; by chi-square test), when compared with calcium-supplemented and control rats. Though this implies that milk supplementation provides protection against some aspects of carcinogenesis of the colon, in rats fed low fat diets, this does not appear to be mediated through the calcium content of milk.

Adenocarcinoma↗
PubMed1987

Host-mediated transformation: metronidazole.

To evaluate the possible genotoxic effects of the drug, metronidazole in the fetus, we employed the hamster embryo host-mediated assay. Pregnant golden Syrian hamsters were fed metronidazole at doses ranging from 200 mg/kg to 900 mg/kg on days 11 and 12 of pregnancy. Embryonic cells obtained from the treated animals were studied in vitro for morphologic evidence of transformation. To further assess the significance of the in vitro finding, cells from mass culture were tested for their ability to grow in soft agar. The drug-treated cells and cells previously treated with diethyl nitrosamine (positive controls) showed comparable growth characteristics. To confirm the neoplastic potential of the drug-treated embryonic cells, subcultivated cells from the tenth passage were implanted into nude mice and irradiated immunosuppressed hamsters. Cells from the 300 mg/kg treatment produced fibrosarcoma in nude mice but not in the irradiated hamsters. Cells from no other dose level employed in the study produced tumors in host animals. It is concluded that metronidazole is capable of vertical transmission of potential genotoxic effects to the fetus.

Animals↗
PubMed1987

The impact of Medicare coverage on the PA profession.

Federal legislation that took effect on January 1 provides for Medicare part B reimbursement for physician assistant services in several clinical settings. Besides recognizing PAs' contribution to health care delivery, the law may greatly increase demand for PAs (especially in geriatric medicine), allow them to branch out to more nontraditional forms of practice, and prompt a need for a larger pool of graduates from PA education programs. This legislative victory does not diminish--but heightens--the profession's responsibility to show that PA services are cost-effective.

Medicare↗
PubMed1987

The interaction of retrovirus and chemical carcinogen in experimental colon carcinogenesis.

The isolation and characterization of oncogenes from human colon cancer and the recognition of their homology with the ras gene of the Harvey and Kirsten strain of murine sarcoma virus (MSV) led us to investigate the effect of exogenous MSV on 1,2 dimethylhydrazine (DMH)-induced colon carcinoma in rats. DMH, 20 mg base/kg, was injected weekly for 10 weeks into Sprague-Dawley rats. The Moloney murine sarcoma virus (MSV-M) was injected (200 focus-forming units) intraperitoneally into 15 rats 48 hours after the last DMH injection or in 12 rats before the first DMH injection. Controls consisted of 12 rats receiving 10 injections of DMH only, nine rats receiving MSV-M alone, and 10 untreated rats. All tumors induced were adenocarcinomas of the gastrointestinal tract, characteristically induced by DMH and not by MSV-M. In the late virus group there was an augmentation of colon tumor induction (mean, 2.2 versus 1.1 colon tumors/rat, p less than 0.05), and in the MSV pretreated group, there was also significant augmentation of colon tumor induction (mean, 2.4 versus 1.1 colon tumors/rat, p less than 0.005) when compared with rats treated with DMH alone. Rats treated with MSV-M alone and untreated rats had no tumors. This is the first study to suggest the importance of exogenous viral infection in chemically induced colonic carcinogenesis.

1,2-Dimethylhydrazine↗
PubMed1986

Clinical pharmacology of vinzolidine.

Vinzolidine (VZL), a new semisynthetic vinca alkaloid, was studied by using 3H-labeled VZL administered PO in four patients. At single doses from 1.5 to 36.5 mg/m2 (0.034-0.919 mg/kg) radioactivity was rapidly absorbed with a half-life of absorption of 1 h and a peak at 4 h. Plasma decay of radiolabel followed a biphasic pattern with an alpha half-life of 10.48 h and a beta half-life of 172 h. The apparent plasma clearance was dose-dependent. The total radiolabel recovered was 52.9% +/- 11.4% of the administered label, with 90% in the feces. HPLC analysis revealed that in all extracted plasma, urine, and feces the predominant material was unchanged VZL. Several metabolites were observed but not identified.

Dose-Response Relationship, Drug↗
PubMed1986

Lack of a direct effect of the autonomic nervous system on glucose-stimulated gastric inhibitory polypeptide (GIP) secretion in man.

