Formation of quinonoid-derived protein adducts in the liver and brain of Sprague-Dawley rats treated with 2,2',5, 5'-tetrachlorobiphenyl

A possible role for metabolic activation of 2,2',5, 5'-tetrachlorobiphenyl (TCB) to quinonoid metabolites was investigated in vitro in rat liver microsomes and in vivo in male Sprague-Dawley rats. Incubation of TCB with phenobarbital-induced rat liver microsomes resulted in metabolism of TCB to 3-hydroxy-TCB (3-OH-TCB) and 3,4-dihydroxy-TCB (3,4-diOH-TCB), which were further oxidized to form a reactive intermediate that bound to liver proteins. The predominant species observed in the Raney nickel assay for cysteinyl adducts was identified as 3,4-diOH-TCB, consistent with an adduct having the structure 5-cysteinyl-3,6-dichloro-4-(2', 5'-dichlorophenyl)-1,2-benzoquinone. This adduct may arise via the Michael addition of the sulfhydryl group of cysteine to 3, 6-dichloro-4-(2',5'-dichlorophenyl)-1,2-benzoquinone (Cl(4)PhBQ). Metabolism of 3-OH-TCB by phenobarbital-induced microsomes in the presence of either NADPH or cumene hydroperoxide as a cofactor resulted in the formation of adducts. Dose-dependent formation of cysteinyl adducts was observed in liver cytosolic protein from rats treated with a single dose of TCB (0-200 mg/kg) by gavage. By regression analysis, the TCB adducts decayed with a half-life of 2. 03 +/- 0.131 days (mean +/- SE), which is approximately 2.5-fold shorter than the endogenous half-life for liver cytosolic protein in rat liver, suggesting adduct instability. Saturable formation of TCB adducts was observed in liver cytosolic protein of rats receiving multiple doses of TCB over 5 days. The levels of Cl(4)PhBQ-derived adducts were 2.1-fold greater than the estimated steady-state levels predicted by the single-dose treatment [97.7 +/- 13.2 vs 45.7 +/- 3. 73 (pmol/g)/(mg/kg of body weight)], suggesting induction of metabolism. A single cysteinyl adduct, inferred to be 5-cysteinyl-3, 6-dichloro-4-(2',5'-dichlorophenyl)-1,2-benzoquinone, was detected in brain cytosolic protein of rats treated with multiple doses of TCB with levels of 15.2 (pmol/g)/(mg/kg of body weight). Implied involvement of a reactive quinone in the liver and brain of TCB-treated rats supports the idea that quinonoid metabolites may be important contributors to PCB-derived oxidative damage to genomic DNA.

A simple physiologic pulsatile perfusion system for the study of intact vascular tissue

Perfusion vascular culture models may provide a useful link between cell culture models and animal culture models by allowing a high level of control over important parameters while maintaining physiologic structure. The purpose of this study was to develop and test a new vascular culture system for pulsatile perfusion culture of intact vascular tissue. The system generates a pulsatile component of flow by means of a cam-driven syringe and a peristaltic pump and compliance chamber. Cams were designed, constructed and tested to simulate canine femoral and common carotid artery flows. The mean pressure was adjusted between 60 and 200 mmHg without significantly affecting flow rate, flow waveform, or the pressure waveform. Porcine common carotid artery segments were cultured in this pulsatile perfusion system. The viability of vascular segments was tested after various culture times with a functional assay that demonstrated both smooth muscle cell and endothelial cell response to vasomotor challenge.

Gastric adenocarcinoma of Meckel's diverticulum as a cause of colonic obstruction

A 45-year-old-female patient with no prior surgical history presented with bowel obstruction. At laparotomy, a bulky tumor arising from the ileum, which completely obstructed the sigmoid colon, was found. A left hemicolectomy followed by a transverse colostomy and a Hartman's pouch were performed. Pathological examination of the specimen revealed gastric adenocarcinoma arising from a Meckel's diverticulum in the ileum. Malignant transformation from a Meckel's diverticulum is an uncommon occurrence. This case illustrates that successful management of a symptomatic Meckel's diverticulum, even with malignant transformation, can be achieved by surgical resection.

Evaluation of thrombolysis and angioplasty in a porcine iliac artery thrombosis model: application of endovascular stent-graft-induced thrombosis

PURPOSE

To develop a novel endovascular thrombosis model in the porcine iliac artery for the evaluation of thrombolysis and angioplasty.

MATERIALS AND METHODS

A stent-inversion-graft (SIG) model combining either a 3-mm or 5-mm tapered expandable polytetrafluoroethylene (ePTFE) graft attached within a self-expandable, 10-mm nitinol stent was placed in the left common iliac artery via an ipsilateral common femoral artery approach in 24 pigs. When the iliac artery was thrombosed, urokinase (250,000 IU) plus heparin (1,000 units) were pulse sprayed via a contralateral femoral approach (n = 12). Saline pulse-spray was used as a control group (n = 12). Balloon angioplasty was performed to eliminate the stenotic tapered graft within the stent after successful thrombolysis. The efficacy of the thrombolysis was assessed with use of intravascular ultrasound (IVUS) and arteriogram.

RESULTS

Both the 3-mm tapered and 5-mm tapered SIG models caused iliac artery occlusion in 22 +/- 5 and 41 +/- 9 minutes, respectively, after the deployment. Luminal patency was re-established successfully in all occluded arteries after urokinase infusion. Angioplasty was successful in eliminating the tapered stenosis and restoring the normal diameter in all iliac arteries treated with urokinase. Complete thrombolysis was achieved in both models treated with urokinase.

CONCLUSION

This novel endovascular approach of inducing arterial thrombosis is simple to perform and reliably produces arterial thrombosis. The intraluminal stenosis is also amenable to angioplasty. This model is useful for the evaluation of antithrombotic treatment modality and adjunctive endovascular interventions.

A porcine model of carotid artery thrombosis for thrombolytic therapy and angioplasty: application of PTFE graft-induced stenosis

PURPOSE

To develop a porcine carotid artery thrombosis model for the evaluation of thrombolytic therapy and adjunctive angioplasty procedures.

METHODS

Bilateral carotid thrombosis was induced in 16 pigs using endothelial crush injury followed by external polytetrafluoroethylene (PTFE, 5 x 2 cm2) wrap placement to create segmental carotid stenosis. Light microscopy was used to examine thrombus composition. Selective carotid catheterization was performed via a femoral approach. Two hours following carotid artery occlusion, a urokinase (250,000 IU) and heparin (1000 U) solution was pulse-sprayed in 1 carotid artery while the contralateral vessel received the control saline vehicle. The efficacy of thrombolytic therapy was assessed using carotid arteriography and intravascular ultrasound. The feasibility and technical efficacy of balloon angioplasty within the carotid stenosis model were also evaluated.

RESULTS

Carotid artery occlusion occurred in 30 +/- 6 minutes following endothelial injury plus PTFE wrap placement. Histological examination of carotid arteries showed endothelial irregularity with fibrin-rich and platelet-rich thrombus. Urokinase was effective in recanalizing all occluded arteries (100%), while the control saline vehicle showed no effective thrombolysis (p < 0.001). Angioplasty was successful in restoring normal diameter in all arteries (100%).

CONCLUSIONS

This carotid artery thrombosis model, which incorporates intimal injury with segmental stenosis, is simple to create and reproducible. It provides not only a model for the evaluation of thrombolytic therapy but also a practical training tool for adjunctive endovascular interventions.

