Applicability of radiotracer methods of measuring14CO2 assimilation for determining microbial activity in soil including a newin situ method

The applicability of two methods (pyrolysis gas chromatography and acidification-wet oxidation) for determining¹⁴CO₂ incorporation into soil microorganisms was investigated. Both methods were able to distinguish biologically incorporated¹⁴C from abiotically adsorbed¹⁴C, but to varying degrees, there being a larger carryover of abiotic¹⁴C into the organic fraction and a higher percentage of assimilated¹⁴C in the organic fraction with the wet oxidation method. Using¹⁴C assimilation as a measure, it was possible to determine microbial activities in soils of diverse properties under a variety of conditions, including polar soils under harsh environmental conditions. Both light and dark¹⁴CO₂ fixation was measurable.¹⁴CO₂ assimilation was not always proportional to the enumerable microorganisms. A new design for measurement of microbial activityin situ enabled measurement of total C influx (primary productivity) into soils with minimal perturbation to the natural soil ecosystem.     

Lymphangiography: Its Practical Value in Surgically Staged Patients with Hodgkin's Disease

Since the introduction of “staging laparotomy” (to determine the disease''s stage) in assessing Hodgkin''s disease, some observers have argued that lymphangiography could be safely omitted in the initial diagnostic evaluation.To test these opinions a series of 75 patients with Hodgkin''s disease who had a staging laparotomy and histological correlation with lymphangiograms was reviewed. Of 16 examinations with positive results, one proved to be a false positive. Of the 14 examinations with equivocal results, one proved histologically positive. In the remaining 45 lymphangiograms, five were falsely negative. In all five of these patients abdominal lymph nodes were involved, but in areas that do not routinely opacify on lower extremity lymphangiography. The overall accuracy was 90 percent.Therapeutically, the lymphangiogram permits accurate planning for treatment by radiation therapy so that all known disease is treated and yet bone marrow is not excessively irradiated. Changes in lymph node architecture after therapy provide valuable information as to regression of the disease or signs of its early recurrence.     

Preliminary characterization of Thy-1.1 and Ag-B antigens from rat tissues solubilized in detergents

1. A radioactive binding assay for Thy-1.1 alloantigen which functions in the presence of detergents was established by using glutaraldehyde-fixed thymocytes as target cells. Thy-1.1 activity in detergent extracts was then assayed by measuring inhibition of the binding assay. 2. Solubilization of Thy-1.1 from whole thymocytes, and their membranes by a large number of non-ionic detergents and deoxycholate was studied. In the same extracts Ag-B(4) histocompatibility antigenic activities were measured. With the exception of Nonidet P-40, the detergents did not affect the antigenicity of Thy-1.1, but only Lubrol-PX and deoxycholate gave effective solubilization as measured by activity remaining in the supernatant after centrifugation at 200000g for 40min. With Ag-B(4) antigen, Triton X-100, Triton X-67 and Nonidet P-40 gave effective solubilization as well as Lubrol-PX and deoxycholate. Solubilization of Thy-1.1 activity from leukaemia cells and a brain homogenate was also studied, but none of the non-ionic detergents gave satisfactory results with these tissues. 3. Extracts from thymocyte membranes were further examined by gel filtration and sucrose gradient centrifugation. The Thy-1.1 activity behaved as a single component in deoxycholate with a density similar to that of a globular protein, but in Lubrol-PX the antigen was contained in a low-density complex. In Lubrol-PX extracts Ag-B(4) was also found in aggregates not observed in deoxycholate. 4. The s(20,w) values for Thy-1.1 and Ag-B(4) antigens in deoxycholate were 2.4 and 4.4, and v values were 0.70 and 0.75 respectively. The Stokes radius observed for Thy-1.1 was 3.1nm and for Ag-B(4) 5.3nm. By using these values the molecular weights for the antigen-detergent complexes were calculated to be 28000 for Thy-1.1 and 100000 for Ag-B(4).     

Polarography of Polynucleotides: III. Polyadenylic Acid: The Electrode Process and Interaction with Polyamines

Polyadenylic acid (poly A) was studied under various conditions using both DC polarography and phase sensitive AC polarography and by measuring the time-course of the current during the lifetime of a single drop of the dropping mercury electrode. Under certain conditions the current at potentials of the limiting portion of the DC polarographic wave does not reach its limiting value and in extreme situations peak-shaped curves are observed. This phenomenon is explained in terms of desorption and repulsion from the electrode of neutral poly A due to its polyanionic character. Consequently, the suppression of the current can be enhanced by increasing negative potential of the electrode and by exposing the negative charges of phosphate groups, e.g., by increasing pH and temperature and by decreasing ionic strength and buffer capacity; vice versa, the current suppression can be at least partially eliminated by reversing these conditions. Polyamines which seem to shield the phosphate groups through specific interactions are very effective in eliminating the current suppression. The effectiveness of a polyamine is determined by its chain length and by the density of its amino groups and the geometry of their distribution.     