To determine whether the autonomic nervous system has a direct effect on GIP secretion, six normal subjects received a 4-hr intraduodenal perfusion of glucose (225 mg/min) and polyethylene glycol on four successive days. During the latter 2 hr, either normal saline, propranolol, phentolamine, or atropine were infused intravenously. Glucose absorption was calculated by measuring glucose and polyethylene glycol following luminal aspiration distal to the perfusion site. Basal and peak or nadir values in the saline study of plasma glucose, insulin, glucagon, and GIP were similar to the other three studies prior to autonomic blockade. During the latter 2 hr of the glucose perfusion, the plasma glucose and glucagon responses to saline did not differ from responses to the three blocking agents. Phentolamine but not atropine or propranolol resulted in a greater insulin response compared to saline (3247 +/- 762 vs 1348 +/- 388 microU/ml/120 min, P less than 0.01). GIP was not significantly affected by phentolamine (18,146 +/- 4574), propranolol (7585 +/- 5854), or atropine (15,797 +/- 6297) compared to saline (11,717 +/- 5204 pg/ml/120 min). Glucose absorption was unaffected by infusions of saline, phentolamine, and propranolol, but was increased following atropine infusion (5841 +/- 1120 vs 1044 +/- 808 mg/120 min, P less than 0.02). There appears to be no direct effect of the autonomic nervous system on glucose-induced secretion of GIP.

Adult↗
PubMed1986

Perineal proctectomy, posterior rectopexy, and postanal levator repair for the treatment of rectal prolapse.

This report describes a one-stage perineal operation for the treatment of complete rectal prolapse aimed at restoration of anal continence in addition to resection of the prolapsed segment of rectum. This procedure was performed on 25 patients, most of whom were elderly or debilitated, over the past three years without local or systemic complications. Significant improvement in continence was seen in 88 percent of the patients within four weeks of operation, and in the remainder of the patients, within three months postoperatively.

Aged↗
PubMed1986

Serious complications of sulfasalazine.

Whereas minor side effects of sulfasalazine are common, serious adverse reactions to this drug generally are considered rare. However, this report discusses three major complications of sulfasalazine that occurred within the past three years, one resulting in the death of a patient. As more patients with inflammatory bowel disease are being managed by physicians of various disciplines, it is important to become familiar with the potentially dangerous side effects of all medications prescribed. For this reason, a brief review of the pharmacology, clinical use, and toxicity of sulfasalazine is presented.

Absorption↗
PubMed1986

Diabetes and pregnancy: control can make a difference.

In pregnant patients who have diabetes mellitus, metabolic control has been demonstrated to improve neonatal outcome considerably. All pregnant patients should be screened for gestational diabetes at 24 to 28 weeks of gestation with use of a glucose challenge test. Dietary therapy, and insulin therapy when appropriate, reduces the neonatal mortality associated with gestational diabetes to that of normal pregnancy. Macrosomia remains a problem, but aggressive use of insulin therapy may minimize this complication. Intensive control of insulin-dependent diabetes both before conception and during pregnancy is essential. The risk of congenital malformations can be reduced to that associated with normal pregnancy if diabetes is well controlled during the first 8 weeks of pregnancy. Neonatal survival, macrosomia, and hypoglycemia also are directly related to the degree of control of maternal diabetes during the pregnancy.

Birth Weight↗
PubMed1986

Establishing a flexible sigmoidoscopy/colonoscopy program for surgical residents. The University of Illinois experience.

The clinical value of lower gastrointestinal endoscopy and the requirement of the American Board of Surgery for endoscopic training mandate establishing a program in flexible sigmoidoscopy and colonoscopy for all surgical residents. In a 12-month period, the surgical residents at the authors' institution performed 599 flexible sigmoidoscopic and 116 total colonoscopic examinations under the supervision of two attending colorectal surgeons, with no mortality and a 0.03 per cent morbidity. There was an average of 42 endoscopic examinations per resident for the 3-week training period. Three hundred seventy (62%) of the flexible sigmoidoscopic examinations were for screening and 229 (38%) were for the evaluation of symptomatic patients. Colorectal polyps were identified in 68 patients (11.4%) and carcinoma in 14 patients (1.9%). Forty-nine per cent of the colonoscopic examinations were for endoscopic polypectomy. Sixty-four per cent of patients with more than one adenomatous polyp harbored polyps in different surgical segments of the colon. Every resident was able to perform flexible sigmoidoscopy safely by the end of the 3-week training period, and in addition, the residents rated their endoscopic experience as a valuable part of their surgical training.