Antithrombotic and hemostatic capacity of factor Xa versus thrombin inhibitors in models of venous and arteriovenous thrombosis

Thrombin plays a central role in venous and arterial thrombosis. We utilized two different rabbit models of in vivo thrombosis to investigate the effect of inhibitors of thrombin generation and thrombin activity. The agents tested were specific inhibitors of factor Xa (fXa) [N2-[(phenylmethyl)sulfonyl]-D-arginyl-N-[(1S)-4-[(aminoiminomethyl++ +)a mino]-1-(2-thiazolylcarbonyl)butyl]-glycinamide (C921-78)] and thrombin [D-phenylalanyl-N-[4-[(aminoiminomethyl)amino]-1-(chloroacetyl)but yl]-L-prolinamide (PPACK)], as well as drugs that affect both thrombin and fXa, unfractionated and low molecular weight (enoxaparin) heparin. The agents administered as constant intravenous infusion were evaluated for antithrombotic efficacy in anesthetized rabbits. All four agents were capable of dose dependent inhibition of thrombosis in venous and arteriovenous thrombosis models. However, due to the more aggressive nature of thrombotic stimulation in the arteriovenous shunt model, complete cessation of thrombus growth was not achieved for any of the agents at the doses tested. Comparison between the agents focused on the differences in extension of coagulation parameters (activated partial thromboplastin time, prothrombin time, thrombin clotting time), changes in hematological parameters, and extension of rabbit cuticle bleeding time at doses required to produce maximum inhibition in the thrombosis models. In the venous thrombosis model at the maximally effective dose, C921-78 had minimal extension of ex vivo clotting parameters, while enoxaparin and unfractionated heparin demonstrated a two to sevenfold increase in activated partial thromboplastin times, and PPACK had a threefold extension of thrombin clotting times. In addition, unlike the other three agents, which exhibited no significant changes in hematological parameters, PPACK demonstrated dose dependent thrombocytopenia. A standardized cuticle bleeding time was used as a measure of perturbation of hemostasis. The agents were evaluated for significant increases in bleeding time at doses up to eight times that needed to completely inhibit venous thrombus formation. Unfractionated heparin displayed a significant bleeding time effect at the dose required to inhibit venous thrombosis (100 u/kg+2 u/kg/min). Enoxaparin and PPACK caused significant bleeding time extensions at four times the fully efficacious venous dose (800 u/kg+8 u/kg/min and 30 microg/kg/min). By contrast, C921-78 did not significantly increase bleeding time even at eight times the maximally effective dose (240 microg/kg+7.2 microg/kg/min). Our results demonstrate that specific inhibition of fXa can be utilized to derive potent antithrombotic activity without disrupting extravascular hemostasis.

Embryology, anatomy, and surgical exposure of the great abdominal vessels

This article describes the embryology of the abdominal aorta and the anatomic features of its major visceral branches, including the celiac, superior mesenteric, and inferior mesenteric arteries. The common anatomic variants of these visceral vessels also are reviewed. Various operative techniques to gain surgical exposure to these vessels are described.

A new perfusion culture system used to study human vein

BACKGROUND

Cell culture studies, ring studies, and indirect physiologic studies are the predominant models used to study human vascular tissue. Such studies are limited in their capacity to permit physiologic single-factor changes or to provide the proper mechanical stress or extracellular matrix present in normal tissues. We present a newly devised organ culture system that addresses these issues and permits survival of intact segments of human vascular tissue in a perfused environment. Our experience culturing human saphenous vein with this system is detailed.

METHODS

Perfusion culture chambers were designed and constructed in our laboratory. Excess saphenous vein segments were collected from coronary artery bypass graft cases at our hospital and then mounted into our perfusion culture system for 0, 24, 48, 72, or 96 h. Vasomotor assays, hematoxylin and eosin staining, bromodeoxyuridine staining, and factor VIII staining were performed to assess tissue survival.

RESULTS

A total of 24 veins were cultured. Average vessel length was 5 cm. The vessels contracted and relaxed the following amounts: time 0 (6.7% contraction, 5.0% relaxation), 24 h (5.7%, 5.3%), 48 h (5.2%, 2.8%), 72 h (4.8%, 5.3%), 96 h (4.8%, 3.8%). Hematoxylin and eosin staining, bromodeoxyuridine staining, and factor VIII staining support the viability of the tissue segments.

CONCLUSION

A new perfusion organ culture system has been devised that permits survival of intact human venous tissue for periods up to 96 h. Studies that permit physiologic single-factor changes along with precise control of the hemodynamic environment are possible with this system.

Effects of homocysteine on smooth muscle cell proliferation in both cell culture and artery perfusion culture models

BACKGROUND

Hyperhomocysteinemia is associated with increased risk for vascular disease. However, the pathogenic mechanisms of homocysteine are largely unknown. We evaluated the effects of homocysteine on smooth muscle cell (SMC) and endothelial cell proliferation in cell culture and on SMC proliferation of balloon angioplasty-injured arteries in a perfusion culture model.

METHODS

Human and pig SMCs and endothelial cells were cultured with variable amounts of homocysteine for 72 h and the total cells were counted using a hemocytometer. Fresh pig carotid arteries were harvested from a local slaughterhouse and cultured in a newly designed artery perfusion culture system. Five groups of arteries (six per group) were cultured for 48 h under different conditions: normal control, balloon angioplasty injury alone, and injury with three different doses of homocysteine. Vessel viability was evaluated. SMC proliferation was assayed by bromodeoxyuridine (BrdU) DNA labeling.

RESULTS

At concentrations equivalent to those in human hyperhomocysteinemia, homocysteine significantly stimulated both cultured human and pig SMC proliferation with a dose-dependent effect, while it inhibited cultured endothelial cell growth. Perfusion-cultured pig carotid arteries remained contractile in response to norepinephrine and relaxant to nitroglycerine, and viable cells were also isolated from the cultured arteries. SMC proliferation (BrdU index) showed significant differences among the groups. SMC proliferation was stimulated by vascular injury and further enhanced by homocysteine in a dose-dependent manner. The proliferative response occurred strongly on the luminal side of the vessel wall, with the effects tapering toward the adventitia.

CONCLUSIONS

Homocysteine had a mitogenic effect on vascular SMCs and a cytotoxic effect on endothelial cells. This differential effect of homocysteine on vascular cells may represent a pathogenic mechanism of vascular lesion formation in patients with hyperhomocysteinemia.

Dietary adherence in the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group

Participants in controlled feeding studies must consume all study foods and abstain from all other foods. In outpatient studies in which adherence may be compromised by free-living conditions, promoting, documenting, and monitoring dietary adherence are necessary. In the Dietary Approaches to Stop Hypertension (DASH) trial, a thorough participant screening process, an orientation session, and a run-in feeding period before randomization aided in the selection of participants who would most likely adhere to the demands of the study protocol. Throughout the feeding period, various educational and motivational techniques were used to encourage DASH participants to adhere to the dietary protocol. Both objective and subjective methods documented excellent participant adherence. Daily monitoring of individual adherence was based on meal attendance, body weight measurements, and daily diaries. Urinary sodium, potassium, phosphorus, and urea nitrogen values and an anonymous poststudy survey were used to evaluate adherence at the end of the study. Most DASH participants adhered to the feeding regimen by consuming only study foods and no other foods. When adherence lapsed, participants generally cited the lack of menu variety as a reason. Successful participant adherence to the constraints of an outpatient controlled feeding study is possible with carefully selected participants and a variety of adherence-promoting strategies incorporated into the study protocol.

Dietary Approaches to Stop Hypertension: rationale, design, and methods. DASH Collaborative Research Group

Epidemiologic studies across societies have shown consistent differences in blood pressure that appear to be related to diet. Vegetarian diets are consistently associated with reduced blood pressure in observational and interventional studies, but clinical trials of individual nutrient supplements have had an inconsistent pattern of results. Dietary Approaches to Stop Hypertension (DASH) was a multicenter, randomized feeding study, designed to compare the impact on blood pressure of 3 dietary patterns. DASH was designed as a test of eating patterns rather than of individual nutrients in an effort to identify practical, palatable dietary approaches that might have a meaningful impact on reducing morbidity and mortality related to blood pressure in the general population. The objectives of this article are to present the scientific rationale for this trial, review the methods used, and discuss important design considerations and implications.

The effects of dietary patterns on quality of life: a substudy of the Dietary Approaches to Stop Hypertension trial

Few studies have examined the effects of dietary changes, particularly modifications of whole dietary patterns, on quality of life. The Dietary Approaches to Stop Hypertension (DASH) trial compared the effects of 3 dietary patterns on blood pressure. In this substudy, we examined the effect of these diets on health-related quality of life. All DASH participants ate a control diet for 3 weeks and then were randomly assigned to continue the control diet, to a fruits and vegetables diet or to a combination diet for 8 weeks. The combination diet emphasized fruits, vegetables, and low-fat dairy products. It included whole grains, poultry, fish, and nuts, and was reduced in fats, red meat, sweets, and sugar-containing beverages. The control diet was similar to typical American intake; the fruits and vegetables diet was rich in fruits and vegetables but was otherwise similar to the control diet. Both the fruits and vegetables diet (P < .001) and the combination diet (P < .001) significantly lowered blood pressure. At the Duke University Medical Center, Durham, NC, site, participants completed the Medical Outcomes Study Short Form-36 questionnaire to assess their health-related quality of life at baseline and at the end of the dietary intervention. Eighty-three participants completed the questionnaires at both time points. In general, health-related quality of life improved in all treatment groups except for the control group in perceptions of change in health, which diminished. In the combination diet group all the subscales were improved or unchanged compared with baseline values. However, only the change in health score improved significantly (P < .05) as compared with that of the control diet group. When all the subscales were summed into a total score, the control diet was associated with mean improvement of 4.0%, the fruits and vegetables diet with 5.0%, and the combination diet with 5.9% from baseline. These data suggest that the fruits and vegetables diet and particularly the combination diet cannot only lower blood pressure, but may also improve the perception of health-related quality of life.

