Handgrip and knee extension strength as predictors of cancer mortality: A systematic review and meta-analysis.

The specific role of different strength measures on mortality risk needs to be clarified to gain a better understanding of the clinical importance of different muscle groups, as well as to inform intervention protocols in relation to reducing early mortality. The aim of the systematic review and meta-analysis was to determine the relationship between muscular strength and risk of cancer mortality. Eligible cohort studies were those that examined the association between muscular strength, as assessed using validated tests, and cancer mortality in healthy youth and adults. The hazard ratio (HR) estimates obtained were pooled using random effects meta-analysis models. The outcome was cancer mortality assessed using the HR (Cox proportional hazards model). Eleven prospective studies with 1 309 413 participants were included, and 9787 cancer-specific deaths were reported. Overall, greater handgrip (HR = 0.97, 95% CI, 0.92-1.02; P = .055; I2  = 18.9%) and knee extension strength (HR = 0.98, 95% CI, 0.95-1.00; P = .051; I2  = 60.6%) were barely significant associated with reduced risk of cancer mortality. Our study suggests that higher level of muscular strength is not statistically associated with lower risk of cancer mortality.

Treadmill training in Parkinson's patients after deep brain stimulation: Effects on gait kinematic.

OBJECTIVE: The purpose of this study was to evaluate the effect of treadmill training with body weight support on gait kinematics parameters in patients with PD using DBS. DESIGN: Twelve patients completed the protocols (age: 60.9±10.6 years; disease duration: 20±7 years; and time since DBS surgery: 20±4 months). The same set of patients underwent two trainings protocols and four gait analyses (before and after each training). They received eight weeks of treadmill training without body weight support (16 sessions) in conjunction with physiotherapy program followed by six weeks of wash out period, followed by eight weeks of body-weight-supported treadmill training in conjunction with a same physiotherapy program. The Gait Kinematic Analysis involved eight infrared cameras that detected 19 reflective spherical markers attached in limb lower of patients. Statistical analysis used the Wilcoxon test (p≤0.05). RESULTS: Both the training no showed significant differences in linear variables. As the angular variables, only training with support showed significant increase of ranges of motion: pelvis tilt, obliquity and rotation amplitude; hip adduction-abduction and rotation amplitude; percentage of peak flexion in swing phase; foot progression amplitude. CONCLUSION: The body weight supported treadmill training may promote increase of mobility of lower limbs during gait and it could be a targeted intervention for PD patients treated with DBS.

Pharmacokinetics of sufentanil in patients undergoing coronary artery bypass graft surgery.

OBJECTIVE: To determine the pharmacokinetics of sufentanil in patients undergoing coronary artery bypass graft surgery. DESIGN: Prospective, multigroup study. SETTING: University-affiliated hospital. PARTICIPANTS: Patients with good left ventricular function undergoing elective surgery (n = 103). INTERVENTIONS: Sufentanil was administered by target-controlled infusion, with target effect-site concentrations ranging from 0.4 to 4.5 ng/mL. Isoflurane was administered as required to maintain stable hemodynamics. Sufentanil pharmacokinetics were determined by population modeling. The potential effects of gender, weight, different premedications (lorazepam, morphine-scopolamine, or clonidine), and coinduction with propofol on sufentanil pharmacokinetics were explored. MEASUREMENTS AND MAIN RESULTS: The first model determined was a simple 3-compartment model, without any covariates, which had these parameters: V(1) = 5.7 L, V(2) = 18.1 L, V(3) = 225 L, Cl(1) = 0.69 L/min, Cl(2) = 3.1 L/min, and Cl(3) = 1.4 L/min. The overall predictive ability during the entire pre-cardiopulmonary bypass period of this model was excellent, with virtually no bias (median prediction error, -0.4%) and good precision (median absolute prediction error, 18.4%). More complex models with the various premedications used or coinduction with propofol as covariates did not improve the predictive accuracy or precision compared with the simple 3-compartment model. Similarly, including either gender or weight as a covariate did not improve predictive ability. CONCLUSION: The authors have determined a pharmacokinetic model for sufentanil that can be used to maintain desired target concentrations of sufentanil before cardiopulmonary bypass, with a high degree of accuracy and acceptable variability. Concomitantly administered medications (lorazepam, morphine-scopolamine, clonidine, or propofol) do not appear to have any clinically important effects on distribution-phase sufentanil pharmacokinetics.

A comparison of clonidine with conventional preanesthetic medication in patients undergoing coronary artery bypass grafting.

