Inhibition of sugar uptake in adenosine-treated 3T3 cells

Addition of 5 to 250 micromolar adenosine to the culture medium resulted in a 30–80% inhibition of the rate of uptake of 2-deoxyglucose or 3–0-methylglucose by sparse or confluent 3T3 cells within three hours. The inhibition of deoxyglucose uptake could be reversed partially by changing the cells to medium without adenosine for two hours and could be prevented completely by the addition of persantin, an inhibitor of nucleoside uptake. The adenosine effect is not due to inhibition of pyrimidine synthesis, since it is not prevented by uridine. It is not seen in 3T6 cells lacking adenosine kinase. The inhibition could be observed on confluent cells whose deoxyglucose uptake was stimulated by insulin, epidermal growth factor (EGF), calf serum or calcium phosphate. Although the percentage stimulation over control by these factors varied, the percentage inhibition by addition of adenosine of the stimulated rates, as well as the unstimulated rate, was relatively constant. EGF, insulin and calcium phosphate caused little or no stimulation of deoxyglucose uptake by sparse cells, whether adenosine treated or untreated. The results suggest that adenosine acts intracellularly after phosphorylation to regulate sugar uptake through a mechanism which is independent of the regulation by hormones and cell density.     

Spawning of hermatypic corals in Bermuda: a pilot study

This study investigates spawning of 4 hermatypic coral species from the subtropical environment of Bermuda. Laboratory evidence of spawning behaviour is supported by synchronous field observations. Development of scleractinian planulae to postlarval stages is recorded. Diploria strigosa, D. labyrinthiformis, Montastrea annularis and M. cavernosa shed highly buoyant, pigmented eggs (300–440 µm diam.) during July to September 1986. Brief spawning periods, synchronous between conspecific colonies, were recorded for M. annularis (July and August) and M. cavernosa (August) within 1 d of the last quarter of the lunar cycle. In August, there were overlaps amongst the spawning dates of D. strigosa and the Montastrea species. Nocturnal spawning periods differed between M. annularis and M. cavernosa. This constitutes the first evidence from an Atlantic community of overlapping spawning dates amongst several faviid species, and of the accumulation of scleractinian eggs and planulae in surface slicks.     

More is not better: brood size and population growth in a self-fertilizing nematode.

The normal form of the nematode Caenorhabditis elegans is a self-fertilizing hermaphrodite, which produces from the same germ-line tissue first a limited number of sperm and then a larger number of oocytes. Self-progeny brood sizes are determined by the number of sperm, and most of the oocytes remain unfertilized. Therefore it might seem selectively advantageous to increase the number of sperm, and hence the size of the brood. A mutation that leads to a 50% increase in sperm production allows a comparison of population growth rates between the wild type (mean brood 327 progeny) and the mutant (mean brood 499 progeny). Wild-type populations grow faster, as measured by food consumption, indicating that increased brood size is not advantageous. The mutant appears to be at a disadvantage because the additional spermatogenesis leads to a delay in the onset of oogenesis, and hence to an increase in the minimum generation time. In support of the notion of an optimal brood size, it was found that different natural isolates of this species have self-fertilities similar to that of the standard laboratory strain, in the range 250-350 progeny per worm.     

Benthic macroinvertebrates of northwestern lake victoria,East Africa: Abundance,distribution, intra-phyletic relationships and relationships between taxa and selected element concentrations in the lake-bottom sediments

Phytoplankton assemblage and seston composition of the San José's gulf (Argentine, 42° S) were studied during a period of two years. Cell counts, chlorophyll, particulate nitrogen and particulate carbon determination were made. Phytoplankton synecology was studied using principal component analysis.

     

Value of 1-alpha-hydroxy vitamin D3 in treatment of primary hyperparathyroidism before parathyroidectomy.

The postoperative course of six patients with primary hyperparathyroidism and obvious radiological evidence of bone disease pretreated with 1-alpha-hydroxy vitamin D3 (1 alpha HCC) was indistinguishable from that of six patients with a similar clinical and radiological picture who were not pretreated. 1alphaHCC may increase the hypercalcaemia in some cases and cannot be recommended for the routine preparation of such patients for surgery.     

An apparatus for anesthetizing small laboratory animals.

A simple apparatus was designed for simultaneous general anesthesia of a number of small laboratory animals with spontaneous respiration. Anesthesia is consistent over many hr. The apparatus consists of an oxygen tank and vaporizer, a glass distribution bottle, and a non-return circuit of separate inspiratory and expiratory valves for each animal. The equipment is inexpensive to construct and can be rapidly adjusted for exact control of gas flow and anesthetic depth.     

Agonal phase,ischaemic times,and renal vascular abnormalities and outcome of cadaver kidney transplants.

A retrospective study of 250 cadaver kidney transplants was carried out to determine the effects of the agonal period, the warm and cold ischaemic times, and the use of kidneys with vascular anomalies on the primary success and failure and the subsequent level of function of the transplants. Kidneys with vascular anomalies or from non-ventilated donors had a primary failure rate of over 30%, whereas those with normal vasculature or from ventilated donors had a rate of 17%. An initial warm ischaemic time of more than 60 minutes was associated with a primary failure rate of 57% and a cold ischaemic time of over 550 minutes with a primary failure rate of 47%. The interrelationship between the warm and cold ischaemic times in the primary success or failure of the transplants was examined and criteria defined for selecting potentially viable cadaver kidneys for transplantation, as follows: (1) The donor should be (a) ventilated, (b) aged 6-50 years, and (c) have normal ante-mortem renal function and have secreted more than 1-5 1 of urine in the 24 hours before death (or an equivalent volume if the urinary output was recorded for less than 24 hours before death); (2) the kidney should have normal renal vasculature enabling single arterial and venous anastomoses to be performed; (3) kidneys with I.W.I.T.s of longer than 60 minutes should not be used; (4) for kidneys with I.W.I.T.s of less than 20 minutes the C.I.T. is not critical but should not exceed 12 hours; (5) for kidneys with I.W.I.T.s of 20-60 minutes the C.I.T. should not exceed 450 minutes.