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Biomedical subjects

R Park

Publications and source records attributed to R Park.

At least 91 records · Page 5Linked to original sources
PubMed1985

Acute upper airway obstruction in the postburn period.

Upper airway obstruction in the severely burned patient is a well-known problem that is due to mucosal edema secondary to the effects of toxic substances and heat on the laryngeal and tracheal mucosa. Herein, we report a different cause of airway obstruction seen in the late postburn period during the induction of anesthesia for reconstructive procedures. This obstruction is due to the presence of severe burn-scar contractures of the neck that prevent successful endotracheal intubation. We have seen this occur 17 times in 13 patients. All of the patients were successfully treated by an emergency neck release, after which most of the patients could be intubated and the release then skin grafted. Surgeons operating on patients with scar contractures of the neck should be aware of this condition and its appropriate treatment.

Adolescent↗
PubMed1985

A randomized clinical trial of adjuvant adriamycin in uterine sarcomas: a Gynecologic Oncology Group Study.

After hysterectomy, 156 evaluable patients with stage I (limited to the corpus) or stage II (limited to the corpus and cervix) uterine sarcomas were randomly assigned to adjuvant chemotherapy with Adriamycin (Adria Laboratories, Columbus, Ohio) for six months or to no further treatment. Pelvic irradiation (external or intracavitary) was optional before randomization. Of 75 patients receiving Adriamycin, 31 have suffered recurrences compared with 43 of 81 receiving no adjuvant chemotherapy. This difference is not statistically significant. Moreover, there is no difference in progression-free interval or survival. The optional radiotherapy did not influence the outcome although there was a suggestion that vaginal recurrence was decreased by pelvic radiotherapy. The recurrence rates in specific cell types (leiomyosarcoma, homologous mixed mesodermal sarcoma, or heterologous mixed mesodermal sarcoma) were not significantly different although the pattern of recurrence differed, with pulmonary metastases being more common in leiomyosarcoma and extrapulmonary recurrence being more common in mixed mesodermal sarcoma. The outcome with respect to chemotherapy was not altered even after adjusting for maldistribution of cases. Thus, we could not show a benefit for this dose schedule of Adriamycin as adjuvant treatment for uterine sarcomas.

Adolescent↗
PubMed1985

Mortality among workers exposed to coal tar pitch volatiles and welding emissions: an exercise in epidemiologic triage.

The United Automobile Workers International Union has established a system of epidemiologic triage to evaluate patterns of mortality among groups of union members. In response to worker concerns, the Union examined mortality at a metal stamping plant, using a method which linked pension records with the State of Michigan computerized death registry. The observed proportion of malignant neoplasms was nearly twice that expected (95% Confidence Limits 1.36, 2.62). Two- to five-fold excess proportional mortality from cancer of the digestive organs, lung cancer, and leukemia accounted for most of the overall excess. Strong associations were found between lung and digestive organ cancer and employment as maintenance welders or millwrights in the plant (odds ratios greater than 10). High levels of six polycyclic aromatic hydrocarbons with mutagenic and carcinogenic properties were found during hot coal tar application to wood block floors, work conducted by the high-risk groups. These levels were substantially reduced following the purchase of new tar pots. The example demonstrates that epidemiologic tools can play a valuable role in occupational health decision making, but care must be taken to avoid mechanical reliance on quantitative testing and to acknowledge the important role of social and political value judgments in the establishment of responsible public policy.

Adult↗
PubMed1985

Epithelial ovarian carcinoma of low malignant potential.

The records of 94 patients with epithelial ovarian carcinoma of low malignant potential were examined. These records were contributed by Walter Reed Army Medical Center, Naval Hospital, Bethesda, MD, and Naval Hospital, Portsmouth, VA. A review of microscopic sections from each of the 94 tumors confirmed that these were lesions of low malignant potential. The tumors occurred in patients of a younger age than that generally described for invasive epithelial ovarian carcinoma. Forty-seven of 94 patients had stage I disease. The corrected five- and ten-year survival rates were 95 and 87%, respectively. Adjunctive postoperative therapy may not influence survival.

Adenocarcinoma, Mucinous↗
PubMed1985

Persistence of endometrial activity after radiation therapy for cervical carcinoma.

