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Biomedical subjects

B F Johnson

Publications and source records attributed to B F Johnson.

158 records · Page 9Linked to original sources

Lysis of yeast cell walls induced by 2-deoxyglucose at their sites of glucan synthesis.

Six sites of 2-deoxyglucose (2DG)-induced lysis on three yeasts (Schizosaccharomyces pombe, Pichia farinosa, and Saccharomyces cerevisiae) coincided with the regions of growth of their glucan layers. Identification of the glucan layer as the site of lysis suggests a mechanism of attack by 2DG or by its derivatives. It is proposed that the glucan layer grows by addition of glucose into internal breaks of polysaccharide molecules. 2DG inhibited resynthesis (insertion of glucose) of the broken glycosidic linkage.

Aminohydrolases↗

Growth of the fission yeast, Schizosaccharomyces pombe, with late, eccentric, lytic fission in an unbalanced medium.

Growth of Schizosaccharomyces pombe in batch cultures in a commercial defined medium was found to be normal until the last generation before the stationary phase. Approximately one-half the progeny of the last division lysed. Lysis occurred at breaks in the cell wall at cell-plates whose fission was eccentric. Normal culture cycle patterns were obtained when the medium was balanced by addition of either 0.20 mg of l-asparagine per ml or 5.0 mg of KH(2)PO(4) per ml, or both. The lytic effect of growth in the unbalanced medium was compared with similar effects of growth in 2-deoxyglucose. These studies with 2-deoxyglucose in the balanced medium confirmed earlier cytological observations (lysis at all growing points), but showed that the similarities were superficial.

Asparagine↗

The effect of once-daily minoxidil on blood pressure and plasma lipids.

Once-daily minoxidil administration was added to the treatment regimen of 11 patients with hypertension that was inadequately controlled by nadolol 160 mg and chlorthalidone 50 mg given once daily. Additional diuretic therapy was needed by five patients. During treatment without minoxidil and at three and six months of maintenance minoxidil therapy, respectively, 24-hour postdose supine blood pressure fell significantly (P less than .01) from 142 +/- 19/96 +/- 6 mm Hg to 132 +/- 16/87 +/- 4 and 131 +/- 12/87 +/- 4 mm Hg, and home recordings showed that minoxidil induced a mean increase of about 5 beats/min in heart rate. Resting plasma renin activity was not significantly altered. High-density lipoprotein (HDL) cholesterol increased from 31.6 +/- 9.9 to 35.2 +/- 10.9 mg/dL (P less than .05) and to 34.4 +/- 11.3 mg/dL (NS), and low-density lipoprotein (LDL) cholesterol decreased from 146 +/- 36 to 136 +/- 32 mg/dL (P less than .05) and to 126 +/- 35 mg/dL (P less than .01) over the same periods. At six months, approximately 20% changes in ratios of HDL cholesterol to either LDL or total cholesterol were seen. These changes occurred despite a three-pound mean increase in body weight (P less than .05); these alterations are potentially beneficial in terms of reducing the estimated risk of coronary artery disease.

Adult↗

Plaque assay and replication of Tipula iridescent virus in Spodoptera frugiperda ovarian cells.

A plaque assay was developed for the study of Tipula iridescent virus (TIV) replication using a cell line derived from the fall army worm Spodoptera frugiperda (Sf9). Infection and plaque formation were monitored with time by phase contrast microscopy, video and fluorescent light microscopy. Structure of virions, viroplasmic centres and organelles of infected cells were examined by transmission electron microscopy (TEM). After 4 h postinfection, plaques were visibly detected within the cell monolayer by the presence of localized cell damage and production of numerous vesicular-like cytoplasmic structures. Quantitation of virions present per A260 unit of TIV preparation was determined by TEM. The number of visible plaques corresponded to virus concentration and 1 A260 produced approximately 10(5) plaques. DNA hybridization analysis revealed no gross differences in genomic DNA from TIV propagated in either Sf9 cells or wax moth Galleria mellonella larvae. These findings indicate that Sf9 is permissive for replication of TIV and superior by some parameters to other cell lines currently in use for the study of host cell/TIV interactions.

Animals↗

Randomized prospective comparison of laparoscopic and open peritoneal dialysis catheter insertion.

OBJECTIVE: To compare laparoscopic and conventional peritoneal dialysis catheter insertion with respect to post operative discomfort, complication rates, and catheter survival. DESIGN: Randomized prospective study. SETTING: Tertiary referral renal unit. PATIENTS: Fifty patients commencing peritoneal dialysis. INTERVENTION: Catheters were implanted laparoscopically or by a conventional surgical technique. MAIN OUTCOME MEASURES: The duration of surgery, hospital stay, pain scores, and analgesic requirements were recorded. Complications (early/late) and catheter survival were compared. RESULTS: The conventional procedure was faster than the laparoscopic (14.3 vs 21.9 minutes, p < 0.0001). There was no difference in any other parameter assessed. CONCLUSIONS: The data suggest that the insertion techniques are equivalent, and that laparoscopic insertion does not reduce early complication rates.

Catheterization↗