Increase In Overall Length Research Articles

Upper Gastrointestinal Series in the Workup for Pediatric Gastrostomy Placement: Does it Delay Care?

IntroductionUpper gastrointestinal (UGI) series is often part of the workup prior to the placement of gastrostomy tubes in children. Prior studies have suggested UGI to be limited in utility and an extra financial burden. The goal of this study was to investigate the utility and cost of UGI studies. MethodsA retrospective, case control study of patients aged < 18 y receiving gastrostomy tubes at a free-standing children's hospital between 2012 and 2017. Total costs were obtained from the Pediatric Health Information System. ResultsSix hundred eighty five patients underwent gastrostomy placement during the study period. UGI was obtained in 90.8% of patients; 23.6% of studies were abnormal. The most common abnormal findings were reflux (13.8%) and abnormal anatomy (5.8%). The median time to obtain a UGI was 0.82 d (interquartile range 0.22-1.05). Obtaining a UGI was associated with delayed care in 104 patients (15.2%). If a delay was encountered, median time was 2.47 d (interquartile range 1.86-2.99). Ladd's procedures were performed in 12 patients (1.7%) found to have malrotation on UGI. None of the 63 patients who did not undergo UGI required a Ladd's procedure. Patients that had a UGI did not experience an increase in overall length of stay (14.3 versus 15.6 d, excluding intensive care unit patients), operative time (34 versus 39 min), or a change in rate of operative complications (11.5% versus 14.3%). In addition, UGI did not have a significant impact on total adjusted costs ($49,844 versus $83,438 without UGI, P = 0.12) but did slightly increase total adjusted costs per day ($2212 versus $1999 without UGI, P = 0.01). ConclusionsUGI prior to gastrostomy placement in children rarely identified abnormal findings that changed the operative plan, was associated with delayed care in 15% of patients, and was associated with slightly increased costs per day. Further analyses to identify subsets of children that may benefit from routine UGI are warranted.

Orbital Complications of Acute Sinusitis in Pediatric Patients: Management of Chandler III Patients.

BackgroundSurgery is often avoided in the setting of pediatric orbital complications from acute sinusitis unless necessitated by alarming ophthalmological signs. Criteria for surgical intervention are not well-defined.ObjectiveWe aim to review our experiences, management practices and patient outcomes over a ten-year period for Chandler III patients.MethodsA retrospective review was performed from January 1, 2007 through December 31, 2016 of patients treated for orbital symptoms secondary to acute sinusitis at a free-standing tertiary-care pediatric hospital.ResultsOf the 186 patients reviewed, 42 Chandler III patients were included. Average age was 82.6 months (SD 50.6) with a slight male predominance (M to F, 1.8 to 1). 27 patients (64.3%) underwent intervention including endoscopic sinus surgery (ESS) with or without orbitotomy. Late surgical intervention (>48hrs from admission) demonstrated significant increase in overall length of stay (LOS) when compared with early surgical intervention and/or medical management (median, 6.9 vs 3.6 vs 3.7 days; p < 0.01). Postoperative LOS was also higher in the late surgery group compared with patients who had surgery within 48 hours of admission, but this did not reach statistical significance [median, 3.8 vs 2.8 days, p= 0.12]. There was no significant difference in overall abscess volume between patients who underwent intervention and those who did not (1019 mm3 vs 805 mm3, p = 0.5), but abscess width ≥ 1.2 cm was associated with higher rates of intervention. An alarming extraocular exam was the most common factor associated with surgical intervention.ConclusionPediatric subperiosteal orbital abscess may prompt surgical intervention by ESS. An alarming ophthalmologic exam should prompt consideration of early intervention, which may lead to decreased overall and post-operative length of hospital stay.Level of Evidence4Meeting InformationAmerican Rhinologic Society, Fall National Meeting. Chicago, IL, USA. September 8–9, 2017.

Acute intracranial stenting with mechanical thrombectomy is safe and efficacious in patients diagnosed with underlying intracranial atherosclerotic disease.

