Synthesis time of beta-galactosidase in Escherichia coli B/r as a function of growth rate

By analysing the kinetics of beta-galactosidase accumulation after induction, the synthesis time of beta-galactosidase in Escherichia coli B/r was found to be 75s in rapidly growing cells (1.36 and 2.1 doublings/h), and 90s in slowly growing cells (0.63 doubling/h). These values correspond to peptide-chain-elongation rates of 16 and 13 amino acids/s respectively, in agreement with previous findings, indicating that the peptide-chain growth rate is constant (presumably maximal) in fast-growing bacteria, but decreased in slowly growing bacteria [Forchhammer & Lindahl (1971) J. Mol. Biol. 55, 563-568].

Deanol and methylphenidate in minimal brain dysfunction

Deanol, a putative acetylcholine precursor, has been used as a treatment for childhood hyperactivity for years. Efficacy has not been satisfactorily established, however. Seventy-four children referred for problems with learning, including many with hyperactivity, were screened for neurological or psychiatric illness, then given deanol, methylphenidate, or placebo in a double-blind fashion for 3 months. Maintenance dose for methylphenidate was 40 mg daily; for deanol, 500 mg. Behavior rating forms, reaction time, and a series of standard psychometric tests were given before and after treatment. Both drugs showed significant improvement on a number of tests; the pattern and degree of change differed slightly for the two. In this paradigm, deanol thus appeared to improve performance in children with learning and behavior disorders. The mechanism of action remains speculative; proof that deanol increases acetylcholine is scanty, and there is a theoretical basis for actually assuming an anticholinergic effect. Further clinical studies on deanol are indicated.

Effect of progesterone on estrogen receptors in the rabbit uterus

The macromolecular binding of estradiol was investigated in the rabbit uterus under various hormonal states in a search for evidence of progesterone antagonism of the estrogen-receptor complex interaction. Progesterone did not alter the sucrose gradient sedimentation characteristics of the estrogen-receptor complex in estrus or castrate animals. Progesterone treatment of castrated animals did not alter the absolute number of EBS (estrogen-binding sites) per cell, but did result in decreased relative concentration of EBS by increasing the soluble protein content of the cells over that seen in untreated castrates. Castration did not alter the absolute number of EBS per cell but did increase the relative concentration of estrogen binding in the cytosol.

Treatment of thyrotoxicosis during pregnancy with propranolol

The treatment of two pregnant thyrotoxic patients with propranolol alone is discussed. One patient had a spontaneous remission during pregnancy wile taking propranolol. In the other patient treatment with propranolol allowed postponement of definitive therapy until after delivery, when the fetus was no longer at risk. There were no complications of therapy in either patient and both infants were normal. The use of propranolol in thyrotoxicosis is discussed and the pertinent literature is reviewed. Regional anesthesia is preferred over general anesthsia in patients taking propranolol. Patients taking propranolol who require general anesthesia for delivery should have continuous monitoring of electrocardiogram and central venous pressure. To this date no method of therapy has been free of fetal side effects. Surgical treatment is associated with occasional abortion or premature labor; antithyroid medication occasionally results in fetal goiter or cretinism.

Epidemic Venezuelan equine encephalitis in North America in 1971: vector studies

A major epidemic of Venezuelan equine encephalitis occurred in south Texas in the summer of 1971. More than 1500 equines died of VEE in Texas, and 110 human cases with no deaths were reported. Vector studies in south Texas and northern Tamaulipas revealed that the overall mosquito infection rates during the peak of the epidemic were about 1:100, one of the highest rates observed for a major epidemic. Mosquito infection rates of this magnitude could easily explain the intensity of VEE outbreaks in both equines and man. A total of 943 VEE virus isolations were made from mosquitoes. Eight of the 12 mosquito species found infected were implicated in the epidemic cycle of VEE for the first time. Sufficient laboratory and field evidence is available to prove that Psorophora confinnis was one of the primary vectors of VEE. The lack of laboratory evidence necessitates the use of the term "probable" primary vectors for other species apparently equally as involved on the basis of field infections; these include Aedes sollicitans, Aedes thelcter and Psorophora discolor. Eight other species from which less than 10 VEE virus isolations were made were considered auxiliary vectors. Mosquitoes of some species were tested individually; such tests showed 2-4% of the probable primary vectors to be infected. The first isolation of VEE virus of the epidemic was made from P. confinnis on June 28, 1971. Highest mosquito infection rates occurred during the week of July 5. Mosquito infection rates declined precipitously in the last 3 weeks of July 1971, signaling the end of the epidemic in the study area. One explanation for the decline was that equines, the principal epidemic hosts, were eliminated as a source of virus by death or by acquisition of natural or induced immunity. Mosquito control appeared to be effective in reducing the infected mosquito population while the immunization of equines with TC 83 VEE vaccine was accomplished. Quarantines appeared to be effective in restricting the VEE virus activity to south Texas. Undoubtedly all of the control measures contributed to stopping the epidemic. Continued VEE surveillance by various government and other agencies failed to reveal any further epidemic VEE activity in the US in 1972. Other arboviruses isolated during the VEE studies in south Texas included St. Louis encephalitis virus, and San Angelo subtype of the California Group. A virus of the Bunyamwera Group was also isolated from Palo Blanco, Tamaulipas.

