Stress resistance of Drosophila transgenic for bovine CuZn superoxide dismutase

Several oxidative and non-oxidative stresses were applied to two transgenic strains of Drosophila melanogaster (designated P(bSOD)5 and P(bSOD)11) that express superoxide dismutase (SOD) at elevated levels, and control strains that express normal SOD levels. Transgenic strain P(bSOD)5 exposed to paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride), a redox cycling agent that generates superoxide anion when metabolized in vivo, was significantly more resistant to this xenobiotic than control flies. When test flies were subjected to 100% oxygen for 20 min each day, the mean lifespan was 3.62 days for control strain 25, but 4.35 days for both transgenic strains. The mortality curves of strains fed 1% H2O2 were similar, but the median lifespan of 72 h for controls and 64 h for transgenics suggests that the transgenic flies were slightly more sensitive to H2O2. The activity of catalase was the same for all strains. Using starvation resistance as a non-oxidative stress, flies maintained on water without any food had identical survival curves; for all strains, the median lifespan was 72 h. Throughout the lifespan, no statistically significant difference in physical activity was displayed for transgenic versus control flies. Collectively, these data suggest that the increased lifespan previously observed in SOD transgenics is specifically related to resistance to oxidative stresses.

Nongenital pelvic leiomyosarcoma metastatic to the heart

A patient who had a 5-year history of a low-grade nongenital pelvic leiomyosarcoma was evaluated for worsening dyspnea, hypertension, and jugular venous distension. An echocardiogram revealed a large right atrial mass. At surgical exploration, metastatic leiomyosarcoma was found within the inferior vena cava extending from below the renal veins up into the right atrium. Using cardiopulmonary bypass with profound hypothermia and circulatory arrest, the inferior vena cava was opened below the renal veins, and the tumor was transected. That portion of the tumor above this transection was then extracted through a right atriotomy. Resection of the pelvic tumor was not thought to be feasible. The patient remains asymptomatic with stable pelvic tumor 1 year after the procedure.

A technique for managing terminally ill ovarian carcinoma patients

A patient with terminal ovarian carcinoma was admitted with malnutrition, abdominopelvic pain, and an inoperable complete small bowel obstruction after failing standard therapy and several experimental regimens for her disease. Despite this serious situation, she had an overall high performance status. Instead of administering intravenous narcotics, providing nasogastric suction, and giving other supportive care to make her apparently imminent death as comfortable as possible, her malnutrition was treated with total parenteral nutrition administered through an indwelling central venous catheter during the night hours only. The pain was successfully treated with an indwelling epidural catheter with the continuous infusion of morphine through a portable pump carried by a shoulder strap. The intestinal obstruction was relieved by a percutaneous endogastric tube which drained spontaneously into a leg bag. This regimen allowed the patient complete daytime mobility. She remained active, largely at home, with slowly progressing tumor until her death 9 months after the institution of this supportive care.

Radical vulvectomy with partial rectal resection and temporary colostomy as primary therapy for selected patients with vulvar carcinoma

The patient with carcinoma of the vulva may present with tumor involvement of the perirectal area. Traditional treatment has often involved ultraradical therapy including a radical vulvectomy with posterior or total pelvic exenteration in an effort to obtain adequate surgical margins. Five-year survival rates for these patients range from 20-50%, and major operative morbidity as well as psychological problems are associated with this extensive surgery. Five patients treated for a locally advanced vulvar carcinoma involving the perirectal area were thought to be candidates for a rectum-sparing procedure. They underwent a radical vulvectomy, bilateral inguinal lymphadenectomy, partial rectal resection, and a diverting colostomy. Four of the five patients agreed to a colostomy closure 6 months after their primary therapy; these four patients have resumed normal bowel function. All patients remain clinically free of tumor.

Indwelling epidural catheters for pain control in gynecologic cancer patients

Seven patients with severe pain caused by an advanced, incurable gynecologic malignancy were treated with an indwelling epidural catheter connected to an implantable subcutaneous port through which morphine was infused. There were few major complications associated with insertion or maintenance of the system. The average usage was 60 days, although the system functioned continuously for 6 months in one patient. Pain distribution in these women ranged from the upper abdomen to the lower extremities. All patients, including one with liver metastases, reported good to excellent pain control with the epidural narcotics. Two subjects with upper abdominal pain occasionally required supplemental oral oxycodone, but the other five patients had adequate pain relief with the epidural system alone. The indwelling epidural system provides excellent analgesia for patients with advanced, incurable gynecologic cancer.