To investigate whether significant differences exist in recanalization rates and primary outcomes between patients who undergo mechanical thrombectomy alone versus those who undergo mechanical thrombectomy with acute intracranial stenting. Through the utilization of a prospectively collected endovascular database at a comprehensive stroke center between 2012 and 2020, variables such as demographics, co-morbid conditions, symptomatic intracerebral hemorrhage, mortality rate at discharge, and good/poor outcomes in regard to modified thrombolysis in cerebral infarction score and modified Rankin Scale were examined. The outcomes between patients receiving acute intracranial stenting + mechanical thrombectomy and patients that underwent mechanical thrombectomy alone were compared. There were a total of 420 acute ischemic stroke patients who met criteria for the study (average age 70.6 ± 13.01 years; 46.9% were women). Analysis of 46 patients from the acute stenting + mechanical thrombectomy group (average age 70.34 ± 13.75 years; 37.0% were women), and 374 patients from the mechanical thrombectomy alone group (average age 70.64 ± 12.92 years; 48.1% were women). Four patients (8.7%) in the acute stenting + mechanical thrombectomy group experienced intracerebral hemorrhage versus 45 patients (12.0%) in the mechanical thrombectomy alone group (p = 0.506); no significant increases were noted in the median length of stay (7 vs 8 days; p = 0.208), rates of modified thrombolysis in cerebral infarction 2B-3 recanalization (p = 0.758), or good modified Rankin Scale scores (p = 0.806). Acute intracranial stenting in addition to mechanical thrombectomy was not associated with an increase in overall length of stay, intracerebral hemorrhage rates, or any change in discharge modified Rankin Scale. Further research is required to determine whether mechanical thrombectomy and acute intracranial stenting in acute ischemic stroke patients is unsafe.

Predictors of Exceeding Target Inpatient Rehabilitation Length of Stay After Hip Fracture.

The aim of the study was to identify factors associated with exceeding a target inpatient rehabilitation length of stay of 28 days or less for individuals with hip fracture. Retrospective cohort study of hip fracture patients admitted to an urban Canadian inpatient rehabilitation facility between January 1, 2013, and January 1, 2018. Patient characteristics previously shown to be associated with individual outcomes and/or length of stay after hip fracture were extracted from the institution's data warehouse. Regression models were used to examine factors associated with exceeding target length of stay as well as overall length of stay. Four hundred ninety-three subjects were included in the analysis. Three hundred forty-five (70%) met and 148 (30%) exceeded their target length of stay. Patients who exceeded their target were more likely to be elderly (odds ratio, 1.05; 95% confidence interval, 1.02-1.08), to live alone prefracture (odds ratio, 1.72; 95% confidence interval, 1.02-2.91), to have dementia (odds ratio, 2.79; 95% confidence interval, 1.12-6.97), and higher admission pain scores (severe pain odds ratio, 2.51; 95% confidence interval, 1.06-5.93). Higher admission motor Functional Independence Measure scores (odds ratio, 0.95; 95% confidence interval, 0.92-0.98) were protective. Advancing age, having dementia, living alone prefracture, and reporting moderate or severe pain at the time of admission not only increased the odds of an individual exceeding their target length of stay but also was associated with an overall increase in length of stay. Conversely, having a higher admission motor Functional Independence Measure score was protective.

Northwest Coast Halibut Hooks: an Evolving Tradition of Form, Function, and Fishing

The Northwest Coast (NWC) halibut hook is both an indigenous fishing technology, and an iconic object of rich cultural history. This study utilizes biological, statistical, ecological, and ethnographic data to examine the function(s) of NWC halibut hooks, and how and why dimensions are changing through time. Analyses of measurements from 143 specimens, dated from 1867 to 2015, suggest a statistically significant increase in overall length through time. These findings support the hypothesis that as the use of modern fishing technologies became more prevalent, and traditional NWC halibut hooks largely lost their original function (i.e., catching halibut), dimensions changed to favor decorative or symbolic content over utilitarian/functional requirements. Archival data, peer-reviewed literature, and ethnographic interviews with contemporary carvers and fishers support the assertion that average dimensions of early NWC halibut hooks targeted fish between 20 and 100 lbs., thus promoting sustainability of Pacific halibut breeding populations. Whether the hooks were designed intentionally to promote sustainability or this size of fish was targeted for other reasons remains an open question.

A retrospective analysis of catheter-based thrombolytic therapy for acute submassive and massive pulmonary embolism.