UNLABELLED: In this controlled study, we compared clonidine with conventional premedication in 35 patients undergoing coronary artery bypass grafting (CABG). After premedication with clonidine 5 microg/kg p.o. (Group C, n = 11), lorazepam 60 microg/kg p.o. (Group L, n = 13), or morphine 0.1 mg/kg plus scopolamine 6 microg/kg i.m. (Group M, n = 11), sedation, anxiety, and quality of premedication were graded. After the administration of sufentanil 2.0 microg/kg over 12.5 min, a computer-assisted infusion device targeted a sufentanil effect-site concentration of 0.75 ng/mL. Hemodynamic variables, end-tidal isoflurane concentration (ET-ISO), the electroencephalographic spectral edge, and the serum sufentanil concentration (SUF) were measured. There were no intergroup differences in anxiety, sedation, quality of premedication, the dose of sufentanil causing unconsciousness, or the electroencephalographic (EEG) response to induction. Intraoperative SUF was stable, with no intergroup difference. The average prebypass ET-ISO was lower in Group C than in Group M. The ET-ISO and peak ET-ISO after intense surgical stimulation were lower in Group C versus Groups L and M. Mean arterial blood pressure was lower in Group C versus Groups L and M. There were no intergroup differences in pharmacologic intervention, time to extubation, or intensive care unit stay. Clonidine produces sedation, anxiolysis, and quality of premedication comparable to conventional premedication. Compared with other drugs, clonidine does not alter the dose of sufentanil inducing unconsciousness or EEG slowing, but it uniquely reduces isoflurane requirements. IMPLICATIONS: In patients undergoing coronary artery bypass grafting, clonidine produces sedation and relieves anxiety as effectively as conventional premedication. Clonidine does not uniquely alter the dose of sufentanil inducing unconsciousness or electroencephalographic slowing, but it significantly reduces isoflurane requirements.

Instrumented posterolateral lumbar fusion. Results and comparison with anterior interbody fusion.

STUDY DESIGN: Prospective case series. OBJECTIVES: To assess the results of instrumented posterolateral lumbar fusion, using recognized outcome assessment techniques, to evaluate the correlation between technical and clinical results and the effects of assessment techniques, and to compare the outcome with that of anterior lumbar fusion. SUMMARY OF BACKGROUND DATA: Assessments of lumbar spinal fusion results have frequently been published in forms that render direct comparison difficult and thus have not provided optimal assistance in the selection of a preferred method of treatment. METHODS: One hundred and thirty-five patients with intractable back pain underwent instrumented posterolateral lumbar spinal fusion performed by a single surgeon. Review of results was undertaken by independent observers, using a recognized outcome assessment measure. RESULTS: A solid bony fusion was obtained in 82% of patients. The method of outcome assessment profoundly affected the results; whereas 65% of patients rated themselves significantly improved by the procedure, only 19% achieved a good or excellent result on the Low Back Outcome Score. Patients undergoing a second procedure did not do well, and "salvage" surgery is not recommended. Compensation status was a significant prognostic factor. Psychological distress at review had a profound effect on the disability score and on patient satisfaction ratings. Overall, the results were inferior to those in a similar series treated by anterior lumbar fusion. CONCLUSION: It is recommended that in future studies a recognized outcome score be used and that the analysis specifically include compensation status and psychological distress.

Dictyostelium discoideum myoJ: a member of a broadly defined myosin V class or a class XI unconventional myosin?

The simple eukaryote Dictyostelium discoideum contains at least 12 unconventional myosin genes. Here we report the characterization of one of these, myoJ, a gene initially identified through a physical mapping screen. The myoJ gene encodes a high molecular weight myosin, and analysis of the available deduced amino acid sequence reveals that it possesses six IQ motifs and sequences typical of alpha helical coiled coils in the tail region. Therefore, myoJ is predicted to exist as a dimer with up to 12 associated light chains (six per heavy chain). The 7.8 kb myoJ mRNA is expressed all throughout the life cycle of D. discoideum. The myoJ gene has been disrupted and a phenotypic analysis of the mutant cells initiated. Finally, phylogenetic analysis of the head region reveals that myoJ is most similar to two plant myosin genes, Arabidopsis MYA1 and MYA2, that have been alternatively suggested to be either members of the myosin V class or founding members of the myosin XI class.

Examination of the endosomal and lysosomal pathways in Dictyostelium discoideum myosin I mutants.