Colonoscopy↗
PubMed1986

Integration of laboratory and epidemiologic studies to evaluate genotoxic exposure in tool and die workers.

In summary, the data presented here provides perspective on the analysis of cancer in a relatively small population of tool and die workers. Each part of the effort establishes evidence for or against the presence of a workplace carcinogenic effect. Overall, the weight of evidence leads to the hypothesis that cutting fluids are a likely candidate for observed increases in urinary system cancer and perhaps other sites. Because cutting fluids and a wide variety of metals are used together, the interaction of these entities need be considered in the overall process of carcinogenesis in the workplace.

Biotransformation↗
PubMed1985

Anal carcinoma presenting as a perirectal abscess or fistula.

In five years, 15 patients were seen with anal carcinomas presenting as perirectal abscesses or fistulas. Nine patients had acute abscesses without histories of chronic anorectal disease, and six patients had long-standing anorectal disease in which carcinoma developed. Operative exploration was needed to establish the diagnosis in all patients. Early definitive surgery would certainly have prevented most if not all of the cancers from developing in the group with chronic anorectal disease.

Abscess↗
PubMed1985

Ileoanal anastomosis 24 years after total proctocolectomy for ulcerative colitis.

The efficacy of constructing an ileal pouch in association with an ileoanal anastomosis after mucosal proctectomy has been well established. Ordinarily, the pouch is fashioned at the time of mucosal proctectomy. This report describes a patient whose end ileostomy was successfully converted to a J-pouch 24 years after intersphincteric resection of his rectum for ulcerative colitis. Postoperative anal manometric data are presented, and the potential for applying this operation to other patients who have had previous intersphincteric rectal resections is discussed.

Anal Canal↗
PubMed1985

Neither dietary ethanol nor beer augments experimental colon carcinogenesis in rats.

There is an epidemiologic association between beer consumption and rectal cancer. Beer and ethanol were tested in the rat-dimethylhydrazine (DMH) experimental carcinogenesis model in order to verify this observation. Ethanol was found not to affect the number of colonic tumors induced by DMH (86 vs. 77 controls, P = 0.764). In rats fed beer and treated with DMH, there was a decrease in gastrointestinal tumor induction (P = 0.043). This instance then becomes one of many in which conclusions drawn from epidemiologic studies have been contradicted when subjected to analysis in an experimental colon carcinogenesis model.

1,2-Dimethylhydrazine↗
PubMed1985

A unique late mechanical complication of jejunoileal bypass.

The consequences of jejunoileal bypass include not just metabolic derangements, though the frequency and severity of these problems have led to the procedure being abandoned in the treatment of morbid obesity, but a variety of mechanical complications as well. In this report, a new mechanical complication is presented: Intussusception of the defunctionalized ileum into the sigmoid colon, an intussusception caused by malignant lymphoma of the ileum. Because the patient had pain but no evidence of obstruction, the ileal tumor was fortuitously discovered during flexible sigmoidoscopy.

Adult↗
PubMed1985

Hypoglycemia: fact or fiction?

Many misconceptions continue to persist in both the lay and the professional literature regarding the proper approach to the diagnosis and treatment of hypoglycemia. Often, patients with a symptom complex suggestive of hypoglycemia have normal levels of plasma glucose in association with these symptoms. The major diagnostic error is the failure to document hypoglycemia (that is, record plasma glucose levels) at the time the patient is spontaneously symptomatic. This review details the requirements necessary for glucose homeostasis, defines organic hypoglycemia, and demonstrates a logical approach to the diagnosis and treatment of patients with this symptom complex.

Blood Glucose↗
PubMed1985

Protective role of faecal pH in experimental colon carcinogenesis.

There is epidemiological evidence that populations with alkaline stool pH are at greater risk for colon cancer than populations with acid stool pH. This association was investigated in the laboratory using the rat-dimethylhydrazine colon carcinogenesis model. Rats with acid stool pH, produced by consumption of lactulose or sodium sulphate or both, had significantly fewer colon tumours after injections of dimethylhydrazine (DMH) than rats treated with DMH alone. The results confirm the hypothesis that acidification of the stool can protect against the induction of colon cancer.

1,2-Dimethylhydrazine↗