Catheter-based thrombolysis (CBT) is emerging as an option for acute pulmonary embolism (PE). Although prior studies have demonstrated improvement in right ventricular function, little data is available regarding clinical patient outcomes. Our institution adopted CBT as an option for patients with submassive and massive PE and we evaluated its effect on patient outcomes. Two hundred and twenty-one patients who presented to our institution with submassive and massive PE were analyzed over three years by time period; 102 prior to the use of CBT and 119 during the time CBT was performed. The primary outcome was in-hospital major adverse clinical events (a composite of death, recurrent embolism, major bleeding, or stroke). Secondary outcomes were overall and ICU length of stay and individual components of the composite outcome. Mean age was 56.3±16 years with high rates of central PE (57.9%), RV dysfunction (37%), and myocardial necrosis (26%). Mean RV/LV ratio was 1.2. Thirty-two patients were treated with CBT. The composite endpoint occurred more frequently in the CBT era vs the pre-CBT era (21.0% vs 14.7%, p=0.23). After multivariate adjustment, CBT treatment demonstrated no effect on major adverse clinical events (OR 0.84, CI 0.22-3.22, p=0.80). CBT era patients had an unadjusted 37% increase in ICU days and 54% increase in total length of stay (p<0.001). Within the CBT era, CBT treatment resulted in an adjusted 190% increase in overall length of stay (p<0.001). CBT did not demonstrate improvement in hospital outcomes, despite adjustments of PE severity, and was associated with a significant increase in overall and ICU length of stay.

Antibiotics conspicuously affect community profiles and richness, but not the density of bacterial cells associated with mucosa in the large and small intestines of mice

The influence of three antibiotics (bacitracin, enrofloxacin, and neomycin sulfate) on the mucosa-associated enteric microbiota and the intestines of mice was examined. Antibiotics caused conspicuous enlargement of ceca and an increase in overall length of the intestine. However, there were no pathologic changes associated with increased cecal size or length of the intestine. Conspicuous reductions in the richness of mucosa-associated bacteria and changes to community profiles within the small (duodenum, proximal jejunum, middle jejunum, distal jejunum, and ileum) and large (cecum, ascending colon, and descending colon) intestine occurred in mice administered antibiotics. Communities in antibiotic-treated mice were dominated by a limited number of Clostridium-like (i.e. clostridial cluster XIVa) and Bacteroides species. The richness of mucosa-associated communities within the small and large intestine increased during the 14-day recovery period. However, community profiles within the large intestine did not return to baseline (i.e. relative to the control). Although antibiotic administration greatly reduced bacterial richness, densities of mucosa-associated bacteria were not reduced correspondingly. These data showed that the antibiotics, bacitracin, enrofloxacin, and neomycin sulfate, administered for 21 days to mice did not sterilize the intestine, but did impart a tremendous and prolonged impact on mucosa-associated bacterial communities throughout the small and large intestine.

Material Characterization at High Strain by Adapted Tensile Tests

The strength of materials at high strain levels has been determined using the so-called Continuous-Bending-under-Tension (CBT) test. This is a modified tensile test where the specimen is subjected to repetitive bending at the same time. This test enables to create high levels of uniform strain. A wide variety of materials has been tested this way. The strength of the material after CBT testing has been measured in different ways: by secondary tensile tests, by interrupted CBT tests, and directly from the fracture in the CBT test. All methods yield similar results: the strength is largely unaffected by the cyclic pre-deformation and mainly depends on the overall increase in length. Only for multi-phase materials the strength shows a minor influence of CBT test conditions. The hardening follows the extrapolated hardening observed in a conventional tensile test, except for brass. This test method can potentially be used for measuring hardening curves at high strain levels.

STEREOLOGICAL STUDIES ON FETAL VASCULAR DEVELOPMENT IN HUMAN PLACENTAL VILLI

In human pregnancy, fetal well-being depends on the development of placental villi and the creation and maintenance of fetal microvessels within them. The aim of this study was to define stereological measures of the growth, capillarization and maturation of villi and of fetoplacental angiogenesis and capillary remodelling. Placentas were collected at 12-41 weeks of gestation and assigned to six age groups spanning equal age ranges. Tissue samples were randomised for position and orientation. Overall growth of peripheral (intermediate and terminal) villi and their capillaries was evaluated using total volumes, surface areas and lengths. Measures of villous capillarization comprised capillary volume, surface and length densities and capillary:villus surface and length ratios. Size and shape remodelling of villi and capillaries was assessed using mean cross-sectional areas, perimeters and shape coefficients (perimeter2/area). Group comparisons were drawn by analysis of variance. Villous and capillary volumes, surfaces and lengths increased significantly throughout gestation. Villous maturation involved phasic (capillary:villus surface and length ratios) or progressive (volume, surface and length densities) increases in indices of villous capillarization. It also involved isomorphic thinning (cross-sectional areas and perimeters declined but shape coefficients did not alter). In contrast, growth of capillaries did not involve changes in luminal areas or perimeters. The results show that villous growth and fetal angiogenesis involve increases in overall length rather than calibre and that villous differentiation involves increased capillarization. Although they do not distinguish between increases in the lengths versus numbers of capillary segments, other studies have shown that capillaries switch from branching to non-branching angiogenesis during gestation. Combined with maintenance of capillary calibres, these processes will contribute to the reduced fetal vascular impedances observed during pregnancy.

