Uronide Deposition Rates in the Primary Root of Zea mays

The spatial distribution of the rate of deposition of uronic acids in the elongation zone of Zea mays L. Crow WF9 × Mo 17 was determined using the continuity equation with experimentally determined values for uronide density and growth velocity. In spatial terms, the uronide deposition rate has a maximum of 0.4 micrograms per millimeter per hour at s = 3.5 mm (i.e., at the location 3.5 mm from the root tip) and decreases to 0.1 mg mm⁻¹ h⁻¹ by s = 10 mm. In terms of a material tissue element, a tissue segment located initially from s = 2.0 to s = 2.1 mm has 0.14 μg of uronic acids and increases in both length and uronic acid content until it is 0.9 mm long and has 0.7 μg of uronide when its center is at s = 10 mm. Simulations of radioactive labeling experiments show that 15 min is the appropriate time scale for pulse determinations of deposition rate profiles in a rapidly growing corn root.     

The identification of trihydroxyeicosatrienoic acids as products from the incubation of arachidonic acid with washed blood platelets

Arachidonic acid is converted by washed platelets from man, horse and dog into a mixture of 8, 9, 12-trihydroxyeicosa-5, 10, 14-trienoic acid and 8, 11, 12-trihydroxyeicosa-5, 9, 14-trienoic acid (termed 8, 9, 12-THETA and 8, 11, 12-THETA respectively and THETA collectively). Gas chromatographic — mass spectrometric evidence of structure is discussed.     

Antigen-specific. I region-restricted interactions in vitro between tumor cell lines and T cell hybridomas

A series of H-2d B cell tumor lines and one monocytic tumor cell line were shown to be capable of I region-restricted antigen presentation to I-A-d- and I-Ed- restricted, antigen-specific cloned T cell hybridomas. For the most part, antigen presentation correlated with the present of Ia antigens on the presenting cells, although in a few interesting cases Ia-expression lines failed to present antigen. These T cell hybridomas, together with the B cell and to monocyte tumor cell lines, offer a unique set of tools to study the phenomenon of I region-restricted antigen presentation.     

Maltosylamine, a specific inhibitor of beta-amylase.

β-Maltosylamine has been synthesized for the first time. It is an effective specific inhibitor of sweet potato β-amylase. This result extends the observation that 1-aminoglycosides are specific inhibitors of exoglycosidases which hydrolyze the corresponding glycose and also demonstrates that an enzyme acting with inversion, as well as those acting with retention of anomeric configuration, can be inhibited by glycosylamines. Maltosylamine, which acts as a reversible inhibitor of β-amylase, appears to be directed to the active site since it protects the essential sulfhydryl group of the enzyme from inactivation by N-ethylmaleimide.     

Mutagens in the feces of 3 South-African populations at different levels of risk for colon cancer.

The incidence of mutagens in the feces of 3 South-African populations at different risk levels for colon cancer has been determined. Lyophilized fecal samples were extracted with ether and the mutagenicity of the extracts determined using the Salmonella/mammalian microsome mutagenicity test. 19% of the samples from urban white South-Africans, a population at a high risk for colon cancer, were mutagenic using Salmonella typhimurium strain TA100. This incidence was significantly greater (p less than 0.001) than the incidence of mutagen excretion in the low-risk populations of urban blacks (2%) and rural blacks (0%). This pattern was also obtained using Salmonella typhimurium strain TA98. The incidence of mutagen excretion for urban whites was 10%, as compared to 5% and 2% for urban and rural blacks, respectively.     

Sustained swimming speeds and myotomal muscle function in the trout, Salmo gairdneri

Rainbow trout were trained for 3–4 weeks in a flume at swimming speeds of 1, 2 and 3 l s⁻¹. For each experiment growth rates were estimated and by measuring the hypertrophy of red and mosaic skeletal muscle fibres their function was described at particular swimming speeds and compared with earlier experiments on coalfish using the same technique.
Maximum growth, compared with controls in still water, occurred at swimming speeds of 1 l s⁻¹. At this speed the trout mosaic muscle fibres hypertrophied by 40% but the red muscle fibres showed only a 25% hypertrophy. It is suggested that natural swimming speeds are close to 1Ls^−l and the trout mosaic fibres are better adapted for use at this speed in comparison with coalfish white muscle fibres.     

Prospectively randomised trial of proximal gastric vagotomy either with or without pyloroplasty in treatment of uncomplicated duodenal ulcer.

A consecutive series of 100 men with uncomplicated duodenal ulcer was randomly divided into two groups: one group of 52 underwent proximal gastric vagotomy (PGV), the other group (48) underwent PGV with pyloroplasty (PGVP). Preoperative peak acid output (PAOP) was measured in all patients. Those with a higher preoperative PAOP were significantly more likely to develop recurrent ulceration. Three patients developed recurrent ulceration after PGV and seven after PGVP. Dumping was both more common and more severe after PGVP than PGV. An overall satisfactory result was achieved in 92% after PGV and 81% after PGVP. We conclude that combining pyloroplasty with PGV has no appreciable advantages.