Dietary Approaches to Stop Hypertension: a summary of study results. DASH Collaborative Research Group

The Dietary Approaches to Stop Hypertension multicenter trial examined the impact of dietary patterns on blood pressure in 459 adults with blood pressure < 160 mm Hg systolic and 80 to 95 mm Hg diastolic. After a 3-week run-in period on a control diet low in fruits, vegetables, and dairy products, and with a fat content typical for Americans, participants were randomized for 8 weeks to either the control diet, a diet rich in fruits and vegetables, or a combination diet that emphasized fruits, vegetables, and low-fat dairy products. Body weight and sodium intake were held constant, and physical activity did not change during the intervention. Baseline mean +/- standard deviation systolic and diastolic blood pressures were 131.3 +/- 10.8 mm Hg and 84.7 +/- 4.7 mm Hg, respectively. Relative to the control diet, the combination diet reduced blood pressure by 5.5 mm Hg and diastolic blood pressure by 3.0 mm Hg (P < .001). For those on the fruits and vegetables diet, blood pressure reductions relative to control were 2.8 mm Hg systolic (P < .001) and 1.1 mm Hg diastolic (P < .07). In 133 participants with hypertension, the combination diet produced a net blood pressure reduction of 11.4 and 5.5 mm Hg systolic and diastolic, respectively (P < .001). In participants without hypertension (n = 326), the corresponding blood pressure reductions were 3.5 mm Hg systolic (P < .001) and 2.1 mm Hg diastolic (P < .003). In other subgroup analyses, minorities showed relatively larger reductions in blood pressure than nonminorities (P < .001). We conclude that the dietary pattern reflected in the combination diet can substantially reduce blood pressure, and, accordingly, provides an additional lifestyle approach to preventing and treating hypertension.

Pre-enrollment diets of Dietary Approaches to Stop Hypertension trial participants. DASH Collaborative Research Group

A large body of evidence suggests that several nutrients are related to blood pressure. Less is known about the eating patterns of special populations, such as those at risk for hypertension, or how demographic factors affect the diets of these populations. This article characterizes the usual diets of participants before they enrolled in the Dietary Approaches to Stop Hypertension (DASH) trial. During screening for DASH, 380 participants completed the National Cancer Institute food frequency questionnaire. Nutrient and food group intake, the Keys score (a measure of a diet's atherogenicity), and the Diet Quality Index were estimated from the food frequency questionnaire. The effects of age, sex, race, baseline weight, and education on these dietary factors were assessed among DASH participants and compared with similar data from the Third National Health and Nutrition Examination Survey and other published reports. Among DASH participants, African-Americans reported lower intakes of dairy products (P < .001), calcium (P < .001), and magnesium (P < .05) than did whites. Older women reported greater intakes of calcium, magnesium, and potassium (all P < .05) and less fat (P < .05) than did younger women. Older men consumed fewer servings of fruits (P < .03), less vitamin C (P < .05), and had a higher Keys score (P < .05) than did younger men. Heavier (body mass index > or = 25) participants reported lower intakes of protein and potassium, but higher fat and energy intakes (all P < .05). Taken together, these data show that younger, overweight African-American women have the least healthful diets, because they consume more atherogenic foods and fewer of the nutrients related to decreased blood pressure. Overall Diet Quality Index scores did not differ between African-American and white participants. Despite differences in dietary assessment methods between the population samples of DASH and the Third National Health and Nutrition Examination Survey, within each population sample patterns of micronutrient intake were similar between African-American and white participants.

The DASH Diet, Sodium Intake and Blood Pressure Trial (DASH-sodium): rationale and design. DASH-Sodium Collaborative Research Group

The DASH Diet, Sodium Intake and Blood Pressure Trial (DASH-Sodium) is a multicenter, randomized trial comparing the effects of 3 levels of sodium intake and 2 dietary patterns on blood pressure among adults with higher than optimal blood pressure or with stage 1 hypertension (120-159/80-95 mm Hg). The 2 dietary patterns are a control diet typical of what many Americans eat, and the DASH diet, which, by comparison, emphasizes fruits, vegetables, and low-fat dairy foods, includes whole grains, poultry, fish, and nuts, and is reduced in fats, red meat, sweets, and sugar-containing beverages. The 3 sodium levels are defined as higher (typical of current US consumption), intermediate (reflecting the upper limit of current US recommendations), and lower (reflecting potentially optimal levels). Participants are randomly assigned to 1 of the 2 dietary patterns using a parallel group design and are fed each of the 3 sodium levels using a randomized crossover design. The study provides participants with all of their food during a 2-week run-in feeding period and three 30-day intervention feeding periods. Participants attend the clinic for 1 meal per day, 5 days per week, and take home food for other meals. Weight is monitored and individual energy intake adjusted to maintain baseline weight. The primary outcome is systolic blood pressure measured at the end of each intervention feeding period. Systolic blood pressure is compared across the 3 sodium levels within each diet and across the 2 diets within each sodium level. If effects previously observed in clinical trials are additive, sodium reduction and the DASH diet together may lower blood pressure to an extent not as yet demonstrated for nonpharmacologic treatment. The DASH-Sodium results will have important implications for the prevention and treatment of high blood pressure.

The Linear Index Model for establishing nutrient goals in the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group

Establishing target levels of nutrients in feeding studies presents a challenge to dietitians. Although researchers studying energy-containing nutrients, such as protein and fat, commonly establish target levels according to body weight or as a percentage of energy, it is less clear how to establish levels of micronutrients. Typically, a constant target level is used regardless of energy requirements. Alternatively, nutrients could be provided at a fixed level per 1,000 kcal. Such an approach, however, could result in absolute levels of nutrient intakes that are difficult to achieve through foods alone, particularly for persons with high energy requirements. This report describes the Linear Index Model, a new approach for establishing target levels of selected micronutrients in the Dietary Approaches to Stop Hypertension trial. This model indexes micronutrient levels to energy levels to achieve a linear range of targeted intake in proportion to the energy intake. The Linear Index Model has several benefits: it takes advantage of indexing nutrients according to energy requirements, thus providing levels of nutrient intakes that can be readily achieved by foods; it is based on population consumption data, thus providing a realistic range of intakes for the experimental conditions; and it ensures distinct contrasts in experimental conditions. The Linear Index Model is a feasible and practical approach for establishing target levels of nutrients in feeding studies.

Validation of diet composition for the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group

The Dietary Approaches to Stop Hypertension trial involved 4 clinical sites at which 459 participants (in 5 cohorts) were fed 3 dietary patterns over 11 weeks per cohort. The 3 patterns were a control diet, a fruits and vegetables diet, and a combination diet. Before the intervention, key nutrient levels in each diet were validated at 2 energy levels (2,100 and 3,100 kcal) by chemical analysis of the prepared menus. During intervention, diets were sampled across all cohorts, sites, and energy levels, and 7-day menu cycle composites were assayed. In general, sodium, potassium, calcium, and magnesium in the validated menus for each diet/energy level met the nutrient targets, though moderate variability was evident among individual menus, particularly for potassium, calcium, and magnesium. However, as intended, there was clear separation and no overlap in mineral levels in individual menus of diets that were designed to differ. During intervention, macronutrient contents met nutrient goals. Sodium, potassium, calcium, and magnesium in the diets generally met target levels, though potassium in the fruits and vegetables diet was 11% to 23% below target. There were no consistent differences in nutrient levels between sites. The mean nutrient levels in the validated menus and diets sampled during intervention were in excellent agreement with each other, though sodium was somewhat higher (approximately 6%) in the diets from intervention vs validation. These results indicate the success of the quality control measures implemented and suggested consistent overall diet composition throughout the 28 months during which the study was conducted.

Descriptive characteristics of the dietary patterns used in the Dietary Approaches to Stop Hypertension Trial. DASH Collaborative Research Group

The Dietary Approaches to Stop Hypertension trial was a randomized, multicenter, controlled feeding study to compare the effect on blood pressure of 3 dietary patterns: control, fruits and vegetables, and combination diets. The patterns differed in selected nutrients hypothesized to alter blood pressure. This article examines the food-group structure and nutrient composition of the study diets and reports participant nutrient consumption during intervention. Participants consumed the control dietary pattern during a 3-week run-in period. They were then randomized either to continue on the control diet or to change to the fruits and vegetables or the combination diet for 8 weeks. Sodium intake and body weight were constant during the entire feeding period. Analysis of variance models compared the nutrient content of the 3 diets. Targeting a few nutrients thought to influence blood pressure resulted in diets that were profoundly different in their food-group and nutrient composition. The control and fruits and vegetables diets contained more oils, table fats, salad dressings, and red meats and were higher in saturated fat, total fat, and cholesterol than was the combination diet. The fruits and vegetables and combination diets contained relatively more servings of fruits, juices, vegetables, and nuts/seeds, and were higher in magnesium, potassium, and fiber than was the control diet. Both the fruits and vegetables and combination diets were low in sweets and sugar-containing drinks. The combination diet contained a greater variety of fruits, and its high calcium content was obtained by increasing low-fat dairy products. In addition, the distinct food grouping pattern across the 3 diets resulted in substantial differences in the levels of vitamins A, C, E, folate, B-6, and zinc.

