Root-growth behavior of the Arabidopsis mutant rgr1. Roles of gravitropism and circumnutation in the waving/coiling phenomenon

In this study we investigated the kinetics of the gravitropic response of the Arabidopsis mutant rgr1 (reduced root gravitropism). Although the rate of curvature in rgr1, which is allelic to axr4, was smaller than in the wild type (ecotype Wassilewskija), curvature was initiated in the same region of the root, the distal elongation zone. The time lag for the response was unaffected in the mutant; however, the gravitropic response of rgr1 contained a feature not found in the wild type: when roots growing along the surface of an agar plate were gravistimulated, there was often an upward curvature that initiated in the central elongation zone. Because this response was dependent on the tactile environment of the root, it most likely resulted from the superposition of the waving/coiling phenomenon onto the gravitropic response. We found that the frequency of the waving pattern and circumnutation, a cyclic endogenous pattern of root growth, was the same in rgr1 and in the wild type, so the waving/coiling phenomenon is likely governed by circumnutation patterns. The amplitudes of these oscillations may then be selectively amplified by tactile stimulation to provide a directional preference to the slanting.

Analysis of changes in relative elemental growth rate patterns in the elongation zone of Arabidopsis roots upon gravistimulation

Although Arabidopsis is an important system for studying root physiology, the localized growth patterns of its roots have not been well defined, particularly during tropic responses. In order to characterize growth rate profiles along the apex of primary roots of Arabidopsis thaliana (L.) Heynh (ecotype Columbia) we applied small charcoal particles to the root surface and analyzed their displacement during growth using an automated video digitizer system with custom software for tracking the markers. When growing vertically, the maximum elongation rate occurred 481 +/- 50 microns back from the extreme tip of the root (tip of root cap), and the elongation zone extended back to 912 +/- 137 microns. The distal elongation zone (DEZ) has previously been described as the apical region of the elongation zone in which the relative elemental growth rate (REGR) is < or = 30% of the peak rate in the central elongation zone. By this definition, our data indicate that the basal limit of the DEZ was located 248 +/- 30 microns from the root tip. However, after gravistimulation, the growth patterns of the root changed. Within the first hour of graviresponse, the basal limit of the DEZ and the position of peak REGR shifted apically on the upper flank of the root. This was due to a combination of increased growth in the DEZ and growth inhibition in the central elongation zone. On the lower flank, the basal limit of the DEZ shifted basipetally as the REGR decreased. These factors set up the gradient of growth rate across the root, which drives curvature.

Automated, eight-cage indirect calorimetry in rats

We have constructed an automated, eight-cage indirect calorimeter (AIC) for the measurement of energy expenditure in rats. We compared the measurements of resting energy expenditure (REE) in rats during a 30-h fast obtained with the AIC with those obtained with a manual indirect calorimetry (MIC) system. There was both a high degree of correlation between the two techniques during the initial 18 h of the fast (r = 0.90, P < 0.05) and strong intertechnique agreement. REE (AIC) decreased during the final 12 h of the 30-h fast (79.6 +/- 2.7-72.0 +/- 4.4 kcal.kg-0.75.d-1 [mean +/- SD, P < 0.01]). REE (MIC) did not show a significant decrease during this part of the fast (79.7 +/- 2.6 - 75.2 +/- 4.7 kcal.kg-0.75.d-1 [P = NS]). During the final 12 h of the fast agreement between the two systems gradually dissipated and correlation was poor (r = 0.375, P < 0.05). The frequency of animal handling necessitated by MIC may have resulted in a stress-induced increase in metabolic work that would mask the animals' adaptive response to starvation. This investigation demonstrates the advantages of the AIC and calls into question the accuracy of manual methods under long-term starvation conditions.

Resting energy expenditure of patients with gynecologic malignancies

OBJECTIVE

To evaluate resting energy expenditure compared to predicted energy expenditure in patients with cervical or ovarian carcinoma who require specialized nutritional support.

