Monoclonal antibodies showing sequence specificity in their interaction with single-stranded DNAs

Six hybridoma cell lines which secrete monoclonal antibodies binding to nucleic acids were produced from autoimmune NZB/NZW mice. Four of the antibodies were IgG's and the other two were IgM's. Using a solid phase radioimmunoassay (SPRIA) the binding of the antibodies to over thirty different nucleic acids was estimated. All the antibodies were extremely specific. There was no detectable interaction with various RNAs, and single-stranded DNAs bound more antibodies than duplex or multi-stranded DNAs. In every case the antibodies also showed considerable sequence preferences. For example one monoclonal antibody bound to d(TTC)n but not to d(TCC)n while another interacted strongly with D(TG)n and d(CA)n but not with d(TC)n, d(GA)n or homopolymers. In other cases the patterns of sequence specificity were extremely difficult to interpret although it seems clear that monoclonal antibodies have the potential to distinguish between any two nucleic acids however similar.

Lymph flow during fluid absorption from rat jejunum

The relation between intestinal lymph flow (JL) and fluid absorption rate (JV) was studied with an in vivo jejunal preparation of the rats under pentobarbital sodium anesthesia. It was found that in more than 60% of the rats there is a communication between hepatic and intestinal lymphatics. JL was significantly higher in these rats whether the intestine was in the nonabsorptive state or during fluid absorption. This is undoubtedly due to the contribution of hepatic lymph. The increased lymph flow due to fluid absorption in the rats without hepatic lymphatic communication varied over a wide range of 0-27% of the absorbed volume with a mean value of 8%. In the rats with simultaneous fat absorption, JV did not change but JL decreased to about 3% of the absorbed volume. There was no correlation between JL and JV. Furthermore, obstruction of JL caused no change in JV, indicating that the lymphatic system is not indispensable in fluid transport. From these findings, it is concluded that JL is not a constant proportion of the absorbed volume but depends on the pathophysiological state of the intestine.

Occupational and environmental health problems of the developing oil shale industry: a review

The American oil shale industry is on the threshold of commercial industrial development. Potential occupational hazards include shalosis or oil shale pneumoconiosis, dermatoses, cancer of the skin, lung, and possibly other sites, and accidents. Air, water, and solid waste pollution problems are complicated by the aridity of the Green River oil shale formation located in Utah, Colorado, and Wyoming. The region currently lacks the schools, health facilities, community services, and skilled labor required for large-scale development. The oil shale industry faces an opportunity and a challenge of prudently assessing and controlling exposures and contributing to the social development of the region.

Inhibition of Microbial Growth in English Sole ( Parophrys retulus ) 1

The influence of potassium sorbate on growth of microorganisms in seafood was tested by treating English sole ( Parophrys retulus ) homogenate with 0, 0.1 and 1.0% potassium sorbate. Viable counts during 1.1-C storage revealed that 0.1% potassium sorbate delayed the onset of logarithmic growth of bacteria for 1 day compared to no delay for the untreated control. The generation time of 1.7 days and a maximum growth level of 10⁹ cells per g were unchanged by the presence of 0.1% potassium sorbate. The 1.0% sorbate treatment extended the lag period to 6 days. The generation time was increased to 2.1 days and the maximum level of growth reached was 10⁷ cells per g on the 14th day. Tests of the microbial flora of the fish revealed that Pseudomonas spp., which comprised 17.1 %of the total at 0 day, increased to 96.0% of the microbial population in 14 days at 1.1 C for the untreated sample. During the same period the Pseudomonas population reached 100% for the 0.1% sorbate-treated sample, and to 98.2% for the 1.0% sorbate-treated sample. Potassium sorbate at the concentrations employed, therefore, did not seem to alter the typical microbial spoilage pattern.

Zinc-deficiency and activities of urea cycle-related enzymes in rats

In contrast to previous reports, an increase in glutamate dehydrogenase activity and no change in arginase activity were observed in rats fed a zinc-deficient diet for 15 weeks. The discrepancies could be due to a difference in degree and duration of zinc-deficiency.