Comparison of 4 nutrient databases with chemical composition data from the Dietary Approaches to Stop Hypertension trial. DASH Collaborative Research Group

Accuracy of computerized nutrient databases is an important consideration in selecting a nutrient analysis system. We project compared the nutrient content of daily menus calculated from 4 microcomputer programs to chemical analysis of menus analyzed for the Dietary Approaches to Stop Hypertension (DASH) trial. Thirty-six menus were entered at 2 independent DASH sites using the ESHA Food Processor, Minnesota Nutrition Data System, Moore's Extended Nutrient Database, and Nutritionist IV databases. Food prepared according to these menus was chemically analyzed at the Food Analysis Laboratory Control Center at Virginia Polytechnic Institute and State University, Department of Biochemistry, Blacksburg. Estimates for 13 nutrients were compared: energy, total fat, saturated fat, monounsaturated fat, polyunsaturated fat, carbohydrate, protein, cholesterol, calcium, potassium, magnesium, iron, and sodium. The overall intraclass correlation between the 2 sites' data entry was 0.998; thus, values were averaged for analyses. Databases varied significantly in their mean deviations from chemical analyses values for saturated, monounsaturated, and polyunsaturated fatty acids, potassium, magnesium, and iron (P < .05); however, these differences were small (< 10%). Absolute deviations, which estimate the combined effect of bias and precision, were significantly different among databases for energy, saturated fatty acids, and polyunsaturated acids. Absolute differences from the laboratory values varied by < 15%, except for iron. All 4 databases were comparable in accuracy and precision and performed well. Criteria for database selection depends not only on overall database accuracy, especially for nutrients of interest, but also on the ease of use of the program, relevant features of the associated software; and cost.

A dietary approach to prevent hypertension: a review of the Dietary Approaches to Stop Hypertension (DASH) Study

BACKGROUND

Populations eating mainly vegetarian diets have lower blood pressure levels than those eating omnivorous diets. Epidemiologic findings suggest that eating fruits and vegetables lowers blood pressure.

HYPOTHESIS

Two hypotheses were tested: (1) that high intake of fruits and vegetables lowers blood pressure, and (2) that an overall dietary pattern (known as the DASH diet, or DASH combination diet) that is high in fruits, vegetables, nuts, and low-fat dairy products, emphasizes fish and chicken rather than red meat, and is low in saturated fat, cholesterol, sugar, and refined carbohydrate lowers blood pressure.

METHODS

Participants were 459 adults with untreated systolic blood pressure < 160 mmHg and diastolic blood pressure 80-95 mmHg. After a 3-week run-in on a control diet typical of Americans, they were randomized to 8 weeks receiving either the control diet, or a diet rich in fruits and vegetables, or the DASH diet. The participants were given all of their foods to eat, and body weight and sodium intake were held constant. Blood pressure was measured at the clinic and by 24-h ambulatory monitoring.

RESULTS

The DASH diet lowered systolic blood pressure significantly in the total group by 5.5/3.0 mmHg, in African Americans by 6.9/3.7 mmHg, in Caucasians by 3.3/2.4 mmHg, in hypertensives by 11.6/5.3 mmHg, and in nonhypertensives by 3.5/2.2 mmHg. The fruits and vegetables diet also reduced blood pressure in the same subgroups, but to a lesser extent. The DASH diet lowered blood pressure similarly throughout the day and night.

CONCLUSIONS

The DASH diet may offer an alternative to drug therapy in hypertensives and, as a population approach, may prevent hypertension, particularly in African Americans.

Interactive 3-D virtual colonoscopy system

We describe a low-cost three-dimensional (3-D) virtual colonoscopy system that is a noninvasive technique for examining the entire colon and can assist physicians in detecting polyps inside the colon. Using the helical CT data and proposed techniques, we can three-dimensionally reconstruct and visualize the inner surface of the colon. We generate high resolution of video views of the colon interior structures as if the viewer's eyes were inside the colon. The physicians can virtually navigate inside the colon in two different modes: interactive and automatic navigation, respectively. For automatic navigation, the flythrough path is determined a priori using the 3-D thinning and two-pass tracking schemes. The whole colon is spatially subdivided into several cells, and only potentially visible cells are taken into account during rendering. To further improve rendering efficiency, potentially visible cells are rendered at different levels of detail. Additionally, a chain of bounding volume in each cell is used to avoid penetrating through the colon during navigation. In comparison with previous work, the proposed system can efficiently accomplish required preprocessing tasks and afford adequate rendering speeds on a low-cost PC system.

Intestinal volvulus following laparoscopic cholecystectomy

The introduction of laparoscopic cholecystectomy has revolutionized the surgical management of biliary diseases. As the application of this procedure becomes more popular, a variety of associated complications have emerged. We present a rare case of a patient who developed an intestinal volvulus 3 days following laparoscopic cholecystectomy. The precipitating factors of this complication and review of literature are discussed.

Dose-specific production of chlorinated quinone and semiquinone adducts in rodent livers following administration of pentachlorophenol

Production of chlorinated quinoid metabolites was investigated in the livers of Sprague-Dawley rats and B6C3F1 mice following single oral administration of pentachlorophenol (PCP) (0-40 mg/kg body weight) and in male Fischer 344 rats, following chronic ingestion of PCP at 1,000 ppm in the diet for 6 months (equivalent to 60 mg PCP/kg body weight/day). Analyses of the rates of adduction in the livers of Sprague-Dawley rats and B6C3F1 mice suggested that the production of tetrachloro-1,2-benzosemiquinone (Cl4-1,2-SQ) adducts was proportionally greater at low doses of PCP (less than 4-10 mg/kg body weight) and was 40-fold greater in rats than in mice. Production of tetrachloro-1,4-benzoquinone (Cl4-1,4-BQ) adducts, on the other hand, was proportionally greater at high doses of PCP [greater than 60-230 mg/kg body weight] and was 2- to 11-fold greater in mice than in rats over the entire range of dosages. A mathematical model employed these data to predict the rates of daily adduct production and steady state levels of PCP-derived quinone and semiquinone adducts in rats and mice. To evaluate predictions of the model, levels of PCP-derived adducts at steady state were investigated in the livers of male Fischer 344 rats chronically ingesting 60 mg PCP/kg body weight/day. Levels of total Cl4-1,4-BQ-derived adducts in liver cytosolic proteins (Cp) (22.0 nmol/g) and in liver nuclear proteins (Np) (3.07 nmol/g) were comparable to those of model predictions (15.0 and 3.02 nmol/g for Cp and Np, respectively). Overall, these results suggest that species differences in the metabolism of PCP to semiquinones and quinones were, in part, responsible for the production of liver tumors in mice but not rats in chronic bioassays.

Accuracy of stereotactic core-needle breast biopsy in atypical ductal hyperplasia

BACKGROUND

The histologic diagnosis of atypical ductal hyperplasia (ADH) has been reported as having a high rate of malignancy, either ductal carcinoma in situ (DCIS) or invasive ductal carcinoma (IDC). We reviewed our surgical group's experience with stereotactic core-needle biopsies (SCNB), specifically looking at the follow-up of ADH.

METHODS

From November 1994 through July 1997 our group performed 539 SCNB. Twenty-one patients (4%) were diagnosed as ADH. Eighteen patients had subsequent wire-localized excisional biopsies. Three patients were followed up mammographically. One patient refused follow-up.

RESULTS

Of the 18 patients who underwent excisional biopsies, 2 patients were found to have DCIS and 1 patient had lobular carcinoma in-situ. There were no cases of IDC.

CONCLUSION

Our results show a much lower incidence of malignancy in cases of ADH found on SCNB than has been previously reported. While the standard of care is still to follow up ADH found on SCNB with excisional biopsy, more data may justify following up certain subsets of patients.

