Cardiac arrest following chlormethiazole infusion in chronic alcoholics

Two chronic alcoholics who had cardiac arrests (one fatal) while receiving chlormethiazole by infusion are reported. Although a causal relationship has not been indisputably established, caution is advised when administering this drug to chronic alcoholics during withdrawal.

Bioluminescence in Mesopelagic Squid: Diel Color Change During Counterillumination

Two species of mesopelagic squid greatly altered the color of their bio-luminescence during counterillumination. The color change was triggered by changes in water temperature corresponding to those normally encountered by these vertically migrating animals. These squid can probably conceal themselves under the different colors of downwelling light that they encounter in their day and night habitats.

Applied physiology for wheelchair design

The purpose of this study was to evaluate potential wheelchair design changes that may reduce operational energy cost and cardiopulmonary responses. Design changes, which were simulated with a wheelchair ergometer, allowed two techniques of hand-rim propulsion: the usual synchronous application of force (sync), and an asynchronous technique where force was applied one hand at a time in a reciprocal fashion (async). Three hand-rim drive ratios were also simulated: low, normal, and high. Combinations of these force application-drive ratio simulations were evaluated at power output (PO) levels of 30 and 60 kpm.min-1. The async-high combination was found to elicit significantly lower (P less than 0.01) gross caloric output, pulmonary ventilation, and heart rate values, and provide the greatest advantage over conventional sync-normal operation at both PO levels. It appeared that async propulsion and high drive ratio resulted in less wasted movements. Although the async-high combination was superior under these test conditions, other combinations may be necessary to better match various locomotive tasks to individuals of different capabilities.

Structure and dynamics of neural network oscillators

Techniques are given to represent oscillating neural networks by asynchronous logical switching networks, and to analyze the oscillating networks using a directed graph called a state transition diagram. Consideration is restricted to network oscillators containing no rhythm determining pacemaker neurons, and no neurons exhibiting self-limiting properties such as post-inhibitory rebound or accumulating refractoriness. In the state transition diagrams, stable oscillations are associated with a particular geometric configuration called a cyclic attractor (the heavy cycle in Fig. 2). We show that given the network connectivity it is possible to predict autonomous dynamic behaviour, as well as behaviour following hyperpolarizing or depolarizing inputs to neurons of the network. Conversely, given information about patterns of firing activity during cycles and transients of neural networks, the network connectivity can be predicted. The theoretical techniques can be used to generate a census of network structures capable of generating stable oscillations. Several representative network oscillators are discussed in the context of previous theoretical and experimental studies of the structure of neural network oscillators. Although the number of theoretically possile network oscillators capable of generating sustained oscillations is very large, the techniques which are given should be useful in the design of experiments capable of distinguishing between equally plausible hypotheses.

Postharvest Variation in Cellulase, Polygalacturonase, and Pectinmethylesterase in Avocado (Persea americana Mill, cv. Fuerte) Fruits in Relation to Respiration and Ethylene Production

Cellulase, polygalacturonase (PG), pectinmethylesterase (PME), respiration, and ethylene production were determined in single "Fuerte" avocado fruits from the day of harvest through the start of fruit breakdown. PME declined from its maximum value at the time of picking to a low level early in the climacteric. PG activity was not detectable in the preclimacteric stage, increased during the climacteric, and continued to increase during the postclimacteric phase to a level three times greater than when the fruit reached the edible soft stage. Cellulase activity was low in the preclimacteric fruit, started to increase just as respiration increased, and reached a level two times greater than at the edible soft stage. Cellulase activity started to increase 3 days before PG activity could be detected. Increased production of ethylene followed the increase in respiration and cellulase activity by about 1.5 days. These results indicate that a close relation exists between the rapid increase in the cell wall-depolymerizing enzymes and the rise in respiration and ethylene production and refocused attention on the role of the cell wall and the associated plasma membrane in the early events of fruit ripening.

