Selective breakage of DNA alongside 5-bromodeoxyuridine nucleotide residues by high temperature hydrolysis

The substitution of thymine mucleotides (pT) in oligodeoxynucleotides by bromouracil nucleotides (pBU) changes the properties of the oligonucleotides in two ways: (1) It alters their mobility during DEAE-Cellulose homochromatography1. (2) It substantially enhances their sensitivity to high temperature hydrolysis under mildly alkaline conditions (pH 8.9). The resultant breaks occur adjacent to pBU residues and leave terminal phosphates on the breakage products. With more extreme conditions some loss of terminal phosphates can occur. Heating at 100 degrees for 16 hr at pH 8.9 produces cleavage at about half of the pBU residues with minimal loss of terminal phosphates. The properties described here may explain the thermal sensitivity of bacteria grown in 5BU2 and may have a use in DNA sequencing technology.     

Long-term effects of urinary tract infections. The need for a controlled trial

Two series of children with urinary tract infections are compared: in one the infections were primarily covert, while in the other they were predominantly overt. Grade III reflux occurred only in the overt infection group, and the development or progression of renal clubbing and scarring was much more common in these patients. Now that effective, long-term prophylactic therapy for infection is available, the author urges that controlled trials be established to determine whether or not sterile reflux is harmful and whether or not ureteral reimplantation for reflux is of value.     

Infection of sheep with adult and larval Ostertagia circumcincta: abomasal morphology

The infection of parasite-naive sheep with approximately 15,000 adult Ostertagia circumcincta via abomasal cannulae resulted in marked changes in the structure and function of the abomasum. The functional changes, which have been characterised previously, included elevated abomasal pH and increased serum concentrations of pepsinogen and gastrin. Eight days after the transplant of adult worms, the abomasa of recipient animals were significantly heavier than those of controls (P < 0.001), the thickness of the fundic mucosa was greater (P < 0.01), there were fewer parietal cells (P < 0.01) and increases in the numbers of mitotic figures and mucus-producing cells. Mucous cell hyperplasia was also evident in the fundic mucosae of sheep receiving a trickle infection of infective, third-stage O. circumcincta larvae and was prominent within nodules associated with larval development. In non-nodular mucosa, there was hyperplasia of mucous cells and changes in the distribution of parietal cells. Decreases in the number of parietal cells at the gland base were offset by increases at a mid-gland level, probably due to chronic hypergastrinaemia, so that, overall, total parietal cell number was unaffected. Mucous cell hyperplasia and the diminution of parietal cell number are seen in a diverse range of disease states and may be mediated by host growth factors such as Transforming growth factor-alpha. Alternatively, the cellular and/or the secretory changes in response to the presence of adult worms are mediated by chemicals that are cytotoxic/inhibitory for parietal cells, and released by the parasites themselves.     

Durability of monopolar Teflon-coated electromyographic needles

The results of a two-year study on durability and cause of failure of electromyographic monopolar electrodes are reported. The electrodes were obtained from the regular stock of three different manufacturing sources. Durability is defined on the basis of the number of patients that could be examined before failure. The range was 3 to 110 with the averages 19.7, 33.8, and 62.5 for the three different manufacturers. Common causes of electrode failure included: Teflon retraction, 40.6%; tip dullness or burrs, 34.8%; structural failure of wire or pin, 13.1%; electrical artifacts, 9.7%; and bending of needle shank, 5.7%. Variations in manufactures' tip contour and bevel correlated with tip durability.