Exoplanet detection. A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary.

Using gravitational microlensing, we detected a cold terrestrial planet orbiting one member of a binary star system. The planet has low mass (twice Earth's) and lies projected at ~0.8 astronomical units (AU) from its host star, about the distance between Earth and the Sun. However, the planet's temperature is much lower, <60 Kelvin, because the host star is only 0.10 to 0.15 solar masses and therefore more than 400 times less luminous than the Sun. The host itself orbits a slightly more massive companion with projected separation of 10 to 15 AU. This detection is consistent with such systems being very common. Straightforward modification of current microlensing search strategies could increase sensitivity to planets in binary systems. With more detections, such binary-star planetary systems could constrain models of planet formation and evolution.

Responses of frog skin, Rana pipiens, calcium ion transport to parathyroid hormone, calcitonin, and vitamin D3.

The responses of cutaneous Ca2+ transport to parathyroid hormone, calcitonin, and vitamin D3 were evaluated in intact Rana pipiens and isolated skins from this species. Parathyroid hormone (12 pmol g-1) stimulated Ca2+ influx in intact frogs but not in isolated skin (10-100 pmol ml-1) unless the frogs had been pretreated with vitamin D3 injections (100-300 microgram day-1) for 3 days prior to isolating the skins for flux measurements. Pretreatment of intact frogs with vitamin D3 for 3 days (100 microgram day-1) also resulted in greater responses to PTH (6-12 pmol g-1). Vitamin D3 (most likely after conversion to 1,25(OH)2D3) had a direct stimulatory effect on Ca2+ transport in isolated skins after three daily doses of 500 microgram of D3. Calcitonin also stimulated Ca2+ influx in both intact frogs (24 pmol g-1) and isolated skins (25-100 pmol ml-1). We conclude that parathyroid hormone, facilitated by vitamin D, stimulates Ca2+ influx in the skin of R. pipiens. We also conclude that calcitonin is stimulatory for cutaneous Ca2+ influx in this species.

Active calcium ion transport Xenopus laevis skin.

The skin of intact, free-swimming Xenopus laevis transports Ca2+ inwardly in a manner that is proportional to the external [Ca2+] up to about 0.3 mmol.l-1, saturates above 0.3 mmol.l-1, and is opposed to the electrochemical gradient. Efflux is relatively constant at external concentrations between 0.016 and 0.6 mmol.l-1; net flux which is negative below 0.125 mmol.l-1 becomes positive above this external [Ca2+]. Allometric analysis suggests that both Ca2+ influx and efflux scale to the 2/3 power approximately like surface area. There were no significant differences in influx between summer and fall animals; however, efflux was greater in the fall and this resulted in a change from positive balance in the summer to negative balance in the fall. Isolated skins were shown to support a Ca2+ uptake rate of nearly 30 nmol.cm-2.h-1. The phenylalkylamine verapamil in the apical bathing solution significantly inhibited this at 25 mumol.l-1. The benzothiazepine diltiazem was also effective at 50 mumol.l-1 while the dihydropyradine nifedipine was ineffective up to 100 mumol.l-1. The inorganic ion La3+ was effective at blocking Ca2+ uptake at 300 mumol.l-1; Ni2+ was also effective at 500 mumol.l-1 but Co2+ was ineffective up to 500 mumol.l-1. These results suggest that apical calcium channels in Xenopus laevis skin have properties similar to mammalian L-channels and fish gill Ca2+ channels.

Laparoscopic splenectomy for congenital spherocytosis with splenomegaly: a case report.

The traditional method of splenectomy involves a 7- to 10-cm abdominal incision, with its attendant morbidity that includes sepsis. Recently, the laparoscopic technique has been adopted for splenectomy. Many surgeons still believe that laparoscopic splenectomy should be carried out only for idiopathic thrombocytopenia purpura and Hodgkin's disease with a normal-sized spleen. A 16-year-old girl with marked splenomegaly (spleen size for times normal and weighing 600 g) due to congenital spherocytosis underwent laparoscopic splenectomy and retrieval of the spleen through the umbilical trocar site. Preoperative arterial embolization was not used, and the operative blood loss was estimated to be only 250 mL. Her postoperative course was uncomplicated, and she was discharged on the 4th postoperative day. The operative technique is described and the advantages of laparoscopic splenectomy are discussed.