Blue-green algae: their excretion of iron-selective chelators enables them to dominate other algae

During blue-green algal blooms, other algae can be completely suppressed. This ability of blue-green algae to suppress other algae may be determined by the abailability of iron. Iron deprivation induces the production of hydroxamate chelators, which appear to be the agent suppressing other algae.     

Cerebral ischemic events associated with prolapsing mitral valve

Twelve patients who had no evidence of arteriosclerotic cerebral vascular disease, lacked hypertension or coagulation defect, and had not been receiving contraceptive therapy had recurrent transient cerebral ischemic attacks (TIAs) and partial nonprogressive strokes. All had prolapsing mitral valve proved by angiocardiography. The average age was 38 years, compared with 62 years in a larger series of patients with TIA associated with arteriosclerosis. We propose that the ischemic events are related to emboli emanating from the abnormal mitral valve with or without an associated paroxysmal cardiac arrhythmia.     

Toxicity following methoxyflurane anaesthesia. IV. The role of obesity and the effect of low dose anaesthesia on fluoride metabolism and renal function

Seven obese and five normal weight patients were studied before, during and after one hour of methoxyflurane-nitrous oxide anaesthesia during peripheral surgical operations and compared with eight patients of normal weight anaesthetized with nitrous oxide-meperidine and d-tubocurare. Estimates were made of renal function, including serum and urinary electrolytes, osmolarity, uric acid, urea and creatinine. Renal clearances for the latter three substances were also calculated. Serum and urinary inorganic and organic fluoride concentrations were measured, as were renal clearances. This low dose methoxyflurane anaesthesia resulted only in a decrease in uric acid clearance among all the measures, when compared to the meperidine-nitrous oxide controls. The clearance of uric acid remained depressed for longer in the obese patients, but otherwise they did not differ from the normal weight patients. It is possible but not proven that depressed uric acid clearance may be related to the organic fluoride metabolite and an early indicator of methoxyflurane renal toxicity. The previously documented biotransformation of methoxyflurane was seen in this study. A double peak in serum inorganic fluoride was shown in all patients but one. Rather large differences in peak levels of serum inorganic fluoride occurred. The only significant difference between the obese and normal weight patients as far as fluoride metabolism was concerned was a greater variability in the serum inorganic fluoride levels in the obese patients. It would appear that the obese patient metabolizes methoxyflurane in a quantitatively if not qualitatively different fashion than the normal weight patient, perhaps because of fatty infiltration of the liver. Caution is advised in the use of methoxyflurane for more than 90 minutes of low concentration administration in view of the unpredictability of the biotransformation.     

Aerial fallout of DDT in southern California

Ender's method of intramedullary fixation of intertrochanteric and subtrochanteric fractures is described. Ender's nail is a pre-bent flexible steel nail with a diameter of 4.5 millimeters. Three to five of these nails are inserted from a small incision proximal to the medial epicondyle of the femur into the medullary canal. They are passed through the femur across the fracture site and into the head of the femur, where they diverage. They are in the lines of force and therefore are not subjected to bending moments. The fracture fixation allows immediate weight-bearing. This method of fixation was used in a series of 203 patients. Their average age was sixty-eight years; the mortality rate was 10.3 per cent. In 3.9 per cent superficial infections occurred, but in no case was there a deep infection involving the bone. Functional return (walking) was achieved in all of the survivors who were able to walk at the time of injury, and there were no nonunions.     

The metal/tissue interface effect in irradiation of the oral cavity

Bovine ligamentum nuchae elastin that had been partially digested by porcine pancreatic elastase and then thoroughly washed with 0.2 M-NaC1/0.05 M-sodium borate solution continued to release peptide fragments in solution. Complete removal of elastase from the elastin surface required extraction with dilute alkali, a procedure that does not irreversibly inactivate the enzyme or hydrolyse elastin.     

The effect of environmental pH on the failure strain of anodic films formed on the aluminum alloy 2024

The ultimate tensile strain of anodic films formed on 2024-T4 aluminum was evaluated as a function of pH in environments of 10⁻³M and 1·0M KNO₃, using resistive and capactive techniques. In the resistive technique, ultimate tensile strain was defined as the strain at which a discontinuous increase in anodic current was observed; in the capacitive technique, film failure was marked by a discontinuity in the slope of the capacitance versus strain curve. The ultimate tensile strain was seen to be significantly greater at the zero-point-of charge of the oxide (pH 8) than at higher or lower pH; in the capacitive measurements the ultimate tensile strain had an average value of 0·97 at pH 8 and 0·87 for measurements made at pH values of 4, 7 and 9. Dielectric behavior of the anodic films was seen to be different only in degree from that of films formed on pure aluminum. Changes in capacitance associated only with exposure were measured and taken into account. Capacitance behavior with strain was modeled by two linear regions; the first was attributed to elastic deformation of the film and the second, after failure, to the growth of regions of metal covered only with a thin, spontaneously-formed oxide.     

Cell proliferation in the prostate complex of the castrate mouse

Cell proliferation during 100 h of continuous androgen challenge was studied in the seminal vesicle and coagulating gland of Balb/c mice castrated 3 days or 14 days prior to the first daily injection of 250 mug testosterone propionate. Continuous labelling with [3H] thymidine indicated that the seminal vesicle was almost totally responsive to androgen, as early as 3 days after castration, whereas the androgen sensitivity of the coagulating gland increased from 30% at 3 days after castration to 85% at 14 days after castration. In both tissues the magnitude of the proliferative reaction could be related to the extent of cell loss prior to stimulation. The duration of the pre-replicative phase in the response of the seminal vesicle to androgen was 20-25 h both at 3 and 14 days after castration. In the coagulating gland the pre-replicative phase was 40 h at 3 days after castration and 20 h at 14 days after castration. The maximum uptake of [7alpha-3H] testosterone administered to mice 3 days after castration was significantly greater (P less than 0-01) in the seminal vesicle compared to the coagulating gland. At 14 days the seminal vesicle and coagulating gland exhibited a similar capacity for uptake. The in vivo metabolism of [7alpha-3H] testosterone was studied by thin layer chromatography 30 min and 120 min after administration. A high proportion of the radioactivity extracted from all the tissues was associated with highly polar steroids. At 3 days after castration, the seminal vesicle, 2 h after administration of radioactive testosterone, retained a much higher proportion of radioactivity associated with dihydrotestosterone than did the coagulating gland. The localization of steroid in mice 3 days after castration was studied by dry-mount autoradiography at intervals up to 2 h after the injection of [1,2,6,7(n)-3H]-testosterone. A heavier deposition of silver grains was observed over autoradiographs of the seminal vesicle. In the seminal vesicle the grains were primarily located over nuclear areas whereas in the coagulating gland the grains were diffusely distributed over both nuclear areas and over cytoplasmic areas.     

The occurrence in amino acid sequences of extensive informational symmetries based on possible codon-codon complementarity in the encoding polynucleotides

1. A procedure is described for the detection and assessment of informational complementarity in an amino acid sequence; it is based on possible autocomplementarity in the mRNA, and involves codon-to-codon matching. 2. This procedure was applied to myelin basic protein, a variety of protamines, histone IV, silk fibroin, rat skin collagen alpha1 chain and a sheep keratin. A multiplicity of extensive low-probability informational symmetries, based on codon-to-codon matching, were detected. 3. These low-probability orderings, which are independent of the actual mRNA codons, are rationalized in terms of the evolutionary ordering of the amino acid sequences concerned, in such a way that constraints on the secondary structure of the coding polynucleotides were satisfied. This possible interpretation is supported by a number of significant common properties of the protein sequences analysed.