DESIGN

Women with biopsy-proven cervical or ovarian carcinoma referred to the Nutrition Support Service were studied. Resting energy expenditure was measured by indirect calorimetry and compared to predicted energy expenditure (PEE) as determined by the Harris-Benedict equation for females.

RESULTS

Sixty one patients were studied. Patients with ovarian cancer (n = 31) had a significantly higher measured resting energy expenditure (% PEE) than patients with cervical cancer (109 +/- 18% vs. 98 +/- 16%, p < 0.02, respectively). This difference in measured resting energy expenditure between groups could not be explained by differences in the extent of disease, nutritional status, body temperature, or nutrient intake between groups. A greater proportion of patients with ovarian cancer were hypermetabolic (> 110% of predicted) in comparison to patients with cervical cancer (55% vs. 13%, p < 0.01, respectively). Measured resting energy expenditure varied between 53% and 157% of predicted for the entire population.

CONCLUSION

Ovarian cancer patients are more hypermetabolic than cervical cancer patients. The Harris-Benedict equation for females is a unreliable estimate of caloric expenditure in patients with cervical or ovarian cancer receiving specialized nutritional support.

Long-term enteral access in aspiration-prone patients

Aspiration pneumonia is a serious complication of enteral feeding. Many critically ill patients are particularly at risk for aspiration. Few studies have rigorously compared various access devices. Risk factors for aspiration and studies examining aspiration associated with enteral feeding devices are reviewed. We recommend a surgical jejunostomy for all patients at high risk for aspiration who require more than 3 weeks of enteral nutrition support.

The button jejunostomy for long-term jejunal feeding: results of a prospective randomized trial

Low profile, self-retaining feeding conduits ("buttons") inserted percutaneously through a mature gastrostomy stoma are ideal for prepyloric feeding. We tested the efficacy of a surgically inserted button (Button, C.R. Bard, Inc) in the jejunum for long-term postpyloric feeding. Forty-two aspiration risk patients were prospectively randomized to receive a standard No. 14 French red rubber catheter (n = 21, mean age 68 +/- 17 years) or the button (n = 21, mean age 68 +/- 18 years). Common indications for jejunal feeding were aphagia due to obtundation (41%) and esophageal dysmotility (41%). All feeding devices were inserted 20 cm distal to the ligament of Treitz via a serosal tunnel (catheter) or double pursestring (button) technique. No patient required reoperation, and cardiopulmonary failure was the most frequent cause of death, occurring in 11 patients (26%). Goal feedings were obtained in 91% of the catheter patients and 100% of the button patients by postoperative day 4.7 +/- 1.9 and 4.2 +/- 2.2, respectively. At a follow-up of 43 +/- 13 days, 12 (92.3%) of 13 catheter patients and 9 (81.8%) of 11 button patients were receiving goal feedings. Three patients in the catheter group and four patients in the button group had resumed an oral diet. Device-related complications (dislodgment, occlusion, peritubular leak, or bowel obstruction) and total number of patients with complications were significantly lower in the button group (one [5%] vs eight [38%] for device-related complications and one [5%] vs six [29%] for incidence of complications for the button and catheter groups, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Home parenteral nutrition after near total enterectomy

Six patients with extreme short bowel syndrome (4.2 +/- 4.9 cm of residual small bowel) were provided home parenteral nutrition (HPN) for 14,397 days. The average age at onset of HPN was 38 years (18-64 years). Patients maintained body weight at 97% of ideal (86-112%) with mean serum albumin of 3.7 +/- 0.6 g/dL (normal 3.5-5.8 g/dL), serum transferrin of 341 +/- 104 mg/dL (normal 200-400 mg/dL), and mean serum pre-albumin of 27.5 +/- 12.6 mg/dL (normal 16.6-43 mg/dL). Hospital admission for HPN-related complications was required 10.3 times/patient for a total of 864 hospital days and was catheter related in 71% of episodes. Catheter sepsis occurred once per 436 catheter days and required catheter removal in only 33% of instances. Five patients were able to resume an oral diet, five had returned to work or school, and three were married with family. HPN allowed return to a quality productive life with acceptable morbidity following catastrophic massive bowel resection.

