An analysis of some sensitizing agents in the pathogenesis of stress-induced gastric erosive disease

Prior surgical implantation of a venous catheter sensitized rats to cold-immobilization stress. Three of six catheterized females succumbed during the stress. The remaining rats fell into two groups in terms of their core temperature at the end of the stress period: Male uncatheterized rats had higher temperatures than rats in the other three groups. No relation was found between catheter patency and magnitude of hypothermia. Degree of gastric disease paralleled the core temperature findings in that the male uncatheterized rats had significantly fewer gastric erosions than the rats in the other three groups. Additionally, a robust effect of gender was found with uncatheterized females showing more hypothermia and more gastric disease than uncatheterized males. A subsequent experiment was conducted to evaluate whether anesthesia or wearing the protective spring was responsible in part for the sensitization seen. Here, the gender difference was less although females consistently averaged lower core temperatures after stress than did males. Despite similar core temperatures after stress, females that were prepared with the protective spring apparatus developed more gastric disease than female controls or similarly treated males. Thus, the additional sensitization exhibited by females in the first experiment may relate to the fact that both catheterization and the taping procedure were sensitizers while only catheterization was a sensitizer for males.     

Factors Influencing Induction of Resistance to Dark Abscission by Malformin

Factors influencing induction of resistance to dark abscissionby malformin on cuttings of Vigna radiata during treatment inlight were examined. When light duration (13.5 W m^–2)increased from 0 to 48 h, the effect of malformin on subsequentdark abscission changed from stimulation only (0 to 4 h), stimulationfollowed by inhibition (8 to 12 h), to inhibition only (24 to48 h). Maximum abscission resistance occurred after 48 h whenirradiance was 6.6 W m^–2. Kinetin treatment in light reducedsubsequent dark abscission by controls but did not reduce abscissionon malformintreated cuttings. Hadacidin had no effect on inductionof abscission resistance by malformin. IAA, hydroxyproline,CaCl₂, sucrose, and NH₄NO₃ were inactive. ABA and ethephon completelyblocked induction of abscission resistance by malformin. Inhibitionof abscission induced by kinetin was also blocked by ABA. Becauseboth puromycin and malformin inhibited dark abscission followingtreatment in light, malformin may induce abscission resistanceby inhibiting protein synthesis or promoting formation of othersubstances which inhibit protein synthesis. Leaf blade removalfrom the distal end of the petioles abolished malformin-inducedabscission resistance. It is suggested that in light malformininduces formation of abscission-inhibiting compounds in leaveswhich are responsible for development of abscission resistance. (Received May 17, 1983; Accepted November 8, 1983)     

Estimating equivalent dose functions for alternative routes of exposure

Humans are exposed to some compounds by more than one route. This occurs incidentally with environmental pollutants, and intentionally in the medical use of drugs. Dose-response functions given estimates of the received dose as a function of dose applied (and typically time) may be available for each route separately. Under mild regularity conditions, the two functions can be combined (numerically or analytically) to provide a function giving dose pairs for the alternative routes which are equivalent in terms of received dose. With Gaussian errors, the estimation is maximum likelihood and, more generally, asymptotically unbiased and least squares. The same approach may be applied to characteristics such as the maximum response level and area under the curve. Confidence limits are available for the difference between responses. Finally, other applications are discussed. The methods can also be used to compare compounds or species.     

Effects of endurance exercise on metabolic water production and plasma volume

Six endurance-trained and heat-acclimatized adult males ran for 1 h (or until exhaustion) at room temperature (23.8 degrees C) on three occasions. The work loads approximated 37, 56, and 74% of the subjects' aerobic capacities. Venous blood samples were drawn, and urine was collected before and immediately after each exercise bout. Metabolic cost was partitioned by energy substrate, and metabolic water production was quantified from urinary nitrogen, oxygen, and carbon dioxide production. Total body water loss was recorded as the decrease in body weight during the exercise. All subjects completed 1 h of exercise at the two lower exercise intensities but, due to exhaustion, averaged only 35.5 min at the highest work intensity. There were no significant changes in plasma volume after the exercise bouts. Metabolic water production increased with increasing work intensity as did the fraction of total caloric expenditure derived from carbohydrate metabolism. Plasma protein content significantly increased at all levels of exercise intensity. Metabolic water production alone would be of minimal help in plasma volume maintenance and thermoregulation during endurance exercise.     

Cobalt(III)-promoted hydrolysis of atp

The rate of phosphate hydrolysis of ATP in the substitution-inert complex Co(NH₃)₄ATP-has been examined in the presence and absence of [Co(cyclen)(H₂O)₂]³⁺. The rate of hydrolysis of Co(NH₃)₄ATP- in the absence of [Co(cyclen)(H₂O)₂]³⁺ is essentially independent of pH in the range 6.0 to 9.0, and the rate constant is 2.6 × 10^?5 sec ^?1 at pH 9.0, 40°C, and 1.0 M ionic strength Rate constants for the hydrolysis of Co(NH₃)₄ATP- in the presence of [Co(cyclen)(H₂O)₂]³⁺ are sharply dependent upon pH in the same range. The rate constants at pH 8.0, 8.6, and 9.0 are 8, 63, and 95 times larger than the rate constant at pH 7.0. At pH 9 the rate constant is 1.2 × 10^?3 sec^?1 for 16 mM Co(NH₃)₄ATP- in the presence of 10 mM [Co(cyclen)(H₂O)₂]³⁺. The proposed mechanism for hydrolysis involves the coordination of a phosphate group of Co(NH₃)₄ATP- by [Co(cyclen)(H₂O)₂]³⁺ to form a dinuclear species, followed by internal attack of coordinated hydroxide on the phosphate chain.     