Thermal Contrast in the Atmosphere of Venus: Initial Appraisal from Pioneer Venus Probe Data

The altitude profiles of temperature and pressure measured during the descent of the four Pioneer Venus probes show small contrast below the clouds but significant differences within the clouds at altitudes from 45 to 61 kilometers. At 60 kilometers, the probe which entered at 59.3 degrees north latitude sensed temperatures 25 K below those of the lower latitude probes, and a sizable difference persisted down to and slightly below the cloud base. It also sensed pressure below those of the other probes by as much as 49 millibars at a mean pressure of 200 millibars. The measured pressure differences are consistent with cyclostrophic balance of zonal winds ranging from 130 +/- 20 meters per second at 60 kilometers to 60 +/- 17 meters per second at 40 kilometers, with evidence in addition of a nonaxisymmetric component of the winds. The clouds were found to be 10 to 20 K warmer than the extended profiles of the lower atmosphere, and the middle cloud is convectively unstable. Both phenomena are attributed to the absorption of thermal radiation from below. Above the clouds, in the lower stratosphere, the lapse rate decreases abruptly to 3.5 K per kilometer, and a superimposed wave is evident. At 100 kilometers, the temperature is minimum, with a mean value of about 170 K.

Structure of the Atmosphere of Venus up to 110 Kilometers: Preliminary Results from the Four Pioneer Venus Entry Probes

The four Pioneer Venus entry probes transmitted data of good quality on the structure of the atmosphere below the clouds. Contrast of the structure below an altitude of 50 kilometers at four widely separated locations was found to be no more than a few degrees Kelvin, with slightly warmer temperatures at 30 degrees south latitude than at 5 degrees or 60 degrees north. The atmosphere was stably stratified above 15 or 20 kilometers, indicating that the near-adiabatic state is maintained by the general circulation. The profiles move from near-adiabatic toward radiative equilibrium at altitudes above 40 kilometers. There appears to be a region of vertical convection above the dense cloud deck, which lies at 47.5 to 49 kilometers and at temperature levels near 360 K. The atmosphere is nearly isothermal around 100 kilometers (175 to 180 K) and appears to exhibit a sizable temperature wave between 60 and 70 kilometers. This is where the 4-day wind is believed to occur. The temperature wave may be related to some of the wavelike phenomena seen in Mariner 10 ultraviolet photographs.

A system for storage and retrieval of individual cells following flow cytometry

A system has been developed to deposit cells in indexed locations on a gelatin-coated film following flow cytometry, allowing the measurements made of individual cells to be correlated with observed morphology or with subsequent microspectrophotometric measurements. Samples are deposited in a continuous track on the film by a deposition nib attached to the flow system below the observation point; laminar flow is preserved by adjusting the tape speed and the flow velocity. Locations of individual cells are indicated by etching the film with a spark triggered by the detection of a cell in the flow cytometer. After deposition, the film is dried by forced warm air. Cells on gelatin may be washed and restained with Papanicolaou and other stains with reasonable preservation of morphology. The system may be used for validation of automated cytodiagnostic procedures based on flow cytometry and for biomedical research.

Evidence for thyroidal secretion of 3,3',5'-triiodothyronine in man and its control by TSH

Thyroidal secretion of 3,3',5'-triiodothyronine (reverse T3, rT3) and its control by TSH was assessed by measuring (1) arterio-venous hormone gradients in patients undergoing surgery, (2) changes of hormone concentrations after induction of anaesthesia, and (3) changes induced by TRH administration. In ten patients in whom thyroid activity was under TSH control (parathyroidectomy and non-toxic goitre) increased thyroid vein/carotid artery ratios (TV/CA) for rT3 (mean TV/CA ratio 2.53) were found when compared to six patients with non-toxic goitre on suppressive doses of T4 (mean TV/CA ratio, 1.27) (P less than 0.05). The mean calculated operative secretion rate of rT3 was 12.5 microgram/day but only 2.4 microgram/day in patients receiving T4. In thirteen patients undergoing elective surgery induction of anaesthesia significantly increased rT3 levels. In nine euthyroid adults intravenous TRH (200 microgram) increased peripheral venous rT3 levels between 3 h (P less than 0.005) and 8 h (P less than 0.05) after the injection. It is concluded that significant amounts of rT3 are secreted by the thyroid gland at operation and this is, in part, under TSH control.