Length of Office Visits for Gastrointestinal Disease: Impact of Physician Specialty

Physician-visit length is an important determinant of patient satisfaction and outcomes. Our objective was to compare visit length for gastrointestinal disorders between gastroenterologists and primary-care providers (PCPs). From the National Ambulatory Medical Care Survey, visits to office-based physician practices between 1993 and 2004 were identified and multivariate regression was used to identify predictors of visit duration. There were 3135, 3391, and 3964 office visits associated with gastrointestinal disease, corresponding to 71, 140, and 180 million visits nationwide in 1993-1996, 1997-2000, and 2001-2004 respectively. Visit duration to all physicians increased from 17.3 minutes in 1993-1996 to 20.2 minutes in 2001-2004. Among gastroenterologists, visit length remained constant, from 21.0 minutes in 1993-1996 to 22.3 minutes in 2001-2004. On multivariate regression, age >50 years (1.8 minutes), new-patient encounters (7.4 minutes), and visits in 1997-2000 (2.7 minutes) and 2001-2004 (3.4 minutes) were associated with longer visit length. Encounters with gastroenterologists (3.3 minutes) were associated with longer visit duration than those with PCPs. The greatest adjusted difference in visit length between the two was seen for visits associated with constipation (5.7 minutes favoring gastroenterologists) and irritable bowel syndrome (2.4 minutes). There has been an overall increase in length of physician visits associated with gastrointestinal disease. Both patient and provider factors predict visit length.

Cost Analysis of Functional Restoration Surgery for Extremity Soft-Tissue Sarcoma

Limb-sparing surgery, consisting of wide-margin tumor resection and preoperative or postoperative radiotherapy/chemotherapy, has become the surgical treatment of choice for extremity sarcomas. However, adequate tumor resection can sometimes compromise crucial limb function, necessitating functional restoration surgery. The purpose of this study was to determine the cost impact and functional outcomes of such procedures. Patients receiving either functional restoration surgery or soft-tissue-only reconstruction following extremity soft-tissue sarcoma excision were identified. Patients were then compared along several dimensions: overall length of stay and its subdivisions, surgical time, and total charges and its subdivisions. Patients' functional outcomes were assessed with the Toronto Extremity Salvage Score. Sixty-seven patients who underwent 69 limb-sparing procedures were identified. Fifteen of these procedures (eight upper extremity, seven lower extremity) required functional restoration surgery; 54 of these procedures (13 upper extremity, 41 lower extremity) required only soft-tissue coverage. In the upper extremity, there was a statistically significant increase in overall length of stay (2.8 days) and its subdivisions, surgical time (3.7 hours), and total charges (12,484 dollars) and its subdivisions associated with performing functional restoration surgery. In lower extremity cases, statistically significant increases were determined in only the total charges (9190 dollars) and medical supply charges (13,204 dollars) following functional restoration. Patients who underwent functional restoration surgery had better postoperative function (mean Toronto Extremity Salvage Score, 82 versus 80), but this difference was not statistically significant. Although functional restoration surgery is more costly than soft-tissue reconstruction alone, the authors believe that the associated better functional outcome justifies its performance.

Risk for stroke after elective noncarotid vascular surgery.