The role of myosin Is in endosomal trafficking and the lysosomal system was investigated in a Dictyostelium discoideum myosin I double mutant myoB-/C-, that has been previously shown to exhibit defects in fluid-phase endocytosis during growth in suspension culture (Novak et al., 1995). Various properties of the endosomal pathway in the myoB-/C- double mutant as well as in the myoB- and myoC- single mutants, including intravesicular pH, and intracellular retention time and exocytosis of a fluid phase marker, were found to be indistinguishable from wild-type parental cells. The intimate connection between the contractile vacuole complex and the endocytic pathway in Dictyostelium, and the localization of a myosin I to the contractile vacuole in Acanthamoeba, led us to also examine the structure and function of this organelle in the three myosin I mutants. No alteration in contractile vacuole structure or function was observed in the myoB-, myoC- or myoB-/C- cell lines. The transport, processing, and localization of a lysosomal enzyme, alpha-mannosidase, were also unaltered in all three mutants. However, the myoB- and myoB-/C- cell lines, but not the myoC- cell line, were found to oversecrete the lysosomal enzymes alpha-mannosidase and acid phosphatase, during growth and starvation. None of the mutants oversecreted proteins following the constitutive secretory pathway. Two additional myosin I mutants, myoA- and myoA-/B-, were also found to oversecrete the lysosomally localized enzymes alpha-mannosidase and acid phosphatase. Taken together, these results suggest that these myosins do not play a role in the intracellular movement of vesicles, but that they may participate in controlling events that occur at the actin-rich cortical region of the cell. While no direct evidence has been found for the association of myosin Is with lysosomes, we predict that the integrity of the lysosomal system is tied to the fidelity of the actin cortex, and changes in cortical organization could influence lysosomal-related membrane events such as internalization or transit of vesicles to the cell surface.

Dictyostelium myosin I double mutants exhibit conditional defects in pinocytosis.

The functional relationship between three Dictyostelium myosin Is, myoA, myoB, and myoC, has been examined through the creation of double mutants. Two double mutants, myoA-/B- and myoB-/C-, exhibit similar conditional defects in fluid-phase pinocytosis. Double mutants grown in suspension culture are significantly impaired in their ability to take in nutrients from the medium, whereas they are almost indistinguishable from wild-type and single mutant strains when grown on a surface. The double mutants are also found to internalize gp126, a 116-kD membrane protein, at a slower rate than either the wild-type or single mutant cells. Ultrastructural analysis reveals that both double mutants possess numerous small vesicles, in contrast to the wild-type or myosin I single mutants that exhibit several large, clear vacuoles. The alterations in fluid and membrane internalization in the suspension-grown double mutants, coupled with the altered vesicular profile, suggest that these cells may be compromised during the early stages of pinocytosis, a process that has been proposed to occur via actin-based cytoskeletal rearrangements. Scanning electron microscopy and rhodamine-phalloidin staining indicates that the myosin I double mutants appear to extend a larger number of actin-filled structures, such as filopodia and crowns, than wild-type cells. Rhodamine-phalloidin staining of the F-actin cytoskeleton of these suspension-grown cells also reveals that the double mutant cells are delayed in the rearrangement of cortical actin-rich structures upon adhesion to a substrate. We propose that myoA, myoB, and myoC play roles in controlling F-actin filled membrane projections that are required for pinosome internalization in suspension.

The effect of operative position on lumbar lordosis. A radiographic study of patients under anesthesia in the prone and 90-90 positions.

STUDY DESIGN: The effect of intraoperative positioning on lumbar lordosis was retrospectively studied by radiographic analysis of 40 patients under general anesthesia. OBJECTIVES: The aim of this study was to document changes in segmental and total lumbar lordosis between preoperative standing and intraoperative radiographs taken in the "90-90" and prone positions. SUMMARY OF BACKGROUND: Preservation of physiologic lordosis was an important consideration in reconstructive lumbar spine surgery. To avoid iatrogenic loss of lordosis when using spinal instrumentation and to facilitate decompressive procedures, it was necessary to understand how segmental alignments were affected by intraoperative positioning. Although many positioning techniques were used, the effect on lumbar lordosis was not well established. METHODS: Preoperative (standing 36" lateral spine) and intraoperative radiographs (lateral lumbar spine L1 to the sacrum) in either the "90-90" position on a Hastings frame (n = 20) or the prone position on a Jackson table (n = 20) were measured twice by two independent observers using Cobb methodology for total and segmental lordosis between L1 and S1. Data were analyzed for intra- and interobserver reliability and changes in segmental and total lordosis between standing and intraoperative radiographs. RESULTS: Analysis of intra- and interobserver reliability revealed measurements were accurate and reproducible. The "90-90" position produced significant loss (P < or = 0.01) of total and segmental lordosis at all levels except L1-L2, which showed no change. Segmental lordosis was reduced nearly 60% at L2-L3, L3-L4, and L4-L5, and total lordosis was reduced by more than 35%. The prone position on the Jackson table increased segmental lordosis at L5-S1 by 22% (P < or = 0.01) and preserved total and segmental standing lordosis at all other levels. CONCLUSIONS: The "90-90" position on the Hastings frame was associated with significant reduction of total and segmental lordosis in the middle and lower lumbar spine. Positioning prone on a Jackson table maintained standing lumbar lordosis and increased lumbosacral lordosis.