Fibroblast growth factor-2-toxin induced cytotoxicity: differential sensitivity of co-cultured vascular smooth muscle cells and endothelial cells

Recombinant FGF-2-SAP is a mitotoxin consisting of the plant-derived ribosome-inactivating toxin saporin (SAP) fused to basic fibroblast growth factor (FGF-2). FGF-2-SAP targets and kills cells bearing upregulated FGF receptors. In vivo, FGF-2-SAP inhibits smooth muscle cell hyperplasia in models of restenosis. The present study examined the potential for a differential effect of FGF-2-SAP on canine vascular endothelial cells (EC) and smooth muscle cells (SMC) separately as well as in a novel co-culture model. Canine vascular SMC and EC cultures were established separately and made quiescent once cells reached 80% confluence. Following the release from growth arrest, both cell types were treated with FGF-2-SAP, or FGF-2, or SAP alone for 48 h. [3H]TdR incorporation was used to determine the growth response of SMC and EC. The co-culture system was created by plating canine vascular SMC and EC on either side of a microporous 13 microm thick polyester membrane insert. Both cell types were grown to 80% confluence and independently made quiescent. Following the release from growth arrest, cells were treated with FGF-2-SAP, or FGF-2, or SAP alone. Negative and positive control groups were untreated wells containing phosphate buffered saline and complete growth media, respectively. After 48 h, both [3H]TdR incorporation and total DNA content, by fluorometric measurement, were quantitated in SMC and EC independently. FGF-2-SAP showed a concentration-dependent cytotoxicity in both canine SMC and EC but cytotoxicity for EC required substantially higher concentrations. In co-cultured SMC, FGF-2-SAP significantly decreased both [3H]TdR uptake and total DNA content at 0.5, 5, 50, and 500 ng/ml (0.01-10 nM) compared to positive controls. In co-cultured EC, FGF-2-SAP decreased [3H]TdR uptake at 50 and 500 ng/ml and total DNA content at 500 ng/ml compared to positive controls. Neither SAP alone nor FGF-2 alone showed a significant effect on [3H]TdR uptake or DNA content of either SMC or EC. In this unique co-culture model, which better replicates the relationship between SMC and EC in vivo, we demonstrated a dose-response range of FGF-2-SAP at which both the proliferation and total cell number of SMC, but not EC, is significantly reduced. These data suggest that FGF-2-SAP may have therapeutic utility in inhibiting myointimal hyperplasia in the absence of a deleterious effect on regenerating endothelium following vascular reconstructions.

Inter-rater reliability and validity of the action research arm test in stroke patients

BACKGROUND AND PURPOSE

The Action Research arm test (ARAT) was constructed for assessing recovery of upper extremity function after cortical injury. The objective of the study was to verify the inter-rater reliability and validity of the ARAT in stroke patients.

METHODS

50 stroke patients participated in the study. For the purpose of inter-rater study, the ARAT was administered by three experienced raters on each patient within a 3-day period. Validity was assessed by comparing the patients' scores on the ARAT with those obtained for the other well-validated measurements evaluating upper extremity motor impairment and disability.

RESULTS

Intra-class correlation coefficient (ICC) for the total score was 0.98 indicating very high inter-rater reliability. ICCs were also very high in each of the subscales. The score of the ARAT was closely correlated with that of the upper extremity part of the motor assessment scale, the arm sub-score of the motricity index and the upper extremity movements of the modified motor assessment chart (Pearson r = 0.96, 0.87 and 0.94, respectively).

CONCLUSION

The preliminary results of this study support the value of the ARAT for measuring recovery of arm-hand function in stroke patients.

Reversible acylation of factor Xa as a potential therapy for hemophilia

Current therapies for treatment of hemophilia A involve infusion of factor VIII, but are ineffective for patients who develop inhibitory antibodies. We have previously proposed that bypassing the intrinsic pathway (VIIIa/IXa) with reversibly acylated factor Xa offers an improvement on existing therapies as it provides a time-dependent release of procoagulant activity without the addition of factors VIII or IX. The present study was designed to determine the effect of substituted 4-amidinophenyl benzoates on the acylation of factor Xa, as well as the subsequent deacylation rates of the resulting acyl Xa. A subset of this series of acyl Xa's were incorporated into the prothrombinase complex and recovery of catalytic activity was measured by activation of prothrombin to thrombin. Similarly, some acyl Xa's were also evaluated for their capacity to enhance clotting times of human plasma. Our study indicates that by choosing the appropriate acyl Xa, the time course of factor Xa regeneration can be modulated extensively. Animal studies will be required to show that the use of acyl Xa as a procoagulant agent is feasible in an in vivo system.

Dosimetry of chlorinated quinone metabolites of pentachlorophenol in the livers of rats and mice based upon measurement of protein adducts

The dosimetry of chlorinated quinones arising from metabolism of pentachlorophenol (PCP), in the livers of male Sprague-Dawley rats and B6C3F1 mice was investigated via measurements of cysteinyl protein adducts and estimates of the second-order reaction rate constants between the quinones and the proteins. We had previously shown that adducts of tetrachloro-1,4-benzoquinone (Cl4-1,4-BQ) and tetrachloro-1,2-benzosemiquinone (Cl4-1,2-SQ) were observed at the highest levels in the livers of Sprague-Dawley rats to which PCP had been administered by gavage (5-40 mg/kg body wt) (Biomarkers 1, 232-243, 1996). In the current study we observed that adducts of Cl4-1,4-BQ and tetrachloro-1,2-benzoquinone (CL4-1,2-BQ) were predominant in the livers of B6C3F1 mice receiving 20 mg PCP/kg body wt. The second-order rate constants, representing in vitro reactions between Cl4-1,2-BQ and Cl4-1,4-BQ and various cysteine residues of hepatic proteins of liver cytosol and liver nuclei, were estimated to be 0.012-1.96 L(g protein)(-1) hr(-1) in rats and 0.082-1.67 L(g protein)(-1) hr(-1) in mice. The estimated tissue doses of the quinones to liver cytosol decreased in the order rat Cl4-1,4-BQ > mouse Cl4-1,4-BQ > mouse Cl4-1,2-BQ and to liver nuclei in the order mouse Cl4-1,2-BQ > mouse Cl4-1,4-BQ > rat Cl4-1,4-BQ. The corresponding doses of Cl4-1,2-SQ could not be inferred due to our inability to estimate the second-order rate constants. After aggregating the estimated contributions of all quinone species, mice had a fourfold greater dose to liver nuclei than rats, whereas rats had a threefold greater dose to liver cytosol. The increased nuclear dose to mouse liver compared to that of the rat suggests that the mouse is at greater risk to hepatic DNA damage from PCP-derived quinones. Investigation of the time course of levels of unconjugated tetrachlorohydroquinone (Cl4HQ) in the livers indicated that about 0.4% of Cl4HQ was oxidized to Cl4-1,4-BQ in both rats and mice.

A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group

BACKGROUND

It is known that obesity, sodium intake, and alcohol consumption factors influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure.

METHODS

We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a "combination" diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels.

RESULTS

At base line, the mean (+/-SD) systolic and diastolic blood pressures were 131.3+/-10.8 mm Hg and 84.7+/-4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P<0.001 for each); the fruits-and-vegetables diet reduced systolic blood pressure by 2.8 mm Hg more (P<0.001) and diastolic blood pressure by 1.1 mm Hg more than the control diet (P=0.07). Among the 133 subjects with hypertension (systolic pressure, > or =140 mm Hg; diastolic pressure, > or =90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003).

CONCLUSIONS

A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension.

Metabolic and behavioral effects of a high-sucrose diet during weight loss

In response to evidence linking obesity and high amounts of dietary fat, the food industry has developed numerous reduced-fat and nonfat food items. These items frequently derive a relatively large percentage of their energy from sugars and the effect of these sugars on weight regulation is not well known. We studied the comparative effects of high- and low-sucrose, low-fat, hypoenergetic diets on a variety of metabolic and behavioral indexes in a 6-wk weight-loss program. Both diets contained approximately 4606 kJ energy/d with 11% of energy as fat, 19% as protein, and 71% as carbohydrate. The high-sucrose diet contained 43% of the total daily energy intake as sucrose; the low-sucrose diet contained 4% of the total daily energy intake as sucrose. Twenty women aged 40.6 +/- 8.2 y (mean +/- SD) with a body mass index (in kg/m2) of 35.93 +/- 4.8 consumed the high-sucrose diet; 22 women aged 40.3 +/- 7.3 y with a body mass index of 34.93 +/- 4.4 consumed the low-sucrose diet. Mixed-design analysis of variance showed a main effect of time (P < 0.01), with both diet groups showing decreases in weight, blood pressure, resting energy expenditure, percentage body fat, free triiodothyronine (FT3), urinary norepinephrine, and plasma lipids. Small but significant interactions were found between group and time in total cholesterol (P = 0.009) and low-density lipoprotein (LDL) (P = 0.01). Both groups showed decreases in depression, hunger, and negative mood, and increases in vigilance and positive mood with time (P < 0.01). Results showed that a high sucrose content in a hypoenergetic, low-fat diet did not adversely affect weight loss, metabolism, plasma lipids, or emotional affect.