Polypurine DNAs and RNAs form secondary structures which may be tetra-stranded

Polypurine DNAs and RNAs containing at least 33% guanine form a stable secondary structure at neutral pH and moderate ionic strengths. The tm's of the polymers increase with increasing guanine content. To eliminate possible structures three novel polymers, d(Gn2A)n, d(Gm6A)n and d(IA)n, as well as the random copolymer rr(G,A)n were were studied. Both d(Gn2A)n and d(IA)n can form a secondary structure whereas d(Gm6A)n and r(G,A)n cannot. Model building suggested two possible structures, one a duplex and the other a tetra-stranded polymer. The latter is considered to be the more likely, since previous X-ray diffraction studies have shown that rGn and rIn are tetra-stranded. Circular dichroism spectra are also consistent with such an interpretation.

Synthesis of HLA antigens from membrane-associated messenger RNA

Proteins encoded by genes in the human major histocompatibility region, HLA, are present on the plasma membranes in the cells of most tissues. We have isolated messenger RNA (mRNA) from lymphoblastoid cells and studied its templating activity for HLA polypeptides by using an mRNA-dependent cell-free translation system and immunorecipitation with specific antisera. We estimate the sizes of the mRNA to be 1,700, 1,300, and 900 nucleotides for HLA-A, -B, and -C (HLA-ABC), HLA-DR, and beta 2-microglobulin, respectively. These sizes are consistent with our inability to detect larger polypeptide precursor for more than one HLA-ABC or HLA-DR antigen. Subcellular fractionation into cytosol and membrane fractions indicated that mRNA for the HLA-ABC and HLA-ABC and HLA-DR polypeptides was found predominantly in the membrane fraction. The beta 2-microglobulin mRNA appeared to be divided into roughly equal portions between both fractions. Nevertheless, we believe that in the cell, beta 2-microglobulin is synthesized in the rough endoplasmic reticulum, and that, because the protein is relatively small, the mRNA is released from the polyribosomes during the isolation procedure. We conclude that the properties of the HLA region and the beta 2-microglobulin mRNA are consistent with current models for the synthesis and membrane insertion of eukaryotic cell surface proteins. Our findings do not suggest the existence of multigenic precursor polypeptides for HLA antigens in contrast to those for several viral membrane glycoproteins.

Digital image enhancement and noise filtering by use of local statistics

Computational techniques involving contrast enhancement and noise filtering on two-dimensional image arrays are developed based on their local mean and variance. These algorithms are nonrecursive and do not require the use of any kind of transform. They share the same characteristics in that each pixel is processed independently. Consequently, this approach has an obvious advantage when used in real-time digital image processing applications and where a parallel processor can be used. For both the additive and multiplicative cases, the a priori mean and variance of each pixel is derived from its local mean and variance. Then, the minimum mean-square error estimator in its simplest form is applied to obtain the noise filtering algorithms. For multiplicative noise a statistical optimal linear approximation is made. Experimental results show that such an assumption yields a very effective filtering algorithm. Examples on images containing 256 × 256 pixels are given. Results show that in most cases the techniques developed in this paper are readily adaptable to real-time image processing.

A review of the health effects of cadmium

A review of the health effects of cadmium is presented. Overexposure to cadmium produces numerous acute and chronic effects. Cases of acute poisoning resemble metal-fume poisoning. The first and most distinctive indication of chronic effects is renal tubular dysfunction characterized by proteinuria. Other chronic effects include liver damage, emphysema, osteomalacia, neurological impairment, testicular, pancreatic, and adrenal damage, and anemia. Tumorigenic effects have been observed in animals, and excessive prostatic and lung cancer has been observed in worker studies. In vitro and in vivo mutagenic effects have been noted. Cadmium has been shown to cause hypertension in animals; however, it is unclear whether it is capable of causing similar effects in exposed human populations. Normal urinary excretion is less than 2 micrograms/day and correlates with exposure. Normal blood concentration is below 10 ng/gm of whole blood, and although levels are elevated in exposed groups, there is no apparent direct correlation. Hair values correlate well with exposure. Occupational and environmental standards are discussed.