Molecular genetic analysis of myoC, a Dictyostelium myosin I.

The protozoan myosin Is are widely expressed actin-based motors, yet their in vivo roles remain poorly understood. Molecular genetic studies have been carried out to determine their in vivo function in the simple eukaryote Dictyostelium, an organism that contains a family of four myosin Is. Here we report the characterization of myoC, a gene that encodes a fifth member of this family. Analysis of the deduced amino acid sequence reveals that the myoC gene encodes a myosin that is homologous to the well-described Acanthamoeba myosin Is as well as to Dictyostelium myoB and -D. The expression pattern of the myoC mRNA is similar to that of myoB and myoD, with a peak of expression at times of maximal cell migration, around 6 hours development. Deletion of the myoB gene has been previously shown to result in mutant cells that are defective in pseudopod extension and phagocytosis. However, no obvious differences in cell growth, development, phagocytosis or motility were detected in cells in which the myoC gene had been disrupted by homologous recombination. F-actin localization and ultrastructural organization also appeared unperturbed in myoC- cells. This apparent 'lack' of phenotype in a myosin I single knockout cannot be simply explained by redundancy of function. Our results rather suggest that the present means of assessing myosin I function in vivo are insufficient to identify the unique roles of these actin-based motors.

F-actin distribution of Dictyostelium myosin I double mutants.

The roles of the myosin I class of mechanoenzymes have been investigated by single and double gene knockout studies in the amoeba Dictyostelium discoideum. Cells lacking different myosin I pairs (myoA-/myoB-, myoB-/myoC-, and myoA-/myoC-) were examined with respect to their cytoskeletal organization. F-actin localization by rhodamine-phalloidin staining of cells indicates that the myoA-/myoB-, myoB-/myoC-, and myoA-/myoC- cells appear to redistribute their F-actin more slowly than wild type cells upon adhesion to a substrate. These studies suggest that Dictyostelium myoA, myoB, and myoC may have overlapping roles in maintaining the integrity or organization of the cortical membrane cytoskeleton.

A draining sinus tract of obscure etiology: a case report.

A patient presented with a draining sinus tract on the lingual alveolus of the posterior mandibular ridge. The source of the sinus tract was not readily apparent. Radiographs created the impression that a lesion of unusual and possibly metastatic origin might be involved. Comprehensive diagnostic tests were ordered, but the source of the lesion remained obscure until a surgical exploration was performed.

An in vitro model for the analysis of intestinal brush border assembly. I. Ultrastructural analysis of cell contact-induced brush border assembly in Caco-2BBe cells.

Intestinal epithelial cells assemble and maintain a polarized, highly organized membrane-cytoskeleton array, the brush border. We describe an in vitro, cell contact-induced brush border assembly model using the Caco-2BBe clones. Subconfluent cells were 'depolarized' by brief passage through suspension culture in the presence of cytochalasin D and re-plated on filters at high density in low-Ca2+ medium. Upon return to regular medium, these small, rounded cells with bleb-like protrusions formed, over the course of 19 days, a polarized monolayer of tall, columnar cells with a well-defined brush border. Ultrastructural changes were documented by both transmission and scanning electron microscopy. The earliest events of microvillar assembly coincided with a short period of cell aggregation. Intercellular cysts were occasionally observed within these aggregates, and junction formation between cells which had no contact with the filter was also observed. Monolayer formation was completed within 48 hours, and cell height steadily increased approximately 3.5-fold over 19 days. Concurrent with monolayer formation and the increase in cell height, sparse microvilli with a few actin core filaments gradually became more dense and better organized. By the third day, the actin core bundles had begun to extend into the subjacent cytoplasm, while terminal web assembly was underway at five days. The mature morphology of the brush border was first observed at nine days, although cell height and microvillar density continued to increase during the subsequent ten days. Microvillar density rose approximately nine-fold throughout brush border assembly in the Caco-2BBe cells. With the exception of the formation of cellular aggregates at the onset of the time course, this sequence of morphological changes is comparable to that observed during brush border assembly in embryonic intestinal epithelial cells. The Caco-2BBe assembly model provides a useful system in which to investigate various molecular aspects of brush border assembly.