Cells in vivo and in vitro from osteopetrotic mice homozygous for c-src disruption show suppression of synthesis of osteopontin, a multifunctional extracellular matrix protein

Mice carrying homozygous disruption of the c-src proto-oncogene (Src-/-) develop osteopetrosis due to an impaired ability of osteoclasts to adhere to the bone surface and/or to form bone-resorbing ruffled border. It has also been reported that osteopontin (OPN), a secreted phosphoprotein, mediates osteoclast adherence to the bone matrix. We report here that cells from Src-/- mice, both in vitro and in vivo, express OPN mRNA and protein at a significantly reduced level as compared to cells from Src+/- and +/+ animals, suggesting a potential role for the proto-oncogene c-src in the regulation of OPN gene expression. Our data also show that OPN gene expression can be induced by treatment of SR-/- cells with epidermal growth factor (EGF) and 12-O-tetradecanoyl phorbol-13-acetate (TPA). Results obtained from studies using inhibitors of receptor tyrosine kinases (RTKs) and protein kinase C (PKC) suggest that PKC and RTK are positioned in a pathway with PKC as the downstream effector for the EGF-induced OPN gene expression in SRC-/- cells, and that pp60c-src and EGF may regulate OPN gene expression through a common signalling pathway. Furthermore, contrary to published reports, our study shows that EGF-mediated cell signalling does not require functional interaction between the EGF-receptor and pp60c-src.

Characterization of chlorinated adducts of hemoglobin and albumin following administration of pentachlorophenol to rats

Five cysteinyl adducts (including one with multiple isomeric forms) of hemoglobin (Hb) and albumin (Alb) have been characterized in the blood of Sprague-Dawley rats following administration of pentachlorophenol (PCP). Three of these adducts were formed by multiple substitution reactions of tetrachloro-1,4-benzoquinone (Cl4-1,4-BQ) and its products, and two arose from reactions of tetrachloro-1,4-benzosemiquinone (Cl4-1,4-SQ) and tetrachloro-1,2-benzosemiquinone (Cl4-1,2-SQ). Adducts of tetrachloro-1,2-benzoquinone (Cl4-1,2-BQ) were not observed. Regarding adducts of Cl4-1,4-BQ and its products, specific structures were assigned to monosubstituted, disubstituted, and trisubstituted adducts of Hb and Alb following modification of rat blood with Cl4-1,4-BQ (0-45 microM) in vitro and after metabolism of PCP (0-40 mg/kg body weight) in Sprague-Dawley rats, in vivo. The formation of all adducts was linear over the ranges tested, with Alb adducts being more abundant than Hb adducts. The levels of the adducts measured were in the following order: monosubstituted > disubstituted > trisubstituted. The observation that Cl4-1,4-BQ can produce multisubstituted adducts with proteins suggests that protein-protein cross links may be formed, with inherent toxicological implications. Regarding adducts of the semiquinones (detected only in vivo), linear production of Hb and Alb adducts was observed with increasing dosage of PCP for adducts of both Cl4-1,4-SQ and Cl4-1,2-SQ. Higher levels of the semiquinone adducts were observed in Hb than in Alb, in contrast to the results with the quinone adducts. In a separate in vivo experiment (20 mg PCP/kg body weight), where animals were sacrificed at intervals up to 336 h postadministration, adducts were eliminated at rates which were comparable among the different adducts of a given protein.

Procoagulant activity of reversibly acylated human factor Xa

The plasma clotting factors used to treat hemophiliacs who have developed inhibitory antibodies have a shared history of limited clinical safety and utility. To improve on existing bypass factors, we have developed a reversibly acylated form of human plasma factor Xa capable of providing a time-dependent release of procoagulant activity. Factor Xa was treated with p-amidinophenyl p'-anisate to generate anisoyl Xa. The chemical modification of the protein involves acylation of the active site serine residue of factor Xa. Anisoyl Xa deacylated in a time, pH, and temperature-dependent manner. Active factor Xa generated on deacylation of anisoyl Xa exhibited amidolytic and prothrombinase complex activities in in vitro assays, the level being comparable to those of untreated factor Xa. When Anisoyl Xa was infused into rabbits, active factor Xa was generated on deacylation of the acylated enzyme, which shortened the activated partial thromboplastin time (APTT) in a dose-dependent manner. The duration of effect on rabbit APTT could be directly correlated to the level of human plasma factor Xa. Because anisoyl Xa bypasses the "tenase" complex that is compromised in hemophilia A and B and is unaffected by inhibitory antibodies, it has the potential to be used as an effective bypass therapy.

Community dwelling elderly are appropriate subjects for intensive dietary choice restriction studies

There is a traditional belief that the elderly have difficulty coping with dietary change, and therefore have a diminished likelihood of successfully responding to nutritional interventions or restrictions. Using a controlled mild zinc-deficiency feeding study as a model for strict dietary intervention, we assessed psychological responses to severe dietary choice restriction in 15 Caucasian, elderly (66.12 +/- 4.43 years) males (n= 7) and females (n = 8). Participants completed the Medical Outcomes Study Short Form 36-Item Questionnaire (SF-36) as an index of QOL and the Multi-dimensional Health Locus of Control (MHLC) as a measure of health beliefs at pre-intervention baseline, post-intervention, and follow-up. No subjects dropped out nor were any meals missed during the entire 21-day feeding study period. No significant differences were detected across time on the MHLC (Internal F = 0.53, P = 0.6; Powerful Others F = 0.28, P = 0.8; Chance F = 1.1, P = 0.4.) by one-way ANOVA. Similarly, for the SF-36 no significant differences were found across time (F = 0.76, P = 0.5). Our results suggest that restricting dietary choices does not negatively impact older adult subjects and that they can cope well with dietary choice restriction and change. Older adults should not be overlooked for nutritional intervention solely due to age considerations.

In vivo tissue distribution of fibroblast growth factor-1 after intraarterial delivery

The clinical applicability of fibroblast growth factor-1 (FGF-1) plus heparin delivery in optimizing the healing of both autogenous vein and synthetic vascular grafts has been suggested. The authors have reported enhanced endothelial cell proliferation, concurrent increased capillarization, and minimal intimal hyperplasia using suspensions of FGF-1 and heparin impregnated onto expanded polytetrafluoroethylene grafts. The current study characterizes the tissue distribution of 125I-FGF-1 delivered by continuous intraarterial infusion. 125I-FGF-1 delivered by continuous intraarterial infusion. 125I-FGF-1 (1.1 ng) and heparin (28 U) were continuously infused into the thoracic aorta via the proximal end of the ligated left carotid artery for 24 hr in four New Zealand white rabbits using an Alzet (Alza Corp., Palo Alto, CA) osmotically activated pumping device. Rabbits were sacrificed after 24 hr, exsanguinated, and biopsies taken from the liver, kidneys, spleen, lungs, heart, thyroid gland, muscle, and fat. These samples were assayed for radioactivity and results expressed as cpm 125I/gram of both wet and dry weight of tissue. 125I-FGF-1 uptake (cpm/g dry wt.) was greatest in the thyroid (551.1 +/- 131.4). This was 2.5-5.5 x greater (p < or = 0.01) than those organs with intermediate uptake (lungs, liver, kidneys, spleen, and heart). Lowest uptake was noted in the blood, muscle, and fat. A similar distribution pattern was found in wet weight comparisons. Total organ 125I-FGF-1 content was greatest in the liver at 818.1 +/- 176.3 cpm (p < or = 0.002) and intermediate in the lungs (204.7 +/- 38.5 cpm) and kidneys (191.2 +/- 11.9 cpm). Although no FGF-1-induced toxicity has yet been reported, these results will allow for future tissue-specific toxicology studies before clinical trials.

Treating esophageal cancer with a combination of chemotherapy, radiation, and excision

BACKGROUND

Treatment of esophageal cancer has been primarily palliative. Recent studies have shown that preoperative combination chemo- and radiation therapy increases the effectiveness of surgical excision.

PATIENTS AND METHODS

Beginning in 1990, 29 patients in the Spokane area were treated with preoperative chemo- and radiation therapy. They were 23 men and 6 women whose mean age was 66 years. Twenty-five had adenocarcinoma, of whom 3 had Barrett's esophagitis. Four had squamous cell carcinoma. The chemotherapy included fluorouracil, cisplatin, and vinblastine. Radiation was given concomitantly, BID for 21 days. Surgical excision was performed about 3 weeks after the last radiation session, pending recovery from cytopenia.

RESULTS

There was 1 operative death, for an operative mortality of 3.4%. Twenty-three patients (79%) were found to have no residual cancer at the time of resection. Of this group, 8 died of metastatic cancer at a mean of 15 months postoperatively (range 1 to 28), and 15 were alive at a mean of 28 months (range 12 to 46). Six patients (21%) had residual cancer in the resected specimen, either at the primary site or--more often--in adjacent lymph nodes. Five have died at 6, 8, 9, 24, and 28 months postoperatively; 1 remains alive at 14 months. The mean survival among these 6 patients is 15 months.

