O6-Methylguanine methyltransferase activity is increased in rat tissues by ionising radiation

The effect of whole body ionising radiation from a linear acceleratoron rat tissue O⁶-methylguanine (O⁶-meG) methyl-transferase (MT)activity has been assessed using an assay which measures thetransfer of ³H-radioactivity from ³H-methylated substrate DNAto protein. The maximal effect occurred 2 days after a 1 kraddose, at which time activity in liver extracts was increased5-fold in two different rat strains. Activity in lung and kidneywas increased 4- and 2-fold, respectively. Similar degrees ofenhancement were found in these three tissues using an h.p.l.c.method for measuring MT activity. The increase in activity wasreflected in an increased capacity to repair O⁶-meG producedin liver DNA by administration of [¹⁴C]dimethylnitrosamine (DMN):this effect was dose dependent, being detectable after 30 radsand maximal after 600 rads. Incorporation of labelled breakdownproducts of the DMN into adenine in DNA increased as the doseradiation increased suggesting an inhibition of DNA synthesis.The implications of these results for the mechanism of enhancingO⁶-meG repair are discussed.     

Histopathology of lung cancer in New Mexico, 1970-72 and 1980-81

In conjunction with a population-based case-control study of lung cancer in New Mexico, the histopathology of cases diagnosed during 1980 and 1981 and during 1970-72 was reviewed. Adequate histologic or cytologic material was obtained for 725 cases, with 308 during 1970-72 and 417 during 1980-81. The light microscopic histologic type was classified on the basis of review by 2 pathologists. No significant differences were found in the histologic-type distributions in Hispanics and non-Hispanic whites. In males, the distributions of histologic types were similar in the two time periods, but in non-Hispanic white women the proportion of adenocarcinoma declined during 1980-81 as the proportion of small cell carcinoma increased. The panel classification was compared with that recorded by the New Mexico Tumor Registry. Overall agreement was 52.1% for 1970-72 and increased to 65.2% for 1980-81. The discrepancies between the two classifications were largest for the categories of large cell undifferentiated carcinoma and "other malignancy."     

A randomised trial of bilateral erector spinae plane block vs. no block for thoracolumbar decompressive spinal surgery

Major spinal surgery causes significant postoperative pain. We tested the efficacy and safety of bilateral erector spinae block on quality of recovery and pain after thoracolumbar decompression. We randomly allocated 60 adults to standard care or erector spinae block. Erector spinae block improved the mean (SD) quality of recovery-15 score at 24 postoperative hours, from 119 (20) to 132 (14), an increase (95%CI) of 13 (4–22), p = 0.0044. Median (IQR [range]) comprehensive complication index was 1 (0–3 [0–5]) in the control group vs. 1 (0–1 [0–4]) after block, p = 0.4. Erector spinae block reduced mean (SD) area under the curve pain during the first 24 postoperative hours: at rest, from 78 (49) to 50 (39), p = 0.018; and on sitting, from 125 (51) to 91 (50), p = 0.009. The cumulative mean (SD) oxycodone consumption to 24 h was 27 (18) mg in the control group and 19 (26) mg after block, p = 0.20. In conclusion, erector spinae block improved recovery and reduced pain for 24 h after thoracolumbar decompression surgery.     

A new interstitial deletion of chromosome No. 4 del(4) (q22::q25)

A female child is described with multiple anomalies including epicanthus, frontal bossing, short sternum, polydactyly, cleft of the larynx, renal cysts, and unusual dermatoglyphics. She died aged 3 months and was found to have a unique de novo deletion of chromosome No. 4 (q22-q25). This case is compared with other long arm deletions of 4q and reference made to assignment of genetic markers to chromosome No. 4.     

Identification of mycobacteria by high-performance liquid chromatography.

Mycolic acids extracted from saponified mycobacterial cells were examined as p-bromophenacyl esters by high-performance liquid chromatography (HPLC). Standard HPLC patterns were developed for species of Mycobacterium by examination of strains from culture collections and other well-characterized isolates. Relative retention times of peaks and peak height comparisons were used to develop a differentiation scheme that was 98% accurate for the species examined. A rapid, cost-effective HPLC method which offers an alternative approach to the identification of mycobacteria is described.     

Regional central serotonin-2 receptor binding and phosphoinositide turnover in rats with 5,7-dihydroxytryptamine lesions

"Denervation supersensitivity" of serotonin (5-HT) receptors has been proposed to explain the behavioral supersensitivity to 5-hydroxytryptophan (5-HTP) which develops after lesions of indoleamine neurons with 5,7-dihydroxytryptamine (5,7-DHT). To examine the possible role of receptor recognition sites and second messenger activity in supersensitivity, we measured regional 5-HT2 receptor ligand binding and 5-HT-stimulated phosphoinositide turnover in adult rats with 5,7-DHT lesions made by intracisternal injection and their saline-treated controls. In [3H]ketanserin binding studies of fresh brain tissue two weeks after 5,7-DHT injection, there were no significant changes in frontal cortex, brainstem, or spinal cord in Bmax, Kd, or nH of 5-HT2 receptors, 5,7-DHT lesions did not affect basal levels of [3H]inositol phosphate (IP) accumulation but significantly increased 5-HT-stimulated [3H]IP accumulation in the brainstem (+27%) and cortex (+23%). Because brainstem rather than cortex is involved in 5-HTP-evoked myoclonus, increased 5-HT-stimulated phosphoinositide hydrolysis in brainstem following 5,7-DHT lesions in the rat may be relevant to serotonergic behavioral supersensitivity.