Osseous metaplasia in ovarian papillary serous cystadenocarcinoma

The finding of osseous metaplasia within an ovarian papillary serous cystadenocarcinoma is very rare. A review of the medical literature reveals only two previously published cases where mature bone was found in an ovarian serous cystadenocarcinoma. This report presents an additional case of this unusual phenomenon whose clinical significance remains uncertain.

Do patients understand written health information?

Long sentences, medical terms and small print make hospital information brochures and consent forms difficult for many patients to understand. There are, however, things nurses can do to make written information for patients more accessible.

Metastatic placental site trophoblastic tumor

A patient with metastatic placental site trophoblastic tumor is presented. Her treatment included several aggressive chemotherapeutic regimens. In this patient, the clinical course and assays of beta-hCG (beta fragment of human chorionic gonadotropin) correlated with her response to these treatments.

Adjuvant therapy in stage I and stage II epithelial ovarian cancer. Results of two prospective randomized trials

About a third of patients with ovarian cancer present with localized disease; despite surgical resection, up to half the tumors recur. Since it has not been established whether adjuvant treatment can benefit such patients, we conducted two prospective, randomized national cooperative trials of adjuvant therapy in patients with localized ovarian carcinoma (International Federation of Gynecology and Obstetrics Stages Ia to IIc). All patients underwent surgical resection plus comprehensive staging and, 18 months later, surgical re-exploration. In the first trial, 81 patients with well-differentiated or moderately well differentiated cancers confined to the ovaries (Stages Iai and Ibi) were assigned to receive either no chemotherapy or melphalan (0.2 mg per kilogram of body weight per day for five days, repeated every four to six weeks for up to 12 cycles). After a median follow-up of more than six years, there were no significant differences between the patients given no chemotherapy and those treated with melphalan with respect to either five-year disease-free survival (91 vs. 98 percent; P = 0.41) or overall survival (94 vs. 98 percent; P = 0.43). In the second trial, 141 patients with poorly differentiated Stage I tumors or with cancer outside the ovaries but limited to the pelvis (Stage II) were randomly assigned to treatment with either melphalan (in the same regimen as above) or a single intraperitoneal dose of 32P (15 mCi) at the time of surgery. In this trial (median follow-up, greater than 6 years) the outcomes for the two treatment groups were similar with respect to five-year disease-free survival (80 percent in both groups) and overall survival (81 percent with melphalan vs. 78 percent with 32P; P = 0.48). We conclude that in patients with localized ovarian cancer, comprehensive staging at the time of surgical resection can serve to identify those patients (as defined by the first trial) who can be followed without adjuvant chemotherapy. The remaining patients with localized ovarian cancer should receive adjuvant therapy, and with adjuvant melphalan or intraperitoneal 32P should have a five-year disease-free survival of about 80 percent.

Evaluation of flurbiprofen-exposed irises to acetylcholine anterior chamber irrigation

Flurbiprofen (Ocufen), an antiprostaglandin, has been introduced into cataract surgery. It is used to prevent intraoperative miosis by blocking inflammatory mediator formation. Ocufen has been noted to diminish the controlled miosis produced by using acetylcholine in the operative period. This study evaluated the pupillary response to acetylcholine after it had been exposed to Ocufen. This was done using a control versus a study eye in 16 rabbits dilated with phenylephrine hydrochloride and cyclopentolate hydrochloride. The pupil diameters were measured at baseline, then the rabbits' anterior chambers were irrigated with an acetylcholine solution. The resultant pupillary diameters were measured at one and five minutes. At five minutes post-irrigation there was a statistically significant greater constriction in the control group than in the Ocufen group. This implies that Ocufen dampens the iris musculature's response to acetylcholine.

Bowel perforation associated with intraperitoneal chromic phosphate instillation

Intraperitoneal chromic phosphate is widely used as adjuvant therapy in the treatment of early-stage ovarian epithelial carcinoma. Delayed bowel injury is an infrequently observed complication of chromic phosphate administration. This report presents a case of colon perforation which occurred 4 months after treatment with intraperitoneal chromic phosphate for stage IB ovarian papillary serous cystadenocarcinoma.