Radiation therapy is a proved treatment for cervical carcinoma; however, it destroys ovarian function and has been thought to ablate the endometrium. Estrogen replacement therapy is often prescribed for patients with cervical carcinoma after radiation therapy. A review of records of six teaching hospitals revealed 16 patients who had endometrial sampling for uterine bleeding after standard radiation therapy for cervical carcinoma. Fifteen patients underwent dilatation and curettage, and one patient underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy when a dilatation and curettage was unsuccessful. Six patients had fibrosis and inflammation of the endometrial cavity, seven had proliferative endometrium, one had cystic hyperplasia, one had atypical adenomatous hyperplasia, and one had adenocarcinoma. Although the number of patients who have an active endometrium after radiation therapy for cervical carcinoma is not known, this report demonstrates that proliferative endometrium may persist, and these patients may develop endometrial hyperplasia or adenocarcinoma. Studies have indicated that patients with normal endometrial glands have an increased risk of developing endometrial adenocarcinoma if they are treated with unopposed estrogen. Patients who have had radiation therapy for cervical carcinoma should be treated with estrogen and a progestational agent to avoid endometrial stimulation from unopposed estrogen therapy.

Adenocarcinoma↗
PubMed1985

Repair of vaginal prolapse and perineal hernia after pelvic exenteration.

Perineal hernias have been a significant complication of pelvic exenteration since the inception of this procedure. A variety of natural and artificial materials have been used to support the small bowel to prevent its descent into the lower pelvis with subsequent hernia and fistula formation. More recently, neovagina construction using gracilis myocutaneous flaps has provided both sexual function and support for the small bowel. A patient is presented who had prolapse of her neovagina and a perineal hernia 12 months after exenterative surgery. A technique to repair this complication is described, and a possible method of preventing it is discussed.

Adult↗
PubMed1984

A fifteen-month double-blind cross-over study of the efficacy and antigenicity of human and pork insulins.

The antigenicity and efficacy of semi-synthetic human and pancreatic pork insulins have been compared in a double-blind double cross-over study in 96 insulin-treated diabetic patients. Transfer from pork to human insulin was associated with a 1.2 +/- 0.5 mmol/l deterioration (p less than 0.05) in the fasting blood glucose level, while the opposite change caused a 1.1 +/- 0.5 mmol/l improvement (p less than 0.05). After 4 months treatment, glycosylated haemoglobin levels were lower on pork (11.1 +/- 0.3%) than on human (11.7 +/- 0.3% p less than 0.01) insulin. The incidence of hypoglycaemia was similar with the two insulins. IgG insulin antibody levels were identical after human insulin treatment (5.7 +/- 0.4 micrograms/l) compared to pork insulin treatment (5.9 +/- 0.5 micrograms/l). Patients with high levels of antibodies (greater than 10 micrograms/l) showed a similar reduction in level when switched to either species of highly purified insulin. The deterioration in fasting blood glucose control is consistent with similar reports for biosynthetic human insulin and suggests, in the absence of changes in insulin antibody levels, a small but clinically significant pharmacokinetic difference between human and pork insulin.

Adolescent↗
PubMed1983

Lactic acidosis: current concepts.

Lactic acidosis is now a widely recognized disorder in clinical medicine. Experimental studies during the past decade demonstrate an important role of lactate disposal mechanisms in the pathogenesis of lactic acidosis. Such factors as decreased cardiovascular reserve, inadequate liver perfusion and alterations in liver intracellular pH appear to limit the normally large capacity of the liver to dispose of lactic acid. The continued high mortality of this disorder has led to a re-examination of the conventional, empirical treatment of lactic acidosis with sodium bicarbonate. Available data suggest that alkali may cause or exacerbate the conditions of excessive lactate production, decreased cardiac reserve and inadequate hepatic lactate disposal which exist in this disorder. In contrast, dichloroacetate therapy shows strikingly beneficial results, at least in early experimental studies.

Acidosis↗
PubMed1983

Lactic acidosis and the cardiovascular system in the dog.

1. Lactic acidosis is a clinical syndrome characterized by metabolic acidaemia (pH less than 7.25) and hyperlactaemia (lactate greater than 5 mmol/l). Many patients with type B lactic acidosis have no evidence of tissue hypoxia or myocardial dysfunction when first evaluated. Although it is considered that cardiac dysfunction is secondary to the systemic effects of lactic acidosis, the reverse may sometimes be true. To evaluate this possibility, studies were carried out in 43 dogs consisting of a control group and three groups which had hyperlactataemia and metabolic acidaemia related to either: (1) phenformin infusion; (2) hepatectomy; (3) lactic acid infusion. Serial studies of cardiac function, as well as measurements of GFR (glomerular filtration rate) and hepatic portal vein (HPV) blood flow, were carried out. 2. In dogs infused with phenformin for 99 min, the arterial pH, lactate, bicarbonate, heart rate and mean blood pressure (BP) were normal. However, there was significant deterioration (P less than 0.01) in several indices of cardiac function, including the peak positive dP/dt, cardiac output, LVEDP (left ventricular end-diastolic pressure) and percentage extraction of oxygen and lactate by the heart. After 3 h of phenformin, the blood lactate exceeded 5 mmol/l and there were further significant decrements (P less than 0.01) in cardiac output, LVEDP and dP/dt, as well as BP and heart rate. In dogs subjected to hepatectomy, the decrement in cardiac output was similar to that with phenformin infusion. However, in animals infused with lactic acid, despite a similar blood pH and lactate, cardiac output was unaffected. Although percentage myocardial oxygen extraction declined in phenformin-infused animals, there was a concomitant increase in coronary sinus blood flow such that myocardial oxygen utilization was probably unaltered. 3. Thus, in certain types of experimental type B lactic acidosis, myocardial dysfunction may be a primary event, with other associated systemic manifestations being secondary.

