Impact of procedural multimedia instructions for pH BRAVO testing on patient comprehension: a prospective randomized study.

The positive impact on patient comprehension and improved procedural outcomes when multimedia is utilized to convey instructions preprocedurally has been previously shown for gastrointestinal procedures such as colonoscopy. However, in gastroesophageal reflux testing (GERD), we continue to utilize verbal and written instructions to establish this diagnosis when we use BRAVO pH testing. This is arguably a more complex procedure involving stopping medications, placement of a device, and maintaining an accurate diary for the duration of the testing. We hypothesize that by utilizing multimedia to relay complex textual information, patients will have improved comprehension of periprocedural instructions thereby improving data entry and satisfaction of expectations during the procedure. Prospective randomized study of 120 patients undergoing endoscopic placement of the BRAVO pH monitoring capsule for evaluation of GERD receive either written preoperative instructions (control) or written plus video instructions (video group). A composite comprehension score was calculated using procedure-specific parameters of data entry over the 48-hour monitoring period. Patient satisfaction was evaluated on the basis of a five-point Likert scale. Extent of patient satisfaction was defined by the fulfillment of patient expectations. Exclusion criteria included patients who did not have access to the video or did not complete follow-up. Seventy-eight patients completed all follow-up evaluations. The video group (n = 44) had a significantly higher mean comprehension score when compared to the control group (n = 34) (9.6 ± 1.4 vs. 7.4 ± 2.0, P = 0.01). Overall satisfaction with instructions was significantly higher in the intervention group (91% vs. 47%, p 0.01). We detected no significant difference in comprehension or satisfaction scores in subgroup analyses of the video group comparing patients <65 and ≥65 years of age and by education level. Compared to standard written instructions, video instructions improved patient comprehension based on data evaluation, and satisfaction. Therefore, clinicians should consider incorporation of multimedia instructions to enhance patient periprocedural expectations and understanding of reflux pH testing using the BRAVO procedure.

Ammonia oxidizer populations vary with nitrogen cycling across a tropical montane mean annual temperature gradient.

Functional gene approaches have been used to better understand the roles of microbes in driving forest soil nitrogen (N) cycling rates and bioavailability. Ammonia oxidation is a rate limiting step in nitrification, and is a key area for understanding environmental constraints on N availability in forests. We studied how increasing temperature affects the role of ammonia oxidizing archaea (AOA) and bacteria (AOB) in soil N cycling and availability by using a highly constrained natural mean annual temperature (MAT) elevation gradient in a tropical montane wet forest. We found that net nitrate (NO3- ) bioavailability is positively related to MAT (r2  = 0.79, P = 0.0033), and AOA DNA abundance is positively related to both NO3- availability (r2  = 0.34, P = 0.0071) and MAT (r2  = 0.34, P < 0.001). In contrast, AOB DNA was only detected in some soils across the gradient. We identified three distinct phylotypes within the AOA which differed from one another in abundance and relative gene expression. In addition, one AOA phylotype increased in abundance with MAT, while others did not. We conclude that MAT is the primary driver of ecosystem N availability across this gradient, and AOA population size and structure appear to mediate the relationship between the nitrification and N bioavailability. These findings hold important implications for nutrient limitation in forests and feedbacks to primary production under changing climate.

The Relationship Between Soil Arthropods and the Overwinter Survival of Ixodes scapularis (Acari: Ixodidae) Under Manipulated Snow Cover.

We explored the relationship between the diversity and abundance of the soil arthropod predator community and the overwinter survival of engorged larval Ixodes scapularis Say under variable snow cover in a hardwood forest. We reduced the snow cover over 30 soil core field microcosms, simulating predicted changes in snow pack in the northeastern United States. An additional 29 microcosms were used as references with no snow pack manipulation. Each microcosm contained 15 engorged larval I. scapularis. We expected lower soil temperature without insulating snow cover to reduce tick survival. However, we observed that reduced snow cover had no effect, with 44.2 and 44.7% overwintering successfully in the reference and snow-removal plots, respectively. Increasing taxonomic family richness of arthropod predators and the total number of large (>1 mm) arthropod predators significantly reduced the overwinter survivorship of I. scapularis within the microcosms. Small (<1 mm) arthropod predator abundance had no effect. Our results suggest that forests with complex natural arthropod predator communities show reduced tick survival.

Recovery from disturbance requires resynchronization of ecosystem nutrient cycles.

Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near-total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake, litterfall, and net mineralization are nearly the same. Disturbance can disrupt this synchronization if there is a disproportionate loss of one nutrient relative to the other. We model the resynchronization of N and P cycles following harvest of a northern hardwood forest. In our simulations, nutrient loss in the harvest is small relative to postharvest losses. The low N:P ratio of harvest residue results in a preferential release of P and retention of N. The P release is in excess of plant requirements and P is lost from the active ecosystem cycle through secondary mineral formation and leaching early in succession. Because external P inputs are small, the resynchronization of the N and P cycles later in succession is achieved by a commensurate loss of N. Through succession, the ecosystem undergoes alternating periods of N limitation, then P limitation, and eventually co-limitation as the two cycles resynchronize. However, our simulations indicate that the overall rate and extent of recovery is limited by P unless a mechanism exists either to prevent the P loss early in succession (e.g., P sequestration not stoichiometrically constrained by N) or to increase the P supply to the ecosystem later in succession (e.g., biologically enhanced weathering). Our model provides a heuristic perspective from which to assess the resynchronization among tightly cycled nutrients and the effect of that resynchronization on recovery of ecosystems from disturbance.

Intercellular adhesion molecule-1 (ICAM-1) is upregulated in aggressive papillary thyroid carcinoma.

BACKGROUND: Intercellular adhesion molecule-1 (ICAM-1) is implicated in carcinogenesis. In this study we examined the expression of ICAM-1 in papillary thyroid cancer (PTC). We hypothesized that ICAM-1 correlates with indicators of tumor aggressiveness in PTC. METHODS: Thirty-five primary and metastatic PTCs, five follicular adenomas, five Hashimoto thyroiditis, five nodular hyperplasia, and eight normal thyroid tissue samples were analyzed for ICAM-1 gene expression using quantitative reverse-transcription polymerase chain reaction (RT-PCR). ICAM-1 gene expression was analyzed at protein level by immunohistochemistry (IHC) using a semiquantitative score. Gene expression and intensity levels were correlated with markers of tumor aggressiveness including BRAF V600E mutation, tumor size, extrathyroidal extension (ETE), angiolymphatic invasion, and lymph node metastasis. RESULTS: ICAM-1 gene expression was higher in PTC (p = 0.01) and lymph node metastases (p = 0.03) when compared with benign tumors and Hashimoto's. Furthermore, PTCs exhibiting BRAF V600E mutation (p = 0.01), ETE (p < 0.01), and lymph node metastasis (p = 0.02) were associated with higher ICAM-1 levels. Gene expression correlated with protein levels on IHC. Additionally, poorly differentiated thyroid carcinoma had a higher ICAM-1 intensity score compared with well-differentiated carcinoma (p = 0.03). CONCLUSIONS: ICAM-1 expression is upregulated in papillary thyroid carcinoma. Furthermore, ICAM-1 upregulation correlated with aggressive tumor features such as BRAF V600E mutation, ETE, and lymph node metastasis, suggesting that ICAM-1 plays a role in thyroid cancer progression.

Shock and tissue injury induced by recombinant human cachectin.

Cachectin (tumor necrosis factor), a protein produced in large quantities by endotoxin-activated macrophages, has been implicated as an important mediator of the lethal effect of endotoxin. Recombinant human cachectin was infused into rats in an effort to determine whether cachectin, by itself, can elicit the derangements of host physiology caused by administration of endotoxin. When administered in quantities similar to those produced endogenously in response to endotoxin, cachectin causes hypotension, metabolic acidosis, hemoconcentration, and death within minutes to hours, as a result of respiratory arrest. Hyperglycemia and hyperkalemia were also observed after infusion. At necropsy, diffuse pulmonary inflammation and hemorrhage were apparent on gross and histopathologic examination, along with ischemic and hemorrhagic lesions of the gastrointestinal tract, and acute renal tubular necrosis. Thus, it appears that a single protein mediator (cachectin) is capable of inducing many of the deleterious effects of endotoxin.

Nitrogen retention in urban lawns and forests.