An in vitro model for the analysis of intestinal brush border assembly. II. Changes in expression and localization of brush border proteins during cell contact-induced brush border assembly in Caco-2BBe cells.

In the companion paper (M. D. Peterson and M. S. Mooseker (1993). J. Cell Sci. 105, 445-460) we describe a method for modeling brush border assembly in the Caco-2BBe clones. In this study we have examined the molecular changes accompanying cell contact-induced brush border assembly. A subset of brush border proteins was tracked throughout brush border assembly by immunoblotting and by immunofluorescent localization using laser scanning confocal microscopy. Actin, fodrin, villin and presumptive unconventional myosin immunogens were distributed at the periphery of depolarized cells. All proteins partitioned primarily with the membrane fraction upon differential sedimentation of depolarized cell lysates; the fractionation patterns were comparable to those of confluent cells. After a monolayer had formed, each protein showed a redistribution to the apical domain in a discrete sequence. Actin and villin began to shift apically at 2 d, while fodrin and the unconventional myosin immunogens did not redistribute until 3 d. Enterocyte-like localization was observed by 5 d for all proteins. Sucrase-isomaltase was not reliably detectable until 9 d by immunofluorescence, after brush border assembly was complete. Quantitative immunoblot analysis of total cell extracts demonstrated an average 10-fold increase in villin levels, while fodrin levels appeared to remain unchanged. Three putative unconventional myosin immunogens of 140 kDa, 130 kDa, and 110 kDa have been detected previously in the C2BBe cells with a head-specific monoclonal antibody to avian brush border myosin I (M. D. Peterson and M. S. Mooseker (1992) J. Cell Sci. 102, 581-600). Each of these immunogens displayed distinct expression patterns during brush border assembly. The 140 kDa species decreased by half, while the 130 kDa immunogen(s) did not change in any consistent fashion. The 110 kDa protein, presumed to be human brush border myosin I, rose on average 8-fold. A ribonuclease protection assay was also performed using a probe for human brush border myosin I. Equal amounts of total RNA from depolarized and confluent cells were assayed; the level of protected product was approximately 9-fold greater in the confluent cells. The expression patterns of the brush border proteins, coupled with the correlation to the ultrastructural features during brush border assembly in C2BBe cells, show that differentiation of the C2BBe cells closely resembles the changes that occur during human fetal intestinal differentiation.

Characterization of the enterocyte-like brush border cytoskeleton of the C2BBe clones of the human intestinal cell line, Caco-2.

The brush border (BB) of the enterocyte is a well-studied example of the actin-based cytoskeleton. We describe here a cell culture model that expresses a faithful representation of the in vivo structure. Two clones (C2BBe 1 and 2) isolated from the cell line Caco-2 (derived from a human colonic adenocarcinoma) formed a polarized monolayer with an apical BB morphologically comparable to that of the human colon. BBs could be isolated by standard methods and contained the microvillar proteins villin, fimbrin, sucrase-isomaltase and BB myosin I, and the terminal web proteins fodrin and myosin II. The immunolocalization of these proteins in confluent, filter-grown monolayers was determined by laser scanning confocal microscopy; patterns of distribution comparable to those in human enterocytes were observed. Sedimentation analysis of cell homogenates derived from C2BBe cells and human colonic epithelial cells demonstrated similar patterns of fractionation of BB proteins; the physical association of those proteins, as determined by extraction from the BB, was also comparable between the two cell types. Like enterocytes of the human intestine, C2BBe cells expressed multiple myosin I immunogens reactive with a head domain-specific monoclonal antibody raised against avian BB myosin I, one of which co-migrated with the approximately 110 kilodalton (kDa) heavy chain of human BB myosin I. In addition, the C2BBe cells express a pair of higher molecular mass immunogens (130 and 140 kDa). These myosin I immunogens all exhibit ATP-dependent association with the C2BBe cytoskeleton. Although the higher molecular mass immunogens were detected in several other human intestinal lines examined, including the parent Caco-2 line, none of these other lines expressed detectable levels of the 110 kDa immunogen, which is presumed to be the heavy chain of human BB myosin I.