Acidosis↗
PubMed1983

Metabolic effects of dichloroacetate in diabetic dogs.

In fasted, diabetic dogs treated with dichloroacetate (DCA) (300 mg X kg-1 X h-1 iv), we determined the relative contributions by skeletal muscle and gut to the supply of precursors used for hepatic gluconeogenesis. The total production of lactate and alanine by skeletal muscle and gut decreased from 2,370 to 1,160 mumol X kg-1 X h-1 during treatment with DCA. Hepatic uptake of these substrates decreased from 1,040 to 435 mumol X kg-1 X h-1, and blood glucose decreased from 370 +/- 18 to 279 +/- 22 mg/dl (P less than 0.001). DCA treatment decreased the skeletal muscle production of both lactate and alanine to 40% of control, whereas gut production was decreased to only 72% of control levels. Hepatic uptake of the two substrates decreased in proportion to the change in blood levels because fractional hepatic extraction was unaltered. The effects of DCA on the interorgan metabolism of plasma amino acids showed that diminished availability of alanine for hepatic gluconeogenesis was compensated in part by increased release of other gluconeogenic amino acids from muscle and gut. Gut uptake of glutamine appeared unchanged, but most of its metabolic end products were released in greater amounts by DCA treatment, suggesting enhanced glutamine degradation. These results in fasted, diabetic dogs indicate that 1) DCA treatment lowers blood glucose in part by limitation of gluconeogenic substrate supply from skeletal muscle and gut, and 2) DCA has complex and diverse effects on the interorgan metabolism of plasma amino acids.

Acetates↗
PubMed1982

Systemic effects of NaHCO3 in experimental lactic acidosis in dogs.

Lactic acidosis is characterized by metabolic acidosis due to accumulation of H+ ions from lactic acid with blood lactate of at least 5 mM. The standard treatment is intravenous NaHCO3, with resultant mortality in excess of 50%. Despite the high mortality, the metabolic and systemic effects of NaHCO3 used in the treatment of lactic acidosis have not been extensively studied. The present experiments in diabetic dogs were designed to address these questions. Dogs with phenformin-induced lactic acidosis (blood lactate above 5 mM, arterial pH below 7.20) were treated with equimolar amounts of either NaCl or NaHCO3 or received no therapy. Intravenous NaHCO3 resulted in a decline of cardiac output and intracellular pH (pHi) of liver and erythrocytes, whereas treatment with NaCl did not. With NaHCO3 but not with NaCl infusion gut lactate production increased almost stoichiometrically, with no change in arterial pH or bicarbonate but with a doubling of lactate. Bicarbonate also resulted in a decrease of hepatic portal vein blood flow. The mean survival time and percent mortality were similar in NaCl- vs. NAHCO3(-) treated animals. Although both groups lived longer than did animals receiving no therapy, the differences were not significant. Thus, treatment of experimental lactic acidosis with either NaCl or NaHCO3 or with no therapy results in no change of blood pH and bicarbonate and in a similar mortality. In terms of systemic effects, however, NaHCO3 results in significant decrements of liver and erythrocyte pHi, hepatic portal vein blood flow, and cardiac output and in significant increments of gut lactate production, whereas NaCl does not. The data suggest that the rationale for therapy of lactic acidosis with NaHCO3 should probably be reevaluated.

Acidosis↗
PubMed1982

Treatment of lactic acidosis with dichloroacetate in dogs.