Lawns are a dominant cover type in urban ecosystems, and there is concern about their impacts on water quality. However, recent watershed-level studies suggest that these pervious areas might be net sinks, rather than sources, for nitrogen (N) in the urban environment. A 15N pulse-labeling experiment was performed on lawn and forest plots in the Baltimore (Maryland, U.S.A.) metropolitan area to test the hypothesis that lawns are a net sink for atmospheric-N deposition and to compare and contrast mechanisms of N retention in these vegetation types. A pulse of 15N-NO3-, simulating a precipitation event, was followed through mineral soils, roots, Oi-layer/thatch, aboveground biomass, microbial biomass, inorganic N, and evolved N2 gas over a one-year period. The 15N label was undetectable in gaseous samples, but enrichment of other pools was high. Gross rates of production and consumption of NO3- and NH4+ were measured to assess differences in internal N cycling under lawns and forests. Rates of N retention were similar during the first five days of the experiment, with lawns showing higher N retention than forests after 10, 70, and 365 days. Lawns had larger pools of available NO3- and NH4+; however, gross rates of mineralization and nitrification were also higher, leading to no net differences in NO3- and NH4+ turnover times between the two systems. Levels of 15N remained steady in forest mineral soils from day 70 to 365 (at 23% of applied 15N), but continued to accumulate in lawn mineral soils over this same time period, increasing from 20% to 33% of applied 15N. The dominant sink for N in lawn plots changed over time. Immobilization in mineral soils dominated immediately (one day) after tracer application (42% of recovered 15N); plant biomass dominated the short term (10 days; 51%); thatch and mineral-soil pools together dominated the medium term (70 days; 28% and 36%, respectively); and the mineral-soil pool alone dominated long-term retention (one year; 70% of recovered 15N). These findings illustrate the mechanisms whereby urban and suburban lawns under low to moderate management intensities are an important sink for atmospheric-N deposition.

Metabolic effects of cachectin/tumor necrosis factor are modified by site of production. Cachectin/tumor necrosis factor-secreting tumor in skeletal muscle induces chronic cachexia, while implantation in brain induces predominantly acute anorexia.

We have developed a murine model of wasting by injecting intracerebrally cells which continuously secrete h-cachectin/TNF (CHO-TNF) to: (a) determine the effects of cachectin/TNF produced continuously in the central nervous system (CNS), and (b) compare the metabolic effects of cachectin/TNF-secreting tumor in the brain to the cachexia caused by CHO-TNF tumor in peripheral tissue (IM). Intracerebral CHO-TNF tumors produced increased serum h-cachectin/TNF levels with lethal hypophagia and weight loss (mean survival time of 11 d); these changes were not observed in association with nonsecretory control brain tumors. The metabolic consequences of intracerebral cachectin/TNF production were indistinguishable from acute, lethal starvation: whole-body lipid content was decreased significantly but protein was conserved. Although intramuscular cachectin/TNF-secreting tumors caused similar increases of serum h-cachectin/TNF levels, profound anorexia did not develop; wasting developed after a longer period of tumor burden (50 d) with classical signs of cachexia (i.e., anemia and depletion of both protein and lipid). These studies provide a reproducible animal model of site-specific cytokine production and suggest that, regardless of serum levels, cachectin/TNF produced locally in brain influences both the rate of development of wasting and its net metabolic effects.

Cyclooxygenase-2 expression is up-regulated in human pancreatic cancer.

A large body of evidence suggests that cyclooxygenase-2 (COX-2) is important in gastrointestinal cancer. The purpose of this study was to determine whether COX-2 was expressed in adenocarcinoma of the human pancreas. Quantitative reverse transcription-PCR, immunoblotting, and immunohistochemistry were used to assess the expression of COX-2 in pancreatic tissue. Levels of COX-2 mRNA were increased by >60-fold in pancreatic cancer compared to adjacent nontumorous tissue. COX-2 protein was present in 9 of 10 cases of adenocarcinoma of the pancreas but was undetectable in nontumorous pancreatic tissue. Immunohistochemical analysis showed that COX-2 was expressed in malignant epithelial cells. In cultured human pancreatic cancer cells, levels of COX-2 mRNA and protein were induced by treatment with tumor-promoting phorbol esters. Taken together, these results suggest that COX-2 may be a target for the prevention or treatment of pancreatic cancer.

Diagnosis of follicular thyroid lesions by proton magnetic resonance on fine needle biopsy.