The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia in children.

The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia were studied in 15 unpremedicated ASA I children using measurements of heart rate, blood pressure and M-mode echocardiography (echo). The children (ages 2 to 7.3 yr) were randomly assigned to receive either isoflurane (N = 8) or halothane (N = 7) with oxygen. End-tidal carbon dioxide concentrations (range 30-44 mmHg) were monitored throughout the study in each child. The experimental protocol was completed prior to intubation and the initiation of surgery. Within each anesthetic group, preinduction (control) hemodynamic and echo measurements were compared with measurements obtained at two sequential equipotent end-tidal anesthetic concentrations (0.74% and 2.22% isoflurane; or 0.5% and 1.5% halothane). We also compared the data of the isoflurane group with that of the halothane group at each equipotent end-tidal anesthetic concentration. Preinduction hemodynamic (heart rate, blood pressure) and echo measurements (left ventricular dimensions and function) were similar between the two anesthetic groups. With isoflurane or halothane administration, blood pressure decreased significantly, while heart rate remained essentially unchanged. The observed alterations in heart rate and blood pressure were similar in both study groups at each equipotent end-tidal anesthetic concentration. In contrast, there were marked differences in the echo measurements of the two anesthetic groups. Halothane was associated with a significant dose-dependent decrease in echo-measured left-ventricular shortening fraction and mean velocity of circumferential fiber shortening. These echo measurements were not significantly altered by isoflurane at either end-tidal anesthetic concentration. These alterations suggest halothane is associated with significant myocardial depression in normal children, while myocardial function is well preserved during isoflurane anesthesia.

Types of aortic stenosis in surgically removed valves.

In 109 specimens of aortic valves removed surgically from adults for isolated or dominant aortic stenosis, five types of valve were encountered. In order of decreasing frequency the types were as follows: calcification of congenitally bicuspid aortic valves (48.6%); calcification of a normally tricuspid aortic valve without commissural fusion, the so-called senile type of aortic stenosis (27.6%); calcification of an acquired bicuspid valve (12.8%); the fibrous (rheumatic)-type valve (10.1%); and calcification of congenitally unicuspid valves (0.9%). In the overall study men were more commonly represented than women by a ratio of 3:2. In only the senile type were women more commonly represented than men.

Biological activities of indoleacetylamino acids and their use as auxins in tissue culture.

THE AUXIN ACTIVITIES OF A NUMBER OF INDOLEACETYLAMINO ACID CONJUGATES HAVE BEEN DETERMINED IN THREE TEST SYSTEMS: growth of tomato hypocotyl explants (Lycopersicon esculentum Mill. cv. Marglobe); growth of tobacco callus cultures (Nicotiana tabacum L. cv. Wisconsin 38); and ethylene production from pea stems (Pisum sativum L. cv. Alaska). The activities of the conjugates differ greatly depending on the amino acid moiety. Indoleacetyl-l-alanine supports rapid callus growth from the tomato hypocotyls while inhibiting growth of shoots and roots. Indoleacetylglycine behaves in a similar manner but is somewhat less effective in supporting callus growth and in inhibiting shoot formation. The other amino acid conjugates tested (valine, leucine, aspartic acid, threonine, methionine, phenylalanine, and proline) support shoot formation without supporting root formation or much callus growth. The tobacco callus system, which forms abundant shoots in the presence or absence of free indoleacetic acid, produces only rapid undifferentiated growth in the presence of indoleacetyl-l-alanine and indoleacetylglycine. The other conjugates inhibit shoot formation weakly if at all. Most of the conjugates induce sustained ethylene production from the pea stems but at rates well below the initial rates observed with free indoleacetic acid. Many, but not all of the effects of conjugates such as indoleacetyl-l-alanine can be mimicked by frequent renewals of the supply of free indoleacetic acid.

Comparison of skin doses to large fields using tangential beams from cobalt-60 gamma rays and 4-MV x rays.

Excess radiation to the skin during external beam megavoltage radiation therapy has reportedly caused excessive erythema in patients treated with the Clinac 4 linear accelerator on sloping surfaces, but not for similar treatments with cobalt 60. Doses at the epidermal level were measured under geometries simulating sloping surfaces for a Clinac 4 and an Eldorado 8 cobalt-60 teletherapy machine. For equal doses to the axilla, doses to the epidermal layer were similar. When the tumor dose was calculated for the mediastinum, the dose to the skin in the axillary region was 12% higher for the Clinac 4.