Review: ethidium fluorescence assays. Part 1. Physicochemical studies

DNA and RNA can be assayed rapidly and very sensitively by exploiting the enhanced fluorescence of ethidium intercalated into duplex regions. By assaying at different pHs and introducing a heating/cooling cycle, a great many physicochemical aspects of DNA and RNA can be studied avoiding the use of radiolabels, and often giving information not otherwise readily obtainable. Studies are described on duplex DNA which involve measurement of extinction coefficients, cross-linking by chemicals, Cot curve analysis as well as estimation of drug-DNA binding constants. The assays can be adapted to investigate multi-stranded nucleic acid structures. The use of covalently closed circular DNA also allows rapid and extremely sensitive measurements of nicking caused by irradiation or drugs.

Review: ethidium fluorescence assay. Part II. Enzymatic studies and DNA-protein interactions

Almost all DNA and RNA metabolizing enzymes can be assayed rapidly and very sensitively by exploiting the enhanced fluorescence of ethidium intercalated into duplex DNA or RNA. Denatured DNA and natural RNAs contain duplex regions due to intramolecular hydrogen-bonding and can also be sensitively measured. Where the product is truly single-stranded (e.g. dTn) it can be assayed by adding the appropriate complementary strand (e.g. dAn or rAn). Some of the assays described provide information not readily obtained by other assay procedures. Among the enzymes readily assayed are DNA and RNA polymerases, terminal deoxynucleotidyl transferases, nucleases of all varieties (e.g. single-strand specific, endonucleases including for example AP endonucleases, exonucleases, RNase H, etc.), ligases, topoisomerases including gyrases, and indirectly enzymes such as proteases and superoxide dismutase. DNA binding proteins such as histones and helix destablizing proteins can also be quantitatively assayed.

Human epidermal cell cultures: growth and differentiation in the absence of differentiation in the absence of dermal components or medium supplements

Human epidermal cells grew and differentiated in vitro, provided that the pH of the culture medium was at 5.6-5.8, the seeding density was optimal (approximately 2.5 x 10(5) cells per cm2), and the incubation temperature was maintained at 35-37 degrees C. Under these conditions, epidermal cells from many different skin locations grew to confluency within 15-20 days and formed multi-layered sheets whose differentiated structure resembled that of the full depth of skin epidermis. Cell proliferation and differentiation did not require a feeder layer, a collagen substrate, a high concentration of fetal bovine serum, or added hormones. The sheets of differentiated epidermal cells could be dissociated from the plastic surfaces of the tissue culture flasks. The use of such cultured cells for wound dressing is proposed.

Lymph capillary pressure of rat intestinal villi during fluid absorption

A newly developed intestinal preparation is described for determining lymph capillary pressure (PL) in the villi in vivo and in vitro. Determination of PL provided an estimate of tissue fluid pressure in the villi. PL was related to the fluid absorption rate and increased by lymphatic obstruction. During fluid absorption from isotonic mucosal fluid, PL was 1.4 +/- 0.5 or 1.1 +/- 0.4 cmH2O determined in vivo or in vitro, respectively. Both pressures were essentially in the same range as that (0.7 +/- 0.3--1.3 +/- 0.5 cmH2O) in which the mucosal fluid was isotonic Na2SO4 solution or Na-free solutions from which little fluid absorption occurred. This range of pressures may be taken as the normal tissue fluid pressure in the villi. At a high rate of fluid absorption from hypotonic mucosal fluid, PL increased to 5.2 +/- 1.4 cmH2O and tissue fluid pressure was also similarly increased. It is concluded that the fluid absorptive process by the epithelium could not develop an appreciable hydrostatic pressure in the villus tissue space or in the lymphatics.

