Tiliqua scincoides: temperature-sensitive units in lizard brain.

Extracellular action potentials were recorded from units in the preoptic area of the brain of the Australian blue-tongued skink (Tiliqua scincoides) during periods of local heating and cooling of the brain (20 degrees to 36 degrees C) with water-perfused thermodes. In this temperature range most spontaneously firing neurons were temperature-insensitive, but eight showed sensitivity to the thermal stimulus. Five warm neurons increased their activity when the brain temperature was raised, and three cold neurons showed increased activity with fall in temperature.

Mechanism of exercise-induced ocular hypotension.

PURPOSE: Although acute dynamic exercise reduces intraocular pressure (IOP), the factors that provoke this response remain ill-defined. To determine whether changes in colloid osmotic pressure (COP) cause the IOP changes during exercise, standardized exercise was performed after dehydration and hydration with isosmotic fluid. METHODS: Progressive cycle ergometer exercise to volitional exhaustion was performed after 4 hours' dehydration, and after hydration with 946 ml isosmotic liquid (345 mOsM). In each experiment, venous blood taken before and immediately after exercise was analyzed for hematocrit, plasma protein concentration, total plasma osmolality, and plasma COP. RESULTS: Exercise in both experiments significantly reduced IOP and elevated COP (each P < 0.01). Dehydration, compared with hydration, also significantly reduced IOP and elevated COP, when measured before and after exercise (P < 0.05). The correlation of mean IOP with mean COP, over the entire range created by varying exercise and hydration statuses, was statistically significant (r = -0.99; P < 0.001). In contrast, other indexes of hydration status, including hematocrit, total plasma osmolality, and plasma protein concentration, failed to change as IOP changed and failed to correlate with IOP, on either a group or individual basis, in conditions of varying levels of exercise and hydration. CONCLUSIONS: Acute dynamic exercise and isosmotic fluid ingestion each seem to change IOP through changes in COP.

Regulation of intraocular pressure after water drinking.

PURPOSE: Acute oral water loading transiently elevates intraocular pressure (IOP) via mechanisms that remain unexplained. We tested the possibilities that water drinking might elevate IOP by creating a blood-aqueous osmotic gradient, or that it might instead alter active ion pumping and the formation of aqueous humor. METHODS: In the first series, 16 young, healthy individuals were studied during dehydration and for 1 hour after rehydration (14 mL H2O/kg body weight). Hematocrit, total plasma osmolality, and plasma colloid osmotic pressure were determined simultaneously with measurements of IOP. In a second series (N = 16), rehydration occurred after pretreatment with either placebo or a topical carbonic anhydrase inhibitor (1 drop 2% dorzolamide in each eye, 12 and 2 hours before oral water loading). RESULTS: In both series, mean IOP increased significantly 15 minutes after water ingestion and remained elevated above baseline for 45 minutes. In contrast, colloid osmotic pressure and hematocrit were unaltered by water drinking, and neither these variables nor total plasma osmolality correlated with IOP. In the second series, pretreatment with dorzolamide reduced baseline IOP, but failed to alter the magnitude or time course of IOP elevations induced by water drinking. CONCLUSION: Because water drinking failed to create a blood-ocular osmotic pressure gradient, neither vitreous hydration nor increased aqueous ultrafiltration can explain increases in IOP after acute hydration. Because the increase in ocular tension apparently also is independent of active bicarbonate pumping, factors affecting aqueous drainage must explain the water drinking effect.

Measurement of the transverse beam spin asymmetry in elastic electron-proton scattering and the inelastic contribution to the imaginary part of the two-photon exchange amplitude.

We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A( perpendicular), at two Q2 values of 0.106 and 0.230 (GeV/c)(2) and a scattering angle of 30 degrees

Evidence for strange-quark contributions to the nucleon's form factors at Q2=0.108 (GeV/c)2.

We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q(2)=0.108 (GeV/c)(2) and at a forward electron scattering angle of 30 degrees p)=[-1.36+/-0.29(stat)+/-0.13(syst)]x10(-6). The expectation from the standard model assuming no strangeness contribution to the vector current is A(0)=(-2.06+/-0.14)x10(-6). We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G(s)(E)+0.106G(s)(M)=0.071+/-0.036 at Q(2)=0.108 (GeV/c)(2). We again find the value for G(s)(E)+0.106G(s)(M) to be positive, this time at an improved significance level of two sigma.

[Etiology and clinical course of bacterial endocarditis, 1971-1980]. / Atiologie und Verlaufsbeobachtung bei bakterieller Endokarditis 1971-1980.

Etiology and clinical course of infective endocarditis were analyzed in 31 patients seen at this institution between 1971 and 1980. The follow-up period averaged 60 (1-180) months. The infection relapsed 9 times (relapse rate 31-38%). The etiologic agent isolated from blood cultures in 26/42 infective episodes. Penicillin-sensitive streptococci were by far the most frequent cause of infective endocarditis (46%), followed by Staphylococcus aureus in 23%. A predisposing cardiac lesion existed in 26/31 patients (84%), aortic valve disease and a prolapsing mitral valve being the most frequent. In the 31 patients there were 5 deaths, 2 of which occurred acutely within a few days following the onset of endocarditis (mortality rate 6%), 2 suddenly after completion of antimicrobial therapy and 1 from another cause during the observation period. Surgery was necessary in 18 patients, emergency valve replacement being required in 3 cases (10%). In 15 patients (52%) cardiac surgery was performed electively after healing of the endocarditis. The indication for surgery was onset of heart failure due to valvular incompetence in 16 patients and recurrent systemic embolization in 2 patients. All patients survived surgery. At restudy no difference was observed in overall cardiac function, physical working capacity and employment activities among the surviving patients whether operated upon or not.

Measurement of strange-quark contributions to the nucleon's form factors at Q(2) = 0.230 (GeV/c)(2).

We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a Q2 of 0.230 (GeV/c)(2) and a scattering angle of theta (e) = 30 degrees - 40 degrees. Using a large acceptance fast PbF2 calorimeter with a solid angle of delta omega = 0.62 sr, the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A(phys)=(-5.44+/-0.54(stat)+/-0.26(sys))x10(-6). The standard model expectation assuming no strangeness contributions to the vector form factors is A(0) = (-6.30+/-0.43) x 10(-6). The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G(s)(E) + 0.225G(s)(M) = 0.039+/-0.034 or F(s)(1) + 0.130F(s)(2) = 0.032+/-0.028.