Patients undergoing operations to treat peripheral vascular disease have systemic atherosclerosis and are at risk for stroke. However, the incidence and effect of cerebrovascular events on noncarotid vascular surgical outcomes are not well-defined. Patients undergoing common operations for vascular disease from 1997 to 2000 were examined with data from the Veterans Affairs (VA) National Surgery Quality Improvement Project and the VA patient treatment files. Operations studied included abdominal aortic aneurysmectomy (n = 2551), aortobifemoral bypass (n = 2616), lower extremity bypass (n = 6866), and major lower extremity amputation (n = 7442). The incidence of perioperative stroke was determined, and logistic regression analysis was used to identify independent risk factors for stroke. Logistic and linear regression analyses were used to quantify the effect of postoperative stroke on adjusted mortality and length of stay. Odds ratio (OR) and 95% confidence interval (CI) were defined. P <.05 was considered significant. Stroke was uncommon after noncarotid vascular procedures, occurring in only 0.4% to 0.6% of patients. Independent risk factors for stroke include preoperative ventilation (OR, 11; 95% CI, 5.0-22.3; P <.001), previous stroke or transient ischemic attack (OR, 4.2; 95% CI, 2.7-6.4; P <.001), postoperative myocardial infarction (OR, 3.3; 95% CI, 1.3-8.7; P =.009), and need to return to the operating room (OR, 2.2; 95% CI, 1.4-3.5; P =.001). Factors that did not appear to be associated with stroke risk included procedure type, diabetes, renal failure, dialysis dependence, number of transfused units of blood, and hypertension. After controlling for other postoperative complications and comorbid conditions, postoperative stroke significantly increased the risk for perioperative mortality (OR, 6.3; 95% CI, 3.4-11.4; P <.001), with similar magnitude as postoperative myocardial infarction (OR, 6.3; 95% CI, 3.9-10.1; P <.001). Stroke was also associated with a 48% increase in overall length of stay. Stroke after noncarotid peripheral vascular surgery is uncommon, but results in markedly increased mortality and length of stay. Stroke risk is most strongly associated with previous stroke history and greater degree of illness. Patients with these associated conditions deserve particular attention to assessing and medically managing modifiable risk factors.

The effects of nerve growth factor and dibutyryl cyclic AMP on cytoskeletal densities in cultured sensory ganglia

The effects of nerve growth factor (NGF) and dibutyryl cyclic AMP (DBC) on the density of cytoskeletal structures in cultured dorsal root ganglia were examined using morphometric techniques. After 24 hr in culture, NGF-treated neurites were longer than either DBC-treated or control neurites. At 48 hr, neurites produced in response to NGF and DBC were of equivalent length, while controls were considerably shorter. Comparison of electron micrographs of neuritic profiles revealed some differences of area and cytoskeletal density between treatment groups. Morphometric analysis was used to determine these differences under several growth conditions, at various rates of elongation and at different neurite lengths. As shown by analysis of variance, both NGF-treated and control neurites tapered in diameter at 48 hr in vitro, while DBC-induced neurites increased in area. An increase in cytoskeletal density for all treatment groups indicated that density was not always correlated with changes in area. An increased density of microtubules as compared to neurofilaments was seen at 24 hr, with equal densities of both cytoskeletal elements present after 48 hr in vitro. Comparisons between individual groups of data indicated that NGF-treated neurites relied primarily on microtubular density at 24 hr in vitro, when NGF induced longer, faster growing neurites. At 48 hr, there was an increase in neurofilaments proximal to the explant in the presence of DBC, implying that DBC may cause increased synthesis and/or transport of these structures. A comparison of microtubule to neurofilament ratios indicated that at 24 hr, there was always a greater density of microtubules. However, after 48 hr, neurofilament density increased such that there were equivalent densities of both cytoskeletal elements, possibly due to the overall increase in length observed in each treatment group. These data imply that 1) neurites with different rates of elongation may exhibit differences in cytoskeletal density; 2) neurites of equivalent lengths may be of differing stabilities; 3) NGF and DBC produce neurites with different cytoskeletal densities, implying divergent mechanisms of neurite induction; 4) the presence or absence of NGF may be partially responsible for variations in cytoskeletal densities observed between peripheral and central processes of DRG during development.

A new delay-line kicker with capacitive loading sandwiches

Abstract The delay-line type of kicker for the in- and ejection into and from cyclic accelerators is the right choice if extremely fast rise and fall times are required. It will be shown that it may be operated at 1 3 of the wave impedance of the pulse generator as compared to the lumped element solution with a corresponding reduction in the pulse voltage [1]. The pulse generator charge voltage will be reduced by a factor of 1.5. However, low wave impedance requires high capacitive loading for which the usual construction of delay-line magnets is prohibitive since is makes use of longitudinal subdivision of the ferritic core of the magnet into a number of individual cells, each cell consisting of a piece of ferrite followed by a capacitive plate connected to the magnet conductor. For decreasing cell length the percentage of longitudinal space occupied by the capacitive plate increases with a corresponding increase in overall length and a decrease in magnetic length. Therefore in practice there exists a lower limit for the cell length and the associated cell inductance. This in turn introduces a lower limit for the wave impedance since the capacitive loading would lead to unacceptable bulky capacitor units. In this article a straightforward modification of the usual design of delay-line kickers will be described with a picture frame ferrite geometry as it is used for lumped element kickers and capacitive loading units being attached to the core like sandwiches. This approach offers a number of advantages compared to the conventional solution.