Complexes formed by (pyrimidine)n . (purine)n DNAs on lowering the pH are three-stranded

(Pyrimidine)n . (purine)n DNAs of repeating sequences form a distinctive complex on lowering the pH below 6. Previously this complex was thought to be tetra-stranded. The present work is inconsistent with this view, and four lines of evidence show that the complex consists of a triplex together with a poly d(purine) possessing secondary structure. Formula: (see text). (a) S1 nuclease digestion leads to degradation of 50% of the poly d(purine) content of the pH 5-induced complex. (b) Buoyant density studies demonstrate that there is no interaction between the triplex and added free poly d(purine) and also that the complex formed from duplex DNA contained poly d(purine) which is free to form a triplex on addition of an appropriate poly d(pyrimidine) in the correct stoichiometry. (c) The hyperchromic shifts of the triplex and poly d(purine), upon melting, are mutually independent. (d) The circular dichroism spectrum of the complex is simply the weighted average of a triplex together with a free poly d(purine). The triplexes have tm's approximately 20 degrees higher than the corresponding duplexes under comparable conditions and they are extremely resistant to various deoxyribonucleases; properties which may prove useful for their isolation from natural sources.

Transformation of nuclear morphology during cellular maturation

Using in vivo labeling of mouse leukocytes with tritiated thymidine, cells in the neutrophilic series were studied to determine the change in their nuclear shape as a function of maturation level. Several morphologic shape parameters including perimeter and bending energy were used to quantify the distribution of the nuclear morphology in a given age cohort. The change in these distributions as a function of calender age level was determined. The two parameters named above were used to test the possibility of inferring the age from the quantitative morphology.

Bis-intercalative binding to DNA of novel bis(10-methyl)acridinium chlorides and its dependence on chain length of linker

The synthesis of a series of novel bis(10-methyl)acridinium compounds (both unsubstituted and the 6-chloro-2-methoxy substituted) linked by methylene bridges of lengths from (CH2)4 to (CH2)12 and in one case by spermine is described. Their ability to bind to duplex DNA was compared by their relative inhibition of E. coli DNA polymerase catalyzed DNA synthesis. It was determined that they function as DNA template inhibitors and do not affect the DNA polymerase directly. Their ability to function as bis-intercalators was assessed by a novel and convenient topoisomerase fluorescent assay. It was concluded that whereas the (CH2)4-linked compounds act only as monofunctional intercalators because of steric constraints the (CH2)6-, (CH2)8-, and (CH2)10-linked substituted bisacridinium compounds, as well as the (CH2)10- and (CH2)12- unsubstituted analogues, function as bis-intercalators with DNA.

Atmospheric scattering of middle uv radiation from an internal source

A Monte Carlo model has been developed which simulates the multiple-scattering of middle-uv radiation in the lower atmosphere. The source of radiation is assumed to be monochromatic and located at a point. The physical effects taken into account in the model are Rayleigh and Mie scattering, pure absorption by particulates and trace atmospheric gases, and ground albedo. The model output consists of the multiply scattered radiance as a function of look-angle of a detector located within the atmosphere. Several examples are discussed, and comparisons are made with direct-source and single-scattered contributions to the signal received by the detector.

Antibiotic resistance patterns of gram-negative bacteria isolated from environmental sources

A total of 2,445 gram-negative bacteria belonging to fecal coliform, Pseudomonas, Moraxella, Acinetobacter, and Flavobacterium-Cytophaga groups were isolated from the rivers and bay of Tillamook, Oregon, and their resistances to chloramphenicol (25 microgram/ml), streptomycin (10 microgram/ml), ampicillin (10 microgram/ml), tetracycline (25 microgram/ml), chlortetracycline (25 microgram/ml), oxytetracycline (25 microgram/ml), neomycin (50 microgram/ml), nitrofurazone (12.5 microgram/ml), nalidixic acid (25 microgram/ml), kanamycin (25 microgram/ml), and penicillin G (10 IU/ml) were determined. Among fecal coliforms the bay isolates showed greater resistance to antibiotics than those from tributaries or surface runoff. No such well-defined difference was found among other bacterial groups. The antibiotic resistance patterns of gram-negative bacteria from different sources correlated well, perhaps indicating their common origin. The antibiotic resistance patterns of gram-negative bacteria of different general also correlated well, perhaps indicating that bacteria which share a common environment also share a common mode for developing antibiotic resistance.

