Effect of demedullation on freezing injury in hind limbs of rats

Freezing incidence and tissue loss on exposure of hind limbs of female Wistar rats to freezing mixture was reduced by demedullation 6 days prior to cold exposure (p<0.01 and p<0.001 respectively); demedullation 1 h after freezing injury had no effect on tissue loss. Noradrenaline (1 mg/kg i.p.) 5 min before exposure increased the freezing incidence in intact (p<0.05) as well as in demedullated rats (p<0.01), with no effect on tissue loss. Adrenaline (500 mg/kg i.p.) had no effect on either. A sustained fall in plasma adrenaline after demedullation leading to reduced reactivity of the blood vessels to some vasoactive agents is postulated.     

Effects of cooling on certain blood constituents in relation to reproductive behaviour in buffaloes

Forty-five healthy lactating buffaloes were taken for this study in three groups: group 1 served as control. At 11:00 and 15:00 h daily the animals in group 2 were given showers and of group 3 were sent for wallowing for half an hour each time. Blood samples were taken at 14-day intervals. The overall mean values of acid phosphatase, alkaline phosphatase, total plasma ascorbic acid and plasma proteins were 2.61, 2.87, 2.89 (KA U/100ml plasma); 4.81, 4.71, 4.51 (KA U/100 ml plasma), 1.04, 1.29, 1.41 (mg/100ml plasma) and 7.05, 6.17, 6.05 (g/100 ml plasma) in control, shower and wallow groups respectively. The different parameters of reproductive efficiency-percentage of animals coming in oestrus, days-open, duration of oestrus, percent conception rate and services per conception were 40, 60, 19.09, 20, 7 in the controlgroup; 53.33, 42, 19.46, 28.50, 4.25 in the shower group and 73.33, 38.75, 23.00, 50 and 2.00 in the wallow group respectively.     

Intramolecular conformation of puromycin in solution as studied by proton magnetic resonance

The intramolecular conformation of puromycin, a broad spectrum antibiotic, in solution has been investigated by proton magnetic resonance (PMR) spectroscopy. A comparison of the proton chemical shift and proton-proton coupling constant data of puromycin with puromycin aminonucleoside suggests that puromycin in solution exists as an equilibrium blend of extended and folded conformers. These folded conformers are the result of flexibility around the C alpha -C beta bond of the aminoacyl segment of puromycin. One of the folded conformers predicted by PMR is in excellent agreement with the x-ray data.     

Experimental support for a right-handed vertical double helix

The experimentally observed geometry of a miniature double helix of high anti (χCN fixed ? 120°) nucleic acid structure indicates substantial interstrand base stacking with little intrastrand base stacking. This geometry is consistent with the right-handed vertical double helix in which the base planes are parallel to helical axis proposed by Olson [(1977) Proc. Natl. Acad. Sci. USA 74 , 1775] from theoretical calculations. The experimental data do not agree with the left-handed model in which the base planes are perpendicular to helical axis that has been proposed by Yathindra and Sundaralingam [(1976) Nucl. Acids Res. 3 , 729]. The theoretically computed chemical shift changes for the various double-helical configurations show that for the system examined, only the vertical model can explain the experimentally observed shift trends. The melting curve for the helix–coil transition for high anti dinucleoside monophosphate has been observed for the first time. Even though the experimental data support vertical double helices when χCN is fixed at 120°, data on naturally occurring nucleic acid structures indicate that they have no proclivity to enter into vertically stabilized double-helical arrays.