Intracerebroventricular saccharide infusions inhibit thirst induced by systemic hypertonicity

The effect of intracerebroventricular (i.c.v.) infusion of various iso- and hypertonic saccharide solutions on water intake stimulated by intracarotid (i.c.) infusion of hypertonic NaCl was studied in sheep. Without an i.c.v. infusion, water intake during a 10-min period following an i.c. infusion of 4 M NaCl (1.4 ml/min over 20 min) was 1.5-2.0 litres. I.c.v. infusion of all saccharide solutions (made up in artificial cerebrospinal fluid (CSF) with no Na) tested, 0.27 or 0.7 M D-glucose, L-glucose, 2-deoxyglucose and sucrose, decreased (35-65%) water intake. In general, there was little or no difference in antidipsogenic effectiveness between the isotonic and the hypertonic solutions or between the different saccharides used. I.c.v. infusion of artificial CSF ([Na] = 150 mM) did not alter water intake. CSF [Na] was decreased by all of the saccharide infusions. CSF osmolality was increased by the hypertonic solutions, was decreased by the artificial CSF and was unchanged by the isotonic solutions infused. The observation that the antidipsogenic effectiveness of saccharides which readily cross the blood-brain barrier (BBB; D-glucose, 2-deoxyglucose) was similar to that of saccharides which do not readily cross the BBB (sucrose, L-glucose) contrasts with effects reported on sodium appetite and suggests that the Na sensors involved in the inhibition of hypertonic NaCl-stimulated water intake are located close to or on the surface of the brain ventricular system, i.e. are responsive to changes in CSF [Na].(ABSTRACT TRUNCATED AT 250 WORDS)

Oesophageal ischaemia in motility disorders associated with chest pain

The cause of chest pain in diffuse oesophageal spasm and "nutcracker" oesophagus is not clear. Spasm of the oesophageal muscle itself is probably not the cause, because pain and spasm are frequently not coincident. It is suggested instead that oesophageal ischaemia may be the cause of the pain, since the rewarming rate of the oesophagus after a standardised cold challenge was significantly longer in 9 patients with these motility disorders than in 21 normal controls. As rewarming time in other sites correlates with blood flow, these results are consistent with the hypothesis that the oesophagus is ischaemic in these patients.

Mortality among bearing plant workers exposed to metalworking fluids and abrasives

Epidemiologic studies have reported associations between gastrointestinal cancer mortality and exposure to cutting fluids and abrasives in metal machining and precision grinding operations. Two previous studies found excess stomach cancer among workers exposed to water-based cutting fluids in bearing plants. This study reports similar findings in a third and larger population. Cause of death and work histories were determined for 1,766 bearing plant workers who died between Jan 1, 1950 and June 30, 1982. Mortality odds ratios (SMOR) and proportional mortality ratios (PMR) revealed significant excesses of gastrointestinal malignancies. The proportional mortality excess for stomach cancer among white men was greatest among those with more than 10 years' exposure in the major grinding group (PMR = 13/3.8 = 3.39; P less than .001). The SMOR by logistic regression for stomach cancer among white men was 2.3 (P = .02) for 25 years' grinding experience. For cancer of the pancreas among white men, there were significant associations with both machining and grinding jobs in straight oil (SMOR = 9.9 and 3.2, respectively, for 25 years duration). These findings could not be explained by confounding due to the ethnic background of the decedents. This study confirms previous evidence that grinding operations using water-based cutting fluids increase the risk for stomach cancer and provides moderate evidence that exposures to straight oil-cutting fluids increase the risk for cancer of the pancreas. There were indications, meriting further investigation, that non-malignant liver disease is associated with cutting fluid exposures and that lung cancer is associated with oil smoke from operations such as forging or heat treating.

Occupational cancer in metalworking and transportation equipment industries

Hazardous chemical exposures may be a more important public health problem in chemical-using industries, such as the metalworking and transportation equipment industries, than in chemical manufacturing plants. Recent studies have identified excess mortality from cancer among groups of workers in model and patternmaking, plating and die-cast, foundry, machining, electronics operations and vehicle assembly plants. The chemical agents or levels of exposure associated with these findings have not previously been thought to pose a cancer risk. Therefore, estimates of the fraction of cancers associated with workplace exposure may understate the importance of exposure in this setting.