A rapid method for the measurement of the unwinding angle of intercalating agents and the superhelix density of circular DNAs

By incubating covalently-closed circular DNA in the presence of calf thymus topoisomerase and unwinding ligands (intercalating drugs and proteins) DNAs of different superhelix density can be produced. These changes in superhelix density can be monitored by an ethidium fluorescence assay, since the level of ethidium binding varies with the superhelix density of a DNA. Thus the equivalence point, in a titration between an unwinding ligand and a supercoiled DNA, can be found. This forms the basis for an extremely rapid method for measuring unwinding angles and superhelix densities. Results are presented which agree well with those reported by previous authors using different techniques. The present method compares very favourably with others when evaluated in terms of rapidity, cost of materials, cost of equipment, accuracy and also applicability.

Bifunctional intercalation and sequence specificity in the binding of quinomycin and triostin antibiotics to deoxyribonucleic acid

Quinomycin C, triostin A and triostin C are peptide antibiotics of the quinoxaline family, of which echinomycin (quinomycin A) is also a member. They all remove and reverse the supercoiling of closed circular duplex DNA from bacteriophage PM2 in the fashion characteristic of intercalating drugs, and the unwinding angle at I 0.01 is, in all cases, almost twice that of ethidium. Thus, as with echinomycin, they can be characterized as bifunctional intercalating agents. For the triostins this conclusion has been confirmed by measurements of changes in the viscosity of sonicated rod-like DNA fragments; the helix extension was found to be almost double that expected for a simple monofunctional intercalation process. For triostin A, further evidence for bifunctionality was derived from the cross-over point of binding isotherms to nicked circular and closed circular bacteriophage-PM2DNA. Binding curves for the interaction of quinomycin C and triostin A with a variety of synthetic and naturally occurring nucleic acids were determined by solvent-partition analysis, but triostin C was too insoluble in aqueous solution to make this method applicable. For quinomycin C the highest binding constant was found with Micrococcus lysodeikticus DNA, and its pattern of specificity among natural DNA species was broadly similar to that of echinomycin, although the binding constants were 2--6 times as large. For triostin A the highest binding constant was again found for M. lysodeikticus DNA, but the specificity pattern was quite different from that of the quinomycins. In particular, triostin A bound better to poly(dA-dT) than to the poly(dG-dC) whereas this order was reversed for quinomycin C. There was also evidence that the binding to poly(dA-dT) might be co-operative in nature. No significant interaction could be detected with poly(dA).poly(dT) or with RNA from Escherichia coli. Poly(dG).poly(dC) gave variable results, depending on the source of the polymer. The different patterns of specificity displayed by the quinomycins and triostins are tentatively ascribed to differences in their conformations in solution.

Interaction between synthetic analogues of quinoxaline antibiotics and nucleic acids. Changes in mechanism and specificity related to structural alterations

