Schedule-induced cocaine drinking: choice between cocaine and vehicle

Rats were exposed to daily 3-hr schedule-induced polydipsia sessions (fixed-time 1-min food-pellet delivery) with two drinking fluids available: cocaine solution and water. Fluid position was alternated daily. Polydipsia occurred mostly from a preferred-side spout (position preference) until cocaine solution concentration was increased to between 0.52 and 1.04 mg/ml and animals drank mostly water. Within a lower concentration range (0.28-0.6 mg/ml) maximum session cocaine intakes ranged from 54.3 to 120.1 mg/kg. Postsession serum cocaine levels were about 200 ng/ml. At individually chosen cocaine solution concentrations, the addition of saccharin to the solution did not increase cocaine intake, but a compound solution (saccharin plus glucose) did. With progressive dilution of the compound vehicle, an almost complete preference for cocaine solution was maintained. But with a return to water as the vehicle, animals reverted to a position preference after a few sessions, although one maintained a clear cocaine preference. Schedule-induced polydipsia produced chronic, oral self-administration of cocaine resulting in pharmacologically significant intakes and serum levels.     

A treadmill test of sprint running

Anaerobic power is characterized by a high degree of specificity regarding both the recruited muscles as well as the recruitment pattern. The popular Wingate Anaerobic Test (WAnT) is a cycling test that does not satisfy the need for a running-specific anaerobic test. We describe such a test, using a novel type of a commercially available treadmill (BRL 1800, Gymrol, France). The ergometer is equipped with a torque motor to neutralize the frictional resistance of the treadmill belt, and a hip-belt harness connected to a horizontal rod. Force applied to the harness is monitored by a strain gauge mounted on the rod, while vertical movement is monitored by a potentiometer at the posterior fixed end of the rod. These, in conjunction with the treadmill belt speed, enable the computation of horizontal and vertical power as well as the combined total output. Power is calculated both as 'peak' power (highest 2.5 s segment) and 'mean' power (20 s duration). Preliminary results of young athletes were generally consistent with the expected age-related changes in anaerobic power. Values obtained on the anaerobic treadmill were always higher than the corresponding WAnT values previously obtained in comparable age groups. The higher values were probably due to the larger muscle mass involved and the shorter peak and mean power durations (2.5 and 20 s versus 5 and 30 s in the WAnT, respectively). This test should enable not only running-specific anaerobic power monitoring but also the characterization of the relationship between the horizontal and vertical components of that power.     

Thoraskopische Koronarchirurgie

Thorascopic coronary surgery has achieved great progress in the past few years. After computer-directed instrument systems were introduced, which enabled high precision and expanded mobility in close quarters, the limitations of conventional endoscopic instruments were largely overcome. Employing modern surgical telemanipulators and endoscopic stabilizers, entirely endoscopic myocardial revascularization of the anterior wall is being successfully performed during off-pump surgery. Longer operating times and conversion rates in about one-fifth of the patients due to technical and anatomical limitations still restrict the use of these new surgical techniques compared to conventional surgery. Development of further technologies and integration of video-assisted navigation systems will broaden the application of computer-assisted instrument systems in the near future.     

A prospective survey of neuroleptic malignant syndrome in a short-term psychiatric hospital

Of 1,470 patients treated with neuroleptics during 1 year at a private psychiatric hospital, only one patient developed neuroleptic malignant syndrome--an annual frequency of 0.07%. Use of low doses of neuroleptics may account for this frequency, which is below recent estimates.     

M protein and protein F act as important determinants of cell-specific tropism of Streptococcus pyogenes in skin tissue.

The pathogenic gram-positive bacterium Streptococcus pyogenes (group A streptococcus) causes numerous diseases of cutaneous tissue, each of which is initiated after the interaction of the bacterium with the cells of the epidermis. In this study, we show that different surface proteins of S. pyogenes play important roles in determining the cell-specific tropism of the bacterium in skin. Using streptococcal strains with defined mutations in the genes which encode surface proteins in combination with primary cultures of human skin and an in situ adherence assay which uses histological sections of human skin, we show that the M protein of S. pyogenes mediates the binding of the bacterium to keratinocytes, while a second streptococcal surface protein, protein F, directs the adherence of the organism to Langerhans' cells. Characterization of binding revealed that adherence was inhibited by purified streptococcal proteins and pretreatment of both host cells with the protease trypsin. Adherence was only slightly affected by the state of keratinocyte differentiation in vitro, but was considerably modulated in response to environmental conditions known to regulate expression of M protein and protein F, suggesting that the interaction between these bacterial cell-surface structures/adhesins and keratinocytes and Langerhans' cells may play an important role in streptococcal skin disease.     

The effects in the rat of two fragments of parathyroid hormone-related protein on uterine contractions in situ.

Synthetic parathyroid hormone fragment PTH(1-34) has been reported recently to inhibit uterine contractions stimulated by a variety of agonists. We have studied the effect in this system of the parathyroid hormone-related protein fragment PTHrP(1-34) which shows 60% homology with PTH over the first thirteen amino acid residues. The effects of two different PTHrP fragments on acetylcholine-stimulated uterine contractions in vitro were studied. Whereas synthetic hPTHrP(75-86 amide) (10(-9)-10(-7) M) was without effect, synthetic hPTHrP(1-34) (10(-9)-10(-7) M) was capable of inhibiting, in a dose-related fashion, uterine muscle contractions precontracted with 10(-6) M-acetylcholine. In a second series of experiments the bovine PTH(3-34) fragment itself was shown to have no stimulatory effect on acetylcholine-stimulated contractions. Also this fragment in an equimolar concentration (10(-7) M) failed to antagonize the effects of PTHrP(1-34) on acetylcholine-stimulated uterine contractions. However, a 100-fold excess molar concentration of bPTH(3-34) (10(-6) M) completely abolished the inhibitory action of hPTHrP(1-34) (10(-8) M) on acetylcholine-stimulated uterine contractions. These results clearly show that the inhibitory action of PTH(1-34) and PTHrP(1-34) on uterine contractions depends on the integrity of the amino-terminal region of the molecule.