Studies on the rates of water use of dwarf wheat and their relationship with potential values based on the climatological approach

Summary Field studies were conducted to assess the field evapotranspiration of dwarf wheat under semi-arid conditions of Hissar (India), and to compare the same with the values obtained by various formulae using meteorological parameters. First irrigation to the crop was given three weeks after sowing and subsequent irrigations when about 50% of the available soil moisture was depleted from the root zone. Measured quantity of water was applied according to the soil moisture deficit in the root zone.The daily rate of water use by wheat was quite low during the early part of the growth (about 2 mm per day). It increased gradually up to ear emergence and grain development (about 5 mm per day) and declined towards maturity. Potential evapotranspiration calculated by Thornthwaite formula was most unreliable for estimating evapotranspiration. Evaporation from the U.S. open pan evaporimeter gave quite closer values to the actual rates, except during maturity. Ramdas values did not show much closeness with the actual water use rates. Penman's formula gave values quite closer to the field water use rates. Consumptive use calculated by Blaney-Criddle method did not give appropriate estimate during January and February, but it exhibited much closeness during December and March. re]19750305     

The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces changes in the heme spin state of microsomal cytochrome P-450

In vitro studies on the nature of interaction of the neurotoxin MPTP with hepatic microsomal cytochrome P-450 were carried out. Spectral perturbation studies showed nitrogenous ligand type binding between MPTP and cytochrome P-450 with a peak at 423 nm and a broad trough at 400 nm. Scatchard analysis of MPTP-cytochrome P-450 binding suggested that MPTP binds to at least 2 species of cytochrome P-450--a high affinity binding species with an apparent spectral dissociation constant (Ks) of 372 microM and a low affinity species with Ks of 37.6 mM. EPR studies confirmed that MPTP is a type II substrate for the forms of cytochrome P-450 with which it interacts and causes a shift from the high spin state of cytochrome P-450 to the low spin state. MPTP is, thus, likely to be an effective inhibitor of cytochrome P-450.     

Racial differences in cardiac structure and function in essential hypertension.

OBJECTIVE--To assess racial differences in cardiac structure and function in patients presenting with previously untreated hypertension. DESIGN--Untreated black patients with hypertension were compared with untreated white patients matched for age and sex. Both groups had similar body mass indices, blood pressures, and reported duration of hypertension. SETTING--Cardiovascular risk factor clinic for outpatients. SUBJECTS--36 men and 22 women with untreated essential hypertension. MAIN OUTCOME MEASURES--Variables of heart structure and function on cross sectional and Doppler echocardiography. RESULTS--The black patients had a significantly greater interventricular septal thickness (mean 1.23 (95% confidence interval 1.14 to 1.33) v 1.09 (1.02 to 1.16) cm; P = 0.02) and posterior wall thickness (mean 1.14 (1.07 to 1.22) v 0.96 (0.88 to 1.03) cm; P = 0.001) than the white patients, although left ventricular internal diameter was not significantly different (mean 4.90 (4.68 to 5.12) v 4.82 (4.64 to 5.01) cm; P = 0.59). This resulted in a significantly greater left ventricular mass index (mean 151 (137 to 164) v 120 (107 to 133) g/m2; P = 0.001) and relative wall thickness (mean 0.47 (0.43 to 0.51) v 0.40 (0.37 to 0.42) cm; P = 0.004) in the black patients. Comparison of Doppler measures of left ventricular diastolic function showed a significantly longer isovolumic relaxation time in black patients (mean 107 (98 to 116) v 92 (83 to 101) ms; P = 0.02) compared with white patients, although peak early to atrial filling ratios were similar in both groups (mean 1.14 (0.95 to 1.32) v 1.04 (0.94 to 1.15); P = 0.37). CONCLUSION--Among previously untreated hypertensive patients, black subjects compared with white subjects have significantly higher left ventricular mass index and relative wall thickness, as well as more impairment of left ventricular function during diastole.