The interaction with DNA of six chemically synthesized derivatives of the quinoxaline antibiotics was investigated. Five of the compounds bound only weakly to DNA or not at all; for these substances spectrophotometric measurements, sedimentation studies with closed circular duplex bacteriophage-PM2 DNA and thermal-denaturation profiles were used to determine limits fot the binding constants. No interaction could be detected with two products of degradation of echinomycin (quinomycin A), one of which, echinomycinic acid dimethyl ester, had the lactone linkages opened, whereas the other retained an intact octapeptide ring but had a broken cross-bridge. The other compounds studied were des-N-tetramethyl-triostin A ('TANDEM') and its derivatives. A derivative of 'TANDEM' IN WHICH benzyloxycarbonyl moieties replace both quinoxaline chromophores had binding constants to nucelic acids in the range 10(2)--10(3)-1, whereas no interaction could be detected for a benzyloxycarbonyl derivative that, in addition, had the cross-bridge broken. The derivative of 'TANDEM' with L-serine in place of D-serine in both positions showed no detectable interaction with Clostridium perfringens DNA, whereas the binding constant to poly(dA-dT) was approx 2 X 10(3)M-1. 'TANDEM' itself bound strongly to DNA, and the bathochromic and hypochromic shifts in its u.v.-absorption spectrum in the presence of DNA were similar to those seen with echinomycin. From the effect on the sedimentation coefficient of closed circular duplex bacteriophage-PM2 DNA the mechanism of binding was shown to involve bifunctional intercalation, typical of the naturally occurring quinoxaline antibiotics. Solvent-partition analysis was used to determine binding constants for the interaction between 'TANDEM' and a variety of natural and synthetic DNA species. The pattern of specificity thus revealed differed markedly from that previously found with the naturally occurring quinoxaline antibiotics. Most striking was the evident large preference for (A + T)-rich DNA species, in complete contrast with echinomycin and triostin A. The highest binding constant was found for poly(dA-dT), the interaction with which appeared highly co-operative in character. The conformations adopted by those quinoxaline compounds that bind strongly to DNA were examined withe aid of molecular models on the basis of results derived from n.m.r. and computer studies. It appears that the observed patterns of base-sequence specificity are determined, at least in part, by the structure and conformation of the sulphur-containing cross-bridge.

The topological trapping of circular DNAs on agarose: unexpected restrictions on DNA rotation

DNA linked to an insoluble matrix has many potential applications. In some cases, it is highly desirable that the DNA be chemically unaltered, and for this reason, we have developed methods for topologically trapping circular DNAs on agarose. Open circular (oc) DNA containing at least one nick is readily trapped on agarose which has been heated or dissolved in sodium perchlorate to destroy secondary structure and then gelled by cooling or dialysis respectively. On the other hand, covalently closed circular (ccc) DNA of superhelix density −0.12 (PM2 DNA) is only poorly trapped unless first relaxed by topoisomerases or with the appropriate addition of an intercalating drug. When the oc DNA – agarose was used in a procedure for rapidly obtaining binding constants of drugs to DNA, the binding constant of ethidium was found to be considerably less than that expected. On addition of calf thymus topoisomerase to the binding-assay mixture, the ethidium-binding constant increased to the expected value. Thus, although free oc DNA is topologically unrestricted, oc DNA trapped in agarose must be rotationally constrained such that addition of ethidium introduced supercoils. The nature of these constraints is discussed with respect to the known structure of agarose bihelices.

Transferred pulmonary surfactant film: chemical analysis and contact angle study

The Langmuir dip plate transfer technique was adapted to isolate the interfacial film formed at the surface of lung wash. The chemical analysis of the film showed that the weight ratio of lipid to protein of this surfactant film and its content of surface active substances were higher than those of lung wash. It was found that the wettability of the surfactant film could be simulated by a Dipalmitoyl lecithin and albumin film. When the surfactant film was transferred at condensed state (one of low air-lung-wash surface tension), we found the film exhibited a low critical surface tension which indicates the dominance of the lipid in the outer most layer of the film. On the other hand, insignificant amount of lipid was found in the film transferred at expanded state (one of high surface tension) and its surface behavior was shown to be similar to that of a protein film.