Total quality management: one way to get started

Continuous QI requires our hospitals to undergo a fundamental change in values, beliefs, and ways to manage. Process improvement changes must start with senior managers, who create the environment for continuous improvement and then enable department managers and employees to improve their processes. Persistent poor quality does not respect organizational boundaries, and HQIP provides an opportunity to manage all the resources necessary to make improvements. As pharmacy managers, we must identify processes under our control that can be continuously improved based on documented customer judgments. We must stop asking employees to work harder in a flawed system and empower them to improve those processes within their control. It may be easy to become frustrated if it seems to take a long time to implement TQM. Remember, transforming our departments and hospitals will not happen overnight. We are embarking on a new style of leadership and management, one that will help pharmacies implement our pharmaceutical care vision.

Laparoscopic-guided jejunostomy

The proximal jejunum is the preferred site for long-term enteral access in the patient at risk for aspiration. Herein we describe a laparoscopic technique for the creation of a feeding tube jejunostomy. This minimally invasive approach is an alternative for patients requiring chronic postpyloric enteral feeding.

Contribution of skeletal muscle atrophy to exercise intolerance and altered muscle metabolism in heart failure

BACKGROUND

The purpose of this study was to investigate the prevalence of skeletal muscle atrophy and its relation to exercise intolerance and abnormal muscle metabolism in patients with heart failure (HF).

METHODS AND RESULTS

Peak VO2, percent ideal body weight (% IBW), 24-hour urine creatinine (Cr), and anthropometrics were measured in 62 ambulatory patients with HF. 31P magnetic resonance spectroscopy (MRS) and imaging (MRI) of the calf were performed in 15 patients with HF and 10 control subjects. Inorganic phosphorus (Pi), phosphocreatine (PCr), and intracellular pH were measured at rest and during exercise. Calf muscle volume was determined from the sum of the integrated area of muscle in 1-cm-thick contiguous axial images from the patella to the calcaneus. A reduced skeletal muscle mass was noted in 68% of patients, as evidenced by a decrease in Cr-to-height ratio of less than 7.4 mg/cm and/or upper arm circumference of less than 5% of normal. Calf muscle volume (MRI) was also reduced in the patients with HF (controls, 675 +/- 84 cm3/m2; HF, 567 +/- 112 cm3/m2; p less than 0.05). Fat stores were largely preserved with triceps skinfold of less than 5% of normal and/or IBW of less than 80% in only 8% of patients. Modest linear correlations were observed between peak VO2 and both calf muscle volume per meter squared (r = 0.48) and midarm muscle area (r = 0.36) (both p less than 0.05). 31P metabolic abnormalities during exercise were observed in the patients with HF, which is consistent with intrinsic oxidative abnormalities. The metabolic changes were weakly correlated with muscle volume (r = -0.42, p less than 0.05).

CONCLUSIONS

These findings indicate that patients with chronic HF frequently develop significant skeletal muscle atrophy and metabolic abnormalities. Atrophy contributes modestly to both the reduced exercise capacity and altered muscle metabolism.

Surgical jejunostomy in aspiration risk patients

One hundred patients underwent laparotomy for independent jejunal feeding tube placement. Neurologic disease was present in 50%, and obtundation (28) and oropharyngeal dysmotility (25) were the most common indications for enteral feeding. The post-pyloric route was chosen because of aspiration risk in almost all (94%) patients. Postoperative (30-day) mortality rate was 21%, because of cardiopulmonary failure in most (18). One death resulted directly from aspiration of tube feeds. Two surgical complications required reoperation: one wound dehiscence and one small bowel obstruction. Four wound infections occurred. Two patients underwent reoperation after tube removal, and four tubes required fluoroscopically guided reinsertion for peritubular drainage (2), removal (1), and occlusion (1). Aspiration pneumonia was present in 18 patients preoperatively and in eight postoperatively. None of the patients with feeding-related preoperative aspiration pneumonia (13) had a recurrence while fed by jejunostomy. Three patients developed postoperative aspiration pneumonia before initiation of jejunostomy feedings. Jejunostomy may be performed with low morbidity rate and substantial reduction of feeding-related aspiration pneumonia, and is the feeding route of choice in aspiration risk patients.