Trace-element analysis of human teeth and bone by proton-induced X-ray emission

The objective of our study is to correlate Fe, Cu, Zn, Pb, Br, Sr, and Mo concentrations in human teeth crown, root, and bone. The samples, teeth from a lower jaw bone and the lower jaw bone itself, were obtained from a 97-yr-old female cadaver. Two hundred milligrams of crown and root of the teeth, and lower jaw bones were fixed to a Kapton film and irradiated with a 3.8-MeV external proton beam from an 8-MV FN Tandem Van de Graaff Accelerator. TheF-test was used to analyze the difference between crown, root, and bone. It resulted in the following: For Fe, Zn, and Pb, the comparison showed significant differences among the three sample populations of tooth crown, root, and bone; for Cu, Br, Sr, and Mo, the comparison showed no significant differences among all three sample populations. Several elements in the samples were highly interrelated.     

Usefulness of erythrocyte ferritin analysis in hereditary hemochromatosis.

A study was carried out to determine the usefulness of erythrocyte ferritin analysis in identifying homozygotes and heterozygotes in families affected with hereditary hemochromatosis, an autosomal recessive disorder. To select the subjects the genotypes of 60 people from 26 affected families were determined by HLA-A and HLA-B haplotyping. In addition, data for 12 homozygotes for whom erythrocyte ferritin values were available from the literature were included. Likelihood analysis was used to evaluate the diagnostic value of erythrocyte ferritin analysis alone and in combination with serum ferritin testing. An erythrocyte ferritin value of 150 ag/cell or higher combined with a serum ferritin level above the 90th percentile indicated homozygosity, whereas a value of less than 150 ag/cell and a serum ferritin level at or below the 90th percentile indicated that homozygosity could be ruled out with a high degree of confidence. The probability of heterozygosity rose to 92% when the erythrocyte ferritin value was between 29 and 149 ag/cell and to 98% when this result was combined with a serum ferritin level at or below the 90th percentile. Erythrocyte ferritin analysis in combination with serum ferritin testing is useful for identifying homozygotes and a proportion of heterozygotes in families affected with hemochromatosis.     

Quantification of 5- and 15-HPETE''s by direct chemical ionization mass spectrometry

This report describes the application of direct chemical ionization mass spectrometry (DCIMS) to the identification and quantification of 5- and 15-HPETEs. A unique feature of the method is use of a polyimide-coated fused silica fiber that allows vaporization of the hydroperoxides, with very low excess energy, into the plume of the chemical ionization reagent gas plasma. Mass spectra are obtained that allow identification of the nonreduced and nonderivatized free acid forms of 5- and 15-HPETE as well as their quantification from 1 microgram to 100 picograms.     

Human bronchial epithelial cells with integrated SV40 virus T antigen genes retain the ability to undergo squamous differentiation

Human bronchial epithelial cells transformed by either DNA virus infection (SV40 or Adenovirus 12-SV40 hybrid virus) or transfection with the SV40 large T antigen gene were studied for their ability to undergo squamous differentiation when exposed to 12-O-tetradecanoylphorbol-13 acetate (TPA), transforming growth factor-beta 1 (TGF-beta 1), or fetal bovine serum (FBS), agents that induce the squamous differentiation of normal human bronchial epithelial cells. Squamous differentiation occurred in all ten T-antigen-positive cell cultures when they were exposed to either FBS or TGF-beta 1, but none differentiated when exposed to TPA. From one cell line, designated BEAS-2B, two subclones were isolated, one of which was induced to undergo squamous differentiation by FBS, and a second that failed to undergo squamous differentiation and was mitogenically stimulated when exposed to serum. These phenotypically different subclones provide a new in vitro cellular system for delineating the mechanism(s) of human bronchial epithelial cell squamous differentiation in response to FBS or TGF-beta 1.     

Mitotic index and size of symbiotic algae in Caribbean Reef corals

Size and frequency of division were determined for zooxanthellae from nine scleractinian coral species collected in February, 1983 at Discovery Bay, Jamaica, from four depths over a 51 m bathymetric range. Mean diameters of zooxanthellae ranged from 6.4 to 12.6 m. Small zooxanthellae were found in Madracis mirabilis, Eusmilia fastigiata and Dendrogyra cylindrus whereas larger cells were seen in Agaricia agaricites, Porites astreoides, Montastrea cavernosa and Acropora cervicornis. Zooxanthellae division was not phased over a diel cycle. The percentage of zooxanthellae in a paired stage of cytokinesis (mitotic index or MI) was highly variable and ranged from 1.1% to 14.1%. Values measured in E. fastigiata and D. cylindrus were greater than in the other corals. MI was higher in branch tips of A. cervicornis than in branch bases. Daily average MI was negatively correlated with mean cell diameter and for a majority of the coral species increased with habitat depth. MI values were used to estimate specific growth rates and generation times for zooxanthellae in vivo for comparison with other dinoflagellates.