Microbiological characteristics of Pacific shrimp (Pandalus jordani)

Microorganisms associated with Pacific shrimp (Pandalus jordani) were isolated and identified. Those on the iced raw shrimp, which yielded an average count of 1.6 x 10(6), were predominantly Moraxella, Pseudomonas, Acinetobacter, Arthrobacter, and Flavobacterium-Cytophaga spp. The blanching and peeling reduced the microbial level to 3.3 x 10(4) and also selectively eliminated Moraxella spp. The microbial flora changed after each processing sequence, and the heat sensitivity and growth characteristics of the representative microbial groups suggested that the presence of Arthrobacter and Acinetobacter spp. in peeled shrimp may indicate inadequate cleaning of raw shrimp or a shorter blanching time. The presence of Moraxella and Flavobacterium-Cytophaga spp. would indicate the degree of secondary contamination, and the presence of Pseudomonas spp. would indicate the shelf-age of the processed shrimp.

Epithelial cell extrusion during fluid transport in canine small intestine

Epithelial cell extrusion during fluid transport was studied under both in vitro and in vivo conditions. The rate of cell extrusion from the villus tips in vitro increased by about onefold in the villi with obstruction of lymph flow associated with the increase of lymph and tissue fluid pressure. When lymph pressure in the jejunal and ileal villi was increased to 6.4 +/- .2 and 12.3 +/- .5 mmHg, respectively, by injection of Ringer solution into the central lacteals, fluid leaked out of the villi and a shedding of epithelium occurred. Vigorous villus spasmodic contraction induced by cocaine or atropine also caused a shedding of epithelium. Cells always appeared in the lumen of intestine in vivo either during fluid absorption or secretion. A copious secretion of fluid, increase of cell loss, and congestion of blood in the villi occurred by the action of cholera toxin, MgSO4, and choline chloride. The rate of cell loss was highest during fluid secretion induced by an elevation of tissue fluid pressure such as at high venous pressure or during intra-arterial histamine infusion. It is thus concluded that elevated tissue fluid pressure is involved in epithelial cell extrusion during fluid transport.

Effect of histamine on intestinal fluid secretion in the dog

Intra-arterial infusion of histamine into the small intestine caused about a onefold increase of blood flow, edema of the intestinal tissues and mesentery, and produced a copious secretion of fluid. The jejunal secretions had an ionic composition similar to that of plasma, whereas ileal secretions contained high concentrations of HCO3 with relative low concentrations of Cl. The secretions contained protein (1.5 +/- .2 g/100 ml, range 0.5-2.4) with a similar electrophoretic pattern of plasma protein. When lissamine green was present in the blood, it also appeared in the secretion to a considerable concentration. It is inferred from these findings that a major mechanism of fluid secretion by the action of histamine involves a filtration process across the mucosal epithelium by the incrreased tissue fluid pressure due to extensive capillary leak.

A solvent-partition method for measuring the binding of drugs to DNA. Application to the quinoxaline antibiotics echinomycin and triostin A

The development of a novel solvent-partition method for measuring the interaction between nucleic acids and drugs of limited water solubility is described. Factors relevant to the choice of a suitable water-immiscible solvent are summarised. i-Amyl acetate was selected for studying the binding of echinomycin and triostin A to DNA. Details of the experimental determination of extinction and partition coefficients are given; in the i-amyl acetate/buffer system employed for most experiments, the partition coefficients for echinomycin and triostin A were 111 +/- 4 and 943 +/- 23, respectively. Equilibration of echinomycin between the organic and aqueous phases was 90% complete within a few minutes, and a period of 2 h shaking was found satisfactory to ensure full attainment of equilibrium. Representative results are presented showing specific binding of the quinoxaline antibiotics to DNA, strong preference for double-helical as opposed to heat-denatured or single-stranded DNA, and restricted uptake by closed circular duplex PM2 DNA. The method is potentially applicable, with appropriate modifications, to the study of interactions between other ligands and DNA.