Early-onset repeated dieting reduces food intake and body weight but not adiposity in dietary-obese female rats

As dieting behavior and attempts at weight loss are becoming increasingly common in adolescent girls, we wished to determine whether early-onset repeated dieting influenced the development of obesity and its metabolic correlates. Female rats were fed a high-fat diet and subjected to six cycles of dieting and regain, beginning in the peripubertal period. Although dieted rats weighted less than nondieted high-fat fed controls at the completion of the sixth cycle, body composition analysis revealed that the two groups were equally obese. Cumulative caloric intake was less in dieted rats, suggesting that the pattern of consumption promoted by dieting helped to establish the obesity. Resting metabolic rate did not differ between the two groups. These data suggest that although early-onset repeated dieting may result in reduced body weight, the eventual level of adiposity may be unknowingly elevated, potentially leading to long-term health risks.

Nutritional support in renal failure

Adequate protein intake is necessary in renal failure to reduce morbidity. The desire to avoid dialysis should not be a justification to starve patients, particularly because fed patients have better survival rates in acute renal failure. The treatment techniques for renal failure may be used secondarily as a delivery route for nutrients.

Nutritional assessment and indications for nutritional support

The goal of nutritional assessment is to identify prospectively all those patients who would develop a nutrition-related complication. In practical terms, there is no single test capable of achieving this goal. At present, the best method of nutritional assessment is an organized step-by-step multifactorial approach. This involves assessment of the primary illness, the patient history, and the prognosis. A nutritional status examination is done, and the current intake is compared with the nutritional goals. A decision is then made whether to force feed. If forced feeding is initiated, the effectiveness of the therapy must be monitored frequently until the patient recovers and is able to be sustained by volitional oral intake.

Resting energy expenditure in patients with pancreatitis

OBJECTIVE

To assess the resting energy expenditure of hospitalized patients with pancreatitis.

DESIGN

Prospective, case-referent study.

SETTING

Nutrition support service in a university tertiary care hospital.

PATIENTS

Patients referred to the Nutrition Support Service with the diagnosis of pancreatitis. Excluded from study entry included those with cancer, obesity (greater than 150% ideal body weight), those measured within 3 postoperative days, or patients requiring ventilator support with an FIO2 of greater than 0.5. Forty-eight patients with either acute pancreatitis (n = 13), chronic pancreatitis (n = 24), acute pancreatitis with sepsis (n = 7), or chronic pancreatitis with sepsis (n = 7) were studied. The two septic groups were combined into a single pancreatitis-with-sepsis group, since no significant differences among measured variables were observed between individual septic groups.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Resting energy expenditure was measured by indirect calorimetry and compared with the predicted energy expenditure, as determined by the Harris-Benedict equations. Resting energy expenditure (percent of predicted energy expenditure) was significantly (p less than .02) greater for patients with pancreatitis complicated by sepsis (120 +/- 11%) compared with the nonseptic chronic pancreatitis group (105 +/- 14%). Resting energy expenditure for the nonseptic acute pancreatitis patients (112 +/- 17%) was not significantly different from the other groups. The septic pancreatitis group had the largest percentage (82%) of hypermetabolic (resting energy expenditure greater than 110% of predicted energy expenditure) patients, whereas 61% and 33% of the acute and chronic pancreatitis groups were hypermetabolic, respectively (p less than .02).

CONCLUSIONS

Resting energy expenditure is variable in patients with pancreatitis (77% to 139% of predicted energy expenditure). The Harris-Benedict equations are an unreliable estimate of caloric expenditure. Septic complications are associated with hypermetabolism and may be the most important factor influencing resting energy expenditure in pancreatitis patients.