CONCLUSIONS

Combined chemo- and radiation therapy prior to esophagectomy appeared to improve outcome in this small series of patients with esophageal cancer. Local control was excellent, but distant metastasis continues to be a significant problem.

Rationale and design of the Dietary Approaches to Stop Hypertension trial (DASH). A multicenter controlled-feeding study of dietary patterns to lower blood pressure

Epidemiologic studies have found that dietary patterns characterized by high intakes of certain minerals and fiber are associated with low blood pressure. Dietary Approaches to Stop Hypertension (DASH) is a multicenter, randomized, controlled-feeding trial designed to test the effects on blood pressure of two such dietary patterns consumed for 8 weeks. The two experimental diets will be compared with each other and with a control dietary pattern that is relatively low in potassium, magnesium, calcium, and fiber, and has a fat and protein profile mirroring current consumption. The first experimental diet, arguably termed "ideal," is high in fruits, vegetables, whole cereal products, low-fat dairy products, fish, chicken, and lean meats designed to be low in saturated fat and cholesterol; moderately high in protein; and high in minerals and fiber. The second experimental diet tests the effect of fruits and vegetables alone. Its potassium, magnesium, and dietary fiber content will be at the same high levels as the ideal dietary pattern, while its fat, protein, and calcium content will resemble that of the control dietary pattern. The study population will consist of 456 healthy men and women, aged 22 years or older, with systolic blood pressure less than 160 mm Hg and diastolic blood pressure 80 to 95 mm Hg. African-American and other minority groups will comprise 67% of the population. Participants will eat one of the three dietary patterns. The DASH trial has unique features. First, dietary patterns rather than single nutrients are being tested. Second, all food for the experimental diets is provided to the participants using a standardized multicenter protocol. Because the dietary patterns are constructed with commonly consumed food items, the results, if positive, may be conveniently implemented in dietary recommendations to the general public.

Transformation of mouse cells by wild-type mouse c-Src

Previous studies in which chicken and human c-Src were overexpressed in chicken and rodent cells have indicated that overexpression of wild-type c-Src can not induce complete neoplastic transformation. However, studies with v-Src mutants have demonstrated that species-specific differences can play a significant role in transforming activity. Here we show that, in contrast to chicken c-Src, overexpressed mouse c-Src can induce significant anchorage-independent growth and tumorigenicity when transfected into NIH3T3 mouse cells. The biochemical cause for this difference is unknown. In particular, the protein-tyrosine kinase activities of chicken and mouse c-Src appear to be similar. This result is consistent with the hypothesis that v-Src-induced transformation results from perturbation of signalling pathways modulated by c-Src and highlights the need for caution in controlling for potential species-specific differences in studies of c-Src function.

Marginal zinc deficiency in older adults: responsiveness of zinc status indicators

OBJECTIVE

Suspicions that mild zinc deficiency is common among the elderly cannot be confirmed or refuted because definitive indicators of zinc status are lacking. The goal of this study was to document the clinical responsiveness of parameters of zinc status in a group of older adults consuming a carefully controlled diet: first moderately low in zinc (3.97 mg/day for 15 days) and then high in zinc (28.19 mg/day for 6 days).

METHODS

Fifteen older adults (mean age = 66.6 yrs) volunteered to consume a marginally zinc-deficient diet for 15 days followed by 6 days of zinc repletion. Plasma concentrations of erythrocyte metallothionein and the enzyme 5'-nucleotidase, as well as levels of zinc, alkaline phosphatase, copper and ceruloplasmin were measured before and after zinc depletion and repletion.

RESULTS

Plasma zinc levels were not altered during the study. Alkaline phosphatase (AP) values did not change in the expected direction, although a small decrease in AP following zinc repletion was statistically significant. Erythrocyte metallothionein results followed a pattern similar to that of alkaline phosphatase, little change, but a small, statistically significant drop after zinc repletion. As expected, there were no diet-associated changes in plasma copper and ceruloplasmin levels. In contrast, plasma concentrations of the enzyme 5'-nucleotidase decreased (p < 0.01) from 2.7 +/- 0.5 to 1.1 +/- 0.5 U during zinc depletion and increased (p < 0.05) to 2.2 +/- 0.4 U after 6 days of repletion.

CONCLUSIONS

Mild zinc deficiency is difficult to detect. In this study, traditional indicators such as plasma zinc and alkaline phosphatase did not change as would be expected in response to alterations in zinc intake. Likewise, erythrocyte metallothionein did not respond to altered zinc intakes as expected but this factor may reflect long-standing or more severe zinc depletion and thus requires additional study. Activity of the enzyme 5'-nucleotidase appears responsive to acute changes in zinc intake; however, more work is needed to define how well these activities will reflect zinc intake in other types of subjects.

Effect of gamma carboxylation on prothrombinase inhibitory activity of catalytically inactive factor XA

Recombinant catalytically inactive factor Xa (factor rXai) is capable of assembly into inactive prothrombinase complexes, thus serving as a competitive inhibitor (Ki = 0.3nM) of active factor Xa. In order to study the role of gamma carboxylation in prothrombinase complex assembly, we have prepared differentially gamma carboxylated factor rXai and have measured the activities of these proteins in prothrombinase complex inhibition and in extension of plasma clotting. A factor rXai preparation containing 8 out of a possible maximum of 11 g carboxyglutamic acid (GLA) residues was found to be as active as chemically inactivated plasma factor Xa which was fully gamma carboxylated. Loss of a single additional g carboxyglutamic acid in the recombinant protein, however lead to a marked loss in activity. Factor rXai preparation with 8 GLA residues is also detected by a monoclonal antibody specific for a GLA dependent epitope. Thus assembly of the factor Va/Xa complex on phospholipid membranes does not require the presence of all of the g carboxyglutamic acid residues present in the plasma protein.

Measurement of hemoglobin and albumin adducts of tetrachlorobenzoquinone

Tetrachloro-1,4-benzoquinone (Cl4BQ), a metabolite of pentachlorophenol (PCP), is believed to play a role in the genotoxicity of PCP. We have developed a method to measure the adducts of Cl4BQ with cysteine residues of hemoglobin (Hb) and albumin (Alb). This method employs the use of Raney nickel to selectively cleave the sulfur-bound adducts. Adducts of Hb and Alb with Cl4BQ were measured following modification of rat blood with Cl4BQ (0-90 microM) in vitro. The formation of both Hb and Alb adducts was linear over the entire range with second-order rate constants of 6.89 and 167 L mol-1 h-1, respectively. The proportions of the concentrations of these Hb and Alb adducts to those of all covalently-bound products were estimated to be 0.053 and 0.178, respectively, at initial Cl4BQ concentrations between 3 and 90 microM. The overall rate of reaction of Cl4BQ in rat blood (in vitro) was pseudo-first-order with an estimated half-time of 4.35 h. Hb and Alb adducts of Cl4BQ were also measured in vivo following oral administration of PCP to rats (0-20 mg/kg body wt). Linear production of Hb and Alb adducts was observed over the entire range of dosages, with slopes of 0.09 and 8.22 pmol of adduct (g of protein)-1 [(mg of PCP)/(kg body wt)]-1, respectively. On the basis of production of Hb adducts in vitro and in vivo, it is estimated that 2.7 x 10(-7) mol of Cl4BQ was released to the blood of rats per mole of PCP administered.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of prothrombinase and thrombin inhibitors in a novel rabbit model of non-occlusive deep vein thrombosis

A quantitative and non-occlusive deep vein thrombosis model was developed in rabbits. We used this model to test the antithrombotic activity of the prothrombinase complex inhibitors factor rXai and its chemical analog glutamyl-glycyl-arginyl chloromethyl ketone inactivated human factor Xa (EGR-Xai), along with the thrombin inhibitors D-phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) and heparin. Dose dependent effects of the inhibitors during constant infusion were monitored. Measurements included thrombus weights, hemostatic parameters and both cuticle and ear bleeding times. In this model, factor rXai and EGR-Xai had comparable in-vivo efficacy, and showed 80%-93% inhibition at plasma levels of 6.5 nM (rXai) and 8 nM (EGR-Xai). Effects on ex-vivo clotting times varied among the inhibitors. At 80-100% thrombus inhibition, factor rXai and EGR-Xai had no statistically significant effect, while PPACK extended thrombin clotting time (TCT) times 2.3-fold, and heparin prolonged both activated partial thromboplastin time (APTT), prothrombin time (PT) and TCT ex-vivo clotting times 6.9-, 1.2-, and 7-fold respectively. At these dosages, cuticle and ear bleeding times were prolonged for all inhibitors and showed increases of 177%-389% (cuticle) and 45%-129% (ear). Our results demonstrate that direct inhibition of prothrombinase complex assembly is effective in arresting venous thrombosis.