Most thyroidectomies are currently performed for diagnostic purposes. It has been established that proton magnetic resonance spectroscopy (MRS) on excised thyroid tissue can distinguish normal thyroid from invasive carcinomas (P < 0.0001). The purpose of this study was to assess whether the same discrimination could be obtained preoperatively from fine needle biopsy (FNB). This has clinical importance because cytological examination of fine needle aspirates cannot distinguish between benign and malignant follicular thyroid lesions. Here we demonstrate a sensitivity of 95% for proton MRS to correctly identify clinically or histologically proven carcinoma. MRS measurements were made on FNB specimens (containing as few as 10(6) cells) from solitary thyroid nodules. MR assessment of FNB was inconsistent with that of the corresponding tissue in only 6.5% of cases. The discrimination between cancer and normal tissue was based on altered cellular chemistry measured as a one-dimensional spectral ratio of resonances from the amino acid lysine and lipid. Benign follicular lesions were separated into two groups: 67% with a spectral ratio similar to malignant thyroid tumors, and 33% with a spectral ratio comparable to that in normal thyroid tissue. Thus, in contrast with histopathology, MRS offers a method for assessment of FNB of follicular lesions with the potential to identify a biologically benign group, which could avoid thyroid surgery for purely diagnostic purposes.

p44/p42-MAP kinase expression in papillary thyroid carcinomas.

BACKGROUND: Recent studies suggest that mitogen-activated protein (MAP) kinase contributes to the growth and tumorigenesis of human epithelial cancers. Furthermore, blockade of this pathway may inhibit the growth of epithelial cancers. To determine whether MAP kinase is activated in human papillary thyroid carcinomas (PTCs), we analyzed the presence of native MAP kinase (MAPK) and activated phosphorylated MAP kinase (pMAPK) in papillary thyroid cancers and thyroid carcinoma cell lines. METHODS: Protein from paired specimens of 10 patients with PTC was analyzed by immunoblot for MAPK and pMAPK. In addition, MAPK protein expression and cell growth were analyzed in 3 thyroid tumor cell lines treated with a mitogen extracellular kinase inhibitor, U0126. RESULTS: All 10 PTCs had equal expression of MAPK in the tumors and adjacent normal tissue. Six of the 10 tumors demonstrated increased expression of the pMAPK in the tumor specimen compared to the adjacent normal tissue. Interestingly, 3 of 4 patients without differential expression had multifocal PTC. The pMAPK was expressed constitutively in 3 thyroid cancer cell lines. The MAPK inhibitor treatment decreased pMAPK expression and decreased serum-induced growth in all 3 cell lines. CONCLUSIONS: MAP kinase activation is common in PTCs and may offer a potential target for growth inhibition of PTCs.

Telomerase activity in benign and malignant thyroid diseases.

BACKGROUND: Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant cells and is inactive in most normal somatic cells, with the excitation of proliferative stem cells, male germ cells, and activated lymphocytes. The measurement of telomerase activity in clinically obtained tissue samples may provide useful information as both a diagnostic and prognostic marker. In this study, we sought to determine whether telomerase activity might prove helpful in the assessment of benign and malignant thyroid tumors. METHODS: A modified, semiquantitative polymerase chain reaction-based telomeric repeat amplification protocol assay was used for detection of telomerase activity in 59 samples obtained at thyroidectomy, including 15 thyroid cancers, 22 benign thyroid diseases, and 22 adjacent normal thyroid tissues. RESULTS: Four of 13 differentiated thyroid carcinomas (30%) and 2 of 2 medullary carcinomas (100%) expressed telomerase activity. Unexpectedly, we also detected activity in 3 of 22 (14%) adjacent normal thyroid tissues and 6 of 22 (28%) benign thyroid diseases. Pathologic review of the telomerase-positive benign specimens revealed that many contained extensive lymphoid infiltrates with germinal centers (six of nine, 67%), as did two of four telomerase-positive papillary carcinomas. CONCLUSIONS: In contradistinction to other epithelial carcinomas, telomerase does not appear to be frequently reactivated in differentiated thyroid carcinomas.

Telomerase activity in the differentiation of benign and malignant adrenal tumors.

BACKGROUND: Telomerase is an RNA-dependent DNA polymerase that extends the ends of chromosomes by synthesizing the 6 oligonucleotide repeat TTAGGG and thus serves as a marker for cellular immortality. Although absent in most adult somatic tissues, telomerase activity is present in stem cells and is reactivated in nearly all primary human malignancies. In this study we sought to determine whether tumors of the adrenal glands contain telomerase activity and whether telomerase activity can be used to differentiate benign and malignant tumors of the adrenal glands. METHODS: Tissue was obtained from 23 specimens at adrenalectomy. Adjacent normal adrenal tissue was obtained for control. All specimens were rapidly frozen and stored at -80 degrees C until assay. Telomerase activity was determined by the telomeric repeat amplification protocol (TRAP). RESULTS: Telomerase activity was present in 5 of 23 (22%) of the adrenal tumors. All 3 malignant tumors were strongly TRAP positive. There was a single cortical adenoma that had very weak telomerase activity. The single TRAP-positive tumor of the adrenal medulla was a ganglioneuroma. CONCLUSIONS: Benign adrenal tumors infrequently contain telomerase activity, whereas telomerase reactivation appears to be common in malignant tumors of the adrenal glands. These data suggest that determination of telomerase activity may offer a novel way to facilitate the differentiation of benign and malignant adrenal tumors.