Book reviewsThe Fundamentals of X-Ray and Radium Physics, 7th edit. By SelmanJoseph, xxxiii + 592 + index, 1985 (Charles C. Thomas, Springfield, Illinois), $29.75. ISBN 0–398–05065–1

This book has found a place on many a library shelf since it was first published over 30 years ago. The seventh edition shows a small increase in overall length, while a glance through the contents section suggests the changes are very superficial. The author has contented himself with the title and kept to the fundamentals of his subject, starting the book with simplified mathematics at a junior-school level and progressing slowly through basic physics, electricity and magnetism. The second quarter, dealing with X rays and their production, is very adequate, biased heavily to diagnostic equipment, the only references to radiotherapy being developed out of a discussion on absorbed dose and a later section on radiation protection.

The Pharmacological Basis of Therapeutics

The editors of first edition of The Pharmacological Basis of Therapeutics cited as their major objectives the correlation of pharmacology with related medical sciences, reinterpretation of actions and uses of drugs from viewpoint of important advances in medicine, and placing of emphasis on applications of pharmacodynamics to therapeutics. These objectives have been achieved yet again in seventh edition of this classic text. [T]he descriptions of commonly used ophthalmic medications are surprisingly comprehensive considering encyclopedic scope of this book. Although dramatic advances in fields of biochemistry, physiology, pathophysiology, and basic and clinical pharmacology have necessitated a revision of every chapter of text and an overall increase in length, current version retains simple and straightforward organization that is characteristic of previous editions. Fifty-eight noted authorities in fields of clinical pharmacology and toxicology and in such medical disciplines as

Routine preoperative biliary drainage: effect on management of obstructive jaundice.

The routine application of preoperative percutaneous transhepatic biliary drainage (PTBD) to patients who have obstructive jaundice has a significant effect on overall morbidity, mortality, and patient survival by allowing selective application of the most appropriate therapeutic modality. Surgical patients who undergo PTBD were compared with those for whom PTBD was not available. The surgical complication rate was 44% for those who did not undergo PTBD and 15% for those who did. The surgical procedure-related mortality rate was 30% for those who did not undergo PTBD and 12% for those who did. These differentials may have been due either to a beneficial effect of presurgical decompression or to the fact that only more favorable candidates were selected for operative internal bypass. There was an overall increase in length of survival following the application of PTBD, especially in those patients who were surgical candidates.

Influence of wave action and latitute on morphology and standing crop of New ZealandDurvillaea antarctica(Chamisso) Hariot (Phaeophyta, Durvilleales)

Abstract Variations in morphology and standing crop of New Zealand Durvillaea antarctica (Chamisso) Hariot are described quantitatively in relation to wave action and latitude. Distinct “thonged” (very strong wave action) and “cape” (moderate wave action) forms are recognised and described. Complete intergradation occurs, but the extent to which a population tends to one form is indicative of the wave forces predominating. Thonged-form plants show increases in overall length, stipe length and diameter, and degree of division and honeycomb development ofthe blade. Cape-form plants show a reduced overall length, stipe length and diameter, and degree of division and honeycombing of the blade. Where the impact force of waves is exceptionally strong plants may become stunted and lack development of a blade base. Generally the species is scarce where wave action is exceptionally strong or where conditions are calm. Regardless of other conditions prevailing the size of stipes increased with latitude. Water turbu...

Rapid Bioassay for Auxin

AbstractA rapid bioassay is described for the detection of growth substances. The bioassay is simple to perform under ordinary laboratory or classroom conditions and the sensitivity to auxin is comparable to other bioassays, including those using Avena first internode sections. The bioassay is performed on isolated first internode sections from partly etiolated bean plants (Phaseolus vulgaris L. cv. Bush Burpee Stringless Bush Bean). The test material is applied to one side and near the base of the section. Auxin treatments induce curvature and the distance of the lateral displacement of the apical portion of the segment is proportional to the concentration applied. Routinely, the indole 3‐acetic acid response is measured 1 to 3 h after treatment. The sections also respond to gibberellic acid (GA3), which induces an increase in overall length, but unlike auxin, GA3 does not cause curvature. The test compounds are applied via a small filter paper disk that provides a convenient means for studying interactions of two or more compounds by co‐applications. Auxin‐induced growth can be monitored with a sensitive motion detector. Data are presented which confirm the usefulness of the assay.