Breast tumor cell lines from pleural effusions

During 1973, 4 new epithelial tumor cell lines were isolated from pleural effusions from breast cancer patients. We describe 3 of these lines: MDA-MB-134, with a mean chromosome number of 43; MDA-MB-175, with a mean chromosome number of 49; and MDA-MB-231, with a mean chromosome number between 65 and 69. We isolated the same cell type from 4 of 10 effusions from MDA-MB-134 and from 6 of 8 effusions from MDA-MB-175. We found that pleural effusions as a source of breast tumor cells to be cultured and studied in vitro have the following advantages: 1) large amounts of material and the possibility of obtaining sequential samples from the same patient; 2) high viability of tumor cells; 3) scarcity or absence of fibroblasts; and 4) the possibility of separating the tumor cells from other “contaminating” cell types by differences in their speed or degree of attachment to the flask. All lines from different patients differed, as seen grossly and microscopically. All lines from sequential pleural effusions from the same patient were apparently alike. No viruses or mycoplasmas were detected in any line.

Simple quantitative vectorcardiographic criteria for the diagnosis of right ventricular hypertrophy

The vectorcardiogram is a useful supplement to the conventional electrocardiogram in the recognition of right ventricular hypertrophy. Many quantitative criteria have been proposed. However they are often too complicated for routine clinical application. Based on the distribution of the QRS loop area in the various quadrants in the vectorcardiogram in 198 normal subjects, three simple criteria for diagnosis of right ventricular hypertrophy are derived: 1) the anterior and rightward QRS loop area in the transverse plane is greater than 70% of the total; 2) the QRS loop area in the right posterior quadrant of the transverse plane is greater than 20% of the total; 3) the QRS loop area in the right inferior quadrant in the frontal plane is greater than 20% of the total. Vectorcardiogram recordings in 97 patients with atrial septal defect, mitral stenosis, and chronic obstructive lung disease with pulmonary hypertension met one or more of the criteria in 80 (83%). The conventional electrocardiogram of these patients was suggestive of right ventricular hypertrophy in 64 (66%). It is concluded that the proposed vectorcardiographic criteria provide a sensitive means for the diagnosis of right ventricular hypertrophy. Their specificity however was not tested.

Effect of exposure to subfreezing temperatures on ethylene evolution and leaf abscission in citrus

Citrus leaves exposed to subfreezing temperatures evolved ethylene at rates between 0.1 and 38.3 microliters per kilogram fresh weight per hour whereas untreated leaves evolved between 0.01 and 0.50 microliter per kilogram fresh weight per hour. Leaves not injured by freezing temperatures did not abscise, and ethylene evolution was near normal after 2 days. Freeze-injured leaves continued evolving high ethylene levels 4 or 5 days subsequent to freeze injury, and many of the freeze-killed leaves abscised. Supportive evidence suggested freeze-induced ethylene was involved in freeze-induced leaf abscission; whereas freeze-inhibited abscission was not due to a lack of ethylene but injury to other metabolic systems necessary for abscission.

Phaeochromocytoma of the bladder

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Capsular polysaccharides of Serratia marcescens

Four polysaccharides were isolated from the capsular layer of Serratia marcescens cells grown on a sucrose medium. In composition, electrophoretic behavior, and sedimentation in the ultracentrifuge, all were shown to be markedly different. Analytical data indicated that the polysaccharides were an acidic glucomannan (I), a rhamnoglucan (II), a glucoheptan (III), and a rhamnoheptoglucan (IV). In I, in addition to the main acidic component D-glucuronic acid, a small amount of guluronic acid was also identified. A relatively high protein or peptide content in the purified polysaccharides suggested that it was firmly bound to the carbohydrate structure; "bound" lipid consisting mainly of hydroxymyristic acid was also a part of the structure. Methylation studies established the main glycosidic linkages in I, II, and III. The capsular polysaccharides had properties similar to those of polysaccharides isolated from a culture filtrate of S. marcescens in an earlier study, and a possible relationship between these two groups of polysaccharides is discussed.