Succinoxidase Activity of Avocado Fruit Mitochondria in Relation to Temperature and Chilling Injury throughout the Climacteric Cycle

Mitochondria were isolated from ;Fuerte' avocado fruit (Persea americana Mill.) at four different stages of the respiratory climacteric. Preclimacteric fruit had the highest rate of succinate oxidation and the postclimacteric mitochondria the lowest. Subsequently, successive additions of ADP increased the respiratory control ratio.Arrhenius plots of succinate oxidation of intact mitochondria from climacteric rise and climacteric peak fruit showed two transition temperatures, while only one was observed in preclimacteric fruit. The low temperature phase transition was at about 9 C, while the high one was at 20 C. In postclimacteric fruit, the low temperature transition decreased to between 5 and 2 C. The state 3 rate of succinate oxidation was highest for mitochondria from preclimacteric fruit and decreased for each later stage. The state 4 rates for preclimacteric and climacteric rise were the same, while both the climacteric peak and postclimacteric rates were about 40% lower than the preclimacteric O(2) uptake.The results indicate continuous changes in the mitochondrial membrane of the electron transport chain throughout the climacteric cycle. The change in the membrane influencing the phosphorylation system is greatest between climacteric rise and peak stages. Mitochondrial membranes of postclimacteric fruit are presumed to change from flexible disordered to solid ordered phase at a lower temperature than those of other climacteric stages.

Barbiturates and serum calcium in the elderly

In a retrospective study, based on a biochemical survey of people aged 65 and over in a general practice, subjects taking a barbiturate preparation for indications other than epilepsy had a significantly lower serum calcium concentration than did those taking nitrazepam or diazepam. Ordinary doses of barbiturate may adversely affect vitamin D metabolism in the elderly.

Bioluminescent countershading in midwater animals: evidence from living squid

Midwater squid respond to overhead illumination by turning on numerous downward-directed photophores; they turn off the photophores when overhead illumination is eliminated. The squid are invisible when the intensity of the photophores matches the intensity of the overhead illumination. These results strongly support the theory of ventral bioluminescent countershading.

Patterns and bilateral coordination of scaphognathite rhythms in the lobster Homarus americanus

The bilateral patterns of forward and reversed scaphognathite (SG) pumping are described for the American lobster. During forward pumping the two SGs usually function synchronously, but may also function independently. The nine muscles of one SG are arranged into four functional groups which are sequentially active during forward pumping. During reversed beats, motor neurones to one group of muscles are inactive while bursts to another are either delayed or missing. Reversal beats do not appear to alter the phasing of the central oscillators that generate the basic SG rhythm. Phase analysis of bilateral SG beating demonstrates two types of relationship: phase coupling or phase drifting with a tendency to couple. An animal may remain in one state for long periods of time or may alternate between states. Coupling can occur at more than one phase indicating phase multistability. The coupled state may remain constant at markedly different frequencies of beating, indicating phase rather than latency coupling between SGs. During the drifting state each SG tends to assume its “intrinsic” rate of oscillation. The drift state reflects the inherent asymmetry of the two SG systems. The influence of several parameters of sensory stimulation on phase and frequency of SG beating are analyzed.

The Effect of Indole-3-acetic Acid and Other Growth Regulators on the Ripening of Avocado Fruits

Observations were made of the effects of several plant regulators, indole-3-acetic acid, kinetin, abscisic acid, and gibberellic acid, as well as of extracts prepared from leaves and fruit stalks on the respiration pattern, ethylene production, and the number of days to ripen of avocado fruits (Persea americana Mill.). These substances were vacuum infiltrated to insure good penetration and distribution. Kinetin, abscisic acid, gibberellic acid, and the extracts had no effect on either ripening time or on the respiration pattern and ethylene production of the fruits. Indoleacetic acid, however, had a marked effect on ripening. At high concentrations (100 and 1000 mum), indoleacetic acid stimulated respiration and induced preclimacteric ethylene production, resulting in accelerated ripening of the fruits. At the low concentrations (1 and 10 mum), it delayed ripening of fruits and suppressed the climacteric respiration and ethylene production. The results reinforce several previous observations with other fruits that auxins may largely constitute ;resistance to ripening' and may be responsible for the lack of ripening shown by unpicked fruits.