Microbiological characteristics of Dungeness crab (Cancer magister)

Aerobic, heterotropic microorganisms of Dungeness crab (Cancer magister) were isolated from raw crab, cooked crab, crab meats obtained during commercial processing, and from retail crab meat samples. Each microbial isolate was then identified to the genus level employing the revised replica plating procedure. Microbial groups most commonly isolated from crab meat were, in the order of predominance, Moraxella, Pseudomonas, Acinetobacter, Arthrobacter, Micrococcus, Flavobacterium-Cytophaga, and Bacillus sp. Proteus, Staphylococcus, yeasts, Vibrio, and Lactobacillus sp. were found less frequetly in some samples. Distribution patterns of microbial flora in crab meat revealed the presence of three classes of microorganisms. Microorganisms that originated from the raw crab and gained predominance by growth during refrigerated storage were Moraxella, Pseudomonas, Acinetobacter, and Flavobacterium-Cytophaga sp. Those that originated from the crab but did not grow in meat were Arthrobacter and Bacillus sp. Micrococcus, Staphylococcus, and Proteus sp. were introduced during processing, but they did not grow in the refrigerated crab meat.

Effects of bile and gastrointestinal secretions on the infectivity of Newcastle disease virus

Bile aspirated from chicken gall bladders was found to contain substances neutralizing Newcastle disease virus (NDV). Nonspecific factors were present in the bile, probably the bile acids, which caused a reduction in the infectivity of the virus. Specific anti-NDV activity was found in the bile of birds that had been vaccinated with a lentogenic strain, Ulster, and challenged with a velogenic, viscerotropic strain, California 1083. Immunoglobulins were also found in these secretions and demonstrated to include the immunoglobulin A class as well as immunoglobulin G. Variability in the neutralizing capacity of bile was found with two different plaque clones of strain 1083, indicating antigenic heterogeneity in the viral population. No difference was found between bile from uninfected birds and the bile from NDV-immune birds in their activities against influenza strain Turkey Ontario 7732, whereas activity existed against a non-viscerotropic strain of NDV, Texas GB. These findings suggest that the specific activity of the secretions was most probably due to the presence of secretory antibody. The importance of the antiviral substances present in the alimentary tract was discussed with respect to the protection of the chicken against the viscerotropic pathotype of NDV.

Dispersion of indicator measured from microvessels of cat mesentery

The indicator-dilution method was used to investigate blood flow in the microvascular network of the mesenteric membrane of the cat by replacing the normal blood flow into the mesenteric artery with a dextran-saline solution for a finite period of time. The dilution of the dextran-saline bolus as it flowed downstream was measured in a selected arteriole and its adjacent venule with a microphotometric system. Based on an in vitro calibration study done on glass capillary tubes, the measured optical density was converted to the hematocrit. The dilution curve for a finite injection and for a step injection, the mean transit time (MTT), and the appearance time for the arteriole and the venule were computed. The dispersion found in the arterial system, a network of diverging branches, was reasonably well simulated by the dispersion in a parabolic flow system. However, the dispersion found in the venules, where the irregular capillary blood flow converges, was considerably skewed from that in a parabolic system. A wide distribution of MTT was found for the arterioles and the venules, and there was considerable overlap in the MTT distribution for these two groups. This finding cannot be simulated by a network with a parallel arrangement. The difference in MTT for pairs of arterioles and venules was distributed over a narrow range, probably indicating shunt flow in the mesenteric microvascular network.

Compound inhibitory to Clostridium botulinum type E produced by a Moraxella species

A Moraxella strain, A-43, produced a compound inhibitory to the outgrowth of Clostridium botulinum type E spores. The inhibitor could be produced in various laboratory media, and the outgrowth of germinated spores was inhibited by a 1/10th dilution of the A-43 spent medium. Germination was not affected. Molecular weight of the inhibitor was estimated at 800 to 1,000. The inhibitor was dialyzable and could be concentrated by lyophilization. It was stable at 37, 25, and 5 C, but was 70% inactivated when heated at 65 C for 10 min. The inhibitor was not volatile and could not be vacuum-distilled at 40 C. Solutions of acids with pH values below 2.0 destroyed the activity. The A-43 inhibitor appears to be similar, in molecular weight and inhibition characteristics, to tylosin.