Repair Kinetics of Radiation-Induced Mitotic Delay

The recovery from radiation-induced mitotic delay in asynchronous sarcoma-180 (S-180) ascites tumor cells has been analyzed in a manner analogous to the repair of sublethal damage. 200-R increments were separated by various fraction intervals (not exceeding the time necessary for mitosis to return to control levels) for total exposures up to 1600 R. The accumulated mitotic delay after the last exposure increment, in percent of an equivalent single exposure, decreased exponentially with overall treatment time in a bimodal fashion. An initial repair process displayed a half time of 2.3 h of overall elapsed time and was followed by a slower process with a half time of 15.1 h. Such a bimodal recovery provides an explanation of why fractionation intervals long with respect to the amitotic period resulting from a single 200 R exposure enhance mitotic delay over that of equivalent single exposures, while shorter fractionation intervals diminish it. It also predicts that mitotic delay vs. dose curves should bend toward the abscissa as the exposure time is increased with large single exposures and large fractionated exposures given over short fraction intervals.     

Deformation of the Diastolic Left Ventricle: I. Nonlinear Elastic Effects

A linear incremental finite element model is used to analyze the mechanical behavior of the left ventricle. The ventricle is treated as a heterogeneous, non-linearly elastic, isotropic, thick-walled solid of revolution. A new triaxial constitutive relation for the myocardium is presented which exhibits the observed exponential length-passive tension behavior of left ventricular papillary muscle in the limit of uniaxial tension. This triaxial relation contains three parameters: (a) a “small strain” Young's modulus, (b) a Poisson's ratio, and (c) a parameter which characterizes the nonlinear aspect of the elastic behavior of heart muscle. The inner third and outer two-thirds of the ventricular wall are assumed to have small strain Young's moduli of 30 and 60 g/cm², respectively. The Poisson's ratio is assumed to be equal to 0.49 throughout the ventricular wall. In general, the results of this study indicate that while a linearly elastic model for the ventricle may be adequate in terms of predicting pressure-volume relationships, a linear model may have serious limitations with regard to predicting fiber elongation within the ventricular wall. For example, volumes and midwall equatorial circumferential strains predicted by the linear and nonlinear models considered in this study differ by approximately 20 and 90%, respectively, at a transmural pressure of 12 cm H₂O.     

Secondary and Tertiary Responses of the Induced Bactericidin from the West Indian Spiny Lobster, Panulirus argus

West Indian spiny lobsters, Panulirus argus, synthesized a hemolymph bactericidin after being injected with killed suspensions of gram-negative bacillus EMB-1 isolated from the normal gut of this lobster. To study differences between the primary response and secondary response, animals were given a primary antigen injection of EMB-1 followed by a second injection of the same antigen 22 to 51 days later. As a rule, secondary bactericidal responses were enhanced over the primary in a manner reminiscent of specific anamnesis in mammalian immunoglobulin synthesis. Immunological memory was also suggested when tertiary responses were compared to secondary and by the persistence of residual titers for many days or weeks without additional antigenic stimulation.     

Variations in the middle ear of the Mammalia

The comparative morphology of mammalian middle ear structures has been studied by examining the histological sections of the ears of 144 specimens of mammals which had been collected, with a few exceptions, in two expeditions to the Caribbean area. Fifty-four species of six orders of mammals were represented. Sixteen structural features or relationships were specifically studied and the bearing of taxonomic groupings on the variability was analysed.
A taxonometric analysis using these middle ear features indicated that Microdipodops may lie nearer to Dipodomys than to Perognathus.
A table presenting the detailed results has been deposited with the British Museum (Natural History).     

Two Additional Salmonella Serotypes: Salmonella enteritidis Ser 58:a:- and Salmonella enteritidis Ser 44Z36, Z38:-

The antigenic compositions of two additional Salmonella serotypes isolated from the feces of man were determined to be 58:a:- and 44:Z(36), Z(38)-.     

Number of Transformable Units Per Cell in Diplococcus pneumoniae

Analysis of frequencies of single and random multiple transformations in Diplococcus pneumoniae showed that there are at least two transformable units per cell of the total population in highly competent cultures. If 100% of the cells are competent in these cases, the units may be interpreted as the strands of one duplex deoxyribonucleic acid recipient chromosome. The theory is developed to allow for extension to more complex situations.