Additive effects of thermal injury and infection on the small bowel.

Thermal injury is associated with functional alterations of multiple organ systems, including the gastrointestinal tract. To study the effects of ongoing infection after thermal injury on bowel mass, composition, and blood flow, male Wistar rats were randomized to receive either 30% scald burn, 30% scald burn with Pseudomonas aeruginosa wound inoculation, sham burn, or sham burn with pair feeding to burned and infected animals. On days 3 and 7 after injury, intestinal blood flow was measured with 51Cr-labeled microspheres, and intestinal mass and composition were analyzed. Burned and infected animals demonstrated a chronic loss of small bowel mass not seen in burned animals without infection by day 7 after injury. Compositional alterations of the small bowels of burned and infected animals included protein wasting similar to but occurring earlier than that seen with anorexia alone and significantly decreased deoxyribonucleic acid and ribonucleic acid content, whereas tissue water content remained unchanged. These chronic intestinal alterations in the burned and infected group could not be explained by ongoing ischemia because intestinal blood flow in these animals was not significantly altered at either time point, implying mediation by other pathophysiologic mechanisms.

Pathophysiologic glucocorticoid levels and survival of translocating bacteria.

Burn wound sepsis in rats results in sustained corticosterone elevations and the prolonged presence of translocated bacteria in the mesenteric lymph nodes (MLNs). To determine if survival of bacteria in the MLNs may be influenced by pathophysiologic corticosterone levels, MLNs were quantitatively analyzed from rats randomized to the following groups: burn wound sepsis (BI); BI with adrenocortical response attenuated by cyclosporine (cyclosporine/BI); or cyclosporine/BI with corticosterone replacement (cyclosporine/BI + P). Although rates of bacterial translocation were similar, corticosterone levels were significantly different among the three groups and correlated with the number of lymphocytes and the number of enteric bacteria present per gram of MLN. Thus, pathophysiologic elevations of corticosterone levels during sepsis may exert an effect that allows survival of translocated bacteria in the MLNs of rats, perhaps due to glucocorticoid-associated alterations in regional immunity.

Surgical complications of nonsteroidal antiinflammatory drug-induced small bowel ulceration.

BACKGROUND: The association between nonsteroidal antiinflammatory drug (NSAID) intake and gastroduodenal peptic ulceration is well recognized. Recent experimental data implicate NSAIDs in the development of a similar spectrum of pathologic lesions of the small bowel. However, clinically significant NSAID-induced small bowel ulcerations have been reported infrequently. This study sought to examine small bowel complications of NSAID use requiring surgical intervention. STUDY DESIGN: A retrospective study of all patients (n = 283) who underwent small bowel resection on the general surgery services at the University of Texas Southwestern Medical Center during a 3-year period from 1991 to 1994 was conducted. Patients who had a history of chronic NSAID use, no other predisposing risk factors for gastrointestinal bleeding, and pathologically confirmed small bowel ulcerations complicated by hemorrhage, perforation, or obstruction were included in this study. RESULTS: Eleven patients with 12 surgical complications of NSAID-induced small bowel ulcerations were identified. These 11 patients all underwent emergent laparotomies with small bowel resection (one patient had two separate operations, 8 months apart). Small bowel ulcerations were noted to occur in the jejunum (4) and the ileum (8) and were multiple in half of the cases. Complications included bleeding (50%), perforation (33%), and obstruction (17%). CONCLUSIONS: This report is the first examining a series of surgical complications of NSAID-associated small bowel ulcerations. Our data suggest that small bowel complications of NSAID use requiring surgical intervention may occur more frequently than is currently recognized and, like peptic ulcer disease attributed to NSAIDs, result in significant morbidity and mortality.

Characterisitcs of patients having thyroid surgery under regional anesthesia.

