Did liberalising bar hours decrease traffic accidents?

Legal bar closing times in England and Wales have historically been early and uniform. Recent legislation liberalised closing times with the object of reducing social problems thought associated with drinking to “beat the clock.” Indeed, using both difference in difference and synthetic control approaches we show that one consequence of this liberalisation was a decrease in traffic accidents. This decrease is heavily concentrated among younger drivers. Moreover, we provide evidence that the effect was most pronounced in the hours of the week directly affected by the liberalisation: late nights and early mornings on weekends. This evidence survives a series of robustness checks and suggests at least one socially positive consequence of extending bar hours.     

内源性一氧化碳的血管调节作用

一氧化碳（CO）作为继一氧化氮之后的又一内源性气体信号分子,具有与一氧化氮相似的血管调节作用.在生理状态下,CO具有舒张血管,抑制血管平滑肌细胞增殖的作用.在病理生理学状态下,CO参与高血压、动脉粥样硬化、肺动脉高压、血管钙化等发病过程.该文就CO的生成、代谢,生理状态下及病理状态下内源性CO的血管调节作用进行综述.     

Regulation of nisin biosynthesis by continuous cultures and by resting cell of Lactococcus lactis subsp. lactis

Nisin production by Lactococcus lactis subsp. lactis has been investigated using lactose as carbon source. Whether or not continuous cultures were lactose-limited, maximum nisin titre was observed at an intermediate mu value with a sharp peak of activity between 0.2 and 0.3/h. The maximum specific growth rate obtained in the medium used was 0.6/h and the maximum titre of nisin at mu = 0.25/h (160 AU/ml) was about nine-fold higher as compared with activity obtained at a dilution rate of 0.05/h or 0.4/h. With a constant dilution rate of 0.25/h and varying initial lactose concentrations from 3 to 40 g/l, there is an increase in nisin biosynthesis with increasing lactose concentration correlated with higher rates of sugar consumption. A Ymax value of 0.2 g bacterial dry weight and a maintenance coefficient of 124 mg lactose/g bacterial dry weight/h were determined. Lactose consumption increased from 1 to 3.28 g of lactose/g (dry wt) of cell mass/h and the nisin titre from 12.5 to 164.2 AU/ml. At higher values, nisin production declined. This implies that biosynthesis of nisin is regulated by a system of repression and derepression. Addition of lanthionine and beta-methyllanthionine precursors to the medium decreased the nisin titre when either threonine, threonine-cysteine, or cysteine-serine-threonine was added at the optimal dilution rate of 0.25/h; however, simultaneous addition of serine and cysteine elicited a slight increase in nisin activity. Studies with resting cells confirm that the biosynthesis of nisin is tightly regulated, since the production rate can be 5.6-fold higher than in cells grown in continuous culture. In addition, cell-adhered nisin appears to play a role in the production of the enzyme: low levels of cell-adhered nisin elicited high production rates, whereas high levels were not associated with nisin biosynthesis. In addition to pH, magnesium sulphate and lactose concentrations, nitrogen sources were also able to interfere in cell-adherence nisin.     

Computerized left ventricular mechanics and control system analyses models relevant for cardiac diagnosis

Two left ventricular models, relevant to cardiac diagnosis, are presented. The first is a Computer-based Finite Element Stress Analysis model of the left ventricle (LV) aimed to account for the irregular left ventricular geometry obtainable from single plane cineangiocardiography. The in vivo data for the model consists of instantaneous left ventricular chamber pressure and cine. The calculated wall stresses are compared with idealized geometry models. The finite element model is better able to delineate the stress concentrations at sites of large curvatures.The second model consists of a control system model of the LV, which formulates the interaction of the mechanics of the LV and the lumped parameter circulatory system by the central nervous system's monitoring of the mean arterial pressure, regulation of the heart rate, left ventricular contractility and the perepheral impedance. The model is parametrically simulated for a subject by means of the continuous system modelling program (CSMP); then the simulated model's response to a physiological stress simulating pressure perturbation is determined; the model enables an assessment of the physiological stress sustaining capacity of a subject.     