Long-term effects of dieting on resting metabolic rate in obese outpatients

There is growing concern that dieting may adversely affect the metabolic rate and exacerbate efforts to control weight. In this study we measured the resting metabolic rate nine times over 48 weeks in 18 obese women (108.0 +/- 3.1 kg) who were randomly assigned to one of two dietary conditions. Nine patients consumed approximately 5021 kJ/d (1200 kcal/d) throughout the 48 weeks, while the other nine consumed a 1757-kJ/d (420-kcal/d) diet for 16 of the first 17 weeks and a conventional reducing diet for the remainder of treatment. All patients increased their physical activity, primarily by walking. During the first 5 weeks, the fall in metabolic rate was more than double the relative reduction in weight. By contrast, at week 48, the metabolic rate of patients in the two conditions was reduced by 9.4% +/- 4.0% and 8.3% +/- 2.2%, respectively, while weight was reduced by 16.6% +/- 2.7% and 19.5% +/- 2.7%, respectively. Thus, neither dietary regimen, combined with modest physical activity, was associated with long-term reductions in resting metabolic rate that exceeded decreases anticipated with the achievement of a lower body weight.

Components of energy expenditure in tumor-bearing animals

Single snapshot measurements of resting energy expenditure (REE) suggest that hypermetabolism contributes to cancer cachexia, but tumor impact on total 24-hr energy expenditure (TEE) is unknown. Automated multicage indirect calorimetry was employed to measure daily energy expenditure in adult Buffalo rats (n = 16) randomized to tumor inoculation or controls. Measurements included baseline REE, activity EE (AEE), thermic response to food (TEF), and TEE. Rats (n = 16) were randomized. Metabolic measurements, tumor size, and body weight were recorded weekly. Animals were sacrificed at Week 5 for analysis of host and tumor composition. Significant depletion of total lean body mass occurred in TB rats (greater than 15% wt loss, ANOVA P less than 0.001) which inversely correlated with tumor growth (r = -0.81, P less than 0.001). REE, TEF, AEE, and TEE did not change in controls (ANOVA P = n.s.). In TB rats, a 19.5% increase in REE occurred (119.4 +/- 3.3 to 138.7 +/- 1.8 kcal/kg LBM/day, P less than 0.01). TEE remained unchanged (157.3 +/- 5.6 vs 152.9 +/- 3.6 kcal/kg LBM/day, P = n.s.) due to a 66% decrease in AEE (32.9 +/- 3.1 to 10.5 +/- 1.7 kcal/kg LBM/day, P = 0.01). TEF did not change (4.7 +/- 0.8 vs 5.0 +/- 0.3 kcal/kg LBM/day, P = n.s.). Both TB and controls demonstrated a decreased REE in response to a 24-hr fast (7.9% vs 4.8%, P = n.s.). Respiratory quotient decreased in both groups when comparing fed to fasted values: TB (0.86 to 0.76) and controls (0.86 to 0.71), but the decline was greater in controls (P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of thrombolytic therapy for occlusion of long-term catheters

Nineteen ambulatory outpatients requiring a tunneled central venous access device with catheter occlusion were studied. Mean catheter life was 7.9 +/- 8.2 months (range, from 1-36 months) at the time of the occlusion. Urokinase (5000 units/ml) was injected in sufficient amount to fill the internal volume of the catheter and allowed to stay for 5 to 10 min before attempting to aspirate. Repeated aspiration attempts were performed every 5 to 10 min for a maximum of 30 to 60 min or patency. In the event catheter patency was not restored, the thrombolytic solution was aspirated from the catheter and a maximum of two additional trials were instituted. Results included clearance of four out of 15 withdrawal occlusions (27%) and two out of four resistance to infusion occlusions (50%). Overall, successful catheter clearance occurred in six out of 19 occlusions (32%). The efficacy rate of thrombolytic therapy for successfully clearing occluded catheters at our institution using conventional low-dose thrombolytic therapy is markedly lower than previously reported rates of 57 to 100%. The reasons for this discrepancy may reflect differences in dosage of thrombolytic agent, method of administration, frequency of monitoring of catheter patency, and catheter life.