Lactic acidosis is a clinical condition due to accumulation of H(+) ions from lactic acid, characterized by blood lactate levels >5 mM and arterial pH <7.25. In addition to supportive care, treatment usually consists of intravenous NaHCO(3), with a resultant mortality >60%. Dichloroacetate (DCA) is a compound that lowers blood lactate levels under various conditions in both man and laboratory animals. It acts to increase pyruvate oxidation by activation of pyruvate dehydrogenase. We evaluated the effects of DCA in the treatment of two different models of type B experimental lactic acidosis in diabetic dogs: hepatectomy-lactic acidosis and phenformin-lactic acidosis. The metabolic and systemic effects examined included arterial blood pH and levels of bicarbonate and lactate; the intracellular pH (pHi) in liver and skeletal muscle; cardiac index, arterial blood pressure and liver blood flow; liver lactate uptake and extrahepatic splanchnic (gut) lactate production; and mortality. Effects of DCA were compared with those of either NaCl or NaHCO(3). The infusion of DCA and NaHCO(3), delivered equal amounts of volume and sodium, although the quantity of NaHCO(3) infused (2.5 meq/kg per h) was insufficient to normalize arterial pH. In phenformin-lactic acidosis, DCA-treated animals had a mortality of 22%, vs. 89% in those treated with NaHCO(3). DCA therapy increased arterial pH and bicarbonate, liver pHi and cardiac index, with increased liver lactate uptake and a fall in blood lactate. With NaHCO(3) therapy, there were decrements of cardiac index and liver pHi, with an increase in venous pCO(2) and gut production of lactate. Dogs with hepatectomy-lactic acidosis were either treated or pretreated with DCA. Treatment with DCA resulted in stabilization of cardiac index, a fall in blood lactate, and 17% mortality. NaHCO(3) was associated with a continuous decline of cardiac index, rise in blood lactate, and 67% mortality. In dogs pretreated with NaCl, mortality was 33%, but all dogs pretreated with DCA survived. Dogs pretreated with DCA also had lower blood lactate and higher arterial pH and bicarbonate than did those pretreated with NaCl.Thus, in either of two models of type B experimental lactic acidosis, treatment with DCA improves cardiac index, arterial pH, bicarbonate and lactate, and liver pHi. The mortality in dogs with type B lactic acidosis was significantly less in DCA-treated animals than in those treated with other modalities.

Acetates↗
PubMed1982

Diagnosis and differentiation of fat malabsorption in children using 13C-labeled lipids: trioctanoin, triolein, and palmitic acid breath tests.

Three substrates labeled with nonradioactive 13C have been employed to establish a trilogy of noninvasive breath tests to detect fat malabsorption in children and then to differentiate the etiology of the steatorrhea. Administration of 17 mg/kg of (13C)triolein Lipomul (The Upjohn Co., Kalamazoo, Mich.) resulted in a peak excretion rate of 13CO2 greater than 2.7% dose/h in 10 normal subjects (mean value 4.96 +/- 2.2% dose/h) whereas all 17 subjects with fat malabsorption were below this value (mean value, 0.75% +/- 0.63% dose/h); p less than 0.001). For the detection of fat malabsorption, the discriminative value of (13C)triolein was superior, 100% sensitive, and 89% specific, while the use of (13C)palmitic acid (17 mg/kg) or (13C)trioctanoin (7.5 mg/kg) alone yielded both false-positive and false-negative results. In 6 out of 6 cases, pancreatic insufficiency could be differentiated from mucosal disease (7 patients) or bile salt deficiency (4 patients) by the presence of abnormal triolein or trioctanoin breath tests, or both but normal palmitic acid breath tests. However, further differentiation of mucosal disorders from bile salt disorders could not be achieved using either a single- or a multiple-substrate breath test. The use of the single triolein breath test in children offers an attractive, sensitive alternative to conventional fecal fat measurements to establish the presence of steatorrhea, and when using 12C-lipid with multiple substrates, the tests are capable of providing additional insight into the mechanism of fat malabsorption.

Adolescent↗
PubMed1980

Measurement of the liver extracellular space in vivo in dogs.

To obtain a reasonable estimate in vivo of the liver extracellular space (ECS) in intact, non-exsanguinated dogs, the distribution volumes of a variety of radioactive tracers were obtained as a function of time. 36Cl, 14C- and 3H-inulin, 125I-albumin, 51Cr-red cells, and endogenous 35Cl distribution volumes were obtained in liver from 5 min to 4 h. The 36Cl space was stable and reproducible at 29.0%, a value similar to the endogenous 35Cl (28.2%) and 5 min 14C-inulin (29.9%) spaces. The 36Cl space may be used as the upper limit of liver ECS, whereas the inulin space exceeds this value after 5 min and progressively increases. Electrolyte concentrations in liver cell water are calculated using the 36Cl space of 29% as the liver ECS. The advantages of using 36Cl over other methods to determine liver ECS in intact animals are discussed.

Albumins↗