Expression, purification, and characterization of inactive human coagulation factor Xa (Asn322Ala419)

We have expressed in Chinese hamster ovary cells a catalytically inactive form of human factor Xa (factor rXai). A recombinant precursor of human factor Xa was inactivated by two point mutations in the serine protease catalytic triad, Asp322Asn and Ser419Ala. A two-step purification to homogeneity of the secreted material involved immunoaffinity followed by heparin-agarose chromatography. Two forms were identified; a fully processed dimer (70%) and a partially processed monomer (30%). Limited N-terminal amino acid sequencing of factor rXai detected the predicted residues and gamma-carboxyglutamic acid content was 90% of human plasma control. Although devoid of measurable proteolytic activity, factor rXai competitively inhibited plasma factor Xa assembly into functional prothrombinase complexes (Ki = 3 x 10(-10) M). Factor rXai also inhibited plasma clotting in a dose-dependent manner. The possible use of recombinant catalytically inactive proteins as a general approach for pharmacological regulation of human diseases is discussed.

Role of p34cdc2-mediated phosphorylations in two-step activation of pp60c-src during mitosis

Phosphorylation of pp60c-src by p34cdc2 at three amino-proximal serine/threonine residues is temporally correlated with, but insufficient for, mitotic activation of c-Src kinase. The direct cause of activation during mitosis appears to be temporally correlated partial dephosphorylation of Tyr-527, a residue whose phosphorylation strongly suppresses pp60c-src activity. Site-directed mutagenesis of the serine/threonine phosphorylation sites blocks half the mitosis-specific decrease in Tyr-527 phosphorylation and half the increase in pp60c-src kinase activity. We conclude that p34cdc2 partially activates pp60c-src by a two-step process in which its serine/threonine phosphorylations either sensitize pp60c-src to a Tyr-527 phosphatase or desensitize it to a Tyr-527 kinase. Furthermore, additional events, independent of these p34cdc2-mediated phosphorylations, participate in mitotic activation of pp60c-src.

Design of constructs for the expression of biologically active recombinant human factors X and Xa. Kinetic analysis of the expressed proteins

Activation of vitamin K-dependent plasma proteases occurs by specific interaction with components of the blood coagulation cascade. In this report, we describe the direct expression and enzymatic characterization of the human coagulation zymogen factor X and its activated form, factor Xa, from transformed Chinese hamster ovary fibroblast cell lines. Expression was achieved using either a full-length factor X cDNA or a unique mutant factor Xa cDNA. The functional factor Xa precursor contained a novel tripeptide bridge in place of the native 52-amino acid activation peptide. This mutation allowed for intracellular processing and secretion of the activated form of factor X. Secreted recombinant factors X (rX) and Xa (rXa) were purified by sequential anion-exchange and immunoaffinity chromatography. The enzymatic activities of factors rX and rXa were compared with those of plasma factors X and Xa in three independent assay systems. In comparison to human plasma factor X, the amidolytic, prothrombinase complex, and plasma clotting activities of factor rX were 50, 85, and 43%, respectively. The corresponding comparative activities for factor rXa were 32, 64, and 48%, respectively. The ability to directly express mutant forms of biologically active human factor X will facilitate the structure/function analysis of this important blood coagulation protein and may lead to the development of novel coagulation inhibitors.

Plasma uptake of manganese as affected by oral loads of manganese, calcium, milk, phosphorus, copper, and zinc

Six adult subjects were administered a series of manganese (Mn) tolerance tests to investigate the influence of various minerals on Mn plasma uptake. Oral loads given to all six subjects included 40 mg manganese alone, or with 800 mg calcium (Ca) as either calcium carbonate (CaCO3) or 545 ml 2% milk. Four of the subjects also received loads of 800 mg phosphorus (P), 2 mg copper (Cu), and 50 mg zinc (Zn) with the 40 mg Mn. Baseline Mn tolerance tests for all subjects produced a rapid increase in plasma Mn, followed by return to baseline. The addition of Ca as either CaCO3 or 2% milk to the oral Mn essentially blocked the plasma uptake of Mn. No significant differences were found between the source of Ca in its inhibitory effect. Plasma Ca uptake was lower when Mn was simultaneously administered, but the results were not significantly different. Ionized levels of plasma Ca did not change significantly. The addition of Cu to the Mn load decreased the area under the curve for plasma Mn by about half, but it was not significantly different in the four subjects. In contrast, the addition of Zn to the Mn produced a significant increase in plasma Mn. Phosphorus has no influence on plasma uptake of Mn. These results indicate that the plasma uptake of Mn is greatly reduced by concomitant ingestion of Ca but may be increased by an oral load of Zn.

Isolation of cell membrane for epidermal growth factor receptor studies

The cell membrane isolation procedure we developed here can be scaled up from four to several hundred plates of cultured cells. Transmission electron microscopy, membrane marker enzyme analysis, binding study, EGF-dependent receptor autophosphorylation, and Western blots all demonstrate the biological activity of the purified cell membranes. The membrane purification procedure has been adapted by others in assessing EGF kinase activity and has been used for the purification of cell membranes from other types of cultured cells.

Hypoxia stimulates endothelial cell angiotensin-converting enzyme antigen synthesis

Previous studies from our laboratory indicate that exposure of the rat to chronic normobaric hypoxia reduces stores of active angiotensin-converting enzyme (ACE) in the lung. This study assesses directly the effects of hypoxia on ACE synthesis in cultured porcine pulmonary artery endothelial cells. Confluent cultures were exposed to hypoxia [2.5% O2 at 1 atmosphere (atm)] in a triple gas incubator; controls were cultured in normoxic conditions. After 24-, 48-, and 72-h exposure to hypoxic or normoxic conditions, followed by incubation with [35S]methionine for an additional 24 h under the same conditions, newly synthesized radiolabeled ACE was quantitated. Radiolabeled ACE was isolated by an immunobead procedure using either anti-ACE (porcine lung) immunoglobin G (IgG) or nonimmune IgG. A single radiolabeled peak (150 kDa) with the same electrophoretic mobility as purified porcine lung ACE was observed. There was a significant time-dependent increase in endothelial cell ACE antigen synthesis without a concomitant change in either cell number or total trichloroacetic (TCA)-precipitable protein in hypoxic cells compared with normoxic controls. In contrast, ACE activity, assessed by conversion of 125I-labeled angiotensin I to 125I-labeled angiotensin II was unchanged in cultures exposed to hypoxia (2.5% O2). This suggests that an inactive form of ACE is synthesized by cultured pulmonary artery endothelial cells under hypoxic conditions.

Isolation and interrelationships of the multiple molecular tissue-type and urokinase-type plasminogen activator forms produced by cultured human umbilical vein endothelial cells

Primary and early subcultures (1st- to 3rd passage) of human umbilical vein endothelial cells produce tissue-type plasminogen activator (t-PA) antigen, consisting only of a major Mr 110,000 t-PA form. Later subcultures (greater than 4th passage) produce increasing amounts of t-PA antigen, consisting of a major Mr 110,000 and a minor Mr 68,000 form as well as increasing amounts of urokinase-type plasminogen activator (u-PA) antigen, consisting of a minor Mr 95,000 and major Mr 54,000 form. All of the major plasminogen activator forms were purified to homogeneity from 72 h serum-free conditioned media (3 liters, 1-1.8 x 10(9) cells) by a combination of immunoaffinity and gel filtration chromatography. Typically, 4th to 6th passage cultures produced/secreted t-PA-type proteins consisting of an inactive Mr 110,000 (220 IU/mg) and active Mr 68,000 (76,500 IU/mg) form representing about 39 and 8%, respectively, of the total starting sodium dodecyl sulfate stable t-PA activity, and u-PA-type proteins consisting of an inactive Mr 95,000 (700 IU/mg) and active Mr 54,000 (81,000 IU/mg) form representing about 9 and 38%, respectively, of the total starting sodium dodecyl sulfate stable u-PA activity. The isolated Mr 68,000 t-PA and Mr 54,000 u-PA proteins, exist only as two-chain forms in the absence of aprotinin and as mixtures of single- and two-chain proteins in the presence of aprotinin. Treatment with nucleophilic agents completely dissociated the Mr 110,000 t-PA and Mr 95,000 u-PA proteins into their respective Mr 68,000 t-PA and Mr 54,000 u-PA activity forms and a common Mr 46,000 protein, confirming the enzyme-inhibitor complex nature of these inactive plasminogen activator forms.