BACKGROUND: Recently local/regional anesthesia has been reintroduced as an alternative to general anesthesia for thyroidectomy. This study was undertaken to analyze characteristics and outcomes of patients who had thyroid surgery performed under regional anesthesia compared with those who had thyroidectomy under general anesthesia. STUDY DESIGN: One hundred seventy-five consecutive patients who underwent thyroid surgery under regional or general anesthesia during a 3-year period were analyzed. Fifty-eight operations were performed under regional anesthesia and 116 under general anesthesia. Patient characteristics analyzed included age, gender, obesity, anesthesia class, and tumor pathology. Postoperative complications, including nausea or vomiting, were compared. Additionally, operative times and length of stay in each group were compared. RESULTS: Patient characteristics including age, gender, tumor pathology, and anesthesia class were similar in both groups. But only 2% of patients treated under regional anesthesia were obese compared with 23% under general anesthesia. Although not significant, there was a trend toward decreased incidence of nausea and vomiting in the regional group. Other complications for the regional and general anesthesia groups were equal at 3%. Two patients required conversion to general anesthesia. Complications in the general anesthesia group included one episode of transient symptomatic hypocalcemia, two patients with transient vocal cord paralysis, and one episode of hematoma. Finally, there was a statistically significant increase in total operating room time and length of stay for the general anesthesia group. CONCLUSIONS: Regional anesthesia is a safe alternative to general anesthesia for patients undergoing thyroid surgery. Patients who cannot communicate verbally with the surgical team or who are obese may not be ideal candidates for regional anesthesia. The use of regional anesthesia results in a decreased length of stay and similar operative and operating room times.

Bacterial overgrowth and intestinal atrophy in the etiology of gut barrier failure in the rat.

Bacterial translocation occurs in animal models of shock, trauma, sepsis, and parenteral or elemental enteral alimentation. Bowel atrophy and cecal bacterial overgrowth have both been implicated in the pathophysiology of bacterial translocation in many of these models. To further define the etiology of bacterial translocation resulting from dietary manipulations, rats were fed a elemental/defined-formula diet (DFD) for 2 weeks ad libitum and then randomized to either intestinal decontamination with a nonabsorbable antibiotic (neomycin) or no antibiotic treatment. Neomycin treatment significantly (p less than 0.01) reduced the incidence of bacterial translocation after DFD, in association with a significant reduction in the number of cecal gram-negative bacteria. Neither loss of bowel mass after DFD nor bowel composition was affected by oral neomycin. Bacterial translocation after DFD would thus appear to be the result of cecal bacterial overgrowth rather than a loss of a physical intestinal barrier due to atrophy.

Soil and xylem water potential and soil water content in contrasting Pinus contorta ecosystems, Southeastern Wyoming, USA.

The relationships between volumetric soil water content (ϕ), in situ soil water potential (Ίsoil) and predawn xylem pressure potential (Ίpredawn) were quantified in four contrasting lodgepole pine ecosystems in Wyoming, USA. On three of the sites, changes in Ίsoil correlated closely with Ίpredawn, but on a porous soil derived from coarse granitic parent material, Ίpredawn declines occurred much sooner than corresponding declines in Ίsoil, possibly because of local depletion of rhizosphere moisture and low molecular diffusivity of water in that soil. Exptrapolation of laboratory-derived characteristic curves for soil moisture to field conditions yielded different relationships between ϕ and Ίsoil than curves derived from in situ measurements, probably because of disruption of soil structure and porosity during sample collection and handling in laboratory studies. Although a close correlation between ϕ and Ίpredawn was observed, future efforts at modelling the soil-plant-atmosphere continuum should be directed towards a more detailed understanding of the complex relationships between Ίsoil at varying depths and plant water stress.

Immunonutrition: the role of arginine.

Clearly, arginine has great potential as an immunomodulator and may prove useful in catabolic conditions such as severe sepsis and postoperative stress. there is a body of evidence suggesting that supplemental arginine upregulates immune function and reduces the incidence of postoperative infection. More modest improvements in nitrogen balance have been observed. Tumor response to arginine appears to depend on the immunogenicity of the particular tumor and on the requirement of arginine by the tumor as a growth substrate. Of note, ornithine shares the thymotrophic, immunostimulatory and secretagogue effects of arginine. It is, therefore, likely that these compounds share the same cellular mechanism of action or that arginine acts via increasing the concentration of available ornithine. The role of arginine in the injured patient and in the tumor-bearing host demands additional study based on the promising experimental evidence regarding the supplemental use of arginine.