Effects of nonglucose substrates (xylitol, medium-chain triglycerides, long-chain triglycerides) and carnitine on nitrogen metabolism in stressed rats

To evaluate the efficacy of nonglucose energy substrates in promoting nitrogen retention and survival in stressed states, two series of studies were done. In study 1, 50 rats underwent cecal ligation/perforation and subsequent infusion for 24 hr with one of four isocaloric (220 kcal/kg/day), isonitrogenous (1.4 g/N/kg/day), isovolemic regimens which differed in caloric source: Glucose (GLU) + long-chain triglycerides (LCT) (50%:50%), GLU + LCT + medium-chain triglycerides (MCT) (50%:32%:18%), GLU + LCT/Carnitine (10 mg/dl) or GLU + LCT + Xylitol (XYL) (33%:33%:33%). The nitrogen-sparing effect of GLU + LCT was not enhanced by the addition of carnitine to facilitate LCT mitochondrial uptake or by MCT to bypass carnitine-dependent transport. In contrast, relative to GLU + LCT GLU + LCT + XYL decreased urinary 3-methylhistidine (3MH) excretion (p less than 0.01), and enhanced nitrogen retention (p less than 0.01 vs GLU + LCT). For study 2, 24 male rats were anesthetized, cannulated for TPN, and given a 25% burn. They were then randomized into three dietary groups. The diets were isocaloric (103 kcal/kg/day) and isonitrogenous (2.0 g N/kg/day) but differed in nonprotein calorie source: GLU + LCT (51%:49%), GLU + Glycerol (51%:49%) and XYL + LCT (51%:49%). As in the septic animals, N balance was best with the xylitol regimen (p less than 0.01). The polyol, xylitol, appears to have a significant nitrogen sparing effect in stressed animals.

Antibiotic therapy of catheter infections in patients receiving home parenteral nutrition

Fifty-eight episodes of catheter-related sepsis in 21 patients receiving home parenteral nutrition were retrospectively studied. Of 81 organisms isolated from the blood, 59% were Gram-positive cocci, 25% were Gram-negative bacilli, and 16% were yeast. Attempts to treat bacterial infections at home with antibiotic therapy while the catheter remained in place were made; fungal isolation resulted in immediate hospitalization and catheter removal. Gram-negative infections more often resulted in eventual hospitalization (92%) and catheter removal (50%) than Gram-positive infections (57% hospitalization and 23% catheter removal). Empiric therapy with 1 g of cefazolin intravenously every 12 hr was successful in only 33% of episodes caused by coagulase-negative staphylococci, whereas vancomycin was successful in 62%. Sensitivity testing was not a reliable guide for antibiotic choice for treatment of these infections. Cefazolin, 1 g, intravenously every 12 hr was successful in only 25% of Gram-negative episodes treated empirically with this regimen. We conclude that our home parenteral nutrition patients should be hospitalized for a few days upon presentation with a catheter infection for clinical evaluation and aggressive antibiotic therapy. Vancomycin is the preferred drug for treatment of catheter-related infections caused by coagulase-negative staphylococcus.

Ablation of abnormal energy expenditure by curative tumor resection

Resting energy expenditure is abnormal in most patients with cancer and may contribute to cancer cachexia. These metabolic abnormalities may be a direct measure of tumor metabolism, or represent alterations in the size or activity of the body cell mass, or both. To unravel this pathogenesis, we prospectively studied 68 preoperative patients with cancer about to undergo curative resection by measuring resting energy expenditure before and after tumor resection. The preoperative measured resting energy expenditure was compared with expected resting energy expenditure based on Harris-Benedict resting energy expenditure predictions: 10 patients were hypometabolic (less than 90% Harris-Benedict); 35 were normometabolic (90% to 110% Harris-Benedict); and 23 were hypermetabolic (greater than 110% Harris-Benedict). Using each patient as his or her own control, resting energy expenditure normalized or remained normal following curative resection. In contrast, after palliative resection, resting energy expenditure remained hypermetabolic or significantly increased toward hypermetabolism. Tumor induces an abnormal metabolic rate, since tumor removal results in prompt normalization of resting energy expenditure. The abnormal energy expenditure of patients with cancer cannot be solely attributed to abnormal host body composition.