Nonsquamous cancer of the vagina

This report retrospectively analyzes 48 cases of primary vaginal cancer treated at Walter Reed Army Medical Center and the Naval Hospital, Bethesda, from 1962 through 1983. There was an unusually high number of uncommon histologic types. Nine patients had an adenocarcinoma, 5 had a sarcoma, 3 had a melanoma, 2 had an adenosquamous carcinoma, 1 had a lymphoma, and 1 had a carcinoid tumor. The remaining 27 patients had a squamous cell carcinoma. This represents a 43% prevalence of nonsquamous lesions. Nonsquamous cancer of the vagina occurred in patients at an earlier age than squamous cell carcinoma. Presenting symptoms, the location of the tumor within the vagina, and survival rates were similar for both groups. The clinical characteristics and treatment of the patients with nonsquamous tumors are discussed.

Results of second-look laparotomy in patients with early-stage ovarian carcinoma

One hundred twelve patients with early (FIGO stage I and II) ovarian carcinoma had a second-look laparotomy performed after comprehensive surgical staging and randomization into clinical protocols. Of the 95 patients who were asymptomatic before second-look laparotomy, only 5% had positive findings. In contrast, 53% of the 17 patients with findings that suggested recurrence or bowel obstruction had disease at second-look laparotomy. Overall, only 13% of the entire group of 112 patients had recurrent disease at second-look laparotomy. Asymptomatic patients with early ovarian carcinoma who have undergone careful initial surgical staging followed by appropriate adjuvant therapy can be spared a routine second-look operation.

The treatment of retroperitoneal fibromatosis with medroxyprogesterone acetate

Wide excision is the recommended primary therapy for retroperitoneal fibromatosis. Radiation therapy and a variety of medications have been used to treat patients with recurrent tumors, but the response to these agents has not been uniform. The patient presented was successfully treated with medroxyprogesterone acetate for recurrent retroperitoneal fibromatosis that was refractory to multiple operative resections and radiation therapy.

Multiple sequence elements are required for regulation of human T-cell leukemia virus gene expression

The U3 region of the long terminal repeat (LTR) of human T-cell leukemia virus type I (HTLV-I) contains sequences that respond to the trans-activating transcription (tat) factor encoded by the pX region of the provirus. Results presented here show that there are multiple tat-responsive sequences within the LTR and that a single 21-nucleotide sequence, which is repeated three times within the U3 region, is sufficient to determine the response to the trans-activator. This sequence is capable of conferring a tat-responsive phenotype upon the HTLV-I and simian virus 40 promoters, independent of orientation. Sequences required for efficient HTLV-I LTR-directed gene expression are also located 3' to the site of RNA initiation, within the R and U5 regions of the LTR.

Clinical significance and etiology of infected catheters used for total parenteral nutrition

Catheter related sepsis (CRS) is the most serious complication of total parenteral nutrition. Frequently, however, low rates of CRS are associated with a high incidence of infection of the catheter tip, the clinical significance of which is unclear. The relationships between CRS, infection of the catheter tip and infection at the site of catheter insertion have been investigated in 283 catheters of 257 patients receiving total parenteral nutrition. CRS occurred in only ten patients (3.5 per cent) whereas organisms were isolated from 108 catheter tips (38.2 per cent). The most common organism isolated was Staphylococcus epidermidis (66.7 per cent). Eight catheter tips were colonized from a distant septic focus. Organisms were isolated from 90 catheter tips which were removed electively from patients who displayed no clinical evidence of sepsis. There was a poor correlation between infected catheter tips and infected catheter insertion sites. Asymptomatic infection of the catheter tip appears to be of little clinical relevance, resulting in no patient morbidity. Contamination of the catheter tip during or after removal seems to account for a significant proportion of these infections.

Mortality among ferrous foundry workers

Mortality analyses were carried out for 278 male hourly workers who were employed for at least 10 years at a gray iron foundry and who died between January 1, 1970 and December 31, 1981. Statistically significant excess proportional mortality due to non-malignant respiratory disease (SPMR = 177), lung cancer (SPMR = 148), and leukemia (SPMR = 284) was found among the 221 white males. Among nonwhite males there was a significant excess in proportional mortality due to circulatory diseases (SPMR = 143). White males in the Finishing classification experienced a significant excess of proportional mortality due to nonmalignant respiratory disease (SPMR = 279) and lung cancer (SPMR = 179). White males in the Core Room classification experienced an excess of proportional mortality due to nonmalignant respiratory disease (SPMR = 321). Case-control studies demonstrated a significant association between nonmalignant respiratory disease and the Finishing classification after controlling for the effects of age, prior occupations in coal mining or foundries, and smoking. A positive but nonsignificant association between lung cancer and Finishing was also found after controlling for age, prior work history, and smoking in case control studies.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.