Recovery of feeding in rats following frontal neocortical ablations

This study examines behavioral recovery from the aphagia-adipsia syndrome following frontal neocortical ablation in relation to the recovery of neurological function in the brain-damaged animal. Regulation of food and water intake in the post recovery period was also investigated. Behavioral recovery occurs in three articulated stages of improving sensori-motor function which reflect the animal's underlying neurological recovery. The first stage is one in which food and water intake can be accomplished only by reflexive sucking. In the second stage, goal directed scraping of the surface of solid foods and ingestion of soft foods are possible. In the final stage, chewing and biting are re-established and normal weight regulation is maintained on a standard laboratory diet. After recovery, sensori-motor deficits remain which do not impair feeding and drinking unless mechanically difficult diets are presented. Except for a response deficit in the insulin-induced overeating test and an increased sensitivity to quinine adulterated food, recovered animals respond normally to a series of regulatory challenges.     

Models of energy metabolism of intact animals: Data tabulations, representation of basal metabolic activities and endocrine effects upon metabolism

Explicit representation of several aspects of tissue metabolism has been found essential in animal models constructed to evaluate concepts and hypotheses regarding physiological regulatory mechanisms. Using a model of human metabolism as an example, an approach adopted for representation of animal energy metabolism is presented. Discussed are bases for identification of tissue and organ systems appropriately represented separately or in aggregate, definition of basal and variable functions of the tissue or organ system elements which comprise the model, systematic compilation of data required and example equations representing tissue energy metabolism, endocrine function and metabolic regulation.     

Studies on the ascending pathways from the thermosensitive region of the spinal cord

Summary In young guinea pigs the ascending pathways from the spinal thermosensitive region were studied by means of 1. microelectrode recording and 2. micro-electrocoagulation. In the first series of studies, impulse frequency was recorded from single units of the spinothalamic tract which responded to a temperature rise in the spinal segments C₅-T₂ with an increase of discharge frequency. At a spinal cord temperature of 38–39° C these units showed a firing rate of 1–5 imp./sec; local heating of the spinal cord (dT/dt=0.1° C/sec) to 40–41° C caused an increase in discharge frequency to 20–25 imp./sec. The mean static impulse frequency was 3 imp./sec at a spinal cord temperature of 39° C, and 10 imp./sec at a spinal cord temperature of 42.5° C.In the second series of studies bilateral RF-coagulations were carried out in different sites of the diencephalon. These experiments showed that the ascending fibres from the spinal thermosensitive region connect the thermosensitive spinal region with a hypothalamic temperature control centre.Supported by the Deutsche Forschungsgemeinschaft (Br. 184/10).     

Evidence against a causal relationship between increase in c-AMP and induction of tyrosine hydroxylase in the rat adrenal medulla

Summary It was the purpose of the present experiments to establish whether the reserpine-mediated changes in adrenomedullary c-AMP result from - or -adrenergic activation of adenylate cyclase by catecholamines liberated from adrenal chromaffin cells and whether a causal relationship exists between these changes and subsequent induction of tyrosine hydroxylase (TH).The reserpine-mediated increase in c-AMP was blocked by neither - nor -adrenergic blocking agents. However, propranolol abolished the increase in c-AMP by a mechanism which is not related to the -blocking properties of this drug. Although propranolol abolished the reserpine-mediated increase in c-AMP it did not interfere with the subsequent TH induction. Moreover, administration of aminophylline together with reserpine produced a larger and more prolonged increase in c-AMP in denervated adrenals than reserpine alone in intact glands. Denervation prevented TH induction in spite of the more extensive increase in c-AMP in the adrenal medulla after the combined treatment. It is concluded that there is no causal relationship between the overall increase in c-AMP in the adrenal medulla and the subsequent TH induction. However, the possibility that a small pool of c-AMP which is overshadowed by the non-related overall changes may be involved in trans-synaptic TH induction cannot be excluded.     

Increased blood osmolarity and its effect on respiration of dehydrating men

Summary Eight unacclimatized nude male subjects were alternately exposed to room temperature (25.5–27.8°C) and heat (43.3°C D.B., 28°C W.B.). While in the heat chamber respiration was affected by an elevatedT _r and plasma osmolarity. Removal of subjects from the heat decreasedT _rbut did not significantly change osmolarity. Effects ofT _rand osmolarity on respiration then could be separated. The data indicated that increased plasma osmolarity reduced respiratory responses to elevated body temperature. Decreased sensitivity to inhaled 3% CO₂ also correlated with increases in plasma osmolarity, thus suggesting opposing actions of elevated body temperature and increased osmolarity on respiration of men undergoing progessive dehydration.This work was supported by N.I.H. grants 5 R01 He-07075 and 1K3 HE-25, 110.